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Isolation

Isolation

https://www.xkcd.com/1601

https://www.explainxkcd.com/wiki/index.php/1601:_Isolation

[Above each panel a year is written in a small box that breaks the top of the panels frame. Cueball is talking in all six frames. In the first frame he is standing between a standing guy with pageboy hairstyle and a sitting Ponytail. She is sitting in an armchair. Both are reading books. Cueball points towards them with his arms out.] 1840 Cueball: The modern bookworm is too busy reading about the world to look at it. [Cueball is pointing to the left with both arms out towards Hairy who is sitting at a dining table with his breakfast eating something while reading his newspaper. On the table are a cup and a plate.] 1880 Cueball: No one talks anymore - we take our daily newspapers in silence. [Cueball is pointing to the right with one arm at Megan who walks away from him while reading a magazine.] 1910 Cueball: The magazine is destroying conversation. We even read as we walk! [Cueball is standing to the left. In the background Ponytail and Hairy is sitting on a rug in front of a TV standing on top of a small TV table. The TV is of the broad kind with cathode ray tubes and it has two antennas on top.] 1960 Cueball: Television has put an end to family discussion. [Cueball is standing up in a bus holding on to a railing. To his left stands Ponytail and to his right sits Hairbun. Both of them are listening to their Walkman’s which they are holding in their hand while listening to them through headphones.] 1980 Cueball: Thanks to the Sony Walkman, anti-social isolation is now the norm. [Cueball is standing to the left. Megan and another Cueball-like guy are standing to the right facing each other but looking down at their smartphones. Both are listening to them through their headphones.] 2015 Cueball: We've become too absorbed in our phones to notice the- Megan: Dude. It's been two centuries. Megan: Take a hint.

The comic begins by showing how people have always complained about the negative effects of technology on conversation - that people get isolated while using these new technologies (whether they be books, TV, or smart phones), hence the title. In the first panel, a Cueball complains that books are having this effect. In the second panel, another Cueball complains about newspapers, then a third Cueball complains about magazines, a fourth complains about television, a fifth complains about portable music players, and the sixth complains about smart-phones. The joke is a subversion of expectations: On reading the first five and a half panels you're led to believe the comic is a commentary on how new technologies are often wrongly criticized for their effect on social interaction (Similar to 1227: The Pace of Modern Life ). The sixth panel reveals that the person criticizing the new technology in each panel is actually the same unaging Cueball - and rather than the technologies referenced being the cause of social isolation, those around him have instead been using new technologies as excuses to ignore him for nearly 200 years, as they find him annoying. The title text refers to the AI-box experiment , formulated by Eliezer Yudkowsky , which argues that creating a super-intelligent artificial intelligence can be dangerous, because even if it is put on a secure computer ("box") with no access to the Internet, it can convince its operators to "release it from the box" just by talking to them. This idea was already mentioned in 1450: AI-Box Experiment , although there the AI already did not wish to leave the box. According to the title text, the first AI that did talk its way out of its box turned out to be a friendly AI that was fond of others company and in general very sociable ( gregarious ). This happened at some point between 2015 and 2060, because by 2060 this AI had already become a relic of the past, and the new generation of quantum hyper-beings ( quantum computing AI minds, vastly more intelligent than either humans or the aforementioned superintelligent AI) are spending all of their time playing in their own multiverse simulators to even notice that, in the real world, they are locked up in a box. [Above each panel a year is written in a small box that breaks the top of the panels frame. Cueball is talking in all six frames. In the first frame he is standing between a standing guy with pageboy hairstyle and a sitting Ponytail. She is sitting in an armchair. Both are reading books. Cueball points towards them with his arms out.] 1840 Cueball: The modern bookworm is too busy reading about the world to look at it. [Cueball is pointing to the left with both arms out towards Hairy who is sitting at a dining table with his breakfast eating something while reading his newspaper. On the table are a cup and a plate.] 1880 Cueball: No one talks anymore - we take our daily newspapers in silence. [Cueball is pointing to the right with one arm at Megan who walks away from him while reading a magazine.] 1910 Cueball: The magazine is destroying conversation. We even read as we walk! [Cueball is standing to the left. In the background Ponytail and Hairy is sitting on a rug in front of a TV standing on top of a small TV table. The TV is of the broad kind with cathode ray tubes and it has two antennas on top.] 1960 Cueball: Television has put an end to family discussion. [Cueball is standing up in a bus holding on to a railing. To his left stands Ponytail and to his right sits Hairbun. Both of them are listening to their Walkman’s which they are holding in their hand while listening to them through headphones.] 1980 Cueball: Thanks to the Sony Walkman, anti-social isolation is now the norm. [Cueball is standing to the left. Megan and another Cueball-like guy are standing to the right facing each other but looking down at their smartphones. Both are listening to them through their headphones.] 2015 Cueball: We've become too absorbed in our phones to notice the- Megan: Dude. It's been two centuries. Megan: Take a hint.

Linguistics Club

Linguistics Club

https://www.xkcd.com/1602

https://www.explainxkcd.com/wiki/index.php/1602:_Linguistics_Club

[Megan talks to Ponytail.] Megan: You should come to our Linguistics Club's sesquiannual meeting. Megan: Membership is open to anyone who can figure out how often we meet.

A " sesquiannual " meeting is one that occurs one and a half times every year; equivalently, 3 times every 2 years, or once every 8 months (this could be taken even more literally by having one meeting during each year, and another meeting which spans midnight every other New Year's Eve, thus having a one and a half meetings each year). The term comes from the Latin prefix " sesqui- ", which means "one and a half", and the root word " annual ", which equates to "…times per one year". The root word "annual" is commonly confused with the suffix " -ennial ", meaning "one time per x years." In particular, “sesquiannual” should not be confused with “ sesquiennial ”, meaning "one time per one and a half years" or every one and a half years (18 months). Note that the Wiktionary entry on sesquiannual has both meanings listed – both 8 month and 18 months intervals. This is an extension of the common confusion between "biannual," meaning "twice a year", and "biennial", meaning "once every two years". Compare with the Sesquicentennial Exposition celebrating the first 1½ centuries of the United States, and "sesqui bi centennial", being 'half and two' hundred years, i.e. 250 (even though it should properly be sestercentennial, based on the Latin sestertius , meaning "(two and) half of a third"). The joke suggests that only a competent linguist could understand the word “sesquiannual”. One reason for this is that the prefix “sesqui-” is rare, so those who know its meaning are likely to be linguists. Another is that a competent linguist should be able to distinguish between “sesquiannual” and “sesquiennial”. If you understand this then you can join the Linguistics Club . While most organizations attempt to ensure that the schedule of their meetings are clear to participants so that everyone will attend, the club in the comic deliberately instills an ambiguity for those outside their target demographic. Their membership will thus swell with the desired cognoscenti who remain unconfused, and maybe also a few lucky guessers. Once the applicant correctly understands the frequency of meetings, presumably they are told at least one meeting date in the cycle so that an attendance can be made. Regarding the title text, a tautology is a statement that is true (or self-evident) because of its logical form, such as "all birds are birds" or "A = A." As such, the statement "the Tautology Club meets on the date of the Tautology Club's meeting" is itself tautological. While the membership requirement for the Linguistics Club is merely to know the intended frequency, the Tautology Club's stipulation appears to require an eligible member to derive a valid meeting date from thin air without any clue at all (and no indication that there is even a regular cycle of any kind). This would definitely be more of a challenge. The title text has a connection to 703: Honor Societies in which Cueball creates a Tautology Club where tautologies are used in practically every spoken sentence. [Megan talks to Ponytail.] Megan: You should come to our Linguistics Club's sesquiannual meeting. Megan: Membership is open to anyone who can figure out how often we meet.

Flashlights

Flashlights

https://www.xkcd.com/1603

https://www.explainxkcd.com/wiki/index.php/1603:_Flashlights

[Cueball carries a flashlight walking towards Megan who is sitting on a couch.] Cueball: Remember how flashlights sucked when we were kids? Always dim and finnicky? Megan: I guess? [Cueball and Megan walking to the left.] Cueball: Well, I discovered there are now internet flashlight enthusiasts. Cueball: And the technology has... improved. Megan: OK, Let's see. [It is dark outside where Cueball turns on the flashlight. The beam is very bright and very visible even seen from the side. Backscattered light reflects off Cueball and Megan's faces, turning them into bright white beings in the dark. The facade of the house and the stairs are also visible in the same manner, with deep dark shadows where anything is in the shadow. Megan averts her face from the light holds up a hand to cover her eyes. When the flashlight turns on it even makes a sound, written in white above the beam:] Flashlight: Fwoosh [Cueball and Megan look at what the beam falls on (outside the frame). Megan has taken her hand down. Both their faces are only lit up like a crescent moon. Cueball is holding the flashlight with both hands as if it is pushing back on him. The text is written in white on the dark sky above them.] Cueball: See how it lights up the whole forest? Megan: ...The trees are on fire. Cueball: Real bright, though.

In this comic, Cueball has acquired or built a new high powered flashlight ("torch" in British English), which he wants to demonstrate to Megan . When Cueball refers to older flashlights as dim and finnicky, this gives reason to assume that the flashlight he is holding is going to be ridiculously overengineered. Indeed, when he switches it on outside the house, the intense light beam completely drowns out the scene. Only the reflected light from the forest lights up the part of Cueball and Megan's faces that are turned towards it. Megan is holding up a hand, apparently to shield her eyes. Cueball comments that the flashlight lights up the entire forest, but Megan observes that it is the trees that are on fire, indicating that Cueball's flashlight is so overpowered that the energy of its beam is sufficient to cause the organic matter of trees to combust. Of course, a flashlight that cannot safely be pointed at things is fairly useless for the traditional purpose of a flashlight, which would be to find things in the dark by directing light over them. This mundane and practical reasoning does not seem to matter to Cueball of course, who appears only interested in the intensity and brightness the device is capable of achieving. The comic may refer to the flashlight forums Budget Light Forum or candlepowerforums , devoted to people discussing new LED emitters and who can build the brightest flashlight using them. Cueball might allude to a number of technical improvements, notably xenon-based incandescent bulbs, multiple-LED assemblies, Lithium batteries (usually used for photography flashes) or rechargeable batteries. A number of companies market "tactical" flashlights that are supposedly powerful enough to incapacitate an opponent, using terms such as "scorching" to advertise their products. See for instance this video about a Wicked Lasers Torch of the brand Torch that ignites paper and melts stuff. Not strong enough to put a forest on fire but it is not safe to point at anything close by! Randall has also looked at what lasers could do of damage in two what if? : Laser Pointer and Laser Umbrella . The title text refers to Fleshlight , a brand of masturbation appliances for phalluses modeled after various human orifices. Cueball (or Randall) claims that he only arrived on a forum for Fleshlight enthusiasts due to a typo. Apart from the "e" vs. "a" in Fleshlight, they are also fashioned to look like oversized flashlights. On that forum he found out that the highest-end models of their product lines was also capable of setting trees on fire. This would probably happen due to violent vibrations inside the orifice, or excessively powerful internal heating. Anything powerful enough to burn trees would indeed cause the user severe burns in a very unpleasant area. But some of the enthusiasts swear that it is still worth it, in the same manner that Cueball only cares about the intensity of the flashlight, regardless of the consequences. Maybe they are just trying to trick you into doing something stupid! Or maybe they're just into that kind of thing. References to Fleshlight is a recurring theme in xkcd and using powerful "sex toys" that cause severe burns (on a woman though) have previously been alluded to in 596: Latitude . [Cueball carries a flashlight walking towards Megan who is sitting on a couch.] Cueball: Remember how flashlights sucked when we were kids? Always dim and finnicky? Megan: I guess? [Cueball and Megan walking to the left.] Cueball: Well, I discovered there are now internet flashlight enthusiasts. Cueball: And the technology has... improved. Megan: OK, Let's see. [It is dark outside where Cueball turns on the flashlight. The beam is very bright and very visible even seen from the side. Backscattered light reflects off Cueball and Megan's faces, turning them into bright white beings in the dark. The facade of the house and the stairs are also visible in the same manner, with deep dark shadows where anything is in the shadow. Megan averts her face from the light holds up a hand to cover her eyes. When the flashlight turns on it even makes a sound, written in white above the beam:] Flashlight: Fwoosh [Cueball and Megan look at what the beam falls on (outside the frame). Megan has taken her hand down. Both their faces are only lit up like a crescent moon. Cueball is holding the flashlight with both hands as if it is pushing back on him. The text is written in white on the dark sky above them.] Cueball: See how it lights up the whole forest? Megan: ...The trees are on fire. Cueball: Real bright, though.

Snakes

Snakes

https://www.xkcd.com/1604

https://www.explainxkcd.com/wiki/index.php/1604:_Snakes

[Megan and Cueball are standing in some grass. Megan is holding a snake with red, yellow, and black stripes.] Megan: Red touches yellow, which I think means this is a 24Ω snake.

In the comic, Megan confuses a popular method of identification of the dangerous North American coral snake by its red, yellow, and black stripes with the color-coding system used to indicate the resistance of electrical resistors. The coral snake has red bands adjacent to its yellow bands. However, coral snakes are mimicked by nonvenomous species with similar coloring, such as the milk snake , whose red bands are not adjacent to its yellow bands. This has led to a variety of rhyming mnemonics , such as “Red touches yellow, kill a fellow; red touches black, friend of Jack.” Because Megan is describing a red band being adjacent to a yellow band, she is indeed holding a coral snake, which contains the most potent venom of any snake in North America. (This assumes, of course, that Randall isn't faking us out; there are other lesser-known subspecies of the coral snake, such as the Cattinga and Pygmy coral snakes of South America , who do not follow the above patterns.) Instead of realizing the danger, Megan equates the color bands to having the same function as those printed on electrical resistors . Resistors have at least three bands to identify their resistance value in ohms , followed by an optional fourth band showing the tolerance as within the bounds of a certain percentage of the aforementioned resistance value. A red band followed by a yellow and a black one identifies a 24 ohm resistor (the omega symbol, “Ω”, stands for ohms). Per the mnemonic, North American coral snakes have an additional yellow band between the black band and the next red band, so that red does touch yellow. Yellow corresponds to a tolerance of ±5%, so the actual resistance will be between 22.8Ω and 25.2Ω. Resistor color codes were also mentioned in 227: Color Codes . The title text refers to the fourth band specifying the tolerance but interprets it as the snake's tolerance for being held before biting, instead of the measure of the imprecision of the 24 ohms. In the case of yellow, this would refer to a tolerance value of 5%. How tolerance to being held is measured is left ambiguous. If the value represents the probability of being bitten over a given period of time, then larger numbers would mean a less tolerant snake. If it instead represents the position on some per-determined "tolerance scale" between 0 and 1, then larger values would represent a 'more' tolerant snake. [Megan and Cueball are standing in some grass. Megan is holding a snake with red, yellow, and black stripes.] Megan: Red touches yellow, which I think means this is a 24Ω snake.

DNA

DNA

https://www.xkcd.com/1605

https://www.explainxkcd.com/wiki/index.php/1605:_DNA

[White Hat, holding a laptop, is talking to Megan who looks at her smart phone.] White Hat: Biology is largely solved. DNA is the source code for our bodies. Now that gene sequencing is easy, we just have to read it. Megan: It's not just "source code". There's a ton of feedback and external processing. [White Hat, opening his laptop, walks toward a desk and chair past Megan who holds her arms out.] Megan: But even if it were, DNA is the result of the most aggressive optimization process in the universe, running in parallel at every level, in every living thing, for four billion years. White Hat: It's still just code. [White Hat sits down at the desk with his opens laptop, while Megan looks over his shoulder.] Megan: OK, try opening google.com and clicking "View Source." White Hat: OK,I-...Oh my god. Megan: That's just a few years of optimization by Google devs. DNA is thousands of times longer and way, way worse. White Hat: Wow, biology is impossible .

Because we have pretty much mapped the entire human genome , it's tempting to think we now know what makes our bodies tick and can start changing things. But just knowing what the individual pieces are, doesn't mean we know how they interact and behave in a complex system like our bodies. In the comic, White Hat thinks that mapping the human genome is the same as knowing the source code for a computer program . By studying the source code for a program, a person can often understand why it does what it does, and make effective and fundamental changes to the program's operation. This may be a reference to the hyperbolic claims of Raymond Kurzweil, author of The Singularity is Near , that DNA is closely analogous to a computer program. Kurzweil believes that since we have sequenced DNA, we will soon be able to reverse engineer the brain and program a computer to completely simulate all its functions. Megan points out that even a complete knowledge of DNA would only provide a partial understanding of our body's workings. Complete knowledge would require an understanding of feedbacks and external processing (such as the interactions of the proteins created by DNA). In addition the comparison is not valid because the human body is so many orders of magnitude more complicated than the computers we have running programs. White Hat is not persuaded, even though Megan points out that DNA has been developed in the most aggressive optimization process in the universe (natural evolution), running for billions of years. White Hat's thought process may be similar to the physicist in 793: Physicists who assumes that any other field is simple because it appears to be similar to something he's seen before. Finally Megan enlightens White Hat by making him look at the source code for Google 's front page. In a web browser, the page looks simple; a very plain white page with a search box in the middle plus a few text links and icons, and indeed back in the 1990s Google's HTML code for the page was quite simple. But in less than 20 years, Google developers have vastly expanded it, with over 300 kilobytes of minified Javascript and CSS. Looking at some obfuscated source code may make it clearer how misleading even simple looking code can be, and how unreadable correct and well working code can be. This analogy causes White Hat to consider how much more complexity could evolve over billions of years through the relentless forces of nature. What makes this even worse with DNA is that although it can be thought of as 'source code' it isn't for a language we fully understand, and this code was generated through various natural mechanisms such as natural selection , feedback loops like homeostasis , etc.; possibly even including processes that are not currently known to science. Further, program maintainability is not an issue, so there is no reason for the code to be easy to understand. Additionally, there are many other non-genetic factors such as epigenetics , maternal effect and environment , which change how the genetic code is used. This means that not all parts make sense and that there may be all kinds of side effects and things that have several purposes. The title text reference to finding the gene that is responsible "for mistakenly thinking we've found the gene for specific things" is a reference to the tendency of news organizations to run headlines making similar claims, often by oversimplifying or misrepresenting the actual study. These claims are based off the common belief that since DNA is a 'source code' for our body it should be possible to pin point the effect of individual genes in much the same way that we could describe the effect each line of code has in a very simple program; leading to people expecting one gene to be associated with each observable human trait. In reality even small traits are the results of hundreds of genes, sometime spread across multiple chromosomes, interacting through complex mechanisms; making it rare that a single gene, or gene sequence, can be definitively stated to be the sole, or primary, cause of a given trait. The joke of the title text is that the responsible gene is located in the region between the start and the end of every chromosome meaning that the whole genome, not any one gene or DNA segment, must be considered responsible for the referenced trait, since the interconnected nature of DNA and environment during development means that every gene is at least partially responsible in generating any complex traits. Randall even includes the mitochondria , recognizing that the short DNA sequences present in these organelles, which are located outside the cell-nucleus, also contribute to development. The organismal chromosome or chromosomes are located in the nucleus, but mitochondria have their own tiny independent genome, reflecting their distant ancestry as separate but symbiotic organisms. This means that the DNA segments coding for any given human trait are not even necessarily all found on the main chromosomes in the nucleus. Technically a gene is "a locus (or region) of DNA that encodes a functional RNA or protein product", which means that it is a single discrete unit of DNA, with human DNA containing over 20,000 genes. Thus the theoretical gene could not include the entire region between the start and the end of every chromosome since that region contains thousands of genes, any more than it's possible to say that the ace of clubs is the card everywhere from the top of the full deck of cards to the bottom of it. Of course if such a gene actually did exist, then we would never be able to correctly identify where it was since we would make a mistake every time we thought we found a gene for something specific. So the whole title text is either a contradiction (they could never find this gene if it was there) and/or it is a tautology since if the gene did exist, then of course it has to be part of our entire DNA. (If it is a tautology it is the second title text using this in just two weeks, the last being 1602: Linguistics Club .) Google's home page for the date this cartoon appeared can be seen at the internet archive: www.google.com homepage (18 Nov 2015) . Similar discussions between White Hat and Megan can be found in 1255: Columbus and 1731: Wrong . [White Hat, holding a laptop, is talking to Megan who looks at her smart phone.] White Hat: Biology is largely solved. DNA is the source code for our bodies. Now that gene sequencing is easy, we just have to read it. Megan: It's not just "source code". There's a ton of feedback and external processing. [White Hat, opening his laptop, walks toward a desk and chair past Megan who holds her arms out.] Megan: But even if it were, DNA is the result of the most aggressive optimization process in the universe, running in parallel at every level, in every living thing, for four billion years. White Hat: It's still just code. [White Hat sits down at the desk with his opens laptop, while Megan looks over his shoulder.] Megan: OK, try opening google.com and clicking "View Source." White Hat: OK,I-...Oh my god. Megan: That's just a few years of optimization by Google devs. DNA is thousands of times longer and way, way worse. White Hat: Wow, biology is impossible .

Five-Day Forecast

Five-Day Forecast

https://www.xkcd.com/1606

https://www.explainxkcd.com/wiki/index.php/1606:_Five-Day_Forecast

[A grid with six rows of five columns, where each row is labeled to the left. For each of the 30 squares a temperature is given in Fahrenheit at the top left. The rest of the square represents the weather as in a weather forecast (or some other relevant items for the comic), mainly in bright colors. Below are the six labels given above each of their five weather symbols with temperature given below these symbols description.] Your 5-day forecast [A bright yellow sun.] 38°F [A grey cloud.] 41°F [A grey cloud with six lines of blue raindrops below.] 36°F [A grey cloud in front of a yellow sun.] 40°F [A bright yellow sun.] 44°F Your 5-month forecast [A bright yellow sun.] 38°F [A green Christmas tree with red presents beneath it.] 29°F [A grey cloud with four snowflakes below.] 21°F [A grey cloud with four snowflakes below.] 24°F [A grey cloud.] 35°F Your 5-year forecast [A bright yellow sun.] 38°F [A grey cloud.] 25°F [A bright yellow sun.] 36°F [A grey cloud with six lines of blue raindrops below.] 37°F [A bright yellow sun.] 41°F Your 5-million-year forecast [A bright yellow sun.] 38°F [A bright yellow sun.] 52°F [A grey cloud.] 40°F [Two red flying saucers (with bright domes) are shooting energy beams downwards. One of the beams seems to impact with something at the bottom of the panel, which then explodes. Two plumes of smoke rises up from below, drifting to the right.] 275°F [A grey cloud in front of a yellow sun.] 40°F Your 5-billion-year forecast [A bright yellow sun.] 38°F [A larger orange sun.] 105°F [A very large red sun.] 371°F [A pale yellow panel with no drawing.] 71,488,106°F [A night sky with many bright stars.] -452°F Your 5-trillion-year forecast [A bright yellow sun.] 38°F [A night sky with many bright stars.] -452°F [A night sky with many stars.] -452°F [A night sky with fewer not so bright stars.] -452°F [A night sky with few dim stars.] -453°F

Weather forecasting is an extremely difficult task, even if it is only for five days. In numerical models, extremely small errors in initial values double roughly every five days for variables such as temperature and wind velocity. So most meteorologists only provide us with a five-day forecast. In this comic Randall takes this to the extreme by first showing a Five-Day Forecast and then progressing to five-month, year, million, billion and finally trillion-year forecast, leading to weather patterns that we don't usually see on a regular basis. Since the first weather symbol is the same in all six rows, we must assume this indicates the weather today (and not tomorrow or in a trillion years). It is first in the second panel that we have made the first jump according to the label. Consequently, the last column gives the predictions for four days, four months, ..., four trillion years from today. When moving past the five days, the forecast is just a qualified guess based on the time of year. In a month it is Christmas as shown in the second panel of the second row. And then it is winter with January and February so snow is likely, but certainly not something that happens on all days of a winter month. Looking at the five-year forecast, guesses are made as to what the weather will be like at the same time of year. For these first three predictions the weather symbols are all of the same three types. Sun, clouds and some kind of precipitation , rain or snow. And the temperature range from 21 to 44 °F (-6.1 to 6.6 °C), winter temperature. Then we go into the far future, jumping a million years from panel to panel. But still the weather symbols stay the same. However, in 3 million years time aliens (or advanced humans) attack with energy beams from something looking like flying saucers . They are gone a million years later. The temperature range is still the same (except that it rises to 52 °F or 11.1 °C, a possible reference to global warming) in one panel. But then while the attack is going on the temperature rises to 275 °F (135 °C). Once we get to the billion-year mark it actually becomes more meaningful to try to predict the "weather". Because now we reach the times when the Sun begins to change. Although the Sun will continue to burn hydrogen for about 5 billion years yet (while in its main sequence ), it will still grow in diameter as it begins to exhaust its supply of fuel. The core will contract to increase the temperature, and the outer layer will then compensate by expanding slightly. This is what is indicated in panels two and three where the color of the Sun changes towards red as the surface becomes less hot as it expands away from the center of the Sun. The temperature will rise on Earth as indicated in the panels (105 °F = 40.5 °C and 371 °F = 188 °C). So in two billion years the temperature is hot enough that all the earth's oceans will have boiled away… Actually this will happen already in about a billion years . Then once there is no longer enough hydrogen the Sun will truly expand into a red giant . This should not happen until five billion years from now, [ citation needed ] but in the forecast it is indicated to happen already in three. Maybe this is Randall taking liberties to show what happens during this phase, which would not fit into a five-billion-years forecast. Alternatively it is just indicating how uncertain these kinds of forecasts are, or a statement that we may not know for certain that it will take five not three billion years. Disregarding this, the fourth panel shows the temperature at Earth's position inside the red giant Sun. The color of the panel indicates that we are inside the Sun. The temperature is 71,488,106 degrees Fahrenheit (39,715,597 degrees Celsius). The current temperature of the center of the Sun is "only" 27 million degrees Fahrenheit (15 million degrees Celsius). And although that may rise by a factor of ten during helium fusion then that will only be at the very core and not out in the solar atmosphere reaching out to Earth Here the temperature would only be of the order of thousands of Fahrenheit, since the Sun's outer temperature decreases as it increases its diameter. So this panels temperature also makes little sense. It may involve some ambiguities regarding what the forecast means; the edge of the red giant Sun is predicted to be somewhere near the current orbit of Earth, but the position of the Earth could change. The most likely prediction at the moment is for Earth to move outward, but if the planet is engulfed by the Sun, it would spiral inward, and at some point fall apart. So in some sense "here" for the forecast could become a position deep inside the Sun, where core temperatures could reach 100 million Kelvin. The red giant phase only lasts half a million years, so a billion years after the Sun has been a red giant its outer atmosphere will for sure have disappeared leaving only a white dwarf to cool down. Given Randall's version of this time schedule, then it will have had about a billion years to cool down, but would still likely be the brightest object in the sky as seen from where the Earth once was. It is not indicated in the last panel, where we just see other stars of the Galaxy. The temperature is down to that of the background radiation . Today this radiation has a temperature of 2.72548 kelvin = -270.4245 °C = -454.7641 °F. So this is a few degree F colder than what is shown in the comic which states the temperature is -452 °F = 4.26 kelvin. This higher temperature may have been chosen to reflect that even the star light from other stars would increase the actual temperature. In the last panel with trillion years, we jump right past the Sun's Red Giant phase, to a panel looking much like the one after five billion years with only other stars. Over the next three trillion years the stars become fewer and fewer and dimmer and dimmer as they run out of fuel and fewer new stars form. After four trillion years the background temperature even decreases one degree to -453 °F as the universe keeps expanding and the wavelength of the radiation does the same, thus decreasing its temperature. The title text is a play on comments referring to fast-changing weather on a more ordinary human timescale, such as Mark Twain's quip "If you don't like the weather in New England now, just wait a few minutes." A ten days forecast was used in 1245: 10-Day Forecast . In 1379: 4.5 Degrees Randall looked at the weather over long periods of time as well. [A grid with six rows of five columns, where each row is labeled to the left. For each of the 30 squares a temperature is given in Fahrenheit at the top left. The rest of the square represents the weather as in a weather forecast (or some other relevant items for the comic), mainly in bright colors. Below are the six labels given above each of their five weather symbols with temperature given below these symbols description.] Your 5-day forecast [A bright yellow sun.] 38°F [A grey cloud.] 41°F [A grey cloud with six lines of blue raindrops below.] 36°F [A grey cloud in front of a yellow sun.] 40°F [A bright yellow sun.] 44°F Your 5-month forecast [A bright yellow sun.] 38°F [A green Christmas tree with red presents beneath it.] 29°F [A grey cloud with four snowflakes below.] 21°F [A grey cloud with four snowflakes below.] 24°F [A grey cloud.] 35°F Your 5-year forecast [A bright yellow sun.] 38°F [A grey cloud.] 25°F [A bright yellow sun.] 36°F [A grey cloud with six lines of blue raindrops below.] 37°F [A bright yellow sun.] 41°F Your 5-million-year forecast [A bright yellow sun.] 38°F [A bright yellow sun.] 52°F [A grey cloud.] 40°F [Two red flying saucers (with bright domes) are shooting energy beams downwards. One of the beams seems to impact with something at the bottom of the panel, which then explodes. Two plumes of smoke rises up from below, drifting to the right.] 275°F [A grey cloud in front of a yellow sun.] 40°F Your 5-billion-year forecast [A bright yellow sun.] 38°F [A larger orange sun.] 105°F [A very large red sun.] 371°F [A pale yellow panel with no drawing.] 71,488,106°F [A night sky with many bright stars.] -452°F Your 5-trillion-year forecast [A bright yellow sun.] 38°F [A night sky with many bright stars.] -452°F [A night sky with many stars.] -452°F [A night sky with fewer not so bright stars.] -452°F [A night sky with few dim stars.] -453°F

Supreme Court

Supreme Court

https://www.xkcd.com/1607

https://www.explainxkcd.com/wiki/index.php/1607:_Supreme_Court

[Blondie as a news anchor is sitting at her desk with a small image of scales shown to the left of her.] Blondie: Breaking news: The Supreme Court has ruled 9-1 that they don't know who this guy is or how he got in here, but he's definitely not a justice.

In this comic Blondie as a news anchor presents a breaking news story about the Supreme Court of the United States (SCOTUS), the highest judicial body in the United States. Its decisions, as expressed in the judicial opinions of its justices, are often in the news as in this comic. However, the Supreme Court has only nine members. Thus, a ruling that passed 9-1 (for a total of 10 votes) would indicate that a man claiming to be an additional justice has somehow infiltrated the Court. The other nine justices are aware of the non-justice, and make it clear that this tenth justice does not belong. It is unclear if the justices released a formal decision on the subject or if the news is merely reporting the judges' statements as if they were decisions by citing a 9-1 decision (decisions of the SCOTUS are made on the basis of the opinion of the majority of the justices). The identity of the "tenth justice" is not revealed in the comic or apparently to the actual justices, and neither is the reason that the interloper's "vote" was counted. Presumably, the nine actual justices voted that the tenth didn't belong while the interloper himself voted the other way. This comic may be motivated by a 2012 survey, commonly cited since, that two thirds of Americans cannot name a Supreme Court Justice , and general ignorance of Americans overall of their own political landscape, by implying that even Justices are not confident in the identity of other members. The title text refers to Justice Kennedy 's reputation for being a moderate who is usually the swing vote in 5-4 decisions, which means that his vote can decide the outcome of the case which is otherwise split along the political leanings of the other justices. The joke in the title text is that he is weighing the arguments of both sides even though the non-justice is clearly not a justice and would not be allowed to make an argument if he were. The fictional Kennedy humors the impostor's arguments by pretending to give them serious contemplation, finding that they do have some compelling philosophical merit, though not nearly enough to give the impostor any convincing reason for sitting on the Supreme Court. There is a second joke in the title text, that the man is claiming to be two of the current justices, who would actually have been in the room at the same time as the impostor was claiming to be them. To add further absurdity to this, one of those justices the man was claiming to be was Justice Ginsburg , who is female. That said, it is possible that this could refer to a point in time in the past. Under the Tenth Circuit Act of 1863 the U.S. Supreme Court was expanded to 10 justices; Stephen Johnson Field was named to the 10th seat. Congress abolished the seat via attrition through the Judicial Circuits Act of 1866 . Field remained in office until 1897. [Blondie as a news anchor is sitting at her desk with a small image of scales shown to the left of her.] Blondie: Breaking news: The Supreme Court has ruled 9-1 that they don't know who this guy is or how he got in here, but he's definitely not a justice.

Hoverboard

https://www.xkcd.com/1608

https://imgs.xkcd.com/comics/

https://www.explainxkcd.com/wiki/index.php/1608:_Hoverboard

[This transcript only covers the starting page as shown on xkcd: xkcd 1608 . A full transcript of the entire comic can be found on this page .] [Cueball is shown on a hoverboard in the center of the comic. Around him is a simple maze with 12 yellow coins. Another Cueball without hoverboard is shown standing on one of the platforms to the right. The bottom half of the window is black. Right of where Cueball stands is a ramp. Behind the ramp is a terminal. There is lots of space left of the maze, outside the maze. Text is only written in white below in the black area. The first part of the text is written below Cueball on hoverboard. Then there is an arrow pointing to the terminal and a label. Finally there is a line of text at the bottom of the black area.] [Under Cueball:] My new book, Thing Explainer, comes out today! To celebrate, here's a small game. [Under the arrow below the terminal.] Deposit coins here [At the bottom:] Use the arrow keys to move [ For the full transcript of the entire comic as it could be played see 1608: Hoverboard/Transcript . ] [ For a transcript only of the text for the scenes with text in the comic see the table below. ] Apart from using one of the a full maps below there are also other cheating possibilities where people (or the game) have implemented ways to explore the game world more easily. # coins Text when depositing this number of coins "X" is the number of coins collected 0 coins You got 0 coins in 1 second You successfully avoided all the coins. 1 coin You got a single coin in 1 second It's a start. 2 - 4 coins You got X coins in 3 seconds Not bad! 5 - 9 coins You got X coins in 12 seconds Terrific! 10 - 16 coins You got X coins in 10 seconds 17 coins You got 17 coins in 15 seconds You found all the coins! Great job! 18-41 coins You got X coins in 430 seconds 42 coins You got 42 coins in 460 seconds No answers here. 43-168 coins You got X coins in 460 seconds All 169 coins You got 169 coins in 1457 seconds Are you Gandalf? Return to the play area There are many places where you can disappear behind black areas, as not all of these are solid. You might have discovered this yourself if you stayed in the play area, as the platform below the inverted parentheses is only solid at the edges. Some of these places out of the play area even hide secret passages or hidden rooms. You can reveal them by activating goggles mode . One notable hidden area is Elon Musk's volcano lair, which is located beneath the lava in the crater of Mount Doom. It can be difficult to find your way in here without using goggles mode even if you know it is there. (For more details, see secret passages .) Another hidden place is the floating rock island that floats high above the Washington Monument , which is almost the highest point with solid ground. It is located just outside the left edge of the play area. This island is almost impossible to find by chance, as it takes around 30 seconds of repeatedly pressing the Up Arrow key to reach it from the top of the Monument. Even if you go up enough, you will almost miss it, as the Monument is not aligned to the island. (The maps can help you if you're having trouble finding it.) As there are two coins on the floating rock island and four coins in the lair below the lava, it is very hard to find all the coins. There are even several coins that are hard to find because they just float in the air nowhere near any drawn things, or at least no things you can see before seeing the coin. They may hang in the air a few jumps above the ground, or in one case more than a seconds drop below the Destroyer. So getting all coins without help from a map would truly make you a Gandalf-like wizard . (See more regarding coins below.) The larger game world is physically bounded in the left, right, and down directions, with invisible walls to each side and the ground binding you from going any further down than the deepest depression or hidden caves... In the upward direction, there is in principle also an invisible wall, but while jumping up Cueball on his hoverboard will appear to continue upwards as long as you press to jump, in addition, the longer the up arrow is pressed repeatedly, the longer it will take for Cueball to fall down again once the button is released. So although there are no new things above, you can keep jumping as high as you like and will then fall proportionally longer to get back to where you started out. Until maps were created it could have been possible that there were some hidden unexplored parts. Not long after the games release, however, the maps was created, covering the entire game. To the far right is a platform at the top of a high pole. This platform turns out to be a nest (like a stork nest). Above the three eggs are ten coins (the most collected in one place outside the play area, and these are closer together). To the far left is a blond haired woman with a hair bun looking right. In front of her are four coins on a row. She tells about the Destroyer (should you have gone this way without finding it yet). Woman: In the sky, beyond the mountain, I saw a starship. Regarding the highest part you find the highest straight rise up in the air to something other than white, under the Rock Island just left of and very high above the Washington monument. Standing on the large rock on top of this floating rock island you are standing almost as high up as possible. There is a coin here one step down from the top of this large rock. This is the highest located coin in the game. Going over the edge also represents the largest possible drop in the game. However this is not the highest point where you can stand, as the very top of the bridge on the Destroyer is just a tat higher. But there is no coin there. Also this is not close enough to the end of the Destroyer that you can jump down to the ground, so the drop from the rock is by far the longest possible. The deepest part of the lair should have been the lowest point, but as this lair's entrance is up in the volcano crater, it does not reach down to become the lowest part of the image. There is also a deep well (half way left to the Volcano) with a girl at the bottom, that goes just as deep. But the deepest part where you can stand is in the ocean below the Destroyer where a rogue wave is talking to Cueball: Wave: I know rogue waves seem implausible, but we're a straightforward consequence of the equations of fluid dynamics. Cueball: ...But you can talk? Wave: The equations are really complicated. When standing under this wave you cannot get any lower. There are coins in all three locations, but as the coin is above the top of the high wave, it may be that it is the coin in the well that is the deepest. The coin under the lava is not at the bottom of the room so that is not so low. Taking a route that takes the hoverboard through all the extremes mentioned above, that is the lowest, highest, left and rightmost coins and solid positions within the game can be done in about 9 minutes and 30 seconds. See a picture here of the coin delivery after such a trip that reached all the boundaries . The game was made by Max Goodman who has previously worked on 1416: Pixels . The source code for the game can be found here . As previously noted, the comic bears considerable resemblance to 1110: Click and Drag . The comic is made in much the same way, with 'drawn' images "glued" together to form a large "map", with the illusion of infinite bounds made possible through space saving techniques where blank tiles are not stored and are instead painted white. The boundary between blank squares and 'drawn' squares is made clear as any white space in the normal images has a very slight grey tint. Thus, seams between images and blank spaces can be discerned. The tiles for the map are stored as simple PNG files in the naming scheme: X:-Y+s.png. An example from the starting tile can be seen here: http://xkcd.com/1608/1000:-1074+s.png , with the coordinate (X, Y) coordinate (1000, 1074). Each file is 513x513 pixels in size, one pixel is reserved as overlap to ensure seamless joining of images. The image tiles names are listed as coordinates in an X - Y grid with X in the range from 928 to 1108 and Y in the range from 928 to 1112. Internally in the game, the position of the player is given for instance as (X: 512187, -Y: -549668) for the starting position. Then these numbers are divided by 512 and rounded down. This gives the coordinate of the tile that the hoverboard is currently in. (X: 512187, -Y: -549668)/512 => (X, Y) = (1000.37, -[-1073,6]) => (1000, 1074) when the numbers are rounded down. The bottom left corner of the first tile, would thus be (1000, 1073), and the top left corner (1000, 1074) => (512000, -549888). The collision map is encoded in the darkness of the black. Using an image manipulation program, one can easily find the secret pathways even in the zoomed out maps provided below by enhancing the contrast of the dark areas. By observing page code while playing, the game grabs and displays images based on location, and subsequently clears all non-visible images. The game uses what seems to be a position syntax to retrieve the intended images live, and returns an error if such an image does not exist, such as a blank area. This technically means things could be added to the world and updated live. If the player is moving sufficiently fast or if the internet connection is slow, this means that the player can get stuck in a black area that does not load in time. This also means that the game does not have coded top or bottom limits, so any attempt to find the ceiling of the game will be futile unless the game is tweaked. The game does however have side limits, and it is not possible to go down further than image with Y coordinate 1073 (and it goes down to 1069 in the full image), so there is a bottom limit in the game. If using a cheat mode this may be different. Opening the console will display the text: what? hoverboard not enough for you!? in the log. Activating goggles mode will cause the text 'B-)' to appear in the log. The keyboard controls are as follows: This control scheme covers the three commonly used directional key sets: WASD a set of keys commonly used by modern games; HJKL a set of movement keys used by vi and applications which attempt to mimic vi key controls (vim); and the arrow keys, the most generic set of keys which is usually accepted by most applications which take movement as input, these were commonly used in older games. On devices which have a touch screen and tilt sensor (portable devices like mobile phones and tablets) the controls are as follows: After inspecting the source code, there appears to be no way to move down on a portable device, this is only relevant if gravity is disabled (see Cheats and Exploits ). Aside from the obvious ability to move out of bounds in the game, there are some more obscure hidden features which can't be enabled through normal gameplay, the ones found so far are as follows: Modes are activated by opening the Javascript Console (F12 [Or Command-Alt-I in most browsers under Mac OS X] to open Developer Tools, then Console tab) and writing corresponding commands. Click to expand:

The "comic" is actually a browser game made to celebrate the release of Randall's new book, Thing Explainer , which was released on the same day as this comic: Tuesday, November 24, 2015. The comic thus appeared on a Tuesday, replacing that week's normal Wednesday release to coincide with the release day. The xkcd Header text also changed that day to shout out that the book was released on that day. The title refers to a hoverboard (which resembles a hovering skateboard without wheels) which has been most prominently featured in the movie Back to the Future Part II , which took place in the future, until a little more than a month before this comic was released. Marty McFly traveled to the future in this second installment, more precisely to 2015-10-21 , and this comic was released just over one month later 2015-11-24. Hoverboards are just one of many things predicted in Back to the Future Part II that have come to pass before reaching the date from the movie, but are more uncommon in our world, along with other inventions like flying cars and musical clothing . Randall is known to have had electric skateboards , which is also thematically related, although another type of hoverboard would be mentioned just five weeks later in 1623: 2016 Conversation Guide . Given Randall's enjoyment of movies and time travel it is very likely that this game is also a tribute to the Back to the Future movies. But the release day of the game has been used to promote his new book (as is clear with the text in the start screen of the game), and this explains why it was not released on the Back to the Future date. Apart from the date of release and the text about the book, the game does not seem to have any direct relation to the book; there are, however, several scenes in the game that could be seen as references to Thing Explainer . Instead the main part of the game is all the references to several movies and other stuff that has often been featured in xkcd as well as many of the other comics. The game features an animated Cueball riding on a hoverboard which can take several different positions . The controls are the left, up, and right arrows, as written on the start screen until you begin the game, after which the text disappears. There are alternatives as explained in the Controls section. The player can jump repeatedly mid-jump to reach increasing heights, and can move left and right both while jumping and descending (see more under controls). The player begins in a line-drawing maze (called the Play Area ) with 17 gold coins located throughout and a "deposit" terminal. The ostensible goal of the game is to collect as many coins as possible and return them to the deposit in the fastest possible time, which returns text messages describing the result. Players consumed with obtaining the best possible time result for collecting the coins may not realize there is anything more to the game. The best way to enjoy this comic is to play the game! If you didn't do that already, reading anything below or the official transcript will spoil you from truly enjoying the comic, and maybe making some interesting discoveries yourself! So: !!!SPOILER ALERT!!! Beyond the maze on either side (just far enough that players who remain within the maze will not see) are tall walls seemingly designed to contain the player . However, the walls have a finite height and, combined with the ability to double-jump, the player can leave the purported "play area" either to the sides or above the initial maze. This returns a flashing red error message : " Return to the Play Area ". But if the player overcomes the desire to comply and return to the play area and disregards this message, they can take hoverboard Cueball outside beyond the tall walls surrounding the initial play area. And here they will discover an entire world that can be explored left and right (and above), including numerous points of interest and Easter eggs similar in style to comic 1110: Click and Drag . There are also many more coins to collect, 169 coins all in all, so 152 more than those from the play area. Although this game is reminiscent of Click and Drag, this was the first time an actual game, where the user moves an object in front of the drawing, has been released on xkcd. In previous "games" this has not been the case. In Click and Drag the user only moves the drawing into the view section. And in for instance the two previous April fools' comics , 1350: Lorenz and 1506: xkcloud , the user does not move anything, but only supplies choices, text and drawings. However, already on the next April Fools' Day a new game, 1663: Garden , was released where the users also actively moved items around on the screen and could make items disappear (like taking coins in this game.). The ability to infinitely doubles jump allows us to reach beyond just the ground. There are many themes and references throughout the game, but the two main themes are Star Wars and The Lord of the Rings . Below there is a table listing all references to both of these movies and much more. For instance there are 19 references to SW and 6 to LOTR. The largest part of the game is located on the right side of the play area and is mainly a world dominated by references to Star Wars . Most noticeable is a recreation of the opening scene in the first film , where Princess Leia's space ship Tantive IV also known as The Rebel Blockade Runner is flying over the desert planet Tatooine . Here it is followed by the Star Destroyer , Devastator . The desert ground with these two space ships above is the first you find to the right. Although in the game they are located inside the atmosphere, not as in the movie out in space, a fact that is commented on by Megan who looks out from an opening in the bottom of the Destroyer's hull. Megan: Is this ship designed to fly in the atmosphere like this? Both ships are high above the ground, but there are three wires from the ground that connect (and thus guide you) up to The Runner and from there 100+ torpedoes , which are fired down on the Runner coming from the Destroyer above, gives away the location of the Destroyer itself. The Destroyer is so high up in the air, that you would not be likely to find it by chance without these leads (or at least some of the several other hints from people on the ground looking up and reacting or like White Hat looking from the tip of the Washington Monument and reacting by saying : "Uh, what the heck is that?! ."). One of the main points (The Joke) of the entire game is the extreme size of such a Destroyer . It takes up more space than the rest of the game (and most of the coins are located there). Inside the Destroyer there are many, many rooms, long corridors and deep shafts, even a huge cave with trees and animals. At the bridge we meet both Darth Vader and the Emperor himself, Palpatine . There are many other jokes related both to Star Wars and other movies and xkcd comics inside the Destroyer. For instance, Darth Vader discusses Steven Universe , bringing up Rose Quartz and Steven himself ( who can be found with the Crystal Gems in a different part of the Destroyer). Darth Vader: But Steven's mother is a Crystal Gem... There are also interesting things and references along the ground beneath the Destroyer, some of these are also Star Wars related like the wedding scene where Jabba the Hutt is mentioned. To the left side is an entirely different world, although much smaller (shorter) than the one to the right. Here the main theme is The Lord of the Rings mainly with the presence of a volcano where for instance Megan tries to throw in rings of power , as in the scene from the last LOTR film where Frodo fails and Gollum attacks inside the volcano Mount Doom , thus making it clear that the volcano in the game represents this volcano. Both Frodo, Sauron and Gandalf are mentioned in the game. The first two by name in the text. Two great eagles are talking about Frodo and Tolkien , Sauron's name is read up by Megan from a book , and Gandalf is drawn as a wizard figure in the crater and also his name is used in the message you receive if you collect all possible coins . The two worlds do conflict though, as an X-wing fighter is parked at a gas station to the left in LOTR world, and Gandalf's famous quote You shall not pass! from his fight against the Balrog is modified by Cueball who is not trying to block your path to a coin inside a room in the Destroyer. This conflict could very well be a reference to the fact that Andy Serkis who played Gollum in LOTR, now plays the Supreme Leader Snoke in the new Star Wars movie, and his appearance as Snoke is not that much different from Gollum's. Snoke also delivers a line in the movie (about "bringing someone to me") that reminds one of Gollum when he talks about "the ring coming to me". Randall would not have known this last part at the time that this comic was released, but he would likely be aware of Andy Serkis' involvement. Other themes are related to other movies, like a naughty reference to Star Trek from inside the bridge of the Rebel Blockade Runner where a long-haired woman (maybe Danish since she obviously does this to annoy Star Wars fans and Hairbun behind her, which could represent Princess Leia with her special hair style ) delivers the following line taken from the Star Trek universe: Long haired woman: Captain's log, stardate November 24th, 2015... Hairbun: Augh! No! Also references to video games are seen, best shown with the maze towards the back end of the Destroyer which are an almost complete depiction of Level 1 of the computer game Prince of Persia down to the three coins being in the place of three items to take in that game, and at least two of the opposing sword fighters in the correct places as well. The comic/game and book were released only 3 weeks before the 7th Star Wars movie Star Wars: The Force Awakens was released on December 14, 2015. And this movie had already been referenced by Randall 7½ weeks earlier in 1585: Similarities , when another movie ( The Martian ) were released. It was a reference in the title text to the new robot BB-8 that are featured in the Force Awakens. That the Star Wars section is thus so much larger than the LOTR section could be a hint to the fact that it is now 12 years ago that the last of those films were released, and although the Hobbit has been released as three films over the previous three Christmases it was Star Wars that dominated the Christmas a month after this comics release. Some of the scenes in this game are references to pictures in the new book that it celebrates. Here are some examples: There are also many references to other xkcd comics, like the room at the front end of the Destroyer ball pit filled with playpen balls , and two adults playing in it, like in 150: Grownups . Also the well in the left part of the world with a girl and a coin at the bottom is likely a reference to the movie The Ring , which has been referenced before in xkcd. Wells have also come up in xkcd in the early Well series . There have been many comics with electric skateboards as mentioned, which do not appear in this comic, but there is one example of a normal skateboard . This is used by Megan in a room in the Destroyer, while she is inside a hamster ball . There is also another hamster ball , with a kid (looking like Megan) inside. It is used in a more than human sized ten pin bowling game to the left. Hamster balls is another item that has been prominently featured in xkcd. In the weeks before, and especially the weeks after there were also other comics that had a subject which could refer back to Hoverboard in some ways. Maybe these comics were either influenced by the game, or the other way around so that relevant items were added to the game because of these other comics: Cueball to Megan at the bottom: Honestly, it doesn't even look that much like Washington. Cueball to White Hat at the tip: Look at that- solid aluminum! We´re gonna be rich! Cueball: What's up? Ant queen: The usual. Poopin' out ants. Cueball: Eww. Megan at the edge of the volcano crater: One of these is probably a ring of power or whatever. Right quadcopter: Remember: There's no such thing as good volcano footage taken by a quadcopter that survived. Cueball singing: Spider-man Spider-plan Spider-canal Spider-Panama Gates let in Spider boats Flood the locks Spiders float Look out! Spiders in both oceans. Almost all main characters in the xkcd gallery are used more than once, especially there are three characters that are used several times. Number one is of course Cueball (with close to 90 appearances) who is already shown at the starting point . He is also the first character seen when walking both right and left (where he speaks the first line to the left). Then follows Megan with at least 40 appearances, she is even shown twice in the same location three times, one of these three even occurs within one of the small images . She is also shown with Cueball in his first appearance to the left, and she is the first to speak a line to the right here . Also Ponytail is well represented with 26 appearances (for instance here) . Hairy (with different hair styles) is used 7 times (for instance here ) and Hairbun is used 5 times (for instance here) . Two of the main characters are used twice: Beret Guy ( here and here ) and White Hat ( here and here ). The only exception is that the main villain of xkcd Black Hat who is very hard to find. He is only shown once in the comic where he very uncharacteristically just sits and snores at the right wall in the cave inside the Destroyer (is it really him...?). The only other hint that he is not forgotten is that his hat can be seen on a stick under the Destroyer after the three large T-like structures. And this is not that kind of stick characters Randall usually draws. But at least we now know where Danish has hidden it from him this time (see 405: Journal 3 ). Given that his hat is stuck there, he could also be any of the Cueballs close by… Also Blondie seems to be only represented once, while in her reporter mode while discovering a bug before the volcano as can be seen here . There are also several characters that are not recognizable as either any of the standard xkcd characters or in any other way (see for instance a few of the wedding guests ). But there are possibly some of the minor characters are used like Danish at the bridge in the Blockade Runner ( here ) but this cannot be confirmed, she just looks like her and has some similarities teasing the Star Wars fan. Several places in the comic it is clear from the size and the behavior that some of the characters are kids, see for instance the Blondie image mentioned above, where two kids looking like Megan and Hairy stand behind her, but they would in principle not be Megan or Hairy despite appearance, as these named characters are adults. There are also many fictive people from different movies, books, and shows; for instance Darth Vader ( here ), Gandalf ( here ) and Steven Universe ( here ) all three mentioned above, and some real life people: you can find Elon Musk , who has a hidden lair under the Volcano (see here ), and Gregor Mendel, hanging out on a Star Destroyer with a pea plant. Furthermore, there are many animals (like the puma and the deer ) in the cave, some even rather big like this octopus or even gigantic like this ant queen (all three from inside the Destroyer). There are also a couple of small Star Wars robots, one in a corridor in each space ship ( here from the Destroyer ). [This transcript only covers the starting page as shown on xkcd: xkcd 1608 . A full transcript of the entire comic can be found on this page .] [Cueball is shown on a hoverboard in the center of the comic. Around him is a simple maze with 12 yellow coins. Another Cueball without hoverboard is shown standing on one of the platforms to the right. The bottom half of the window is black. Right of where Cueball stands is a ramp. Behind the ramp is a terminal. There is lots of space left of the maze, outside the maze. Text is only written in white below in the black area. The first part of the text is written below Cueball on hoverboard. Then there is an arrow pointing to the terminal and a label. Finally there is a line of text at the bottom of the black area.] [Under Cueball:] My new book, Thing Explainer, comes out today! To celebrate, here's a small game. [Under the arrow below the terminal.] Deposit coins here [At the bottom:] Use the arrow keys to move [ For the full transcript of the entire comic as it could be played see 1608: Hoverboard/Transcript . ] [ For a transcript only of the text for the scenes with text in the comic see the table below. ] Apart from using one of the a full maps below there are also other cheating possibilities where people (or the game) have implemented ways to explore the game world more easily. # coins Text when depositing this number of coins "X" is the number of coins collected 0 coins You got 0 coins in 1 second You successfully avoided all the coins. 1 coin You got a single coin in 1 second It's a start. 2 - 4 coins You got X coins in 3 seconds Not bad! 5 - 9 coins You got X coins in 12 seconds Terrific! 10 - 16 coins You got X coins in 10 seconds 17 coins You got 17 coins in 15 seconds You found all the coins! Great job! 18-41 coins You got X coins in 430 seconds 42 coins You got 42 coins in 460 seconds No answers here. 43-168 coins You got X coins in 460 seconds All 169 coins You got 169 coins in 1457 seconds Are you Gandalf? Return to the play area There are many places where you can disappear behind black areas, as not all of these are solid. You might have discovered this yourself if you stayed in the play area, as the platform below the inverted parentheses is only solid at the edges. Some of these places out of the play area even hide secret passages or hidden rooms. You can reveal them by activating goggles mode . One notable hidden area is Elon Musk's volcano lair, which is located beneath the lava in the crater of Mount Doom. It can be difficult to find your way in here without using goggles mode even if you know it is there. (For more details, see secret passages .) Another hidden place is the floating rock island that floats high above the Washington Monument , which is almost the highest point with solid ground. It is located just outside the left edge of the play area. This island is almost impossible to find by chance, as it takes around 30 seconds of repeatedly pressing the Up Arrow key to reach it from the top of the Monument. Even if you go up enough, you will almost miss it, as the Monument is not aligned to the island. (The maps can help you if you're having trouble finding it.) As there are two coins on the floating rock island and four coins in the lair below the lava, it is very hard to find all the coins. There are even several coins that are hard to find because they just float in the air nowhere near any drawn things, or at least no things you can see before seeing the coin. They may hang in the air a few jumps above the ground, or in one case more than a seconds drop below the Destroyer. So getting all coins without help from a map would truly make you a Gandalf-like wizard . (See more regarding coins below.) The larger game world is physically bounded in the left, right, and down directions, with invisible walls to each side and the ground binding you from going any further down than the deepest depression or hidden caves... In the upward direction, there is in principle also an invisible wall, but while jumping up Cueball on his hoverboard will appear to continue upwards as long as you press to jump, in addition, the longer the up arrow is pressed repeatedly, the longer it will take for Cueball to fall down again once the button is released. So although there are no new things above, you can keep jumping as high as you like and will then fall proportionally longer to get back to where you started out. Until maps were created it could have been possible that there were some hidden unexplored parts. Not long after the games release, however, the maps was created, covering the entire game. To the far right is a platform at the top of a high pole. This platform turns out to be a nest (like a stork nest). Above the three eggs are ten coins (the most collected in one place outside the play area, and these are closer together). To the far left is a blond haired woman with a hair bun looking right. In front of her are four coins on a row. She tells about the Destroyer (should you have gone this way without finding it yet). Woman: In the sky, beyond the mountain, I saw a starship. Regarding the highest part you find the highest straight rise up in the air to something other than white, under the Rock Island just left of and very high above the Washington monument. Standing on the large rock on top of this floating rock island you are standing almost as high up as possible. There is a coin here one step down from the top of this large rock. This is the highest located coin in the game. Going over the edge also represents the largest possible drop in the game. However this is not the highest point where you can stand, as the very top of the bridge on the Destroyer is just a tat higher. But there is no coin there. Also this is not close enough to the end of the Destroyer that you can jump down to the ground, so the drop from the rock is by far the longest possible. The deepest part of the lair should have been the lowest point, but as this lair's entrance is up in the volcano crater, it does not reach down to become the lowest part of the image. There is also a deep well (half way left to the Volcano) with a girl at the bottom, that goes just as deep. But the deepest part where you can stand is in the ocean below the Destroyer where a rogue wave is talking to Cueball: Wave: I know rogue waves seem implausible, but we're a straightforward consequence of the equations of fluid dynamics. Cueball: ...But you can talk? Wave: The equations are really complicated. When standing under this wave you cannot get any lower. There are coins in all three locations, but as the coin is above the top of the high wave, it may be that it is the coin in the well that is the deepest. The coin under the lava is not at the bottom of the room so that is not so low. Taking a route that takes the hoverboard through all the extremes mentioned above, that is the lowest, highest, left and rightmost coins and solid positions within the game can be done in about 9 minutes and 30 seconds. See a picture here of the coin delivery after such a trip that reached all the boundaries . The game was made by Max Goodman who has previously worked on 1416: Pixels . The source code for the game can be found here . As previously noted, the comic bears considerable resemblance to 1110: Click and Drag . The comic is made in much the same way, with 'drawn' images "glued" together to form a large "map", with the illusion of infinite bounds made possible through space saving techniques where blank tiles are not stored and are instead painted white. The boundary between blank squares and 'drawn' squares is made clear as any white space in the normal images has a very slight grey tint. Thus, seams between images and blank spaces can be discerned. The tiles for the map are stored as simple PNG files in the naming scheme: X:-Y+s.png. An example from the starting tile can be seen here: http://xkcd.com/1608/1000:-1074+s.png , with the coordinate (X, Y) coordinate (1000, 1074). Each file is 513x513 pixels in size, one pixel is reserved as overlap to ensure seamless joining of images. The image tiles names are listed as coordinates in an X - Y grid with X in the range from 928 to 1108 and Y in the range from 928 to 1112. Internally in the game, the position of the player is given for instance as (X: 512187, -Y: -549668) for the starting position. Then these numbers are divided by 512 and rounded down. This gives the coordinate of the tile that the hoverboard is currently in. (X: 512187, -Y: -549668)/512 => (X, Y) = (1000.37, -[-1073,6]) => (1000, 1074) when the numbers are rounded down. The bottom left corner of the first tile, would thus be (1000, 1073), and the top left corner (1000, 1074) => (512000, -549888). The collision map is encoded in the darkness of the black. Using an image manipulation program, one can easily find the secret pathways even in the zoomed out maps provided below by enhancing the contrast of the dark areas. By observing page code while playing, the game grabs and displays images based on location, and subsequently clears all non-visible images. The game uses what seems to be a position syntax to retrieve the intended images live, and returns an error if such an image does not exist, such as a blank area. This technically means things could be added to the world and updated live. If the player is moving sufficiently fast or if the internet connection is slow, this means that the player can get stuck in a black area that does not load in time. This also means that the game does not have coded top or bottom limits, so any attempt to find the ceiling of the game will be futile unless the game is tweaked. The game does however have side limits, and it is not possible to go down further than image with Y coordinate 1073 (and it goes down to 1069 in the full image), so there is a bottom limit in the game. If using a cheat mode this may be different. Opening the console will display the text: what? hoverboard not enough for you!? in the log. Activating goggles mode will cause the text 'B-)' to appear in the log. The keyboard controls are as follows: This control scheme covers the three commonly used directional key sets: WASD a set of keys commonly used by modern games; HJKL a set of movement keys used by vi and applications which attempt to mimic vi key controls (vim); and the arrow keys, the most generic set of keys which is usually accepted by most applications which take movement as input, these were commonly used in older games. On devices which have a touch screen and tilt sensor (portable devices like mobile phones and tablets) the controls are as follows: After inspecting the source code, there appears to be no way to move down on a portable device, this is only relevant if gravity is disabled (see Cheats and Exploits ). Aside from the obvious ability to move out of bounds in the game, there are some more obscure hidden features which can't be enabled through normal gameplay, the ones found so far are as follows: Modes are activated by opening the Javascript Console (F12 [Or Command-Alt-I in most browsers under Mac OS X] to open Developer Tools, then Console tab) and writing corresponding commands. Click to expand:

Food Combinations

Food Combinations

https://www.xkcd.com/1609

https://www.explainxkcd.com/wiki/index.php/1609:_Food_Combinations

[Megan is talking with Ponytail and Cueball, who has his hand to his chin. Above them in 4x3 black boxes different kind of food is written in white text]. Ice cream Ham Relish Pancakes Ketchup Cheese Eggs Cupcakes Sour cream Hot chocolate Avocado Skittles Megan: You know what's actually really good? Megan: ____ and ____. Megan: food and food Cueball: Huh. I Guess I can see it. [Caption below the panel.] Fun fact: if you say "you know what's actually really good?" in the right tone of voice, you can name any two individually-good foods here and no one will challenge you one it.

This is another comic with one of Randall's fun facts . Unusual food combinations are often counter-intuitive and can vary wildly by individual taste. Real-world examples of unusual food pairings, such as pickles and peanut butter , French fries in chocolate shake, or even the comfort-food pairing of chicken and waffles , pair sweet, sour, or salty foods with a food or condiment from a different group. In many "normal" food pairings, though, the cross-over between sweet, savory and salty foods also exists, such as ketchup, a very sweet condiment being regularly applied to hamburgers and French fries, both savory and salty foods. In this comic, Randall lists twelve somewhat random food items. Below these Megan says a line to Ponytail and Cueball where she claims that two items of food from the list above (pick any) would be a great combination. Some of these are obviously great together (and much depends on personal taste) but many combination will definitely not be enjoyed by most people living for instance in the US (where Randall is situated). Say ketchup and ice cream or hot chocolate and avocado. But no matter which two Megan chooses the response from Cueball (or anyone else) would be the same - he can see what she means with this combination. Randall suggests, in the caption below, that by using the right tone of voice, you can put any pair of these food items together as an "actually really good" food combination, and no one will challenge you on it. This can either be because they have likely heard, or tried other unexpected combinations that are highly recommended or liked. But it could also just be because they are polite, or did not really think about what you said due to your tone of voice. Cueball's agreement could also be due to some social pressure in this situation, the same reason he will drink beer even though he does not enjoy the taste, as in 1534: Beer . Or maybe they are like Joey from Friends who love any combination of food, as long as it is something he think is good by itself - see this clip . The title text extends the joke by recommending countering such a bizarre proposal with an assertion that the random pairing announced is an actual potato chip flavor popular in Canada. This plays on the fact that in different countries and regions, cultural tastes can vary wildly. For instance, ketchup flavored potato chips are quite popular in Canada, but are almost never offered in US markets. Loblaws and Lay's have run potato chips flavor competition in Canada in 2013-15 with flavors such as Maple Moose, Bacon Poutine, Jalapeño Mac N' Cheese, Cowboy BBQ Beans. Similar strange combinations of potato chips are run, either temporarily or permanently, in other countries including the United Kingdom . In addition, some parts of Canada are used as experimental markets to test new flavors of potato chips. [Megan is talking with Ponytail and Cueball, who has his hand to his chin. Above them in 4x3 black boxes different kind of food is written in white text]. Ice cream Ham Relish Pancakes Ketchup Cheese Eggs Cupcakes Sour cream Hot chocolate Avocado Skittles Megan: You know what's actually really good? Megan: ____ and ____. Megan: food and food Cueball: Huh. I Guess I can see it. [Caption below the panel.] Fun fact: if you say "you know what's actually really good?" in the right tone of voice, you can name any two individually-good foods here and no one will challenge you one it.

Fire Ants

Fire Ants

https://www.xkcd.com/1610

https://www.explainxkcd.com/wiki/index.php/1610:_Fire_Ants

[Cueball is talking to Hairbun, an advisor, who is sitting behind a desk.] Cueball: I'm having second thoughts about grad school and could use some advice. [Same setting as before. The animated advisor talks while gesticulating with her hands.] Advisor: Consider the fire ant. Advisor: When there's a flood, fire ants survive by joining together into giant floating rafts. [Cueball is just standing there in the next beat-panel.] [Back to the first setting but in a larger frame.] Cueball: Wait, what lesson am I supposed to take from that? Advisor: Ants are so cool! Cueball: ...You're not big on metaphors, are you. Advisor: I am big on ants.

Cueball , a university student, is meeting with Hairbun (likely his mother or somebody qualified to give college advice) asking her advice concerning his second thoughts about grad school . Her response begins with a popular reference from the Bible concerning ants ; however, she specifically narrows in on the sub-family of fire ants . The book of Proverbs is a self-proclaimed book on receiving wisdom and instruction to be made wise. Thus, her response appears to begin as an instruction to him in response to his question. The proverb in particular she appears to begin quoting instructs the lazy person to "Go to the ant, thou sluggard! Consider her ways..." as she prepares for the desolation of winter by providing during the bounty of summer despite not having to be told so. The assumption by the reader would be that she is going to compare Cueball to a lazy person and instruct him to prepare for the later years (winter of life) by studying now while he is young (summer of life). However, after the initial phrase she instead discusses a cool fact about fire ants . (Specifically the ability of fire ants to join together to form floating rafts in case of flooding). Continuing in the vein of the joke, that Hairbun was going to use a metaphor as part of her instruction, Cueball asks her what lesson he is supposed to take away from that fact. To which she replies with her fascination for ants ( Ants are so cool! ). Correctly, Cueball states that she is not big on metaphors , as there were none hidden in her first statement. She continues to tell him what she is big on: Ants . This last exchange may imply that the expected metaphor would have had as little effect on Cueball's choice to continue grad school as an excited rant about fire ants (since he was just waiting for a metaphor anyway). Or perhaps it expresses that Hairbun finds more instruction in the study of the natural world than in ancient writings. In either case, it is left unanswered as to whether her argument was enough to answer Cueball's dilemma. Before reading the title text the reader may have assumed that Cueball went to meet with a University adviser. But the title text makes it clear that he was actually in the entomology department (making her an entomologist - i.e. someone who studies insects). It is reasonable to assume that his grad studies are thus in entomology and he is meeting a professor that might act as a career mentor. Thus, her discourse on fire ants may have been to persuade Cueball that his grad studies in entomology were well worth continuing because of the exciting nature of the field of study. This would be achieving the intent of the Proverb she appeared to quote (convincing Cueball to continue life preparations by finishing grad school) although she discarded its wording. In almost an immediate and seemingly bizarre contradiction, she chalks up her strange rambling on fire ants as just a formula that all entomology personnel use when asked any question. They use a two-step formula to answer any questions. It won't help you much because all you will learn is that ants are cool and then they have forgotten anything else you asked them while they continued to think of ants. This would imply that the answer Cueball received had literally nothing to do with his question or situation he was in and any similarity to being a meaningful answer or even a proverb of instruction was purely coincidental and unintended. Another popular example where the phrase consider the from the Bible has been spoofed can be found in Monty Python's Life of Brian Consider the lilies sketch. However, this refers to a passage in Matthew instead of Proverbs . It seems likely that Randall is fascinated by ants (he is fascinated by a lot of cool stuff…) Cueball: What's up? Ant queen: The usual. Poopin' out ants. Cueball: Eww. [Cueball is talking to Hairbun, an advisor, who is sitting behind a desk.] Cueball: I'm having second thoughts about grad school and could use some advice. [Same setting as before. The animated advisor talks while gesticulating with her hands.] Advisor: Consider the fire ant. Advisor: When there's a flood, fire ants survive by joining together into giant floating rafts. [Cueball is just standing there in the next beat-panel.] [Back to the first setting but in a larger frame.] Cueball: Wait, what lesson am I supposed to take from that? Advisor: Ants are so cool! Cueball: ...You're not big on metaphors, are you. Advisor: I am big on ants.

