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Temperature

Temperature

https://www.xkcd.com/901

https://www.explainxkcd.com/wiki/index.php/901:_Temperature

[A close up of Cueball with a thermometer in his mouth.] [The thermometer beeps.] Thermometer: BEEP [A full-body shot of Cueball looking down at the thermometer.] [A close-up of the thermometer's read-out.] Thermometer: PREGNANT

This is a play on the fact that many digital thermometers look similar to pregnancy tests . Cueball , perhaps feeling ill, thinks he is using a thermometer to measure his body temperature and determine if he has a fever. As a male, and as he is taking it orally, he is doubtless surprised when the thermometer tells him instead that he is pregnant. The two bars on the thermometer are similar to lines that appear on a traditional pregnancy test. One bar is the control line; it will become visible given any normal urine sample. If it doesn't appear, the test is invalid. The other bar, the test line, reacts to human chorionic gonadotropin , a hormone that's released during pregnancy. If both lines become visible, the test result is positive; if only the control line becomes visible, the test result is negative. Other results are invalid, since the control line didn't appear. Thermometers are typically used to measure temperature, and the title text notes that this clever thermometer has also detected a fever in the baby. [A close up of Cueball with a thermometer in his mouth.] [The thermometer beeps.] Thermometer: BEEP [A full-body shot of Cueball looking down at the thermometer.] [A close-up of the thermometer's read-out.] Thermometer: PREGNANT

Darmok and Jalad

Darmok and Jalad

https://www.xkcd.com/902

https://www.explainxkcd.com/wiki/index.php/902:_Darmok_and_Jalad

[Captain Dathon is seen on a communications screen.] Alien: Darmok and Jalad at Kalenda's! [Jean-Luc Picard and Deanna Troi stand next to each other, looking off to the right.] Picard: Their language must be based on folklore and metaphor! Computer! Search cultural archives for Darmok-Jalad-Kalenda! [Picard and Troi listen to the response.] Computer (off-panel): In Tamarian legend, Darmok and Jalad got totally wasted and hooked up at a party at Kalenda's. [Dathon is seen on the communications screen again, winking.] WIIIIIINK

This comic is a parody of the Star Trek: The Next Generation episode " Darmok " in which Captain Picard and the Enterprise crew meet with a Tamarian ship. They can translate the individual words of Tamarian with perfect accuracy, but the Tamarians communicate using metaphors based on their own history and culture—without these cultural references, the Enterprise crew are unable to understand what the Tamarians are actually saying. "Darmok and Jalad at Tanagra" is repeated many times in this episode by the Tamarian captain, Dathon. Picard is eventually able to decipher the line to discover that it was a story of two warriors marooned on an island (Tanagra) who work together to defeat a common foe. The alien's intention is that he and Picard work together to defeat a monster as a way to cement ties between the Tamarians and the Federation . In the comic, instead of suggesting a dramatic gesture to achieve a diplomatic breakthrough, the alien seems to be suggesting a one-night stand, hence the wink in the final panel. It is not clear if he is chatting up Deanna Troi (who has the long curly hair) or Picard. However, given that in the original episode Darmok and Jalad (the two warriors) were metaphorically identified with Dathon and Picard, it seems likely that he is flirting with Picard. The title text suggests that the actor Patrick Stewart , who played Captain Picard, might find Star Trek fans indecipherable, in the same way that Captain Picard found the Tamarians indecipherable. This is a joke about how Star Trek fans stereotypically make constant references to the franchise which are so dense and obscure that even the program's actors might find them impossible to understand. [Captain Dathon is seen on a communications screen.] Alien: Darmok and Jalad at Kalenda's! [Jean-Luc Picard and Deanna Troi stand next to each other, looking off to the right.] Picard: Their language must be based on folklore and metaphor! Computer! Search cultural archives for Darmok-Jalad-Kalenda! [Picard and Troi listen to the response.] Computer (off-panel): In Tamarian legend, Darmok and Jalad got totally wasted and hooked up at a party at Kalenda's. [Dathon is seen on the communications screen again, winking.] WIIIIIINK

Extended Mind

Extended Mind

https://www.xkcd.com/903

https://www.explainxkcd.com/wiki/index.php/903:_Extended_Mind

[An IM window is open over a Chrome window with tabs for Spark Plug, Feeler Gauge, and Wikipedia.] Message with Mike1979 Mike1979: I replaced my spark plugs and now my car is running weird. Me: The spark gap might be off. Me: You can check with a feeler gauge. Mike1979: What should the gap be? Me: Usually between 0.035" and 0.070". Me: But it depends on the engine. [An IM window is open over a Chrome window with a single Wikipedia tab, marked ERROR. The page says: "Wikipedia has a problem. Try waiting a few minutes and reloading (can't contact the database server: unknown error (10.0.0.242))] Message with Mike1979 Mike1979: I replaced my spark plugs and now my car is running weird. Me: What is a spark plug?? Me: Help Me: What is a car?? When Wikipedia has a server outage, my apparent IQ drops by 30 points. Randall: "I drew it based on an older error message where the IP was 10.0.0.243. I changed it to 242 (a) because I try not to get too specific with those things, and didn't want people poking the actual machine at .243 (if it was still there) - I actually considered putting .276 and seeing how many people noticed, but figured they'd just think I made a dumb mistake. and (b) as part of this ancient inside joke involving the number 242 ..."

This comic refers to the fact that the narrator has become so dependent on Wikipedia as a source of information that although it gives him the great advantage that he appears learned on any topic with a remarkable degree of specificity, the downside is that whenever Wikipedia goes offline, the limitations of his actual knowledge are revealed. The title, "Extended Mind" , refers to a theory proposed by philosophers Andy Clark and David Chalmers, which postulates that the mind not only includes what can be found in the skull, but also incorporates external things, like Wikipedia. Others have connected this sort of thing to the inate biogical intelligence, or knowledge, but still consider it a different phenomenon under a label such as " ex telligence ". The title text refers to an observed phenomenon that many of Wikipedia's page links eventually lead to the Philosophy page. This may be due to the fact that the first few links in any article tend to reference more general or abstract ideas, which eventually gravitate towards philosophy. This is not actually true, though. It works for the spark plug page and countless others but not for all. The comment section below has some examples, but many of them are not working anymore, because Wikipedia references change in time, as just about anyone can just log in and add/remove links, or just adjust their position in an article. Most instances of this not working are because of endless loops (page A to page B back to page A, or anything like that). More info on this bizarre characteristic of the encyclopedia can be found on their page about it or on this blog . [An IM window is open over a Chrome window with tabs for Spark Plug, Feeler Gauge, and Wikipedia.] Message with Mike1979 Mike1979: I replaced my spark plugs and now my car is running weird. Me: The spark gap might be off. Me: You can check with a feeler gauge. Mike1979: What should the gap be? Me: Usually between 0.035" and 0.070". Me: But it depends on the engine. [An IM window is open over a Chrome window with a single Wikipedia tab, marked ERROR. The page says: "Wikipedia has a problem. Try waiting a few minutes and reloading (can't contact the database server: unknown error (10.0.0.242))] Message with Mike1979 Mike1979: I replaced my spark plugs and now my car is running weird. Me: What is a spark plug?? Me: Help Me: What is a car?? When Wikipedia has a server outage, my apparent IQ drops by 30 points. Randall: "I drew it based on an older error message where the IP was 10.0.0.243. I changed it to 242 (a) because I try not to get too specific with those things, and didn't want people poking the actual machine at .243 (if it was still there) - I actually considered putting .276 and seeing how many people noticed, but figured they'd just think I made a dumb mistake. and (b) as part of this ancient inside joke involving the number 242 ..."

Sports

Sports

https://www.xkcd.com/904

https://www.explainxkcd.com/wiki/index.php/904:_Sports

[Two Cueball like commentators sit behind a desk.] Commentator to the left: A weighted random number generator just produced a new batch of numbers. Commentator to the right: Let's use them to build narratives! [Caption below the panel:] All sports commentary

A random number generator is any object or program that arbitrarily selects and produces a number from within a pre-defined range of numbers. For example, a single six-sided die will produce any integer between 1 and 6, inclusive. In an unweighted random number generator, every number that it can possibly produce has the same odds of coming up. When rolling a single precision die , for instance, there is an equal chance of rolling a 1, 2, 3, 4, 5, or 6. Conversely, in a weighted random number generator, some numbers are more likely to come up than others. For example, when rolling two dice, a seven is far more likely to come up than a two, as there are six possible ways to roll a seven but only one way to roll a two. All sports generate numbers that are inherently random. Home runs, goals, sacks, passes, shots, hits, misses, errors, and many more such statistics are generated in every match of every sports game. The rules of the particular sport, as well as the skill of the participants, introduces bias toward certain values; hence, sports matches are weighted random number generators. If the generator is weighted to favor a specific team in a specific game, that is discussed. Then the results of the game (more random numbers) are discussed. It's the discussion that is the narrative part. If a player breaks a record, that becomes part of the narrative. The number is random, but weighted because of player skill or the rules of the sport. College sports in the US are especially prone to this kind of narrative-first journalism with their penchant for using more arbitrary systems of placement to determine postseason play than professional sports which have almost all standardized their systems around sometimes highly complicated metrics to determine who reaches the postseason. Prime examples of this are the new College Football Playoff which has a committee release polls every week after Week 9 of the college football season, with the top four teams in the final poll playing for the championship, and March Madness where a similar committee ranks the top 68 teams in the country in a bracket for the championship tournament. The old Bowl Championship Series , which determined the NCAA Division I college football champion from 1998 to 2013, literally used computers generating numbers and algorithms based on team performance as a heavy part of their ranking systems that determined which two teams played for the championship at the end of the season. The title text applies this to financial/stock results/forecasts as well and, most appropriately, to Dungeons & Dragons ( D&D ), a tabletop role-playing game. In D&D the players and Dungeon Master are forging a narrative about the characters and world they have collectively made up; the players all decide on courses of action (such as negotiating with townspeople, intimidating nobles, attacking monsters, to name a tiny faction of possibilities) and whether they succeed is determined by rolling dice of various numbers of sides. The numerical results are woven into a narrative by the Dungeon Master. This strip is one of several in which Randall affectionately trivializes sports (see for instance 1107: Sports Cheat Sheet , 1480: Super Bowl and 1507: Metaball ). [Two Cueball like commentators sit behind a desk.] Commentator to the left: A weighted random number generator just produced a new batch of numbers. Commentator to the right: Let's use them to build narratives! [Caption below the panel:] All sports commentary

Homeownership

Homeownership

https://www.xkcd.com/905

https://www.explainxkcd.com/wiki/index.php/905:_Homeownership

[Cueball is in an empty room, on the phone with a friend.] Cueball: I've always rented, so this blows my mind—this house is mine ? I own a building? Friend: Yup! Cueball: I could, like, decide to drill a hole in that wall there, and nobody could do anything about it? Friend: That's right! [Cueball, off the phone, stands in silence.] Ten hours later: [Cueball is standing to the left a pile of rubble, on the phone with a friend.] Cueball: Can I come stay with you? My house has a... problem. Friend: Let me guess: you drilled holes in it until it collapsed? Cueball: I don't think I'm cut out for homeownership.

One common annoyance of American renters is their inability to make simple changes to their dwelling — for example, drilling a hole in a wall to hang a picture — without having to ask for permission from the property owner. In many cases, if the renter drills the hole without asking permission, they are charged for repairs. This is one reason that home ownership can be empowering, as it allows the owner to do anything they wish with their property. This can lead to mishaps however, as shown in the comic when Cueball drills holes in the house to prove his ownership, to the point of structural instability. Cueball's last statement expresses the fact that he was actually better off having someone who could dictate what could and could not be done with his residence. The title text references fictional research showing that 60% of the toxic assets involved in the United States housing bubble were created by power drills. The implication being that Cueball is not alone in his hole drilling tendencies which created not only structural collapse of the homes, but also the financial collapse of the market as those houses would now be worth far less than the mortgages placed against them. Note the double usage of the word collapse. [Cueball is in an empty room, on the phone with a friend.] Cueball: I've always rented, so this blows my mind—this house is mine ? I own a building? Friend: Yup! Cueball: I could, like, decide to drill a hole in that wall there, and nobody could do anything about it? Friend: That's right! [Cueball, off the phone, stands in silence.] Ten hours later: [Cueball is standing to the left a pile of rubble, on the phone with a friend.] Cueball: Can I come stay with you? My house has a... problem. Friend: Let me guess: you drilled holes in it until it collapsed? Cueball: I don't think I'm cut out for homeownership.

Advertising Discovery

Advertising Discovery

https://www.xkcd.com/906

https://www.explainxkcd.com/wiki/index.php/906:_Advertising_Discovery

[Caption above the panel:] Advertising discovery: [Person sits at computer, reading an ad on the screen. The bracketed superscripts are blue.] Ad: Turgidax® triples [2] your penis size overnight, [2][5] improving both your sexual attractiveness [2][7] and your cardiovascular health. [7][8][9] Person (thinking): Sounds legit. [Caption below the panel:] Wikipedia has trained us to believe anything followed by little blue numbers in brackets.

On Wikipedia , a well-referenced text or statement indicates credibility. References for particular facts are linked to by bracketed blue little numbers in superscript . [1] [3][4] When faced with a statement followed by these, readers will normally believe it without further ado, [6][10] since they take it on trust that there are directions on the bottom of the page, leading to a reliable source or two, agreeing with what the statement says. The effect becomes strengthened when such information often is confirmed to be correct. In the comic, advertisers have realized that it has gone so far that people in general will take any nonsense for granted if there is just the right amount of Wikipedia-style reference tags to it. The penis pump e-commerce can suddenly flourish (again?) and the spammers won't even need to bother making up findings to cite. Turgidax ® is something Randall formed from turgid , meaning swollen. One reason that the attaching of -ax creates a typically pill-like name is simply that -ax (and -ex ) are common Latin adjectival word endings, and that many drugs have names formed from Latin words. -Ax is also, specifically, the root of the -acious ending in English, as in "audacious" or (appropriately) bodacious , meaning "extra" or "especially". The idea is it makes the genitalius extra or especially turgid. Cardiovascular means relating to the heart and blood vessels. The title text is about how Wikipedia users have been able to add "disputed"-tags (nowadays "disputed – discuss") after challenged facts, with this template , since the dawn of time. [11] [ disputed – discuss ] So when faced with the new advertising trick IRL , we could counter by scribbling those tags all over with blue Sharpie marker pens, and so automatically revive the critical thinking . [Caption above the panel:] Advertising discovery: [Person sits at computer, reading an ad on the screen. The bracketed superscripts are blue.] Ad: Turgidax® triples [2] your penis size overnight, [2][5] improving both your sexual attractiveness [2][7] and your cardiovascular health. [7][8][9] Person (thinking): Sounds legit. [Caption below the panel:] Wikipedia has trained us to believe anything followed by little blue numbers in brackets.

Ages

Ages

https://www.xkcd.com/907

https://www.explainxkcd.com/wiki/index.php/907:_Ages

[A number line labeled "age." The start point is 0, with points labeled 10, 20, 30, 40, 50, 60, and 70, and the line continues past the width of the panel. There are interstitial, non-labeled points. Above the line are labeled brackets. They are (approximated):] 0-3: [Non-sentient] 4-12: "Everything is exciting!" 13-17: "Everything sucks!" 18-22: "Woooo college! Wooooo—" [vomit] 23-30: "Relationships are hard! 31-42: "So are careers!" 43-54: "No daughter of mine is going out dressed like that!" 55-75+: [More sex than anyone is comfortable admitting]

This is a graph of the general themes that occur between the ages covered by each individual set of brackets. The layout is a parody of larger timescales of human or geologic history, e.g. "Bronze Age" or "Iron Age". The "ages" identified and experiences typical at that age: The title text is a joke about the shortsightedness of many people (at any age) in believing their current age to be ideal. [A number line labeled "age." The start point is 0, with points labeled 10, 20, 30, 40, 50, 60, and 70, and the line continues past the width of the panel. There are interstitial, non-labeled points. Above the line are labeled brackets. They are (approximated):] 0-3: [Non-sentient] 4-12: "Everything is exciting!" 13-17: "Everything sucks!" 18-22: "Woooo college! Wooooo—" [vomit] 23-30: "Relationships are hard! 31-42: "So are careers!" 43-54: "No daughter of mine is going out dressed like that!" 55-75+: [More sex than anyone is comfortable admitting]

The Cloud

The Cloud

https://www.xkcd.com/908

https://www.explainxkcd.com/wiki/index.php/908:_The_Cloud

[Cueball finds a computer tower with a wire leading away from it.] Cueball: What's this? Off-screen: The Cloud. [Cueball looks behind him. The wire leads to an outlet in the wall next to where Black Hat sits at a desk with a computer. Another wire leads from that outlet to Black Hat's computer.] Cueball: Huh? I always thought "The Cloud" was a huge, amorphous network of servers somewhere. Black Hat: Yeah, but everyone buys server time from everyone else. In the end, they're all getting it here. [A close-up of Black Hat.] Cueball: How? You're on a cable modem. Black Hat: There's a lot of caching. [A close-up of Cueball, looking down at the tower at his feet.] Cueball: Should the cord be stretched across the room like this? Black Hat: Of course. It has to reach the server, and the server is over there. [Cueball turns back to the Black Hat, still sitting at the computer.] Cueball: What if someone trips on it? Black Hat: Who would want to do that? It sounds unpleasant. Cueball: Uh. Sometimes people do stuff by accident. Black Hat: I don't think I know anybody like that.

This comic is a reference to all of the companies that rolled out "cloud" services like Google 's and Amazon 's music service and Apple 's aptly named iCloud online backup service around the time that the comic was released. Despite the mental image people using cloud services have of their data being placed literally in the sky, the reality is that all the data in the cloud has to be stored somewhere , sometimes being merely a server. Black Hat claims that the various cloud services are all ultimately provided by his server. When Cueball expresses skepticism that Black Hat has enough bandwidth to make that possible, he explains that it's done by Caching . Caching is an arrangement whereby some data is stored locally in order to reduce the need to retrieve it from more distant storage. However, it would require an unrealistically efficient level of caching to reduce the overhead requirements of the world's cloud storage networks to a level that could be accommodated by Black Hat's non-Enterprise class cable modem -- and if it could be done, it would simply transfer the load to other servers (i.e. Cueball's description of "the cloud" as it exists in the real world). However, it does make a bottleneck at Black Hat's server. The title text refers to the Roomba , which is a small round battery-powered vacuum cleaner that runs automatically around the house. The Roomba begins to learn the dimensions of rooms, however, apparently it has never learned to avoid running over the cord, pulling it free of the socket and cutting power to the server. The regular nightly downtime is a reference to an urban legend in which some critical piece of equipment (often a server) is unplugged regularly so that a vacuum cleaner or similar janitorial tool can be temporarily plugged in. Although the Roomba vacuum does not require this computer's outlet, "running over the cord" apparently causes similar interruption in service, probably unplugging the cord, requiring it to be plugged in again. This comic is reminiscent of a scene in the British sitcom The IT Crowd in which the IT department pranks their non-tech-savvy manager by presenting a single small box and claiming that it contains the entire Internet. The last panel showcases both Black Hat's stereotypical sadism and callousness. When Cueball asks about the hazard (namely, tripping) implicit in a cord stretching across a room, Black Hat responds by implying no one would want to do that, because it's unpleasant. Cueball responds with the fact that some people do things by accident, to which Black Hat says he doesn't know anyone like that. The only way Cueball can disprove this (at least quickly) is by admitting he's one of those people, opening him up to Black Hat's ridicule. Alternatively, this could be a hint towards how Black Hat, being the sadist he is, would "accidentally trip over" the cord, purposefully causing downtime and subsequent unpleasantness to those who rely on the cloud, a proposition supported by the title text. There are some connections with both 1117: My Sky and the title text of 1444: Cloud and especially the April Fools' Day comic 1506: xkcloud . [Cueball finds a computer tower with a wire leading away from it.] Cueball: What's this? Off-screen: The Cloud. [Cueball looks behind him. The wire leads to an outlet in the wall next to where Black Hat sits at a desk with a computer. Another wire leads from that outlet to Black Hat's computer.] Cueball: Huh? I always thought "The Cloud" was a huge, amorphous network of servers somewhere. Black Hat: Yeah, but everyone buys server time from everyone else. In the end, they're all getting it here. [A close-up of Black Hat.] Cueball: How? You're on a cable modem. Black Hat: There's a lot of caching. [A close-up of Cueball, looking down at the tower at his feet.] Cueball: Should the cord be stretched across the room like this? Black Hat: Of course. It has to reach the server, and the server is over there. [Cueball turns back to the Black Hat, still sitting at the computer.] Cueball: What if someone trips on it? Black Hat: Who would want to do that? It sounds unpleasant. Cueball: Uh. Sometimes people do stuff by accident. Black Hat: I don't think I know anybody like that.

Worst-Case Shopping

Worst-Case Shopping

https://www.xkcd.com/909

https://www.explainxkcd.com/wiki/index.php/909:_Worst-Case_Shopping

[Cueball is diving in very deep, dark blue water. He shines a flashlight at the sea floor.] Cueball (thinks): Eight meters. There's the wreckage... Yes! I see the key! [As he swims further toward it, his flashlight starts to cut out.] Cueball (thinks): Gotta grab it, surface, get in to the radio shed, and warn the President! Just a few more... Flashlight: BZZT FIZZ [This panel has no border like the others, and is divided in half diagonally by a thought bubble.] [The left half of it is a dark blue thought bubble with the diver inside it. On the right hand side are packaged flashlights hanging on a shelf. The one called Hi-Brite is $24.95 and is labeled "water resistant to 10 meters." The one called "FenStar G6" is $49.95 and says "water resistant to 40 meters."] Cueball (thinks): Oh no. [Cueball and a friend stand in front of a flashlight display in a store. Cueball looks down at the packages with his hand on his chin in thought. The thought bubble from the previous panel leads from his head. The friend stands behind him.] Cueball: ...maybe I should spring for the deeper water resistance. Friend: Why on earth would you care about that? Cueball: Look, you never know.

For most people, under most circumstances, a flashlight's water-resistance is a completely moot point, as most flashlight use occurs on dry land. But, as Randall has shown before , there is a tendency for people to imagine elaborate scenarios in which an extra edge would be useful. In the dream sequence over the first 2 and a half frames, Cueball appears to be diving to find a key underwater, which he spots using his flashlight when he is at 8 meters. His flashlight goes out at 10 meters because he bought the "Hi-Brite" model. The dream sequence also references a "radio shed", which were only really used in the past for amateur radios or some other military style bases/compounds—which would align with his "warn the President" line. He thus suggests the more water-resistant flashlight. However, this is seen as ridiculous from his friend, since the more durable model costs over $25 more in return. He replies that "you never know" what situation you'll be in. The title text takes Cueball's thought process to the next level. If he is getting a flashlight that works to 40 meters (worst-case), he should probably be prepared for even deeper waters as well (even worse-case). [Cueball is diving in very deep, dark blue water. He shines a flashlight at the sea floor.] Cueball (thinks): Eight meters. There's the wreckage... Yes! I see the key! [As he swims further toward it, his flashlight starts to cut out.] Cueball (thinks): Gotta grab it, surface, get in to the radio shed, and warn the President! Just a few more... Flashlight: BZZT FIZZ [This panel has no border like the others, and is divided in half diagonally by a thought bubble.] [The left half of it is a dark blue thought bubble with the diver inside it. On the right hand side are packaged flashlights hanging on a shelf. The one called Hi-Brite is $24.95 and is labeled "water resistant to 10 meters." The one called "FenStar G6" is $49.95 and says "water resistant to 40 meters."] Cueball (thinks): Oh no. [Cueball and a friend stand in front of a flashlight display in a store. Cueball looks down at the packages with his hand on his chin in thought. The thought bubble from the previous panel leads from his head. The friend stands behind him.] Cueball: ...maybe I should spring for the deeper water resistance. Friend: Why on earth would you care about that? Cueball: Look, you never know.

Permanence

Permanence

https://www.xkcd.com/910

https://www.explainxkcd.com/wiki/index.php/910:_Permanence

[A large panel the combined width of the four panels below it.] [A blue Linux terminal installer screen with a grey box that is labeled "[!]CONFIGURE THE NETWORK" in red. Below, in black, it reads "Please enter the hostname for the system." Below is an empty blue entry box with a cursor and dashed underscore, and below this it says "<GO BACK>".] [Cueball sits at his computer, Megan stands behind him.] Megan: You've been staring at that screen a while. Cueball: Picking a good server name is important. [Megan stares at him.] [She continues to stare.] [Cueball pushes his chair back, puts one elbow on the back of the chair and points with his other hand at the screen.] Megan: And yet you settled on "Caroline" for our daughter in like 15 seconds. Cueball: But this is a server! Cueball: Besides, I had to—you were trying to name her "Epidural." Megan: Those were good drugs.

On the top panel is the sketch of a Debian Installer showing a hostname dialog for its menu-driven frontend. Cueball wants to make sure that he chooses a great permanent name that he can give to the server he is running. Choosing a name for a server is an important task. It is non-trivial enough that there are official communications on how to choose a good name and why many ideas are bad, for example RFC 1178 Name Your Computer . It is important to pick a good name because changing it is costly once many reference to the existing name are widespread. For example, RFC 1178 states: When Megan quips about how quickly, in comparison, Cueball named their daughter Caroline (a living being - that is, the type of entity that would give the server purpose), Cueball retorts that he was under pressure at the time: Megan tried to name said daughter "Epidural" in honor of the painkiller drugs that were being injected into her spine at the time. Megan tries to justify this by explaining that those were very good drugs, but thus also confirms Cueball's point, in that she was drugged, not in her right mind, and thus not making good decisions. Epidurals work by stopping nerves in the spinal cord from transmitting signals, and would not have an effect on the brain similar to those seen in someone given an opiate or narcotic. She may, however, have been motivated purely by the fact that the drug stopped the pain of labor or a cesarean section; alternatively, she may have been on entirely different drugs at the same time. In the title text Cueball mentions that he thinks that it is easier to change a person's name than to change the hostname of a server because of the number of changes that would need to be made to each of the machines that would have saved the old name of the server. It seems that Cueball hasn't realised that a child's name will get logged in government records, school records, and pretty much anything they sign up for and anything they buy or sign. (Of course, many of those documents will be changed by other organizations, making them somebody else's problem. Depending on the exact set of documents which Cueball needs to personally update, changing a name might be easier for him ). Also, you typically have to wait in line at the Social Security Administration office or at the Department of Motor Vehicles, both of which take excruciatingly long amounts of time. [A large panel the combined width of the four panels below it.] [A blue Linux terminal installer screen with a grey box that is labeled "[!]CONFIGURE THE NETWORK" in red. Below, in black, it reads "Please enter the hostname for the system." Below is an empty blue entry box with a cursor and dashed underscore, and below this it says "<GO BACK>".] [Cueball sits at his computer, Megan stands behind him.] Megan: You've been staring at that screen a while. Cueball: Picking a good server name is important. [Megan stares at him.] [She continues to stare.] [Cueball pushes his chair back, puts one elbow on the back of the chair and points with his other hand at the screen.] Megan: And yet you settled on "Caroline" for our daughter in like 15 seconds. Cueball: But this is a server! Cueball: Besides, I had to—you were trying to name her "Epidural." Megan: Those were good drugs.

Magic School Bus

Magic School Bus

https://www.xkcd.com/911

https://www.explainxkcd.com/wiki/index.php/911:_Magic_School_Bus

[A girl sits at a desk in a classroom, and the teacher stands before her. The teacher has a blue dress and blonde hair piled on her head in a bun. The girl raises her hand, the teacher raises both arms above her head, a pointer in one hand.] Girl: Ms. Frizzle, how do batteries work? Ms. Frizzle: To the bus! [Ms. Frizzle and the children are shown getting onto the bus.] [The bus, with Ms. Frizzle at the helm and a child's face in every window, soars through a rainbow void filled with a giant amoeba, a rocket, an epicyclic gear, a planet with rings, and a Feynman diagram.] [The bus is parked, and the occupants have gotten out. The children stand around Ms. Frizzle, and she stands at a desk with a computer on it, typing.] Computer: Wikipedia - Batteries

The Magic School Bus is a series of educational children's books in the US that was adapted in the mid-nineties into an animated television show. The series centers on a class of children whose teacher Ms. Frizzle makes use of the titular magic school bus to take her students on a variety of magical field trips that allow them to experience various scientific topics first hand, such as the inner anatomy of the human body, the effects of friction, what goes on inside a beehive, and many others. In this comic, however, Ms. Frizzle initially takes the students onto the bus apparently for one of these field trips to explore the way batteries work, but then for whatever reason, she has the students get off the bus again and simply resorts to looking up the Wikipedia article about batteries . The implied joke is that, with the advent on resources like Wikipedia, it's no longer necessary for Ms. Frizzle to take the students on half-hour long trips in the bus to experience whatever phenomenon they are studying that day (which is what the third panel symbolizes) - Wikipedia effectively answers the question quickly and easily. An alternative answer is that Ms. Frizzle has just gotten lazy, and has resorted to looking up the answers to the students' questions on Wikipedia instead of taking them on field trips. The alternative seems more likely, since the third panel shows them still going on an adventure, however briefly it takes to get to the library/computer lab. The red and white checkered rocket in the bottom-right of the third panel can possibly be a reference to The Adventures of Tintin Destination Moon and Explorers on the Moon , in which Tintin goes to the moon in a rocket that is similar, if not identical, to the one depicted. To the bottom-left is a green Ciliate , a single celled life-form covered in hair-like fibres. At the top right are a set of Planetary gears . To the top left is a ringed planet, perhaps Uranus and in the background is a complex Feynman diagram . The child who is asking the question looks similar to Wanda, one of the regular students in the class who often asked the questions that set the field trips in motion. Ralphie, the student in the second panel with the backward hat, was another student who often asked these questions. The students in the class were shown to be from many backgrounds (i.e. some of the students were black, another was Asian, etc.), something Randall appears not to have added into this comic, despite it being in color. The title text is a reference to Phoebe, one of the students in Ms. Frizzle's class, who would regularly make a remark beginning with "At my old school..." (Phoebe used to go to a different school, unlike many of the other students in the class) to express wonder at how unusual were the events of Ms. Frizzle's field trips (e.g. "At my old school, we never rode on bees!"). Phoebe actually said that so much that in an episode where she goes back to her old school, the sign out front labels it as "Phoebe's old school". Microsoft Encarta 2005 was a digital encyclopedia that was often used in school settings for learning with the aid of computers. Arguably, with the advent of Wikipedia, programs like Encarta have become relatively less widely used, which is part of the joke in the title text. [A girl sits at a desk in a classroom, and the teacher stands before her. The teacher has a blue dress and blonde hair piled on her head in a bun. The girl raises her hand, the teacher raises both arms above her head, a pointer in one hand.] Girl: Ms. Frizzle, how do batteries work? Ms. Frizzle: To the bus! [Ms. Frizzle and the children are shown getting onto the bus.] [The bus, with Ms. Frizzle at the helm and a child's face in every window, soars through a rainbow void filled with a giant amoeba, a rocket, an epicyclic gear, a planet with rings, and a Feynman diagram.] [The bus is parked, and the occupants have gotten out. The children stand around Ms. Frizzle, and she stands at a desk with a computer on it, typing.] Computer: Wikipedia - Batteries

Manual Override

Manual Override

https://www.xkcd.com/912

https://www.explainxkcd.com/wiki/index.php/912:_Manual_Override

[A plane is in a nosedive with smoke pouring from one wing. Text comes from someone reading in the cockpit.] "This is the emergency override system, which can be used to regain control of the aircraft. Complete instructions for activating this system are available as a GNU info page."

There are two jokes in this comic. The first is that the pilot typed "man override" to manually override the plane's computer and steer the plane to safety, but instead he ends up opening the manual page for "OVERRIDE". The second joke is making fun of a trend in documentation for Unix-like systems using the free GNU toolchain. Historically, UNIX systems had a way to access descriptions of the available programs by using the "man" command (from "manual"). Typing "man [program name]" would output a concise, helpful text, called a " man page ", describing the program's functionality, available command-line options, a list of related programs, etc. For some GNU-based systems, however, the output of "man [program name]" will be entirely too brief, mainly telling what the program does, then directing the user to invoke a GNU-specific information system ( GNU Info ). GNU Info pages can be quite useful, e.g. they often contain much more information than man pages, and are hypertextual , allowing quick navigation through a network of content-related Info pages; however, they often are much more complex to search through than simple man files, which take the form of single scrollable pages, one per program. As such, the humour is predicated upon understanding the frustration which sometimes arises when GNU users seek out a man page, hoping for an easy, digestible read, only to find that the man page they opened merely redirects them to another, less accessible network of hypertext Info pages. This can be especially annoying when it interrupts a person's workflow; e.g. when what they wanted was to spend three seconds looking up the proper format of a particular command line function, and instead they end up redirected to a maze of detailed documentation. This would be especially dangerous when one is trying to stop a plane from crashing. [ citation needed ] To add injury to the insult, sometimes the Info pages aren't actually installed, causing the "info" viewer to just render the same old "man" page that had the directions in the first place. The title text provides a tongue-in-cheek correction to the comic's title, suggesting that rather than typing "man(ual) override", the user/pilot should type "info override" to search GNU Info instead. [A plane is in a nosedive with smoke pouring from one wing. Text comes from someone reading in the cockpit.] "This is the emergency override system, which can be used to regain control of the aircraft. Complete instructions for activating this system are available as a GNU info page."

Core

Core

https://www.xkcd.com/913

https://www.explainxkcd.com/wiki/index.php/913:_Core

[A cutaway diagram of the Earth, with colored layers including a labeled outer core and inner core.] [A closeup of the stylized outer core, labeled "Turbulent molten metals at 30 million PSI" with turbulence lines, and of the inner core, labeled "moon-sized iron sphere."] [Cueball reading a book pulls legs up tight under office chair, peering downwards.] [Caption below the frame:] I freak out about fifteen minutes into reading anything about the Earth's core when I suddenly realize it's RIGHT UNDER ME . What people of different science fields would often think about became the subject of 2057: Internal Monologues . Geologist are not included, but the molten core beneath our feet would probably have been the choice if they had. That Randall was actually already thinking about adding geology was made clear in the next comic 2058: Rock Wall about the core/mantle beneath our feet and 20 miles of rock (wall).

This comic reflects on the fact that no matter where you are on Earth , its core is always directly under you, while incredibly hot and under huge amounts of pressure. Yet most of the time, we ignore this completely unless there is a volcanic eruption (which has nothing to do with the core, but mainly with the friction between the tectonic plates). Cueball is presumably reading a geology book with diagrams and various facts about the Earth's interior, such as the core being subdivided into an inner core and an outer core , that the inner core is a solid ball, the size of the moon, that the outer core is at a pressure of 30 million pounds per square inch (approximately 2 million times atmospheric pressure at sea level) and the outer core is made of molten metal in a constant turbulent motion - a bit like a pot of boiling water. But every time he gets 15 minutes in to such a book he freaks out, realizing this deadly stuff is right beneath him, and he bends over to look down to the Earth. The title text makes a note of how cool it would be to study this and be able to tell people you study what they're standing over... always! So if you do - then let everyone you meet know what you do for a living as soon as you introduce yourself by pointing at the ground beneath you! (Despite most geologists and geophysicists not studying the core, they do study what is beneath our feet.) Alternately, the title text referencing someone gesturing downward, might look as if they were pointing to their genitals. It might be considered a humorous opening to a speech. [A cutaway diagram of the Earth, with colored layers including a labeled outer core and inner core.] [A closeup of the stylized outer core, labeled "Turbulent molten metals at 30 million PSI" with turbulence lines, and of the inner core, labeled "moon-sized iron sphere."] [Cueball reading a book pulls legs up tight under office chair, peering downwards.] [Caption below the frame:] I freak out about fifteen minutes into reading anything about the Earth's core when I suddenly realize it's RIGHT UNDER ME . What people of different science fields would often think about became the subject of 2057: Internal Monologues . Geologist are not included, but the molten core beneath our feet would probably have been the choice if they had. That Randall was actually already thinking about adding geology was made clear in the next comic 2058: Rock Wall about the core/mantle beneath our feet and 20 miles of rock (wall).

Ice

Ice

https://www.xkcd.com/914

https://www.explainxkcd.com/wiki/index.php/914:_Ice

[Megan is setting up a party. She is standing with a bottle in one hand looking at a snack table in front of her. Beret Guy stands behind her with both arms raised. Above and behind them there is a big banner with gray text.] Megan: Everything's ready... Megan: Except we're out of ice. Beret Guy: I'll get some! Banner: Party! [Beret Guy is walking down the street past a building with a store window and sign. He is carrying a large bag of ice over his shoulder. Danish is standing on the sidewalk up against the brick wall and calls to him.] Danish: Hey sexy. Where're you headed with all that ice? Beret Guy: A party! Danish: There's a better party up at my place. Beret Guy: But I— Danish: C'mon, one drink. Sign: Save Mart Bag: Ice [Zoom in on Beret Guy who rubs his eyes groggily, small bubbles floating up from his head. A caption is written above the image in a box that breaks the top frame of this panel:] The next morning... Beret Guy: ...Ugh... Where am I? Beret Guy: I was supposed to— Beret Guy: —Where's all my ice!? [Beret Guy looks down to find himself in a bathtub full of kidneys. His scream extends on both sides of the panel, with only the five central A's in full view:] Beret Guy: AAAAAAA

This comic is a reference to an old urban legend : a guy is drugged, then he awakes in an ice-filled bathtub only to discover both of his kidneys have been harvested by organ thieves . They have left him in the tub of ice, to let him survive in time to get to a hospital for dialysis . It is now his problem to get a new kidney, whereas the thieves can sell the organs to someone who (also) needs a kidney transplantation . By doing it in this way, the thieves prevent themselves from becoming murderers; thus if they get caught they might get a lesser sentence. That would be the explanation why they do not just kill the " organ donor ". In this comic the situation is reversed: Beret Guy (who has just bought some ice for the party he is about to return to) is lured by Danish up to "her place" where he is drugged. The next morning he awakes in a bathtub filled with kidneys, only to discover that his ice has been harvested by Danish. The title text refers to a similar story where the victim is left a note by their captor or one-night stand that says " Welcome to the AIDS club ". Rather than having been involuntarily infected with HIV/AIDS , the victim, Beret Guy, has been involuntarily enrolled in the American Automobile Association (AAA) and his roadside assistance card has been left on the counter. This could also be another pun on Beret Guy's response of yelling AAAAAAA , which could be another kind of AAA club that he is welcomed to. There is no display of typical "Beret Guy behavior" in this comic, although it is typical for him to be involved in an incident that turns the world upside down. His encounter with organ thieves only cost him his ice, a party and that he got a nasty experience. But he retained his kidneys and was not infected with HIV. [Megan is setting up a party. She is standing with a bottle in one hand looking at a snack table in front of her. Beret Guy stands behind her with both arms raised. Above and behind them there is a big banner with gray text.] Megan: Everything's ready... Megan: Except we're out of ice. Beret Guy: I'll get some! Banner: Party! [Beret Guy is walking down the street past a building with a store window and sign. He is carrying a large bag of ice over his shoulder. Danish is standing on the sidewalk up against the brick wall and calls to him.] Danish: Hey sexy. Where're you headed with all that ice? Beret Guy: A party! Danish: There's a better party up at my place. Beret Guy: But I— Danish: C'mon, one drink. Sign: Save Mart Bag: Ice [Zoom in on Beret Guy who rubs his eyes groggily, small bubbles floating up from his head. A caption is written above the image in a box that breaks the top frame of this panel:] The next morning... Beret Guy: ...Ugh... Where am I? Beret Guy: I was supposed to— Beret Guy: —Where's all my ice!? [Beret Guy looks down to find himself in a bathtub full of kidneys. His scream extends on both sides of the panel, with only the five central A's in full view:] Beret Guy: AAAAAAA

Connoisseur

Connoisseur

https://www.xkcd.com/915

https://www.explainxkcd.com/wiki/index.php/915:_Connoisseur

[White Hat is holding a wine glass down in one hand and holding a bottle of wine up in front of him with the other hand. He is looking at the label and talking with Cueball standing next to him with his own filled wine glass in one hand. He is looking down at the glass.] White Hat: How do you stand this cheap wine? Cueball: Wine all tastes the same to me. [Close-up of White Hat.] White Hat: You've just never had good wine. If you paid more attention, you'd realize there's a whole world here. [Close-up on Cueball, who spreads his arms out, resulting in the wine in the glass sloshing so much that part of the wine is above the rim of the glass, some even hanging over the edge and a spray droplet hanging above the sloshing liquid.] Cueball: But that's true of anything! Wine, house music, fonts, ants, Wikipedia signatures, Canadian surrealist porn— Cueball: Spend enough time with any of them and you'll become a snobby connoisseur. [This panel has no border (aka a 'frameless panel') and is next to but aligned further down than the first three panels. It shows a zoom out of both White Hat and Cueball again. White Hat now has both glass and bottle held down at his side. Cueball holds his glass down, but tilted away from him. A small puddle of wine is on the floor next to Cueball.] White Hat: But some things do have more depth than others. Cueball: If you locked people in a box for a year with 500 still frames of Joe Biden eating a sandwich, by the end they'd be adamant that some were great and some were terrible. White Hat: You're exaggerating. Cueball: Oh, really? [This panel is below the feet of the two characters from the previous panel. It goes further to the left than those two, and is wider than the previous panels, but it does not go much past the middle, so there is a blank white space to the left of this panel, below the first and most of the second panel. It shows a box, with two star burst on the surface from where two voices emanate from the inside. Over the top left of the panels frame is a small frame with a caption:] A year later: [The voice from left side of the box:] Sure, most closed-mouth frames are boring, but in #415, the way the man's jaw frames the mayo on his hand is pure perfection, and— [The voice from right side of the box:] What a surprise- you praising a mayo frame. Listening to you , I'd think there was nothing else in The Sandwich. [The voice from right side of the box:] Frankly, the light hitting J.B.'s collar through the lettuce would put #242 in my top ten even if he had no mayo on his hand at all .

