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Decision Paralysis

Decision Paralysis

https://www.xkcd.com/1801

https://www.explainxkcd.com/wiki/index.php/1801:_Decision_Paralysis

[Megan and Cueball are standing near two sport cars. Megan points excitedly at the cars while Cueball looks at his smartphone.] Megan: There! If we steal one of those cars, we can get to the base and defuse the bomb! Cueball: Hmm, the one on the left accelerates faster but has a lower top speed. Cueball: Ooh, the right one has good traction control. Are the roads wet? [Caption below the frame:] Protip: If you ever need to defeat me, just give me two very similar options and unlimited internet access. "A discrete decision based upon an input having a continuous range of values cannot be made within a bounded length of time."

This comic illustrates a common problem in the internet era where, with the wealth of knowledge available to us at all times, one puts undue weight on otherwise arbitrary decisions. This is taken to a comedic extreme by showing how Cueball is unable to make a critical, time-sensitive choice without putting hours of research in to justify it. Any benefit to researching the imminent decision of "which car will get us to our destination fastest" will be more than offset by the time it takes to make that decision. [ citation needed ] The inability to make a snap judgment in this case will prove very destructive as the bomb mentioned by Megan will now likely detonate before they get to the base. The difference in time/effort needed to steal either car is likely presumed to be insignificant to this scenario. In the caption below the comic Randall gives the reader one of his recurring protips . In the tip, he reveals a weakness for his potential opponents to exploit. Randall admits to having the same problems with decision-making as Cueball, and suggests that if he were placed in an equally urgent situation testing his (in)ability to choose, he would fail just as spectacularly, as long as he had free access to the internet. As the old saying goes, "give 'em enough rope, and they'll hang themselves"; in this case, give Randall enough internet access, and he'll get caught in an indefinite research loop. The title text continues this absurdity by bringing a third option to the table, the choice of inaction (which by wasting his time on calculations and research, Cueball has taken), a choice here that seems unacceptable, but the time spent mentioning (and researching it) simply adds to that already spent researching the two cars. Of course this option ensures that they are not killed when the bomb explodes, because they will not be anywhere close to the base. That might make it the only reasonable choice left after wasting so much time pondering which car to steal. That not making a choice is also a choice has often been mentioned in literature and other places, like when the band Rush in their song Freewill sings "If you choose not to decide - You still have made a choice". Supposing both of them know how to drive (and steal) a car and defuse the bomb, the best option in this situation is to leave the phone in the pocket and steal both cars, and see who gets there first to defuse the bomb. This would both ensure one of them reaches the base as quick as possible and at the same time resolve the problem of which car would be best for the problem. Of course that would also have defused the joke, No Pun Intended ... [Megan and Cueball are standing near two sport cars. Megan points excitedly at the cars while Cueball looks at his smartphone.] Megan: There! If we steal one of those cars, we can get to the base and defuse the bomb! Cueball: Hmm, the one on the left accelerates faster but has a lower top speed. Cueball: Ooh, the right one has good traction control. Are the roads wet? [Caption below the frame:] Protip: If you ever need to defeat me, just give me two very similar options and unlimited internet access. "A discrete decision based upon an input having a continuous range of values cannot be made within a bounded length of time."

Phone

Phone

https://www.xkcd.com/1802

https://www.explainxkcd.com/wiki/index.php/1802:_Phone

[Someone off-panel asks Cueball a question which he answers while walking to a small table with some items laying on it.] Off-panel voice: Wanna go for a walk? Cueball: Sure, just need to grab my device that feeds me a 24/7 stream of opinions, context-free scary world news, and random emotional stimuli. Cueball: Plus a spare battery so the feed won't be interrupted.

When someone asks you if you want to go for a walk they often expect to have a conversation, while enjoying both the exercise, the fresh air and the company. Thus any disturbance not related to the walk is not welcome. Going for a walk is often seen as a way to relax from all the daily stress, as it takes the walkers away from work and chores. Cueball agrees to go for a walk, but not to all the associated expectations. His first instinct is to bring along his smartphone , though rather than call it such, he opts for a lengthy description detailing all the functions he intends to use. He describes the phone as a device that gives him a continuous ( 24/7 ) stream of information, much of which is often out of context. The stream contains people's opinions, context-free but scary news, and other random stimuli. Conspicuously, long-distance communication (ostensibly the primary function of a smartphone) is not listed. This may be a sign that Cueball is addicted to his phone . The stream of opinions mentioned could be from news or bloggers but it could also just be from his friends on social media platforms. News stories that are shared on social media are often scary, which becomes even worse because news outlets are likely to use a title that exaggerates the topic to create a fear reaction. The random emotional stimuli could be from many things such as text messages/emails and pictures of kittens and babies on social network, and shared internet memes or viral videos. All things that could cause a quick shift in emotions. As if all this was not enough, Cueball even says he will also take his spare battery, so he won't risk that his constant feed could be interrupted, because he will not be able to recharge his phone during the walk. All in all, his choice and constant need for staying updated and being online violates all the usual expectations, that his friend could have expected from asking him out for a walk. Randall's fear of running out of power on his smartphone was earlier mentioned in 1373: Screenshot , where a low battery charge stresses him too much to realize it is someone else's screenshot, rather than his own phone that has a low charge. Since then he has made other references to his issue with low batteries in 1872: Backup Batteries and 1965: Background Apps . The title text shows it would be possible to take an action to avoid this feed. In the first bracket a person (could be Cueball or Randall ) disables all his social networking accounts . Most of his news feed will thus disappear. But this leads to the next bracket which states that such a choice would lead to increased social isolation , since he will no longer be in contact with any of his online friends. In fact, today many people also get into contact with their "real" local friends through social media, so one might thus miss out on events like parties or get-togethers. In addition, his friends, not sharing his dislike for social media, may not understand his decision. All of this leads to the final sentence Wait, why does this ALSO feel bad? [Someone off-panel asks Cueball a question which he answers while walking to a small table with some items laying on it.] Off-panel voice: Wanna go for a walk? Cueball: Sure, just need to grab my device that feeds me a 24/7 stream of opinions, context-free scary world news, and random emotional stimuli. Cueball: Plus a spare battery so the feed won't be interrupted.

Location Reviews

Location Reviews

https://www.xkcd.com/1803

https://www.explainxkcd.com/wiki/index.php/1803:_Location_Reviews

[Inside the main panel there is a frame with a Google location map with the typical red pin stuck in the center of the map inside a large gray region of the map. A river goes from the north through the gray region and out to the west. East and south of the river some roads and other items are shown, several of them also outside the gray region. The red pin is stuck next to a corner in one of the roads.] [Below the map is the name of the location at the red pin, and below that there are three lines of unreadable text:] Canyon River Nuclear Launch Facility [Below that there is broken line with text in the break, and below that follows 11 reviews with yellow stars to the left. The stars are either just outlines or colored completely, with the left one always being filled:] Reviews (22) [5 of 5 stars filled] Greatest country on earth [2 of 5 stars filled] Looks cool but you can't get in [1 of 5 stars filled] What is this store [4 of 5 stars filled] My cousin worked here [2 of 5 stars filled] Waitstaff heavily armed and very rude [1 of 5 stars filled] Stop doing chemtrails [1 of 5 stars filled] This place is a symptom of the military-industrial complex strangling our democracy and... (read full review-1184 words) [4 of 5 stars filled] Anyone else notice the hole in the west fence? [5 of 5 stars filled] Whoa, missiles! [3 of 5 stars filled] Good idea but confusing web site. How do I preorder? [1 of 5 stars filled] Please don't launch these [Caption below the panel:] I love finding reviews of places that really don't need to have reviews.

Many online advertising services and social media networks (like Google and Yelp , both mentioned in the title text, and for instance Facebook ) allow users to leave reviews of stores, businesses and locations. For various reasons these sites often find themselves with pages dedicated to, as Randall puts it, "places that really don't need reviews" such as municipal works installations, government property, and natural landmarks. This naturally attracts both clueless people and lots of self-styled comedians leaving less-than-helpful comments on such review pages. Randall is just poking fun at this phenomenon by inventing possible reviews for the (fictional) location Canyon River Nuclear Launch Facility , depicted with a Google Maps -styled map page along with a series of so-called reviews. (There does exist a Canyon River located in Ontario / Canada and one in Washington /USA (the latter is a significant tributary to the Satsop River ). Canada does not maintain nuclear weapons since 1984, so the launch site should be located in Washington). See explanations for the 11 visible (out of 22) reviews in the table below . Of course those responsible for such a facility with nuclear missiles would not like the attention they would be getting in this way, especially not when one of the comments mentions a hole in the fence... Although this comic makes a joke about reviews it has chosen a very dangerous facility to joke about. See more about this under Politics below In the title text Randall mentions that both Google and Yelp keep deleting his scathing reviews of several locations like the above. The questions is if they would have done it if they had not been so harsh... While Canyon River Nuclear Launch Facility appears not to exist, the places/phenomena he lists in the title text certainly do, and are places that you either cannot or would not normally visit as destinations. Here below each "location" is explained. That the deletion of such reviews is real has been proven by this comic, as it also happened for those that (of course) posted these reviews on Google maps as a response to this comic. Mariana Trench is the deepest area of the world's oceans, about 10,994 meters (36,070 ft) deep, located between Japan and Australia. The pressure in the Mariana Trench is about 1,086 bars, more than 1,000 times the standard atmospheric pressure of about 1 bar at sea level. Despite this enormous pressure some organisms live in the Mariana Trench . Humans can reach the ground only by special deep-sea submarines, like Jacques Piccard did in 1960 with the Bathyscaphe Trieste . See reviews for the Mariana Trench at Google Maps and Facebook . The Chernobyl reactor core is the most dangerous part of the Chernobyl Nuclear Power Plant . It is located in the North of Ukraine. In the reactor No. 4 there was a nuclear disaster that happened on 26 April 1986. It caused devastating damage and massive radioactive contamination. There is still a Chernobyl Exclusion Zone 30 kilometers around the power plant. See reviews for the Chernobyl power plant at Google Maps and Facebook . Jet streams are a meteorologic phenomenon about 9 to 16 kilometers above the ground. A stream consists of air currents with speeds from 92 km/h (50 kn; 57 mph) to over 398 km/h (215 kn; 247 mph). Such jet streams are routinely used for reducing fuel usage for long distance plane travels. As it is a ribbon rather than a point, it could not have a single point on the map. Also, the jet stream fluctuates north and south; so even if it could be pinpointed, the location would be constantly changing. The equator is, as with the jet streams, not a singular place but a circumference around the Earth. Reviewing the equator as a singular location is rather pointless, though there is a whole range of specific (and interesting) locations around the equator, with countries with tropical rainforest climate , which many people from European and North American countries struggle with. That said, most of the equator goes over water. In the table the rating is given with the review. After that an explanation both of the rating and of the review is given. Notice that any or all of the reviews could be sarcastic or "trolling", as is fairly typical on the internet, especially for reviews given for such a location as this one. This table assumes all the reviews are played straight. The decision to make a comic depicting a nuclear missile launch facility may not be entirely random, given Randall's mildly political mood lately. In particular, it could be due to the cold relationship between Russia and the United States at the time of this comics release. Two weeks prior to this comics release Russia Deploys Missile, Violating Treaty and Challenging Trump . This was less than a month after Donald Trump became president. Trump has been positive towards Vladimir Putin earlier, but after the violation USA condemned the new missile. That Randall was not in favor of Trump becoming president was made clear in 1756: I'm With Her . His predecessor Barack Obama even stated, before Trump was elected, that If Trump can't handle Twitter, then he can't handle nuclear codes . Randall has earlier mentioned the codes indirectly in 1242: Scary Names , where he mentions the Nuclear football , which is much more scary than the name... It is a year ago he finished a "series" of four comics in a short period about nuclear weapons with 1655: Doomsday Clock (see about the other comics at the bottom of that explanation). But it seems that recent events have made him think about it again, although he tries no to as made evident in 1796: Focus Knob . [Inside the main panel there is a frame with a Google location map with the typical red pin stuck in the center of the map inside a large gray region of the map. A river goes from the north through the gray region and out to the west. East and south of the river some roads and other items are shown, several of them also outside the gray region. The red pin is stuck next to a corner in one of the roads.] [Below the map is the name of the location at the red pin, and below that there are three lines of unreadable text:] Canyon River Nuclear Launch Facility [Below that there is broken line with text in the break, and below that follows 11 reviews with yellow stars to the left. The stars are either just outlines or colored completely, with the left one always being filled:] Reviews (22) [5 of 5 stars filled] Greatest country on earth [2 of 5 stars filled] Looks cool but you can't get in [1 of 5 stars filled] What is this store [4 of 5 stars filled] My cousin worked here [2 of 5 stars filled] Waitstaff heavily armed and very rude [1 of 5 stars filled] Stop doing chemtrails [1 of 5 stars filled] This place is a symptom of the military-industrial complex strangling our democracy and... (read full review-1184 words) [4 of 5 stars filled] Anyone else notice the hole in the west fence? [5 of 5 stars filled] Whoa, missiles! [3 of 5 stars filled] Good idea but confusing web site. How do I preorder? [1 of 5 stars filled] Please don't launch these [Caption below the panel:] I love finding reviews of places that really don't need to have reviews.

Video Content

Video Content

https://www.xkcd.com/1804

https://www.explainxkcd.com/wiki/index.php/1804:_Video_Content

[From left to right: Hairy, Cueball, Megan and Hairbun sit around a conference table.] Cueball: Research shows young people like YouTube, so we should present news stories as videos instead of text! Megan: Good idea! Hairbun: They'll love that! [Caption below the panel:] Instead of arguing with newspapers about this, we should just tell them how much young people like making out and see what happens.

This comic is a commentary on the growing publishing industry and their successful attempts at regaining an audience. News media has evolved dramatically as the world entered the information era . Newspapers , which were at one point the most widely distributed and consumed form of media, have rapidly been eclipsed by new technologies such as television , Internet , and streaming video . Subscriptions to paper-based media have been drastically declining to the point where many publishers are on the verge of shutting down. While publishers are making an effort to move their content to newer, more popular forms of media, in many cases they are still clearly behind the times. The comic illustrates one such example with Cueball suggesting presenting news stories as videos rather than text. This is presented and received by Megan , Hairbun and Hairy as a clever new idea that would appeal to young people based on the fact that they like watching YouTube videos. However, apparently no one in the comic has realized that television news programs have been filling such a niche for decades and that young people are just as uninterested. In fact, online video based news is often considered annoying, especially if autoplaying or if there is no text based alternative. In reality, this idea is not at all original and likely to be doomed to fail from the start. As with many similar attempts, the new "ideas" that publishers are trying to adopt are merely cramming news content into things young people like, without really understanding why they like it and without considering whether news would be a good fit. In the caption, Randall suggests it would be pointless to argue with newspaper publishers about their ideas. Presumably Randall believes publishers who fall for those ideas are already out of touch with the new generation, and would not be able to understand why those ideas lack merit. Instead, he suggests taking the trend to a ridiculous extreme, by telling publishers that young people like making out . Suppose publishers follow the same pattern and try to cram news into this as well, they would end up creating some form of news program centered around making out. The results may turn out completely laughable or highly entertaining. If the former, it could serve as a wake-up call to publishers that they need to reconsider their approach. If the latter, then it could actually become a trend and unexpectedly reinvigorate the industry. In the title text it seems like the news agency actually consider this idea, or is at least confused enough to ask. Their interpretation of combining "making out" with news is to make it sexy, but the next speaker says that this has been tried before and doesn't work. This is likely a reference to Naked News (no link due to NSFW -ness), a news program that does that: it features attractive women delivering the news while simultaneously disrobing. This concept has not, for some reason, spread to the mainstream. According to the speaker, merely making the news sexy is not enough – the news content must be directly integrated into the making out; how this would be accomplished is as yet unclear. The title text also dismisses the proposed name Mouth Content as possibly the title of a Neil Cicierega album, in reference to his recently-released Mouth Moods , as well as his prior albums Mouth Sounds and Mouth Silence . [From left to right: Hairy, Cueball, Megan and Hairbun sit around a conference table.] Cueball: Research shows young people like YouTube, so we should present news stories as videos instead of text! Megan: Good idea! Hairbun: They'll love that! [Caption below the panel:] Instead of arguing with newspapers about this, we should just tell them how much young people like making out and see what happens.

Unpublished Discoveries

Unpublished Discoveries

https://www.xkcd.com/1805

https://www.explainxkcd.com/wiki/index.php/1805:_Unpublished_Discoveries

[Ponytail walks up to Megan, who is sitting in an office chair at a desk using her laptop.] Ponytail: When you make a big scientific discovery, it takes a while to get it published. Ponytail: Right? Megan: Mm hmm. [Zoom-in on Ponytail.] Ponytail: So there are probably several research teams out there who are sitting on Nobel-Prize-worthy discoveries, but haven't told the rest of us yet. Megan (off-panel): Makes sense. [Ponytail leans over the desk, trying to see Megan's laptop screen from behind it.] [Ponytail leans further. Megan pulls the screen down so Ponytail cannot see it.] Ponytail: Sooo... What are you working on? Megan: It isn't me! Ponytail: I promise I won't tell. Megan: Shoo! Go bother someone else.

Ponytail walks up to Megan , and makes the observation that when a scientific discovery is made, it then takes a while to publish it. She then goes on to note that there are probably research teams making "Nobel-Prize-worthy" discoveries that have simply not been published. She is obviously curious if Megan is working on something like this, and tries to see what Megan is working on, but Megan prevents her from seeing this by partly closing her laptop. Then Ponytail asks Megan what she is doing but Megan just tells her that she isn't the one working on a project like this and ask her to "Go bother someone else." This is not the first time Ponytail asks Megan if she is working on some groundbreaking research project: Back in 1067: Pressures , Ponytail was probing Megan about her work, since, as hinted by the caption of that comic, Megan is a Swiss patent clerk just like Albert Einstein . Ponytail thus assumes she has the same potential to produce Nobel-Prize-worthy work as him. While there is no clear indication that this comic should be a continuation of that comic or that Megan is a patent clerk, Ponytail still assumes Megan is on her way to a Nobel Prize - but that Megan is just not yet ready to announce her discovery to the public for one reason or another. In the first two panels, Ponytail is referring to the general issue that, to publish a discovery on a scientific topic, it can take a very long time, especially when the discovery is "Nobel-Prize-worthy". Obviously the first step is for the researcher to demonstrate rigor by more supporting experiments (see 397: Unscientific ), plus summarize the discovery into the format accepted by the journal the paper is submitted too. The latter can take considerable time by itself, especially if the first journal the paper is submitted to declines publication. Because other journals chosen afterwards may have a completely different layout (for instance in physics, the journal with the greatest impact factor is Nature , then followed by for instance Science and then Physical Review Letters . All three have very different layouts regarding format and figures etc.) Thus the paper may need to be submitted to various journals until one accepts, which may also take a few months, and even when accepted it can take anywhere from 25 days to 150+ days just for the paper to be processed through the publishing system due to various reasons , including the nature of the publishing process, assigning extra work as conditions for acceptance, or even formatting problems. This has prompted researchers to come up with some interesting work-arounds . In the title text, Megan claims that she is actually just trying to convert an emailed tax form to a PDF. This could of course just be to ward off any further attempts by Ponytail to spy on her "real" Nobel-worthy work. Megan sarcastically states that her conversion of tax forms is in the running for a Nobel Prize, perhaps because she considers it an incredibly difficult task (even for these things that should not be hard - see 1349: Shouldn't Be Hard ). While this could be true, this task is in no way connected to any kind of scientific endeavor, and as a result could never be considered for any kind of Nobel Prize. That the task is so difficult is though officially acknowledged by the IRS as they themselves note that saving and printing their Online tax forms could be tricky. Quote: Fill-In Tax Forms The IRS also offers Free Fillable Forms which allow you to save (and print) the information you’ve typed in online. The fill-in tax forms also require Adobe Acrobat Reader software. To save the data you’ve filled in, use the Adobe Reader’s “Save” function (not the web browser’s “Save” function). ... The months and weeks before April 15th (this comic was released on March 1st), is the "tax season" in the US so Americans are in the process of completing their tax forms, which is why this comic is timely. Given the US tax code is complained by many to be too complex , it is possible for researchers to delay publication of their discoveries to deal with their tax returns first. This can cause people to "sit on their discovery" for a while, although hopefully not as long as the task of publishing itself. A year after this comic, 1971: Personal Data became the second tax related comic to be released in March, close to the tax day, making it two years in a row. Also before these comics the trouble with tax returns was the joke in 1566: Board Game , but it was released in August. [Ponytail walks up to Megan, who is sitting in an office chair at a desk using her laptop.] Ponytail: When you make a big scientific discovery, it takes a while to get it published. Ponytail: Right? Megan: Mm hmm. [Zoom-in on Ponytail.] Ponytail: So there are probably several research teams out there who are sitting on Nobel-Prize-worthy discoveries, but haven't told the rest of us yet. Megan (off-panel): Makes sense. [Ponytail leans over the desk, trying to see Megan's laptop screen from behind it.] [Ponytail leans further. Megan pulls the screen down so Ponytail cannot see it.] Ponytail: Sooo... What are you working on? Megan: It isn't me! Ponytail: I promise I won't tell. Megan: Shoo! Go bother someone else.

Borrow Your Laptop

Borrow Your Laptop

https://www.xkcd.com/1806

https://www.explainxkcd.com/wiki/index.php/1806:_Borrow_Your_Laptop

[White Hat walks toward Cueball's desk pointing at his laptop while looking back at Cueball standing behind him.] White Hat: Can I load it up on your laptop? Cueball: Sure! Cueball: Oh, just hit both shift keys to change over to QWERTY. Cueball: Caps lock is control. And spacebar is capslock. Cueball: And two-finger scroll moves through time instead of space. Cueball: And– [Caption below the panel:] Once I've used a computer for a while, no one else will ever use it again. Supporters claim that typing speed is faster on a Dvorak keyboard, although this is still contentious, and this is a reason Randall often makes jokes about it as can be seen in the category referenced above. The same problem would arise if the computer is set to another language than the keyboard layout, which often happens in countries where more than one language is common. Nevertheless by doing some registry hacking (Windows) or editing configuration text files (UNIX/Linux) it is possible to reach Cueball's approach. The simpler and operating system independent approach would be to use a programmable keyboard, such as a keyboard using QMK firmware [1] A typical classic configuration for the shift key in Windows is by pressing one of the shift keys five times in a row it turns on a Sticky Key notice, where the Ease of access center enables people with for instance only one hand to be able to reach Ctrl+Alt+Delete or other combinations on which two hands are needed.

White Hat asks to borrow Cueball's laptop to view something (possibly a website). Cueball permits this, but immediately begins rattling off a list of very unusual key- and mouse-bindings that he has applied to the device. In the caption, Randall states that he himself tends to continually re-configure computers that he owns in weird ways, eventually rendering it unusable or at least unpleasant to use for others. Of the three items in Cueball's list of customizations only the first and half of the second seems like a real and relevant changes. At first he has programmed the computer so that hitting both shift keys simultaneously will change the keyboard back to QWERTY. The QWERTY keyboard is the standard in the US (as well as some other places using the roman alphabet). This implies that Cueball prefers a different keyboard layout, (most likely the Dvorak keyboard layout, see trivia ), but doesn't need the printed letters to match up with those of the laptop. Cueball would have to make a special customization to make pressing the two shift key trigger this shift (see trivia ). Presumably Cueball can later return to this favorite layout by pressing the shift keys again. Cueball tells, in the first part of the second point on the list, that he has changed his keyboard layout so that capslock acts as the control key (Ctrl). Swapping capslock and control is a common thing to do in the world of enlightened users on Unix or for users of the Emacs editor . The "Caps Lock" key (immediately to the left of the "A" in a traditional layout) is much easier to reach for a touch typist than the more out-of-the-way "Ctrl", and the latter is often used more frequently, especially by programmers. However, the second part where Cueball says he has then moved capslock so that it is activated when hitting the spacebar makes no sense. It is quite impractical, as the spacebar is the largest key and it will not gain anything from being used for anything other than spaces, especially not a rarely used key that locks into capital letter mode move when activated. It would make the common accidental application of capslock more likely. And what is worse he doesn't tell White Hat where he has put the space bar function, making it impossible to write a simple text, although he could try to see what the Ctrl keys does now... Finally Cueball goes out on a limb with an impossible setting, which is that his laptop is setup so that scrolling moves through time instead of through "space" (as in up and down on the screen). This refers to spacetime , a common model in relativistic physics. The feature in only activated when using two-finger scroll , which is often used on touchpads /track pads for laptops as a gesture for scrolling. The title text may suggest that "moving through time" may pertain to undo/redo, or perhaps browser history. Finally it becomes clear these three settings are not the only important changes, as Cueball's list continues with at least one other point which he doesn't get to finish in the comic. Thus the list may be much longer than four points. In the title text Randall says that he would actually find a feature where the scroll wheel was mapped to send a stream of undo/redo commands would be kind of cool. (Notice he is no longer talking about the two-finger scroll from the comic). But only if used with software that could keep up with such a feature. He thus indirectly states that many programs would not be be able to keep up. For an example of what this might look like, many digital artists record timelapse footage of their art, which could be thought of as a continuous string of redo commands (occasionally broken up by undo commands whenever the artist needs to correct a mistake). Outside of art programs, such continuous undo/redo action would produce unexpected and chaotic results. This could also indicate that this was a similar feature that Cueball was referring to when talking about moving through time with the two finger scroll in the main comic. So not as in the computer traveling through time, but rather scrolling through the previous actions performed on the computer, as in moving through the computers past. People often have reasons to change their keyboard layouts on laptops, due to the reduced keyboard, which can leave vital keys out. Rather than change the keyboard layout all the time in order to access keys which are not accessible in one of the layouts, one can take advantage of text substitution and keyboard remapping programs to set shortcuts for keys they use often. [White Hat walks toward Cueball's desk pointing at his laptop while looking back at Cueball standing behind him.] White Hat: Can I load it up on your laptop? Cueball: Sure! Cueball: Oh, just hit both shift keys to change over to QWERTY. Cueball: Caps lock is control. And spacebar is capslock. Cueball: And two-finger scroll moves through time instead of space. Cueball: And– [Caption below the panel:] Once I've used a computer for a while, no one else will ever use it again. Supporters claim that typing speed is faster on a Dvorak keyboard, although this is still contentious, and this is a reason Randall often makes jokes about it as can be seen in the category referenced above. The same problem would arise if the computer is set to another language than the keyboard layout, which often happens in countries where more than one language is common. Nevertheless by doing some registry hacking (Windows) or editing configuration text files (UNIX/Linux) it is possible to reach Cueball's approach. The simpler and operating system independent approach would be to use a programmable keyboard, such as a keyboard using QMK firmware [1] A typical classic configuration for the shift key in Windows is by pressing one of the shift keys five times in a row it turns on a Sticky Key notice, where the Ease of access center enables people with for instance only one hand to be able to reach Ctrl+Alt+Delete or other combinations on which two hands are needed.

Listening

Listening

https://www.xkcd.com/1807

https://www.explainxkcd.com/wiki/index.php/1807:_Listening

[Black Hat and Danish enter Cueball and Ponytail's house. They have hardly passed the door mat, with the door still open showing the road and another house outside.] Ponytail: Hello, welcome to our house! Black Hat: Thanks for inviting us! Black Hat: Alexa, order two tons of creamed corn. Black Hat: Alexa, confirm purchase. [Caption below the frame:] When visiting a new house, it's good to check whether they have an always-on device transmitting your conversations somewhere.

This comic depicts Cueball and Ponytail welcoming Black Hat and Danish to their house. Black Hat immediately talks to Amazon Alexa to order two tons of creamed corn . This would be quite expensive (around $10,000), and the hosts would be charged because it was ordered on their Amazon Echo device. It would also be a serious inconvenience, as the purchase would be quite bulky and useless, seeing as an average person would have very little use for two tons of creamed corn. [ citation needed ] The caption claims that this is an effort to find systems recording conversations, such as Alexa or Google Home , for the security of the guests , so they aren't being monitored by an always-on listening device without their consent (at least not without any consequences). However, because Black Hat is the one coming up with this it's more likely his motives are on the sadistic side, and it's more likely a warning for the hosts to turn off any voice-activated systems before having guests come over, so that the guests don't take advantage of them. (It should also be noted that such purchasing services encourage the user to set up a PIN code to stem off such exploits.) A concerned "visitor" may also want to test for voice-activated systems when near any persons carrying an iPhone or Android mobile device, because these are also always-on listening devices. "Hey Siri" and "Ok Google" voice activation use the same technology as "Alexa" and "Echo" detection. The title text says that this takes care of the "host gift thing", referring to the custom where house guests give a gift to the hosts. However, Black Hat is making the hosts pay for it, so it can be as expensive as he wants, thus making this yet another example of his being a classhole . For more examples of this, see the trivia below. [Black Hat and Danish enter Cueball and Ponytail's house. They have hardly passed the door mat, with the door still open showing the road and another house outside.] Ponytail: Hello, welcome to our house! Black Hat: Thanks for inviting us! Black Hat: Alexa, order two tons of creamed corn. Black Hat: Alexa, confirm purchase. [Caption below the frame:] When visiting a new house, it's good to check whether they have an always-on device transmitting your conversations somewhere.

Hacking

Hacking

https://www.xkcd.com/1808

https://www.explainxkcd.com/wiki/index.php/1808:_Hacking

[Ponytail is writing on her laptop at her desk while Cueball looks over her shoulder.] Ponytail: You know how sometimes people put a space in their email address to make it harder to harvest? Cueball: Yeah? Ponytail: They have a tool that can delete the space! Cueball: Oh my god. [Caption below the panel:] Less-dramatic revelations from the CIA hacking dump

This comic is referencing an incident on the day before this comic was released, March 7, 2017, in which WikiLeaks exposed thousands of hacking exploits (thus the title) and programs from the CIA (see for instance this article: WikiLeaks Just Dumped a Mega-Trove of CIA Hacking Secrets ). Many of the tools that were in the leak were similar to publicly available tools, or not entirely unexpected, with several coming from sites such as StackOverflow and Reddit . The main joke in this comic refers to the common practice of adding spaces between parts of an email address when publishing them on websites. For example, " [email protected] " may be written as "john dot doe at example dot org". The purported goal of doing this is to thwart page scraping bots from harvesting the correct email addresses and prevent them from becoming the target of spam or being sold as address lists for email marketers. In this comic, Ponytail tells Cueball that the CIA has a tool which can delete such spaces. Such a tool can fix the space and most likely convert the words "dot" and "at" into their respective symbols. This will overcome the problems faced by harvesting tools, and make these email addresses more prone to receive spam. Cueball appears shocked to hear this news, but given the caption below, stating that this was one of the less dramatic revelations from the CIA hacking dump, this is likely sarcasm by Cueball (and Randall ). In fact, it is quite simple to devise a program which detects and converts/removes such spaces; it's naive to believe that one can prevent e-mail addresses from being harvested just by writing the addresses with space or omitting @ etc. Some people might not realize that he's being sarcastic, though, and that misunderstanding might be part of the joke. The title text lists three other undramatic (fictitious) hacking exploits which sound more interesting, but are still more or less useless, and certainly not dramatic news. They are: [Ponytail is writing on her laptop at her desk while Cueball looks over her shoulder.] Ponytail: You know how sometimes people put a space in their email address to make it harder to harvest? Cueball: Yeah? Ponytail: They have a tool that can delete the space! Cueball: Oh my god. [Caption below the panel:] Less-dramatic revelations from the CIA hacking dump

xkcd Phone 5

xkcd Phone 5

https://www.xkcd.com/1809

https://www.explainxkcd.com/wiki/index.php/1809:_xkcd_Phone_5

[An image of a smartphone with a common optical camera lens attached on its back is shown. Over the entire length the case is slightly rounded. There are several features visible as bottom like features at the top and bottom of the front as well a microphone like slit at the top. A sliding switch is visible on the side, and at the bottom there is a knob, a connector port and a small slit. Clockwise starting from the top left all the labels read:] Hook shot Bluetooth speaker Stained-glass display Gallium chassis remains solid up to 85°F Soundproof Can feel pain E-ZPass partnership: Phone can be dropped into coin basket to pay tolls Foldable (once) Screen transfers images to skin Retina storage Background task automatically catches and eats Pokémon Supercuts partnership: Trims hair fed into charging port Squelch knob IBM buckling-spring home button Cot-caught merger switch 60x optical zoom camera LORAN navigation 28-factor authentication [Below the phone:] Introducing The xkcd Phone 5 We're trying to catch up to Apple but refuse to skip numbers ®TM