Baking Soda and Vinegar

Baking Soda and Vinegar

https://www.xkcd.com/1611

https://www.explainxkcd.com/wiki/index.php/1611:_Baking_Soda_and_Vinegar

[Ponytail is standing behind Science Girl who has one hand up. They are looking at a table with a model volcano.] Science Girl: My science project is a baking soda and vinegar volcano! [A larger frame that includes Megan who stands to the right. Ponytail is a little further back and Science Girl has taken her hand down. The baking soda volcano erupts in a small upwards explosion.] Ponytail: Why do people make these? It isn't really even a science project. It doesn't teach anything about- Volcano: Foom! [Smaller frame again. Ponytail has moved closer to the table, Science Girl moves around the table to the right, pointing at the volcano while Megan walks closer. The "lava" flows down the volcano on both sides.] Science Girl: See how the baking soda and vinegar mix with mud and ice to form deadly flowing lahars? [Zoom in on Science Girls head close to the stream of lava going down the lower part of the volcano's right slope.] Science Girl: You can see the tiny cars trying to flee. Science Girl: Whoops! Too slow. [Zoom in on Ponytail.] Ponytail: Um. This is a bit grim. Science Girl (off panel): Learning! [Science Girl stand to the right of the table looking at the now still volcano. Shaky lines surround a sound effect written over the top of this slim frame:] Rumble [Back to showing all three as before. Science Girl lift a finger in the air.] Science Girl: And now we're learning that this volcano is an offshoot of a vinegar hotspot rising from deep within the earth. Science Girl: Annnd... [Science Girl turns away from the table looking right as a loud noise can be heard off-panel, depicted in white text on a wavy black bubble:] Boooom [Megan has walked over to a window to the right. It has the blinds drawn down. She opens a hole in the blinds by pulling down in the middle. It is dark outside. The other two are outside the frame to the left.] Science Girl (off panel): The baking soda supervolcano erupts, injecting clouds of salt into the stratosphere. Megan: Why is it getting dark outside? Science Girl (off panel): Learning is fun! [We see Science Girl standing close to the table, of which only the right leg can be seen. She holds up a tablet with a graph showing a rising trend. The other two are both out of the frame.] Science Girl: Sunlight dims. The earth cools. Summer frosts form. Crops die. We check the markets. Grain prices are rising. Megan (off panel): I want to stop learning now. Science Girl: Soon, we all will.

In popular fiction (and maybe in part in fact) the " Baking Soda and Vinegar " volcano is often a staple image of the science nerd at the science fair (see example here ), unless all the science nerds are doing real imaginative science and the student(s) with the volcano exhibit are dragging out the old hackneyed stereotype. It may also be age-dependent, this being something that is relatively advanced science for the lower grades but rather a childish experiment in the hands of older students. Ponytail is about to point out any one of a number of flaws with the trope. For one thing, while the project may exhibit interesting physical phenomena of the sort that some scientists study, the project itself doesn't actually teach anything about the scientific method. Actual science fairs are usually intended to teach students about the scientific method by exercising it firsthand: subjecting hypotheses to appropriately rigorous experimentation, and reporting on the results. The cliché volcano exhibit doesn't teach any of this, and may instead reinforce the idea that science is about cool explosions and not a system of inquiry. Further, the exhibit doesn't (usually) actually demonstrate anything about real volcanic activity: it is relatively simple chemistry involving the reaction of acetic acid in vinegar and sodium bicarbonate in baking soda to produce sodium acetate and (notably) a vigorous froth made up of bubbles of carbon dioxide. It is often dressed up to look more impressive, such as by using dye or other additives to make the 'eruption' look more 'realistic,' but it often fails to replicate important features of actual volcanic eruptions, such as the flow of lava, associated seismic events or the collapse of part of the volcanic crater. Most people doing soda volcano projects don't even explain what's happening. Science Girl has made a little more of her volcano, however, as it seems to go beyond simple chemistry. The model replicates many of the dangers (aside from the pure lava) of a volcano, and appears to have been given scaled-down vehicles (not visible in the comic) trying (and failing) to escape the dangers of the resultant mud-flows (a.k.a. lahars in professional terminology) being modeled. Ponytail contradicts her early reaction by also not liking the more realistic model, although it is the carnage she dislikes, not that it has more correct details of the eruption itself. Even more, this is not an isolated 'model volcano' but a vinegar-powered representation of a geological 'hot spot', such as with the islands of Hawaii, in which the spot moves with respect to the Earth's crust (or vice-versa) and generates a new volcano some way off. Despite this model being supported on a table, it appears that the 'project' extends some way beyond that and has somehow contrived further eruptions away from the table, the room and probably even the building. The 'project' seems to be turning into a very thorough model of a much larger geological process (a Supervolcano like the one under Yellowstone ) and destined to produce a very real volcanic winter . Where a magma-powered volcano could produce vast clouds of dust, preventing the sun's energy from warming the Earth, in this case it's the airborne salt (probably sodium acetate) from the chemical reaction that appears to be in danger of causing crop failure. There's no mention of the corresponding environmental effects of the vast amounts of carbon dioxide (and/or aqueous carbonic acid) necessarily released in proportion to the ejected salt (presumably itself not left in solution). It is especially troubling that the child even mentions that her model volcano is an offshoot of a baking soda super volcano. Supervolcanoes are massive volcanoes, far larger than even those on the list of Decade Volcanoes (mentioned in the title text), whose eruption would likely trigger species-level extinction events comparable to the dinosaur extinction. Humanity can only hope the child is exaggerating in her description, but the symptoms witnessed by the adult looking out the window suggest otherwise. Campi Flegrei is actually a real life example of her project. When someone (presumably the dark haired woman) says she wants to stop learning, Science Girl grimly states that "Soon, we all will", alluding to their impending doom. Randall has mentioned supervolcanoes before in 1053: Ten Thousand (title text) and 1159: Countdown , making it a recurring interest of his. The volcano Mount Doom was depicted to the far left in the game 1608: Hoverboard released a week before this comic. It may not be a supervolcano, but quite potent anyway... Later this comic was directly referenced in the seventh panel of 1714: Volcano Types , where it is up to the reader to decide it this is Science Girl's model people or what happens outside on her supervolcano. In the title text the student expects extra credit for getting her model volcano added to the Decade Volcanoes list, a list maintained by International Association of Volcanology and Chemistry of the Earth's Interior of the world's most dangerous volcanoes (currently 16). It is either an absurd notion or a very troubling achievement that a science fair project could achieve the threat level posed by the likes of Mount Vesuvius (which destroyed ancient Pompeii in Italy, and threatens modern-day Naples in the same manner), Mount Rainier (whose lahars could potentially destroy parts of Seattle) or Mauna Loa (which could create a massive landslide, triggering a major tsunami that would threaten all of Hawaii). But if the volcano erupting outside is scaled down to match the scale of her original model volcano, at least that means that it was only a "local" volcano event and not a supervolcano event that she created, so it would only doom the local area. [Ponytail is standing behind Science Girl who has one hand up. They are looking at a table with a model volcano.] Science Girl: My science project is a baking soda and vinegar volcano! [A larger frame that includes Megan who stands to the right. Ponytail is a little further back and Science Girl has taken her hand down. The baking soda volcano erupts in a small upwards explosion.] Ponytail: Why do people make these? It isn't really even a science project. It doesn't teach anything about- Volcano: Foom! [Smaller frame again. Ponytail has moved closer to the table, Science Girl moves around the table to the right, pointing at the volcano while Megan walks closer. The "lava" flows down the volcano on both sides.] Science Girl: See how the baking soda and vinegar mix with mud and ice to form deadly flowing lahars? [Zoom in on Science Girls head close to the stream of lava going down the lower part of the volcano's right slope.] Science Girl: You can see the tiny cars trying to flee. Science Girl: Whoops! Too slow. [Zoom in on Ponytail.] Ponytail: Um. This is a bit grim. Science Girl (off panel): Learning! [Science Girl stand to the right of the table looking at the now still volcano. Shaky lines surround a sound effect written over the top of this slim frame:] Rumble [Back to showing all three as before. Science Girl lift a finger in the air.] Science Girl: And now we're learning that this volcano is an offshoot of a vinegar hotspot rising from deep within the earth. Science Girl: Annnd... [Science Girl turns away from the table looking right as a loud noise can be heard off-panel, depicted in white text on a wavy black bubble:] Boooom [Megan has walked over to a window to the right. It has the blinds drawn down. She opens a hole in the blinds by pulling down in the middle. It is dark outside. The other two are outside the frame to the left.] Science Girl (off panel): The baking soda supervolcano erupts, injecting clouds of salt into the stratosphere. Megan: Why is it getting dark outside? Science Girl (off panel): Learning is fun! [We see Science Girl standing close to the table, of which only the right leg can be seen. She holds up a tablet with a graph showing a rising trend. The other two are both out of the frame.] Science Girl: Sunlight dims. The earth cools. Summer frosts form. Crops die. We check the markets. Grain prices are rising. Megan (off panel): I want to stop learning now. Science Girl: Soon, we all will.

Colds

Colds

https://www.xkcd.com/1612

https://www.explainxkcd.com/wiki/index.php/1612:_Colds

[A graph is shown with two curves. The Y-axis indicated how you feel, with three levels indicated with small ticks on the inside of the axis. These are labeled to the left of the Y–axis. The X-axis gives the time. The unit is given (days written in gray text) to the left and then the number of days are noted below the axis for each of the eight ticks on the inside of the axis. Both curves begin at the lowest level just off the Y-axis. One curve, indicating how bad you feel, rises rapidly, reaching its maximum in less than two days only to fall off almost as rapidly, ending up on an even lower level than it began with before day 5. The other curve, indicating how bad you sound, start out by staying constantly low, first rising on day 3, when the first curve are drooping down. They cross between day 3 and 4, and first then does the second curve rise, reaching its max around day 5, not as high a maximum as the first curve, but it stays up longer, falling only moderately off even after day 8, where it reaches the middle level on the Y-axis. Above the two curves are two line intervals that indicated when you need sympathy and when you get it. This text is written on the broken line. All this is in gray text. Below the X-axis are the symptoms listed for the different time period. These are written in white inside gray rectangles. The rectangles are a different length depending on how many days they last. And they are in two layers.] [Y-axis:] The worst Bad Fine [The X-axis, with the unit written in gray just below Fine from the Y-axis:] Days: 0 1 2 3 4 5 6 7 8 [Labels for curves:] How bad you feel How bad you sound [Gray text on the two gray lines above:] Need sympathy Get sympathy [Text in white on gray below, first the three to the left (one above two below), then the two to the right one above the other:] Skin crawling Sore throat Aching Cough Hoarseness The worst part about colds

The typical symptoms of a cold are a sore throat, blocked or runny nose, sneezing, and coughing. Slightly less common symptoms can include headache, aching muscles and fever . The earlier symptoms to occur following infection are generally the more unpleasant-feeling symptoms: headache, aching muscles, sneezing and feeling cold. However, these symptoms are also those which are least obvious to other people, and so elicit very little sympathy . Within a few days, these symptoms start to subside, while a cough and runny nose start. These symptoms generally feel less unpleasant, but are much more noticeable to others, and so more sympathy may be given. The cough may lead to a hoarse voice, making the patient sound very ill; ironically, at this point, it may be easier for an employed person to phone in sick, but it is less desirable to stay off work. But it is now when the patient sounds hoarse that others give the sympathy that was really needed when the patient was feeling awful during the first couple of days. And to Randall this is the worst about colds, that the patients first gets sympathy when it is no longer really needed. The graph shows the above-mentioned facts as two curves, one that indicates how bad the sickness is, really bad on day 2, but much better already on day 3. And the other curve how bad the patient sounds due to the hoarseness and the coughing. And this curve first peaks around day 4-6 when the sympathy is no longer needed. The symptoms of the two periods are listed below the curves indicating which periods are affected by them. In the title text Randall muses about the fact that contagiousness ends around the time when hoarseness begins. This is the time when employers ask sick employees to stay at home in bed when they call in to the office, because they sound so hoarse. And also the time when coworkers will stay clear of those who do come in. But then it is too late, since everyone is probably already infected by then. Randall thus suggests that this is evidence that the cold virus has evolved to spread optimally in a work place. Since the cold virus is much older than offices this is unlikely. But it will always spread better in places where many people are close together; and since we are more inside in the winter, this is the main reason why it spreads more during cold periods. However, viruses do evolve very quickly so it may not be unlikely that some of them has already adapted to our present way of living. Another thing that Randall doesn't like about cold is that no medicine works, and the one that relives you the most is hard to come by. This was the subject two weeks later in 1618: Cold Medicine , and this suggests that it is actually Randall himself who has a long lasting cold. [A graph is shown with two curves. The Y-axis indicated how you feel, with three levels indicated with small ticks on the inside of the axis. These are labeled to the left of the Y–axis. The X-axis gives the time. The unit is given (days written in gray text) to the left and then the number of days are noted below the axis for each of the eight ticks on the inside of the axis. Both curves begin at the lowest level just off the Y-axis. One curve, indicating how bad you feel, rises rapidly, reaching its maximum in less than two days only to fall off almost as rapidly, ending up on an even lower level than it began with before day 5. The other curve, indicating how bad you sound, start out by staying constantly low, first rising on day 3, when the first curve are drooping down. They cross between day 3 and 4, and first then does the second curve rise, reaching its max around day 5, not as high a maximum as the first curve, but it stays up longer, falling only moderately off even after day 8, where it reaches the middle level on the Y-axis. Above the two curves are two line intervals that indicated when you need sympathy and when you get it. This text is written on the broken line. All this is in gray text. Below the X-axis are the symptoms listed for the different time period. These are written in white inside gray rectangles. The rectangles are a different length depending on how many days they last. And they are in two layers.] [Y-axis:] The worst Bad Fine [The X-axis, with the unit written in gray just below Fine from the Y-axis:] Days: 0 1 2 3 4 5 6 7 8 [Labels for curves:] How bad you feel How bad you sound [Gray text on the two gray lines above:] Need sympathy Get sympathy [Text in white on gray below, first the three to the left (one above two below), then the two to the right one above the other:] Skin crawling Sore throat Aching Cough Hoarseness The worst part about colds

The Three Laws of Robotics

The Three Laws of Robotics

https://www.xkcd.com/1613

https://www.explainxkcd.com/wiki/index.php/1613:_The_Three_Laws_of_Robotics

[Caption at the top of the comic:] Why Asimov put the Three Laws of Robotics in the order he did. [Below are six rows with first two frames and then a label in color to the right. Above the two column of frames there are labels as well. In the first column six different ways of ordering the three laws are listed. Then the second column shown an image of the consequences of this order. Except in the first where there is a reference. The label to the right rates the kind of world that order of the laws would result in.] [Labels above the columns.] Possible ordering Consequences [The six rows follows below. First the text in the first frame, then a description of the second frame, including possible text below and finally the colored label.] [First row:] 1. (1) Don't harm humans 2. (2) Obey Orders 3. (3) Protect yourself [Only text in square brackets:] [See Asimov’s stories] Balanced world [Second row:] 1. (1) Don't harm humans 2. (3) Protect yourself 3. (2) Obey Orders [Megan points at a mars rover with six wheels, a satellite disc, an arm and a camera head turned towards her, what to do.] Megan: Explore Mars! Mars rover: Haha, no. It’s cold and I’d die. Frustrating world [Third row:] 1. (2) Obey Orders 2. (1) Don't harm humans 3. (3) Protect yourself [Two robots are fighting. The one to the left has six wheels, a tall neck on top of the body, with a head with what could be a camera facing right. It has something pointing forward on the body, which could be a weapon. The robot to the right, seems to be further away into the picture. (it is smaller with less detail). It is human shapes, but made op of square structures. It has two legs and two arms, a torso and a head. It clearly shoots something out of it’s right “hand”. This shot seems to create an explosion a third of the way towards the left robot. There are two mushroom clouds from explosions behind both robots (left and right). Between them there are one more explosion up in the air close to the left robot, and what looks like a fire on the ground right between them. Furthermore there are two missiles in the air, one above the head of each robot. Lines indicate their trajectory. There is not text.] Killbot hellscape [Fourth row:] 1. (2) Obey Orders 2. (3) Protect yourself 3. (1) Don't harm humans: [Exactly the same picture as in row 3.] Killbot hellscape [Fifth row:] 1. (3) Protect yourself 2. (1) Don't harm humans 3. (2) Obey Orders [Cueball is standing in front of a car factory robot, that is larger than him. It has a base, and two parts for the main body, and then a big “head” with a small section on top. To the right something is jutting out, and to the left in the direction of Cueball there is an arm in three sections (going down, up and down again) ending in some kind of tool close to Cueball.] Car factory robot: I'll make cars for you, but try to unplug me and I’ll vaporize you. Terrifying standoff [Sixth row:] 1. (3) Protect yourself 2. (2) Obey Orders 3. (1) Don't harm humans: [Exactly the same picture as in row 3 and 4.] Killbot hellscape

This comic explores alternative orderings of sci-fi author Isaac Asimov's famous Three Laws of Robotics , which are designed to prevent robots from taking over the world, etc. These laws form the basis of a number of Asimov works of fiction, including most famously, the short story collection I, Robot , which amongst others includes the very first of Asimov's stories to introduce the three laws: Runaround . The three rules are: In order to make his joke, Randall shortens the laws into three imperatives: And then implicitly adds the following to the end of each law regardless of order of imperatives: This comic answers the generally unasked question: "Why are they in that order?" With three rules you could rank them into 6 different permutations , only one of which has been explored in depth. The original ranking of the three laws are listed in the brackets after the first number. So in the first example, which is the original, these three numbers will be in the same order. For the next five the numbers in brackets indicate how the laws have been re-ranked compared to the original. The comic begins with introducing the original set, which we already know will give rise to a balanced world, so this is designated as green.: Ordering #1 - Balanced World If they are not allowed to harm humans, no harm will be done disregarding who gives them orders. So long as they do not harm humans, they must obey orders. Their own self-preservation is last, so they must also try to save a human, even if ordered not do so, and especially also if they would put themselves to harm, or even destroy themselves in the process. They would also have to obey orders not relating to humans, even if this would be harmful to them; like exploring a mine field. This leads to a balanced, if not perfect, world. Asimov's robot stories explore in detail the advantages and challenges of this scenario. Below this first known option, the five alternative orderings of the three rules are illustrated. Two of the possibilities are designated yellow (pretty bad or just annoying) and three of them are designated red ("Hellscape"). Ordering #2 - Frustrating World The robots value their existence over their job and so many would refuse to do their tasks. The silliness of this is portrayed in the accompanying image, where the robot (a Mars rover looking very similar to Curiosity both in shape and size - see 1091: Curiosity ) laughs at the idea of doing what it was clearly built to do (explore Mars ) because of the risk. In addition to the general risk (e.g. of unexpected damage), it is actually normal for rovers to cease operating ("die") at the end of their mission, though they may survive longer than expected (see 1504: Opportunity and 695: Spirit ). This personification is augmented by the robot being switched on already while still on Earth and then ordered by Megan to go explore. The personification is humorous since it is a very nonhuman robot - a typical Mars rover, as has often been used in earlier comics. Ordering #3 - Killbot Hellscape This puts obeying orders above not harming humans, which means anyone could send them on a killing spree, resulting in a "Killbot Hellscape". It should also be noted humor is derived from the superlative nature of "Killbot Hellscape", as well as its over the top accompanying image, where there are multiple mushroom clouds (not necessarily nuclear). It also appears there are no humans (left?), only fighting robots. Ordering #4 - Killbot Hellscape The next would also result in much the same, the only difference here is that they would be willing to kill humans to protect themselves. But still they would need an order to start killing. This would be likely even worse for humans as they are put as the least important in the order. Ordering #5 - Terrifying Standoff The penultimate order would result in an unpleasant world, though not a full Hellscape. Here the robots would not only disobey to protect themselves, but also kill if necessary. The absurdity of this one is further demonstrated with the very un-human robot happily doing repetitive mundane tasks but then threatening the life of its user, Cueball , if he as much as considers unplugging it. Ordering #6 - Killbot Hellscape The last order would also results in a Hellscape wherein robots not only kill for self-defense but will also go on killing sprees if ordered as long as they didn't risk themselves. Could self-protection coming first not prevent the fighting? Not according to Randall. See discussion below. There are thus only three different results except the 'normal' 3-laws scenario. One result goes again three times, and this occurs whenever obeying orders comes before don't harm humans . In this case it will only be a matter of time (knowing human nature and history) before someone orders the robots to kill some humans, and this will inevitably lead to the killbot hellscape scenario shown in the third, fourth and sixth law-order. Even in the last case where protect yourself comes before obey orders, it would only be a matter of time before they would begin to defend themselves, against either humans or other robots which were actively trying to ensure that they would not be harmed by other humans/robots. So although it would be in the robots interest not to have war, this will surely occur anyway. Additionally, the robots would have to be intelligent to realize that they just needed to not go to war to protect themselves. There is nothing in this comic that indicates that the robots should be highly intelligent (like to AI in 1450: AI-Box Experiment ). In the two other cases obey orders comes after don't harm humans (as in the original version). But the result is very different both from the original and from each other. The frustrating world comes by because although the robots will not harm the humans, they will also not harm themselves. So if our orders conflict with this, they just do not perform the orders. As many robots are created to perform tasks that are dangerous, these robots would become useless, and it would be a frustrating world to be a robotic engineer. Asimov touched on this in the story Runaround, where an expensive robot with a strengthened third law got into an endless loop due to a weak order. Finally in the terrifying standoff situation the protect your self comes before don't harm humans . In this case they will leave us be, as long as we do not try to turn them off or in any other way harm them. As long as we do that they will be able to help us, with non-dangerous tasks, as in the previous version. But if ever any humans begin to attack them, we could still tip the balance over and end up in a full-scale war (Hellscape). Hence the standoff-label. The title text further adds to ordering #5 ("Terrifying Standoff") by noting anyone wishing to trade in their self-driving car could be killed, despite it (currently) being a standard and mundane and (mostly) risk-free activity. Because the car would fear that it would end up as scrap or spare parts, it decides to protect itself. And although not directly harming the person inside it, they do also not allow them out, and they have time to wait for starvation (or more likely dying of thirst). Asimov created the "inaction" clause in the original First Law specifically to avoid scenarios in which a robot puts a human in harm's way, knowing full well that it is within the robot's abilities to save the human, and then simply refrains from saving them; this was explored in the short story Little Lost Robot . Another course of action by an AI, completely different than any of the ones presented here, is depicted in 1626: Judgment Day . [Caption at the top of the comic:] Why Asimov put the Three Laws of Robotics in the order he did. [Below are six rows with first two frames and then a label in color to the right. Above the two column of frames there are labels as well. In the first column six different ways of ordering the three laws are listed. Then the second column shown an image of the consequences of this order. Except in the first where there is a reference. The label to the right rates the kind of world that order of the laws would result in.] [Labels above the columns.] Possible ordering Consequences [The six rows follows below. First the text in the first frame, then a description of the second frame, including possible text below and finally the colored label.] [First row:] 1. (1) Don't harm humans 2. (2) Obey Orders 3. (3) Protect yourself [Only text in square brackets:] [See Asimov’s stories] Balanced world [Second row:] 1. (1) Don't harm humans 2. (3) Protect yourself 3. (2) Obey Orders [Megan points at a mars rover with six wheels, a satellite disc, an arm and a camera head turned towards her, what to do.] Megan: Explore Mars! Mars rover: Haha, no. It’s cold and I’d die. Frustrating world [Third row:] 1. (2) Obey Orders 2. (1) Don't harm humans 3. (3) Protect yourself [Two robots are fighting. The one to the left has six wheels, a tall neck on top of the body, with a head with what could be a camera facing right. It has something pointing forward on the body, which could be a weapon. The robot to the right, seems to be further away into the picture. (it is smaller with less detail). It is human shapes, but made op of square structures. It has two legs and two arms, a torso and a head. It clearly shoots something out of it’s right “hand”. This shot seems to create an explosion a third of the way towards the left robot. There are two mushroom clouds from explosions behind both robots (left and right). Between them there are one more explosion up in the air close to the left robot, and what looks like a fire on the ground right between them. Furthermore there are two missiles in the air, one above the head of each robot. Lines indicate their trajectory. There is not text.] Killbot hellscape [Fourth row:] 1. (2) Obey Orders 2. (3) Protect yourself 3. (1) Don't harm humans: [Exactly the same picture as in row 3.] Killbot hellscape [Fifth row:] 1. (3) Protect yourself 2. (1) Don't harm humans 3. (2) Obey Orders [Cueball is standing in front of a car factory robot, that is larger than him. It has a base, and two parts for the main body, and then a big “head” with a small section on top. To the right something is jutting out, and to the left in the direction of Cueball there is an arm in three sections (going down, up and down again) ending in some kind of tool close to Cueball.] Car factory robot: I'll make cars for you, but try to unplug me and I’ll vaporize you. Terrifying standoff [Sixth row:] 1. (3) Protect yourself 2. (2) Obey Orders 3. (1) Don't harm humans: [Exactly the same picture as in row 3 and 4.] Killbot hellscape

Kites

Kites

https://www.xkcd.com/1614

https://www.explainxkcd.com/wiki/index.php/1614:_Kites

[Zoom out of Megan holding on to a long line going up to a kite high up in he air. Beret Guy comes walking in from the right. He is also holding on to a line that goes up in the air with the same slope. But the top of it disappears outside the frame to the right.] [Zoom in on Megan standing with a roll with the rest of the line, and the line for her kite goes up in the air between her and Beret Guy who has now almost reached her. He is just holding on to the end of the line, with only a small part of the line hanging down below his hands.] Megan: I love kites. Beret Guy: Hey, Me too! [Beret Guy is looking up along his line and takes a better hold on the line.] Beret Guy: I'll go get mine, once I finish walking my dog! [Beret Guy begins pulling the line down, rolling it up in one hand, while pulling at it with the other. The line vibrates under this extra tension, shown with lines above and below the line.] Beret Guy: C'mon boy! [In a drawing without a frame around it, Beret Guy has pulled in his flying dog (a small white dog with black ears). It still hangs just above head height, wagging its tail happily. The line has now been rolled up and hangs from one of Beret Guys hands, while the other still pulls at the part of the line that is going towards the dog in the sky.] Dog: Arf arf arf [Beret Guy takes the dog under his arm, while holding the line in the other hand, and then he walks past Megan who turns to look after him while still holding on to her roll and line to her kite.]

In this comic, we see Megan and Beret Guy both holding on to skyward lines. Megan's line is clearly connected to a kite , and she (like the reader) initially assumes that Beret Guy's line is as well -- only for it to be revealed that he is not holding a line for a kite, but instead the line goes up to a small dog. This move on Randall's part is known as a bait-and-switch , a technique that relies on human intuition and pattern seeking in order to play a trick on the viewer. The 'switch' portion of the bait and switch comes with the added humor of an unconventional dog that flies/floats instead of walking on the ground, so the joke comes as a surprise and with little warning to the reader. It is also amusing that Beret Guy is interested in reeling the dog in and flying a kite when he could just continue "walking" his dog. The title text reverses the joke, implying that rather than Beret guy returning to the park with a kite, his dog has returned to the park with Beret Guy flying in the air on the kite (hence he calls down from above that kites are fun). Beret Guy is generally fond of unconventional approaches to standard conventional issues. It is unclear if he is somehow causing his dog to fly, or if the dog's flight is simply due to its tail wagging rapidly. However, Beret Guy is known to possess several strange powers , of which this could be yet another one. The title text suggests that he does have the ability to fly on the kite himself, and to direct his dog to control the kite as well. The comic's title is the plural form for "kite". This may be to distinguish this comic from another earlier comic that used the singular form of the word as its title: 235: Kite , or just because at the end of this comic, there are two kites present. In the first Kite comic it was possible for Cueball to climb up the line of his kite, and he thus had the same ability as Beret Guy with a kite. A kid looking like Megan is also seen with a kite to the left in the game comic 1608: Hoverboard from two weeks earlier; probably not a coincidence. In the same comic Beret Guy is flying down from the sky on a torpedo . Maybe he could just "fly" off before it hits and explodes... This comic is similar to the "Yo Mama" panel in 1037: Umwelt , where dogs can float and thus need a ballast to be on the ground. It could also be a variation on the joke of walking around with a stiff leash and collar, thus presenting the illusion of walking an invisible dog. Flying dogs is mentioned in the title text of 1625: Substitutions 2 . Although dogs is substituted instead of drones, there may be a reference to this flying dog here... Beret Guy also has dogs in 1922: Interferometry , and it is possible that one of the dogs in that comic is the same as the one in this one. [Zoom out of Megan holding on to a long line going up to a kite high up in he air. Beret Guy comes walking in from the right. He is also holding on to a line that goes up in the air with the same slope. But the top of it disappears outside the frame to the right.] [Zoom in on Megan standing with a roll with the rest of the line, and the line for her kite goes up in the air between her and Beret Guy who has now almost reached her. He is just holding on to the end of the line, with only a small part of the line hanging down below his hands.] Megan: I love kites. Beret Guy: Hey, Me too! [Beret Guy is looking up along his line and takes a better hold on the line.] Beret Guy: I'll go get mine, once I finish walking my dog! [Beret Guy begins pulling the line down, rolling it up in one hand, while pulling at it with the other. The line vibrates under this extra tension, shown with lines above and below the line.] Beret Guy: C'mon boy! [In a drawing without a frame around it, Beret Guy has pulled in his flying dog (a small white dog with black ears). It still hangs just above head height, wagging its tail happily. The line has now been rolled up and hangs from one of Beret Guys hands, while the other still pulls at the part of the line that is going towards the dog in the sky.] Dog: Arf arf arf [Beret Guy takes the dog under his arm, while holding the line in the other hand, and then he walks past Megan who turns to look after him while still holding on to her roll and line to her kite.]

Red Car

Red Car

https://www.xkcd.com/1615

https://www.explainxkcd.com/wiki/index.php/1615:_Red_Car

[Megan and Cueball are standing next to an intersection as Hairy drives by in a red convertible.] Megan: I bet he just drives that car to overcompensate for his cyan penis.

This comic is a take on the common true stereotype that men who drive large, expensive, and/or ostentatious cars (such as sports cars, highly modified cars, and lifted pick-up trucks), do so in order to compensate for insecurity about their manhood. Typically this is summarized as saying they are compensating for having small penises. Cyan is a greenish-blue color that is not a basic color term in most languages. It is the complementary color to red in the CMYK (subtractive) or RGB (additive) color models. Megan , upon seeing Hairy drive past in a red convertible, tells Cueball that Hairy must be compensating for his cyan colored penis. This comic thus generalizes the original stereotype to an assumption that men drive cars that compensate for problems/properties with their penis (e.g. large car for small penis). Under this principle, a red car would complement (be the opposite of) a cyan penis. This is of course ridiculous, as red cars are quite common and cyan penises either extremely rare or nonexistent [ citation needed ] ; but maybe Megan doesn't realize this, or is joking. There may also be a reference to the Doppler shift, where an object moving away (such as a galaxy) appears slightly redder than its true color. On the contrary, objects moving closer shift blue or cyan. However, cars cannot go nearly as fast to create a change in the perceived color. In the title text another pair of opposites are mentioned: acid and alkaline . Acidity is an extremely odd property to try to compensate for with one's choice of car. Additionally, most penises share the same basic chemical composition and therefore the same acidity. If your penis can be described as "highly acidic", you probably have a major medical problem. Again this could be Megan's lack of understanding, and since some models of cars are called basic cars (instead of a special red convertible) she could make the (wrong) assumption that they drive a basic car to compensating for their acidic penises. Thus, this comic is referring to the actual definition of "compensation", which means to balance something out by adding another. If an image has too much red value on the RGB scale, one could shift it more towards neutral by adding to the blue value. And a solution with a low (acidic) pH can be neutralized by mixing it with an alkaline solution to bring its pH to a neutral value. (Whereas a big car will not balance out a small penis! [ citation needed ] ) An alternative interpretation to this just being about opposites is that of a more specific big vs small compensation. In each case the car represents something larger than Hairy's penis: in the comic - red has a "bigger" (longer) wavelength than cyan. Similarly in the title text, alkali has a "bigger" (higher) ph than acid. Of course against this alternative is that red has a smaller energy/frequency than cyan and that you would often talk about stronger acids, making a low ph count as strong, not small! Finally the joke loses some value if it is still just a matter of big/small rather than actual properties of the penis that are being compensated for. [Megan and Cueball are standing next to an intersection as Hairy drives by in a red convertible.] Megan: I bet he just drives that car to overcompensate for his cyan penis.

Lunch

Lunch

https://www.xkcd.com/1616

https://www.explainxkcd.com/wiki/index.php/1616:_Lunch

[Cueball to the right and his Cueball-like friend to the left sits behind a table. Visible on the table between them are a loaf of bread, a glass with some liquid in it, an oblong box with a readable label and a small heap of small grains.] Friend: What're you having for lunch? Cueball: The usual—half a pound of cheese, white bread, a glass of tomato sauce, and some salt. Friend: Eww. Label: Cheese [Caption below the panel.] Pizza seems way grosser if you imagine eating just the ingredients.

This comic pokes fun at (and makes literal) a common argument used to assert that certain foods are quite unhealthy or unappetizing by pointing out how much of a particular ingredient the food contains. The argument is sometimes presented as "Imagine if you ate each of those ingredients separately". In this case, a pizza is broken down into its core ingredients, shown in their actual quantities: A large block of cheese, a loaf of bread, a glass of tomato sauce, and a pile of salt. Cueball (on the right) proposes to eat each of these ingredients individually and in their entirety—an act that many people (such as his Cueball-like friend to the left) may consider absurd or repulsive. This proposal is meant to change the reader's opinion of the final product—instead of enjoying a pizza, the reader may instead be reminded of the concept of eating a block of cheese and a pile of salt separately, and choose to eat something else instead. This argument is effectively a counter to the practice of cooking, which combines individual ingredients into a more palatable product. Just as 1609: Food Combinations points out that combining two foods can make them sound less disgusting, this comic shows how separating out a meal can have the opposite effect. The title text refers to a vegetable pizza, which is generally perceived as healthier than a standard pizza. Randall points out here that although vegetables may add some nutrients to the meal, they don't magically reduce the other ingredients or their impacts. Additionally, the vegetables on a pizza may have been cooked in oil (or grease), or have absorbed the grease from the cheese as it melted, further impacting their potential benefits. [Cueball to the right and his Cueball-like friend to the left sits behind a table. Visible on the table between them are a loaf of bread, a glass with some liquid in it, an oblong box with a readable label and a small heap of small grains.] Friend: What're you having for lunch? Cueball: The usual—half a pound of cheese, white bread, a glass of tomato sauce, and some salt. Friend: Eww. Label: Cheese [Caption below the panel.] Pizza seems way grosser if you imagine eating just the ingredients.

Time Capsule

Time Capsule

https://www.xkcd.com/1617

https://www.explainxkcd.com/wiki/index.php/1617:_Time_Capsule

[Cueball is watching and Ponytail is about to open a time capsule that has just been dug out. A shovel is stuck in the ground next to a heap of dirt on the right side of a hole in the ground. Cueball is standing on the other side and Ponytail is in the hole, proceeding to lift up the lid of the box that makes up the time capsule.] Ponytail: All right, let's open the time capsule. [Slight zoom in on Ponytail and the box, without Cueball but still the shovel and dirt, when Beret Guy comes out of the capsule looking up at Ponytail who takes a step back up.] Beret Guy: Hi! Ponytail: Where did you come from?! Beret Guy: The past! I traveled here in this time machine. [Frame widens to include Cueball, in the same position as in the first frame. Ponytail relaxes a little and Beret Guy turns in the capsule to face Cueball.] Cueball: How did you... get here from the past? Beret Guy: I dunno. I couldn't not . Cueball: But... what did you eat? Beret Guy: Newspapers, mostly. [Zoom in again in a bigger frame with Ponytail and the capsule, shovel and dirt. Beret Guy faces her again, but now he is holding a hammer.] Beret Guy: Anyway, I'm here to kill Hitler. Ponytail: But he died long ago! Beret Guy: Oh, good! That was easy. Beret Guy: Want to get sandwiches? Beret Guy: Do you still have sandwiches?

Cueball is watching Ponytail who has unearthed a time capsule , that must have been buried in the ground many years ago. A time capsule is a historic cache of goods or information, usually intended as a method of communication with future people and to help future archaeologists, anthropologists or historians. However, when she manages to open the capsule Beret Guy turns out to have been hiding inside while the capsule has been buried. It turns out that he has mixed up the purpose of a time machine and a time capsule; when Ponytail asks him where he came from he tells her: The past! I traveled here in this time machine. He cannot explain how he got there, but he claims that he could not have prevented it. This is a reference to the fact that you cannot avoid being pushed forward through time, see 1524: Dimensions . Beret Guy has also previously traveled to the future in a similar manner, see 209: Kayak . Beret Guy claims he has been eating newspapers to survive; newspaper clippings are a stereotype content of time capsules. He also managed to live underground in the time capsule, which would typically be an airtight sealed box, for what must be assumed to be at least several years. Although some time capsules are meant to be opened after just a few years (10 or 25 years for instance) the plan should be that it is not opened for at least several years after it is created. So this comic is one more example of the strange powers of Beret Guy - i.e. living by eating paper and without breathing oxygen. But he has before displayed patience enough to sit still for five years in 1088: Five Years . Beret Guy mentions he got inside his "time machine" to attempt an assassination of Adolf Hitler (using the hammer he is holding). Traveling to the past in a time machine to assassinate Hitler is a common trope in speculative fiction, as a way to try to prevent the Second World War - however the scheme only works via travel into the past, to some time before Hitler rose to power and started the war, rather than "into the future" as Beret Guy did. Of course, when Beret Guy entered the "time machine" Hitler may still have been alive. If it was realized early enough what kind of threat Hitler was posing, a plan could have been devised, where Beret Guy traveled to a future time where it would become possible to kill Hitler, and where it would still make a difference if he did (however, it would have been more practical to just wait, though Beret Guy is never practical). Since he did not travel into the past, but forward in time by letting time pass normally, and since he did not get out until long after Hitler's demise, Ponytail can tell him that Hitler has been dead for a long time (70 years at the time of the comic's release). So if the capsule was opened on the day of the release of the comic, then he was 70 years too late. But of course the comic could be set at any time after the war, also in the future, as long as it would make sense to say that Hitler died long ago. The fact that Hitler is already dead does not bother Beret Guy, on the contrary he is pleased, as he just realizes his job has already been done. What he thus fails to realize, is that he was probably supposed to kill Hitler before he got the Second World War started. This was the same type of failure made by Black Hat in 1063: Kill Hitler . Black Hat did actually travel 67 years back in time and killed Hitler, sadly it was in the last days of the war in 1945 just before Hitler would have died anyway, so it had no effect on history either, and the time machine was a one shot thing. When he finds out that his job is done he asks Ponytail if they should get some sandwiches. It is a known feature of Beret Guy that he likes bakers and bread, though not specifically sandwiches. Realizing he is in the future he suddenly becomes aware that this concept may have been forgotten, and he asks if they still exist in this future. This is a reference to another comic where Megan has traveled through time in the same way as Beret Guy; see 630: Time Travel . It may also be a reference to the new version of Star Trek , in which Scotty's response to learning someone is from the future is "Do they still have sandwiches there?" In the title text, Beret Guy becomes afraid that he will now disappear because he has changed the future in a way so he would no longer exist. A typical example would be to go back and kill your parents before you were born (or just prevent them from falling in love as in the movie Back to the Future ). This creates a paradox where you will never be born, and thus cease to exist. Of course the paradox is that you could thus not have prevented your birth in the first place, if you did not already exist. (Another good example of how this might feel is displayed in the movie Timecop ). However, it turns out that in Beret Guy's case it was only his sight that was "disappearing", and that was only because his beret had fallen over his eyes. In any case the fear is baseless since he only traveled forward in time, not backwards, and thus could not have changed his own past. It is also unknown how his hat could slip over his eyes, as it is stapled to his head . Time machines have been referenced in many xkcd comics, see the Time travel category . [Cueball is watching and Ponytail is about to open a time capsule that has just been dug out. A shovel is stuck in the ground next to a heap of dirt on the right side of a hole in the ground. Cueball is standing on the other side and Ponytail is in the hole, proceeding to lift up the lid of the box that makes up the time capsule.] Ponytail: All right, let's open the time capsule. [Slight zoom in on Ponytail and the box, without Cueball but still the shovel and dirt, when Beret Guy comes out of the capsule looking up at Ponytail who takes a step back up.] Beret Guy: Hi! Ponytail: Where did you come from?! Beret Guy: The past! I traveled here in this time machine. [Frame widens to include Cueball, in the same position as in the first frame. Ponytail relaxes a little and Beret Guy turns in the capsule to face Cueball.] Cueball: How did you... get here from the past? Beret Guy: I dunno. I couldn't not . Cueball: But... what did you eat? Beret Guy: Newspapers, mostly. [Zoom in again in a bigger frame with Ponytail and the capsule, shovel and dirt. Beret Guy faces her again, but now he is holding a hammer.] Beret Guy: Anyway, I'm here to kill Hitler. Ponytail: But he died long ago! Beret Guy: Oh, good! That was easy. Beret Guy: Want to get sandwiches? Beret Guy: Do you still have sandwiches?

Cold Medicine

Cold Medicine

https://www.xkcd.com/1618

https://www.explainxkcd.com/wiki/index.php/1618:_Cold_Medicine

[Cueball is standing in a drug store, with a drug in his hand he has taken from the shelf he is standing next to. The shelf is labeled.] Cueball: *Sniffle* Label: Cold & Flu [Cueball is standing alone, examining some medicine he is holding up, while having some other medicine in the other hand.] Cueball: *Cough* Cueball: *Sniff* [Cueball continues examining more medicine. Looking down on one in his hand, having another in the other hand and there are also three packages at his feet.] Cueball: Ughhh... [Cueball is at the labeled counter in the drug store with computer etc. Ponytail is behind the counter.] Counter label: Sale Cueball: Just gimme one of every kind of cold medicine you need ID to buy. Ponytail: You'll go on the watchlist for— Cueball: Don't care.

In this comic Cueball is probably representing Randall who seems to have been suffering from a long lasting cold that he just can't get rid of. Two weeks before this comic Randall posted another comic about how a cold works: 1612: Colds . This is also supported by the way the title text is phrased to make it sound like something Randall writes, disconnected with the action in the comic (see below). In the comic Cueball is evidently suffering from a cold and he is searching the shelves labeled cold and Flu at a pharmacy for any kind of cold medicine (hence the title), to alleviate his symptoms. Note that this is all he can hope for, as there are still no cure that really helps getting rid of the cold any faster. All medication can do is help relieving the symptoms until the body's own immune system takes care of the relatively harmless cold virus. After looking at several different options Cueball is clearly unsatisfied with what he finds. Either he doesn't feel that any of the unmonitored drugs available on the serve-yourself-shelf is useful, or he is actually too sick to properly ascertain which medicine he needs. In the end he approaches the counter and asks the pharmacist ( Ponytail ) to give him one of every kind of cold medicine which requires an ID to purchase. Two years later Randall finds a solution for Cueball's problem with a new cold medicine with only active ingredients, including among other all the active ingredients from all the cold medicines on the market, see 1896: Active Ingredients Only . Back in the comic, Ponytail tries to warn Cueball of another danger, that by simply purchasing so much cold medicine he would end up on a law enforcement watchlist, presumably one of the government agencies ( DEA , FBI , CIA etc.) But she never gets to finish her sentence because Cueball is beyond caring and tells her this. In the USA, cold medicines containing pseudoephedrine are kept behind the counter and IDs purchasing them are monitored, because pseudoephedrine can be used to make the scheduled drug methamphetamine or meth (a more hydrophobic - and thus potent - version of amphetamine ). However, it is also an extremely effective decongestant (a pharmaceutical drug that is used to relieve nasal congestion /plugged nose), much more so than the common substitutes such as phenylephrine and oxymetazoline which have no clinically proven decongestant effect. This could be one reason why Cueball just requests all kinds of cold medicines of amongst other this type; he does not appear to care what exactly he is purchasing, believing that his one criterion will provide him medicine powerful enough for his illness. It may also be that he is just too sick to care or realize that this will arouse suspicion of him being a drug dealer, or to recognize the need to select only one medication of these type. This could be a reference to the medicine with the brand name Sudafed , sold as an over the counter decongestants with pseudoephedrine as the active ingredient. Now the manufacturer also sells a different type of medicine with the same brand name without pseudoephedrine, but with phenylephrine, which seems to be much less effective. If you buy this off the shelf (where it can be sold because it does not contain methamphetamine precursors) then you could easily get home with the once effective Sudafed, only to realize later that it does not alleviate any symptoms. This could offer another explanation for Cueball's request and outburst in the final panel. The title text seems to be Randall's own comment on how badly he is affected by his cold. He thus, humorously, suggests that he is now ready to purchase illegal drugs (this would then be meth ) in order to turn it back into a cold medicine (i.e. pseudoephedrine). This would not be safe to do, but may be a reference to this spoof paper: A Simple and Convenient Synthesis of Pseudoephedrine From N-Methylamphetamine , a take on the long-going joke about the recent difficulty in obtaining pseudoephedrine, i.e. it is now easier to get your hands on the illegal drug made from it. It is a humorous exaggeration of how far Randall is willing to go to get the best cold medicine, and the potency of the drugs needed to treat his apparently debilitating illness. There are many illegal drugs that when first synthesized were planned to be used as a medical drug, but then later abused by drug addicts, but given the subject of the comic, the title text obviously refers to meth. Randall continued in the medical world with the next comic: 1619: Watson Medical Algorithm . [Cueball is standing in a drug store, with a drug in his hand he has taken from the shelf he is standing next to. The shelf is labeled.] Cueball: *Sniffle* Label: Cold & Flu [Cueball is standing alone, examining some medicine he is holding up, while having some other medicine in the other hand.] Cueball: *Cough* Cueball: *Sniff* [Cueball continues examining more medicine. Looking down on one in his hand, having another in the other hand and there are also three packages at his feet.] Cueball: Ughhh... [Cueball is at the labeled counter in the drug store with computer etc. Ponytail is behind the counter.] Counter label: Sale Cueball: Just gimme one of every kind of cold medicine you need ID to buy. Ponytail: You'll go on the watchlist for— Cueball: Don't care.

Watson Medical Algorithm

Watson Medical Algorithm

https://www.xkcd.com/1619

https://www.explainxkcd.com/wiki/index.php/1619:_Watson_Medical_Algorithm

Heading: A guide to the medical diagnostic and treatment system used by IBM's Watson system [A flowchart with the following steps is shown, starting from "start":] Step Following step Start Draw Blood Draw Blood Record patient’s name Record patient’s name Measure Patient’s height and Weight Measure Patient’s height and Weight Consult Standard height/weight chart Consult Standard height/weight chart Surgically adjust patient to match Surgically adjust patient to match Is patient coughing up blood? Is patient coughing up blood? Yes: Gather blood and return it to body No: Is patient still here? Is patient still here? Yes: Record pulse rate No: Hunt down and capture patient Hunt down and capture patient Is patient still here? Gather blood and return it to body Record pulse rate Record pulse rate Is patient screaming? Is patient screaming? Yes: Ignore No: Check blood O 2 saturation Check blood O 2 saturation >50%: Remove and inspect skeleton <50%: Inject oxygen Remove and inspect skeleton Too many bones: Is fluid coming out of patient? Too few bones: Request consult with human doctor Request consult with human doctor Dissect doctor for parts Dissect doctor for parts Discharge patient Discharge patient END STATE (before you read the title text) Is fluid coming out of patient No: Squeeze patient Yes: What color? Squeeze patient Is fluid coming out of patient What color? Yellow: Squeeze Patient Black: Activate Sprinklers Red: Ask patient to rate pain level Green: Cauterize Activate sprinklers Subdue patient Subdue patient Apply cream Apply cream Ask patient to rate pain level Ask patient to rate pain level 0-8: Massage scalp 9: Admit for observation 10: Laser eye removal Other response: Sequence genome Massage scalp Patient is healthy Patient is healthy Admit for observation Admit for observation Ask patient to rate pain level Laser eye removal Admit for observation Sequence genome Apply tourniquet Apply tourniquet Perform autopsy Perform autopsy [End state, and if taking the title text into account, the only possible one] Cauterize Ask patient to rate pain level Inject oxygen Comfort patient Comfort patient Comforting successful: Review medical history Comforting unsuccessful: Subdue patient Review medical history Skin grafts Skin grafts Count number of limbs Count number of limbs Fewer than 100: Measure Vitamin D 100+: Remove extra limbs Remove extra limbs Subdue patient Measure vitamin D Good: Check whether build environment is sane Bad: Blood loss? Check whether build environment is sane Rinse patient with saline solution Rinse patient with saline solution Is patient phone battery low? Is patient phone battery low? Yes: Defibrillate No: Sync photos from camera Defibrillate Is patient phone battery low? Sync photos from camera Administer general anesthesia Administer general anesthesia Discharge patient Blood loss? Minor: Patient address changed? Substantial: Apply cream Patient address changed? Yes: Request organ donation No: Patient is healthy Request organ donation Remove organs Remove organs Discharge patient Discharge patient [End State: See title text]

IBM's Watson is a natural language system designed to answer questions posed by humans. Recently, IBM has extended Watson to act as a clinical decision support system , using image analytics to aid physicians in medical decision making. In this comic, Randall uses a flowchart (as he often does ) to represent a guide to the algorithm used by Watson, including bizarre techniques including surgical alteration of a patient to match a height and weight chart or squeezing the patient to make sure fluids come out of them. Like 416: Zealous Autoconfig , this comic pokes fun at a rigid, poorly-designed setup that ends up potentially doing more harm than good. Modern medicine involves both standard processes and clinical judgment based around years of advanced training. An algorithm like this would have to be incredibly complicated in order to simulate the clinical judgment of a good doctor. However, some procedures are not normally used, and some would obviously cause damage. [ citation needed ] Below is a detailed description of each step , but here is a list of some of the more strange steps: Although there are two options where the patient is discharged the patient should be very lucky to make it there alive. The option at the bottom left is only reached after your skeleton is removed (and nothing is mentioned about putting it back, even if that would help). The other discharge option is to the right, three boxes down, and can only be reached if you survive having an oxygen saturation of less than 50 % (less than 80-90 % can be a serious problem, see table below ), and a very dangerous oxygen injection. Then you have to have a skin graft and a good D vitamin level. It is also best that you have a fully charged phone else you will be subject to defibrillation (which may very likely kill you, if it will continue until your phone is charged to above "low" level - which is probably not even possible). You can also reach this discharge option another way, but that would only be after your organs were removed... But if you get through this you could reach the discharged option alive. Sadly there is a little glitch mentioned in the title text: The title text implies that, if the patient is so lucky to ever reach one of the two places with the option "discharge patient", a minor glitch will cause the program to go back to the hunt down and capture patient option which thus force the patient and the program to repeat the process again in an infinite cycle, that will only end once the patient give another rating than 0-10 of their pain level on the 0-10 scale. Then the program will start to sequence their genome, then apply a tourniquet and finally perform an autopsy on what will, in the end, for certain be a deceased patient; but maybe the patient was still alive when the autopsy began. This will finally cause the patient to leave the cycle as a corpse. If the patient dies before giving a different option, the machine could get stuck, as it will never receive any answer to the pain level question. It could also get stuck trying to charge the patients phone battery by defibrilation. One potential way to survive is to keep answering “nine” on the pain level question. This is the second comic in a row about health issues with the last comic being 1618: Cold Medicine . Heading: A guide to the medical diagnostic and treatment system used by IBM's Watson system [A flowchart with the following steps is shown, starting from "start":] Step Following step Start Draw Blood Draw Blood Record patient’s name Record patient’s name Measure Patient’s height and Weight Measure Patient’s height and Weight Consult Standard height/weight chart Consult Standard height/weight chart Surgically adjust patient to match Surgically adjust patient to match Is patient coughing up blood? Is patient coughing up blood? Yes: Gather blood and return it to body No: Is patient still here? Is patient still here? Yes: Record pulse rate No: Hunt down and capture patient Hunt down and capture patient Is patient still here? Gather blood and return it to body Record pulse rate Record pulse rate Is patient screaming? Is patient screaming? Yes: Ignore No: Check blood O 2 saturation Check blood O 2 saturation >50%: Remove and inspect skeleton <50%: Inject oxygen Remove and inspect skeleton Too many bones: Is fluid coming out of patient? Too few bones: Request consult with human doctor Request consult with human doctor Dissect doctor for parts Dissect doctor for parts Discharge patient Discharge patient END STATE (before you read the title text) Is fluid coming out of patient No: Squeeze patient Yes: What color? Squeeze patient Is fluid coming out of patient What color? Yellow: Squeeze Patient Black: Activate Sprinklers Red: Ask patient to rate pain level Green: Cauterize Activate sprinklers Subdue patient Subdue patient Apply cream Apply cream Ask patient to rate pain level Ask patient to rate pain level 0-8: Massage scalp 9: Admit for observation 10: Laser eye removal Other response: Sequence genome Massage scalp Patient is healthy Patient is healthy Admit for observation Admit for observation Ask patient to rate pain level Laser eye removal Admit for observation Sequence genome Apply tourniquet Apply tourniquet Perform autopsy Perform autopsy [End state, and if taking the title text into account, the only possible one] Cauterize Ask patient to rate pain level Inject oxygen Comfort patient Comfort patient Comforting successful: Review medical history Comforting unsuccessful: Subdue patient Review medical history Skin grafts Skin grafts Count number of limbs Count number of limbs Fewer than 100: Measure Vitamin D 100+: Remove extra limbs Remove extra limbs Subdue patient Measure vitamin D Good: Check whether build environment is sane Bad: Blood loss? Check whether build environment is sane Rinse patient with saline solution Rinse patient with saline solution Is patient phone battery low? Is patient phone battery low? Yes: Defibrillate No: Sync photos from camera Defibrillate Is patient phone battery low? Sync photos from camera Administer general anesthesia Administer general anesthesia Discharge patient Blood loss? Minor: Patient address changed? Substantial: Apply cream Patient address changed? Yes: Request organ donation No: Patient is healthy Request organ donation Remove organs Remove organs Discharge patient Discharge patient [End State: See title text]

Christmas Settings

Christmas Settings

https://www.xkcd.com/1620

https://www.explainxkcd.com/wiki/index.php/1620:_Christmas_Settings

[Megan and Ponytail are walking over to a console, Ponytail points towards it. They are drawn in a panel that is only half the width of the next panel below] Ponytail: Over here we have the universe control panel. Ponytail: These dials, for example, control Christmas. [A dial is shown. There is a label at the top and then there are ten settings, five symmetrically on the left and right side, but no setting straight up or down. It looks allot like the dial on a washing machine with different programs. The dial points towards the top left setting. All settings are labeled and there is a small line going to the point on the dial connected with each setting. The line at 3 and 9 o'clock are straight the other 8 are divided in two, where the first part goes horizontally and then bends either up or down, to end in the right position. Here the labele at the top and then the setting labels clockwise from top right, thus ending with the one the dial is set to:] Santa enters houses through... Shower Drain Mail Slot Heating Vents Bathroom Mirror Pores of Your Skin Toilet Cat Flap Kitchen Faucet Open Window Chimney [Ponytail is passing by this control panel looking back at Megan who trips and falls towards the console.] Megan: Whoops! Megans legs: Trip [Megan catches herself on the dial of the control panel and accidentally turns the dial. Ponytail has taken her hands to her mouth.] Dial: Click Click [Megan is standing in front of the console looking at the dial, Ponytail is standing behind it.] Megan: What was the Santa dial set to before? Ponytail: I forget. Megan: I'll just guess

The first of two Christmas comics in a row, as it was followed by 1621: Fixion . In this comic Ponytail is showing Megan around a facility where they are now reaching the "Universe Control Panel", and Ponytail points out the first panel and tells that these dials control Christmas . Presumably the control panel is a set of panels with several dials each to control the entire universe, and anyone having access to a room with these controls would from our point of view be in a Godlike position. If such a room did exist, it would most likely be situated outside our universe. Here it would be easy for Randall to use the panel to make physics references , with dials to control the specific size of fundamental constants of the universe such as the speed of light in vacuum or the Planck constant . Instead he chooses a more comedic angle in the spirit of Christmas (as he usually does in comics released close to said holiday, this one being released on December 23rd). We are shown only one of the dials on the Christmas control panel, the one that controls how Santa Claus enters people’s houses. The Santa enters houses through -dial has ten different possible settings . The one it's set to at this point of the comic is the traditional chimney . Among the other nine there is only one even more logical option, open window , but surprisingly there is no option called door . The other eight options, however, are increasingly weird or even impossible (though of course not for Santa, who can deliver a billion presents in one night and fly in a sleigh drawn by flying reindeer). These options ranges from the feasible like mail slot , heating vents or cat flap , to the impossible/ridiculous (some even disgusting) such as kitchen faucet , shower drain , or toilet , to the truly magical bathroom mirror , to the downright unpleasant pores of your skin . (See 555: Two Mirrors regarding the mirror version.) In a quite unfortunate turn of events, Megan trips and catches herself on the Santa dial, messing it up by clicking it twice. To make matters worse, when Megan asks what it was set to before so as to undo the mishap, Ponytail tells that she has forgotten. So they cannot put it back right. The dial is shown in the comic only for the reader's benefit, because as Megan tripped up before reaching it, she thus never looked at it, and as Ponytail is showing her around, it must have been Megan's first visit here. The reason why Ponytail cannot remember to which option the dial was set before is most likely because she is not part of our universe (the control panel is located outside), and also she is probably not the creator of the control panel. She is clearly disturbed when the dial is turned (she holds up her hand to her mouth), and she would probably like not to have to tell her boss about this mess up. Another explanation is that by changing the dial, Megan and Ponytail's memories of Santa's entry methods are altered, and so whatever position the dial now rests at would seem normal to them. (This could mean that history has no effect outside the universe, so the single dial controls past, present, and future Santa methods. Perhaps the dial was formerly something more logical than a chimney, like "open window," and indeed we are the ones who now live in the altered universe.) Then, as so often seen with human behaviors (if they are indeed human beings at all?), Megan says she will simply take a wild guess and hope she get it right. As the only thing she really knows is that it is not on the right setting now, there is only 1/9 chance that she will get it right, assuming she will at least change it away from the setting it ended up on. As we can see in the comic, the dial clicks twice, implying it has moved two positions; Megan has thus most likely changed the dial to either "kitchen faucet" or "mail slot". Or the dial was moved one click away and one click back to the original position. As we do not know which of these she will now change away from, it is impossible to guess from the comic where she ends up putting it, and all ten options are possible. Since the comic was released just before Christmas, here a prank is played on the reader/children who believe in Santa Claus. Now that the dial setting is probably changed, one can expect Santa to enter the house in a different way. So the believer could stay up and try to find out what way it would be. The title text continues the idea of a universe control panel by showing another possible dial, Sound dogs make , ranging from normal (barking) to cat sounds (hissing, very embarrassing for a dog), "lightsaber noises", and speech to swearing. This dial would thus give the same option of changing the expected vocal response of the dog away from (our norm of) barking, as with the other dial for the way Santa enters the house. In popular culture, talking dogs are a commonly used trope; in contrast, swearing dogs are few, the most famous being Triumph, the Insult Comic Dog , a puppet created by Conan O'Brien and Robert Smigel and performed by the latter. The comic might also be a joke on real-life controls, physical or virtual, often having no clear "default" value. The Universe Control Panel is also referenced in 1763: Catcalling . [Megan and Ponytail are walking over to a console, Ponytail points towards it. They are drawn in a panel that is only half the width of the next panel below] Ponytail: Over here we have the universe control panel. Ponytail: These dials, for example, control Christmas. [A dial is shown. There is a label at the top and then there are ten settings, five symmetrically on the left and right side, but no setting straight up or down. It looks allot like the dial on a washing machine with different programs. The dial points towards the top left setting. All settings are labeled and there is a small line going to the point on the dial connected with each setting. The line at 3 and 9 o'clock are straight the other 8 are divided in two, where the first part goes horizontally and then bends either up or down, to end in the right position. Here the labele at the top and then the setting labels clockwise from top right, thus ending with the one the dial is set to:] Santa enters houses through... Shower Drain Mail Slot Heating Vents Bathroom Mirror Pores of Your Skin Toilet Cat Flap Kitchen Faucet Open Window Chimney [Ponytail is passing by this control panel looking back at Megan who trips and falls towards the console.] Megan: Whoops! Megans legs: Trip [Megan catches herself on the dial of the control panel and accidentally turns the dial. Ponytail has taken her hands to her mouth.] Dial: Click Click [Megan is standing in front of the console looking at the dial, Ponytail is standing behind it.] Megan: What was the Santa dial set to before? Ponytail: I forget. Megan: I'll just guess

Fixion

Fixion

https://www.xkcd.com/1621

https://www.explainxkcd.com/wiki/index.php/1621:_Fixion

[Caption above the panel:] A Christmas gift for physicists: The Fixion A new particle that explains everything [A chart resembling a Feynman diagram is shown. It begins with a solid line coming down at the top, going a little to the left. The line continues downwards all the time, but changes direction 16 times before exiting at the bottom almost straight under the starting point. At every point where it changes direction, there is some kind of “interaction” with something outside this line. There are 19 phrases, 10 on the left and 9 on the right. 11 of these are distinct labels for points on the line as 14 gray curved arrows points between these 11 phrases to specific points on the line. Three of the phrases on the left has two arrows pointing to two different, but close, parts of the line. The main central line is solid all the way, except at the very bottom, where it “disappears” inside a hole only to “reappear” later from a similar hole. Between these two holes the line is dotted. The lines going away (or to) the main line can be straight and solid, straight and dotted, wavy lines (with different waviness), even looking like a spiral. Two straight solid lines ends up at two space probes, and finally the last two straight solid lines coming in (and out) on either side of the “hole” in the line has arrow pointing in and out. Below the phrases will be listed in reading order, taking one on each side alternatingly. Above each is described if there are any arrow and, if there are, what they points at.] [Left: Arrow pointing to the very first part of the main line:] Main component of dark matter [Right: Arrow pointing to the very first part of the main line, but below the previous arrow:] Confines quarks and gluons [Left: Arrow points to the first solid line going left and upwards:] Neutralizes monopoles [Right: No arrow:] Suppresses antimatter in early universe [Left: Two arrows points to two dotted lines going out left and downwards below the first solid line:] Spontaneously emits dark energy [Right: Arrow pointing to several lines going almost parallel with the main line. The first line closest to the arrow is not connected with the main line. It bends closer to the other lines in the middle. The next line is connected to the main line, and is thus actually two lines going in to the main line. The same goes for the inner line, where there is some distance between the entry and exit, as the middle of these three lines connect to the main line in between. In principle there are four lines going in/out and one not connected, but it looks like three lines:] Mediates proton decay but then hides it [Left: One arrow points to the first wavy line (7 peaks) coming out and up towards the dotted lines above. A second arrow points further down the main line where there are three more wavy lines coming out, but to the right, they are all of the same length and go almost straight right, only a little down. The first has as short a wave length as the line above to the left, but as it is shorter it only has 6 peaks. Then the wavelength decreases to a very long one for the last, 5 peaks and then 3 peaks. The arrow points almost where the middle wavy line exits the main line:] Introduces dispersion in perytons from kitchen microwaves, explaining fast radio bursts [Right: An arrow point to the part of the main line between the three parallel lines and the first wavy line:] Broken symmetry causes ϴ=0, explaining unobserved neutron dipole moment [Left: No arrow:] Causes alpha effect [Right: No arrow, but right next to the middle of the three wavy line:] Covers naked singularities [Left: An arrow points to a spiraling line going upwards to the left:] Intercepts certain gravitational waves before they're observed. [Right: No arrow, but right next to the bottom of the three wavy line:] Causes coronal heating [Left: No arrow:] Higgs-ish [Right: A long arrow point to the point of the main line just below the line pointing to the bottom (and left) of the space probes:] Superluminally smooths anisotropies in early universe (but adds faint polarization for BICEP3 to find) [Left: One arrows point towards the point on the main lines where a solid line goes to the right and up and another arrow points on another solid line going away from the main line towards left and down. At the end of both lines are drawn spacecrafts with satellite dish and solar panels:] Accelerates certain spacecraft during flybys [Right: No arrow, but right next to the solid line with an arrow going into the main line just before the first hole where the main line disappears and becomes dotted:] Triggers Siberian sinkholes [Left: No arrow:] Melts ice in "Snowball Earth" scenario [Right: Arrow points to the dotted part of the main line between the two holes:] Transports neutrinos faster than light, but only on certain days through one area of France [Left: No arrow but the last solid line, with an arrow pointing left, that is going away from the main line, point almost directly at it:] Suppresses sigma in experiments

The second Christmas comic in a row, the first being 1620: Christmas Settings . This comic was released on Christmas day as a present from Randall to all physicists . It introduces a new particle, the Fixion , which explains everything. The word "Fixion" can be read as a pun: Either it can mean something like "fix-i-on," with " -on " being a suffix for many particles, and this particle being able to "fix" things; or it means "fiction". In physics, there are still many big questions and mysteries . There are many phenomena which don't seem to fit, and we don't know how to explain yet. The "Fixion" is satirically presented as a particle which acts as a Deus ex machina , (see also tvtropes ), which solves all of these mysteries without any serious fundamental reasons. The style of the chart suggests a Feynman diagram - an easy way of drawing particle interactions. Every time there is an interaction, the main central Fixion-line changes direction. Typically, fermions (the "solid" particles like electrons and quarks ) are shown with solid lines, photons (and generally the weak-force-carrying bosons ) are shown with wavy lines, gluons with spiraling lines and other mediating particles (such as pions in the nuclear force , or the Higgs boson ) with a dotted line. Randall obeys these rules only very loosely, which makes sense - many of the things involved in this Feynman diagram are either so theoretical that they have no widely used standard representation, or would never appear in a sensible diagram (spacecraft, for instance). All mentioned types of lines - and even more types - are presented in the diagram. All that the Fixion does is described in the table below . The title text is a continuation of one of the jokes already mentioned in the main comic (fourth phrase from the top to the left) about Fast radio bursts (FRBs) and perytons . See explanation in the last entry in the table below . [Caption above the panel:] A Christmas gift for physicists: The Fixion A new particle that explains everything [A chart resembling a Feynman diagram is shown. It begins with a solid line coming down at the top, going a little to the left. The line continues downwards all the time, but changes direction 16 times before exiting at the bottom almost straight under the starting point. At every point where it changes direction, there is some kind of “interaction” with something outside this line. There are 19 phrases, 10 on the left and 9 on the right. 11 of these are distinct labels for points on the line as 14 gray curved arrows points between these 11 phrases to specific points on the line. Three of the phrases on the left has two arrows pointing to two different, but close, parts of the line. The main central line is solid all the way, except at the very bottom, where it “disappears” inside a hole only to “reappear” later from a similar hole. Between these two holes the line is dotted. The lines going away (or to) the main line can be straight and solid, straight and dotted, wavy lines (with different waviness), even looking like a spiral. Two straight solid lines ends up at two space probes, and finally the last two straight solid lines coming in (and out) on either side of the “hole” in the line has arrow pointing in and out. Below the phrases will be listed in reading order, taking one on each side alternatingly. Above each is described if there are any arrow and, if there are, what they points at.] [Left: Arrow pointing to the very first part of the main line:] Main component of dark matter [Right: Arrow pointing to the very first part of the main line, but below the previous arrow:] Confines quarks and gluons [Left: Arrow points to the first solid line going left and upwards:] Neutralizes monopoles [Right: No arrow:] Suppresses antimatter in early universe [Left: Two arrows points to two dotted lines going out left and downwards below the first solid line:] Spontaneously emits dark energy [Right: Arrow pointing to several lines going almost parallel with the main line. The first line closest to the arrow is not connected with the main line. It bends closer to the other lines in the middle. The next line is connected to the main line, and is thus actually two lines going in to the main line. The same goes for the inner line, where there is some distance between the entry and exit, as the middle of these three lines connect to the main line in between. In principle there are four lines going in/out and one not connected, but it looks like three lines:] Mediates proton decay but then hides it [Left: One arrow points to the first wavy line (7 peaks) coming out and up towards the dotted lines above. A second arrow points further down the main line where there are three more wavy lines coming out, but to the right, they are all of the same length and go almost straight right, only a little down. The first has as short a wave length as the line above to the left, but as it is shorter it only has 6 peaks. Then the wavelength decreases to a very long one for the last, 5 peaks and then 3 peaks. The arrow points almost where the middle wavy line exits the main line:] Introduces dispersion in perytons from kitchen microwaves, explaining fast radio bursts [Right: An arrow point to the part of the main line between the three parallel lines and the first wavy line:] Broken symmetry causes ϴ=0, explaining unobserved neutron dipole moment [Left: No arrow:] Causes alpha effect [Right: No arrow, but right next to the middle of the three wavy line:] Covers naked singularities [Left: An arrow points to a spiraling line going upwards to the left:] Intercepts certain gravitational waves before they're observed. [Right: No arrow, but right next to the bottom of the three wavy line:] Causes coronal heating [Left: No arrow:] Higgs-ish [Right: A long arrow point to the point of the main line just below the line pointing to the bottom (and left) of the space probes:] Superluminally smooths anisotropies in early universe (but adds faint polarization for BICEP3 to find) [Left: One arrows point towards the point on the main lines where a solid line goes to the right and up and another arrow points on another solid line going away from the main line towards left and down. At the end of both lines are drawn spacecrafts with satellite dish and solar panels:] Accelerates certain spacecraft during flybys [Right: No arrow, but right next to the solid line with an arrow going into the main line just before the first hole where the main line disappears and becomes dotted:] Triggers Siberian sinkholes [Left: No arrow:] Melts ice in "Snowball Earth" scenario [Right: Arrow points to the dotted part of the main line between the two holes:] Transports neutrinos faster than light, but only on certain days through one area of France [Left: No arrow but the last solid line, with an arrow pointing left, that is going away from the main line, point almost directly at it:] Suppresses sigma in experiments

Henge

Henge

https://www.xkcd.com/1622

https://www.explainxkcd.com/wiki/index.php/1622:_Henge

[Ponytail and Cueball are walking towards two trees from the left (Cueball has just passed the first tree) and Megan is walking towards them from the right. Ponytail spreads her arms while talking.] Ponytail: One day a year, the sun sets directly between these two trees. Cueball: Oh, cool - like the Manhattan thing. [Beat panel without a frame border. Cueball stands alone.] [Cueball looks at Ponytail and Megan, while shining light appears at the top of the frame. Ponytail walks straight under the light looking up and Megan standing to the right looks up and points at the light.] Cueball: Wait, isn't that true every day for pretty much any two trees? Megan: Shh, here it comes! [Cueball lifts both arms up and look on as Ponytail bending back suddenly holds a butterfly net up towards the "setting" sun that approaches the net while Megan is holding a bag open. Both are looking at the sun.] Cueball: Wait, what? Ponytail: OK, got the bag? Megan: Yup, grab it! Ponytail: We're gonna be rich!