White Hat is fond of good wine , and he can probably distinguish slight differences in different types of wine, perhaps being the type that attends wine tasting parties. He doesn't like the cheap wine that Cueball has served for him (implying a cheap wine cannot be a good one, an opinion held by stereotypical wine snobs), looking with disgust at the label of the offending bottle. On the other hand, Cueball doesn't have a preference; all of them taste the same for him, so presumably he gets the cheaper ones. White Hat tells Cueball that if he just tried some really good wine and paid more attention he would discover a whole new world. Cueball's answer is the main message of the comic. He says that wine is no different from anything else in this respect, and makes a list starting with the wine but then going past house music , fonts , ants , ending with Wikipedia signatures and Canadian surrealist porn . His point being if you spend enough time focusing on any one subject, then you'll become a snobby connoisseur on that topic. White Hat tries to defend wine by saying that some things have more depth than others (wine being among them), but Cueball challenges him on this by choosing something as obscure as 500 pictures of Joe Biden , then Vice President of the United States under Barack Obama , eating a sandwich as an example. He claims that if people were locked up in a box with those pictures for a year, they would end up being connoisseurs with the same vehemence regarding the best picture as wine tasters can be about the best wine. White Hat claims that this is an exaggeration, but Cueball takes this as a challenge so in the last panel, apparently White Hat and Cueball are actually running this experiment to see if they will end up concentrating on slight differences among the pictures of Joe Biden eating a sandwich, just in the same way that White Hat concentrates on slight differences among different kinds of wine. The result of the experiment is clearly going to Cueball's side, the discussion being mainly between the importance of mayo or the light through lettuce from the sandwiches. This mentality may also be applied to online groups based on any subject (such as television shows, films, and other hobbies and interests), where arguments and vehement, stubborn opinions are common despite the fairly unimportant subject. The title text presents the same idea in a different wording. The "scale of our brains" refers to a concept similar to Richard Dawkins' Middle World , where things too small (say, smaller than the point of a pin) or too big (bigger than what we can see from a mountaintop) are just out of our comprehension, so the things our brains understand must be neither too small nor too big, i.e. the "middle world". However, the title text goes further in this idea: When we find things too big (like the distance to the Moon), we shrink it so that it fits into the "middle world" we're used to. Conversely, when we find things too small (say, a mote of dust), we expand it for the same reason. In a quite similar way, if all we have is pictures of Joe Biden eating a sandwich, we "resize" that subject so that we can fill books with the details about the pictures. [White Hat is holding a wine glass down in one hand and holding a bottle of wine up in front of him with the other hand. He is looking at the label and talking with Cueball standing next to him with his own filled wine glass in one hand. He is looking down at the glass.] White Hat: How do you stand this cheap wine? Cueball: Wine all tastes the same to me. [Close-up of White Hat.] White Hat: You've just never had good wine. If you paid more attention, you'd realize there's a whole world here. [Close-up on Cueball, who spreads his arms out, resulting in the wine in the glass sloshing so much that part of the wine is above the rim of the glass, some even hanging over the edge and a spray droplet hanging above the sloshing liquid.] Cueball: But that's true of anything! Wine, house music, fonts, ants, Wikipedia signatures, Canadian surrealist porn— Cueball: Spend enough time with any of them and you'll become a snobby connoisseur. [This panel has no border (aka a 'frameless panel') and is next to but aligned further down than the first three panels. It shows a zoom out of both White Hat and Cueball again. White Hat now has both glass and bottle held down at his side. Cueball holds his glass down, but tilted away from him. A small puddle of wine is on the floor next to Cueball.] White Hat: But some things do have more depth than others. Cueball: If you locked people in a box for a year with 500 still frames of Joe Biden eating a sandwich, by the end they'd be adamant that some were great and some were terrible. White Hat: You're exaggerating. Cueball: Oh, really? [This panel is below the feet of the two characters from the previous panel. It goes further to the left than those two, and is wider than the previous panels, but it does not go much past the middle, so there is a blank white space to the left of this panel, below the first and most of the second panel. It shows a box, with two star burst on the surface from where two voices emanate from the inside. Over the top left of the panels frame is a small frame with a caption:] A year later: [The voice from left side of the box:] Sure, most closed-mouth frames are boring, but in #415, the way the man's jaw frames the mayo on his hand is pure perfection, and— [The voice from right side of the box:] What a surprise- you praising a mayo frame. Listening to you , I'd think there was nothing else in The Sandwich. [The voice from right side of the box:] Frankly, the light hitting J.B.'s collar through the lettuce would put #242 in my top ten even if he had no mayo on his hand at all .

Unpickable

Unpickable

https://www.xkcd.com/916

https://www.explainxkcd.com/wiki/index.php/916:_Unpickable

[Caption above the panel:] HackerShield Geek-Proof Safe System: [Two boxes sit side by side. One is a safe with a lock marked "Unpickable." It is labeled: ① 24-pin dual-tumbler radial-hybrid lock (rendered unopenable by a fused 17th pin). The other is a shoebox. It is labeled: ② Shoebox containing your valuables.]

The comic plays on the idea that geeks and nerds will try to break into high-security areas in order to challenge themselves, instead of to steal things. The vault is labeled "unpickable" as a kind of challenge to break into it, while all the valuables are simply stored in a shoe box beside the vault. A 24-pin dual-tumbler radial-hybrid lock would probably be too bulky and cumbersome to actually exist. The key would be huge, or just plain long . Given the length of the key, it would need to be extremely strong, and the length would be around 96mm, assuming that each notch is 5mm. In theory, though, it would be a remarkably difficult type of lock to pick. The fused 17th pin means that, even with the correct key, it cannot be opened. It would be much easier to simply break open the safe with brute force than to pick it. A simple and nerdy way to open the vault with brute force would be to use canned air, using the principle that cold objects are more brittle. Once the air is emptied onto the lock, it can be easily smashed with an ordinary hammer. This is an example of nerd sniping , since the vault is nearly unopenable, nerds and geeks would spend all their time on the vault and ignore the seemingly useless shoe box. The title text continues the theme, with an unsolved 5x5x5 Rubik's cube to further challenge and distract the thief. [Caption above the panel:] HackerShield Geek-Proof Safe System: [Two boxes sit side by side. One is a safe with a lock marked "Unpickable." It is labeled: ① 24-pin dual-tumbler radial-hybrid lock (rendered unopenable by a fused 17th pin). The other is a shoebox. It is labeled: ② Shoebox containing your valuables.]

Hofstadter

Hofstadter

https://www.xkcd.com/917

https://www.explainxkcd.com/wiki/index.php/917:_Hofstadter

[Cueball sits at a desk, working on a laptop. Megan approaches the desk and picks up a tiny book.] Megan: What's this? Cueball: Douglas Hofstadter's six-word autobiography. After all those 700-page tomes, I guess he wanted to try for brevity. Megan: Huh. Let's see... [Close up of Megan, reading the tiny book.] Book: I'm So Meta, Even This Acronym [Full shot of Cueball and Megan again. Megan looks down at the tiny book in her hand.] Megan: ...whoa. Cueball: I think he nailed it.

Douglas Hofstadter is an American author who has written several books about philosophy, mathematics, and science. He is perhaps most famous for his book Gödel, Escher, Bach which explores "strange loops," or self-referential systems . "Meta-" is a Greek prefix meaning "outside" or "beyond." As an adjective, "meta" informally refers to anything self-referential, like the last phrase of this sentence. An example of the use of such a term can be found in 1313: Regex Golf . At first reading, the six word autobiography in the second panel, "I'm So Meta, Even This Acronym", may seem unfinished, however the clue is in the final word. An acronym is an abbreviation formed by the initial letters of a series of words, and reading the first letter of each of the six words in order yields "ISMETA", completing the sentence and setting up the self-reference. Hofstadter himself did something similar in Gödel, Escher, Bach in the chapter "Contracrostipunctus", where the first letter of each line spells out the phrase " H ofstadter's C ontracrostipunctus A crostically B ackwards S pells J .S.Bach" - and taking the first letters of each word in that sentence backwards does indeed spell " J.S. BACH ". This comic is probably a reference to Six-Word Memoirs , a project launched in 2006 in which people "tell their life story in just six-words". This comic may additionally be a reference to the meme "explain <whatever> in six words", which was making the rounds at the time. In the title text, a reference implementation is, broadly, an example of how to implement some feature during the software development process. In this case the feature is a self-referential joke, and the sentence itself is, correctly, self-referential. Hofstadter has been referenced before, in the title text of 555: Two Mirrors and 608: Form . Furthermore, his famous book has been directly spoofed in the title of 24: Godel, Escher, Kurt Halsey . Finally, the self-reference reference ("IS META") is also a typical concept used most famously in 688: Self-Description but also in several other comics . [Cueball sits at a desk, working on a laptop. Megan approaches the desk and picks up a tiny book.] Megan: What's this? Cueball: Douglas Hofstadter's six-word autobiography. After all those 700-page tomes, I guess he wanted to try for brevity. Megan: Huh. Let's see... [Close up of Megan, reading the tiny book.] Book: I'm So Meta, Even This Acronym [Full shot of Cueball and Megan again. Megan looks down at the tiny book in her hand.] Megan: ...whoa. Cueball: I think he nailed it.

Google+

Google+

https://www.xkcd.com/918

https://www.explainxkcd.com/wiki/index.php/918:_Google%2B

Megan: You should join Google+! Cueball: What is it? Megan: Not Facebook! Cueball: What's it like? Megan: Facebook! [Cueball considers.] Cueball: Oh, what the hell. Cueball: I guess that's all I really wanted. click

At the time of the comic's release, Google+ was a new social network announced by Google on June 28, 2011. When it launched there were many tech articles written about G+, which appears to look and/or function similarly to Facebook. In the first panel, Megan describes G+ as 'not Facebook '. Facebook is a popular social networking site. [ citation needed ] She then describes G+ as being like Facebook. After Cueball thinks about it in the second frame, he comes to a realization in the third frame that a social network like Facebook, but not related to Facebook is all he really wanted. This is in reference to the backlash that happens every so often wherein people grow tired of Facebook, its arcane policies, its cavalier attitude toward user privacy and/or its general disdain for end users, and people want to leave Facebook, but have no comparable platform to move their social networking to. The title text uses "you'll never be able to convince your parents to switch" as both point and counterpoint in an argument, since this fact has both negative (your parents won't see posts you want them to see, and won't be able to post things for you to see) and positive (your parents won't see posts you don't want them to see, and you won't have to worry about keeping up with their posts) implications. On April 2, 2019, Google shut down Google+ for consumers. It is still available for users with a G Suite account. Megan: You should join Google+! Cueball: What is it? Megan: Not Facebook! Cueball: What's it like? Megan: Facebook! [Cueball considers.] Cueball: Oh, what the hell. Cueball: I guess that's all I really wanted. click

Tween Bromance

Tween Bromance

https://www.xkcd.com/919

https://www.explainxkcd.com/wiki/index.php/919:_Tween_Bromance

[All of Cueball's lines are overlaid over the entire comic; the panels listed are merely the ones directly under each sentence fragment.] [Cueball is standing smugly behind Megan, who is seated in front of a computer and typing.] Cueball: By my guesstimate, Cueball: my frenemy yiffed so hard Cueball: her moist taint made [Megan's eye twitches.] Cueball: her panties preggers! Megan: STOP IT STOP IT!

Apparently, Randall hates some ridiculous neologisms. Cueball seems to be dictating a "Tween bromance" story or novel to Megan , who is possibly typing it up. He is including all the words that get to Megan in a sequence. Megan is just annoyed and starts to shriek in rage; considering Cueball keeps speaking more annoying words in the title text, that seems to have been the point. Like this comic fills a sentence with (gross) neologisms, 550: Density crams a sentence with memes. According to 1485: Friendship , Randall doesn't like the word bromance much either. Uncomfortable synonyms are also seen in 1322: Winter and 2352: Synonym Date . [All of Cueball's lines are overlaid over the entire comic; the panels listed are merely the ones directly under each sentence fragment.] [Cueball is standing smugly behind Megan, who is seated in front of a computer and typing.] Cueball: By my guesstimate, Cueball: my frenemy yiffed so hard Cueball: her moist taint made [Megan's eye twitches.] Cueball: her panties preggers! Megan: STOP IT STOP IT!

YouTube Parties

YouTube Parties

https://www.xkcd.com/920

https://www.explainxkcd.com/wiki/index.php/920:_YouTube_Parties

[Cueball and a group consisting of three Cueballs and one Ponytail are standing in a dark room around a table. The group and Cueball are illuminated by a laptop on the table.] [Caption above the panel:] The problem with YouTube parties: Cueball (thinking): This video is blowing their MINDS. Group (thinking): Oh man, I know what video we should watch once this is over.

A YouTube party is when a group of people show each other YouTube videos. The problem with YouTube parties is that no one pays attention to the video that's playing; instead, each person is thinking of the video that they personally want to play next. You can see analogous behavior at any get-together where couples (parents) are telling stories about their kids. Nobody cares about anybody else's kid; they are just waiting (not even listening) until they get the chance to talk about their own offspring. The joke seems to be that everybody is doing this, but it is unclear whether they realize it. They each seem to be under the delusion that the others will be fascinated by "their" video (or child's accomplishments), even though the evidence strongly suggests otherwise. Possibly they don't care about that either; they just want an audience, even an unwilling one. This may be defensible where kids are involved, because the parents could reasonably feel that the accomplishments of their children reflect well on themselves. However, the people in the YouTube party didn't create the videos, they just found them. Which makes their behavior (or perhaps YouTube parties in general) even more inane and pointless. The title text reiterates this point. The speaker is reminded of another video that is so superior to the one currently playing that we should find it and watch it immediately. We can always go back to the current video later (if anybody still remembers, that is; and according to the comic above no one will want to remember it). [Cueball and a group consisting of three Cueballs and one Ponytail are standing in a dark room around a table. The group and Cueball are illuminated by a laptop on the table.] [Caption above the panel:] The problem with YouTube parties: Cueball (thinking): This video is blowing their MINDS. Group (thinking): Oh man, I know what video we should watch once this is over.

Delivery Notification

Delivery Notification

https://www.xkcd.com/921

https://www.explainxkcd.com/wiki/index.php/921:_Delivery_Notification

[The first panel is a UPS InfoNotice®. Most of the text on it is just scribbles, though the company logo and header is clear.] [Cueball opens their door to see the InfoNotice® stuck on his door.] Cueball: What! I've been here all day! Cueball 2 (off-screen): Huh? Cueball: They have my laptop. [Cueball and Cueball 2 are standing next to each other. Cueball has his arms to his sides, in annoyance.] Cueball 2: So get it tomorrow. Cueball: I fly out in the morning and they don't open till noon! Cueball 2: Sucks. [Cueball stands, working on a laptop.] Cueball: It's right there . I can see the UPS building on the map. Cueball 2 (off-screen): Ok... [Dramatic zoom to the Cueball's upper torso and face, along with clenched fist.] Cueball: My laptop is there. Cueball: It's mine . Cueball: I'm going to get it. [Even more dramatic zoom! Cueball's face fills the panel.] Cueball 2 (off-screen): They won't let you. Cueball: Who are they to keep from me what is mine? Cueball 2 (off-screen): Dude, they— [Zoomed out on Cueball, who spins around, raising a finger.] Cueball: A quest is at hand! Cueball 2(off-screen): Security's gonna throw you out. Cueball: I fear neither death nor pain. But I will not go unarmed. [Three inset panels overlap, in a montage format.] [Elves in long robes stand around a table, on which lies a broken sword.] Light the beacons and send word to the Elves. They must reforge the sword of my fathers. [An Elf beats the sword together on an anvil.] [An Elf rides a horse, silhouetted by the full moon.] Ere dawn, I will go forth to the Sorting Depot. [The Elf knocks at the door, sword in scabbard held under arm.] Knock knock knock knock [Cueball opens the door, to find a second InfoNotice® stuck on top of the first. The Elf is gone.]

In the US, when the package delivery company UPS (or other package delivery companies) knocks on your door or rings your doorbell and cannot reach you, they leave a delivery attempt notification stuck to your door. These may be for packages that require a signature, such as expensive electronics. An example is shown in the first panel. This comic hints that the threshold for the UPS delivery person to leave such a notice is unreasonably low. The delivery personnel made only a token effort to deliver the package (which, incidentally, is their only actual job) before posting the yellow delivery notification and unconcernedly driving away to their next delivery (or, more likely, their next yellow-delivery-notification-posting). After missing the delivery, Cueball (who is directly referencing The Lord of the Rings ) asks the Elves to reforge his sword in order to go on a quest to retrieve his new laptop. In The Lord of the Rings , Aragorn (accepting his role as the heir to the king of the West) had the sword of Elendil , called Narsil , reforged (which symbolizes the reuniting of the race of man under one leader). Cueball obviously views the UPS building as a dangerous and impenetrable fortress, and possession of such a sword is the only way to guarantee success in his quest. Ironically, when the Elves come to deliver the new sword, the delivery elf is unable to notify anyone in the house, and simply leaves another delivery notification. In the title text, Rivendell is one of the home of the Elves, where the broken shards of Narsil resided, with Elrond and his elves. Unfortunately for Cueball, the sorting depot of Rivendell has the same, limited opening hours as the UPS. It is apparent that Cueball will not be getting his laptop in time for his flight. [The first panel is a UPS InfoNotice®. Most of the text on it is just scribbles, though the company logo and header is clear.] [Cueball opens their door to see the InfoNotice® stuck on his door.] Cueball: What! I've been here all day! Cueball 2 (off-screen): Huh? Cueball: They have my laptop. [Cueball and Cueball 2 are standing next to each other. Cueball has his arms to his sides, in annoyance.] Cueball 2: So get it tomorrow. Cueball: I fly out in the morning and they don't open till noon! Cueball 2: Sucks. [Cueball stands, working on a laptop.] Cueball: It's right there . I can see the UPS building on the map. Cueball 2 (off-screen): Ok... [Dramatic zoom to the Cueball's upper torso and face, along with clenched fist.] Cueball: My laptop is there. Cueball: It's mine . Cueball: I'm going to get it. [Even more dramatic zoom! Cueball's face fills the panel.] Cueball 2 (off-screen): They won't let you. Cueball: Who are they to keep from me what is mine? Cueball 2 (off-screen): Dude, they— [Zoomed out on Cueball, who spins around, raising a finger.] Cueball: A quest is at hand! Cueball 2(off-screen): Security's gonna throw you out. Cueball: I fear neither death nor pain. But I will not go unarmed. [Three inset panels overlap, in a montage format.] [Elves in long robes stand around a table, on which lies a broken sword.] Light the beacons and send word to the Elves. They must reforge the sword of my fathers. [An Elf beats the sword together on an anvil.] [An Elf rides a horse, silhouetted by the full moon.] Ere dawn, I will go forth to the Sorting Depot. [The Elf knocks at the door, sword in scabbard held under arm.] Knock knock knock knock [Cueball opens the door, to find a second InfoNotice® stuck on top of the first. The Elf is gone.]

Fight Club

Fight Club

https://www.xkcd.com/922

https://www.explainxkcd.com/wiki/index.php/922:_Fight_Club

Friend: But Fight Club isn't really about fighting. It's about the way society— Cueball: Nope, don't wanna hear it. Friend: But it says consumers are— Cueball: This conversation is over. The first rule of talking to me about movies is do NOT talk about Fight Club.

Fight Club is a movie starring Brad Pitt and Edward Norton that was released in 1999, based on the novel of the same name by Chuck Palahniuk. It included this oft-quoted and parodied line: "The first rule of Fight Club is you do not talk about Fight Club." The movie has been fiercely debated by critics, primarily regarding whether it makes a sophisticated philosophical statement about society and consumerism or whether it is just a movie with lots of fighting and mischief . Randall explains his position in the title text, claiming that he lies somewhere in-between and does not want to debate this issue with others. "This conversation is over" is also a line from the movie, in the scene where the Narrator (Edward Norton) is arguing with Marla Singer (Helena Bonham Carter) while Tyler (Brad Pitt) tells the Narrator what to say from the bottom of the basement stairs. Friend: But Fight Club isn't really about fighting. It's about the way society— Cueball: Nope, don't wanna hear it. Friend: But it says consumers are— Cueball: This conversation is over. The first rule of talking to me about movies is do NOT talk about Fight Club.

Strunk and White

Strunk and White

https://www.xkcd.com/923

https://www.explainxkcd.com/wiki/index.php/923:_Strunk_and_White

[Hairbun, with glasses, sits behind a desk typing on a computer. A line goes from the keyboard indicating that the text above is the one she types. Behind her stand Cueball with a book in his hand, and a man with male-pattern baldness holding up a smoking pipe.] Dear Internet, We, the current editors of Strunk & White's The Elements of Style , must—with great reluctance— clarify a point of orthography: "Strunk & White" should be used for the style manual and "Strunk/White" for the erotic fan fiction pairing. E.B. White is mentioned again in the later comics, 2162: Literary Opinions and 1087: Cirith Ungol .

The 1918 writing style guide The Elements of Style , by Cornell University professor William Strunk Jr. and New Yorker writer E.B. White (perhaps better known as the author of Charlotte's Web and Stuart Little ), is commonly referred to as " Strunk & White ". In this comic, the current editors of Strunk & White are clarifying a matter of style pertaining to the style guide, an instance of meta humor , a recurring theme in xkcd . Erotic fan fiction is a genre of writing in which fans make up erotic stories involving characters from non-erotic stories. " Slash fiction " is a subgenre that pairs characters of the same sex: These pairings are denoted by using the "/" to separate the paired characters, hence the name "slash fiction". This convention is generally thought to originate with the Kirk/Spock pairing in Star Trek fan fiction, wherein "K/S" was used for such romantic or erotic works of fan fiction, while "K&S" was used for non-romantic works. This comic imagines a similar distinction being necessary for " Strunk & White " vs. "Strunk/White". The title text comments that authors of Strunk/White fan fiction will most likely have read The Elements of Style , which makes them better writers. [Hairbun, with glasses, sits behind a desk typing on a computer. A line goes from the keyboard indicating that the text above is the one she types. Behind her stand Cueball with a book in his hand, and a man with male-pattern baldness holding up a smoking pipe.] Dear Internet, We, the current editors of Strunk & White's The Elements of Style , must—with great reluctance— clarify a point of orthography: "Strunk & White" should be used for the style manual and "Strunk/White" for the erotic fan fiction pairing. E.B. White is mentioned again in the later comics, 2162: Literary Opinions and 1087: Cirith Ungol .

3D Printer

3D Printer

https://www.xkcd.com/924

https://www.explainxkcd.com/wiki/index.php/924:_3D_Printer

[Two people before a 3D printer, one with a wrench.] Cueball: 3D printers are getting incredible. Ponytail: I think we're not far from widespread deployment. Ponytail: And you know what that means. Cueball: Spam containing actual enlarged penises? Ponytail: I give it a week.

With the ongoing development of 3D printing technology, the cost of low end 3D printers continues to reduce steadily, and the complexity of modelling and producing components is becoming easier. These factors, among others, means that 3D printers are beginning to be found in homes, rather than exclusively in businesses. Ponytail & Cueball are discussing the improvements and expect widespread deployment soon. Spam emails promoting penis-enlargement products are very common, and often show images of unnaturally large penises to advertise how effective they are. The adverts prevalence and aggressive marketing techniques have made them a well known staple of email inboxes, though the improvement of spam filters has increasingly banished them to the spam folder. Cueball and Ponytail predict that the spam producers will quickly jump on the opportunity presented by the widespread prevalence of 3D printers, and start advertising their wares with 3D printed phalluses. Usually someone would have to proactively choose to print out a spam email, but it wouldn't be difficult to imagine a scenario where the email contains malicious code which automatically prints them a huge phallus. In the title text, Better Homes and Gardens is an American magazine that, as the name suggests, shows you how to make your home and garden better often by reusing common household items in new and innovative ways. Acrylonitrile-butadiene-styrene (or ABS) is a light-weight and moldable plastic which makes it perfect for 3D printers. [Two people before a 3D printer, one with a wrench.] Cueball: 3D printers are getting incredible. Ponytail: I think we're not far from widespread deployment. Ponytail: And you know what that means. Cueball: Spam containing actual enlarged penises? Ponytail: I give it a week.

Cell Phones

Cell Phones

https://www.xkcd.com/925

https://www.explainxkcd.com/wiki/index.php/925:_Cell_Phones

[Cueball holds a cellphone. Black Hat is sitting at a desk with a laptop.] Cueball: Another huge study found no evidence that cell phones cause cancer. What was the W.H.O. thinking? Black Hat: I think they just got it backward. [Black Hat turns towards Cueball in an unframed panel, holding the laptop with one hand by the upper edge of the screen. Cueball is not visible.] Cueball: Huh? Black Hat: Well, take a look. [There is a plot of total cancer incidence and cell phone users. Cancer rises from 1970 to 1990, then stays relatively steady. Cell phone use rises from roughly 1984, and steeply after 1990, to the present.] Cueball: You're not... There are so many problems with that. Black Hat: Just to be safe, until I see more data I'm going to assume cancer causes cell phones.

This comic is a good explanation of the correlation/causation fallacy, where one party states two unrelated events and posits that they must have influenced each other. After hearing about the "Cell Phones Don't Cause Cancer" study, which refutes a claim made by the World Health Organization (just Google the debate or check out Wikipedia's article on it , the comic doesn't focus much on it), Black Hat plots "Total Cancer Incidence" per 100,000 and "Cell Phone Users" per 100 on the same graph. The graph in frame 3 shows an exponential rise in cancer in the 70's and 80's, followed by an exponential rise in cell phone usage in the 2000's. Black Hat reverses the correlation/causation fallacy, and comically comes to the conclusion that cancer causes cell phones . The comic highlights a well-known fallacy known as post hoc ergo propter hoc , often shortened to simply post hoc. The Latin translates to "after this, therefore because of this," referring to the common mistake that because two events happen in chronological order, the former event must have caused the latter event. The fallacy is often the root cause of many superstitions (e.g., a person noticing he/she wore a special bracelet before getting a good test score thinks the bracelet was the source of his/her good fortune), but it often crosses into more serious areas of thinking. In this case, the scientific research community, which often prides itself on its intellectual aptitude, is gently mocked for being nonetheless prone to such poor reasoning all too often. The different possibilities are generally known as causation, when one thing is proven to cause another, or correlation, when changes in one thing are aligned with changes in another, but there is no proof that they are directly related. The title text refers to the way Black Hat holds the laptop in panel 2. Being that Cueball (and Randall, for that matter) are quite into computers, the potential damage to a laptop screen either from the weight of its lower body or the pressure of the user's fingers on the LCD screen is enough to make him squirm in discomfort. The risk of dropping the computer is also present. [Cueball holds a cellphone. Black Hat is sitting at a desk with a laptop.] Cueball: Another huge study found no evidence that cell phones cause cancer. What was the W.H.O. thinking? Black Hat: I think they just got it backward. [Black Hat turns towards Cueball in an unframed panel, holding the laptop with one hand by the upper edge of the screen. Cueball is not visible.] Cueball: Huh? Black Hat: Well, take a look. [There is a plot of total cancer incidence and cell phone users. Cancer rises from 1970 to 1990, then stays relatively steady. Cell phone use rises from roughly 1984, and steeply after 1990, to the present.] Cueball: You're not... There are so many problems with that. Black Hat: Just to be safe, until I see more data I'm going to assume cancer causes cell phones.

Time Vulture

Time Vulture

https://www.xkcd.com/926

https://www.explainxkcd.com/wiki/index.php/926:_Time_Vulture

[Cueball is watching a large black bird, with apparently fractal wings, which hovers above his Cueball-like friend who walks towards Cueball and now turns to look at the bird over his shoulder.] Cueball: Dude, you've got a Time Vulture. Friend: Holy crap! What is it? [Zoom-in on Cueball who now looks at his friend who are now standing close to Cueball looking up at the bird off-panel.] Cueball: They're predators that use aging to kill prey. Friend: Huh? What do you mean? [The panel zooms in on the Cueball's face. The friends reply comes from off-panel.] Cueball: They live for millennia and use little energy. They can slow down their internal clocks so time speeds past. To hunt, they lock on to some prey, and when it stops moving, they eat it. Friend (off-panel): But what if the prey doesn't die? [Zoom out to Cueball and his friend that now look at each other.] Cueball: I don't think you quite understand. Friend: I mean, I'm not about to die... Cueball: From the vulture's viewpoint, everyone says that moments before they do.

This comic is about the time vulture (hence the title), a fictional creature made up by Randall . Cueball notices that his Cueball-like friend is followed by a time vulture, making the exclamation Dude, you've got a time vulture. The primary food source for vultures is carrion, or rotting meat. A time vulture, as explained by Cueball, is a type of vulture that can live for millennia , spending very little energy and it can even slow down its internal clocks so time speeds past, a kind of forward time travel, to the point where its prey dies. In this way, it can thus always wait long enough for the prey to die of natural causes no matter how long it takes, as seen from the prey's point of view. So in principle they kill their prey by using aging, as Cueball explains, although in fact, like any vulture, they just find prey that has already (almost) died, as from their point of view every living thing is just about to die. But as with other vultures, they do not participate in the actual killing. Time vultures thus just need to locate and find any one living creature (of a reasonable size), then it becomes it’s prey as it then just waits until it dies, spending hardly any energy while it waits. Real soaring vultures can also stay afloat for considerable time spans without actually using any energy as they just float on thermals . Thus the time vulture will now keep soaring over Cueball’s friends head for the rest of his life, or until they travel on an airplane (airplanes typically cruise at an altitude too high for a vulture to fly over them, although it is of course possible that the vulture could board the plane as well), and then when he dies (whenever and of whichever cause), it will descend and feast on his carcass. This should, in principle, not make any difference to the friend, since most people already live with the knowledge that they will eventually die [ citation needed ] , and that their body will end up being destroyed one way or another. Typically it will not be caused by vultures, but for instance by the fire of the Crematory or by the decomposition caused by small animals and germs in the earth we are buried in. However, it is not very nice to be reminded of this every living second of the rest of your life thus the consternation of the friend and his question and statement; But what if the prey doesn't die? and I'm not about to die... At first, the question doesn’t make sense since there are no known examples of terrestrial animals (including humans) that are large enough to matter as prey for a vulture and can survive through the several millennia that a time vulture can wait. The few species that can live that long and grow at least as large as vulture prey, such as the 2,384 acre (965 hectare) "Humongous Fungus", an individual of the fungal species Armillaria solidipes in the Malheur National Forest , thought to be between 2,000 and 8,500 years old [1] [2] , and a Great Basin bristlecone pine ( Pinus longaeva ) measured by ring count to be over 5000 years old. [3] , are stationary, such as fungi and plants, or aquatic, such as coral and sponges. Thus, the moving land species large enough to be attractive as prey will always die within the lifespan of the vulture (as Cueball tries to explain). However, the question actually does make sense, because the prey does not have to outlive the vulture to avoid being eaten by the vulture; it simply has to live long enough to get to an airport, get through security screening, and board a flight that goes either too fast or too high for the vulture to follow. Therefore, the vulture would get to eat the prey only if the prey died on the way to the airport, while standing outdoors in line for security screening, or while walking from the terminal to the airplane (if passengers board outdoors instead of using a passenger boarding bridge (Jetway) ). It is possible that the prey might not die this soon, unless security screening lines exceed the maximum human lifespan of approximately 120 years. And because the time vulture can slow down its internal clock, in its point of view, everyone who ever says "But, I'm not about to die", would say so right before they die; actually anything a person ever says after the time vulture has locked on to that person, happens just before they die as seen from the vulture's point of view. In humans' point of view, it could be many years after the statement was made, but for the time vulture, a human lifespan only lasts a mere moment. Of course, since a human can travel a considerable distance in this time, even around the world, the human would be traveling at an extremely high velocity from the vulture's perspective, so the vulture would be unable to keep up and the human would escape. In a more extreme fashion, since the vulture’s perception of time is significantly slowed, it would be more simple to buy a rifle and kill the Time Vulture. It is thus really more of a philosophical comic about the fact that we all have death waiting for us, you could say it soars above our head and just wait for it to happen. And in relation to the deep time of the geology of the Earth or the expansion of the universe, the time it takes for people to live their lives is hardly worth mentioning... In the title text it is stated that all real life vultures are actually a kind of time vultures, as real life vultures also sometimes spot a dying animal, not quite dead yet, and then wait for this prey to die. But time vultures are able to wait for millennia for their prey to die, whereas regular vultures do not have that kind of time, before they need to feed or land, thus the comment that some vultures have more patience than others. Real vultures and their preying habits was referenced in 1746: Making Friends , directly in the title text. [Cueball is watching a large black bird, with apparently fractal wings, which hovers above his Cueball-like friend who walks towards Cueball and now turns to look at the bird over his shoulder.] Cueball: Dude, you've got a Time Vulture. Friend: Holy crap! What is it? [Zoom-in on Cueball who now looks at his friend who are now standing close to Cueball looking up at the bird off-panel.] Cueball: They're predators that use aging to kill prey. Friend: Huh? What do you mean? [The panel zooms in on the Cueball's face. The friends reply comes from off-panel.] Cueball: They live for millennia and use little energy. They can slow down their internal clocks so time speeds past. To hunt, they lock on to some prey, and when it stops moving, they eat it. Friend (off-panel): But what if the prey doesn't die? [Zoom out to Cueball and his friend that now look at each other.] Cueball: I don't think you quite understand. Friend: I mean, I'm not about to die... Cueball: From the vulture's viewpoint, everyone says that moments before they do.

Standards

Standards

https://www.xkcd.com/927

https://www.explainxkcd.com/wiki/index.php/927:_Standards

How Standards Proliferate (See: A/C chargers, character encodings, instant messaging, etc.) Situation: There are 14 competing standards. Cueball: 14?! Ridiculous! We need to develop one universal standard that covers everyone's use cases. Ponytail: Yeah! Soon: Situation: There are 15 competing standards.

For any engineering task, there are numerous ways a given problem can be solved. The more complex the task, the more room for diversity. That's all well and good for a one-off problem, but if a design is meant to be iterated over time, or if an entire industry is solving that same problem, part reuse and interoperability become issues to deal with. Technical standards thus came to exist so that industries could avoid wasting resources reinventing the wheel , whilst offering their clients a certain amount of simplicity and compatibility between vendors. But, standards have issues of their own. They don't accommodate every use case , they might have restrictions or royalties attached, and people tend to be plagued by Not Invented Here syndrome . So, competing standards have a tendency to arise to address different perceived needs. After a while, the market for competing standards gets messy and hard to follow, and integrating systems built around competing standards gets burdensome. As a result, someone eventually takes on the challenge of creating a universal standard that everyone can rally around. This almost never works. In many cases, a new standard fails to displace the incumbent standards, eventually loses funding and support, and thus becomes a relic of history. In many other cases, it only penetrates far enough to survive, ironically making the situation messier. The latter situation often ends up becoming cyclical, with new standards periodically rising and failing to gain traction. Three examples are given at the top of the comic: AC chargers , character encoding and instant messaging . The title text mentions mini-USB and micro-USB, which were different standards used in 2011. As of 2019 for most applications of small USB ports (especially for charging / connecting cell phones), mini USB has lost most of its relevance and micro USB is competing with USB-C, as well as some solutions only used by single companies (such as Apple). Not all standards are created equal. In the development of standards , private standards adopt a non-consensus process in comparison to voluntary consensus standards. Private standards in the Information and Communications Technology (ICT) sector and the agri-food industry (governed by the Global Food Safety Initiative ) are discussed in a publication from International Organization for Standardization. How Standards Proliferate (See: A/C chargers, character encodings, instant messaging, etc.) Situation: There are 14 competing standards. Cueball: 14?! Ridiculous! We need to develop one universal standard that covers everyone's use cases. Ponytail: Yeah! Soon: Situation: There are 15 competing standards.

Mimic Octopus

Mimic Octopus

https://www.xkcd.com/928

https://www.explainxkcd.com/wiki/index.php/928:_Mimic_Octopus

[Captions above the panel:] Southeast Asian Sea Life Identification Chart [The chart consist of 14 black silhouettes which includes eight individual fish and several other object/animals. From top left: A Moorish idol, unknown fish, a rockfish, a clownfish, unknown fish, a lionfish, a shark, a sea lily, an w|angler fish, an anchor with chain, a submarine, a scuba diver, a school of seven large and four small fish, and and at the bottom right a silhouette of an octopus displaying eight arms and a tilted head with large white eyes. All 14 are labeled the same except the octopus:] Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Two Mimic Octopuses

This comic is a parody of fish and sea-life identification charts, referencing the mimic octopus which, as the name implies, is able to mimic other animals, so all animals and objects found in the sea could actually just be such an animal. The identification chart for South East Asian sea life shows 13 creatures mimicked including eight individual fish (two of which are not yet recognized) and other objects and animals. In order, top-to-bottom, left-to-right: A Moorish idol (Gill, from Finding Nemo ) , unknown, a rockfish , a clownfish , unknown, a lionfish , a shark , a sea lily , an angler fish , an anchor , a submarine , a scuba diver and school of 11 fish . Finally there is an octopus , but rather than being the mimic octopus in its natural form it's actually two of them each mimicing part of an octupus. The Orson Scott Card novel that the title text refers to is Lost Boys : "A withdrawn eight-year-old in a troubled family invents imaginary friends who bear the names of missing children" (Publisher's Weekly). The part of the story that Randall is referring to (Chapter 7, Crickets) involves a situation where the protagonist, Stevie, is given a C grade for an otherwise impeccable diorama featuring underwater animals involving clay sculptures (when only a poster would have sufficed) and a well-written presentation supposedly because the other children had destroyed the diorama before the end of the day. To make matters worse, his teacher, Ms. Jones, had made fun of his project and given the ribbon for first prize to someone else. On inquiring about, his father, Step, found out that the principal, Dr. Mariner, had already made the decision to hand Stevie the blue ribbon for first prize as she had reviewed the project before it had been destroyed, but Ms. Jones had secretly overruled her behind her back by announcing that another child (JJ) would receive the ribbon. So, the next day he met up with Ms Jones after school to have a word on the grading of his project. Needless to say, they ended up arguing about minor issues, with Mrs. Jones justifying the reason for her decision on, among other things, the definition of a 'depiction', whether or not the amount of content was defined by the word count or the number of pages and of the importance of putting the report in a plastic cover. The argument finally comes to a head when Step points out that there was only one red mark on the project report, and that concerned an 'incorrect' pluralization of the word 'octopus' “But Mrs. Jones, surely you know that the plural of “octopus” is either ‘octopus’, with nothing added, or ‘octopuses’.” “I think not,” said Mrs. Jones. “Think again, Mrs. Jones.” She must have realized that she was not on firm ground here. “Perhaps ‘octopuses’ is an alternate plural, but I’m sure that ‘octopi’ is the preferred.” “No, Mrs. Jones. If you had looked it up, you would have discovered that ‘octopi’ is not the preferred spelling. It is not a spelling at all. The word does not exist, except in the mouths of those who are pretending to be educated but in fact are not. This is because the ‘us’ ending of ‘octopus’ is not a Latin nominative singular ending, which would form its plural by changing to the letter ‘i’. Instead, the syllable ‘pus’ in ‘octopus’ is the Greek word for ‘foot.’ And it forms its plural the Greek way. Therefore ‘octopoda’, not ‘octopi’. Never ‘octopi’.” “Well, then, octopoda. Your son’s paper said octopuses.” “I know,” said Step. “When he asked me the correct plural, I told him octopoda. But then he was still uncertain, because my son doesn’t think he knows something until he knows it, and so he looked it up. And to my surprise, octopoda is only used when referring to more than one species of octopus, rather than when referring to more than one actual octopus. What Stevie put in his paper is in fact the preferred dictionary usage. Which you would have known, too, if you had looked it up.” After proving his case that his son did indeed deserve an A grade, he then threatened to bring the matter to the attention of the principal. He then warned Mrs Jones that while he wanted the grade to remain unchanged, he wanted her to inform the class that the ribbon would be awarded to Stevie, before revealing that he had been recording the conversation all along. And, after this, after Mrs Jones came crying for forgiveness before leaving, Step realized how vulnerable she was and how she was channeling her frustration at one particular student in each class to find some relief from that. According to the Merriam-Webster Dictionary , 'octopi', 'octopuses', and 'octopodes' (UK English) are all correct plural versions of "octopus." Supposedly, Randall would very much like the word 'octopi' to remain unrecognized by major dictionaries as otherwise it would lessen the magnitude of the climactic conclusion of this argument by rendering Step's mockery of Ms. Jones' perceived intellectual superiority factually invalid. This also offers another reason why the octopus in the chart is named two mimic octopuses , so Randall can use the correct pluralization of the word in the comic. This is an example of a comic where the title text seems more important to Randall than the actual comic. It should be noted that, at least according to Etymology Dictonary , Octopi is wrong for exactly the reasons that Step lists and first appears over 60 years later. [Captions above the panel:] Southeast Asian Sea Life Identification Chart [The chart consist of 14 black silhouettes which includes eight individual fish and several other object/animals. From top left: A Moorish idol, unknown fish, a rockfish, a clownfish, unknown fish, a lionfish, a shark, a sea lily, an w|angler fish, an anchor with chain, a submarine, a scuba diver, a school of seven large and four small fish, and and at the bottom right a silhouette of an octopus displaying eight arms and a tilted head with large white eyes. All 14 are labeled the same except the octopus:] Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Mimic Octopus Two Mimic Octopuses

Speculation

Speculation

https://www.xkcd.com/929

https://www.explainxkcd.com/wiki/index.php/929:_Speculation

[Two Cueball-like guys are playing basketball. The right guy (Cueball) attempts to throw the basketball through the hoop, but it bounces off down to his friend. To the right Black Hat has his back to the other two while he is looking at his phone.] Friend: Do you seriously think everyone will move to Plus? It was hard enough getting them on Facebook. [The friend has caught the rebound and now passes the basketball back to Cueball. Black Hat is not shown.] Cueball: Do they have to? Cueball: My mom still uses AOL—it doesn't mean my social life has to happen there. [Only Cueball is shown. He passes the basketball to the right towards the off-pannel Black Hat.] Cueball: Universal adoption isn't everything. I mean, IRC is still— [Zoom in on the basketball as an arrow pierces the ball, forming a slight depression.] Thunk [Cueball looks to Black Hat who has a crossbow in one hand, he is still looking at the phone in his other hand. The ball with the arrow lies between them.] Cueball: You're not really the "catch" type, are you? Black Hat: I am not.

During a basketball game, the players discuss the nature of universal conformity. Facebook and Google+ are competing social networks ; at the time of this comic many people were switching to Plus over Facebook leading many to speculate that Facebook was in decline and that Plus would soon be the dominant social network. As of 2019, it seems that Facebook has successfully held its position as the Default Social Network™, while Google Plus was a colossal blunder for Google and was finally sunset for consumers in April 2019. The two players seem to have a disagreement over this. One player states that it would be ridiculous to expect everyone to move to Plus. The other player denies the notion that they have to, stating that he values his personal preference over conformity. He supports this idea by saying that his mother still uses AOL and other people continue using IRC and that if each time a new dominant social network emerged and everyone switched to it, neither of these things would stick around. They are interrupted when they pass the ball to Black Hat , who immediately shoots it with a crossbow bolt. Their arguments and rather intelligent discussion are derailed by the absurdity of Black Hat's reaction, which is both humorous and puts the issue in stark contrast. Black Hat neither joins in the discussion nor does he participate in the game. It seems that any offer to participate in either is met with a blunt and clear denial. He is simply not a conformist. A possible explanation for the joke is that while tech geeks or Google enthusiasts might discuss whether the world will move from Facebook to Plus, a number of people might simply ignore the debate and "shoot" the discussion dead by just ignoring the existence of anything that isn't Facebook. In the title text, Black Hat continues to provide an example of his tendency to play by his own rules. A clay pigeon is a clay disc that is thrown into the air and serves as a target on a skeet shooting range. Participants are expected to shoot the pigeons with a shotgun but Black Hat would rather capture the clay pigeons and shoot them from a very close range. (This is made even more humorous by the excellent crossbow skills he shows in the comic.) This practice eventually got him expelled from the shooting range. It is unclear whether Black Hat was good at shooting clay pigeons from farther away. [Two Cueball-like guys are playing basketball. The right guy (Cueball) attempts to throw the basketball through the hoop, but it bounces off down to his friend. To the right Black Hat has his back to the other two while he is looking at his phone.] Friend: Do you seriously think everyone will move to Plus? It was hard enough getting them on Facebook. [The friend has caught the rebound and now passes the basketball back to Cueball. Black Hat is not shown.] Cueball: Do they have to? Cueball: My mom still uses AOL—it doesn't mean my social life has to happen there. [Only Cueball is shown. He passes the basketball to the right towards the off-pannel Black Hat.] Cueball: Universal adoption isn't everything. I mean, IRC is still— [Zoom in on the basketball as an arrow pierces the ball, forming a slight depression.] Thunk [Cueball looks to Black Hat who has a crossbow in one hand, he is still looking at the phone in his other hand. The ball with the arrow lies between them.] Cueball: You're not really the "catch" type, are you? Black Hat: I am not.