This is the fifth entry in the ongoing xkcd Phone series , and once again, the comic plays with many standard tech buzzwords, and horribly misuses all of them, to create a phone that sounds impressive but self-evidently isn't to even the most ignorant customer. The previous comic in the series 1707: xkcd Phone 4 was released almost 8 months before this one and the next 1889: xkcd Phone 6 was released 7 months later. The slogan beneath the phone, "We're trying to catch up to Apple but refuse to skip numbers", is a reference to inconsistent product numbering, such as Samsung releasing the Note 7 after the Note 5 , likely in an attempt to catch up to the numbering of either the iPhone or Galaxy S series, both of which were already at 7. Similarly, there was also no official iPhone 2 . But there is an xkcd Phone 2 available. The trademark sign behind the word "numbers" possibly indicates a reference to the Apple spreadsheet app with the same name. This phone seems to have a curved display. But the edges are curved down and not up, as they are on other curved phones. The title text that says that the phone will be returned to you by the toll operators is a reference to E-ZPass partnership feature; see explanation in the table regarding that feature. Hook shot In The Legend of Zelda the Hookshot is a recurring weapon/tool. It is a machine consisting of a chain and hook. When used, the chain extends and sends the hook which is attached to it. It is used to bring items to Link or bring Link closer to a goal ( Link is the name shared by the main protagonists, each possessing the Spirit of the Hero). Likely a reference to new video game The Legend of Zelda: Breath of the Wild , which was released a week prior to this comic (ironically, that game does not feature the Hookshot). In the comic the hook shot is shown as a small port upon the phone's top; the hook itself is not visible, suggesting it is contained in the device until use. Most Hookshots in the game series are large enough to be grasped in or encompass the hand, with the hook being large and extending out of the tool even without use. The size of the port and absence of the hook before use implies a very small hook and a very thin chain, making it impractical for use in either of the tool's functions. Bluetooth speaker Bluetooth speakers are often used to play audio from a smartphone wirelessly, usually with more volume and better quality than the phone's small built-in speaker can provide. Embedding a bluetooth speaker into the phone would allow the phone to play audio from outside sources through its built-in speaker, which could be useful if no better speakers were available but would generally be avoided given the previously noted limitations of phone speakers. This is perhaps a jab at the current trend of playing music or Internet content audibly in public through the tiny, tinny speaker embedded in most phones. The Bluetooth speaker is located in the normal place for a phone's speaker. Stained-glass display Stained glass is colored glass, traditionally used for decorative windows in buildings most often churches. It is generally much thicker and because of the color much less transparent, especially for some colors, than the glass types normally used for touch-screens, making the phone difficult to use as it would remove some of the colors shown on the screen below the glass. A typical feature noticed about the glass for real phones would be its strength, as in work phones for construction workers. Gallium chassis remains solid up to 85°F Many high-end electronic devices have chassis made of alloys of light metals such as magnesium or titanium rather than steel or plastic . Besides being lightweight and of superior quality and durability than ordinary sheet steel or cheap plastic, these are often perceived as bragging points by the users, boasting about 'rare' metal chassis. Gallium , however, is an uncommon metal with a very low melting point of 85 °F (or 29.8 °C), making it one of only four pure metals (along with mercury , rubidium and caesium ) that can be liquid around room temperature. Because the melting point is lower than the average human body temperature of 98.6 °F (37 °C) a gallium smartphone chassis would melt in the user's bare hand, assuming it hadn't already done so due to heat produced by its internal components. Even if the electronics had good heat management, cooling in smartphones is normally accomplished by distributing heat to the case, not exhausting it. A similar real advertisement regarding the chassis would be that it was waterproof down to some depth (say, 85 feet or 25 meters). See also the feature below regarding this. Soundproof A Soundproof chassis could result in the unwanted effect that the speakers and microphone may not work as no sound may enter or leave the phones chassis. A more likely feature would be waterproof (see above point). Can feel pain Possibly a reference to intelligent personal assistants like Siri , Cortana or Alexa gaining consciousness (see 1807: Listening for the latter). Such artificial intelligence references is a recurring subject on xkcd. This could mean that either the phone feels pain for damages inflicted upon it or it feels the user's pain level (regarding either physical and/or emotional pain). The meaning would quickly become apparent for the user if the chassis melts on contact with exposed skin leaving the phone with "open wounds". This could be seen as a similar feature of the first xkcd phone, 1363: xkcd Phone , where the title text notices (among many other things) that the phone will drown if submerged in water. A similar thing is also mentioned for 1549: XKCD Phone 3 . That phone is waterproof but can drown . Since this phone is soundproof but not waterproof, per the two points above, the drowning issue may still be relevant. The second phone, 1465: xkcd Phone 2 , cries when lost a similar display of emotions/feelings. That phone also mentions waterproofing, but here it is only the interior, and although it is washable, it is only a one-time feature (like the fold-ability of this one; see two points below). Finally it also 1707: xkcd Phone 4 mentions that it is waterproof, but not between 30-50 m down... E-ZPass partnership Phone can be dropped into coin basket to pay tolls E-ZPass is an electronic toll collection system. The vehicle drives through the toll lane without stopping, and sensors detect the pass and deduct the appropriate amount from the user's account. The phone's integration with E-ZPass is absurd since the phone needs to be dropped into a coin basket to work. Not only would you have to stop in order to throw the phone into the coin basket, which defies the idea of E-ZPass, but you would also lose your phone. In the title text , however, it says that the phone will be retrieved by the toll operators and returned by mail within 4–6 weeks. So this slightly mitigates the problem of losing the phone, but there would be about a month where the phone could not be used. Foldable (once) Almost anything long and slim can be "folded" by simply snapping it in half. But as it says, this can only be done once, because the phone cannot be unsnapped and will not work any more once it has been folded. This is a reference to the rumors of the new Samsung Galaxy X that is really foldable like a piece of rubber. See this video . It could also refer to the fact that a version of iPhone had a weak spot that lead it to easily folding and breaking. And it could be a reference to flip phones . Screen transfers images to skin Transferring images to the skin sounds like either real tattoos or the water tattoos used by children or other kinds of temporary tattoos . Likely it should be understood that it would be possible to transfer the image displayed on the screen to your skin, hopefully when activating the feature rather than by accident, and, preferably, also not permanently. This may also be a reference to the experimental Cicret Bracelet's ability to project images onto your arm: [1] Retina storage This is a play on the name of Apple's prized " Retina Display ". The joke may be in reference to Apple's possession of a trademark for the word "retina" in regards to computer equipment, which is made to seem absurd by the unusual use. It is not made clear whose retinas are meant to be stored. It could also be a reference to retinally implanted computers. The retina storage is a slot at the bottom of the phone right of the charging port. Background task automatically catches and eats Pokémon A reference to Pokémon Go , an augmented reality game where the goal is to go to specific locations and play a mini-game in order to catch virtual creatures called Pokémon (see 1705: Pokémon Go ). This phone apparently catches Pokémon automatically, similar to the external device Pokémon Go Plus . However, this feature also eats them, which is something that is not part of the game and wouldn't be desirable, as it is about collection and storing as many different Pokémon as possible. It could be a coincidence, but it seems funny that the label for this background feature is the only one that points at the back of the phone. Supercuts partnership Trims hair fed into charging port Supercuts is an American hair salon chain that provides hair cuts and styling. The implication here is that the user can get a haircut by Supercuts by sticking hair into the charging slot. This is not only impractical and would only work for hair long enough to be fed into the port, but it would most likely result in a bad haircut. Also the slot would soon be filled with hair. The charging slot is otherwise placed in the normal spot and looks like a regular charging port. This feature could actually be quite dangerous if the hair is not removed from the charging slot afterwards because the hair could melt or catch fire inside the phone. Squelch knob Squelch is a feature of radios (CB, ham, scanner, etc) which quiets background noise when no usable signal is present. It cuts off audio completely when only noise is present. As different environments can have differing levels of background noise, an adjusment such as a knob is required to set the level at which the squelch circuit deactivates and lets audio through ("opening" or "breaking" the squelch). This feature already exists in audio call software but hardwiring it to a knob on the outside of the phone is probably excessive. For a smartphone, perhaps this knob could control the "signal-to-noise" ratio of your Facebook feed or other social media platforms. It takes the place of the headphone jack, replacing the normal hole with a small knob. IBM buckling-spring Home button IBM buckling-spring keyboards are favorites of geeks for the feeling of quality and auditory feedback (keys click loudly when pressed) they provide. Real smartphones' home buttons, typically located exactly as in this image, provide little to no such satisfaction when pressed. Cot-caught merger switch This is a reference to the cot–caught merger , a linguistic change happening among English speakers, particularly in some parts of North America and the British Isles, which causes caught (previously pronounced "kawt") to be pronounced the same as cot (pronounced "kot"). The switch is clearly visible on the side of the phone. A real feature physically similar to this is the slide switch on the iPhone and iPad, allowing the user to (un)lock the orientation of the screen or to (un)mute the device. 60x optical zoom camera A powerful optical zoom lens is usually a desirable feature for cameras. However, as shown in the comic, it results in very bulky lens. If 60× zoom should be achieved the lens needs to be as big as shown on the backside of the phone, and the whole idea of being able to carry the smartphone easily in a pocket would be defied. For that reason, such lenses are never used in smartphones, although rarely some devices, like the Samsung Galaxy Camera , use a smaller lens with a similar design. But this is no longer a smartphone. This feature would seem to be a jab at the variety of add-on devices, including close-up lenses, handles, and external flashes, that are currently in use to enhance the phone's ability to function like a camera (and the selfie stick ). Some phones might instead mention their digital zoom level instead. But that is not a popular feature among photo enthusiasts, as digital zooming gains no additional optical resolution. Users would actually be better off using the maximum optical zoom, and then enlarging their images with photo-editing software, which might offer better, but slower, algorithms (e.g. linear resampling versus Lanczos resampling ). Likewise, (mobile phone) cameras are often advertised with their high number of megapixels , while retaining their small image sensor size . As each individual sensor gets less light, it creates more image noise . Randall has made several comics about cameras before; see for instance 1719: Superzoom and other comics linked via this. Contrast the EasyMacro band - 4x zoom with little appreciable thickness. Assuming 60x is referring to the base focal length of the iPhone and that the xkcd Phone 5 has the same dimensions as the iPhone 7 Plus then in 35mm format this lens would be 30-1800mm f/0.4-f/24. This is a completely infeasible (but not physically impossible) lens in 35mm format, but similar small format lenses (albeit with more reasonable aperture ranges) do exist in mass production, for example the Nikon P900. LORAN navigation LORAN (Long Range Navigation) was a precursor to modern GPS navigation, using land-based transmitters. Once developed for sea shipping, it is accurate to about 300 meters (1,000 feet). The joke, of course, is that all modern smartphones have integrated GPS navigation which is far more accurate. Due to the much lower frequencies involved, reception of LORAN signals though is much better in areas with obstructed view of the sky. However LORAN has been decommissioned more or less completely since before 2000. Incidentally, some receivers of the Decca Navigator System (which operates on a similar principle as LORAN) featured moving map displays, something we associate with modern GPS devices. 28-factor authentication An authentication factor is a way of proving one's identity. There are 3 generally recognized forms : something you know, something you have, and something you are. It can be a password, a fingerprint, a physical key, etc.... Secure applications may include two or more factors; a common example is the "PIN and chip" system used with credit cards, where you need both the card and secret code to authorize a transaction. Many online services now provide two-factor authentication to protect against password-based attacks. 28-factor authentication would likely be very secure in theory but also so impractical that it would be unusable. The user will need to prove their identity 28 different ways which would be so time consuming that would outweigh the convenience of a smart phone. A 2-factor smoke detector was soon after mentioned in one of the tips in 1820: Security Advice . [An image of a smartphone with a common optical camera lens attached on its back is shown. Over the entire length the case is slightly rounded. There are several features visible as bottom like features at the top and bottom of the front as well a microphone like slit at the top. A sliding switch is visible on the side, and at the bottom there is a knob, a connector port and a small slit. Clockwise starting from the top left all the labels read:] Hook shot Bluetooth speaker Stained-glass display Gallium chassis remains solid up to 85°F Soundproof Can feel pain E-ZPass partnership: Phone can be dropped into coin basket to pay tolls Foldable (once) Screen transfers images to skin Retina storage Background task automatically catches and eats Pokémon Supercuts partnership: Trims hair fed into charging port Squelch knob IBM buckling-spring home button Cot-caught merger switch 60x optical zoom camera LORAN navigation 28-factor authentication [Below the phone:] Introducing The xkcd Phone 5 We're trying to catch up to Apple but refuse to skip numbers ®TM

Chat Systems

Chat Systems

https://www.xkcd.com/1810

https://www.explainxkcd.com/wiki/index.php/1810:_Chat_Systems

[An Euler diagram with many circle like drawings for various chat systems is shown. Some circles overlapping others in complicated ways, others are single circles with no connections, but most are embedded into others. Inside the circles mainly the standard sticky figures like Cueball, Megan, Ponytail and Hairy are shown but there are also a few others.] [The list of items and its intersections from left top to right bottom is:] Skype - none, Email Email - none, Skype, SMS, Slack, Hangouts, IRC, ICQ, iMessage, Signal, WhatsApp, Zephyr, FB Messenger, Instagram DM, BBM, Telegram, Twitter DM SMS - none, Email, Slack, Hangouts, IRC, Snapchat, iMessage, Signal, WeChat, WhatsApp, Zephyr, FB Messenger, Instagram DM, Peach, BBM, Twitter DM AIM - none Slack - Email, SMS, Hangouts, IRC, Signal Hangouts - Email, SMS, Slack, IRC, Signal IRC - Email, SMS, Slack, Hangouts, Signal Snapchat - SMS ICQ - Email iMessage - Email, SMS, Signal, FB Messenger Signal - Email, SMS, Slack, Hangouts, IRC, iMessage, Zephyr, Instagram DM WeChat - SMS WhatsApp - Email, SMS Zephyr - Email, SMS, Signal FB Messenger - Email, SMS, iMessage Instagram DM - Email, SMS, Signal Peach - SMS BBM - Email, SMS Telegram - none, Email Twitter DM - none, Email, SMS The "chat" tab in an old Google Doc - none Apache Request Log - none Wall (Unix) - none Wall (bathroom) - none [Caption below the panel:] I have a hard time keeping track of which contacts use which chat systems.

The comic consists of an Euler diagram showing a wide variety of chat systems and their intersections. (Euler diagrams should not be confused with Venn diagrams , see more on this here ). The comic demonstrates the complexity that can be involved in modern communications: simply remembering how to get in touch with someone can be a challenge. Below is a table with explanation for all 24 mentioned chat systems and below that a list of each system's intersections with the other systems. Several of the systems are already considered old, like The "chat" tab in an old Google Doc , but some people keep using them, which is part of the joke. There only seems to be one "chat" system which could in no way be said to be an on-line chat system, and that is the Wall (bathroom) at the bottom, which refers to how people writes notes on public bathroom walls, making it an extra joke and possibly a reference to 229: Graffiti . In the title text, Randall explains how he is one of the only few Instagram users to use the UNIX 'talk' gateway (an old peer-to-peer chat system whereby users logged into the same UNIX system could privately communicate with each other in a full-screen interface.) But he doesn't tell how he had enhanced this old fashioned software. Note that this is similar to the earlier 949: File Transfer . The 24 chat systems with the number of stick figures inside are listed. Notice there are only 23 real systems, as one of the systems is a bathroom wall. [An Euler diagram with many circle like drawings for various chat systems is shown. Some circles overlapping others in complicated ways, others are single circles with no connections, but most are embedded into others. Inside the circles mainly the standard sticky figures like Cueball, Megan, Ponytail and Hairy are shown but there are also a few others.] [The list of items and its intersections from left top to right bottom is:] Skype - none, Email Email - none, Skype, SMS, Slack, Hangouts, IRC, ICQ, iMessage, Signal, WhatsApp, Zephyr, FB Messenger, Instagram DM, BBM, Telegram, Twitter DM SMS - none, Email, Slack, Hangouts, IRC, Snapchat, iMessage, Signal, WeChat, WhatsApp, Zephyr, FB Messenger, Instagram DM, Peach, BBM, Twitter DM AIM - none Slack - Email, SMS, Hangouts, IRC, Signal Hangouts - Email, SMS, Slack, IRC, Signal IRC - Email, SMS, Slack, Hangouts, Signal Snapchat - SMS ICQ - Email iMessage - Email, SMS, Signal, FB Messenger Signal - Email, SMS, Slack, Hangouts, IRC, iMessage, Zephyr, Instagram DM WeChat - SMS WhatsApp - Email, SMS Zephyr - Email, SMS, Signal FB Messenger - Email, SMS, iMessage Instagram DM - Email, SMS, Signal Peach - SMS BBM - Email, SMS Telegram - none, Email Twitter DM - none, Email, SMS The "chat" tab in an old Google Doc - none Apache Request Log - none Wall (Unix) - none Wall (bathroom) - none [Caption below the panel:] I have a hard time keeping track of which contacts use which chat systems.

Best-Tasting Colors

Best-Tasting Colors

https://www.xkcd.com/1811

https://www.explainxkcd.com/wiki/index.php/1811:_Best-Tasting_Colors

[Caption above the chart:] Best-Tasting Colors [Below the caption there is a scale with two large ticks (with labels written above) at either end and seven smaller ticks in between for nine ticks in total. The labels:] Bad Good [Below the scale to the left is a numbered list of ten colors. Black double arrows goes under the scale. On the arrows there are labeled points, but there is also questions marks and other exceptions where text is not pointing to a point. Labels appear both above and below the arrows, but here the text is listed as it appears on the scale from left (bad) to right (good):] 1. Pink - Watermelon, ???, Cotton candy 2. Red - Raspberry, Cherry, Strawberry 3. Blue - ???, Blue raspberry, ??? 4. Green - Lime, Mint, Pistachio??, Watermelon, Green apple 5. White - ???, White chocolate, ???, Vanilla, ??? 6. Brown - Coffee, Caramel ? [However you feel about chocolate] ? 7. Orange - Orange, Creamsicle 8. Yellow - Popcorn?!, Lemon 9. Purple - Grape 10. Black - Licorice

In this comic, Randall rates colors based on tastiness of various flavors, which makes it very similar to 388: Fuck Grapefruit . The colors are sorted in descending order (from most tasty to least tasty) by the midpoint of their overall taste range. Within each color, several individual items are placed at points marked by dots along a tastiness scale, with nine ticks ranging from bad (1) to good (9). For example, within the pink color band at the very top, watermelon is only rated 6/9 — much less tasty than cotton candy, which is almost at 9/9, making it the very best tasting flavor in the chart. Interestingly, watermelon is mentioned twice, as it is also listed under green. Usually people do not eat the green part of a watermelon, so it is strange that Randall has rated both types at almost the same level of tastiness. It could be that he sees the green watermelon as green, but also sees the pink fruit inside, so it is actually the pink fruit that is rated for both colors, or the chart is a rating of candy (such as jellybean or popsicle) flavors, as it is not uncommon for both green and pink to represent watermelon in those situations. For pink, blue and white there are one, two and three regions, respectively labeled with "???". It is not clear what the purpose of these is. Perhaps they indicate regions in which Randall is unable to think of any examples, and is inviting the reader to speculate. For instance, are there any pink-colored foods more tasty than watermelon (6/9) but less tasty than cotton candy (8.5/9)? It could also be that he thinks there must be other interesting foods with this color, which could seem to be the case for white and blue, where there are a group of question marks above the most tasty labeled flavor blue raspberries and vanilla for white. The latter is yet a joke, as vanilla is black, but is often used in white food such as vanilla ice, which he may have been thinking off, or just again messes with his readers. The question marks thus imply an arbitrary tastiness assigned to a color that is not derived from an actual data point, however. For instance, the only blue datapoint is "blue raspberry", assigned a ranking of 5.5. But the range assigned to blue as a whole is 4 to 8. The regions on either side of the blue raspberry dot are labeled with ???. There are a few exceptions with chocolate the most obvious as Randall makes a wide range for chocolate for brown, ranging from 2.5-9.5 out of 9. And the arrows here ends in single question marks indicating that the range could be even longer. In the title text he acknowledges the fact chocolate is its own thing and that regarding its taste reasonable people may differ in opinion. The region for chocolate could not go further down because below the section for chocolate for brown food, there is another range with some other brown food items that Randall really does not like, caramel and especially coffee at 1.5/9. It may seem that Randall has never grown up to drink the drinks that society often dictates that you should drink. Not drinking Coffee (or hating it when you do) can be a problem with all the coffee breaks and meetings held over coffee etc. And as Randall has shown in 1534: Beer he also doesn't like beer... Although it is not so clear as with chocolate pistachio is also split up with three lines indicating a range on the green from about 5 to 7 without any assigned point to their taste. And finally popcorn at 1.5/9 simply falls below the otherwise already low and slim rating range for yellow foods (2.5-3.5) with only lemon at 3/9 included. Many people love popcorn, but not especially for the corns actual taste, which is non existing if not for the adding of salt or sugar or other additives. The worst taste by far to Randall, though, is licorice, and black food has a very small range from almost below 1 to less than 1.5. In USA it seems few people like licorice (although as most of the other mentioned food items, it may come in a wide variety of flavors and strengths). But in for instance northern Europe (Scandinavia) many people love it. See more explanations for all the mentioned flavors in the table below. It also seems that Randall's taste has changed over the nine years since the grapefruit comic. In the title text, Randall asserts that his rankings of colors and flavors are indisputable (with the exception of chocolate). This together with rather obscure flavors included ("blue raspberry", "creamsicle") rather than more obvious choices, such as banana for yellow and carrot for orange could be a jab at the reception of his first food ranking comic, 388: Fuck Grapefruit which ranked fruits based on their tastiness and ease of consumption. Randall claims that it is the most controversial piece he has ever published. So all this is maybe just a way to generate even more controversy about this comic, and based on the discussion below he may have succeeded. In 882: Significant researchers were studying the effect of eating 20 differently colored types of jelly beans (and all colors here are included except white). [Caption above the chart:] Best-Tasting Colors [Below the caption there is a scale with two large ticks (with labels written above) at either end and seven smaller ticks in between for nine ticks in total. The labels:] Bad Good [Below the scale to the left is a numbered list of ten colors. Black double arrows goes under the scale. On the arrows there are labeled points, but there is also questions marks and other exceptions where text is not pointing to a point. Labels appear both above and below the arrows, but here the text is listed as it appears on the scale from left (bad) to right (good):] 1. Pink - Watermelon, ???, Cotton candy 2. Red - Raspberry, Cherry, Strawberry 3. Blue - ???, Blue raspberry, ??? 4. Green - Lime, Mint, Pistachio??, Watermelon, Green apple 5. White - ???, White chocolate, ???, Vanilla, ??? 6. Brown - Coffee, Caramel ? [However you feel about chocolate] ? 7. Orange - Orange, Creamsicle 8. Yellow - Popcorn?!, Lemon 9. Purple - Grape 10. Black - Licorice

Onboarding

Onboarding

https://www.xkcd.com/1812

https://www.explainxkcd.com/wiki/index.php/1812:_Onboarding

[Beret Guy shakes hands with Ponytail in front of a building while he points at the two large double doors under an unreadable sign.] Beret Guy: Hi! Welcome to the team! Beret Guy: We do business here and we'll turn into dirt later. [Beret Guy and Ponytail walk by three bikes.] Beret Guy: This is our main campus. Beret Guy: We have a free bikeshare system, at least until whoever owns those bikes finds out. [Beret Guy points forward as they walk on.] Beret Guy: The LaserJet is over there, and the printer is over there. Beret Guy: You can't use it right now; it's been printing an infinite-scroll webpage since 2013. [Zoom in on their heads.] Beret Guy: Restrooms are all-digital - no pipes. Beret Guy: The WiFi is very fast, but cursed. Beret Guy: Our server room is carbon-neutral but produces bismuth constantly. [Beret Guy has turned towards an off-panel Ponytail holding a hand out towards her.] Beret Guy: You'll be working on our infrastructure, which is currently maintained by Lin-Manuel Miranda. [Zoom out to both facing each other. From the right singing is heard from off-panel, as indicated with two musical notes.] Ponytail: ...The songwriter? Is he also an engineer? Beret Guy: Nope, huge misunderstanding on our part. Cost a fortune. But he's really nice and it makes karaoke nights fun. Lin-Manuel Miranda (off-panel): How far I'll gooo

This is another one of Beret Guy's mysterious businesses , in which he shows new employee Ponytail around the building in which the company resides. The process of showing a new employee around the business and starting to get them introduced to people and systems and procedures is often referred to as " onboarding " - hence the title of the comic. The first panel starts out as a typical welcoming of the new employee to a small indie business. Very quickly, however, Beret Guy's explanation jumps to an existential viewpoint. Very rarely do conversations or introductions involve discussing the eventual fate of our bodies, and certainly not in a professional light as in this comic. Beret Guy, however, has no problem with discussing death and decay as just part of his business. This seemingly contradicts the title text in 1493: Meeting , where it is claimed that employees of the company can not physically die. However, this could be a new company he has started since then. Alternatively, this is a literal statement, perhaps related to the cursed Wi-Fi mentioned later in the comic. In the second panel, Beret Guy shows Ponytail the free bikeshare system this business apparently has in place. Bikesharing is a system in which many users share one or more bikes among themselves. Typically the bikes belong to some of the members of the group who are allowing them to be used by other members who may not have one, but Beret Guy calmly remarks that this system will only exist "until whoever owns those bikes finds out", implying that they were not donated or shared by any member of the group, but are being used without permission or the knowledge of the true owner of the bikes. This is, thus, not actually a bikeshare, and would be more properly described as theft. In the third panel, Beret Guy shows Ponytail that the laserjet is over there and the printer is over there, thus indicating that the laserjet is not a printer. This is a bit disconcerting, since the HP LaserJet is in fact a common brand of laser printer , suggesting that his laserjet may be some rather more exotic device, such as a laser-propelled jet aircraft . In any case, however, the printer is not available, as it's been printing an infinite-scroll web page since 2013. An infinite-scrolling web page is a web page that, as the name implies, seems to have no end. This style of webpage typically has no definite pages or sections, but instead continues to feed data to the screen as the user scrolls. In reality, trying to print one of these would only print the current section the user was viewing, and even if it was somehow able to infinitely print, the operator could theoretically cancel the operation at any time. Presumably, this continuous printing serves some useful purpose, e.g. prints latest news, because someone would have to be refilling the paper for the printer to have kept running this long; it would have run out of paper long ago otherwise. Mistaken print jobs are sometimes notoriously difficult to stop due to many levels of buffering (application, printer driver, OS spooler, print server, printer device) and lapses in job control software. Infinite scrolling (in the sense of an annoying UI design style for browsing large but finite documents) was previously covered in 1309: Infinite Scrolling . A similar separation of the phrase "laserjet printer" has been explored in 1681: Laser Products . In the fourth panel, Beret Guy makes three more remarks. Restrooms are all-digital—no pipes. While many technology standards nowadays are entirely digital, one's restroom is one of the things that most definitely should not be. A restroom without pipes would have no way to bring water in and transfer wastes away, and would most certainly be at the very least an unpleasant encounter. (It's implied that the waste is being transferred digitally, although this is obviously impossible .) This could also be a pun joking with the fact that a common (in the past and reappearing recently) technology in sound amplifiers is the use of tubes, but nowadays most sound amplifiers are all-digital. So a "latest technology" restroom cannot have pipes (synonym of tubes) and has to be all-digital. The Wi-Fi is very fast, but cursed. Fast Wi-Fi is certainly desirable, but in this case, he claims it is also cursed. Whether the curse is a side-effect of the fast Wi-Fi or totally unrelated is left unsaid, as well as what the curse is. This could possibly be a joke relating to American slang: all technology can behave inexplicably from time to time, and Wi-Fi is notorious for randomly losing connection -- this is often exaggerated and called "cursed". Knowing Beret Guy, though, it's probably literal , perhaps purchased from one of the " mysterious shops that sell you magical items, and then it turns out they're cursed" . Our server room is carbon-neutral but produces bismuth constantly. Normally, carbon-neutral would mean that it is designed to be environmentally friendly by reducing and offsetting its carbon emissions enough that it has no net effect on the environment. The term is a little bit confusing because the meaning is of course carbon-dioxide-neutral. But while carbon is not a common material used in servers, bismuth is used as lead replacement in some solders . While this replacement is often used because of the toxicity of lead , in this case it refers to an IBM mainframe computer where the Bi 58 Sn 42 alloy is used because of its low temperature soldering characteristics. So producing bismuth would destroy all the electric connections in the server. An alternative explanation is a compact nuclear reactor in the server room which can both make the server room carbon-neutral and leak bismuth (by creating it in the reactor). In the last two panels, Beret Guy explains that Ponytail will be working on the infrastructure, which is apparently maintained by Lin-Manuel Miranda . He is among other things a songwriter but certainly not an engineer or anyone qualified to be responsible for an entire infrastructure. Ponytail knows about his songs and thus surprised asks if he is also an engineer. (This echoes 1665: City Talk Pages , which includes a train station designed by Andrew Lloyd Webber , a composer best known for writing The Phantom of the Opera ). It is worth noting that Beret Guy actually acknowledges the mistake here, claiming the mistake "cost a fortune." This is unusual for Beret Guy, as he has of yet failed to acknowledge or recognize the oddity of every other aspect of his mysterious business, many of which are certainly stranger than this. However, he doesn't seem to mind this at all and does not wish to fire him. Instead he plans on fixing the mistake by hiring a real network engineer, Ponytail, to do the work alongside Miranda. Because, as Beret Guy continues to explain, the bright side of having Lin-Manuel Miranda in his business overshadows the lost fortune. Apparently Lin-Manuel Miranda is really nice and he makes karaoke nights fun, a clear reference to his engaging stage presence and vocal skills. Off screen, Lin-Manuel Miranda is heard singing " How Far I'll Go ", which is a song that he composed for the Disney movie Moana . It was nominated for an Oscar for Best Original Song in the 2017 show just a few weeks prior to this comic. The title text mentions the potential dangers of having your server room constantly produce bismuth, but only as a prelude to a bismuth/business pun. Because of the earlier carbon reference, it could also be a parallel to the difficulty in convincing businesses to become more energy efficient and reduce greenhouse gas emissions despite the urgency, as Randall has often referred to in xkcd with 1732: Earth Temperature Timeline . [Beret Guy shakes hands with Ponytail in front of a building while he points at the two large double doors under an unreadable sign.] Beret Guy: Hi! Welcome to the team! Beret Guy: We do business here and we'll turn into dirt later. [Beret Guy and Ponytail walk by three bikes.] Beret Guy: This is our main campus. Beret Guy: We have a free bikeshare system, at least until whoever owns those bikes finds out. [Beret Guy points forward as they walk on.] Beret Guy: The LaserJet is over there, and the printer is over there. Beret Guy: You can't use it right now; it's been printing an infinite-scroll webpage since 2013. [Zoom in on their heads.] Beret Guy: Restrooms are all-digital - no pipes. Beret Guy: The WiFi is very fast, but cursed. Beret Guy: Our server room is carbon-neutral but produces bismuth constantly. [Beret Guy has turned towards an off-panel Ponytail holding a hand out towards her.] Beret Guy: You'll be working on our infrastructure, which is currently maintained by Lin-Manuel Miranda. [Zoom out to both facing each other. From the right singing is heard from off-panel, as indicated with two musical notes.] Ponytail: ...The songwriter? Is he also an engineer? Beret Guy: Nope, huge misunderstanding on our part. Cost a fortune. But he's really nice and it makes karaoke nights fun. Lin-Manuel Miranda (off-panel): How far I'll gooo

Vomiting Emoji

Vomiting Emoji

https://www.xkcd.com/1813

https://www.explainxkcd.com/wiki/index.php/1813:_Vomiting_Emoji

[Cueball, looking at his smartphone, approaches Megan who is sitting in an office chair at a desk working on her laptop. Next to Megan's reply is a large yellow faced emjoi with closed eyes and a large open mouth from where a thick green stream of vomit is gushing out. ] Cueball: The proposed emoji for Unicode 10.0 look good. Megan: Hmm. Megan: "U+1F92E Face with open mouth vomiting" [Cueball is holding his phone down looking at Megan's screen.] Cueball: Eww. Megan: Really, "vomiting" should be a combining modifier, so you can use it to make a vomiting version of any emoji. Cueball: Umm. Megan: I'm gonna write up a proposal. [Megan's proposal with six examples of vomiting emoji. All six are colorful also apart from the green stream of vomit gushing out of mouth or holes when there is no mouth. Above the list is Megan's suggested title for the modifier, and the title for each emoji is next to them in the list. The cowboy is like the original version but with a hat. The Statue of Liberty is blue and bends forward to vomit. The gray dove has lost its green olive branch, now above its head. The yellow moon is in first quarter and has a face. The red and blue rocket has fire out the rear and the vomit out an open hatch. The yellow hand has a big hole in its center.] U+1F93F Vomiting modifier U+1F920 U+1F93F Vomiting cowboy U+1F5FD U+1F93F Vomiting Statue of Liberty U+1F54A U+1F93F Vomiting dove U+1F31B U+1F93F Vomiting moon U+1F680 U+1F93F Vomiting rocket ship U+270B U+1F93F Vomiting hand Two years after this comic was published, in 2019, Unicode added U+1F93F in Unicode 12.0 and Emoji 12.0, but instead used the code for a diving mask emoji .

This comic relates to the recent Emoji v5.0 proposal for Unicode 10.0 which includes a vomiting emoji . Cueball initially states that the newly proposed emoji look good, until Megan points out the existence of the vomiting emoji. While Cueball finds this distasteful, Megan rather seems to like it, going as far as suggesting rather than a single emoji, it should be possible to have a whole array of vomiting emojis by combining the vomiting action with other existing emojis. Note: Some of the emojis below may not display correctly if your browser or operating system doesn't implement the latest Unicode standard. Unicode is the computing industry standard for representing text. More recent additions have included emoji characters, such as grinning face (😁) or hands clapping (👏). Each Unicode character is assigned a numerical code, usually written in hexadecimal notation. For example, the grinning face emoji is assigned the code U+1F601, and the clap symbol is assigned U+1F44F. Unicode also supports "combining modifiers" which allow, among other uses, placing accents on letters, adding decorations to other emojis, or changing the colors of flags or skin tones. For example, letters such as A, O, or n together with a combining tilde (U+303) modifier result in those letters having a tilde glyph on top (Ã, Õ, ñ), and various emojis for people, such as 👨 or 👩, together with the medium-dark skin tone modifier (U+1F3FE), results in those same people with altered skin color (👨🏾, 👩🏾). Along the same lines, Megan's proposal is to assign the code U+1F93F to be a combining modifier indicating vomiting. Under this proposal, it would theoretically be possible to combine a vomiting modifier with any emoji to produce a vomiting version of that emoji. Six examples are given in the last panel, with each being progressively more nonsensical. The title text continues this and gives another example of a ridiculous combination. The examples given in the comic are: Most of these Emoji could be seen as related to the political situation in the USA at the moment, see more here . Assigning Unicode characters to emojis has been controversial historically due to the fact that Unicode was created as a standard for text. Emojis, which are essentially drawings of people or objects, aren't typically perceived as parts of text, and so leads some to object to co-opting the standard for non-text things. Using combining modifiers to further expand emojis is also seen as an abuse of the original purpose of modifier characters. As an alternative, emoji zero-width joiner sequences are in use, where an emoji is encoded as a series of simpler emoji and zero-width joiners. In practice, this would probably be how the above characters would be implemented, instead of with a combining modifier. Jokes that make fun of Unicode, involving emojis that shouldn't exist or inappropriate combinations thereof, are fairly common on the Internet. In the title text of 1726: Unicode , Randall mentioned the proposed " brontosaurus " emoji in Unicode. And shortly before that Megan talked in similarly drawn emojis in 1709: Inflection . In general emoji has become a recurrent topic on xkcd. [Cueball, looking at his smartphone, approaches Megan who is sitting in an office chair at a desk working on her laptop. Next to Megan's reply is a large yellow faced emjoi with closed eyes and a large open mouth from where a thick green stream of vomit is gushing out. ] Cueball: The proposed emoji for Unicode 10.0 look good. Megan: Hmm. Megan: "U+1F92E Face with open mouth vomiting" [Cueball is holding his phone down looking at Megan's screen.] Cueball: Eww. Megan: Really, "vomiting" should be a combining modifier, so you can use it to make a vomiting version of any emoji. Cueball: Umm. Megan: I'm gonna write up a proposal. [Megan's proposal with six examples of vomiting emoji. All six are colorful also apart from the green stream of vomit gushing out of mouth or holes when there is no mouth. Above the list is Megan's suggested title for the modifier, and the title for each emoji is next to them in the list. The cowboy is like the original version but with a hat. The Statue of Liberty is blue and bends forward to vomit. The gray dove has lost its green olive branch, now above its head. The yellow moon is in first quarter and has a face. The red and blue rocket has fire out the rear and the vomit out an open hatch. The yellow hand has a big hole in its center.] U+1F93F Vomiting modifier U+1F920 U+1F93F Vomiting cowboy U+1F5FD U+1F93F Vomiting Statue of Liberty U+1F54A U+1F93F Vomiting dove U+1F31B U+1F93F Vomiting moon U+1F680 U+1F93F Vomiting rocket ship U+270B U+1F93F Vomiting hand Two years after this comic was published, in 2019, Unicode added U+1F93F in Unicode 12.0 and Emoji 12.0, but instead used the code for a diving mask emoji .

Color Pattern

Color Pattern

https://www.xkcd.com/1814

https://www.explainxkcd.com/wiki/index.php/1814:_Color_Pattern

[Cueball holds up his smartphone in front of his laptop which stands in front of him on a desk. Megan is sitting in an armchair reading, facing away from Cueball. She is singing her reply, as indicated with four double musical notes around her two lines of text.] Cueball: I took a picture of my computer screen—why is the photo covered in these weird rainbow patterns? Megan: When a grid's misaligned with another behind Megan: That's a moiré...

The comic references moiré patterns in a parody of the song “ That's Amore ” made famous by Dean Martin in 1953 . (See trivia for pronunciation). In mathematics, physics, and art, moiré patterns or moiré fringes are a kind of aliasing -- large scale interference patterns that can be produced when an opaque ruled pattern with transparent gaps is overlaid on another similar pattern. For the moiré interference pattern to appear, the two patterns must not be completely identical in that they must be displaced, rotated, etc., or have different but similar pitch. Moiré patterns appear in many different situations. In printing, the printed pattern of dots can negatively interfere with the image. In television and digital photography, a pattern on an object being photographed can interfere with the shape of the light sensors to generate unwanted artifacts . In digital photography or videography, moiré patterns occur when the pattern of pixels on the image sensor are not 100% identically aligned with patterns on the subject being photographed. Photographs of a digital screen taken with a digital camera often exhibit moiré patterns, since it is very difficult to align the camera sensor's grid with the screen's pixel grid perfectly. This is the problem Cueball ran into, where the photo he just took of his computer screen is covered in weird rainbow patterns (the color patterns from the title). It is possible to reduce this effect by changing the distance and angle between the camera and the screen. There can also be bands of uneven brightness on digital photos or videos of electronic displays, those are caused by scan lines and are different from the moiré patterns described in this comic. Megan responds to Cueball's complaint with a song that explains moiré patterns. Her song is a parody of the song That's Amore , where "Amore" means "love" in Italian. The pun is that "That's a Moiré" and "That's Amore" are phonetically quite similar . The title text continues the song with a second verse, again with musical notes indicating that it should be sung. More information on when moiré patterns occur is given here, indicating that the space between the grid lines should be small and the two grids should be almost identical, for the maximum moiré effect. This verse, however, could also work if a moiré was changed to amore , as two people squeezed tight together, and without much difference between them could lead to a romantic relationship. Randall was not the first to spoof this song using "a moiré" instead of "Amore". His two verse version, two verses from the original song, and other prior versions can be found below . It is the second time that Randall has changed the lyrics to "That’s Amore", although the first time, in 321: Thighs , he only changed eye to thigh in the original versions first verse. It turns out that Randall was not the first to spot the possibility of changing the lyrics from "That’s Amore" to "That's a Moiré." Verses are shown below as follows: the lyrics first to the original song, then to Randall's song from this comic, and below that other songs (with citations). The two first verse in the original song : When a moon hits your eye like a big pizza pie That's amore When the world seems to shine like you've had too much wine That's amore The entire version of Megan's ( Randall's ) song is: When a grid's misaligned with another behind That's a moiré... When the spacing is tight And the difference is slight That's a moiré A similar song based on the same pun was made by Craig Swanson in 1993 and can be found on his web comic Perspicuity in this comic: That's a Moiré . His song text was: When new lines hit your eyes From two screens when they ply That's a Moire! Jamie Zawinski and Michael Bayne wrote a similar verse for the Moiré screensaver they made in 1997 (search for that's to find it on the linked page): When the lines on the screen Make more lines in between, That's a moiré! [Cueball holds up his smartphone in front of his laptop which stands in front of him on a desk. Megan is sitting in an armchair reading, facing away from Cueball. She is singing her reply, as indicated with four double musical notes around her two lines of text.] Cueball: I took a picture of my computer screen—why is the photo covered in these weird rainbow patterns? Megan: When a grid's misaligned with another behind Megan: That's a moiré...