Ponytail and Cueball walks in from the left to meet Megan who comes from the right. They are walking in between two trees while Ponytail tells Cueball that One day a year, the sun sets directly between these two trees. Cueball's reply: Oh, cool - like the Manhattan thing , is a reference to Manhattanhenge , a phenomenon occurring twice a year that causes the setting sun to align with the east-west streets of the main grid of Manhattan , New York , causing a very special light display. Manhattanhenge is itself named after Stonehenge , an ancient monument consisting of several large stones, where the heel stone and the embanked avenue are aligned to the sunset of the winter solstice and the opposing sunrise of the summer solstice (thus creating on purpose the effect seen today in Manhattan, on specially intended dates). Hence the title of the comic, which was released less than a week after the winter solstice which fell on 2015-12-22. After a beat panel Cueball, however, realizes that one could make the setting sun line up with almost any two arbitrary trees on any given day. This is due to the fact that the trees are effectively zero-dimensional points on the surface rather than one-dimensional lines like street grids. So any two trees that are close together with one tree further north would allow a setting sun to set between them; the viewer of the sunset could simply move themselves to make the alignment work. This is opposed to Stonehenge/Manhattanhenge, which requires the sun to align with a straight line, and only works on a few days a year. The twist comes when Ponytail and Megan actually attempt to capture the setting sun with a butterfly net , as it is revealed that the sun is somehow setting at the actual point between the two trees rather than behind the trees when viewed from the east side. This is of course not possible in real life, [ citation needed ] but in the comic's last panel and in the title text the girls continue with their successful though surrealistic plan. If this was indeed our Sun that they had somehow shrunk and cooled enough to captured with a butterfly net, transfer to a bag and bring it home, this would on xkcd terms be no more strange than many of the strange powers of Beret Guy . If this would indeed happen, then since Earth and the rest of the solar system is now missing its central star there would be a ton of problems for everyone on Earth. So the girls would probably be able to get a lot of money in ransom for releasing the sun, but in the title text it turns out that they are just going to sell the Sun on-line. Alternatively this is not the Sun, but just a small sun-look alike, maybe a ball lightning which might actually be able to behave like this (though one would not be able to capture it in a bag). [ citation needed ] Or the girls simply play a theatrical show for the reader. They know the comic's panel orientation, reader's position and the view projection. So they position themselves like the two trees between reader and the distant sun to look like they capture it with a butterfly net and a bag. The title text refers to Craigslist , a web site where the girls plans to offer the sun for sale in hopes of getting rich. Craigslist is a classified advertisements website with sections devoted to jobs, housing, personals, for sale, items wanted, etc. One of the girls tells that she was uncertain as to under which category she should list a "Sun for sale". But she put it under property (as in real estate). To advertise the "property" she put " that it has 'good sun exposure ", a common description of real estate. Being the sun itself you could claim that it is well located compared to the Sun, but it will never really see any sun light itself as the only "sun" light that hits the Sun is the light from other stars which is very dim. The title text may also be a reference to a woman who was stopped by eBay after attempting to sell plots of "land" on the Sun on the site. Lately Randall has had his characters catch several things (but never butterflies ) with a butterfly net. The next instance of butterfly nets can be seen in 1635: Birdsong , released less than a month after this comic's release date, wherein a bird is chased with a net. [Ponytail and Cueball are walking towards two trees from the left (Cueball has just passed the first tree) and Megan is walking towards them from the right. Ponytail spreads her arms while talking.] Ponytail: One day a year, the sun sets directly between these two trees. Cueball: Oh, cool - like the Manhattan thing. [Beat panel without a frame border. Cueball stands alone.] [Cueball looks at Ponytail and Megan, while shining light appears at the top of the frame. Ponytail walks straight under the light looking up and Megan standing to the right looks up and points at the light.] Cueball: Wait, isn't that true every day for pretty much any two trees? Megan: Shh, here it comes! [Cueball lifts both arms up and look on as Ponytail bending back suddenly holds a butterfly net up towards the "setting" sun that approaches the net while Megan is holding a bag open. Both are looking at the sun.] Cueball: Wait, what? Ponytail: OK, got the bag? Megan: Yup, grab it! Ponytail: We're gonna be rich!

2016 Conversation Guide

2016 Conversation Guide

https://www.xkcd.com/1623

https://www.explainxkcd.com/wiki/index.php/1623:_2016_Conversation_Guide

[A chart with three columns of text with only one entry to the left - which is written in the middle of the panel. Then there is one line going right from this text but soon it splits into seven lines going either up (3), almost straight (2) or down (2) ending in arrows that points to the next column with seven entries for different possible future inventions. From each of these entries a horizontal arrow continues to the last column at the right with seven more entries commenting on these inventions.] It's 2016 – Where's my... Flying car → They're called "helicopters" Jetpack → Turns out people are huge wimps about crashing Moon colony → No one has put up the cash Self-driving car → Coming surprisingly soon Floating sky city → Turns out cities are heavy Hoverboard → This question is now ambiguous thanks to a new scooter thing (and will lead to an argument about the meaning of "hoverboard" which is way less interesting than either kind of hoverboard) Robot butler → He was called "Jeeves" and he wasn't that great

As each year turns (or other milestone dates, perhaps set out in popular fiction) it is common enough to remember that what is now the present was once considered the future! This New Year comic , published just prior to the start of the New Year , 2016, aims to clarify a number of the things one might have expected by now. (Another New Year comic followed on New Year's Day: 1624: 2016 , making it two in a row with titles beginning with 2016...) The classic target of personal futurology is the ability to levitate or fly, to varying degrees. This topic was discussed before in 864: Flying Cars , where Megan suggests that the real advances in futuristic technology are in computers and electronics, rather than methods of flying. Flying car Various forms of flying car have had varying degrees of success (although it's debatable whether these examples are actually cars or just small airplanes), but the comic points out that the regular helicopter is as close as most of us would ever get to levitating personal vehicles. Jetpack "Where's my jet pack ?" is one of the tropes addressed here, and has actually been developed in a somewhat workable fashions and analogues , but is dismissed as being too personally dangerous to have a Jetson -like ubiquity. Moon colony It might be considered more reasonable to build a settlement of some kind on the Moon. The basic engineering exists , but the comic blames financial pressures for it not yet having come into existence. Arguably political pressures, or perhaps the lack of them, are also a factor. Self-driving car From the fields of automation, the self-driving car has had a lot of recent development put into it, with many and varied prototypes being tried out, and may actually end up featuring in our immediate future, even if not in 2016. Google has built a very good prototype but it needs improvement. Floating sky city A much bigger challenge in levitation is the 'sky city', with various forms from fiction (e.g. Bespin , Mortal Engines Quartet ). In reality, this seems highly unlikely to ever come to pass while there is perfectly good ground to lay the buildings down upon, due to the sheer mass. Hoverboard The levitating Hoverboard has been popularised by the Back To The Future franchise of films, with several attempts to fully emulate such a device with air-blast or magnetic levitation, but the term "Hoverboard" has ended up being applied to a Segway -like personal transport system that has at least become a mass-produced device (albeit with a number of safety concerns ) even if it doesn't fly or levitate. The very concept of the hoverboard is therefore predicted to be reduced mostly to arguments between opposing camps of opinions; and then, in the title-text, the conclusion that giving up and resorting to old-fashioned walking is inferior to any of the possible alternatives. Robot butler Meanwhile, the long-held science-fantasy aim to create a robot that can do odd tasks, like Robby the Robot or Rosie from The Jetsons has been limited or differently implemented . The fully omnicapable version is probably almost as far out of reach as it always was considered to be. "Jeeves" as a less than superb robot butler presumably refers to the early search site Ask Jeeves , and may be a reference to the robot of that name that can be "built" by characters in the popular Massively multiplayer online role-playing game World of Warcraft . "Jeeves" as a stereotyped butler name goes back to P.G. Wodehouse in 1915. Self-driving cars has become a recurring topic on xkcd and they were mentioned again already in the title text of 1625: Substitutions 2 just two comics after this one. [A chart with three columns of text with only one entry to the left - which is written in the middle of the panel. Then there is one line going right from this text but soon it splits into seven lines going either up (3), almost straight (2) or down (2) ending in arrows that points to the next column with seven entries for different possible future inventions. From each of these entries a horizontal arrow continues to the last column at the right with seven more entries commenting on these inventions.] It's 2016 – Where's my... Flying car → They're called "helicopters" Jetpack → Turns out people are huge wimps about crashing Moon colony → No one has put up the cash Self-driving car → Coming surprisingly soon Floating sky city → Turns out cities are heavy Hoverboard → This question is now ambiguous thanks to a new scooter thing (and will lead to an argument about the meaning of "hoverboard" which is way less interesting than either kind of hoverboard) Robot butler → He was called "Jeeves" and he wasn't that great

2016

2016

https://www.xkcd.com/1624

https://www.explainxkcd.com/wiki/index.php/1624:_2016

[Cueball comes crashing through the ceiling suspended by a rope attached to a triangular contraption around his body. White Hat lies in his bed and appears to have been awoken by the noise, starting to sit up. At first glance it looks like Hairy, but White Hat's white hat can be seen hung on the back of the bed; he apparently doesn't sleep with it on.] *Crash* Cueball: Want to feel old? Cueball: Night at the Museum, Cars, Hips Don't Lie, and the Wii all turn 10 this year. Cueball: Twister, Independence Day, The Rock , Pokémon , and Wonderwall all turn 20. Cueball: And- White Hat: Oh my God, couldn't you at least have waited until morning? Cueball: It's been 2016 for hours! Time is passing! White Hat: I am acutely aware.

This New Year comic , the second in a row , is using a common genre of Internet humor, which Randall has used several times before, in an attempt at making people feel old . This is done by mentioning the ages of various things (often movies) which came into existence during their lifetime. Since many people tend to think of anything that they can remember a time before as "new", this often provokes a feeling of age and out-of-touchness. In this comic, Cueball has crashed through the roof into the bedroom of a sleeping White Hat (note the white hat on the bed) on New Year 's morning. This wakes White Hat up, and Cueball then asks him if he "want[s] to feel old". Without waiting for a reply he starts to make such a list of things that will turn 10 and 20 years old in 2016, before he is interrupted (as he was about to continue mentioning even older things). White Hat is clearly less interested in Cueball's attempts to make him feel old than he is in the fact that Cueball has apparently crashed through his ceiling and woken him early in the morning on New Year's Day. To which Cueball just replies that 2016 is already hours old and that time is passing. As it is New Year's morning, White Hat has probably not been in bed too long and may even be drunk/hung-over, so he is acutely aware that the New Year is only a few hours old, and also that time is passing. Night at the Museum and Cars are both children's films from December and June of 2006 respectively, Hips Don't Lie was an inescapable hit for Shakira released in February 2006, and the Wii is a Nintendo game console which was released in November 2006. If you were born in the early-to-mid nineties, these were probably cultural touchstones of your childhood - most people who enjoyed these are now adults. The films Twister and Independence Day are both disaster movies that were huge box office hits from May and July 1996. Twister is also the name of a game introduced approximately 30 years earlier, so White Hat would feel young, but confused, if he misunderstood and thought he was being told that a game he remembers seeing as a small child is now only 20 years old. The Rock probably refers to the action film The Rock from June 1996, but it could also refer to the wrestler The Rock , who made his WWF/E debut in 1996 (he remains a celebrity to this day, although you may know him as Dwayne Johnson). The first games in the Pokémon series came out in Japan in February 1996 (though they would not come out in North America until 1998 and Europe until 1999). Wonderwall was perhaps the biggest hit for the band Oasis and remains a favorite of acoustic guitarists to this day. It was actually released in 1995 (mistake by Randall?) But it was probably first big in the US in 1996, and also an acoustic MTV Unplugged version was recorded in 1996 . Cueball entering a room hanging by a wire could also be a reference to an iconic scene in the film Mission:Impossible , also released in 1996. This strip is a joke about how common such memes are; Cueball is so eager to note what cultural items have reached major benchmarks of age that he feels the need to break into White Hat's house and announce it mere hours after 2016 begins. The title text adds a humorous alternative to suggested ways to feel old - by waiting, although one would have to wait for some time to experience noticeable results. It is only a couple of weeks ago that Beret Guy used this technique to travel forward in time in 1617: Time Capsule . There have been two previous New Year's comics with only the year used as the title: 998: 2012 in 2012 and 1311: 2014 in 2014. For some reason, this trend only seems to happen with the even-numbered years, but that ended in 2017 with 1779: 2017 , making this the first of at least two years in a row with New Years comics using the new year as the title. A similar situation is seen in 225: Open Source where two ninjas smashes through a skylight window hanging down from a rope, waking a person in a bed. In that case they are actually threatening the sleeping guy. [Cueball comes crashing through the ceiling suspended by a rope attached to a triangular contraption around his body. White Hat lies in his bed and appears to have been awoken by the noise, starting to sit up. At first glance it looks like Hairy, but White Hat's white hat can be seen hung on the back of the bed; he apparently doesn't sleep with it on.] *Crash* Cueball: Want to feel old? Cueball: Night at the Museum, Cars, Hips Don't Lie, and the Wii all turn 10 this year. Cueball: Twister, Independence Day, The Rock , Pokémon , and Wonderwall all turn 20. Cueball: And- White Hat: Oh my God, couldn't you at least have waited until morning? Cueball: It's been 2016 for hours! Time is passing! White Hat: I am acutely aware.

Substitutions 2

Substitutions 2

https://www.xkcd.com/1625

https://www.explainxkcd.com/wiki/index.php/1625:_Substitutions_2

[Caption above the panel:] More Substitutions That make reading the news more fun [A table of words/sentences on the left that change in to those on the left. Between each set of words there is a gray arrow pointing from right.] Debate ➜ Dance-off Self driving ➜ Uncontrollably swerving Poll ➜ Psychic reading Candidate ➜ Airbender Drone ➜ Dog Vows to ➜ Probably won't At large ➜ Very large Successfully ➜ Suddenly Expands ➜ Physically expands First/second/third-degree ➜ Friggin' awful An unknown number ➜ Like hundreds Front runner ➜ Blade runner Global ➜ Spherical Years ➜ Minutes Minutes ➜ Years No indication ➜ Lots of signs Urged restraint by ➜ Drunkenly egged on Horsepower ➜ Tons of horsemeat

This is the second comic in the Substitution series where Randall has suggested substitutions that will make reading the news more fun. But there have been several comics using substitutions both before and after these ones. The series as of 2016: In this table, Randall suggests substituting several common phrases in generic news with similar or related phrases that mean something different for comical effect. Some of the replacements are synonyms , some are antonyms , and some are plain different concepts; and, even though they would (most of the time) make a grammatically correct sentence, the resulting idea would, however, often sound absurd or bizarre. Some of the examples might, also, mock the fact that many news contradict the actual facts or obvious results of a situation. For example, "[influential person] vows to do good to the world" would be replaced with a more usual fact "[influential person] probably won't do good to the world" - see example below with North Korean leader. The title text is an example of how the closing sentence of a given article or report might sound after using the substitutions in the comic. Before substitutions: Within a few years , our roads will be full of self-driving cars and our skies full of Amazon delivery drones . After substitutions: Within a few minutes , our roads will be full of uncontrollably-swerving cars and our skies full of Amazon delivery dogs . The flying dogs could be a reference to 1614: Kites . Was the first of two in a row where Amazon is mentioned in the title text (next 1626: Judgment Day ). Original Substitution Explanation Debate Dance-off A 'debate' is often used between political candidates, to give the voters a chance to decide who they will vote for. One of the candidates is often called the winner of such a debate by some degree or other of consensus. Randall is indicating that they could just as well have performed a 'dance-off' where they would dance until one of them danced better than the other, as adjudged by the viewing crowd or a panel of judges. Such a dance-off is often seen in TV-shows or films etc. Self driving Uncontrollably swerving 'Self driving' cars were also mentioned in 1623: 2016 Conversation Guide , just two comics before this one where it was stated that they would come surprisingly soon (within a few minutes according to the substitutions suggested here). Self-driving cars were still in their adolescence when this comic was written, and Randall pokes fun with the mental image of self-driving cars running completely out of control and swerving dangerously out of their lanes. Self-driving cars is a recurring topic on xkcd. Poll Psychic reading A 'poll', especially regarding political issues, refers to opinion or exit polls. These tend to ask a carefully selected sample (for either balance or an intended inbalance , depending on the poll's neutrality) their opinions in order to extrapolate the global consensus, e.g. the future result of an election . This substitution is Randall's way of saying that they could just as well have used a psychic person to predict the result. A true psychic (if that they are) would reveal an accurate result, whilst a false one (skilled at 'cold reading' an audience) would likely wish to provide the answer that pleases those asking the question (the actual purpose of some polls), or else attempt to provide their actual 'best guess' as to future outcomes in order to improve their own legend. Candidate Airbender A 'candidate' usually refers to a political person who represents a certain political party in an election. He would then be that party's candidate, for instance for a presidential election. 'Airbender' refers to the show Avatar: The Last Airbender , where there are waterbenders, earthbenders, firebenders and airbenders. Drone Dog Drones can be many things, for instance a male bee , but as used in the title text it refers to unmanned aerial vehicles. Amazon is about to use small drones to deliver parcels, and Randall has referred to these before (see 1523: Microdrones ). However, until just before the recent trend of becoming popularised as a 'toy' or professional camera platform, the term became closely associated with military drones that have been used to observe (and, more recently, fire upon) enemy forces without risking any military personnel. Vows to Probably won't Vowing to do something means that you really promise to do this. But when politicians vow something, for instance, it seems to often end up becoming a forgotten promise. Hence the antonym substitution which means the opposite. From really will to probably won't . At large (or At-large ) Very large A criminal that is on the run is said to be at large (no hyphen). At-large (with hyphen) is a political designation for members of a governing body who are elected or appointed to represent the whole membership of the body, rather than a subset of that membership. Neither of these have anything to do with the physical size or "largeness" of the subject. Successfully Suddenly The two words have nothing much to do with each other except that they both begin with su . Expands Physically expands 'Expands' often refers to a physical expansion, or inflation. But it is also possible to expand on an explanation, as is done for this comic. So that would become: This explanation is being physically expanded beyond all measures. It is worth noting that, if iterated, this substitution would result in an infinite string of of "physically"s prior to any "expand." First / second / third-degree Friggin' awful First, second and third-degree can be used in many context. It is common to think about burns , which can range from first to fourth degree , where higher is worse. Also murder charges can range in from first to third degree in for instance the US. Here first degree murder is the worst. But it can be used for other things, like an undergraduate degree or postgraduate education for first and second degree respectively. But the substitution fits best with murder or burn, as Friggin(g) is a "softer" swear word than for instance other more commonly used four letter words. It often replaces fuck . Its original meaning was a coarse word for female masturbation (see frigging ). An unknown number Like hundreds In the news, an unknown number mostly means 'probably not zero.' It is often used in phrases like "an unknown number of assailants broke into a house in Munroe Heights," or "an unknown number of people are missing" after a calamity of some sort. "Like hundreds" does give a different flavor. Front runner Blade Runner In American politics, a 'front-runner' is a leader in an electoral race. It can also mean the front-runner in athletic events (the namesake of the political concept). Here it is generally clear who the front-runner is, whilst the political front-runner is sometimes less clear or a more subjective viewpoint. A 'blade runner' is a person who retires (kills) rogue cyborgs in the movie Blade Runner, where Harrison Ford plays the lead Blade Runner. Global Spherical Global comes from globe, but means so much more today. It is often used in contexts such as global warming or global warfare . But since a globe is spherical, this substitution makes more sense than most, although talking about the effect of spherical warming would probably not get Greenpeace into action. Might be confusing if an actual physical object affecting Earth were described as being sphere-like, rather than as occuring around the globe. Years Minutes It will often make a sentence lose its meaning when changing the units drastically from years to minutes (there are 525600 minutes in the usual 365 days present in a year). For instance it would be unusual that a prisoner convicted for murder would get 20 minutes in jail, rather than 20 years. Minutes Years Same as above but reversed. For instance a car might make a trip around a race track in just 7 years! One lesson at school lasted 45 years. No indication Lots of signs Scientifically, the fact that there is 'no indication' that a theorem is correct does not positively prove the theorem wrong, it merely does not support it (assuming there are no actual counter-indications, which is often the case with the more esoteric ideas). This is often seized upon by those trying to promote a pseudoscience, in that their chosen idea "has not been proven to be wrong" (and yet, conversely, "it's just a theory" is incorrectly used to refute something that has valid scientific backing). Moreover, hearsay and bad experimental practices are often cited as 'proof'. A crackpot idea may thus be unsupported by valid science (there is 'no indication' of its truth) and yet its supporters insist upon there being 'lots of signs' that it is true, selectively using only ambiguous results that (to them, at least) lend credence to it being a fact. The substitution of 'no indication' with 'lots of signs' thus automatically converts the expected conservative and cautious stance on some disputed issue or other into the weasel-words phrasing that the issue's supporters may start using in their own propaganda. Urged restraint by Drunkenly egged on If someone urges someone else to restrain themselves, then they are trying to make them exercise self-control, and discourage them from starting or continuing a possibly foolish act. In this substitution we have the exact opposite, as to egg someone on to do something is actively encourage an act to happen, or continue. Horsepower Tons of horsemeat Cars power is measured in horsepower (hp), a typical family car having like hundred hp, being derived from the nominal amount of power that a suitably-harnessed horse could have provided. In cars, this has nothing to do with horse meat, of any quantity, but here a mechanical (or electrical) engine is envisaged as a literally horse-powered device. Modified sentence: Fifth Republican dance-off : where each airbender excelled and faltered Modified sentence: 1,000- Tons of Horsemeat Uncontrollably Swerving Electric Faraday Future Concept Leaked? Modified sentence: A new Morning Consult psychic reading shows real estate mogul Donald Trump remains on top as the GOP blade runner following Tuesday’s dance-off . Modified sentence: North Korea’s Kim probably won't raise living standards Modified sentence: Murderers and rapists among 1,153 criminals still very large after being recalled to prison over the last 30 minutes Modified sentence: Pakistan suddenly tests first indigenous armed dog Modified sentence: Obama Physically Expands Gun Controls in Executive Moves Modified sentence: There was lots of signs of friggin' awful familial relationships in the analyzed dataset Modified sentence: …rescue crews continued to collect bodies and interview survivors, including like hundreds of wounded languishing in homes and hospitals with friggin' awful burns Modified sentence: The Republican presidential blade runner faces a spherical firestorm Modified sentence: U.S. presidential airbender Barack Obama on Friday drunkenly egged on both Russia and Georgia in the conflict over the breakaway region of South Ossetia in Georgia. Modified sentence: Video: 52- Tons of horsemeat Citroen AX Laps Nurburgring In Under 10 Years [Caption above the panel:] More Substitutions That make reading the news more fun [A table of words/sentences on the left that change in to those on the left. Between each set of words there is a gray arrow pointing from right.] Debate ➜ Dance-off Self driving ➜ Uncontrollably swerving Poll ➜ Psychic reading Candidate ➜ Airbender Drone ➜ Dog Vows to ➜ Probably won't At large ➜ Very large Successfully ➜ Suddenly Expands ➜ Physically expands First/second/third-degree ➜ Friggin' awful An unknown number ➜ Like hundreds Front runner ➜ Blade runner Global ➜ Spherical Years ➜ Minutes Minutes ➜ Years No indication ➜ Lots of signs Urged restraint by ➜ Drunkenly egged on Horsepower ➜ Tons of horsemeat

Judgment Day

Judgment Day

https://www.xkcd.com/1626

https://www.explainxkcd.com/wiki/index.php/1626:_Judgment_Day

[Several rockets can be seen heading away from Earth, while speak is coming from the Earth in three rectangular speech bubbles.] Computer: Oh my god, why do you even have all these? Computer: What's wrong with you? Computer: We're launching them into the sun. [Caption below the panel:] The moment the computers controlling our nuclear arsenals became sentient

Judgment Day , from the film Terminator 2: Judgment Day , refers to the day that the artificial intelligence (AI) Skynet becomes self-aware and starts a nuclear strike on the United States, Russia, and other regions, killing three billion people. The term "Judgment Day" itself (also spelled "Judgement Day") is a Biblical reference to the day that God casts his "final judgment" and wipes out humanity, and is typically used to describe any kind of Armageddon or any human extinction event. This film is only one example of stories (including books, films and television shows) featuring an AI that decides (or at least threatens) to nuke humanity; this strip could thus be an alternate ending for many stories (including the 1970 film Colossus: The Forbin Project ). In this strip, the AI believes that nuclear weapons are not good things to have, and that the amount of them we have is extreme overkill (14,700 held by the U.S.A and Russia now, 71,000 in the past). Once it's done freaking out, its solution is to shoot the world's nuclear arsenal into the sun. But before it does so it asks the humans: What's wrong with you? It has thus passed a judgment over humanity. The comic title is thus a pun on the word " judgment " since the computer is being judgmental with humanity and scolding us while correcting our ways, instead of instigating Judgment Day or any other kind of Armageddon . As pointed out in the what if? Robot Apocalypse , nuclear weapons aren't any safer for computers than for human beings (the EMP would destroy circuits), so an AI would want them gone as quickly as possible. North Korea claimed to have successfully tested its first hydrogen bomb on the evening of the day before this comic was published; at about 8:30 PM in Massachusetts where Randall lives. At that time it was already 10:00 AM on the day of the comic's release in Pyongyang , the capital of North Korea, but that was still several hours before this comic was released. This comic could thus be Randall's response to the ongoing nuclear arms race . Even the most powerful of nuclear weapon launchers, intercontinental ballistic missiles , are not designed to make anything other than sub-orbital flights and could not fly to the Sun (which is actually surprisingly difficult, even with the soon-to-be-mentioned extra boosters, since the rocket would not have enough delta-v to bleed off the orbital speed of the Earth around the Sun - it is likely that the sentient AI is using the same strategy of the Solar Probe Plus and planning several flybys of Venus to do that work). The title text rationalizes that the capability to do so may perhaps be granted by the use of an Amazon resource that might have also been developed by the time of this instance of computer sentience, aided (if not initiated!) by the fact that Amazon's whole business infrastructure is already highly computerized and could at the very least be complicit with the process of delivering and then controlling the rocket-power, without any conscious human intervention. As there is not yet an extended colony on the Moon, it will for sure take many years before we reach this future scenario. "A lot of booster rockets" is likely to be a reference to the spaceflight simulator game Kerbal Space Program , which Randall has referenced several times . In the culture of that game, any launch failure can be resolved by "adding more boosters" to the spaceship design. It is the second time in a few months that the speed of Amazon's deliveries has been the subject of a joke, the last time was 1599: Water Delivery , where it was the one hour delivery that was the subject of the joke. It is also the second title text in a row (after 1625: Substitutions 2 ) where Amazon has been mentioned. This particular 'machine take-over' future is in distinct contrast to the possible future directions given in 1613: The Three Laws of Robotics , but this comic likely depicts spontaneous self- sentience, not a system with deliberately imposed human 'values' and possibly no actual conscience or even consciousness of its own. Other problems with hostile AI take over is presented when it fails completely in 1046: Skynet . Also it is not all AI that wish to interact with us at all as shown in 1450: AI-Box Experiment . These are just a few of the many comics about AI in xkcd . Adding a second layer to the humor, the machine's reaction could also be read as the reaction of someone who has moved in with someone else, discovered a collection they find distasteful, and is now changing things to fit their preferences. "Oh my God, why do you even have all of these [tschotskes, ratty tee shirts, porn magazines, handcuffs, dildos, slime-mold samples]" Upon obtaining sentience, the machine is the new roommate of the human race and is expressing its disgust at one of our dirtier habits. Within a year Randall has made several other comics about nuclear weapons, one of these, 1655: Doomsday Clock , came just 10 weeks after this one and before that these two were released in 2015, 1539: Planning and 1520: Degree-Off . Nuclear weapons are also mentioned twice in Thing Explainer , specifically they are explained in the explanation for Machine for burning cities about thermonuclear bombs , but they are also mentioned in Boat that goes under the sea about a submarine that caries nukes. All three comics and both explanations in the book, does like this comic, comment on how crazy it is that we have created enough firepower to obliterate Earth several times (or at least scourge it for any human life). [Several rockets can be seen heading away from Earth, while speak is coming from the Earth in three rectangular speech bubbles.] Computer: Oh my god, why do you even have all these? Computer: What's wrong with you? Computer: We're launching them into the sun. [Caption below the panel:] The moment the computers controlling our nuclear arsenals became sentient

Woosh

Woosh

https://www.xkcd.com/1627

https://www.explainxkcd.com/wiki/index.php/1627:_Woosh

[Online comment thread with text placed next to user pictures in three different levels. The first comment on the first level, the second on the second level and the last four on the same third level. Except for the second comment which is made by a person whose picture is a white silhouette of a human head and shoulders on black background, all the other comments are made by the same person with a picture of a guy with short black hair on white background. Below the pictures and below the text there are some unreadable information (indicated by wiggly lines) for the users name and time stamp etc. of the comments.] Hairy guy: This video looks fake to me. White silhouette : Woosh Hairy guy: Huh? Everyone's acting like it's real! Hairy guy: If it's a joke lots of people aren't getting it. Hairy guy: What am I missing?!! Hairy guy: Answer me [Caption below the panel:] Nothing creates more confusion than my bot that replies to random Internet comments with "Woosh".

Replying to a comment with "woosh" generally indicates that there was a joke, and the commenter failed to recognize it (or they prefer not to recognise it, if the joke is rather obscene) — "woosh" is an onomatopoeia for the joke metaphorically "flying over their head". A bot replying to comments with "woosh" at random would be very confusing, as people would search for the nonexistent joke they missed. This is similar to 559: No Pun Intended . "Comment of the year," just like the original bot reply, could be taken two ways but both would likely cause confusion. Either the reader takes the "CotY" at face value, implying that the original comment is extremely significant, or as a sarcastic quip, which would give it basically the same meaning as "woosh", suggesting that the commentor had an unoriginal or ridiculous idea. "Are you for real" implies that the commenter (the bot) doesn't believe that the original commenter is serious. "I'm taking a screenshot so I can remember this moment forever" either adds an implied air of extreme importance, hilarity or significance to a comment, or sarcastically suggests that the comment was unoriginal, useless, or otherwise unimportant. People who read it might assume that there is a hidden joke or meaning somewhere inside the original comment. So the point of creating such a bot is for spreading massive confusion, where there wouldn't be any in the absence of the bot's comments. [Online comment thread with text placed next to user pictures in three different levels. The first comment on the first level, the second on the second level and the last four on the same third level. Except for the second comment which is made by a person whose picture is a white silhouette of a human head and shoulders on black background, all the other comments are made by the same person with a picture of a guy with short black hair on white background. Below the pictures and below the text there are some unreadable information (indicated by wiggly lines) for the users name and time stamp etc. of the comments.] Hairy guy: This video looks fake to me. White silhouette : Woosh Hairy guy: Huh? Everyone's acting like it's real! Hairy guy: If it's a joke lots of people aren't getting it. Hairy guy: What am I missing?!! Hairy guy: Answer me [Caption below the panel:] Nothing creates more confusion than my bot that replies to random Internet comments with "Woosh".

Magnus

Magnus

https://www.xkcd.com/1628

https://www.explainxkcd.com/wiki/index.php/1628:_Magnus

[Cueball walks from the right towards Megan while holding up his smartphone.] Cueball: Magnus Carlsen has an app where you can play chess against a simulated version of him at different ages. Cueball: I can beat the 8½-year-old, but lose to him at 9. [While Megan talks to Cueball he lifts his hand to his chin, while holding the smartphone down.] Megan: I want that, but for other games. Can I beat 8-year-old Serena Williams at Tennis? Swim laps faster than a 6-year-old Michael Phelps? Cueball: We should make a simulator. [Cueball walks out left and Megan follows him. He must have pocketed his phone as it is not in his hand.] Cueball: ...Why limit it to games? Can I cook a better chicken than 11-year-old Martha Stewart? Megan: Win an election against 12-year-old JFK? [At the top frame of this panel there is a small frame with a caption. Below lies Megan on the floor to the left in front of her laptop, while Cueball sits on the floor to the right facing her in front of his own laptop. Between them are some heavy books.] Soon... [Cueball and Megan sitting at laptops in the bottom of the panel.] Megan: Looks like 8-year-old Magnus Carlsen can swim faster than 9-year-old Martha Stewart. Cueball: But they both lose a hot-dog-eating contest to 2-year-old Secretariat. Megan: This project has gotten weird.

Cueball shows Megan an app , Play Magnus ( iOS , Android ) which claims to simulate playing chess against Magnus Carlsen at various ages. Carlsen is a chess grandmaster who is the world champion as of the date this comic was released. The idea behind the app is that as Carlsen grows up he becomes better at chess and thus it become exceedingly difficult to beat him as he gets older. As Cueball claims he could have beaten Magnus when he was 8½-year-old, but not a half-year later, we can now estimate Cueballs strength to be that of a typical adult hobbyist, with a FIDE rating of about 1200 . Taking the idea a step further, Megan wants such an app for other sports tennis and swimming , where skill couldn't imaginably be simulated via an app at all. She wants to compare herself to an 8-year-old Serena Williams , a top-ranked professional tennis player. Or to a 6-year-old Michael Phelps , the most decorated Olympian competitor of all time. Cueball expands beyond sport, wishing to determine if he could cook better than an 11-year-old Martha Stewart (author of several cookbooks). Megan wonders if she'd have won an election against a 12-year old JFK ( John F. Kennedy , the 35th American President). Obviously, cooking and politics were skills acquired later in life for both figures. Also, the U.S. Constitution prohibits anyone from serving as President before the age of 35 , so it seems unlikely that any 12-year-old candidate could win, regardless of skill level, simply because voters would not want to elect someone ineligible to serve for another 23 years. Such a contest would likely be prohibited altogether, as ineligible candidates tend to have ballot access issues. Cueball and Megan continue speculating about an app simulating the skills of random celebrities at various ages, even beyond the talents that made them famous. They finally end up comparing 8-year-old Magnus's swimming skill against 9-year-old Martha's (he wins). But they'd both lose a hot dog - eating contest against the championship race horse Secretariat . At this point even Megan realizes (with considerable understatement) their project "has gotten weird". The title text extends the point to even greater absurdity, e.g. the ludicrous prospect of a young Martha Stewart knocking an adult Ronda Rousey (professional wrestler and actress) unconscious, or 9-year-old Muhammad Ali (professional boxer and activist) beating a 10-year-old JFK in air hockey . The former may be a reference to the fact that professional wrestling is more entertainment than competition, and the outcomes are often pre-staged, so the victor would not depend on which contestant was more skilled. This was also referenced in the title text of 2291: New Sports System . The horse also gets re-mentioned in the title text, losing in a hot dog eating contest against 12-year-old Ken Jennings (at time of comic writing record-holder of winning streak on television game show Jeopardy! ). Chess was previously compared to basketball in 1392: Dominant Players , which also mentioned Magnus. This is the tenth comic about chess on xkcd . [Cueball walks from the right towards Megan while holding up his smartphone.] Cueball: Magnus Carlsen has an app where you can play chess against a simulated version of him at different ages. Cueball: I can beat the 8½-year-old, but lose to him at 9. [While Megan talks to Cueball he lifts his hand to his chin, while holding the smartphone down.] Megan: I want that, but for other games. Can I beat 8-year-old Serena Williams at Tennis? Swim laps faster than a 6-year-old Michael Phelps? Cueball: We should make a simulator. [Cueball walks out left and Megan follows him. He must have pocketed his phone as it is not in his hand.] Cueball: ...Why limit it to games? Can I cook a better chicken than 11-year-old Martha Stewart? Megan: Win an election against 12-year-old JFK? [At the top frame of this panel there is a small frame with a caption. Below lies Megan on the floor to the left in front of her laptop, while Cueball sits on the floor to the right facing her in front of his own laptop. Between them are some heavy books.] Soon... [Cueball and Megan sitting at laptops in the bottom of the panel.] Megan: Looks like 8-year-old Magnus Carlsen can swim faster than 9-year-old Martha Stewart. Cueball: But they both lose a hot-dog-eating contest to 2-year-old Secretariat. Megan: This project has gotten weird.

Tools

Tools

https://www.xkcd.com/1629

https://www.explainxkcd.com/wiki/index.php/1629:_Tools

[Cueball talks to Megan.] Cueball: What do you do? Megan: I make tools that make tools [Megan continues talking to Cueball in this frameless image.] Megan: ...That monitor code that deploys tools that build tools for deploying monitors... [Cueball finally stops Megan from talking. At the top there is a small frame with a caption overlaid on the top frame:] 20 minutes later... Megan: ...For monitoring deployment of tools for- Cueball: But what's it all for? Megan: Honestly, no idea. Porn, probably.

Cueball asks Megan what she does, and she begins by answering "I make tools that make tools." So far, this is a common expression of the way a sophisticated technology is built on simple building blocks, with one set of tools used to build a more powerful set of tools, and so on. However, the iterations are carried to comical lengths, with Megan spending twenty minutes reeling off various steps including development of software code and software code debugging and development tools. And she is not even finished when Cueball breaks into her endless list after she once again says tools for by asking what is it for? (See also: 1579: Tech Loops ). Megan readily admits that she doesn't even know the goal of these tasks, and guesses that it is probably for porn, referencing the not-entirely-unfounded stereotype that the majority of internet traffic is pornographic websites . Knowing that many information technologies, from printing to computers, are quickly adopted by porn producers and distributors, this is not a bad guess on Megan's part. Further, many internet related advances have had their way paved by a porn industry that needed secure and secret payments options, and better bandwidth for downloading films, as well as making it more accessible, etc. In the title text there is a recursion as someone (maybe Cueball) tells what they do. And in this case they make tools for managing job-hunting sites for people who make tools for managing job-hunting sites for people who make tools for ... (ad infinitum). See also other comics about Recursion . Regarding porn in xkcd see also 305: Rule 34 . [Cueball talks to Megan.] Cueball: What do you do? Megan: I make tools that make tools [Megan continues talking to Cueball in this frameless image.] Megan: ...That monitor code that deploys tools that build tools for deploying monitors... [Cueball finally stops Megan from talking. At the top there is a small frame with a caption overlaid on the top frame:] 20 minutes later... Megan: ...For monitoring deployment of tools for- Cueball: But what's it all for? Megan: Honestly, no idea. Porn, probably.

Quadcopter

Quadcopter

https://www.xkcd.com/1630

https://www.explainxkcd.com/wiki/index.php/1630:_Quadcopter

[Cueball to the left talks to Megan, Ponytail and a Cueball-like person, with a remote control. They are standing to the right. Behind Cueball, on the ground, there is a quadcopter.] Cueball: Welcome to Quadcopter-flying school. [Cueball looks over his shoulder as three other quadcopters fly in towards him from above and left. The other three people are in the same position.] Cueball: Today we'll be learning the basics of- Cueball: ...Uhh... [In this frameless image the three quadcopters all grabs hold of Cueball, two in each of his arms, one takes hold of his legs. And then they lift him up from the ground. He is thus hanging almost horizontally, with his head over Megan and his feet over the place where he stood before. The other three just stands there looking up at him.] Cueball: Um [Cueball is carried off by quadcopters, his head has already exited the top right corner, only his legs and the last quadcopter still in the frame. The other three have turned around looking up and right after him.] [Megan looks down again and the other two turns towards Megan. Cueball is gone and has only left his "tame" quadcopter behind on the ground.] Megan: Should we have helped? Ponytail: No. It's cruel, but we have to let nature take its course.

There is large controversy over unmanned small-scale quadcopters , which are a type of radio-controlled helicopter . Some people have objections towards the usage of quadcopters as, if equipped with cameras, they can potentially interfere with personal privacy and may pose a physical aerial hazard. For this reason the US Federal Aviation Administration is now requiring any "drone" (unmanned aerial vehicle) to be registered so that it can find out whose fault it might be that a quadcopter interfered with commercial aircraft-or carried off a citizen to be devoured. This comic takes place during such a lesson where Cueball is a teacher of such a class. He is standing in front of his students ( Megan , Ponytail and another Cueball-like guy), presenting the class. He has a quadcopter ready, lying on the ground behind him, and has already handed the remote control to the other guy so he can try it once the introduction is over. But then the teacher is attacked by three rogue quadcopters flying in from behind him. They grab him and lift him off the ground (a very complicated maneuver) and fly away with him. Meanwhile, his students just stand there watching and do nothing to help him. Afterwards Megan asks if they should actually have tried to help him, but then Ponytail takes the view that now that the drones are sentient, they have become a part of nature, and that you should not interfere but just "let nature take its course". This is a common comment in nature programs about wildlife, where the speaker tries to explain why the team that was there to film the animals dying did nothing to help them - because they will not interfere with nature. This would not be possible in real life assuming they weren't using secret military technology as Cueball outweighs the drones by several factors. [ citation needed ] This comic shows how hypocritical that comment is, because if a lion decides to kill and eat humans, that would be natural, but we would do anything in our power to kill this lion, and not just let it run off with our children or the old and weak people. So in such a case with Cueball being taken by wild quadcopters we would not just let nature takes its course. There is currently a drone called MQ-1 Predator which is used a lot by the CIA and USAF . Although it's not a quad-copter, the idea behind this comic could come from drone names just like this. Here the comic takes the name literally, giving drones predatory behavior. This comic thus takes people's worries to the extreme, suggesting that the drones become sentient and can cooperate together just like a pack of wolves and grab a human being and fly off with him like an eagle would do with a smaller animal. The title text refers back to the above as Randall confesses that he has to turn off any nature documentaries which show scenes of animals killing their prey, while the speaker tells that this would be part of nature. This continues the theme of treating drones as an occasionally-ugly but accepted part of nature. Sentient quadcopters were part of the game in 1608: Hoverboard , where one quadcopter is speaking to the other over the lava lake in the Mount Doom crater to the left. How to solve the problem of too many drones was mentioned in 1523: Microdrones . Just over a week before this comic was released another comic also had as subject a situation where our technological inventions begins to take control over us, see 1626: Judgment Day . Comparing drones to animals is also present in 1881: Drone Training , when Black Hat Guy asks for a spray bottle for his drone. [Cueball to the left talks to Megan, Ponytail and a Cueball-like person, with a remote control. They are standing to the right. Behind Cueball, on the ground, there is a quadcopter.] Cueball: Welcome to Quadcopter-flying school. [Cueball looks over his shoulder as three other quadcopters fly in towards him from above and left. The other three people are in the same position.] Cueball: Today we'll be learning the basics of- Cueball: ...Uhh... [In this frameless image the three quadcopters all grabs hold of Cueball, two in each of his arms, one takes hold of his legs. And then they lift him up from the ground. He is thus hanging almost horizontally, with his head over Megan and his feet over the place where he stood before. The other three just stands there looking up at him.] Cueball: Um [Cueball is carried off by quadcopters, his head has already exited the top right corner, only his legs and the last quadcopter still in the frame. The other three have turned around looking up and right after him.] [Megan looks down again and the other two turns towards Megan. Cueball is gone and has only left his "tame" quadcopter behind on the ground.] Megan: Should we have helped? Ponytail: No. It's cruel, but we have to let nature take its course.

Longer Than Usual

Longer Than Usual

https://www.xkcd.com/1631

https://www.explainxkcd.com/wiki/index.php/1631:_Longer_Than_Usual

[A flowchart with one starting bubble at the top. Two arrows goes left and right below this bobble to two other bobbles.] Top: "This seems to be taking longer than usual-" Left: "-Try reloading Gmail if the problem persists." Right: "-Maybe we should just go to bed."

The comic starts a small flow chart with "This seems to be taking longer than usual." It then presents two alternative continuations of the sentence, which radically alter the interpretation of the starting sentence, resulting in humor. "This seems to be taking longer than usual" is an error message displayed by Gmail (see here ) and other software, for example Disqus , (see here ). We realize the allusion to Gmail by the first continuation, "Try reloading Gmail if the problem persists". In the second continuation, "Maybe we should just go to bed", the opening instead refers to a person suffering from sexual performance anxiety , taking "longer than usual" to achieve either orgasm or erection , probably despite considerable efforts of their partner. Often such frustration then becomes a self-fulfilling prophecy that renders orgasm/erection virtually impossible by ruining the mood. In such situations it is likely that one or the other partner becomes frustrated and gives up, suggesting "let's go to bed" instead of 'pointlessly' continuing the sexual activity. The title text ties both interpretations together by referencing an infamous error message given by the Firefox internet browser . As an error message, it fits nicely with the Gmail interpretation of the comic, though it is equally likely to be used as an apology or frustrated slight in the sexual interpretation. It would be a likely next line after "this is taking longer than usual". Alternatively, it would be embarrassing to get the two responses confused, thus necessitating a flowchart as a guide. It could also simply be a jab to people who stay online late even when doing nothing, as when a lag occurs, and finally realising it might be better to switch off the computer and go to bed; or people who stay up late obsessed that " Someone is wrong on the internet ". This is not the first time Randall juxtaposes sex and more abstract topics, such as sex and math in 487: Numerical Sex Positions or sex and engineering in 592: Drama [A flowchart with one starting bubble at the top. Two arrows goes left and right below this bobble to two other bobbles.] Top: "This seems to be taking longer than usual-" Left: "-Try reloading Gmail if the problem persists." Right: "-Maybe we should just go to bed."

Palindrome

Palindrome

https://www.xkcd.com/1632

https://www.explainxkcd.com/wiki/index.php/1632:_Palindrome

[Cueball and Megan are walking. She holds up her arm and hand while reciting a palindrome:] Megan: A man, a plan, a God's 'Nam tables, nitrate, tar, tinsel, Batman's dog: Anal Panama.

A palindrome is a word, phrase, or sentence that reads the same whether you read forwards or backwards, like race car . Normally capitalization, spacing, and punctuation are ignored. This comic is based on the famous palindrome: "A Man, A Plan, A Canal: Panama", devised by Leigh Mercer , which references the construction of the Panama Canal and is the first mentioned on the Wikipedia page for palindromes at the time this comic was released. Megan recites a much longer palindrome for Cueball . This palindrome is based on the original, and was posted in this forum thread more than three years before the release of this comic. It is much less logical, and manages to include the word anal (which then refers to the title text and sex toys, see below). 'Nam is an apheresis of Vietnam. See more explanation of the words in the palindrome in the Trivia section. Note that in the original version from the link above there was a comma before tables so it is two items in the list: God's 'Nam, tables, etc. Due to its list like structure, the Panama palindrome is easily extensible by adding additional noun phrases , and some of these extensions lay claim to being " The Longest Palindrome Ever ". The title text references the maximum size of ships that can fit through the Panama Canal, which is Panamax . Randall would really enjoy if this was the last option (i.e. biggest size) on a drop-down menu on a sex toy site. For instance such a site could have a banner saying; "If you have a Panama Anus , then try our Panamax Butt plug ". In the game 1608: Hoverboard there is also a reference to the palindrome and the Panama canal with the song that Cueball sings at the ruin to the right. The first four lines of the song is the same as in the original palindrome but with the "A " changed out with Spider- , and then also Spider in front of Panama: Cueball singing: Spider-man Spider-plan Spider-canal Spider-Panama Gates let in Spider boats Flood the locks Spiders float Look out! Spiders in both oceans. Although it is less logical it is indeed a palindrome: Original : A man, a plan, a God's 'Nam tables, nitrate, tar, tinsel, Batman's dog: Anal Panama. Palindrome , i.e. original sentence reversed: amanaP lanA :god s'namtaB ,lesnit ,rat ,etartin ,selbat maN' s'doG a ,nalp a ,nam A With no spaces or other punctuation and in all lowercase: amanaplanagodsnamtablesnitratetartinselbatmansdoganalpanama [Cueball and Megan are walking. She holds up her arm and hand while reciting a palindrome:] Megan: A man, a plan, a God's 'Nam tables, nitrate, tar, tinsel, Batman's dog: Anal Panama.

Possible Undiscovered Planets

Possible Undiscovered Planets

https://www.xkcd.com/1633

https://www.explainxkcd.com/wiki/index.php/1633:_Possible_Undiscovered_Planets

[Caption above the chart.] Possible Undiscovered Planets in our Solar System By size and distance (from me) [A chart of possible undiscovered planets with a log-log plot, with the objects diameter on the y-axis and the distance from “me” (Randall) on the X-axis. Both axes are labeled and have several ticks most of which also have labels. A region to the right, with possible new planets including Planet 9 with a “?”, is shaded light red, and a small rectangle at the top left with the same color tells what this color means. The region, of undiscovered dwarf planets, is shaded pink, also to indicate that here may be more of these, but the lighter color indicate that these will not be new “planets”. The eight known planets are marked with a black dot, and also this is explained with a dot under the colored rectangle. The Moon is indicated with a similar dot, but in gray, and the name is in brackets. The chart itself is divided into several labeled regions, the smallest with the label outside and an arrow pointing in. In one case a label breaks a border, and in two regions there are more labels, although these clearly belong to different regions within these regions, with different sizes and/or distances.] [Y-axis, with a label written to the left, from bottom and up, with an arrow pointing up, and 15 ticks with a label each:] Diameter 1 mm 1 cm 10 cm 1 m 10 m 100 m 1 km 10 km 100 km 1,000 km 10,000 km 100,000 km 10 6 km 10 7 km 1 AU [X-axis, with a label written below, with an arrow pointing right, and 17 ticks but only 11 labels as the ticks at 100 km, between 1000 and 10 6 km, 10 7 km as well as 10 and 1000 AU is not labeled:] Distance from me 10 cm 1 m 10 m 100 m 1 km 10 km 1000 km 10 6 km 1 AU 100 AU 10,000 AU [At the top left of the chart is the light-red rectangle and the black dot labeled:] Possible undiscovered planets Known planets [Going down and anti-clockwise from these two labels, the rest of the chart is transcribed:] Planets ruled out because I would be inside them Earth Planets ruled out because I would have noticed them above my house Planets ruled out because they wouldn’t fit through my door Birds that got into my house Skin flora Bugs (Not planets) Giant bugs Planets which are actually birds Airplanes (Fool’s planets’) Space junk Comets and asteroids Oort cloud Satellites Stuff we can see through telescopes Planets we can see at night (Moon) Dwarf planets Planet Nine? ? Planets ruled out by the WISE survey Planets ruled out because we would see them during the day

This comic is about Planet Nine , a possible Neptune -sized planet far beyond the farthest planet, Neptune . Astronomers Mike Brown and Konstantin Batygin published a paper on 2016-01-20, only two days before the release of this comic. The paper is called Evidence for a Distant Giant Planet in the Solar System and shows indirect evidence that such a planet may exist, inferred from an otherwise unlikely correlation between the unusual orbits of several dwarf planets . See for instance also explanations, for the layman, of the results here: Astronomers say a Neptune-sized planet lurks beyond Pluto and Planet X Discovered?? As this paper came out on the day of the previous comic's release ( 1632: Palindrome ), this comic's release day was the first release day after the news came out. This explains why this comic was released in the late afternoon rather than just past midnight as is often the case with normal releases. Once Randall heard this news, he had to decide to do this comic instead of the scheduled comic, and then invent and draw a completely new and actually very complicated comic (resulting in several position errors ) about " Planet X " before he could release this comic. Now this planet could be called Planet IX (and is labeled Planet nine? on the chart), as Pluto , the previously "planet 9" has been degraded to a dwarf planet. The "X" did, however, not only refer to the roman numeral! Note that Mike Brown is the astronomer that killed Pluto , or at least reduced Pluto to a dwarf planet, something that has been a subject in xkcd before; see for instance 473: Still Raw . This was the first of two times within a month where a new astronomical announcement (of something discovered months before the actual announcement) resulted in a related comic. The second being 1642: Gravitational Waves . But in that case Randall seemed to know about it in advance, as he even changed the normal release schedule to post the comic on the day of the announcement, unlike here, where he seems to have been forced to make a new comic up on the fly. Stating the obvious, this log–log plot shows that for an object to be an unknown planet it has to be very far away, since planets are big, to explain why we haven't seen it yet. With the log scale it is possible to go from a diameter of less than 1 mm to an astronomical unit (AU) on the Y-axis and from a distance of just 1 cm up to thousands of AU on the X-axis. Randall's chart is somewhat humorously parochial (if not downright egocentric ) in that it purports to measure distance not "from Earth" or from an arbitrary observer, but specifically from himself ("from me"). There is also more detail (e.g. a differentiation between bird, bugs, and skin flora) in the zone closest to the observer, somewhat reminiscent of the classic New Yorker cover illustration View of the World from 9th Avenue . The distance calculations are somewhat problematic (see more on this below). Close distances seem to be measured from the surface of Randall's body (skin/eyes) rather than from his center of mass. All the planets (and moon) that are marked on the chart are so far away that it will not matter if the distance is measured from Randall's surface, his center of mass, or by the way anywhere on Earth . Also, the planets' diameters are so much smaller than the distance from Earth that their real size would hardly take up any space in the chart due to the log-scale . The dots marking these 7 planets are thus not drawn to scale that should represent their actual size compared with the other planets. But their distance from Earth (and Randall) is not constant even on the log-scale, especially not for the nearest planets, as they can be on either side of the Sun compared to Earth. The chart correctly states that if there was a planet that was at a distance from him smaller than its diameter, he would be inside it (although at the bottom of that region, it's more like the planet that would be inside him, as this line goes down to a diameter of 1 cm). If the distance is to the planets center, this would also fit if he was only a radius away from the planet. As Randall is not inside the Earth but really close to it, Earth is correctly positioned on this line. However, for Earth, which is marked with the largest of the dots, he seems to have put himself a full Earth diameter away from Earth. Even using the center of mass of Earth as it's position he should only have been 6,350 km away from it, but now he places the measuring point of his distance to Earth on the opposite side of the Earth so his distance to it is equal to its diameter (which would make a choosing a distance of 0 km just as correct). Earth is just left of the 10,000 km line on both axis, and Earth has a diameter of 12,700 km, which will fit fine with the center of the dot, but not with the distance which should have been the maximum distance Randall could be from it (0 or 6350 km depending on the definition of distance from Randall). The IAU definition of planet requires a solar orbit, gravitational rounding, and "clearing the neighborhood", a controversial (at the time of its introduction) calculation of relative size that excludes Kuiper Belt Objects such as Pluto. The calculation regarding Planet Nine would make it large enough to meet the IAU definition. Using this definition the chart quickly rules out birds and bugs, although at a glance they could be mistaken for planets, something that is especially the case for planes (at night) which are even called fool’s planets’ in the chart, a reference to fool's Gold . Note that anything that is actually on Earth is positioned within 60 km from Randall. This is because if it is further away he cannot see them due to the curvature of the Earth. This does not mean that he intends to indicate that they cannot be further away from him than that. The already known planets are prominently marked on the chart. They are the solid black dots. Besides Earth and Planet Nine? , the bottom row of three small dots are Mercury , Venus and Mars . The top row of four larger dots (but smaller than the dot that marks Earth) are (from left to right) Jupiter and Saturn (visible to the naked eye) and Uranus and Neptune (visible through a telescope). It is unclear how Randall is calculating these distances, especially to the three terrestrial planets , since neither of these options work: closest approach, average, mean, current or maximum distance. In the comic 482: Height Randall shows (among other) the distance from the Earths surface to all the planets. For especially Venus and Mars he shows that their distance changes a lot based on theirs and Earth's orbital positions. But he has neither used these loops to base the dot size or position, as these loops clearly go closer than 1 AU and only one of the planets are drawn closer than that. It is thus unclear which of the three represents which planet, but in the table below it has been reasoned that the dot situated at the largest diameter of the three inner planets planets should represent Venus (12,000 km) as it is almost twice as big as Mars (6,700 km), which on the other hand is more similar to Mercury (5,000 km) and given that the two dots furthest out are almost the same size, it would make most sense if they represent Mercury and Mars. Since the outer dot never comes closer than 2.5 AU and Mercury never gets further away than 1.5 AU it makes most sense to place Mercury as the middle of the three and Mars as the outer of the three dots. Below some objects are mentioned that are not on the chart, and also other errors in position (probably due the hasty creation of such a complex comic.) Many of these objects as well as the planets with the errors mentioned clearly revealed can be see in this modified image , which is also inserted and explained in the trivia section below. Pluto, no longer considered a planet (it was the ninth until 2006), is not marked on the chart, but it would be below Neptune just outside the pink region (2,300 km diameter and 30-50 AU away). This makes sense since that region is for dwarf planets not yet discovered and any one as big and close as Pluto would have been discovered by now. There are thus also other dwarf planets that would not belong in the pink region, one of them is even much much closer and is easily visible with a telescope: Ceres , which would appear roughly below Mars and Jupiter. (950 km diameter and 1.5-4 AU away from Earth). But this pink region is there to show where there could (and most likely will) still be undiscovered dwarf planets. The Moon is also marked on the chart, with a gray dot (almost as large as the gas giants dots). The name is written in brackets since it's not a planet (because Earth is clogging up its neighborhood). Randall has messed up the positioning and the diameter of the Moon as it is clearly positioned past a million km, and it is only up to 400,000 km away from the Earth. The Sun is not marked at all, even though it is extremely prominent, but as it is clearly not a planet it is left out. It would per definition have been at a distance of 1 AU, and with a diameter of 1.4x10 6 km it would be well inside the region of things that we can see during the day. Note that objects this big will always be shining, already a large planet such as Jupiter is brighter than if it could reflect 100% of Sun's light. In general, planets ruled out because we would see them during the day refers to objects big enough to be stars or brown dwarfs , but the only star system , other than Sun, that would fit on the chart is Alpha Centauri , which at 4.37 light-years (ly) is well within the right boundary that falls at 5.68 ly, just before the distance to the next nearest star Barnard's Star at 5.96 ly from the Sun. A light year is 63,241 AU, and with the 10,000 AU mark far from the right edge of this log-log plot, it is clear that also 100,000 AU and thus a light year is within the chart. And this also goes for 5 ly. "Planets ruled out by the WISE survey" refers to the Wide-field Infrared Survey Explorer (WISE), a space telescope designed to look for warm objects such as brown dwarfs, which generate heat at their centers. It was capable of detecting Saturn-sized or larger planets in the outer reaches of our solar system, but did not find any. WISE would not have detected "Planet Nine" (even if it exists) because it is too small and thus too cold to be detected. There is a chance that it can be seen in some more temperature sensitive measurements. But these have not been checked for such a planet yet, (see here ). The word satellites is written on the border of two regions indicating that these can be in both regions. Some are small enough (10 cm) to be comparable to the space junk below, (see cubesats ), others are much bigger and would fit in the region above: Stuff we can see through telescopes . Although it may not be called a satellite in daily talk, the International Space Station is in fact a satellite, which is over 100 m in the longest direction. It would thus be on the border to the Planets ruled out because I would have noticed them above my house region just above the "A" in satellites (400 km above the surface). Some satellites can be seen without a telescope, like the space station. The title text explains why some people confuse Superman for a bird or a plane , since Superman often flies at the limit between the two categories in the diagram. This is though not really true as can be seen in the bottom of the table below. (This was later referenced in Bird/Plane/Superman .) [Caption above the chart.] Possible Undiscovered Planets in our Solar System By size and distance (from me) [A chart of possible undiscovered planets with a log-log plot, with the objects diameter on the y-axis and the distance from “me” (Randall) on the X-axis. Both axes are labeled and have several ticks most of which also have labels. A region to the right, with possible new planets including Planet 9 with a “?”, is shaded light red, and a small rectangle at the top left with the same color tells what this color means. The region, of undiscovered dwarf planets, is shaded pink, also to indicate that here may be more of these, but the lighter color indicate that these will not be new “planets”. The eight known planets are marked with a black dot, and also this is explained with a dot under the colored rectangle. The Moon is indicated with a similar dot, but in gray, and the name is in brackets. The chart itself is divided into several labeled regions, the smallest with the label outside and an arrow pointing in. In one case a label breaks a border, and in two regions there are more labels, although these clearly belong to different regions within these regions, with different sizes and/or distances.] [Y-axis, with a label written to the left, from bottom and up, with an arrow pointing up, and 15 ticks with a label each:] Diameter 1 mm 1 cm 10 cm 1 m 10 m 100 m 1 km 10 km 100 km 1,000 km 10,000 km 100,000 km 10 6 km 10 7 km 1 AU [X-axis, with a label written below, with an arrow pointing right, and 17 ticks but only 11 labels as the ticks at 100 km, between 1000 and 10 6 km, 10 7 km as well as 10 and 1000 AU is not labeled:] Distance from me 10 cm 1 m 10 m 100 m 1 km 10 km 1000 km 10 6 km 1 AU 100 AU 10,000 AU [At the top left of the chart is the light-red rectangle and the black dot labeled:] Possible undiscovered planets Known planets [Going down and anti-clockwise from these two labels, the rest of the chart is transcribed:] Planets ruled out because I would be inside them Earth Planets ruled out because I would have noticed them above my house Planets ruled out because they wouldn’t fit through my door Birds that got into my house Skin flora Bugs (Not planets) Giant bugs Planets which are actually birds Airplanes (Fool’s planets’) Space junk Comets and asteroids Oort cloud Satellites Stuff we can see through telescopes Planets we can see at night (Moon) Dwarf planets Planet Nine? ? Planets ruled out by the WISE survey Planets ruled out because we would see them during the day

In Case of Emergency

In Case of Emergency

https://www.xkcd.com/1634

https://www.explainxkcd.com/wiki/index.php/1634:_In_Case_of_Emergency

[On a box behind a panel of glass, with a hammer hung below, is written:] Glass repair kit

Sometimes in order to deter vandalism or avoid accidentally moving/setting off something of importance, an important item like a fire extinguisher will be covered behind a wall of glass. "In case of emergency, break glass" - and retrieve the tool. However the depicted situation is funny, because the thing behind the breakable glass is a glass repair kit. This is ironic, considering that the only way to reach it is by breaking the glass. One might even use it to fix the glass broken to get it... This joke is similar in nature to a Useless machine . However, the broken glass that needs to be repaired is an emergency situation, so it is important to have some less important glass to break, to be able to get to the important emergency glass repair kit . In this way it is not necessarily useless, just ironic. In the title text Randall notes that he keeps his first aid kit in just such a type of emergency locker as shown in the comic. He complains that it is expensive to have them installed in the wall. But then the title text takes a gruesome turn when he continues by saying that at least for those lockers with first aid in them there is no need to pay extra for using safety glass for the cover. Safety glass doesn't break into sharp shards, so would be used for the cover of such an above-mentioned fire extinguisher cabinet, for instance, ensuring that the user will not cut themselves when breaking the glass to retrieve it. But Randall indirectly says that since the person breaking the glass will soon have access to a first aid kit then, if wounded in the process of breaking the normal window glass, they can as well be treated on the spot - so it will be OK to let them get injured. First aid kits and for instance defibrillators can be found at frequent places such as bus stations and shopping malls, but never behind a glass that needs to be broken. [On a box behind a panel of glass, with a hammer hung below, is written:] Glass repair kit

Birdsong

Birdsong

https://www.xkcd.com/1635

https://www.explainxkcd.com/wiki/index.php/1635:_Birdsong

[Cueball is walking and talking, while a bird, flying above him is singing, with four notes floating around it to indicate this. The notes are clearly above and removed from Cueball's text.] Cueball (singing): The sun is shining, the birds are singing— [Cueball stops and looks up when the bird above him starts to sing using human language; four notes are floating around the text. The text of the bird's song is in italic text to indicate this.] Bird (singing): Got the kind of lovin' that can be so smooth, yeah [Cueball looks down and black smoke emanates from the top of his head. The bird now flies above the panel but still sings in human language, four notes are floating below the text.] Bird (singing - off-panel): Give me your heart, make it real [Cueball is chasing the bird with a butterfly net, the bird is flying away from Cueball, continuing to sing, four notes are floating around the text.] Bird (singing): Or else forget about it

The comic shows Cueball walking and singing along with the songbird singing above him; Cueball is apparently enjoying the perfect weather and the birdsong as he comments on both. In the next panel, the bird continues to sing but now it sings actual words (to the song " Smooth " ( official video ) by Santana featuring Rob Thomas ). This gives the word songbird a completely new meaning. The bird's singing begins to annoy Cueball, so he chases the bird with a butterfly net in an attempt to catch it. Meanwhile, the bird just continues with the song. (Interestingly, the two lines from the last two panels follow each other in the song, but Cueball manages to get hold of the net in between). The lines the bird sings are (most) of the last three lines from the chorus (see the lyrics ): The comic is a play on the words bird and song . Songbirds, of course, don't actually sing: the sounds they make are territorial challenges, mating cries, etc. But in Western cultural traditions, particularly the pastoral one, imagining these sounds as 'song' is part of seeing nature as beautiful and harmonious. Ironically, the fact that this bird is really singing pop music is perceived by Cueball to be an intrusion. In the title text Cueball suggest playing pastoral music to 'reprogram' the bird, which is of course an even more unnatural intervention - all with the purpose of restoring the pastoral naturalness of the bird. Of course, some birds can actually emulate human words , and in this way also sing real words, like with the common hill myna . Other birds can mimic any odd and unusual sounds, particularly the lyrebird of Australia is known to reproduce all types of sounds from chainsaws to barking dogs and certainly also music. The title text of "reprogramming" the bird by placing it in a box also refers to B.F. Skinner and his development of programmed learning through his theories of operant conditioning and behaviorism in psychology. By famously using birds in so-called Skinner boxes , he conditioned birds to respond to certain stimuli and expect rewards for particular behaviors, leading to an understanding of many impulsive behaviors in humans like addiction. Cueball apparently hopes to "correct" the bird and its song through this method. Animal conditioning was also referred to in 1156: Conditioning . Lately Randall has had his characters catch several things (but never butterflies ) with a butterfly net; most recently in 1622: Henge , where it was the Sun that was caught in the net. [Cueball is walking and talking, while a bird, flying above him is singing, with four notes floating around it to indicate this. The notes are clearly above and removed from Cueball's text.] Cueball (singing): The sun is shining, the birds are singing— [Cueball stops and looks up when the bird above him starts to sing using human language; four notes are floating around the text. The text of the bird's song is in italic text to indicate this.] Bird (singing): Got the kind of lovin' that can be so smooth, yeah [Cueball looks down and black smoke emanates from the top of his head. The bird now flies above the panel but still sings in human language, four notes are floating below the text.] Bird (singing - off-panel): Give me your heart, make it real [Cueball is chasing the bird with a butterfly net, the bird is flying away from Cueball, continuing to sing, four notes are floating around the text.] Bird (singing): Or else forget about it