Days of the Week

Days of the Week

https://www.xkcd.com/930

https://www.explainxkcd.com/wiki/index.php/930:_Days_of_the_Week

[The whole comic is a single panel, with a circular diagram of the days of the week.] Polar graph of what stuff happens on which days, based on number of Google results for phrases like "company meeting on <day>." The relative frequency of <day> in <phrase> is shown by the distance from the center at which <phrase>'s line crosses <day>. Each curve is normalized to have the same number of total hits - they're not on the same scale. (Not easy to reproduce the actual plot, these are the phrases, in order of popularity on Wednesday.) 1. <day> is ladies night 2. announced <day> 3. company meeting on <day> / company meeting <day> 4. due on <day> 5. got laid <day> 6. drunk on <day> / so drunk <day> 7. <day> is the big day 8. Church <day> 9. got my period <day> 10. we broke up on <day> 11. <day> sucked [Thursday, from most common to least common: 11, 2, 1, 3, 9, 4, 5, 7, 10, 6, 8] [Friday, from most common to least common: 10, 4, 6, 7, 5, 9, 11, 3, 2, 1, 8] [Saturday, ditto: 6, 7, 5, 11, 9, 10, 8, 3, 2, 1, 4] [Sunday, ditto: 8, 9, 7, 11, 10, 5, 6, 2, 3, 4, 1] [Monday, ditto: 4, 2, 9, 11, 3, 5, 10, 6, 7, 8, 1] [Tuesday, ditto: 3, 2, 4, 5, 1, 7, 9, 10, 11, 8, 6]

As explained in the image, the graph is a polar graph, charting the relative strengths by which certain phrases are associated with certain days of the week. The closer a phrase comes to the center of the graph, the less the phrase is associated with whatever day of the week that is. Conversely, the further out a phrase is, the more associated with that day of the week it is. Perhaps the clearest example of this in the above graph is the ladies night line, which has such a strong peak on Wednesday that it goes clear out of the bounds of the picture. Likewise, church is so strongly associated with Sunday that it goes off the chart there. Also of interest are the less eccentric orbits, for instance "big day" and "so drunk." The fact that these don't clearly peak on any one day indicates that (according to Google, at least) big days are spread out fairly evenly throughout the week (with a minimum on Mondays), and so drunk tends to peak on weekends, though it seems fairly evenly split between Fridays and Saturdays. Mentioned in the title text is Rebecca Black 's viral pop hit, Friday , which received considerable negative attention and ridicule for its terrible songwriting and performance. It peaks so far out that no perspective which would show it would be of any use, since many parodies have been made of the song since. [The whole comic is a single panel, with a circular diagram of the days of the week.] Polar graph of what stuff happens on which days, based on number of Google results for phrases like "company meeting on <day>." The relative frequency of <day> in <phrase> is shown by the distance from the center at which <phrase>'s line crosses <day>. Each curve is normalized to have the same number of total hits - they're not on the same scale. (Not easy to reproduce the actual plot, these are the phrases, in order of popularity on Wednesday.) 1. <day> is ladies night 2. announced <day> 3. company meeting on <day> / company meeting <day> 4. due on <day> 5. got laid <day> 6. drunk on <day> / so drunk <day> 7. <day> is the big day 8. Church <day> 9. got my period <day> 10. we broke up on <day> 11. <day> sucked [Thursday, from most common to least common: 11, 2, 1, 3, 9, 4, 5, 7, 10, 6, 8] [Friday, from most common to least common: 10, 4, 6, 7, 5, 9, 11, 3, 2, 1, 8] [Saturday, ditto: 6, 7, 5, 11, 9, 10, 8, 3, 2, 1, 4] [Sunday, ditto: 8, 9, 7, 11, 10, 5, 6, 2, 3, 4, 1] [Monday, ditto: 4, 2, 9, 11, 3, 5, 10, 6, 7, 8, 1] [Tuesday, ditto: 3, 2, 4, 5, 1, 7, 9, 10, 11, 8, 6]

Lanes

Lanes

https://www.xkcd.com/931

https://www.explainxkcd.com/wiki/index.php/931:_Lanes

[The panels are arranged top to bottom. The first is set above a larger image.] Friend: So, are you guys out of the woods? Cueball: We don't know. Friend: Well, did the treatment work? Cueball: We don't know. [Cueball's next few lines are set by themselves in their own panels, arranged around a larger image.] Cueball: I always assumed that when you got cancer, they gave you a prognosis, then treated you, and at the end of treatment either you beat it or you died. [The diagram shows a simple highway. Starting at the bottom, with diagnosis for five lanes, the road travels through a cloud of treatment, after which two lanes disappear, and three continue. Later on, there's another off-ramp labeled 'cancer "comes back"', which loops back into the treatment cloud. Otherwise, the highway enters a later cloud called survive.] Cueball: And I knew sometimes it "recurred," which I assumed meant back to square one. Cueball: But that's turned out not to be quite right. [Back to Cueball and his friend.] Cueball: Once most cancers spread out into your body, they're incurable. Cueball: If your 10-year prognosis is 60%, that means a 40% chance that some cancer will slip past the treatment and get out. [The frame zooms in to show just Cueball.] Cueball: So they kill all the cancer they can find, and then you're a "survivor." But your odds are still 60%. [The panel zooms in further, now showing only Cueball's top half.] Cueball: They can't scan for individual cancer cells. The only way to know if it worked is to wait for tumors to pop up elsewhere. Cueball: If you go enough years without that happening then you were in the 60%. [The frame shows both people again.] Cueball: And often the first sign is a cough or bone pain. Cueball: So you spend the next five or ten years trying not to worry that every ache and pain is the answer to the question "Do I make it?" [There's an extra large panel, with a small one floating inside it.] [The panel shows fifty-two lanes emerging from the cloud of 'Treatment'. Signs show 1 year, 2 years, 3 years, 4 years, 5 years, 6 years. Lanes branch off and fade into darkness earlier on the right, with some lanes continuing off the top of the panel.] [Inset panel.] Friend: Man. Friend: Fuck cancer. Cueball: Seriously.

xkcd is a webcomic of romance , sarcasm , math , and language : humor isn't necessarily guaranteed. This comic is an example of that, it being severely depressing. The comic is built around a dialogue between two people (we'll say Cueball is the one talking, and the other is his friend) about cancer, presumably cancer that Megan has been diagnosed with. The conversation itself is about as straightforward as a conversation can be. It details the maturation of Cueball 's and Megan 's understanding of cancer diagnoses, knowledge which we can presume he has gained, reluctantly, by watching a loved one suffer. This whole cancer series was sparked because Randall 's then-fiancee, now wife, is currently in Megan's position, and we, the readers, are now the beneficiaries of this new understanding of cancer diagnoses without having to watch somebody close to us suffer. The comic's title, Lanes, comes from the two panels which illustrate both ends of the spectrum of Cueball's mental representation of how cancer treatment proceeds. In that there are many possible outcomes for cancer treatment, the image of a multi-lane freeway seems an apt metaphor to represent this understanding visually. In the first freeway diagram, there are several paths, but the system is very simple, and easy to take in. Only a few lanes lead off into the oblivion which surrounds the freeway, a single off-ramp circles back from the path to survival to treatment, and survival is a visible endpoint. In the second freeway diagram, however, things are much, much more complex, and much more bleak. Even six years out, survival isn't visible, and many lanes end in oblivion, sometimes not veering off for years after treatment. The title text informs us that this is meant to be loosely representative of breast cancer stages one through four, proceeding by quarters from left to right. It's a grim outlook, hence the friend's understated but completely fitting reaction to this plethora of new knowledge. Specific numbers: There are 52 lanes, so 13 lanes per cancer stage. Stage 1 has a 1:12 = ~8% chance of recurrence leading to death within 6 years. Stage 2 has a 5:8 = ~38% chance. Stage 3 has an 8:5 = ~62% chance. Stage 4 has an 11:2 = ~85% chance of death within 6 years. The opening line of "being in the woods" is revisited in 1928: Seven Years , where Cueball and Megan are shown walking through a forest in a cancer-themed strip. [The panels are arranged top to bottom. The first is set above a larger image.] Friend: So, are you guys out of the woods? Cueball: We don't know. Friend: Well, did the treatment work? Cueball: We don't know. [Cueball's next few lines are set by themselves in their own panels, arranged around a larger image.] Cueball: I always assumed that when you got cancer, they gave you a prognosis, then treated you, and at the end of treatment either you beat it or you died. [The diagram shows a simple highway. Starting at the bottom, with diagnosis for five lanes, the road travels through a cloud of treatment, after which two lanes disappear, and three continue. Later on, there's another off-ramp labeled 'cancer "comes back"', which loops back into the treatment cloud. Otherwise, the highway enters a later cloud called survive.] Cueball: And I knew sometimes it "recurred," which I assumed meant back to square one. Cueball: But that's turned out not to be quite right. [Back to Cueball and his friend.] Cueball: Once most cancers spread out into your body, they're incurable. Cueball: If your 10-year prognosis is 60%, that means a 40% chance that some cancer will slip past the treatment and get out. [The frame zooms in to show just Cueball.] Cueball: So they kill all the cancer they can find, and then you're a "survivor." But your odds are still 60%. [The panel zooms in further, now showing only Cueball's top half.] Cueball: They can't scan for individual cancer cells. The only way to know if it worked is to wait for tumors to pop up elsewhere. Cueball: If you go enough years without that happening then you were in the 60%. [The frame shows both people again.] Cueball: And often the first sign is a cough or bone pain. Cueball: So you spend the next five or ten years trying not to worry that every ache and pain is the answer to the question "Do I make it?" [There's an extra large panel, with a small one floating inside it.] [The panel shows fifty-two lanes emerging from the cloud of 'Treatment'. Signs show 1 year, 2 years, 3 years, 4 years, 5 years, 6 years. Lanes branch off and fade into darkness earlier on the right, with some lanes continuing off the top of the panel.] [Inset panel.] Friend: Man. Friend: Fuck cancer. Cueball: Seriously.

CIA

CIA

https://www.xkcd.com/932

https://www.explainxkcd.com/wiki/index.php/932:_CIA

[A television is showing Blondie as a news anchor. The inset picture of the news shows the logo of LulzSec, a man wearing a monocle and top hat.] Blondie: Hackers briefly took down the website of the CIA yesterday... [Ponytail, sitting in an armchair, is watching a television (seen from the side) standing on a table hearing what Blondie says as indicated with a zigzag line from the TV. Above the top part of the frame is a smaller frame with a label:] What people hear: Blondie (not shown from the TV): Someone hacked into the computers of the CIA!! [Megan, sitting in an armchair, is watching a television (seen from the side) standing on a table hearing what Blondie says as indicated with a zigzag line from the TV. Above the top part of the frame is a smaller frame with a label:] What computer experts hear: Blondie (not shown from the TV): Someone tore down a poster hung up by the CIA!!

Blondie as a news anchor is reporting on a hacker attack on the CIA (hence the title). This comic is a reference to the attacks by a group briefly known as LulzSec , which was a splinter group from the internet community known as Anonymous , also featured in 834: Wikileaks . In the back of the news report in frame one is the logo that was used by LulzSec. The group was able to publicize several high profile attacks. They were able to briefly take down the CIA website using a DDoS attack. DDoS stands for Distributed Denial of Service in which the attacker uses many computers to send traffic to a host and render it incapable of answering requests from any other computer, effectively taking the site down. This comic is pointing out the difference between what lay-people ( Ponytail ) and the computer expert ( Megan ) hear when seeing a story like this. Most people may think there is no boundary between the CIA website and its internal network, and conclude hackers compromised the USA intelligence service's most precious data, which would be an incredible display of incompetence by the CIA and would have some pretty obvious negative side effects for CIA assets around the world. Computer experts, on the other hand, may compare the CIA website to a company's poster, so the damage done is much different and less harmful: the CIA's public relation capacities are hindered for a few hours. The damage from a DDoS is less a catastrophic compromise of valuable federal databases, and more like flash mob crowding in the lobby of the CIA offices, making life mildly inconvenient. The title text is a transcript of a made up news report. A story similar to the attack is illustrated using old technology. This attempts to demonstrate how silly the news coverage of the real event is. The recruiting poster refers to the CIA website, as it is a PR tool with no connection to sensitive information. It being ten feet high refers to the fact that that the website is open to the public and has limited protections (as danger from a compromised site is low). The ladder technology refers to the DDoS attack, as these attacks are primitive, but possibly well coordinated. The plexiglass poster covers refer to website security tools that may be added to deter future vandalism. [A television is showing Blondie as a news anchor. The inset picture of the news shows the logo of LulzSec, a man wearing a monocle and top hat.] Blondie: Hackers briefly took down the website of the CIA yesterday... [Ponytail, sitting in an armchair, is watching a television (seen from the side) standing on a table hearing what Blondie says as indicated with a zigzag line from the TV. Above the top part of the frame is a smaller frame with a label:] What people hear: Blondie (not shown from the TV): Someone hacked into the computers of the CIA!! [Megan, sitting in an armchair, is watching a television (seen from the side) standing on a table hearing what Blondie says as indicated with a zigzag line from the TV. Above the top part of the frame is a smaller frame with a label:] What computer experts hear: Blondie (not shown from the TV): Someone tore down a poster hung up by the CIA!!

Tattoo

Tattoo

https://www.xkcd.com/933

https://www.explainxkcd.com/wiki/index.php/933:_Tattoo

[Megan is in the panel. Megan points at her chest.] Megan: I just have one tattoo - it's six dots on my chest, done by my oncologist. Megan: I need them for aligning the laser sights on a flesh-searing relativistic particle cannon, Megan: So it will only kill the parts of me [Dramatic zoom, the panel background is black, with white text.] Megan: That are holding me back. [The panel is larger, revealing who they're talking to.] Megan: But your barbed wire bicep tattoo is pretty hardcore, too! Cueball: No, it's OK. I'll just go put a shirt on.

An oncologist is a doctor who specializes in the treatment of cancer . This comic is certainly related to Randall's wife's breast cancer . Megan in this comic has a tattoo for the alignment lasers of the radiotherapy machine which will fire a beam of radiation with sufficient intensity to kill the cells in the targeted area. A common such machine is a linear accelerator or "Linac" which accelerates electrons to very high speed, these can then either be used to generate high energy X-rays to treat the patient, or the electron beam itself can be used (both are types of radiation; the electrons being beta radiation and x-rays being EM [electromagnetic] radiation). Commonly when radiotherapy is used as part of breast cancer treatment some combination of both is prescribed. In order to allow healthy tissue to recover better, rather than deliver all the radiation in one go, the treatment is delivered a little bit each day over the course of about a month. It is therefore vital that the radiation can be delivered to the correct target area day after day, and this is done by lining up the alignment lasers of the linac with the skin markers - that is Megan's tattoo dots. It may not be considered a "traditional" tattoo (because she says it was done by her oncologist and not in a tattoo parlor). In the last frame, it is mentioned that Cueball has a barbed wire bicep tattoo, which is common in the US as a tattoo that people get when they want to seem tough, even if they aren't tough already. The joke in the comic is that Cueball got this barbed wire tattoo to look tough, but it pales in comparison to the tattoo from (or for) the cancer removal or treatment. It is kind of funny because Cueball has his whole shirt off just to show a biceps tattoo. The title text references gamma ray therapy after describing electron linear accelerator-based treatment systems; however, technically gamma ray therapy only refers to radionuclide (i.e., Cobalt-60) based radiation therapy systems. In regards to a 90-second session killing a horse, typical dose rates of modern radiation therapy systems are of the order of several gray per minute for the field sizes used, for example, in the treatment of breast cancer . It is feasible that a single 90-second delivery of radiation could deliver over 10 Gy in a single instance to the specific areas of the body that could be fatal, such as neuropathy or radiation induced liver disease. [Megan is in the panel. Megan points at her chest.] Megan: I just have one tattoo - it's six dots on my chest, done by my oncologist. Megan: I need them for aligning the laser sights on a flesh-searing relativistic particle cannon, Megan: So it will only kill the parts of me [Dramatic zoom, the panel background is black, with white text.] Megan: That are holding me back. [The panel is larger, revealing who they're talking to.] Megan: But your barbed wire bicep tattoo is pretty hardcore, too! Cueball: No, it's OK. I'll just go put a shirt on.

Mac/PC

Mac/PC

https://www.xkcd.com/934

https://www.explainxkcd.com/wiki/index.php/934:_Mac/PC

[Two Cueballs stand facing out of the screen.] Cueball #1: I'm a Mac Cueball #2: And I'm a PC. Cueballs: And since you do everything through a browser now, we're pretty indistinguishable.

This comic is a parody of the " Get a Mac " (also known as "I'm a Mac" or "Mac vs. PC") ad campaign for the Mac brand of computers. The ads personified the Mac and their competitors, the PC. The ads poked fun at the PC's terrible function while paying attention to the Mac's unique features. Each ad started with the duo introducing themselves as "I'm a Mac..." "...and I'm a PC." The comic, however, presents the differences between them as no longer of much importance, since most everything nowadays is done through browsers. In essence, using the same browser to visit the same website among different operating systems would give you an experience that is very much the same. Additionally, there is some self-referential humor here; both the Mac and PC are simple stick figures due to xkcd's style. Therefore, they are literally identical as far as appearance goes. The apotheosis of computing via a browser is probably the Chromebook , a range of laptops whose operating system is based upon the browser Google Chrome , and which first became commercially available a few weeks before this comic appeared. The title text refers to window management , which is software that controls windows on computers, and is in many ways similar to the more recent development of tabbed browsers. xmonad is one such program, and Randall says that eventually it will be an extension usable with the browser Firefox . What makes it somewhat unusual (and thus worth mentioning) is that it is a tiling window manager , meaning it automatically arranges and resizes newly opened program windows to fit a grid. This is especially useful on large screens. [Two Cueballs stand facing out of the screen.] Cueball #1: I'm a Mac Cueball #2: And I'm a PC. Cueballs: And since you do everything through a browser now, we're pretty indistinguishable.

Missed Connections

Missed Connections

https://www.xkcd.com/935

https://www.explainxkcd.com/wiki/index.php/935:_Missed_Connections

[The page is set up like the missed connections area of Craigslist, with a list of messages from an individual to a person they weren't able to communicate with at the time. All readable text is in blue. There is a large heading at the top:] Personals > Missed Connections [Below the heading there is a gray section in a black frame with two lines. The first line has a search box and a drop down menu with text and two black arrows to the right of it. The second line has three check boxes and two other boxes, all empty. all boxes has white background. Text is written many places around these boxes (and on the drop down menu), it is written in black, but none of it is readable.] [Below this gray section follows seven missed connections, the last being cut before the description of "Me" is finished, and the line visible is cut of, so the lower third of the letters are hidden below the comics frame.] You: Clinging to hood of your stolen Wienermobile, trying to reach into engine to unstick throttle Me: Screaming, diving out of the way You: Vaguely human silhouette Me: At bottom of wishing well with harpoon gun You: Confused UDP packet Me: Cisco router in 45.170/16 block You: Baddest fuckin' Juggalo at Violent J's party Me: Nancy Pelosi (D-Ca) You: Getting married to me Me: Also getting married, but distracted by my phone You: Cute boy on corner of 4th & Main, 5'11, 169lbs, social security number 078-05-1120, pockets contained $2.09 in change, keys, and a condom. Retinal scan attached Me: Driving street view van You: George Herman "Babe" Ruth Me: Fellow Time Lord. Saw your Tardis on third moon of

Missed Connections is a page on Craigslist in which people who saw each other briefly and want to reconnect attempt to find each other again. In the case of missed connections, one person describes themselves "Me" and describes the other person "You" in order that the second person would recognize themself and try to reconnect. The first entry appears to be a goofy joke, although there have been many Wienermobile incidents in the past. The second entry refers to a person (you) looking down into a wishing well (presumably to throw in a coin to get a wish), but someone (me) is sitting down in the well with a harpoon looking up spotting the silhouette at the top of the well. This seems like a very weird thing to do, and the vaguely human shadow may be lucky to be alive, since the only reason the "you" should know about the "me" is if the me fired the harpoon (and missed). A person sitting in a well telling people stuff (as if it was the well speaking) was the pun in 568: Well 2 . Oddly enough, this entry could possibly be a reference to this episode of The Fairly OddParents . The third entry is a reference to networking. UDP stands for User Datagram Protocol . UDP packets don't use handshaking to verify they have contacted the correct host, so they can get lost or confused. The Cisco router location is a block of IP addresses that was unallocated at the time when this comic was published but has been allocated to Latin America and Caribbean since then. Cisco is a company that makes networking equipment. This is a play on a missed connection for someone who was lost and asked for directions. The fourth entry is a reference to two events in 2011 in which President Barack Obama invited rappers--among other people--to the White House. After each event, right-wing commentators blasted the event as a party unbecoming of the dignity of the White House. Nancy Pelosi is the Democratic Leader of the US House of Representatives . The acronym (D-CA) is a common notation for politicians which notates party (D for Democrat) and state (CA for California). Pelosi would have also been invited to these events, and the missed connections listing is a reference to what the commentators imagined the event would have been like. A " juggalo " is a term referring to a fan of the rap group Insane Clown Posse (which includes rapper Violent J ), which is notorious for having a wild, misogynistic, and violent fanbase. The fifth entry is a straightforward joke. One of the two people getting married was so distracted by their phone they have no clue where their spouse is now, or even who they are. Alternatively, it could be that the second party deserted the wedding because they were frustrated by their partner being distracted by their cell phone during the wedding, and the first partner is now hoping to convince them to return. The sixth entry is a reference to how the Google Street View car was not only recording photos of the street in 360 degrees, it was also collecting data from unencrypted Wi-Fi networks. The comic takes this to the next level, that the Google Street View van also scans what we have in our pockets and does a retinal scan. In this case, the social security number referenced is the most used SSN of all time. The retinal scan takes this even further, indicating that Google's cameras are collecting fine enough images to identify people by Retinal scan . The entry gets a bit absurd when you realize with all this data, it should be trivial for the Google employee to ID and meet this young man, and would not need the Missed Connections page. The last entry suggests that Babe Ruth , the American baseball slugger of 1914-1935, is actually a Time Lord . Time Lord is a reference to the popular sci-fi series Doctor Who in which The Doctor, who is a Time Lord, uses a TARDIS , which is a time travel machine. Possibly because he was a baseball player "ahead of his time". The title text is another reference to the privacy concerns surrounding Google Street View van, to which Google responded by claiming that the street view camera wouldn't capture anything that someone walking by wouldn't be able to see. Randall is not worried about the street view van since he expects that Google will already know anything that such a van could discover from reading his e-mails. This last statement is of course much more serious than having a photo taken by a passing van, thus making it clear what people should fuss about, and it is not the van. [The page is set up like the missed connections area of Craigslist, with a list of messages from an individual to a person they weren't able to communicate with at the time. All readable text is in blue. There is a large heading at the top:] Personals > Missed Connections [Below the heading there is a gray section in a black frame with two lines. The first line has a search box and a drop down menu with text and two black arrows to the right of it. The second line has three check boxes and two other boxes, all empty. all boxes has white background. Text is written many places around these boxes (and on the drop down menu), it is written in black, but none of it is readable.] [Below this gray section follows seven missed connections, the last being cut before the description of "Me" is finished, and the line visible is cut of, so the lower third of the letters are hidden below the comics frame.] You: Clinging to hood of your stolen Wienermobile, trying to reach into engine to unstick throttle Me: Screaming, diving out of the way You: Vaguely human silhouette Me: At bottom of wishing well with harpoon gun You: Confused UDP packet Me: Cisco router in 45.170/16 block You: Baddest fuckin' Juggalo at Violent J's party Me: Nancy Pelosi (D-Ca) You: Getting married to me Me: Also getting married, but distracted by my phone You: Cute boy on corner of 4th & Main, 5'11, 169lbs, social security number 078-05-1120, pockets contained $2.09 in change, keys, and a condom. Retinal scan attached Me: Driving street view van You: George Herman "Babe" Ruth Me: Fellow Time Lord. Saw your Tardis on third moon of

Password Strength

Password Strength

https://www.xkcd.com/936

https://www.explainxkcd.com/wiki/index.php/936:_Password_Strength

The comic illustrates the relative strength of passwords assuming basic knowledge of the system used to generate them. A set of boxes is used to indicate how many bits of entropy a section of the password provides. The comic is laid out with 6 panels arranged in a 3x2 grid. On each row, the first panel explains the breakdown of a password, the second panel shows how long it would take for a computer to guess, and the third panel provides an example scene showing someone trying to remember the password. [The password "Tr0ub4dor&3" is shown in the center of the panel. A line from each annotation indicates the word section the comment applies to.] Uncommon (non-gibberish) base word [Highlighting the base word - 16 bits of entropy.] Caps? [Highlighting the first letter - 1 bit of entropy.] Common Substitutions [Highlighting the letters 'a' (substituted by '4') and both 'o's (the first of which is substituted by '0') - 3 bits of entropy.] Punctuation [Highlighting the symbol appended to the word - 4 bits of entropy.] Numeral [Highlighting the number appended to the word - 3 bits of entropy.] Order unknown [Highlighting the appended characters - 1 bit of entropy.] (You can add a few more bits to account for the fact that this is only one of a few common formats.) ~28 bits of entropy 2 28 = 3 days at 1000 guesses/sec (Plausible attack on a weak remote web service. Yes, cracking a stolen hash is faster, but it's not what the average user should worry about.) Difficulty to guess: Easy [Cueball stands scratching his head trying to remember the password.] Cueball: Was it trombone? No, Troubador. And one of the O's was a zero? Cueball: And there was some symbol... Difficulty to remember: Hard [The passphrase "correct horse battery staple" is shown in the center of the panel.] Four random common words {Each word has 11 bits of entropy.} ~52 bits of entropy 2 44 = 550 years at 1000 guesses/sec Difficulty to guess: Hard [Cueball is thinking, in his thought bubble a horse is standing to one side talking to an off-screen observer. An arrow points to a staple attached to the side of a battery.] Horse: That's a battery staple. Observer: Correct! Difficulty to remember: You've already memorized it Through 20 years of effort, we've successfully trained everyone to use passwords that are hard for humans to remember, but easy for computers to guess.

This comic says that a password such as "Tr0ub4dor&3" is bad because it is easy for password cracking software and hard for humans to remember, leading to insecure practices like writing the password down on a post-it attached to the monitor. On the other hand, a password such as "correct horse battery staple" is hard for computers to guess due to having more entropy but quite easy for humans to remember. Entropy is a measure of "uncertainty" in an outcome. In this context, it can be thought of as a value representing how unpredictable the next character of a password is. It is calculated as log2(a^b) where a is the number of allowed symbols and b is its length. A truly random string of length 11 (not like "Tr0ub4dor&3", but more like "J4I/tyJ&Acy") has log2(94^11) = 72.1 bits, with 94 being the total number of letters, numbers, and symbols one can choose. However the comic shows that "Tr0ub4dor&3" has only 28 bits of entropy. This is because the password follows a simple pattern of a dictionary word + a couple extra numbers or symbols, hence the entropy calculation is more appropriately expressed with log2(65000*94*94), with 65000 representing a rough estimate of all dictionary words people are likely to choose. (For related info, see https://what-if.xkcd.com/34/ ). Another way of selecting a password is to have 2048 "symbols" (common words) and select only 4 of those symbols. log2(2048^4) = 44 bits, much better than 28. Using such symbols was again visited in one of the tips in 1820: Security Advice . It is absolutely true that people make passwords hard to remember because they think they are "safer", and it is certainly true that length, all other things being equal, tends to make for very strong passwords and this can be confirmed by using rumkin.com's password strength checker . Even if the individual characters are all limited to [a-z], the exponent implied in "we added another lowercase character, so multiply by 26 again" tends to dominate the results. In addition to being easier to remember, long strings of lowercase characters are also easier to type on smartphones and soft keyboards . xkcd's password generation scheme requires the user to have a list of 2048 common words (log 2 (2048) = 11). For any attack we must assume that the attacker knows our password generation algorithm, but not the exact password. In this case the attacker knows the 2048 words, and knows that we selected 4 words, but not which words. The number of combinations of 4 words from this list of words is (2 11 ) 4 = 2 44 , i.e. 44 bits. For comparison, the entropy offered by Diceware's 7776 word list is 13 bits per word . If the attacker doesn't know the algorithm used, and only knows that lowercase letters are selected, the "common words" password would take even longer to crack than depicted. 25 random lowercase characters would have 117 bits of entropy , vs 44 bits for the common words list. Example Below there is a detailed example which shows how different rules of complexity work to generate a password with supposed 44 bits of entropy. The examples of expected passwords were generated in random.org.(*) If n is the number of symbols and L is the length of the password, then L = 44 / log 2 (n). a = lowercase letters A = uppercase letters 9 = digits & = the 32 special characters in an American keyboard; Randall assumes only the 16 most common characters are used in practice (4 bits) (*) The use of random.org explains why jAwwBYne has two consecutive w's, why Re-:aRo has two R's, why [email protected] ~"#^.2 has no letters, why ewpltiayq has no numbers, why "constant yield" is part of a password, etc. A human would have attempted at passwords that looked random. The title text likely refers to the fact that this comic could cause people who understand information theory and agree with the message of the comic to get into an infuriating argument with people who do not — and disagree with the comic. If you're confused, don't worry; you're in good company; even security "experts" don't understand the comic: Sigh. 🤦‍♂️ The comic illustrates the relative strength of passwords assuming basic knowledge of the system used to generate them. A set of boxes is used to indicate how many bits of entropy a section of the password provides. The comic is laid out with 6 panels arranged in a 3x2 grid. On each row, the first panel explains the breakdown of a password, the second panel shows how long it would take for a computer to guess, and the third panel provides an example scene showing someone trying to remember the password. [The password "Tr0ub4dor&3" is shown in the center of the panel. A line from each annotation indicates the word section the comment applies to.] Uncommon (non-gibberish) base word [Highlighting the base word - 16 bits of entropy.] Caps? [Highlighting the first letter - 1 bit of entropy.] Common Substitutions [Highlighting the letters 'a' (substituted by '4') and both 'o's (the first of which is substituted by '0') - 3 bits of entropy.] Punctuation [Highlighting the symbol appended to the word - 4 bits of entropy.] Numeral [Highlighting the number appended to the word - 3 bits of entropy.] Order unknown [Highlighting the appended characters - 1 bit of entropy.] (You can add a few more bits to account for the fact that this is only one of a few common formats.) ~28 bits of entropy 2 28 = 3 days at 1000 guesses/sec (Plausible attack on a weak remote web service. Yes, cracking a stolen hash is faster, but it's not what the average user should worry about.) Difficulty to guess: Easy [Cueball stands scratching his head trying to remember the password.] Cueball: Was it trombone? No, Troubador. And one of the O's was a zero? Cueball: And there was some symbol... Difficulty to remember: Hard [The passphrase "correct horse battery staple" is shown in the center of the panel.] Four random common words {Each word has 11 bits of entropy.} ~52 bits of entropy 2 44 = 550 years at 1000 guesses/sec Difficulty to guess: Hard [Cueball is thinking, in his thought bubble a horse is standing to one side talking to an off-screen observer. An arrow points to a staple attached to the side of a battery.] Horse: That's a battery staple. Observer: Correct! Difficulty to remember: You've already memorized it Through 20 years of effort, we've successfully trained everyone to use passwords that are hard for humans to remember, but easy for computers to guess.

TornadoGuard

TornadoGuard

https://www.xkcd.com/937

https://www.explainxkcd.com/wiki/index.php/937:_TornadoGuard

[The comic is a single panel which resembles a reviews page for a mobile phone application. Next to the app title is a pictogram of a tornado touching the ground] ----App store---- TornadoGuard From DroidCoder2187 ----------------- Plays a loud alert sound when there is a tornado warning for your area. ----------------- Rating: ★★★★☆ Based on 4 reviews ----------------- User Reviews: [The first three reviews show five black stars. The last review shows one black and four white stars.] Reviewer 1 (Dark silhouette): ★★★★★ Good UI! Many alert choices. Reviewer 2 (Helicopter without rotors): ★★★★★ Running great, no crashes Reviewer 3 (White square with black triangles at the top left and bottom right corner): ★★★★★ I like how you can set multiple locations Reviewer 4 (White car): ★☆☆☆☆ App did not warn me about tornado. [Caption below the comic:] The problem with averaging star ratings

This is a comic with a take on an application store - the most common app stores are for iPhones and Android devices. App stores take all the reviews and average the ratings for the overall star rating. In this comic, we see why this is sometimes a bad idea, especially with something as important as an app called TornadoGuard that should alert the user if there is a tornado warning for an area, an announcement indicating that a tornado is approaching. In this case, there are three 5 star reviews about the stability and user interface features of the app, left by users who actually never experienced its core functionality (simply because they never used it in a place where there was a tornado since they got it); however, the only review related to whether the app really works is given the same weight as the others, and sadly for that user, the TornadoGuard app failed in alerting the user to an upcoming tornado. Tornadoes are a recurring subject on xkcd. Also see future comic 1098: Star Ratings , 1754: Tornado Safety Tips . In 2615: Welcome Back Cueball returns to the app after almost 11 years to find that he has to walk through all kinds of info before getting to know if the visible tornado is likely to head his way... The title text is software-developer humor, the same as used in 583: CNR which contains further explanation. It is a note from the developer's bug report , which said they could not reproduce the error. Of course, they could only reproduce such a failure if there were a tornado coming towards their area, and if a tornado warning was issued. This is a fairly rare situation, especially in certain areas of the world. This lack of suitable testing conditions explains why the actual alert portion of their code appears to be faulty. This is a common problem with code that cannot be easily tested -- that when finally needed, it does not actually work. This is the reason for emergency drills. In 2219: Earthquake Early Warnings an app for warning of Earthquakes was the main topic, but tornado warnings was mentioned in the title text. In 2236: Is it Christmas? being right most of the time, except when it matters was the topic. [The comic is a single panel which resembles a reviews page for a mobile phone application. Next to the app title is a pictogram of a tornado touching the ground] ----App store---- TornadoGuard From DroidCoder2187 ----------------- Plays a loud alert sound when there is a tornado warning for your area. ----------------- Rating: ★★★★☆ Based on 4 reviews ----------------- User Reviews: [The first three reviews show five black stars. The last review shows one black and four white stars.] Reviewer 1 (Dark silhouette): ★★★★★ Good UI! Many alert choices. Reviewer 2 (Helicopter without rotors): ★★★★★ Running great, no crashes Reviewer 3 (White square with black triangles at the top left and bottom right corner): ★★★★★ I like how you can set multiple locations Reviewer 4 (White car): ★☆☆☆☆ App did not warn me about tornado. [Caption below the comic:] The problem with averaging star ratings

T-Cells

T-Cells

https://www.xkcd.com/938

https://www.explainxkcd.com/wiki/index.php/938:_T-Cells

[Two people are standing facing each other, having a conversation. One is holding a laptop.] Cueball (with laptop): What's the deal with this leukemia trial? {{Citation: Nejm, Aug 10, 2011}} Friend: Gotta wait and see. Friend: Helping the immune system attack tumors has been a longtime research target. Friend: Lots of promising leads. Often they don't pan out. Cueball: What'd these guys do? Friend: They took some of the patient's T-cells and patched their genes so they'd attack the cancer. That hasn't been enough in the past but their patch also added code to get the T-cells to replicate wildly and persist in the body. Cueball: Which worked, but created its own set of problems? Friend: How'd you guess? But I think the craziest part is the way they insert the patched genes. Cueball: How? Friend: Well, think - What specializes in invading and modifying T-cells? Cueball: Seriously? Friend: Yup. Must've been a fun conversation. [The last panel is set in a doctors office. A patient is sitting on the observation bed talking to their doctor.] Patient: Ok, so I have blood cells growing out of control, so you're going to give me different blood cells that also grow out of control? Doctor: Yes, but it's ok, because we've treated this blood with HIV! Patient: Are you sure you're a doctor? Doctor: Almost definitely.

This is a cancer- and leukemia-related comic. Two characters are having a discussion about a new trial ( Porter et al. NEJM 2011 ) in cancer treatment. A trial is done to test a proposed treatment on a select group of patients before approval for the wider patient group. In this case, the two characters are talking about a trial in which immune cells are taken out of the patient's body and genetically modified. The modified cells are able to both attack the cancer cells and replicate very quickly. However, to make these genetic changes inside the cells, they used HIV as the vehicle to introduce these new genes as it is specialized in invading and modifying immune cells. HIV is good for this because HIV attacks your T-cells and slowly kills off your immune system. If HIV was used as a vector to introduce a trait into your T-cells it could express a trait to hunt tumors and since it is already good at changing your T-cells it would be well-suited to this task. Basically, this treatment seems to replace one terrible disease with another terrible disease. As the title text says, they don't know how to get rid of the modified T-cells after they remove the cancer. And the last part of the title text is a joke, in which the doctor suggests yet another disease, smallpox , to inject into the patient's body. This is similar to the song There Was an Old Lady Who Swallowed a Fly in which a little old lady who swallowed a fly where each time she puts some other animal in her body to get rid of the last one and eventually she dies. This is akin to that as you have cancer so you put super-strong T-cells modified by HIV to get rid of them but then you have Leukocytosis so you get smallpox to kill those, and so on. Cueball possibly could have guessed this because he is familiar with biology according to this comic and one of the most common diseases that attacks T-cells would be HIV. Although highly expensive (because it currently requires customized set of alterations for each individual cancer), over the next few years subsequent clinical trials revealed the power of these super-strong T-cells (called Chimeric Antigen Receptor T-cells, or CAR T-cells for short) to cure previously uncurable cancers. For example, in 75 children with previously untreatable leukemia, 4 in 5 had no detectable cancer three months after treatment with CAR T-cells ( Maude et al. NEJM 2013 ). More and more different kinds of CAR T-cells are becoming FDA approved to treat a growing number of cancers. Seven years after this cartoon, the American Society of Clinical Oncology chose CAR T-cells as the 2018 Advance of the Year . [Two people are standing facing each other, having a conversation. One is holding a laptop.] Cueball (with laptop): What's the deal with this leukemia trial? {{Citation: Nejm, Aug 10, 2011}} Friend: Gotta wait and see. Friend: Helping the immune system attack tumors has been a longtime research target. Friend: Lots of promising leads. Often they don't pan out. Cueball: What'd these guys do? Friend: They took some of the patient's T-cells and patched their genes so they'd attack the cancer. That hasn't been enough in the past but their patch also added code to get the T-cells to replicate wildly and persist in the body. Cueball: Which worked, but created its own set of problems? Friend: How'd you guess? But I think the craziest part is the way they insert the patched genes. Cueball: How? Friend: Well, think - What specializes in invading and modifying T-cells? Cueball: Seriously? Friend: Yup. Must've been a fun conversation. [The last panel is set in a doctors office. A patient is sitting on the observation bed talking to their doctor.] Patient: Ok, so I have blood cells growing out of control, so you're going to give me different blood cells that also grow out of control? Doctor: Yes, but it's ok, because we've treated this blood with HIV! Patient: Are you sure you're a doctor? Doctor: Almost definitely.

Arrow

Arrow

https://www.xkcd.com/939

https://www.explainxkcd.com/wiki/index.php/939:_Arrow

[Cueball stands with a bow and arrow drawn tightly, aiming off-screen.] [He fires the arrow, it disappears offscreen. The bowstring vibrates for effect.] [He stands holding the bow by their side, watching the arrow fly away.] [A boomerang flies on-screen, coming from the direction the arrow was fired. Cueball reaches up to catch the boomerang.] [Cueball is now holding the boomerang, staring at it with confusion.]

The comic appears to be a reference to 475: Further Boomerang Difficulties , which was a sequel to 445: I Am Not Good with Boomerangs , which had a man throwing a boomerang that never returned. Cueball shoots an arrow off with a bow and a boomerang returns to him. This confounds him. As it was also a Cueball that threw the boomerang in the other comic, this may be the same Cueball that now finally has his boomerang return to him after a long time (464 comics later). This would really freak him out then. The title text is a pun on how boomerangs always come back, along with how "The Return of X" is often used for movie names. However, as shown in the prequel as well as in an even earlier comic, Cueball/ Randall has to admit: I Am Not Good with Boomerangs . So for him it would be a surprise if the boomerang returned! Boomerangs also became a main theme in the interactive comic 1350: Lorenz . [Cueball stands with a bow and arrow drawn tightly, aiming off-screen.] [He fires the arrow, it disappears offscreen. The bowstring vibrates for effect.] [He stands holding the bow by their side, watching the arrow fly away.] [A boomerang flies on-screen, coming from the direction the arrow was fired. Cueball reaches up to catch the boomerang.] [Cueball is now holding the boomerang, staring at it with confusion.]

Oversight

Oversight

https://www.xkcd.com/940

https://www.explainxkcd.com/wiki/index.php/940:_Oversight

[Megan and Cueball have sex up against a wall.] [Megan and Cueball have sex standing in an armchair.] [Megan and Cueball have sex in a swing, swaying above a table with a flower vase on it.] [Fitocracy. The search phrase is "sex" and the site returned "activity not found."] [Megan and Cueball stand in front of the computer, Megan is at the keyboard, Cueball stands back wearing a towel tied around his waist.] Megan: Come on! That was like two hours of cardio! Cueball: Hmm, let's see... The part on the dresser was kind of like skiing...