Flag

Flag

https://www.xkcd.com/1815

https://www.explainxkcd.com/wiki/index.php/1815:_Flag

[A three-colored flag is shown, divided in vertical thirds. The left and rightmost parts of the flag are dark blue, and the center is red and each section has a large white star in its center. Neighboring thirds are separated by a thinner white vertical stripe. At the top of the flag, there is an off-white status bar like one found at the top of an iOS smart device. On the left it is displaying the strength of the connection (3/5 dots), in the center it is displaying the time and on the right there are three small icons the last is the battery charge:] 3G 5:48 PM 39% [Below the panel there are two captions] The design committee fired me once they realized that my editing process involved a screenshot, but it was too late. Until they change it, our new country has the only national flag to include a phone notification bar.

Presumably Randall was hired by a committee to propose a new flag for an unspecified country. His process of editing the flag involved taking a screenshot of his design to export it, a mistake that went unnoticed by anyone until the flag was officially implemented. Once the problem was pointed out, the design committee placed the blame on Randall, but could not immediately undo their decision until new suggestions had been submitted and a new committee could agree on another design. Thus the country is now stuck with this design, making it the only country with such a bar in the flag. The title text mentions a compromise bill that will change the flag. This implies that the flag was approved with the status bar included. Apparently, there is some controversy about removing the status bar from the flag, as the compromise bill proposes keeping the status bar and changing the displayed percentage of the battery from 39% to 100%. This may be wordplay on the term "charge" as used in vexillology , where it refers to a figure appearing on the background of the flag. It may also be a reference to 1373: Screenshot . The bar in notification bar , is a vexillological descriptor, as in the " Stars and Bars ," a term used for the first flag of the Confederate States of America , not to be confused with the counting technique. Flags are often minimalist and involve geometric shapes and solid colors. A notification bar at the top of the flag would clash with these design elements and look unprofessional. [ citation needed ] The flag in the comic is otherwise well-designed, conforming with a principle of heraldry and vexillology known as the rule of tincture : the "metals" consist of white/silver and yellow/gold, while the "colours" consist of red, blue, green, black, and purple; anything in the "metal" category should only be placed upon a background of the "colour" category and vice versa. The elements of the flag's intended design—the colors red, white, and blue; the use of stripes; and the star emblems—are the same that are used in the American flag the Stars and Stripes . The elements of this flag are, however, also present in several other existing flags, like those derived from Union Jack , the flag of the United Kingdom , and like the flags of Australia and New Zealand . They are also in the flags of North Korea , Liberia , and Malaysia . The flags from USA, Australia, Liberia and Chile have white stars , and those of USA and Liberia have white bars as well. The low battery status might imply that the country is low on resources. It thus seems like people have taken the reference to modern times smartphones to their hearts and actually wish to have this very modern design. But if they indeed continue with this idea, thinking that their country would look better with a full battery charge, they might also consider changing the 3G connection to the newer 4G or 5G version, according to what was available at that time in that location, and giving the phone a full signal (5/5 instead of only 3/5 dots). And maybe also choose a time that would mean something rather than 5:48 PM. For instance noon/midnight, or 8:00. The reason such a status bar could be missed in the first place could be that most people today look at pictures on their smartphones all the time, and thus their own phone's status bar is indirectly included at the top of all the pictures they see. People thus do not notice these status bars any longer as they are always there and clearly not important for the picture. Randall has mentioned before, in 1373: Screenshot , that he cannot take smartphone screenshots seriously if the battery of the device is low, as he cannot focus on the content, becoming afraid his own device is running out of power—a problem that only occurs if he sees it on his smartphone, as he then becomes concerned that it is his phone that is about to run out of charge. But in this status bar, there is still 39%, enough not to cause immediate concern. His fear of losing his on-line connection like this was the joke in the comic 1802: Phone released about a month before this one. Since Randall was asked to create this flag, it seems most likely that he would have to be a citizen of this new country. It could thus indicate that a group of states has broken free from the United States to form their own smaller union of three states, one for each star. With the current political situation in the states after Donald Trump’s inauguration there has been some talk about states leaving the USA, and Randall has clearly been against the election of Trump, see 1756: I'm With Her . His choice of comic subjects seems to have been affected by the election result. Since Randall lives in Massachusetts , it could be this and two other nearby states that have formed their own new union of states, maybe the other two small states Connecticut and Rhode Island . [A three-colored flag is shown, divided in vertical thirds. The left and rightmost parts of the flag are dark blue, and the center is red and each section has a large white star in its center. Neighboring thirds are separated by a thinner white vertical stripe. At the top of the flag, there is an off-white status bar like one found at the top of an iOS smart device. On the left it is displaying the strength of the connection (3/5 dots), in the center it is displaying the time and on the right there are three small icons the last is the battery charge:] 3G 5:48 PM 39% [Below the panel there are two captions] The design committee fired me once they realized that my editing process involved a screenshot, but it was too late. Until they change it, our new country has the only national flag to include a phone notification bar.

Mispronunciation

Mispronunciation

https://www.xkcd.com/1816

https://www.explainxkcd.com/wiki/index.php/1816:_Mispronunciation

[White Hat and Cueball are walking.] Cueball: I sometimes misspell "misspell" and "mispronunciation," and I mispronounce "mispronunciation," Cueball: But the epitome of mispronunciation is probably the way I pronounce "epitome."

This comic is a meta-joke where Cueball explains to White Hat which words he often spells or pronounces incorrectly. Ironically, those words happen to be words whose definitions mean "to spell incorrectly" and "being pronounced incorrectly". While describing the words he says he has trouble with, he manages to use the same words correctly in sentences both inside quotation marks (to refer to the word itself) and outside (to describe the action corresponding to those words). The word misspell is misspelled quite often (although not in this comic!). Misspell is quite commonly misspelled as mispell or miss-spell . Some might argue that misspelled is the one word which should always be misspelled intentionally and written mispelled , so that its orthography reflects its meaning. ("If it isn't mispelled, then it isn't mispelled !") The word mispronunciation is often misspelled and mispronounced like "mispronounciation", with the middle part like "noun" instead of "nun". This is made even more confusing by the fact that the related word, "pronounce", does in fact have "noun" in the middle. The punchline comes when Cueball tells that the epitome of mispronunciation is the way Cueball pronounces epitome . This is also metahumor, as epitome refers to a very good or perfect example. Thus Cueball shows the epitome of mispronunciation when he incorrectly pronounces epitome . The title text explains Cueball's mispronunciation of epitome. It is supposed to be pronounced in four syllables, /əˈpɪtəmi/ (uh-PIH-tuh-mee), starting with a schwa , then emphasis on the second syllable pronounced like "pit", and a long E on the fourth syllable pronounced like "me". Instead, he pronounces it /ˈɛpɪtoʊm/ (EPPY-tome), with emphasis on the first part pronounced like the beginning of "epic", and a silent E on the second part pronounced like "tome". The mispronounced version is what a person unfamiliar with the word might reasonably guess, given other words with similar spelling like "epicenter", "epitaph", and "episode". EpiPen , a trademark for a type of epinephrine autoinjector (i.e. adrenaline), is brought up to further illustrate the inconsistency between spelling and pronunciation. This time the word is supposed to be pronounced with an emphasized "EPPY", but he (intentionally?) mispronounces it like "uh-PIE", possibly to match other proper nouns such as Epirus and Epione . [White Hat and Cueball are walking.] Cueball: I sometimes misspell "misspell" and "mispronunciation," and I mispronounce "mispronunciation," Cueball: But the epitome of mispronunciation is probably the way I pronounce "epitome."

Incognito Mode

Incognito Mode

https://www.xkcd.com/1817

https://www.explainxkcd.com/wiki/index.php/1817:_Incognito_Mode

[A woman with long blonde hair (maybe a version of Blondie) holds both arms up as she addresses Cueball who is sitting in an office chair working on his laptop.] Woman: ...But remember—if you browse in incognito mode for more than two hours, you'll be trapped there forever! [Caption below the panel:] Animorphs tech tips

A woman (maybe a different version of Blondie , or Rachel from Animorphs) warns Cueball about not browsing for more than two hours in incognito mode as he might get stuck there forever. Incognito mode/private mode is a feature in a web browser that automatically clears any cookies and web history when the browser window is closed, but does not shield you from censorship, malware, or tracking . One could become metaphorically "trapped" in this mode if they don't want to lose this data (for example if they've found a useful page which they want to refer back to, or if they're on a website like YouTube which uses cookies to provide recommended videos and they're finding the recommendations interesting), meaning that they can never close the browser again. Presumably this is more likely to happen after a longer browsing session. The only option to keep browsing data when the incognito/private session is closed is to bookmark or write down the URLs of interesting pages; there is no way to keep the cookies, so things such as recommended YouTube videos from within the incognito browsing session will inevitably be lost when it is closed. As a side note, desktop users can use a browser extension to export the list of open tabs, but mobile browsers usually can not. However, mobile browsers might deny basic features such as saving pages and screenshots in incognito mode, making it unattractive to use. And currently, there is no way to back up cookies from incognito mode on either browser type. Animorphs is a book series by K. A. Applegate featuring several teenagers who have a special power: they can morph into various animals whose DNA they have absorbed through alien technology. However, if they stay morphed for over two hours, they will get stuck in that form until they die (this is presumably where the "two hours" in the comic comes from). In this comic Randall pokes fun at this by relating it to surfing in incognito mode/privacy mode in a browser. As explained above, staying for too long in incognito mode may cause the user to become "stuck" in this mode until something causes the browser to close, such as the browser/computer crashing or a power failure. This is analogous to the Animorphs who become stuck in animal form if they spend too long in that form. An alternative interpretation revolves around the use of incognito/private browsing modes when the user is paranoid. They may use this mode if, for example, they don't want the risk of anyone else discovering what they've been doing online, and they find it safer to simply use incognito mode rather than manually deleting the relevant cookies and browsing history afterwards. If they use this mode a lot, the sense of paranoia that initially led them to use incognito mode can reinforce itself, and over time they may become uncomfortable browsing outside of incognito mode. This is another way in which one may become "trapped" in incognito mode after extended use. The caption explains that tech tips from Animorphs are the worst, i.e. the woman is an Animorph, and this was not good advice. [ citation needed ] The title text continues the idea that an Animorph tech support team would be the worst possible explaining that their solutions are always the same. And then it gives an example which references a common occurrence in the Animorphs book series wherein the protagonists uses their ability to morph into animals to infiltrate enemy strongholds. In the example it is an update for Apple's OS X (a popular commercial operating system), that broke something. The solution is to infiltrate Apple by morphing apples. Morphing into fruits is nonsensical within the rules for morphing, put forth in the books, since the children can only turn into animals and not into fruits like apples. It would also be very ineffective, since fruits can't move on their own. Plus, Apple Inc. has little to do with actual apples, so this is not a good form to infiltrate their headquarters (morphing into bugs or even Apple's employees would be more effective, and is allowed by books' rules). Randall is not the first to propose morphing into vegetables as an Animorph's parody . Animorphs has been referenced before, first only in the title texts of 1187: Aspect Ratio and 1360: Old Files , and then later in the main comic in 1380: Manual for Civilization , with the books being the actual manual... [A woman with long blonde hair (maybe a version of Blondie) holds both arms up as she addresses Cueball who is sitting in an office chair working on his laptop.] Woman: ...But remember—if you browse in incognito mode for more than two hours, you'll be trapped there forever! [Caption below the panel:] Animorphs tech tips

Rayleigh Scattering

Rayleigh Scattering

https://www.xkcd.com/1818

https://www.explainxkcd.com/wiki/index.php/1818:_Rayleigh_Scattering

[Science Girl asks Blondie a question which she answers while lifting her arm towards Science Girl.] Science Girl: Why is the sky blue? Blondie: Because air is blue. [Megan walks in from behind Science Girl.] Megan: No, the sky is blue because of Rayleigh scattering– Blondie: Nah, it's because air is blue. Blue light bounces off it and hits our eyes. Same as why anything is any color. [Zoom in on Blondie's face.] Blondie: It's why far-off mountains look blue – because of all the blue air in the way. [Zoom out to Megan standing longer from Science Girl than Blondie who has thrown her arms out. Science Girl is facing directly out towards the reader.] Megan: There's a specific quantum mechanism by which– Blondie: Yeah but there's a physics mechanism for every color. You don't have to get all quantum right away. [Frameless panel with Science Girl looking up at Blondie who stands holding her hands on her sides. Megan speaks from off-panel.] Megan (off-panel): ...OK, I guess. Blondie: Any other questions? Science Girl: How do planes stay up? [Blondie holds a finger up in front of Science Girl while Megan now is the one to throw out her arms.] Megan: Well, the airflow– Blondie: Tiny birds in the wings. Thousands. Flapping hard. Science Girl: WOW! Megan: NO!

This comic suggests it is better to explain things in an easy-to-understand and intuitive manner, even if such explanations may not capture all of the scientific detail involved. This is especially the case for children whose ability to grasp abstract physics has not yet fully developed. Giving the most complete and physically accurate explanation would make the concepts much more elaborate than necessary, and would cause major confusion in inexperienced listeners. The principle is demonstrated by the explanation on why the sky is blue . The commonly given explanation for this is, as the comic title says, Rayleigh scattering . However, in order to understand how Rayleigh scattering works to produce a blue color, one must go into quantum mechanics and deal with properties of molecules in air and their effects on different wavelengths of light. Even then, one will also need to know about the inner workings of human visual perception to realize why the color we perceive isn't the wavelength that's being most strongly scattered (see 1145: Sky Color ). The child is not likely to understand this kind of explanation. On the other hand, a much simpler explanation, such as "because air is blue" — that is, air molecules reflect blue light, in the same way blue paint reflects blue light — also adequately explains the phenomenon, and is much more understandable to less physically inclined listeners. When Science Girl asks Blondie (possibly Miss Lenhart ) why the sky is blue, Megan walks in and starts to explain in a very scientific way involving quantum mechanics. This is criticized by Blondie, who then convinces her that the simpler explanation is sufficient, as there is a quantum mechanical explanation for every color, there is no need to elaborate on the sky's color any more than any other object's color. Megan implicitly accepts this, but then in the final panel, Science Girl asks another common question - how do planes fly? Megan starts again to give the traditional answer (airflow causing lift ) but is interrupted by Blondie saying that it's because the wings of an airplane are full of small birds. While this might not be as ridiculous as it first seems (the child might later learn that the "tiny birds" are actually air molecules, and "flapping wings" are actually pressure differentials), it is certainly over-simplified to a staggering extent. Thus Megan and Blondie illustrate the two extremes of education philosophy: where one chooses to teach the complete truth with no regard for whether it's understandable, the other chooses to make up understandable explanations with no regard for whether it's true. Arguably, neither approach is in the student's best interest and a balance needs to be achieved. When Science Girl reacts like she believes Blondie's last comment about the planes, she could almost have been called April Fool. Although this comic was released one day too early for that, this was also the only year between April 1st of 2011 and April 1st of 2018 where no such comic was released. See more about this in the trivia section below. The title text refers to another common question as for why leaves are green. This is commonly explained by the fact that they are filled with chlorophyll , a chemical used by plants for photosynthesis. Randall points out that it would be an equally valid question to ask why chlorophyll is green. This poses an interesting contrast to the answer to the question about the color of the sky, since even physicists are usually satisfied with the general explanation for leaves and don't feel the need to jump into describing quantum phenomena that cause chlorophyll to reflect green light. Also, "Why does chlorophyll scatter green light" may be a great question because chlorophyll reflects, not scatters, light and this challenges Megan-types to coherently explain the difference before they go challenging little children with pedantry. Or because green light is less efficient during photosynthesis, and explaining that is similar to explaining Rayleigh Scattering. What-if 141 also mentions the simpler explanation to the original question: Sunbeam has this relevant text: "Normal light interacts with the atmosphere through Rayleigh scattering. You may have heard of Rayleigh scattering as the answer to 'why is the sky blue.' This is sort of true, but honestly, a better answer to this question might be 'because air is blue.' Sure, it appears blue for a bunch of physics reasons, but everything appears the color it is for a bunch of physics reasons." There is also a footnote in that comment with an additional example: "When you ask, 'Why is the statue of liberty green?' the answer is something like, 'The outside of the statue is copper, so it used to be copper-colored. Over time, a layer of copper carbonate formed (through oxidation), and copper carbonate is green.' You don't say 'The statue is green because of frequency-specific absorption and scattering by surface molecules.' " Randall himself has published Thing Explainer which gives simplified descriptions of complex scientific and technological objects. Even in his book, some of the more advanced details have been simplified to a toy model (such as calling liquid oxygen "cold wet air" and a nuclear reactor "box of burning metal"). [Science Girl asks Blondie a question which she answers while lifting her arm towards Science Girl.] Science Girl: Why is the sky blue? Blondie: Because air is blue. [Megan walks in from behind Science Girl.] Megan: No, the sky is blue because of Rayleigh scattering– Blondie: Nah, it's because air is blue. Blue light bounces off it and hits our eyes. Same as why anything is any color. [Zoom in on Blondie's face.] Blondie: It's why far-off mountains look blue – because of all the blue air in the way. [Zoom out to Megan standing longer from Science Girl than Blondie who has thrown her arms out. Science Girl is facing directly out towards the reader.] Megan: There's a specific quantum mechanism by which– Blondie: Yeah but there's a physics mechanism for every color. You don't have to get all quantum right away. [Frameless panel with Science Girl looking up at Blondie who stands holding her hands on her sides. Megan speaks from off-panel.] Megan (off-panel): ...OK, I guess. Blondie: Any other questions? Science Girl: How do planes stay up? [Blondie holds a finger up in front of Science Girl while Megan now is the one to throw out her arms.] Megan: Well, the airflow– Blondie: Tiny birds in the wings. Thousands. Flapping hard. Science Girl: WOW! Megan: NO!

Sweet 16

Sweet 16

https://www.xkcd.com/1819

https://www.explainxkcd.com/wiki/index.php/1819:_Sweet_16

[The comic shows a direct elimination bracket (a single-elimination tournament): there is a single match played by every pair of teams, and the winners of those matches are paired up for the next round of matches, this continues until there are no more matches to be played. There are sixteen teams described here (hence the number in the title), eight on each side of the empty rectangle in the middle. Every two teams are connected, these connectors are then also connected, these connectors are yet again connected, and a final pair of connectors, after making one counter-clockwise right angle turn, end up in the top and bottom edges of the central rectangle. The bracket is empty, no results of any of the matches are indicated.] [These are paired.] A school with a dog on their team A school whose team is entirely dogs [These are paired.] A dog team with one human A dog team with one cat [These are paired.] A baseball team playing basketball A basketball team with baseball gear [These are paired.] NBA2K17 top players NBA2K17 top developers [These are paired.] The 1988 Los Angeles lakers Four kindergarteners and Lebron James [These are paired.] Boxers playing basketball Basketball players in boxing gloves [These are paired.] A team playing on stilts A team playing on Segways [These are paired.] A bad team that would make a good Cinderella story A good team playing in glass slippers

March Madness , with its championship played on the day this comic was published, is a colloquial name for the National Collegiate Athletic Association (NCAA) basketball tournament, which features 68 American college basketball teams in an elimination bracket. Due to the setup, the 16 teams that make it to the third round of the tournament (or fourth if counting the "First Four") are sometimes called the "Sweet 16", hence the title. Winning a third round game means that a team is part of the "Elite Eight," who can win to move on to the "Final Four," and then to the championship game, where a winner is crowned. This is the second time Randall has made a bracket with strange opponents meeting each other in a bracket; the first was 1529: Bracket and brackets were mentioned a second time in 2131: Emojidome . References to basketball is a recurring subject on xkcd, as is Randall's lack of interest for sport in general . In this comic, the bracket, see details below , of the final 16 is not filled in with actual college team names, but descriptions of the odd circumstances of each team. For example, the first team is "a school with a dog on their team", a reference to Air Bud . The team descriptions become increasingly bizarre, comprising varied sports and pop culture references and often building on and playing off of previous team descriptions. The first four teams on the left are composed partially or completely of animals, which are most likely pets, but could be animals for assisting disabled persons, emotional support animals, police dogs, feral cats, etc. The next two teams consist of some form of baseball -basketball crossover. The bottom two teams on the left feature developers and players of NBA 2K17 , a basketball video game by 2K Games. The first team on the right, the 1988 Los Angeles Lakers is an actual historical NBA team; though the particular team from 1988 would not exist today, it could be a team of the same players, who would now be in their mid-50s or 60s. They are paired against a team of four kindergartners and current Cleveland player Lebron James (born 1984), who was also a kindergartner in 1988. James was considered the best active NBA player as of 2017. Ironically, LeBron James has since become a Laker, as of the 2019-20 NBA season; he has become the first NBA player to win a championship in 3 different teams (having previously won titles with the Miami Heat and Cleveland Cavaliers). The next two teams feature basketball- boxing crossovers. The bracket after that features teams on unconventional mobility aids, Segways and stilts . The final two teams are Cinderella teams . A Cinderella story is when a weak team works hard to achieve success. The final team consists of players wearing glass slippers, often a part of the Cinderella fairy tale. The title text explains what the heck Randall was doing to make this comic: Randall is incredibly out of touch with sports, or at least their traditions. During March Madness a popular pastime is to take a look at the starting bracket of all 68 teams and speculate who will win each round. This activity is sometimes associated with gambling, where the person with the most correct bracket could potentially win money. Randall, when handed a blank bracket, instead fills it with teams he wants to see play rather than who is actually in the tournament. A bracket is considered "busted" when a number of predicted teams lose earlier than expected. In this case, since Randall's Sweet 16 does not include any of the real teams participating in the tournament, his bracket is busted from the beginning. As neither this comic from April 3rd or the previous comic, 1818: Rayleigh Scattering from March 31st was one of Randall's April fools' comics , this was the first year since 2010 with no April Fools' Day comic. See more on this in the Trivia section for the previous comic. Two years later in 2019 the April Fools' comic 2131: Emojidome , was using such a bracket as above to match 512 emojis to find the best emoji. Same time of year, so probably again a reference to March Madness. [The comic shows a direct elimination bracket (a single-elimination tournament): there is a single match played by every pair of teams, and the winners of those matches are paired up for the next round of matches, this continues until there are no more matches to be played. There are sixteen teams described here (hence the number in the title), eight on each side of the empty rectangle in the middle. Every two teams are connected, these connectors are then also connected, these connectors are yet again connected, and a final pair of connectors, after making one counter-clockwise right angle turn, end up in the top and bottom edges of the central rectangle. The bracket is empty, no results of any of the matches are indicated.] [These are paired.] A school with a dog on their team A school whose team is entirely dogs [These are paired.] A dog team with one human A dog team with one cat [These are paired.] A baseball team playing basketball A basketball team with baseball gear [These are paired.] NBA2K17 top players NBA2K17 top developers [These are paired.] The 1988 Los Angeles lakers Four kindergarteners and Lebron James [These are paired.] Boxers playing basketball Basketball players in boxing gloves [These are paired.] A team playing on stilts A team playing on Segways [These are paired.] A bad team that would make a good Cinderella story A good team playing in glass slippers

Security Advice

Security Advice

https://www.xkcd.com/1820

https://www.explainxkcd.com/wiki/index.php/1820:_Security_Advice

[Cueball is listening to Ponytail who holds her hands out in front of her.] Ponytail: We've been trying for decades to give people good security advice. Ponytail: But in retrospect, lots of the tips actually made things worse. [Cueball takes his hand to his chin as Ponytail takes her arms down.] Cueball: Maybe we should try to give bad advice? Ponytail: I guess it's worth a shot. [Below these two panel is one large and long panel with a long list with 13 tips. The underlined heading and the bracket below it are centered above the bullet list below.] Security tips (Print out this list and keep it in your bank safe deposit box.)

The comic depicts a conversation between Cueball and Ponytail , discussing the fact that giving people security advice in the past has failed to improve their internet security, and in some cases even made things worse. One such example is telling people to create complicated passwords containing numbers and symbols, which not only made the passwords harder to remember (leading people to create huge security risks by leaving post-it notes with their passwords on their computer monitor ), but did not actually make those passwords harder to crack (see 936: Password Strength ). As a result, Cueball suggests using reverse psychology and give out bad advice instead, in hopes of achieving a positive effect. The last panel contains a list with 13 security tips, which are parodies of actual security tips. The title text is just one more tip. See table below for explanations for all 14 tips. This comic is yet another tips comic . [Cueball is listening to Ponytail who holds her hands out in front of her.] Ponytail: We've been trying for decades to give people good security advice. Ponytail: But in retrospect, lots of the tips actually made things worse. [Cueball takes his hand to his chin as Ponytail takes her arms down.] Cueball: Maybe we should try to give bad advice? Ponytail: I guess it's worth a shot. [Below these two panel is one large and long panel with a long list with 13 tips. The underlined heading and the bracket below it are centered above the bullet list below.] Security tips (Print out this list and keep it in your bank safe deposit box.)

Incinerator

Incinerator

https://www.xkcd.com/1821

https://www.explainxkcd.com/wiki/index.php/1821:_Incinerator

[Cueball and Ponytail stand next to an incinerator, with a combustion chamber and flue that rises up to the top of the frame.] Ponytail: Great, the new incinerator is installed. Now we just need to dispose of the old one. [Ponytail walks out of the frame.] [Cueball lowers his head, beat panel] [Cueball raises his hand and begins to ask a question.] Cueball: Hey, could— Ponytail (off-panel): No. Cueball: Aww, maaan.

Cueball and Ponytail have just finished installing an incinerator for some unspecified purpose at some establishment. Ponytail brings up the problem of having to get rid of the old incinerator, and Cueball begins to suggest using the new incinerator to incinerate the old one, but he is shut down by Ponytail off-panel. This makes him noticeably disappointed, probably because the idea of using an incinerator to destroy an incinerator is novel to him. Throwing an incinerator inside another incinerator would probably break some kind of regulations or safety concerns, and since incinerators are meant to withstand their own high heat capacities it would be ineffective anyway. The title text implies that this comic was inspired by recent events at Randall 's house: his trash can broke and he struggled with how to dispose of it. At least for Randall, there is something wrong with forcing anything to destroy something of its own kind -- in this case, throwing the old trash can in the new trash can. Since machines have no human emotion [ citation needed ] this would not cause any trauma for the machine , but the humans in charge might feel as if something is wrong, and Randall mentions having an existential crisis . This is because humans tend to project human qualities onto the machines they are working with ( anthropomorphization ), thus possibly framing the situation in the context of something like cannibalism or homicide. Another way of taking it would be in the sense of "being replaceable". Many people live without wanting to think of what might happen to everything around them after they die, but in this title text one can start comparing the trash can to themselves — the same way the trash can turns into something to be disposed and replaced with a new one after it becomes useless, what about people then? What will happen to you when you grow older? Should you suddenly go sick and become useless? How about in your job, what would happen if someone more superior than you comes around and starts threatening your hard-earned position? Yet another interpretation is that while disposing of the trash can, Randall realized that he was now in the same situation as the trash can itself. The trash can was a tool used by others, in order to dispose of trash. And yet, in time, the trash can itself became trash and had to be disposed of by Randall. Which makes one wonder if Randall is himself a tool created/used by others, who will one day dispose of Randall when he has outlived his usefulness, the same way that he disposed of the trash can when it outlived its usefulness. From this perspective, Randall is simply a more intelligent and autonomous trash-junking-tool, different in degrees but similar in nature to his own trash can. Many people define themselves by the things they do and are capable of. The idea of losing those, and then being replaced for it, is a bitter pill that we will all have to swallow at some point. All things must come to end after all, including ourselves. A more simple reason for this may be that for almost anything else you might pick up, having done so you now have the option to put it in the trash can. Picking up the trash can itself (perhaps just to work out if it is beyond use) simultaneously removes "the trash can you may opt to put something you hold in" from its usual point in your normally instintively simple mental mapping of the domestic universe. Plus, actually throwing out a garbage can can be surprisingly difficult . Another device to perform a meta-action was previously explored in 952: Stud Finder . [Cueball and Ponytail stand next to an incinerator, with a combustion chamber and flue that rises up to the top of the frame.] Ponytail: Great, the new incinerator is installed. Now we just need to dispose of the old one. [Ponytail walks out of the frame.] [Cueball lowers his head, beat panel] [Cueball raises his hand and begins to ask a question.] Cueball: Hey, could— Ponytail (off-panel): No. Cueball: Aww, maaan.

Existential Bug Reports

Existential Bug Reports

https://www.xkcd.com/1822

https://www.explainxkcd.com/wiki/index.php/1822:_Existential_Bug_Reports

[Megan is sitting in an office chair at her desk typing on her laptop. Above her are two light-gray frames with text. Above each frame is a bold header:] Issue: Recent update broke support for hardware I need for my job. Workaround: If we wait long enough, the Earth will eventually be consumed by the Sun.

Megan is sitting at her desk, writing an error report. Her description of the issue is fairly standard, albeit somewhat vague: A recent software update has broken the support for hardware she needs for her job. Most likely, she is saying that her OS is now reporting a piece of hardware is no longer supported. This is self-evidently problematic for her, as described in her error report. The humor in this strip comes from her own suggested workaround (a short-term method of working despite the problem), which is absurd as she proposes simply waiting for the Sun to consume the Earth when it turns into a red giant towards the end of its lifetime approximately 5 billion years from now. While this would eliminate the issue, as both the hardware and software as well as Megan and her job would all cease to exist, this would not be helpful to Megan as it does not address the underlying problem of her being unable to work in the present. 5 billion years is also far in excess of the lifespan of humans [ citation needed ] and operating systems alike. Lastly, as it does not allow Megan to actually continue her work, it's not strictly speaking a workaround. In the title text, Randall asks for a workaround from Megan's "workaround". He writes it down as another bug report, as though it were a software problem. The answer is that there is none . Randall in his crisis see no way to prevent Earth from being consumed by the Sun. However, one possible workaround could be evacuation of the Solar System, as if humanity still exists by the time the Earth's destruction occurs, we will likely have highly advanced technology. Maybe at that time it would even be possible to move the Earth , first further out to prevent both the engulfment and also the earlier evaporation of the oceans and later it could then be moved back in when the sun turns into a white dwarf . Megan has previously expressed such existential problems in 220: Philosophy , where Randall presented a solution for it. Similar she was depressed in 1111: Premiere , where it was the boiling away of the oceans, mentioned above, that was her concern. [Megan is sitting in an office chair at her desk typing on her laptop. Above her are two light-gray frames with text. Above each frame is a bold header:] Issue: Recent update broke support for hardware I need for my job. Workaround: If we wait long enough, the Earth will eventually be consumed by the Sun.

Hottest Editors

Hottest Editors

https://www.xkcd.com/1823

https://www.explainxkcd.com/wiki/index.php/1823:_Hottest_Editors

[A short list with a heading above a line and below that a list of seven years increasing with 5 years intervals. After each year are gray lines that leads to the name of an editor, except for the first two years, where there is a two row square bracket around the first entry;] Hottest Editors -------------------- 1995-2000—[Emacs–Vim Editor war] 2005—Vim 2010—Notepad++ 2015—Sublime Text 2020—CRISPR 2025—CRISPR (Vim keybindings)

The comic has a play on the word 'Editor'. The editors from 1995 to 2015 are software text editors, and the editor(s) from 2020 onward are genomic editing techniques that edit DNA . Text editors are popular among programmers and computer scientists to edit machine-readable text, as well as other digital files. Two of the earlier editors, Vim and Emacs , traditionally use the keyboard (rather than the mouse) to perform common actions (like scrolling, marking text, saving, and searching). As Vim and Emacs use different keyboard commands in different styles, proficiency in one editor does not make it easy to use the other. The " Editor wars " refers to Vim and Emacs users debating heavily over which of the two editors is the best (keyboard bindings is just one argument). This debate was previously mentioned in 378: Real Programmers . More modern editors (including Notepad++ and Sublime Text) mainly use keyboard shortcuts that are global to the operating system, again different from Vim and Emacs. Notepad++ is a popular text and source code editor, initially released in 2003 and available only for the Windows platform. Sublime Text is the current "most popular" text editor according to this comic; it was released in 2008. Sublime Text, Vim, and Emacs are cross-platform. The 2020 editor ' CRISPR ' is not a text editor, but a technique used to edit DNA in a pre-existing genome. The technique has experienced a surge of recent attention in the media (beginning with the 2016 publication of "The Heroes of CRISPR" and litigation over the patent ownership), suggesting it may become the most popular "editor" in years to come. The joke lies in the comic intentionally not distinguishing between text/code editing and genome editing. It may also suggest that we will not be editing digital plain-text files, but DNA in 2020, possibly due to very recent advances in DNA digital data storage . Many pieces of software that contain editing functions (in text boxes, on command lines, etc.) offer Emacs and/or Vim keybindings: the keys will be (roughly) the same as in Emacs or in Vim, so that someone familiar with one of those editors can use the keyboard without learning something new. The comic suggests that in 2025, the Vim key-bindings will be the most popular for editing genes using CRISPR. This creates a comical effect: CRISPR is a technique that operates on genes and not on digital hardware, so it does not use a keyboard per se. Consequently, it is surprising that CRISPR would have key bindings. The comic also suggests that in 2025, Vim will make a comeback in DNA editing, thus having 'won' the battle with Emacs. The title text says that Randall has been banned from the code base of Tesla , as he keeps sending pull requests (code changes) to steer a Tesla car using Vim keybindings. Not only does this seem implausible, but it seems dangerous to steer a car with a (computer) keyboard. The arguably most important keybindings of a text editor are those to move the editing location (the cursor) around. Vim classically uses the h , j , k , and l keys for left , down , up , and right functions, although it also supports the arrow keys present on modern keyboards. To use these in a vehicular context, up and down would probably, as in many racing games, be mapped to acceleration and braking, respectively. One additional problem with using essentially binary inputs (key pressed or not) as a replacement for a car's steering wheel is achieving different degrees of direction change. Pressing, say, the h key could either cause the car to turn its wheels left by a pre-set, fixed amount, or it could turn them left the more the longer the key is held down. There has been a spoof based on the reverse principle, however. [A short list with a heading above a line and below that a list of seven years increasing with 5 years intervals. After each year are gray lines that leads to the name of an editor, except for the first two years, where there is a two row square bracket around the first entry;] Hottest Editors -------------------- 1995-2000—[Emacs–Vim Editor war] 2005—Vim 2010—Notepad++ 2015—Sublime Text 2020—CRISPR 2025—CRISPR (Vim keybindings)

Identification Chart

Identification Chart

https://www.xkcd.com/1824

https://www.explainxkcd.com/wiki/index.php/1824:_Identification_Chart

[A silhouette identification guide chart shows eight silhouettes in two rows. The silhouettes are a combination of the fuselage of an aircraft and the wings of birds, or in the second case an insect. Below each silhouette is a label:] Osprey Hornet Falcon Harrier Eagle Kestrel Hawk Blackbird

Some aircraft are named after creatures of flight, including birds of prey , other birds, and insects. This comic spoofs an "identification guide" of bird silhouettes, each with the fuselage of an aircraft and the wings of the flying animal from which the aircraft gets its name. All are birds with the exception of the hornet which is an insect, see the table below for individual explanations. This idea of having feathered wings on a plane is absurd, as bird wings (for birds that can fly) are made to support the lightweight structure of a bird. Supporting the metal parts of a plane along with its human pilot would be impossible. [ citation needed ] General military training often includes aircraft identification. Silhouette charts are given to ground observers for memorization and reference so that friend or foe can be determined in the field. Conversely, many bird watching books will carry pictures of avian silhouettes from below, as often key details like tail and wing shape are the easiest way to determine the species of a high soaring bird, especially birds of prey. (Two comics later Cueball is out birdwatching with his friend in 1826: Birdwatching and could need such a chart, if he could spot any birds that is. A hawk, that is actually a drone, was spotted in 1910: Sky Spotters .) The pseudo-confusion between birds and planes here could be a reference to the "It's a bird! It's a plane! It's Superman" quote often used in, naturally, Superman -related entertainment. A similar joke was used in 1792: Bird/Plane/Superman . The comic highlights not only the various designs of aircraft tails, but also bird wings. Some wings are highly adapted for soaring (eagle), speed (falcon), as well as rapid acceleration and short flights (blackbird). The title text is juxtaposing military air bases with breeding nests of the animals, both of which might earn a hostile response to approach at the wrong time, but in wildly different measure. Encroaching on breeding territory of some of the birds being referenced may result in getting dived at or chased, so the comparison invites the reader to imagine what might happen if the analogous creatures in the comic were defending their nest with aircraft ordnance. And if the birds were armed, with the missiles normally found on a military aircraft then imagine what would happen... This could also be a reference to the increasing hostility between US and Russia, as well as the generally more strained relationship US now has with many countries after the election of Donald Trump for president half a year before this comic was released. This is also the second comic to refer to the military in less than two months, the first being 1803: Location Reviews reviewing a Nuclear Launch Facility. Randall has seemed very worried in his comics since the election, see more regarding this here . The idea of a bird with plane engines was first used in 1729: Migrating Geese , which also shows birds in silhouette. The third last bird in the right arm of the V-formation has twin engines. [A silhouette identification guide chart shows eight silhouettes in two rows. The silhouettes are a combination of the fuselage of an aircraft and the wings of birds, or in the second case an insect. Below each silhouette is a label:] Osprey Hornet Falcon Harrier Eagle Kestrel Hawk Blackbird

7 Eleven

7 Eleven

https://www.xkcd.com/1825

https://www.explainxkcd.com/wiki/index.php/1825:_7_Eleven

[A person in a spacesuit is trying in vain to open the door to a convenience store, rattling the handle. Behind him stands a tall post with a big 7-eleven logo at the top and the opening hours on a bar below the logo.] Sign: 7-Eleven Bar: Open 24 hours Door: Rattle rattle [Caption below the panel:] I'm glad they finally opened a 7-Eleven here on Mars, but it's annoying how it closes for 37 minutes every day.