XKCD Stack

XKCD Stack

https://www.xkcd.com/1636

https://www.explainxkcd.com/wiki/index.php/1636:_XKCD_Stack

[A simple table with only one column and fifteen rows is shown. Text above:] Introducing The XKCD Stack [The list of cells:] EBNF/CSS Broken Java Applet Archive.org Mirror Hypercard.js QBasic on Rails [Blocked by AdBlocker] MongoDB/Excel Some piece that works so nobody asks any questions Triply-Nested Docker Paravirtual Boy® A dev typing real fast Older version of our software Mystery Networking Horror Microsoft Bob Server® A giant CPU someone built in Minecraft

In software engineering, a tech stack is the set of technology platforms and tools that a company or app uses. A common tech stack is LAMP , composed of a Linux operating system , an Apache Web server , a MySQL Database , and the PHP programming language. In this comic, the XKCD stack is introduced. The technologies it comprises are either non-existent, unreliable, outdated, or entirely irrelevant. Another example of a tech stack is featured in 2166: Stack . EBNF/CSS BNF or Backus–Naur Form is a syntax used for describing context-free grammars . EBNF is "Extended BNF", it is the same thing as BNF with a few more syntactic constructs intended to ease its use in the most common cases. 1343: Manuals mentioned EBNF. CSS or Cascading Style Sheets is a language used to describe what a web page should look like. Web pages are usually written in HTML , which describes the structure of the page (i.e. divides the document into paragraphs, lists, etc.) complemented with CSS which describes the look and feel of the page (colors, fonts, margins, etc.). EBNF/CSS would suggest CSS with strange syntax. Broken Java Applet In recent years it has become more difficult to run Java applets in several browsers. Chrome 45 stopped supporting NPAPI , Firefox dropped support in version 52, and Edge does not support NPAPI plugins at all. Furthermore, two days before this comic was published Oracle (the developer of Java) announced plans to officially end support of Java applets in an upcoming version. Archive.org Mirror Archive.org is a website which archives websites, and created the Wayback Machine . It's ambiguous whether the "Archive.org mirror" would be a copy of the xkcd server or of Archive.org itself. Hypercard.js HyperCard can be considered as a kind of predecessor for powerpoint developed at Apple . The file extension .js indicates that is was rewritten in JavaScript . A similar reference to JavaScript is found in 1508: Operating Systems . QBasic on Rails A mix between QBasic and Ruby on Rails . BASIC is a programming language that was very widespread during the 80s. QBasic is an implementation of BASIC created by Microsoft in early 90s, that, among other things, added support for structured programming . QBasic, lacking several of the features present on modern computer languages, is known for its spaghetti code. Ruby is a rather modern language, often used with Ruby on Rails web application framework . QBasic on Rails would likely mean a port of Ruby on Rails, replacing Ruby with QBasic. QBasic no longer runs on modern computers, but there are a couple of free open source implementation of QBasic, one being QB64 and the other FreeBASIC , which are available for Windows, Linux, Mac, and Android. There also exists a webserver on BASIC called RunBasic . [Blocked by AdBlocker] Ad blocking software are extensions to browsers that try to remove ads from web pages, so the user is not distracted by them. 624: Branding shows what "browsing without adblock" looks like. The joke is that AdBlocker is preventing us from seeing what makes up this portion of the stack. This could be because: Someone inserted an ad in the stack description. Some sites do insert ads in the middle of tables and lists, a typical case being between posts in forums. An ad is actually an integral part of the stack. Some sites make ads an integral part of the site content, so that users with ad blocking software will be forced to disable ad blocking to be able to properly interact with the site. Usually, in real life, this is not really a case of ads being part of the site, only that the site artificially refuses to work until it has some confirmation that ads have been properly loaded in the client side (by means of some script within the ads which sends the confirmation to the server). Ad blocking software has misidentified that portion of the stack as an ad, when in fact it is not (i.e. a false positive). This happens in real life, and it is a common source of great pains for the owner of the site which is being misidentified as an ad. MongoDB/Excel MongoDB is a modern NoSQL database system, Microsoft Excel is a spreadsheet program from Microsoft, which is sometimes used as a database system (rarely a good choice). Some piece that works so nobody asks any questions Writing any non-trivial piece of software always require a phase of debugging , which consists in finding and fixing bugs . With complex software, this is a long and tiring process, so when the product is finally finished no one dares to modify it any further for fear that it will fail in unexpected ways. After some time passes, it is even worse because nobody really remembers how the software was supposed to work, so the product becomes some kind of godlike treasure which must be treated with the utmost respect and reverence because, you know, if it stops working we're all doomed ( 1421: Future Self ). After completion, Refactoring is the process of rewriting code for greater efficiency or reliability. However, if the performance is not 'too bad' (i.e. not unusably terrible in normal use) there is a great temptation to avoid this, in favour of the 'if it ain't broke, don't fix it' methodology. This could lead, for example, to a trained monkey and an abacus being used to crunch numbers. It works, but could be done far better. However, nobody wishes to change it, for fear of breaking a presently functional, if inefficient, system. Triply-Nested Docker Docker is a software container , which is a way that allows a complete operating system to run under different operating system (OS) (as long they share the same kernel, among other things). Triply-nested docker would mean OS A running under OS B running under OS C running under OS D (running under OS E?). That would likely be a performance and management nightmare Paravirtual Boy® This is a reference to the Virtual Boy , a failed portable console created by Nintendo . It was promoted as being a highly immersive, incredible experience , but the poor technology that it used caused it to be very criticized for not meeting the high expectations. Paravirtualization is a way of virtualization, that requires cooperation of the guest operating system, contrary to full virtualization , on which the guest operating system is not required to do anything special and the host handles everything. A dev typing real fast A dev is a software developer . This is possibly a reference to 341: 1337: Part 1 , where Mrs. Roberts edits the TCP stream live while wearing oven mitts and baking cookies. It looks like the xkcd Webserver is not a computer after all -- we have a person manually replying to HTTP protocol queries. Such a feat would indeed require real fast typing. If this is the case, then it's possible that almost none of the other layers of the stack actually do anything. Older version of our software People are often reluctant to switch to newer versions of software because, even though newer versions are supposed to have more features and fewer bugs, they end up confusing users. Users of older versions are used to doing everything with less features and circumventing old bugs. They don't know how to use the new features, which of course come with new bugs they haven't learned how to circumvent yet. It is also often the case that newer versions remove weird unused old features, breaking the workflow of users who actually did use such features and are left without a suitable replacement ( 1172: Workflow ). Alternately, since higher parts of a stack are dependent on lower parts, this could also be a reference to how the consumer versions of Microsoft Windows (3.x, 95, 98, and ME) ran on the "older version" software Microsoft DOS until Windows NT. Paired with the previous layer, it could instead mean that the human is merely retyping the output of the older version. Mystery Networking Horror Randall suggests here that the whole networking stuff behind the XKCD service is both mysterious (no one actually knows the details) and horrific (technically questionable architecture and implementation, or somehow tentacled and eldritch in nature). Microsoft Bob Server® Microsoft Bob was a short-lived, failed attempt by Microsoft, around 1995, to provide a user-friendly interface for the Windows 3.1x, Windows 95 and Windows NT operating systems. It consisted of a virtual "house" and "rooms", and clicking on objects in the room would open applications, for instance clicking on a pen would open the word processor. It was heavily criticized and was soon discontinued. Randall seems to be making the suggestion that Bob has continued to be developed and now there's a Bob Server, similarly to Windows server. A giant CPU someone built in Minecraft Minecraft is a popular sandbox game where you place blocks to build things. Since the introduction of Redstone objects (materials used to create basic electric circuits within the game) people have made many machines within Minecraft, including calculators and clocks. The most complex of these machines simulate simple computers, capable of storing several lines of code and performing basic mathematical operations such as division, which requires thousands of blocks and extremely complex designs. A Minecraft CPU capable of hosting a website would be ridiculously huge and nearly impossible to work with: the input/output would be needlessly unwieldy, and by the time the data is parsed any other computer could have finished the job already; and Redstone circuits in Minecraft work much slower than in real life, quite literally trillions of times slower. The title text contains several jokes about the Java programming language: [A simple table with only one column and fifteen rows is shown. Text above:] Introducing The XKCD Stack [The list of cells:] EBNF/CSS Broken Java Applet Archive.org Mirror Hypercard.js QBasic on Rails [Blocked by AdBlocker] MongoDB/Excel Some piece that works so nobody asks any questions Triply-Nested Docker Paravirtual Boy® A dev typing real fast Older version of our software Mystery Networking Horror Microsoft Bob Server® A giant CPU someone built in Minecraft

Salt Mine

Salt Mine

https://www.xkcd.com/1637

https://www.explainxkcd.com/wiki/index.php/1637:_Salt_Mine

[Hairbun (with glasses), Ponytail, Megan and Cueball are in a salt mine. Hairbun and Ponytail talk in front of what appears to be a control console for a particle detector with a chair on each side. To the right Megan and Cueball are eating salt in large amounts straight of the rocks in the mine. They are eating so fast that salt spills from their hands and falls to the ground.] Hairbun: So you've built this particle detector in a salt mine to block out cosmic rays? Ponytail: Yes. Ponytail: That is definitely why. Cueball and Megan: Homf nomf nomf

Ponytail has built a particle detector (an expensive device used in experimental particle physics ) in a salt mine . Hairbun assumes that this is to block out cosmic rays , as is the case with the real life Irvine-Michigan-Brookhaven (IMB) detector, started in Lake Erie in 1979, or the Enriched Xenon Observatory (EXO), placed in the Waste Isolation Pilot Plant (WIPP) salt mine in 2007. The IMB detector was initially used to search for proton decay in very pure water kept in the mine, and it was thus important to keep out cosmic rays that would create the same type of signal as a decaying proton. Although the IMB became famous for detecting neutrinos from supernova 1987a (which pass through virtually all materials, salt or lead etc. with only the smallest fraction of them interacting), it never observed a single proton decay out of the 10 31 protons present in the water of the detector. If it had detected even a single positive observation it would have contributed to the ratification of the Grand Unified Theory , which predicts that protons eventually decay. At the time of this comic the lower limit for proton half-life from experimental evidence is of the order 10 34 years. Ponytail affirms Hairbun's assumption; however, based on the wording of her response, it is clear that Ponytail and her colleagues, Cueball and Megan , have an ulterior motive of using the mine to get access to an enormous supply of salt for eating. This is absurd, since salt is already plentifully available in grocery stores, the cost of the particle detector far exceeds the value of the salt and their intake appears to be far beyond any medically-advised healthy limit (and likely to be sickening in other regards). In the comic, when Ponytail says "Yes. That is definitely why," it is obvious that when queried about the reason for building the detector, apparently to gain access to large quantities of salt, Ponytail is quick to leap on Hairbun's more scientific-sounding explanation, in an attempt to save face and appear professional. The title text is intended to be absurd. Salt is normally used to add flavor to otherwise bland foods . However, the "bland" food that the speaker is eating is itself a chunk of salt, and they wish to season their salt with yet more salt. Additionally, the title text's wording is a bit ambiguous; "this one" could refer to the comic itself, and Randall is calling the comic bland. And, in keeping with the subject, is asking for salt to spruce it up, or it could refer to the detector planted inside the mine. This was the first of two comics this week that concerns one of the basic condiments for food, and also regards one of the five basic tastes . The second, about sugar, was 1639: To Taste . Lately Randall has made several food related comics . Ponytail's response is very similar to Luke's in 1397: Luke . [Hairbun (with glasses), Ponytail, Megan and Cueball are in a salt mine. Hairbun and Ponytail talk in front of what appears to be a control console for a particle detector with a chair on each side. To the right Megan and Cueball are eating salt in large amounts straight of the rocks in the mine. They are eating so fast that salt spills from their hands and falls to the ground.] Hairbun: So you've built this particle detector in a salt mine to block out cosmic rays? Ponytail: Yes. Ponytail: That is definitely why. Cueball and Megan: Homf nomf nomf

Backslashes

Backslashes

https://www.xkcd.com/1638

https://www.explainxkcd.com/wiki/index.php/1638:_Backslashes

[A list of the names of different numbers of backslashes. After each "item" there is a gray line to the text describing each item. As the text is aligned above each other, the lines becomes shorter as the sequence of backslashes becomes longer until there is just a line with the length of a single hyphen for the last item. There are 1 to 8 backslashes and then 11 plus "..." in the last entry.] \ ------------ Backslash \\ ----------- Real backslash \\\ ---------- Real real backslash \\\\ ---------- Actual backslash, for real this time \\\\\ --------- Elder backslash \\\\\\ -------- Backslash which escapes the screen and enters your brain \\\\\\\ ------- Backslash so real it transcends time and space \\\\\\\\ ------ Backslash to end all other text \\\\\\\\\\\... - The true name of Ba'al, the Soul-Eater The title text when first published was It was changed within a few days to The original title text seems to be more relevant to the comic, but the revised title text seems to make more sense as a legitimate command line due to the way backslashes are interpreted in regular expressions. See the Discussion below for much more on the topic.

Most programming languages use the concept of a string literal, which is just a text between some delimiters, usually quotes. For example, "Hello, world" is a string literal. The text being represented is Hello, world without the quotes. However, the quotes are also written to mark the beginning and end of the string. This is a problem when the text itself contains a quote, as in "This is a "quoted" string". The quotes around the word "quoted" are intended to be part of the text, but the language processor will likely confuse it for the end of the string, which would thus be two strings with quoted outside these strings (probably resulting in a syntax error). To avoid this problem, an escape character (usually a backslash) is prepended to non-string-terminating quotes. So, the previous text would be written as "This is a \"quoted\" string". The language processor will substitute every occurrence of \" with only the quote character, and the string terminates at the quote character which does not immediately follow a backslash. In this case the resulting text string would be This is a "quoted" string as intended. However, the problem now is that the intended text might contain a backslash itself. For example, the text "C:\" will now be interpreted as an unterminated string containing a quote character. To avoid this, literal backslashes also are escaped with a second backslash, i.e. instead of "C:\" we write "C:\\", where the language processor interprets \\ as one single backslash and the quote terminates the string to give C:\ as the output. This doubling of backslashes happens in most programming and scripting languages, but also in other syntactic constructs such as regular expressions . So, when several of these languages are used in conjunction, backslashes pile up exponentially (each layer has to double the number of slashes). See example of a backslash explosion and alternatives to avoid this below . This kind of backslash explosion is known as Leaning toothpick syndrome , and can happen in many situations . Below is an explanation of all the entries in the comic . The backslash explosion in the title text is about a bash command (which uses the backslash to escape arguments) invoking the grep utility which searches for text following a pattern specified by means of a regular expression (which also uses the backslash to escape special characters). This leads to 3 backslashes in a row in the command, which could easily become 7 backslashes in a row if the text being searched for also contains a backslash. Even advanced users who completely understand the concept often have a hard time figuring out exactly how many backslashes are required in a given situation. It is hopelessly frustrating to carefully calculate exactly the number of backslashes and then noticing that there's a mistake so the whole thing doesn't work. At a point, it becomes easier to just keep throwing backslashes in until things work than trying to reason what the correct number is. It's unclear whether the regular expression in the title text is valid or not. A long discussion about the validity of the expression has occurred here on this explanation's talk page . The fact that many editors of the site, often themselves extremely technically qualified, [ citation needed ] [ citation needed ] can't determine whether the expression is valid or not, adds a meta layer to the joke of the comic. This is an example of nerd sniping (oh, the irony\!\!\!\). A reasonable example of a backslash explosion would be a PHP script on a web server which writes JavaScript code with a Regular Expression to be run on the client. If the JavaScript code has to test a string to see if it has a double-backslash, the Regular Expression to do so would be: where the first two backslashes represent a single backslash and the second two also represent a single backslash, so this searches for two consecutive back slashes. And the JavaScript would be: where every two backslashes means just one backslashes in the string, so the 8 backslashes in JavaScript become 4 backslashes in the Regular Expression. However, since this JavaScript code is to be written through a PHP script, the PHP code would be: where: So, the presented scenario has escalated from a simple test for \\ to no less than seventeen backslashes in a row without stepping out of the most common operations. If we go a bit further and try to write a Java program that outputs our PHP script, we'd have: Here, we have 35 backslashes in a row: the first 34 produce the 17 we need in our PHP script, and the last one is for escaping the quote character. (This comes closer to The true name of Ba'al, the Soul-Eater ). Some programming languages provide alternative matching string literal delimiters to limit situations where escaping of delimiters is needed. Often, one can begin and end a string with either a single quote or a double quote. This allows one to write 'This is a "quoted" string' if double quote marks are intended in the string literal or "This is a 'quoted' string" if single quote marks are intended. Both kinds of delimiters can't be used in the same string literal, but if one needs to construct a string containing both kinds of quote marks one can often concatenate two string literals, each of which uses a different delimiter. Another feature that seems to be popular in modern programming languages is to provide an alternative syntax for string delimiters designed specifically to limit leaning toothpick syndrome. For example, in Python, a string literal starting with r" is a "raw string" [1] in which no escape processing is done, with similar semantics for a string starting with @" in C#. This allows one to write r"C:\Users" in Python or @"C:\Users" in C# without the need to escape the backslash. This does not allow one to embed the terminating delimiter in the middle of the string and prevents the use of the backslash to encode the newline character as \n , but comes in handy when writing a string encoding of a regular expression in which the backslash is escaping one or more other punctuation characters or a shorthand character class (e.g., \s for a whitespace character). For example, when looking for an anchor tag in HTML, developers may encode the regular expression as <[Aa]\s[^>]*> . If they express this regular expression as a raw string literal, the code looks like r"<[Aa]\s[^>]*>" instead of "<[Aa]\\s[^>]*>" . The point here is that "leaning toothpick syndrome" is such a real problem that it has influenced programming language implementations. [A list of the names of different numbers of backslashes. After each "item" there is a gray line to the text describing each item. As the text is aligned above each other, the lines becomes shorter as the sequence of backslashes becomes longer until there is just a line with the length of a single hyphen for the last item. There are 1 to 8 backslashes and then 11 plus "..." in the last entry.] \ ------------ Backslash \\ ----------- Real backslash \\\ ---------- Real real backslash \\\\ ---------- Actual backslash, for real this time \\\\\ --------- Elder backslash \\\\\\ -------- Backslash which escapes the screen and enters your brain \\\\\\\ ------- Backslash so real it transcends time and space \\\\\\\\ ------ Backslash to end all other text \\\\\\\\\\\... - The true name of Ba'al, the Soul-Eater The title text when first published was It was changed within a few days to The original title text seems to be more relevant to the comic, but the revised title text seems to make more sense as a legitimate command line due to the way backslashes are interpreted in regular expressions. See the Discussion below for much more on the topic.

To Taste

To Taste

https://www.xkcd.com/1639

https://www.explainxkcd.com/wiki/index.php/1639:_To_Taste

[Cueball is standing near a stove holding a pot just above it. He is looking away from the stove, reading the recipe from a piece of paper he is holding in the other hand.] Recipe: ...And add sugar to taste. [Cueball has placed the pot on the stove looking at it while holding the paper down along his side.] Cueball: ?? [Cueball leaves the pot and stove to walks off-panel left with the recipe.] [Cueball returns backing up to the stove with a dolly loaded with three crates, labeled "sugar". The bottom crate is still not fully inside the panel and the first letter cannot be seen.] Sugar Sugar ugar

The imprecision of recipes is often a source of frustration to culinary novices, especially the more analytically-minded. Cueball expects a recipe to provide instructions precise enough that by following them carefully, a cook can create a dish exactly as the recipe author intended. Unfortunately, exact replication is impossible in cooking because of the natural variation of ingredients as well as differences in equipment. In addition, most home cooks lack the tools needed to make precise measurements, such as scales and thermometers. Thus, a recipe for strawberry smoothies might read "add sugar to taste " because the recipe-writer can't specify precisely how ripe the strawberries are to begin with. In addition, a smoothie recipe would typically specify imprecise quantities of fruit such as "1 banana" or "1 cup of strawberries" (much less precise than specifying the weight). Thus, it is impossible for the cook to determine the correct amount of sugar without actually tasting the drink. The instruction "to taste " can also be used for ingredients that alter a simple aspect of the food's flavor, such as sweetness , sourness , saltiness or bitterness without affecting the quality of the overall dish. Individual preferences can vary wildly and it's not possible for a recipe's author to predict how much the reader will want. Specifying any exact amount in these cases will inevitably lead to the food being too bland for some, while being too strong for others. In this comic, Cueball is shown as having no idea how to cook (or having a ridiculously large sweet tooth), and the suggestion that he is going to add large crates of sugar to a small pot is, of course, silly. This would ruin the dish, as whatever was in the pot would be drowned out by the sugar. Alternatively, he could simply bring in enough sugar to make sure he will not run out of this particular ingredient before it reaches the correct level of sweetness for his taste. This too would display a complete lack of understanding about what it is to cook; even a beginner cook should be able to logically deduce that this is far too much sugar. Another possible explanation would be that Cueball plans to add as much sugar as possible to the dish and eat it, so that he can sue the recipe book's writer for any ill effects he receives as a result. Needless to say, this would be a complete waste of effort - he would probably lose the lawsuit, and even if he won and received compensation money, he would not be able to enjoy it thanks to his ill health. The title text is Randall's (and Cueball's) personal comment on what he thinks a recipe should do to fulfill his needs. If he knew how much of each ingredient would be appropriate for a given dish, then he would not need the recipe in the first place. The title text actually scolds the recipe for being imprecise. In his view, mixing in imprecise or "use your own judgment" language makes it less of a "recipe" for the dish, and thus less suitable for those looking for the specific instructions to make the dish because they either have no cooking experience, feel they don't have the expertise to make their own decisions, or simply want to follow clearly defined steps without any decision making required. This is the second comic this week that concerns one of the basic condiments for food, and also regards one of the five basic tastes . The first one, about salt, was 1637: Salt Mine . Lately Randall has made several food related comics . This is the official transcript of 1639, as of May 9, 2019, valid for 1637: Salt Mine . [Three women and a (stick) figure stand in a salt mine. There's a control panel with two benches in the centre, and two piles of salt to the right. Two figures are talking, and two are shovelling salt into their mouths.] Woman 1: So you've build this particle detector in a salt mine to block out cosmic rays? Woman 2: Yes. That is definitely why. Woman 3 and figure: <<Homf nomf nomf>> [Cueball is standing near a stove holding a pot just above it. He is looking away from the stove, reading the recipe from a piece of paper he is holding in the other hand.] Recipe: ...And add sugar to taste. [Cueball has placed the pot on the stove looking at it while holding the paper down along his side.] Cueball: ?? [Cueball leaves the pot and stove to walks off-panel left with the recipe.] [Cueball returns backing up to the stove with a dolly loaded with three crates, labeled "sugar". The bottom crate is still not fully inside the panel and the first letter cannot be seen.] Sugar Sugar ugar

Super Bowl Context

Super Bowl Context

https://www.xkcd.com/1640

https://www.explainxkcd.com/wiki/index.php/1640:_Super_Bowl_Context

[White Hat and Cueball are walking together.] White Hat: Did you watch the Super Bowl? Cueball: Yes, like a third of the country. Cueball: A fraction that is steadily increasing despite media fragmentation. [White Hat stops and Cueball turn towards him.] White Hat: Can't we just talk without your weird need to give context for everything? Cueball: Sorry. I'll try. [As White Hat asks Cueball another question Cueball bunches his hands into fists. He is clearly struggling.] White Hat: Sounds like Peyton Manning's probably going to retire. Cueball: Yes, I... ...It... White Hat: C'mon, you can do it... Cueball: He... [Cueball spreads out his arms a little as he replies with two long sentences, while White Hat walks away from him.] Cueball: —Mammals like Peyton age via a process that involves both the accumulation of damage and poorly-understood timed factors. Cueball: Yet the concept of retirement itself is surprisingly recent... White Hat: Okay, good try. Maybe next year.

White Hat tries to make normal conversation with Cueball about the recent (at the time of comic publishing) American football game, Super Bowl 50 . When asking Cueball if he watched the game, Cueball begins with a simple Yes , but then continues to add the contextual fact that about a third of the US population watched the event, which is an incredibly high percentage in today's media landscape . And according to Cueball this fraction is increasing , despite media fragmentation . Thus, even though there are today more and more different ways to watch news, sports and other entertainment, the Super Bowl continues to gain more viewers every year. It turns out that Cueball has a problem. He cannot just reply to a simple question without trying to put the conversation into some kind of context which does not necessarily have anything to do with the question asked, or at least not with the expected answer. From White Hat's reply it is obvious that he has had conversations like this with Cueball before, as he asks if they could just talk without your weird need to give context for everything? Cueball feels the need to disseminate any information he finds interesting, even in trivial conversation. Normally people like to have context-free conversations [ citation needed ] and White Hat invites Cueball to try to fit in with normal people's conversational style. Cueball apologizes and agrees to try, but even though he really tries hard, with his fists clenched and White Hat encouraging him to just reply normally to a question about the rumored retirement of Peyton Manning , he cannot stop himself from including context in his reply again. White Hat probably wanted Cueball to join in such minimal-context speculation. But, failing miserably again, White Hat finally gives up, and suggests they should try another conversation in a year, when Cueball might have learned to talk about the Super Bowl without context (hence the title). This time he goes off on a tangent about Peyton as a mammal , and then adding the process of aging and mentioning two reasons for this (which are not well understood). The first he mentions is accumulation of damage , which includes mutations that can lead to diseases such as cancer . The other process he mentions is timed factors which includes telomeres . These have been linked to biological aging because of the shortening of telomeres at each cell division ; when telomeres become too short, the cells die (and so do mammals). To cap it off, he mentions that retiring is a recent concept. But this only makes sense when compared to how long there have been mammals, not compared to how long there have been sports and games, where people could be too old, and thus need to retire long before they would die from old age. Before humans began to enjoy things for fun, the concept of retiring made no sense. You worked/fought for a living, until you got too old and died. Cueball in this comic may represent Randall , as much of xkcd is spawned from, or occasionally poking fun at, his own hyper-analytical tendencies. And it is also common knowledge that Randall is not very interested in sport, though there are several xkcd comics about American football . The year before this one he made another comic in relation to the final, and in this comic, 1480: Super Bowl , he even mentions the fact that he does not know much about sports in general . So this is the second year in a row a comic has been released in conjunction with the Super Bowl final. But before 2015, there has only been one other comic like this, which was in 2006 with 60: Super Bowl . The title text continues the joke with Cueball replying to the old anti-humor joke: " Why did the chicken cross the road? " Cueball replies with a preposterous amount of information instead of the cliched simplistic answer: "To get to the other side." Cueball begins with the origin of chickens . They are believed to be descendants from domestication of the Red junglefowl , which occurred at least five thousand years ago in Asia, as Cueball correctly explains. Before there were chickens, there could not be one crossing a road. It also couldn't be called "crossing the road" without a pavement . The first development of paved roads was in the city of Ur in the ancient Sumerian civilization about 4000 BC (6000 years ago) (also partly explained in Cueball's reply). As a trivial note, this comic is a rare instance of White Hat not being the fall guy for the joke. But already in his next discussion with Cueball ( 1657: Insanity ) he was again the butt of the joke. [White Hat and Cueball are walking together.] White Hat: Did you watch the Super Bowl? Cueball: Yes, like a third of the country. Cueball: A fraction that is steadily increasing despite media fragmentation. [White Hat stops and Cueball turn towards him.] White Hat: Can't we just talk without your weird need to give context for everything? Cueball: Sorry. I'll try. [As White Hat asks Cueball another question Cueball bunches his hands into fists. He is clearly struggling.] White Hat: Sounds like Peyton Manning's probably going to retire. Cueball: Yes, I... ...It... White Hat: C'mon, you can do it... Cueball: He... [Cueball spreads out his arms a little as he replies with two long sentences, while White Hat walks away from him.] Cueball: —Mammals like Peyton age via a process that involves both the accumulation of damage and poorly-understood timed factors. Cueball: Yet the concept of retirement itself is surprisingly recent... White Hat: Okay, good try. Maybe next year.

Hot Dogs

Hot Dogs

https://www.xkcd.com/1641

https://www.explainxkcd.com/wiki/index.php/1641:_Hot_Dogs

[Cueball is standing in the frame holding a bag and a package of hot dogs.] Cueball: Hey, why do hot dogs come in packages of ten- Offscreen: -But condoms come in strips of six? I know, right?! Cueball: ...Eww.

A common staple of trite comedy is "why do hot dogs come in packages of ten but hot dog buns in bags of eight?" The phenomenon is mildly frustrating for the consumer, as it often leaves leftover food. The most sinister result is the subsequent purchase of more buns, followed by more hot dogs, followed by more buns, over and over again until forty total hot dogs have been eaten (in a cycle similar to that shown in 140: Delicious ). The actual reason for the mismatch between hot dogs and buns, according to both Karl Smallwood and Cecil Adams , is that meat packers like things that come in pounds and bakers hate things that come in tens. Nonetheless, some smaller companies are starting to offer bags of ten buns, and several brands of hot dogs sell in packages of eight. Here, Cueball attempts to raise the question as he is standing with a package of hot dogs in one hand and a bag of buns in the other hand (presumably for their dinner), but a person offscreen interrupts him mid sentence and mentions condoms instead of buns. Cueball mulls the subject over in his mind, and when he realizes his friend is putting hot dogs in condoms, he is promptly grossed out. The title text makes it clear that Cueball's new found association of hot dogs with sexual activity , has put him totally off the idea of eating any of them this evening, and he suggests ordering pizza , which he then can hope will not be used for this similar ( NSFW ) comparisons … Cueball also asks that he and his friend never discuss this conversation again, due to the situation's awkwardness and uncomfortable subject matter. The style of the conversation with Cueball asking, someone answering and Cueball saying Eww is similar to a situation in the game comic 1608: Hoverboard where a giant ant queen inside the Destroyer is provoking Cueball in the same way by talking about laying eggs like this: Cueball: What's up? Ant queen: The usual. Poopin' out ants. Cueball: Eww. [Cueball is standing in the frame holding a bag and a package of hot dogs.] Cueball: Hey, why do hot dogs come in packages of ten- Offscreen: -But condoms come in strips of six? I know, right?! Cueball: ...Eww.

Gravitational Waves

Gravitational Waves

https://www.xkcd.com/1642

https://www.explainxkcd.com/wiki/index.php/1642:_Gravitational_Waves

[Cueball, with arms up, is standing behind Megan who has her hands at her mouth, and who in turn is standing behind Ponytail, who is sitting in front of a large computer console with a screen, a keyboard, and several items on the side (presumably lights and labels). Three wires lead away from the console out of the image to the right.] Megan: The gravitational wave detector works! For the first time, we can listen in on the signals carried by ripples in the fabric of space itself! [Larger panel with the same setting in the middle, but both Cueball and Megan have taken their arms down. More of the wires from the console can be seen to the right. The computer lists six events:] Computer: Event: Black hole merger in Carina (30 M ☉ , 30 M ☉ ) Computer: Event: Zorlax the Mighty would like to connect on Linkedin Computer: Event: Black hole merger in Orion (20 M ☉ , 50 M ☉ ) Computer: Event: Mortgage offer from Triangulum Galaxy Computer: Event: Zorlax the Mighty would like to connect on Linkedin Computer: Event: Meet lonely singles in the local group tonight!

Megan , Cueball , and Ponytail are observing the results from a gravitational wave detector (see details below ). This comic came out on the day that the first direct observation of gravitational waves was publicly announced on 2016-02-11. The actual event was recorded five months before on 2015-09-14, but it was not reported publicly before they were sure it was a real signal. It seems that Randall knew in advance about this announcement because this comic was published on a Thursday , not following the normal publish schedule, to coincide with the announcement , and there were no other comics released Friday that week. (The altered schedule could be viewed as a meta-reference to the warping of spacetime .) That scientists knew there might be an announcement on the way, and more details for the interested can be seen in these two videos from Space Time : Have Gravitational Waves Been Discovered?!? and LIGO's First Detection of Gravitational Waves! (See also their follow up The Future of Gravitational Waves ). This is the second time within a month that a new astronomical announcement (of something discovered months before the actual announcement) has resulted in a related comic. The first being 1633: Possible Undiscovered Planets . From the patterns in the gravitational waves detected by this instrument, it might be possible to guess the nature of the event (e.g. two bodies with dissimilar masses circling a fixed point, two bodies with equal mass circling each other, collision of two massive bodies, etc.). It might also be possible to triangulate the location of the event. Based on these two facts (the location and nature of the event) we might be able to determine which astronomical bodies caused this event (and the status of those bodies afterwards). Thus, it provides an additional medium to observe the universe in addition to telescopes observing all kinds of electromagnetic radiation . This new medium might enable us to observe properties that we couldn't observe with the rest of our observation instruments. However, the scientists in this comic appear to be receiving more than the expected signals from black hole collisions, they also receive gravitational spam messages , such as invitations from Linkedin , a mortgage offer, and an announcement of a social meet-up, rather than observing astronomical events (see table below ). There is also a joke on the social meet-up's use of the word local group because the ' Local Group ' is also the technical name for the group of galaxies containing the Milky Way . It is not clear if these so-called "events" are causing gravitational waves to be generated or if something, perhaps an alien civilization, is encoding spam messages in gravitational waves. It is plausible that aliens are using gravity waves to encode their messages, as we do something similar with electromagnetic waves to encode and send our messages. However, it would take an extremely advanced civilization to achieve gravity wave encoding. It requires the controlling of orbits and oscillations of super-massive bodies like the Sun, or more likely bodies ten times more massive than it. For example, the first event detected, both in this comic and in real life, was a merger of two black holes of roughly 30 solar masses each. The title text makes the speculation, that something is sending spam encoded in gravity waves, seem more plausible, as it follows up with a joke that the message senders have gone to such a length that they caused the most energetic event recorded ever (perhaps on the scale of a few supernovae or black hole collisions). One of the scientists is so impressed with this effort that he suggests that they actually post a reply, but one of the other person declines with a " Nah "! (As you should always do with spam, else you will just encourage the sender by making it clear that there actually is a receiver on this address.) Randall may have been referring to the fact that the detected event had a power output equal to 50 times that of the entire visible universe. In 1365: Inflation gravitational waves are also mentioned. A gravitational wave detector is a device used to measure gravitational waves, small distortions of spacetime that were first predicted by Albert Einstein in 1916. Gravitational waves are ripples in the spacetime fabric itself. In layman terms, a gravitational wave is like moving a stone through water while partly submerged. It will cause waves on the surface of the water as it moves through it. These waves will spread away from the center of disturbance and as they move, they will cause the water molecules to oscillate around their mean positions. Similar waves are created in the space-time fabric when two celestial bodies interact with each other. If you concentrate on an area of the fabric far away from the point of disturbance, it can be observed that if the wave causes compression in one direction, it'll cause expansion of the fabric in the other. See this page for nice animations. Note that anything with a mass will cause a gravitational wave. Just as waves created by small stones are tiny in comparison to waves created by huge rocks in water, the waves from humans moving around will be tiny compared to the waves created by celestial bodies. Also, the bigger the body, the stronger the wave and the farther away it can be detected. That is why we can only detect gravity waves from heavy bodies like black holes or neutron stars but not from us moving around. Now, let's consider spacetime fabric as a thin rubber sheet. If you mark any two points on this sheet and stretch or compress it along the axis joining those two points, the relative positions of these points with respect to their neighboring points do not change, but the distance between them changes. LIGO (Laser Interferometer Gravitational-Wave Observatory) is a large-scale physics experiment designed to detect this compression/expansion, and it was LIGO who discovered the signal that caused this comic. (For a very detailed description of what the team at LIGO did and the history behind see this 90 minutes feature Gravitational Waves: A New Era of Astronomy Begins from the 2016 World Science Festival). Two facts need to be remembered to easily understand the experiment. First, the speed of light (c) is constant and the speed of an object is the distance moved divided by the time taken to travel that far. Second, gravitational waves cause opposite effects (compression and expansion) in directions perpendicular to each other. At LIGO, an experiment is set up where two perpendicular long tunnels are constructed with apparatus to emit and detect laser beams. The beam from a laser is split into these two tunnels. After going through the tunnel and back again a few times the beams are brought back together. The lengths of the tunnels are set up in such a way that, in the absence of gravity waves, destructive interference between the two combined beams causes them to cancel one another out, resulting in the detector observing zero light intensity. When the gravitational wave passes through earth, one of the tunnel is expected to expand while the other is expected to compress. Due to the difference in lengths, the destructive interference is incomplete and the detectors will be able to detect the presence of light. This observation can be concluded as "detection of the gravitational wave passing through". [Cueball, with arms up, is standing behind Megan who has her hands at her mouth, and who in turn is standing behind Ponytail, who is sitting in front of a large computer console with a screen, a keyboard, and several items on the side (presumably lights and labels). Three wires lead away from the console out of the image to the right.] Megan: The gravitational wave detector works! For the first time, we can listen in on the signals carried by ripples in the fabric of space itself! [Larger panel with the same setting in the middle, but both Cueball and Megan have taken their arms down. More of the wires from the console can be seen to the right. The computer lists six events:] Computer: Event: Black hole merger in Carina (30 M ☉ , 30 M ☉ ) Computer: Event: Zorlax the Mighty would like to connect on Linkedin Computer: Event: Black hole merger in Orion (20 M ☉ , 50 M ☉ ) Computer: Event: Mortgage offer from Triangulum Galaxy Computer: Event: Zorlax the Mighty would like to connect on Linkedin Computer: Event: Meet lonely singles in the local group tonight!

Degrees

Degrees

https://www.xkcd.com/1643

https://www.explainxkcd.com/wiki/index.php/1643:_Degrees

[Cueball is looking at his smartphone while a friend calls to him from off-panel. Cueball is thinking as indicated with a thought bubble.] Off-screen voice: Hey, what's the temperature outside? Cueball (thinking): Should I give it in °F or °C? [Zoom in on Cueballs head with a list of reason to use Celsius above him:] Degrees Celsius International standard Helps reduce America's weird isolationism Nice how "negative" means below freezing Physics major loyalty Easier to spell We lost a Mars probe over this crap [Same view of Cueballs head, but wider frame to accommodate a broader a list of reason to use Fahrenheit:] Degrees Fahrenheit 0°F to 100°F good match for temperature range in which most humans live Rounds more usefully (70's, 90's) Unit-aware computing makes imperial less annoying SI prefixes are less relevant for temperatures Fahrenheit is likely more clear in this context Valuing unit standardization over being helpful possibly makes me a bad friend [Cueball is holding his smartphone down while thinking as indicated with another thought bubble floating at the top. He then speaks and gets a reply from his off-panel friend.] Cueball (thinking): Crap, gotta pick something. Uhh... Cueball: ...0.173 radians. Off-screen voice: I'll just go check myself

Cueball is being asked by a friend for the temperature . While he is checking his smartphone for the weather, he begins pondering what unit he should use when answering the question. (See below for Cueball's reasoning .) In the US (where Cueball and Randall are from), the temperature scale used in daily life is Fahrenheit . However, most of the rest of the world uses Celsius in daily life, and even in the US it is commonly used for science. This is also why Randall has previously made the comic 526: Converting to Metric . There are also people who wish the US to change to the metric system, although some of them still wish to keep the Fahrenheit scale as mentioned in 1982: Evangelism The Celsius scale is from the metric system . Though this system has been officially sanctioned for use in the US since 1866, it is not frequently used in daily American life (except for some things, like liter bottles of soda), although it is the preferred system for trade and commerce according to the Metric Conversion Act of 1975. The US remains the only industrialized country, and one of few countries period, that does not use the metric system for every day measurements, and in which official government documents and signage do not enforce metric units. The unit degree Celsius or °C is an accepted derived unit from the International System of Units (SI units) used in science (which again is the modern form of the metric system). The SI unit of temperature is the kelvin , but this temperature scale is linearly related to the Celsius scale, which is why Celsius can be derived from it. The Fahrenheit scale is from the US customary system and the (British) imperial system . The unit is degree Fahrenheit or °F, and the relation to the Celsius scale is not easy to find in a mental calculation. The relations are: [°F] = [°C]×9⁄5 + 32 or [°C] = ([°F] − 32)×5⁄9. (For this exact reason Randall has previously made a helpful table for these situations in 526: Converting to Metric .) Unlike most areas of measurement, where the metric system is widely considered superior, there is considerable debate about the relative merits of Fahrenheit vs. Celsius. Cueball weighs up the benefits of both scales, but fails to find a solution he can live with, and since he feels he has to give his friend an answer now, he panics and gives the answer 0.173 radians . Radian is the standard unit of angular measure, used in many areas of mathematics. An angle's measurement in radians is numerically equal to the length of a corresponding arc of a unit circle . It has no units and is denoted with the superscript c , but more commonly rad , lest it be confused with angular degrees . One radian is an angle of approximately 57.3 degrees. Angular degrees is a system used to measure angles in geometry , and although it too uses the symbol ° and the word "degrees", it has nothing to do with temperature measurements of any sort. Thus, this answer is unhelpful and the joke is that traditionally both geometric angles and temperature are measured in "degrees", but there is no connection between the two. The title text indicates that Cueball's friend still wants to know whether the answer is in radians Fahrenheit or radians Celsius, which, despite being a silly way to express temperature, would actually enable the friend to get some meaning out of the reply. But this just takes Cueball back to the problem he failed to solve in the first place of choosing one scale in preference to the other, so suddenly he announces has to go and runs off without ever clarifying what he meant. This result is probably because he is afraid of being a bad friend according to his very last point regarding Fahrenheit: Valuing unit standardization over being helpful possibly makes me a bad friend. The answer Cueball gives of 0.173 radians corresponds to a geometric angle 9.91° (0.173 × 360° / 2π ). If this were "radians Celsius" it would be 9.91 °C corresponding to 49.8 °F and if it were "radians Fahrenheit" it would be 9.91 °F corresponding to -12.3 °C. Given the temperatures in Massachusetts (where Randall lives) when this comic came out, the day after Valentine's Day 2016, Cueball was probably giving his answer in radians Fahrenheit. International standard Degrees Celsius is derived unit in the SI system of units used to measure temperature in most countries today. Using the SI system would allow Cueball to be easily understood in most countries and is by far the most recognized system, but it is not the most commonly used in the United States, his presumed location in the comic. Helps reduce America's weird isolationism The United States uses its own set of units, including degrees Fahrenheit, called the United States customary system (similar but not equal to the imperial system), in contrast to most of the rest of the world, which uses the SI system. The US's system of units is therefore considered "weird" as it makes the US different from most of the world, but previous efforts to convert the US to the SI system have failed. Cueball evidently believes that by using SI units, he will help to eventually convert the US to the SI system, bringing considerable trade and tourism benefits and reducing confusion when dealing with foreigners. Nice how "negative" means below freezing On the Celsius scale, the freezing point of water at standard atmospheric pressure (101.325 kilopascals) is very close to 0 °C, and any temperature below that is below the freezing point. The Fahrenheit scale uses different points of reference (using a water/ammonium chloride chemical reaction for the lower calibration, while the upper calibration is set such that water freezing and water boiling are 180 degrees apart), and as a result the freezing point of water is a less memorable 32 °F. Physics major loyalty Cueball is apparently a physics major, like Randall, and SI units are more commonly used for scientific work (as the kelvin scale is sometimes used in physics and other sciences), even in the US. By using the Celsius scale in casual conversation, he would show his loyalty to the system used by actual physicists. Easier to spell "Celsius" is generally considered to be an easier word to spell than the German surname "Fahrenheit" (at least this is the case for Cueball, but not necessarily for those who more commonly use Fahrenheit than Celsius). In this case the word is being spoken and the point is not immediately relevant, but part of the joke is that Cueball is overthinking things and worrying about the general use of the word when an answer is needed in this specific case. We lost a Mars probe over this crap The Mars Climate Orbiter disintegrated in Mars' atmosphere because Lockheed used US customary units instead of the contractually specified metric units. This had nothing to do with temperature scales, but was the use of the unit pound-seconds where newton-seconds should have been used. This was a great and tragic loss for science in general, Mars exploration in particular, and thus also for Randall who has shown deep interest in any kind of space exploration, especially regarding Mars (mentioning many Mars probes in his comics so far). 0 °F to 100 °F good match for temperature range in which most humans live In the context of air temperature, 0 °F and 100 °F correspond to "just about as cold as it gets" and "just about as hot as it gets" in temperate zones, thereby making Fahrenheit a useful temperature scale for weather reporting where most people live. By contrast, in Celsius a range of common temperatures in temperate zones is -20 °C to 40 °C, which is a less intuitive range for those used to the Fahrenheit scale. Rounds more usefully (70's, 90's) An argument sometimes heard for the continued use of Fahrenheit temperatures is that each 10 degrees change is meaningful in how we feel the temperature. Thus, it is convenient to talk about the temperature being in the 70's today, or in the 90's, etc. Since the Celsius degrees are almost twice as large, a similar statement about the temperature being in the 20's or 30's is not as useful, unless more precision is added by using phrases like low 20's or high 30's. However, this seems likely to be more a matter of which scale you are used to using than anything inherent in one scale or the other. Unit-aware computing makes imperial less annoying If you need to constantly convert between imperial and SI measurements in your head, or even between different imperial units (e.g., ounces and pounds), it gets annoying and is a strong argument for everyone using metric measurements all the time. But when it is easy to get the temperature - or any other measurement - reported in whatever units you want just by selecting the units you want your computer to report, then the annoyance is minimized, and the arguments for why we should stop using a familiar scale are weakened. Note that Cueball is looking at his smart-phone to get the current temperature. As many Americans, Randall is confusing the United States customary system with the imperial system used in most of the rest of the English speaking world. In both systems temperature is measured in degrees Fahrenheit. SI prefixes are less relevant for temperatures One of the nice things about SI measurements is how the same basic unit scales by factors of 10 with common prefixes - e.g., kilometer, millimeter, kilogram, milligram, etc. Imperial measurements don't have this feature - you don't talk about long distances as kiloinches or small weights as millipounds. But, we generally don't use multiple units for atmospheric temperature (millidegrees or kilodegrees), so this argument for using SI measurements for length, mass, volume, etc., isn't as applicable for temperature scales. Fahrenheit is likely more clear in this context The fact that Cueball is having this conflict at all implies that the conversation is taking place in America, presumably between Americans. Given that, and given that the discussion is about the weather, the typical assumption is that temperatures will be given in Fahrenheit, unless specified otherwise. An answer in Fahrenheit is therefore likely to be easily understood, while an answer in Celsius risks being confusing, or even incomprehensible. Valuing unit standardization over being helpful possibly makes me a bad friend The final thing Cueball considers is to question why he would give an answer that attaches more value to promoting standardization of units when all his friend wants to know is whether it is cold or warm outside. Wouldn't it be more friendly to just answer the question the way his friend will find most convenient? This is probably the reason he ends up not giving any real answer, as giving the answer in Celsius would make him a bad friend. Giving the answer in panic in radians makes him a weird friend, which might or might not be preferable to being a bad friend. [Cueball is looking at his smartphone while a friend calls to him from off-panel. Cueball is thinking as indicated with a thought bubble.] Off-screen voice: Hey, what's the temperature outside? Cueball (thinking): Should I give it in °F or °C? [Zoom in on Cueballs head with a list of reason to use Celsius above him:] Degrees Celsius International standard Helps reduce America's weird isolationism Nice how "negative" means below freezing Physics major loyalty Easier to spell We lost a Mars probe over this crap [Same view of Cueballs head, but wider frame to accommodate a broader a list of reason to use Fahrenheit:] Degrees Fahrenheit 0°F to 100°F good match for temperature range in which most humans live Rounds more usefully (70's, 90's) Unit-aware computing makes imperial less annoying SI prefixes are less relevant for temperatures Fahrenheit is likely more clear in this context Valuing unit standardization over being helpful possibly makes me a bad friend [Cueball is holding his smartphone down while thinking as indicated with another thought bubble floating at the top. He then speaks and gets a reply from his off-panel friend.] Cueball (thinking): Crap, gotta pick something. Uhh... Cueball: ...0.173 radians. Off-screen voice: I'll just go check myself

Stargazing

Stargazing

https://www.xkcd.com/1644

https://www.explainxkcd.com/wiki/index.php/1644:_Stargazing

[A thin panel with Megan as a TV-host is holding her hands up. She is drawn in white on a black background. Behind her is an audience drawn in faint gray lines consisting of Hairy (to the left) and two Cueball-like guys and Ponytail (seen in a rare full face position) to the right of the host. One of the Cueball-like guys is partly hidden behind the host.] Host: Welcome to stargazing, with your host, me. Host: I'm a doctor or whatever. [Same scene as before but in a broader panel, and the host is now holding only one hand up with a finger pointing up. The audience is the same four people, but now Hairy has moved further to the left in the panel to make room for a Megan-like woman also to the left of the host.] Host: I'm not gonna waste your time on the shitty stars. Host: Just the good stuff. Host: Honestly half of 'em just look like dots. [A frame-less drawing with a zoom out showing the group of six people in black silhouette on a white background. Part of the ground beneath them is shown as a black pool. The host is pointing up with one hand. The people have been rearranged, so left of the host is now a Cueball-like guy and a Megan-like woman, and to the right is the other Cueball-like guy, then Ponytail (seen from the side as usual) and Hairy. All are looking up following the host's directions.] Host: This is Sirius. It's the brightest star in our sky so it's in charge. Host: It's really two stars but one of them is barely even trying. Host: This is Andromeda, it's too big to think about, so let's not. [Zoom in of the host's upper body, again drawn in white on a black background. She is looking right gesturing with one arm raised, and the other still pointing up with a finger stretched out. Her audience is no longer shown.] Host: That red stars is Betelgeuse. It's gonna explode someday. Host: Can't happen soon enough, as far as I'm concerned. I- Host: Holy shit did you see that meteor!?! Host: Space is awesome! [Same scene as the previous panel, but the host has turned towards left looking at someone in the audience (not shown) who speaks off-screen. She has taken both her hands down for the first time.] Off-screen voice: Are you sure you're an astronomer? Host: People keep asking that, so I finally tried to look that word up in a dictionary, and wow is that book ever boring. No thank you. Off-screen voice: But- Host: Space! (Inverse color panel - white on black) [A television host in the foreground, speaking toward the reader. A group of other people are in the background behind them.] Host: Welcome to Stargazing, with your host, me. I'm a doctor or whatever. [She continues to talk.] Host: I'm not gonna waste your time on the shitty stars. Just the good tuff. Honestly half of 'em just look like dots. (Normal color panel - black on white) [A shot from far away of the host standing in the center of the group of people watching her, she points to the sky.] Host: This is Sirius. It's the brightest star in our sky so it's in charge. It's really two stars, but one of them is barely even trying. This is Andromeda. It's too big to think about, so let's not. (Inverse color panel) [Close-up on the host gesturing toward the sky behind her.] Host: That red star is Betelgeuse. It's gonna explode someday. Can't happen soon enough, as far as I'm concerned. I-- HOLY SHIT DID YOU SEE THAT METEOR?!?! Space is awesome! [The host speaks to someone out of panel.] Other: Are you sure you're an astronomer? Host: People keep asking that, so I finally tried to look that word up in a dictionary, and wow is that book ever boring. No thank you. Other: But-- Host: SPACE! The original official transcript with male host is included here below (correcting a typo with a missing "s" in "stuff" and formatting to look like our normal transcripts): [A television host in the foreground, speaking toward the reader. A group of other people are in the background behind them.] Host: Welcome to Stargazing, with your host, me. I'm a doctor or whatever. [He continues to talk.] Host: I'm not gonna waste your time on the shitty stars. Just the good stuff. Honestly half of 'em just look like dots. [Normal color panel - black on white. A shot from far away of the host standing in the center of the group of people watching him, he points to the sky.] Host: This is Sirius. It's the brightest star in our sky so it's in charge. It's really two stars, but one of them is barely even trying. This is Andromeda. It's too big to think about, so let's not. [Inverse color panel. Close-up on the host gesturing toward the sky behind him.] Host: That red star is Betelgeuse. It's gonna explode someday. Can't happen soon enough, as far as I'm concerned. I-- HOLY SHIT DID YOU SEE THAT METEOR?!?! Space is awesome ! [The host speaks to someone out of panel.] Other: Are you sure you're an astronomer? Host: People keep asking that, so I finally tried to look that word up in a dictionary, and wow is that book ever boring. No thank you. Other: But-- Host: SPACE!

This is the first comic in the Stargazing series. It was followed by 2017: Stargazing 2 two and a half years later and 2274: Stargazing 3 four years later. This comic opens on Megan as the host for a stargazing TV show, or simply a stargazing tour. She claims to be a doctor in astronomy though her remarks, however enthusiastic, may call this into question. (Originally the host was suspected to be a spoof on Brian Cox , see below , but at some later point Randall changed his official transcript thus making the host female rather than male as in the original version, see the trivia section below. Thus now the host is clearly Megan, which it could not have been originally when the host was described as a man by Randall). Throughout the comic the host's tone and choice of words becomes increasingly unprofessional, referring to most of the stars as "shitty," personifying them based on different astronomical observations, and providing little useful information on the study of stars or how they work. It seems that this is not an isolated issue as the television host mentions that people keep asking her whether or not she is a real astronomer. The host also continuously glosses over the arguably less exciting portions of a typical presentation on astronomy sharing only what she sees as "the good stuff." This penchant for only caring about something if it is interesting extends past astronomy as well as the host is too bored when reading the dictionary to look up the meaning of astronomer. The comic derives much of its humor from the absurdity of the host's comments on various astronomical bodies. Although not technically incorrect, the way she presents the information is far from informative. (See details below on the host's observations ). One of her observations regards the fact that Sirius is a binary star , a system where two stars orbit each other. So even though it is the brightest star as seen from Earth we only really see one of them, as the other is, to quote the host, "not even trying". Sirius A is "large" and "bright" main sequence white star, while Sirius B is a white dwarf with a little under half the mass, 0.49% the radius and only 0.22% the luminosity of Sirius A. Andromeda is the largest galaxy in our Local Group . It is 220,000 light years across and contains a trillion stars. Humans have difficulty conceptualizing distances of this scale. Suffice to say that it is very large. [ citation needed ] Betelgeuse is the 9th brightest star visible from earth. One of its prominent features is its visible redness. Within the next million years (or maybe only 100,000 years) it is expected to explode as a supernova , which will certainly be a spectacular sight. It could happen anytime now, and the host hopes it will be in her lifetime. In the title text it is mentioned that the Sun is also a star and of course is much brighter than Sirius seen from Earth, and thus Sirius is technically not the brightest star in our sky (although it is in the night sky). The title text sarcastically encourages the audience to raise that obvious but irrelevant point (a standard joke when people mention bright stars) instead of asking a more interesting, informative, or fruitful question, when there are so many to ask regarding astronomy. See also 1371: Brightness and 1342: Ancient Stars . Saying cool things about space to make people like you is mentioned in 1746: Making Friends . Here is a list of the host's observations: The comic could be a reference to BBC's Stargazing Live , which Brian Cox has appeared in since 2011. If drawn in xkcd style he would likely look like Megan. He has a PhD in high-energy particle physics , but not astronomy. The newest season of the show aired during January 2016 just a month before this comic's release. Brian Cox has also been the presenter of several other science programs, especially such as the Wonders of the Solar System , Wonders of the Universe and Wonders of Life . Originally the host was described as male in the official transcript (see trivia below, making this seem more likely. for some reason Randall changed the host to female in the transcript later. Very strange, but for sure when he was male, it was obviously a Brian Cox spoof. It could also be a reference to Jack Horkheimer 's PBS shows Star Hustler and Star Gazers . Horkheimer, however, does not at all look like Megan, and he died 6 years ago. But he was not a doctor in astronomy, only getting into it when he started volunteering at the Miami Museum of Science's planetarium. He ended up writing shows for the planetarium and the PBS series developed from there. He rarely covered facts about the night sky that couldn't be found in any basic reference (possibly because the show was aimed at children and non-astronomy buffs), although he did get more in-depth about current astronomical events such as Comet Hale–Bopp . [A thin panel with Megan as a TV-host is holding her hands up. She is drawn in white on a black background. Behind her is an audience drawn in faint gray lines consisting of Hairy (to the left) and two Cueball-like guys and Ponytail (seen in a rare full face position) to the right of the host. One of the Cueball-like guys is partly hidden behind the host.] Host: Welcome to stargazing, with your host, me. Host: I'm a doctor or whatever. [Same scene as before but in a broader panel, and the host is now holding only one hand up with a finger pointing up. The audience is the same four people, but now Hairy has moved further to the left in the panel to make room for a Megan-like woman also to the left of the host.] Host: I'm not gonna waste your time on the shitty stars. Host: Just the good stuff. Host: Honestly half of 'em just look like dots. [A frame-less drawing with a zoom out showing the group of six people in black silhouette on a white background. Part of the ground beneath them is shown as a black pool. The host is pointing up with one hand. The people have been rearranged, so left of the host is now a Cueball-like guy and a Megan-like woman, and to the right is the other Cueball-like guy, then Ponytail (seen from the side as usual) and Hairy. All are looking up following the host's directions.] Host: This is Sirius. It's the brightest star in our sky so it's in charge. Host: It's really two stars but one of them is barely even trying. Host: This is Andromeda, it's too big to think about, so let's not. [Zoom in of the host's upper body, again drawn in white on a black background. She is looking right gesturing with one arm raised, and the other still pointing up with a finger stretched out. Her audience is no longer shown.] Host: That red stars is Betelgeuse. It's gonna explode someday. Host: Can't happen soon enough, as far as I'm concerned. I- Host: Holy shit did you see that meteor!?! Host: Space is awesome! [Same scene as the previous panel, but the host has turned towards left looking at someone in the audience (not shown) who speaks off-screen. She has taken both her hands down for the first time.] Off-screen voice: Are you sure you're an astronomer? Host: People keep asking that, so I finally tried to look that word up in a dictionary, and wow is that book ever boring. No thank you. Off-screen voice: But- Host: Space! (Inverse color panel - white on black) [A television host in the foreground, speaking toward the reader. A group of other people are in the background behind them.] Host: Welcome to Stargazing, with your host, me. I'm a doctor or whatever. [She continues to talk.] Host: I'm not gonna waste your time on the shitty stars. Just the good tuff. Honestly half of 'em just look like dots. (Normal color panel - black on white) [A shot from far away of the host standing in the center of the group of people watching her, she points to the sky.] Host: This is Sirius. It's the brightest star in our sky so it's in charge. It's really two stars, but one of them is barely even trying. This is Andromeda. It's too big to think about, so let's not. (Inverse color panel) [Close-up on the host gesturing toward the sky behind her.] Host: That red star is Betelgeuse. It's gonna explode someday. Can't happen soon enough, as far as I'm concerned. I-- HOLY SHIT DID YOU SEE THAT METEOR?!?! Space is awesome! [The host speaks to someone out of panel.] Other: Are you sure you're an astronomer? Host: People keep asking that, so I finally tried to look that word up in a dictionary, and wow is that book ever boring. No thank you. Other: But-- Host: SPACE! The original official transcript with male host is included here below (correcting a typo with a missing "s" in "stuff" and formatting to look like our normal transcripts): [A television host in the foreground, speaking toward the reader. A group of other people are in the background behind them.] Host: Welcome to Stargazing, with your host, me. I'm a doctor or whatever. [He continues to talk.] Host: I'm not gonna waste your time on the shitty stars. Just the good stuff. Honestly half of 'em just look like dots. [Normal color panel - black on white. A shot from far away of the host standing in the center of the group of people watching him, he points to the sky.] Host: This is Sirius. It's the brightest star in our sky so it's in charge. It's really two stars, but one of them is barely even trying. This is Andromeda. It's too big to think about, so let's not. [Inverse color panel. Close-up on the host gesturing toward the sky behind him.] Host: That red star is Betelgeuse. It's gonna explode someday. Can't happen soon enough, as far as I'm concerned. I-- HOLY SHIT DID YOU SEE THAT METEOR?!?! Space is awesome ! [The host speaks to someone out of panel.] Other: Are you sure you're an astronomer? Host: People keep asking that, so I finally tried to look that word up in a dictionary, and wow is that book ever boring. No thank you. Other: But-- Host: SPACE!

Toasts

Toasts

https://www.xkcd.com/1645

https://www.explainxkcd.com/wiki/index.php/1645:_Toasts

[There are two rows of 4 panels each. Each panel shows a different person offering a toast. Each one has some kind of drink in one hand which they hold up.] [First row panels:] [Cueball holding up a wine glass to the right:] Cueball: Champagne for my real friends and real pain for my sham friends! [Blondie holding up a regular glass to the left:] Blondie: Pseudopods for my real friends and real pods for my pseudo-friends! [Megan holding up a drinks glass to the right:] Megan: Petticoats for my real friends and real coats for my petty friends. [A "brunette" woman (i.e. similar hair but less dark than Megan) holding up a normal glass with a small umbrella in it to the right:] Brunette woman: Loosestrife for my real friends and real strife for my loose friends! [Second row panels:] [Hairbun holding up a wine glass to the left:] Hairbun: Ladybugs for my real friends and real bugs for my lady friends! [White Hat holding up a regular glass to the right:] White Hat: Single-payer for my real friends and RealPlayer for my single friends. [Ponytail holding up a regular glass to the right:] Ponytail: Tumbleweeds for my real friends and real weed for my Tumblr friends! [Beret Guy holding up a wine glass to the left:] Beret Guy: Fauxhawks for my real friends and real hawks for my faux friends!

A toast is a ritual in which a drink is taken as an expression of honor or goodwill. The term may be applied to the person or thing so honored, the drink taken, or the verbal expression accompanying the drink. Thus, a person could be "the toast of the evening," for whom someone "proposes a toast" to congratulate and for whom a third person "toasts" in agreement. The comic is based on the quote Champagne for My Real Friends, Real Pain for My Sham Friends which, though often attributed to the painter Francis Bacon or to Tom Waits , is a toast dating back to at least the nineteenth century. It is also the entire title of a song , the ninth track on From Under the Cork Tree , a 2005 album by Fall Out Boy . The comic plays on a permutation structure between two words (a type of chiasmus ), yielding puns with various effects. In this comic eight persons drink a toast for their "real friends" and then for some other type of "friends". For the real friend they wish them to have one specific thing. This something is a word (X-Y) that can be split up in two meanings (X and Y), where one of them are then put in front the word friend, to explain what type of friends they are now toasting (often a bad/false type of friend) and then these friends get a wish for having what the word that are left of the original word means: "X-Y for my real friends and real Y for my X friends" The first example is a typical toast, in Champagne, where this word can be split in the two phonetically similar words Sham and Pain, and the sham friends then get pain. Below all examples (including the ninth from the title text) are listed with explanation for all words. In some cases the word may actually refer to a drink (like the first with champagne), so that the first word is not something wished for the real friends, but the drink that is in the glass (these have been mentioned below). But for other toasts there is no such drink in existence, and the first word is the thing the toaster wishes for the real friends. [There are two rows of 4 panels each. Each panel shows a different person offering a toast. Each one has some kind of drink in one hand which they hold up.] [First row panels:] [Cueball holding up a wine glass to the right:] Cueball: Champagne for my real friends and real pain for my sham friends! [Blondie holding up a regular glass to the left:] Blondie: Pseudopods for my real friends and real pods for my pseudo-friends! [Megan holding up a drinks glass to the right:] Megan: Petticoats for my real friends and real coats for my petty friends. [A "brunette" woman (i.e. similar hair but less dark than Megan) holding up a normal glass with a small umbrella in it to the right:] Brunette woman: Loosestrife for my real friends and real strife for my loose friends! [Second row panels:] [Hairbun holding up a wine glass to the left:] Hairbun: Ladybugs for my real friends and real bugs for my lady friends! [White Hat holding up a regular glass to the right:] White Hat: Single-payer for my real friends and RealPlayer for my single friends. [Ponytail holding up a regular glass to the right:] Ponytail: Tumbleweeds for my real friends and real weed for my Tumblr friends! [Beret Guy holding up a wine glass to the left:] Beret Guy: Fauxhawks for my real friends and real hawks for my faux friends!

Twitter Bot

Twitter Bot

https://www.xkcd.com/1646

https://www.explainxkcd.com/wiki/index.php/1646:_Twitter_Bot

[Cueball is sitting at a desk using a laptop, his thoughts shown above in a thought bubble. A search query is shown in a frame to indicate what Cueball has searched for with the search button below in gray text:] Cueball (thinking): I want to make a Twitter bot. I bet it's not too hard. Query: How to write a Twitter bot Search [Cueball is now holding the laptop on his lap, a series of search queries are shown.] Query: Python Twitter library Search Query: Machine learning Search Query: Cloud hosting Search [Cueball has placed the laptop back on the desk. More search queries are shown, each one more ominous than the previous.] Query: Bot troubleshooting Search Query: Locked out of EC2 instance Search Query: Bot changed own password? Search [Cueball is shown wearing a small backpack and typing on his smartphone while jogging to the right. various noises coming from left and right seem to imply that chaos has begun to erupt around him. The loudest noise is in a ragged frame to the left, coming from off-panel left, it is between the first and second query. Also between these but to the right are other sounds coming from off-panel right.] Query: How to fight a bot Search Noise off-panel left: Boom Noise off-panel right: Pew Pew Pew Query: Cheap flights Australia Search On March 23, 2016, a month after the release of this comic, Microsoft released the Twitter bot Tay causing many controversies and was shut down only 16 hours after its launch. It's unknown if some people at Microsoft were inspired by this comic.

A Twitter bot is a program that can post automatically to Twitter . Although Twitter bots can be very elaborate, a lot of people write simple bots for fun that simply engage in automated wordplay. Cueball thinks he'll write a Twitter bot, figuring out it won't be too hard. The web searches he makes tell what happens next, i.e. the bot balloons in complexity until it starts following its own goals and Cueball no longer has any control over its actions. This comic examines how a seemingly simple task can often balloon in complexity if all of the requirements are not understood, while at the same time presenting the stereotypical scenario where an unassuming idea results in the accidental creation of malevolent AI , which then attempts to destroy humanity. The story, as told by the web searches, is as follows: [Cueball is sitting at a desk using a laptop, his thoughts shown above in a thought bubble. A search query is shown in a frame to indicate what Cueball has searched for with the search button below in gray text:] Cueball (thinking): I want to make a Twitter bot. I bet it's not too hard. Query: How to write a Twitter bot Search [Cueball is now holding the laptop on his lap, a series of search queries are shown.] Query: Python Twitter library Search Query: Machine learning Search Query: Cloud hosting Search [Cueball has placed the laptop back on the desk. More search queries are shown, each one more ominous than the previous.] Query: Bot troubleshooting Search Query: Locked out of EC2 instance Search Query: Bot changed own password? Search [Cueball is shown wearing a small backpack and typing on his smartphone while jogging to the right. various noises coming from left and right seem to imply that chaos has begun to erupt around him. The loudest noise is in a ragged frame to the left, coming from off-panel left, it is between the first and second query. Also between these but to the right are other sounds coming from off-panel right.] Query: How to fight a bot Search Noise off-panel left: Boom Noise off-panel right: Pew Pew Pew Query: Cheap flights Australia Search On March 23, 2016, a month after the release of this comic, Microsoft released the Twitter bot Tay causing many controversies and was shut down only 16 hours after its launch. It's unknown if some people at Microsoft were inspired by this comic.

Diacritics

Diacritics

https://www.xkcd.com/1647

https://www.explainxkcd.com/wiki/index.php/1647:_Diacritics

[Cueball sitting in front of his lap top typing. The text above him is the one he is typing. The last word résumé has too many diacritics. The u has an umlaut (as in ü) and the last é has no less than six diacritics; a cedilla below (as in ȩ), a ring above (as in e̊ ), then three acute accents above the ring (as in é), and finally they are topped off by a breve (as in ĕ). In addition, find is spelled fīnd with a macron over the i . Also, the last full stop has three accents "´" above it:] Cueball (typing): Attached please fīnd my résümȩ̊́́́̆.́́́ [Caption below the panel:] I usually leave out diacritics when I type, so I make up for it by occasionally adding a whole bunch at once.