Fitocracy is a web site that turns workouts into a social game by awarding points, badges, levels and all sorts of other gamification . Megan and Cueball , by their judgment, have spent approximately two hours engaged in sexual activity . However, according to this cartoon, Fitocracy does not consider sex to be an activity acceptable for its site, despite the vigorous nature of Cueball and Megan's sexual workout. This could be due to an oversight (an unintentional error), as the comic is titled, or intentional, as Fitocracy does not consider sex to be an acceptable exercise. The title text explains how sites like Fitocracy are so successful. Because human brains, especially the cynical ones, like to game the system whenever they can, they will find easy things to do that also score high. In the case of Fitocracy, these are simple exercises that add up a lot when applied daily. But the creators of Fitocracy (and other such successful sites, like Weight Watchers or Lumosity) know this, and, as "in Soviet Russia" , the system games you, as shown, to adopt an exercise regimen, or to lose weight, or to get smarter, or whatever else there is. Sex does raise your breathing rate and heartbeat, but as sparkpeople (a similar site to fitocracy) notes , it is not as effective as a session at a gym, as it does not typically use the main muscle groups in their full range of motion and doesn't sustain a raised heartbeat for a sufficient length of time. They consider sex to be less effective as cardio than brisk walking, as it burns only about 100-200 cal per hour, which is little raised above a typical resting rate of about 60 cal per hour. (Of course, these statistics exclude several of the sexual activities Megan and Cueball engage in.) [Megan and Cueball have sex up against a wall.] [Megan and Cueball have sex standing in an armchair.] [Megan and Cueball have sex in a swing, swaying above a table with a flower vase on it.] [Fitocracy. The search phrase is "sex" and the site returned "activity not found."] [Megan and Cueball stand in front of the computer, Megan is at the keyboard, Cueball stands back wearing a towel tied around his waist.] Megan: Come on! That was like two hours of cardio! Cueball: Hmm, let's see... The part on the dresser was kind of like skiing...

Depth Perception

Depth Perception

https://www.xkcd.com/941

https://www.explainxkcd.com/wiki/index.php/941:_Depth_Perception

[The entire comic is narrated by Cueball, and never spoken by the Cueball shown in the examples. All dialog is shown in rectangular frames overlaid on the comic panels.] [In the first panel the background shows a cloudy sky in color, with the clouds all running together and appearing as a blue gray smear. Towards the bottom the horizon and the ground appear dark almost black at the very bottom. Two frames with two lines of text are at the top left and right, similar below except the one to the left has four lines and the one to the right only one line.] I've always had trouble with the size of clouds. I know they're huge. I can see their shapes. But I don't really see them as objects on the same scale as trees and buildings. They're a backdrop. [The next panel is split in three parts. The top part is in a single frame. The middle part is frame-less and only has text - the only narrating not inside one of the frames. Then at the bottom there are two frames overlaid over three small panels in a row] [In the top part of the 2ns panel stands Cueball on a flat disk inside a hemispherical dome with the front half cut away. The dome is about three times as tall as Cueball. Above the dome there is one frame with text. There is also two labeled arrows pointing to the dome and the disk.] Stars are the same way. Arrow up: Sky Arrow down: Ground [Text in between the top and the bottom panels:] I know they're scattered through and endless ocean, but my gut insists they're a painting on a domed ceiling. [The next two frames with text is overlaid above (three lines of text) and below (one line of text) the three panels described first. Those three panels are all inverted with black background and white Cueball:] [Left panel: Cueball stands on a curved surface, looking up.] [Middle panel: The perspective of the scene shifts, suddenly the surface Cueball is standing on is in the top left of the panel. Cueball is now looking down, leaning back, and waving his arms trying to regain balance. [Right panel: The perspective of the scene returns to normal, Cueball is now semi-crouched, staring at the ground with legs spaced apart to help him balance.] If I try hard enough, I get a glimmer of depth, a dizzying sense of space, But then everything snaps back. [An American football field is shown with Cueball drawn very small near the middle. Sections at the left tips of each of the goal posts are highlighted and shown as a zoomed view in an insert box. These insert shows the two webcams mounted on the top of the very tip, one for each goal posts. There are two frames with text above the field, the top one most to the left with one line, the second directly below it with two lines, and below the field there is also one frame with one line in it.] So one summer afternoon I set up two HD webcams hundreds of feet apart, Pointed them at the sky, [The next two frames with two lines of text each are stretched over the two middle panels in this second row of panels:] [The first panel shows a pair of glasses and a smartphone with an attachment designed to clip onto the glasses. The smartphone screen is setup to display two images side by side such that one camera is visible in the left half of the screen, and the other camera is visible in the right half of the screen. There are four arrows pointing to the two items and to each of the two parts of the screen. They all have labels which are between the two lines of text, but here shown below for clarity.] [The next panel shows the completed phone glasses assembly.] And fed one stream to each of my eyes. The parallax expanded my depth perception by a thousand times, Arrow top left: Right camera Arrow top right: Smartphone Arrow bottom left: Very strong reading glasses Arrow bottom right: Left camera [Cueball stands wearing the phone glasses assembly, one hand held up to the device, staring into the sky. There are two frames one above and one below with two lines of text each:] And I stood in my living room At the bottom of an abyss [Another colored panel with blue sky and clouds below the top part of the panel from left to right. Cueball is now a giant who stands in the middle of the frame on the shore of a coastline with a small island off the coast, only a step away for him. A city is near his right foot and the tallest skyscraper appears ankle high. A mountain range is behind him with mountains that are also only barely ankle high. A river flows past the mountains and joins another coming from them on it's way down towards the coast. Cueball is standing with his head well above cloud level as clouds swim around him. At the top above and left of his head the last frame with one line of text is located:] Watching mountains drift by.

This comic is one of those that is less focused on humour and more focused on a sense of wonder at the world for both Cueball / Randall and the reader. Cueball discusses how difficult it is to intuitively feel the reality of how vast the things he sees every day and night are - how big the clouds are, and how far away the stars are. Depth perception - seeing things in 3-D rather than as a flat 2-D image - is partly created by having "binocular vision", or two eyes spaced apart. Each eye sees a slightly different angle on a scene, and the brain combines these two views to give a genuinely three-dimensional view of something. 3-D glasses work the same way, by feeding a slightly offset image into each eye. When you look at far away objects, the offset from each eye is undetectable, and so they may look more like flat 2-D images - hence the impression Cueball has of stars being painted onto a dome rather than being extremely large, far away objects at very different distances. He wonders if he can work around this impression as far as the clouds are concerned. Normally, Cueball's eyes are a few centimetres apart, like everyone else's, and his 3-D perspective is based on that scale. Here, Cueball puts HD webcams on the tops of football uprights, which are 360 feet (~110 m) apart instead of a few centimetres. He uses strong reading glasses to hold up a smartphone, and feeds the far more offset images of the webcam feeds to each eye so that his brain will create a 3-D perspective of the clouds, which would normally be too massive for the offset between two human eyes to grasp their three-dimensional structure in the same way as smaller, closer things. This technique doesn't give him the view as if he were a giant as in the final panel, but rather as if he were a giant "at the bottom of an abyss" as per the second-last panel, as the clouds are higher than the goalposts on which the cameras are mounted. The final panel is some artistic license to give the reader a real sense of what it feels like for Cueball to carry this out; it shows us that he has finally achieved a more truthful perspective on the size and shapes of the clouds than he had when he started. The reason for the reversal of the "right camera" and "left camera" panes on the smartphone screen is unclear, this is likely just a mistake. The title text is a line from the 1969 song " Both Sides Now " by Joni Mitchell; the full chorus runs: "I've looked at clouds from both sides now / From up and down and still somehow / It's cloud illusions I recall / I really don't know clouds at all." Binocular depth perception involves seeing the same object from slightly different angles, from 'both sides', so Randall is taking the song lyric and literalising it. The song itself has a bittersweet tone and relates to how you understand things differently as you mature, but still don't necessarily feel like you understand them at all, so the tone also fits pretty un-ironically into the theme of the comic. [The entire comic is narrated by Cueball, and never spoken by the Cueball shown in the examples. All dialog is shown in rectangular frames overlaid on the comic panels.] [In the first panel the background shows a cloudy sky in color, with the clouds all running together and appearing as a blue gray smear. Towards the bottom the horizon and the ground appear dark almost black at the very bottom. Two frames with two lines of text are at the top left and right, similar below except the one to the left has four lines and the one to the right only one line.] I've always had trouble with the size of clouds. I know they're huge. I can see their shapes. But I don't really see them as objects on the same scale as trees and buildings. They're a backdrop. [The next panel is split in three parts. The top part is in a single frame. The middle part is frame-less and only has text - the only narrating not inside one of the frames. Then at the bottom there are two frames overlaid over three small panels in a row] [In the top part of the 2ns panel stands Cueball on a flat disk inside a hemispherical dome with the front half cut away. The dome is about three times as tall as Cueball. Above the dome there is one frame with text. There is also two labeled arrows pointing to the dome and the disk.] Stars are the same way. Arrow up: Sky Arrow down: Ground [Text in between the top and the bottom panels:] I know they're scattered through and endless ocean, but my gut insists they're a painting on a domed ceiling. [The next two frames with text is overlaid above (three lines of text) and below (one line of text) the three panels described first. Those three panels are all inverted with black background and white Cueball:] [Left panel: Cueball stands on a curved surface, looking up.] [Middle panel: The perspective of the scene shifts, suddenly the surface Cueball is standing on is in the top left of the panel. Cueball is now looking down, leaning back, and waving his arms trying to regain balance. [Right panel: The perspective of the scene returns to normal, Cueball is now semi-crouched, staring at the ground with legs spaced apart to help him balance.] If I try hard enough, I get a glimmer of depth, a dizzying sense of space, But then everything snaps back. [An American football field is shown with Cueball drawn very small near the middle. Sections at the left tips of each of the goal posts are highlighted and shown as a zoomed view in an insert box. These insert shows the two webcams mounted on the top of the very tip, one for each goal posts. There are two frames with text above the field, the top one most to the left with one line, the second directly below it with two lines, and below the field there is also one frame with one line in it.] So one summer afternoon I set up two HD webcams hundreds of feet apart, Pointed them at the sky, [The next two frames with two lines of text each are stretched over the two middle panels in this second row of panels:] [The first panel shows a pair of glasses and a smartphone with an attachment designed to clip onto the glasses. The smartphone screen is setup to display two images side by side such that one camera is visible in the left half of the screen, and the other camera is visible in the right half of the screen. There are four arrows pointing to the two items and to each of the two parts of the screen. They all have labels which are between the two lines of text, but here shown below for clarity.] [The next panel shows the completed phone glasses assembly.] And fed one stream to each of my eyes. The parallax expanded my depth perception by a thousand times, Arrow top left: Right camera Arrow top right: Smartphone Arrow bottom left: Very strong reading glasses Arrow bottom right: Left camera [Cueball stands wearing the phone glasses assembly, one hand held up to the device, staring into the sky. There are two frames one above and one below with two lines of text each:] And I stood in my living room At the bottom of an abyss [Another colored panel with blue sky and clouds below the top part of the panel from left to right. Cueball is now a giant who stands in the middle of the frame on the shore of a coastline with a small island off the coast, only a step away for him. A city is near his right foot and the tallest skyscraper appears ankle high. A mountain range is behind him with mountains that are also only barely ankle high. A river flows past the mountains and joins another coming from them on it's way down towards the coast. Cueball is standing with his head well above cloud level as clouds swim around him. At the top above and left of his head the last frame with one line of text is located:] Watching mountains drift by.

Juggling

Juggling

https://www.xkcd.com/942

https://www.explainxkcd.com/wiki/index.php/942:_Juggling

[The panel shows a close up of Cueball reading a book. The book is called "How To Juggle" and has a picture of a person juggling on the cover.] [The view now shows the entirety of Cueball. The book is splayed on the floor behind them, and he is holding some juggling balls.] [Cueball throws the juggling balls in the air.] [He lowers his arms to prepare to catch the balls. The balls are hovering in mid-air.] [Cueball now stands with his arms by his sides. The balls have not moved and are still suspended in mid-air.] [Cueball jumps, trying to grab the lowest ball. He can't reach.] [Cueball scratches his head and stares at the still floating juggling balls.] [Cueball throws the book into a trash can.]

In an attempt to learn to juggle Cueball begins practicing after reading an instruction book. In the third panel, it seems as though he is juggling normally after tossing the balls into their air. However, in a baffling phenomenon the balls he throws into the air seem to stop adhering to the strict laws of physics part of the way through his throw. As can be proven in simple demonstrations things tend to fall toward the largest center of gravity, and items in motion do not completely stop, unless other forces are at play as well. [ citation needed ] The joke here is partially making fun of the idea that in a comic, the visuals of juggling would be the same as the visuals sitting in place in the air. So at first while reading, we assume Cueball is juggling, until it is revealed he has no control over the position of the balls at all. Cueball is understandably perplexed, but instead of ascribing the event to some inexplicable supernatural agent, he concludes that the book's juggling instructions were faulty and throws it away. The title text furthers the joke by implying the book too seems to have become caught up in this phenomenon, which might now occur whenever Cueball throws something. Many things could be taken away from this. Perhaps Cueball is so spectacularly bad at juggling his failure breaks the laws of physics. Or perhaps the book assumes gravity and momentum are present where you choose to juggle. Or perhaps the book merely instructs you how to juggle like the picture on the front of the cover, where the balls can also be thought to hover. However it seems that for some reason physics has only stopped acting on these objects as Cueball himself is able to jump and fall back down without any trouble and the book was previously on the floor, implying it had been dropped there. While it is possible to reach zero gravity (or at least microgravity), there is no place in our universe where objects with mass have no momentum. Some possible explanations might be that Cueball is outside of our universe, he has just discovered something that's theoretically impossible, or he is just dreaming, or Randall has taken comedic license on the "momentum" part for the sake of the joke. Or he could be in a place where the surrounding fluid, instead of having the normal properties of earth's atmosphere, is a very thick or viscous fluid in which things simply become stuck. Or, perhaps the fourth wall is broken, and Cueball doesn’t recognize he’s in a web comic, but we do. This may also be a reference to a motto often brought up in the Hitchhikers Guide to the Galaxy series: if you forget about physics, they will forget about you. This comic is part of the following unpublished comic from the five-minute comics ; specifically the unpublished fourth part . [The panel shows a close up of Cueball reading a book. The book is called "How To Juggle" and has a picture of a person juggling on the cover.] [The view now shows the entirety of Cueball. The book is splayed on the floor behind them, and he is holding some juggling balls.] [Cueball throws the juggling balls in the air.] [He lowers his arms to prepare to catch the balls. The balls are hovering in mid-air.] [Cueball now stands with his arms by his sides. The balls have not moved and are still suspended in mid-air.] [Cueball jumps, trying to grab the lowest ball. He can't reach.] [Cueball scratches his head and stares at the still floating juggling balls.] [Cueball throws the book into a trash can.]

Empirical

Empirical

https://www.xkcd.com/943

https://www.explainxkcd.com/wiki/index.php/943:_Empirical

[Two people are standing together, Megan and Cueball.] Megan: Will you marry me? [Cueball throws his hands in the air excitedly.] Cueball: Let's find out! [The couple are now standing in front of an altar. A flower arch stretches over the couple and a person is standing behind the altar. Megan is wearing a knee length white dress and a veil. Cueball is wearing a bow tie. They are holding hands.] [The couple stand together, still dressed from the wedding and still holding hands.] Cueball: Apparently, yes!

When faced with the question "Will you marry me?", Cueball approaches the question in an empirical way. The word empirical denotes information gained by means of direct observation or experiments. In this comic, Cueball completes the "Will you marry me?" experiment, by actually getting married (as opposed to deciding on the spot or taking time to think) and the results are "yes". The word "will" has two meanings: auxiliary verb of the future and disposition to do something. In the first sense Cueball cannot answer this question since he cannot know the future. Of course the question Will you marry me? uses the verb will in the second sense. This comic is likely a reference to Randall 's marriage around this time. The title text states that Cueball is surprised by the results, suggesting that Cueball actually was not confident of his ability to marry, meaning that perhaps the marriage is not in good standing. [Two people are standing together, Megan and Cueball.] Megan: Will you marry me? [Cueball throws his hands in the air excitedly.] Cueball: Let's find out! [The couple are now standing in front of an altar. A flower arch stretches over the couple and a person is standing behind the altar. Megan is wearing a knee length white dress and a veil. Cueball is wearing a bow tie. They are holding hands.] [The couple stand together, still dressed from the wedding and still holding hands.] Cueball: Apparently, yes!

Hurricane Names

Hurricane Names

https://www.xkcd.com/944

https://www.explainxkcd.com/wiki/index.php/944:_Hurricane_Names

[A weather reporter sits behind a desk with an image of the Gulf of Mexico and surrounding land masses displayed to his left. 9 hurricane symbols are scattered across the map, primarily over Cuba.] Reporter: After the latest wave of hurricanes, not only have we run through the year's list of 21 names, but we've also used up the backup list of Greek letters. All subsequent storms will be named using random dictionary words. Reporter: The newly-formed system in the gulf has been designated "Hurricane Eggbeater", and we once again pray this is the final storm of this horrible, horrible season.

The World Meteorological Organization (WMO) maintains lists of potential names for tropical cyclones in each tropical cyclone basin ; Regional Specialized Meteorological Centres (RSMCs) and Tropical Cyclone Warning Centres (TCWCs) are responsible for assigning those names to tropical cyclones within their respective areas of responsibility. In the North Atlantic Ocean (including the Gulf of Mexico and Caribbean Sea as pictured), the NOAA 's National Hurricane Center (NHC/RSMC Miami) gives names to tropical cyclones (of which hurricanes are a subset), going through the alphabet (excluding Q, U, X, Y, and Z) and resetting at "A" at the beginning of the year. For example, the North Atlantic storms in 2012 were named "Alberto", "Beryl", "Chris", "Debby", and so on. There are six lists of names for the North Atlantic Ocean, which rotate every six years. Storms that are extremely catastrophic are removed from the lists. If there were more than 21 hurricanes in a season before 2021, the 21-letter alphabet becomes exhausted and the hurricanes are named with Greek letters. This has happened only twice: in the 2005 Atlantic hurricane season , see 1126: Epsilon and Zeta , and in the 2020 Atlantic hurricane season . In 2021, the World Meteorological Organization ended the use of the Greek alphabet and unveiled a supplementary list of names to be used in event of exhaustion. There have never been enough cyclones in one season to exhaust both the English and Greek alphabet (which would require more than 45 cyclones in a season; the most so far has been 30), and Randall is hypothesizing what the names would be if this happened. In the comic, the NHC has named the hurricanes using random words out of the Oxford English Dictionary (OED). The humor here is intrinsic: "Hurricane Eggbeater" is a bizarre and hilarious name (and may also refer to how an eggbeater spins and 'destroys' an egg in a similar manner to how a hurricane might affect the surrounding area). The place in the image shown is the Gulf of Mexico and its surroundings, with the land being white, and the ocean, black. The title text takes this already surreal twist to an even more ridiculous extreme, where an impossibly long hurricane season exceeds 300,000+ storms and exhausts the OED completely. Even when the NHC starts referring to them using counting numbers , which will be sufficient to cover an infinite number of hurricanes, they are foiled by a theorem in set theory . In mathematics, the set of all counting numbers is a countable set (as are the set of all integers or all fractions) whereas the set of all points on a surface is an uncountable set (as is the set of all real numbers). Cantor diagonalization is a famous proof that it is impossible to map objects from an uncountable set one-to-one with objects from a countable set. Applying this theorem to hurricanes, if there were to be one hurricane for every possible point on Earth's surface, it would be impossible to assign a distinct counting number to each one. This of course defeats NHC's last-resort naming scheme, but more pertinently, human civilization would be in a lot of trouble. At this point, the meteorologists give up and decide to name all the hurricanes "Steve", which is popular on the internet as an arbitrary, generic name. Ironically, this makes "Steve" no longer arbitrary. The reporter then goes on to tell people that their forecast is "Steve" meaning that the hurricanes are everywhere. He says "good luck", which is probably because there are currently hurricanes on all points of the earth's surface at the time of his speaking. [A weather reporter sits behind a desk with an image of the Gulf of Mexico and surrounding land masses displayed to his left. 9 hurricane symbols are scattered across the map, primarily over Cuba.] Reporter: After the latest wave of hurricanes, not only have we run through the year's list of 21 names, but we've also used up the backup list of Greek letters. All subsequent storms will be named using random dictionary words. Reporter: The newly-formed system in the gulf has been designated "Hurricane Eggbeater", and we once again pray this is the final storm of this horrible, horrible season.

I'm Sorry

I'm Sorry

https://www.xkcd.com/945

https://www.explainxkcd.com/wiki/index.php/945:_I%27m_Sorry

[Megan and Cueball are standing next to each other having a conversation.] Megan: My Mom's house burned down. Cueball: Oh! I'm sorry! Megan: Why? It's not your fault. Cueball: It's nice of you to say that, but I know what I did. [Caption below the panel:] It annoys me when people interpret an obviously sympathetic "I'm sorry" as an apology, so I've started responding by making it one. This kind of game, in which a deliberate misunderstanding of language is treated as the other person's fault seems to be a peeve of Randall's, and is dealt with in several other strips, for instance, 169: Words that End in GRY .

The term "I'm sorry" expresses a general feeling of sorrow or grief. It can be used either as an apology (expressing sorrow for one's own actions) or of sympathy (expressing sorrow for someone else's misfortune). Both uses are normal and acceptable, and the distinction is generally clear from the context. Some people deliberately conflate the two uses, treating an expression of sympathy as if it were an apology. This confusion is almost always feigned, as both uses of the term are well understood. As it says below the comic, when Megan rejects his sympathetic "I'm sorry" by treating it as if it were an apology and saying it was not his fault, rather than just agreeing with her, an irritated Cueball implies that it was always intended as an apology, because he DID, in fact, burn down her mother's house. It is unlikely that he actually burned her house down, but rather is simply teaching Megan a lesson not to nitpick so much. The title text has Cueball further attempting to convince Megan that he is not just being sarcastic, but really did set the fire, for the simple reason that he hates her mother. [Megan and Cueball are standing next to each other having a conversation.] Megan: My Mom's house burned down. Cueball: Oh! I'm sorry! Megan: Why? It's not your fault. Cueball: It's nice of you to say that, but I know what I did. [Caption below the panel:] It annoys me when people interpret an obviously sympathetic "I'm sorry" as an apology, so I've started responding by making it one. This kind of game, in which a deliberate misunderstanding of language is treated as the other person's fault seems to be a peeve of Randall's, and is dealt with in several other strips, for instance, 169: Words that End in GRY .

Family Decals

Family Decals

https://www.xkcd.com/946

https://www.explainxkcd.com/wiki/index.php/946:_Family_Decals

[Close up of the rear ends of two cars parked next to each other. Both have white stickers on their black rear windows. The car on the left is an urban SUV and most of the rear is visible with all the lights and a readable license plate with gray text visible. Its stickers represent a family. From left to right they are a Cueball-like guy, a woman with white hair like Blondie (i.e. black shows through), a girl with two ponytails, a boy of the same height and a smaller boy, both boys Cueball-like. The car on the right is a sporty hatch back, and only the left part until the middle is shown. The left lights and the very left part of the license plate can be seen. Its stickers show Cueball, Megan and then a large pile of dollar notes (six piles of different heights) and two large money bags with dollar signs on them, and the rear left bag is partly hidden by two piles of notes.] License plate of SUV: ICE-LI3 License plate of sporty hatch back: 4[cut off]

There exists a current fashion among car owners to place decals on their back window that represent their family. The decals consist of stick figures to depict the parents and children, perhaps shown doing a favorite activity, and even pets. The first car window features a couple with three children, while the other shows just a couple ( Cueball and Megan ), with piles of dollar bills and two large bags with dollar signs on them. The humor comes from the opportunity cost implied in this — not having children allows you to avoid the expense of raising them and accumulate money for your own use. One might expect that the cars would represent the difference in wealth, and they are identified as 'urban SUV' and 'sporty hatch back' in the official transcript . The larger car is a Subaru Outback which is a typical car used by families. The second car is a Honda Fit , which is a budget compact hatchback, in the comic it has a spoiler added. The Subaru Outback is more expensive now than the Honda Fit, which seems to fit perfect with the comic's implication since a family of five have to buy the large expensive hatchback. Being able to buy a smaller car that doesn't need to hold a five member family also allows you to save more money. The title text refers to the humorous description of cats as the real masters of their household, and the little girls surrounding the cat refers to their ability to influence humans with their cuteness (as referenced in 231: Cat Proximity ). The implication is that any adults in the household have a limited, non-credited role. The title text could also be a reverse of the stereotypical "crazy cat lady". Instead of someone owning a very large quantity of cats it could be one cat with an ungodly number of little girls. [Close up of the rear ends of two cars parked next to each other. Both have white stickers on their black rear windows. The car on the left is an urban SUV and most of the rear is visible with all the lights and a readable license plate with gray text visible. Its stickers represent a family. From left to right they are a Cueball-like guy, a woman with white hair like Blondie (i.e. black shows through), a girl with two ponytails, a boy of the same height and a smaller boy, both boys Cueball-like. The car on the right is a sporty hatch back, and only the left part until the middle is shown. The left lights and the very left part of the license plate can be seen. Its stickers show Cueball, Megan and then a large pile of dollar notes (six piles of different heights) and two large money bags with dollar signs on them, and the rear left bag is partly hidden by two piles of notes.] License plate of SUV: ICE-LI3 License plate of sporty hatch back: 4[cut off]

Investing

Investing

https://www.xkcd.com/947

https://www.explainxkcd.com/wiki/index.php/947:_Investing

Ponytail: Sure, 2% interest may not seem like a lot. But it's compound ! [Ponytail opens a computer and begins calculating.] Ponytail: If you invest $1,000 now, in just ten short years you'll have... ...let's see... Ponytail: ...$1,219. Ponytail: Ok, so compound interest isn't some magical force. Megan: Yeah, I'm just gonna try to make more money.

Compound interest is a type of interest in which the interest earned is added to the total amount, so that the interest itself then begins to gain interest in an exponential fashion. This contrasts to simple interest , where the amount used to calculate the interest will always stay at a fixed value. In economics classes, many teachers like to demonstrate extreme examples of compound interest, typically turning a thousand dollars into tens of thousands thanks to unrealistically high interest rates over several decades. But here, Ponytail discovers that a more realistic example is less than overwhelming. Instead of simple interest of 2% earning $200 in ten years, with compounding $219 is produced, hardly any better on a $1000 investment. There is an urban legend that Einstein said that compounding interest is the most powerful force. Snopes has its doubts about it . The idea in the title text that people take advice from physicists making small talk is also referenced in 799: Stephen Hawking and 1206: Einstein . Ponytail: Sure, 2% interest may not seem like a lot. But it's compound ! [Ponytail opens a computer and begins calculating.] Ponytail: If you invest $1,000 now, in just ten short years you'll have... ...let's see... Ponytail: ...$1,219. Ponytail: Ok, so compound interest isn't some magical force. Megan: Yeah, I'm just gonna try to make more money.

AI

AI

https://www.xkcd.com/948

https://www.explainxkcd.com/wiki/index.php/948:_AI

[Megan sits on an office chair at a desk. A laptop computer is on the desk, audio from a Cleverbot chat is shown coming from the laptop with a zigzag line from the screen. Megan has turned her head away from the computer to the right addressing Cueball off-panel.] Megan: Did you see the Cleverbot-Cleverbot chat? Cleverbot (from computer): I am not a robot. I'm a unicorn. [In the next frame-less panel, Megan has turned the chair away from the desk, which is not shown, and is now sitting with her hands in her lap in front of Cueball who holds one hand up as he replies.] Cueball: Yeah. It's hilarious, but it's just clumsily sampling a huge database of lines people have typed. Chatterbots still have a long way to go. [A close-up of Megan's head and shoulders. She has a hand to her chin and appears to be contemplating the last remark. Cueball replies from off-panel.] Megan: So... Computers have mastered playing chess and driving cars across the desert, but can't hold five minutes of normal conversation? Cueball (off-panel): Pretty much. [Both are shown again as in panel two, Cueball with his hands down.] Megan: Is it just me, or have we created a Burning Man attendee?

This comic is a reference to the wildly funny [ citation needed ] video of two Cleverbots talking to each other. By recording and analyzing whatever humans type into its input, they can sound pretty human to whoever is reading their response. Megan has been watching the video and asks Cueball about it. He says it's just "clumsy sampling" as they are still very far from sounding like humans and holding normal conversations. Megan then sums up that as of the release of this comic computers were good at chess and at driving cars through a desert (i.e. a place with no obstacles to hit. The ability of such self-driving cars would improve much later, with this comic being the first with a direct reference to such cars. Later self-driving cars became a recurring topic on xkcd). But they cannot hold a conversation for five minutes. And she thus concludes that a cleverbot would be perfect for attending Burning Man . Burning Man is a week-long event held yearly in Black Rock City, Nevada. The festival encourages an artistic, anti-establishment philosophy and attracts a broad but devoted following combining hippies, anarchists, nudists, techno-utopians and survivalists. Shows of custom cars on the desert plain are a big part of Burning Man, and mental games like chess are a popular way to pass the time there. However, a common joke about Burning Man attendees is that they can only talk about Burning Man - hence why they can't hold a five minute conversation. A tradition of Burning Man is not to shower while you are there, mostly because all water must be brought in from offsite. And of course Cleverbot reacts badly in showers because if you do try to shower a Cleverbot, you end up with a shorted out computer. [Megan sits on an office chair at a desk. A laptop computer is on the desk, audio from a Cleverbot chat is shown coming from the laptop with a zigzag line from the screen. Megan has turned her head away from the computer to the right addressing Cueball off-panel.] Megan: Did you see the Cleverbot-Cleverbot chat? Cleverbot (from computer): I am not a robot. I'm a unicorn. [In the next frame-less panel, Megan has turned the chair away from the desk, which is not shown, and is now sitting with her hands in her lap in front of Cueball who holds one hand up as he replies.] Cueball: Yeah. It's hilarious, but it's just clumsily sampling a huge database of lines people have typed. Chatterbots still have a long way to go. [A close-up of Megan's head and shoulders. She has a hand to her chin and appears to be contemplating the last remark. Cueball replies from off-panel.] Megan: So... Computers have mastered playing chess and driving cars across the desert, but can't hold five minutes of normal conversation? Cueball (off-panel): Pretty much. [Both are shown again as in panel two, Cueball with his hands down.] Megan: Is it just me, or have we created a Burning Man attendee?

File Transfer

File Transfer

https://www.xkcd.com/949

https://www.explainxkcd.com/wiki/index.php/949:_File_Transfer

[Cueball stands near a computer, talking on the phone to another person.] Cueball: You want your cousin to send you a file? easy. He can email it to- ...Oh, it's 25 MB? Hmm... Cueball: Do either of you have an FTP server? No, right. Cueball: If you had web hosting, you could upload it... Cueball: Hm. We could try one of those MegaShareUpload sites, but they're flaky and full of delays and porn popups. Cueball: How about AIM Direct Connect? Anyone still use that? Cueball: Oh, wait, Dropbox! It's this recent startup from a few years back that syncs folders between computers. You just need to make an account, install the- Cueball: Oh, he just drove over to your house with a USB drive? Cueball: Uh, cool, that works too. [Caption below the panel:] I like how we've had the internet for decades, yet "sending files" is something early adopters are still figuring out how to do. This comic has a resemblance to both 1810: Chat Systems and 2194: How to Send a File

Cueball is trying to help two people, his friend and his friend's cousin, exchange a 25 MB file. Most people know how to use email to send files through the internet, but (as of 2011 when this comic was published) 25 MB exceeds the attachment size limit of most email services. The reason there is a limit is because every email has to be transferred between several mail transfer agents, and each one has to temporarily store a copy of the email. Space constraints on those mail servers means that they must impose size limits, and an email with such a large attachment will therefore not be delivered. The next option is to upload the file to an FTP server (FTP stands for File Transfer Protocol , as opposed to HTTP, Hypertext Transfer Protocol ), used to transfer files between computers on a shared network, such as the internet. However, FTP servers are a touch more esoteric than a mere email attachment, and many internet users don't have access to one of their own. Web hosting is simply the ability to create a website and store all the data for said website on a server which is connected to the internet. If Cueball's friend's cousin had the ability to do that, sharing the file would be as easy as putting a copy of it in an accessible directory and sending the link to the desired recipient. Megaupload was one of many sites on the Internet that recognized most users' inability to host large files on their own, and so offers to host large files, sometimes for free, sometimes for a small fee. The payoff is that in order to make such a service profitable, many of these sites are cluttered with banner and pop up ads in a mad effort to squeeze as much ad revenue out of every page view as possible. It's not a dealbreaker for some, but Cueball seems to think it'll be too much for his friend's cousin to handle. AIM Direct Connect was a file sharing system on AOL Instant Messenger, which was already suffering severe drops in popularity by the year 2000. Clearly, Cueball is grasping at straws here: anybody desperate enough to invoke the name of AOL as a solution instead of a problem must be at their wits' end. Dropbox is a program with a web-based GUI that automates file sharing between two computers on the internet. But this solution also has its issues, as it requires that at least the sending party has a Dropbox account. Installing Dropbox software is not actually required, since Dropbox also provides a web interface for uploading and downloading files. At the time of the comic's publication, Dropbox was still relatively new and unknown, thus why it is not Cueball's first suggestion. While Cueball is still explaining Dropbox, the friend's cousin has copied the file to a USB drive and physically transported it to the friend's house, circumventing the Internet entirely. It's not an elegant solution, but sometimes traditional methods are the most efficient ways to get something done. When used to transfer files between computers in the same room or building, this same approach is referred to as sneakernet . This comic is also an illustration of what Andy Tanenbaum said in 1989: Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. Sneakernet was examined in this What If article. Tim Berners-Lee developed the http protocol, the html markup language and the first web browser. Therefore he is considered to be the inventor of the World Wide Web. He envisioned originally an interactive web, where it would have been possible for the users to change a website directly using the browser, which would have made it possible to upload a file directly to a webpage: Tim Berners-Lee's original vision of the Web involved a medium for both reading and writing. In fact, Berners-Lee's first web browser, called WorldWideWeb, could both view and edit web pages (from Wikipedia WebDAV ). In contrast to this, a static web ("web 1.0") came alive, which developed then later to the interactive "web 2.0" we know today. Wikis like this website , where the page content is editable via forms, are a perfect example for this "emulated interactivity". From the technical point of view, the webpage is still static and the browser is just a viewer for html pages with the limited possibility to send some form data to the server. Scripts on the server, which process this form data, change then the web page. This mechanism is a more complicated work-around for what Tim Berners-Lee originally planned. Dropbox and the web interfaces of email providers are further examples of this "emulated interactivity". The title text assumes, that Tim Berners-Lee feels probably generally sad, that his invention developed into this unnecessary complicated way and misusing emails (maybe even via the web interface of email providers) for file sharing is therefore especially painful for what could have been so simple. [Cueball stands near a computer, talking on the phone to another person.] Cueball: You want your cousin to send you a file? easy. He can email it to- ...Oh, it's 25 MB? Hmm... Cueball: Do either of you have an FTP server? No, right. Cueball: If you had web hosting, you could upload it... Cueball: Hm. We could try one of those MegaShareUpload sites, but they're flaky and full of delays and porn popups. Cueball: How about AIM Direct Connect? Anyone still use that? Cueball: Oh, wait, Dropbox! It's this recent startup from a few years back that syncs folders between computers. You just need to make an account, install the- Cueball: Oh, he just drove over to your house with a USB drive? Cueball: Uh, cool, that works too. [Caption below the panel:] I like how we've had the internet for decades, yet "sending files" is something early adopters are still figuring out how to do. This comic has a resemblance to both 1810: Chat Systems and 2194: How to Send a File

Mystery Solved

Mystery Solved

https://www.xkcd.com/950

https://www.explainxkcd.com/wiki/index.php/950:_Mystery_Solved

[A twin prop airplane flies high overhead.] Off-screen person: What's that airplane? [The plane has landed, and the pilot is walking towards the crowd waving.] Off-screen person: Holy crap— Is that Amelia Earhart? [A close up of Amelia Earhart waving.] Amelia: Hey everyone! My flight was a success! Off-screen person: But... Where were you!? [A wide view of Amelia, she stops waving.] Amelia: I flew around the world! Off-screen person: But you disappeared in 1937! [A close up of Amelia Earhart.] Amelia: Right, to fly around the world. Off-screen person: It's 2011! Amelia: The world is big. It's a long flight. [A wide view of Amelia] Off-screen person: But you... It's not... I - Amelia: Can I talk to someone smarter?

In this comic, aviation pioneer Amelia Earhart's plane comes back to land after it went missing in 1937. It was presumed that Earhart was dead and that her plane went down into the ocean at some point during her journey, although various alternate theories have arisen since then, with no clear answer to the mystery. However, this comic proposes a much simpler explanation: there was no disappearance, it just took her 74 years to fly around the Earth. This explanation is simple, but impossible. Earhart seems to think the person she is talking with is stupid for not comprehending such a simple answer, but in fact her explanation raises a multitude of other questions. Among them: Another possibility is that she did not just fly around the earth, but flew very fast (near light speed ) for 74 years to return without having aged much . However, this would not explain why she thinks it is a long trip around the earth, and it raises the additional questions of how she would accomplish this feat in a twin-engine monoplane and how no one else noticed any signs of her plane traveling near light speed, such as a 74-year-long sonic boom. Earhart's disappearance gave birth to many conspiracy theories. One of these, which was explored in the TV series Star Trek: Voyager , involves her being abducted to another part of the galaxy , where she was left in cryogenic stasis until found by the Voyager crew. Something similar could be the case here, having Earhart frozen by aliens until 2011. The title text lists a few more deceptively mundane answers to long-unsolved mysteries that at first seem to dispel the questions with boring logic, but in fact raise more questions than they answer. The first is the lost colonists of Roanoke , who were one of the first groups to come to North America, but then suddenly disappeared, leaving their colony untouched. The comic suggests that they simply left to found Roanoke, Virginia . Like all the other explanations in this comic, this doesn't explain how this simple solution became lost to public knowledge. It also doesn't explain why they abandoned their original colony, or how they made it to Roanoke, Virginia, which is more than 300 miles away, or where they were between when their colony was found abandoned in 1590 and when the future Roanoke, Virginia, was established over 200 years later, in the nineteenth century. The second mystery in the title text, the Franklin Expedition , was a British voyage in 1845 to study the Northwest Passage that also disappeared, somewhere in northern Canada. The text suggests that the expedition wasn't lost; it was still exploring and eventually found its way to the Pacific Ocean in 2009. This is impossible, because the men on the expedition would be long dead. As a side note, both of the Franklin Expedition ships were eventually found wrecked in the years after this comic was published: one in 2014 , and the other in 2016 . The final mystery is Jimmy Hoffa , the famous Teamsters Union leader who went missing in 1975 and declared dead in 1982 (possibly murdered). The comic says Jimmy simply opted to switch to the more formal version of his name; again, this raises the question of how such a thing would be possible without anyone noticing. The current head of the Teamsters is in fact named James Hoffa (he is Jimmy Hoffa's son and goes by "James P. Hoffa" professionally); the comic could be implying that the senior Hoffa is not only alive but actually impersonating his own son, which would raise the question of why the supposed "son" doesn't look suspiciously older than he claims to be. [A twin prop airplane flies high overhead.] Off-screen person: What's that airplane? [The plane has landed, and the pilot is walking towards the crowd waving.] Off-screen person: Holy crap— Is that Amelia Earhart? [A close up of Amelia Earhart waving.] Amelia: Hey everyone! My flight was a success! Off-screen person: But... Where were you!? [A wide view of Amelia, she stops waving.] Amelia: I flew around the world! Off-screen person: But you disappeared in 1937! [A close up of Amelia Earhart.] Amelia: Right, to fly around the world. Off-screen person: It's 2011! Amelia: The world is big. It's a long flight. [A wide view of Amelia] Off-screen person: But you... It's not... I - Amelia: Can I talk to someone smarter?

Working

Working

https://www.xkcd.com/951

https://www.explainxkcd.com/wiki/index.php/951:_Working

[Ponytail is standing next to Cueball filling his vehicle with petrol. Ponytail is pointing off-screen.] Ponytail: Why are you going here? Gas is ten cents a gallon cheaper at the station five minutes that way. Cueball: Because a penny saved is a penny earned. If you spend nine minutes of your time to save a dollar, you're working for less than minimum wage.

This comic is a jab at price-gouging shoppers who spend large amounts of time checking multiple shopping outlets for the best deals. The minimum wage is the lowest possible wage that a person could legally be paid, usually only targeted at providing unskilled laborers with an equitable level of income. In 2011, when this comic was published, US Federal minimum wage was $7.25 an hour, though certain states and cities typically have higher minimum wages. Using simple math, the caption states that a person is effectively working below the minimum wage when they spend their time looking to save a few cents on their purchases. (Randall's math checks out: $7.25/hour times nine minutes would equate to just over $1.08.) Benjamin Franklin's adage "A penny saved is a penny earned" is usually taken to mean that a person, merely by making the effort to save their money rather than spending it frivolously, has put in worthwhile effort that makes them deserving of that money. Cueball flips the meaning of the phrase, instead saying that saving money is work just like a job, and as one would not take a job that paid less than minimum wage, the compensation is inadequate for the amount of effort it would take to drive to a cheaper gas station. Of course, if you are unemployed and cannot expect to get any wages it could still be worth your time. The title text, however, then goes on to talk about how the extra fuel consumption involved in finding cheaper gas leads to more extra money being spent on gas than is actually saved at the cheaper outlet. This problem has also been examined in What if? - Cost of Pennies . See also 1205: Is It Worth the Time? . However, Randall neglects to consider the effect that customers have on prices. If customers consistently go out of their way to get the lowest prices, then sellers will be motivated to lower their prices to attract customers. On the other hand, if customers consistently purchase from the most convenient seller, then sellers can raise prices without losing business. [Ponytail is standing next to Cueball filling his vehicle with petrol. Ponytail is pointing off-screen.] Ponytail: Why are you going here? Gas is ten cents a gallon cheaper at the station five minutes that way. Cueball: Because a penny saved is a penny earned. If you spend nine minutes of your time to save a dollar, you're working for less than minimum wage.

Stud Finder

Stud Finder

https://www.xkcd.com/952

https://www.explainxkcd.com/wiki/index.php/952:_Stud_Finder

[Black Hat sits on a couch, reading a book. Cueball is approaching him from behind the couch holding a picture in a frame, a screwdriver, and some screws.] Cueball: Have you seen my stud finder? I've looked everywhere. Black Hat: It sounds like you may be interested in my new product, a— Cueball: Shut up.