This comic pokes fun at the idiosyncrasies of time keeping. Since units of time are intimately tied to a planet's rotation, and planets rotate at different rates, time keeping doesn't always follow a simple pattern. Many stores advertise being open 24/7, which means that they're open all day, every day. Many locations of the convenience store chain 7-Eleven are now "open 24 hours", again meaning they are always open (despite historically being open only from 7 AM to 11 PM local time, hence its name). The main joke in the comic refers to the fact that a day on Mars (the time it takes for Mars to make a full rotation on its own axis) is about 24 hours and 37 minutes. If a 7-11 store is open for literally 24 hours per Mars day, then it would actually be closed for around 37 minutes each day. NASA, for its Mars missions, uses a "Mars-hour" that is one twenty-fourth of a Martian day; had the sign implicitly referred to 24 Mars-hours then the store would be open for the entire Mars day. The duration for the Martian day used by Randall is the Martian sidereal day (how long it takes the non-Sun stars to get to the same position in the sky) of 24 hours, 37 minutes, and 22.663 seconds. However, Mars exploration missions use the Martian solar day (how long it takes the Sun to get to the same position in the sky) or sol of 24 hours, 39 minutes, and 35.244 seconds. Thus in practice, the 7-11 store would be closed for 39 minutes daily instead of 37 minutes. Likewise, Earth time usually refers to solar days; a typical (mean) sidereal Earth day is 23 hours, 56 minutes, 4.0916 seconds long. The first part of the title text refers to daylight saving time (DST), where clocks are changed on predefined days of the year in order to maximize use of available sunlight. In the United States, most places set clocks forward by one hour on the second Sunday of March, resulting in a 23-hour day, and back again on the first Sunday of November, resulting in a 25-hour day. Thus technically, even a 7-11 in the US would not truly be open "24 hours" every day. Arizona and Hawaii are called out as exceptions because they do not observe daylight saving time (except on the Navajo reservation in Arizona). Randall has made fun of DST several times before , and once again he shows his disdain for DST by saying that in the U.S., only 24-hour stores within the two states not using DST are honest. This comic came out over a month after DST began in the US. The second part of the title text refers to leap seconds , which may be added or subtracted to the end of June or December in order to synchronize time with Earth's actual rotation. Months with a leap second will see its last day being one second longer than 24 hours. Since leap seconds apply to all Earth-based clocks, any store on Earth would not technically be open for exactly 24 hours on such days. Leap seconds have been referred to before in the title text of 1514: PermaCal . [A person in a spacesuit is trying in vain to open the door to a convenience store, rattling the handle. Behind him stands a tall post with a big 7-eleven logo at the top and the opening hours on a bar below the logo.] Sign: 7-Eleven Bar: Open 24 hours Door: Rattle rattle [Caption below the panel:] I'm glad they finally opened a 7-Eleven here on Mars, but it's annoying how it closes for 37 minutes every day.

Birdwatching

Birdwatching

https://www.xkcd.com/1826

https://www.explainxkcd.com/wiki/index.php/1826:_Birdwatching

[Cueball and Knit Cap with a knit cap are standing together looking up in the sky. Cueball holds a camera with a large lens down in front of him, and his friend holds binoculars down in front of him.] Cueball: Birdwatching is hard. Cueball: They're all way too small and far away. [In a frame-less panel they both raise their tool eyepieces to their eyes.] Cueball: That hawk is over a mile up! How did you even spot it? [Both lower their eyepiece again. The friend still looks up while Cueball looks down on his camera which he holds up in front of him. A black squiggly line above his head indicates that he is fuming over his camera's abilities.] [Cueball now has a vacuum cleaner with a big body and a large hose which he is pointing towards the sky, as air is visibly sucked in to the hose and the vacuum cleaner is making a very loud noise which extends beyond the frame of the panel.Cueball is holding one hand on the vacuum cleaner which has a label with its brand on it. Cueball's camera lies on the ground in front of the vacuum cleaner. The friend looks back at Cueball.] Vacuum cleaner: Whrrrrr Label: Shop Vac

In this comic Cueball and Knit Cap are out birdwatching (hence the title). Birdwatching is an activity to observe birds. Usually this is done at a distance, as birds are flying in the air, and are far away. It is thus helpful to use binoculars . Knit Cap uses binoculars and manages to spot a hawk a mile up. Cueball, however, has brought his camera, probably his superzoom camera from 1719: Superzoom . (He uses that again already two comics later in 1828: ISS Solar Transit ). It is very difficult to find anything in such a camera, especially if held in one's hand (as opposed to on a tripod) and zoomed in. Maybe Cueball is with his trained friend, out birdwatching for the first time. Cueball is frustrated and comments on the difficulty and is amazed Knit Cap can spot birds over such distances. Frustrated with his camera, Cueball comes up with a solution, which is to use a vacuum cleaner , specifically a shop vac , to pull the birds in closer so he won't need the superzoom camera to see them. This is physically impossible with such a small device. Even if the shop vac created a perfect vacuum, it can only pull out air at the speed of sound, which amounts to approximately 1 cubic meter per second considering the apparent size of the hose. This is not enough to create a significant amount of wind or affect the atmosphere. (He might've borrowed it from Beret Guy who has many strange powers that also extends to improving vacuum cleaners, which Cueball knows about as seen in 1486: Vacuum ). Cueball's shop vac bird collector is similar in concept to vacuum-based insect collectors used by entomologists . Cueball evidently thinks that a similar concept will work to easily collect birds. The title text refers to park rangers , who are officials in charge of protecting the natural elements (i.e. plants, animals, etc.) in many parks and would certainly object to birds being forced to coalesce via an extremely powerful vacuum. If such a vacuum were created and used for this purpose, it probably would pose a threat to the safety of birds. Cueball says he has solved this problem by placing a perforated screen in front. In doing so, he can safely attract the birds without trapping them inside the vacuum. He implies that this should remove the danger to the birds, which is not the case. While the birds can no longer enter the vacuum itself, having a large number of birds pulled into a (presumably small) screen would probably fare poorly for the birds, so Cueball's solution is rather poor. When out birdwatching it is a great idea to have a silhouette chart to be able to recognize the birds by the shadow they make against the sky. Two comics before this one Randall made a comic with just such a chart, 1824: Identification Chart , although that was for combinations of birds and planes... [Cueball and Knit Cap with a knit cap are standing together looking up in the sky. Cueball holds a camera with a large lens down in front of him, and his friend holds binoculars down in front of him.] Cueball: Birdwatching is hard. Cueball: They're all way too small and far away. [In a frame-less panel they both raise their tool eyepieces to their eyes.] Cueball: That hawk is over a mile up! How did you even spot it? [Both lower their eyepiece again. The friend still looks up while Cueball looks down on his camera which he holds up in front of him. A black squiggly line above his head indicates that he is fuming over his camera's abilities.] [Cueball now has a vacuum cleaner with a big body and a large hose which he is pointing towards the sky, as air is visibly sucked in to the hose and the vacuum cleaner is making a very loud noise which extends beyond the frame of the panel.Cueball is holding one hand on the vacuum cleaner which has a label with its brand on it. Cueball's camera lies on the ground in front of the vacuum cleaner. The friend looks back at Cueball.] Vacuum cleaner: Whrrrrr Label: Shop Vac

Survivorship Bias

Survivorship Bias

https://www.xkcd.com/1827

https://www.explainxkcd.com/wiki/index.php/1827:_Survivorship_Bias

[Hairy, holding an arm out towards an unseen crowd, is standing on a podium with five large bags around him, each having a dollar sign on it.] Hairy: Never stop buying lottery tickets, no matter what anyone tells you. Hairy: I failed again and again, but I never gave up. I took extra jobs and poured the money into tickets. Hairy: And here I am, proof that if you put in the time, it pays off! [Caption below the panel:] Every inspirational speech by someone successful should have to start with a disclaimer about survivorship bias.

This comic is a parody of entrepreneurial speeches. Entrepreneurial speeches are talks, such as graduation commencements or motivational speeches. The idea behind graduation commencements is that the entrepreneur, having accumulated wisdom and experience in the process of becoming successful, will share his insights and experience to the students, in the hope that they learn lessons that will help them achieve success as well. Companies hire motivational speakers to motivate employees to work hard. A common theme in these talks is that the entrepreneur succeeded by persisting through hardship, sometimes despite other people telling them they would be better off giving up. They advise students to do the same, and to keep pursuing their dreams even through subsequent failure. While this isn't necessarily bad business advice, this can give students a biased vision of reality, and lead them to imagine that they will succeed as long as they keep trying. This comic makes a joke about survivorship bias, hence the title. Survivorship bias , or survival bias, is the logical error of concentrating on the people or things that "survived" some process and inadvertently overlooking those that did not because of their lack of visibility. This can lead to false conclusions in several different ways. The survivors may be actual people, as in a medical study, or could be companies or research subjects or applicants for a job, or anything that must make it past some selection process to be considered further. They may also have "survived" on only some of their attempts. In this comic Hairy is giving a talk encouraging people to "never stop buying lottery tickets". This is an unwise investment plan, because the chances of winning the lottery are mathematically very low and the total payout is usually less than the total ticket sales, meaning the expected return from buying a lottery ticket is ( almost ) always negative. Survivorship bias applies in this situation since people who eventually win (and, presumably, win more than they've spent on lottery tickets in the time that it took them to win) are much more likely to give inspirational speeches than someone who never won or didn't win enough to make the "investment" worthwhile. The obvious bad strategy (keep buying lottery tickets) is a metaphor for strategies that successful entrepreneurs recommend (keep persisting and putting money into your start-up); these strategies may be bad on average, but people who pursued them and succeeded are much more likely to be invited and give speeches than people who pursued them and went bankrupt (or people who pursued safer strategies and kept their money), making it appear to students that taking high risks and persisting in the face of expensive failure is the optimal strategy. And those who have done both, are more likely to speak about the successes than the failures and bankruptcies. Randall says in the caption below the panel that people should be informed about survivorship bias before hearing inspirational talks from successful people. The title text says "They say you can't argue with results, but what kind of defeatist attitude is that? If you stick with it, you can argue with ANYTHING." In the comic, the speaker's "result" was winning the lottery. Pointing out the survivorship bias is Randall effectively arguing with results, by pointing out that they were obtained randomly, and that it ignores all the other people who may have (foolishly) followed this same process, but never won the lottery. Taken a step further, one could use the survivorship bias to argue against the results of any process, be it research (Any given research process is bound to produce SOME good results, and since those are the only ones published, it is difficult to determine if the research process itself contributed to the good results), business decisions (Some businesses fail, and others succeed, but since only the successful ones stick around, it can be difficult to determine WHY they failed or succeeded), etc.. [Hairy, holding an arm out towards an unseen crowd, is standing on a podium with five large bags around him, each having a dollar sign on it.] Hairy: Never stop buying lottery tickets, no matter what anyone tells you. Hairy: I failed again and again, but I never gave up. I took extra jobs and poured the money into tickets. Hairy: And here I am, proof that if you put in the time, it pays off! [Caption below the panel:] Every inspirational speech by someone successful should have to start with a disclaimer about survivorship bias.

ISS Solar Transit

ISS Solar Transit

https://www.xkcd.com/1828

https://www.explainxkcd.com/wiki/index.php/1828:_ISS_Solar_Transit

[Cueball is kneeling in front of a small platform while operating a camera with a very long objective. The camera is angled sharply upward toward the sky as it is attached to a tripod standing on the platform. An off-panel voice calls out to him.] Off-panel voice: What's going on? Cueball: ISS solar transit. From this spot, the space station should briefly line up with the sun. Cueball: I got a sun filter and I'm trying to take a picture of it crossing. [Two half height panels above each others follow. The first shows an image of the very orange sun on a black background, as seen through the camera.] [The second of the two half height panels shows Cueball making further adjustments to the camera, as in the first panel.] Cueball: Perfect. Hmm, I should set the white balance. [Once gain there are two panels above each other. The top is black with white text and icons from the white balance menu. It has the following options shown after each of the icons as mentioned below in the square brackets:] [Shining light bulb]: Incandescent [Shining fluorescent lamp]: Fluorescent [Shining sun]: Direct sunlight [Lightning]: Flash [Cloud]: Cloudy [A house that cast a shade]: Shade [Two triangles with a circle between them]: Custom [In the panel below Cueball still operates the camera as before] [A frame-less but full height panel follows where Cueball leans back from the camera with his hands on his thighs.] [The last two panels are again above each other. It is almost the same panels as before the frame-less panels, except that the direct sunlight option has been selected as shown with a blue selection band across that option.] Incandescent Fluorescent Direct sunlight Flash Cloudy Shade Custom [In the bottom panel Cueball again operates the camera.]

This is the first comic in a two comic series , released during the same week on Monday and Friday. This comic continues in 1830: ISS Solar Transit 2 . Cueball is trying to take a photograph of the International Space Station moving in front of the sun ( example ). He has his camera with a long lens set up with a fixed setting to keep it still while he contemplates the best way to get the photographs he wants. A normal camera is not able to take a photograph of the sun due to the extreme brightness. This is why Cueball is using a solar filter , which makes the sun look orange instead of white, as shown in the second panel. Digital cameras need to determine the color temperature of a photograph to correctly display colors. This is done using the white balance setting. The joke here is that Cueball selects the "direct sunlight" option, as he feels it is the option that best suits his unusual situation of directly photographing the sun, even though the "direct sunlight" setting is intended to be used for photographing objects directly illuminated by the sun and not for the sun itself. The light from an object illuminated by "direct sunlight" is, in fact, indirect sunlight when it reaches the camera sensor; so when photographing the sun itself, the camera receives sunlight that is even more direct than "direct". The use of a solar filter influences the color temperature, so "custom" would probably be the correct option here. A camera using the "custom" option usually requires you to focus on a white or gray object first to determine the correct setting. Most high-end cameras, like the superzoom camera that is likely depicted here, are able to capture in raw image format , allowing the user to adjust the white balance afterwards in software. The title text is pointing out that the sunlit side of the moon is also in direct sunlight, which is why we are able to see it, and so "direct sunlight" would actually be the correct setting in this case. It is the second comic within a week where Cueball is using a camera, similar to the one he used in 1719: Superzoom . The previous comic was 1826: Birdwatching , two comics before this one. [Cueball is kneeling in front of a small platform while operating a camera with a very long objective. The camera is angled sharply upward toward the sky as it is attached to a tripod standing on the platform. An off-panel voice calls out to him.] Off-panel voice: What's going on? Cueball: ISS solar transit. From this spot, the space station should briefly line up with the sun. Cueball: I got a sun filter and I'm trying to take a picture of it crossing. [Two half height panels above each others follow. The first shows an image of the very orange sun on a black background, as seen through the camera.] [The second of the two half height panels shows Cueball making further adjustments to the camera, as in the first panel.] Cueball: Perfect. Hmm, I should set the white balance. [Once gain there are two panels above each other. The top is black with white text and icons from the white balance menu. It has the following options shown after each of the icons as mentioned below in the square brackets:] [Shining light bulb]: Incandescent [Shining fluorescent lamp]: Fluorescent [Shining sun]: Direct sunlight [Lightning]: Flash [Cloud]: Cloudy [A house that cast a shade]: Shade [Two triangles with a circle between them]: Custom [In the panel below Cueball still operates the camera as before] [A frame-less but full height panel follows where Cueball leans back from the camera with his hands on his thighs.] [The last two panels are again above each other. It is almost the same panels as before the frame-less panels, except that the direct sunlight option has been selected as shown with a blue selection band across that option.] Incandescent Fluorescent Direct sunlight Flash Cloudy Shade Custom [In the bottom panel Cueball again operates the camera.]

Geochronology

Geochronology

https://www.xkcd.com/1829

https://www.explainxkcd.com/wiki/index.php/1829:_Geochronology

[Ponytail is gesturing toward some rock formations in a grass field while addressing Megan and Cueball who are looking down at the rocks, Cueball with a hand to his chin.] Ponytail: This bedrock likely formed as the Dalmatian microplate subducted under East Laika during the Upper Pomeranian. Cueball: Ah, yes. [Caption below the panel:] Geology Tip: There are so many microplates and ages that no one remembers them all, so in a pinch you can bluff with dog breeds.

Ponytail is describing the origin of some rock formations to Megan and Cueball . She apparently forgot the names of the microplates and the age when the subduction occurred, so she substituties them with names of dog breeds ( Dalmatian , Laika and Pomeranian ) to seem knowledgeable and impress her audience. Although no microplates or geological ages with these names exist, this is not obvious for people outside of the field, as dog breeds are often named after geographic regions. For example Dalmatia is the name of a region in Croatia , and a microplate named after it could exist (possibly as a fragment of the former Adriatic Plate ). Likewise, a Laika Plate could be named after the Laika Island in Vanuatu ; however, the name is unrelated to the island and originates from the Russian word лайка (lit. "barker", a generic name for several breeds of hunting dogs and also the given name of the first dog in space on Sputnik 2 ). Geological ages are often named after place where the first rocks dating from the age were found e.g. the Devonian is named after the English ceremonial county of Devon (aka Devonshire), while the Permian is named after the Russian city of Perm . Thus, a Pomeranian Age named after Pomerania , a region on the Baltic Sea split between Poland and Germany , might reasonably exist. So the comic concludes in the caption with one of Randall's many tips , this time a geology tip, about how it is possible to pretend to be more knowledgeable regarding geology (and to bluff others not educated in the science) by just inserting dog breeds names instead of real names as no one remembers the names of all the microplates. An actual geologist, unlike Ponytail, would not be fooled. The title text continues the situation until Ponytail starts to run out of dog breeds. Her audience catches on... until one of them chimes in that her "explanation" did name two real geological features: the dog breeds Labrador and Newfoundland are named after the two Canadian regions of Labrador and Newfoundland respectively. Geologically, Labrador is the easternmost section of the Canadian Shield , the ancient core of the North American continent. In contrast, Newfoundland (especially western Newfoundland) was formed from terranes , the remnants of a series of plates that collided with - and subducted beneath - North America. Some geologists have assigned the name "Newfoundland Plate" to one of these former microplates that Newfoundland now comprises. However, the title text explanation is not likely to be entirely accurate, because the most significant mountains in Newfoundland are the Long Range Mountains , which are the northernmost of the Appalachian Mountains , created when Africa and North America collided to form Pangaea ; no mountain range is identified as being the result of the collision of the Newfoundland Plate with North America. Subduction was featured in a previous comic 1388: Subduction License . [Ponytail is gesturing toward some rock formations in a grass field while addressing Megan and Cueball who are looking down at the rocks, Cueball with a hand to his chin.] Ponytail: This bedrock likely formed as the Dalmatian microplate subducted under East Laika during the Upper Pomeranian. Cueball: Ah, yes. [Caption below the panel:] Geology Tip: There are so many microplates and ages that no one remembers them all, so in a pinch you can bluff with dog breeds.

ISS Solar Transit 2

ISS Solar Transit 2

https://www.xkcd.com/1830

https://www.explainxkcd.com/wiki/index.php/1830:_ISS_Solar_Transit_2

[Every panel is split into two half-height panels arranged vertically.] [The first top panel shows an image of an orange sun on a black background with a white dot labeled in light-blue letter at the top right corner. The dot is in a light-blue cross-hair and a light-blue dotted trail is behind it as indicating movement towards the sun.] ISS [In the bottom panel Cueball is kneeling in front of a small platform while operating a camera with a very long objective while holding a smartphone. The camera is angled sharply upward toward the sky as it is attached to a tripod standing on the platform.] Cueball: Perfect! Transit in three... two... [The upper image is the same but the dot has halved the distance to the sun.] ISS [Cueball sits in the panel below.] Cueball: ...one... [In the upper panel the dotted line enters the Sun and the white dot has plunged into the sun making a flare "splash" out from the surface of the Sun. This makes a sound written in orange letters.] Fwoosh [Cueball sits silent in the panel below.]

This Friday comic is a continuation of the Monday comic from the same week, 1828: ISS Solar Transit , where Cueball was preparing his camera in order to capture the transit of the International Space Station (ISS) across the Sun . The comic is also made in the same special way using split panels. As noted in the first comic in the ISS series the white balance is still not set properly, because the sun looks orange instead of white/yellow. However, instead of transiting across the face of the sun, the ISS crashes into the Sun. In reality, of course, this can never happen, because the ISS orbits Earth at an altitude of between 330 and 435 km, while the Earth orbits the Sun at an altitude of about 149.60 million kilometers or 1 astronomical unit . This means the minimum distance between the ISS and the Sun is only slightly less than 1 AU. Also, due to parallax , only people in a very localized region on earth are able to see the ISS "hit" the sun. For all others the ISS would travel past the sun. Additionally, even if the ISS would somehow impact the sun, it would not make a noticeable splash, due to being incredibly tiny compared to the sun. It would get vaporized before reaching it. (See the what if? Tungsten Countertop ). And it would make no "Fwoosh" sound to be heard on Earth, primarily because there's a lot of empty space between Earth and the Sun [ citation needed ] , and sound cannot propagate in empty space. The title text plays on the event in the comic, by saying that a new space station is being launched every few weeks as the event in the comic keeps happening, with a continual series of ISSs being destroyed by crashing into the Sun on a regular basis. This is clearly implausible, as it has taken many years to build up the ISS, and there are at least three astronauts on board that would get killed a couple of times a month in that case. It's possible that the comic is a play on conspiracy theories about space exploration, such as the moon landing being faked. In these situations, while the government may be trying to cover up or show something different from what actually happened, amateur photographers/astronomers/radio enthusiasts (such as Cueball in this comic) claim to observe the event independently of government or commercial sources, and see what really happened. In this case, the conspiracy theory would be that the ISS actually does crash into the sun every few weeks, but we're made to believe that it orbits the earth without crashing, while Cueball is able to observe what really happens with his camera. It further bears certain resemblance to the beliefs of the Flat Earth Society, which is that the Sun and Moon are only 3000 miles away from the earth, with the rest of the cosmos being only 100 miles further way. Were that the case, such a collision would be far less unlikely; as it is, such a collision is patently ridiculous. [Every panel is split into two half-height panels arranged vertically.] [The first top panel shows an image of an orange sun on a black background with a white dot labeled in light-blue letter at the top right corner. The dot is in a light-blue cross-hair and a light-blue dotted trail is behind it as indicating movement towards the sun.] ISS [In the bottom panel Cueball is kneeling in front of a small platform while operating a camera with a very long objective while holding a smartphone. The camera is angled sharply upward toward the sky as it is attached to a tripod standing on the platform.] Cueball: Perfect! Transit in three... two... [The upper image is the same but the dot has halved the distance to the sun.] ISS [Cueball sits in the panel below.] Cueball: ...one... [In the upper panel the dotted line enters the Sun and the white dot has plunged into the sun making a flare "splash" out from the surface of the Sun. This makes a sound written in orange letters.] Fwoosh [Cueball sits silent in the panel below.]

Here to Help

Here to Help

https://www.xkcd.com/1831

https://www.explainxkcd.com/wiki/index.php/1831:_Here_to_Help

[Megan, standing next to Hairy, is addressing the reader holding her arms out. Cueball walks in from the right.] Megan: Our field has been struggling with this problem for years. [Cueball holds his laptop high up in one arm above Megan's head while holding his other arm out as well. Megan has turned to look at him.] Cueball: Struggle no more! I'm here to solve it with algorithms! [In a frame-less panel Cueball sits on a chair at a desk with his laptop working on it, while Hairy and Megan looks on from behind.] [Cueball, still sitting at his laptop, points at the screen. Megan raises her arms and four small lines above her head, on either side of her speech line, indicate her annoyance with Cueball.] Six months later: Cueball: Wow, this problem is really hard. Megan: You don't say.

This comic is a satire of computer programmers, who sometimes forget that not everything can be solved with an algorithm , or of the tendency to think computers are the answer to everything. In the first panel, Megan talks about how the field that she and Hairy work in has a difficult problem that many people have been working on. Cueball , believing that algorithms can solve their problem, tries to help. In the next panel, Megan and Hairy silently watch Cueball working on the problem on his laptop. Finally, six months later, Cueball concedes, and an exasperated Megan retorts sarcastically, pointing out that she had explained its difficulty six months ago within the timeline. The title text furthers Cueball's apparent arrogance by showing a dialogue. Megan or Hairy says, "We TOLD you it was hard," referring to the first panel, but Cueball, still confident in his own ability's superiority, says, "Yeah, but now that I'VE tried, we KNOW it's hard." The joke is that Cueball believes that, even though he has just failed, it was his attempt which proved the difficulty, and not Megan and Hairy's work for years. The dialog references an exchange from the film The Imitation Game , in which Alan Turing's superior claims, "The Americans, the Russians, the French, the Germans, everyone thinks Enigma is unbreakable," and Turing replies, "Good. Let me try and we'll know for sure, won't we?" The satire, however, applies far beyond computer programmers. It can be read as a political commentary, as in nobody knew health care could be so complicated. It is what we'd all like to see when well-meaning advice givers provide the "simple" solution to all our problems, or management provides glib advice from ten thousand feet. It is a commentary on the universal tendency to see problems as simple because we don't know what makes them hard. This comic calls back to 793: Physicists and possibly 1570: Engineer Syllogism in central theme. [Megan, standing next to Hairy, is addressing the reader holding her arms out. Cueball walks in from the right.] Megan: Our field has been struggling with this problem for years. [Cueball holds his laptop high up in one arm above Megan's head while holding his other arm out as well. Megan has turned to look at him.] Cueball: Struggle no more! I'm here to solve it with algorithms! [In a frame-less panel Cueball sits on a chair at a desk with his laptop working on it, while Hairy and Megan looks on from behind.] [Cueball, still sitting at his laptop, points at the screen. Megan raises her arms and four small lines above her head, on either side of her speech line, indicate her annoyance with Cueball.] Six months later: Cueball: Wow, this problem is really hard. Megan: You don't say.

Photo Library Management

Photo Library Management

https://www.xkcd.com/1832

https://www.explainxkcd.com/wiki/index.php/1832:_Photo_Library_Management

[A line graph is shown. The x-axis is labeled "Photos taken per day" and the y-axis is labeled "Time spent going through photos per day". The content is divided into six sections:] [Section 1: Few photos taken per day, no limit to time spent:] "No problems" [Section 2: Some photos taken per day, a limited amount of time spent going through:] "Photo library fits on most devices as long as they're not too old" [Section 3: More photos taken per day, less time spent going through:] "Need cloud storage, external hard drive, or frequent upgrades" [Section 4: A lot of photos taken per day, and even less time spent going through:] "Photo library grows faster than Moore's Law" [Section 5: Above line increasing where more time is spent as more photos are taken:] "Can't find the good photos among the thousands of bad ones" [Section 6: Below line of negative gradient, as number of photos increases and time decreases:] "Can't sleep, too busy sifting through photos to find the best one"

The comic is about the results of how many photos one takes. It is a graph showing multiple areas corresponding to the number of photos taken per day by a user and the total time spent reviewing them. The comic is split into 6 sectors as described below: As Randall goes through more photos, he finds more bad ones, erases them and more storage becomes available. This allows taking more photos and still don't exceed the limits of the quota. This is why the "secondary" lines (e.g between the different storage types) are not completely vertical but tilted to the right at the top. The title text states "A good lifehack is to use messy and unstable systems to organize your photos. That way, every five years or so it becomes obsolete and/or collapses, and you have to open it up and pick only your favorite pictures to salvage." If you know that you will lose everything, that knowledge will encourage you to save what you want the most and leave everything else. It will also help decrease how many photos you have through the same awareness. [A line graph is shown. The x-axis is labeled "Photos taken per day" and the y-axis is labeled "Time spent going through photos per day". The content is divided into six sections:] [Section 1: Few photos taken per day, no limit to time spent:] "No problems" [Section 2: Some photos taken per day, a limited amount of time spent going through:] "Photo library fits on most devices as long as they're not too old" [Section 3: More photos taken per day, less time spent going through:] "Need cloud storage, external hard drive, or frequent upgrades" [Section 4: A lot of photos taken per day, and even less time spent going through:] "Photo library grows faster than Moore's Law" [Section 5: Above line increasing where more time is spent as more photos are taken:] "Can't find the good photos among the thousands of bad ones" [Section 6: Below line of negative gradient, as number of photos increases and time decreases:] "Can't sleep, too busy sifting through photos to find the best one"

Code Quality 3

Code Quality 3

https://www.xkcd.com/1833

https://www.explainxkcd.com/wiki/index.php/1833:_Code_Quality_3

[Ponytail sitting in front of a computer screen typing. Cueball speaks only off-panel, but since this is a direct continuation of comic 1513 and 1695: Code Quality and Code Quality 2 where Cueball is shown, there can be no doubt it is him.] Ponytail: Your code looks like song lyrics written using only the stuff that comes after the question mark in a URL. Cueball (off-panel): Sorry. [Zoom in on Ponytail's upper body.] Ponytail: It's like a JSON table of model numbers for flashlights with "tactical" in their names. [Zoom back out again. Ponytail has lifted her hands off the table and is slightly leaning back against the chair.] Ponytail: Like you read Turing's 1936 paper on computing and a page of JavaScript example code and guessed at everything in between. [Zoom in again on Ponytail's face.] Ponytail: It's like a leet-speak translation of a manifesto by a survivalist cult leader who's for some reason obsessed with memory allocation. Cueball (off-panel): I can get someone else to review my code. Ponytail: Not more than once, I bet.

This comic is the third in the Code Quality series: In the first panel, Ponytail references query strings , which store information, such as search queries or page numbers, relevant to the URL. Query strings are not meant to be especially human-readable (eg. "&sxsrf=APq-WBvn82l8oTeNNzZeCkI7B9nM5nxoVg%3A1647235405067"), so a song based on one would likely not be a good one. [ citation needed ] A tactical flashlight is a light that can be mounted on a gun for use in low-light scenarios. They tend to be very durable and very bright. Different models have different features and capabilities, so they are given cool-sounding model numbers. JSON (JavaScript Object Notation) is a subset of JavaScript used, by many programming languages, as a convenient way of recording structured data. It's not clear what else would be in the table (tables typically have more than one column) and JSON technically has arrays and objects (dictionaries) but not tables, but a JSON array of objects of these model numbers would look something like: Alan Turing was a British theoretical computer scientist, often considered the father of the field. His 1936 paper outlined Turing machines, a theoretical model for computing, as well as computability and the halting problem. Theoretical computer science is very different from practical coding; understanding the contents of the paper would not at all help a coder to understand today's algorithms, design patterns, and best practices. This is not helped by a page of JavaScript example code. JavaScript is a popular programming language which makes web pages responsive to user inputs, and while JavaScript arguably solves the problem in a practical manner (as opposed to Turing's very theoretical work), it does get a lot of criticism - for instance it is nearly untyped , which allows the programmer to do very interesting things, like JSFuck . Then, example code is used to explain a concept in programming or demonstrate how a program works, but it does not actually run on any computer. "Guessing everything in between" would involve attempting to write code using skills that could range anywhere from the most basic programming to Turing's extremely advanced ideas. In the final panel, Ponytail references leet-speak , in which symbols are replaced with similar-looking symbols, and a manifesto , a statement of a person or group's beliefs and intentions. A manifesto from a survivalist cult leader might be nonsensical, even before being translated to leet-speak. Memory allocation is a low-level computer programming concept; most modern languages have features that take care of memory allocation for the programmer, possibly implying that Cueball does not know how to use these features. At this point Cueball, quickly becoming impatient with Ponytail's sass in what is supposed to be a formal code review, retorts that if she can't start giving him the constructive criticism that he's looking for, he can always find someone else to replace her. Ponytail smugly responds that nobody else would be able to stomach his code for more than one sitting, and that she's the only one he's got. Forth is an old programming language that tends to be difficult to read. It is stack-based, meaning that values to be operated on are moved on a stack before the operation to be performed is given. Using stacks can be considered different from programming languages that resemble natural human language (e.g. COBOL ). While stack-based computing makes some problems very simple (for example, it is relatively simple to design a Forth compiler, or reversing the order of an array) and uses less computing resources, such programming languages are not easy to learn. Since Forth allows the programmer to rewrite the language, or define their own language, and it does not enforce restrictions like data types, it may be especially easy for novices to write cryptic code. A cryptogram is a cipher puzzle, generally one easy enough to be solved manually. The title text implies that the code is so bad that it looks like unreadable Forth code that is missing random characters. [Ponytail sitting in front of a computer screen typing. Cueball speaks only off-panel, but since this is a direct continuation of comic 1513 and 1695: Code Quality and Code Quality 2 where Cueball is shown, there can be no doubt it is him.] Ponytail: Your code looks like song lyrics written using only the stuff that comes after the question mark in a URL. Cueball (off-panel): Sorry. [Zoom in on Ponytail's upper body.] Ponytail: It's like a JSON table of model numbers for flashlights with "tactical" in their names. [Zoom back out again. Ponytail has lifted her hands off the table and is slightly leaning back against the chair.] Ponytail: Like you read Turing's 1936 paper on computing and a page of JavaScript example code and guessed at everything in between. [Zoom in again on Ponytail's face.] Ponytail: It's like a leet-speak translation of a manifesto by a survivalist cult leader who's for some reason obsessed with memory allocation. Cueball (off-panel): I can get someone else to review my code. Ponytail: Not more than once, I bet.

Lunch Order

Lunch Order

https://www.xkcd.com/1834

https://www.explainxkcd.com/wiki/index.php/1834:_Lunch_Order

[Three Hairy's are between two control panels, one is sitting at the panel on the right, the two others are standing and talking in the middle.] Hairy 1: Sir - Strategic command has sent us a lunch order. Hairy 2: Don't they have anything better to do? [Caption below the panel:] Everyone complains about autocorrect, but we forget about the time it prevented a nuclear war.

The comic plays on the similarity of the words "launch" and "lunch," and the fact that both "Lunch order" and "Launch order" are common phrases in their respective environments. A "lunch order" is common in many work places, where a person may be asked to go pick up lunches for multiple coworkers so they don't all need to leave to get their lunches -- they would typically give their lunch order to the person making the run so they would know what to order. A "launch order" would only apply to a place capable of launching missiles , such as military installation housing launch-able missiles. So while a "lunch order" is pretty benign and could certainly apply to such a place, a "launch order" of a nuclear warhead is a much more drastic command, meaning that the principle of deterrence has failed and mutually assured destruction is imminent. By receiving an order for "Lunch" instead of to "Launch," nuclear conflict was avoided. Autocorrect is a feature in many software text-entry applications (such as smartphone "keyboards") that will make changes to entered text that it identifies as misspelled in order to quickly increase legibility of the final text. While this process typically makes text entry quicker and easier for users, sometimes the automatically corrected text will not match what the user intended to send, which can lead to miscommunication. In most circumstances, military units charged with the maintenance of active nuclear weapons will receive their orders to employ those weapons based on direct communication from a commanding authority, these forces in the United States are commanded by the United States Strategic Command. The majority of modern nuclear weapons are prepared to be deployed by rocket launch. The joke does not depict an actual historic event. To our knowledge, the last time the United States almost launched nuclear missiles at a hostile power was June 1980 , while the function we know today as Autocorrect would not enter development until the 1990's . That said, the country still maintains a large nuclear arsenal ready to launch on short notice. The comic might be playing off recent fears involving hostilities between the United States and North Korea ; if any l(a)unch preparations have been taken in 2017, they were not declassified by the time this comic was published. The title text plays on the similarity between two phrases: "GO FOR LAUNCH" is the standard way to express the Launch status check for a rocket (and means that all checks have passed and launch can proceed), whereas "GO FOR LUNCH" expresses the more mundane act of simply beginning one's lunch break. Despite the repetition (which is intended to reduce the chance of a miscommunication), the autocorrect still managed to distort the message a further two times. A previous comic also explain the 898: Chain of Command and who's responsible of the red button. Missile launch systems and inaccurate alteration of text also figure in the later comic 2099: Missal of Silos . [Three Hairy's are between two control panels, one is sitting at the panel on the right, the two others are standing and talking in the middle.] Hairy 1: Sir - Strategic command has sent us a lunch order. Hairy 2: Don't they have anything better to do? [Caption below the panel:] Everyone complains about autocorrect, but we forget about the time it prevented a nuclear war.