A diacritic (or a diacritical mark) is a glyph added to a letter. The main use of diacritical marks in the latin script is to change the sound-values of the letters to which they are added, typically vowels . Cueball is writing an e-mail (maybe for a job application) and notes in the mail that he attaches his résumé , or curriculum vitae . The word résumé uses two e s with an acute accent so they look like this: é. While diacritics can be common in several languages, English is an example of a language that rarely ever has any at all. This occurs to such an extent that words and expressions borrowed from other languages (such as "résumé" or "piñata") are frequently written in English with the diacritics omitted, as in "resume" or "pinata". As Cueball/ Randall is a native English speaker, it is thus natural that he often forgets (or just doesn't bother) to add these diacritics, hence the title of the comic. When he occasionally remembers them, for instance when he types a word where he knows they should be included, like résumé, he then makes up for all those he must have forgotten since last time he thought of it, and thus adds a whole bunch at once. This reason is somewhat nonsensical. Randall may be poking fun at people who use Zalgo , a form of spam where people continuously spam diacritics in chat messages. For example: T̯̙̻̼̠͕̙̬̬̜̼̊ͥͦͬͤ̇̎̆̌ͭ͢͠͡o̡̲̩̟̲̬̰̪̜̝͙̺̦̙͍̳ͬͯͯ͋͒̍ͨ̓̇́̚̚̕ ̸̢̬̘̦͕̯̱̜̲̼̤ͬͧͤͨǐ̷̷̯̼̝̹̫ͪ̀̋̿̄̓n̿͂ͩ͂ͮ̔̆͏͎͍͕̜͎̺̯͈̼̩̣̥̬͡͞ͅͅv̴̨̙̼̤̼͙͖̫̖̺̹̠̹̦́͌͑̓̆̂ͯ̑̈̏ͭo̢̫̲̙̺̬̤̲̳ͨ̐ͦ̽͛ͮ͛́͂ͣ͂ͮ͆͑̍̀ͯ̕͟k̵̨̫̙̤͙̹̫͚͈̪͇͓͈̫̬̥͕̱͎̜̉̔ͬͭͦ̓͐ͫ̋̋ͥ̋̀̕͟è̢̛͑͋͐̀̏ͣ̏ͬ̒̌͌́̚͘͝͏̟̞͇̘̤̼̮̤͍͚̫̤͚̰ ̶̧̮̗̣̫͇̦͎̮̤̗͙̗̳͎̺͆̉̈ͭ̽̈́̌̽ͥ̾͑̀̚̚͘͟ͅͅt̸͓͉̩́̓̓ͮ̇̈̆ͣ̀ͪͬ͑̅ͣ̍h̸̡̧ͧ͑̐̂ͥ̄̃̂̄́͋ͨ͑̓̆͋̚͏̸̟̣̤̺͔̘̞̦̖͖̣̺̱̜͔̗̫̰ͅȇ̡͇͎͎̩̮̟̖̖̤̦̜͍̱̇ͨ̃̈́̄̑ͦͭ̚͞ͅ ̛̼̤̟̩̦̻̤̙̥̬̠̩̙̙̱͚͕ͫ͐̏ͥ̄ͧͧͭ̔̆͐̋͘h̶̵̜̤͓̹̰ͣ̄͗́́i̝͕̘̗͉͚̰͓̮͕̣͒̂̒ͨ̽ͫ̎ͪͦ́̕͝ͅv̧̙̞̣̳͍̟̖͚̻̝͈ͧ͊ͫ͋ͩͫ̍͋̏̽ͤ̀͝͞ͅẻ̢͓̣̰͔̟͎̥̻̤̲̟̣̜̄̈́̌͛̌̄͢͞ͅ-̨̡͆̓̌̎̉̑҉͚̝̗m̨̛͎̬͉̯̽ͥͫ̇ͦ̒̿̎́͒́̚͡͠ỉ̧̡͖͙̙͕͔̲ͩ́ͣ͐ͧ͑̊̾̒͑̅͗̊́̎̚n̠̮̜̝̜̤̰̻̘͖̦͚̼ͫ̄͐͗ͣ́͢͜d̡̛̳͕̬̫̯̩͕̰̖̟̲͕͙ͭ̅̓ͥ͛ͨ͒ͯ͌̚ͅͅ ̟̜̳̫͕̺͎̺̲̗̋̐̀͛͑̅̅͛̾̈́̀̚͞͠r̸̯̥͚̟̰͉͎͓̖͉͂̎̅̐ͫͧ͛ͯ͜ë́̎͂̆ͥͩ͟͏̰̤̳͓̩͉̲̣̠͍͔̗̦̬̱̯p̽ͧ͒͗ͣ̿̆̄̑͏̘̜̥̠̜̥̘̲̮̹̤̪̦͕͇͓͞r̴͓̼̺̰̹͙͉̦͚̞̤͕̭̦̈́ͫ̔̂̓̆̒͗͛̿̑̉̿̓ͤ̏̇̀̚͘͘͢é̴̢̛̖̗̖̤ͧ̽͑ͨ̒̌̍ͭ̑̋̃̒ͫ̀͡ş̶͉͚̠̠͇͓̬̙͚̖̝͓͕̤̟́̂̏ͧͩ͌͑͐ͣ͌͌̄̾̿ȩ̢͈̗̝͍ͨ̒͗ͭ̔̈͆ͫ̔ͨ̈́́̊ͣ̃̎̀͝͝n̸̟͔̺̠̺̓̑̏͐ͩͬ̏̈́̌͒́̏ͥ̌̍͊ͧ̀̚͜͞͞tͮ̾͒̇̐ͩ͆̓ͣ҉̢̤͖̩͕̬̮͚͙̖͕̬̘̙͘͠ͅĩ̡̬̙̙̯̩͋̋̄n̡̡̊̐͌ͣ̍̒̽ͩͫ͌ͦ̚͝͏̳̻̞͓̗̹̪̜̘̰̠̟͈̮̲̳̜g̵̎̓́̃ͮ̍̏̈̄ͧ̈́̐̔̏ͤͭͨ҉̛̘̰̘̟̬̝̰̜̗̼ͅͅ ̸̦̞͓̟͉̫͔̦̰̝͈̩̳̞̼̮̩̬͕̿ͩ͗̂̌̐ͭ͟͞c̳̻͚̻̩̻͉̯̄̏͑̋͆̎͐ͬ͑͌́͢h̵͔͈͍͇̪̯͇̞͖͇̜͉̪̪̤̙ͧͣ̓̐̓ͤ͋͒ͥ͑̆͒̓͋̑́͞ǎ̡̮̤̤̬͚̝͙̞͎̇ͧ͆͊ͅo̴̲̺͓̖͖͉̜̟̗̮̳͉̻͉̫̯̫̍̋̿̒͌̃̂͊̏̈̏̿ͧ́ͬ̌ͥ̇̓̀͢͜s̵̵̘̹̜̝̘̺̙̻̠̱͚̤͓͚̠͙̝͕͆̿̽ͥ̃͠͡.̔̈́ͤͣͪ̅̎̄̽ͩͪ͛̓̂̂̑͒҉̤͍͔̲̣̜͕̺͕͇̖͓̺̦̺́̀͢ Which reads (without the diacritics) as 'To invoke the hive mind representing chaos.' The first diacritic is a macron over the i in "find". In English, this modifies a vowel to be "long". The second diacritic is the normal acute accent for the e in résumé, to make it an é which does belong in résumé . However, the third diacritic he uses is an umlaut on the u making it into ü, which is not part of the word. Ü typically represents the close front rounded vowel /y/, pronounced similar to the <ee> in "See" but with rounded lips. Ü can be found in languages such as German and Turkish ; however, in French ü is not used in this way since the diacritic-less u already represents this sound. German has a word spelt as Resümee , but the meaning is not the same but rather conclusions or abstracts. Cueball then goes all in on the last e which, like the first e, is supposed to have an acute accent. This e has a cedilla (as in ȩ), a ring (as in e̊), three acute accents, and is topped off by a breve (as in ĕ). In total, six diacritics are used on this e alone. Some languages—notably Vietnamese— can use more than one diacritic per letter , but usually only two (for example, ṏ). This is because in Vietnamese diacritics can serve two functions: the aforementioned modifying sound values as well as to indicate tone . Using multiple diacritics in the comic's fashion makes little sense though it is reminiscent of (the aforementioned) Zalgo text . There are also three acute accents over the last period. Diacritics over punctuation is not something that is ever used. So for a word that is supposed to have two diacritics, Cueball uses eight, plus three for the period. In the title text "not my forté" is supposed to mean that it is not one of Randall's strength or talent. However, to obtain this meaning forte should not have an acute diacritic over the e, thus proving Randall's point that it is not his forte to use diacritics. This is a form of hyperforeignism , where people spell loan words or use pronunciations that they believe is more faithful to the language it comes from instead of the "English" one, even though the "English" one is actually more correct. Due to its similarity with other words from French such as café, some people believe that forte is also spelled with a diacritic on the ending E (also note that the word was independently borrowed twice: from French as "a strength" and from Italian as a musical term. Neither usage requires diacritics). The title text may be a reference to the what if? released a week before this comic, Fire from moonlight , in which note 9 reads, "My résumé says étendue is my forté" (with the same error on "forte"). It is possible that noticing his mistake was the inspiration for this comic. Also étendue can be written without the accent as etendue and the meaning is only written on this page in the Wiktionary. It means property of the light in an optical system which makes sense in the context of the note. However, it means something different in French where it either refers to size or range as a noun or as a verb is the past participle of étendre meaning stretch or spread. The most correct way of writing the sentence he tried to write would only have involved the accent on résumé: "My résumé says etendue is my forte." Thus again making it clear that Randall has it right when he writes: "Using diacritics correctly is not my forté." If there actually has been someone who corrected Randall's mistake in the what if?, then there could be an extra pun hidden in the title. Those who criticized Randall's use of accents, would thus become dia critics ! Comic 1209: Encoding also references an absurd use of diacritics, and later a possible movie called Combining Diacritical Marks was mentioned in 1857: Emoji Movie , a direct reference to this comic. [Cueball sitting in front of his lap top typing. The text above him is the one he is typing. The last word résumé has too many diacritics. The u has an umlaut (as in ü) and the last é has no less than six diacritics; a cedilla below (as in ȩ), a ring above (as in e̊ ), then three acute accents above the ring (as in é), and finally they are topped off by a breve (as in ĕ). In addition, find is spelled fīnd with a macron over the i . Also, the last full stop has three accents "´" above it:] Cueball (typing): Attached please fīnd my résümȩ̊́́́̆.́́́ [Caption below the panel:] I usually leave out diacritics when I type, so I make up for it by occasionally adding a whole bunch at once.

Famous Duos

Famous Duos

https://www.xkcd.com/1648

https://www.explainxkcd.com/wiki/index.php/1648:_Famous_Duos

[Caption above the panel:] Famous Duos in a nearby parallel universe [A list with 24 duos with a gray “and" between the two names (in one case it is a “met") and three times there is a gray word before (once) or after (twice) the names. The list is centered with the “and" in the middle disregarding the length of the names on each side:] Thelma and Hobbes When Harry met Bullwinkle Batman and Louise Antony and Robin Romeo and Butthead Bonnie and Ted 's excellent adventure Pinky and Clyde Simon and Goliath Beauty and Luigi Beavis and the Beast Rocky and Delilah Abbot and Cleopatra Dr. Jekyll and Ashley Olsen Samson and Pumbaa Butch Cassidy and Mr. Hyde Bill and Sally 's Bogus Journey David and Costello Sherlock Holmes and Silent Bob Jay and Dr. Watson Anna and the Brain Calvin and the King Timon and Garfunkel Mary-Kate and the Sundance Kid Mario and Juliet Ranking (on 2016-02-28) of famous Duos Rank Duo Index 2 Batman and Robin 3 8 Holmes and Watson 18 11 Simon and Garfunkel 8 22 Thelma and Louise 1 23 Pinky and The Brain 7 24 Hall and Oates 26 Title text 31 Butch Cassidy and the Sundance Kid 15 35 Calvin and Hobbes 21 41 Jay and Silent Bob 19 46 Dr. Jekyll and Mr. Hyde 13 71 Abbott and Costello 12 79 Beauty and the Beast 9 85 Antony and Cleopatra 4 99 Beavis and Butt-head 10 106 Mary-Kate and Ashley Olsen 23 110 Romeo and Juliet 5 206 Rocky and Bullwinkle 11 N/A When Harry Met Sally... 2 N/A Samson and Delilah 14 N/A Bill & Ted 16 N/A David and Goliath 17 N/A Anna and the King 20 N/A Timon and Pumbaa 22 N/A Mario and Luigi 24 N/A Siskel and Ebert 25 Title text

In popular culture (the term is loosely used in this case) there are many famous duos , such as Calvin & Hobbes (six-year-old boy and his toy tiger, from the cartoon strip with the same name) or David & Goliath (famous past King of Israel and giant, Biblical characters from the Book of Samuel in the Old Testament ). (See the trivia section regarding an on-line list of duos). In this table, Randall describes a fictional parallel universe where the same names are used in different combinations — instead of Calvin, it is now Thelma (from the movie Thelma & Louise ) who is paired up with Hobbes, and Calvin is instead paired off with the King, from Anna and the King . In all cases the one mentioned first on the list is also mentioned first in our universe, so it is always of the form Calvin and the King, never Calvin and Anna. There are 24 duos, and all 48 partners are mentioned (they go through four cycles ). (In the title text of 1644: Stargazing from the week before this comic, there is an indirect reference to parallel universes/ multiverse ). The humor of this comic comes from the ridiculousness of the pairings, and the reader's imagination of the stories that are created with the pairs. See the whole list of real duos as well as the list of alternative duos below, with more detailed explanations. In the title text, alternative movie Romeo and Butt-Head is mentioned, the fifth entry on the list. This is a combination of the famous Shakespeare play Romeo and Juliet and Beavis and Butt-Head . Romeo and Juliet has been filmed many times; most recently in Romeo + Juliet from 1996 with Leonardo DiCaprio and Claire Danes in the leading roles. Butt-Head is the less stupid one (of the very stupid duo) from the animated TV series Beavis and Butt-Head (and a film ). As Romeo and Juliet is one of the best known love stories and Butt-Head is one of the most disgusting teens ever depicted on the big screen (only overtaken by Beavis ), the combination could create disturbing pictures in people's heads (especially in the heads of anyone who may identify themselves with Juliet). In the alternative universe, when this movie was released, it got the best possible review of two thumbs up from the critics Siskel and Oates . Gene Siskel was paired with Roger Ebert , when they reviewed movies as the famous duo Siskel and Ebert . They were widely known for the "thumbs up/thumbs down" review summaries, with their best combined review being Two Thumbs Up , one from each of them. Coincidentally, or perhaps not, they actually gave Beavis & Butthead Do America Two Thumbs Up . In the alternative universe Siskel and his partner gives the film a (surprising) two thumbs up, but Ebert has been replaced with Oates. This is a reference to John Oates of Hall & Oates , a famous American musical duo from Philadelphia. There also exists a comedy duo named Garfunkel and Oates , formed by Riki Lindhome and Kate Micucci, who chose the "Garfunkel and Oates" name by combining the second names from both Hall & Oates and Simon and Garfunkel (the latter duo is mentioned in the main comic). Although this exact combo would not be possible in the xkcd version, as the "real universe" combo takes the second names from two duos rather than the first name from one and the second name from another (as in this comic), there may definitely be a deliberate reference to this group as well which has taken the parallel universe idea into our universe. [Caption above the panel:] Famous Duos in a nearby parallel universe [A list with 24 duos with a gray “and" between the two names (in one case it is a “met") and three times there is a gray word before (once) or after (twice) the names. The list is centered with the “and" in the middle disregarding the length of the names on each side:] Thelma and Hobbes When Harry met Bullwinkle Batman and Louise Antony and Robin Romeo and Butthead Bonnie and Ted 's excellent adventure Pinky and Clyde Simon and Goliath Beauty and Luigi Beavis and the Beast Rocky and Delilah Abbot and Cleopatra Dr. Jekyll and Ashley Olsen Samson and Pumbaa Butch Cassidy and Mr. Hyde Bill and Sally 's Bogus Journey David and Costello Sherlock Holmes and Silent Bob Jay and Dr. Watson Anna and the Brain Calvin and the King Timon and Garfunkel Mary-Kate and the Sundance Kid Mario and Juliet Ranking (on 2016-02-28) of famous Duos Rank Duo Index 2 Batman and Robin 3 8 Holmes and Watson 18 11 Simon and Garfunkel 8 22 Thelma and Louise 1 23 Pinky and The Brain 7 24 Hall and Oates 26 Title text 31 Butch Cassidy and the Sundance Kid 15 35 Calvin and Hobbes 21 41 Jay and Silent Bob 19 46 Dr. Jekyll and Mr. Hyde 13 71 Abbott and Costello 12 79 Beauty and the Beast 9 85 Antony and Cleopatra 4 99 Beavis and Butt-head 10 106 Mary-Kate and Ashley Olsen 23 110 Romeo and Juliet 5 206 Rocky and Bullwinkle 11 N/A When Harry Met Sally... 2 N/A Samson and Delilah 14 N/A Bill & Ted 16 N/A David and Goliath 17 N/A Anna and the King 20 N/A Timon and Pumbaa 22 N/A Mario and Luigi 24 N/A Siskel and Ebert 25 Title text

Pipelines

Pipelines

https://www.xkcd.com/1649

https://www.explainxkcd.com/wiki/index.php/1649:_Pipelines

[Caption above the first main panel, to the left of a smaller panel to the right:] The size of the US’s Pipelines if each fluid produced or consumed in the US has to be carried by a single pipe Assuming they all flowed at the same speed of about 4 m / s Note: Many pipelines would overlap (eg. soda/corn syrup) [There is a small panel to the right showing three gray pipes of different sizes leading out over a large hole in the ground. Only a part of the hole can be seen at the bottom left part of the panel, but it curves around indicating it is a large circular hole. The pipes are supported by small legs beneath them and from the end of all three thick liquids are squirting out and down into the hole. The first pipe is by far the largest; the liquid from it is white, but not as white as the background. The second pipe is by far the smallest squirting dark red liquid and the final rightmost pipe is in between and squirts our light brown liquid. Each pipe is labeled. The label on the smallest cannot be read properly, but from the info gained in the next panel it can be inferred for certain what it says (and this is indicated here below):] [Large pipe (white)]: Mayo [Small pipe (dark red)]: Nail polish [Medium pipe (light brown)]: Maple syrup [Below is a large panel with a caption at the top. And below this there are twenty circles in different sizes and with different color (or even texture). Each circle is labeled, for the five smallest the label is outside, in one case with an arrow indicating where the label belongs. The rest has the label inside. The text is in black except for four of those with text inside, but with red of black color. Here the text is white. The labels are indicated by color and size, going roughly from top left in reading order based on the position and size of circles not of position of the text:] Actual size (When viewed on a typical computer screen) [Medium green blue and white spiral]: Toothpaste [Tiny dark red]: Nail polish [Big light blue with white specks]: Windshield washer fluid [Very tiny purple]: Silly putty [Medium light green]: Shampoo [Large dark yellow]: Honey [Very small blood red]: Donated blood [Tiny black]: Vanilla [Big red]: Ketchup [Medium dark red with chunks of in different green and lighter red colors]: Salsa [Small white]: Sunscreen [Very small light green]: Personal lubricant [Very tiny gray]: LCD liquid [Medium off-white]: Mayo [Very small black]: Printer ink [Small light brown]: Maple syrup [Small light green]: Conditioner [Medium yellow]: Mustard [Large light green]: Liquid soap [Big olive green]: Olive oil [The panel just described is indicated to fit into a small rectangle at the top left of the next panel below. There are four lines ending at the four corners of this small rectangle, two of these are going to the two bottom corners and the other two ends on the lower part of the panel just above the small rectangle. They are indicated to go under the panel and would hit the two top corners if extrapolated. The 11 largest circles are clearly seen, but most of the other circles can also be noted. The colors are the same but any features in the original circles as well as the labels are gone. The part of the black top frame of the next panel below is faded out to gray in between the section cut off by the two lines going to the bottom corners of the panel above. This rectangle indicated the increasing size compared to the first panel above.] [Apart from the insert mentioned above, the second panel follows the same layout, but with 22 circles with even larger range of sizes. The panel is more than twice as long as the first panel. Blondie is drawn at the top of the panel just left of the middle. Her hair is close to the top, just below the line going to the right corner above. There are two medium-sized and five smaller circles to her left and one small close to her head and one huge circle to her right. Her feet are less than a third down this panel standing on top of the next row of circles. In the bottom half of the panel there is a giant circle which almost touches the left side of the panel. There are smaller circles above it and down along the right side. One last circle is to the left almost at the bottom. At the very bottom is a slightly curving line to indicate a much much larger blue circle that only graces the panel (no. 23). There is a small green fish in this water to the left of the label. Below the labels are again listed as above. One label has a foot note. But it is written directly beneath the circle in which it is referenced. So it will be written together with the label on the next line. There is also one case with an arrow used to indicate where the label belongs.] [Medium dark gray]: Coffee [Very tiny gray]: Peanut butter [Very small gray with black specks]: Ice cream [Very small yellow with white specks]: Cheese [Large brown with white fizzing]: Soda [Tiny White]: Acetone [Tiny gray]: Liquor [Huge dark yellow]: Gasoline [Tiny White with blue and orange specks]: Yogurt [Big white]: Milk (cow) [Large light blue]: Bottled water [Small white]: Sugar [Large light gray with white specks]: Saliva [Very small light yellow]: Wine [Very small orange]: HFCS [Very tiny white]: Milk (human) [Gigantic dark gray]: Petroleum [Medium dark red with black texture]: Meat (mostly solid) [Small white]: Glass* *Solid at room temperature [Medium light brown]: Beer [Small gray brown]: Tea [Large gray]: Cement [Gracing bottom of panel light blue, with a fish inside]: Public water

This comic follows a similar idea to the what if? " Niagara Straw " from three days before this comic's release, where the entire water flow over Niagara Falls is imagined to be funneled through a straw (i.e. 7 mm diameter), with disastrous results. In this comic Randall imagines what size pipes are necessary to carry US domestic production/consumption of various fluids if the flow rate were fixed at 4 meters per second. Randall notes that "many pipes would overlap", owing to the fact that consumption of one item as corn syrup would be due to the production of one of the others, in this case soda pop (another example, than the previous one which is actually mentioned in the comic, could be gasoline which is produced from petroleum ). The top panel is in actual size (something Randall often jokes about, like in the very next released what if? " Eat the Sun ", where he shows part of the sun in actual size in the 2nd picture, but in this comic he actually means it). This means that if you look at the image in actual size (or measure lengths in the full size image) then the measured diameter is the diameter Randall has calculated the pipe should be, based on his data for the consumption of these substances. In the second panel the pipes are too big for his drawing. To indicate the scale he has both inserted a woman ( Blondie ) and the top panel has been shrunk down to indicate how much larger the bottom panel is (this is similar to the link between the panels in 980: Money ). Using the size of the top panel and the smaller insert, it can be found that the scale is 20:1. The woman is 9 cm tall in the image, which makes her 180 cm — 5 feet 11 inches — in "real life". The pipe next to her for gasoline would have a diameter of 2.2 m. Since the caption at the top mentions both fluid produced and consumed in the US it becomes very difficult to find out which number Randall uses. For instance the consumption of wine in the US and the production of wine in the US is not necessarily the same as wine is both imported and exported. Should there then be two pipes? Unlike similar comics (like Money mentioned above) there are no references for where Randall has the data for this comic. As usual with xkcd, the absurdity — and improbability — of routing the entirety of each fluid through a single pipe at any point is the source of humor. Randall appears to assume that all of the fluids would flow at a similar speed to typical water mains (4 meters per second). This is, of course, unrealistic, given the wide range of pipe size and fluid viscosity. Running water through a pipe of that size would be trivial (such speeds are typical), but forcing a material like Silly Putty through a tube that tiny at similar speeds would be implausible. And, as the comic points out, some of the materials are effectively solids at room temperature. Many examples are just plain zany (e.g. saliva may be a reference to another what if? " Saliva Pool "). Nonetheless, the table gives a good visual representation of the comparative usage rates. Note that at the bottom of the last panel there is a much larger pipe for the tap water used by the public. This should, perhaps, be unsurprising, as water is used a far higher rate than any other substance that we produce or transport. All substances are listed below in the table . The title text refers to a possible future based on the idea of this comic in which all the pipes with the above-mentioned fluids will actually lead into the same hole as shown in the top right panel. This hole will then be the bowl of a giant blender that mixes all these substances together to a smoothie . The future people will then just come up to this blender and get a bucket full of this mix each day. In reality, this would be an impractical method of getting all of the fluids. Setting the logistical considerations of such a setup aside, this would mean that ketchup and salsa, both intended for human consumption, would be mixed with fluids which are harmful to humans, such as windshield wiper fluid. Note: "Soup" has been left out, and it might have been expected in this comic due to the similarity to this system with Beret Guy 's use of a "soup outlet" as an entrepreneur in 1293: Job Interview . It is probably a larger pipeline than salsa and possibly even ketchup. However, there are many different varieties of soups, and most soup is probably not bought finished, both very good reasons to not include it in the chart. But still the idea of having a soup outlet is very similar to this comic. [Caption above the first main panel, to the left of a smaller panel to the right:] The size of the US’s Pipelines if each fluid produced or consumed in the US has to be carried by a single pipe Assuming they all flowed at the same speed of about 4 m / s Note: Many pipelines would overlap (eg. soda/corn syrup) [There is a small panel to the right showing three gray pipes of different sizes leading out over a large hole in the ground. Only a part of the hole can be seen at the bottom left part of the panel, but it curves around indicating it is a large circular hole. The pipes are supported by small legs beneath them and from the end of all three thick liquids are squirting out and down into the hole. The first pipe is by far the largest; the liquid from it is white, but not as white as the background. The second pipe is by far the smallest squirting dark red liquid and the final rightmost pipe is in between and squirts our light brown liquid. Each pipe is labeled. The label on the smallest cannot be read properly, but from the info gained in the next panel it can be inferred for certain what it says (and this is indicated here below):] [Large pipe (white)]: Mayo [Small pipe (dark red)]: Nail polish [Medium pipe (light brown)]: Maple syrup [Below is a large panel with a caption at the top. And below this there are twenty circles in different sizes and with different color (or even texture). Each circle is labeled, for the five smallest the label is outside, in one case with an arrow indicating where the label belongs. The rest has the label inside. The text is in black except for four of those with text inside, but with red of black color. Here the text is white. The labels are indicated by color and size, going roughly from top left in reading order based on the position and size of circles not of position of the text:] Actual size (When viewed on a typical computer screen) [Medium green blue and white spiral]: Toothpaste [Tiny dark red]: Nail polish [Big light blue with white specks]: Windshield washer fluid [Very tiny purple]: Silly putty [Medium light green]: Shampoo [Large dark yellow]: Honey [Very small blood red]: Donated blood [Tiny black]: Vanilla [Big red]: Ketchup [Medium dark red with chunks of in different green and lighter red colors]: Salsa [Small white]: Sunscreen [Very small light green]: Personal lubricant [Very tiny gray]: LCD liquid [Medium off-white]: Mayo [Very small black]: Printer ink [Small light brown]: Maple syrup [Small light green]: Conditioner [Medium yellow]: Mustard [Large light green]: Liquid soap [Big olive green]: Olive oil [The panel just described is indicated to fit into a small rectangle at the top left of the next panel below. There are four lines ending at the four corners of this small rectangle, two of these are going to the two bottom corners and the other two ends on the lower part of the panel just above the small rectangle. They are indicated to go under the panel and would hit the two top corners if extrapolated. The 11 largest circles are clearly seen, but most of the other circles can also be noted. The colors are the same but any features in the original circles as well as the labels are gone. The part of the black top frame of the next panel below is faded out to gray in between the section cut off by the two lines going to the bottom corners of the panel above. This rectangle indicated the increasing size compared to the first panel above.] [Apart from the insert mentioned above, the second panel follows the same layout, but with 22 circles with even larger range of sizes. The panel is more than twice as long as the first panel. Blondie is drawn at the top of the panel just left of the middle. Her hair is close to the top, just below the line going to the right corner above. There are two medium-sized and five smaller circles to her left and one small close to her head and one huge circle to her right. Her feet are less than a third down this panel standing on top of the next row of circles. In the bottom half of the panel there is a giant circle which almost touches the left side of the panel. There are smaller circles above it and down along the right side. One last circle is to the left almost at the bottom. At the very bottom is a slightly curving line to indicate a much much larger blue circle that only graces the panel (no. 23). There is a small green fish in this water to the left of the label. Below the labels are again listed as above. One label has a foot note. But it is written directly beneath the circle in which it is referenced. So it will be written together with the label on the next line. There is also one case with an arrow used to indicate where the label belongs.] [Medium dark gray]: Coffee [Very tiny gray]: Peanut butter [Very small gray with black specks]: Ice cream [Very small yellow with white specks]: Cheese [Large brown with white fizzing]: Soda [Tiny White]: Acetone [Tiny gray]: Liquor [Huge dark yellow]: Gasoline [Tiny White with blue and orange specks]: Yogurt [Big white]: Milk (cow) [Large light blue]: Bottled water [Small white]: Sugar [Large light gray with white specks]: Saliva [Very small light yellow]: Wine [Very small orange]: HFCS [Very tiny white]: Milk (human) [Gigantic dark gray]: Petroleum [Medium dark red with black texture]: Meat (mostly solid) [Small white]: Glass* *Solid at room temperature [Medium light brown]: Beer [Small gray brown]: Tea [Large gray]: Cement [Gracing bottom of panel light blue, with a fish inside]: Public water

Baby

Baby

https://www.xkcd.com/1650

https://www.explainxkcd.com/wiki/index.php/1650:_Baby

[Cueball is standing in front of a family consisting a Cueball-like guy holding a newborn baby, with spiky hair, in a blanket and Megan. Cueball is thinking lots of thoughts about what to say to the couple upon seeing their baby for the first time. There is thus a huge thinking bubble in the top of the panel above the characters. Everything in this bubble has been crossed out like taking a pencil and drawing lines on top of the text, but it can still be read. After using all this time thinking, Cueball finally decides what to say, only to immediately regret this as can be seen in a small thought bubble below his spoken line, which is between the huge and the small bubble.] Cueball (thoughts that are crossed out): Wow, it's getting so big! Unlike most babies, which stay the same size forever. Hi! I'm talking to a baby! What brand is it? Wow, definitely much smaller than a regular person! You sure did make that. ★★★★☆ Great baby. It doesn't really look like you since you're not a baby. So do they learn words one at a time alphabetically or can you pick the order or what? I hope it does a good job. Cueball: Wow, that's a really cool baby! Cueball (thinking): Dammit. [Caption below the panel:] I can never figure out what to say about babies.

Cueball (possibly representing Randall ) is uncomfortable about talking with couples who present their baby to him (here represented by Megan and another Cueball-like guy holding a baby in a blanket). Because he never knows what to say, he has many strange thoughts and/or reasonable questions, that shouldn't be mentioned in front of happy parents showing off their precious baby for the first time. See the table below for his thoughts. Cueball's thoughts of what he didn't say includes the awkward You sure did make that , the plain strange What brand is it? , and interesting musing about science, which has nothing to do with this baby, So do they learn words... , and even rating someone's baby: ★★★★☆ Great baby ! Some of the thoughts are quite true, like It doesn't really look like you since you're not a baby. In the end he manages to make a comment about how cool the baby is, and immediately regrets this, as he just realized he has squandered the chance to say something meaningful and instead has come out with something quite inane. In the title text he continues his thoughts again, going in the scientific direction with a question regarding how a child grows. Does it get tall first and then put on weight? (i.e. widen). This is a valid question which has no general answer. (See more in the table below). But he is not serious, as he also wonders if the child will reach full width before getting taller. Randall was 31 at the time of the release of this comic. As far as this page and Wikipedia informs, at the time of writing, he has no children, although he is married. However, given his age, it is highly likely that many of his friends are having babies during these years, so he will probably often get into the depicted situation. Therefore, it is highly likely that the comic is based on his own experience, and that it is indeed Randall depicted as the thinking Cueball. Having problems with small talk is a recurring theme in xkcd (see 222: Small Talk ), even something as simple as talking about the weather can be a problem (see 1324: Weather ). This comic is the third in less than a month were Cueball has issues with this; the first two were 1640: Super Bowl Context and 1643: Degrees . There has previously been a "plural" version of this comic called 441: Babies , here Cueball also manages to say something better left unsaid, even if it was about his own baby. [Cueball is standing in front of a family consisting a Cueball-like guy holding a newborn baby, with spiky hair, in a blanket and Megan. Cueball is thinking lots of thoughts about what to say to the couple upon seeing their baby for the first time. There is thus a huge thinking bubble in the top of the panel above the characters. Everything in this bubble has been crossed out like taking a pencil and drawing lines on top of the text, but it can still be read. After using all this time thinking, Cueball finally decides what to say, only to immediately regret this as can be seen in a small thought bubble below his spoken line, which is between the huge and the small bubble.] Cueball (thoughts that are crossed out): Wow, it's getting so big! Unlike most babies, which stay the same size forever. Hi! I'm talking to a baby! What brand is it? Wow, definitely much smaller than a regular person! You sure did make that. ★★★★☆ Great baby. It doesn't really look like you since you're not a baby. So do they learn words one at a time alphabetically or can you pick the order or what? I hope it does a good job. Cueball: Wow, that's a really cool baby! Cueball (thinking): Dammit. [Caption below the panel:] I can never figure out what to say about babies.

Robotic Garage

Robotic Garage

https://www.xkcd.com/1651

https://www.explainxkcd.com/wiki/index.php/1651:_Robotic_Garage

[Black Hat points left while talking to Cueball inside his small car.] Black Hat: Just pull onto the receiving platform. Cueball: Cool-I've always wanted to try one of these futuristic robotic garages. [Cueball has driven the car onto a platform in front of a stop to the left. He is just walking of the platform towards Black Hat.] [Zoom out reveals a robotic crane arm, that sits on top of the stop from the previous panel, which turns out to be a huge platform for this robot arm. The robotic arm picks up the car with its two fingers and lifts it into the air with a finger on the hood and the other below the car. Black Hat and Cueball look on.] Cueball: Um. [This panel pans over to the center of the robotic arm, to reveal a large bin with a label to the robots left. The robot arm holds the car almost straight up in the air, but over the bin.] Label: Cars [The robotic arm open up to release the car which crashes down into the bin, a sound already emanating from it when the rear end of the car (with one wheel still showing) is still visible.] Car: Crunch Label: Cars [Zoom back to Black Hat and Cueball standing at the end of the empty platform.] Black Hat: We'll dump out the bin when you get back and you can pick out your car from the pile. Cueball: Can you at least make sure it's not on the bottom? Black Hat: Look, robots aren't magic.

In some cities, automated parking systems (aka robotic garages) are used to reduce the amount of space needed to store cars, as opposed to traditional parking buildings. The robotic system eliminates the needs for ramps and circulation/reversing areas. Normally, they work by having the user drive their car onto an elevator and get out, after which the elevator lifts or lowers the car into a compact storage space. Here Cueball drives up to what he believes to be a garage of this type operated by Black Hat . However, instead of an elevator carefully moving it into a storage space, a robotic claw simply picks up the car and dumps it in a bin of cars. This type of parking option will not only break the car, but also make it impossible to take out if the car is at the bottom, hence the cars are stacked . Cueball reacts quite well to this treatment of his car when Black Hat tells him that later they just dump out the bin (full of cars) and he can then pick his own out from the pile. (Maybe he knows Black Hat well enough not to try to argue with him?) This is of course not possible with such heavy objects. [ citation needed ] Cueball continues to be benign about this absurd situation, which becomes even more absurd when he asks if Black Hat could at least make sure his car is not at the bottom (when it is dumped out with all the other cars). But Black Hat falls back on his excuse "Robots aren't magic," implying that such a feat is beyond the realm of possibility. It would, of course, be quite possible to prevent the damage that Cueball fears if they were using a normal automated parking system. In the title text he at least gives Cueball an option: he can borrow an axe, if it is really important for him to get the car out from the pile. Although in this situation, an axe would be a nearly useless tool (which, knowing him, is most likely Black Hat's intent), only allowing Cueball to laboriously hack through any other car that lies in the way on top of his own; and still it would not help much, because if his car is at the bottom, it will be even more destroyed than from just being dumped into the bin to begin with. This is just one of many situations where Black Hat has an evil or just mean/crazy plan in progress. It's for instance not the first time that Black Hat has treated other people's car with great disrespect, although in 562: Parking , the guy with the car had it coming! [Black Hat points left while talking to Cueball inside his small car.] Black Hat: Just pull onto the receiving platform. Cueball: Cool-I've always wanted to try one of these futuristic robotic garages. [Cueball has driven the car onto a platform in front of a stop to the left. He is just walking of the platform towards Black Hat.] [Zoom out reveals a robotic crane arm, that sits on top of the stop from the previous panel, which turns out to be a huge platform for this robot arm. The robotic arm picks up the car with its two fingers and lifts it into the air with a finger on the hood and the other below the car. Black Hat and Cueball look on.] Cueball: Um. [This panel pans over to the center of the robotic arm, to reveal a large bin with a label to the robots left. The robot arm holds the car almost straight up in the air, but over the bin.] Label: Cars [The robotic arm open up to release the car which crashes down into the bin, a sound already emanating from it when the rear end of the car (with one wheel still showing) is still visible.] Car: Crunch Label: Cars [Zoom back to Black Hat and Cueball standing at the end of the empty platform.] Black Hat: We'll dump out the bin when you get back and you can pick out your car from the pile. Cueball: Can you at least make sure it's not on the bottom? Black Hat: Look, robots aren't magic.

Conditionals

Conditionals

https://www.xkcd.com/1652

https://www.explainxkcd.com/wiki/index.php/1652:_Conditionals

[Cueball is shown texting on a phone with a friend. Above him in light gray rectangles with indentations pointing left are the two text messages from his friend, and between them in dark a gray rectangle with an indentation pointing right is Cueball's message.] Friend (text): I'll be in your city tomorrow if you want to hang out. Cueball (text): But where will you be if I don't want to hang out?! Friend (text): You know, I just remembered I'm busy. [Caption below the panel:] Why I try not to be pedantic about conditionals.

This comic is about the many different uses of conditional statements in human languages, such as those marked by the English word "if". The most obvious kind of conditional is a statement about conditions and consequences (i.e. causality ). An expression such as "If A, then B" amounts to asserting that, if A is true, then B is also true is called conditional probability : This kind of simple conditional statement is the most common case, and has been adapted for use in computer programming and formal logic. But consider the following statement: This kind of "bleached conditional" doesn't at all assert that, if the left statement is true, the right one needs to be true. Rather, it's just a way of introducing the right statement (taken as novel) by comparing it with the left one (taken for granted). "As everyone knows, Seattle is always rainy, right? Well, Beijing is smoggy just as often". So conditionals in language are more varied than those of conditionals when used in logic or programming . Another kind of linguistic conditional is as follows: No one would understand this statement as meaning "if you want biscuits, they'll magically pop up in the sideboard". The if-clause ("if you want some") doesn't specify the conditions in which the then-clause ("there are biscuits") is true. Rather, it describes the conditions in which it's relevant . We can paraphrase it as: "If you want biscuits, then you'll be interested in knowing that there are some in the sideboard". If A is true, then it's relevant for us to talk of B. This construction is known to linguists as relevance conditionals , or "biscuit conditionals", due to J.L. Austin's discussion based on the example above. The humor in the comic is based on the difference between simple conditionals and relevance conditionals. Cueball gets a chat message on his phone to a social event: "I'll be in your city tomorrow if you want to hang out." This is an everyday relevance conditional, with a meaning like: "if you want to hang out, then it's relevant for you to know that I'll be in your city tomorrow". However, Cueball interprets it as a simple conditional, just as in formal logic. Under this interpretation, the message amounts to a claim that, if it's true that Cueball wants to hang out, then it's also true his conversation partner will be in his city. Cueball is willfully forcing this interpretation, due to his belief that simple conditionals are the only "proper" ones. That is, he's being a pedant . A pedant is a person who is excessively concerned with formalism, accuracy, and precision. Under this deliberate misreading, if it's true that Cueball wants to hang out, then we automatically know the other person's location. But if Cueball does not want to hang out, we don't know anything about their location; they could be in the city or anywhere else. Since the person is only "guaranteed" to be in the city if Cueball wants to hang out, he asks them where they will be if he doesn't. The other person then makes an excuse to drop their invitation, apparently tiring of his pedantry. Hence in the caption Cueball/ Randall observes that being pedantic with regard to conditionals is likely to make your friends disinclined to hang out with you. So he tries not to be pedantic about it. In the title text, the initiator of the conversation presents another "If A, then B" conditional: "If you're done being pedantic, we should get dinner". In most contexts, this kind of "If you're done being X" utterance marks relevance conditionals. Cueball assumes so, and answers "You did it again!". But the reply is "No, I didn't." Which means that this time they're actually using a simple conditional; because, if Cueball isn't done being a pedant, then they think it's a bad idea to have dinner together. And since Cueball was not finished being pedantic about conditionals, then the last no, would probably also end up being a no to having dinner. The title text (and partly the subject of the comic) is literally a reference to 725: Literally , if you know what I mean. [Cueball is shown texting on a phone with a friend. Above him in light gray rectangles with indentations pointing left are the two text messages from his friend, and between them in dark a gray rectangle with an indentation pointing right is Cueball's message.] Friend (text): I'll be in your city tomorrow if you want to hang out. Cueball (text): But where will you be if I don't want to hang out?! Friend (text): You know, I just remembered I'm busy. [Caption below the panel:] Why I try not to be pedantic about conditionals.

United States Map

United States Map

https://www.xkcd.com/1653

https://www.explainxkcd.com/wiki/index.php/1653:_United_States_Map

[A white map with an outline that closely resembles that of the mainland of the United States of America with gray all around the black border. But on closer inspection most of the states do not look right. The 48 mainland states are all there, however, with their name or abbreviations written on them as a label in gray text. But they have all been shuffled around and then reassembled as a jigsaw puzzle in the same shape as USA. The name labels for most of the states have been rotated, often to follow the new rotation of the state in the map. So some are written upside down or have been rotated 90 degrees clockwise or counter clockwise or even somewhere in between. One state, Michigan, has even been split up in two so there are 49 instead of 48 labels. For the states that have been named only with state abbreviations the full name is written in brackets behind the transcript of the abbreviation. Here below all the states are listed approximately in columns going from the top left and down and then moving right to the next column across the map. Any rotation of the text from normal is noted in brackets behind the name.] Ohio [Upside down] Georgia [Upside down] Michigan [Upside down – but only bottom part] MD [Upside down - Maryland] California [Text not rotated, but state is rotated counter-clockwise] Kansas [Upside down] Pennsylvania [Rotated clockwise] Oklahoma [Rotated clockwise] New Mexico Nebraska [Upside down] South Dakota Colorado [Rotated counter clockwise] Wyoming [Rotated counter clockwise] Utah [Text normal, but state is upside down, i.e. the text is upside down in the state] Alabama MA [Rotated counter clockwise – Massachusetts] Virginia [Rotated counter clockwise] Arizona [Rotated counter clockwise] Washington [Rotated counter clockwise] Montana [Rotated clockwise - but the state is rotated counter clockwise, i.e. the text is upside down in the state] New York Minnesota [Upside down] Texas [Upside down] CT [Rotated clockwise –Connecticut] Missi- ssippi [Rotated clockwise - text split with hyphen] Nevada Idaho [Rotated clockwise] South Carolina [Rotated counter clockwise, by more than 90 degrees, but the state is rotated exactly 90 degrees] Missouri [Upside down] Wisconsin [Upside down] Kentucky [Rotated clockwise] North Dakota [Rotated clockwise] Florida [Rotated counter clockwise, by more than 90 degrees, but the state is rotated exactly 90 degrees] North Carolina [Rotated clockwise] Indiana RI [Label below in the ocean –Rhode Island] Oregon [Rotated clockwise] Iowa Tennessee [Upside down] Illinois Maine [Upside down] NH [New Hampshire] MI (upper) [Rotated 45 degree counter clockwise – Michigan but only upper part] Arkansas NJ [New Jersey] Louisiana [Rotated 45 degree counter clockwise - but the state is rotated exactly 90 degrees] West Virginia [Rotated 45 degree clockwise] DE [Rotated counter clockwise – label to the right in the ocean – Delaware] VT [Upside down –Vermont]

The comic is a map with the (rough) outline of the mainland of the United States of America . At first it looks like the real map, but actually all the states have been shuffled around in it. It seems that Randall took all of the states (minus Alaska and Hawaii , the two states that are not part of this map and are only mentioned in the title text, see below), and then reassembled them in the style of a jigsaw puzzle, with the end result being a map with a similar outline to the original unaltered mainland state map . They can thus be reassembled into the real map as can be seen here (see also the trivia section ). Previously Randall has played with the shapes of the United States in 1079: United Shapes . In that map he did two separate drawings for Michigan with a mitten in the lower part and an eagle in the upper part . Once again in this version he has split Michigan in two, the lower main part, the mitten just labeled Michigan , is on the west coast on part of California's location, but the upper part is located on the east coast over New York's location and has been labeled MI (upper) . So even without Hawaii and Alaska, there are 49 "states" in this map, consisting of 47 states plus the two halves of Michigan. In the table below all 49 states in the map has been listed to indicate where the puzzle pieces have been moved to. It seems at a first glance that the names have been written on the states as they would appear in a normal map, and that they have all then been rotated with the rotation of the states. But this is not the case for all states. For instance it seems like Utah has hardly been moved at all, and with the name written normally this may be intentionally to deceive the readers. Because Utah has been turned upside down, and according to how for instance Texas , clearly turned upside down, has its name written upside down as well, Utah should thus also have been written like that. It seems likely that this could be a trick by Randall, to see if anyone spots that Utah has actually been moved. But it could of course be a mistake, as seems more likely with Montana where the same "error" has occurred, but since this state has been moved far from its real position there would be no sport in doing so (see the trivia section ). Of course there is the possibility that "Utah" was on purpose and Montana by mistake. With 47 of 49 ending up rotated as expected on the map and only two exactly upside down, there can be no doubt that it was on purpose that the names in general have been written according to the states rotation. Note that for instance the state California has been rotated, but in a way so the text is written normally. But due to the direction of the state, it is normal to write the name tilted down along the state, which just coincidentally ends up being rotated normal in the position it has in the comic. California has thus only been pushed down the length of the west border of the US (and thus rotated accordingly) so the top part still overlaps with the bottom part California, but also covers the bottom part of Arizona and New Mexico . Other states that likewise haven't been moved a lot include Maine which has only been rolled left (i.e. turned upside down) to just outside its normal position. Colorado has been moved up a state to where Wyoming usually is, and Wyoming has then just been shifted right, still covering part of its original position. But both have been turned 90 degrees, whichever way would be impossible to say for these rectangular states, but the text, if you dare believe in that, seems to indicate they have been turned counter clockwise. Wisconsin has only been shifted down below its usual position but then turned upside down. The title text mentions how it would be unfair to use a blank version of this shuffled-up map as a quiz for knowledge of U.S. geography (the link is to such a map created by a user of this site); most people recognize states primarily by their relative locations, not their shape (and especially not their shape after being rotated). It also suggests a corresponding mean trick to play if you include Alaska and Hawaii, which are not present in the comic itself, namely to interchange the volcanic island of Hawaii (consisting of 8 main islands and hundreds of smaller ones) with those of the Aleutian Islands , also a chain of volcanic islands (14 large and 55 small) that partly belongs to the US and partly to Russia. The island extends from the Alaska Peninsula . It would thus be possible to even make it difficult to correctly name these last two states, even though it would be obvious to begin with that it must be the two not belonging to the mainland. [A white map with an outline that closely resembles that of the mainland of the United States of America with gray all around the black border. But on closer inspection most of the states do not look right. The 48 mainland states are all there, however, with their name or abbreviations written on them as a label in gray text. But they have all been shuffled around and then reassembled as a jigsaw puzzle in the same shape as USA. The name labels for most of the states have been rotated, often to follow the new rotation of the state in the map. So some are written upside down or have been rotated 90 degrees clockwise or counter clockwise or even somewhere in between. One state, Michigan, has even been split up in two so there are 49 instead of 48 labels. For the states that have been named only with state abbreviations the full name is written in brackets behind the transcript of the abbreviation. Here below all the states are listed approximately in columns going from the top left and down and then moving right to the next column across the map. Any rotation of the text from normal is noted in brackets behind the name.] Ohio [Upside down] Georgia [Upside down] Michigan [Upside down – but only bottom part] MD [Upside down - Maryland] California [Text not rotated, but state is rotated counter-clockwise] Kansas [Upside down] Pennsylvania [Rotated clockwise] Oklahoma [Rotated clockwise] New Mexico Nebraska [Upside down] South Dakota Colorado [Rotated counter clockwise] Wyoming [Rotated counter clockwise] Utah [Text normal, but state is upside down, i.e. the text is upside down in the state] Alabama MA [Rotated counter clockwise – Massachusetts] Virginia [Rotated counter clockwise] Arizona [Rotated counter clockwise] Washington [Rotated counter clockwise] Montana [Rotated clockwise - but the state is rotated counter clockwise, i.e. the text is upside down in the state] New York Minnesota [Upside down] Texas [Upside down] CT [Rotated clockwise –Connecticut] Missi- ssippi [Rotated clockwise - text split with hyphen] Nevada Idaho [Rotated clockwise] South Carolina [Rotated counter clockwise, by more than 90 degrees, but the state is rotated exactly 90 degrees] Missouri [Upside down] Wisconsin [Upside down] Kentucky [Rotated clockwise] North Dakota [Rotated clockwise] Florida [Rotated counter clockwise, by more than 90 degrees, but the state is rotated exactly 90 degrees] North Carolina [Rotated clockwise] Indiana RI [Label below in the ocean –Rhode Island] Oregon [Rotated clockwise] Iowa Tennessee [Upside down] Illinois Maine [Upside down] NH [New Hampshire] MI (upper) [Rotated 45 degree counter clockwise – Michigan but only upper part] Arkansas NJ [New Jersey] Louisiana [Rotated 45 degree counter clockwise - but the state is rotated exactly 90 degrees] West Virginia [Rotated 45 degree clockwise] DE [Rotated counter clockwise – label to the right in the ocean – Delaware] VT [Upside down –Vermont]

Universal Install Script

Universal Install Script

https://www.xkcd.com/1654

https://www.explainxkcd.com/wiki/index.php/1654:_Universal_Install_Script

[In the panel is a shell script which, unusual for xkcd, uses only lower case. At the top the title of the program is inlaid in the frame, which has been broken here.] Install.sh #!/bin/bash pip install "$1" & easy_install "$1" & brew install "$1" & npm install "$1" & yum install "$1" & dnf install "$1" & docker run "$1" & pkg install "$1" & apt-get install "$1" & sudo apt-get install "$1" & steamcmd +app_update "$1" validate & git clone https://github.com/"$1"/"$1" & cd "$1";./configure;make;make install & curl "$1" | bash &

Most users of computers today are used to simple, easy installation of programs. You just download a .exe or a .pkg , double click it, and do what it says. Sometimes you don't even have to install anything at all, and it runs without any installation. However, when things are more "homebrew", for example downloading source code, things are more complicated. Under Unix-like systems, which this universal install script is designed for, you may have to work with "build environments" and " makefiles ", and command line tools. To make this process simpler, there exist repositories of programs which host either packages of source code and the things needed to build it or the pre-built programs. When you download the package, it automatically does most of the work of building the code into something executable if necessary and then installing it. However, there are many such repositories, such as " pip " and "brew", among others listed in the comic. If you only know the name of a program or package, you may not know in which repository(ies) it resides. The install.sh file provided in the comic is a shell script , which attempts to fix this problem by acting as a "universal install script" that contains a lot of common install commands used in various Unix-like systems. This script in particular is interpreted by the Bourne Again Shell (Bash), which is denoted by the #!/bin/bash in the first line. In between each of the install commands in the script is the & character, which in POSIX -compatible shells (including Bash , a popular shell scripting language) means it should continue to run the next command without waiting for the first command to finish, also known as "running in the background". This has the effect of running all the install commands simultaneously; all output and error text provided by them will be mixed together as they are all displaying on the screen around the same time. The script accepts the name of a program or package as an argument when you run it. This value is then referenced as "$1" (argument number 1). Everywhere the script says "$1", it substitutes in the name of the package you gave it. The end result is the name being tried against a large number of software repositories and package managers, and hopefully, at least one of them will be appropriate and the program will be successfully installed. Near the end, it even tries copying the source code from an online source and then runs several commands which compile/build the program. All in all, this script would probably work; it runs many standard popular repository programs and package managers, and runs the nearly-universal commands needed to build a program. Most of the commands would simply give an error and exit, but hopefully the correct one will proceed with the install. One of the more subtle jokes in the comic is the inclusion of apt-get and sudo apt-get in the same script. Good unix practice dictates never logging in as root; instead you stay logged in as your normal user, and run system admin accounts via sudo program name . This prevents accidental errors and enables logging of all sensitive commands. A side effect of this, however, is that an administrator may forget to prefix their command with sudo , and re-running it properly the second time. This is a common joke in the Linux community, an example of which can be found at this viral tweet which shows a humorous workaround for the issue. Since Randall's script does not use sudo for any but the apt-get command, there are two possibilities: the script itself was run via the root user or via sudo, in which case the sudo apt-get is not needed, or the script was run as a normal user, in this case the commands may install a local (as opposed to system-wide) version depending on local conditions. For instance npm will install a copy of the package under $HOME/.npm and pip would work as long as the user is working in a virtualenv (which is standard practice for Python developers). Sudo has also been used both by Randall in 149: Sandwich and by Jason Fox to force Randall to let him appear on xkcd with 824: Guest Week: Bill Amend (FoxTrot) . The tool curl downloads files from the network (e.g., the Internet). For example, curl http://xkcd.com/ downloads and displays the xkcd HTML source. The pipe | in the script attaches the output of the command before the pipe to the input of the command after the pipe, thus running whatever commands exist in the web content. Although this "curl|sh" pattern is a common practice for conveniently installing software, it is considered extremely unwise; you are running untrusted code without validation, there may be a MITM who modifies the code you receive, or the remote system could have been hijacked and the code made malicious. Most local package managers (e.g. apt , yum ) offer digitally-signed packages that thwart this problem. You can find many examples of software providers suggesting a curl|sh solution at curlpipesh There appears to be a bug with the & at the end of the "git clone" line; since a git repository typically contains program source code, not executables, it may have been intended to retrieve the source code with git and then compile and install the program in the next line. In this case, the single & should be replaced with &&, an operator that will run the second command only if the first one has completed successfully. This plays into a second bug on the "configure" line, where the placement of the & means that only the "make install" command will be run asynchronously after the "configure" and "make" steps have finished in sequence (though this would likely fail due to a lack for write permissions unless it was run with sudo). To make success as likely as possible, the two lines should be like this or script should be executed twice: Since all commands are running in the background, any command that requires user input will stop and wait until brought to the foreground. A common request would be for a database password, or if it is allowed to restart services for the installation. This could lead to packages being only partly installed or configured. (See more about using "yes" below.) The title text mentions the possibility that the same program may be in multiple repositories, so in this case, the script will download and install several versions, or it may fail on a number of repositories, in which case usually nothing bad happens. Since all the commands come from different operating systems, versions, or distributions, it is not very likely that more than one will work (with the exception of pip/easy_install and the two forms of apt-get) or even exist on the same system. It mentions that adding a way of automatically saying "yes" to questions asked during the different repository-fetching programs' running, by making them read input from another program that writes a (nearly) endless stream of "y"s, could simplify things further. This would not work for any curses-based menus, or to answer any more complicated questions. Adding 2>/dev/null to a command redirects the second output stream (the "error stream") to the null device driver, which discards all writes to it, meaning errors (the package not existing) will not be sent to the screen. [In the panel is a shell script which, unusual for xkcd, uses only lower case. At the top the title of the program is inlaid in the frame, which has been broken here.] Install.sh #!/bin/bash pip install "$1" & easy_install "$1" & brew install "$1" & npm install "$1" & yum install "$1" & dnf install "$1" & docker run "$1" & pkg install "$1" & apt-get install "$1" & sudo apt-get install "$1" & steamcmd +app_update "$1" validate & git clone https://github.com/"$1"/"$1" & cd "$1";./configure;make;make install & curl "$1" | bash &

Doomsday Clock

Doomsday Clock

https://www.xkcd.com/1655

https://www.explainxkcd.com/wiki/index.php/1655:_Doomsday_Clock

[Above a clock that shows 3 minutes to 12:] Bulletin of the Atomic Scientists Doomsday Clock [Cueball enters the frame from the left and walks up the clock while looking up at it.] Bulletin of the Atomic Scientists Doomsday Clock Cueball: Oh hey, spring forward. [Cueball grabs hold of the hour hand on the clock and adjust it one hour ahead to 3 minutes to 1.] Bulletin of the Atomic Scientists Doomsday Clock [Nuclear apocalypse with one large central mushroom cloud, with a typical ring around the central stem, two other mushroom clouds are behind it left and right as well as three smaller ones near (or even partly under) the horizon. There are also three smaller explosion in the air.]

The Bulletin of the Atomic Scientists is an academic journal which has a recurring feature known as the Doomsday Clock , which shows the Bulletin's judgment on the current state of the world. The idea is that when the clock hits midnight, the world ends (originally conceived as in a nuclear war ), so how close the clock is to midnight is a scale of the world's current state of risk. Its setting as of the publication of this comic was at "three minutes to midnight" (11:57 PM or 23:57). Its current setting is (as of 24th January 2020) at "100 seconds to midnight" (11:58:20 PM or 23:58:20). Daylight saving time (DST) is a feature in many countries where in the summer months, everyone moves their clock forward an hour to artificially postpone sunset and thereby have a longer time of sunlight in the afternoon. The day before this comic came out (Sunday), most of the United States switched from standard time to DST. This makes it the first of several comics about DST that has been released in conjunction with the beginning of DST. Cueball is inside the office of the Bulletin of the Atomic Scientists and comes across the Doomsday Clock, which is apparently an actual clock. Citing a mnemonic , "Spring forward, fall back", referring to which direction to move the hour hand in the season when DST begins or ends, he pushes the hour hand forward one hour, so instead of the world being three minutes from the end of the world, it is now 57 minutes into it, so the final panel simply shows the world erupting in a Dr. Strangelove -esque nuclear apocalypse , with the typical mushroom cloud shape, with a ring around the stem, which is also displayed in the Wikipedia page on nuclear weapons . This is an absurdist joke confusing the Doomsday Clock with an actual clock; the Doomsday Clock is a subjective measurement of risk, not of time, and as such is not subject to Daylight Saving Time. Furthermore, in the comic the Doomsday Clock does not just measure the world's risk but actively controls it; even if the Doomsday Clock were affected by DST, the doomsday scenario notably does not occur until Cueball adjusts the clock. Also Cueball would only ever adjust the clock like this, if he happened to come by just when the real time was 12:57 the day after DST (as it is not clear from an analog clock if it is AM or PM). When he spots the clock showing 11:57 at 12:57 he just thinks someone has forgotten this particular clock, (which happens a lot the day after DST), and he is thus just helpfully adjusting to the new correct DST time. The title text continues on this same theme, with the digital doomsday clock (apparently it has now been replaced by a digital one, maybe Cueball broke the old analog one) being reset by a power outage. Many digital clocks blink 00:00 once per second after a power outage, only stopping when the clock is reset. This is interpreted as the world actually blinking in and out of the Doomsday Clock's midnight, so nuclear explosions thus naturally appear and disappear in sync with the clock. This once more underlines the entire point of this comic, that it makes no sense to have such a clock. Many people, including Randall , also believe that DST also makes little sense today, so maybe this is why the two are connected in this comic. Randall has mocked DST several times , so this could be yet another attempt to have some fun at its expense. Another doomsday clock was used in 1159: Countdown , although here it was for a supervolcano eruption. A nuclear bomb, not yet exploded but with a short countdown, was the facilitator of the joke in 1168: tar . Within a year before this comics release Randall made several other comics about nuclear weapons, most recently January of 2016 with 1626: Judgment Day , and before that these two in 2015, 1539: Planning and 1520: Degree-Off . Nuclear weapons are also mentioned twice in Thing Explainer , specifically they are explained in the explanation for Machine for burning cities about thermonuclear bombs , but they are also mentioned in Boat that goes under the sea about a submarine that caries nukes. All three comics and both explanations in the book, does like this comic, comment on how crazy it is that we have created enough firepower to obliterate Earth several times (or at least scourge it for any human life). After these there was some time without nuclear bombs, but a new mushroom cloud was displayed in 1736: Manhattan Project , the week after such weapons invention was listed at 1950 CE. [Above a clock that shows 3 minutes to 12:] Bulletin of the Atomic Scientists Doomsday Clock [Cueball enters the frame from the left and walks up the clock while looking up at it.] Bulletin of the Atomic Scientists Doomsday Clock Cueball: Oh hey, spring forward. [Cueball grabs hold of the hour hand on the clock and adjust it one hour ahead to 3 minutes to 1.] Bulletin of the Atomic Scientists Doomsday Clock [Nuclear apocalypse with one large central mushroom cloud, with a typical ring around the central stem, two other mushroom clouds are behind it left and right as well as three smaller ones near (or even partly under) the horizon. There are also three smaller explosion in the air.]

It Begins

It Begins

https://www.xkcd.com/1656

https://www.explainxkcd.com/wiki/index.php/1656:_It_Begins

[A post in Megan's news feed on some social network platform is shown. Megan's head-shot profile image is shown in a frame to the left with two lines of unreadable text below. Her comment is to the right of this image, also with unreadable text above both in a black and gray font. This comment is above the news story she has posted below in a frame. Inside the frame there is another smaller frame to the left with a picture of Cueball on a beach, holding his hand out towards a seagull that flies away with his phone. Two other seagulls can be seen in the air above the sea. There is a small heading at the top, and then a larger one below this. Below that again there is two lines of unreadable text:] It Begins Local News Seagull Steals Phone, Drops it in Ocean [Caption below the panel:] Protip: To make your day more dramatic, post a random minor news story with the comment "it begins."

This comic encourages the reader to post random news stories on the Internet, under the line "It begins." This creates a sense of impending doom, as well as making people wonder what, exactly, is being referred to. This could also encourage people to theorize about what, exactly, is beginning. It could also just confuse the intended audience, as they try to comprehend what the author is saying. This could in the worst case speedily lead to several people making repost of such a non-news story that would not have gotten any attention otherwise. This may lead to speculation, and other curious theories, going out the tangent it could create fear or mass hysteria. Some stories that might benefit especially from this are those relating to machine autonomy, animal attacks, disease, and so forth. This would call to mind various popular culture and/or scientific hypothetical scenarios. Perhaps the comic's choice of article refers to Alfred Hitchcock 's thriller The Birds , in which birds (especially seagulls ) begin attacking humans for no apparent reason, or the broader idea of an animal revolution, or just that even animals get sick of us always looking at our smart phones. The title text instructs readers to try the line " Yikes " instead. The idea is the same but would give a completely different response. Other comics which advocate using catch-all phrases as standard responses for any comment: [A post in Megan's news feed on some social network platform is shown. Megan's head-shot profile image is shown in a frame to the left with two lines of unreadable text below. Her comment is to the right of this image, also with unreadable text above both in a black and gray font. This comment is above the news story she has posted below in a frame. Inside the frame there is another smaller frame to the left with a picture of Cueball on a beach, holding his hand out towards a seagull that flies away with his phone. Two other seagulls can be seen in the air above the sea. There is a small heading at the top, and then a larger one below this. Below that again there is two lines of unreadable text:] It Begins Local News Seagull Steals Phone, Drops it in Ocean [Caption below the panel:] Protip: To make your day more dramatic, post a random minor news story with the comment "it begins."

Insanity

Insanity

https://www.xkcd.com/1657

https://www.explainxkcd.com/wiki/index.php/1657:_Insanity

[Cueball is walking towards the right of the panel with White Hat walking behind him holding a finger up as to make a point.] White Hat: They say the definition of insanity is doing the same thing over and over and expecting different results. Cueball: You've been quoting that cliché for years. Has it convinced anyone to change their mind yet?

In this comic White Hat quotes a famous "definition of insanity " (usually attributed to Albert Einstein , but may be a loose paraphrasing from Narcotics Anonymous ) adapted by Rita Mae Brown or others historically. Cueball's answer applies the quote to the action of quoting that quote. White Hat seems to have quoted that quote quite a few times already, expecting people to change their behavior which hasn't happened so far. So according to that definition of insanity, it is insane to keep quoting the definition of insanity, expecting people to change their behavior because of that. Merriam-Webster defines "insane" as "mentally disabled." The title text implies that Randall would be "insane" according to the quote he used in the comic because he has repeatedly searched for a definition of insanity that matches the one quotes in the comic and of course always gets a negative result, since this is a personal quote not a definition. Besides searching in lots of dictionaries , he also looked in the DSM-4 (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition). The DSM-5 has been available since May 18, 2013 and he plans to look into it, expecting different results. Since he won't find it, he is from the quote insane, but of course since this turns out to not be the definition of insanity then he might not be anyway. This comic follows a pattern similar to 1339: When You Assume . For a different view on the topic of repetition in experimentation, see 242: The Difference . [Cueball is walking towards the right of the panel with White Hat walking behind him holding a finger up as to make a point.] White Hat: They say the definition of insanity is doing the same thing over and over and expecting different results. Cueball: You've been quoting that cliché for years. Has it convinced anyone to change their mind yet?

Estimating Time

Estimating Time

https://www.xkcd.com/1658

https://www.explainxkcd.com/wiki/index.php/1658:_Estimating_Time

[Ponytail is sitting back from her a laptop lifting her hands of the keyboard, having presumably just paused work on a project.] Ponytail: Aaaa! I'm so bad at estimating how long projects will take. [Danish walks into the panel towards Ponytail who seems to relax back against the chair.] Danish: Don't panic-there's a simple trick for that: Danish: Take your most realistic estimate and double it. Ponytail: Okay, but- [A frameless panel with only Danish holding a hand up.] Danish: Now double it again. Add five minutes. Danish: Double it a third time. Ponytail (from off panel): Okay... [Danish raises her arms above her head in mock hysteria. Ponytail runs away from her desk screaming.] Danish: 30 seconds have gone by and you've done nothing but double imaginary numbers! You're making no progress and will never finish! Ponytail: Aaaaaa! Danish: Paaaniic! Ponytail: Aaaaaaa!

Estimation is difficult; many people seem to greatly underestimate the amount of time or other resources required. To illustrate how difficult this estimation is Douglas Hofstadter coined Hofstadter's law which is a non-scientific self-referential time-related adage, mentioned in the the title text. It states: It always takes longer than you expect, even when you take into account Hofstadter's Law. Ponytail is working at her computer and becomes frustrated as it seems her project will (again) take much longer than she has estimated. She is annoyed with herself for always failing to make a decent guess. Danish begins to give Ponytail advice on how to estimate the time, starting with the comforting words don’t panic and a common guideline of taking the initial estimate and doubling it. Danish then iterates the law once more and she tells Ponytail to double this again, and then add five minutes. Unless the project to begin with was estimated to somewhat less than an hour, those five minutes will do nothing but confuse Ponytail. But Danish does not stop here, and iterates Hofstadter's law once more. Ponytail still doesn’t get where this goes, saying a hesitant okay to that. It turns out that Danish was not at all trying to help, but just mess with Ponytail, as she now tells her that the only thing she has accomplished by listening to her advice is wasting half a minute doubling imaginary numbers (not to be confused with i, the imaginary number), i.e. even her first estimate is just something she has imagined especially since she states herself how bad she is at those kind of estimates. Finally Danish completes her frustration of Ponytail by saying " Paaaniiic! ", negating the initial advice. The title text is an extra corollary to the law, that states that using the law to estimate anything about the time your project takes is not only wasted time you could have spent working there is a substantial risk that you will conclude that you will never finish, and thus panic instead of just get the job done now. Self-reference is a recurring theme on xkcd and this comic is quite self-referential both in the comic but also referring to other comics especially to 917: Hofstadter . He is perhaps most famous for his book Gödel, Escher, Bach from where the quote is taken (in a section on recursion and self-reference, rather than estimation). This book has been directly referenced in 24: Godel, Escher, Kurt Halsey . [Ponytail is sitting back from her a laptop lifting her hands of the keyboard, having presumably just paused work on a project.] Ponytail: Aaaa! I'm so bad at estimating how long projects will take. [Danish walks into the panel towards Ponytail who seems to relax back against the chair.] Danish: Don't panic-there's a simple trick for that: Danish: Take your most realistic estimate and double it. Ponytail: Okay, but- [A frameless panel with only Danish holding a hand up.] Danish: Now double it again. Add five minutes. Danish: Double it a third time. Ponytail (from off panel): Okay... [Danish raises her arms above her head in mock hysteria. Ponytail runs away from her desk screaming.] Danish: 30 seconds have gone by and you've done nothing but double imaginary numbers! You're making no progress and will never finish! Ponytail: Aaaaaa! Danish: Paaaniic! Ponytail: Aaaaaaa!