It sounds like you may be interested in my new product, a— stud finder finder. Cueball cannot locate his stud finder , so Black Hat begins a sales pitch, presumably for a "stud finder" finder. The joke is in the irony of having to find something that is used to find other things. Cueball interrupts Black Hat before he can make the obvious joke. The same comic technique is used later in 1059: Bel-Air . Currently no product exists that will locate a stud finder, although online review compilations are useful for finding the right stud finder to buy. Studs are vertical wood members in wood-framed construction common in North America, although steel framing has become a popular alternative. These supports reinforce a wall at regular intervals, typically 16 inches (about 40 cm), and at corners, windows, and doors. Most stud finders use an electrostatic field that is affected by the densities and types of materials in the vicinity, identifying where studs and other significant framing elements are located. One might want to know the locations of studs within a wall for installing wiring, mounting shelves and heavy objects to walls, or in this comic, hanging a picture. Wiring can be inserted between studs behind the drywall , while shelves, pictures, etc. are better affixed to studs. Many stud finders have a light that turns on in conjunction with a beep when a higher density is detected, indicating the edge of a stud. But there are circumstances that can fool stud finders. Most are designed for the drywall-over-wood-framing construction, and can be fooled by older plaster and lath construction where the density is much more uniform throughout the length of the wall. Lower quality stud finders can also be fooled by things like moisture in the drywall or wiring within the wall cavity, and may thus beep when there is not a stud behind the scanned location. As a result, many people will try alternatives such as using a magnet to find the drywall screws or nails, or tapping a finishing nail through the wall to see if there is a stud underneath. At the title text, Randall just gives up. Assuming there was no electrostatic interference, a stud finder going off randomly would indicate lots and lots of studs at random places that change position. The idea of a "something doer doer" was explored again in 1821: Incinerator and the title text of 2376: Curbside . [Black Hat sits on a couch, reading a book. Cueball is approaching him from behind the couch holding a picture in a frame, a screwdriver, and some screws.] Cueball: Have you seen my stud finder? I've looked everywhere. Black Hat: It sounds like you may be interested in my new product, a— Cueball: Shut up.

1 to 10

1 to 10

https://www.xkcd.com/953

https://www.explainxkcd.com/wiki/index.php/953:_1_to_10

Megan: On a scale of 1 to 10, how likely is it that this question is using Binary? Cueball: ...4? Megan: What's a 4?

The binary numeral system refers to a counting system in base-2, which uses only the digits 0 and 1, as opposed to the more familiar base-10 decimal system, which uses the digits 0 through 9. In this case, the scale of 1 to 10 is using binary, so in decimal it would be a scale of 1 to 2. Since 4 in binary is "100" it doesn't fit into the range "1" to "10" in a binary system. And Megan doesn't even know the number "4" because she's only working on the binary system, this character does not exist for her. It is also possible that Megan is using base-3 or base-4, both of which don't have a 4 (base-3 counts 1, 2, 10, etc., and base 4 counts 1, 2, 3, 10 etc.) It should be noted that if Megan is indeed speaking out loud in such a way that confuses Cueball, she would be saying "ten" out loud; this would automatically indicate she is indeed using base-10 (or higher). The correct pronunciation of "10" in base-2 is "one zero". The title text uses a similar joke. Since test scores are usually written as either a letter grade or a percentage, 11 correct questions out of 100 would be a failing score in decimal notation. However, 11/100 in binary translates to 3/4 in decimal, which would be 75%, accepted in most classes as a 'C' grade. It could also be argued that a score of 11 should count as a "B", as 11 is B in hexadecimal, however this link is a bit more tenuous, as the whole score would then be interpreted as "B/256". Megan: On a scale of 1 to 10, how likely is it that this question is using Binary? Cueball: ...4? Megan: What's a 4?

Chin-Up Bar

Chin-Up Bar

https://www.xkcd.com/954

https://www.explainxkcd.com/wiki/index.php/954:_Chin-Up_Bar

[Black Hat is in the middle of on an escalator with five other people as it ascends. He carries something like a a pole.] [Zoom in on Black Hat and Cueball.] Cueball: This is a long escalator. Black Hat: 70 meters. Longest in the country. [Black Hat goes upwards holding his pole.] [Cueball is still behind Black Hat.] Cueball: Why're you carrying a chin-up bar? Black Hat: Why aren't you wearing a hat? [The view returns to the original view only showing the six people ascending, only shifted so they are all a bit longer to the right.] Cueball: I'm not really a hat person. Black Hat: And I'm not really a not-carrying-a-chin-up-bar person. [Close up on Cueball on the escalator.] [Zoom out. Black Hat still has the pole in his hands.] Cueball: Seriously, why did you bring it? Black Hat: How should I know? I'm not a psychologist. [Zoom in on the top of the escalator where Black Hat steps off and installs the chin-up bar on the exit of the escalator.] Twist Click Click [View from above towards both ascending and descending escalators. Black Hat and Cueball are on the descending escalator.] [The final panel takes up two entire rows and shows all people falling down.] It would appear that the man behind Cueball with glasses and a goatee is the psychologist from 435: Purity , and then Megan next to him could be the sociologist from the same comic. This gives new meaning to Black Hat's line about not being a psychologist. Escalators were also the subject of the earlier comic 252: Escalators , a rather more funny take on these dangerous devices.

Black Hat has once again showed everyone that he is a classhole , with a plan to block traffic on the longest single-tier escalator in the Western hemisphere. At the time of the comic's publishing, that placed the comic in the Wheaton station in Washington D.C. 's Washington Metro subway system, where the 70-meter (230-foot) escalator is. It's clear that Black Hat knows it is the longest and that this is the reason he has chosen this exact escalator for his plan. Black Hat carries a chin-up bar over his shoulder up the escalator, resulting in a conversation with Cueball , riding up behind him, about Black Hat's motives for doing such. Black Hat uses sly conversing methods to avoid saying his true motives. First he counters the question with another question: Why aren't you wearing a hat? Cueball's reply is a normal I'm not really a hat person , whereas Black Hat's copy reply is not a real answer; I'm not really a not-carrying-a-chin-up-bar person , which is probably a sentence never used before this comic. [ citation needed ] It takes Cueball a second to process this answer, but he doesn't give up and asks why again. Black Hat continues deflecting his questions by stating that he's not a psychologist , although he clearly is aware of his own motives and intentions. (One could argue that it would take a psychology degree to explain those motives and intentions.) After this they reach the top and once they get off Black Hat quickly turns around and locks the bar in place at about waist height (i.e. as high up as possible on an escalator), just before the moving part of the escalator ends. Chin-up bars are typically capable of holding up a 300 pound (130 kg) person without moving, and a bar like Black Hat has brought with him can be installed easily in a doorway , or in the opening of an escalator… The unexpected appearance of a solidly attached bar at the top of a crowded escalator could be disastrous. The first people would probably stumble backward to avoid it or hit it and topple backwards, and collide with the passengers immediately behind them, knocking them off their feet and likely creating a domino effect all the way down. Indeed, this is exactly what happens and is depicted in the last panel. Black Hat and Cueball are seen on the descending escalator in the background, Cueball has turned around looking at the scene and displaying worry about what Black Hat has done, but Black Hat isn't even looking at the chaos he has caused, completely ignoring all the falling bodies. Although it might be possible, the two are fairly lucky to be unscathed, as they could have been hit by someone in the pileup falling all the way over in their side of the escalator. Since they are most likely on the way down to a subway, the traffic should make it easy for them to get away on the next train, before anyone has a chance to try and find the perpetrator, so Black Hat gets away with his schemes once again. In the title text it is made clear that the few people that actually escaped the moving stairs were unable to use the emergency shutdown because Black Hat had disabled the system, presumably before ascending in the first place. This is stated to have caused the stampede to last for two hours and waves of falling people would end up reaching the bottom three times, before ascending with the stairs again. The reason for this extended mayhem could be that only the very first people at the top of this domino effect who actually hit the chin-up-bar know what caused the problem to begin with. Since they are likely among those people too hurt to explain anything in time, the next group of people trying to get out after the first wave of falling people might just proceed to run into the same problem at the top once again. The problem is exacerbated by the disabled shutoff, so even if someone sees the chin-up-bar and knows how to escape, they would either be pulled back into the crowd of traffic or be free but unable to help. This helps to explain why the cycle of crowd collapse happened three times, and the use of the word "stampede" connotes the panicked, unorganized behavior of the trapped people that serves to make the problem worse. Alternately, the stampede reaching the bottom might suggest that the people traversed the entire length of the escalator, though this is not sufficiently wide enough for a human body. [Black Hat is in the middle of on an escalator with five other people as it ascends. He carries something like a a pole.] [Zoom in on Black Hat and Cueball.] Cueball: This is a long escalator. Black Hat: 70 meters. Longest in the country. [Black Hat goes upwards holding his pole.] [Cueball is still behind Black Hat.] Cueball: Why're you carrying a chin-up bar? Black Hat: Why aren't you wearing a hat? [The view returns to the original view only showing the six people ascending, only shifted so they are all a bit longer to the right.] Cueball: I'm not really a hat person. Black Hat: And I'm not really a not-carrying-a-chin-up-bar person. [Close up on Cueball on the escalator.] [Zoom out. Black Hat still has the pole in his hands.] Cueball: Seriously, why did you bring it? Black Hat: How should I know? I'm not a psychologist. [Zoom in on the top of the escalator where Black Hat steps off and installs the chin-up bar on the exit of the escalator.] Twist Click Click [View from above towards both ascending and descending escalators. Black Hat and Cueball are on the descending escalator.] [The final panel takes up two entire rows and shows all people falling down.] It would appear that the man behind Cueball with glasses and a goatee is the psychologist from 435: Purity , and then Megan next to him could be the sociologist from the same comic. This gives new meaning to Black Hat's line about not being a psychologist. Escalators were also the subject of the earlier comic 252: Escalators , a rather more funny take on these dangerous devices.

Neutrinos

Neutrinos

https://www.xkcd.com/955

https://www.explainxkcd.com/wiki/index.php/955:_Neutrinos

[Megan and Cueball are talking.] Megan: Did you see the neutrino speed of light thing? Cueball: Yup! Good news; I need the cash. Megan: Huh? Cash? [Text above half-sized panel.] Yeah. When there's a news story about a study overturning all of physics, I used to urge caution, remind people that experts aren't all stupid, and end up in pointless arguments about Galileo. [Half-height panel.] [Cueball sitting on chair, looking down at laptop in his lap. Books and things are on a desk in front of him.] Cueball: No, this isn't about whether relativity exists. If it didn't, your GPS wouldn't work. Cueball: What do you mean, "science thought police"? Have you seen our budget? We couldn't begin to afford our own thought police. [Megan and Cueball talking again.] Megan: That sounds miserable and unfulfilling. Cueball: Yup. So I gave up, and now I just find excited believers and bet them $200 each that the new result won't pan out. [Same as last panel.] Megan: That's mean. Cueball: It provides a good income, and if I'm ever wrong, I'll be too excited about the new physics to notice the loss.

The " Neutrino speed of light thing " mentioned in this comic was an actual story from the day before the comic was posted. An experiment at CERN caused a stream of neutrinos to be passed from CERN in Switzerland to a receiving station at the INFN laboratories of Gran Sasso in Italy ( LNGS ). The initial findings from the experiment were that the neutrinos arrived at the detector in less time than a beam of light would have taken. The neutrinos had apparently exceeded the speed of light . Albert Einstein famously posited that the speed of light in a vacuum is both constant and absolutely the fastest possible speed for any object in the universe. Nothing can accelerate to any faster speed. Therefore, a report that neutrinos have been found travelling faster than light challenges a fundamental law of physics and turns all of physics, or at least special relativity , on its head. Prior experience has shown Cueball that in such cases, arguing with people and preaching caution is futile and will lead to "pointless arguments about Galileo". Galileo Galilei was famously convicted of heresy for his defending the heliocentric system , and is often used as an example of revolutionary ideas being suppressed by the powerful. Believers in the new findings would thus accuse Cueball and the scientific community of being as stubborn and oppressive as the Inquisition in Galileo's time, and even compare them to the Thought Police from George Orwell's 1984 , another popular archetype of oppressive measures. Cueball realizes that it is more satisfying and profitable to place bets with them instead. His reasoning is that almost invariably, these supposedly world-changing discoveries end up falling apart after further investigation, and that if it doesn't, then the discovery itself will satisfy his scientific curiosity enough to outweigh his monetary loss. This is similar to Stephen Hawking 's scientific wagers , where Hawking set bets such that, if he was wrong, he would be paid, and if he was right, he'd have to pay and wouldn't mind because he'd just have been proven right. The title text is a reference to a graph published similar to, if not the same as, the one found here . The continental drift can be seen, as well as the clearly marked jump showing the earthquake in question. Postscript: Cueball (that is, Randall) was correct. The experiment was found to be flawed. Neutrinos are not faster than light , the data was probably wrong due to a faulty connection on an optical fiber. [Megan and Cueball are talking.] Megan: Did you see the neutrino speed of light thing? Cueball: Yup! Good news; I need the cash. Megan: Huh? Cash? [Text above half-sized panel.] Yeah. When there's a news story about a study overturning all of physics, I used to urge caution, remind people that experts aren't all stupid, and end up in pointless arguments about Galileo. [Half-height panel.] [Cueball sitting on chair, looking down at laptop in his lap. Books and things are on a desk in front of him.] Cueball: No, this isn't about whether relativity exists. If it didn't, your GPS wouldn't work. Cueball: What do you mean, "science thought police"? Have you seen our budget? We couldn't begin to afford our own thought police. [Megan and Cueball talking again.] Megan: That sounds miserable and unfulfilling. Cueball: Yup. So I gave up, and now I just find excited believers and bet them $200 each that the new result won't pan out. [Same as last panel.] Megan: That's mean. Cueball: It provides a good income, and if I'm ever wrong, I'll be too excited about the new physics to notice the loss.

Sharing

Sharing

https://www.xkcd.com/956

https://www.explainxkcd.com/wiki/index.php/956:_Sharing

[Megan and Cueball hang out in front of a tree.] Megan: Whoa. What's this? Cueball: What's what? Megan: This tree has a USB port. Cueball: Try connecting to it, I guess. [Megan brings out a laptop and connects to it.] Megan: It's offering up a drive with one file on it. Cueball: What's the file? Megan: An eBook. "Shel_Silverstein_-_The_Giving_Tree.azw" Cueball: Never heard of it. Let's take a look! Laptop: DRM Error: You have not purchased rights to view this title. Lending is not enabled. Cueball: Huh. Oh well. Megan: Let's go see what Mike is up to. [The tree is alone.]

Cueball and Megan encounter a USB Dead Drop in a tree, placed in such a way as to simulate the tree itself has a USB port. The Giving Tree is a book in which a tree gives everything it has to a little boy out of love and a desire for the boy's company: apples to sell, wood to build a house, even letting the boy cut it down to make a boat. At the end of the book, the boy comes back as a grown man and the tree tells him sadly that it has nothing else to give. The man tells the tree that he only wants a tree stump to sit on, and the tree gladly gives him that. Notably, the tree's moments of greatest distress come when it fears that it can give the boy no more and that the boy will leave it. .azw is an e-book file format used and created by the online company Amazon.com , which makes and sells the popular Amazon Kindle e-reader. Complaints against the format have been made concerning its closed nature: some people claim that all information should be free and imposing restrictions on its usage is limiting growth in the modern world. This comic was published two days before the release of the fifth generation of Kindles, alongside complaints that Amazon would continue to use DRM "encumbered" e-book formats. The comic is a criticism of the usage of DRM in digital commerce. The tree's willingness to offer up its file is parallel to the generous nature of the tree in The Giving Tree . The tree is prevented from sharing its file however, by DRM in the file. With nothing to gain from the tree, Cueball and Megan leave the tree alone, in a manner similar to the fears of the tree in The Giving Tree . The final frame is a reference to the iconic silhouette of a tree that is used in the loading screens of Amazon's Kindles, a link between the abandoned tree in the comic and an abandoned Kindle. The title text is an elaboration on the idea of a more modern Giving Tree. While in the original book, the tree gives the boy various gifts, in the new, modern version, the tree shows "its friend" (presumably the boy) all the places the friend can buy things, using social media to do so. This, like the DRM on the book from earlier, is a criticism of some aspect of the modern world, in this case, the increased commercialism due to social media. [Megan and Cueball hang out in front of a tree.] Megan: Whoa. What's this? Cueball: What's what? Megan: This tree has a USB port. Cueball: Try connecting to it, I guess. [Megan brings out a laptop and connects to it.] Megan: It's offering up a drive with one file on it. Cueball: What's the file? Megan: An eBook. "Shel_Silverstein_-_The_Giving_Tree.azw" Cueball: Never heard of it. Let's take a look! Laptop: DRM Error: You have not purchased rights to view this title. Lending is not enabled. Cueball: Huh. Oh well. Megan: Let's go see what Mike is up to. [The tree is alone.]

Development

Development

https://www.xkcd.com/957

https://www.explainxkcd.com/wiki/index.php/957:_Development

[Cueball is a news anchor at desk reporting. Behind him to the left is a black screen showing a white icon of a hurricane moving over the black ocean towards a thin sliver of white land in the top left corner. There are three white question-marks around the hurricane.] Cueball: Fear turned to confusion today as Hurricane Rina developed to Piaget stage 5, with sustained interests in objects and their properties. Hurricane: ? ? ?

Cueball is a news anchor reporting on a hurricane. NHC is the National Hurricane Center and the APA is the American Psychological Association . The reference to Piaget Stage 5 in the comic is a reference to Piaget 's Stages of Development in which stage 5 is where (to quote Wikipedia and Gruber, H.E.; Voneche, J.J.. eds. The essential Piaget .) "'Infants become intrigued by the many properties of objects and by the many things they can make happen to objects; they experiment with new behavior.' This stage is associated primarily with the discovery of new means to meet goals. Piaget describes the child at this juncture as the 'young scientist,' conducting pseudo-experiments to discover new methods of meeting challenges." This is exactly what the comic is describing in sustained interest in objects and their properties and the handy "?"s around the picture behind the newscaster in this comic. With that out of the way, this comic is a pun on the use of the word "development" to classify hurricanes which also uses categories from 1 to 5 as defined by the Saffir-Simpson hurricane scale (Piaget's Stages go from 1-6). The comic is making a joke that if the APA were on hurricane forecast duty instead of the NHC, that the hurricanes would be classified with Piaget's stages instead of categories. [Cueball is a news anchor at desk reporting. Behind him to the left is a black screen showing a white icon of a hurricane moving over the black ocean towards a thin sliver of white land in the top left corner. There are three white question-marks around the hurricane.] Cueball: Fear turned to confusion today as Hurricane Rina developed to Piaget stage 5, with sustained interests in objects and their properties. Hurricane: ? ? ?

Hotels

Hotels

https://www.xkcd.com/958

https://www.explainxkcd.com/wiki/index.php/958:_Hotels

[Cueball is sitting at a desk with a laptop, looking at a review website] Cueball: What's with this negative review? You liked that hotel. Black Hat: I have a script that posts a bad review for every hotel I stay at. It reduces demand, which means more vacancies and lower prices next time. Cueball: What if the place sucks? Black Hat: I change the review to positive to steer other people over there. Cueball: You punish companies you like! Black Hat: The odds of my review putting a hotel out of business are negligible. Cueball: If we all did that the system would collapse! Black Hat: Doesn't affect my logic. Tragedy of the commons. Cueball: That's not even the tragedy of the commons anymore. That's the tragedy of you're a dick. Black Hat: If you're quick with a knife, you'll find that the invisible hand is made of delicious invisible meat.

In this comic, Black Hat is giving all the hotels he has stayed at, likes, and wants to stay in again bad reviews, in order to lower demand for said hotel. He is simultaneously putting good reviews on bad hotels to steer other people there so there are more vacancies at good hotels. He also claims he is not influential enough to put the good hotels out of business. But even if he didn't put the hotels out of business, the market would certainly still be affected, and all so he could enjoy a lower price, once again proving he's a classhole. The tragedy of the commons "is a dilemma arising from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately deplete a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this to happen." This situation is not a complete example of this concept as Black Hat is the only one doing it. He understands, however, that if others do it, it would apply. (Another example is what would happen using a certain strategy in the game Oregon Trail ). The logic is also similar to a conversation about fighting in the war in Catch-22 . Yossarian believed that he shouldn’t fight because America will win regardless of his involvement, so there is no point in him dying. In the last frame, Black Hat references the invisible hand which is the term coined by Adam Smith and used by economists use to describe the self-regulating nature of the marketplace. Black Hat appears to be taking advantage of this invisible hand by cutting it with a knife and eating it. The title text is an example of Black Hat's negative reviews, which in itself is a surrealist joke about the hotel. A somewhat believable (if exaggerated) set of complaints about an awful hotel is that the "Room filled to brim with bedbugs, and when front desk clerk opened mouth to talk, semen poured out". However instead, the objects of focus are reversed, creating a ridiculous scenario for the reader to enjoy, if they are not too disgusted by the imagery of the text. [Cueball is sitting at a desk with a laptop, looking at a review website] Cueball: What's with this negative review? You liked that hotel. Black Hat: I have a script that posts a bad review for every hotel I stay at. It reduces demand, which means more vacancies and lower prices next time. Cueball: What if the place sucks? Black Hat: I change the review to positive to steer other people over there. Cueball: You punish companies you like! Black Hat: The odds of my review putting a hotel out of business are negligible. Cueball: If we all did that the system would collapse! Black Hat: Doesn't affect my logic. Tragedy of the commons. Cueball: That's not even the tragedy of the commons anymore. That's the tragedy of you're a dick. Black Hat: If you're quick with a knife, you'll find that the invisible hand is made of delicious invisible meat.

Caroling

Caroling

https://www.xkcd.com/959

https://www.explainxkcd.com/wiki/index.php/959:_Caroling

[Three people, two the same size, one smaller stand together singing Christmas carols.] Carolers (in unison): Good king Wenceslas looked out on the— [Black Hat leans out of an above ground window.] Black Hat: King Wenceslas massacred my people. [The carolers stand in silence, the smaller one looks at the others.]

Here are the lyrics for the first verse of the Christmas Carol, " Good King Wenceslas " Good King Wenceslas looked out, on the Feast of Stephen, When the snow lay round about, deep and crisp and even; Brightly shone the moon that night, tho' the frost was cruel, When a poor man came in sight, gath'ring winter fuel. While not a king, Wenceslaus I, Duke of Bohemia is considered a martyr and a saint. Far from being responsible for any massacre, he protected his subjects from external dominance and is still a national hero to the Czech people. Black Hat is supplying disinformation to unsuspecting carolers, either to shut them up, by making them falsely think that they are associating themselves with a morally reprehensible man, or just because he's a classhole like that. The title text references "the Feast of Stephen ", also known as the "Feast of St. Stephen" or "St. Stephen's Day", which is a holiday celebrated on 26 or 27 December by the Western or Eastern Church respectively. (For the Eastern Orthodox Church , which still observes the Julian calendar , it falls on 9 January of the Gregorian calendar .) It is not actually a feast that involved eating a person named Stephen. [ citation needed ] If you look closely, you can see that the carolers may be a family. The man and woman are confused by what Black Hat has said, and the girl is looking to the adults, perhaps gauging their facial reactions, or just waiting for their reply. [Three people, two the same size, one smaller stand together singing Christmas carols.] Carolers (in unison): Good king Wenceslas looked out on the— [Black Hat leans out of an above ground window.] Black Hat: King Wenceslas massacred my people. [The carolers stand in silence, the smaller one looks at the others.]

Subliminal

Subliminal

https://www.xkcd.com/960

https://www.explainxkcd.com/wiki/index.php/960:_Subliminal

[Cueball and Megan are gathered around a computer. Cueball is seated interacting with the computer while Megan stands behind them with an arm resting on the back of the chair.] Cueball: What hidden arrow? Megan: I thought everyone knew about it. Pull up the FedEx logo. Click [Megan is now pointing at the screen.] Cueball: Where is it? Megan: Right there. Look at the whitespace. Cueball: I don't see it. [The next panel shows a stylised view of the FedEx logo. The white space above the 'ed' in Fed is decorated to look like a tank turret with the barrel extending into the letter 'F'. Along the bottom of the letters a baseball player with the number 24 on his back is reaching out to catch a baseball. The baseball is forming the centre of the 'e' while the arm provides the break for the tail. The baseballers head marks the centre of the 'd' and the number 24 is coloured in blue to show the lower half of the stroke of the 'd'. Toward the right of the image the space between the 'E' and 'x' has been decorated to look like a Guy Fawkes mask, with ties wrapping around the 'x' and being drawn off-screen. A faint outline suggests the whitespace above the 'x' is a hat, with the brim extending into the upper part of the 'E'. Two speech bubbles are visible above the drawing, both spoken by off-screen characters.] Cueball (off-screen): All I see is Guy Fawkes watching Willie Mays catch a fly ball while an armored assault vehicle rolls past. Megan (off-screen): ...You either need more medication or less. Not sure which.

This comic is about the FedEx logo and how there is a subliminal/hidden arrow in the logo; specifically, in the whitespace between the "E" and the "x". When Cueball looks at the logo, he instead sees a wild scene including Guy Fawkes , Willie Mays and an assault vehicle . Megan then replies "...You either need more medication or less. Not sure which." Which is implying that he is taking medication for some condition that causes him to hallucinate (or something similar). The implication being that he either needs more medication because it isn't working properly, or less medication because it is causing him to hallucinate in itself. Guy Fawkes was a British revolutionary who tried to blow up the Houses of Parliament in 1605. His likeness is nowadays used as a symbol of protest, most famously in the graphic novel and movie " V For Vendetta " and by Anonymous and the Occupy movement . Willie Mays was an American baseball player for the San Francisco Giants who made a famous over-the-shoulder catch in the World Series. Some consider it to be the best defensive play of all time in baseball. The title text is a play on the Internet idiom "once you see it, you can't unsee it," although it says that you can't unsee it until your body has finished processing the magic mushrooms , that you must have taken for some reason, which would be why you would keep seeing it in the first place. [Cueball and Megan are gathered around a computer. Cueball is seated interacting with the computer while Megan stands behind them with an arm resting on the back of the chair.] Cueball: What hidden arrow? Megan: I thought everyone knew about it. Pull up the FedEx logo. Click [Megan is now pointing at the screen.] Cueball: Where is it? Megan: Right there. Look at the whitespace. Cueball: I don't see it. [The next panel shows a stylised view of the FedEx logo. The white space above the 'ed' in Fed is decorated to look like a tank turret with the barrel extending into the letter 'F'. Along the bottom of the letters a baseball player with the number 24 on his back is reaching out to catch a baseball. The baseball is forming the centre of the 'e' while the arm provides the break for the tail. The baseballers head marks the centre of the 'd' and the number 24 is coloured in blue to show the lower half of the stroke of the 'd'. Toward the right of the image the space between the 'E' and 'x' has been decorated to look like a Guy Fawkes mask, with ties wrapping around the 'x' and being drawn off-screen. A faint outline suggests the whitespace above the 'x' is a hat, with the brim extending into the upper part of the 'E'. Two speech bubbles are visible above the drawing, both spoken by off-screen characters.] Cueball (off-screen): All I see is Guy Fawkes watching Willie Mays catch a fly ball while an armored assault vehicle rolls past. Megan (off-screen): ...You either need more medication or less. Not sure which.

Eternal Flame

Eternal Flame

https://www.xkcd.com/961

https://www.explainxkcd.com/wiki/index.php/961:_Eternal_Flame

[Two people before a memorial with an eternally spinning wait cursor. They contemplate silently on an influential life. Goodbye, Steve.]

Steve Jobs died on October 5, 2011, the day before this comic was posted. He was the CEO and one of the founders of Apple, Inc . He was the head of Apple for the introduction of OS X , the default operating system used on all modern Macintosh computers. In OS X when there is a significant slowdown, the Cursor becomes the symbol seen in the comic. It may appear when an application is not responding, or if the computer is busy. This symbol is infamous among OS X users, and is nicknamed "the beachball of death". It appears during a lag, and can take a very long time to disappear, thus seeming endless. The title and rotating cursor above a fixture in the ground seems to be referencing the John F. Kennedy Eternal Flame , suggesting that the rotating cursor above the fixture is, in fact, a monument to Steve Jobs. The title text refers to the fact that when an application is not responding on the Mac, the application sometimes recovers and the system comes back; other times, however, the damage is irrevocable, a Kernel Panic happens and the system needs a restart. A similar tribute comic was also dedicated to Terry Pratchett , the day after he died, in 1498: Terry Pratchett , to Gary Gygax , three days after he died, in 393: Ultimate Game , and to John Horton Conway , two days after he died, in 2293: RIP John Conway . [Two people before a memorial with an eternally spinning wait cursor. They contemplate silently on an influential life. Goodbye, Steve.]

The Corliss Resolution

The Corliss Resolution

https://www.xkcd.com/962

https://www.explainxkcd.com/wiki/index.php/962:_The_Corliss_Resolution

[Cueball with an unusual suit runs right with a small cloud behind his legs. The frame of the panel is only two thirds the normal height and above the frame is the text from the narrator:] Narrator: The Fermi Paradox: Planets are so common that life should be too. So where is it? [Cueball keeps running with the small cloud behind his legs. Above him there are two frames with narration:] Narrator: Well, now we know. Narrator: It's not that life inevitably destroys itself with war. [Cueball leaps into the air off a jagged cliff edge with gray cliffs. The image frame only covers a small part of the center of this panel. Narration text is shown both above and below the image:] Narrator: It's just that it takes longer to develop space colonization. Narrator: Than it does to invent an activity [A Youtube video is shown with the usual icons in the black bar below the image; play, volume, full screen etc. The video shows Cueball soaring downwards as indicated with four speed lines behind his spread out arms and legs. The strange suit has opened up revealing it to be a wingsuit. The sound is on and Cueball can be heard. Above the video frame there is a final narration text in a frame. Two people are watching the video together off-panel and their comments are shown below in two voice bubbles with arrows pointing left and right.] Narrator: More fun than survival. Cueball: Wheeeee! Off-panel voice #1: Holy crap. Off-panel voice #2: I don't care how dangerous it is. I have to try it.

Jeb Corliss is a professional BASE jumper and wingsuit flyer, like in the fourth panel. Corliss has jumped from a lot of different buildings and monuments in the world. Hence, the Corliss Resolution. The Fermi paradox is an astronomical problem that states: "The universe is large enough that many planets should have extraterrestrial intelligent life. Why, then, haven't we detected any signs of it?" The paradox has numerous hypothetical solutions — some say that life is much rarer than we think, and others suggest that civilizations will eventually destroy themselves (as mentioned in the comic). Randall proposes another solution to the Fermi paradox: before they can develop space travel and the like, civilizations will inevitably invent an "activity more fun than survival." That is, something fun that's also very dangerous, such as flying off a cliff in a wingsuit. As said in the title text, a being that can already fly (hence "avian society") would probably prefer flying around outside over developing the tools needed for space colonization. See 384: The Drake Equation for another comic about intelligent life in the universe. [Cueball with an unusual suit runs right with a small cloud behind his legs. The frame of the panel is only two thirds the normal height and above the frame is the text from the narrator:] Narrator: The Fermi Paradox: Planets are so common that life should be too. So where is it? [Cueball keeps running with the small cloud behind his legs. Above him there are two frames with narration:] Narrator: Well, now we know. Narrator: It's not that life inevitably destroys itself with war. [Cueball leaps into the air off a jagged cliff edge with gray cliffs. The image frame only covers a small part of the center of this panel. Narration text is shown both above and below the image:] Narrator: It's just that it takes longer to develop space colonization. Narrator: Than it does to invent an activity [A Youtube video is shown with the usual icons in the black bar below the image; play, volume, full screen etc. The video shows Cueball soaring downwards as indicated with four speed lines behind his spread out arms and legs. The strange suit has opened up revealing it to be a wingsuit. The sound is on and Cueball can be heard. Above the video frame there is a final narration text in a frame. Two people are watching the video together off-panel and their comments are shown below in two voice bubbles with arrows pointing left and right.] Narrator: More fun than survival. Cueball: Wheeeee! Off-panel voice #1: Holy crap. Off-panel voice #2: I don't care how dangerous it is. I have to try it.

X11

X11

https://www.xkcd.com/963

https://www.explainxkcd.com/wiki/index.php/963:_X11

[The comic is a graph with a curve starting at (0,0) that snakes toward the upper right of the graph. The axes are labelled:] x axis: Time since I last had to open Xorg.conf y axis: General satisfaction with how my life is going

X11 is the X window system (commonly X Window System or X11, based on its current major version being 11). It is a computer software system and network protocol that provides a basis for graphical user interfaces (GUIs) and rich input device capability for networked computers. The X11 stacks are usually implemented using a display server. The reason that it is called a display server is that the actual viewer and the server do not need to be on the same system; X11 frequently runs over a network connection. This adds considerably to the complexity of the mechanism. Most UNIX-based operating systems, including Linux and the BSDs use X11 as their base graphical subsystem and thus always use a display server and a display client. MacOSX has built-in support for X11, but does not use it for normal applications. For Windows, commercial and free solutions implementing an X11 display client exist. Until 2004, for Linux the default display server was XFree86 . This project required a variation of the config file that Randall mentions. It was forked into Xorg due to disagreements over the development model. Xorg is nowadays the default display server: X.Org Server (commonly abbreviated to Xorg Server, XServer or just X) refers to the X server release packages stewarded by the X.Org Foundation, which is hosted by freedesktop.org , and provides an interface to the standard X Window releases for the use of the free and open source software community. Every aspect of XFree86 and Xorg can be modified in numerous ways, all the way down to tiny behaviors such as the default window size, window-border snapping, mouse button maps or how a touchpad is used. All of these settings can be found in the xorg.conf file, a massive file with hundreds upon thousands of individual settings that have accumulated over the lifetime of the Xorg project. The full documentation for xorg.conf contains all the settings contained within the file. When a problem arises in the graphical portion of a desktop using the X server, the solution may be to edit the xorg.conf file. The soul-crushing prospect of having to open and look up the correct parameter out of thousands that is causing issues is enough to destroy a person's satisfaction with their life. Editing xorg.conf (especially manually) is much less necessary than it used to be. In fact, some distributions do not even come with an xorg.conf file, because everything necessary can be auto-detected and/or configured elsewhere. The Wayland project aims to replace some of X11 and not include any of the cruft that built up over the decades. It was started in 2008, way more than 19 years after the aforementioned config file turned into a hell. The title text references a letter Thomas Jefferson wrote to James Madison on the popular basis of political authority. There are a few quotes that can be pulled to sum up his ideas. To keep our ideas clear when applying them to a multitude, let us suppose a whole generation of men to be born on the same day, to attain mature age on the same day, and to die on the same day, leaving a succeeding generation in the moment of attaining their mature age all together. Let the ripe age be supposed of 21. years, and their period of life 34. years more, that being the average term given by the bills of mortality to persons who have already attained 21. years of age. In his day most people lived only to age 55, so he supposes that a person reaches maturity at 21, and will live until 55 and then die. For the purposes of the other arguments he makes in the letter, he also supposes that all the people of a generation are born on the same day, and that they will all die on the same day: the day they turn 56. Then I say the earth belongs to each of these generations, during its course, fully, and in their own right. Since only one generation is alive in his example, his model allows for that generation to do as they please for their time on earth, elsewhere in the letter he describes that each generation should not be able to leave the next generation in a worse position, so the debts accrued by one generation must be paid off by that generation. This has built us up to the quote that everyone attaches onto. Every constitution then, and every law, naturally expires at the end of 19 years. If it be enforced longer, it is an act of force, and not of right. -It may be said that the succeeding generation exercising in fact the power of repeal, this leaves them as free as if the constitution or law has been expressly limited to 19 years only. Because a generation reaches maturity at 21, and at that point the previous generation dies off, and this generation has 19 productive years until they are 40 and have 15 years of senility until their own death they have full reign of the earth as they please. Continuing on under the laws (and debts) of the previous generation is "an act of force, and not of right". Jefferson picked 19 years because that was the length of time a generation spent in power, not that every 19 years all laws should be abolished, but that every generation, each new generation should tear down all the systems put in place, re-evaluate, and build better laws, systems, and constitutions. [The comic is a graph with a curve starting at (0,0) that snakes toward the upper right of the graph. The axes are labelled:] x axis: Time since I last had to open Xorg.conf y axis: General satisfaction with how my life is going

Dorm Poster

Dorm Poster

https://www.xkcd.com/964

https://www.explainxkcd.com/wiki/index.php/964:_Dorm_Poster

[Cueball finds dorm room.] [View into the dorm room. The left half is already occupied, and a roommate has filled his side with the normal accoutrements of dorm life. There is a Pink Floyd "Dark Side of the Moon" poster hanging on the far wall, offset and only on the roommate's side.] [Cueball has a bit of a ponder.] [Cueball leaves for a bit.] [Cueball returns with an item.] [View into the dorm room. Cueball is moving in, and has placed a second Pink Floyd "Dark Side of the Moon" poster modified with a lens in the rainbow's path. The poster is placed upside down on Cueball's side of the far wall to catch the rainbow, feed it back into the prism, and turn it back into a narrow stream of white light.]

The poster on the wall is the album artwork, by Hipgnosis , for Pink Floyd's album The Dark Side of the Moon . It shows a beam of light passing through a dispersive prism and separating into a rainbow. After thinking a bit, the new student makes a poster that uses a lens to reverse the rainbow into another prism, likely to mess with his new roommate. This idea actually isn't very innovative, because the original backside of the album contained the reverse rainbow and prism (but not the lens). The setup with two prisms was used by Isaac Newton to prove that white light is composed of different colors of light. In the title text, Randall makes the joke that by recording a record under the name "Pink FTFY" (fixed that for you), the name of his band would come immediately after Pink Floyd alphabetically, so the album would be to the right of Pink Floyd's album for Dark Side of the Moon, allowing for the same image seen in the back of the dorm room to be on the shelves of the record store. Since the cover of his album would be catching the light from Pink Floyd's album and forming white light once again, Randall would be "fixing" the cover of Dark Side of the Moon. However Randall makes the crack that no one would see the joke, because of the fact music can be bought and downloaded online, which has decreased the traffic the record stores in recent years. [Cueball finds dorm room.] [View into the dorm room. The left half is already occupied, and a roommate has filled his side with the normal accoutrements of dorm life. There is a Pink Floyd "Dark Side of the Moon" poster hanging on the far wall, offset and only on the roommate's side.] [Cueball has a bit of a ponder.] [Cueball leaves for a bit.] [Cueball returns with an item.] [View into the dorm room. Cueball is moving in, and has placed a second Pink Floyd "Dark Side of the Moon" poster modified with a lens in the rainbow's path. The poster is placed upside down on Cueball's side of the far wall to catch the rainbow, feed it back into the prism, and turn it back into a narrow stream of white light.]

Elements

Elements

https://www.xkcd.com/965

https://www.explainxkcd.com/wiki/index.php/965:_Elements

[Aang the Avatar and Dmitri Mendeleev stand in opposition to each other. Aang wields all 4 classical elements: Water, Fire, Earth, and Air.] Aang: I'm the avatar, master of all 4 elements! Mendeleev: Really? I'm Mendeleev, master of all 118+. swoosh Mendeleev: That was polonium-bending. You probably didn't feel anything, but the symptoms of radiation poisoning will set in shortly.

In the popular children's TV show Avatar: The Last Airbender , the four nations that inhabit the world can each telekinetically control one of the four classical elements: water, earth, fire and air. One person, the avatar, can control all four elements and is markedly more powerful than any other character. Dmitri Mendeleev is the creator of the modern periodic table, which categorizes the 118+ atomic elements by their atomic number. The comic is comparing the control over more magical power with more practical, "science-y" power. Fire, boulders, and storms may be more impressive visually, but science has proven time and again the "boring" can have very practical, very deadly applications. Additionally, while the advantages of controlling the four alchemical elements are mostly physical and visible (characters in the show most often use their powers to push, throw, or create barriers), the phenomena related to Mendeleev's elements and his research include subatomic particle interactions. One power the depicted Mendeleev has that the Avatar definitely does not have is control over radioactive elements, and this is the subtle, slow-acting power he demonstrates. Polonium gained a level of notoriety as the poison used to kill Russian dissident Alexander Litvinenko . The title text talks about power levels of the elements if each element had a controlling nation as per the TV show. Ununoctium (1-1-8-ium) was the placeholder name for Oganesson , the 118th element. It did not officially gain its permanent name until late 2016, 5 years after this comic was released. Oganesson is the heaviest element that has been created, as well as the one with the shortest life before it decays into other elements. Xenon is a noble gas with few practical applications, but it is sometimes used in "neon" signs. [Aang the Avatar and Dmitri Mendeleev stand in opposition to each other. Aang wields all 4 classical elements: Water, Fire, Earth, and Air.] Aang: I'm the avatar, master of all 4 elements! Mendeleev: Really? I'm Mendeleev, master of all 118+. swoosh Mendeleev: That was polonium-bending. You probably didn't feel anything, but the symptoms of radiation poisoning will set in shortly.

Jet Fuel

Jet Fuel

https://www.xkcd.com/966

https://www.explainxkcd.com/wiki/index.php/966:_Jet_Fuel

[Hairy throws his arms out as he talks to Cueball, who answers while lifting a hand palm up.] Hairy: 9/11 was an inside job! Jet fuel can't burn hot enough to melt steel! Cueball: Well, remember — jet fuel wasn't the only thing on those planes. They would've also carried tanks full of the mind-control agents airliners use to make chemtrails. Cueball: Who knows what temperature that stuff burns at! Hairy: Whoa. Hairy: Good point! [Caption below the panel:] My Hobby: Playing conspiracy theories off against each other. For those wondering: it is true that kerosene does not burn hot enough in air to melt steel, but it does burn hot enough to cut the steel's supporting strength roughly in half, which is more than enough to collapse a building weighing thousands of tons. (Although standard engineering practice is to use a safety factor of three, and a safety factor of two is sufficient to allow for a 50% reduction in strength, over half of the columns in the two towers were severed in the initial impact, increasing the stress on the remaining columns.) Cueball messing with 9/11 truther conspiracy theorists was also the subject of 690: Semicontrolled Demolition , and in 496: Secretary: Part 3 Black Hat claims the Twin Towers never actually collapsed. Chemtrails are mentioned again later in 1677: Contrails and 1803: Location Reviews .