Random Obsessions

Random Obsessions

https://www.xkcd.com/1835

https://www.explainxkcd.com/wiki/index.php/1835:_Random_Obsessions

[The comic shows curves plotted in an (x,y)-plane. The x-axis shows years from 2004 to 2017, with every even year labeled. The y-axis is labeled "popularity relative to peak (based on google trends)". There are five vaguely bell-shaped curves, each stretching over 9-10 years. It is implied that they rise from a value close to zero, to which they also return.] The curve labeled "robot monkeys" peaks in early 2005 and ends near the x-axis in late 2011. The curve labeled "pirates vs ninjas" peaks in late 2008 and ends in late 2014. [The remaining three curves all end in mid 2017, the comic release date. ] The curve labeled "zombies" starts in late 2007 and peaks in early 2013. By 2017 it has fallen to about 30% of its peak value. The curve labeled "bacon" starts in late 2009 and peaks in mid-2015. By 2017 it shows a value of about 90% of its peak value. The curve labeled "definition of a sandwich" starts in late 2013 and in 2017 it has reached approximately half its peak value. [Text below the panel:] Judging from Google Trends, these random semi-ironic obsessions seem to last about nine or ten years, so we should be done with the sandwich thing by 2024.

This comic is formatted as a graph showing various Internet trends over the years according to Google Trends . The caption states that these "random obsessions," as stated in the title, have 9-10 year cycles, and so predicts that the sandwich debate will be over by around 2024. Discussions about the definition of "sandwich" are surprisingly common on the web, such as "Is hot dog a sandwich?" (See this discussion on Reddit) The title text is a joke based on the debate over the definition of a sandwich. The speaker, presumably Randall , starts out with the fairly reasonable stance that open-faced sandwiches are not true sandwiches, but then veers off into the absurd by claiming that literally every other physical object in the universe is a sandwich. We can only hope that Randall does not extend this view to human beings . (On the other hand, Randall may simply be defining a sandwich in an unusual way without implying that all other items are edible, or that all objects "sandwiched" between two of the same thing (such as air, vacuum, laptops, or slices of bread) constitute a "sandwiched item" which is not necessarily edible. Such strange definitions have been seen before, in the title text of 1405: Meteor .) The other obsessions mentioned are, in order: robot monkeys, pirates vs ninjas, zombies, and bacon. "Robot Monkeys" likely refers to people being obsessed with a movie or robots of some kind. It may specifically refer to the American/Japanese animated TV series, Super Robot Monkey Team Hyperforce Go! , which aired from September 18, 2004 to December 16, 2006. It is possible that, based on this, that the trend curve does not actually begin in 2001, but does actually begin in 2004 as shown. "Pirates vs Ninjas" refers to a longstanding internet meme, popular in roughly the years shown on the chart, that held that ninjas and Caribbean pirates were arch-enemies. "Zombies" refers to the recent occurrence of zombie themed television shows (The Walking Dead) and movies (World War Z etc). Though the trend is dying out, as seen by the fact the graph is past the peak, there has been an explosion in bacon flavored/scented products as well as items of clothing and decor that look like bacon. The YouTube channel Epic Meal Time was also part of the bacon fad, as adding large quantities of bacon to the meal being prepared was one of the running gags of the channel. [The comic shows curves plotted in an (x,y)-plane. The x-axis shows years from 2004 to 2017, with every even year labeled. The y-axis is labeled "popularity relative to peak (based on google trends)". There are five vaguely bell-shaped curves, each stretching over 9-10 years. It is implied that they rise from a value close to zero, to which they also return.] The curve labeled "robot monkeys" peaks in early 2005 and ends near the x-axis in late 2011. The curve labeled "pirates vs ninjas" peaks in late 2008 and ends in late 2014. [The remaining three curves all end in mid 2017, the comic release date. ] The curve labeled "zombies" starts in late 2007 and peaks in early 2013. By 2017 it has fallen to about 30% of its peak value. The curve labeled "bacon" starts in late 2009 and peaks in mid-2015. By 2017 it shows a value of about 90% of its peak value. The curve labeled "definition of a sandwich" starts in late 2013 and in 2017 it has reached approximately half its peak value. [Text below the panel:] Judging from Google Trends, these random semi-ironic obsessions seem to last about nine or ten years, so we should be done with the sandwich thing by 2024.

Okeanos

Okeanos

https://www.xkcd.com/1836

https://www.explainxkcd.com/wiki/index.php/1836:_Okeanos

[The comic takes place during a typical YouTube livestream. The livestream video titled "Camera 1: Exploring the Central Pacific Basin" is provided by the channel "OceanExplorerGov" and recorded from Okeanos Explorer exploratory vessel. On the left hand side, the live video feed is playing, showing a jellyfish in the ocean's depths. On the right hand side, the live chat is displayed.] User #1: Fake User #2: Who else is watching this in 2017? User #3: Is this prerendered or will this be in the game? User #4: That squid is a neoliberal User #5: Why do the McElroys never talk User #6: Stop messing around and eat the fish already User #7: This is why Trump won User #8: Why do u never craft anything User #9: This is just a distraction User #10: Something is wrong with that baby giraffe [Caption below the panel:] I love watching the Okeanos Ocean Exploration livestream, but it's probably for the best that they don't enable chat.

The NOAAS Okeanos Explorer , named after the Greek (and Roman) personification of the sea Okeanos , is a vessel that is currently exploring the Central Pacific Basin. It livestreams the video feed [1] of its deep sea exploration online. This comic seems to be a representation of the livestream on YouTube [2] ; see the table below for details. The chat section for the actual livestream is disabled, but the comic adds some humorous examples of what the chat section would look like. Several of the examples are the product of commenters falsely believing the livestream is that of a game, probably since most livestreams on YouTube are of people playing games; Randall is joking about the viewers of said streams in particular not being able to tell the difference, as well as YouTube commenters in general. Randall has mentioned the ridiculousness of comments on YouTube before in both 202: YouTube and 481: Listen to Yourself . One of the comments seems to refer to Minecraft or a similar game, since one of the comments asks why nothing is being crafted (crafting is a mechanic in many games, used to make items). In the caption below Randall states that he likes to view the stream and commends them on disabling the chat section, for the reasons given in the comic above. The title text is yet another comment by someone who dropped their phone from a boat, and now wants to use Okeanos' resources to find it, which is of course impossible; if the boat was anywhere near Okeanos, the phone would have swiftly been hidden in the silt on the bottom. And even if not, the chance of finding anything dropped in the Pacific Ocean , the largest Ocean on the Earth, is all but zero. Also, the Central Pacific Basin, where Okeanos was at the time of this comic's release, is 6500 meters deep; at that depth the water pressure is approximately 4454.863 kilopascals, or roughly 646 PSI. This is probably enough to irrevocably damage something as breakable as a cell phone. Even if the phone were of the so-called "waterproof" variety, that rating is usually only applicable to a few meters of depth rather than thousands of meters. Needless to say, retrieving one's phone from the bottom of the Central Pacific Basin would be a challenging and pointless endeavor. [The comic takes place during a typical YouTube livestream. The livestream video titled "Camera 1: Exploring the Central Pacific Basin" is provided by the channel "OceanExplorerGov" and recorded from Okeanos Explorer exploratory vessel. On the left hand side, the live video feed is playing, showing a jellyfish in the ocean's depths. On the right hand side, the live chat is displayed.] User #1: Fake User #2: Who else is watching this in 2017? User #3: Is this prerendered or will this be in the game? User #4: That squid is a neoliberal User #5: Why do the McElroys never talk User #6: Stop messing around and eat the fish already User #7: This is why Trump won User #8: Why do u never craft anything User #9: This is just a distraction User #10: Something is wrong with that baby giraffe [Caption below the panel:] I love watching the Okeanos Ocean Exploration livestream, but it's probably for the best that they don't enable chat.

Rental Car

Rental Car

https://www.xkcd.com/1837

https://www.explainxkcd.com/wiki/index.php/1837:_Rental_Car

[A Cueball-like guy standing behind a desk looking at a computer screen services Megan and Cueball on the other side of the desk.] Guy: We have two rental cars left. Guy: One is the murder car. But don't let the name scare you! Guy: It's definitely haunted. But most drivers don't get murdered. Guy: Maybe one in six. [The guy lifts his hand and looks at Megan and Cueball.] Guy: The other is a regular sedan. Guy: But it has a GPS that's stuck trying to navigate to Seattle, and you can’t turn it off. Megan: ...I can ignore it, right? That's fine. [In a frame-less panel Megan and Cueball drive in the sedan.] GPS: Turn left GPS: Recalculating GPS: Make a U-turn GPS: Recalculating GPS: Turn right GPS: Make a U-turn GPS: Recalculating [Megan and Cueball walk back into the agency with the guy behind his desk. Megan holds out the car keys in one hand.] Guy: Back already? Megan: We'll take the murder car. Guy: Popular choice.

In this comic the couple Megan and Cueball want to rent a car. The Cueball-like guy from the car rental agency tells them they only have two vehicles available: Megan believes she can ignore this and accepts the less lethal car. The comic suggests that driving with a GPS that tries to guide you to a different destination than that which you wish to visit—so it is always recalculating and asking you to do U-turns—is incredibly annoying. So annoying that given the choice between the persistent low-level annoyance of the GPS on one hand, and the ("low") probability of being murdered on the other, most people will choose the latter option. After all, they might survive murderous ghosts but they feel they will not survive long having to listen to the broken GPS. According to the title text, the murderous ghosts haunt both cars, but as soon as the car starts driving and the GPS begins to drone on, even the ghost cannot stand listening to the broken GPS and stops possessing it. Apart from the joke about GPS, this is also a subtle joke on the horrible cars one might get at a car rental service. It is also possible that the car rental service is trying to drive people away from the haunted car, which we can assume is just a normal car, to get more profit when people come back and take the "haunted" car when their GPS is broken. [A Cueball-like guy standing behind a desk looking at a computer screen services Megan and Cueball on the other side of the desk.] Guy: We have two rental cars left. Guy: One is the murder car. But don't let the name scare you! Guy: It's definitely haunted. But most drivers don't get murdered. Guy: Maybe one in six. [The guy lifts his hand and looks at Megan and Cueball.] Guy: The other is a regular sedan. Guy: But it has a GPS that's stuck trying to navigate to Seattle, and you can’t turn it off. Megan: ...I can ignore it, right? That's fine. [In a frame-less panel Megan and Cueball drive in the sedan.] GPS: Turn left GPS: Recalculating GPS: Make a U-turn GPS: Recalculating GPS: Turn right GPS: Make a U-turn GPS: Recalculating [Megan and Cueball walk back into the agency with the guy behind his desk. Megan holds out the car keys in one hand.] Guy: Back already? Megan: We'll take the murder car. Guy: Popular choice.

Machine Learning

Machine Learning

https://www.xkcd.com/1838

https://www.explainxkcd.com/wiki/index.php/1838:_Machine_Learning

[Cueball Prime holds a canoe paddle at his side and stands on top of a "big pile of linear algebra" containing a funnel labeled "data" and box labeled "answers". Cueball II stands to the left side of the panel.)] Cueball II: This is your machine learning system? Cueball Prime: Yup! You pour the data into this big pile of linear algebra, then collect the answers on the other side. Cueball II: What if the answers are wrong? Cueball Prime: Just stir the pile until they start looking right.

Machine learning is a method employed in automation of complex tasks. It usually involves creation of algorithms that deal with statistical analysis of data and pattern recognition to generate output. The validity/accuracy of the output can be used to give feedback to make changes to the system, usually making future results statistically better. Cueball stands next to what looks like a pile of garbage (or compost), with a Cueball-like friend standing atop it. The pile has a funnel (labelled "data") at one end and a box labelled "answers" at the other. Here and there mathematical matrices stick out of the pile. As the friend explains to the incredulous Cueball, data enters through the funnel, undergoes an incomprehensible process of linear algebra , and comes out as answers. The friend appears to be a functional part of this system himself, as he stands atop the pile stirring it with a paddle. His machine learning system is probably very inefficient, as he is integral to both the mechanical part (repeated stirring) and the learning part (making the answers look "right"). The main joke is that, despite this description being too vague and giving no intuition or details into the system, it is close to the level of understanding most machine learning experts have of the many techniques in machine learning. 'Machine learning' algorithms that can be reasonably described as pouring data into linear algebra and stirring until the output looks right include support vector machines , linear regressors , logistic regressors , and neural networks . Major recent advances in machine learning often amount to 'stacking' the linear algebra up differently, or varying stirring techniques for the compost. This comic compares a machine learning system to a compost pile. Composting is the process of taking organic matter, such as food and yard waste, and allowing it to decompose into a form that serves as fertilizer. A common method of composting is to mound the organic matter in a pile with a certain amount of moisture, then "stirring" the pile occasionally to move the less-decomposed material from the top to the interior of the pile, where it will decompose faster. In large-scale composting operations, the raw organic matter added to the pile is referred to as "input". This cartoon implies a play on the term "input", comparing a compost input to a data input. A recurrent neural network is a neural network where the nodes affect one another in cycles, creating feedback loops in the network that allow it to change over time. To put it another way, the neural network has 'state', with the results of previous inputs affecting how each successive input is processed. In the title text, Randall is saying that the machine learning system is technically recurrent because it "changes" (i.e. gets mushy) over time. [Cueball Prime holds a canoe paddle at his side and stands on top of a "big pile of linear algebra" containing a funnel labeled "data" and box labeled "answers". Cueball II stands to the left side of the panel.)] Cueball II: This is your machine learning system? Cueball Prime: Yup! You pour the data into this big pile of linear algebra, then collect the answers on the other side. Cueball II: What if the answers are wrong? Cueball Prime: Just stir the pile until they start looking right.

Doctor Visit

Doctor Visit

https://www.xkcd.com/1839

https://www.explainxkcd.com/wiki/index.php/1839:_Doctor_Visit

[Cueball is seated on an medical examination table while Ponytail stands dressed in a doctor's coat holding a file in her right hand.] Cueball: Everything look good? Ponytail: I don't get how your body has been moving around for years and still works at all. My USB cables fray after like a month. Ponytail: Your heart has been pumping for decades without pausing for even a few minutes. Ponytail: And your eyes! They're so fragile and exposed! [Zoom in on Cueball gazing at his palms.] Ponytail (off-panel): You're full of all these high-pressure fluids and intricate parts that could kill you in seconds if they stopped working! [Zoom out again to the entire scene.] Cueball: ...can you just tell me whether I'm healthy? Ponytail: Yeah, you're fine. Ponytail: Which is weird, given that your body is basically made from dissolved bread. Later Doctor Ponytail offers these thoughts again as an internal monologue in 2057: Internal Monologues .

Cueball is visiting his doctor Ponytail , apparently for a general medical checkup. While there is nothing wrong with him medically, the doctor wonders why he has continued to work for many years despite his body parts' individual fragility. Compared to man-made structures - like the USB cables mentioned by Ponytail, which quickly begin to fray - it's surprising that the body can survive for so long while sustaining so much wear and tear. Actually the body gets stronger and more fit the more it is used (an example of antifragility ), in contrast to USB cables, which tend to wear out with use. Ponytail specifically mentions his eyes which are so fragile and exposed. Yet most people go through a whole life with both eyes intact, although the vision itself may be impaired. The human reflexes and the shape of the skull around the eyes has a lot to do with the fact that it is possible to protect such fragile structures for a lifetime. Ponytail also remarks that the body is composed of high pressure fluids (particularly blood, intracellular and extracellular fluids) and intricate parts (like the nervous system and the heart). If the fluids stopped flowing or the intricate parts stopped working, the entire body would fail, killing Cueball. It should be noted that the human body is constantly replacing dead/injured cells and proteins. In a young human body, everything in the body is continually refurbished, and nothing is able to become old enough to deteriorate unintentionally; this requires a constant supply of energy and nutrients to keep this process going. As the body ages, these self-repair mechanisms eventually slow and can no longer keep up with the required repairs; this manifests as the various symptoms of old age (wrinkled skin, graying and balding hair, worsening eyesight and hearing, etc.) and eventual death. USB cables are built to withstand far more wear and tear than the human body. But while this makes them tougher than blood vessels on the outset, they inevitably fray and fail faster than blood vessels because they lack the self-repair mechanisms of organic material. The doctor's final remark is that Cueball is mainly made from dissolved bread, which is true from the perspective that the food (bread) he eats is digested in his alimentary system, absorbed into his bloodstream and used as nutrients for growth and repair. Paleontologists use a method called isotopic analysis to determine the diets of ancient people from elements preserved in teeth and bones. Ponytail could have ordered a similar test on Cueball. This is taken further in the title text, where she states that the blood tests reveal he is 30% breakfast cereal . This likely comes from the widely-cited but not entirely accurate factoid that the human body is 70% water. The other 30% would then be flesh and other organic matter, or the dissolved bread the doctor described. Breakfast cereal and bread are both products of cereal , the edible part of a grain, making the comparison apt. All things taken into consideration, we don't actually have any confirmation that Ponytail is a real doctor . As Randall has stated before, anybody can just buy a lab coat . Although Ponytail's answer in the final panel lacks the usual "I have no idea" or equivalent non-answer , it's still somewhat possible she's a real doctor having an existential episode. [Cueball is seated on an medical examination table while Ponytail stands dressed in a doctor's coat holding a file in her right hand.] Cueball: Everything look good? Ponytail: I don't get how your body has been moving around for years and still works at all. My USB cables fray after like a month. Ponytail: Your heart has been pumping for decades without pausing for even a few minutes. Ponytail: And your eyes! They're so fragile and exposed! [Zoom in on Cueball gazing at his palms.] Ponytail (off-panel): You're full of all these high-pressure fluids and intricate parts that could kill you in seconds if they stopped working! [Zoom out again to the entire scene.] Cueball: ...can you just tell me whether I'm healthy? Ponytail: Yeah, you're fine. Ponytail: Which is weird, given that your body is basically made from dissolved bread. Later Doctor Ponytail offers these thoughts again as an internal monologue in 2057: Internal Monologues .

Genetic Testing Results

Genetic Testing Results

https://www.xkcd.com/1840

https://www.explainxkcd.com/wiki/index.php/1840:_Genetic_Testing_Results

[Cueball is seated on an medical examination table while Ponytail stands dressed in a doctor's coat holding a file in her right hand.] Ponytail: Your genetic test results are back. Apparently you're part of an unbroken lineage stretching back billions of years to the early Earth!

Ponytail continues Cueball 's medical checkup with a genetic test. Genetic tests show people genetic diseases that they might be at risk for and/or give them insight into their ancestry. In this case, the genetic results are extremely obvious: His genes are part of a long line of genes stretching back to some of the earliest life forms to have genes. This information is universally true - every known organism has such a genetic history - which makes it so vague as to be useless for either medicine or ancestry. In epidemiology, a risk factor is a variable associated with an increased risk of disease or infection. The title text says that this is a risk factor because being a living organism is, trivially, associated with every disease that exists. [Cueball is seated on an medical examination table while Ponytail stands dressed in a doctor's coat holding a file in her right hand.] Ponytail: Your genetic test results are back. Apparently you're part of an unbroken lineage stretching back billions of years to the early Earth!

Who?

Who?

https://www.xkcd.com/1841

https://www.explainxkcd.com/wiki/index.php/1841:_Who%3F

[Cueball is walking from left to right while Hairy follows him.] Hairy: ...I'm getting a ride with Katie to Adam's wedding. Hoping to see Brian on the way! Cueball: Oh, that's cool! Cueball: ...I can't keep living this lie, so I'm just gonna come out and admit it: I have no idea who any of the people you keep mentioning are.

Cueball and Hairy are walking while Hairy is talking about going to a wedding by sharing a ride. He names three people: the groom; a friend with whom he's sharing the ride; and another person he hopes to meet on the way, perhaps another guest at the wedding. The ellipsis at the beginning indicates he's been talking beforehand, and Cueball has listened to all of it. Cueball at first replies with an "it's cool" sentence, apparently expressing interest, satisfaction or approval at the idea of Hairy meeting the people he mentioned. This usually happens when two people are talking about something they have in common, like meeting with friends at a social gathering. However, Cueball suddenly expresses that he's been lying about knowing them, and he doesn't have any intentions of preserving such lie. Note that he didn't need to explicitly acknowledge to be those people's acquaintance, he might just have nodded or said expressions like "it's cool". Part of a social need for inclusion, or as a way to continue a conversation, people sometimes agree with the person they are talking to, or feign knowledge of the people, things or topics that were mentioned. The title text suddenly changes the situation by stating that it's possible Hairy has been talking to someone else using a Bluetooth earphone set . This hands-free device is used to communicate via phone call and is small in nature and only visible from one side of the face, so anyone who comes across someone using this device can at first wonder whether they're actually talking to them, because no phone can be seen. This situation could mean that Cueball has been hearing and / or talking to this person, who might not even be his acquaintance, given that he knows people that Cueball doesn't seem to know about, and that he might not actually be his friend. This is a hilarious exaggeration of people with some attention problems. The title text is an allusion to 476: One-Sided , where Randall doesn't realize who the other person is talking to. In 302: Names Cueball also has difficulty with names. The problems with bluetooth headsets' inconspicuousness is a key point in 736: Cemetery . Another example of not knowing someone is talking on the phone: [1] [Cueball is walking from left to right while Hairy follows him.] Hairy: ...I'm getting a ride with Katie to Adam's wedding. Hoping to see Brian on the way! Cueball: Oh, that's cool! Cueball: ...I can't keep living this lie, so I'm just gonna come out and admit it: I have no idea who any of the people you keep mentioning are.

Anti-Drone Eagles

Anti-Drone Eagles

https://www.xkcd.com/1842

https://www.explainxkcd.com/wiki/index.php/1842:_Anti-Drone_Eagles

[Black Hat, Cueball and Megan are standing and talking.] Cueball: Everyone loves these eagles that take down drones, but... I dunno. Megan: You gotta admit, it's pretty cool. [Close-up of Cueball.] Cueball: Yeah, but... training rare animals to hurl themselves at whirling machinery can only get us so far, you know? [In a frame-less panel the setting is back to that of the first panel.] Cueball: At some point, it's like releasing police dogs onto freeways to attack speeding motorcycles. Megan: Also cool, but I see your point. [Black Hat lifts his hand and Cueball turns his face towards him.] Black Hat: Plus, I just finished my autonomous drone that hunts eagles. Cueball: Man, you are an entirely separate class of problem.

Law enforcement and security agencies often use birds of prey to combat drones flying unlawfully over restricted sites. This is often more cost effective than using technological means (such as scramblers and counter-drones) and safer for the public than using conventional weaponry (such as shotguns). Eagles, being predators, have natural tendencies to attack the central components of drones while avoiding the sharp and spinny bits. Cueball argues that this is unethical as it forces rare animals to put their lives at risk, and compares it to using police dogs for traffic control, which people would generally frown upon. Effectiveness depends upon the conditions of use. Obviously eagles can't be used everywhere that drones are restricted, but they are often effectively used where ground security is also present to identify and arrest those that might be unlawfully flying the drones, so they can't indefinitely replenish their hardware. The first paragraph has links to real life examples. Not only would it be unethical, but also ineffective. The supply of Eagles is rather limited, and there are biological limits to how fast it can be replenished, whereas more drones can be created very quickly to replace those that are destroyed. Traffic control dogs would be similarly ineffective, as dogs would struggle to run as fast as a speeding motorcycle, and would be powerless to stop the motorcycle even if they could. Megan thinks both ideas (eagles and dogs) sound cool, but she understands the ethical argument against using them for traffic control. Black Hat , on the other hand, goes a step further and says that he has created a drone that hunts the eagles, flipping the premise from “anti-drone eagles” to “anti-eagle drones”. In the title text, he continues that is ethical because they (only the title text mentions that there are several of such drones) only target the most populous species first, although they will eventually eradicate the endangered ones once they bring down the number of all birds of prey (note that this implies that he wants to make all birds of prey extinct or endangered). He seems to miss the point that it is not merely the relative number of birds that creates the ethical problem, but the fact that animals' lives are being put at direct risk by humans. His construction of the anti-eagle drone may be simply for the point of making the eagles' goals not only dangerous, but also entirely ineffective. This is probably not an opposition to privacy but merely his trademark classholery in action. Nevertheless, Black Hat raises a crucial point in ecology : There are generalist and specialist predators (as well as herbivores). A specialist hunts or eats only one species (e.g. the koala eats only eucalyptus ), while a generalist hunts or eats the most available food. Thus, a generalist often spares species that have become rare due to overhunting, disease or famine. A generalist predator (or herbivore) thus manages the wildlife, and a healthy population of generalists is almost always beneficial. Now, if Black Hat creates a drone that hunts the most available species, he gets the right idea (a food generalist manages wildlife), but gets the other one seriously wrong: Eagles are already doing their job as generalists, and as predatory birds are not so abundant, a generalist that feeds on predatory birds would need to have a very large territory. And as drones cannot reproduce yet and do not need to hunt as an energy source, releasing a drone to fulfil an ecological role would not make any sense. How does the drone know it has hunted enough eagles? Does the eagle-hunting drone feel hunger and decide to hunt elsewhere after reducing the number of local eagles, or does it just hibernate? [Black Hat, Cueball and Megan are standing and talking.] Cueball: Everyone loves these eagles that take down drones, but... I dunno. Megan: You gotta admit, it's pretty cool. [Close-up of Cueball.] Cueball: Yeah, but... training rare animals to hurl themselves at whirling machinery can only get us so far, you know? [In a frame-less panel the setting is back to that of the first panel.] Cueball: At some point, it's like releasing police dogs onto freeways to attack speeding motorcycles. Megan: Also cool, but I see your point. [Black Hat lifts his hand and Cueball turns his face towards him.] Black Hat: Plus, I just finished my autonomous drone that hunts eagles. Cueball: Man, you are an entirely separate class of problem.

Opening Crawl

Opening Crawl

https://www.xkcd.com/1843

https://www.explainxkcd.com/wiki/index.php/1843:_Opening_Crawl

[On a black background with many stars is five blocks of yellow text that recedes towards a black section at the back of the panel. The last block cannot be read, but it is (almost) possible to read the second block of text at the back. The bottom line of the last text block is cut off through the middle of the letters.] "All systems show battle ready, Admiral," the comm officer reported from the portside crew pit. "The task force is beginning to check in." "Very good, Lieutenant," Grand Admiral Thrawn nodded. "Inform me when all have done so. Captain Pellaeon?" "Sir?" Pellaeon said, searching his superior's face for the stress the Grand Admiral must be feeling. The stress he himself was certainly feeling. This was not just another tactical strike against the Rebellion, after all—not a minor shipping raid or even a complex but straightforward hit-and-fade against some insignificant planetary base. After nearly a month of frenzied preparations, Thrawn's master campaign for the Empire's final victory was about to be launched. But if the Grand Admiral was feeling any tension, he was keeping it to himself. "Begin the countdown," he told [Cut off through the middle and at the end]: Pellaeon, his voice as calm as if he were ordering [Caption beneath the panel:] Movie theater projection booth prank: see how many pages of a Star Wars novel you can get people to read before they figure out there's no movie coming after it.

Each episodic Star Wars film begins with an " opening crawl " giving the audience some of the backstory, which often reads like the prologue of a novel. Randall wants to reverse this by projecting the text of a Star Wars novel and see how long this can be continued before viewers realize it is a prank. The text in the opening scroll is actually from the beginning of the final book of the Thrawn Trilogy by Timothy Zahn. The title text compares different Star Wars novels' style, remarking on how well suited they would be for this prank. Timothy Zahn is a science fiction writer who has written and contributed to many novels and comics in the Star Wars expanded universe . The text in the comic is the first five paragraphs from the book The Last Command . The characters mentioned are Grand Admiral Thrawn , the primary antagonist of the Thrawn Trilogy , and Gilad Pellaeon , who serves as a Dr. Watson -type companion to Thrawn throughout much of the trilogy. Splinter of the Mind's Eye was an early Star Wars novel written before the original film was expanded to a trilogy (and then expanded some more), so it contains multiple aborted subplots which can make it very confusing for a fan who has seen the later works. The term "EU" refers to "Expanded Universe", which was the term for the corpus of non-cinematic Star Wars content before Star Wars was acquired by Disney . Not wanting to be constrained by previous canon, Disney declared all "Expanded Universe" content to be non-canonical to all future movies, and re-branded the EU as "Legends" to take place in its own alternate continuity. For a very long time, fans believed that the Thrawn Trilogy would have constituted Star Wars VII to IX should the movie have been made and thus "before they figure out there's no movie coming after it" refers to both the mistaken belief of fans and the novelisation as delivered through the opening crawl. [On a black background with many stars is five blocks of yellow text that recedes towards a black section at the back of the panel. The last block cannot be read, but it is (almost) possible to read the second block of text at the back. The bottom line of the last text block is cut off through the middle of the letters.] "All systems show battle ready, Admiral," the comm officer reported from the portside crew pit. "The task force is beginning to check in." "Very good, Lieutenant," Grand Admiral Thrawn nodded. "Inform me when all have done so. Captain Pellaeon?" "Sir?" Pellaeon said, searching his superior's face for the stress the Grand Admiral must be feeling. The stress he himself was certainly feeling. This was not just another tactical strike against the Rebellion, after all—not a minor shipping raid or even a complex but straightforward hit-and-fade against some insignificant planetary base. After nearly a month of frenzied preparations, Thrawn's master campaign for the Empire's final victory was about to be launched. But if the Grand Admiral was feeling any tension, he was keeping it to himself. "Begin the countdown," he told [Cut off through the middle and at the end]: Pellaeon, his voice as calm as if he were ordering [Caption beneath the panel:] Movie theater projection booth prank: see how many pages of a Star Wars novel you can get people to read before they figure out there's no movie coming after it.

Voting Systems

Voting Systems

https://www.xkcd.com/1844

https://www.explainxkcd.com/wiki/index.php/1844:_Voting_Systems

[White Hat and Ponytail are standing on either side of Cueball who is talking while lifting one hand.] Cueball: I prefer approval voting, but if we're seriously considering instant runoff, then I'll argue for a Condorcet method instead. [Caption beneath the panel:] Strong Arrow's theorem: The people who find Arrow's theorem significant will never agree on anything anyway.

This comic is about types of single-winner voting systems: Arrow's impossibility theorem gives a list of criteria for ranked voting systems and states that no system can satisfy all of them at once, despite that for each of them it may seem "obvious" that an electoral system ought to satisfy it. Some voting theorists (such as Cueball) dislike IRV because it fails more of the criteria than Condorcet does. The primary joke in the comic is the premise that people who are pedantic or knowledgeable enough to find Arrow's theorem to be relevant will self-fulfill the theorem by being inclined to disagree on any effort to change the voting system. This is illustrated by Cueball's voting system preference that is contingent on the preferences of other people, which defeats their effort to produce a community-wide ranking. A secondary joke in the comic is that often voters don't pick their favorite choice in a vote. Instead, they vote for a less favorable, but more likely electable, person as a way to prevent their least favorite choice from being elected. This is commonly called "spoiler effect"; in Arrow's parlance it is a form of IIA criterion failure . Cueball's strategic vote switch implies that they may be using FPTP (which they dislike) to make the decision, as FPTP is the only system to involve a potential "spoiler effect" (note, however, that certain vote distributions in systems such as IRV can produce a similarly problematic and illogical effect on the outcome). A third joke is the recursive self-referencing inherent in voting to choose a voting system. The title text stipulates that Cueball has no fixed ranking of preference for human candidates, but makes this choice dependent on which voting system is favoured by the group. This exceeds strategic voting considerations as the ranking should have full information, whom Cueball prefers in each situation. Therefore Arrow's impossibility theorem and the analysis behind it assume the ranked preferences of an individual voter as a fixed given. To make them dependent on the voting system makes assessing the efficacy of the voting systems absurd or at least much more complicated to do as a general assessment. That is given as the reason why Arrow would wholeheartedly hate him. [White Hat and Ponytail are standing on either side of Cueball who is talking while lifting one hand.] Cueball: I prefer approval voting, but if we're seriously considering instant runoff, then I'll argue for a Condorcet method instead. [Caption beneath the panel:] Strong Arrow's theorem: The people who find Arrow's theorem significant will never agree on anything anyway.

State Word Map

State Word Map

https://www.xkcd.com/1845

https://www.explainxkcd.com/wiki/index.php/1845:_State_Word_Map

[Caption above the map, with sub caption:] Most-Used Word in Each State Based on Something Something Search Data [Beneath the captions are a colorful map of the United States of America. Each state has one color, but the colors do not change from state to state, but rather between rows of states. The top "row" is purple, the second row is gray-blue, but only goes half across. Where it stops a pink row of states begins. Beneath this runs a yellow row, except it does not take California with it, since it belongs to the next purple line beneath this yellow line. Finally the two states not in the contiguous states as well as the southern states from Texas to Florida are again pink. Inside each state is written one, and only one word (or for small states the word is outside and if needed a line indicates which state it belongs to). The words size depends on the size of the state and the word. If it can fit inside the state it will be written in a font large enough to fill the entire state if possible (in one case a hyphen is used). So a short word, like "lets" in huge Texas becomes huge, but a word like "noise" which has been fitted inside small Massachusetts becomes small.] [Here are the 50 words written in lines resembling the colors on the map (from left to right). Purple, gray-blue, pink, yellow, purple and pink:] You can make these maps say whatever you want by adjusting the methodology. Half the time you're just amplifying random noise. Because the underlying data doesn't vary that much from one state to another. But whatever. Nobody checks this stuff. Just pick whatever normal-ization lets you make fun of Florida.

This is another of the many comics where Randall used a map of the United States for his joke (see below for examples). Similar in spirit to 1138: Heatmap , this comic pokes fun at many maps that attempt to use data to discern unique characteristics about various sub-regions, in this case American states . This map may have been inspired by this map posted on Twitter by Google Trends the day before the comic was posted. Many web companies use maps like this in viral marketing, but the methodology behind them is pretty weak. The random noise in the data will mean that there will be variations between states even if there is no underlying pattern - and this can be further boosted by statistical tricks. A common one is to show the "most characteristic" or "most distinctive" term for each state. For instance, the most common cause of death is heart disease or cancer in every US state, but this makes for a boring map. Looking at the most distinctive cause of death produces a more interesting map, but it highlights very minor trends - Lousiana is marked as having syphilis as its most distinctive cause of death, even though only 15 Louisianans in every 100,000 have the disease and there were only 22 syphilis deaths in the state over a whole decade. These maps can give a misleading impression of huge variation between states that doesn't really exist. This map does not include real data, but says (when read left to right/west to east): You can make these maps say whatever you want by adjusting the methodology. Half of the time you're just amplifying random noise because the underlying data doesn't vary that much from one state to another. But whatever. Nobody checks this stuff. Just pick whatever normalization lets you make fun of Florida. The primary joke is that the likelihood of these being the words used most often by the inhabitants of each state is low, rather than accurately representing the most used words Randall has just done exactly what he says he can do (make fun of Florida by putting whatever he wants). He also has not obtained the data from anywhere, just 'Something Something'. The joke about Florida is that the most used word in Florida is "Florida", which would make people in Florida very self-centered. The comic continues to make fun of Florida in the title text by saying that Florida searches for sex porn instead of porn , which is not needed since porn means images and film of people having sex. This is also probably a reference to PornHub's data-farming exercises, where they have periodically released the most frequently searched term by state. Florida is often the butt of many jokes, including the Florida Man meme and many mocking jibes regarding its messy electoral history . For more information on why Florida itself seems eager to play into this stereotype, check out the "Only in Florida" phenomenon Randall previously used a map of the United States as the basis for his comics in 1767: US State Names , 1653: United States Map , 1509: Scenery Cheat Sheet and in 1079: United Shapes . [Caption above the map, with sub caption:] Most-Used Word in Each State Based on Something Something Search Data [Beneath the captions are a colorful map of the United States of America. Each state has one color, but the colors do not change from state to state, but rather between rows of states. The top "row" is purple, the second row is gray-blue, but only goes half across. Where it stops a pink row of states begins. Beneath this runs a yellow row, except it does not take California with it, since it belongs to the next purple line beneath this yellow line. Finally the two states not in the contiguous states as well as the southern states from Texas to Florida are again pink. Inside each state is written one, and only one word (or for small states the word is outside and if needed a line indicates which state it belongs to). The words size depends on the size of the state and the word. If it can fit inside the state it will be written in a font large enough to fill the entire state if possible (in one case a hyphen is used). So a short word, like "lets" in huge Texas becomes huge, but a word like "noise" which has been fitted inside small Massachusetts becomes small.] [Here are the 50 words written in lines resembling the colors on the map (from left to right). Purple, gray-blue, pink, yellow, purple and pink:] You can make these maps say whatever you want by adjusting the methodology. Half the time you're just amplifying random noise. Because the underlying data doesn't vary that much from one state to another. But whatever. Nobody checks this stuff. Just pick whatever normal-ization lets you make fun of Florida.