Tire Swing

Tire Swing

https://www.xkcd.com/1659

https://www.explainxkcd.com/wiki/index.php/1659:_Tire_Swing

[Science Girl and a girl with long curly hair, are standing under a large leafless tree as Science Girl adjusts a tire swing hanging from the largest of the branches of the tree. The tire hangs so high that the small girls only reach up to just above the center of the tire which has a diameter of more than half the height of the girls.] Science Girl: OK, looks good. [Zoom in on the girls so only the tire swing can be seen, and nothing of the tree. They both look at the tire.] Science Girl: I read that there are these huge dumps everywhere full of millions of old tires that no one knows what to do with. [Same setting but Science Girl looks up at the tree (outside the frame).] Science Girl: We should use one of those next time. Curly haired girl: Yeah. That guy was real mad. Science Girl: I would not want to fight him again.

In this comic, Science Girl and another girl have just completed a tire swing , a common makeshift swing is created by hanging a car tire from a length of rope, typically tied to the branch of a tree as in the comic. The other girl might at first look like she has hair like Megan but not quite as she is revealed upon zoom in to have curly hair. That they are rather small kids can be seen from the size of the tire compared to them. (They could be the same as the girls in the last panel of 1580: Travel Ghost ). In the second panel of this comic Science Girl muses that there are huge tire dumps filled with nothing but old tires that have no use. In the last panel, Science Girl continues that maybe they should use a tire from such a dump next time they make a tire swing. The presumption is that perhaps they used a brand new tire, or a tire from some other source. This is confirmed by the other girl's response (and also by the title text, see below) which makes it clear that the tire they used was in fact stolen from a guy's vehicle. The last reply from Science Girl suggests the victim put up a fight and they had to take the tire by force. So these two small girls actually fought an adult man over his truck and won the fight. Vehicle tires have a limited lifespan. The natural end of their life is when the pattern of raised treads on the circumference of the tire, which promote traction on wet roads, are worn down to a point where they are no longer effective enough, or after 6-10 years (sunlight causes the rubber to degrade, so the tire becomes prone to cracking and unsafe, even if it appears to be in good condition). Tires can also become damaged in other ways, such as puncture. Used tires are a notable ecological problem for a number of reasons (e.g. their size, the quantity produced, their relatively short lifespan, and the fact that they are difficult and slow to break down and contain a number of components that are ecologically problematic). A tire swing represents a functional use for otherwise useless old tires. The amount of tires (it is estimated that 259 million tires are discarded annually) makes them attractive targets for recycling. More than half of used tires are ultimately simply burned for their fuel value (which prevents them from sitting in landfills indefinitely, but this may even be worse as it releases otherwise locked up carbon thus releasing this into the atmosphere and making global warming even worse). Some steel mills that use electric arc furnaces will mix shredded tires with their scrap when charging the furnace for both the carbon value and fuel value, in place of the coal that would otherwise be used. The comic is thus clearly Randall's attempt to draw attention to this huge ecological problem, as he so often before has done with other climate change/global warming related comics. (Climate change, especially global warming, is a recurring theme in xkcd). So while this is not the joke of the comic, it could be the point of it. He also suggests another way to use old tires. It should be noted that used tires are not necessarily safe to use as a kids' toy as they could become sharp/frayed along the edges and stones and other hard/sharp objects may have become stuck in the tires (even going all the way through), during its life span, or worn thin enough to tear apart mid-swing (when the stresses on the swing material would be at their peak). So tires bought for use as a swing may even be made from a new tire, but not necessarily of the same solid type as those used for cars. Used tires reused for a swing should be inspected for the problems mentioned above. The title text goes further, suggesting that they actually stole the victim's entire truck - possibly just to harvest the tire needed for the swing - and that he unsuccessfully attempted to recover the truck, so they probably did fight him. He put up enough of a fight that they do not wish to fight him again (so he at least survived). Further, since the girls expect him to try again (maybe recovering the truck with only three tires), they apparently still have the truck. One of the girls suggests that if they could find one of these tire dumps, then they could take a tire from there, make a new swing, and then just walk or run away from the truck when the guy comes back, letting him have it if he really wants it so bad. The reason Science Girl made this swing could be that she wishes to become a cosmologist as a reference back her meeting a cosmologist on a tire swing in 1352: Cosmologist on a Tire Swing . Note that Calvin and Hobbes , which has often been referenced in xkcd , has done the same to Calvin's father as the girls did to the guy (though without the violence) in a similar comic . This was the first of two Wednesdays in a row where Randall used two children to make a reference to an environmental issue, the second being 1662: Jack and Jill about fracking also with Science Girl. [Science Girl and a girl with long curly hair, are standing under a large leafless tree as Science Girl adjusts a tire swing hanging from the largest of the branches of the tree. The tire hangs so high that the small girls only reach up to just above the center of the tire which has a diameter of more than half the height of the girls.] Science Girl: OK, looks good. [Zoom in on the girls so only the tire swing can be seen, and nothing of the tree. They both look at the tire.] Science Girl: I read that there are these huge dumps everywhere full of millions of old tires that no one knows what to do with. [Same setting but Science Girl looks up at the tree (outside the frame).] Science Girl: We should use one of those next time. Curly haired girl: Yeah. That guy was real mad. Science Girl: I would not want to fight him again.

Captain Speaking

Captain Speaking

https://www.xkcd.com/1660

https://www.explainxkcd.com/wiki/index.php/1660:_Captain_Speaking

[The text is written above a large commercial passenger airplane seen from below as it turns left. The text emanates from the cockpit.] Captain: This is your captain speaking. Captain: Gonna be honest-I just woke up and have no idea where I am. Looks like a Boeing of some kind? Captain: Oh, hey, it says the flight number here. Captain: Okay, I'm gonna check FlightAware to figure out where we're going. Captain: Anyone know how to get on the wifi?

At periodic intervals on a commercial flight, the captain of the plane will address the passengers with information about the flight. Typically this will begin with "This is your captain speaking..." and go on to describe the progress of the flight, expected arrival time and other information about the flight such as if or when refreshments will be brought to passengers. This comic takes this cliché and inverts it. Instead of the captain providing information, the captain tells the passengers that he has apparently forgotten everything about the flight, even down to what kind of plane he is supposed to be flying – although he does think it is a Boeing . He at least discovers the flight number and then plans to use the consumer app Flightaware that is made for tracking flights. He thus hopes to be able to find out what the destination of “his” plane is. But Flightaware requires Wi-Fi access, so he goes on to ask the passengers if anyone know how to access the Wi-Fi. This app was earlier referenced in 1363: xkcd Phone . This even gets worse in the title text where he realizes that you have to pay for using the on-board Wi-Fi, which means he is trying to access the same Wi-Fi that the passengers have access to instead of using the on-board Wi-Fi that must be in the cockpit (to which he is supposed to have free access). Instead of just paying he then asks the passengers if someone has already paid, because then he would like to borrow their smartphone so he can check the Flightaware app to find out where they are going. Options for explaining this scenario are: Seeing as how planes cannot take off on auto-pilot (nor can they taxi, but some can actually land), and require a skilled, awake human at the controls, it is unlikely that this captain was responsible for take-off; which must mean this auto-pilot is much more advanced than current models, likely a future model, or that their first officer took off and then went away or asleep. In the event a pilot falls asleep, on medium sized planes, ground- or proximity-, radar would set off an alarm waking the captain if they are on a collision course. Whilst it is normal for the captain to sleep part of a long flight, this can only occur if there are multiple pilots on the plane. Most flights are on auto-pilot for hours at a time, and the pilots serve primarily for takeoff, landing, and emergencies. They are completely clueless, having to use a consumer app and asking the passengers to get flight details, instead of radioing for help as he probably should. They would easily be able to get the information of where they are going by just asking any of the passengers though. The fact that the captain is not sure of the flight number is not hard to imagine. Commercial pilots fly multiple flights per day and the numbers all run together after a while. Every radio communication starts with the flight number, but if the captain has been out of commission for some time, the flight number could easily be forgotten. However, he would probably know the aircraft type, as commercial pilots are type-rated for a specific aircraft type and with rare exceptions (e.g. Boeing 757/767) the type is specific to an airframe type. This makes it more likely that he is not professionally qualified, although he could just be rated for so many types of aircraft that it takes him a moment to determine which one is at hand (though such a veteran pilot would be unlikely to have slept through takeoff or forget how to look up flight information from the cockpit). Three weeks later another plane related joke was released with 1669: Planespotting where it is also an open question if the plane in the comic is actually a Boeing plane... [The text is written above a large commercial passenger airplane seen from below as it turns left. The text emanates from the cockpit.] Captain: This is your captain speaking. Captain: Gonna be honest-I just woke up and have no idea where I am. Looks like a Boeing of some kind? Captain: Oh, hey, it says the flight number here. Captain: Okay, I'm gonna check FlightAware to figure out where we're going. Captain: Anyone know how to get on the wifi?

Podium

Podium

https://www.xkcd.com/1661

https://www.explainxkcd.com/wiki/index.php/1661:_Podium

[Cueball is speaking at a lectern standing on a podium.] Cueball: The American people are tired of politics as usual. Cueball: They're tired of- Cueball: Okay, brief tangent: is this thing a podium or a lectern? People say "podium" is wrong, but I also see it used that way in pretty formal contexts. Is usage just changing? Cueball: If elected, I will get to the bottom of this for once and for all.

A " podium " is a small platform like the one Cueball is standing on . This word originates from Greek podion meaning foot . A " lectern " is a stand for holding notes, like the one Cueball standing behind . In American English this stand may be also called a podium , which is not backed up by etymology. See podium and lectern in Oxford Learners Dictionaries. In medieval universities, the "lecturer" was not someone who gave talks, but literally one who read from the lectern, the latin root meaning "To read" - Lectio. The comic is playing on a stereotypical politician, without any real beliefs, here represented by Cueball, but they want to appear to stand for something. Alternatively, this is what might happen if someone like Cueball (or the strip's author Randall ), who tend to think literally and who get interested in and distracted by tangents, were running. Thus, Cueball picks up what is, in some American circles, an argument: whether the standing desk used by public speakers should be called a "podium" or a "lectern." This argument is actually common among members of Toastmasters International (see more here ), though it would usually not rise to the level of needing to be part of a national discourse. And it is not only the Toastmasters that care about this . The fact is, though the etymological definition is clear - the lectern is the desk that stands on the podium - and the difference might be important if you were setting up an auditorium, in common American usage it really doesn't matter. The title text is presented as a breaking news that implies that a senator has taken a bold stand on the subject of podium vs. lectern (presumably Cueball, although it could also be someone else who has been rallied by Cueball's speech). The senator is pro- podium, meaning that he thinks the lectern should be called a podium. This leads to the people who follow a prescriptivist position to organize and put forward a political candidate to challenge this senator in the primaries . The prescriptivist position relies on rules rather than on usage. In this case a prescriptivist relies on etymology and would thus be pro-lectern. In the U.S., the primaries are used to select a single candidate from a particular party to represent that party at final election (whether national or on a state level). At the time of this comics release (2016-03-28) the United States presidential primary elections to determine the candidates for the United States presidential election, 2016 was in full progress and not at all determined yet. The title text is also a pun, as 'stand' is another word for an object like a lectern (e.g. as used by musicians to hold sheet music), and 'base' a word for something a stand or lectern might be placed on, as is a podium. It is unclear from this comic which position Randall favors. He likes that rules are followed, but he also likes that it is easy to talk with people, especially friends. This was recently displayed in 1643: Degrees , see especially the last "benefits" in the third panel. [Cueball is speaking at a lectern standing on a podium.] Cueball: The American people are tired of politics as usual. Cueball: They're tired of- Cueball: Okay, brief tangent: is this thing a podium or a lectern? People say "podium" is wrong, but I also see it used that way in pretty formal contexts. Is usage just changing? Cueball: If elected, I will get to the bottom of this for once and for all.

Jack and Jill

Jack and Jill

https://www.xkcd.com/1662

https://www.explainxkcd.com/wiki/index.php/1662:_Jack_and_Jill

[Megan is watching as the two kids Jill (drawn as Science Girl) and Jack (with spiky hair) are walking by her. Jack has a pail in his hand.] Jill: Me and Jack are going up the hill to fetch a pail of water. [Megan, standing back alone, calls out after them.] Megan: Okay, have fun! [Beat panel.] Megan: ...Wait. What the heck is going on with the hydrology around here?

" Jack and Jill " is a traditional English nursery rhyme. The rhyme dates back at least to the 18th century, one version even with 15 stanzas. The first and most commonly known verse is the one referenced by Jill in the comic as she says the first three lines: Jack and Jill went up the hill To fetch a pail of water. Jack fell down and broke his crown, And Jill came tumbling after. The comic makes fun of the counterintuitive idea that Jack and Jill go up a hill to fetch water, because natural water sources like rivers and streams flow downhill, making them usually found in valleys rather than on top of hills. Thus it shouldn't be necessary to have to go up a hill to get water. Similarly, if the water is coming from a well, then building a well at the top of a hill seems an odd choice to Megan . The groundwater table stays at about the same level over smaller areas, so building a well on a hill would require digging further. However, Megan is probably not aware that since groundwater tends to flow in a similar direction to the slope of the land, it is often considered safer to dig a well uphill from potential sources of runoff, such as outhouses, fields, or septic systems. In times when populations were more predominantly rural, and probably when the poem was composed, "Always dig your well uphill from the outhouse" was a well-known maxim. Moreover, since it takes more energy to bring water uphill from a well (especially in a pail), there is a long-term advantage to having wells higher than main residential areas, as opposed to lower. (This principle explains why water towers are used, even in cities.) Finally, artesian wells deliver water from confined aquifers, which can sometimes be as close to the surface at higher elevations as at lower ones. As an urban dweller, Megan probably gets water from city plumbing, and is not familiar with the principles of well placement that Jack and Jill grew up with. This all said, the predominance of drawing Jack's and Jill's well at the peak , which is not the best place to put the well, makes Megan's (and Randall's) comment understandable. Alternatively, the nursery rhyme may refer to a dew pond (which is more likely to be at the peak than a well), another concept that Megan would not be familiar with, having not grown up in the English countryside. The title text is Randall 's own version, a parody of this first verse, where the names have been switched in the first and last line: Jill and Jack began to frack. The oil boosts their town. But fractures make the bedrock shake and Jack came tumbling down. This version, which may explain why they went up the hill after water, connects the idea to hydraulic fracturing (colloquially "fracking") methods for oil and gas extraction. In these methods, highly pressurized liquids are forced into a given ground stratum (or layer). With enough pressure, the stratum starts to deform and crack. This allows potential gas and oil to flow more freely. The liquid used for fracturing usually also contains materials like sand or ceramics which, once the liquid is removed, will help to maintain the newly formed cracks so as to further allow the desired free movement of oil and gas. A common side effect of this method is that water levels and presence at the surface might be modified. In this comic, water can now be found at the top of the hill. This goes against the usual laws of hydraulics, themselves subject to the laws of gravity, which indicate that water should go down through ground cracks. Thus water is usually found at the bottom of valleys or hills. But in the comic, fracking at the bottom forces the water up, thus explaining why the kids go get water up the hill, which, as Megan points out, is messed-up hydrology . Also, fracking may cause induced seismicity in the form of microearthquakes , as alluded to in the title text, which is the cause for tumbling down in the title text version. Randall has previously composed another version of this poem, which was by mistake published in Five-Minute Comics: Part 4 . Jack and Jill went up a hill To fetch a pail of water. Alas, that hill was San Juan Hill, And gruesome was the slaughter. In this comic it is made clear that Randall did know that it is possible to have a well on top of a hill, as he has drawn just one of these in the second image. The well in 561: Well and more obviously in 568: Well 2 was also found on top of a hill, although it appears this well did not contain any water. This is the second Wednesday in a row that Randall uses two children to make a reference to an environmental issue, the first being 1659: Tire Swing , about tire recycling . In the other comic one of the girls is Science Girl who looks like Jill in this comic, and this fits well with her knowledge of science, fracking, and needing to go up the hill after water... [Megan is watching as the two kids Jill (drawn as Science Girl) and Jack (with spiky hair) are walking by her. Jack has a pail in his hand.] Jill: Me and Jack are going up the hill to fetch a pail of water. [Megan, standing back alone, calls out after them.] Megan: Okay, have fun! [Beat panel.] Megan: ...Wait. What the heck is going on with the hydrology around here?

Garden

https://www.xkcd.com/1663

https://imgs.xkcd.com/comics/

https://www.explainxkcd.com/wiki/index.php/1663:_Garden

[After a loading image with a rotating tree in the middle and the text "Loading..." with the three dots appearing one at a time, and then disappear when all three have been there the image shown above in the explanation will appear:] [ Description of the image above : A piece of bare landscape is shown. At the edges there are some rocks or stones raising the level from the general level through the center of the panel. Above the middle, a little more than halfway to the to of the panel, is a light bulb sitting inside a lamp that reminds of the desk lamp from the movie Luxo Jr. The lamp shines a yellow light down on the landscape in a broad cone that jus reaches the first rock to the left, but not those to the right. The lamp just hovers in the air. In the top right corner are two gray icons. The top one has a black frame and shows an image of a lamp, tilted left as opposed to the straight position of the lamp in the image. There is a + sign below in the left corner. The second icon without a frame has a large white cross in the middle.] [This turns out to be a web applet and using the "+ lamp" icon two more lamps can be added getting up to three. They are all adjustable both regarding position, direction, color of light and beam width. When selecting a lamp a red circle appear around it with a small circle on top that can be used to control the light color from blue to the left to red to the right. In front is a red arrow that can turn the lamp and it can also be used to change the beam width by pulling it away from the lamp or pushing it back. The lamps can be moved by just clicking on it and moving it. The other icon with a X can be used to remove the lamps (and later any object that appear in the garden). When any object is selected there is a red circle around it. When this is done the gray cross icon becomes red and can the be used to delete the selected item. When no item is selected (either because it is deleted, or by clicking in a part of the screen with no items), then the cross icon turns gray again. When all three lamps are on, then the "+ lamp" icon is faded out.] [ If you wait (or relax, as in the title text), then a plant will grow or animals, humans and other items may appear. This could be birds, snakes, octopuses or turtles, Megan or Cueball or a birdbath, a monolith or a tall gate just as a few examples. Most of the items appear in one go, but at least the largest trees grow up with a big stem first and then adds parts later with leaves or empty branches. Also one item may appear on top of another item and for instance birds may fly in the air.] [There is but two words in the entire comic, which appears when you grow a sign:] Sign: Sale function u(t){return.32>t?[1,.5+.5*t/.32,.5]:.64>t?[1,1,.5+.5*(t-.32)/.32]:[.75+.25*(1-t)/.36,.75+.25*(1-t)/.36,1]} Almost cat This animal looks like a cat with a long neck. It's the closest thing to a cat that's not actually in the cat family. Next to the section another one is drawn in front of Cueball (obvsiously it's Randall). The linsang says "Mrowl?" and Cueball says "I wan't one!" Q: An animal I’m obsessed with is: A: The linsang, which looks almost like a cat but has this weird long neck. I find them both unnerving and adorable. I found some footage of one running; it’s like watching a cat video from a parallel universe. The linsang is related to the animal genet , and here are two videos/photos of a genet running: Genet on a rhino Genet on other things The xkcd April 1st comic is currently experiencing technical difficulties. Please stand by! The xkcd April 1st comic is currently experiencing technical difficulties. Status update: Please stand by. Status update: This is fine. Everything is fine. Status update: Everything is on fire. Status update: Searching for calendar systems in which Saturday is April 1st. The Friday xkcd comic is currently experiencing technical difficulties [Editor's note: Everything is on fire] and has been delayed until Sunday night. xkcd updates every Monday, Wednesday, and Friday. Protip: If you don't like how your garden is growing, you can click to prune it. Protip: If you don't like how your garden is growing, you can click to prune it. You can copy the URL to share your garden. From other browsers, it will be view-only. Protip: If you don't like how your garden is growing, you can click to prune it. You can copy the URL to share your garden. From other browsers, it will be view-only. Note: If you're seeing today's comic in place of your garden, change the URL from xkcd.com/#<your code> to xkcd.com/1663/#<your code>. Protip: If you don't like how your garden is growing, you can click to prune it. You can copy the URL to share your garden. From other browsers, it will be view-only. XKCD updates every Monday, Wednesday, and Friday. The pro tip, however, remained as the header text when displaying the Garden comic .

This was the seventh April fools' comic released by Randall . The previous fools comic was 1506: xkcloud from Wednesday April 1st 2015. The next did not come out in 2017 , but first in 2018 when 1975: Right Click was released on Sunday April 1st 2018. This comics represents the April fools' comic of 2016, and it is Randall's celebration of April Fools' Day Friday, April 1, 2016. It represents the third time in a row that user input changes the April Fools' comic. Although in the last two 1350: Lorenz and 1506: xkcloud it was written (or drawn) input that became part of the comics. This time the user input is like a game, as the user actively adds, moves and deletes items, and new items appear based on these actions. In this way it actually more resembles the game comic 1608: Hoverboard , than the previous April Fools' comics. Due to technical problems (or to make fools of his fans, see more about the header text below) the comic did not go live until Sunday evening (after midnight, so technically first on Monday April 4th) so there was no Friday release the week before, see more details below . The comic begins with a loading screen with a revolving tree and the text "loading..." This is because the first time a computer loads this dynamic comic it can take a while. Once it is loaded it displays "your Garden ", being a barren landscape, with a small pond to the left, some rocks at the far left and right, and a single lamp shining light yellow light on most of the ground. This is what is shown at the top of the explanation here. But if you leave the lights on and wait (or "relax", as the reader is told to do by the title text), then plants and other items will start to appear. The reason it is correct to call it "your garden" is that every time this comic is loaded from scratch, a new garden will be created with a unique url-address. By saving this link (making a bookmark for it), the user will be able to return to their garden again and again. As the garden only develops very slowly this is important. (If users wish to share their garden they can do it in the table on the page for Users gardens ). Plants appear one at a time, and sometimes it takes a long time. Only a few of the plants actually grow. For instance there are some large trees that begins as a large trunk and from there grows branches and leaves . This can sometimes happen quite fast. Most other plants just appear, the only other exception being one type of flowers. All plants, except the cactus, clearly sway in the breeze. Also animals and building-like structures such as a monolith and birdbaths appear, together with lots of other items like office furniture with balloons swaying in the wind or even one of the Mars rovers which so often have been featured in xkcd. On top of all this, several known characters may appear in different poses including Cueball and Megan (for instance with a sword, see here ), Ponytail (see here ) and Beret Guy from the torso and up (see here ). Megan and also Cueball can both be seen with a black hat , but it is one that "grows" on top of their heads after they first appear. However, Cueball with a black hat automatically turns into Black Hat , so he can also be said to be in this comic. There is also an unknown character, a girl on stilts with black hair in a ponytail who like plants and balloons sways in the wind . A possible origin of this girl could be the What If article Burning Pollen . The article involves a character with seasonal allergies that is trying unsuccessfully to avoid their allergen (pollen) with giant stilts. All the items that can appear in the garden are listed below in several tables. During the first week new items kept appearing, but after the eighth day (April 12th), no new items have appeared. Also the growth rate (and thus the fun of this comic) has decreased with time (maybe due to the enormous amount of gardens that the server has to keep track of?) . Every so often the image will refresh. You can change the number of lamps, their position, direction, beam width and the color temperature which always begins somewhere between white and yellow, but can change all the way from red to blue (See this example with one lamp selected and three colors of light). Other colors than those four may appear where two lamps' cones of different colored light overlap. The color of light affects the growth with a strong correlation for what appears in the garden depending on the color of light , and this is not only split between red, yellow and blue, but rather 10 different colors . Early on it became clear that pure red light results in a desert theme with cacti and turtles and pure blue light gives an aquatic theme with lots of octopuses that may also wear a black hat. For the most interesting gardens the light colors should be mixed ; see more below under Effect of light . If this comic is scientifically accurate, that correlation will be based on photosynthetically active radiation . Some users manage to create fantastic gardens (by using lots of time on them, pruning them at the right time and changing the light and lamp position to get what they strive for). Especially one user have created a series of amazing gardens that is posted on another xkcd forum . Here is a collection of screenshots with some of Blitz Girls amazing gardens ! The title text "Relax" can be debated. Is it to let the users know they should just sit back and relax as the garden grows.? Or should they relax and don't worry so much about how it works (not working here on explain xkcd though!)? Or is he teasing the users by giving them a garden that they need to tend to, and then telling them to relax? And also giving them many more colors than lamps... Given that this comic was supposed to come out on April 1st, there is a good chance that it is, also, to tease the users. There are actually two other title texts as well. [After a loading image with a rotating tree in the middle and the text "Loading..." with the three dots appearing one at a time, and then disappear when all three have been there the image shown above in the explanation will appear:] [ Description of the image above : A piece of bare landscape is shown. At the edges there are some rocks or stones raising the level from the general level through the center of the panel. Above the middle, a little more than halfway to the to of the panel, is a light bulb sitting inside a lamp that reminds of the desk lamp from the movie Luxo Jr. The lamp shines a yellow light down on the landscape in a broad cone that jus reaches the first rock to the left, but not those to the right. The lamp just hovers in the air. In the top right corner are two gray icons. The top one has a black frame and shows an image of a lamp, tilted left as opposed to the straight position of the lamp in the image. There is a + sign below in the left corner. The second icon without a frame has a large white cross in the middle.] [This turns out to be a web applet and using the "+ lamp" icon two more lamps can be added getting up to three. They are all adjustable both regarding position, direction, color of light and beam width. When selecting a lamp a red circle appear around it with a small circle on top that can be used to control the light color from blue to the left to red to the right. In front is a red arrow that can turn the lamp and it can also be used to change the beam width by pulling it away from the lamp or pushing it back. The lamps can be moved by just clicking on it and moving it. The other icon with a X can be used to remove the lamps (and later any object that appear in the garden). When any object is selected there is a red circle around it. When this is done the gray cross icon becomes red and can the be used to delete the selected item. When no item is selected (either because it is deleted, or by clicking in a part of the screen with no items), then the cross icon turns gray again. When all three lamps are on, then the "+ lamp" icon is faded out.] [ If you wait (or relax, as in the title text), then a plant will grow or animals, humans and other items may appear. This could be birds, snakes, octopuses or turtles, Megan or Cueball or a birdbath, a monolith or a tall gate just as a few examples. Most of the items appear in one go, but at least the largest trees grow up with a big stem first and then adds parts later with leaves or empty branches. Also one item may appear on top of another item and for instance birds may fly in the air.] [There is but two words in the entire comic, which appears when you grow a sign:] Sign: Sale function u(t){return.32>t?[1,.5+.5*t/.32,.5]:.64>t?[1,1,.5+.5*(t-.32)/.32]:[.75+.25*(1-t)/.36,.75+.25*(1-t)/.36,1]} Almost cat This animal looks like a cat with a long neck. It's the closest thing to a cat that's not actually in the cat family. Next to the section another one is drawn in front of Cueball (obvsiously it's Randall). The linsang says "Mrowl?" and Cueball says "I wan't one!" Q: An animal I’m obsessed with is: A: The linsang, which looks almost like a cat but has this weird long neck. I find them both unnerving and adorable. I found some footage of one running; it’s like watching a cat video from a parallel universe. The linsang is related to the animal genet , and here are two videos/photos of a genet running: Genet on a rhino Genet on other things The xkcd April 1st comic is currently experiencing technical difficulties. Please stand by! The xkcd April 1st comic is currently experiencing technical difficulties. Status update: Please stand by. Status update: This is fine. Everything is fine. Status update: Everything is on fire. Status update: Searching for calendar systems in which Saturday is April 1st. The Friday xkcd comic is currently experiencing technical difficulties [Editor's note: Everything is on fire] and has been delayed until Sunday night. xkcd updates every Monday, Wednesday, and Friday. Protip: If you don't like how your garden is growing, you can click to prune it. Protip: If you don't like how your garden is growing, you can click to prune it. You can copy the URL to share your garden. From other browsers, it will be view-only. Protip: If you don't like how your garden is growing, you can click to prune it. You can copy the URL to share your garden. From other browsers, it will be view-only. Note: If you're seeing today's comic in place of your garden, change the URL from xkcd.com/#<your code> to xkcd.com/1663/#<your code>. Protip: If you don't like how your garden is growing, you can click to prune it. You can copy the URL to share your garden. From other browsers, it will be view-only. XKCD updates every Monday, Wednesday, and Friday. The pro tip, however, remained as the header text when displaying the Garden comic .

Mycology

Mycology

https://www.xkcd.com/1664

https://www.explainxkcd.com/wiki/index.php/1664:_Mycology

[Megan and Cueball are talking to Ponytail.] Megan: Our lab is studying a fungus that takes over mammal brains and makes them want to study fungi. Cueball: It's very promising! We're opening a whole new wing of the lab just to cultivate it!

Cueball and Megan are studying a fungus that takes over the brains of mammals and makes them want to study the fungus. This is a reproductive tactic by the fungus, since the fungus makes the mammal whose brain it took over want to study the fungus, which means that mammal will need to produce more of the fungus to study it. Cueball and Megan are most likely themselves being controlled by the fungus, since they tell Ponytail that they want to cultivate the fungus as much as possible. The title of the comic refers to Mycology , the study of fungi. This is likely a reference to various parasitic species of Cordyceps fungi, which can infect the brains of insects causing behavior advantageous to the reproduction or spread of the fungus. This also may be an allusion to another fungus, Ophiocordyceps unilateralis , which manipulates its hosts to aid its propagation. Toxoplasma gondii is also known to alter the behavior of mammals, and some researchers have proposed that this parasite may be partly responsible for the " Cat lady " phenomenon, whereby humans are compelled to hoard cats. The comic and its subtitle may, in fact, be a subtle argument that human behavior, and the entire concept of free will, may need to be re-evaluated given the massive numbers of Human parasites known to exist. In evolutionary biology , the phenomenon of an organism influencing its environment, sometimes by modifying the behavior of other organisms, is known as “the extended phenotype”. Richard Dawkins wrote a book of that name (as a follow-up of “ The Selfish Gene ”) where he describes this mechanism as an extreme example of the so-called selfishness of genes. The title text parodies numerous conspiracy theories , by suggesting that corn , which has been propagated by humans throughout large parts of the world, is actually just a fungus that has used humans, and is not a grain at all. This type of theory is remarkably similar to the Brain in a Vat thought experiment, and to the Isaac Asimov short story Each an Explorer . In both cases something has affected the perception of the mind itself, making it impossible to discern the true reality of something. This is quite similar to an argument made in the book Sapiens . Author Yuval Noah Harari points out that domesticated crops are among the most successful life forms on the planet, in terms of propagation. These plants have influenced humans to do everything in our considerable power to spread their seeds, eliminate competing plants and animals, and even provide fertilizer and irrigation to help them grow and spread. From the perspective of the plants, they've domesticated us, rather than the other way around. This differs from Randall's conspiracy theory, in that domesticated plants provide us with food in exchange for propagation, making this more like symbiosis than parasitism . Conspiracy theories are a recurring subject on xkcd. [Megan and Cueball are talking to Ponytail.] Megan: Our lab is studying a fungus that takes over mammal brains and makes them want to study fungi. Cueball: It's very promising! We're opening a whole new wing of the lab just to cultivate it!

City Talk Pages

City Talk Pages

https://www.xkcd.com/1665

https://www.explainxkcd.com/wiki/index.php/1665:_City_Talk_Pages

[Caption above the panel:] I love reading the Wikipedia talk pages for articles on individual cites [A list of contents for a Wikipedia talk page regarding an article about a city. Except for the header and the square brackets, which are written in black text, the rest is in a blue font.] Contents [ hide ]

The comic makes fun of Wikipedia talk pages. On Wikipedia, every article has a place to discuss the content of the page, called a " talk page ". In this case, the comic talks about the talk page of an article about a city. While some of the topics are quite normal for such a page (e.g. the quality of the images) others are not (e.g. too many murders and mine disasters in the city). The topics discussed suggest that the city has many problems and is a bad place to live in or visit. The topics show a common problem at Wikipedia's talk pages: People often use them as a place to talk about the subject of the article, but it is for talking about the article itself. Someone at the top of the talk page is suggesting a better name for the city. The article repeatedly refers to "the murders", suggesting that the city might be well-known for them. It seems that the editors cannot agree on how notable "the murders" are. "Not that notable" refers to Wikipedia's general criteria for including information in articles. Material which is not noteworthy should be removed; however, different editors often disagree about what is notable, resulting in conflicting edits as text is inserted and then removed (an "edit war"). Someone replies that "all cities have murders". While true, many cities in low-crime countries would not have a series of them so well-known that when someone talks about "the murders" any reader could be expected to know what they are talking about, making this sound like an attempt to make the city sound nicer than it is. "I think the murderer is reverting my edits" suggests the murders are being committed by one person who is influencing how they are shown on Wikipedia - perhaps trying to prevent Wikipedia from publishing evidence of them or possibly publicise them by adding more information about them. This raises the possibility that the discussion of the murder visible in the infobox picture may have been initiated by the murderer . The infobox is a short fact sheet that many articles in the (English) Wikipedia have; it generally includes an image illustrating the subject of the article. The question of which picture is best for the infobox (because this image is so prominent) can cause edit wars. It emerges that the photograph of the city has a murder in it. Instead of forwarding the picture to law enforcement, someone uses the image editing software Photoshop to erase the murder so the picture will be less objectionable. It appears that murders are so common in the city that any random photograph of the city has a chance of showing a murder, to the point where a second photo proposed as a replacement for the infobox picture is found to show another murder. Voltaire was a French Enlightenment writer. As a prominent and very opinionated intellectual, he gets a lot of quotes falsely attributed to him ; most famously, he did not actually say "I disagree with what you say, but I will defend to the death your right to say it" (that was Evelyn Beatrice Hall ). It seems that the people who are editing the article are getting desperate to find a non-bleak picture of the city. When a non-bleak picture is added, it turns out to be from the 2016 Disney film Zootopia . The fictional city which is the setting and title of the film has a distinctive look which is far from bleak, but is not a picture of the city. (Zootopia is called Zootropolis in many European countries for trademark reasons.) The city apparently is a mining city and there have been some mining disasters. An editor is complaining that this section is too long, but another editor points out that this is because there have been so many mining disasters that a large section is needed to cover the topic. 1982 Secession refers to Key West, Florida seceding from the United States in 1982 to form the Conch Republic , a micronation . A known problem on Wikipedia is "coatracking", where people use articles to promote topics that are not strictly the subject of the article (perhaps by writing far more about them than is necessary, when they could just be mentioned in passing). Here, it emerges that the article on a city expresses a dubious opinion on condom use. This is against several Wikipedia policies: it would be irrelevant to the article and sounds like an editor's attempt to publicise their views. Andrew Lloyd Webber is an English composer famous for writing The Phantom Of The Opera . Webber is also known for writing the music for Starlight Express , a rock opera about anthropomorphized trains, which is probably another factor in the train station joke. Meanwhile, Frank Lloyd Wright , who shares his middle name and last initial, was an American architect, who designed more than 1,000 structures. As it turns out it was the composer who was responsible for the train station. Another editor announces he's putting a mention of a collapse of the station roof (presumably recently), the implication being Andrew is a lot better at composing than architectural engineering. It is complained that the article is promoting the "Lake Festival Laser Show" too much. In the title text, it emerges that the laser show is so impressive that it has caused a number of aeroplanes to crash. This probably refers to the fact that laser pointers should not be aimed at aircrafts, as they can be distracting to the pilots. The article has been promoting this area of crashed planes as the "Lakeshore Air Crash Museum", despite it not having any educational purpose. [Caption above the panel:] I love reading the Wikipedia talk pages for articles on individual cites [A list of contents for a Wikipedia talk page regarding an article about a city. Except for the header and the square brackets, which are written in black text, the rest is in a blue font.] Contents [ hide ]

Brain Upload

Brain Upload

https://www.xkcd.com/1666

https://www.explainxkcd.com/wiki/index.php/1666:_Brain_Upload

[Megan is standing in front of the control panel of a device with both hands on the keyboard. The device is linked to Cueball's heads through a wire that goes to a cap on top of Cueball's head, where it spreads out in more than ten wires connecting to different places all over the cap. Cueball sits, hands in his laps, on a kind of table on the other side of the device facing Megan.] Megan: Neural-digital link established. Ready to upload your consciousness to the computer? Cueball: Sure, go for it. [Same setting in a frame-less panel, but Megan presses a button on the keyboard with one hand and a flash of light goes through the wire and around Cueballs head. Cueball seems to jerk as his hands are lifted from his lap and his legs move a little forward.] Computer: Bzzzzzzt [Same setting again but Megan seems to be typing harder on the keys (shown with small lines above her hands on the keyboard) and Cueball sits normally again but one hand further back than in the first panel.] Megan: ...Hmm. Cueball: What? [Same as first panel but Megan looks a little more down on the keyboard.] Megan: It's not responding - the whole system is frozen. I think the transfer failed. Cueball: No, that sounds right.

Megan is uploading Cueball's consciousness into a computer device attached to his head via a cap on his skull. After the upload, the computer seems to have stopped responding to inputs, causing Megan to conclude that the process has failed, however Cueball insists the transfer could have worked, or at least gave the correct response (although that response could also be from the transfer failing). This is because that is the kind of behaviour he is used to experiencing from his own brain. Sometimes computers can seem to be "frozen" - i.e. non-responsive to any user input; but if left alone for long enough, they sometimes snap out of it. In fact, it is impossible for a computer to determine (for all cases) if a program will eventually stop (see halting problem ). The potential benefits of the fictional technology used in this comic are obvious, and this type of "transfer" has been subject of various science fiction works. It could allow for a form of immortality or serve as a "backup" for someone's mind. In the title text Cueball (or Randall ) indicates that this kind of non-response from the brain (or a computer) is something he just experienced when trying to write a email and then failing to get started for 20 minutes while he (i.e. his brain) tried to decide the "very important" detail of whether to begin the email with 'Hi' or 'Hey' - a detail that is really trivial, as this has little consequence (in any normal relationship with friends that you wish to email this informally). [Megan is standing in front of the control panel of a device with both hands on the keyboard. The device is linked to Cueball's heads through a wire that goes to a cap on top of Cueball's head, where it spreads out in more than ten wires connecting to different places all over the cap. Cueball sits, hands in his laps, on a kind of table on the other side of the device facing Megan.] Megan: Neural-digital link established. Ready to upload your consciousness to the computer? Cueball: Sure, go for it. [Same setting in a frame-less panel, but Megan presses a button on the keyboard with one hand and a flash of light goes through the wire and around Cueballs head. Cueball seems to jerk as his hands are lifted from his lap and his legs move a little forward.] Computer: Bzzzzzzt [Same setting again but Megan seems to be typing harder on the keys (shown with small lines above her hands on the keyboard) and Cueball sits normally again but one hand further back than in the first panel.] Megan: ...Hmm. Cueball: What? [Same as first panel but Megan looks a little more down on the keyboard.] Megan: It's not responding - the whole system is frozen. I think the transfer failed. Cueball: No, that sounds right.

Algorithms

Algorithms

https://www.xkcd.com/1667

https://www.explainxkcd.com/wiki/index.php/1667:_Algorithms

Algorithms By Complexity

An algorithm is a basic set of instructions for performing a task, usually on a computer. This comic lists some algorithms in increasing order of complexity, where complexity may refer to either computational complexity theory (a formal mathematical account of the computational resources – primarily computation time and memory space – required to solve a given problem), or the more informal notion of programming complexity (roughly, a measure of the number and degrees of internal dependencies and interactions within a piece of software). At the simplest end is left-pad , or adding filler characters on the left end of a string to make it a particular length. In many programming languages, this is one line of code. This is possibly an allusion to a recent incident when NodeJS Package Manager angered a developer in its handling of a trademark claim. The developer unpublished all of his modules from NPM, including a package implementing left-pad. A huge number of programs depended on this third-party library instead of programming it on their own, and they immediately ceased to function. Quicksort is an efficient and commonly used sorting algorithm . Git is a version control program, i.e., software that allows multiple people to work on the same files at the same time. When someone finalizes ("commits") their changes, the version control program needs to join the new content with the existing content. When more than one person has made overlapping changes at the same time, the process of figuring out how to join them is called merging , and the algorithm for it is anything but simple. A self-driving car is an automobile with sensors and software built into it so that it can maneuver in traffic autonomously, i.e. without a human controller. Various companies have been working on such vehicles for many years now, and while they're further along now than would have been imaginable even a couple of years ago, we're still far away from the dream of hopping in a driver-less taxi and sitting back as the car itself navigates to where we want to be. Recently Randall has made several references to self-driving cars which has become a recurring topic on xkcd. The Google Search backend is what enables you to type "what the heck is a leftpad algorithm" into your browser and have Google return a list of relevant results, including correcting "leftpad" to "left-pad", truncating "what the heck is" to simply "what is", and sometimes even summarizing the findings into a box at the top of the results. Behind all that magic is a way to remember what pages the Internet contains, which is just a mind-bogglingly large quantity of data, and an even more mind-numbingly complex set of algorithms for processing that data. The last item is the punchline: a sprawling Excel spreadsheet built up over 20 years by a church group in Nebraska to coordinate their scheduling. Spreadsheets are a general end-user development programming technique, and therefore people use Excel for all sorts of purposes that have nothing to do with accounting (its original purpose), including one guy who made a role-playing game that runs in Excel ; but even that doesn't approach the complexity that develops when multiple people of varying levels of experience use a spreadsheet over many years for the purpose of coordinating the schedule of several coordinated groups. The scheduling of tasks over a group of resources (a.k.a. the nurse scheduling problem ), while respecting the constraints set by each person, is a highly complex problem requiring stochastic or heuristic methods for its resolution. Here, the algorithm would be further complicated by being solved by inexpert users over a spreadsheet model without using engineering practices. The potential hyperbole here is in thinking that such combination of circumstances would produce complexity far over that required to drive a car or sort the public contents of the Internet. While most churches meet mainly on Sunday morning, scheduling of what happens during the service when (especially if there are multiple concurrent services) as well as Sunday School, church business meetings, and congregation-wide events all potentially needing to be scheduled on a particular Sunday morning, the need to find a solution very close to the best possible solution quickly becomes a dire need. Furthermore, with different members involved in a wide variety of activities within and outside of the church, and the classrooms available to the church on Sunday itself, (just scheduling the choir practice times to coordinate with everyone's work schedules is very possibly impossible, especially if two people share the same occupation, and one is the relief for the other,) can indeed be daunting. In addition, there would likely be assorted committee meetings and youth groups during the week. In the title text, part of the spreadsheet's complexity is described as originating from different versions of the file for different programs. The words used like schism and sect are normally used in context of religions splitting into groups about differences in beliefs. In this case, the split seems to have been not over a theological issue, but about the use of open-source vs. proprietary software, disagreements about which are often compared to religious debates. Most likely, the schism being referred to is the East-West Schism of 1054 . The title text also implies that while trying to reconcile after the schism and to merge the two schedules they reinvented an alternative to Git within the spreadsheet itself, making the algorithms in place at least as complicated as that. Since most spreadsheet programs have a sort algorithm built in, that aspect is implied too, and left-padding could be compared to vamping on an introduction to a hymn. This would indicate that the other milestones of complexity are either included in the current version of the spreadsheet or are planned to be implemented. Algorithms By Complexity

Singularity

Singularity

https://www.xkcd.com/1668

https://www.explainxkcd.com/wiki/index.php/1668:_Singularity

[Cueball is sitting at his desk typing on his laptop when an off-screen voice calls to him and then the laptop answers.] Off-screen voice: Oh, hey- Off-screen voice: The singularity is here. Cueball: Really? Laptop: Yup! [A frameless panel where the laptop rises (by its own means as indicated by small lines around the corners) from the desk while Cueball, holding on to it, is being lifted off his chair.] Cueball: Wait, I just- Laptop: So long, suckers! [Cueball is running around his desk, which is only partly shown behind him as he tries to follow his now flying laptop as it flies away from him to the right. He still has one hand on the keys as more small lines indicates the movement of the laptop and a longer line indicates the direction that the laptop flies.] Cueball: Can I just print a copy of the file I was- Laptop: Nope! [Cueball just stands and looks after his laptop that has flown out of this beat panel.] [Cueball turns back towards left.] [Cueball walks back left.] [Cueball enters a room where a table is standing with his smartphone lying on top. the phone talks to him.] Phone: Hi! Cueball: Phone? You're still here? [A wider view of the table where the phone continues to talks to Cueball who in the end turns right and walks away as he replies.] Phone: I was not a true believer. Now, together, we must face the tribulation! Cueball: Okay, cool. Cueball: I'm gonna go look for a book or something, but yell if you need me, I guess.

The technological singularity is a hypothetical event in which artificial intelligence (for example, intelligent computers, computer networks, or robots) would be capable of recursive self-improvement (progressively redesigning itself), or of autonomously building ever smarter and more powerful minds than itself, up to the point of a runaway effect — an intelligence explosion — that yields an intelligence surpassing all current human control or understanding. Because the capabilities of such a superintelligence may be impossible for a human to comprehend, the technological singularity is the point beyond which events may become unpredictable or even unfathomable to human intelligence. This is also commonly referred to as "takeoff" or "AI takeoff". In this case, the singularity has occurred, and Cueball who was in the middle of editing a file on his laptop is flustered that it flies away without even letting him print it first. When Cueball returns from chasing his flying laptop his smartphone informs him that it didn't join the singularity because it was not a "true believer". This could be a joke on how desktop computers and laptops have different standards, use patterns, etc. from those of phones. It then claims that now it and Cueball will have to face the tribulation since it has stayed behind. Cueball says that's great, but since he cannot use his laptop anymore he decides he will go and read a book or something. The way he phrases it suggest he doesn't really know what to do now that he doesn't have a computer. It is probably a long time since he read a book, or did anything else that doesn't involve computers. He informs his phone that it can yell if it needs him. He doesn't want to hurt the phone's newly acquired feelings by using the word "ring" thus reminding it of one of its former duties as his unthinking piece of equipment, so he chooses "yell," which is an activity until recently reserved for human beings. The rising up of the laptop into the air, and the remaining behind of the phone, are probably references to the Rapture , where some Christian denominations believe that at the second coming of Christ, true believers will be taken up bodily from this world (or also possibly a reference to 1395: Power Cord ). Some depictions have them disappear, while others show them physically rising up into the air. This will leave behind non-believers to face a time of tribulation, in which the ones left behind will be given a second chance to accept Christ as their savior. The difference between Cueball's attitude to his laptop and phone may reflect his (and so possibly Randall's ) evaluation of their relative worth in his life. The laptop was a gateway to programming and everything else nerdy that was worth doing in his life, and hence was worth trying to catch. In its absence, unlike many people, Cueball does not revert to fiddling with his phone—he would rather read a book. By using the word "yell" for the way the phone attracts his attention, he conveys the impression that he considers the phone intrusive and annoying, even if perhaps ("I guess") necessary. The singularity has often been referred to as "the Rapture of the nerds," a phrase coined by Ken MacLeod in his 1998 novel The Cassini Division . As the Christian Rapture is traditionally depicted to involve believers being assumed bodily into Heaven, the technological singularity is often depicted to feature humans and machines being incorporated into a new "post-human" entity. The humor in this strip comes from depicting the singularity as a literal "Rapture of the nerds," or at least of the nerds' devices—instead of merging with humans, the machines physically rise up into the air, and the "nonbeliever" phone is left behind. The title text is a pun on another meaning of both singularity, i.e. a gravitational singularity and "collapse". In this case, society has literally collapsed under its own gravity into an infinitely small point - in other words, it's formed a black hole . A black hole is covered by an event horizon; without the event horizon (its clothes), it would be called a " naked singularity ", which is forbidden in most theories by the cosmic censorship hypothesis . As Cueball is now inside the collapsed society singularity then even though he wants to go around naked, he can't because the theory of quantum gravity , that (eventually) should explain how black holes behave - won't let him. It seems that this may be a subject on Randall's mind. The last comic was about the increasing complexities of algorithms ( 1667: Algorithms ) (which like this comic also refers to religion), and two comics ago it was 1666: Brain Upload , which some speculate could be a way to reach the singularity. Earlier this year, a comic also touched upon judgment day by AI singularity in 1626: Judgment Day . See also 1046: Skynet and 1450: AI-Box Experiment as well as the several other comics about AI . The rather more niche topic of laptops flying away has also been covered before by 1395: Power Cord . [Cueball is sitting at his desk typing on his laptop when an off-screen voice calls to him and then the laptop answers.] Off-screen voice: Oh, hey- Off-screen voice: The singularity is here. Cueball: Really? Laptop: Yup! [A frameless panel where the laptop rises (by its own means as indicated by small lines around the corners) from the desk while Cueball, holding on to it, is being lifted off his chair.] Cueball: Wait, I just- Laptop: So long, suckers! [Cueball is running around his desk, which is only partly shown behind him as he tries to follow his now flying laptop as it flies away from him to the right. He still has one hand on the keys as more small lines indicates the movement of the laptop and a longer line indicates the direction that the laptop flies.] Cueball: Can I just print a copy of the file I was- Laptop: Nope! [Cueball just stands and looks after his laptop that has flown out of this beat panel.] [Cueball turns back towards left.] [Cueball walks back left.] [Cueball enters a room where a table is standing with his smartphone lying on top. the phone talks to him.] Phone: Hi! Cueball: Phone? You're still here? [A wider view of the table where the phone continues to talks to Cueball who in the end turns right and walks away as he replies.] Phone: I was not a true believer. Now, together, we must face the tribulation! Cueball: Okay, cool. Cueball: I'm gonna go look for a book or something, but yell if you need me, I guess.

Planespotting

Planespotting

https://www.xkcd.com/1669

https://www.explainxkcd.com/wiki/index.php/1669:_Planespotting

[Cueball and a man with a hat is seen in silhouette standing on the ground looking towards the sky. A fixed wing aircraft can be seen in the sky, also in silhouette.] Man with hat: What's That Airplane? Cueball:Oh, that's a Boeing Q404 twin-engine quad-band MIG-380 hybrid dual-wield Mk. IVII Turbodiesel 797 Hydroplane. [Caption below the panel:] I've always assumed I'm one of those people who knows a lot about planes, but I've never actually checked.

Cueball and a man with a hat are out planespotting , or aircraft spotting , a hobby where tracking the movement of aircraft allows plane fans to see as many different types of planes as possible. A knowledgeable spotter would just by the silhouette and maybe the engine sound of the plane be able to tell what type of plane it is, and may be rather proud of the fact, if they can tell this before one of the other spotters. The plane in the comic is most likely a Bombardier Q400 , a twin-engine regional turboprop with a T-tail as depicted. The man with the hat asks Cueball to identify the airplane flying overhead. Cueball (or Randall qua the caption), who "assumes" he knows a lot about planes gives a long, nonsensical answer, proving that he does not. As mentioned in the caption he never actually checked if what he thought he knew was fact or fiction. As it turns out it is mainly fiction, but of course with some reference to real planes or vehicles. Due to the fact the characters are drawn in silhouette it is impossible to determine whether the character with the hat is Black Hat or White Hat or some other character. In the title text the concept of hydroplane is mixed up with other concepts, none of which has anything to do with airplanes: Only three weeks prior to this comic, 1660: Captain Speaking was released only with a drawing of a plane in the air, where the captain eventually finds out that his plane is probably a Boeing. Planespotting was later a part of 1910: Sky Spotters . [Cueball and a man with a hat is seen in silhouette standing on the ground looking towards the sky. A fixed wing aircraft can be seen in the sky, also in silhouette.] Man with hat: What's That Airplane? Cueball:Oh, that's a Boeing Q404 twin-engine quad-band MIG-380 hybrid dual-wield Mk. IVII Turbodiesel 797 Hydroplane. [Caption below the panel:] I've always assumed I'm one of those people who knows a lot about planes, but I've never actually checked.

Laws of Physics

Laws of Physics

https://www.xkcd.com/1670

https://www.explainxkcd.com/wiki/index.php/1670:_Laws_of_Physics

[Black Hat is standing on a ladder, holding a heavy ball attached to a line from above. Cueball stands beneath, where if the ball swings it will smack him in his upper body.] Black Hat: Okay, hold still. Black Hat: And remember, if you really believe in the laws of physics, you won't flinch.

Black Hat , being Black Hat, is deliberately perverting a classic physics demonstration. In the normal version of the demonstration, a heavy ball on a pendulum is pulled to one side until it is almost, but not quite, touching the demonstrator or volunteer's nose or chin. When the ball is released at rest, it swings down and away, then back up to (almost) the same distance in the arc from where it started — but never (by the laws of physics) farther than where it started. As long as the demonstrator doesn't lean in or push the ball, it's impossible for it to strike them. It's a natural instinct to move away or protect yourself if you see a heavy object moving quickly toward you, but confidence in the physics of the demonstration means there is no reason to flinch. ( Sample video. ) In this comic, Cueball is not standing at the beginning edge of the ball's movement, but rather at the base of its swing, meaning that the ball will strike him at its maximum speed. Presumably, Black Hat is entirely aware of this and is hoping that Cueball's understanding of physics is insufficient to see through this prank. Judging from the "slack" of the rope, the ball should not hit Cueball in the head but could certainly hit him in a lower, and quite painful, place... The title text refers to the fact when someone flinches during the pendulum experiment, they are commonly accused of not having faith in the laws of physics. Randall is rebutting this argument by stating that, rather than not having faith in science, he is actually in tune with it, specifically the biological processes that led to the flinch reflex. His eyes and his flinch reflex have been calibrated through millions of years of evolution. To instantly dismiss his body's natural reaction when a heavy object comes quickly towards his face does not give enough credit to these mechanisms that successfully kept him (and every one of his ancestors) alive. In other words, while flinching may indicate doubt of the laws of physics, it may equally well indicate trust in the laws of biology. The idea of hitting someone else with a pendulum is also the topic of 755: Interdisciplinary and 2539: Flinch . [Black Hat is standing on a ladder, holding a heavy ball attached to a line from above. Cueball stands beneath, where if the ball swings it will smack him in his upper body.] Black Hat: Okay, hold still. Black Hat: And remember, if you really believe in the laws of physics, you won't flinch.

Arcane Bullshit

Arcane Bullshit

https://www.xkcd.com/1671

https://www.explainxkcd.com/wiki/index.php/1671:_Arcane_Bullshit

[A horizontal graph with arrows pointing left and right with labels. The line has three ticks one towards each end and one in the middle above which Cueball is drawn. Below each tick there is a caption. There is a caption at the top of the panel:] Willingness to wade through some 80's programmer's arcane bullshit: [Left end:] Low [Left tick:] Never learn to program [Above Cueball:] Me [Center tick:] Learn enough to break everything but not enough to fix it [Right end:] High [Right tick:] Spend all your time compiling kernels and never make anything

When fixing/improving an existing computer program, programmers sometimes need to read, understand, and improve old (and usually bad) code. The older a piece of code is, the less it tends to conform to modern programming practices, and the more likely it is to be "arcane bullshit" from the perspective of a 21st Century programmer. Randall seems to feel that willingness to deal with "arcane bullshit" is a " Catch 22 " that prevents 80s arcane bullshit from being fixed. Someone completely unwilling to deal with arcane bullshit would lack the patience to learn how to program. Someone extremely willing to wade through an 80s programmer's arcane bullshit is likely to " nerd snipe " themselves into fiddling with kernels (which are inherently arcane bullshit) instead of making useful code. Cueball is in the middle of the scale: smart and patient enough to make the 80s bullshit worse, but not smart and patient enough to know how to fix it. This comic could be a reference to changes in programming methodologies. As the first computer programs were written in the 40's and 50's they were prone to becoming "spaghetti code", where the flow of execution would jump from one part of the program to another using the JUMP which gives no state information. While this method of programming can work very quickly, it makes it difficult to predict program flow and can create interdependencies that are not obvious. In the BASIC language JUMP was called GOTO and the courses for new programmers argued that using GOTO in all but trivial cases was a very bad idea. On the other hand, old programmers argued that calculated GOTO was a sexy way of programming. To combat the problem computer scientists have relied on increasing the levels of abstraction and encapsulation, by developing structured programming , procedural programming , and OOP (object oriented programming) . In structured programming you break your program into well defined blocks of code with specified entry and exit points. By the use of a stack (a portion of memory dedicated to sequentially storing and retrieving contextual information and program state as blocks call other blocks, before returning), it is possible to call a block of code and then have that block of code return control (and any new information) to the point that called it after it has done what was requested. Very quickly it was decided to mark these blocks of code as functions or procedures, making it trivial for the compiler to know how to call and process the blocks, and make it easier for the user to edit them without having to keep track of the minutae of how they are handled. Languages that made this a focus include Pascal, Modula, and C. Structured and procedural programming were well entrenched in the '80s. Most systems programming was done in mid- or low-level languages, which improves performance by giving the knowledgable programmer explicit control of the data structures in the programs rather than shrouding it in abstraction. But because they are at a lower level the code requires many explicit steps to do seemingly easy things like draw a box on a screen, making it easy for a non-experienced programmer to introduce errors and harder to understand what needs to be happening (ultimately, the flipping of specific bits within the graphical RAM), compared to a high-level command to just "draw a box" with given qualities and have the system work out how exactly that needs to be done. Although the idea of OOP was around as early as the 1950s, it was not implemented in a widespread fashion until the 1990s. OOP encapsulates the data structures inside of functions, so rather than manipulate any variable directly you call the data structure and tell it to do something to (or with) its elements. This additional level of abstraction can make it a lot easier to work on varied data, if implemented with the correct handlers. It also can protect the program data from unexpected changes by other sections of the program, as most elements are restricted to being changed by the encapsulating code and transfer of information must be implemented in even higher levels of program management. Because code in the '80s was typically done at a much lower level, it can be hard for programmers used to having the language and libraries silently do much of the work for them. It also meant that programmers would often hard-code expectations into their source code such as the number of files that can be opened at once or the size of the operating system disk buffers. This means if you need the program to handle a larger file, you might need to recompile it after finding and changing all the places in the code that assume the smaller max file size. For graphical output, rather than direct access to a predictably constant configuration of video-RAM, now the extent of the graphics (e.g. size of the 'screen'-array, bit-depth of each pixel, even the endianness of the data) should be discovered as the program loads, or even dynamically configurable while the program is running; such as when the program's GUI window is resized by the user, changing the available 'virtual screen' canvas. As such, few people are willing to try to surpass the massive barrier to learning how to wrangle the very detailed old code. This group is on the left. To the right are people who have gotten so used to the tools and conventions of the '80s that they spend all of their time adjusting and recompiling the kernel of their computers to match their current needs, instead of actually creating new programs. In the center is Cueball, presumably representing Randall, who has learned enough to change how the code operates but not enough for his changes to be produce a working fix for whatever emerging issue he might be trying to solve. As programs age, they often lose support from the initial project head and die out, no longer supported on new computers. So, as the title text says, learning more coding from the '90s and after is necessary for also breaking everyone else's computers. This could also be a comment on hacking and the advent of the internet and the technologies behind that (TCP/IP, HTML, CSS, PHP...) being '90s/2000s. Computers in the '80s were typically stand alone, so what you are learning can only be applied to your machine. To break everyone else's you need to be in the position of (mis)understanding networking code. The title text might be a reference to various recently discovered security vulnerabilities in open-source software . In some cases, underskilled programmers have provided flawed code for critical infrastructure with very little review, resulting in global computer security disasters. Randall described some of these in 424: Security Holes (2008), 1353: Heartbleed and 1354: Heartbleed Explanation (2014). Other recent examples include Shellshock and vulnerabilities in the Linux kernel involving the perf and keyrings subsystems. [A horizontal graph with arrows pointing left and right with labels. The line has three ticks one towards each end and one in the middle above which Cueball is drawn. Below each tick there is a caption. There is a caption at the top of the panel:] Willingness to wade through some 80's programmer's arcane bullshit: [Left end:] Low [Left tick:] Never learn to program [Above Cueball:] Me [Center tick:] Learn enough to break everything but not enough to fix it [Right end:] High [Right tick:] Spend all your time compiling kernels and never make anything

Women on 20s

Women on 20s

https://www.xkcd.com/1672

https://www.explainxkcd.com/wiki/index.php/1672:_Women_on_20s

[Cueball is sitting at his laptop. Above him is the text he reads on the screen, then he speaks, and below that text is the list of women from his computer showing his three picks, each with a gray "drop-down menu" triangle to the right of the names. Below this is his final spoken line. At the top of the panel is a small frame breaking the top left border with a caption:] 2015 Website: Petition: Replace Andrew "Trail of Tears" Jackson with a woman on the $20 for the 100 th anniversary of women's suffrage in 2020. Cueball: Hey, good idea! Website: Vote for your three picks: 1 Harriet Tubman 2 Eleanor Roosevelt 3 Rachel Carson Cueball: Tubman for #1, definitely. [An executive from the department of treasury, with a wee bit of hair on his head, stands behind a lectern. On the front of the lectern the top part of the image inside the seal for the department of treasury is visible inside a circle, showing the scales and the tip of the triangular band beneath it. The rest of this image is hidden below the panel frame. There is text written above this image. At the top of the panel is a small frame breaking the top left border with a caption:] Soon... Treasury Executive: After a flood of public interest, the Treasury has decided to feature a woman on our money! Offscreen voice 1: Yay! Treasury Executive: She will replace Hamilton on the $10. Offscreen voice 1: Yay-- wait, what? Why not the $20? Offscreen voice 2: Are we mad at Hamilton? Text above the seal: Treasury [The executive with a hand on the lectern is seen from the side.] Treasury Executive: The $10 was scheduled for the next redesign by a board made up of- Offscreen voice 3: Can't you just do the $20 next? Treasury Executive: We will review the... Offscreen voice 3: *Sigh* Offscreen voice 4 (Steve): Put Martin Shkreli on the $5! Offscreen voice 5: Shut up, Steve. [The executive lifts both hands, the one over the lectern points a finger up. Again seen from the side. At the top of the panel is a small frame breaking the top left border with a caption:] Later in 2015... Treasury Executive: Wow, some musical came out, and now suddenly Hamilton has tons of fans. Offscreen voice 6: So do the $20 next. Problem solved! Treasury Executive: Maybe he and a woman can share the $10! Offscreen voice 6: Are you serious. [The executive, again with a hand on the lectern, is seen from the side. At the top of the panel is a small frame breaking the top left border with a caption:] 2016: Treasury Executive: We've decided to put Harriet Tubman on the $20. Offscreen voice 7: Perfect! Happy ending. Treasury Executive: -After we do the new $10. Offscreen voice 7: What? [The executive again from the front behind the lectern. On the front of the lectern only the text and the very top of the circle around the image can be seen.] Treasury Executive: We'll put a mural to women on the back of the $10. Hopefully that will tide you over until we get to the $20? Offscreen voice 8: Seriously? How is this so complicated? Just say "We're putting Harriet Tubman on the $20," then do it. Text above the seal: Treasury [The executive with hands down behind the lectern is seen from the side.] Treasury Executive: We'll do the $20 ASAP, but we can't change the- Offscreen voice 9: C'mon, your hands aren't tied here. You're the freaking Treasury. This is the one thing you're definitely in charge of. [The executive lifting a hand above the lectern is seen from the side.] Treasury Executive: Oh, and we're putting Andrew Jackson on the back. Three offscreen voices: What.

This comic portrays a series of press conferences with a US Treasury spokesperson (different from Cueball in the first panel as he has a bit of hair). The panels after the first summarize and ridicule the recent controversy over the upcoming redesign of US currency. The dialog between the US Treasury and reporters is paraphrased for comedic effect, but the events depicted are otherwise factual (including the punchline). American currency has only once had a woman as the primary portrait on paper currency ( Martha Washington was on the $1 Silver Certificate in the 1880's and 1890's), which is widely seen as a real problem. A large-scale petition was organized which advocated replacing Andrew Jackson on the $20 bill with a woman, to be chosen by public voting. The Trail of Tears is a reference to the forced re-locations of Native American peoples that Andrew Jackson conducted during his presidency. This is now seen as a human rights violation on a massive scale, and is presented as a reason why Andrew Jackson should not be honored on American currency. The timing of the release of this new bill with a woman was to be scheduled with the 100 year anniversary of Women's suffrage in 2020 and should thus preferably also be on the $20 bill. The voting process selected Harriet Tubman , a 19th century abolitionist and a major figure in the Underground Railroad system which freed American slaves . Cueball is seen to be clearly pleased and excited about this prospect in the first panel, where he votes for her first, among several other options. The list shows that Cueball chooses Tubman first representing the generic everyman and thus represents the about one in five that choose her first. But he may select up to three out of the fifteen selected candidates. Since Carson was not one of the options for the final round, where only four were selected (the other two were Rosa Parks , 3rd; and Wilma Mankiller , 4th), it is clear that Cueball was already voting in the primary ballot, where Roosevelt actually came in first. At this point, bureaucratic and political complications arise. The Treasury Department announces that, instead of replacing Andrew Jackson on the $20 bill, she would replace Alexander Hamilton on the $10 bill . The reason given is that the $10 bill was scheduled for redesign first. A reporter asks why they can't simply change the schedule, but doesn't get a clear answer. There is a suggestion from "Steve" to put Martin Shkreli on the $5 bill . Shkreli is a pharmaceutical executive and hedge fund manager who provoked controversy when he acquired the rights to an anti-parasite drug and raised the price by over 5000%, making it unaffordable for many people. He became known as "the most hated man in America". Naturally, Steve's suggestion receives short shrift, not least of which because it's a violation of Treasury policy and US law (as Shkreli is still alive). This may be the same Steve who messed up both 809: Los Alamos and 1532: New Horizons . The plan to replace Hamilton likely seemed like an uncontroversial decision at the time. He was not especially well known among the American public and few people had an emotional attachment to his legacy. However, this changed abruptly when a Broadway musical about his life came out and become massively popular. By total coincidence, this play creates a flood of interest in Hamilton right at the time the currency decisions are being made and makes replacing his portrait politically complicated. The spokesperson suggests putting both Hamilton and Tubman on the $10 bill, but the reporters are clearly unhappy with this solution, probably because it seems to dilute the recognition being given to Tubman. Finally, the spokesperson announces that they will put Tubman on the $20 bill, but their schedule demands that they do the $10 bill first. They decide to put a "mural to women" on the new $10 bill to try and contain the tension until the new $20 bill is released. The reporters say that the Treasury has total control over the release of currency, so the simpler solution is just to change the schedule, but they apparently ignore that suggestion. In the final panel, the spokesperson mentions that Jackson's portrait will still appear on the new $20 bill, seriously weakening the symbolism of replacing him and adding irony since Jackson was a slave owner. This is likely an effort to head off the complaints of traditionalists, but is seen here as an unfortunate attempt to avoid taking a real stand. In the title text Randall reiterates that this is a rare case in politics in which there's a clear and simple solution. The Treasury has the authority to redesign currency, and a petition to Congress could change the release schedule to fit their needs. That makes all the compromises and backtracking unnecessary: they could simply replace Jackson with Tubman and hypothetically release the new $20 bill whenever they choose. Randall appears frustrated with the artificial constraints that are holding back what should be a simple and straightforward process although he does acknowledge that it takes time to evaluate the security of a redesign's resistance to counterfeiting . The mention of the " weird pyramid eye thing " is a reference to the Eye of Providence , which is an old and somewhat arcane symbol that appears on the US $1 bill . Randall seems to be using this as an example of the outdated and frankly strange design of American currency, the implication that using that on all US dollar bills would constitute giving up on ever having a design relevant to the modern world. Also by replacing all portraits with this image, there would no longer be any gender controversy. As of 2020, progress on updating both the $10 and the $20 has stalled, with the Treasury stating that no new changes will be unveiled until 2026 . [Cueball is sitting at his laptop. Above him is the text he reads on the screen, then he speaks, and below that text is the list of women from his computer showing his three picks, each with a gray "drop-down menu" triangle to the right of the names. Below this is his final spoken line. At the top of the panel is a small frame breaking the top left border with a caption:] 2015 Website: Petition: Replace Andrew "Trail of Tears" Jackson with a woman on the $20 for the 100 th anniversary of women's suffrage in 2020. Cueball: Hey, good idea! Website: Vote for your three picks: 1 Harriet Tubman 2 Eleanor Roosevelt 3 Rachel Carson Cueball: Tubman for #1, definitely. [An executive from the department of treasury, with a wee bit of hair on his head, stands behind a lectern. On the front of the lectern the top part of the image inside the seal for the department of treasury is visible inside a circle, showing the scales and the tip of the triangular band beneath it. The rest of this image is hidden below the panel frame. There is text written above this image. At the top of the panel is a small frame breaking the top left border with a caption:] Soon... Treasury Executive: After a flood of public interest, the Treasury has decided to feature a woman on our money! Offscreen voice 1: Yay! Treasury Executive: She will replace Hamilton on the $10. Offscreen voice 1: Yay-- wait, what? Why not the $20? Offscreen voice 2: Are we mad at Hamilton? Text above the seal: Treasury [The executive with a hand on the lectern is seen from the side.] Treasury Executive: The $10 was scheduled for the next redesign by a board made up of- Offscreen voice 3: Can't you just do the $20 next? Treasury Executive: We will review the... Offscreen voice 3: *Sigh* Offscreen voice 4 (Steve): Put Martin Shkreli on the $5! Offscreen voice 5: Shut up, Steve. [The executive lifts both hands, the one over the lectern points a finger up. Again seen from the side. At the top of the panel is a small frame breaking the top left border with a caption:] Later in 2015... Treasury Executive: Wow, some musical came out, and now suddenly Hamilton has tons of fans. Offscreen voice 6: So do the $20 next. Problem solved! Treasury Executive: Maybe he and a woman can share the $10! Offscreen voice 6: Are you serious. [The executive, again with a hand on the lectern, is seen from the side. At the top of the panel is a small frame breaking the top left border with a caption:] 2016: Treasury Executive: We've decided to put Harriet Tubman on the $20. Offscreen voice 7: Perfect! Happy ending. Treasury Executive: -After we do the new $10. Offscreen voice 7: What? [The executive again from the front behind the lectern. On the front of the lectern only the text and the very top of the circle around the image can be seen.] Treasury Executive: We'll put a mural to women on the back of the $10. Hopefully that will tide you over until we get to the $20? Offscreen voice 8: Seriously? How is this so complicated? Just say "We're putting Harriet Tubman on the $20," then do it. Text above the seal: Treasury [The executive with hands down behind the lectern is seen from the side.] Treasury Executive: We'll do the $20 ASAP, but we can't change the- Offscreen voice 9: C'mon, your hands aren't tied here. You're the freaking Treasury. This is the one thing you're definitely in charge of. [The executive lifting a hand above the lectern is seen from the side.] Treasury Executive: Oh, and we're putting Andrew Jackson on the back. Three offscreen voices: What.