This is another one of the " My Hobby " series, where Randall tells about a strange hobby. This comic is a reference to the " 9/11 Was An Inside Job " theory that the World Trade Center in New York City was blown up by a "controlled demolition". This is a fairly common argument that is seen on the internet. Hairy 's statement that "jet fuel can't burn hot enough to melt steel" references a common argument used by conspiracy theorists in references to the attacks. The official investigation concluded that the combination of the impact of the jets and the subsequent fire sufficiently compromised the structural steel beams of the towers that they lost integrity and collapsed. People who do not accept this conclusion frequently insist that the flame temperatures resulting from burning jet fuel is less than the melting point of steel, and so argue that the official explanation must be wrong, supporting their argument that the towers were deliberately brought down by explosives, planted by some conspiracy. This argument has been frequently refuted by experts , on a number of grounds. No fuel has a single burning temperature, the temperature of any given flame depends on a number of factors, which can be hard to predict in uncontrolled situtions. In addition, multiple fuels could have contributed to the fire, including not only the jet fuel but also flammables inside the building, and even metals (such as aluminum) that would have been pulverized and dispersed by the impact. Importantly, it is not necessary for beams to melt in order to collapse a building. Metals lose much of their structural strength well below their melting point. If enough beams were sufficiently weakened, they would fail under the weight of the building, putting more pressure on the remaining beams, which would then be likely to fail, and so on. Cueball, however, doesn't argue with Hairy's premises, but instead tries a different tack, by appealing to a completely different conspiracy theory, concerning chemtrails . The Chemtrails conspiracy theory claims that the Contrails left behind aircraft contain mind-control agents planted by the US Government (or any other government, reptiloids , Freemasons , etc.), which are used to drug the population en masse. Cueball operates under the assumption that this theory is true, and points out that this means typical passenger jets would be equipped with containers of these drugs, which could potentially burn at a high temperature. Because these drugs are entirely hypothetical, no assumption about them can possibly be disproven. This puts Hairy in a position of either having to argue against the chemtrail conspiracy theory, while arguing for a 9/11 conspiracy theory or admit that there are factors he can't account for. This is unlikely to shake Hairy from his beliefs, but Cueball appears to find it entertaining to force a conspiracy theorist to confront the contradictions between conspiracy theories. The title text is the natural "double down" on a theory which says that the conspiracy theory itself was concocted by the government and was supposed to distract from the truth, a parodic theory already seen in South Park episode Mystery of the Urinal Deuce . [Hairy throws his arms out as he talks to Cueball, who answers while lifting a hand palm up.] Hairy: 9/11 was an inside job! Jet fuel can't burn hot enough to melt steel! Cueball: Well, remember — jet fuel wasn't the only thing on those planes. They would've also carried tanks full of the mind-control agents airliners use to make chemtrails. Cueball: Who knows what temperature that stuff burns at! Hairy: Whoa. Hairy: Good point! [Caption below the panel:] My Hobby: Playing conspiracy theories off against each other. For those wondering: it is true that kerosene does not burn hot enough in air to melt steel, but it does burn hot enough to cut the steel's supporting strength roughly in half, which is more than enough to collapse a building weighing thousands of tons. (Although standard engineering practice is to use a safety factor of three, and a safety factor of two is sufficient to allow for a 50% reduction in strength, over half of the columns in the two towers were severed in the initial impact, increasing the stress on the remaining columns.) Cueball messing with 9/11 truther conspiracy theorists was also the subject of 690: Semicontrolled Demolition , and in 496: Secretary: Part 3 Black Hat claims the Twin Towers never actually collapsed. Chemtrails are mentioned again later in 1677: Contrails and 1803: Location Reviews .

Prairie

Prairie

https://www.xkcd.com/967

https://www.explainxkcd.com/wiki/index.php/967:_Prairie

[Megan and Cueball stand in a field of wheat, facing away from the panel. The figures are drawn in the typical black and white stick figure style, but the field is immensely detailed, with the grain coloured a rich amber and stroked such that individual stalks can be picked out, with a few dark bands providing contrast. In the distance a low mountain range is visible and in the sky a few scattered fluffy white clouds float low over the horizon.] Megan: Well, when we observe them, they become amber particles of grain.

This comic refers to the song America the Beautiful , which contains the line "amber waves of grain," which refers to the plentiful wheat fields in the Midwestern US. The waves, in this context, are being likened to the waves in the ocean, as the wind can make the wheat move in such a way as to resemble waves. In quantum mechanics the wave-particle duality explains that particles can act like both particles and waves, depending on the context. Using a comedic adaptation of quantum theory, Megan states that the waves of grain become particles of grain when observed, which, in a way, is true. However, this is not a perfect analogy because each grain is a separate entity while an external force, the wind, is what produces the wave motion. The title text builds on the quantum mechanics principle that a laser is a coherent wave . This leads of the absurd notion that one could harness waves in grain fields for use as a laser weapon, which would be used by one state to destroy two neighbors. There is a long running joke in the Rocky Mountain West of completely obliterating nearby states, and in particular Nebraska. The use of the word "majestic" to describe the laser is a reference to another line in "America the Beautiful" — "for purple mountain majesties" — which does in fact allude to the Rocky Mountains in Colorado. [Megan and Cueball stand in a field of wheat, facing away from the panel. The figures are drawn in the typical black and white stick figure style, but the field is immensely detailed, with the grain coloured a rich amber and stroked such that individual stalks can be picked out, with a few dark bands providing contrast. In the distance a low mountain range is visible and in the sky a few scattered fluffy white clouds float low over the horizon.] Megan: Well, when we observe them, they become amber particles of grain.

Everything

Everything

https://www.xkcd.com/968

https://www.explainxkcd.com/wiki/index.php/968:_Everything

[Cueball drags a small wagon and a bag full of various items.] Cueball: You are not the light of my life. Making you happy isn't my greatest dream. [Cueball places the items in an even bigger pile of even more random items.] Cueball: Your smile is not all I live for. I've got my own stuff going on. But you're strange and fascinating and I've never met anyone like you. [Cueball stares in awe as Megan assembles the items into a gargantuan, intoxicatingly complex machine.] Cueball: I want to give you everything just to see what you would do with it. A larger version can be found here:

In traditional western cliches of romance, men are expected to give women particular gifts (including flowers, candy and stuffed animals) and make declarations about how that woman is the sole focus of his life. This strip deliberately subverts those expectations by renouncing those sentiments and giving a decidedly non-traditional set of gifts, but making clear that this is a touching expression of love between these two parties. Cueball is gathering a lot of different sorts of random things, including a parasol , a miniature Eiffel Tower , what appears to be a small round bomb with a short fuse and the bust of a mannequin . He adds these to an already immense pile of weird things including balloons and a cage with a bird. While this happens Cueball narrates in short sentences. The first three are statements that at first seems similar to what you would find on a birthday or anniversary card from one person in a relationship to another, but in this case, all the statements ends up being negative, or at least neutral. The negative continues in the fourth statement, but then it turns around and ends up kind of positive. It turns out to be Megan he is talking about who is shown applying a hammer to the front of a large and strange vehicle while standing on one of its huge wheels. She seems to have built this giant super tank/machine from anything Cueball supplies her with, having several huge pigged wheels, a mounted gun, satellite dish, a crane and smoke coming out of an exhaust pipe at the top, implying it is already running it seems quite a disturbing tank she is creating. But Cueball is very fascinated by her strangeness. Cueball's final statement is also positive: I want to give you everything (hence the title), which could have been on a card as it is. But the reason is unusual (and written at the bottom right at the very end as his final statement). The reason he wishes to give her everything is because what she does is so strange and fascinating so he does this just to see what you would do with it , referring to whatever it is Megan is building now (or later). Some of the objects in the piles in the second panel can easily be determined, like the two balloons. But most others are more difficult to recognize. To the left there is what appears to be a cage with an animal inside, could be a bird. To the right there appears to be the hilt of a sword (maybe stuck in a stone, see 1521: Sword in the Stone ). Finally the tall thin thing sticking out of the top left of the right pile could be the stuffed giraffe from 604: Qwertial Aphasia . There are other distinct things, like the tall "cylinder" and the three "cannonballs" in a pyramid pile to the left, and something with a peculiar shape between the "giraffe" and the sword hilt. But it seems impossible to determine what they are. The title text similarly starts with the conventional Beatles love song " I Want to Hold Your Hand " but for an unconventional reason to not fall out of a gyrocopter. A gyrocopter is a flying machine that has a rotor like a helicopter , but the rotor is not powered by a motor. Rather, the motor of the gyrocopter drives a propeller that accelerates the machine forward, while the air rushing past the rotor drives the rotor like a helicopter during autorotation . [Cueball drags a small wagon and a bag full of various items.] Cueball: You are not the light of my life. Making you happy isn't my greatest dream. [Cueball places the items in an even bigger pile of even more random items.] Cueball: Your smile is not all I live for. I've got my own stuff going on. But you're strange and fascinating and I've never met anyone like you. [Cueball stares in awe as Megan assembles the items into a gargantuan, intoxicatingly complex machine.] Cueball: I want to give you everything just to see what you would do with it. A larger version can be found here:

Delta-P

Delta-P

https://www.xkcd.com/969

https://www.explainxkcd.com/wiki/index.php/969:_Delta-P

[An open wardrobe, with a boat anchor attached to one corner, falling towards water.] [Below the water line a formula with its variables explained is shown:] Q = A * sqrt(2 * g * d) Q = flow rate A = area of opening d = ocean depth (2 km) g = Earth gravity [And below the formula:] Flow: ~400,000 liters / s Water jet velocity: ~200 m / s [Caption below the frame:] The White Witch didn't know what hit her.

The Lion, the Witch and the Wardrobe is a book in which four children accidentally wander into a world known as Narnia through a wardrobe that only allows passage through to Narnia when you aren't looking for it. In the comic, someone connects an anchor to the wardrobe and throws it into the ocean. The formula describes the flow of water through the open doors when the wardrobe sits at the bottom of the ocean in 2 km depth, which means that a steady stream of water at an approximate velocity of 200 meters per second will flow into Narnia. The evil White Witch , who has made it "always winter, and never Christmas," could not have anticipated that a wardrobe portal would suddenly begin spewing approximately 400,000 liters of water per second into Narnia. [ citation needed ] Sea water freezes at low temperatures and flowing water freezes at even lower temperatures, depending how fast it is going. Water jetting out from this portal would be flowing very quickly indeed, approximately 200 meters per second (450 mph or 720 km/h) as the comic says; this is over half the speed of sound. And the water flow is approximately 400,000 liters per second, again, provided in the image above. The force of this water jet would be incredible. This water would not freeze. First it would decimate any forest trees or iron lamp posts in front of it until it eventually slowed down and fell to the ground. There it would create a rapidly expanding river of sea water. Narnia would not stay frozen for long. Snow would melt, ice would break apart and the valley would quickly flood. Delta-P is a mathematical term for the difference in pressure. The shown formula is based on the Hagen–Poiseuille equation which can be applied to a flowing liquid in a long cylindrical pipe; thus the equation here results in an unphysically high flow rate because the opening is rectangular and too short for a laminar flow . Using the Hagen–Poiseuille equation the maximum flow rate is given by: is the pipe cross-sectional area (m 2 ) and is the fluid density (kg/m 3 ). From the hydrostatics of water the pressure difference depends on gravity and the height: is the gravitational acceleration (m/s 2 ) and is the height (m). Putting this together and changing the cross-sectional area to a rectangular area we get the formula used by Randall: Assuming the wardrobe is two meter high and one in width ( A = 2 m 2 ) and using the gravitational constant g = 9.81 m/s 2 the flow rate is 396 m 3 per second, or roughly 400.000 liters per second. The water jet velocity v is based on Torricelli's law : It gives 198 m / s in this scenario. The title text references the video game Portal in which you solve puzzles using a gun which projects portals onto certain surfaces. In the game you cannot shoot a portal through a portal, but Randall says that if you try to create a portal with the portal gun through the wardrobe, space and time knot together. C. S. Lewis's The Chronicles of Narnia series (like most of his writing) is influenced by his views on Christianity and morality (he did not set out to write a "Christian story", but later accepted that there are many parallels between the Chronicles and his faith), with Aslan the lion representing Jesus Christ. As such, Aslan often provides lessons and advice on morality and faith to the main characters; however, the Space Sphere (a minor character in the game Portal 2 ) is a barely-sentient AI whose only preoccupation is going to space, and it would not be receptive to Aslan's teachings. The Space Sphere might be more interested in Lewis's The Space Trilogy , a trilogy of science-fiction books in which the main character travels through space and learns that the divine struggles between good and evil on Earth are also reflected elsewhere in the solar system. [An open wardrobe, with a boat anchor attached to one corner, falling towards water.] [Below the water line a formula with its variables explained is shown:] Q = A * sqrt(2 * g * d) Q = flow rate A = area of opening d = ocean depth (2 km) g = Earth gravity [And below the formula:] Flow: ~400,000 liters / s Water jet velocity: ~200 m / s [Caption below the frame:] The White Witch didn't know what hit her.

The Important Field

The Important Field

https://www.xkcd.com/970

https://www.explainxkcd.com/wiki/index.php/970:_The_Important_Field

[A soldier with a green military hat, with an black emblem on the front, is sitting in an office chair typing at his computer. Sounds are shown when he types, and the message he reads on the screen is shown above with a zigzag line coming from the computer screen. In the first panel he only uses one hand on the keyboard.] Computer: Welcome to the missile launch web interface! Click [Same setting but the soldier types with both hands.] Computer: Enter the target's coordinates. Type Type [Same setting as previous panel.] Computer: Enter your email address for our records. Type Type [Same setting except the soldier has stopped typing.] Computer: Enter your email again, to ensure you typed it correctly.

In this comic, a soldier with a green hat with a black emblem on the front, is using his computer to access an online web interface to launch a missile at a target. The joke is that even though the interface only asks him to enter the target coordinates once, it asks for his email address twice, even though the coordinates are by far the more important detail to get right (launching the missile at the wrong target could result in a disastrous loss of life or property damage). It is common for online interfaces to force users to type certain details twice, as a form of redundancy checking to ensure that the user really has entered the correct details and hasn't made an error. Some forms even go the extra step of preventing the user from copy-pasting into the second field, which would render it useless as a redundancy check. This is usually done for email addresses and when creating new passwords, which are used to identify and authenticate users, and are therefore important to get right. In the title text, Randall suggests that the presence of redundancy checks can give you an interesting insight into what things people deem to be important. He gives a (supposed) real-life example of a merchant that requires only one form of ID in order to buy a gun, but two forms if you want to pay for it by check - suggesting that the seller is more worried about the safety of their money than the potential danger of giving a lethal weapon to someone untrustworthy. [A soldier with a green military hat, with an black emblem on the front, is sitting in an office chair typing at his computer. Sounds are shown when he types, and the message he reads on the screen is shown above with a zigzag line coming from the computer screen. In the first panel he only uses one hand on the keyboard.] Computer: Welcome to the missile launch web interface! Click [Same setting but the soldier types with both hands.] Computer: Enter the target's coordinates. Type Type [Same setting as previous panel.] Computer: Enter your email address for our records. Type Type [Same setting except the soldier has stopped typing.] Computer: Enter your email again, to ensure you typed it correctly.

Alternative Literature

Alternative Literature

https://www.xkcd.com/971

https://www.explainxkcd.com/wiki/index.php/971:_Alternative_Literature

[Cueball and a friend stand in front of Cueball's bookcase. His friend flips through a number of them.] Friend: All your books are full of blank pages. Cueball: Not true. That one has some ink on page 78. Friend: A smudge. Cueball: So? Friend: There are no words. You're not reading. There's no story there. Cueball: Maybe not for you. When I look at those books, I think about all kinds of stories. Cueball: Reading is about more than what's on the page. Holding a book prompts my mind to enrich itself. Frankly, I suspect the book isn't even necessary. Cueball: The whole industry is evil. Greedy publishers and rich authors try to convince us our brains need their words. But I refuse to be a sucker. Friend: Who sold you all these blank books?

While the comic is funny on its own in a " Wake Up , Sheeple " kind of way, the title text reveals that the comic is a parable about homeopathy . The comic title is a play on alternative medicine . In the comic, it is implied that Cueball has been scammed into buying blank books, though he attempts to defend it as a valid choice (ironically, he thinks that it is the other people who are being scammed, not he). The title text likens this to the CVS Pharmacy selling homeopathic pills using methods that does not clearly distinguish them from real pharmaceuticals. Homeopathy is a pseudoscience based on the idea that a substance that causes the symptoms of a disease in healthy people will cure that disease in sick people if administered in sufficiently small doses. It is possible that Cueball actually bought blank notebooks and is scamming himself into believing he made a valid and logical choice. Homeopathic remedies are prepared by repeatedly diluting a substance with alcohol or water . Somewhat counter-intuitively, homeopathy considers the weakest dilutions to have the most powerful healing effect. Frequently, in fact, the dilutions are repeated past the point where any number of molecules of the "active ingredient" can remain. Selling a homeopathic remedy as actual medicine when it is just water is analogous to selling blank books. The smudge of ink Cueball mentions in the comic may be referencing the fact that some of the less diluted homeopathic remedies can contain a tiny amount of the original substance. [Cueball and a friend stand in front of Cueball's bookcase. His friend flips through a number of them.] Friend: All your books are full of blank pages. Cueball: Not true. That one has some ink on page 78. Friend: A smudge. Cueball: So? Friend: There are no words. You're not reading. There's no story there. Cueball: Maybe not for you. When I look at those books, I think about all kinds of stories. Cueball: Reading is about more than what's on the page. Holding a book prompts my mind to enrich itself. Frankly, I suspect the book isn't even necessary. Cueball: The whole industry is evil. Greedy publishers and rich authors try to convince us our brains need their words. But I refuse to be a sucker. Friend: Who sold you all these blank books?

November

November

https://www.xkcd.com/972

https://www.explainxkcd.com/wiki/index.php/972:_November

[Black Hat and Cueball sit in a room.] Black Hat: Did you know November is Tongue Awareness Month? [Cueball is suddenly aware of his tongue.] [Cueball continues to be aware of his tongue.] [Cueball is painfully aware of his tongue.] Cueball: I hate you. Black Hat: Enjoy the next four weeks.

This comic is a homage to Charles Schulz , the creator of the comic Peanuts , who was born on November 26, 1922. Both comics carry the idea that when you start thinking about your tongue, you can hardly stop thinking about it. (Similarly: if you start thinking about your breathing, you stop breathing unless you consciously think to breathe, same goes for blinking.) This is similar to the ironic process theory , where trying to not think about something will invariably make you think about it. The intention of Black Hat in this comic is for Cueball to consciously feel his tongue for the entire month of November. Since it was Black Hat's idea, Black Hat probably suffers the same consequences. This is similar, in concept, to the expression and phrase used for trolling in online communities, " You Are Now Breathing Manually ". The line "you are now aware of your tongue" was mentioned much later in the title text of 2563: Throat and Nasal Passages . Here it was throat and nasal passages awareness which was the subject, due to the, at that time, two year long 2020 COVID-19 pandemic . [Black Hat and Cueball sit in a room.] Black Hat: Did you know November is Tongue Awareness Month? [Cueball is suddenly aware of his tongue.] [Cueball continues to be aware of his tongue.] [Cueball is painfully aware of his tongue.] Cueball: I hate you. Black Hat: Enjoy the next four weeks.

MTV Generation

MTV Generation

https://www.xkcd.com/973

https://www.explainxkcd.com/wiki/index.php/973:_MTV_Generation

[Teenager playing with phone walks in background. White Hat and Megan are in the foreground.] White Hat: See, that's the problem with the MTV generation— No attention span. Teenager's phone: Bleep bloop [White Hat and Megan in frameless panel without teenager from previous panel.] Megan: You know, that phrase referred to the 12-19 demographic that formed the core MTV audience in the mid-1980s. [Zoom in on Megan with White Hat off-panel to the left.] White Hat (off-panel): Uh huh? So? Megan: That generation's now in their 40s. [Zoom back out to White Hat and Megan, with White Hat scratching his head.] White Hat: That can't be right. Megan: Face it: Your problem with the MTV generation is their kids .

MTV stands for "Music Television", which is the name of a US-based cable channel, founded in 1981, specifically focusing on popular music and the music industry in general. The programming largely (though not exclusively) consisted of music videos . The focus of the channel has since shifted to reality shows . In the channel's heyday in the 1980's and early 1990's, it was popular with teenagers and young adults. As is often the case with youth culture, it was roundly condemned by some adults as being destructive and pointless. One of the specific criticisms was that the format of short videos, with quick-edit, highly kinetic visual styles and no underlying narrative was destroying the attention span of the youth. Despite MTV no longer being especially popular (and no longer focusing on music videos), people still use the term MTV Generation to refer to the young cohort, and insist that they have poor attention spans, resulting from their media exposure. Megan explains that the term really originated about 25 years ago, to describe Generation X , the generation born from 1965 to 1980. The actual MTV generation has long since grown up, and most young people today either don't watch MTV, or have no idea that it was originally a music channel. Teenagers today are the children of "the MTV generation" (and even their grandchildren, in some cases). The Breakfast Club is an iconic movie from 1985 in which 5 teenagers spend a Saturday detention together at school. Principal Vernon was the overseer of the detention, and a symbol of authority and oppression of youth - the actor playing principal Vernon was around 45 years old at the time of filming. The irony is that many adults who grew up watching the movie still identify with the teenagers, but now have little in common with them. There are a couple of themes in this strip that Randall has covered before. One is mocking adults for the assumptions they make about young people, youth culture and new technology. Adults have a tendency to whitewash the past, and insist that modern young people are being corrupted by new trends. And when that generation of youth grows up, they tend to make the same assumptions about the next generation. 1601: Isolation , 1227: The Pace of Modern Life , 1414: Writing Skills , 1348: Before the Internet Another theme is making people feel old by pointing out how long ago their common memories are, as in 647: Scary , 891: Movie Ages , 1393: Timeghost , 1477: Star Wars , and 2165: Millennials . [Teenager playing with phone walks in background. White Hat and Megan are in the foreground.] White Hat: See, that's the problem with the MTV generation— No attention span. Teenager's phone: Bleep bloop [White Hat and Megan in frameless panel without teenager from previous panel.] Megan: You know, that phrase referred to the 12-19 demographic that formed the core MTV audience in the mid-1980s. [Zoom in on Megan with White Hat off-panel to the left.] White Hat (off-panel): Uh huh? So? Megan: That generation's now in their 40s. [Zoom back out to White Hat and Megan, with White Hat scratching his head.] White Hat: That can't be right. Megan: Face it: Your problem with the MTV generation is their kids .

The General Problem

The General Problem

https://www.xkcd.com/974

https://www.explainxkcd.com/wiki/index.php/974:_The_General_Problem

[Cueball sits at a table, eating a meal.] Cueball: Can you pass the salt? [Cueball pauses, a bite of food on his fork, silently.] [Cueball still has fork in mid-air.] Cueball: I said- Off-screen person: I know! I'm developing a system to pass you arbitrary condiments. Cueball: It's been 20 minutes! Off-screen person: It'll save time in the long run!

In this comic, Cueball asks a friend or relative to pass him the salt, a common request when dining with others. Usually it is expected that the person will simply pass the salt immediately; however, the offscreen person doesn't get back to him until 20 minutes later, when Cueball repeats his request. The friend explains that they're attempting to solve the general problem of passing any table condiment, not just salt. This is a common mistake made in software development, wherein an developer tries to solve a problem far more general than the specific one they have been tasked to solve. Sometimes, this foresight can be useful, if the developer has predicted use cases that later turn out to be needed; other times, it can lead to wasted time, or worse, overengineering, where a system is made more complex and fragile than it needed to be, instead of robustly solving a single, well-defined problem. It isn't clear what exactly the offscreen friend is doing (or even what they could do) to solve the general condiment-passing problem; most likely they are still in the design stage of their solution and have not even started implementing it, much to Cueball's chagrin. Nonetheless they are convinced that it is worth taking the time to do this now due to the potential time-saving in the long run. In doing so, they are overlooking the more salient and saline facts of the situation; namely, that passing condiments is not something that requires a solution or takes up any significant amount of time, and that Cueball would probably prefer to have the salt while his meal is still warm. In the title text, Randall notes a social paradox: that people tend to be disparaging of such inefficient time-wasting while it's not producing any results, but will heap praise on it when they're able to reap the benefits of that foresight. See also 137: Dreams , 1205: Is It Worth the Time? , 1319: Automation , 1691: Optimization , and the Time management category . [Cueball sits at a table, eating a meal.] Cueball: Can you pass the salt? [Cueball pauses, a bite of food on his fork, silently.] [Cueball still has fork in mid-air.] Cueball: I said- Off-screen person: I know! I'm developing a system to pass you arbitrary condiments. Cueball: It's been 20 minutes! Off-screen person: It'll save time in the long run!

Occulting Telescope

Occulting Telescope

https://www.xkcd.com/975

https://www.explainxkcd.com/wiki/index.php/975:_Occulting_Telescope

[Cueball is presenting his new telescope in front of a white board, pointing to the diagram of said telescope with a pointer. He is standing on a raised podium facing a crowd off-panel] Cueball: The occulting observatory consists of two parts—the telescope and the discs. [A frame-less panel with a black center with white drawings that shows the diagram from the white board in the first panel. It shows a satellite with solar panels above and below the main body which has a front end that looks wider like a telescope. The satellite is labeled with a small arrow pointing at the front end. 11 light waves are indicated as coming towards it from the right, and below these they are labeled. Three of the waves is blocked in the middle by a small vertical line which is also labeled with a small arrow. Above and below the diagram outside the black area Cueball is narrating.] Cueball (narrating): When the telescope sees a star, a disc is carefully steered to block its light. Label: Telescope Label: Light from star Label: Disc Cueball (narrating): This procedure is repeated until all stars are covered. [Back to Cueball on the podium who now looks down on the audience from where a question emanates at the top of the left frame.] Person #1 (off screen): Wait, all? Why? Cueball: I'll feel better. [Close-up on Cueball. as two different persons talks to him, from the lower left frame.] Person #2 (off-screen): I thought the point was to image extrasolar planets. Cueball: The point is that there are too many stars. Cueball: It's been freaking me out. Person #2 (off-screen): What? Person #3 (off screen): He has a point...

Cueball takes the useful practice of occulting stars beyond its intended purpose. Occulting is used in astronomy to block the light from a star under observation so that adjacent dim objects, such as any surrounding extrasolar planets , might be more easily detected and examined. This refers to a proposed starshade mission , envisioned for space telescopes like the James Webb Space Telescope , in which a large occulter would fly in formation with that telescope. Instead of blocking the light of a single star for the purposes of observation, Cueball proposes blocking the light from all stars, for the purpose of making him feel comfortable with the night sky. Cueball feels, some might say irrationally, that "there are too many stars", and "it's been freaking me out". This may be a reference to Isaac Asimov's "Nightfall" which explores in depth the psychological implications by which stars make some people feel small and insignificant because they demonstrate just how vast is the universe. The title text refers to both a Type II Kardashev civilization and a Dyson sphere . A Dyson sphere is a theoretical construction consisting of a network of satellites that orbit and completely surround a star. The purpose of a Dyson Sphere is to capture and transmit all of the available solar energy in the star back to a planet. A Type II Kardashev civilization is a theoretical civilization that has advanced to the point where it has harnessed the energy radiated by its own star (for example, the stage of successful construction of a Dyson sphere). For comparison purposes: The title text reveals that Type II Kardashev civilizations construct Dyson spheres not for the purposes of capturing all solar energy, but merely to block the view of all that hideous space. This may allude to Douglas Adam's Hitchhiker's Guide to the Galaxy novel series, where a planet called Krikkit is completely obscured by a dust layer. Upon building a spacecraft to explore what lies behind that dust cover, they decide to destroy all living beings in the rest of the universe. See http://hitchhikers.wikia.com/wiki/Krikkit . The concept of an occulting space telescope was visited again in 1730: Starshade , and the idea of the vastness of space being frightening was revisited in 2596: Galaxies . [Cueball is presenting his new telescope in front of a white board, pointing to the diagram of said telescope with a pointer. He is standing on a raised podium facing a crowd off-panel] Cueball: The occulting observatory consists of two parts—the telescope and the discs. [A frame-less panel with a black center with white drawings that shows the diagram from the white board in the first panel. It shows a satellite with solar panels above and below the main body which has a front end that looks wider like a telescope. The satellite is labeled with a small arrow pointing at the front end. 11 light waves are indicated as coming towards it from the right, and below these they are labeled. Three of the waves is blocked in the middle by a small vertical line which is also labeled with a small arrow. Above and below the diagram outside the black area Cueball is narrating.] Cueball (narrating): When the telescope sees a star, a disc is carefully steered to block its light. Label: Telescope Label: Light from star Label: Disc Cueball (narrating): This procedure is repeated until all stars are covered. [Back to Cueball on the podium who now looks down on the audience from where a question emanates at the top of the left frame.] Person #1 (off screen): Wait, all? Why? Cueball: I'll feel better. [Close-up on Cueball. as two different persons talks to him, from the lower left frame.] Person #2 (off-screen): I thought the point was to image extrasolar planets. Cueball: The point is that there are too many stars. Cueball: It's been freaking me out. Person #2 (off-screen): What? Person #3 (off screen): He has a point...

Sail

Sail

https://www.xkcd.com/976

https://www.explainxkcd.com/wiki/index.php/976:_Sail

[Someone is sailing a lateen rigged sailboat.] [The wind picks up, pushing the sail forward.] [The wind builds strength, and the sailor has to stand up to hold on to the main sheet.] [The sail balloons out, strangely distorted, and he can barely hold on to the sheet.] [Finally, part of the sail separates into a bubble, and the sailor almost falls over backwards. The sail begins to return to its normal shape.] [The sailor sits down and scratches his head in confusion as the bubble floats away.]

A billowing sail sometimes looks like the first stage of blowing a bubble. The main character is clearly surprised when a bubble is actually formed by the filled sail. Readers infer from the title text that the water is also part of this fantastical scenario. If the boat was overturned ( capsized ) in a soap lagoon, a film would form between the mast and the boom (horizontal bar that adjusts the sail). The film would become like the sail in the comic, filling with air and forming bubbles until the film is used up. [Someone is sailing a lateen rigged sailboat.] [The wind picks up, pushing the sail forward.] [The wind builds strength, and the sailor has to stand up to hold on to the main sheet.] [The sail balloons out, strangely distorted, and he can barely hold on to the sheet.] [Finally, part of the sail separates into a bubble, and the sailor almost falls over backwards. The sail begins to return to its normal shape.] [The sailor sits down and scratches his head in confusion as the bubble floats away.]

Map Projections

Map Projections

https://www.xkcd.com/977

https://www.explainxkcd.com/wiki/index.php/977:_Map_Projections

What your favorite Map Projection says about you [All of these are organized as Title, a copy of the particular projection underneath, and what it says about you under that.] Mercator You're not really into maps. Van der Grinten You're not a complicated person. You love the Mercator projection; you just wish it weren't square. The Earth's not a square, it's a circle. You like circles. Today is gonna be a good day! Robinson You have a comfortable pair of running shoes that you wear everywhere. You like coffee and enjoy The Beatles. You think the Robinson is the best-looking projection, hands down. Dymaxion You like Isaac Asimov, XML, and shoes with toes. You think the Segway got a bad rap. You own 3D goggles, which you use to view rotating models of better 3D goggles. You type in Dvorak. Winkel-Tripel National Geographic adopted the Winkel-Tripel in 1998, but you've been a W-T fan since long before "Nat Geo" showed up. You're worried it's getting played out, and are thinking of switching to the Kavrayskiy. You once left a party in disgust when a guest showed up wearing shoes with toes. Your favorite musical genre is "Post–". Goode Homolosine They say mapping the Earth on a 2D surface is like flattening an orange peel, which seems enough to you. You like easy solutions.You think we wouldn't have so many problems if we'd just elect normal people to Congress instead of Politicians. You think airlines should just buy food from the restaurants near the gates and serve that on board. You change your car's oil, but secretly wonder if you really need to. Hobo-Dyer You want to avoid cultural imperialism, but you've heard bad things about Gall-Peters. You're conflict-averse and buy organic. You use a recently-invented set of gender-neutral pronouns and think that what the world needs is a revolution in consciousness. Plate Carrée (Equirectangular) You think this one is fine. You like how X and Y map to latitude and longitude. The other projections overcomplicate things. You want me to stop asking about maps so you can enjoy dinner. A Globe! Yes, you're very clever. Waterman Butterfly Really? You know the Waterman? Have you seen the 1909 Cahill Map it's based— ...You have a framed reproduction at home?! Whoa. ...Listen, forget these questions. Are you doing anything tonight? Peirce Quincuncial You think that when we look at a map, what we really see is ourselves. After you first saw Inception , you sat silent in the theater for six hours. It freaks you out to realize that everyone around you has a skeleton inside them. You have really looked at your hands. Gall-Peters I hate you.

Map projection , or how to represent the spherical Earth surface onto a flat support (paper, screen...) to have a usable map, is a long-time issue with very practical aspects (navigation, geographical shapes and masses visualization, etc.) as well as very scientific/mathematical ones, involving geometry or even abstract algebra among other things. There is no universal solution to this problem: Any 2D map projection will always distort in a way the spherical reality. Many projections have been proposed in various contexts, each intending to minimize distortions for specific uses (for nautical navigation, for aerial navigation, for landmass size comparisons, etc.) but having drawbacks from other points of view. Some of them are more frequently used than others in mass media and therefore more well-known than others, some are purely historical and now deprecated, some are very obscure, etc. Randall suggests here the idea that someone's "favorite" map projection can reveal aspects of their personality, then goes through a series of them to show what they can mean. He may actually believe that all map projections are in a way bad. This could be inferred from the fact that he much later began publishing a series of Bad Map Projections . The Mercator projection was introduced by Flemish cartographer Gerardus Mercator in 1569. The main purpose of this map is to preserve compass bearings; for example 13 degrees east of north will be 13 degrees clockwise from the ray pointing toward the top of the map, at every point. A mathematical consequence is the mapping is conformal, i.e. if two roads meet at a certain angle on the surface of the Earth, they will meet at that same angle on the map. It also follows that at every point the vertical and horizontal scales are the same, so locally i.e. considering only a small part of the map, geographical features (shapes, angles) are well represented, which helps a lot in recognizing them on-the-field, or for local navigation in that small part only. For this reason, that projection (or a close variant) is used in several online mapping services (such as Google Maps), which means that it is frequently encountered by the general public. A straight line on the map corresponds to a course of constant bearing (direction), which was very useful for nautical navigation in the past (and thus made that projection very well-known). However, from a global point of view, this projection is radically incorrect in how it shows the size of landmasses (for instance, Antarctica and Greenland seem gigantic), and furthermore, it always excludes a small region around each pole (otherwise the map would be of infinite height), so it doesn't provide a complete solution for the problem of map projection. The comic implies that people who like that projection aren't very interested with map issues, and typically use what they are offered without thinking much about it. The Van der Grinten projection is not much better than the Mercator. It was adopted by National Geographic in 1922 and was used until they updated to the Robinson projection in 1988. The Van der Grinten projection is circular as opposed to the Mercator projection. The fictional person believes a circular map is more fitting to the real Earth's three-dimensional spherical nature because both are round. This belief fails to recognize that a two-dimensional circle has very little in common with the surface of a sphere, and thus this projection still causes a vast distortion of space and area. Because of this, Randall implies the Van der Grinten enthusiast to be optimistic and childishly simple-minded (e.g. "you like circles"). The Robinson projection was developed by Arthur H. Robinson as a map that was supposed to look nice and is often used for classroom maps. National Geographic switched to this projection in 1988, and used it for ten years, switching to the Winkel-Tripel in 1998. The Beatles was a rock band that enjoyed great commercial success in the 1960s, and are widely considered the best act ever in the genre of popular music. The Beatles, coffee, and running shoes are all things that are very commonly enjoyed and largely uncontroversial, as well as being comforting. Liking these specific things suggests an ordinary, easygoing lifestyle paralleled by the projection. Also called the Fuller Map, the Dymaxion map takes a sphere and projects it onto an icosahedron, that is a polyhedron with 20 triangular faces. It is far easier to unwrap an icosahedron than it is to unwrap a sphere into a 2D object and has very little skewing of the poles. Buckminster Fuller was an eccentric futurist who believed, for example, that world maps should allow no conception of "up" or "down". He was therefore more than happy to defy people's expectations about maps in the pursuit of mathematical accuracy. Randall associates the projection to geek subculture and niche markets: Proposed by Oswald Winkel in 1921, the Winkel tripel projection tried to reduce a set of three (German: Tripel) main problems with map projections: area, direction, and distance. The Kavrayskiy projection is very similar to the Winkel Tripel and was used by the USSR, but very few in the Western world know of it. The comic links this projection to hipster subculture. The hipster stereotype is to avoid conforming to mainstream fashions. "Post-" refers to a variety of musical genres such as post-punk , post-grunge , post-minimalism , post-rock , etc. that branch off of other genres, and are generally considered less accessible than the genres that spawned them. Liking a genre just called "post-" implies that the listener prefers music that is less mainstream, and may have that as the only criterion for listening. Trivia The Goode homolosine projection takes a different approach to skewing a sphere into a roughly circular surface. An orange peel can be taken from an orange and flattened with fair success; this is roughly the procedure that John Paule Goode followed in creating this projection. Randall is suggesting that people who like this map also prefer relatively easy solutions to other things in life, despite those solutions having nuanced problems that are more difficult to address. People often make arguments that if normal people ran the United States, then the US wouldn't be in the trouble it is. This is from the belief that career politicians are simply out to make money and will only act in the interest of their constituency when their continued easy life is threatened (usually around election time). While some form of this view is very common and probably pretty much correct, Randall is saying that someone who likes this map may take this to extremes. Airline food is another, much maligned, problem. How do you store enough food to feed people on long airplane trips? What kind of food can be served in an enclosed, low-air-pressure environment? The common solution is to use some kind of prepackaged, reheated meal. Randall is saying that the people in favor of the Goode Homolosine wonder why the airlines don't simply order meals from the restaurants in the airport, store that food, and serve it, rather than using bland reheated food. However, this seemingly-obvious solution ignores how being in an airplane dulls your sense of taste. Airplane food is actually over seasoned for eating on the ground, meaning that if airlines switched to restaurant food it would probably taste even blander. There would also be issues with acquiring special meals (for example, vegetarian, Kosher, and Halal meals), especially if suitable restaurants were not in close range to the airport. Older cars burned oil like mad fiends, and oil back then would become corrosive to the innards of an engine, so oil had to be changed often. But, with the introduction of synthetic motor oil and better designed engines, new cars only need their oil changed about every 10,000 to 15,000 miles. A common conspiracy theory is that modern automobile oil manufacturers still recommend that car owners change their oil every 3,000-5,000 miles to "drum" up more business, even though that frequency is unnecessary. All of these references suggest that people who like the Goode Homolosine projection are fans of easy solutions to problems. However, the solutions would not necessarily work in practice. For instance: the restaurants might have trouble making enough food for the whole plane, and it could get cold before being served; the air conditions aboard planes can affect taste, so airlines say they optimize for this; there is no such thing as a "normal" person, and if there were, he/she would have virtually no chance at actually getting into government office and/or may not have prior political experience that would be helpful for congress; and the Goode Homolosine projection, while mostly resembling a flattened orange peel as suggested by the earlier analogy, does indeed cut down on distortion, but also has serious problems of its own, such as leaving huge gaps of nothingness between the continents, making distances across the oceans difficult to visualize. The Hobo–Dyer projection was commissioned by Bob Abramms and Howard Bronstein and was drafted by Mick Dyer in 2002. It is a modified Behrmann projection . The goal was to be a more visually pleasing version of the Gall–Peters. As is discussed in the Gall–Peters explanation, the Gall–Peters was developed to be equal area, so that economically disadvantaged areas can at least take comfort in the fact that their country is represented correctly by area on maps. Randall associates the Hobo–Dyer projection to "crunchy granola" — a stereotype associated with vegetarianism, environmental activism, anti-war activism, liberal political leanings, and some traces of hippie culture. With feminism becoming mainstream and alternative genders being more widely accepted, some have begun to invent gender-neutral pronouns so that when referring to a person whose gender is not known they cannot be offended by being referred to by the wrong pronouns. In Middle English 'they' and 'their' were accepted genderless pronouns that could replace 'he', 'she' as well as be used to represent a crowd, but this usage is considered by some to be grammatically incorrect because of the plural/singular debate ( stupid Victorian Grammarians! ). There have been many attempts at popularizing invented gender-neutral pronouns and they are beginning to achieve some degree of success in the mainstream. Also known as the Equirectangular projection , it has apparently been in use since approximately 100 AD. The benefit of this projection is that latitude and longitude can be used as x,y coordinates. This makes it especially easy for computers to graph data on top of it. According to the comic, the projection appeals to people who find much beauty in simplicity. In any good discussion there has to be at least one smart-ass. [ citation needed ] This is a comic about map projections, that is, the science of taking a sphere and flattening it into 2 dimensions. The smart-ass believes that we shouldn't even try: a sphere is, tautologically, the perfect representation of a sphere. To quote The Princess Bride : "Yes, you're very smart. Shut up." A globe is, of course, the "map projection" used by Google Earth when zoomed out. Similar to the Dymaxion, the Waterman butterfly projection turns a sphere into an octahedron, and then unfolds the net of the octahedron, which was devised by mathematician Steve Waterman based upon the work of Bernard J.S. Cahill . Bernard Cahill published a butterfly map in 1909. Steve Waterman probably has the only extant "ready to go" map following the same general principles, though Gene Keys may not be far behind. Waterman has a poem with graphics in a similar vein to this xkcd comic that is worth reading. [1] Polyhedral projections like Cahill, Dymaxion or Waterman typically offer better accuracy of size, shape and area than flat projections, at the expense of compass directionality, connectedness, and other complications. The joke is that the person responding deeply understands map projections; anyone who knows of this projection is a person that Randall would like to get to know. The Peirce quincuncial projection was devised by Charles Sanders Peirce in 1879 and uses complex analysis to make a conformal mapping of the Earth, that conforms except for four points which would make up the midpoints of sides and lie on equator (the equator is represented by a square and the corners connect the sides in the middle.) Inception was a 2010 movie about meta lucid dreaming . It has a complex story that is difficult to follow and leaves the viewer with many questions at the end, and almost always needs to be watched multiple times to be understood. The human brain is not well developed to deal with oddly obvious things. One example is that everyone has a skeleton, but everyone is surprised to see a part of their body represented by an X-ray. Another is the fascinating complexity of the human hand, a machine which is amazingly complex, driven by a complex interplay of electrical and chemical signals; yet is the size of the hand and so useful. A fascination with or fixation on such thoughts is often associated with an altered state of mind brought on by marijuana consumption. Therefore, Randall may be implying that this map would appeal to stoners. The Gall–Peters projection is mired in controversy, surprisingly for a map. James Gall , a 19th-century clergyman, presented this projection in 1855 before the British Association for the Advancement of Science . In 1967, the filmmaker Arno Peters created the same projection and presented it to the world as a "new invention" that put poorer, less powerful countries into their rightful proportions (as opposed to the Mercator). Peters played the marketing game and got quite a few followers of his map by saying it had "absolute angle conformality," "no extreme distortions of form," and was "totally distance-factual" in an age when society was very concerned about social justice. All of these claims were in fact false. The Mercator projection distorts size in favor of shape, and Gall-Peters distorts shape in favor of size, being especially inaccurate at the equator and the poles. The implication is that the fans of this map are pompously concerned with social justice, and willing either to lie or convey marketing mistruths to promote that cause. Alternatively Randall just dislikes this map projection so much due to the above mentioned inaccuracies, that he hates anyone who likes it. The title text makes a joke that goes to the familiar meme from CSI: Miami , in which the star, David Caruso starts a sentence, then puts on his sunglasses and ends the sentence with a corny pun. In this case, the pun is on map projection and projection in psychology. Psychological projection is an unconscious defense mechanism wherein a person who is uncomfortable with their own impulses denies having them and attributes them to other people, and blames these people for these impulses. The Sunglasses internet meme has been used in other comics as well. What your favorite Map Projection says about you [All of these are organized as Title, a copy of the particular projection underneath, and what it says about you under that.] Mercator You're not really into maps. Van der Grinten You're not a complicated person. You love the Mercator projection; you just wish it weren't square. The Earth's not a square, it's a circle. You like circles. Today is gonna be a good day! Robinson You have a comfortable pair of running shoes that you wear everywhere. You like coffee and enjoy The Beatles. You think the Robinson is the best-looking projection, hands down. Dymaxion You like Isaac Asimov, XML, and shoes with toes. You think the Segway got a bad rap. You own 3D goggles, which you use to view rotating models of better 3D goggles. You type in Dvorak. Winkel-Tripel National Geographic adopted the Winkel-Tripel in 1998, but you've been a W-T fan since long before "Nat Geo" showed up. You're worried it's getting played out, and are thinking of switching to the Kavrayskiy. You once left a party in disgust when a guest showed up wearing shoes with toes. Your favorite musical genre is "Post–". Goode Homolosine They say mapping the Earth on a 2D surface is like flattening an orange peel, which seems enough to you. You like easy solutions.You think we wouldn't have so many problems if we'd just elect normal people to Congress instead of Politicians. You think airlines should just buy food from the restaurants near the gates and serve that on board. You change your car's oil, but secretly wonder if you really need to. Hobo-Dyer You want to avoid cultural imperialism, but you've heard bad things about Gall-Peters. You're conflict-averse and buy organic. You use a recently-invented set of gender-neutral pronouns and think that what the world needs is a revolution in consciousness. Plate Carrée (Equirectangular) You think this one is fine. You like how X and Y map to latitude and longitude. The other projections overcomplicate things. You want me to stop asking about maps so you can enjoy dinner. A Globe! Yes, you're very clever. Waterman Butterfly Really? You know the Waterman? Have you seen the 1909 Cahill Map it's based— ...You have a framed reproduction at home?! Whoa. ...Listen, forget these questions. Are you doing anything tonight? Peirce Quincuncial You think that when we look at a map, what we really see is ourselves. After you first saw Inception , you sat silent in the theater for six hours. It freaks you out to realize that everyone around you has a skeleton inside them. You have really looked at your hands. Gall-Peters I hate you.