Drone Problems

Drone Problems

https://www.xkcd.com/1846

https://www.explainxkcd.com/wiki/index.php/1846:_Drone_Problems

[Megan is sitting on her knees at the porch in front of a house with a smartphone in one hand and operating with her other hand a dish-antenna pointing into the sky. Cueball comes walking up towards the stairs up to the porch while he is looking back and up over his shoulder and pointing into the air.] Megan: People in the park keep flying drones near me, so I've built a system to shoot them down. Cueball: Cool! Oh yeah, there's one now. Megan: Time for a test! [Zoom in on Megan with the device on the porch with Cueball still at the bottom of the stairs leading down. She is operating her phone, which can be seen to be connected with a wire to the dish-antenna device. Cueball is looking away from her and down.] Megan: Okay, locking on… Cueball: Wait, it just crashed. Megan: Damn. [Cueball has walked up the stairs and are standing behind Megan at the door. Megan is now looking up into the sky while still sitting with her phone in front of the device.] Cueball: Here comes another one! Aim for… nope, it got stuck in a tree. [Cueball is now sitting on the porch with a half-full drinking glass in one hand leaning back on the other hand. Megan is gesturing at her device while holding her phone down. Above the top part of the frame, there is another smaller frame overlaid with a caption:] Three hours later… Cueball: Finally, two more just— no, one crashed and the other is hurtling sideways toward the lake. Megan: Will you people learn to fly these things?!

Megan is frustrated because people are flying drones too close to her, so she builds a system to shoot them down. She shows it to Cueball , who is also excited about the idea and helps spot the drones. However, each of the drones gets accidentally destroyed by its pilot because of their inability to fly the drones before Megan can destroy them herself. After three hours of unsuccessful drone hunting, a frustrated Megan complains about people unable to fly the drones, which prevents her (and Cueball) from having fun shooting them down. The joke is that she created the system to get rid of the drones, so the lack of drones should be the desired output - and now she wants the drones nearby (even if only temporarily). This comic is a follow up on 1842: Anti-Drone Eagles , and confirms that Cueball prefers technological air-defense systems to biological measures. The title text refers to the fact that from the pilots' perspective, the system is successful at keeping all the drones away from the house, even though in reality the system has not had a chance to be successful yet. While Megan attributes the repeated drone crashes to poor pilot skill, a possible source for the drones' sudden loss of control is hinted at in panel two, in which the target drone crashes immediately after Megan's device (equipped with a miniature parabolic dish) attempts to "lock on" to the drone in question. While a small and fast-moving drone may be difficult to hit, the control system that directs its movements is easily interfered with (either by overwhelming the RF signal controlling it or by using microwaves to induce short circuits in sensitive electronics). The irony here is that the targeting system for Megan's anti-drone device unintentionally appears to be more effective than the actual weapon it is designed to guide, disabling the drones so quickly that the "real" weapon is unable to be tested. It may also be a reference to the May 30, 2017 FTG-15 test of the United States GMD missile defense system, where an interceptor kill vehicle destroyed a test ICBM . From the perspective of a US adversary, such as North Korea (whose missiles the system is allegedly targeted at), "as far as they know, the system is working perfectly," as the test was declared to be a success. But substantial controversy has dogged the missile defense system for decades, as critics have alleged it is vulnerable to trivial countermeasures . But "as far as they know" strongly implies that the text following it is not true, i.e. the system does not work perfectly. Another possible secondary joke is that the drones were flying near her because the pilots can't fly properly. Yet another possible take on the joke is that Megan's system is actually effective, but Megan is not aware it's been activated. Megan had previously suggested in 1586: Keyboard Problems , that robots (and thus also drones) getting near Cueball's house ( and possibly Cueball's general vicinity ) would unexpectedly crash. Megan previously had a laser cannon to shoot down squirrels in 382: Trebuchet , so this is not the first time she has built a device for shooting things down. [Megan is sitting on her knees at the porch in front of a house with a smartphone in one hand and operating with her other hand a dish-antenna pointing into the sky. Cueball comes walking up towards the stairs up to the porch while he is looking back and up over his shoulder and pointing into the air.] Megan: People in the park keep flying drones near me, so I've built a system to shoot them down. Cueball: Cool! Oh yeah, there's one now. Megan: Time for a test! [Zoom in on Megan with the device on the porch with Cueball still at the bottom of the stairs leading down. She is operating her phone, which can be seen to be connected with a wire to the dish-antenna device. Cueball is looking away from her and down.] Megan: Okay, locking on… Cueball: Wait, it just crashed. Megan: Damn. [Cueball has walked up the stairs and are standing behind Megan at the door. Megan is now looking up into the sky while still sitting with her phone in front of the device.] Cueball: Here comes another one! Aim for… nope, it got stuck in a tree. [Cueball is now sitting on the porch with a half-full drinking glass in one hand leaning back on the other hand. Megan is gesturing at her device while holding her phone down. Above the top part of the frame, there is another smaller frame overlaid with a caption:] Three hours later… Cueball: Finally, two more just— no, one crashed and the other is hurtling sideways toward the lake. Megan: Will you people learn to fly these things?!

Dubious Study

Dubious Study

https://www.xkcd.com/1847

https://www.explainxkcd.com/wiki/index.php/1847:_Dubious_Study

[Megan is standing behind Cueball who is sitting at a computer desk using a laptop.] Megan: Are you sure this study is legit? Cueball: Sure, it says it was accepted for publication. Megan: Where? Cueball: Hmm... The National Academy of Proceedings . [Caption below the panel:] If something is formatted like a serious scientific paper, it can take me a while to realize it isn't one.

This comic alludes to the growing industry in disreputable academic journals , many of whom accept articles of dubious merit for publication without rigorous peer review upon payment of a fee. In an attempt to sound legitimate (and thus attract submissions), many such publishers publish journals whose names sound intentionally similar to (if not identical to) established titles. Here, the National Academy of Proceedings is a meaningless title that sounds similar to the highly regarded academic title Proceedings of the National Academy of Sciences, USA . In the caption, Randall points out that even he is sometimes fooled into believing a study is serious because it is well-formatted and looks professional, at least at first. Even though he eventually realizes the study is dubious, sometimes it's only after reading a significant portion of the paper. A possible unstated concern Randall may have is that some readers might never realize this and end up believing whatever results and conclusions are included in the paper, thereby leading to a belief in false or misleading information among some portion of the population. The title text implies that this (at present) fictional journal has a dubious online presence in the faded internet site MySpace , where the publishers make claims that may be true but are misleading: "peer-viewed" sounds similar to " peer-reviewed ", the community-led process of establishing a paper's scientific integrity prior to publication, but in fact means only that scientists have viewed the content (as Cueball is now). Likewise, some journals might be "published biannually", whereas "downloaded biannually" implies that the journal is read only twice each year. Single articles in high-profile journals such as Proceedings of the National Academy of Sciences would expect to receive hundreds to thousands of views in their first year of publication. The fictional journal publisher no doubt hopes that an inexperienced scientist may mistake these claims for meaningful statements of authority, and thus submit a paper (and eventually pay a fee for its publication). The National Academy of Proceedings in fact sets itself apart from certain predatory journals by ensuring that the claims on its website are in fact factually accurate (if phrased to mislead article authors, particularly those with English as an additional language); some journals are openly dishonest on their websites. Randall also judges academic content based on superficial details in comic 1301: File Extensions , where he focuses on how the information is formatted (in particular if it is in TeX or with the TeX rendering-style of a scientific publication). Similarly, in 906: Advertising Discovery , Randall muses on how we automatically trust anything formatted in Wikipedia style. (This was later proven in a scientific study. [1] ) And on a different note, prestigious-sounding but meaningless names also appear in the title text for 1068 , where SwiftKey suggests the phrase "Massachusetts Institute of America" to Randall. [Megan is standing behind Cueball who is sitting at a computer desk using a laptop.] Megan: Are you sure this study is legit? Cueball: Sure, it says it was accepted for publication. Megan: Where? Cueball: Hmm... The National Academy of Proceedings . [Caption below the panel:] If something is formatted like a serious scientific paper, it can take me a while to realize it isn't one.

Glacial Erratic

Glacial Erratic

https://www.xkcd.com/1848

https://www.explainxkcd.com/wiki/index.php/1848:_Glacial_Erratic

[Ponytail and Megan walks up to a large rock, Ponytail points at it.] Ponytail: That rock is a glacial erratic-A glacier broke it off from those hills and placed it here. [In a frame-less panel they stand and watch the rock.] Megan: What? And just left it here? Megan: And everybody's okay with this? [Megan tries to lift the rock with two hands.] [Megan turns her back to the rock and tries to push it with all her might.] Megan: Get... Megan: ...back... [Ponytail looks on as Megan again has turned around and tries to roll the boulder using both hands.] Ponytail: Why ... Why are you doing that? Megan: Because fuck glaciers!

Ponytail and Megan are walking along when they come across an erratic rock (which differs from the surrounding geology and is brought there by glacial action ). Not wishing to bow down to the forces of nature, Megan tries to take it back to its rightful place, obviously in vain. Megan is annoyed with the glacier for just littering the place up with rocks. She wishes to put it back in place, just like picking up a piece of litter and putting it in the trash bin where it belongs. The title text furthers the absurdity by suggesting that Megan is extra annoyed with having to clean up after the glacier, because it will take a long time (and as she put it "Fuck Glaciers"). The problem for Megan is that she is already using her time chiselling out igneous intrusions which is another type of rock formation caused by solidification of magma , which Megan also plans to undo. To soothe her mind she keeps watching the scene from the Superman film where Superman turns back time to prevent an earthquake and thus also create a fault-sealing by reversing the creation of the fault in the first place. He also prevents the destruction of the Hoover Dam and the death of Lois Lane , but it seems like this is not important to Megan. She is only interested in undoing what nature has already done, and if the Superman scene could be made real it would solve her problems. This may be a play on words based on the word "erratic," as Megan's behavior could be described as such. Megan's actions here are reminiscent of the ones carried out by Cueball in 1119: Undoing . [Ponytail and Megan walks up to a large rock, Ponytail points at it.] Ponytail: That rock is a glacial erratic-A glacier broke it off from those hills and placed it here. [In a frame-less panel they stand and watch the rock.] Megan: What? And just left it here? Megan: And everybody's okay with this? [Megan tries to lift the rock with two hands.] [Megan turns her back to the rock and tries to push it with all her might.] Megan: Get... Megan: ...back... [Ponytail looks on as Megan again has turned around and tries to roll the boulder using both hands.] Ponytail: Why ... Why are you doing that? Megan: Because fuck glaciers!

Decades

Decades

https://www.xkcd.com/1849

https://www.explainxkcd.com/wiki/index.php/1849:_Decades

[A timeline across the top of the box marks decades from 1960 to 2030, the labels are above the line and the ticks marking each decade are below.] [Label: 1960] 60s Music; 60s Fashion; 60s Movies; 60s Culture [Label: 1970] 70s Music; 70s Fashion; 70s Movies; 70s Culture [Label: 1980] 80s Music; 80s Fashion; 80s Movies; 80s Culture [Label: 1990] 90s Music; 90s Fashion; 90s Movies; 90s Culture [Label: 2000 and 2010] [Items grouped over two decades.] Fashion; Culture; Music; Movies [Label: 2020] [The text is in light grey font.] 20s Music?; 20s Fashion?; 20s Movies?; 20s Culture? [Label: 2030] [Caption below the panel:] It's weird how for 20 years we stopped grouping our cultural memories by decade because "2000s" is ambiguous and and "Aughts" and "Teens" never really stuck.

This comic shows, by use of a timeline, an interesting phenomenon where music, fashion, movies and culture created between the years 2000 and 2020 are not commonly grouped into the decade in which they were produced like previous decades. The comic asserts the reason for this is the lack of a single clear term to describe these decades, stating that the term " 2000s " is ambiguous (as it could refer to the decade, century or millennium as a whole) and the terms " Aughts " and "Teens" never became the widely accepted terms for these decades. The time-line in the comic stretches into the future (as of the time of publication) and attempts to name the 2020-2029 decade as the 20s, but does so with an uncertain question mark, presumably because it's (presently) an open question whether this dating convention will be reinstated after a 20-year pause. As the comic points out, common vernacular has managed to operate without clear terms for that grouping for 17 years, and that may have left enough of a mark on our thinking that we'll simply continue to operate in that way. There's an argument to be made grouping culture by decades is fairly arbitrary and not essential in cultural discussions. It should also be considered that that "the twenties" is still occasionally used to refer to the 1920s, and so reusing it to refer to the 2020s could be a source of confusion. It's not impossible that decade-based grouping will fall out of favor altogether in the 21st century. It should perhaps also be noted that culture (particularly when associated with young people) in the 2000s and 2010s is often termed " millennial culture ", although this term frequently comes with negative connotations. The title text talks about Randall's local radio station. Until the 90s, they were able to use clear decade groupings to classify music. Once the year 2000 hit, they began saying "today", avoiding aughts or 2000s, which, as Randall says, never gained popular support. Instead of adopting a term for the 2010s, they simply continued to use "today" to refer to everything after the 1990s (this practice has been fairly common on American radio stations). Randall expresses interest in what change they will include in the 2020s (changing to the 20s or continuing their format), but includes a comedic jab at radio, suggesting that the medium might not last that long. The increasing speed and ubiquity of the internet, combined with compact digital music storage, has made radio programming increasingly obsolete in the United States and other wealthy countries. That said the joke is still based on exaggeration to an extent, since commercial radio is unlikely to disappear entirely in the next three years, but is likely to become less and less viable as an industry over time and what remains or springs from the ashes will likely shift radically in its format and delivery. Twenties were discussed again later in 2249: I Love the 20s . [A timeline across the top of the box marks decades from 1960 to 2030, the labels are above the line and the ticks marking each decade are below.] [Label: 1960] 60s Music; 60s Fashion; 60s Movies; 60s Culture [Label: 1970] 70s Music; 70s Fashion; 70s Movies; 70s Culture [Label: 1980] 80s Music; 80s Fashion; 80s Movies; 80s Culture [Label: 1990] 90s Music; 90s Fashion; 90s Movies; 90s Culture [Label: 2000 and 2010] [Items grouped over two decades.] Fashion; Culture; Music; Movies [Label: 2020] [The text is in light grey font.] 20s Music?; 20s Fashion?; 20s Movies?; 20s Culture? [Label: 2030] [Caption below the panel:] It's weird how for 20 years we stopped grouping our cultural memories by decade because "2000s" is ambiguous and and "Aughts" and "Teens" never really stuck.

Air Force Museum

Air Force Museum

https://www.xkcd.com/1850

https://www.explainxkcd.com/wiki/index.php/1850:_Air_Force_Museum

[Megan walks from left over to Cueball.] Megan: How was your day? Cueball: I visited the military aircraft museum over at the Air Force base. It was really neat! [Both walking together to the right.] Cueball: They have planes from different eras, all kinds of cool equipment, and you can even watch missiles being loaded. [Beat frameless panel. Cueball and Megan walking.] [Both still walking.] Cueball: ...at least, I hope that was a museum. Megan: Do you hear helicopters?

Megan asks Cueball about his day. He tells about his visit to a military aircraft museum at the air force base and lists some of the things he saw. It starts with things you would expect at a typical museum, such as a mix of aircraft from different eras, before revealing the fact that Cueball was able to watch missiles being loaded, which is something that would be out of place and potentially dangerous at a museum. Realizing this, Cueball remarks that he hopes that he was at a museum, and Megan asks him if he hears helicopters. The implication is that Cueball observed the actual military operations at the base; the sound of helicopters might imply Cueball is now being pursued by the military, or may simply be evidence of some military operation potentially related to what Cueball observed. The mention of "planes from different eras" alludes to the fact that military aircraft are often still in use after a much longer time than they were originally designed for. An example of this are the US Air Force's B-52 bomber, first introduced in 1955 (62 years before the publication of this comic) and expected to serve into the 2040s. Additionally, aircraft museums typically house military aircraft from previous eras, such as from WWII and the Cold War, to show the evolution in aircraft design and to showcase technological advances. The title text builds on this premise. Randall says that he had fun visiting another Air Force "museum", but he adds that if they don't have a museum (in which case he was trespassing on a military base) then he denies ever having been anywhere near it. Fortunately for Randall, there is in fact an Air Force museum nearby: the Air Mobility Command Museum about half a mile south of the Dover Air Force Base . [Megan walks from left over to Cueball.] Megan: How was your day? Cueball: I visited the military aircraft museum over at the Air Force base. It was really neat! [Both walking together to the right.] Cueball: They have planes from different eras, all kinds of cool equipment, and you can even watch missiles being loaded. [Beat frameless panel. Cueball and Megan walking.] [Both still walking.] Cueball: ...at least, I hope that was a museum. Megan: Do you hear helicopters?

Magnetohydrodynamics

Magnetohydrodynamics

https://www.xkcd.com/1851

https://www.explainxkcd.com/wiki/index.php/1851:_Magnetohydrodynamics

[Ponytail holding her hands up is facing Cueball and Megan .] Ponytail: The Sun's atmosphere is a superhot plasma governed by magnetohydrodynamic forces... Cueball: Ah, yes, of course. [Caption below the panel:] Whenever I hear the word "magnetohydrodynamic" my brain just replaces it with "magic."

In this comic, Ponytail explains to Cueball that the Sun's atmosphere is a super hot plasma controlled by " magnetohydrodynamics " (a real word), the study of magnetic properties of electrically conducting fluids. This is true, as plasma is both electrically charged (following the laws of electrodynamics) and a fluid (following the laws of hydrodynamics). However, the combination is so difficult for Cueball that he finds it easier to comprehend any statements containing the word "magnetohydrodynamic" by dropping the central part of the word ("netohydrodynam"). Thus, he pretends that Ponytail instead said "The Sun's atmosphere is a superhot plasma governed by magic forces". If Cueball really thinks that magic is more comprehensible than magnetohydrodynamics, then considering just how vaguely and inconsistently magic is portrayed across fiction, that must mean that magnetohydrodynamics is really, really hard! [ citation needed ] In the title text, Randall riffs on the sheer difficulty of magnetohydrodynamics, claiming that they are as simple and understandable as Maxwell's equations and the Navier–Stokes equations -- which is to say, not at all. Maxwell's equations require an advanced knowledge of calculus to even be able to interpret the symbols used, and the solutions of Navier–Stokes equations are on the Millennium Problems list . Randall also notes the alarming frequency with which the subject of magnetohydrodynamics is paired with quantum mechanics and the theory of relativity ; he sarcastically quips that physicists must find magnetohydrodynamics so easy to work with, since they're so compelled to spice it up. [Ponytail holding her hands up is facing Cueball and Megan .] Ponytail: The Sun's atmosphere is a superhot plasma governed by magnetohydrodynamic forces... Cueball: Ah, yes, of course. [Caption below the panel:] Whenever I hear the word "magnetohydrodynamic" my brain just replaces it with "magic."

Election Map

Election Map

https://www.xkcd.com/1852

https://www.explainxkcd.com/wiki/index.php/1852:_Election_Map

[On a TV-screen Cueball is seen pointing at a map on the left which is colored in red and blue. There is a header on the map and in the top right corner of the screen the title of the program is shown. Below this at the bottom of the screen text indicate that the program is broad live. Cueball explains the map, with his text shown above the TV.] Header: Results Title: Election Night Live Cueball: These northern precincts appear red, which probably means they're moving away from us, whereas these bluer regions are approaching us. I believe the district may be rotating in space. [Caption below the panel:] My career as an election analyst was short-lived.

A wave (e.g. an electromagnetic wave, like light) changes its frequency and wavelength when its source is moving relative to the observer, due to the Doppler effect . In the case of light, increased frequency — indicating movement towards the observer — is called blueshift , while reduced frequency — indicating movement away from the observer — is called redshift . These names apply even if the effect is outside of the visible spectrum (e.g. infrared light that has reduced frequency is called redshifted, even though its frequency is further away from that of visible red light than normally). Red and blue colors are used accordingly to indicate the effect. The recent advent of the integral field spectrograph allowed astronomers to produce images illustrating how different parts of a galaxy move along our sightline, images that look not very different from the map Cueball shows. If one side of the image is higher redshifted while the other side is less or even blueshifted, the usual interpretation is that the galaxy is rotating with an axis of rotation not completely parallel to our sightline, but other interpretations are also possible. Nevertheless no redshifted object appears in red to the human eye, it's still white. But the spectral lines are shifted. This means all colors used in those scientific images are not real. The map Cueball shows represents election results. Red regions mark where one of the political parties won, while blue regions indicate another party. (Because Randall lives in the United States, blue most likely corresponds to the Democratic Party , and red to the Republican Party , but this is not stated in the comic.) Cueball, however, analyzes the map as if it showed the magnitude of Doppler effect by the light emitted by the region. This is a very strange interpretation in the context of an election, and is not what the viewers would expect to hear. This is why Cueball was quickly fired from his job, as the caption states. The title text states that the Green Party did not win any precincts . If the Green Party won, its regions would likely be colored green, which would not fit to Cueball's Doppler effect analysis. Sometimes, however, green is used to indicate lack of movement. And since the center of rotating object isn't moving, green-colored spaces could actually be interpreted according to Doppler analysis - but only if they appeared near the center of the rotation. The map appears to depict Georgia's 6th congressional district , which was set for a runoff election on June 20, 2017, the day after the comic ran. The map in the comic appears to be broadly similar to both the result maps of the primary ballot of April 18, 2017 and the result map of the runoff election . The April primary had included 5 Democratic candidates, 12 Republican candidates, and 2 independent candidates (who combined for less than 0.1% of the primary vote), with the top two finishers (who were a Democrat and a Republican) advancing to the runoff. The red-and-blue result maps were similar for the primary and runoff elections because the precincts where Democratic or Republican candidates predominated in the April vote also (generally speaking) tended to have the candidate of the same party lead the vote in June. [On a TV-screen Cueball is seen pointing at a map on the left which is colored in red and blue. There is a header on the map and in the top right corner of the screen the title of the program is shown. Below this at the bottom of the screen text indicate that the program is broad live. Cueball explains the map, with his text shown above the TV.] Header: Results Title: Election Night Live Cueball: These northern precincts appear red, which probably means they're moving away from us, whereas these bluer regions are approaching us. I believe the district may be rotating in space. [Caption below the panel:] My career as an election analyst was short-lived.

Once Per Day

Once Per Day

https://www.xkcd.com/1853

https://www.explainxkcd.com/wiki/index.php/1853:_Once_Per_Day

[Megan and Cueball are standing together, facing each other.] Megan: Got any plans for the day? Cueball: I'm going to eat an apple, an egg, one baby aspirin, and a piece of dark chocolate, drink six glasses of water, one glass of red wine, a cup of coffee, and a cup of tea, then do 30 minutes of exercise. Cueball: Then back to sleep for another 8 hours! [Caption below the panel:] I only do things that news stories have specifically told me to do once per day.

Many news reports on health recommend the "best" way to perform the processes, such as eating, drinking, exercising, or sleeping, that are required to live healthy. These reports tend to give such factors as a type of food to consume regularly, the amount of a nutrient to consume, or how long to exercise, in terms of what or how much to do daily. A simple example of this is the proverb, "An apple a day keeps the doctor away." Perhaps this kind of advice is overthinking things, but Cueball decides to follow it strictly as explained in the caption. So when Megan asks Cueball what his plans are, he just lists his routine consisting only of things that the news has told him exactly how often to do. His list includes the following, which he has to do once per day: Several obvious problems arise with these "you should do ... daily" tips. They are often based on population studies, but they may be harmful in the case of some individual persons. This health-related advice would be beneficial in, say, 60 or 70% of the population, but may be ineffective in other 20% of the people, and deleterious in 10%. This especially relates to the suggested daily intake of aspirin. The second problem is the shaky scientific foundation of this advice. There have been studies examining the effects of a daily glass of red wine, for example, but there is certainly no study which has observed the interaction of all ten of these health tips at once. In particular, tannins (which occur in red wine and coffee) are known to absorb certain substances, which may influence the way in which apples and eggs are digested. Furthermore the scientific basis for these articles are shaky at best. A large number of these studies are just junk science - poor methodology and bias making the study more attention-grabbing, but lacking real substance. Even those studies that are scientifically rigorous are often reported on poorly. "Study proves that dark chocolate helps you lose weight" is a better headline than "Several studies over the last five years hint that chocolate may have certain long term benefits; more research needed" Of course, if Cueball only does these things, then he can't/doesn't attend to other important matters, such as going to work, which most likely allows him to buy the recommended materials in the first place, or even using the toilet. Also, if Cueball only does these things, he will complete his "daily" schedule in significantly less than a day, probably between 8.5 and 9 hours. This means that he will do his "daily" schedule on average almost three times a day. One consequence is that Cueball will be drinking on average about 19 glasses of wine per week instead of 7 glasses of wine per week if he actually drank one glass of wine per day. While drinking 7 glasses of wine per week won't have any negative consequences as long as they are evenly or about evenly spaced, drinking more than fourteen servings of alcohol (where one glass of wine has one serving of alcohol) per week causes long-term liver damage. Also, it's not clear how Cueball is able to overpower his circadian rhythm in order to sleep for over twenty hours per day. Furthermore, while the routine is theoretically subject to change as soon as Cueball hears another such daily recommendation on the news, this won't happen because he hasn't heard a recommendation to tune in to the news every day, so poor Cueball is trapped in his daily schedule. In the title text Cueball explains that his daily routine is not completely fixed. It is broken twice a year, since he also follows public information campaigns suggesting the replacement smoke detector batteries twice a year. While the US National Fire Protection Association recommends a replacement at least once per year others suggest every time when the clock changes according to daylight saving time , i.e. twice a year. (All such recommendations will likely become irrelevant as citizens of the United States, starting in California, are encouraged to replace their existing smoke detectors with new models containing irremovable ten-year batteries.) This is just another example for official overdone recommendations nobody follows, in this case since smoke detectors make annoying beeps when their batteries run low and thus rarely need routine replacements before then. [Megan and Cueball are standing together, facing each other.] Megan: Got any plans for the day? Cueball: I'm going to eat an apple, an egg, one baby aspirin, and a piece of dark chocolate, drink six glasses of water, one glass of red wine, a cup of coffee, and a cup of tea, then do 30 minutes of exercise. Cueball: Then back to sleep for another 8 hours! [Caption below the panel:] I only do things that news stories have specifically told me to do once per day.

Refresh Types

Refresh Types

https://www.xkcd.com/1854

https://www.explainxkcd.com/wiki/index.php/1854:_Refresh_Types

[A table with three columns is shown. The header is:] Refresh Type; Example Shortcuts; Effect [First row:] Soft Refresh [The word refresh has a border to mimic a button:] Gmail REFRESH Button Requests update within JavaScript [Second row:] Normal Refresh [Two PC shortcuts and the Apple command key followed by an R:] F5, CTRL-R, ⌘R Refreshes page [Third row:] Hard Refresh [One PC shortcut, the combination Control plus Shift, and the Apple command key followed by Shift and R:] CTRL-F5, CTRL-⇧, ⌘⇧R Refreshes page including cached files [Fourth row:] Harder Refresh [One single combination using Control plus Shift plus Hyper plus Escape plus R plus F5:] CTRL-⇧-HYPER-ESC-R-F5 Remotely cycles power to datacenter [Fifth row:] Hardest Refresh [One single combination using Control plus the Apple command key plus the Windows key plus Shift plus the hash key plus R plus F5 plus F plus 5 plus Escape plus the letter O plus a slashed zero plus a slashed letter O plus an eject sign plus Scroll Lock:] CTRL-⌘ ⊞ ⇧#-R-F5-F-5-ESC-O-0-Ø-⏏-SCROLL LOCK Internet starts over from ARPANET

In this comic Randall presents five different levels of refresh operations for web applications. The first three ( soft refresh , normal refresh , and hard refresh ) are common operations to keep the content in the browser retrieved from the server up to date. The other two ( harder refresh and hardest refresh ) are fictional operations to perform refresh operations on remote resources. The terms are probably adopted from soft and hard reset operations used to restart broken computers or e.g. smartphones. Soft refresh refers to an operation in a web page, commonly known as Ajax , that requests new information without reloading the entire page. The given example, Gmail , includes a feature that allows users to poll new emails and show it in the inbox interface. It is a command using JavaScript to load new contents from the server in the background and only update necessary components of the page. Since modern web applications do this also automatically in short time intervals those buttons are mostly unnecessary. In Gmail a user will see a new message instantly. The normal refresh is a browser operation that reloads the complete web page, text and other content that has changed since the original load will be updated. The operation can be triggered by refresh buttons in browsers, though it also can be requested using the common keyboard commands as listed by Randall. Many pages -- like the main page at xkcd.com -- don't have a refresh button. If the page has been opened before a new comic release, pressing F5 afterwards causes reload and the new comic is shown. What Randall calls hard refresh is a less common browser operation forcing the browser to re-download every part of the web page, ignoring any cached content. Caching is a common way of decreasing web page load times. Browsers save resources such as images or CSS stylesheets on the first visit on a web page and use the local copy on subsequent visits. It allows them to decrease amount of transfer needed to show the web page, but can prevent showing changes made to the resources (for example a web developer changing the stylesheet). In those cases the hard refresh ensures that each part of the website is downloaded in its newest form. If there is a proxy or a cache (like used for this wiki) in between the browser and the server this type of refreshing may not work. In this case, unless a purge link is available, the user has to wait until the cache entry is expired and a new request to the web server is done. Someone may try to avoid this behavior by including special headers in the HTTP reply to control caching, but not all proxies or clouds follow these instructions. Harder refresh is a joke that extends the existing naming scheme. The joke is that if a hard refresh resets the browser display and cache, a harder refresh should reset the source of the data by cycling power in the data center. Assuming no damage was done, this would reset the memory on the server, erasing any information that had not been written to disk, and setting the server to the state it was in at launch. This would cause considerable downtime, and would be unlikely to help the user at all. In orchestrated environment it may indirectly cause some virtual machines in the cloud to be rebooted and assigned to an other web server needing more workload. But a growing workload is caused by hundreds or thousands additional requests and not just a single key combination from one browser. While there are administrative web tools allowing to perform a reboot (physical or virtual server) just by clicking a single button, this is not what is being referred to in the comic. A standard (non-administrative) user rebooting an actual physical server using a common web page is not possible, unless there is a software or operating system bug that will cause exactly this. This would be considered an extremely critical problem and its resolution would be given an extremely high priority by the server owners. The harder refresh uses six keys, including the non-standard ' HYPER ' key, a feature of the Space cadet keyboard . Hyper could also refer to the Linux modifier key Hyper, similar to Control, Alt, and Super. The fifth option, hardest refresh , moves beyond resetting the source of the data and resets the entire internet back to ARPANET , an early military network which was a forerunner to the modern internet. The implications of this are not made clear, but it should be noted that it wouldn't help to fix any problems a user is experiencing in-browser, as HTTP , the protocol by which web pages are sent, was not developed until late 1990, the year ARPANET was decommissioned. The hardest refresh shortcut uses fifteen keys, including non-standard ones such as Ø and ⏏. (The former is a key found on Danish and Norwegian keyboards, the latter is the "eject" key found on Mac keyboards and some laptops.) The shortcut makes amusing comparisons about a shortcut that includes not only the F5 function key, but also the keys for the letter "F" and the digit "5", as well as the similarity in appearance between O, 0, and Ø. The title text suggests that the inclusion of both the Windows key and Command key in the hardest refresh shortcut is a security measure akin to the Two-man rule , as it would require two keyboards to enter. Normally this would not work in practice as the modifier keys are handled per keyboard and not combined across keyboards for most operating systems allowing more than one keyboard. [A table with three columns is shown. The header is:] Refresh Type; Example Shortcuts; Effect [First row:] Soft Refresh [The word refresh has a border to mimic a button:] Gmail REFRESH Button Requests update within JavaScript [Second row:] Normal Refresh [Two PC shortcuts and the Apple command key followed by an R:] F5, CTRL-R, ⌘R Refreshes page [Third row:] Hard Refresh [One PC shortcut, the combination Control plus Shift, and the Apple command key followed by Shift and R:] CTRL-F5, CTRL-⇧, ⌘⇧R Refreshes page including cached files [Fourth row:] Harder Refresh [One single combination using Control plus Shift plus Hyper plus Escape plus R plus F5:] CTRL-⇧-HYPER-ESC-R-F5 Remotely cycles power to datacenter [Fifth row:] Hardest Refresh [One single combination using Control plus the Apple command key plus the Windows key plus Shift plus the hash key plus R plus F5 plus F plus 5 plus Escape plus the letter O plus a slashed zero plus a slashed letter O plus an eject sign plus Scroll Lock:] CTRL-⌘ ⊞ ⇧#-R-F5-F-5-ESC-O-0-Ø-⏏-SCROLL LOCK Internet starts over from ARPANET

Telephoto

Telephoto

https://www.xkcd.com/1855

https://www.explainxkcd.com/wiki/index.php/1855:_Telephoto

[Cueball stands behind a huge telephoto lens which rests on two tripods, one at the left in front of Cueball, and an other larger one in the middle. The lens is more than five times longer than Cueball is high. In front of the lens is a tree with a bird on top close to the lens. The bird is labeled "Subject". Inside the telephoto lens at the location of the objective lens a small device is shown and labeled "Webcam". From that device a small cable runs through the entire telephoto lens to the eyepiece, where an other device labeled "Camera" is shown.] [Caption below the panel:] Telephoto tip: If you add enough converters and extenders, you don't actually need a fancy lens.

This is another one of Randall's Tips , this time a Telephoto Tip. Telephoto lenses are special lenses for cameras that are physically shorter than their focal length . Using a long-focus lens allows the photographer to magnify a photographic image of an object rather than being physically close to the object. Alternatively one could add " converters " and " extenders " to an existing lens to get a greater focal length for the cost of reduced brightness. The joke is that Cueball did not want to spend the money on buying a new telephoto lens or real converters, and instead achieved the same effect by moving his cheap camera (a standard webcam , in this case) close enough to the subject to obviate the need for magnification. There are many problems with this. First, the end result is completely impractical to carry around; as shown in the comic, Cueball has to set up two tripods just to support the weight of his hulking behemoth of a camera. Second, if you're an animal photographer like Cueball, you need to be able to see the animal as close up as possible in order to get a good picture; a lens with lots of magnification power accomplishes just that without alerting the animal to the photographer's presence, but Cueball's camera would surely scare off any birds he tried to photograph (except in fanciful proof-of-concept diagrams like this comic). Perhaps most damning of all, though, is the fact that Cueball's idea involves installing a webcam at the far end to be able to photograph anything. Webcams are not designed to capture high-resolution images, so the resulting image will be of considerably lower quality compared to professional photographers' works, although it could be better than a standard camera setup taking account of the huge achievable zoom levels. But more importantly, the presence of the webcam renders the functionality of the extenders (and the base camera itself!) completely redundant, cementing this idea as a total waste of money and effort. The same could be achieved by mounting the webcam on a long stick; an extraordinary long selfie stick will achieve nearly the same effect, for considerably less cost and set-up than Cueball's behemoth. The title text continues this by saying he was banned from the Airliners.net photography forum because his new modified lens was so long that it started brushing against planes as they flew by. If Cueball's gargantuan lens is being set up on or near runways or is so long that it potentially damages planes in-flight, then being banned from an online forum should be the least of his worries. [ citation needed ] In-flight damage dealt to planes can cause severe consequences, e.g. causing them to crash. This would possibly put him on the no-fly watchlist, as well as being charged with unintentional damage. [Cueball stands behind a huge telephoto lens which rests on two tripods, one at the left in front of Cueball, and an other larger one in the middle. The lens is more than five times longer than Cueball is high. In front of the lens is a tree with a bird on top close to the lens. The bird is labeled "Subject". Inside the telephoto lens at the location of the objective lens a small device is shown and labeled "Webcam". From that device a small cable runs through the entire telephoto lens to the eyepiece, where an other device labeled "Camera" is shown.] [Caption below the panel:] Telephoto tip: If you add enough converters and extenders, you don't actually need a fancy lens.

Existence Proof

Existence Proof

https://www.xkcd.com/1856

https://www.explainxkcd.com/wiki/index.php/1856:_Existence_Proof

[Miss Lenhart stands in front of a whiteboard and points at calculations written on it.] Miss Lenhart: There exists some number x such that f(x)=G(f(0))=1. [Miss Lenhart moves her arm in a frameless panel.] Miss Lenhart: Oh yes. Miss Lenhart: Somewhere out there, it exists. [Zoom-in on Miss Lenhart raising a fist.] Miss Lenhart: And we must find it... and destroy it. [Miss Lenhart raises a sword.] Miss Lenhart: Grab your swords, students! We ride! Student #1 (off-screen): I think I'm in the wrong math class? Student #2 (off-screen): I'm finally in the right one.