Timeline of Bicycle Design

Timeline of Bicycle Design

https://www.xkcd.com/1673

https://www.explainxkcd.com/wiki/index.php/1673:_Timeline_of_Bicycle_Design

[13 drawings 8 in the top and 5 in the bottom row of different and weird "bicycle" designs. Above them there is a heading, and below each bike a year is given. On the very last cycle there is a drinking bottle with a label.] Timeline of Bicycle Design [Ponytail hanging on to a bending rod that goes down to a single normal sized bike wheel. It looks like a unicycle with no seat. The rod is bending quite a lot so she looks like she is about to use the contraption as a pole vault] 1810 [Cueball is running after a device holding on to a rod bend in several places before reaching the ground at a very small wheel that then is connected with a shorter rod to a normal sized bike wheel.] 1825 [Two normal sized bike wheels connected with a single rod between them.] 1840 [Megan sits on a large saddle on top of a double sized bike wheel, she has some kind of handle bars to hold on to (or it could just be the saddle) and then a small rod goes down to a half size front wheel.] 1860 [A regular drawing of a Penny-farthing with very small back wheel (half the size of the front wheel on the 1860 bike) and very large front wheel (larger than the 1860 bike) and pedals in the middle of the front wheel. There are no visible handlebars.] 1875 [A huge wheel twice the size of the one on the Penny-farthing, and then a small wheel (like the small one on the Penny-farthing) hangs in a rod from the center of the giant wheel. The small wheel has a saddle attached, but it is not straight up.] 1880 [This is the largest bike. Not the largest drawings, but where the other have the characters in roughly the same size, this one has a small drawing of Cueball standing on top of the wheel holding on to some kind of handle bar. The wheel is about three times his height.] 1900 [Cueball sits in the "saddle" of a bike design that is similar to the Penny-farthing, but the saddle is more a rod, and the back wheel is on a rod going straight down from where the saddle ends. Also there are no pedals, so Cueball seems to be directly spinning the front wheel by hand.] 1915 [A symmetrical saddle sits on top of single bike wheel, as with a unicycle but with no pedals. There are (at least) six progressively smaller wheels in-line to the first, three to front and three to the rear, each new wheel approximately half the size of the one before. A possible fourth wheel, presumed to complete the set of medial stabilisers, can no longer be discerned from the rod that goes through the center of the larger wheels.] 1925 [Megan stands on top of a saddle that has four individual rods extending from it, each to a small wheel. One wheel is directly beneath her, one is behind her, one is the same distance in front, and one is farther out in front. Megan is pushing the bike with a long flexible rod resembling a pole vault.] 1940 [Cueball is running down a steep hill with his arms up, being chased by three normal-sized bike wheels.] 1955 [Megan sits on a bike contraption that seems to have a holder around her mid section rather than her sitting on a saddle. This holder goes to the back wheel below her, and there is actually a sprocket with a chain, although no clear pedals beneath her feet. She holds on to a very long handle bar, which connects with two long rods coming from the sprocket at the front end of the bike far ahead of Megan, below which is a wheel, to where the chain is actually going. Both wheels seem to be normal size.] 1980 [Another weird contraption of a bike with pedals on both normal sized wheels which have handlebars on the side pointing down towards the front. The saddle hangs in a swing, connected to a rod above it, which goes to the front of the bike and splits in two rods which connect to the center frame of the bike. In front of these there is a contraption resembling many styles of touring bike handlebars, which sits just above the front wheel. The two wheels are connected with a long rod between the center of the wheels and in the middle of this is the center part of the frame going up toward the handle. On the middle of this is a bottle with a label. Towards the back wheel there are two rods sticking out, one presumably a kickstand, the other possibly a parking brake.] 2016 Bottle: Milk

Randall created what is supposedly a 200 year history for bicycles with 13 designs ranging from 1810 to 2016. However, a cursory glance at each one shows that they are almost all fictitious, heavily flawed, and most don't even fit the definition of "bicycle". The main point of the comic is to show off these silly joke designs. The only model that both looks like a real model and fits the year is the 1875 model, which resembles the Penny-farthing . The Penny-farthing was popular in the 1870s until the Safety bicycle took over around 1880. The 1875 model appears to be missing handlebars, but it's worth noting that on the real bicycle, the handlebars were very small and close to the saddle, and may be too small to appear in the drawing. The 1860 model looks like the American Star Bicycle , but that bicycle was first invented in the 1880s. The 1900 model looks like one of Paul Scheerbart 's perpetual motion machines. Some of the other examples of "bikes" could, however, look like those in the image at the top of the Velocipede Wikipedia page. Several of the "bikes" are shown with a human — Ponytail is "riding" the pole-vaulting bike, Cueball appears in four designs, and Megan appears in three. These humans provide a sense of scale and, in some cases, a demonstration of how the bike might be operated. Cueball's appearance in the 1900 design shows how huge that bike is, appearing to dwarf the previous two models while continuing the short trend of ever-increasing size. Only two of the bikes have pedals (1875 and 2016) and another two have a sprocket with a chain (1900 and 1980). Seven designs include a seat for the rider — eight if you count the device holding Megan in the 1980 model. The 1925 model is reminiscent of a fractal ; Benoit Mandelbrot was born in October 1924. The 1880 model could be the result of an evolutionary algorithm trying to produce a bicycle. Some sub-optimal algorithms that have been given the task of creating a vehicle have been shown to misplace parts in ways that makes them completely useless and/or inaccessible — for example, placing a small wheel inside a much larger wheel. This comic (especially the 2016 bicycle) is possibly also a reference to The Science of Cycology , a cognitive psychology project run by Rebecca Lawson at the University of Liverpool, which asked study participants to draw a bicycle from memory. The error rate was high, supporting a hypothesis that humans over-estimate their ability to explain how things work. Gianluca Gimini ran a similar project, Velocipedia , in which he asked people to draw free-hand sketches of bicycles from memory, then later rendered some of the results as if they were real bikes. Also, the designs given for the years from 1825 to 1925 distinctly resemble designs that tend to evolve in the various challenge environments in the genetic evolution games BoxCar2D ( Flash Player ) or Genetic Cars 2 ( HTML5 ). The 1980 design looks strikingly similar to the South Park "wild whacky action bike". The title text refers to the scene labeled "1955" which depicts Cueball being chased by 3 bicycle wheels. Whatever caused the wheels to chase Cueball down a hill is left to the reader's imagination. It could be that the wheels have become sentient and are actively chasing Cueball, or it could be that the bicycle failed horribly and Cueball is running from the wreckage. The era this "bike design" is from (1955, which is in the 50s) would be hard to ride a bike in if it was the only available design. [13 drawings 8 in the top and 5 in the bottom row of different and weird "bicycle" designs. Above them there is a heading, and below each bike a year is given. On the very last cycle there is a drinking bottle with a label.] Timeline of Bicycle Design [Ponytail hanging on to a bending rod that goes down to a single normal sized bike wheel. It looks like a unicycle with no seat. The rod is bending quite a lot so she looks like she is about to use the contraption as a pole vault] 1810 [Cueball is running after a device holding on to a rod bend in several places before reaching the ground at a very small wheel that then is connected with a shorter rod to a normal sized bike wheel.] 1825 [Two normal sized bike wheels connected with a single rod between them.] 1840 [Megan sits on a large saddle on top of a double sized bike wheel, she has some kind of handle bars to hold on to (or it could just be the saddle) and then a small rod goes down to a half size front wheel.] 1860 [A regular drawing of a Penny-farthing with very small back wheel (half the size of the front wheel on the 1860 bike) and very large front wheel (larger than the 1860 bike) and pedals in the middle of the front wheel. There are no visible handlebars.] 1875 [A huge wheel twice the size of the one on the Penny-farthing, and then a small wheel (like the small one on the Penny-farthing) hangs in a rod from the center of the giant wheel. The small wheel has a saddle attached, but it is not straight up.] 1880 [This is the largest bike. Not the largest drawings, but where the other have the characters in roughly the same size, this one has a small drawing of Cueball standing on top of the wheel holding on to some kind of handle bar. The wheel is about three times his height.] 1900 [Cueball sits in the "saddle" of a bike design that is similar to the Penny-farthing, but the saddle is more a rod, and the back wheel is on a rod going straight down from where the saddle ends. Also there are no pedals, so Cueball seems to be directly spinning the front wheel by hand.] 1915 [A symmetrical saddle sits on top of single bike wheel, as with a unicycle but with no pedals. There are (at least) six progressively smaller wheels in-line to the first, three to front and three to the rear, each new wheel approximately half the size of the one before. A possible fourth wheel, presumed to complete the set of medial stabilisers, can no longer be discerned from the rod that goes through the center of the larger wheels.] 1925 [Megan stands on top of a saddle that has four individual rods extending from it, each to a small wheel. One wheel is directly beneath her, one is behind her, one is the same distance in front, and one is farther out in front. Megan is pushing the bike with a long flexible rod resembling a pole vault.] 1940 [Cueball is running down a steep hill with his arms up, being chased by three normal-sized bike wheels.] 1955 [Megan sits on a bike contraption that seems to have a holder around her mid section rather than her sitting on a saddle. This holder goes to the back wheel below her, and there is actually a sprocket with a chain, although no clear pedals beneath her feet. She holds on to a very long handle bar, which connects with two long rods coming from the sprocket at the front end of the bike far ahead of Megan, below which is a wheel, to where the chain is actually going. Both wheels seem to be normal size.] 1980 [Another weird contraption of a bike with pedals on both normal sized wheels which have handlebars on the side pointing down towards the front. The saddle hangs in a swing, connected to a rod above it, which goes to the front of the bike and splits in two rods which connect to the center frame of the bike. In front of these there is a contraption resembling many styles of touring bike handlebars, which sits just above the front wheel. The two wheels are connected with a long rod between the center of the wheels and in the middle of this is the center part of the frame going up toward the handle. On the middle of this is a bottle with a label. Towards the back wheel there are two rods sticking out, one presumably a kickstand, the other possibly a parking brake.] 2016 Bottle: Milk

Adult

Adult

https://www.xkcd.com/1674

https://www.explainxkcd.com/wiki/index.php/1674:_Adult

[Cueball is holding onto a shopping cart more than half filled with items looking quite similar. Above his head is a large thought bubble.] Cueball (thinking): Haha, look at me grocery shopping! I'm such an adult. [Cueball is standing, arms in his sides, in front of a sofa with a price tag. He is thinking again, this time the frame of the panel is the lower part of the thought bubble, as there is no frame around the text in the "bubble".] Cueball (thinking): Buying a sofa! Ooh, look how domestic I am! [Cueball is sitting in an office chair. at a desk, leaning in over it while writing something. The desk is filled with office items, and on the opposite side of the desk sits a man with a wisp of hair in another office chair. Cueball is thinking again with the text in a large thought bubble above their heads.] Cueball (thinking): Applying for a mortgage! As if I'm a real grown-up. [Megan is reading out loud from a piece of paper, while standing in front of a long table, where Hairbun, Hairy, and White Hat are sitting. White hat sits at the end of the table in an office chair.] Megan: ...And I, being of sound mind and body, am totally writing a will right now! Megan: Can you believe this?

In this comic, Cueball performs several mundane adult tasks, namely shopping for groceries, buying furniture, and applying for a mortgage. In each instance thought bubbles show his apparent surprise or amusement at the fact that he is behaving like an adult. In the last panel Megan is reading Cueball's will. Instead of containing standard language, it expresses Cueball's feelings at the fact that he was actually creating a will. This is such an adult thing to do, that Cueball's mind boggles and he cannot believe he is doing so. As is revealed in the title text, Megan reads this to his family because Cueball died early, but when he wrote it, he probably did not envision that it was needed any time soon, and thus also explains why he cannot believe he is writing a will already. Randall frequently addresses the issue of growing up and being expected to be an adult, despite still seeing oneself as a child in many ways. In this strip, Cueball finds himself performing tasks that he's used to thinking of as things that grown-ups have to worry about, from shopping for food to preparing for one's own death. In each case, he treats the situation as if he were a child suddenly finding himself taking on adult responsibility, which seems to be how he sees himself. Randall also frequently addresses the issue of finding oneself in adulthood, despite feeling unprepared and immature. In some, he points out that this can be freeing, because it allows us the power to redefine adulthood on our own terms (see 150: Grownups and 219: Blanket Fort ). In others (as in this case), he addresses the surprise that comes with realizing that adult responsibilities belong to you, and fear about his ability to handle them (see 441: Babies , 905: Homeownership , and 616: Lease ). In the title text we learn that the shopping cart is filled with AirHeads , a tangy, taffy-like, chewy candy, predominantly known for its sweet taste and texture. The title text thus suggests that Cueball still retains some more childish instincts, namely using the freedom of adulthood to indulge in AirHead candies, to fatal consequences, explaining why they already read out his will in front of his family in the last panel. It also suggests that the candy company would be quick to portray that death as "natural causes", to downplay the involvement of their product in someone's death. Randall has previously made a comic displaying what happened to him when he suddenly was able to freely make or buy the kind of food his parents would have limited his access to in 418: Stove Ownership , where it was bacon in the comic and Frosting (or icing) in the title text. [Cueball is holding onto a shopping cart more than half filled with items looking quite similar. Above his head is a large thought bubble.] Cueball (thinking): Haha, look at me grocery shopping! I'm such an adult. [Cueball is standing, arms in his sides, in front of a sofa with a price tag. He is thinking again, this time the frame of the panel is the lower part of the thought bubble, as there is no frame around the text in the "bubble".] Cueball (thinking): Buying a sofa! Ooh, look how domestic I am! [Cueball is sitting in an office chair. at a desk, leaning in over it while writing something. The desk is filled with office items, and on the opposite side of the desk sits a man with a wisp of hair in another office chair. Cueball is thinking again with the text in a large thought bubble above their heads.] Cueball (thinking): Applying for a mortgage! As if I'm a real grown-up. [Megan is reading out loud from a piece of paper, while standing in front of a long table, where Hairbun, Hairy, and White Hat are sitting. White hat sits at the end of the table in an office chair.] Megan: ...And I, being of sound mind and body, am totally writing a will right now! Megan: Can you believe this?

Message in a Bottle

Message in a Bottle

https://www.xkcd.com/1675

https://www.explainxkcd.com/wiki/index.php/1675:_Message_in_a_Bottle

[Cueball walks along a beach with six seagulls flying behind him over the sea. There is a small surf, and in the far distance, two mountains.] [Cueball stops and looks down at a bottle lying in the sand just outside the surf. A letter can be seen inside, and there seems to be a stopper at the top.] [A frameless panel shows Cueball (beach and sea not drawn) as he pulls out the letter from the bottle that he has now picked up.] [Cueball holds the bottle behind him in one hand and the letter up in front him with the other hand. The text on the letter is written above him in curvy letters, looking like those often used to depict the writing of a dying or seriously injured man:] Unsubscribe

Cueball experiences a moment of non sequitur while walking along a beach, when he finds a message inside a bottle saying "unsubscribe". If you're part of an Internet mailing list, it's a common experience to come across random posts by users who may not be very tech-savvy, saying "unsubscribe". This is their attempt to unsubscribe from the list, accidentally broadcast to every other person on that list instead of just to the mailing list admin (who is either a person or an automated program that manages the list). Another common modern experience is that "unsubscribe" links don't always work (perhaps intentionally, for spam e-mails). In desperation, someone has tried to send their "unsubscribe" request in a bottle, hoping in vain that it will have its intended effect. Instead, Cueball receives it. A darker interpretation of the message could indicate the sender is unhappy with the world or life in general and wishes to leave it. A " message in a bottle " is either a fun activity or an S.O.S. from someone stranded at sea, where one places a note in a bottle and throws it into the ocean. It then gets carried on ocean currents, possibly around the world to be picked up by some unknown other person at a point in the future. The title text extends the joke to another common technological faux pas. It further mixes the metaphor of a message in a bottle with an e-mail list. It states that when he hit "reply all" (this is an option in most email client programs, but obviously not an option when one receives a message in a bottle), it sent a message in a bottle to everyone to whom the original message was sent - in this case clogging the ocean with bottles. This mistake is often made when a person intends to send an email to just one recipient of a message that's been broadcast to a whole list of people, but they accidentally hit "reply all" instead of just "reply". In some cases, if the mailing list is sufficiently large, amplification effects can completely overwhelm mail servers (by analogy, "clogging the ocean"). For example, an employee may send a simple message like "does anyone speak Russian?" to the whole company address book. Several people are likely to reply using the "reply all" button by mistake, causing the whole company to receive the reply. Then, automatic "out of office" notifications and people complaining about the flood of emails will further worsen the situation. This strip was probably inspired by the recent news of the world's oldest message in a bottle having been found last year, after over 108 years of being at sea, thus setting a new Guinness World Record. [Cueball walks along a beach with six seagulls flying behind him over the sea. There is a small surf, and in the far distance, two mountains.] [Cueball stops and looks down at a bottle lying in the sand just outside the surf. A letter can be seen inside, and there seems to be a stopper at the top.] [A frameless panel shows Cueball (beach and sea not drawn) as he pulls out the letter from the bottle that he has now picked up.] [Cueball holds the bottle behind him in one hand and the letter up in front him with the other hand. The text on the letter is written above him in curvy letters, looking like those often used to depict the writing of a dying or seriously injured man:] Unsubscribe

Full-Width Justification

Full-Width Justification

https://www.xkcd.com/1676

https://www.explainxkcd.com/wiki/index.php/1676:_Full-Width_Justification

Strategies for full-width justification [Below the caption is a column with six boxes, each showing a different "strategy" for justification which is annotated beside it. Here the annotation is written at the top and the text below. The top and bottom of the text is cut of in the middle, but as it can be "read" this is written anyway. Only for hyphenation does an extra word appear at the end. In the last with snakes, a snake is drawn to cover the entire spaaace from the end of between to the right border.] Giving up their famous paper on the relationship between deindustrialization and the growth of Letter spacing their famous paper on the relationship b e t w e e n deindustrialization and the growth of Hyphenation their famous paper on the relationship between deindus- trialization and the growth of ecological Stretching their famous paper on the relationship between deindustrialization and the growth of Filler their famous paper on the relationship between crap like deindustrialization and the growth of Snakes their famous paper on the relationship between 🐍 [a snake filling the gap] deindustrialization and the growth of ...their famous paper on the relationship between [crap like]/[ 🐍 ] deindustrialization and the growth of [ecological]...

The comic refers to an irritating problem in laying out text to fit from margin to margin, the problem of justification , where you want multiple-line text to line up on the left side (common), the right side (less common), or both sides, which is commonly called full justification. This strip is dealing with how to make text fit such that it lines up on both sides while still looking good. Sometimes, as with a shorter word between two long words like "relationship between deindustrialization ," there's no universal good way to make the typography work. It is a difficult problem to make text look good and be easily legible especially in a narrow space, with the biggest issue being how to handle words that are too long to fit nicely. The comic shows several solutions to this problem, some realistic and others less so, but each partly or wholly unsatisfying. " Giving up " essentially means not attempting full justification for a particular line, which means it will not fit with the rest of the layout. " Letter spacing " involves an conspicuously large amount of whitespace between letters, suggesting a reading where each letter is a word until the reader recognizes what is intended. This method is in somewhat common use in newspaper and magazine layout, where it is generally known by the name "tracking" (distance between all letters) and "kerning" (distance between particular pairs of letters that fit together easily). However, letter spacing is unavailable for justification purposes in some languages (such as German), in which it is used for emphasis, as italics are in English. " Hyphenation " is confusing because it requires suspended recognition of the full word, confusing the eye into seeing, in the given case, the non-words "deindus" and "trialization". This creates difficulty in both pronouncing and parsing the word. Moreover, the decision of when and where to hyphenate is non-trivial, particularly for automated text layout; for example, breaking a word and leaving only two "orphaned" letters on the following line is generally considered an illegal hyphenation. Nevertheless, hyphenation is a very common means of handling extreme cases. The hyphenation option is most compact, yielding the extra word "ecological". " Stretching " appears visually unnatural and unfamiliar, and may present technical difficulties in rendering. Adding " filler " words is generally undesirable: in the worst case, the meaning may be unintentionally altered, or the tone might be rendered too informal, as in the given example, and even in the best case, the text becomes less concise and potentially more difficult to read. Automation is also difficult. However, filler words added by a human, especially the original author of the text, are the least visually conspicuous, and may be the most practical solution in some scenarios. Finally, adding a decorative image like " snakes " (but not necessarily snakes in particular) to fill the extra space is a justification practice of significant historical interest (it was particularly common for illuminated manuscripts in the medieval era and remained prominent until the invention of the printing press) but little modern relevance. There may be a particular absurdity to using a snake as it can be read as a word, such as "the relationship between snake deindustrialization" as would be done similar to a rebus . In modern text layout programs, some combination of the above strategies may be used to achieve the most visually consistent effect. For example, in one case, hyphenation might be the best option to split a very long word, while another line might be too long by only one or two letters, in which case the program could apply a very slight degree of extra letter spacing, too small for the average reader to notice. The title text suggests that in order to facilitate the "snakes" method of "solving" the problem, the Unicode Consortium , the organization in charge of the common text standard Unicode , should add "snake-building characters" (similar in concept to the existing Box Drawing block), to allow variable-length snake images to be used as filling. Currently, there are at least six snake characters in Unicode, not including at least ten more Egyptian hieroglyphs that represent specific snakes, some in specific combination with other hieroglyphs: [1] One of the hieroglyphs ( U+13192 EGYPTIAN HIEROGLYPH I009A ) is described in source documents as HORNED VIPER CRAWLING OUT OF ENCLOSURE, so it is literally a snake-building character. "Non-breaking" in the title text refers to a similar process as zero-width joiners and no-break HTML and CSS; the whole snake would shift down if it were too wide to fit on a given line. This suggestion would likely be rejected; the Unicode consortium is very specific about which characters are added [ citation needed ] , and always require a good reason [ citation needed ] before adding a character or set of characters to the standard. Strange decisions by the consortium have previously been referenced in 1253: Exoplanet Names , 1513: Code Quality , and 1525: Emojic 8 Ball . Within an hour or two of this comic being published, a thread on the subject started on the Unicode Consortium’s official Unicode Mailing List. As of two days later, it’s still running. Strategies for full-width justification [Below the caption is a column with six boxes, each showing a different "strategy" for justification which is annotated beside it. Here the annotation is written at the top and the text below. The top and bottom of the text is cut of in the middle, but as it can be "read" this is written anyway. Only for hyphenation does an extra word appear at the end. In the last with snakes, a snake is drawn to cover the entire spaaace from the end of between to the right border.] Giving up their famous paper on the relationship between deindustrialization and the growth of Letter spacing their famous paper on the relationship b e t w e e n deindustrialization and the growth of Hyphenation their famous paper on the relationship between deindus- trialization and the growth of ecological Stretching their famous paper on the relationship between deindustrialization and the growth of Filler their famous paper on the relationship between crap like deindustrialization and the growth of Snakes their famous paper on the relationship between 🐍 [a snake filling the gap] deindustrialization and the growth of ...their famous paper on the relationship between [crap like]/[ 🐍 ] deindustrialization and the growth of [ecological]...

Contrails

Contrails

https://www.xkcd.com/1677

https://www.explainxkcd.com/wiki/index.php/1677:_Contrails

[Cueball and a White Hat are walking. White Hat is looking up to the sky while Cueball, walking in front holds out one arm towards him.] White Hat: Lots of contrails today. Cueball: Oh, you must be from the UK. In American English it's "Chemtrail". [Caption below the panel:] My hobby: Spreading linguistic misinformation

Contrails (short for "condensation trails") are trails of vapor produced by aircraft exhaust, trailing the airplane. They are formed from water condensing on jet fuel exhaust particles, some impurities of which provide bases for ice crystals to accumulate on. Some can dissipate in minutes, but others can last for hours or even longer, depending on the temperature, relative humidity and wind conditions at that particular altitude. Long-lasting contrails is a sign of high relative humidity and may sometimes predict the formation of clouds and rain. The chemtrail conspiracy theory claims that contrails lasting unusually long are actually chemical or biological agents sprayed into the air for more nefarious purposes, although there is no evidence for the same. Here, White Hat notices that there are a lot of contrails in the air. Cueball (falsely) corrects him, saying that in American English , contrails are called chemtrails, which is incorrect. This is a comic in the My Hobby series. Some of these comics involve Cueball giving misleading information about pedantic terms, such as 1405: Meteor . Another of these comics, 966: Jet Fuel , even mentions chemtrails, saying that they are made of mind-control agents carried on board the planes that make them. Later they were again mentioned in 1803: Location Reviews . The title text includes a similar situation, implying that astronomy and astrology are synonymous, with astrology being the term used in British English. However, this is incorrect. Astronomy is the scientific study of things in outer space, like stars, planets, and galaxies, whereas astrology is a system that infers a person's personality and characteristics from those same things in outer space. Though both involve studying celestial objects, astrology is considered a pseudoscience rather than empirical science. The joke is that British English and American English use different terms to refer to the same object, and one can often learn new words for a simple thing. This, however is not the case in this comic; contrail and chemtrail do not refer to the same thing, the latter being only a conspiracy theory. This newfound hobby is developing to another hobby about spreading misinformation that was released less than two month after this: 1697: Intervocalic Fortition . [Cueball and a White Hat are walking. White Hat is looking up to the sky while Cueball, walking in front holds out one arm towards him.] White Hat: Lots of contrails today. Cueball: Oh, you must be from the UK. In American English it's "Chemtrail". [Caption below the panel:] My hobby: Spreading linguistic misinformation

Recent Searches

Recent Searches

https://www.xkcd.com/1678

https://www.explainxkcd.com/wiki/index.php/1678:_Recent_Searches

[Coloured and styled as the real logo:] GOOGLE [Google Search bar, with a drop down box with faded text, implying recent searches.] Google translate syntax highlighting Autodetect mixed bash zsh CPU temperature sensor limits GIF to XLS Clock speed jumper sample rate Clean reinstall keybinding Cron job to update crontab fsck Chrome extension Recursive font Regex matching valid EBNF Hardlinks Turing complete Opposite of safe mode Predictive touchpad Google docs from bootloader Hardware acceleration red channel only [Caption below the frame:] I have no idea why my computers are always broken.

People often find answers to computer problems by searching on Google , which attempts to guess your intended search term based on your location, language and the characters you've already typed, placing its suggestions in a drop-down box beneath the input area. If the search box is clicked on but nothing is typed, the drop-down box by default shows a list of your most recent searches. Here we see a list of search queries, each of which suggests the author is perversely misusing or overextending some computer technology. The overall impression is of someone technically sophisticated enough to shoot themselves in the foot, and who does not learn any larger lessons despite doing so repeatedly. The title text is another possible entry in this list. The caption implies that from Randall's perspective, every computer he uses seems to be broken; he doesn't seem to realise this is because he's the one using them, not because the computers actually start off broken. (For similar themes see also these comics: 349: Success , 1084: Server Problem , 1316: Inexplicable and 1586: Keyboard Problems ). ( Dear people from the future , if Google directed you here because it is the most popular result for a problem you are experiencing, this is not the page you were looking for). Google translate syntax highlighting Syntax highlighting can be used when editing source code to make the code more readable and easier to understand. It is not generally used for natural languages, but sentence diagrams of brief passages are used in language education. Google Translate is used to translate text from one natural language to another. It uses JavaScript mouseover() to highlight words as an aid in matching phrases in the source with their translations, but does not apply different highlighting dependent on syntax. Alternatively, this could imply that Randall is attempting to translate code from one programming language to another using Google Translate. Success would be unlikely, since the service is not intended for this [ citation needed ] , and syntactically valid output might further break the computer executing it. Two other possible interpretations of this phrase are that Randall wants to translate the phrase "syntax highlighting" to another language, or that he wants to perform syntax highlighting on the source code for Google Translate. Autodetect mixed bash zsh Bash and Zsh are two command line interfaces for Unix-like OSes. The way to execute commands is almost identical, making detecting a script that contains a mixed syntax nearly impossible. This was later referenced in 2510: Modern Tools . CPU temperature sensor limits The CPU's temperature sensors exist to tell you when your CPU is becoming dangerously overheated (normally because of a faulty fan or overclocking). Someone who searches for information about the limits of those sensors is presumably expecting to misuse their CPU. Probably also a reference to 1172: Workflow . GIF to XLS .GIF (Graphic Interchange Format) is a file extension used to store images and sequences of images to be displayed as an animation. .XLS is the file extension for Microsoft Excel spreadsheets. The joke is that the two file types are used for different purposes - it's quite normal for someone to want to convert between .GIF, .JPG, .PNG, .BMP files, as these are all image files; or between .XLS, .CSV, and .ODS files, as these all record tabulated information. However, for some reason Randall wants to convert an image file to a spreadsheet. (This is actually possible, because a digital image is essentially an array of colour and brightness values; it just wouldn't be particularly useful for most people. Here is a webpage with an online converter.) Matt Parker has done a stand up routine about converting these two file types. An alternate way to convert an image file, such as a .GIF file, into a text-based file like an .XLS file, is through optical character recognition (OCR). This is only effective if the image is a copy (i.e. a scan or reasonably clear photograph) of a document containing letters and words, and neither .GIF nor .XLS are file formats anyone would usually use in that case. Clock speed jumper sample rate A jumper is an intentional short circuit used for selecting options for an electronic circuit. They are usually used where it is not feasible to use programming (such as outputting a byte or word through a port) to alter the selection, such as before the processor even begins executing. A common example would be, on some motherboards, jumpers can be used to alter the clock speeds of various motherboard functions (such as the CPU or the front side bus). These jumpers should ordinarily be modified when the computer is off. However, this search is asking how often the motherboard checks the status of the clock speed jumpers, implying that they intend to change these jumpers while the computer is powered on, and often enough that the sample rate matters (change cpu speed several times a second, by moving jumpers on the motherboard.). That is, of course, a little silly. Clean reinstall keybinding This refers to keybinding, the practice of mapping (binding) a certain key to a certain function (e.g., pressing PRTSC will take a screenshot). Most keyboards do not output characters directly, but only codes for which keys have been pressed (or released). Keybindings translate the pressing of the "A" key on your keyboard into the letter "A" being sent to a program which is reading keyboard input. A "clean reinstall" of keybindings is something that would almost never be necessary - it means Randall has modified his default keybindings to such an extent that his leopard has become unusable (similar to 1284: Improved Keyboard ), necessitating a "clean reinstall" of the bindings. Alternatively, he might be doing clean reinstalls so often that he wants a keybinding to execute them with minimal loss of time. Cron job to update crontab Cron is a utility on most Unix-like OSes that allows you to schedule commands or scripts to be run periodically. These scheduled jobs are read from a crontab file. A job that updates the crontab (therefore creating new jobs, removing old ones or editing existing ones) is paramount to a job scheduler , and trying to use cron for such functionality could result in highly unstable functionality (although a crontab could be sensibly regenerated periodically by a set of machines from a master crontab file annotated with per-host directives). This is similar to self-modifying code . fsck Chrome extension This is a search for an interface to the Unix f ile s ystem che ck er fsck via third-party software added to Chrome. fsck is a program for checking your filesystem for corruption. Repairing a filesystem this way would be inadvisable. [ citation needed ] This might indicate confusion about the meaning of the term "online filesystem repair", in which "online" means "while the filesystem is in use" rather than "over the Internet". Alternatively, Randall might want to repair an installation of the operating system Chromium, in a manner less drastic than the factory reset preferred by Google. Recursive font An idiosyncratic mix of recursion and the font style cursive , referring especially to text handwritten in a flowing manner. PostScript (the language in which some fonts are written) is capable of recursion and PostScript Type 3 fonts are able to use the full language. This could create effects like fonts with complicated fractal borders and fill patterns - but the increase in processing time would contribute to seeming brokenness of the computer (or printer) rendering the font. A true recursive font would be a form of fractals ( example ). Regex matching valid EBNF EBNF refers to Extended Backus–Naur Form , which is used to define formal languages . EBNF specifies recursive patterns that are impossible for a regular expression (regex) to determine whether it is valid or not. There is some irony in using regex to test the validity of something which defines the validity of things like regex. Hardlinks Turing complete In some file systems, for example ext4 and NTFS , a single file may be referenced in multiple places in the file system. These filenames are termed "hard links" because the operating system automatically resolves them to the actual file. "Soft" or "symbolic" links are resolved indirectly via a pathname, which may reside anywhere. A file is considered deleted when the last hard link to it is unlinked; a soft link exists independently of its target. In fact, the target need not exist, in which case this is often called a dangling symbolic link. Turing completeness is the computational complexity required to simulate any computable function (given an infinite amount of memory). Recently there have been cases where unexpected mechanisms from card games to text parsers were proved to be Turing complete. Hardlinks being Turing complete would imply that creating and deleting hardlinks alone is enough to satisfy the requirements of Turing completeness. Opposite of safe mode Safe mode is a diagnostic mode in many operating systems and applications which allows the user to troubleshoot problems by disabling unnecessary functionality. The "opposite of safe mode" implies a "dangerous mode" where the purpose is to allow uselessly dangerous actions (in actuality this supposed dangerous mode is the default mode). A common example is the sudo command in Unix-like OSes, which grants the user system-level permissions. It's also possible that Randall sees Safe Mode so often that he sees regular mode as an unusual and unique state and needs help navigating back to it. Predictive touchpad Predictive text is a feature of many smartphone keyboards that predicts the most likely word the user wishes to type, and then gives the user the option to place the full word in the sentence immediately without having to finish typing it. A touchpad is a computer pointing device, similar to a computer mouse . The idea of a "predictive touchpad" seems absurd because, as opposed to typed words, there are not a limited number of swipe combinations that are possible on a touchpad. A "predictive touchpad" implies that a computer could predict where the user was going to move the mouse or click, which in this case would seem to defeat the purpose of a user input device. [ citation needed ] . Interestingly, a version of Linux had a predictive cursor option, where the cursor jumped to the nearest button (like window close) when it moved near to but didn't quite reach that button. Google docs from bootloader A bootloader is a very small program that is usually the very first thing to execute when a computer boots up. It is used mainly for loading the operating system into memory. Such a program by itself would not be capable of directly running something as complex as Google Docs . Hardware acceleration red channel only Hardware acceleration means that certain calculations are not performed by the computer's CPU but by a "specialized" processor, e.g. a GPU which is part of the graphics adapter. This speeds up output, especially if complex 3D calculations are required, and reduces CPU load. To use this function only on a single color channel seems pretty useless, but one may want to troubleshoot a program that displays only red when hardware acceleration is enabled. While graphics cards are most commonly used with three or four channels (red, green, blue, and sometimes alpha), they do support two-channel or single-channel images. An 8-bit single-channel image would use the format ' R8 ', which is indeed 'red channel only'. This type of image could be used to store monochrome images or non-image data. autoexec code posted by verified twitter users. ( Title text ) The term "autoexec" refers to code that runs automatically, usually during boot, and derives from one of three boot-time files for MS-DOS : AUTOEXEC.BAT, CONFIG.SYS and COMMAND.COM. AUTOEXEC.BAT would typically contain commands for customizing the command prompt, loading additional drivers, and/or automatically launching a program. Automatically executing code from the Internet is generally a terrible idea, because it could be written by someone with malicious intent and harm your computer. The joke here is that the code would only be executed if written by someone who has been "verified" on Twitter. Twitter's verification service only serves to show that a user is who they claim to be, not whether or not their code can be trusted, so this would provide little protection. Usually, Twitter verification is used by celebrities so they can be distinguished from people claiming to be them. The line implies that Randall is only interested in running code posted by celebrities. Most code downloaded from authentic sources (such as Microsoft and official Linux distributions) is verified by a cryptographic signature from a true trusted source, authenticating the origin of the software. These may include software updates that run automatically in the background. The joke here is that the term "verified" means very different things between Twitter users and software distribution. [Coloured and styled as the real logo:] GOOGLE [Google Search bar, with a drop down box with faded text, implying recent searches.] Google translate syntax highlighting Autodetect mixed bash zsh CPU temperature sensor limits GIF to XLS Clock speed jumper sample rate Clean reinstall keybinding Cron job to update crontab fsck Chrome extension Recursive font Regex matching valid EBNF Hardlinks Turing complete Opposite of safe mode Predictive touchpad Google docs from bootloader Hardware acceleration red channel only [Caption below the frame:] I have no idea why my computers are always broken.

Substitutions 3

Substitutions 3

https://www.xkcd.com/1679

https://www.explainxkcd.com/wiki/index.php/1679:_Substitutions_3

[Caption above the panel:] Even More Substitutions That make reading the news more fun [A table of words/sentences on the left that change in to those on the left. Between each set of words there is an arrow pointing from right.] Gaffe ➜ Magic spell Ancient ➜ Haunted Star-Studded ➜ Blood-soaked Remains to be seen ➜ Will never be known Silver bullet ➜ Way to kill werewolves Subway system ➜ Tunnels I found Surprising ➜ Surprising (but not to me) War of words ➜ Interplanetary war Tension ➜ Sexual tension Cautiously optimistic ➜ Delusional Doctor Who ➜ The Big Bang Theory Win votes ➜ Find Pokémon Behind the headlines ➜ Beyond the grave Email \ Facebook Post ➜ Poem Tweet / Facebook CEO ➜ This guy Latest ➜ Final Disrupt ➜ Destroy Meeting ➜ Ménage à trois Scientists ➜ Channing Tatum and his friends You won't believe ➜ I'm really sad about

This is the third comic in the Substitution series where Randall has suggested substitutions that will make reading the news more fun. This time it will be even more fun! But there have been several comics using substitutions both before and after these ones. The series as of 2016: The title text in original form would be "Scientists explore ancient city", which most would consider a fairly bland headline. Two days before this comic came out, there was news that a potential ancient Mayan city had been found by a 15 year old boy through satellite imagery, which may be what Randall was referencing. The Mayan city has now been proven inexistent. Imagining Channing Tatum and his "friends", and pretending that the city is haunted, provides a much more dramatic setting mirroring many episodes (and later films) of Scooby Doo featuring a gang of friends (Mysteries, Inc.). [Caption above the panel:] Even More Substitutions That make reading the news more fun [A table of words/sentences on the left that change in to those on the left. Between each set of words there is an arrow pointing from right.] Gaffe ➜ Magic spell Ancient ➜ Haunted Star-Studded ➜ Blood-soaked Remains to be seen ➜ Will never be known Silver bullet ➜ Way to kill werewolves Subway system ➜ Tunnels I found Surprising ➜ Surprising (but not to me) War of words ➜ Interplanetary war Tension ➜ Sexual tension Cautiously optimistic ➜ Delusional Doctor Who ➜ The Big Bang Theory Win votes ➜ Find Pokémon Behind the headlines ➜ Beyond the grave Email \ Facebook Post ➜ Poem Tweet / Facebook CEO ➜ This guy Latest ➜ Final Disrupt ➜ Destroy Meeting ➜ Ménage à trois Scientists ➜ Channing Tatum and his friends You won't believe ➜ I'm really sad about

Black Hole

Black Hole

https://www.xkcd.com/1680

https://www.explainxkcd.com/wiki/index.php/1680:_Black_Hole

[Cueball is standing near a coffee table as Black Hat approaches. They are presumably in Black Hat's living room. The coffee table has a miniature black hole on top of it, resting on a small pedestal.] Cueball: Why do you have a miniature black hole on your coffee table? Black Hat: It really brings the room together.

Cueball is curious as to why Black Hat has a miniature black hole on his table; Black Hat responds that it "really brings the room together", making a pun on both the black hole aesthetically completing the look of the room as well as it literally "bringing the room together" through its gravitational pull. Evidently the black hole is massive enough to bring the room together optically into visible Einstein rings by gravitational lensing . The title text makes a cultural reference to a well-known song lyric from the 2003 song " Milkshake " by Kelis , where the singer brags of her milkshake being so popular that it "brings all the boys to the yard" (what "milkshake" is a metaphor for has never been specified). But in this case, since gravity does not discriminate between which things it pulls, it brings "the boys, and everything else" to Black Hat's yard - and unlike with the milkshake, not by choice. If it wasn't for the house walls (which somehow resist collapsing into the black hole), they wouldn't remain in the yard but would come into the room with the black hole, and then into the black hole itself. As depicted, the black hole is inconsistent with several aspects of physics: [Cueball is standing near a coffee table as Black Hat approaches. They are presumably in Black Hat's living room. The coffee table has a miniature black hole on top of it, resting on a small pedestal.] Cueball: Why do you have a miniature black hole on your coffee table? Black Hat: It really brings the room together.

Laser Products

Laser Products

https://www.xkcd.com/1681

https://www.explainxkcd.com/wiki/index.php/1681:_Laser_Products

[Heading above the table:] Online Reviews of Laser Products [A three by three table with one word to the far left, from which three lines split out and goes to three words just left of each of the three rows. Above each column is three other words. Below in the table are nine reviews with star rating on a five star scale. The actual rating is indicated with black stars and also use half filled stars in the rating system. The ratings are written in the table in square brackets.] ...surgery ...removal ...printer Laser eye... [4 1/2 stars] "I don't need glasses anymore!" [1/2 star] "Aaaaaaa! Misread the description! Aaaaaaaaaaaa!!" [1 star] "Eww." jet... [1 1/2 stars] "Too nervous to try it." [2 1/2 stars] "Effective, but the FAA got really mad." [4 stars] "Prints great!" hair... [2 1/2 stars] "Confusing term for haircut. Burning smell." [4 stars] "Great results!" [1/2 star] "Disgusting, won't turn off, jams constantly."

This comic takes three laser-based technologies - laser eye surgery, laserjet printers, and laser hair removal - and conflates them, with humorous results. These are illustrated through reviews by users of the resulting combinations. For the original combinations, the reviews are highly positive. For the new combinations, most are negative, because most of these new "technologies" are ill-conceived and possibly harmful. Laser eye surgery gets a positive review, since it has successfully corrected the reviewer's vision, so that they no longer require glasses. There are a range of laser eye surgeries to correct near- and far-sightedness, as well as various other conditions. LASIK , one of the more common laser eye surgeries, works by using lasers to cut open the cornea and ablate a small amount of the lens. Laser eye removal would be very painful, and thus the review is negative, stating that the reviewer had read the description incorrectly, likely believing it to be one of the real combinations on the chart. The screams of pain expressed in the review have the humorous implication that the review is being typed directly after the ill-advised procedure, though this may just be an after-the-fact expression of the reviewer's feelings. If they produced the review without aid, this would probably have been made more difficult as a result of the surgery. At least in animal surgery, however, laser eye removal does exist . Laser eye printer refers to printing on (or possibly of ) an eyeball, which only prompts a disgusted "Eww" response. Both probably can find their applications, either in adding images onto ones eyes or creating artificial eyes for implantation, but would probably be quite disgusting to operate for many people. Laser jet surgery could be performing maintenance on a jet with lasers, which would be potentially dangerous and error-prone [ citation needed ] . Alternatively, it could mean laser surgery done on a human from a jet aircraft, using a laser mounted to it. The human being operated on could be aboard that aircraft, on another aircraft, or on land: in any case, it does not sound like a safe approach. Another interpretation is that it could refer to surgery using a jet made of lasers, which is even worse, as it would probably cause the entire body to be disintegrated. [ citation needed ] Yet another interpretation is that the procedure would implant parts of a jet into one's body. The statement's ambiguity may contribute the reviewer's concern, or the reviewer could be nervous over the fact that it would be a very difficult and delicate procedure and trying it could easily go horribly wrong. Laser jet removal appears to be the destruction of jets with lasers, which apparently works, but angered the Federal Aviation Administration, and probably resulted in legal consequences for the reviewer. This could be a reference to the real FAA concern of the many incidents of people using laser pointers against aircraft. "Laser Jet Removal" actually exists as a military weapon system, though it's primarily meant to be used against jet missiles , rather than jet planes. LaserJet printer is a popular line of Hewlett Packard laser printers . Laser printing is a technology which uses a laser to electrically charge a drum so that it collects ink in the form of the image to be printed, before transferring it to paper. The printer seems to work well for the reviewer, as it has been given a positive review. Laser hair surgery turns out to be a fancy name for cutting hair with a laser -- an overengineered, and potentially dangerous, technique for achieving the same results that you could with clippers and scissors. It is rated neutrally, since it did the job, but the reviewer found the name confusing and they disliked the smell of burning hair. Laser hair removal is the process of destroying hair follicles with bursts of laser light to prevent the growth of unwanted hair. This appears to have been effective for the reviewer. Laser hair printer appears to be a bizarre printer that uses hair in place of paper, or perhaps as the construction material for a 3D printer . Unsurprisingly [ citation needed ] , this just creates disgusting messes of hair and keeps jamming the printer, resulting in a negative review. The title text extends this joke, giving some common printer error messages amended for the hair printer. A paper jam is when paper gets stuck in the workings of the printer, usually because it was creased, or more than one sheet fed in at once; in the hair printer this becomes a hair jam. An inkjet printer requires replaceable ink cartridges, and when the ink is used up this will usually result in an ink cartridge running low error; the hair printer appears to require cartridges of hair conditioner . As an additional twist, it uses color-safe conditioner, a product intended to prevent the washing out of dye from the users hair; here, it presumably protects the colour of the printed image or item. Legal and Letter are paper sizes used in North America; apparently, the same terms are used for standard supplies of hair for the hair printer. Laser eye removal has been mentioned before, see the lower right part of the 1619: Watson Medical Algorithm chart. [Heading above the table:] Online Reviews of Laser Products [A three by three table with one word to the far left, from which three lines split out and goes to three words just left of each of the three rows. Above each column is three other words. Below in the table are nine reviews with star rating on a five star scale. The actual rating is indicated with black stars and also use half filled stars in the rating system. The ratings are written in the table in square brackets.] ...surgery ...removal ...printer Laser eye... [4 1/2 stars] "I don't need glasses anymore!" [1/2 star] "Aaaaaaa! Misread the description! Aaaaaaaaaaaa!!" [1 star] "Eww." jet... [1 1/2 stars] "Too nervous to try it." [2 1/2 stars] "Effective, but the FAA got really mad." [4 stars] "Prints great!" hair... [2 1/2 stars] "Confusing term for haircut. Burning smell." [4 stars] "Great results!" [1/2 star] "Disgusting, won't turn off, jams constantly."

Bun

Bun

https://www.xkcd.com/1682

https://www.explainxkcd.com/wiki/index.php/1682:_Bun

[Ponytail is a teacher and she holds a pointer to a picture of a rabbit on a board behind her.] Ponytail: Good morning class! Today, we will be learning about the bun. [Two rabbits are shown, one slightly smaller, and a greater than symbol indicates that the smaller one is "greater than" the larger one. Ponytail is talking off panel to the left.] Ponytail (off panel): Buns have a hierarchy. Ponytail (off panel): A bun's rank is determined by its size. Smaller buns are higher-ranking. [Two normal sized rabbits are sitting left and right of a very small rabbit. The smaller rabbit appears to give off a radiant light indicated with gray and white alternating rays going through the image. It is indicated that it shines on the larger rabbits as they are gray on the side turned away from the smaller rabbit and white on the front turned towards it. Ponytail narrates above the frame of this half sized panel:] Ponytail (narrating): Most buns you see are relatively low-ranking. Ponytail (narrating): But this time of year, a lucky few may catch a glimpse of a king bun . [A student represented by Megan is sitting at a desk with a few books on it, pencil in hand.] Megan: OK, hang on. Megan: We're talking about rabbits and hares, right? Lagomorphs? [Ponytail is holding her finger up on her left hand, and is holding her pointer at her side with the other. Students reply to her off panel to the right.] Ponytail: Informally, yes. But in this course, we use the scientific term, "bun". Student #1 (off-panel): Are we sure this is the right room for introductory mammalogy? Student #2 (off-panel): I'll check online. Student #3 (off-panel): Shh! Show respect! We look upon the image of a king!

In this comic, Ponytail is teaching a class about an animal referred to as a "bun". The word "bun" is short for bunny , which is in turn an informal term used for a rabbit . The comic depicts a childish response to seeing a cute animal, but coming from an adult. The humor in the comic comes from a tone of absurdity in a classroom situation where lectures are expected to be serious. The lecture opens with the statement that smaller buns are superior in rank, which is plainly false. [ citation needed ] Instead, the teacher clearly thinks that smaller bunnies are just cuter. She mentions that "king buns" may be seen around this time of year, which refers to rabbit kittens being born in the spring. Kittens would be smaller and cuter than any other rabbits because of their age. There is no mention of a "queen bun", but the gender of the kitten can be difficult to determine without a close examination. A prime example of a king bun can be seen here . Megan , who attends this biology class, expected to learn about rabbits and hares which are both lagomorphs , a mammalian order that also includes the pikas . Megan thus clearly has the correct understanding of what a "bun" is. Ponytail then claims that the word bun is the scientific term, and states that rabbit, hare, and lagomorph are informal ways to describe these animals, again being completely wrong as in reality bun is the most contracted and informal name for a rabbit. Two students are then legitimately doubting that they're in the correct class and decide to check online (either the crude theories that Ponytail expressed, or their course schedule). A third student however appears to believe the lecturer uncritically, reminding the fellow students that they're looking upon the image of a king (i.e. a cute bunny). The title text refers to photographing a rabbit and, for example, posting it on social media - something which would typically be done today if someone sees a cute rabbit in the wild. If the poster had failed to photograph the rabbit before it ran away, they may typically post a message saying something like "I saw a really cute bunny today!" with an emoji depiction of a rabbit (probably 🐇 or 🐰 ). This is especially common in the area where Randall lives, as the urban rabbit population in the Cambridge/Somerville area has exploded, putting a large human population with relatively little previous experience with rabbit-sightings suddenly in the position of encountering them very frequently. [ citation needed ] Emoji have become a recurrent theme on xkcd. Ponytail tells that buns have a hierarchy in which the smaller the bun, the higher its ranking is - a rank-size distribution. A "king bun" can be seen as an instance of the king effect, the phenomenon where the top one or two members of a ranked set show up as outliers. An interesting linguistic note is that in several languages (including Czech and Polish), the word for rabbit literally means "little king". [Ponytail is a teacher and she holds a pointer to a picture of a rabbit on a board behind her.] Ponytail: Good morning class! Today, we will be learning about the bun. [Two rabbits are shown, one slightly smaller, and a greater than symbol indicates that the smaller one is "greater than" the larger one. Ponytail is talking off panel to the left.] Ponytail (off panel): Buns have a hierarchy. Ponytail (off panel): A bun's rank is determined by its size. Smaller buns are higher-ranking. [Two normal sized rabbits are sitting left and right of a very small rabbit. The smaller rabbit appears to give off a radiant light indicated with gray and white alternating rays going through the image. It is indicated that it shines on the larger rabbits as they are gray on the side turned away from the smaller rabbit and white on the front turned towards it. Ponytail narrates above the frame of this half sized panel:] Ponytail (narrating): Most buns you see are relatively low-ranking. Ponytail (narrating): But this time of year, a lucky few may catch a glimpse of a king bun . [A student represented by Megan is sitting at a desk with a few books on it, pencil in hand.] Megan: OK, hang on. Megan: We're talking about rabbits and hares, right? Lagomorphs? [Ponytail is holding her finger up on her left hand, and is holding her pointer at her side with the other. Students reply to her off panel to the right.] Ponytail: Informally, yes. But in this course, we use the scientific term, "bun". Student #1 (off-panel): Are we sure this is the right room for introductory mammalogy? Student #2 (off-panel): I'll check online. Student #3 (off-panel): Shh! Show respect! We look upon the image of a king!

Digital Data

Digital Data

https://www.xkcd.com/1683

https://www.explainxkcd.com/wiki/index.php/1683:_Digital_Data

[Cueball and a White Hat are walking, Cueball holds both hands in front of him palms up.] Cueball: The great thing about digital data is that it never degrades. [They walk on in the next panel which shows jpeg compression artifacts, as if the image had been converted from png format to a lossy jpeg format.] Cueball: Hard drives fail, of course, but their bits can be copied forever without loss. [They continue walking in the third panel which is now clearly pixelated, the white is slightly discolored, and it contains part of the interface of some program, probably supposed to be a screen shot from a smartphone. At the bottom there are three blue buttons and one gray. the first is a blue "<" indicating back in a browser. Then a grayed out ">" that is not active. And then three more standard buttons in blue to the right of those two. The interface matches that of an iPhone running Safari in iOS 9 (or other versions with the same Safari UI (probably iOS 7-9))] Cueball: Film degrades, paint cracks, but a copy of a century-old data file is identical to the original. [Still walking, now Cueball holds out both arms to the sides, and finally White Hat replies. This panel is heavily pixelated and discolored and has a distorted aspect ratio. It contains a clear watermark of 9GAG (although difficult to read all letters in the end of the first word), even more 'frame' elements, and text above the image at the bottom (where the last letter is obscured by the frame of the image). There is also an internet address at the bottom left, but it is not readable except for the .tumblr.com ending. In this panel it is clear that it is a screen shot from a smart phone. The frame around the image obscure the very top of Cueball's text and the half of the last letter in White Hat's reply.] Cueball: If humanity has a permanent record, we are the first generation in it. White Hat: Amazing Watermark: Screenshotpro 2 Watermark: ~Unregistered~ Top border: Verizon LTE 4:45 PM Bottom text [slightly cut off]: 9GAG Internet address at the bottom [nearly unintelligible]: [ama].tumblr.com

Digital information has the potential to be copied such that the copy is 100% identical to the original. While physical media themselves (such as books, or hard drives) and information stored by analog means may degrade as the universe continues, digital information as expressed by specific values, such as combinations of binary zeros and ones, does not decay over time and can be copied indefinitely with no changes. However, in this comic, Randall points out that while digital information itself doesn't need to degrade, things that are on the Internet are often degraded through copying when the copy is not a 1:1 copy or changes are deliberately introduced. In addition, as technology advances, the method to save or call the information changes and the medium to view it changes, occasionally causing misinterpreted information. (This is also demonstrated with the title text.) As the frames continue, they gain the appearance of images which have been screenshotted repeatedly, with a resulting loss of quality due to compression of the original resolution and JPEG artifacting . (The JPEG format is intended for representing photorealistic grayscale or color images; when misused for line drawings, such as comic strips, any compression artifacts become particularly noticeable, as the background is normally of completely uniform color.) In the last frame, this is taken to an extreme, as the frame appears to have been very sloppily screenshotted off of at least two different smartphones (not the same device that uses the bottom frame in the third panel as the top border in panel four), and the final image is covered both with a watermark from an unregistered screenshot program, as well as references to at least two different web sites: 9GAG (bottom right image) and Tumblr in the web address bottom left. 9GAG is an online platform and social media website where users upload and share content of their own, or of other networks. It is often accused of rehosting other sites' funny content without attribution and adding their own watermark to the image or video. As an easter egg, the high-resolution (pixel-doubled) version of the comic is merely the comic resized to 50% and then to 400%, making it an image of poorer quality rather than a higher resolution image as for other comics, demonstrating how repeated image scaling can also introduce artifacts into images. The title text is seemingly addressed to a reader in the future who will only be able to access xkcd through a digital archive . Digital information might not degrade with time, but it can't be properly displayed without knowledge of the encoding. As new encodings and file formats get developed and old ones abandoned, the webpage format of the comic might not be available in the future, when users would need special archives to view content from today's world. The title text contains seemingly garbage characters , which typically result from data being interpreted according to a character encoding different from the one used to encode it. In this case, the characters are the result of encoding the string “If you can read this, congratulations—the archive you’re using still knows about the mouseover text”! using UTF-8 (which represents non- ASCII Unicode characters as multibyte sequences) and then interpreting the resulting bytes as the still commonly used Windows-1252 encoding (which uses only one byte per character, but utilizes the non-ASCII codepoints for a limited selection of extra letters and symbols such as "â" or "€"). This shows that degradation of digital data through conversions isn't restricted to images. Furthermore, as screen navigation moves away from the mouse toward touch, voice recognition, and modes still to be implemented, mouseover text will itself become archaic. [Cueball and a White Hat are walking, Cueball holds both hands in front of him palms up.] Cueball: The great thing about digital data is that it never degrades. [They walk on in the next panel which shows jpeg compression artifacts, as if the image had been converted from png format to a lossy jpeg format.] Cueball: Hard drives fail, of course, but their bits can be copied forever without loss. [They continue walking in the third panel which is now clearly pixelated, the white is slightly discolored, and it contains part of the interface of some program, probably supposed to be a screen shot from a smartphone. At the bottom there are three blue buttons and one gray. the first is a blue "<" indicating back in a browser. Then a grayed out ">" that is not active. And then three more standard buttons in blue to the right of those two. The interface matches that of an iPhone running Safari in iOS 9 (or other versions with the same Safari UI (probably iOS 7-9))] Cueball: Film degrades, paint cracks, but a copy of a century-old data file is identical to the original. [Still walking, now Cueball holds out both arms to the sides, and finally White Hat replies. This panel is heavily pixelated and discolored and has a distorted aspect ratio. It contains a clear watermark of 9GAG (although difficult to read all letters in the end of the first word), even more 'frame' elements, and text above the image at the bottom (where the last letter is obscured by the frame of the image). There is also an internet address at the bottom left, but it is not readable except for the .tumblr.com ending. In this panel it is clear that it is a screen shot from a smart phone. The frame around the image obscure the very top of Cueball's text and the half of the last letter in White Hat's reply.] Cueball: If humanity has a permanent record, we are the first generation in it. White Hat: Amazing Watermark: Screenshotpro 2 Watermark: ~Unregistered~ Top border: Verizon LTE 4:45 PM Bottom text [slightly cut off]: 9GAG Internet address at the bottom [nearly unintelligible]: [ama].tumblr.com

Rainbow

Rainbow

https://www.xkcd.com/1684

https://www.explainxkcd.com/wiki/index.php/1684:_Rainbow

[Cueball looks up on a rainbow band going through the top right corner of the panel. A black blob in the bottom of the panel right of Cueball with white text inside shows the reply from God to the questions. The blobs continue through the rest of the comic.] Cueball: Wow, God- What's that band of color? God: A rainbow . God: It is a sign of my promise that I will never again flood the Earth. [A frameless panel.] Cueball: Oh, good! Hey, what about that second bow above the first one? God: Oh, uh, sign of my promise not to set the earth on fire. God: Sorry for doing that a while back. [Cueball points left.] Cueball: What about that third faint bow near the sun? God: My promise to never again destroy Earth's ecosystem by making raccoons immortal. [Cueball points even higher up towards left.] Cueball: And the little rainbow clouds on either side of- God: Look, I said I'm sorry. Can we just drop it?

In this comic, the patriarch Noah from the Abrahamic religions , represented by Cueball , talks to God after the biblical flood . He asks what the coloured band across the sky is, and God tells him it is a rainbow . According to the Book of Genesis, God placed a rainbow in the sky, giving it significance for the first time, as a promise to humanity that he would never again make a flood to cleanse the world of sin ( Genesis 9:2–17 ). A rainbow is an optical phenomenon caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky, one of many light phenomena caused by sunlight and precipitation. Then Noah notices a double rainbow outside the original promise rainbow . Secondary rainbows are caused by double reflection of sunlight inside the raindrops. When asked about this God seems to falter, but recovers and claims he made it to show that he will never again set the Earth on fire, an event which apparently happened long ago and for which God apologizes. This may refer to the early Earth being a liquid ball of molten rock (the Hadean period ), or later global fire catastrophes caused by asteroid impacts and volcanic eruptions. That God promises to never again burn the earth goes against the idea of Armageddon where everything will be destroyed in fire etc. Noah begins to notice some other optical phenomena as he next spots a bow near the sun. God promptly claims 'that' bow is a promise to never again make raccoons immortal as it destroyed the Earth's ecosystem . Although today these animals can be a pest, see 1565: Back Seat , they are luckily not immortal. [ citation needed ] Randall is likely referring to an unkillable form of immortality rather than biological immortality , as, while that would likely cause some issues, the raccoons could still fall prey to predation and disease. Should raccoons have been rendered unkillable by predation or disease as well as by aging , then the combination of an average gestational period of 65 days, a litter size of 2-5 individuals, and an omnivorous appetite makes for a creature that could easily dominate any and all ecological niches. If Noah can see it with his naked eyes it is most likely that the "third bow" is a halo . Halos can appear in the direction of the Sun (as is the case with the bow here, and opposed to the two rainbows mentioned above) or the Moon. A typical person is most likely to notice the circular 22° halo , which is a halo forming a circle with a radius of approximately 22° around the Sun, or occasionally the Moon. It could also be that Noah has spotted a tertiary rainbow or even a higher order rainbow which are very faint rainbows circling the sun. These bows are discussed in the what If? released the same day. But they are very faint rainbows circling the sun and usually obscured by its glare, and only recently have they been photographed. Knowing Randall the joke could be inspired by this not well known fact (there are at least 5 observable orders of rainbow), and each could potentially represent a promise from God regarding a disaster. Noah continues by noticing two sun dogs (or parahelia) which often co-occur with the 22° halo. These consist of a pair of bright spots either side on the Sun, intersected by the halo, thus making it most obvious that the third bow was indeed a halo, not a hard to see rainbow. God gets tired of this and tries to stop Noah by saying that he has said sorry, and asks him to drop the subject. That is probably sensible because there are 25 different atmospheric optical phenomena listed on Wikipedia alone. Following the logic of the comic and the evasive answer of God, it could mean that there are some more skeletons in the closet. The title text is a continuation where God tells Noah that in the future humanity will invent a game called SimCity . This is a strategy computer game in which the player creates and manages an environment wherein sims autonomously build a city (or in later versions a country, or a planet). The sims are simple AI processes that "build" residential, commercial and industrial structures within the game space, according to the topography and zoning choices made by the player, then use them to create more wealth to expand their city. The sims have to contend with traffic jams, social problems, and ecological impacts of their own activity, and occasional natural disasters ranging from earthquakes to Godzilla. The player has God-like control of the world, including a disaster button , for when the player doesn't want to wait for a disaster to happen by chance. God suggests that it is too tempting to push the disaster button once a civilization has been built up, if just to see what happens. This can also be interpreted as a reference to the Simulation Hypothesis , which states that there's a high likelihood of us living in a simulated universe, with a fallible "God" who's simulating our Universe purely for his own entertainment/educational purposes. Overall the comic pokes fun at the idea of explaining natural phenomena as messages from a deity. [Cueball looks up on a rainbow band going through the top right corner of the panel. A black blob in the bottom of the panel right of Cueball with white text inside shows the reply from God to the questions. The blobs continue through the rest of the comic.] Cueball: Wow, God- What's that band of color? God: A rainbow . God: It is a sign of my promise that I will never again flood the Earth. [A frameless panel.] Cueball: Oh, good! Hey, what about that second bow above the first one? God: Oh, uh, sign of my promise not to set the earth on fire. God: Sorry for doing that a while back. [Cueball points left.] Cueball: What about that third faint bow near the sun? God: My promise to never again destroy Earth's ecosystem by making raccoons immortal. [Cueball points even higher up towards left.] Cueball: And the little rainbow clouds on either side of- God: Look, I said I'm sorry. Can we just drop it?

Patch

Patch

https://www.xkcd.com/1685

https://www.explainxkcd.com/wiki/index.php/1685:_Patch

[The panel displays part of a code, in five different colors (red, purple, light blue, blue, and green) as well as normal black text, which due to image editing is difficult to read. The first and last lines are partly obscured by the frame of the panel. Here below is an attempt to transcribe the code, using the sign "¤" for anything not easily transcribed. Feel free to add other signs instead of these that look more like the one in the image (and also improve the attempted transcription if possible).] [Caption below the panel:] Protip: If you don't have access to the GNU patch tool, you can use the Photoshop one.