Citogenesis

Citogenesis

https://www.xkcd.com/978

https://www.explainxkcd.com/wiki/index.php/978:_Citogenesis

Where Citations Come From: Citogenesis Step #1 Through a convoluted process, a user's brain generates facts. These are typed into Wikipedia. [Hairy sits at a desk, typing on a laptop.] Hairy: (typing) The "scroll lock" key was was designed by future Energy Secretary Steven Chu in a college project. Step #2 A rushed writer checks Wikipedia for a summary of their subject. [Ponytail sits at a desk, typing on a desktop.] Ponytail: (typing) US Energy Secretary Steven Chu, (Nobel Prizewinner and creator of the ubiquitous "scroll lock" key) testified before Congress today... Step #3 Surprised readers check Wikipedia, see the claim, and flag it for review. A passing editor finds the piece and adds it as a citation. [Cueball sits on a couch with a laptop in his lap, typing.] Cueball: Google is your friend, people. (typing) <ref>{{cite web|url= Step #4 Now that other writers have a real source, they repeat the fact. [A flow chart, with "Wikipedia citation" in the center. The word "Wikipedia" is in black, the word "citations" is white with a red background. [A black arrow leads from "brain" to "Wikipedia."] [A black arrow labeled "words" leads from "Wikipedia" to "careless writers," and a red arrow labeled "citations" leads back to "Wikipedia citations."] [A black & red arrow leads from "Wikipedia" to "cited facts" which leads to "slightly more careful writers," which leads to "more citations," which leads back to :"Wikipedia" (all black & red arrows).] References proliferate, completing the citogenesis process.

This comic is calling into question the reliability of Wikipedia . This is a favorite pastime of librarians, teachers, and professional researchers, and not usually one of Randall 's. Wikipedia is a free and freely editable encyclopedia that aims to become a comprehensive, neutral compilation of verifiable and established facts . Wikipedia aims to provide only facts backed by reliable sources . However, this comic strip details a process in which Wikipedia can not only spread misinformation but make said misinformation seem reliable through a process of "circular reporting". The title of the comic is a play on the word cytogenesis . Cytogenesis is the formation of cells and their development. Citogenesis , on the other hand, is a portmanteau of 'Citation' and 'Genesis'. A Citation is a reference to a source, used to back up a specific claim, and genesis means the origin of something. By extension, citogenesis is the creation of text in a reliable source that can be cited to back up a claim. In the process described here, someone adds an untrue claim to an article in Wikipedia. A writer of some supposedly "reliable source" checks Wikipedia for information, and blindly relies on it, without checking for proper sources - the comic uses rushed writers, such as those responsible for news stories, as an example of someone who may do this. Eventually, someone notices the claim in the reliable source and cites it in the Wikipedia article. The citation now gives the claim credence, as readers don't realize that the official source was based on the Wikipedia article. Thanks to this citation, other reporters, slightly more cautious than the first, consider this bit of information to be reliable and then cite it in articles of their own. Those articles then get cited in Wikipedia, making the claim seem more reliable, encouraging even more reporters to believe it and repeat the claim. Eventually, a long list of citations is available, giving an impression of consensus, even though all of it originated with a single article, which was based on an uncited Wikipedia edit. Four years before, Randall commented on Wikipedia about that process happening to him (on a minor detail), which probably indicates the inception of this comic: In turn, Randall originated the untrue assertion in this comic that Steven Chu , a physicist, and at the time of the strip the U.S. Secretary of Energy, invented the Scroll lock key, a common button on computer keyboards. Since most people are aware of the scroll lock key but know little about its function or origins, this false information would make for an interesting piece of trivia that would likely spread very quickly. Following this comic, the actual Scroll Lock and Steven Chu articles were both vandalized by "helpful" editors trying to project Randall's reality on Wikipedia. As of May 2022, the Wikipedia article on Citogenesis redirects to the " Circular reporting on Wikipedia " section on the article " Circular reporting ". The section credits the term "citogenesis" to Randall Munroe, with a citation linking to this comic. To make matters even more surreal, a Wikipedia editor once flagged the link to this xkcd comic as "Dubious - The material near this tag is possibly inaccurate or non-factual."! We haven't seen a book like the one Randall describes in the title text. But one example of the misuse of Wikipedia by "reliable sources" concerns the former German minister Karl-Theodor zu Guttenberg . His complete name contains fifteen names/words and reads: Karl-Theodor Maria Nikolaus Johann Jacob Philipp Franz Joseph Sylvester Freiherr von und zu Guttenberg. An anonymous user added one more ("Wilhelm") to the German Wikipedia, just the evening before Karl-Theodor zu Guttenberg was presented as the new Federal Minister of Economics and Technology on February 10, 2009. The next day many major German newspapers published this wrong name ( translation of bildblog.de ). Where Citations Come From: Citogenesis Step #1 Through a convoluted process, a user's brain generates facts. These are typed into Wikipedia. [Hairy sits at a desk, typing on a laptop.] Hairy: (typing) The "scroll lock" key was was designed by future Energy Secretary Steven Chu in a college project. Step #2 A rushed writer checks Wikipedia for a summary of their subject. [Ponytail sits at a desk, typing on a desktop.] Ponytail: (typing) US Energy Secretary Steven Chu, (Nobel Prizewinner and creator of the ubiquitous "scroll lock" key) testified before Congress today... Step #3 Surprised readers check Wikipedia, see the claim, and flag it for review. A passing editor finds the piece and adds it as a citation. [Cueball sits on a couch with a laptop in his lap, typing.] Cueball: Google is your friend, people. (typing) <ref>{{cite web|url= Step #4 Now that other writers have a real source, they repeat the fact. [A flow chart, with "Wikipedia citation" in the center. The word "Wikipedia" is in black, the word "citations" is white with a red background. [A black arrow leads from "brain" to "Wikipedia."] [A black arrow labeled "words" leads from "Wikipedia" to "careless writers," and a red arrow labeled "citations" leads back to "Wikipedia citations."] [A black & red arrow leads from "Wikipedia" to "cited facts" which leads to "slightly more careful writers," which leads to "more citations," which leads back to :"Wikipedia" (all black & red arrows).] References proliferate, completing the citogenesis process.

Wisdom of the Ancients

Wisdom of the Ancients

https://www.xkcd.com/979

https://www.explainxkcd.com/wiki/index.php/979:_Wisdom_of_the_Ancients

[A poem is written outside and right justified along the left edge of the panel to the right.] Never have I felt so close to another soul And yet so helplessly alone As when I Google an error And there's one result A thread by someone with the same problem And no answer Last posted to in 2003 [Cueball stands in front of his desk, having risen so the chair has moved away behind him. He is holding on to his computer's screen, looking at it while visibly shaking the screen and shouting at it.] Cueball: Who were you, DenverCoder9? Cueball: What did you see?!

This comic refers to a common experience that those trying to solve tech problems have. Typically, people search on Google to try to find solutions to the problem. Sometimes the solution can be found on a software program's website, but the most helpful solutions frequently come from discussions on message boards, particularly for more obscure problems. This is because the odds are rather high that someone else, years ago, had the same problem you're having and resolved it. However, in this comic, Cueball is unable to find any mention of the problem he's currently facing except for one forum post about it that did not include the problem's solution. This is akin to finding an FAQ with questions but no answers. The title is a satirical reference to the notion that the "ancients," i.e. from thousands of years ago, possessed knowledge that has been lost to the centuries (such as exactly how Stonehenge was built), and that artifacts from those times do not fully divulge such knowledge. The fact that the "ancient" referred to in the comic is from 2003 (only 8 years before the comic was published) is an exaggeration of the feeling that the forum poster is lost to the sands of time, but in some sense this feeling is nonetheless true, since Cueball is unlikely to be able to contact them. The title text is a suggestion to forums to be aware of the fact that people are likely going to come across such posts in the future and therefore to provide handy summaries of the most helpful conclusions of long threads for them, since combing through several false starts and failed attempts to resolve a problem can be quite tedious. Some forums do indeed follow this practice, pinning the solution or the most helpful approximation to one to the top under the original question. In 1722: Debugging the title text also mentions googling an error message, explaining what it means if you get zero results. Sort of. http://www.mirrorsoferis.com/forum/thread05232003a.html [A poem is written outside and right justified along the left edge of the panel to the right.] Never have I felt so close to another soul And yet so helplessly alone As when I Google an error And there's one result A thread by someone with the same problem And no answer Last posted to in 2003 [Cueball stands in front of his desk, having risen so the chair has moved away behind him. He is holding on to his computer's screen, looking at it while visibly shaking the screen and shouting at it.] Cueball: Who were you, DenverCoder9? Cueball: What did you see?!

Money

Money

https://www.xkcd.com/980

https://www.explainxkcd.com/wiki/index.php/980:_Money

[This transcript is only reproducing text visible on the front page comic .] [Title panel at the top left has one large heading, and then it is possible to read the first and third out of five lines (but not for instance the second line which is just the word "almost"):] Money A chart of all of it [Below this there are 5 large panels, each with a series of plots, comparing the values of various things. The only clearly visible text is the title of each panel written in white on black background at the top of each panel] [The first section covers single coffees up to the hourly salaries of CEOs. It is located below the title panel and there are a lot of green groups marked by unreadable text.] Dollars [The next section discusses values from around $1000 to $1,000,000, including a dissection of the song If I had $1000000. It is located directly below the Dollars section and has mainly orange groups (but also some green) marked by unreadable text.] Thousands [The third section focuses on $1,000,000 to $1,000,000,000, with a large section on campaign contributions of American political presidential campaigns, values of expensive works of art, and J. K. Rowling. It is located to the right of the Thousands section below the Billions section and there are a lot of gray groups (but also some orange) marked by unreadable text.] Millions [The fourth section gets into larger scale finances, profits of various sectors, costs of natural disasters, and net worths of the richest people on the planet. Also, Donald Trump. It is located to the right of the Dollars section and above both the Millions and Trillions section and has mainly yellow groups (but also some gray and red) all marked by unreadable text. There are, however, a few large headings that can be read:] Billions Education The Economic (...?) US household income Federal budget [In the last panel global financial status is described. It discusses derivatives, liquid assets, public debt by nation and GDP by continent, culminating with the total economic production of the human race to date. It is located below the Billions section to the right of the Millions section and has mainly cyan groups (but also one yellow) all marked by unreadable text.] Trillions [ For the full transcript of the huge image see 980: Money/Transcript . ]

This is a chart comic - a type of comic that Randall does from time to time. He has for instance done maps of the Internet ( twice !) and other huge visualizations like this chart Radiation with a similar structure as this chart but with Radiation as the subject. The Radiation chart is most likely the inspiration for this much more comprehensive Money chart. In the chart there are five boxes with items on different scales of monetary value. Each scale of dollar increments are different colors. One dollar increments are green - naturally, because American paper money is green. Thousands are Orange/Red. Millions are gray. Billions are yellow. Trillions are blue. This comic uses the short scale for naming large numbers (so a billion = 1000 millions = 10 9 rather than a million millions = 10 12 as in continental Europe). Because the comic is so huge and complex the explanation has been split into several parts and also individual pages: Below are five tables with explanation for some of the items. The transcript is (as is usually the case with huge comics) only given for the text that is visible on the picture shown here above. However the full transcript for all the text in the huge image has also been completed. Finally some tables with prices has been made (although they are not yet complete). In the Billions box there is a vague term called the "Economic Vortex" as well as arrows that flow between different blocks of this box. This is to show where the money goes. Where it is collected from, and where it is distributed to. Included in one frame is a small man with a red and white striped shirt, blue pants, a cane and a knit cap. He is known as Wally or Waldo (in the US) from the Where's Waldo books . To not give anything away for those who wish to search for him themselves there will be no spoiler here. But if someone needs a little help... Then by clicking this link you will be directed to the relevant section amongst the five sections where Waldo can be found. (The link will take you to that section of the full transcript page). If you still cannot find him (or give up in advance) then just search the transcript page for Wally or Waldo. The title text is a reference to the phrase "Show me the money!" which originates from the film Jerry Maguire . [This transcript is only reproducing text visible on the front page comic .] [Title panel at the top left has one large heading, and then it is possible to read the first and third out of five lines (but not for instance the second line which is just the word "almost"):] Money A chart of all of it [Below this there are 5 large panels, each with a series of plots, comparing the values of various things. The only clearly visible text is the title of each panel written in white on black background at the top of each panel] [The first section covers single coffees up to the hourly salaries of CEOs. It is located below the title panel and there are a lot of green groups marked by unreadable text.] Dollars [The next section discusses values from around $1000 to $1,000,000, including a dissection of the song If I had $1000000. It is located directly below the Dollars section and has mainly orange groups (but also some green) marked by unreadable text.] Thousands [The third section focuses on $1,000,000 to $1,000,000,000, with a large section on campaign contributions of American political presidential campaigns, values of expensive works of art, and J. K. Rowling. It is located to the right of the Thousands section below the Billions section and there are a lot of gray groups (but also some orange) marked by unreadable text.] Millions [The fourth section gets into larger scale finances, profits of various sectors, costs of natural disasters, and net worths of the richest people on the planet. Also, Donald Trump. It is located to the right of the Dollars section and above both the Millions and Trillions section and has mainly yellow groups (but also some gray and red) all marked by unreadable text. There are, however, a few large headings that can be read:] Billions Education The Economic (...?) US household income Federal budget [In the last panel global financial status is described. It discusses derivatives, liquid assets, public debt by nation and GDP by continent, culminating with the total economic production of the human race to date. It is located below the Billions section to the right of the Millions section and has mainly cyan groups (but also one yellow) all marked by unreadable text.] Trillions [ For the full transcript of the huge image see 980: Money/Transcript . ]

Porn Folder

Porn Folder

https://www.xkcd.com/981

https://www.explainxkcd.com/wiki/index.php/981:_Porn_Folder

[Cueball sits at a desk, looking at a laptop screen with one hand on his chin.] Cueball: So I thought I found your porn folder, in calendar/backup/PORN/ Friend (off screen): Don't open that! [A wider shot of the person looking at the laptop.] Cueball: But it contains a bunch more folders, filled with more folders, and then... after 20 levels, somehow I'm back at the main folder? Friend (off screen): It's, uh, well hidden. [Cueball has turned around in the chair, now with the laptop in his lap.] Cueball: I think there's no actual porn here. Cueball: You're just turned on by filesystems. Friend (off screen): It's a hardlinked directory loop - so taboo! Cueball: Now I feel dirty sharing a drive with you.

Cueball seems to have found a porn folder. However, it contains a directory loop, set up by a person off-screen. It is possible to actually do this, but it is widely regarded as a very bad idea, as it can break the system in not-so-obvious ways (mostly by causing seemingly-trivial operations to infinite loop). The implication is that the folder does not need to contain pornographic images because the folder is the porn—its violation of the taboo against looping is something the off-screen character finds erotic. link() is the Linux system call to create a hard link. In an unmodified Linux kernel, it will not allow directory hard links for this exact reason; the person who set up the porn folder apparently "forced" Linux to comply, with all of the sexual analogies that suggests. [Cueball sits at a desk, looking at a laptop screen with one hand on his chin.] Cueball: So I thought I found your porn folder, in calendar/backup/PORN/ Friend (off screen): Don't open that! [A wider shot of the person looking at the laptop.] Cueball: But it contains a bunch more folders, filled with more folders, and then... after 20 levels, somehow I'm back at the main folder? Friend (off screen): It's, uh, well hidden. [Cueball has turned around in the chair, now with the laptop in his lap.] Cueball: I think there's no actual porn here. Cueball: You're just turned on by filesystems. Friend (off screen): It's a hardlinked directory loop - so taboo! Cueball: Now I feel dirty sharing a drive with you.

Set Theory

Set Theory

https://www.xkcd.com/982

https://www.explainxkcd.com/wiki/index.php/982:_Set_Theory

[Miss Lenhart stands at a blackboard, facing away from it. She has a pointer in her hand, and written on the blackboard is some set theory math, although one of the set elements is being pointed into a guillotine.] Miss Lenhart: The axiom of choice allows you to select one element from each set in a collection Miss Lenhart: and have it executed as an example to the others. [Caption below the panel:] My math teacher was a big believer in Proof by Intimidation.

This comic is a pun on the phrase " Proof by Intimidation " which normally is a jocular term used mainly in mathematics. It refers to a style of presenting a purported mathematical proof by giving an argument loaded with jargon and appeals to obscure results, so that the audience is simply obliged to accept it, lest they have to admit to their ignorance and lack of understanding. However, in this comic, "Proof by Intimidation" is taken to mean that by intimidating the elements within a set, they will conform to the proof (or, as the title text says, they will become "well-ordered"). This is accomplished by believing that the elements can be anthropomorphized such that they feel fear. The idea of executing as an example was discussed by Sun Tzu in the ancient book The Art Of War . This interpretation of the term "Proof by Intimidation" bears great resemblance to argument from the stick , which is a fallacious form of reasoning of the form 1. If not P, I will do you harm. 2. Therefore, P. This form of fallacy has the distinction, if properly applied, of never being called out as fallacious. Ponytail, however, is threatening the proposition itself, rather than her audience, bringing a level of absurdity to the situation. The axiom of choice (which has been referenced previously in 804: Pumpkin Carving ) says that given any collection of bins, each containing at least one object, it is possible to make a selection of exactly one object from each bin. It was later referenced in the title text of 1724: Proofs , another comic about a math class with a similar theme on how teachers teach their student mathematical proofs. In the title text, the well-ordering theorem states that every set can be well-ordered. A set X is well-ordered by a strict total order if every non-empty subset of X has a least element under the ordering. This is also known as Zermelo's theorem and is equivalent to the Axiom of Choice. The woodchipper is a reference to the 1996 film Fargo , where a character uses one to dispose of a body. [Miss Lenhart stands at a blackboard, facing away from it. She has a pointer in her hand, and written on the blackboard is some set theory math, although one of the set elements is being pointed into a guillotine.] Miss Lenhart: The axiom of choice allows you to select one element from each set in a collection Miss Lenhart: and have it executed as an example to the others. [Caption below the panel:] My math teacher was a big believer in Proof by Intimidation.

Privacy

Privacy

https://www.xkcd.com/983

https://www.explainxkcd.com/wiki/index.php/983:_Privacy

Dorm: [Cueball and Megan holding hands in front of a door. Megan is attempting to turn the doorknob.] Locked Other Dorm: [Cueball and Megan holding hands inside another dorm room. The roommate is sitting at a computer wearing a headset.] Roommate: I'll be done Tuesday. Roommate in raid Library Rare Book Collection: [Cueball and Megan looking through a closed door. Inside Nelson Mandela and two university workers are talking amongst various items on display.] Occupied by tour for visiting Nelson Mandela Accelerator Tunnel: [Cueball and Megan in silhouette in front of an imposing-looking door. The door is marked "NO ENTRY" with a radioactive trefoil symbol, and has a passcode scanner beside it.] Sealed while beam is in operation Beaver Lodge: [Megan climbing on top of a dirt mound while Cueball stands on the ice beside it. A cross-section reveals a beaver inside the mound and a submerged entrance.] Frozen over for winter to keep out predators, only accessible via underwater entrance Hyperspace: [Megan reading a textbook in front of a table piled with five other textbooks. Cueball looks over Megan's shoulder.] Cueball: Are you sure ? Ruled out by current understanding of physics College Law #27: The availibility [sic] of private space is inversely proportional to the desirability of the hookup.

This comic is about Cueball and Megan attempting to find some privacy to "hook up", which is slang for engaging in sexual activity. They start at a dormitory, which would offer some privacy. Unfortunately, the door is locked. They go to another dorm, but it is occupied by someone playing a MMORPG who is "in a raid ", which means that the gamer is teaming up with others to "raid" something, probably an enemy, and loot their items. This also pokes fun at the fact that some raids may take a very long time to execute, in this case apparently taking on the order of 24 hours. (This comic was published on a Monday morning.) In the third frame, the two try to go to the library's rare book collection. Such a place would usually be deserted, making it usable for sexual activity. However, it is currently occupied by a visiting Nelson Mandela , who is on a tour of the school. Moving on to more bizarre places, they next try an accelerator tunnel , another place that would be private. However, the particle accelerator is in use and the door is sealed tight. This would be a normal safety feature to protect researchers from being exposed to potentially dangerous ionizing radiation from the particle beam. The couple then try a beaver lodge , which, despite being private, is too tiny to fit in, and the only entrance is underwater. What makes it more difficult to get in is that it is winter, and the ground is presumably frozen solid. The last place they attempt to go to is hyperspace , science fiction jargon for an ‘alternate dimension’ that starships supposedly use to travel faster than light. The word is frequently used in the Star Wars movies. However, there is no evidence that anything like hyperspace exists in reality, and in fact current theories of physics do not allow it. The caption is a parody of other laws of physics, such as "brightness is inversely proportional to distance from the source". The title text indicates that the two eventually found privacy for sex in a laboratory, but inadvertently got Megan pregnant. This is a parody of news articles discussing whether scientists can create synthetic life in a lab. This eventual headline appears in a few 1037: Umwelt frames as "Scientists Create Life In Lab", with a similar secondary headline/caption as the punchline. The comic 658: Orbitals is similar in nature to this comic. Dorm: [Cueball and Megan holding hands in front of a door. Megan is attempting to turn the doorknob.] Locked Other Dorm: [Cueball and Megan holding hands inside another dorm room. The roommate is sitting at a computer wearing a headset.] Roommate: I'll be done Tuesday. Roommate in raid Library Rare Book Collection: [Cueball and Megan looking through a closed door. Inside Nelson Mandela and two university workers are talking amongst various items on display.] Occupied by tour for visiting Nelson Mandela Accelerator Tunnel: [Cueball and Megan in silhouette in front of an imposing-looking door. The door is marked "NO ENTRY" with a radioactive trefoil symbol, and has a passcode scanner beside it.] Sealed while beam is in operation Beaver Lodge: [Megan climbing on top of a dirt mound while Cueball stands on the ice beside it. A cross-section reveals a beaver inside the mound and a submerged entrance.] Frozen over for winter to keep out predators, only accessible via underwater entrance Hyperspace: [Megan reading a textbook in front of a table piled with five other textbooks. Cueball looks over Megan's shoulder.] Cueball: Are you sure ? Ruled out by current understanding of physics College Law #27: The availibility [sic] of private space is inversely proportional to the desirability of the hookup.

Space Launch System

Space Launch System

https://www.xkcd.com/984

https://www.explainxkcd.com/wiki/index.php/984:_Space_Launch_System

[Cueball, is holding something up to show it to Black Hat. It is small and rectangular with a black line in the middle (possible a rocket).] Cueball: Check out the SLS — 130 tons to orbit. Finally, rockets that improve on the ones we had 40 years ago. Black Hat: Are we getting Nazis to build those ones, too? [Text is written between two frames, with two smaller frames below. A line comes up to Cueballs first comment, showing that it is still the two from the first frame talking, but off-panel.] Cueball (off-panel): What? Black Hat (off-panel): When we first captured von Braun and his team, we had our engineers interview them, then we built the rockets. Black Hat (off-panel): But our rockets kept exploding. [First small panel below the above text: A soldier with helmet and a machine gun is guarding von Braun who is tied to a chair, while being interviewed by an almost bald scientist (hair along the back of his head), who takes notes on a piece of paper.] [Second small panel below the above text: The same scientist standing with the paper, watches as a launching rocket explodes. The landscape behind shows a hill.] [A black frame with white text above the white Saturn V rocket flying through space.] Black Hat (off-panel): Eventually we gave up and had the German teams do it, and they built us the Saturn V Moon rocket. [Cueball is looking down, his hand with the thing he showed to Black Hat in the first panel hanging down. Black Hat looks at Cueball.] Cueball: I'm… not sure what lesson to take from that. Black Hat: "If you want something done right, learning from the Nazis isn't enough. You have to actually put them in charge." Cueball: That's a terrible lesson. Black Hat: Then I guess you should get a Nazi to come up with a better one.

SLS, which stands for Space Launch System , is the new launch program being designed by NASA to replace the retired Space Shuttle launch system. In the first frame, Cueball is showing Black Hat something about the SLS, possibly a video on his phone or other portable electronic device. As usual with his appearances, Black Hat is causing trouble. Specifically he asks if Nazi scientists are going to build NASA's new SLS program. Specifically he mentions the former Nazi party member Wernher von Braun , who was one of the developers of the Saturn V launch vehicle, who came over to America (from Germany ) as part of Operation Paperclip and helped develop NASA's space program. The unfortunate reality of Operation Paperclip, and one that Black Hat aims to make people uncomfortable with, is that a significant number of ex-German personnel were Nazi party true-believers, and their defection to America effectively granted them amnesty of any war crimes. Black Hat extrapolates this sad reality into an obvious troll attempt: that putting actual Nazis in charge will get you results. This assumption is obviously a bridge too far (which is the comic's punchline), but he gets his desired reaction out of Cueball, who is hanging his head (or staring him down- Randall has left no details to distinguish). First he makes it clear that the lesson is that you should put the Nazis in charge (and we saw from World War Two what that could lead to). Then when Cueball states this is a terrible lesson, Black Hat puts salt in his wound by suggesting that the only way to find a better lesson is to ask a Nazi for a better one - a consistent move if you apply his lesson, but a logic bomb because he suggests to put a Nazi in charge of finding another lesson other than "put a Nazi in charge". The title text is a reference to Shania Twain 's song " That Don't Impress Me Much ". Twain's lyrics include the line "Okay, so you're a rocket scientist / That don't impress me much". But, the title text argues that if she stood under the new SLS prototype, she would admit it was in fact, impressive. And it is thus the SLS head engineer (Garry Lyles) plans to invite Shania to do just that. Although he could still understand if she did not wish to date him, he would be surprised if she was still unimpressed. [Cueball, is holding something up to show it to Black Hat. It is small and rectangular with a black line in the middle (possible a rocket).] Cueball: Check out the SLS — 130 tons to orbit. Finally, rockets that improve on the ones we had 40 years ago. Black Hat: Are we getting Nazis to build those ones, too? [Text is written between two frames, with two smaller frames below. A line comes up to Cueballs first comment, showing that it is still the two from the first frame talking, but off-panel.] Cueball (off-panel): What? Black Hat (off-panel): When we first captured von Braun and his team, we had our engineers interview them, then we built the rockets. Black Hat (off-panel): But our rockets kept exploding. [First small panel below the above text: A soldier with helmet and a machine gun is guarding von Braun who is tied to a chair, while being interviewed by an almost bald scientist (hair along the back of his head), who takes notes on a piece of paper.] [Second small panel below the above text: The same scientist standing with the paper, watches as a launching rocket explodes. The landscape behind shows a hill.] [A black frame with white text above the white Saturn V rocket flying through space.] Black Hat (off-panel): Eventually we gave up and had the German teams do it, and they built us the Saturn V Moon rocket. [Cueball is looking down, his hand with the thing he showed to Black Hat in the first panel hanging down. Black Hat looks at Cueball.] Cueball: I'm… not sure what lesson to take from that. Black Hat: "If you want something done right, learning from the Nazis isn't enough. You have to actually put them in charge." Cueball: That's a terrible lesson. Black Hat: Then I guess you should get a Nazi to come up with a better one.

Percentage Points

Percentage Points

https://www.xkcd.com/985

https://www.explainxkcd.com/wiki/index.php/985:_Percentage_Points

[Cueball is sitting in an armchair watching TV while listening to a news report coming from the TV as shown by a zigzag line.] Voice from TV: Senator Grayton's campaign has imploded following the candidate's promise to give tax breaks to drunk drivers and to authorize the use of unmanned Predator drones in the War On Christmas. Grayton had been polling at 20%, but his support has since plunged by 19%. [Caption below the panel:] I hate the ambiguity created when people don't distinguish between percentages and percentage points.

Senator Grayton is a fictional character, made up for this comic; which is unusual for xkcd, as it typically uses real-world references. The issues that Grayton supports: The term percentage point is used to overcome an ambiguity when comparing two percentages. Reduction of a stated number by a percentage When the original value is given as a number, there is no ambiguity. In the statement below the only possible conclusion is that now only 162,000 people approve of Grayton. Previously 200,000 people approved of Senator Grayton, and then his approval rating dropped by 19%. Reduction of a percentage by a percentage When the original approval rating is given as a percentage (20% in the comic), then a reduction of 19% has two possible meanings: 1) Of the 20% who previously approved (200,000 people), 19% no longer approve. In this case the result is 162,000 as in the above example. 2) Compared to the original results, 19% fewer of the entire original sample of 1 million people approve. In this case only 1% of the original 1 million approve, equal to 10,000 people. If using the second method of comparing percentages, the approvals rating should be described as having dropped by 19 percentage points. In reality, the distinction between the two methods is often overlooked, leading to confusion. The caption's issue with "percentage" versus "percentage points" is that if Grayton's 20% approval rating drops by 19%, that means that his support has only dropped 3.8 percentage points since 19% of 20% is only 3.8%. That would mean that even after all his outrageous statements, his support dropped only from 20% to 16.2%. However, if the news reports that his 20% approval rating dropped 19 percentage points , that means his support has dropped to 1%, which appears to be more accurate given Grayton's egregious policy decisions and the description of his campaign as having "imploded." The punchline to all this is that Randall is more bothered by the "percent" ambiguity than by Grayton's appalling policy plans. References in the title text: [Cueball is sitting in an armchair watching TV while listening to a news report coming from the TV as shown by a zigzag line.] Voice from TV: Senator Grayton's campaign has imploded following the candidate's promise to give tax breaks to drunk drivers and to authorize the use of unmanned Predator drones in the War On Christmas. Grayton had been polling at 20%, but his support has since plunged by 19%. [Caption below the panel:] I hate the ambiguity created when people don't distinguish between percentages and percentage points.

Drinking Fountains

Drinking Fountains

https://www.xkcd.com/986

https://www.explainxkcd.com/wiki/index.php/986:_Drinking_Fountains

[Cueball leaving a public bathroom. A water fountain is next to the bathroom door. An arrow points to the next panel.] [Cueball drinking from the water fountain. An arrow points to the next panel.] [Cueball reenters the bathroom. An arrow points back to the first panel.] I avoid drinking fountains outside bathrooms because I'm afraid of getting trapped in a loop.

Here, we see Cueball using the restroom; as the title text indicates, he is eliminating the liquid waste from his body, or peeing. Some people feel a brief compulsion to urinate after drinking, even if they don't actually need to. Cueball says that he avoids the use of the drinking fountain right after peeing, because he is apparently one of these people and he is afraid that he will be forced into immediately peeing again. And as in the image above, he would be stuck in a loop. A loop is a computer science term, but also used elsewhere, to indicates going through the same steps over and over again. In this case, the bathroom and drinking fountain form an infinite loop, which, when used about computers, refers to a loop which never ends, [ citation needed ] eventually crashing (or hanging, which might actually be worse) the computer, which is therefore a situation to be avoided at all costs. The title text says Cueball/ Randall would be embarrassed in trying to explain his experiment to someone, as an experiment of this nature seems interesting to geeks but gross to non geeks (and to geeks too, if we're being honest), and he wouldn't be able to lie about what he was doing if called by someone. A thread on yahoo answers [1] with a (purported) Biology major concluded that drinking from a hose and peeing at the same time would not work: the kidneys can only process so much pee at a time, and the majority of it is re-used. But since the experiment doesn't put a lower boundary on the flow that would be regarded as an ongoing pee, this objection is invalid. Constantly sipping and dripping might be possible. [Cueball leaving a public bathroom. A water fountain is next to the bathroom door. An arrow points to the next panel.] [Cueball drinking from the water fountain. An arrow points to the next panel.] [Cueball reenters the bathroom. An arrow points back to the first panel.] I avoid drinking fountains outside bathrooms because I'm afraid of getting trapped in a loop.

Potential

Potential

https://www.xkcd.com/987

https://www.explainxkcd.com/wiki/index.php/987:_Potential

Narrator: When teachers complain, "You're not working at your full potential!" [Explosion in background.] Narrator: Don't take it too hard. [Car casually spirals through the air while a crash is heard in the background.] Narrator: They complain way more when you do. [A mechanized, 6-tentacled robot rampages around, picking up cars and creating a small warzone before the student inside while the lamentations of people and the building of military forces are in the background.] Throughout the third frame: AAAAAAAAAAAAAAAAAAAAAAAAAAA! In the control center of the robot: Click, beep, whirr Out-of-frame: It's headed this way! Ponytail: Somebody stop him!

This comic jokes about the common rant by teachers when they are annoyed by lazy or ignorant kids. They commonly say that the kids are not working up to their "full potential" and they need to work harder. The comic comforts the kids who were subject to this — by telling the students if they did reach their full potential, they could, instead of providing better essays and science fair projects, possibly create a monster robot with 6 mechanical legs apparently able to pick up and throw cars, and use machine-guns and force-fields. This is definitely not what they wanted when they said to work to your full potential. [ citation needed ] Note that such a huge and complex machine is usually seen in sci-fi books or movies. Generally, it is the main antagonist that creates them. The title text describes a parallel to the example in the strip, using philosophy rather than engineering. Randall expresses frustration when his teaching gives underprivileged kids the intellectual skills needed to raise existential questions that bug him. His extremely destructive solution is to turn the students onto drugs and crime, where they won't have time or peace of mind to think about philosophy. Narrator: When teachers complain, "You're not working at your full potential!" [Explosion in background.] Narrator: Don't take it too hard. [Car casually spirals through the air while a crash is heard in the background.] Narrator: They complain way more when you do. [A mechanized, 6-tentacled robot rampages around, picking up cars and creating a small warzone before the student inside while the lamentations of people and the building of military forces are in the background.] Throughout the third frame: AAAAAAAAAAAAAAAAAAAAAAAAAAA! In the control center of the robot: Click, beep, whirr Out-of-frame: It's headed this way! Ponytail: Somebody stop him!

Tradition

Tradition

https://www.xkcd.com/988

https://www.explainxkcd.com/wiki/index.php/988:_Tradition

The 20 most-played Christmas songs (2000-2009 radio airplay) by decade of popular release [A bar chart labeled on the X-axis with the decades "1900s" through "2000s" labeled. Each bar has, as one unit, a labeled song. "1900s", "1910s", "1920s", "1980s", "1990s", and "2000s" are empty. "1930s" has "Santa Claus is Coming to Town". "1940s" has "Rudolph the Red-Nosed Reindeer", "Winter Wonderland", "Chestnuts Roasting on an Open Fire", "Let it Snow", "Have Yourself a Merry Little Christmas", "I'll be Home for Christmas", and "White Christmas". "1950s" has "Rockin' Around the Christmas Tree", "Jingle Bell Rock", "Blue Christmas", "Little Drummer Boy", "I Saw Mommy Kissing Santa Claus", "Silver Bells", "It's Beginning to Look a Lot Like Christmas", "Sleigh Ride", and "Frosty the Snowman" "1960s" has "Holly Jolly Christmas" and "It's the Most Wonderful Time of the Year" "1970s" has "Feliz Navidad"] Every year, American culture embarks on a massive project to carefully recreate the Christmases of Baby Boomers' childhoods.

This comic uses the source of the American Society of Composers, Authors and Publishers to say that the 20 most played Christmas songs in the US between 2000 and 2009 were all released between the 1930s and 1970s. It conspicuously excludes a number of more modern songs that seem ubiquitous, but this is because those songs do not appear on the ASCAP list. "Popular release" in this context means release to the general public, not the version of the song which is most popular. The Baby Boomers were born in a period of time after the second World War after the troops came home and, thankful for their lives, went on to produce lots of children. The data appears to come from an ASCAP survey conducted in 2009 . The title text points out that many "traditions" actually have no historical precedent, they're just routines that have been spread by lots of people. The Baby Boomers, since they made up a huge fraction of the US population, were able to accidentally ground many "traditions" that their parents made up in American society just by consensus among themselves. The 20 most-played Christmas songs (2000-2009 radio airplay) by decade of popular release [A bar chart labeled on the X-axis with the decades "1900s" through "2000s" labeled. Each bar has, as one unit, a labeled song. "1900s", "1910s", "1920s", "1980s", "1990s", and "2000s" are empty. "1930s" has "Santa Claus is Coming to Town". "1940s" has "Rudolph the Red-Nosed Reindeer", "Winter Wonderland", "Chestnuts Roasting on an Open Fire", "Let it Snow", "Have Yourself a Merry Little Christmas", "I'll be Home for Christmas", and "White Christmas". "1950s" has "Rockin' Around the Christmas Tree", "Jingle Bell Rock", "Blue Christmas", "Little Drummer Boy", "I Saw Mommy Kissing Santa Claus", "Silver Bells", "It's Beginning to Look a Lot Like Christmas", "Sleigh Ride", and "Frosty the Snowman" "1960s" has "Holly Jolly Christmas" and "It's the Most Wonderful Time of the Year" "1970s" has "Feliz Navidad"] Every year, American culture embarks on a massive project to carefully recreate the Christmases of Baby Boomers' childhoods.

Cryogenics

Cryogenics

https://www.xkcd.com/989

https://www.explainxkcd.com/wiki/index.php/989:_Cryogenics

[Megan staring down at a smartphone in her hand while talking to White Hat.] Megan: Everyone's carrying sensor-packed, always-connected computers everywhere. That wasn't true ten years ago. White Hat: It's all changing too fast, huh? Megan: No, too slowly. [Zoom in on Megan's upper part as she holds up the smartphone showing its screen.] Megan: There's so much potential here. These clumsy, poorly-designed toys are nothing compared to what lies ahead. [Megan climbs into a cryogenic chamber which stands on a base where a small box at the end of the chamber is connected to it through a bend tube. She leaves the smartphone on the floor in front of White Hat.] Megan: That's why I've worked to develop cryogenic freezing. Megan: I'm gonna skip forward 30 years and use this stuff when it's good . [Cueball is greeting Megan holding a fist up in front of him, as Megan with morning hair rises up from the open cryogenic chamber.] 30 years later... Cueball: Welcome to the future! Nothing's changed. Megan: What? Megan: Why?? [Cueball still stands in front of Megan in the chamber, but the scene has rotated revealing a row of other cryogenic chambers behind. The chamber after Megan's is still closed, but the others are open and people emerging.] Cueball: When cryogenic freezing was invented, all the engineers who were excited about the future froze themselves. So there's been no one building anything new. [The scene has rotated to look straight in on the long side of Megan's chamber, Cueball is standing to the left of the chamber. She holds the cover ready to close it again. Two voices comes from off-panel to the right.] Cueball: But they're all waking up now! Megan: Sweet! I'm gonna jump forward to see what they do! Engineer 1 (off-panel): Me too! Engineer 2 (off-panel): Wait, uh, guys?

Megan , holding a smartphone , tells White Hat that everyone now carries a computer in their pocket, and refers to how it is always on-line (connected) and is full of sensors (like orientation, vibration and GPS etc.). This is actually amazing and White Hat assumes she is overwhelmed and ask her if the development is changing too fast for her. But it turns out that Megan is actually disappointed about the pace of technology's improvement, that it goes too slowly . (Who isn't disappointed? From old sci-fi movies' predictions, we should by this point have flying cars and the flying skateboard like in Back to the Future 2 or a hyper technological future like in Blade Runner ). She tells White Hat that she has decided to cryogenically freeze herself now that she has developed cryogenics (hence the title) far enough for humans to survive such a deep freeze, and then she climbs into her homemade chamber and plans to skip 30 years ahead in time. (Actually, this should be called "cryonics", preserving humans, not "Cryogenics", which is just science at low temperatures) Cryonic freezing is the ability to freeze oneself, so that one does not age and doesn't experience the passage of time. It is common in fiction as a useful technology for long space flights or other necessary preservation (like in the book 2001 ). Also people who are terminally ill or beyond current technology to save sometimes go through companies such as the Cryonics Institute in hope that future technology can cure them. However, to Megan's chagrin, when she wakes up, she is told by Cueball ( who is not Terry !) that all the other scientists and engineers that were fascinated about the future had also frozen themselves using her technology, even building their freezing chambers in a line to either side of her chamber, so nothing had been invented while she was frozen. But as Cueball tells her in the final panel, they are all waking up now, implying that finally something new can be invented! But Megan then immediately decides to freeze herself again to see what happens next, hoping the situation 30 years later will be different. But then the guy in one of the nearby chambers gets the same idea as she did (again). However, if everyone does the same thing again, the situation will repeat itself and nothing will ever change again, as they can continue this process in 30 year steps. (Note that this is not time travel , but still related to this recurring theme in xkcd, and similar methods have been called time travel in xkcd before, like in 630: Time Travel and especially 1617: Time Capsule .) It seems, however, that the engineer in the nearest chamber, to Megan's right, spots this problem and tries to stop all the other engineers from freezing down again, as he says Wait, guys . The moral of the comic is: Don't freeze yourself, engineers and scientists! We need your help! The title text refers to tech startups, (and existing tech companies) who often use bold marketing techniques, proclaiming that they are going to "revolutionize" not only a particular product or service, but every facet of a user's life. One of the cliché phrases used in presentations is "Welcome to the future", implying that their product is the only way forwards, and all others are rendered obsolete. In the title text this cliché is turned on its head, when Randall tells about a very short lived tech startup he tried to get going. The reason for the short life of the company was that it admitted that nothing changed with its slogan: "Welcome to the future! Nothing's changed." Technology by its nature tends to evolve and improve, and thus a tech company which doesn't change will fall further and further behind their competitors, likely ending up going bust. Which was the case with Randall's (fake) tech startup. [Megan staring down at a smartphone in her hand while talking to White Hat.] Megan: Everyone's carrying sensor-packed, always-connected computers everywhere. That wasn't true ten years ago. White Hat: It's all changing too fast, huh? Megan: No, too slowly. [Zoom in on Megan's upper part as she holds up the smartphone showing its screen.] Megan: There's so much potential here. These clumsy, poorly-designed toys are nothing compared to what lies ahead. [Megan climbs into a cryogenic chamber which stands on a base where a small box at the end of the chamber is connected to it through a bend tube. She leaves the smartphone on the floor in front of White Hat.] Megan: That's why I've worked to develop cryogenic freezing. Megan: I'm gonna skip forward 30 years and use this stuff when it's good . [Cueball is greeting Megan holding a fist up in front of him, as Megan with morning hair rises up from the open cryogenic chamber.] 30 years later... Cueball: Welcome to the future! Nothing's changed. Megan: What? Megan: Why?? [Cueball still stands in front of Megan in the chamber, but the scene has rotated revealing a row of other cryogenic chambers behind. The chamber after Megan's is still closed, but the others are open and people emerging.] Cueball: When cryogenic freezing was invented, all the engineers who were excited about the future froze themselves. So there's been no one building anything new. [The scene has rotated to look straight in on the long side of Megan's chamber, Cueball is standing to the left of the chamber. She holds the cover ready to close it again. Two voices comes from off-panel to the right.] Cueball: But they're all waking up now! Megan: Sweet! I'm gonna jump forward to see what they do! Engineer 1 (off-panel): Me too! Engineer 2 (off-panel): Wait, uh, guys?