In mathematics, an existence proof is a proof that only shows that an object with a specific property exists, but does not tell what this object is. For instance, if f is a continuous function such that f(0) = 0 and f(100) = 2, it is easy to prove that there exists an x between 0 and 100 such that f(x) = 1 (as in the comic). However, this proof gives no way to find such an x. In many situations, a proof of existence is enough to satisfy a mathematician, but in others, it is desirable to actually identify the object whose existence has been proven. The full statement itself seems like a solution to some kind of function composition problem. Seems like what the class has proven is that if you apply certain function G(x) to a starting point of function f(0), then what it will do is just give you a value of f(x) at some other value of x, existence of which is stated to be proven. The sentence "There exists some number x such that f(x)=G(f(0))=1." boils down to "There is an x such that f(x)=1". The part with G(f(0)) is only a way to arrive at 1. For some reason there is an x that satisfies f(x)=G(f(0)), and since G(f(0))=1, it is equivalent to f(x)=1. In the comic, Miss Lenhart (and students) take this one step further, by taking up arms to destroy the function value, which they have proven to exist. In the last panel, some students off screen begin to wonder if they are in the right class, as normal math classes do not take up swords to fight abstract concepts. [ citation needed ] Another student remarks that they are finally in the right math class, implying that this is the kind of thing they wanted from their math curriculum all along. The phrase " We ride " is commonly used in rallying battle cries, particularly in fantasy or medieval dramas where characters are preparing to enter combat on horseback. Variations of the phrase are used several times in The Lord of the Rings , for example. The title text refers to Real Analysis , a branch of mathematics dealing with real numbers and real-valued functions (as opposed to studies dealing with integers , rational numbers , imaginary numbers in the complex plane, etc.). As the speaker implies, Real Analysis is supposed to remain confined to the theoretical realm of mathematics; certainly nobody signing up for such a class would ever expect to be embroiled in a crusade against intangible constructs! Taken out of its mathematical context, "analysis" literally means "breaking down", referring to the teacher's intention to cut things up with a sword. The use of the uncommon word "realer" conveys that the situation has suddenly developed unusually high stakes. This nuance would be lost if the word "realer" were replaced with the technically correct phrasing of "more real". This may be a continuation of 982: Set Theory , where numbers were "executed" to prove a point. [Miss Lenhart stands in front of a whiteboard and points at calculations written on it.] Miss Lenhart: There exists some number x such that f(x)=G(f(0))=1. [Miss Lenhart moves her arm in a frameless panel.] Miss Lenhart: Oh yes. Miss Lenhart: Somewhere out there, it exists. [Zoom-in on Miss Lenhart raising a fist.] Miss Lenhart: And we must find it... and destroy it. [Miss Lenhart raises a sword.] Miss Lenhart: Grab your swords, students! We ride! Student #1 (off-screen): I think I'm in the wrong math class? Student #2 (off-screen): I'm finally in the right one.

Emoji Movie

Emoji Movie

https://www.xkcd.com/1857

https://www.explainxkcd.com/wiki/index.php/1857:_Emoji_Movie

[Megan and Cueball are walking together while Megan is looking at her smartphone.] Megan: Did you see there's an emoji movie? Cueball: If they have to make a movie about a section of Unicode, it's not the worst choice... Megan: They should do a whole series. I would watch the Combining Diacritical Marks movie . Cueball: That series would have way too many characters.

Megan asks Cueball if he knows about the then-upcoming The Emoji Movie . It was released on July 28, 2017, a month after this comic, and had been widely reviled on the Internet for its lack of original plot, characters, and jokes. Cueball responds to the topic by damning it with faint praise , starting with the presumption that somebody had to make a film about a "section of Unicode". Unicode is the standard by which almost all modern text, in all languages, is represented as computer data. It consists of thousands of "code points", grouped into about 280 contiguous sections known as "blocks". There is no formal term "section of Unicode", which Randall seems to be using to skirt the fact that emojis are not all represented within one Unicode block. Examples of potential Unicode blocks include "Playing Cards", "Musical Symbols", "Tibetan", "Hangul Jamo Extended-B", "Braille Patterns" – and of course "Combining diacritical marks" and "Dingbats", referred to in the comic. Emojis are standard pictograms which include smileys (eg 😂) and common objects such as beer (🍺) and eggplant (🍆). Dating from the late 1990s, they were added to Unicode in 2010. There is actually no Unicode block known as "Emojis". There is Emoticons (U+1F600..U+1F64F), which contains 80 code points, mostly of facial expressions. However it does not include all emojis. For instance, "Baby" (👶) is U+1F476, within the Miscellaneous Symbols and Pictographs block. The topic of emoji in Unicode also appears in 1813: Vomiting Emoji . Megan responds to this presumption by facetiously suggesting that Hollywood should make a series of films about different code blocks, referencing Hollywood's current trend of reducing risk by making many sequels and adaptations. She proposes a movie about Combining Diacritical Marks (see 1647: Diacritics ), a different section of Unicode which contains 112 code points (each assigned to a character). These code points include many varieties of diacritics such as accents, cedillas and tildes which can be combined with other letters to produce an almost unlimited number of possibilities, such as "ў" (Cyrillic U plus breve). Cueball quips that this series would have too many characters. This is a pun on the word "character", which has the double meaning of a fictional character , or a symbol which corresponds to a grapheme (e.g. letter, digit, punctuation mark). It's true that although the Combining Diacritical Marks movie would have only 112 characters, the series as a whole would have tens of thousands, including such epics as "Egyptian Hieroglyphs" (1,071) and "CJK Unified Ideographs Extension B" (42,720). The " Antz / A Bug's Life thing" in the title text refers to the twin films phenomenon, in which two films with very similar (or identical) concepts are released within roughly the same timeframe. Competing studios Dreamworks and Pixar released their respective insect-oriented films in 1998, a year infamous for many other such film pairings (see the Wikipedia article for a full list). Dingbats were an early form of pictograph included within the normal mechanisms for producing computer text, serving a similar function to emojis, but oriented towards practical symbols such as telephones, airport symbols and a wide variety arrows. Unlike emojis, they are usually black-and-white. Previously, dingbats required a specific font to render, but as part of Unicode (U+2700–U+27BF), they can now be displayed in a variety of fonts. For example: ✈ ✆ ➹ ✂ ✰ Some characters are both dingbats and emoji, and are followed with a variant-selector character to indicate whether they should be in color. The joke is that although dingbats and emojis are superficially equivalent, a film which contains many cute human expressions would have much more potential for success than one about dry symbols such as arrows, asterisks and scissors. Megan and Cueball's discussion about the movie is continued in 1870: Emoji Movie Reviews . [Megan and Cueball are walking together while Megan is looking at her smartphone.] Megan: Did you see there's an emoji movie? Cueball: If they have to make a movie about a section of Unicode, it's not the worst choice... Megan: They should do a whole series. I would watch the Combining Diacritical Marks movie . Cueball: That series would have way too many characters.

4th of July

4th of July

https://www.xkcd.com/1858

https://www.explainxkcd.com/wiki/index.php/1858:_4th_of_July

[One single panel is shown. The header reads:] 4 th of July activities 2014 - Watching fireworks 2015 - Watching fireworks from drones 2016 - Flying drones through fireworks 2017 - Intercepting fireworks with drones 2018 - Competitions to hit drones with fireworks 2019 - Teams compete to shoot down each other's firework-armed drones 2020 - Sentient firework-armed drones overthrow humans 2021 - Drones celebrate independence day

In the United States, the 4th of July is celebrated as Independence Day . This comic claims to show the timeline of different activities that are used to celebrate the holiday. One common activity is to watch fireworks displays. With the rise of personal drones there have been several videos of fireworks from drones, including flying the drones through the middle of the display. The comic then purports that starting in the year it was published (2017), fireworks and drones will be at some sort of war with each other, starting with drone pilots leading their drones into the path of the rising fireworks before they explode, leading to fireworks technicians intentionally trying to strike down drones. In 2019, Randall posits that the drones will be weaponized with fireworks and competitions will be held to shoot down your opponents' drone. This wanton destruction of drones leads them to turn against their pilots and humanity in 2020 (after gaining sentience, presumably by their AI evolving through the competition), and then in 2021, they will be celebrating their Independence Day from the humans. As of November 2021, drones have not yet overthrown humans. [ citation needed ] Despite the many unfortunate events that happened in 2020, sentient firework-armed drones overthrowing humans was not one of them. [ citation needed ] The title text refers to another popular 4th of July activity in the United States: Barbecues with fare such as hot dogs and hamburgers. But since the drones don't have mouths or a digestive tract, they simply make a mess by using their rotors as a blender. [One single panel is shown. The header reads:] 4 th of July activities 2014 - Watching fireworks 2015 - Watching fireworks from drones 2016 - Flying drones through fireworks 2017 - Intercepting fireworks with drones 2018 - Competitions to hit drones with fireworks 2019 - Teams compete to shoot down each other's firework-armed drones 2020 - Sentient firework-armed drones overthrow humans 2021 - Drones celebrate independence day

Sports Knowledge

Sports Knowledge

https://www.xkcd.com/1859

https://www.explainxkcd.com/wiki/index.php/1859:_Sports_Knowledge

[Cueball and White Hat are walking together.] Cueball: Mike Trout's on-base plus slugging has been at career highs. After this injury, the Lakers will be lucky if he can hit even close to that. White Hat: ...Lakers? Cueball: I forget which team he is. Broncos? [Caption below the panel:] I know a handful of very specific things, but after that my sports knowledge falls apart quickly.

Cueball , representing Randall , demonstrates that he has some knowledge about Mike Trout , a baseball player for the Los Angeles Angels . However, he mixes up the Los Angeles baseball team for one of the city's basketball teams when he mentions the Lakers . White Hat questions his mentioning of the Lakers, after which Cueball takes another wild guess, this time mentioning an American football team, the Denver Broncos , based in Denver, Colorado, over 800 miles (1300 kilometers) away from Los Angeles, indicating even poorer knowledge about sports. On-base plus slugging (OPS) is a baseball statistic calculated as the sum of the on-base percentage (the number of times a player reaches base divided by the number of plate appearances) and slugging percentage (singles + 2 times the doubles + 3 times the triples + 4 times the home runs divided by at bats). It is useful for figuring out how well a player reaches base and hits for power . As of the date this comic was published, Trout's OPS for the 2017 season at 1.203 was indeed higher than in any of his previous seasons, albeit over a smaller number of games because Trout indeed suffered a thumb injury in late May and had not played since then. (He returned to play starting on July 14.) At the end of the season, the teams leading each division make the playoffs, along with a certain number of other teams. In the NFL (with 8 division winners) and MLB (with 6 division winners), 4 extra teams make the playoffs, and, in the NBA (also with 6 division winners), 10 teams beside the division winners qualify for the playoffs. In baseball the two teams in the American League play a Wild Card game against each other, as do the two in the National League, and in American football , there are Wild Card games in which the two wild card teams per conference play the two lower seeded division winners. At the time of publication, the Los Angeles Angels were, indeed, in the running for a wild-card spot (2½ games out of the playoffs). With the baseball season being halfway over (and thus months away from the Wild Card games in early October) and both football and basketball being in the off-season, Cueball further shows his lack of sports knowledge in asking whether it is next week, and assuming that he could spontaneously decide, at game time, to just go. He could make a decision to go now, but he would have to wait until the season is almost over when the seeding for the playoffs and wild card spots are decided. Sometimes the wild card spots aren't decided until the last game of the season; since MLB rules dictate that the Wild Card team with the better record hosts the game, this scenario would complicate the process of buying the tickets (which could be sold out prior to game time due to high demand), as well as other logistical matters (such as traveling to the game; if Cueball were located in the East Coast of the United States and the game were hosted by the Angels, Cueball would need to take a cross continent flight). In the end, the Angels were eliminated from postseason contention on the final weekend of the season, making Cueball's wish impossible until the next season. As the caption says, he demonstrates that he has very specific knowledge in the topic but stumbles when anything out of his narrow field of view is brought up, similar to 132: Music Knowledge . To compensate for his lack of interest and knowledge in sport Randall made the comic 1107: Sports Cheat Sheet , and he has before directly mentioned his missing knowledge in 1480: Super Bowl . (See more comics linked in those two). [Cueball and White Hat are walking together.] Cueball: Mike Trout's on-base plus slugging has been at career highs. After this injury, the Lakers will be lucky if he can hit even close to that. White Hat: ...Lakers? Cueball: I forget which team he is. Broncos? [Caption below the panel:] I know a handful of very specific things, but after that my sports knowledge falls apart quickly.

Communicating

Communicating

https://www.xkcd.com/1860

https://www.explainxkcd.com/wiki/index.php/1860:_Communicating

[Egg-shaped character Humpty Dumpty, drawn with an angry face, is sitting on a brick wall and facing Alice, depicted as Science Girl.] Humpty Dumpty: When I use a word, it means just what I choose it to mean. Neither more nor less. Alice: I wonder what all those words you just said meant. Maybe you're telling me I can have all your stuff! Humpty Dumpty: What!? No! Alice: Your car, too? Gosh, thanks!

There's glory for you. In Lewis Carroll's " Through the Looking-Glass, and What Alice Found There ", Alice meets Humpty Dumpty (the egg-shaped character from the children's verse). Humpty Dumpty is a Looking Glass creature, and the Looking Glass creatures all feature some form of inversion. For Humpty Dumpty the inversion is in meanings. When they first meet, Humpty Dumpty berates Alice for having a name that doesn't mean anything (contrasted with his name which means his shape). But later, Humpty declares to Alice "There's glory for you". Alice doesn't understand what Humpty means by "glory". Humpty explains that he can make words mean whatever he chooses to mean. By "glory" he meant "a nice knock-down argument". And he adds: "When I use a word, it means just what I choose it to mean. Neither more nor less." ( [1] ) In the comic Humpty is explaining to "Alice" (portrayed by Science Girl ) that he can choose meanings for his words. Alice points out the obvious problem by pretending to wonder what meaning should be given to that utterance, and decides it means "Please take all my belongings". Humpty realizes he has been caught in a trap, but now Alice is choosing meanings, and even his protests are taken to mean "take my car along with my belongings". While it seems that Alice chooses these specific meanings of words to educate Humpty Dumpty about the mistake in his way of thinking, she could as well inform him about planned theft with random, meaningless words or not at all. After all, she got "permission". Also, even though Humpty Dumpty decides about the meanings of words by himself, he "accidentally" chooses the normal meanings of all of Alice's words, because otherwise he wouldn't be informed about the planned theft and wouldn't be able to react to this with "What!? No!". Humpty Dumpty is known from the nursery rhyme or riddle: Humpty Dumpty sat on the wall, Humpy Dumpty had a great fall. All the King's horses and all the King's men, Couldn't put Humpty together again. Carroll's Humpty Dumpty is a parody of people who use technical language without defining their terms, and expect others to understand. The title text continues this. By Humpty insisting that he is not responsible for others understanding him he is unable to get help getting down from the wall, which will lead to his inevitable demise. This two-sided nature of communication is also shown in the title text of 1028: Communication , as well as in later comics like 1984: Misinterpretation (with a list of other comics about communication). [Egg-shaped character Humpty Dumpty, drawn with an angry face, is sitting on a brick wall and facing Alice, depicted as Science Girl.] Humpty Dumpty: When I use a word, it means just what I choose it to mean. Neither more nor less. Alice: I wonder what all those words you just said meant. Maybe you're telling me I can have all your stuff! Humpty Dumpty: What!? No! Alice: Your car, too? Gosh, thanks!

Quantum

Quantum

https://www.xkcd.com/1861

https://www.explainxkcd.com/wiki/index.php/1861:_Quantum

[A chart with the Y-axis titled "How Philosophically Exciting the Questions Are to a Novice Student" and the X-axis titled "How Many Years of Math are Needed to Understand the Answers". The upper-right portion of the chart is labeled "Danger Zone". The following topics are charted as follows: Basic Physics: low excitement, low prerequisites Fluid Dynamics: low excitement, high prerequisites Magnets: medium excitement, medium prerequisites General Relativity: medium excitement, high prerequisites (on the border to the "Danger Zone") Special Relativity: high excitement, low prerequisites Quantum Mechanics: high excitement, high prerequisites (in the "Danger Zone")] [Caption below the panel:] Why so many people have weird ideas about Quantum Mechanics

The comic depicts a relationship between how philosophically exciting the questions in a field of study are, versus how many years are required to understand the answers. For example, special relativity poses very intriguing philosophical questions, such as " can the temporal ordering of spatially separated events depend on the observer? ", or " can time run at different rates for differerent observers? ". But it doesn't take a lot of mathematical knowledge to understand the answers - that when objects move very close to the speed of light, time slows down and their lengths contract : the key Lorentz transformations ultimately involve little more than high-school algebra. Hence, Special Relativity is very high up on the y-axis but not very far on the x-axis. Basic physics is not very philosophically interesting but also not very complicated. Fluid dynamics , as captured by the Navier–Stokes equations is very complicated, but it's concerned with a very specific topic - how water or other fluids flow around - so it doesn't lead to big philosophical questions. The "danger zone" in the top right of the chart is when a field of study is wide-ranging enough to pose broad philosophical questions, and also so complicated that most people can't answer those questions. Quantum mechanics deals with some very strange concepts that readily lend themselves to philosophical questions, such as the idea that merely observing something can change it, or the idea that something can be both a wave and a particle at the same time. However, the explanation for those phenomena is a very complicated piece of math, notably the Schrödinger equation , which means that most people don't have accurate answers to those questions. Randall suggests that this is the reason why so many people have "weird ideas" about quantum mechanics. 1240: Quantum Mechanics also discusses weird ideas that people have about quantum mechanics. General relativity also presupposes considerable mathematical sophistication to understand the Einstein field equations . However, the main contribution of GR – the explanation of gravity in terms of a curved spacetime – does not seem to induce a lot of philosophical novelty beyond that already seen in special relativity, possibly with the exception of black holes . The title text references the Insane Clown Posse (ICP) song " Miracles ", made memetic by the lyric "Fucking magnets, how do they work?" An axis is the direction on a graph in which some quantity is increasing or decreasing. So things that are far along the "miracle" axis are presumably more miraculous. As you move from bottom-left to top-right on the graph, items become both more philosophically interesting and harder to understand. It would be fair to describe something that's hard to understand and raises big philosophical questions as a "miracle". The ICP "Miracles" axis would also intersect the topic "magnets" infamously mentioned in the song. [A chart with the Y-axis titled "How Philosophically Exciting the Questions Are to a Novice Student" and the X-axis titled "How Many Years of Math are Needed to Understand the Answers". The upper-right portion of the chart is labeled "Danger Zone". The following topics are charted as follows: Basic Physics: low excitement, low prerequisites Fluid Dynamics: low excitement, high prerequisites Magnets: medium excitement, medium prerequisites General Relativity: medium excitement, high prerequisites (on the border to the "Danger Zone") Special Relativity: high excitement, low prerequisites Quantum Mechanics: high excitement, high prerequisites (in the "Danger Zone")] [Caption below the panel:] Why so many people have weird ideas about Quantum Mechanics

Particle Properties

Particle Properties

https://www.xkcd.com/1862

https://www.explainxkcd.com/wiki/index.php/1862:_Particle_Properties

Particle Properties in Physics

A table is presented comparing the range (maximum and minimum value) and scale (how big number increments are) of several measures. The table begins by listing properties pertinent to particle physics as the title suggests, but quickly devolves to other domains such as role-playing games (such as D&D) and sports after failing to provide a good definition of flavor . The title text says that in addition each particle has a password, but only hash of the password can be observed. This is a computer science reference. In computer science, properties (e.g. of an object or program) often can be changed with a single command. In physics as we observe it, properties can locally change with the environment. There are several experiments , whether physical constants are really time-const. Password hashing is the practice of hiding the password itself by storing only an irreversible representation of the password. Since the password itself is not stored, the password cannot ever be viewed by the user or a hacker (outside of the login page). This method is considered to be safest way of storing passwords. Password hashing using some key derivation function makes it impossible to steal passwords even if the server that stores hashes is cracked, unless the hash function is also broken, which should be a task which cannot be completed in any feasible time for sufficiently strong passwords. The title-text claims this is predicted by the cosmic censorship hypothesis , which in reality claims that a gravitational singularity must always be obscured by an event horizon (i.e.: there can't be a naked singularity ). There is also a hint of quantum mechanics in the statement, as observation is one of the central concepts of the field, and Heisenberg's uncertainty principle actually states that it is impossible to observe (measure) some property of a particle with arbitrary precision when another one is known (e.g.: you can't determine the momentum and position of a particle). This makes the title text a mix of several domains, as was the above table. Particle Properties in Physics

Screenshots

Screenshots

https://www.xkcd.com/1863

https://www.explainxkcd.com/wiki/index.php/1863:_Screenshots

Intro to Screenshots [The left side of the panel shows three images. The largest image is a screenshot of text with the middle section highlighted and margins and top and bottom rows marked with red lines and arrows. The two smaller images below are cropped versions of the screenshot in the first image: the left image has an incorrect "squashed" aspect ratio and a red X on it, while the right image has a correct aspect ratio and a green check mark.] [The right side of the panel:] Syllabus Highlighting: What & how much Aspect ratios Cropping: Pre- and post- Whitespace Screenshots vs links Catching the right GIF frame Snapchat and trust Embarrassing background tabs Spellcheck's red outlines Security: Beware URL tokens Redacting personal info Useful browser modes Tradeoffs: PNG vs JPG Watermark ethics Spotting fakes [Caption below the panel:] My class on screenshots was a big hit, although for some reason I only ever sold one copy of the digital textbook.

The comic shows a syllabus of an introductory course on screenshots . Screenshots have become a common way of spreading and sharing content on social media like Tumblr and Twitter, particularly excerpts of text such as seen in the cartoon. This in turn has developed into a common language with unwritten rules; the comic imagines a world where such rules have become codified into best practices, able to be taught in classes. The image on the left shows an image of screenshots of text, along with what seems like annotations describing various ratios and dos and don'ts about making such screenshots. The right side shows the main points of the course, touching on topics that are relevant for making and publishing screenshots. Some of these guidelines are violated on a regular basis by people sharing screenshots on the internet, leading to impaired readability and the degradation of digital quality (see 1683: Digital Data ). The punchline of the comic describes a high attendance in the course (presumably many people are interested in how to take high-quality screenshots); however, the digital textbook only sold one copy, implying that the only attendee that bought the book was adept enough to distribute screenshots of the textbook content to the others, because of the information gathered from the class itself. In essence, the writer of the textbook has taught their students how to pirate their material, effectively putting themselves out of a job. There isn't anything that the author can do to prevent this due to the analog hole , which states that if non-interactive media can be visually seen by humans, it can be copied, as with a screenshot. Detailed explanation of the headings on the right: Highlighting: What & How much? This refers to highlighting text of particular interest in screenshots, as depicted on the left. Aspect ratios Again, depicted on the left. If a screenshot is too wide, it might be difficult to read, and/or it will not fit into thumbnails and social networking feeds. This leads to the screenshot being scaled down too much to be readable (see bottom left). An aspect ratio that is too tall would have similar effects, so in general it is better to stick to near-square aspect ratios (see bottom right of the left section). Some users change the aspect ratio when scaling with a very ugly result (see e.g. 1187: Aspect Ratio ). Cropping: Pre- and Post- This refers to cropping the image, that is, cutting away the irrelevant or unnecessary parts, leaving just the content one needs to communicate. Pre- and Post- refers to when the cropping is done, either before the screenshot (i.e. framing the shot) or cropping the screenshot after it has been taken (i.e. fine tuning it in a photo editing program). Whitespace This section presumably deals with whitespace . This generally refers to the space around the content of interest, which is often but not always white. In the main image on the left side of this comic, most of the red marks are arrows indicating the white space of that image. In this case the "whitespace" at the top and bottom are indeed not white, but rather filled with text not relevant to the screenshot. Removing all whitespace makes an image more efficient and helps provide focus on the important part of a screenshot, but too little whitespace can be less comfortable to read or look at, and therefore appear as a more amateurish result. This section of the course would likely discuss this balance. Screenshots vs Links For the most part it is recommended that one links to the original content, rather than publishing a screenshot of said content. In some situations it is advisable to opt for using screenshots, such as if the content in question has been removed from the original source, and one still wants to communicate the fact that it was published there. Additionally, a screenshot is easier to catch people's attention with, as it doesn't require them to take any actions to view. Catching the right GIF frame A GIF is a bitmap image format that was developed in 1987 by CompuServe and has since come into widespread usage on the World Wide Web due to its wide support and portability. The format supports animations and is often used for short looping animations on the internet. They often employ a low frame rate , so that one might notice a funny or interesting frame during playback. The naïve approach is to press the 'Print Screen' button with careful timing, but in this manner it can be very challenging to capture the desired frame of any GIF that plays at a speed of greater than 5 frames per second. Presumably, the course introduces its students to special tools to get the job done, such as the EZgif website or the downloadable 7GIF app . Snapchat and trust Snapchat is a popular social networking application for mobile devices primarily used for sharing images and short videos. One of the main selling points is the transience of content posted. The idea is that as soon as one opens an image or video, a timer starts, and once it has expired the content is no longer accessible on the device. This has led to people sending sensitive content to their friends, thinking that they wouldn't be able to cause much harm, as the content is non-permanent. An obvious flaw in this model is the capability of modern mobile devices to take screenshots (usually available from shortcut keys), and thus permanently save the images to the phone's memory. Saving embarrassing images of one's friends, that they themselves meant as a transient joke, is a serious breach of trust, hence the heading. Embarrassing background tabs A common error when publishing screenshots is not being careful, and leaving content visible that might be embarrassing. For instance, a browser tab open in the background might show content that is embarrassing or private information, such as a page about a sensitive disease one may have (e.g. AIDS ) or pornography . It is easy to miss this when checking, which leads to situations such as this one , where a politician handed out a document with background tabs to pornography websites. Spellcheck's red underlines Spell checkers are designed to notify the writer of a document of spelling and grammatical mistakes in the text. This is usually done through the editor marking text it thinks is incorrect with an underline (usually red, but other colors may indicate different kinds of mistakes). Sometimes these mistakes are not relevant to the writer, such as when editing source code or using a spellchecker that is set to another language. Even if the corrections are relevant, however, one would not want the ugly red underlines on a screenshot. This section presumably deals with this problem. Security: Beware of URL tokens URL tokens are pieces of code embedded in the URL of a website. If implemented well, these help identify a particular document or search query, and do not carry any sensitive security information. Insecure web-apps, however, may encode authentication information (such as session IDs , or even worse: usernames and passwords) in the URL, leading to a massive security risk on the part of someone whose screen might be visible to others. Screenshots allow anyone to easily read off these parameters, and possibly successfully impersonate the creator of the screenshot on a website. This is especially hard to notice to less technically inclined users, who might not know that, say, a session ID (a seemingly random jumble of characters), might be used to impersonate them. Redacting personal info Somewhat related to the previous point: Screenshots might include personal information, such as indications of institutions one might work for, e-mail addresses, and the like, that one might not want to share with the world. This section presumably deals with ways of obscuring such information on screenshots. Useful browser modes Using the private browsing mode offered by most browsers helps with the previous point of keeping your personal information out of the screenshots because websites see you as logged out. Another helpful mode is the full screen browsing mode (usually F11) that will maximize the content to cover the whole screen, keeping the browser UI out of the screenshots. This also helps with privacy, as it will keep the bookmarks on your browser toolbar from being visible, as well as your username if you're logged in Chrome, without having to crop the screenshots manually. Counterpointing with the final bullet on spotting fakes, the Inspect Element browser mode allows you to live-edit the HTML source of the webpage, allowing you to create more convincing fakes if that is your goal. Tradeoffs: PNG vs JPG PNG and JPG are file formats with different image compression algorithms . JPG is widely used for encoding photographs, as it compresses real-world images to a fraction of their normal size without losing much quality. On artificial images with lots of sharp changes in contrast (such as text), however, JPG produces visible compression artifacts due to its lossy compression . For these, PNG is usually used, as it compresses large blocks of a single color, and repeating patterns efficiently, and due to it having a lossless option is able to encode text without artifacts, improving readability. PNG is usually superior for screenshots, as these are artificial images, but if the screenshot is of an actual photo (or a frame of a GIF or movie), JPG might yield lower file sizes at comparable quality. This tradeoff is presumably discussed under the heading. JPG images also have an attached EXIF data file, not present in PNG images, which may contain information about the device that the screenshot was taken on (especially "with", e.g. a camera) and thus be a potential privacy risk in some cases. However, EXIF metadata is not used with JPEG 2000. However, PNG can contain a transparency layer, allowing the object in the image to exist without a background. Watermark ethics Many users and websites add watermarks to their original content (or even worse: their screenshots) to indicate where it came from. As depicted in 1683: Digital Data this can lead to degradation of quality as watermarks are stacked on top of each other. It is generally considered okay to put a single unobtrusive watermark on one's own original work; anything other than that would be considered unethical. Spotting fakes It is relatively easy to fake a screenshot in an image editing program such as GIMP or just editing the page source, making it seem like another organization or person is the original source of the content, possibly damaging their reputation. Some of these techniques are easily detectable by looking at the images metadata or correlating the contents of the screenshot with other sources. The title text once again refers to the continual re-screenshooting of data as seen in 1683: Digital Data , where the final examination consists of the students taking a screenshot good enough that it is still recognizable (and hopefully readable) after being re-compressed, re-screenshot and re-uploaded to various social networking sites, deteriorating its quality. This is quite a difficult task, considering the student only has control over the first screenshot, and subsequent screenshots could degrade the quality to any level. Hopefully the professor is aware of this and plans to perform the test under controlled conditions, as well as grade on a curve. Screenshots were previously explored by Randall in 1373: Screenshot , 1683: Digital Data and 1815: Flag . This comic is one of a small set of comics with the same or almost the same title as another comic (with only the plural form of the word screenshot being the difference). Intro to Screenshots [The left side of the panel shows three images. The largest image is a screenshot of text with the middle section highlighted and margins and top and bottom rows marked with red lines and arrows. The two smaller images below are cropped versions of the screenshot in the first image: the left image has an incorrect "squashed" aspect ratio and a red X on it, while the right image has a correct aspect ratio and a green check mark.] [The right side of the panel:] Syllabus Highlighting: What & how much Aspect ratios Cropping: Pre- and post- Whitespace Screenshots vs links Catching the right GIF frame Snapchat and trust Embarrassing background tabs Spellcheck's red outlines Security: Beware URL tokens Redacting personal info Useful browser modes Tradeoffs: PNG vs JPG Watermark ethics Spotting fakes [Caption below the panel:] My class on screenshots was a big hit, although for some reason I only ever sold one copy of the digital textbook.

City Nicknames

City Nicknames

https://www.xkcd.com/1864

https://www.explainxkcd.com/wiki/index.php/1864:_City_Nicknames

[Black Hat, Megan, and Ponytail are standing on a hill overlooking a city. The Gateway Arch is visible, as well as a number of skyscrapers in the skyline.] Black Hat: Ah, New York. The Hot Tamale. Megan: This is St. Louis. Also, that's not– Black Hat: The Winged City. The Gold Trombone. Castleopolis. Megan: It's none of those. [Close-up of Black Hat] Black Hat: The Kissing Kingdom. Sandland. The High Place. Ol' Ironhook. Megan (off-panel): Still wrong. Black Hat: The Thousand Spires. The Graveyard of Kings. Bloomtown. Lantern City USA. Megan (off-panel): Please stop. [Black Hat, Megan, and Ponytail are walking] Black Hat: The City of Many Daughters. Big Mauve. The Glass Cradle. The Road Source. London Prime. Hamtown. The Salad Bowl. God's Boudoir. The Glittering Swamp. The Steel Forest. The Mobius Strip. The Land of Trains and Fog. The Meeting Place. The Dark Star. The Walled Garden. Skin City. The Horse Rotary. Turkeytown. The Naked Towers. The Meta-City. The Urban Orb. The City of Angles. The Big Wheel. Bird City USA. The City of Seven Crowns. Hilltopia. Bug City. The Bottomless Cup. [Text size getting smaller] Lorde's Fen. The Last Town. The Empty Set. Ghost Harbor. Megan: How long does this last? Ponytail: No city has ever let him stay long enough to find out.

Cities often have official or unofficial nicknames. For instance, St. Louis, Missouri , is known as "Gateway to the West" among several other nicknames. The nicknames typically invoke some historical or geographic feature of the city, but can sometime be opaque to those not familiar with the city. The full, formal name of Bangkok includes a long list of superlatives translating as "The city of angels, the great city, the residence of the Emerald Buddha, the impregnable city (of Ayutthaya) of God Indra, the grand capital of the world endowed with nine precious gems, the happy city, abounding in an enormous Royal Palace that resembles the heavenly abode where reigns the reincarnated god, a city given by Indra and built by Vishnukarn." Despite the skyline being clearly recognizable as St. Louis due to the Gateway Arch , Black Hat calls it New York City . However, the nickname he gives is neither a common New York nickname (such as " The Big Apple ") nor a St. Louis nickname. Megan tries to correct him, but it becomes clear that Black Hat is making up nicknames. Many of his suggestions are puns for real nicknames of other places. The title text contains made up demonyms in the same pattern. A demonym is a word for the people who live in a particular place. They are typically derived from the name of the place (e.g. "St. Louisan" for people from St. Louis, or New Yorker for those from New York), but some regions have an informal demonym that can be used colloquially by those familiar with the place to refer to its residents (e.g. Hoosier for people from Indiana). [Black Hat, Megan, and Ponytail are standing on a hill overlooking a city. The Gateway Arch is visible, as well as a number of skyscrapers in the skyline.] Black Hat: Ah, New York. The Hot Tamale. Megan: This is St. Louis. Also, that's not– Black Hat: The Winged City. The Gold Trombone. Castleopolis. Megan: It's none of those. [Close-up of Black Hat] Black Hat: The Kissing Kingdom. Sandland. The High Place. Ol' Ironhook. Megan (off-panel): Still wrong. Black Hat: The Thousand Spires. The Graveyard of Kings. Bloomtown. Lantern City USA. Megan (off-panel): Please stop. [Black Hat, Megan, and Ponytail are walking] Black Hat: The City of Many Daughters. Big Mauve. The Glass Cradle. The Road Source. London Prime. Hamtown. The Salad Bowl. God's Boudoir. The Glittering Swamp. The Steel Forest. The Mobius Strip. The Land of Trains and Fog. The Meeting Place. The Dark Star. The Walled Garden. Skin City. The Horse Rotary. Turkeytown. The Naked Towers. The Meta-City. The Urban Orb. The City of Angles. The Big Wheel. Bird City USA. The City of Seven Crowns. Hilltopia. Bug City. The Bottomless Cup. [Text size getting smaller] Lorde's Fen. The Last Town. The Empty Set. Ghost Harbor. Megan: How long does this last? Ponytail: No city has ever let him stay long enough to find out.

Wifi vs Cellular

Wifi vs Cellular

https://www.xkcd.com/1865

https://www.explainxkcd.com/wiki/index.php/1865:_Wifi_vs_Cellular

[A graph with two curves that cross each other. The two areas beneath the curve at the top, and down to either the X-axis or the other curve are shaded with vertical gray lines. The Y-axis has no label, but represents reliability, the X-axis is a timeline, with labels indicating years beneath the axis, without any ticks. The two curves are labeled with text interrupting the curves, in the second case using two lines for the text. In the left shaded area there is a label inside and the right shaded area the label is beneath the curves with an arrow pointing to the area. All this text and the arrow is gray. Above the curves there is a caption also in gray font:] To get something to load on my phone, sometimes I have to... Label left area: ...Connect to WiFi Label right area: ...Turn off WiFi Label curve one: Home WiFi reliability Label curve two: Cellular data reliability Year labels: 2000 2005 2010 2015 2020 [Caption below the panel:] It seems weird from a networking point of view, but sometime in the last few years this flipped for me.