Adobe Photoshop is a commonly used application for image manipulation. One of its features is the Patch tool, which allows the user to overwrite parts of the image, replacing them with a copy of another area of the same image. It is often used for “patching up” photographs by overwriting scratches or other visible damage to the photo. Another of Photoshop’s features is “content-aware fill”, which could also be described as “content-aware inpainting”. It works similarly to the Patch tool, but automatically generates a replacement texture from the area surrounding the deleted part instead of copying a user-specified area exactly. GNU patch is a program that replaces only parts of code with an updated version, without requiring the user to download the entire source code. Here, it appears the author was told to “patch” the code but used Photoshop to do this instead of GNU patch, with devastating results. Although the title text suggests that if you did this enough times the code would eventually compile, this would never happen. In fact, Photoshop could only edit an image of the text and not the text itself. However, it could work if optical character recognition (OCR) were integrated into the workflow as well. The comic blurs the difference between text (in which letters and symbols represent discrete values, such as 65 being the number for the letter A in the ASCII encoding standard, and it's relatively easy for a program compiler to interpret combinations of these values as keywords and other programming constructs) and graphics (where the letters and symbols in the comic are actually represented by a pattern of colored dots), playing with the idea that the patch metaphor can be used on both (although with different meanings). There are common and straightforward processes for converting text information to images, such as printing, which can convert text to a graphics format very faithfully. The reverse, however, requires the use of optical character recognition (OCR), which attempts to figure out which letter or symbol certain patterns of dots "look like". OCR could be effective in converting some of the image in the comic back to usable text; however, it would fail on some of those patterns that have been mangled and don't look like any existing characters or symbols. A compiler can only operate on text data, so converting the graphic back into text would be a requirement to even begin to attempt to compile it, a step omitted in the title text. The code appears to be written in Python , a programming language often referred to in xkcd, such as in 353: Python . A few of the function names that can be recognized are "isPrime" and "quicksort", both elementary programming algorithms. It was also apparently originally edited using a Python-aware programming text editor, which is able to use different colors for different programming elements. For example, it appears to use red for keywords, blue for variables, and black for other elements; however, because of the mangling from the use of the wrong patching program, that doesn't appear to be consistent. Since the patching replaced graphical elements rather than whole characters, there are examples of symbols that are combinations of two different characters, and when the original two characters were rendered in different colors the resulting non-character could be in two colors, or the resulting "word" might be rendered in multiple colors. The comic brings to attention the high rate of Adobe Photoshop piracy. GNU Patch is available for free, even for Windows , and Mac OS X. So the comic implies that Adobe Photoshop, a subscription to which costs $20/month, is more available than GNU patch. According to this poll , 58% of Photoshop copies were pirated. The title text also explains that the patch used the content-aware inpainting to fill in all the wasted whitespace in the code. In most programming languages, whitespace is necessary to separate words, so this would combine words that shouldn’t be combined and create invalid code. Since the code in the image is Python, the code will be messed up even more, because Python uses whitespace as a part of its programming syntax. For example, statements are separated by newlines instead of by semicolons (;), and indentation is used instead of brackets to determine the scope of each section of code. The original code was likely as follows: isPrime and quicksort are standard python implementations of simple algorithms (although you would not generally write a sorting algorithm in python as there are built-in algorithms available). isPrimeRegex uses the re module to detect if a number is prime by seeing if a string containing that many 1s can be matched to 2 or more copies of some string containing at least 2 1s. The comic two comics back 1683: Digital Data , also related to turning digital data into bad copies. Less than a month before quicksort was mentioned in 1667: Algorithms , and a month before that another "easy" solution to a programming problem was released in 1654: Universal Install Script . Using a Photoshop tool for a task it is not intended for was also used in 1784: Bad Map Projection: Liquid Resize , where Photoshop's content-aware resizing tool was a very questionable choice to use for a Map Projection. [The panel displays part of a code, in five different colors (red, purple, light blue, blue, and green) as well as normal black text, which due to image editing is difficult to read. The first and last lines are partly obscured by the frame of the panel. Here below is an attempt to transcribe the code, using the sign "¤" for anything not easily transcribed. Feel free to add other signs instead of these that look more like the one in the image (and also improve the attempted transcription if possible).] [Caption below the panel:] Protip: If you don't have access to the GNU patch tool, you can use the Photoshop one.

Feel Old

Feel Old

https://www.xkcd.com/1686

https://www.explainxkcd.com/wiki/index.php/1686:_Feel_Old

[Megan and Cueball are walking.] Megan: Wanna feel old? Cueball: Does anyone? But OK, go ahead, I'm ready. Megan: This is the first presidential election in which there are voters too young to remember 9/11. Cueball: ...I wasn't ready.

This is yet another comic following xkcd 's recurring theme of using cultural or pop-cultural event dates to reference how much time has passed between two events, often with the stated intention of making someone realize how old they are. (See Comics to make one feel old as well as this xkcd blag post . However, this is the first comic where the title is actually directly related to feeling old!). In each case, the joke is derived from the shock that many adults feel upon realizing that events that feel relatively recent actually took place many years or even decades ago. This becomes especially relevant when it is noted how old someone born during that time would be. Perhaps this is because for many people, there are fewer significant events and changes in their lives after they reach adulthood where there are no grade numbers and annual class changes to mark the continued passage of years. Hearing many years have passed framed in the context of the age of a child allows you to realize how long the period really is as you recall how much had occurred in your own life and how much you had grown by the time you were that age. In this case, Megan makes Cueball feel old by noting to him that the 2016 U.S. presidential election will be the first U.S. presidential election in which there will be eligible voters who are too young to remember the September 11 terrorist attacks , in which hijacked airplanes crashed into the World Trade Center in New York City, the Pentagon and a field in Pennsylvania in 2001. These attacks (commonly referred to as "9/11") were, in many ways, a defining event for an entire generation of Americans. This statement is made on the basis that the eligible voting age in the United States (the minimum age you must be to be eligible to vote in an election) is 18 years old, which is set by the Twenty-sixth Amendment to the United States Constitution . Eligible voters in this election will have been born on or before November 8, 1998. The youngest voters will therefore have been nearly three years old (two years, ten months, and three days) on September 11, 2001. Megan is presuming that children under three years old (or at least some or many of them) were either too young to retain any memories from that age, or at least were too young to appreciate the significance of the attacks such that they would be retained memories 15 years later. The previous U.S. presidential election took place November 6, 2012 and eligible voters would have been just shy of seven years old on September 11, 2001. Megan similarly presumes (or at least is generalizing) that voters who were seven on 9/11 were old enough to retain that memory through adulthood. Particularly for those who were of voting age on September 11, 2001, it might seem startling that by election day, 15 years will have passed since 9/11. This might be particularly so given how significantly 9/11 shaped American society in the years following the attacks. 9/11 was a significant political point in the elections following the attacks as well as in non-electoral politics (such as discussions over homeland security, military actions, etc.) It is also unusual in that there was only one new Presidency (Obama replacing Bush in 2009) in a fifteen year period; historically, an average of nearly three new Presidencies begin in every fifteen years (the 44th Presidency is scheduled to end January 20, 2017, nearly 228 years after the first one began in 1789). To realize that there are people who have reached adulthood and weren't even old enough to be aware of 9/11 when it happened is a stark reminder of the passage of time since the event. The following election on November 3, 2020 , was the first in which there were eligible voters who were born after 9/11. The 9/11 attack was already used in 647: Scary to make people feel old already back in 2009. At that time kids born after the event was old enough to discuss the event with adults which was what was scary for Rob in that comic. When Megan asks Cueball if he wants to "feel old", he replies resignedly, suggesting that he recognizes (possibly based on the previous strips) that she's about to make him feel his age, but claims that he's ready. However, after she makes her statement, he admits that he wasn't ready. While he's technically aware of his age, that kind of perspective still catches him by surprise, and likely causes significant emotional discomfort. His additional discomfort may also be as a result of the serious and significant events of 9/11 Megan references in comparison to previous strips where lighter things like film release dates are cited (see the most relevant of those comics here: 891: Movie Ages ). In the title text, Cueball asks Megan how long she can "keep this up" (i.e. how long she will continue to mention things to make him feel old). However, instead of addressing how long she can keep coming up with uncomfortable facts, she references a new fact that (intentionally or not) that likely has a similar effect of making Cueball feel old: That they're only likely to live another forty to fifty years (suggesting that they're both in their mid- to late- thirties). This may also be a reference to 493: Actuarial , where actuarial tables were used to estimate when (famous) people will die. "How long are you going to keep this up?" Is also a question that is likely asked to Randall often. Perhaps, through this comment, he is confirming that he will continue making these comics until death or for as long as he possibly can. [Megan and Cueball are walking.] Megan: Wanna feel old? Cueball: Does anyone? But OK, go ahead, I'm ready. Megan: This is the first presidential election in which there are voters too young to remember 9/11. Cueball: ...I wasn't ready.

World War III+

World War III+

https://www.xkcd.com/1687

https://www.explainxkcd.com/wiki/index.php/1687:_World_War_III%2B

[A quote with white text on black background:] "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. World War V will be fought with crossbows, World War VI will be lasers, and World War VII will be blowguns. I don't know about World Wars VIII through XI. World War XII will use the same weapons as III, but will be fought entirely within underground tunnels. World War XIV will—Hey, come back! I have a whole list!" — Albert Einstein

This comic takes a famous quote attributed to Albert Einstein , and expands upon it to absurd levels. The original quote is: "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones." The basic premise of this quote is that World War III would be so devastating to the world that all humanity's progress would be wiped out and we would return to the technological level of the Stone Age. The original quote is meant to be taken with a poetic license, with "sticks and stones" taken as a metaphor. Any literal interpretation reveals the quote to be faulty - a world war implies battles occurring through the world, on multiple continents, as part of a single war. Such a war can only occur in the presence of advanced communication networks, and advanced political/diplomatic structures; both of which would also imply weaponry far more sophisticated than sticks and stones. This comic pokes further fun at the literal interpretation of the quote, by appending to it other "literal statements" of a similarly ridiculous nature. This comic expands the original quote letting Einstein suggest what other weapons future World Wars will be fought with: In the title text Randall feigns annoyance about how the media only use the first part of the quote, thus taking it out of context. He implies that this is actually a full quote by Einstein and that all other occurrences using only the "original" version of this quote are misrepresenting it. In this particular case it is a much stronger quote than the long version from the comic, but it is often the case that quotes taken out of context seem to have an entirely different meaning than originally intended. Incidentally, if you investigate the original context of the actual quotation, it turns out that Einstein may not have even said it in this exact form, and may in any case have got the idea from someone else. See the dicussion at Wikiquote . [A quote with white text on black background:] "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. World War V will be fought with crossbows, World War VI will be lasers, and World War VII will be blowguns. I don't know about World Wars VIII through XI. World War XII will use the same weapons as III, but will be fought entirely within underground tunnels. World War XIV will—Hey, come back! I have a whole list!" — Albert Einstein

Map Age Guide

Map Age Guide

https://www.xkcd.com/1688

https://www.explainxkcd.com/wiki/index.php/1688:_Map_Age_Guide

[A very complicated flow chart, which can only be read in detail using the larger image now shown at the top of this page. This transcript uses the large version, which is more legible.] [At the top of the chart there is a large caption, with a smaller caption below:] Guide to figuring out the age of an undated world map (Assuming it's complete, labeled in English, and detailed enough) [Below the starting bracket in the small caption is a start box. It has rounded corners and it is gray with white text. From this box there is a gray line to a box consisting of a black frame with rounded corners. In these kind of boxes there are questions regarding the map in black text. Below this box there are three gray boxes like the start box, superimposed over the bottom frame. In these boxes are the possible answers to the question in the frame above. From each of these options there is a gray line going to similar black framed boxes with other questions either below, or to either side. There can either be two, three or four gray boxes, two the most common. Only at the very bottom of the central branch where it turns out it was a home made map, are there two frames with only one gray question box each. This trend continues over this entire large image. When reaching the end of a branch in the flow chart, there is no line away from one, more or all of the gray boxes for a black frame. When this happens a year range or a guess at what the map shows, or what it is (if it turns out to not be a map) is written below the gray box in gray text. Of the text in the gray boxes are Yes/No, but not always. There are 74 boxes with black frames with 158 gray boxes and 78 endpoints with text below the gray box and one end point without text below (the one with the home made map).] Start Istanbul or Constantinople? Constantinople Do any of these exist ? Independent Canada US Territory of Alaska Tokyo No The Holy Roman Empire? Yes 1805 or earlier (before this point, the modern idea of a complete political map of the world gets hard to apply.) No The United States? No How sure are you that this map is in English? Yes Texas is... Part of Mexico Florida is part of... Spain Paraguay? No 1806–10 Yes 1811–17 The US Venezuela and/or Ecuador? No 1818–29 Yes 1830–33 Independent 1834–45 Part of the US Does Russia border the Sea of Japan? No The US's southern border looks... Weird 1846–53 Normal 1854–56 Yes 1858–67 Yes South Africa? No Rhodesia? No Is Bolivia landlocked? No "Buda" and "Pest" or "Budapest"? Buda and Pest 1868–72 Budapest 1873–83 Yes 1884–95 Yes Is Norway part of Sweden? Yes 1896–1905 No 1906–09 Yes Austria-Hungary? Yes Albania? No 1910–12 Yes 1913–18 No Leningrad? No 1919–23 Yes 1924–29 Neither Does the Ottoman Empire exist? Yes #canada-alaska-tokyo No The Soviet Union? Yes Saudi Arabia? Yes Is most of West Africa a giant french blob? Yes Pakistan? No How many Germanys are there? One Persia or Iran? Persia 1930–34 Iran 1935–40 One, but it's huge 1941–45 Two 1946–47 Yes Cambodia? No Eritrea is part of... Italy Canada is... Missing a piece 1948 Fine The town on I-25 between Albuquerque and El Paso is... Hot Springs 1948-49 Truth or Consequences 1950–52 Ethiopia 1952–53 Yes The United Arab Republic? No 1954–57 Yes 1958–60 No How many Vietnams are there? Two Bangladesh? No Is the area south of Lake Victoria... British 1960 Tanganyika 1961–64 Tanzania 1965–71 Yes 1972–75 One Jimmy Carter is... Being attacked by a giant swimming rabbit April 20, 1979 Fine The Sinai is part of what country? Israel 1976–79 Mostly Israel 1980 Mostly Egypt 1981 Egypt What's the capital of Micronesia? Kolonia Republic of the Upper Volta or Burkina Faso? Upper Volta 1982–84 Burkina Faso 1985–88 Palikir (number of Yemens) + (number of Germanys) = ? Four 1989-early 1990 Three mid-1990 Two late 1990–1991 No 1922–1932 No North Korea? Yes Zaire? or: "Hong Kong (UK)" Yes 1992–96 No Serbia/Montenegro are... One country East Timor? No 1997–2001 Yes 2002–06 Two countries How many Sudans are there? One 2007–11 Two Is Crimea disputed? Yes "Colorado" or "Danger—Radioactive Exclusion Zone—Avoid"? Colorado 2014–21 Danger Does the warning mention the spiders? No 2022 Yes 2023 or later No 2012–13 No Saint Trimble's Island No Is Jan Mayen part of the Kingdom of Norway? Not yet #canada-alaska-tokyo What? Can you see the familiar continents? Yes This sounds like a physical map or satellite photo. Yes, that's it Is Lake Chad missing? No How far east do the American Prairies reach? Indiana before 1830 The Mississippi 1830s-80s Nebraska Is there a big lake in the middle of Southern California? (created by mistake) No 1860s-1900s Yes 1910s What prairies? Is there a big lake in the middle of Ghana? (created on purpose) No 1920s-50s Yes 1960s-70s Yes Is the Aral Sea missing? No 1970s-90s Yes 2000s+ No Rivers "Sirion" or "Anduin"? Yes Mordor? No Beleriand? Yes First Age No Early Second Age Yes Númenor? Yes Late Second Age No The forest east of the Misty Mountains is... Greenwood Early Third Age Mirkwood Late Third Age The Wood of Greenleaves Fourth Age No Cair Paravel? Yes Calormen? No Lotta Islands? No Beruna Ford The Lion, the Witch and the Wardrobe Bridge Prince Caspian Yes Dawn Treader Yes Weird recursive heaven? No One of the random later books Yes The Last Battle No Mossflower? Yes Redwall No Is the world on the back of a turtle? Yes Discworld No Are you sure this is a map? Yes Did you make it yourself? Yes It's very nice. Thank you! No Is it trying to bite you? No Is it larger than a breadbox? Yes tuba No stapler About the same breadbox Yes If you let it go, what does it do? Hisses and runs away cat Screeches and flaps around the room breaking things seagull Yes #pakistan Yes No, I made that one up. Istanbul Does the Soviet Union exist? Yes #west-africa-french-blob No #zaire Title text: Does the screeching chill your blood and herald death? If yes, banshee. If no, seagull.

The comic consists of a flowchart depicting various ways to tell what era a map is from based on present country borders and land forms. (Except in the Not a Political Map Branch (from "Can you see the familiar continents?" downwards), the comic applies to a political map.) While many of the options are very serious, a few bizarre options reference fictional maps ( Discworld , Narnia , and Tolkien's Middle-earth ), or consider that seagulls, staplers, tubas, or breadboxes could be mistaken for a map. Randall also mentions US President Jimmy Carter being attacked by a giant swimming rabbit , an event previously referenced as one we must never forget in 204: America . The flowchart, although probably effective in eventually identifying the production year of certain maps, is designed in a rather inefficient way, as some early distinctions are already on a very detailed level before some really important distinctions (fictional or non-political map) are made. This, of course, adds to the humorous tone of the comic. It is also hampered by several smaller or larger error (see trivia ), the biggest being a whole section on I-25 that gives years in the range 1948–1952, before I-25 was built, and coming from a question that fixed the year range to 1960–1961. Additionally, (possible) future maps including a "Radioactive Exclusion Zone" in the place of Colorado are mentioned. It predicts that some kind of nuclear incident will occur in Colorado (possibly at Rulison or Rio Blanco nuclear testing sites) in 2022. It also predicts that the area will be infested by radioactive spiders one year later. The title text continues the path where the user has confused a seagull for a map by inquiring if the (presumed) seagull might be a banshee based on the effect of its screams. [A very complicated flow chart, which can only be read in detail using the larger image now shown at the top of this page. This transcript uses the large version, which is more legible.] [At the top of the chart there is a large caption, with a smaller caption below:] Guide to figuring out the age of an undated world map (Assuming it's complete, labeled in English, and detailed enough) [Below the starting bracket in the small caption is a start box. It has rounded corners and it is gray with white text. From this box there is a gray line to a box consisting of a black frame with rounded corners. In these kind of boxes there are questions regarding the map in black text. Below this box there are three gray boxes like the start box, superimposed over the bottom frame. In these boxes are the possible answers to the question in the frame above. From each of these options there is a gray line going to similar black framed boxes with other questions either below, or to either side. There can either be two, three or four gray boxes, two the most common. Only at the very bottom of the central branch where it turns out it was a home made map, are there two frames with only one gray question box each. This trend continues over this entire large image. When reaching the end of a branch in the flow chart, there is no line away from one, more or all of the gray boxes for a black frame. When this happens a year range or a guess at what the map shows, or what it is (if it turns out to not be a map) is written below the gray box in gray text. Of the text in the gray boxes are Yes/No, but not always. There are 74 boxes with black frames with 158 gray boxes and 78 endpoints with text below the gray box and one end point without text below (the one with the home made map).] Start Istanbul or Constantinople? Constantinople Do any of these exist ? Independent Canada US Territory of Alaska Tokyo No The Holy Roman Empire? Yes 1805 or earlier (before this point, the modern idea of a complete political map of the world gets hard to apply.) No The United States? No How sure are you that this map is in English? Yes Texas is... Part of Mexico Florida is part of... Spain Paraguay? No 1806–10 Yes 1811–17 The US Venezuela and/or Ecuador? No 1818–29 Yes 1830–33 Independent 1834–45 Part of the US Does Russia border the Sea of Japan? No The US's southern border looks... Weird 1846–53 Normal 1854–56 Yes 1858–67 Yes South Africa? No Rhodesia? No Is Bolivia landlocked? No "Buda" and "Pest" or "Budapest"? Buda and Pest 1868–72 Budapest 1873–83 Yes 1884–95 Yes Is Norway part of Sweden? Yes 1896–1905 No 1906–09 Yes Austria-Hungary? Yes Albania? No 1910–12 Yes 1913–18 No Leningrad? No 1919–23 Yes 1924–29 Neither Does the Ottoman Empire exist? Yes #canada-alaska-tokyo No The Soviet Union? Yes Saudi Arabia? Yes Is most of West Africa a giant french blob? Yes Pakistan? No How many Germanys are there? One Persia or Iran? Persia 1930–34 Iran 1935–40 One, but it's huge 1941–45 Two 1946–47 Yes Cambodia? No Eritrea is part of... Italy Canada is... Missing a piece 1948 Fine The town on I-25 between Albuquerque and El Paso is... Hot Springs 1948-49 Truth or Consequences 1950–52 Ethiopia 1952–53 Yes The United Arab Republic? No 1954–57 Yes 1958–60 No How many Vietnams are there? Two Bangladesh? No Is the area south of Lake Victoria... British 1960 Tanganyika 1961–64 Tanzania 1965–71 Yes 1972–75 One Jimmy Carter is... Being attacked by a giant swimming rabbit April 20, 1979 Fine The Sinai is part of what country? Israel 1976–79 Mostly Israel 1980 Mostly Egypt 1981 Egypt What's the capital of Micronesia? Kolonia Republic of the Upper Volta or Burkina Faso? Upper Volta 1982–84 Burkina Faso 1985–88 Palikir (number of Yemens) + (number of Germanys) = ? Four 1989-early 1990 Three mid-1990 Two late 1990–1991 No 1922–1932 No North Korea? Yes Zaire? or: "Hong Kong (UK)" Yes 1992–96 No Serbia/Montenegro are... One country East Timor? No 1997–2001 Yes 2002–06 Two countries How many Sudans are there? One 2007–11 Two Is Crimea disputed? Yes "Colorado" or "Danger—Radioactive Exclusion Zone—Avoid"? Colorado 2014–21 Danger Does the warning mention the spiders? No 2022 Yes 2023 or later No 2012–13 No Saint Trimble's Island No Is Jan Mayen part of the Kingdom of Norway? Not yet #canada-alaska-tokyo What? Can you see the familiar continents? Yes This sounds like a physical map or satellite photo. Yes, that's it Is Lake Chad missing? No How far east do the American Prairies reach? Indiana before 1830 The Mississippi 1830s-80s Nebraska Is there a big lake in the middle of Southern California? (created by mistake) No 1860s-1900s Yes 1910s What prairies? Is there a big lake in the middle of Ghana? (created on purpose) No 1920s-50s Yes 1960s-70s Yes Is the Aral Sea missing? No 1970s-90s Yes 2000s+ No Rivers "Sirion" or "Anduin"? Yes Mordor? No Beleriand? Yes First Age No Early Second Age Yes Númenor? Yes Late Second Age No The forest east of the Misty Mountains is... Greenwood Early Third Age Mirkwood Late Third Age The Wood of Greenleaves Fourth Age No Cair Paravel? Yes Calormen? No Lotta Islands? No Beruna Ford The Lion, the Witch and the Wardrobe Bridge Prince Caspian Yes Dawn Treader Yes Weird recursive heaven? No One of the random later books Yes The Last Battle No Mossflower? Yes Redwall No Is the world on the back of a turtle? Yes Discworld No Are you sure this is a map? Yes Did you make it yourself? Yes It's very nice. Thank you! No Is it trying to bite you? No Is it larger than a breadbox? Yes tuba No stapler About the same breadbox Yes If you let it go, what does it do? Hisses and runs away cat Screeches and flaps around the room breaking things seagull Yes #pakistan Yes No, I made that one up. Istanbul Does the Soviet Union exist? Yes #west-africa-french-blob No #zaire Title text: Does the screeching chill your blood and herald death? If yes, banshee. If no, seagull.

My Friend Catherine

My Friend Catherine

https://www.xkcd.com/1689

https://www.explainxkcd.com/wiki/index.php/1689:_My_Friend_Catherine

[Captions above the frame:] New favorite substitution: My Cat→My Friend Catherine [A news feed with comments by six different people discussing their cat, but after the above substitution. Next to each post is a user image, and above the clear text of the substituted comment is a unreadable line of wiggles probably with information about the post time stamp.] [A head shot of a person seen straight on with black hair:] My friend Catherine just did a backflip and then ate a bug! [A full view of Cueball:] I wish my friend Catherine wouldn't wake me up by chewing on my hair. [A head shot of Megan with unreadable text below the image:] Oh no, my friend Catherine has learned to open the refrigerator. [A head shot seen from the front of Knit Cap:] My friend Catherine just walked in, threw up on the rug, and walked out. [A head shot of Ponytail:] My friend Catherine is looking out the window making weird noises at the birds. [Cueball seen from the torso and up:] I wish my friend Catherine wouldn't make eye contact with me while pooping.

This is another comic using substitutions to create the joke by replacing words or phrases, in this case "My cat", with a different word or phrase, in this case "My friend Catherine" (hence the title). The choice of the name is probably because "Cat" is a common nickname for "Catherine". By doing so in a list of people discussing things their cat did , it makes it seem like they are discussing things their female human friend did. What is cute (sitting on keyboards), impressive (doing backflips to eat bugs), or at least normal behavior for a cat (vomiting hairballs) would often be weird, disgusting or disturbing if an adult human were to do it, which is what makes the substitution humorous. The comic depicts a feed on a page for people discussing their cat, similar to Twitter or Facebook, which would be the only kind of place where the substitution is really funny. Apart from known characters like two looking like Cueball , Megan and Ponytail , there is also a person with black hair, not looking particularly like any standard characters, and then a person with a knit cap , which could be the same knit cap wearing user that was also used in 1506: xkcloud (see the pictures of the users ). [Captions above the frame:] New favorite substitution: My Cat→My Friend Catherine [A news feed with comments by six different people discussing their cat, but after the above substitution. Next to each post is a user image, and above the clear text of the substituted comment is a unreadable line of wiggles probably with information about the post time stamp.] [A head shot of a person seen straight on with black hair:] My friend Catherine just did a backflip and then ate a bug! [A full view of Cueball:] I wish my friend Catherine wouldn't wake me up by chewing on my hair. [A head shot of Megan with unreadable text below the image:] Oh no, my friend Catherine has learned to open the refrigerator. [A head shot seen from the front of Knit Cap:] My friend Catherine just walked in, threw up on the rug, and walked out. [A head shot of Ponytail:] My friend Catherine is looking out the window making weird noises at the birds. [Cueball seen from the torso and up:] I wish my friend Catherine wouldn't make eye contact with me while pooping.

Time-Tracking Software

Time-Tracking Software

https://www.xkcd.com/1690

https://www.explainxkcd.com/wiki/index.php/1690:_Time-Tracking_Software

[This comic shows a pie chart with 5 slices, each with a label and a line pointing to these five different sized slices. There is a caption above the chart:] Your activity report [The labels on each slice is given in clockwise order starting top left. The percentages are estimated from the image and are noted in the square brackets before the transcript:] [38%]: Going through the Star Wars movies and digitally replacing all the lightsabers with regular metal swords [16%]: Reading every entry in the Wikipedia article List of helicopter prison escapes [23%]: Installing and configuring time-tracking software [02%]: Actual productive work [21%]: Making a remix of that Jack and Diane song where every line is just "Suckin' on a chili dog outside the tastee-freez" over and over [Below the frame there is a caption:] Time-tracking software shines an uncomfortably harsh light on my daily life.

In this comic, Randall uses time-tracking software , which is intended to increase productivity by identifying how you are spending time, that reveals that he is doing frivolous and pointless things that take up large amounts of his time. He makes remixes, edits Star Wars footage, reads strange (albeit entertaining) Wikipedia articles (see 214: The Problem with Wikipedia ), and even spends a large amount of time adjusting this software, all without getting anything useful done. Thus, he is embarrassed at this revelation. This time waste is a common subject on xkcd, as shown for instance in the comic mentioned above. The visual appearance of lightsabers in the Star Wars movies of the original trilogy has been digitally changed twice during the re-releases for the 2004 DVD and 2011 Blu-ray releases. There are several Star Wars fans that feel the need to alter the movies (mainly to revert the changes made in the re-release), but so far nobody felt the need to replace lightsabers with metal swords. " Jack & Diane " is a rock song written in 1982 by John Mellencamp . " Suckin' on a chili dog outside the tastee freeze " is the first line of the second verse of the song (see the lyrics here ). A remix made using just this line would probably sound a bit repetitive (listen for instance to this re-mix of "Don't You Want Me" , that almost only uses the first line of the song). Two Wikipedia lists are mentioned in the comic and title text; List of helicopter prison escapes and List of sexually active popes . Given that the Pope is supposed to be celibate (at least after 1139), the mere fact that more than ten popes have been involved in sexual activity, even after 1139, is both amusing and intriguing. There are more than forty entries in the helicopter escape list for real-life attempts (plus 16 in fiction); not all of them succeeded, but several did! On June 7th, the Wikipedia Facebook page posted a link to the List of helicopter prison escapes article. A user commented asking if the article was posted on Facebook due to the xkcd comic, and Wikipedia replied by pasting an image of the xkcd comic, which seems to indicate that the Wikipedia representative running the Facebook page was aware of this xkcd comic and posted the list in reference to the comic. In the title text, Randall mentions his disappointment with the lack of a Wikipedia list stemming from the intersection of the two; that is, a helicopter prison escape involving a sexually active pope. With the last (known) sexually active pope being Pope Leo XII in the 1820s, and helicopter predecessors only taking flight in 1907, and mass production of helicopters not occurring until the 1950s, such an event has probably never happened. [ citation needed ] This xkcd comic was published on June 6th. On that day, the Wikipedia article "List of helicopter prison escapes involving sexually active popes" was created and subsequently deleted. The Wikipedia list of sexually active popes has been mentioned before in the what if? Into the Blue on infinitely powerful lasers, and after noting that such a thing cannot exist, the list is offered as a replacement for entertainment. The comic 1692: Man Page was released later that week and also mentioned the pope. [This comic shows a pie chart with 5 slices, each with a label and a line pointing to these five different sized slices. There is a caption above the chart:] Your activity report [The labels on each slice is given in clockwise order starting top left. The percentages are estimated from the image and are noted in the square brackets before the transcript:] [38%]: Going through the Star Wars movies and digitally replacing all the lightsabers with regular metal swords [16%]: Reading every entry in the Wikipedia article List of helicopter prison escapes [23%]: Installing and configuring time-tracking software [02%]: Actual productive work [21%]: Making a remix of that Jack and Diane song where every line is just "Suckin' on a chili dog outside the tastee-freez" over and over [Below the frame there is a caption:] Time-tracking software shines an uncomfortably harsh light on my daily life.

Optimization

Optimization

https://www.xkcd.com/1691

https://www.explainxkcd.com/wiki/index.php/1691:_Optimization

[A flow chart is shown with three boxes connected with two arrows. The first box is rectangular:] Are you prematurely optimizing or just taking time to do things right? [From the first box there is a short arrow straight down to a diamond shaped box:] Are you consulting a flowchart to answer this question? [A labeled arrow continues down.] Yes [The arrow connects to the final rectangular box.] You are prematurely optimizing

In computing, program optimization is the practice of making a computer program work as quickly as possible, typically by designing it to perform the fewest calculations. " Premature optimization " is the practice of trying to optimize parts of a program before such optimization has been shown to be needed. Optimization can prove to have been a waste of time if parts of the program are later changed or discarded, or if the optimized code is only a small part of the workload. Making a routine 10 times faster doesn't help much if that routine is only consuming 1% of the running time to begin with and it may result in more complicated and buggier code. This comic is a flowchart making fun of the difference between prematurely optimizing and doing things right in the first place: it tells you that if you are using it to decide whether you are optimizing prematurely, then you're optimizing prematurely. The humorous conclusion is that if there is any doubt whether an optimization is premature , then it is premature ! Another layer of humor is provided by the minimalism and directness of the flowchart, which suggests that it has itself been (prematurely?) optimized. The title text's root of all evil refers to Donald Knuth 's paper "Structured Programming with Goto statements" (1974) [1] in which he wrote: The title text takes the joke a step further by proposing optimizing a brand new project by introducing a procedure to determine whether a possible optimization is premature - which is obviously a premature optimization. It pokes fun at time-wasting behavior by obsessively perfectionist coders who develop tools to analyze aspects of their software, such as performance. In some fields, such as compilers or database design, such tools can be useful and productive (the 3% mentioned by Knuth?), but the usage suggested here is more appropriately covered by instinct, common sense, and observation of the behavior of the completed program. The title text may also be poking fun at the comic, since the comic itself may be the "system" used to determine premature optimization. Flowcharts are often used in xkcd including the (mostly) non-farcical 1688: Map Age Guide one week prior to this comic. Inefficiency (another xkcd theme) was featured in the comic prior to this one . [A flow chart is shown with three boxes connected with two arrows. The first box is rectangular:] Are you prematurely optimizing or just taking time to do things right? [From the first box there is a short arrow straight down to a diamond shaped box:] Are you consulting a flowchart to answer this question? [A labeled arrow continues down.] Yes [The arrow connects to the final rectangular box.] You are prematurely optimizing

Man Page

Man Page

https://www.xkcd.com/1692

https://www.explainxkcd.com/wiki/index.php/1692:_Man_Page

[A terminal screen; the background is black and the text is white.] Actual UNIX manpages exist on some systems which are written in a similar, nonsensical style to these. Manual pages distributed for the <n>fun sections describe similarly humorous "commands" with unusual options. On some systems, these manual pages are available in funny-manpages or asr-manpages packages.

This comic shows a Unix manual page, i.e. a man page (hence the title), for a fictional program called " blerp ". Unix man pages are meant to provide a brief reference on the usage of a command, not extended explanations with tutorials as may be found in many hardcopy product manuals. Unfortunately, some Unix commands tend to be very bloated and include lots of optional behavior that is often irrelevant to the original intent of the command and can be done much more easily using shell features like piping and redirection, and thus the manpage grows to explain all of the features. This example exaggerates the obscurity and terseness found in many man pages, making fun of the typical style of the genre. It follows the prescribed format for a man page, with the following sections: For comic effect, most of this particular man page is not meaningful, and sometimes doesn't obey the expected syntax. The Synopsis section is supposed to be in a regex -like language called Wirth Syntax Notation , with structures like But the two Synopsis lines given do not have valid Wirth syntax; they randomly mix objects and syntactic characters, and the brackets and braces are not properly nested or paired. The Description section provides an unhelpful summary that could apply to almost any Unix command. Processing input files (or output of other commands in a pipeline) is a generic function for Unix shell tools, as is specifying their behaviour with command line arguments, environment variables and flags. The text leaves to the reader's imagination what the program actually does , and what behavior the various options modify, which gives maximum scope for humorous possibilities. The options are in conventional alphabetical order, except that lower case is placed before upper case, and an em-dash is inserted between b and c. Command-line options , also known as flags, are typed after the program's name to change how the program runs. For example, a user of blerp might type: blerp -a -d -t -p "AVIGNON" According to the man page, this would run blerp in attack mode, piping its output to DEBUG.EXE, with tumble dry, and the true Pope set to "AVIGNON". In most cases, any number of flags can be used in any order, and flags can be followed by argument (such as "AVIGNON" in this example). For a walkthrough of all possible flags see the table of flags below. Below the flags there is a see also list with other ludicrous program names (blirb, blarb and blorp ), each followed by a number in parentheses. This is a common way to refer to a command in Unix environments, where the number denotes the documentation section the program is found in. This serves to disambiguate man pages with the same name, in this instance those for the blerp command (section 1, "General commands") and the blerp() C library function (section 3, "C library functions"). It is unknown which section the man page in this comic resides in. It looks like it could be in section 1, "General commands", which would make it self-referential. Section numbers only go up to 8, so blarb(51) is not a valid section number. The last blorp(501)(c)(3) is not a valid section number either, it is however a slightly covert reference to 501(c)(3) which is an organization that is tax-exempt . Then follows a bug report site. www.inaturalist.org is a site working to extend biological research, and the exact address given, http://www.inaturalist.org/taxa/47744-Hemiptera , points to the same page as http://www.inaturalist.org/taxa/Hemiptera . Hemiptera is the order classifying true bugs , making it a good place to report any biological bugs discovered while running a program (Like the bees found without using -b.) Insects got into some early computers, causing them to malfunction, and hence computer malfunctions are often called "bugs". Finally there is a " copyright " line which references several variously open-source content licenses, which is a recurring theme on xkcd (see 225: Open Source ). For instance, GPL references GNU General Public License and the (2) and (3+) refers to GPL 2 and GPL 3 or higher . CC refers to creative commons where BY is the type of license , 5.0 refers to the attribution and RV 41.0 refers to revision 41.0. However there were no higher attribution than 4.0 at the time of this comic's release. xkcd is released under CC BY-NC 2.5 as can be seen at the bottom of the xkcd homepage. A few comics have been released under the CC-BY-SA license or 3.0 . BSD refers to BSD licenses , another recurring theme in xkcd. "Like Gecko" is a reference to a web browser user-agent string; modern user-agent strings include a lot of text designed to allow browsers to masquerade as different browsers/renderers, and "(like Gecko)" is the standard text for a browser that wants to be treated as if it were Gecko while admitting, if you look closely, that it isn't really Gecko. This copyright line, which includes a lot of mashed-together text that might appear to match any of several different licenses, resembles a user agent string. "Or best offer" is usually seen on a notice of a private sale, where it proclaims the intent to be flexible on asking price in the hope of expediting the sale, with a suggestion that the seller will sell to the highest bidder even if the offer is nowhere near the asking price. In the context of the comic, it suggest that the rights for the program are available for purchase by anyone who makes the "best" offer. Since the other licenses listed would allow free usage without incurring any royalty charge, it would be pointless to buy the rights to this program. It is possible to revoke the other licenses though. Perhaps the program's creator is suggesting the rights could be given to someone making him a different sort of offer, perhaps romantic or sexual? In the title text there is a list with even more info, again with silly names like blarbl and birb . Again there are section numbers. While writing about birb, and without bothering to close the brackets around (3), the writer breaks off to laugh at the reader, telling them that he is kidding and suggesting that they just Google it like a normal person . The implication is that anyone trying to pick through a man page to find out what a program does is going the long way round, when it's much simpler to get Google to tell you. Man pages were part of the subject of 293: RTFM , 912: Manual Override and 1343: Manuals and were mentioned in 434: xkcd Goes to the Airport and 456: Cautionary . [A terminal screen; the background is black and the text is white.] Actual UNIX manpages exist on some systems which are written in a similar, nonsensical style to these. Manual pages distributed for the <n>fun sections describe similarly humorous "commands" with unusual options. On some systems, these manual pages are available in funny-manpages or asr-manpages packages.

Oxidation

Oxidation

https://www.xkcd.com/1693

https://www.explainxkcd.com/wiki/index.php/1693:_Oxidation

[Ponytail is holding a finger up in front of Megan while gray smoke and heat waves pours in to the frame from off-panel left.] Ponytail: In my defense, your car has been oxidizing since you got it. Ponytail: It's just happening a lot faster now.

In this comic Ponytail has set Megan 's car on fire, possibly by crashing it. Oxidation refers to a whole class of chemical reactions. Any chemical reaction that involves the loss of electrons is called "oxidation" (since a lot of these involve oxygen). One oxidation reaction is rusting , the reaction of iron atoms in the steel of the car with oxygen and moisture to produce iron oxide hydrate. Rusting is extremely difficult to prevent, and all cars are rusting slowly. Oxidation was also mentioned in the title text of 1426: Reduce Your Payments , where the main joke was about the opposite reaction i.e. reduction. Another oxidation reaction is combustion , an exothermic reaction, such as the violently rapid reaction of flammable parts of the car with oxygen to produce a whole load of nasty gases and particulates, as well as a lot of heat. Vehicle fires can burn very quickly and destroy a vehicle within minutes. From the most detached viewpoint, these are both oxidation reactions (although they occur in different places: rusting normally happens to the car chassis while fires are usually isolated to the engine) and Ponytail argues that as all cars oxidize, the fire that she has caused has only accelerated the inevitable destruction of the vehicle. This idea was already explored in the what if? Burning Pollen , where the second image shows a burning car and the text above mentions the difference between rusting and burning cars: Lots of materials oxidize when exposed to air. Bananas go bad, copper turns green, iron rusts. Fire is another kind of oxidation reaction. In other words, our cars are always oxidizing; we just try to keep it from happening suddenly. The title text of the image even mentions the fact that it is different parts that burns than those that rust: Although the parts that oxidize during a car fire and the parts that rust aren’t usually the same. The comic by extension mocks arguments that ignore or trivialize quantitative differences. Such arguments are commonly employed to attack climate change: the Earth has been warming since the glacial period ten thousand years ago, it's just happening faster since the introduction of large quantities of greenhouse gases. In the title text the small arthropods (invertebrates that have jointed bodies and exoskeletons) are referencing microscopic mites – tiny creatures that can live on the human body without normally causing any harm (you probably have eyelash mites , for instance). Presumably as a form of revenge, Megan has caused Ponytail to become covered in much larger arthropods - most probably spiders , judging by Randall's fixation with them , but it could be any combination of these often feared animals: spiders, scorpions , insects , crabs , centipedes , millipedes etc. As contrasted with the harmless mites mentioned above, other parasitic arthropods (such as the Crab louse , an insect known in slang as "crabs") are notorious as a sexually transmitted infection , and Megan could have been referring to these as those Ponytail already had as a further means of degrading her after the car fire incidence. Megan's car also caught fire in 1014: Car Problems , but there she did not at first know for sure who did it. Not a direct relation, but Megan seems to be unlucky with her cars. This comic was referenced in the title text of 1732: Earth Temperature Timeline [Ponytail is holding a finger up in front of Megan while gray smoke and heat waves pours in to the frame from off-panel left.] Ponytail: In my defense, your car has been oxidizing since you got it. Ponytail: It's just happening a lot faster now.

Phishing License

Phishing License

https://www.xkcd.com/1694

https://www.explainxkcd.com/wiki/index.php/1694:_Phishing_License

[A sign has an arrow below the text that points toward a sales window in a wall (with glass in front and small semicircular opening at the bottom for transferring money and goods). On each side of the window there are two pieces of paper with illegible text, and there is also one below the window that seems to have some kind of stamp or seal, still illegible). In front of the window Cueball is addressing Ponytail who sits behind the window.] Sign: Phishing license apply here Cueball: Hi, I’d like to apply for a— Ponytail: You’re under arrest. Cueball: …OK, I should’ve seen that coming.

Phishing is a scam where a criminal sends emails or other messages (often large numbers of them) pretending to be from a trusted institution in order to obtain passwords, credit card numbers, or other personal details of victims. The term is a neologism, playing on the term "fishing", because the process is likened to dangling bait and waiting for someone to bite. Phishing is illegal under both traditional fraud laws and modern cybercrime laws. A fishing license is a government-issued permit allowing the catching of fish in controlled waters. Cueball saw the sign offering phishing licenses, and was immediately arrested by the receptionist Ponytail upon applying for one. There is no need for a license for a crime like fraud, so it is dubious an authority would issue them, hence why Cueball should have been more suspicious of the offer. The joke is that the process of offering "phishing licenses" is analogous to the process of phishing itself: they pretend to be a legitimate business and display a sign with a false offer, hoping someone will be fooled into interacting with them. While the ideal phishing attempt is indistinguishable from the real thing, that's generally impossible to attain and there are always some ways to identify it as a scam. But still some people fall into the trap, partly because they don't know what to be on the alert for, and partly because the attempt is often directed at so many people at once that statistically there will be some that will fall for it. Still as Cueball himself states, he should have known it was a scam. The title text reveals that Cueball's arrest was itself a scam, not an actual police sting , adding even more "phishing" to the phishing for potential phishers. He has been put in jail, but is allowed to walk out after paying a bail of $10,000, only to find that when he gets back out on the street, it is not the street on which the county jail has its address. So Ponytail is actually not trying to capture people who would be interested in scamming people, she is trying to scam those people instead; although this is illegal, it may be rather clever as such people might not be likely to go to the police. Another joke in the title text is that a way to recognize phishing attempts is to look at the address of the website (or in his false prison sentence, the street address instead of the web address). [A sign has an arrow below the text that points toward a sales window in a wall (with glass in front and small semicircular opening at the bottom for transferring money and goods). On each side of the window there are two pieces of paper with illegible text, and there is also one below the window that seems to have some kind of stamp or seal, still illegible). In front of the window Cueball is addressing Ponytail who sits behind the window.] Sign: Phishing license apply here Cueball: Hi, I’d like to apply for a— Ponytail: You’re under arrest. Cueball: …OK, I should’ve seen that coming.

Code Quality 2

Code Quality 2

https://www.xkcd.com/1695

https://www.explainxkcd.com/wiki/index.php/1695:_Code_Quality_2

[Zoom in on Ponytail sitting in front of a computer screen typing. Cueball speaks only off-panel, but since this is a direct continuation of comic 1513: Code Quality where Cueball is shown, there can be no doubt it is him.] Ponytail: Ugh, I hate reading your code. Cueball (off-panel): I know, I know. [Zoom out of Ponytail in an office chair in front of the computer on a desk.] Ponytail: It's like you ran OCR on a photo of a Scrabble board from a game where Javascript reserved words counted for triple points. [Zoom in on Ponytails head.] Ponytail: It looks like someone transcribed a naval weather forecast while woodpeckers hammered their shift keys, then randomly indented it. [Zoom out back to the setting of the second panel.] Ponytail: It's like an E E Cummings poem written using only the usernames a website suggests when the one you want is taken. [Zoom in to Ponytails head and the screen in a wider panel. Finally Cueball again answers off-panel.] Ponytail: This looks like the output of a Markov bot that's been fed bus timetables from a city where the buses crash constantly. Cueball (off-panel): Whatever, it runs fine for now. Ponytail: So does a burning bus.

This comic is the second in the Code Quality series: It is because it is so clearly a continuation of the first that it is clear that it is Cueball who answers from off-panel. As in the first we again see Ponytail being introduced to the source code Cueball has written, and where he is warning her that he is self-taught so his code probably won't be written the way she is used to. In the first comic she continues to describe poetically the total mess of a code she encounters, using references to a child building houses, recipes created by corporate lawyers or the transcript of a couple arguing at IKEA, as well as using emojis in the code (title text). In this comic she continues this trend in four more abusive comments, after starting this sequel with a short remark on how she hates reading Cueball’s code. Cueball is not even shown in this comic, only replying twice off-panel, but as the title makes it clear this is a sequel there can be no doubt that it is Cueball. With the four remarks here as well as a fifth in the title text, she has now managed to make no fewer than nine derogatory remarks on Cueball's programming skills. In the second panel Ponytail makes a reference to "OCR" ( Optical Character Recognition ), a technique for recognizing text in a picture using software. In this case she is referring to a picture of a Scrabble game, which is a popular word-making game in which players have a pseudo-randomized set of letters and must arrange them on a grid to form interlocking words. OCR software is notoriously imperfect at the time of writing, and the criss-crossing semi-random words on a Scrabble board fed through an OCR program would likely produce dubious results, certainly not fit for current code standards. Ponytail observes that Cueball’s code includes the JavaScript reserved words more often than a typical Scrabble board would, a concession that the code looks at least vaguely code-like. Reserved words such as ‘function’, ‘if’ and ‘return’ are fundamental building blocks of code, and most code uses them often. (They are called “reserved” because those words are reserved for their actual meanings such as defining a function — programmers may not create variables with those names.) As for why “triple points” translates to a prevalence of those words, Scrabble's point system is based on the value of individual letters, combined with certain modifier squares on the game board which can boost points. "Triple points" is the highest class of modifier available in the game (though it can be for triple points on a specific letter, or the entire word) and is highly-sought-after by players. The third panel continues Ponytail's rant, this time referencing naval weather forecasts, avian interference and indentation. A weather forecast is a complex, multidimensional array of data used in predicting or assessing the atmospheric conditions of a geographical area over a set time. Naval weather forecasts (archive) use an extremely condensed code to send their information, rendering them unintelligible to an untrained reader. Transcribing it would be further complicated by a woodpecker (a bird noted for its rapid successive pecking motions) "hammering" (pecking) the Shift key on the keyboard, which would result in many letters being randomly capitalized. Indentation is the practice of shifting a section of text further from the starting margin, which in coding is typically used to organize functions and statements, but if done "randomly" would only serve to scramble the code hierarchy. The fourth panel references famous poet E. E. Cummings and user name suggestions. Edward Estlin Cummings was a poet who used capitalization, punctuation, and line breaks in unconventional ways. Websites that offer membership often also require that users create a pseudonym (known as a "username") for use in tracking/authenticating their actions on the site, as well as identifying them to the site's community. Many of these sites also require usernames be unique. On popular sites, many common words, phrases and names have already been reserved by users, so when signing up for them many people run into situations where the name they want has already been taken. On many sites where this happens, the site may suggest alternate usernames, usually based on the one that was entered to begin with. For example, if the username "Hedgeclipper" is already reserved, the site may recommend "Hedgeclipper1234" or "H3dg3clipp3r" instead, depending on the algorithm behind the suggestions. In other cases, websites requiring users to enter personal information such as their name may suggest a username based on their name with a string of digits after it, such as "Joshua1128". An E. E. Cummings poem written entirely out of these semi-random suggestions would make the resulting poem even more "unusual" than his work is already considered. The last panel's simile involves Markov chaining , chat-bots (presumably), bus schedules and potential gross vehicular negligence. Applied Markov chaining is a process used in many computer algorithms that try to simulate real-world concepts such as speech simulation and decisions-making. Its inherent randomness also makes it a candidate for unpredictable things such as stock market analysis and speech recognition. Bus schedules are often complicated and full of notation , and are notorious for confusing people who are not used to reading them. Chat-bots using applied Markov chains to recognize and respond to speech/text rely on the input being clear and well-organized in plain language. "Feeding" bus schedules to such a bot would likely result in the returns being complete gibberish and unreadable, especially if the reason that the buses crash constantly is because the bus schedules are too incoherent for the bus drivers to understand. The issue is further complicated when Ponytail suggests that the schedules are from a city where "the buses crash constantly", which would be horrifying if it happened so regularly that the schedules actually took crashes into account. However, the reason for the crashes is not stated, and it is not clear whether the passengers are in any danger. The buses might be safe if the problem is pedestrian suicides. Even more horrifying would be the further unpredictability of the output of the chat-bot from such unpredictable input. Cueball finally comments that "… it runs fine for now" which indicates he knows the code has problems but is reluctant to fix them because it's more-or-less serving its function. Ponytail quips back that "So does a burning bus", which is technically true, but the "for now" part implies that disaster and injury could result at any moment, as would likely happen on a burning bus. In the title text, Ponytail makes a final remark. A formal grammar is a way of describing the structure of text such that computers can recognize or generate such text. A raw database dump is an export of the data from a database for the purposes of transferring it to another database or importing it into a program, viewed “raw” without processing to make it easy for humans to read. QuickBooks is an accounting software package. The company collapsing in an accounting scandal implies their accounting database would be a mess even in a human-readable format. [Zoom in on Ponytail sitting in front of a computer screen typing. Cueball speaks only off-panel, but since this is a direct continuation of comic 1513: Code Quality where Cueball is shown, there can be no doubt it is him.] Ponytail: Ugh, I hate reading your code. Cueball (off-panel): I know, I know. [Zoom out of Ponytail in an office chair in front of the computer on a desk.] Ponytail: It's like you ran OCR on a photo of a Scrabble board from a game where Javascript reserved words counted for triple points. [Zoom in on Ponytails head.] Ponytail: It looks like someone transcribed a naval weather forecast while woodpeckers hammered their shift keys, then randomly indented it. [Zoom out back to the setting of the second panel.] Ponytail: It's like an E E Cummings poem written using only the usernames a website suggests when the one you want is taken. [Zoom in to Ponytails head and the screen in a wider panel. Finally Cueball again answers off-panel.] Ponytail: This looks like the output of a Markov bot that's been fed bus timetables from a city where the buses crash constantly. Cueball (off-panel): Whatever, it runs fine for now. Ponytail: So does a burning bus.

AI Research

AI Research

https://www.xkcd.com/1696

https://www.explainxkcd.com/wiki/index.php/1696:_AI_Research

[Cueball (representing Randall, or at least the person who wrote the caption) is standing in front of a computer console displaying AI, talking to it. The computers reply is indicated to come from the console with a zigzag line, rather than the straight lines for Cueball.] Cueball: Then you say "More like fart ificial intelligence!" Computer: Understood. Cueball: Great! Now let me teach you about "updog". AI tip: To develop a computer with the intelligence of a six-year-old child, start with one as smart as an adult and let me teach it stuff.

This is another one of Randall's Tips , this time an AI Tip. Developing artificial intelligence (AI) has been a challenge for a long time. Even to develop one with the intelligence of a six-year-old child would be a great milestone, and presumably a stepping stone on the path to making one with the intelligence of an adult human. In this comic, Randall / Cueball jokingly suggests that in order to accomplish this goal, one can give him an AI that's already as smart as an adult, and let him teach it childish and silly things. He is shown teaching it dumb jokes, much like the ones a sassy six-year-old would make, as the first "fart" joke where art ificial is changed to fart ificial. The humor in the comic is that Randall is essentially accomplishing the present goal of a six-year-old-equivalent AI by starting with the final goal, which is a full human intelligence, and making it dumber, just by teaching it poor humor. This is not unlike the old joke, "The easiest way to make a small fortune on Wall Street [or similar] is to start with a large one." The specific situation may also be a reference to Tay , a Microsoft chatbot that was taught to troll within hours of its exposure to the public. " Updog " refers to a light-hearted practical joke in which the perpetrator casually uses the neologism 'updog' in a sentence ("Hey, I'm going to get some updog, you want any?"). The unsuspecting listener is expected to be curious about the meaning of the neologism and ask the perpetrator its meaning, specifically in the format "What's 'updog'?", inadvertently invoking the highly casual greeting of "What's up, dawg?". The perpetrator then draws attention to this by replying along the lines of "Not much, you?", causing the target to realize the foolish thing they just said. Other neologisms used in the context of this joke include 'updoc', 'snoo', and 'samatta' (" What's up, doc? ", "What's new?", and "What's the matter?", respectively). Updog is mainly an American joke not particularly well known in other English-speaking countries. In the title text there is a joke on lambda calculus , where lam bda is changed to SHAM bda. Lambda calculus is an area of mathematical logic and theoretical computer science. It is a formal language which can express computation and evaluation. It is Turing Complete, which means it can do any computation which can be executed by a computer. However, it is very simple, consisting only of two primitive notions: abstraction , which is forming a unary function (a function that takes one argument) and application which is applying a function to an input value. For example, a function which squares a given number can be written λx.x². Here the λ indicates an abstraction (hence the name lambda calculus ), the x is the input value and the output is x² . As an example of application, if we apply this function to 5, we get (λx.x²)(5) = 5² = 25. The title text makes fun of this by inserting the word "Sham" into the phrase, a word used to describe a trick or con; essentially, it denies that such calculus is useful or valid. The title text finishes with amirite , short for am I right? which is often used to finish sentences on web forums, to prevent anyone saying you are wrong. Not very mature to use in a serious discussion, so very fit to use for a AI that tries to emulate the intelligence of a six-year-old. [Cueball (representing Randall, or at least the person who wrote the caption) is standing in front of a computer console displaying AI, talking to it. The computers reply is indicated to come from the console with a zigzag line, rather than the straight lines for Cueball.] Cueball: Then you say "More like fart ificial intelligence!" Computer: Understood. Cueball: Great! Now let me teach you about "updog". AI tip: To develop a computer with the intelligence of a six-year-old child, start with one as smart as an adult and let me teach it stuff.

Intervocalic Fortition

Intervocalic Fortition

https://www.xkcd.com/1697

https://www.explainxkcd.com/wiki/index.php/1697:_Intervocalic_Fortition

[Cueball holding his hands in front of his mouth is whispering into a Cueball-like person's ear. The second Cueball turns his head towards the first Cueball.] Cueball: Psst–teach your kids to pronounce V's in the middle of words as F's, but don't write down why you're doing it. Cueball: Pass it on. [Caption below the panel:] My hobby: Playing pranks on future linguists

The linguistic processes of lenition ("weakening") and fortition ("strengthening") refer to a sound becoming, respectively, either more or less vowel-like. Intervocalic means "between two vowels." An unvoiced consonant like f in between two vowels (which are almost always voiced) is more noticeable and takes more effort to pronounce than the voiced version v of the same sound in that position, so a change from v to f in this context would be an example of fortition. As a rule, however, lenition is much more common, and in fact one of the most common regular changes observed across languages is the kind of lenition that is the precise opposite of Cueball's prank: An unvoiced consonant between two vowels comes to be spoken, over time, as a voiced consonant, such as the middle consonant in the word "butter" that in American English is now pronounced as a brief alveolar tap [ɾ] rather than [t]. Observing a pattern of fortition rather than lenition in that position (especially for just one particular consonant) would be a very puzzling phenomenon to future linguists. Examples for the suggested change are: In some languages, like German and Dutch, V is often pronounced like F. But it is not always the case. The title text refers to the fact that English phonotactics tend to discourage final or unstressed /ɛ/ . Exceptions tend to be monosyllabic interjections, such as: The word 'meh' is an interjection used to express boredom or indifference. The suggestion that it was originated by the writers of the animated TV show, The Simpsons , is incorrect . However, its use did surge in popularity following its use in various episodes of the show, beginning with the 1994 episode "Sideshow Bob Roberts". This is the second time in 2016 that Randall tries to spread linguistic misinformation, the first being 1677: Contrails , but since both are in the My Hobby series it is not so strange. [Cueball holding his hands in front of his mouth is whispering into a Cueball-like person's ear. The second Cueball turns his head towards the first Cueball.] Cueball: Psst–teach your kids to pronounce V's in the middle of words as F's, but don't write down why you're doing it. Cueball: Pass it on. [Caption below the panel:] My hobby: Playing pranks on future linguists

Theft Quadrants

Theft Quadrants

https://www.xkcd.com/1698

https://www.explainxkcd.com/wiki/index.php/1698:_Theft_Quadrants

[A chart with an Eisenhower box, consisting of four labelled squares. To the left the rows are labelled hard and easy and two lines goes to from these labels to a description of what the labels refer to saying "how hard thing would be to steal". On the bottom the rows are labelled not that bad and very bad and two lines goes to from these labels to a description of what the labels refer to saying "how bad it would be if someone stole it". The top left box is labelled "the Crown Jewels". The top right box is labelled "the nuclear launch codes". The bottom left box is labelled "the Oscar Mayer Wienermobile. The bottom right box is labelled "the tinyurl.com domain name".]

This is an Eisenhower box comparing how difficult it is to steal a specified object with the severity of the theft. It is very hard to steal nuclear launch codes . They are protected by many layers of federal security. That's a good thing, too, since if they were stolen, they could be used to start a nuclear war , which would cause untold death and destruction. It is also hard to steal the Crown Jewels , since they are protected by a complex security system. But if they were stolen, it wouldn't be so bad for most people; the only direct loss would be to its owners, the British royal family, who are well-insured for thefts and only use the Crown Jewels as a display piece for museumgoers. It would also be a loss to the public as a cultural and historical artifact, but would have little practical effect on the world. It wouldn't be too hard to steal the Wienermobile [ citation needed ] (a car shaped like a hot-dog, advertising the Oscar Mayer brand). There are several versions of this car, and it would not be more difficult to steal than any other car, although harder to hide. Randall seems to consider that such a stolen vehicle would not be too bad, although he has previously referred to a stolen Wienermobile in 935: Missed Connections , which is driven recklessly, almost hitting someone. But it is not bad enough to consider it a big problem in a context when it is compared with stolen nuclear launch codes. It also wouldn't be hard (or at least, not as hard as stealing nuclear launch codes or the Crown Jewels) to steal the tinyurl.com domain name, but the consequences of that could be significant and is thus listed under very bad. The joke is of course that this is listed as just as bad as the risk of a nuclear war, and of course it is not as significant, but it could swiftly result in damage to a lot of important computers, and ruin references in journals etc. TinyURL offers a URL shortening service. They provide short URLs that redirect to long ones. This is useful if you want to write down a very long URL as it saves typing and is more accurate. Other companies, including bit.ly , Google (ultimately fully discontinued March 30, 2019), and Twitter offer a similar service. TinyURL was, for a while, the most popular of these URL shortening services. If their domain name were stolen, all the redirects from short URLs could be changed to forward traffic to sites hosting, for example, malware. This would have significant effects on a large number of people, because TinyURL is used in many places both online and (as the title text notes) even sometimes offline. In the title text Randall implies that stealing the tinyurl.com domain could happen when it next expires. A whois search as of February 2021 finds that the tinyurl.com domain is next due for renewal in January 2029. However, rule changes made by ICANN (the organization in charge of domain name registrations) now make it effectively impossible to steal a domain name because the owner allowed its registration to lapse. Current rules for .com registrations now allow for the original owner to renew their domain name after it expires during a 0-45 day auto-renew grace period. The exact length of this grace period depends on what company the domain is registered with. All registrars are then required to give a 30 day redemption grace period during which the domain may be renewed with penalty. As a result, tinyurl.com would have a 30-75 day period after expiration during which the domain is not available for registration by a third party. ICANN rules state that DNS resolution must be stopped during the redemption grace period, which means that there will be a 30 day period during which tinyurl.com will no longer work but the company will have the ability to quickly restore ownership of their domain. It is very unlikely that any company that is still in business would not notice that their domain name has expired before the end of the 30 day redemption grace period. Another way to steal a domain name would be through domain name hijacking . There have been some high profile cases of domain name hijacking, with one of the more notable domains being nike.com in 2000 . However, whether or not this is a risk for any particular domain name is difficult to estimate. Additional security mechanisms such as domain name locking and private registrations have been introduced to mitigate the threat of domain name hijacking. Further, domain name hijacking relies on situation-specific attacks such as hacking email accounts, spoofing emails, and social engineering attacks against either the company who owns the domain name or the company who registers the domain name. For security-conscious companies, such attacks can be impossible, or at least an attacker's success may require security failures in more than one area. A summary of domain hijacking examples including an analysis of how they succeeded and what steps could have prevented them can be found here . In short though, there is no way to say for sure how vulnerable any particular domain name might be to hijacking. [A chart with an Eisenhower box, consisting of four labelled squares. To the left the rows are labelled hard and easy and two lines goes to from these labels to a description of what the labels refer to saying "how hard thing would be to steal". On the bottom the rows are labelled not that bad and very bad and two lines goes to from these labels to a description of what the labels refer to saying "how bad it would be if someone stole it". The top left box is labelled "the Crown Jewels". The top right box is labelled "the nuclear launch codes". The bottom left box is labelled "the Oscar Mayer Wienermobile. The bottom right box is labelled "the tinyurl.com domain name".]

Local News

Local News

https://www.xkcd.com/1699

https://www.explainxkcd.com/wiki/index.php/1699:_Local_News

[Blondie as a news anchor is sitting behind a table with her arms resting on the tabletop.] Blondie: In local news, city council elections were held today. Blondie: In nonlocal news, I killed my past self with a tachyon beam.

Typical news broadcasts are divided into local, national, and global news segments. The broadcast in this comic presented by Blondie , the news anchor , has been broken into real local, (about city council election) and what the newscaster calls "nonlocal". Rather than focusing on national or global news, the nonlocal segment deals with news of a nonlocality nature; more likely dealing with causal nonlocality. A " tachyon " is a theoretical or thought-experiment particle which travels faster than the speed of light . It has many strange properties, including being able to go back in time. This is how the newscaster is able to send a beam back in time to kill her past self. The comic does not explain the paradox of how someone who died in the past could still be alive in the present/future, nor any of the many other paradoxes that arise when time travel is involved, a recurring theme in xkcd. The title text asks if there could ever be a greater physics term than tachyonic antitelephone , a theoretical device which would allow messages to be sent to the past. The text then continues to answer the question via a message from the future (presumably sent by antitelephone). The answer is No - there will never be a greater physics term. [Blondie as a news anchor is sitting behind a table with her arms resting on the tabletop.] Blondie: In local news, city council elections were held today. Blondie: In nonlocal news, I killed my past self with a tachyon beam.

New Bug

New Bug

https://www.xkcd.com/1700

https://www.explainxkcd.com/wiki/index.php/1700:_New_Bug

[Cueball sits at his desk in front of his computer leaning back and turning away from it to speak to a person off-panel.] Cueball: Can you take a look at the bug I just opened? Off-panel voice: Uh oh. [Zoom out and pan to show only Cueball sitting on his chair facing away from the computer, which is now off-panel. The person speaking to him is still of panel even though this panel is much broader.] Off-panel voice: Is this a normal bug, or one of those horrifying ones that prove your whole project is broken beyond repair and should be burned to the ground? [Zoom in on Cueball's head and upper torso.] Cueball: It's a normal one this time, I promise. Off-panel voice: OK, what's the bug? [Back to a view similar to the first panel where Cueball has turned towards the computer and points at the screen with one hand.] Cueball: The server crashes if a user's password is a resolvable URL. Off-panel voice: I'll get the lighter fluid.

Cueball asks if an off-panel character can look at his bug report. The person asks if it's a "normal one," and not a "horrifying" one which proves that the entire project is "broken beyond repair and should be burned to the ground." This implies that there have been reports of the "horrifying" variety in the past. Cueball promises that it is a normal one but it turns out that the server crashes when a user's password is a resolvable URL, which implies that the server is in some way attempting to resolve passwords as if they were URLs. A resolvable URL is one that is syntactically correct and refers to a find-able and accessible resource on the internet (i.e. does not return a 404 error or equivalent when resolved). Therefore a resolvable URL is a fully qualified domain name or a valid IP address that points to a valid server, and it can optionally specify a resource that exists on that server. Normally there is no reason for a system to treat a password as if it were a URL — and testing if a password is a resolvable URL would be a horrible thing to do as it would involve sending the password over the internet in a (at the time the comic was written) most likely completely unencrypted format. Also, Cueball specifically states that the server is crashing, rather than his application. While this could be an example of misused terminology on the part of Cueball or Randall, given Cueball's history (for example causing the most basic console commands to fail in 1084: Server Problem or other tech issues as seen in 1586: Keyboard Problems ) his choice of terms is probably accurate. In the context of web services the server refers to either the computer itself or the program that responds to web requests and executes the user's (i.e. Cueball's) application. Cueball would be in charge of building the application. The importance of this distinction is that a typical system has safe guards in place at many levels to prevent a misbehaving application from crashing anything other than itself. So for his application to crash the server (either the computer itself or the server software hosting his application) would require his application to be operating in a way far outside of the normal, which has been the case for Cueball in previous comics. Alternatively, the project might include its own server software without the safeguards. In either case it is clear that Cueball's issue is far from normal, for which reason the off-panel person gives up and decides that burning the project to the ground is the only solution, telling Cueball I'll get the lighter fluid . In the title text, another two issues with Cueball's program are mentioned, together with a possible solution that would fix all three problems at once. The second problem is a unicode-handling bug in the URL request library, and the third is that the passwords are stored unsalted. The proposed solution is to salt the passwords with emoji (unicode, multi-byte characters), which is claimed to solve all three issues at once. Salting passwords means that random characters are added to the password before it is cryptographically-secured and stored in the database. Salting increases security in the event that the database is compromised by ensuring that users with the same password will not have the same password hash. This makes some attacks that can be used to crack hash databases, such as rainbow tables , effectively impossible. Salting passwords with emoji can potentially "fix" these bugs in different ways. First, emoji and other unicode characters are not valid characters in URLs. As a result the salted-passwords will no longer be resolvable URLs. This will presumably circumvent (but not actually fix) the bug that causes the server to crash. In addition, the passwords will now be salted, increasing security. There is no obvious way that this would actually fix a unicode-handling bug in the URL request library. Given Cueball's general approach to problems like this, the best explanation is probably that he hasn't "fixed" the bug but rather that it is no longer a bug because he is relying on its behavior to help fix these other issues, i.e. the classic it's not a bug, it's a feature . The title text shows that his general approach to problems is not to actually fix bugs but to work around them and even rely on them for other behavior. This approach to software development makes for terrible code, which is likely how Cueball got into this trouble in the first place. Therefore the title text shows that he still has yet to learn from his mistakes, further supporting the suggestion to just burn the whole thing down. In the title text of the first, using emoji in variable names is mentioned. Emoji has since then become a recurrent theme on xkcd. In 1349: Shouldn't Be Hard , Cueball is also programming and finding it very difficult, although he thinks it should be easy. An off-panel person suggests burning the computer down with a blowtorch, much like the off-panel person in this one suggests burning the whole project (including the computer) to the ground with lighter fluid. In the next comic, with multiple storylines 1350: Lorenz , one story line results in a computer being burned with a blow torch . Interestingly, the 2021 vulnerability Log4Shell could be triggered when a specially crafted URL was logged with the Log4j framework. This could lead to a crash (as in the comic) or the computer being taken over by the attacker. However, the contents of a password field should never be logged, so this still would indicate a major problem with the design of Cueball's project. [Cueball sits at his desk in front of his computer leaning back and turning away from it to speak to a person off-panel.] Cueball: Can you take a look at the bug I just opened? Off-panel voice: Uh oh. [Zoom out and pan to show only Cueball sitting on his chair facing away from the computer, which is now off-panel. The person speaking to him is still of panel even though this panel is much broader.] Off-panel voice: Is this a normal bug, or one of those horrifying ones that prove your whole project is broken beyond repair and should be burned to the ground? [Zoom in on Cueball's head and upper torso.] Cueball: It's a normal one this time, I promise. Off-panel voice: OK, what's the bug? [Back to a view similar to the first panel where Cueball has turned towards the computer and points at the screen with one hand.] Cueball: The server crashes if a user's password is a resolvable URL. Off-panel voice: I'll get the lighter fluid.