Plastic Bags

Plastic Bags

https://www.xkcd.com/990

https://www.explainxkcd.com/wiki/index.php/990:_Plastic_Bags

Fun Fact: Stores have a competition to see who can spread your items across the most plastic shopping bags. [5 items placed in a single bag; heaviest item placed at the bottom.] Bag Packer: Here you go! Shopper: Thanks! [Same items; heaviest item now placed in separate bag.] Bag Packer: Here you go! Shopper: Oh, that's easier to carry. [Heavy item is now double bagged.] Bag Packer: Here you go! Shopper: Double-bagging the big stuff makes sense... [The other 4 items are now split into 2 separate bags.] Bag Packer: Here you go! Shopper: That's a bit wasteful... [The 2 separate bags are now double bagged.] Bag Packer: Here you go! Shopper: You just put five items in six bags. [Every item is now in its own, double-bagged bag.] Bag Packer: Here you go! Shopper: OK! I give up! I'll buy a reusable bag! [Reusable bag is double-bagged.] Bag Packer: Here you go! Shopper: Augh!

This is another comic with one of Randall's fun facts . In the United States, at the time this comic was written, most grocery stores used to provide plastic bags free; as well as a "bagger," whose only job is to bag the groceries — although sometimes this function is performed by the cashier. An exception to this rule might be "extreme discount" stores, such as Aldi . Customers are rarely, if ever, expected to bag their own groceries, even if they bring a reusable bag. It follows that sometimes a bagger might become a bit overzealous and use too many bags for too few products. This comic is mocking this tendency to go overboard, which is incredibly wasteful. The last frame takes this practice to its absurd and frustrating end, showing a reusable bag that has been double bagged with plastic bags. Exactly why bags are provided is probably a topic best left to academic discussion, but suffice to say that it is the state of the industry in the U.S. Perhaps grocery chains are concerned that if they did not provide free plastic bags, customers would defect, instead, to a competitor. Most shoppers view plastic bags and bagging by the store as givens. Relatively recently, some U.S. jurisdictions have begun to join more and more governments world-wide to either ban plastic bags, charge customers for them, or generate taxes on each sold bag. Using Washington, DC ( Randall 's home turf) example, as of 2010 customers are charged a $0.05 tax (again, by the local government and NOT by the grocery store) for each plastic bag, and receive an equivalent rebate for each reusable bag. While today it is accepted as a fact of life, the tax angered many at its adoption, even spurring some to claim that they would do their shopping in the next state over (in this case, Virginia), driving 5 or 10 miles to save 5 or 10 cents (this would address the theme of wasting money to save a trivial amount, addressed by Randall in 951: Working ). The tax has since become accepted as a fact of life, and has been quite successful at its initial goal of reducing the amount of bags discarded in area rivers and streams. The title text refers to the idea that while many attempt to make the environmentally-conscious decision to bag their groceries with reusable bags, thereby keeping plastic bags out of landfills, sometimes they forget to bring their bags with them from the car, or even leave the bags at home altogether. Randall is commenting on the sense of euphoria he derives from a relatively simple task: remembering to bring the reusable bags to the grocery store and taking them into the store, rather than the good feeling from helping clean up the environment. Fun Fact: Stores have a competition to see who can spread your items across the most plastic shopping bags. [5 items placed in a single bag; heaviest item placed at the bottom.] Bag Packer: Here you go! Shopper: Thanks! [Same items; heaviest item now placed in separate bag.] Bag Packer: Here you go! Shopper: Oh, that's easier to carry. [Heavy item is now double bagged.] Bag Packer: Here you go! Shopper: Double-bagging the big stuff makes sense... [The other 4 items are now split into 2 separate bags.] Bag Packer: Here you go! Shopper: That's a bit wasteful... [The 2 separate bags are now double bagged.] Bag Packer: Here you go! Shopper: You just put five items in six bags. [Every item is now in its own, double-bagged bag.] Bag Packer: Here you go! Shopper: OK! I give up! I'll buy a reusable bag! [Reusable bag is double-bagged.] Bag Packer: Here you go! Shopper: Augh!

Phantom Menace

Phantom Menace

https://www.xkcd.com/991

https://www.explainxkcd.com/wiki/index.php/991:_Phantom_Menace

[Cueball, holding a lightsaber, and another stick figure character in a Darth Maul mask stand on the sidewalk outside of a brick building in an urban area. Each is holding money in his or her hand. There is a broken window on the building.] [Beat panel. They continue to stand there.] [Beat panel. They continue to stand there.] [Darth Maul turns to Cueball.] Darth Maul: Are you sure this place is a theater? Cueball: Let's give it one more month.

Cueball is waiting outside a building with an unidentified character, who is dressed as Darth Maul , a character from Star Wars: The Phantom Menace . Before its release in May 1999, The Phantom Menace was one of the most anticipated movies of all time, with fans camped in lines outside of movie theaters as much as a full month in advance of ticket sales. In this comic, Cueball and his friend are apparently still waiting to see the movie, not having realized that they are waiting outside of a building that is not a movie theater. More importantly, they have been waiting for thirteen years, which should be long enough to realize their error. Darth Maul, the source of Cueball's friend's costume, is a Sith apprentice in the film. The Sith are the group of characters in the Star Wars universe who embrace the dark side of the Force and are the enemies throughout the series. Cueball is holding a cheap replica of a lightsaber , which is the weapon used by the Jedi and the Sith. This comic seems to be poking fun at those people who are willing to wait long in advance for the release of some product or the first theatrical release of a movie. The title text expands upon this when one of the characters states that going to a theater across town may be better, but he is worried about taking the chance due to the possibility of losing their place in this line, a misplaced sense of priorities if the line goes nowhere, and they are presently the only two in it. [Cueball, holding a lightsaber, and another stick figure character in a Darth Maul mask stand on the sidewalk outside of a brick building in an urban area. Each is holding money in his or her hand. There is a broken window on the building.] [Beat panel. They continue to stand there.] [Beat panel. They continue to stand there.] [Darth Maul turns to Cueball.] Darth Maul: Are you sure this place is a theater? Cueball: Let's give it one more month.

Mnemonics

Mnemonics

https://www.xkcd.com/992

https://www.explainxkcd.com/wiki/index.php/992:_Mnemonics

XKCD Presents: Some New Science Mnemonics (Pattern goes: Subject Elements Traditional mnemonic Contents of frame New mnemonics) Order of Operations Parentheses, Exponents, Division & Multiplication, Addition & Subtraction Traditional: Please Excuse My Dear Aunt Sally [Person having a shark delivered to his laptop.] Please Email My Dad A Shark or People Expect More Drugs And Sex SI Prefixes Big: Kilo, Mega, Giga, Tera, Peta, Exa, Zetta, (Yotta) Milli, Micro, Nano, Pico, Femto, Atto, Zepto, (Yocto) Traditional: [I never learned one.] [Graph of the declining profits of the Zune.] [Karl Marx delivering a number of zeppelins to a bunch of confused proletarians.] Proletarians (off-screen): Er. What do we do with them? Karl Marx: Rise! Big: Karl Marx Gave The Proletariat Eleven Zeppelins(, Yo) Small: Microsoft Made No Profit From Anyone's Zunes(, Yo) Taxonomy Kingdom, Phylum, Class, Order, Family, Genus, Species Traditional: King Philip Came Over For Good Sex Katy Perry: I'm not sure who doubts this, really. Katy Perry Claims Orgasms Feel Good Sometimes or Kernel Panics Crash Our Family Game System. Geologic Periods (Precambrian), Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Paleogene, Neogene Traditional: [I never learned one.] [A month's set of birth control pills.] PolyCystic Ovarian Syndrome Does Cause Problems That Judicious Contraceptves [sic] Partially Negate Resistor Color Codes Black Brown, Red, Orange, Yellow, Green, Blue, Violet, Gray, White Traditional: [none I care for] [Glenn Beck holding the traditional "Nanobot Vaccine Chemtrail 9/11" sign.] "Big Brother Reptilian Overlords", yelled Glenn, "Brainwashing Via Ground water!!"; or Be Bold, Respect Others; You'll Gradually Become Versatile, Great Wikipedians! Planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune Traditional: My Very Excellent Mother Just Served Us Nachos [A pregnant Mary attempting to explain things to an incredulous Joseph with black hair and full beard] Mary's "Virgin" Explanation Made Joseph Suspect Upstairs Neighbor.

A mnemonic is a trick that makes memorization easier. To memorize a sequence of names, a common type of mnemonic uses the beginning letters of the names in the sequence and invents another phrase using different words that start with the same letters. For example, the order of operations goes P arentheses, E xponentiation, M ultiplication and D ivision, A ddition and S ubtraction, and the traditional mnemonic goes P lease E xcuse M y D ear A unt S ally, or in Britain: B rackets, I ndices, M ultiplication, D ivision, A ddition and S ubtraction: there is no mnemonic, just the word "BIMDAS" to remember. To make them more memorable, mnemonics are usually quite silly and often vulgar. In this comic, Randall invents various scientific mnemonics, some of them as suggested replacements for traditional ones. The category is listed at the top of the box, the members are listed below that. Then there is the traditional mnemonic that children are usually taught in school to help them remember. Below the comic is one or two options for new mnemonics suggested by Randall. The top one is illustrated in the frame. XKCD Presents: Some New Science Mnemonics (Pattern goes: Subject Elements Traditional mnemonic Contents of frame New mnemonics) Order of Operations Parentheses, Exponents, Division & Multiplication, Addition & Subtraction Traditional: Please Excuse My Dear Aunt Sally [Person having a shark delivered to his laptop.] Please Email My Dad A Shark or People Expect More Drugs And Sex SI Prefixes Big: Kilo, Mega, Giga, Tera, Peta, Exa, Zetta, (Yotta) Milli, Micro, Nano, Pico, Femto, Atto, Zepto, (Yocto) Traditional: [I never learned one.] [Graph of the declining profits of the Zune.] [Karl Marx delivering a number of zeppelins to a bunch of confused proletarians.] Proletarians (off-screen): Er. What do we do with them? Karl Marx: Rise! Big: Karl Marx Gave The Proletariat Eleven Zeppelins(, Yo) Small: Microsoft Made No Profit From Anyone's Zunes(, Yo) Taxonomy Kingdom, Phylum, Class, Order, Family, Genus, Species Traditional: King Philip Came Over For Good Sex Katy Perry: I'm not sure who doubts this, really. Katy Perry Claims Orgasms Feel Good Sometimes or Kernel Panics Crash Our Family Game System. Geologic Periods (Precambrian), Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Paleogene, Neogene Traditional: [I never learned one.] [A month's set of birth control pills.] PolyCystic Ovarian Syndrome Does Cause Problems That Judicious Contraceptves [sic] Partially Negate Resistor Color Codes Black Brown, Red, Orange, Yellow, Green, Blue, Violet, Gray, White Traditional: [none I care for] [Glenn Beck holding the traditional "Nanobot Vaccine Chemtrail 9/11" sign.] "Big Brother Reptilian Overlords", yelled Glenn, "Brainwashing Via Ground water!!"; or Be Bold, Respect Others; You'll Gradually Become Versatile, Great Wikipedians! Planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune Traditional: My Very Excellent Mother Just Served Us Nachos [A pregnant Mary attempting to explain things to an incredulous Joseph with black hair and full beard] Mary's "Virgin" Explanation Made Joseph Suspect Upstairs Neighbor.

Brand Identity

Brand Identity

https://www.xkcd.com/993

https://www.explainxkcd.com/wiki/index.php/993:_Brand_Identity

[The incredibly varied shelf of a supermarket aisle. There are many different types of products on this shelf. Each type has numerous different brands, all surrounding a very plain brand that has, as its only label, the type of product. A plain bag, labeled in plain black letters, says "Potato Chips" and is surrounded by all the other various brands of potato chips. The same exists for tissues, crackers, matches, peanuts, hot sauce, sugar, milk, pasta, coffee, black beans, lima beans, mayo, ketchup, tea, and bread. There is a stark contrast between the incredibly noisy and complex labeling of every other brand and this simple one.] [Caption below:] If I ever sold a line of supermarket goods, this is how I'd build a brand identity overnight.

This comic presents Randall 's idea for a line of food products all with clear black font on a white background. The products with black block lettering and white background stand out from the other items in this comic. The irony is that even though the branding isn't terribly creative, the lack of complexity is what causes the products to stand out. These product packaging styles resemble no-frills products and generic brands . For example, in Canada, the " No Name " generic brand of low-cost products sold by Loblaws general features a plain yellow label with the description of the product in bold black text, and occasionally an image of the product. The brand name is minimalized as are other legally-required elements (e.g. the weight of the product). Another of Loblaws' generic brands, President's Choice (PC) currently has a plain white background with black bold text for the labels on most of its products (usually with an image of the product as well as the brand name), although more recently, text in accent colours has been introduced. The style of packaging might be a reference to The Prisoner TV series from the '60s, a dystopia set in a village (actually, "the village") locked out from the outside world. The shops here only sell "village food". See this photo for an example. It might also be a reference to Portal’s bean cans. In the title text, the lack of a listed URL relates to the lack of branding on the package. It is possible that omitting the URL the consumer's curiosity will be aroused, and they will spend time on the internet hunting for the actual site. [The incredibly varied shelf of a supermarket aisle. There are many different types of products on this shelf. Each type has numerous different brands, all surrounding a very plain brand that has, as its only label, the type of product. A plain bag, labeled in plain black letters, says "Potato Chips" and is surrounded by all the other various brands of potato chips. The same exists for tissues, crackers, matches, peanuts, hot sauce, sugar, milk, pasta, coffee, black beans, lima beans, mayo, ketchup, tea, and bread. There is a stark contrast between the incredibly noisy and complex labeling of every other brand and this simple one.] [Caption below:] If I ever sold a line of supermarket goods, this is how I'd build a brand identity overnight.

Advent Calendar

Advent Calendar

https://www.xkcd.com/994

https://www.explainxkcd.com/wiki/index.php/994:_Advent_Calendar

[A portion of an advent calendar shows 12 windows where the date can be seen below. The top row is cut off so you cannot see the very top of the window At the bottom there are four more windows, but only the top part can be seen, and there is no decoration visible. All the other windows have a decoration, although, you cannot see the one on the second window as it is opened more than 90 degree. The first is also opened, but not more than you can see there is a decoration. The 3rd is also open. The rest is still closed.] [A green mistletoe on red, partially open.] December 23 rd [A fully open window.] December 24 th 12:00 AM [A red and white Santa hat on green just opened.] December 24 th Noon [Two crossed red and white candy canes on white. From here all windows are closed.] December 24 th 6:00 PM [A red Christmas ball on white.] December 24 th 9:00 PM [A white Christmas star on red.] December 24 th 10:30 PM [A red Christmas heart on gren.] December 24 th 11:15 PM [A red Santa sleigh on white.] December 24 th 11:37:30 PM [A red and white Christmas sock on green.] December 24 th 11:48:45 PM [A green Christmas tree on red.] December 24 th 11:54:22.5 PM [A red and green Christmas wreath on white] December 24 th 11:57:11.25 PM [A red and white Christmas gift on green] December 24 th 11:58:35.63 PM [Below the top of four more windows where only the background colors can be seen red, white, green and then red again.] [Caption below the panel:] Zeno's Advent Calendar

An Advent calendar is a special calendar used to count or celebrate the days in anticipation of Christmas. They come in a multitude of forms, from a simple paper calendar with flaps covering each of the days, to fabric pockets on a background scene, to painted wooden boxes with cubby holes for small items. Advent calendars typically take the form of a large rectangular card with "windows", of which there are usually 24: one for each day of December leading up to and including Christmas Eve (December 24). Consecutive doors are opened every day leading up to Christmas, beginning on December 1. The calendar windows open to reveal an image, a poem, a portion of a story (such as the story of the Nativity of Jesus), or a small gift, such as a toy or a chocolate item. This comic, however, depicts an Advent calendar which has a chocolate every time they get halfway to Christmas. This is a joke because of Zeno's paradox , which said "Before a moving object can travel a certain distance, it must travel half that distance. Before it can travel half the distance it must travel 1/4 the distance, etc. This sequence goes on forever. Therefore, it seems that the original distance cannot be travelled, and motion is impossible." This means that eating chocolates at diminishing intervals will make it so Christmas never happens. The title text says that when you get close to midnight, it gets physically impossible to eat the chocolates fast enough to keep up, but you could get to the one-second-away mark with a chocolate liquefier and feeder tube. Going from the second to the last of the visible time stamps it goes like this: At 11:57:11.25 PM there is still remaining 00:02:48.75 (2 minutes 48 seconds and 75 hundredth of a second.) Half of this time period will then progress before the next windows time stamp, that is 00:01:24.375 (1 minute and 24.375 s). This will then give the next time stamp by adding to the previous and we get: 11:58:35.625 PM. This has been rounded to 35.63 s in the comic. Similarly the time stamp for the next four windows, whose top are visible below, can be calculated starting from the fact that there is now only 00:01:24.375 left of the day. It would take three more windows before crossing the 11:59:59 line with less than one second to go. At the 19th window there would only be 0.6591796875 seconds left of the day for a time-stamp of 11:59:59.3408203125. So that would be a window another line further down, even below the green window (no. 15) that is just visible at the button of the panel. And you would have to eat four chocolates in less than five seconds from window no. 16 to fulfill Randall's prediction. When reaching the 24th window there would be 0.0206 s left, so that is 6 chocolates in 0.638 s. That may be a good place to stop, but of course you could continue at least until reaching the Planck time of 5.39 x 10 -44 s. That limit will not be reached before window 162, so there are still 138 chocolates left for those last two hundredths of a second. 1153: Proof is also about Zeno, and 1577: Advent is a very different longer running Advent calendar (but with only a finite number of windows). [ citation needed ] [A portion of an advent calendar shows 12 windows where the date can be seen below. The top row is cut off so you cannot see the very top of the window At the bottom there are four more windows, but only the top part can be seen, and there is no decoration visible. All the other windows have a decoration, although, you cannot see the one on the second window as it is opened more than 90 degree. The first is also opened, but not more than you can see there is a decoration. The 3rd is also open. The rest is still closed.] [A green mistletoe on red, partially open.] December 23 rd [A fully open window.] December 24 th 12:00 AM [A red and white Santa hat on green just opened.] December 24 th Noon [Two crossed red and white candy canes on white. From here all windows are closed.] December 24 th 6:00 PM [A red Christmas ball on white.] December 24 th 9:00 PM [A white Christmas star on red.] December 24 th 10:30 PM [A red Christmas heart on gren.] December 24 th 11:15 PM [A red Santa sleigh on white.] December 24 th 11:37:30 PM [A red and white Christmas sock on green.] December 24 th 11:48:45 PM [A green Christmas tree on red.] December 24 th 11:54:22.5 PM [A red and green Christmas wreath on white] December 24 th 11:57:11.25 PM [A red and white Christmas gift on green] December 24 th 11:58:35.63 PM [Below the top of four more windows where only the background colors can be seen red, white, green and then red again.] [Caption below the panel:] Zeno's Advent Calendar

Coinstar

Coinstar

https://www.xkcd.com/995

https://www.explainxkcd.com/wiki/index.php/995:_Coinstar

[A mischievous Cueball empties a small bag into a machine.] whirrrrrrr bzzt [Machine makes progressively less happy noises.] kachunk tshhhhhhhhhh clickclickclickclick GRIND [Machine malfunctions and shuts down.] pop beeeeeeeeeeeep! [Text below frame] Holiday tip: Coinstar does not handle chocolate coins well.

This is another one of Randall's Tips , this time a Holiday Tip. Chocolate coins are a popular holiday candy, and thus this is another Christmas comic . These candies are usually plain chocolate formed in the shape of coins and covered in metallic foil wrappers. Coinstar machines accept all your loose coins, sort them, count them, and then give you the same amount of money in paper currency, around 9% less as it says in the title text. You may find similar machines in grocery stores and shopping malls around the US and Canada. These machines work by vibrating a box with a series of slots along one side, which each corresponding to the sizes of standard accepted coins. The vibrations move the coins along the different slots. If they pass through the slots the coins are then fed into a mechanism with a counterweight that's balanced to test the weight to ensure that it has captured the appropriate coin. Coins of the right size but wrong weight (such as similarly sized coins of different currencies) are dropped back out into a reject chute to be retrieved by the customer. Coins that do not fit the standard sizes also get rejected in the same way. There are also various anti-theft mechanisms that prevent coins from being counted and then retrieved. Coins that meet the programmed criteria are funneled into internal repositories and are counted towards the total. The chocolate coins in the comic appear to have damaged the machine. As the only property that the candies share with actual currency may be its appearance the machine would not be designed to handle the softer material causing the machine to malfunction and create the unusual noises presented. The chocolate may have fouled the initial vibrating tabulator; it may be that the coins are getting caught in the reject chute or are fouling the scales. In any case, the anti-theft system is being triggered, causing the machine to shut down (preventing false totals from registering) and an alarm to sound. The title text suggests that the machine would take its customary 9% from the total of the chocolate coins which is ironic since the reader knows that their candy has insignificant monetary value. [A mischievous Cueball empties a small bag into a machine.] whirrrrrrr bzzt [Machine makes progressively less happy noises.] kachunk tshhhhhhhhhh clickclickclickclick GRIND [Machine malfunctions and shuts down.] pop beeeeeeeeeeeep! [Text below frame] Holiday tip: Coinstar does not handle chocolate coins well.

Making Things Difficult

Making Things Difficult

https://www.xkcd.com/996

https://www.explainxkcd.com/wiki/index.php/996:_Making_Things_Difficult

[Ponytail in a doctor's coat is carrying a clipboard with lines indicating text, consulting it while Megan is sitting on a high medical table with a full body gown on. At the top there is a frame crossing over the top of the first panel with a caption:] Caption: Breast Cancer Surgery Follow-Up... Ponytail: You're looking great! Remove your top so I can check how the incision is healing. Megan: Nuh-uh. [Ponytail has taken her arm with the clipboard down, while Megan is holding her hand with a thumb up.] Ponytail: *Sigh* Ponytail: Do we have to do this every time? Megan: You know the rules. [In a frame-less panel showing only Ponytail, she searches for something in both her pockets, three sets of two small lines indicate how she moves her hands around inside them.] Ponytail (Mumbling to herself, in smaller text): This is so ridiculous... [Ponytail holds a purple bead necklace up in an outstretched arm. Megan begins to disrobe, opening the dress at her neck pulling with both arms as shown with three sets of two small lines.] Ponytail: Here. Megan: Woooo!

This comic is a reference to the breast cancer surgery that Randall 's fiancee/wife underwent, and is one of many comics about cancer he made because of this. This comic is the follow up appointment after the surgery. When doctor Ponytail asks Megan to take her shirt off, she refuses until Ponytail gives her a necklace of purple beads. Younger and more boorish Mardi Gras tourists sometimes offer necklaces like this in exchange for the exposure of a person's breasts. Megan's line "You know the rules" implies that Megan has stipulated that every time she takes off her shirt for the doctor, a necklace of beads must be exchanged. In the official transcript the doctor is described as an Oncologist , a doctor who works with cancer patients, and Megan/Randall's wife is described as a Delightfully Awesome Person . It is also stated that the oncologist fake-annoyedly searches for something in pockets and that it is a Mardi Gras bead necklace she takes out. Below the xkcd logo in the header at the top of the comic page there is the following text: "Some context for the cancer comics:" and below that a link to a blag posting regarding family-illness that talked about the real world events leading up to this comic. The title text refers to a mastectomy , the surgical removal of one or both breasts. One possible treatment for breast cancer is to surgically remove the breast. After this procedure a false or prosthetic breast is often added to retain the prior physical appearance. The title text suggests this prosthesis could serve as a charging station by including the following features: a spare battery inside the prosthesis, a USB port where the nipple would normally be, and a ring of lights showing the charge level of the battery arranged around the areola (the darker circle of skin around the nipple). This is one of the few comics where a character wears regular clothes, but doctor Ponytail has been seen before in 883: Pain Rating and later in 1713: 50 ccs . Megan is in both, and Cueball also in the latter. [Ponytail in a doctor's coat is carrying a clipboard with lines indicating text, consulting it while Megan is sitting on a high medical table with a full body gown on. At the top there is a frame crossing over the top of the first panel with a caption:] Caption: Breast Cancer Surgery Follow-Up... Ponytail: You're looking great! Remove your top so I can check how the incision is healing. Megan: Nuh-uh. [Ponytail has taken her arm with the clipboard down, while Megan is holding her hand with a thumb up.] Ponytail: *Sigh* Ponytail: Do we have to do this every time? Megan: You know the rules. [In a frame-less panel showing only Ponytail, she searches for something in both her pockets, three sets of two small lines indicate how she moves her hands around inside them.] Ponytail (Mumbling to herself, in smaller text): This is so ridiculous... [Ponytail holds a purple bead necklace up in an outstretched arm. Megan begins to disrobe, opening the dress at her neck pulling with both arms as shown with three sets of two small lines.] Ponytail: Here. Megan: Woooo!

Wait Wait

Wait Wait

https://www.xkcd.com/997

https://www.explainxkcd.com/wiki/index.php/997:_Wait_Wait

Headlines! Stockpiled in case Peter Sagal, host of NPR's Wait Wait Don't Tell Me , does something newsworthy in 2012. [Series of above-the-fold newspapers follows; Each has a headline, picture in most of them, and an explanation.] [First row, first paper.] Wait Wait Don't Shoot Me [A fierce Peter Sagal in a balaclava brandishes a gun in a supermarket.] NPR's Sagal in Whole Foods hostage standoff. [First row, second paper.] Wait Wait Don't Vote For Me Peter Sagal quits race for GOP top spot [A sullen and defeated Peter Sagal surrounded by supporters admits defeat.] [First row, third paper.] Wait Wait Don't Judge Me Sagal opens up about his Kermit fantasy. [Stock profile images of Peter Sagal and Kermit the Frog.] [First row, fourth paper.] Wait Wait Don't Fire Me [Stock profile image of Peter Sagal.] Peter Sagal let go after racist tirade. [Second row, first paper.] Wait Wait Don't Cancel Me NPR axing news quiz. [NPR spokesperson delivering announcement.] [Second row, second paper.] Wait Wait Don't Interrupt Me Sagal stabs Carl Kasell in on-air dispute. [Peter Sagal mid-attack with a knife.] [Second row, third paper.] Wait Wait Don't Look At Me [Peter Sagal with a skin condition.] Peter Sagal's Poison Ivy Ordeal Peter Sagal: "My 'Nam" [Second row, fourth paper.] Wait Wait Don't Friend Me Peter Sagal deletes his Facebook account. [Person holding up a laptop with an "Facebook account not found" screen.] [Third row, first paper.] Wait Wait Don't Seduce Me How Lakshmi Singh stole Sagal's Heart. [A wistful Lakshmi Singh being left by a sullen Peter Sagal.] [Third row, second paper.] Wait Wait Don't Leave Me [A wistful Peter Sagal being left by a furious Beth Sagal.] Sagal's wife out after affair [Third row, third paper.] Wait Wait Don't Spray Me Police Raid Sagal's Occupy NPR protest [Scummy policeman in riot gear spraying Peter Sagal in the face point blank.] [Third row, fourth paper.] Wait Wait Don't Indict Me Sagal, five others named in cash-for-tote-bags scandal [Peter Sagal doing a perp walk.] [Fourth row, first paper.] Wait Wait Don't Clone Me Peter Sagal 'Outraged' over DNA harvesting. [Fiery Peter Sagal, missing a small amount of DNA, at a lectern.] [Fourth row, second paper.] Wait Wait Don't Bust Me Peter Sagal's ghost captured [Ghostbusters, careful not to cross the streams, capture the ghost of Peter Sagal.] [Fourth row, third paper.] Wait Wait Don't Dissect Me Snoozing Sagal nearly snuffed in autopsy snafu [Peter Sagal running away from from a very surprised pathologist.] Peter Sagal: "I aten't dead" [Fourth row, fourth paper.] Wait Wait Don't Objectify Me Peter Sagal is more than just a piece of meat [Fifth row, first paper.] Wait Wait Don't Beatify Me [Peter Sagal shakes his fist at a picture of the pope.] Peter Sagal Rebukes Pope [Fifth row, second paper.] Wait Wait Don't Me Peter Sagal Accidentally [Peter Sagal in a blank vacant.] [Fifth row, third paper.] Wait Wait Don't Speak Its Name [eyes... Eyes... AAAHHH.] Peter Sagal wakes Eldritch terror Peter Sagal:"AAAAAAAA" [Fifth row, fourth paper.] Wait Wait Even For NPR This Is A Bit Much This American Life to document the road to recovery for those who suffer the trauma of losing on Wait Wait

Wait Wait... Don't Tell Me is an hour-long weekly radio news panel game show produced by Chicago Public Radio and National Public Radio . The show is hosted by playwright and actor Peter Sagal . Each episode ends with the panelists making up a potential future news story, usually with implausible "facts". This comic is making puns on the title of the show based on what Peter Sagal might have done that was newsworthy. Carl Kasell , who also served as the news anchor on Morning Edition , was the show's official judge and scorekeeper until May 2014 (after this comic was published), when he retired and was replaced by Bill Kurtis. The 1st row, 4th paper may refer to the Laugh Factory Incident of 2006. In the 3rd row, first paper, Lakshmi Singh is NPR's national midday newscaster. This paper leads to the second paper on the third row, in which Sagal's wife divorces him over his affair with Singh. In the 3rd row, 3rd paper is a reference to a protest at UC Davis (on the campus of University of California, Davis) protests in early 2012 in which sitting, peaceful protesters were calmly pepper-sprayed in their faces by a police officer. That spawned an internet meme of epic proportions . In the 4th row, 2nd paper is a reference to the movie, Ghostbusters . In the 4th row, 3rd paper is a reference to Granny Weatherwax of Terry Pratchett's Discworld novels; Granny Weatherwax is a witch who carries a sign saying " I ATEN'T DED "(sic) when having out-of-body experiences. In the 5th row, 2nd paper is a reference to another internet meme in where someone leaves out the verb in the sentence. The implication is that the verb is something bad, but which bad thing is left as an exercise to stew in the reader's mind. See the I Accidentally ___ meme for more information. In the 5th row, 3rd paper is a reference to the Eldritch abomination Cthulhu, from " The Call of Cthulhu " by H.P. Lovecraft . He is one of the Old Ones, the Elder Gods, and is awakened by his worshipers chanting, "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn" ("In his house at R'lyeh, dead Cthulhu waits dreaming.") Hence the title, "Wait, Wait, Don't speak its name." Two years later another New Years comic, 1311: 2014 , took a similar look at what could happen in 2014, just as this does for 2012. Interesting enough the title of that comic (just the year it was looking at) is more related to the title of the next comic after this one, which is also a New Year comic, and the title is also just the number of the year: 998: 2012 . Headlines! Stockpiled in case Peter Sagal, host of NPR's Wait Wait Don't Tell Me , does something newsworthy in 2012. [Series of above-the-fold newspapers follows; Each has a headline, picture in most of them, and an explanation.] [First row, first paper.] Wait Wait Don't Shoot Me [A fierce Peter Sagal in a balaclava brandishes a gun in a supermarket.] NPR's Sagal in Whole Foods hostage standoff. [First row, second paper.] Wait Wait Don't Vote For Me Peter Sagal quits race for GOP top spot [A sullen and defeated Peter Sagal surrounded by supporters admits defeat.] [First row, third paper.] Wait Wait Don't Judge Me Sagal opens up about his Kermit fantasy. [Stock profile images of Peter Sagal and Kermit the Frog.] [First row, fourth paper.] Wait Wait Don't Fire Me [Stock profile image of Peter Sagal.] Peter Sagal let go after racist tirade. [Second row, first paper.] Wait Wait Don't Cancel Me NPR axing news quiz. [NPR spokesperson delivering announcement.] [Second row, second paper.] Wait Wait Don't Interrupt Me Sagal stabs Carl Kasell in on-air dispute. [Peter Sagal mid-attack with a knife.] [Second row, third paper.] Wait Wait Don't Look At Me [Peter Sagal with a skin condition.] Peter Sagal's Poison Ivy Ordeal Peter Sagal: "My 'Nam" [Second row, fourth paper.] Wait Wait Don't Friend Me Peter Sagal deletes his Facebook account. [Person holding up a laptop with an "Facebook account not found" screen.] [Third row, first paper.] Wait Wait Don't Seduce Me How Lakshmi Singh stole Sagal's Heart. [A wistful Lakshmi Singh being left by a sullen Peter Sagal.] [Third row, second paper.] Wait Wait Don't Leave Me [A wistful Peter Sagal being left by a furious Beth Sagal.] Sagal's wife out after affair [Third row, third paper.] Wait Wait Don't Spray Me Police Raid Sagal's Occupy NPR protest [Scummy policeman in riot gear spraying Peter Sagal in the face point blank.] [Third row, fourth paper.] Wait Wait Don't Indict Me Sagal, five others named in cash-for-tote-bags scandal [Peter Sagal doing a perp walk.] [Fourth row, first paper.] Wait Wait Don't Clone Me Peter Sagal 'Outraged' over DNA harvesting. [Fiery Peter Sagal, missing a small amount of DNA, at a lectern.] [Fourth row, second paper.] Wait Wait Don't Bust Me Peter Sagal's ghost captured [Ghostbusters, careful not to cross the streams, capture the ghost of Peter Sagal.] [Fourth row, third paper.] Wait Wait Don't Dissect Me Snoozing Sagal nearly snuffed in autopsy snafu [Peter Sagal running away from from a very surprised pathologist.] Peter Sagal: "I aten't dead" [Fourth row, fourth paper.] Wait Wait Don't Objectify Me Peter Sagal is more than just a piece of meat [Fifth row, first paper.] Wait Wait Don't Beatify Me [Peter Sagal shakes his fist at a picture of the pope.] Peter Sagal Rebukes Pope [Fifth row, second paper.] Wait Wait Don't Me Peter Sagal Accidentally [Peter Sagal in a blank vacant.] [Fifth row, third paper.] Wait Wait Don't Speak Its Name [eyes... Eyes... AAAHHH.] Peter Sagal wakes Eldritch terror Peter Sagal:"AAAAAAAA" [Fifth row, fourth paper.] Wait Wait Even For NPR This Is A Bit Much This American Life to document the road to recovery for those who suffer the trauma of losing on Wait Wait

2012

2012

https://www.xkcd.com/998

https://www.explainxkcd.com/wiki/index.php/998:_2012

[Cueball and Megan are talking.] Cueball: Well, it's 2012. [Cueball and Megan in frameless panel.] Megan: Yup. Megan: Only 354 days left until everybody abruptly stops talking about Mayans. [Cueball and Megan in wide panel to fit longer text content.] Cueball: Or thinking about Mayans. Cueball: Or acknowledging that huge city-building ancient American civilizations existed at all. Megan: You know what they say — those who fail to learn from history can still manage a 3.0 if they ace their other subjects.

This New Year comic is in reference to the fact that the Mayans , an ancient civilization in the Americas , created a calendar that ends (or, more accurately: restarts) on December 21, 2012. This date is regarded as the end-date of a 5,125-year-long cycle in the calendar used by the Mayan culture. Knowing this, some thought that the world was going to end on that date. Consequently, a lot of people were talking about the Mayans, concerned that the world might end. After December 21, 2012 passed uneventfully, everyone was less concerned about the Mayans, because the world didn't end [ citation needed ] . It is worthy of note that this comic was published nearly a year before the "significant" date and that Randall predicted both the hype and the aftermath perfectly. There is a measure of irony to be had in how the Mayans who still exist today were largely ignored by the doomsayers. "Or acknowledging that huge city-building ancient American civilizations existed at all." In the final frame, Megan parodies the phrase, "Those who fail to learn from history are doomed to repeat it," applying a twist to suggest an academic context. In most American schools, a Grade Point Average is computed by assigning numeric value to each letter grade: A=4, B=3, C=2, D=1, and F=0; receiving high marks (all A's) thus yields a 4.0 GPA. However, if you "Fail to learn from History" — that is, get a failing grade, F, and had at least 3 other classes (not an unusual course load) — you would still get a 3.0 with A's in those other classes. With a more common workload of eight courses per year, GPA as high as 3.5 can actually be reached in those circumstances. She is making the callous — if roundabout — observation that failing to grasp history, while no doubt troubling, isn't an academic show-stopper. Her comment may also be taken to suggest that people who feared the Mayan "prediction" of the end of the world would come to pass had failed to appropriately extrapolate from the numerous other faulty predictions of the end of the world . In fact the Mayans never actually predicted the end of the world with their calendar, those who failed to learn from history jumped to conclusions yet again. The title text jokes that to make up for the lack of Mayan discussion, Randall plans to spend 2013 talking solely about Mayans. For obvious reasons [ citation needed ] , people would probably get sick of this very quickly, hence his comment that his relationships might not fare well. Thankfully, as of 2014, not a single published xkcd comic of 2013 featured any Mayans, so we're pretty sure this promise wasn't kept. [Cueball and Megan are talking.] Cueball: Well, it's 2012. [Cueball and Megan in frameless panel.] Megan: Yup. Megan: Only 354 days left until everybody abruptly stops talking about Mayans. [Cueball and Megan in wide panel to fit longer text content.] Cueball: Or thinking about Mayans. Cueball: Or acknowledging that huge city-building ancient American civilizations existed at all. Megan: You know what they say — those who fail to learn from history can still manage a 3.0 if they ace their other subjects.

Cougars

Cougars

https://www.xkcd.com/999

https://www.explainxkcd.com/wiki/index.php/999:_Cougars

[Cueball is sitting at a computer; a child is standing behind.] Cueball: Whoa, ever seen Wikipedia's list of people who were attacked and killed by cougars? Cueball: Crazy how many of them were kids who were just playing outside their houses. [Caption below the panel:] Reason #58 I should never have children: My love of learning and sharing knowledge about the world.

Randall is giving reason number 58 why he should not have children. We see fictitious "father Cueball " talking about the Wikipedia entry for " List of fatal cougar attacks in North America ". As stated, many of the victims were young children near their home. If you tell a child about something dangerous, but without giving them necessary context to feel protected from it, you are likely to cause nightmares, sleeplessness, or other fear-related issues [ citation needed ] . In most, if not all, cases this would be considered bad parenting, hence a person who enjoys doing so should perhaps not have children. The title text demonstrates that not only is Cueball sharing factual information, he is intentionally adding hypothetical detail (e.g. "yellow eyes glinting in your window") to make the danger seem even worse. The child is unlikely to agree that learning this is fun. Incidentally, a panther is not an actual species but rather a term for either leopards or jaguars with melanistic conditions. Mountain lions themselves are rarely called panthers. [Cueball is sitting at a computer; a child is standing behind.] Cueball: Whoa, ever seen Wikipedia's list of people who were attacked and killed by cougars? Cueball: Crazy how many of them were kids who were just playing outside their houses. [Caption below the panel:] Reason #58 I should never have children: My love of learning and sharing knowledge about the world.

1000 Comics

1000 Comics

https://www.xkcd.com/1000

https://www.explainxkcd.com/wiki/index.php/1000:_1000_Comics

[1000 characters, numerous of which have appeared previously in other comics, are arranged to create the number "1000". Two more people stand in the foreground commenting on the formation. There are several comments amongst these 1000 but here are only written the text that can be read from the small version shown above.] 1000 Megan: Woooo! Cueball: Wow—Just 24 to go until a big round-number milestone!

This comic is the 1000th comic shown on xkcd containing 1000 characters from previous comics arranged in the shape of the number "1000". Megan is clearly excited as she screams "Woooo!", but Cueball , in true nerd fashion, thinks in base-2, saying that there are just 24 to go until a "big round-number milestone". The joke is that during programming, base-2 is used more often than base-10, making milestones powers of two rather than powers of 10. Where 1000 is a round number in base 10 (10 3 ), 1024 is a round number in base 2 (2 10 ). Binary is also referenced in the "Connect the Dots" puzzle, explained below. In the 1000 comic Randall included 404: Not Found , see why in the explanation for this comic. This comic strengthens the fact that Randall did indeed count 404 as a "real" comic. Each of the characters/drawings is numbered on this page: About 2/3rds are described on this page: There is a "Connect the Dots" puzzle hidden within the comic. However, rather than using the conventional decimal system numbering which would start with 1 and count up, 2, 3, 4, 5, ... This "Connect the Dots" puzzle starts with 0 as a programmer would do and counts up in binary numerical order - 0,1,10,11,100,101,110,111,1000,1001 and back to 0. The revealed image forms the shape of a heart. This fits well with the title text where feeling less alone can equate to feeling loved. [1000 characters, numerous of which have appeared previously in other comics, are arranged to create the number "1000". Two more people stand in the foreground commenting on the formation. There are several comments amongst these 1000 but here are only written the text that can be read from the small version shown above.] 1000 Megan: Woooo! Cueball: Wow—Just 24 to go until a big round-number milestone!