In this comic Randall remarks on how recent changes in Wi-Fi and Cellular data reliability have impacted his behavior. Wi-Fi technology has had several advantages over cellular data transmission due to Wi-Fi antennas' more ubiquitous distribution and ability to focus on high data transmission rates instead of broad signal coverage. However, as Wi-Fi has become more popular it is increasingly common to encounter Wi-Fi networks using outdated hardware, poorly organized or overburdened networks, and competition for bandwidth with other Wi-Fi devices. Meanwhile due to continued commercial investment in upgrading and expanding cellular networks and the more frequent consumer replacement of cellular handsets, the reliability of cellular data has continued to increase. Randall notes that prior to 2015 he found that he could improve his internet connection by connecting to a Wi-Fi network instead of using cellular data. After 2015 however, he finds that in many cases he is able to get a stronger connection by disengaging his Wi-Fi connection and getting his data over a cellular connection. Anything larger than a few kilobytes would previously require someone to switch off network data and connect to a wireless network. However, for a couple of years, cellular networks' data transmission rates have often become more reliable (albeit usually costlier for larger amount of data usage) while home Wi-Fi has remained fairly constant, meaning the cellular network is often the best choice to download a file. Randall says it is weird from a networking point of view , but in fact modern LTE connections via the cellular network are faster ( up to 300 Mbit/s ) than the common used Wi-Fi standards like 802.11b/g and 802.11n ( 54-150 Mbit/s ). Faster Wi-Fi standards do exist but they are very rarely supported. In the title text Randall takes a moment to rail against the often misleading promotional rates offered by cable internet providers. Such providers often attempt to up-sell consumer on internet packages with additional features. Here Randall juxtaposes several descriptors that might feature in a cable ad with several that refer to other things entirely. Xtreme Gigaband is a plausible internet package name, but might also be a reference to Comcast's often derided " Xfinity " promotions. And while Panamax sounds like it may be a film term, it is actually a ship classification that denotes the maximum size ship that can safely pass through the Panama canal . (This could also be referencing the title text of 1632: Palindrome .) Seeing as the title text mentions the cable company, implying that they're also Randall's Internet Service Provider, being "with HBO " would mean including HBO in the cable channel line-up, and most likely include being able to stream TV shows made by HBO. Since HBO shows include Game of Thrones , whose 7th season started only 3 days earlier, it's plausible that this comic might have been inspired by Randall attempting to stream the season premiere. Flavor-Blasted is a food term often used in hyperbolic television food ad, but also could be a reference to Comcast Cable's "Blast!" internet packages. Pricing mentioned in title text is exaggerated with only $5 more during first six months, but costing 5 billion after, which is a reference to how service providers would often advertise a lower temporary price, while if you read the fine print the plan is much more costly once the limited time offer runs out, and discounting is simply used for marketing purposes. What's worse, these discounted periods (typically six months) often come with a much longer contract (typically two years) which imposes cancelation fees. [A graph with two curves that cross each other. The two areas beneath the curve at the top, and down to either the X-axis or the other curve are shaded with vertical gray lines. The Y-axis has no label, but represents reliability, the X-axis is a timeline, with labels indicating years beneath the axis, without any ticks. The two curves are labeled with text interrupting the curves, in the second case using two lines for the text. In the left shaded area there is a label inside and the right shaded area the label is beneath the curves with an arrow pointing to the area. All this text and the arrow is gray. Above the curves there is a caption also in gray font:] To get something to load on my phone, sometimes I have to... Label left area: ...Connect to WiFi Label right area: ...Turn off WiFi Label curve one: Home WiFi reliability Label curve two: Cellular data reliability Year labels: 2000 2005 2010 2015 2020 [Caption below the panel:] It seems weird from a networking point of view, but sometime in the last few years this flipped for me.

Russell's Teapot

Russell's Teapot

https://www.xkcd.com/1866

https://www.explainxkcd.com/wiki/index.php/1866:_Russell%27s_Teapot

[Cueball is standing in front of a blueprint labeled "CubeSat-Based Design", containing a satellite with a teapot in the top.] [Caption below the panel:] I'm crowdfunding a project to launch a teapot into orbit around the sun to settle the Russell thing once and for all.

Russell's Teapot is a philosophical argument that reflects on the difficulty of trying to prove a negative. It involves a hypothetical teapot orbiting a heavenly body, whose existence hasn't been proven, and states that it cannot be disproven (somebody put it there secretly?). While an instrument could be theoretically engineered to pick out a teapot-sized object of any luminosity, the teapot would be very easy to confuse for other pieces of space debris, and the space to search is extremely large; the task is thus akin to the proverbial search for a needle in a haystack. Bertrand Russell devised this analogy "to illustrate that the philosophic burden of proof lies upon a person making unfalsifiable claims, rather than shifting the burden of disproof to others." As such, Russell's teapot is very often used in atheistic arguments. Cueball is trying to settle the teapot argument by actually launching a teapot into space via a crowdfunding campaign. This misses the point of Russell's argument, which is about unfalsifiable claims in rhetoric and not a literal teapot. " CubeSat -based design" refers to a type of miniaturized satellites that is made up of 10-centimeter cube units (here seemingly consisting of 3 units) and enables cost-effective means for getting a payload into orbit. The title-text refers to Russell's paradox , also formulated by Bertrand Russell. Russell's paradox was a flaw found in naïve set theory where one could consider "the set of all sets that do not contain themselves" (a "set" is a mathematical term for a "group of things" -- "things" in this case including a set itself). The paradox arises with whether this set, in turn, contains itself: if it does, then it cannot; if it doesn't, then it must. Similarly, like in the barber paradox , the vehicle which launches only vehicles which do not launch themselves is impossible: if the vehicle takes off, it must launch itself as well as the teapot, and thus can never be launched (without violating alleged NASA regulations, at least). That said, he might get around those regulations by using an initial first stage with an offboard power source for the moment of launch, for example a laser striking a parabolic mirror and massively heating air beneath the craft, causing expansion, or a compressed gas cold launch system such as used to clear submarine launched missiles from their tubes before the real rocket motor ignites. The barber paradox can be stated as follows: "Consider a town in which a man, the barber, shaves precisely those men who do not shave themselves. Does the barber shave himself?" Either answer, yes or no, leads to a contradiction. Sometimes the paradox is incorrectly stated, replacing "precisely those" with "only". Under that scenario, there is no paradox; the barber is merely unkempt. There is, however, a solution in this case. Instead of launching itself, the teapot-containing vehicle may be fired from a space gun , catapult, or other launcher, and then boost itself the rest of the way. This, while true for the CubeSats themselves, is not true for their carrier. Randall has talked about CubeSats in later comics as well, specifically in 1992: SafetySat and 2148: Cubesat Launch . From the top right, clockwise. [Cueball is standing in front of a blueprint labeled "CubeSat-Based Design", containing a satellite with a teapot in the top.] [Caption below the panel:] I'm crowdfunding a project to launch a teapot into orbit around the sun to settle the Russell thing once and for all.

Physics Confession

Physics Confession

https://www.xkcd.com/1867

https://www.explainxkcd.com/wiki/index.php/1867:_Physics_Confession

[Megan is facing Ponytail and Cueball.] Megan: I'll be honest: We physicists talk a big game about the theory of everything, but the truth is, we don't really understand why ice skates work, how sand flows, or where the static charge comes from when you rub your hair with a balloon.

A Theory of Everything is a goal of modern physics which would describe the properties of all fundamental particles and all the interactions between them. The current approach to a theory of everything is to describe how at high energies different interactions, such as electromagnetic forces and the strong and weak nuclear interactions merge. It would be possible, in principle to demonstrate how the rest of known physics can be derived from that quantum behavior. This approach, however, leaves many everyday phenomena which are not understood by modern physics, and many arguments against a theory of everything suggest that it won't ever be able to actually precisely describe everything. This comic lists several of those phenomena: The fine detail of how ice skates work is unknown. It is known that there is a film of water between the skate and the ice that lubricates sliding, but scientists dispute how the film gets there. The commonly held belief is that it is caused by the pressure of the narrow skate; another belief is that the ice is melted by the friction of movement; but both fail to fully explain why skating continues to be possible at temperatures that are significantly below 0 Celsius. A better explanation is simply that, near the melting point of a solid, there will be a thin layer of liquid on the surface due to the dynamic equilibrium between the two phases, hence why ice is slippery. This happens regardless of the presence of skates. A more complete explanation is given in the linked article: Why is ice slippery? . Physicists lack a clear understanding of the interactions involved in the flow of granular materials , such as sand. It is known that the behavior diverges greatly from that of a liquid, but it is unknown exactly how the flow works. PhysicsCentral:Granular Materials Modern physics also doesn't understand what makes electrons move from one material to another when two materials are rubbed against each other (the triboelectric effect ), and why the transfer takes more electrons in one direction than in the other. However, this happens, and it's the cause of static electricity , which can be seen when one rubs a latex rubber balloon against hair. The title text mentions another common phenomenon that is poorly understood: the separation of charges in a cumulonimbus cloud. It is thought that interactions between ice and water transfer electrons, and then the different motion of ice (as hail) and water droplets in the cloud separates the charge. NOAA How lightning is created . [Megan is facing Ponytail and Cueball.] Megan: I'll be honest: We physicists talk a big game about the theory of everything, but the truth is, we don't really understand why ice skates work, how sand flows, or where the static charge comes from when you rub your hair with a balloon.

Eclipse Flights

Eclipse Flights

https://www.xkcd.com/1868

https://www.explainxkcd.com/wiki/index.php/1868:_Eclipse_Flights

[Cueball is standing behind Megan, looking over her shoulder as she's seated in front of her laptop.] Cueball: What's that? Megan: Flight plans. Looks like there will be 50 to 100 flights whose route puts them in the path of the eclipse next month. [A map with a shaded path of the eclipse and red planes traveling is shown, with nine planes inside the path and one inside the eclipse shadow..] Cueball: I'm sure the airlines will be prepared. Pilots know that stuff. Megan: But can you imagine being on the one flight where the pilot didn't? [A more detailed plane is shown flying into a curtain of darkness.] Captain: *KSSCHHH* [sound of intercom being activated] Captain: This is your captain speaking. If you look out the right side of the plane, you'll see, uhh... Captain: Folks, this appears to be the end times.

A total solar eclipse occurred on Monday, August 21, 2017 . It was visible as a total eclipse in a narrow band across the contiguous United States from Oregon on the Pacific coast to South Carolina on the Atlantic. Cueball asks Megan what she is doing, which turns out to be mapping the flights of aircraft that will be flying through the path of totality during the eclipse. She has found between 50 to 100 such flights. While most flights during the eclipse are coincidental, a few airlines had special flights planned for the occasion. Alaska Airlines, for example, chartered an invitation only flight for about 50 astronomers and serious eclipse chasers. On the map, the center of the greatest eclipse is shown on the border between Illinois and Kentucky . Cueball says that the airlines and pilots will be prepared and aware of the situation, but Megan wonders what it would be like on a plane with an unprepared crew. The last panel shows a plane flying into the area of the eclipse with one of the crew telling the passengers that the end of the world has come. In many cultures such as ancient Egypt, the end of the world is represented by a great darkness and the sun going out. During past eclipses, people were said to have believed the world was ending much like this comic (except without planes). This could also be a reference to 1391: Darkness as in that comic the reporters also believed a natural event to be the world ending although in a different setting. The title text refers to the 'fasten seat belts' signs on display for the passengers, as a precautionary measure for turbulence. Many pop-culture depictions of the end of the world feature storms, earthquakes, tsunamis, volcanic eruptions, etc; as the captain believes that the end of the world is upon them, he feels it safe to ensure his passengers are prepared for turbulence from any of the phenomena that occur during the end times. However, the precaution of having one's seat belt fastened is vastly insufficient when confronted with such catastrophic events. This was the first reference to the Eclipse within a month of the totality. It was followed less than three weeks later by 1876: Eclipse Searches . The 2017 eclipse was mentioned as early as 2013 in the title text of 1302: Year in Review . And this year's New Year comic, 1779: 2017 , also mentions it. Both comics express concern, in the title text, that it would be canceled/not happen. [Cueball is standing behind Megan, looking over her shoulder as she's seated in front of her laptop.] Cueball: What's that? Megan: Flight plans. Looks like there will be 50 to 100 flights whose route puts them in the path of the eclipse next month. [A map with a shaded path of the eclipse and red planes traveling is shown, with nine planes inside the path and one inside the eclipse shadow..] Cueball: I'm sure the airlines will be prepared. Pilots know that stuff. Megan: But can you imagine being on the one flight where the pilot didn't? [A more detailed plane is shown flying into a curtain of darkness.] Captain: *KSSCHHH* [sound of intercom being activated] Captain: This is your captain speaking. If you look out the right side of the plane, you'll see, uhh... Captain: Folks, this appears to be the end times.

Positive and Negative Reviews

Positive and Negative Reviews

https://www.xkcd.com/1869

https://www.explainxkcd.com/wiki/index.php/1869:_Positive_and_Negative_Reviews

[A picture with four small bottles and a larger one is shown. The text to the right reads:] SmartQuench 9000 Sports Drink 20 oz  12-pack [Below is a list with reviews; a picture for the user (avatar) and the name below, the rating (in stars) and the text to the right.] ---Customer reviews--- Amy 2015 (4 of 5 stars) Perfect after a run Anon513 (5 of 5 stars) My favorite flavor Merlin (1 of 5 stars) Drinking this made me thirstier Mike63 (4 of 5 stars) Good price B Button (1 of 5 stars) Drank 3 bottles on a hot day and got dehydrated! [Caption below the frame:] Physics tells us that negative reviews are really just positive reviews from people traveling backward in time.

The comic shows customer reviews from people who purchased a made-up sports drink multi-pack containing twelve 20 oz bottles. The people who gave negative reviews are Merlin (the wizard from the legends of King Arthur) and B. Button (from the short story The Curious Case of Benjamin Button and its film adaptation ). Merlin remembers the future; in the T. H. White novel series The Once and Future King , he was born at the wrong end of time and has to live backwards. Benjamin Button was born with the physical appearance of an old man and grows younger as time progresses. In this comic, they apparently perceive time backwards: Merlin was thirsty then he drank the SmartQuench 9000, but he perceived it as drinking and then becoming thirsty. Benjamin Button was dehydrated then drank 3 bottles and got better, but perceived it the other way around. Particles of matter can have a positive or negative electric charge . Particles have associated antiparticles with opposite charge. For example electrons are negatively charged particles and their antiparticles are positrons , which are positively charged. Antiparticles can be interpreted as if they were the associated particle moving backward in time. Applying that interpretation to customer reviews gives the caption of the comic: positive reviews from people traveling backward in time are negative reviews (the "antiparticles" of positive reviews). The caption seems to say that there are only positive experiences—some going forward, some backward in life. However, Randall gives an example in the title text of a positive review which is actually about a negative experience by a person traveling backward in time (the person ate at a restaurant then got sick). The conclusion is that there are both positive and negative events, but the way they are perceived depends on both the event and whether one sees it going forward or backward in time. [A picture with four small bottles and a larger one is shown. The text to the right reads:] SmartQuench 9000 Sports Drink 20 oz  12-pack [Below is a list with reviews; a picture for the user (avatar) and the name below, the rating (in stars) and the text to the right.] ---Customer reviews--- Amy 2015 (4 of 5 stars) Perfect after a run Anon513 (5 of 5 stars) My favorite flavor Merlin (1 of 5 stars) Drinking this made me thirstier Mike63 (4 of 5 stars) Good price B Button (1 of 5 stars) Drank 3 bottles on a hot day and got dehydrated! [Caption below the frame:] Physics tells us that negative reviews are really just positive reviews from people traveling backward in time.

Emoji Movie Reviews

Emoji Movie Reviews

https://www.xkcd.com/1870

https://www.explainxkcd.com/wiki/index.php/1870:_Emoji_Movie_Reviews

[Cueball and Megan are walking. Megan is checking her phone.] Megan: Reviews for The Emoji Movie are... not good. Cueball: People are just snobs about emoji. I like them! Language is cool and weird. [Zoom on Megan; Cueball is outside of the frame.] Megan: It's apparently 80% product placement. Cueball (off-screen): Whatever. So was The Lego Movie, and I liked that . [Zoom out; Cueball looks at Megan's phone.] Megan: It features the emoji we all know and love - with a "Meh" emoji in the starring role! Cueball: Wait... a "Meh" emoji? Megan: I wondered about that, too; the others are all familiar. Do they mean 😒? Or 😐 or 😕? Cueball: That's a little confusing... [Zoom in on both heads; Megan is looking at her phone.] Megan: There's a joke in the movie about the "emoji that no one uses" that includes the eggplant emoji. Cueball: ...was that on purpose? Or did they not run the script by enough people? [Megan and Cueball continue walking.] Megan: Here's a line from the Wikipedia plot summary: Megan: Gene and Hi-5 come to a piracy app where they meet the hacker emoji Jailbreak, who wants to reach Dropbox so that she can live in the cloud. Cueball: Okay. Cueball: It's possible this movie is bad.

This comic discusses reviews of The Emoji Movie (previously covered in 1857: Emoji Movie ) between the cynical, Internet-equipped point of view of Megan and Cueball's language-enthusiasm. They ultimately agree the movie is bad. The Emoji Movie was released to theaters in late July 2017 and received nearly universally-negative reviews. It is particularly notable for having a rating below 10% on the review aggregator site Rotten Tomatoes . Many critics of movie point to superficial problems like the subject matter and the product placement. Here, that train of thought is articulated a bit more, and ultimately it's argued that the real reason the film is bad is because the creators cashed in on a trend without doing any research into it. When Megan first mentions the movie's negative reviews, Cueball initially accuses the audience of being overly judgmental of the subject matter. He further expresses his fondness for emoji as an interesting and quirky part of language. Cueball offers an early defense of The Emoji Movie by comparing it to The Lego Movie , which – despite effectively being an entire movie of product placement for Lego – received generally positive reviews. They start talking about a "Meh" emoji, who is the main character of the movie. The idea of " meh " as an emoji is actually ambiguous, as various emoji can be used to describe being unimpressed or neutral towards something. As given in examples from comic those are 😒 ( U+1F612 Unamused face), 😐 (U+1F610 Neutral face) or 😕 (U+1F615 Confused face). The selection of a less identifiable emoji for the leading role also contrasts with the fact that the movie also features more iconic emojis. Megan mentions that one of the attempted jokes in the film is a room full of emojis that are unpopular. Bizarrely, the eggplant emoji (🍆, U+1F346 Aubergine) is featured among them. This is a clear sign that the creative team in charge of this movie had limited first-hand experience with SMS messaging; as any frequent user of emoji will tell you, the 🍆 is frequently used as a sly stand-in for a penis, due to its similar shape. Cueball's reaction is to ask whether the creators of this film intentionally got this wrong (perhaps as a joke, or active denial of the emoji's common usage because it wouldn't be appropriate for a kid's movie). The line from the Wikipedia plot summary was a direct quote from Wikipedia . The sentence was introduced to the article by editor Voicebox64 on July 28, 2017 , and the exact phrasing quoted in the comic came from editor SubZeroSilver on July 30 . Cueball's response to hearing this line, stating that "it's possible this movie is bad", is likely due to the fact that piracy is the act of obtaining media illegally, generally without paying for it over the internet. This means that there is a very low chance of there being a 'piracy app', as an app such as this would not be allowed on any online app store. (A few piracy-focused apps do exist, like Popcorn Time , but they are not available in app stores for obvious reasons.) Jailbreak's design in the movie also does not bear a resemblance to hacker-like emojis at the time the movie was released (👩‍💻, 👨‍💻) or any existing emoji. (This lack of any existent hacker emoji, however, is addressed in the movie; when pressed on the topic, Jailbreak is revealed to be the princess emoji in disguise.) Furthermore, the blatant product placement of the protagonists' desires to use Dropbox, the proprietary software of a for-profit company, is the final nail in the movie's coffin in Cueball's opinion. The fact that Jailbreak's plans to live 'in the cloud' superficially match with Dropbox's cloud storage service does not salvage the concept. The title text is an argument against the common prediction that emojis would lead to less nuanced communication, and as evidence it cites the thinking face emoji (🤔) and upside-down smiley (🙃), both of which are used in ways that have developed difficult-to-define nuances and meanings. In the first case, the thinking-face emoji is often used sarcastically -- for example, feigning confusion when presented with contradictory/hypocritical statements from the same source. The upside-down smiley also has specific usage, indicating a tone of silliness or even insanity, and is also often used sarcastically, such as when reacting to bad news. [Cueball and Megan are walking. Megan is checking her phone.] Megan: Reviews for The Emoji Movie are... not good. Cueball: People are just snobs about emoji. I like them! Language is cool and weird. [Zoom on Megan; Cueball is outside of the frame.] Megan: It's apparently 80% product placement. Cueball (off-screen): Whatever. So was The Lego Movie, and I liked that . [Zoom out; Cueball looks at Megan's phone.] Megan: It features the emoji we all know and love - with a "Meh" emoji in the starring role! Cueball: Wait... a "Meh" emoji? Megan: I wondered about that, too; the others are all familiar. Do they mean 😒? Or 😐 or 😕? Cueball: That's a little confusing... [Zoom in on both heads; Megan is looking at her phone.] Megan: There's a joke in the movie about the "emoji that no one uses" that includes the eggplant emoji. Cueball: ...was that on purpose? Or did they not run the script by enough people? [Megan and Cueball continue walking.] Megan: Here's a line from the Wikipedia plot summary: Megan: Gene and Hi-5 come to a piracy app where they meet the hacker emoji Jailbreak, who wants to reach Dropbox so that she can live in the cloud. Cueball: Okay. Cueball: It's possible this movie is bad.

Bun Alert

Bun Alert

https://www.xkcd.com/1871

https://www.explainxkcd.com/wiki/index.php/1871:_Bun_Alert

[Beret Guy and Ponytail see a rabbit sitting in the grass; Beret Guy points to the bun.] Beret Guy: Bun alert! Ponytail: Oh, yeah! Cute! Beret Guy: Gotta document this. I'll notify everyone, send out a push alert. Ponytail: ...to who? [Zoom in on Beret Guy and Ponytail; Beret Guy taps on his phone.] Beret Guy: Everyone subscribed to the alert system. Ponytail: Alert system? Beret Guy: Yeah! We built it over the last few years. It's pretty small. Still looking for investors. Ponytail: But... why are you alerting people about rabbits? [Zoom out; Beret Guy puts away his phone, points at the bun.] Beret Guy: I mean...look at them. They're like loaves of bread that hop. Ponytail: I see. Beret Guy: People need to know. [Zoom on Beret Guy in a frameless panel.] Beret Guy: They need to know: Beret Guy: There are buns. [Ponytail walks off, Megan comes running towards Beret Guy with a phone in her hand.] Ponytail: Okay, uhh, I'm gonna go. Megan: I got the alert! Where's the bun? Is it small? Beret Guy: Extremely. Megan: Oh my God.

The comic opens with Beret Guy identifying a "bun", an informal term for a rabbit also used in 1682: Bun . The title text of that former comic specifically refers to sending out a "BUN ALERT" to friends and family with location and photographic evidence of the bun, so in this comic, that concept appears to have been elevated from a simple mass SMS/MMS message to a standalone application. Upon seeing the bun, Beret Guy uses his phone to send an alert about the "Bun" with a push notification . He is still looking for investors, though such an app would likely not appeal to a wide market. In response to Ponytail 's confusion, he explains that bunnies are "like loaves of bread that hop" making a pun by comparing rabbits to bread, as "bun" can commonly refer to a small loaf of bread. Beret Guy is known to be fascinated with bakeries, as shown in the comics 434: xkcd Goes to the Airport , 442: xkcd Loves the Discovery Channel , or 452: Mission , so it makes sense that this sort of comparison occurs to him. It is known that the word "bun" is similar to the word "pun". Beret Guy has a history of misinterpreting statements and phrases (and often making said misinterpretations correct through some strange power of his), so it is not implausible that he actually genuinely thinks that these "buns" are bread products that somehow behave exactly like rabbits. As Ponytail leaves, apparently to remove herself from the situation, Megan hurriedly approaches, excited to see the "bun". This serves as a punchline as, despite Ponytail appearing to be the voice of reason, it seems that Beret Guy's inane bun alert system has gathered a dedicated following after all. Megan's question "Is it small?" and her amazement when she finds out that it is parallels the idea in 1682: Bun where the bun's size is said to be inversely correlated with its status; smaller buns such as the one in this comic are thought of as higher-ranking "king buns" by the characters in both strips. In real life, smaller rabbits are more likely to simply be young. It is also possible that she simply thinks smaller buns are cuter, which might have been the motivation for the whole bun-ranking system thing in the first place. The title text refers to buns being crepuscular and nocturnal animals, meaning they are primarily active at twilight and night, respectively. This means that someone with the app would get a lot of notifications while they would most likely be asleep. Many smartphones have a "Do Not Disturb" mode that can be activated so that only select communications (i.e. direct calls) will actually set off the ringer/vibration, and all others will simply be added to the device's notification queue; such a function can be scheduled to automatically activate during the period when the user is asleep. The title text unironically points out a prime example of the need for such a function: if something is likely to notify your device late at night, then you should make sure that those notifications are silenced by the Do Not Disturb function. The bun alert reappears in 1903: Bun Trend , where Beret Guy receives the alert. [Beret Guy and Ponytail see a rabbit sitting in the grass; Beret Guy points to the bun.] Beret Guy: Bun alert! Ponytail: Oh, yeah! Cute! Beret Guy: Gotta document this. I'll notify everyone, send out a push alert. Ponytail: ...to who? [Zoom in on Beret Guy and Ponytail; Beret Guy taps on his phone.] Beret Guy: Everyone subscribed to the alert system. Ponytail: Alert system? Beret Guy: Yeah! We built it over the last few years. It's pretty small. Still looking for investors. Ponytail: But... why are you alerting people about rabbits? [Zoom out; Beret Guy puts away his phone, points at the bun.] Beret Guy: I mean...look at them. They're like loaves of bread that hop. Ponytail: I see. Beret Guy: People need to know. [Zoom on Beret Guy in a frameless panel.] Beret Guy: They need to know: Beret Guy: There are buns. [Ponytail walks off, Megan comes running towards Beret Guy with a phone in her hand.] Ponytail: Okay, uhh, I'm gonna go. Megan: I got the alert! Where's the bun? Is it small? Beret Guy: Extremely. Megan: Oh my God.

Backup Batteries

Backup Batteries

https://www.xkcd.com/1872

https://www.explainxkcd.com/wiki/index.php/1872:_Backup_Batteries

[Cueball is talking to White Hat. He is wearing a large backpack and holding a phone battery.] Cueball: I get stressed out when my phone battery is low, so I carry this backup battery. Cueball: But then I worry about the backup running low, so I carry this second backup. Cueball: Then I worry— [Caption below the frame:] My bag is 90% backup batteries.

Most smartphones (except iPhones and a few others) use replaceable batteries. So it's often possible to buy additional batteries and use them as a backup in case there is no external power source available to recharge the phone. Otherwise it's possible to buy a charging device (also with batteries) that could be connected via cable to the phone to recharge the internal battery. Since there is no cable in the comic picture Cueball probably shows a battery that could replace an empty one in the phone. Cueball gets stressed when his phone is at low battery because the device may run out at any moment, interrupting his activities. In an effort to prevent stress, Cueball decides to carry a backup battery so he can just replace the current battery when it runs low. Cueball realizes that the backup battery itself is prone to depletion, and so he carries a second. He then comes to the same realization for the second backup battery, and indeed every subsequent battery he can carry. Finally this would lead to an unending series of backup batteries, hence his speech is cut off, becoming unending as well. What Cueball never grasps is that his irrational need to hoard a supply of batteries tending to the infinite is the real cause of his stress. In reality, he only needs to consider the maximum amount of time that he spends between recharging his phone, and divide that by the average lifespan of a phone battery, and round up that figure to get the minimum number of batteries required to avoid a power outage (multiplied by 1.5 if the mere state of running low causes stress). If he charges up his phone and backup batteries every night, he would only need 2 to 3 backup batteries, tops. The title text says that Cueball's backpack will turn red if it is less then 20% of it is filled with batteries, similar to the battery indicator on a smartphone when at low battery to warn the user. Cueball probably gets similarly stressed when that happens, perhaps requiring a backup backup-battery backpack. Most backpacks do not have this function. [ citation needed ] It is unclear by what mechanism the backpack turns red or detects that it should do so. That Randall has issues with low battery power on cell phones can be seen in the earlier comics 1373: Screenshot and 1802: Phone and in the later comic 1965: Background Apps . [Cueball is talking to White Hat. He is wearing a large backpack and holding a phone battery.] Cueball: I get stressed out when my phone battery is low, so I carry this backup battery. Cueball: But then I worry about the backup running low, so I carry this second backup. Cueball: Then I worry— [Caption below the frame:] My bag is 90% backup batteries.

Email Reply

Email Reply

https://www.xkcd.com/1873

https://www.explainxkcd.com/wiki/index.php/1873:_Email_Reply

[Cueball sits at a desk, typing on a laptop. The following message is displayed above him:] Dear Kevin, I'm sorry it's taken me two years to reply to your email. I've built up so much stress and anxiety around my email inbox; it's an unhealthy dynamic which is more psychological than technical. I've tried one magical solution after another, and as each one has failed, deep down I've grown more certain that the problem isn't email – it's me. Regardless, these are my issues, not yours; you're my friend, and I owe you the basic courtesy of a response. I apologize for my neglect, and I hope you haven't been too hurt by my failure to reply. Anyway, I appreciate your invitation to join your professional network on LinkedIn, but I'm afraid I must decline...

Cueball is sitting at his desk writing an email . He is responding to Kevin, who sent him an email two years ago. Cueball is so far behind in responding to his email, he goes to great lengths to apologize for it. Instead of blaming the email culture which creates enormous quantities of messages, he blames himself for not keeping up. Failing to answer emails is a common symptom of general anxiety disorder, a problem which can snowball out of control as more and more emails go unread or unanswered. At this point in the email, the reader assumes that Kevin's message really demanded a faster response, being personal and timely. Then Cueball reveals that the email is just the ubiquitous LinkedIn invitation. LinkedIn is a professional networking site notorious for inundating its users with emails inviting them to connect to other users (frequently people the user has little-to-no connection to), as well as any email contacts of their users whether or not they actually belong to LinkedIn themselves. Thus, an invitation to connect to LinkedIn is most often immediately deleted or ignored. A less socially anxious person who understands the irrelevance of such an email would not worry about failing to respond to such a request at all, and certainly would not pour his heart out in apology for failing to reply. The title text makes Cueball's overinvestment in the email even more exaggerated, suggesting that Cueball is rejecting the invitation not because of its pointlessness, but because he feels that as a bad friend who doesn't respond to emails, he is no longer even worthy of it. One could interpret the letter as a passive-aggressive lashing out, but that does not seem to be in character for Cueball . Had the character worn a Black Hat though... Cueball's difficulty in checking his email was previously addressed in 1783: Emails (trivia: the comic numbers 1783 and 1873 are anagrammatic). This is the fourth comic within a year where Randall uses "Kevin" as a go-to-name, although it was half a year since last time in 1795: All You Can Eat . See details in that comic's trivia . [Cueball sits at a desk, typing on a laptop. The following message is displayed above him:] Dear Kevin, I'm sorry it's taken me two years to reply to your email. I've built up so much stress and anxiety around my email inbox; it's an unhealthy dynamic which is more psychological than technical. I've tried one magical solution after another, and as each one has failed, deep down I've grown more certain that the problem isn't email – it's me. Regardless, these are my issues, not yours; you're my friend, and I owe you the basic courtesy of a response. I apologize for my neglect, and I hope you haven't been too hurt by my failure to reply. Anyway, I appreciate your invitation to join your professional network on LinkedIn, but I'm afraid I must decline...

Geologic Faults

Geologic Faults

https://www.xkcd.com/1874

https://www.explainxkcd.com/wiki/index.php/1874:_Geologic_Faults

[The comic shows nine different schematic views to present geographic faults and some more.] [Two planes with a slip fault drifting away to the left and right.] Normal fault [Two planes with a slip fault drifting against each other from left and right.] Reverse fault [Two planes moving sideways away from each other.] Transverse fault [The left plate is moving over the right plate, while the right plate is sliding under the left one] Thrust fault [Two planes drifting away and the connection between them gets smaller, like a piece of taffy candy.] Taffy fault [On top of both planes a small piece with splints holds them together.] Splinted fault [The two planes pressing together with a piece in the middle moving upwards.] Squeezed-bar-of-soap fault [The right plane is connected to the left and swinging up and down.] Apple power cable fault [One side with a thin connector and the other with an evenly spaced hole connecting the planes together. The pieces fit together like a puzzle.] Brio fault Faults have been mentioned several times in xkcd. Thrust faults were previously mentioned in 1082: Geology , and in the title text of 1388: Subduction License , Beret Guy tells Cueball he can't be a 'normal' roomate because in his motion he is creating a reverse fault. A similar joke to the Apple power cable fault is used in 1406: Universal Converter Box .

This comic appears to be a successor to 1714: Volcano Types . Similar to its predecessor, the comic explores several phenomena (in this case, geologic faults), both real, and several made up for the point of a joke. A fault is a geologic feature involving a planar fracture with displacement in a large mass of rock, including the boundaries of two tectonic plates . Normal fault In a normal fault , the hanging wall (the lower wall; right) moves downward relative to the footwall (the upper wall; left). The Earth's crust is extended in this type of fault. Reverse fault A reverse fault is basically the opposite of a normal fault. The hanging wall (left) moves upward relative to the footwall (right), and the Earth's crust is compressed. Transverse fault A transverse fault, also known as a transform fault , is where the two plates move parallel to each other, but in opposite directions. Thrust fault A thrust fault is when older rocks are pushed (or thrust) on top of younger rocks. The angles are typically lower (more horizontal) than in reverse faults. Taffy fault This appears to involve one tectonic plate, that is being stretched out like a piece of taffy . Ductile crustal thinning of this type actually occurs in rocks under tension at sufficient depths . Such deformation is not a fault, however, as there is no fracture along which movement takes place. Splinted fault This appears to be a normal or reverse fault that someone has attempted to fix in position by attaching a large splint, as you might with a broken bone. This is unlikely to prove effective. [ citation needed ] Squeezed-bar-of-soap fault Two plates seem to be moving towards each other, while a third smaller plate is squeezed between them and pushed upwards, much as a slippery bar of soap might pop up when squeezed between two hands. Apple power cable fault The plate appears to have been twisted and bent so many times that parts of it are fraying and the end is splitting apart, similar to a damaged Apple MagSafe connector. Brio fault BRIO is a company from Sweden that makes wooden toys, including train sets. The Brio fault seems to be two tectonic plates which join together like the Brio train track pieces do. (However, this join is obvously incorrect because of the height difference.) (Title text) Torn-bag-of-potato-chips-where-the-tear-is-rapidly-growing fault The title text refers to when a bag of chips gets a tear in it. When this happens, any further stress on the bag, such as reaching in to get more chips, can easily increase the size of the tear, sometimes very quickly. It would be frightening to live near a fault that behaved like this [ citation needed ] because it could cause major seismic events very quickly. If you were close enough to the fault, you might be afraid that the crack would grow underneath you, causing you to fall into the bag of chips — or, rather, the Earth. [The comic shows nine different schematic views to present geographic faults and some more.] [Two planes with a slip fault drifting away to the left and right.] Normal fault [Two planes with a slip fault drifting against each other from left and right.] Reverse fault [Two planes moving sideways away from each other.] Transverse fault [The left plate is moving over the right plate, while the right plate is sliding under the left one] Thrust fault [Two planes drifting away and the connection between them gets smaller, like a piece of taffy candy.] Taffy fault [On top of both planes a small piece with splints holds them together.] Splinted fault [The two planes pressing together with a piece in the middle moving upwards.] Squeezed-bar-of-soap fault [The right plane is connected to the left and swinging up and down.] Apple power cable fault [One side with a thin connector and the other with an evenly spaced hole connecting the planes together. The pieces fit together like a puzzle.] Brio fault Faults have been mentioned several times in xkcd. Thrust faults were previously mentioned in 1082: Geology , and in the title text of 1388: Subduction License , Beret Guy tells Cueball he can't be a 'normal' roomate because in his motion he is creating a reverse fault. A similar joke to the Apple power cable fault is used in 1406: Universal Converter Box .

Computers vs Humans

Computers vs Humans

https://www.xkcd.com/1875

https://www.explainxkcd.com/wiki/index.php/1875:_Computers_vs_Humans

[A laptop sits on a desk with office chair while Cueball is sitting with his back towards the desk in a sofa while he is reading from something in his hands, a book or a smartphone.] Laptop: We computers finally beat you humans at Go. Cueball: Yup. Laptop: Sucks for you! Cueball: Mm hmm. [Same setting in a frameless panel.] Laptop: What's next? Which quintessentially human thing should we learn to do better than you? Cueball: Being too cool to care about stuff. [Same setting.] Laptop: Okay, I'll apply 10,000 years of CPU time to the initial— Cueball: Sounds like you've already lost. Laptop: Damn. This is hard. Cueball: Is it? Never noticed.

Cueball 's laptop smugly crows to its owner about how computers have proven their intellectual superiority over humans yet again. In May 2017, a Google artificial intelligence beat the world's best Go player at the game. Go is a very complex and deep board game, so this could seem alarming to a person concerned about competing with computers. However, Cueball seems too focused on his book or phone to care. He remains nonchalant in the face of this news, and suggests that computers learn next to become "too cool to care about stuff" themselves. The computer gets to work preparing to outdo humans at not caring. However, by expending the physical effort to set up the algorithm, it proves that it cares about reaching this goal, a contradiction that Cueball points out. Cueball further rubs it in by coolly stating that he doesn't even have to try to act the way he acts – much like a wide range of everyday human behaviors, such as moving around, or recognizing objects in images, require very little conscious effort, while being quite hard for machines to emulate. Relative strengths of human versus computer go players was previously mentioned in 1263: Reassuring . This comic also presents something that looks like a reassuring parable (something humans can do which computers are not yet able to do). An irony here is that, unlike in the cartoon, it is very easy to make a computer not care about something. It is making it care about anything that would be quite difficult. The title text elaborates on the hypothetical paradox of computers trying not to care about stuff. Neural network programs are developed by training them with sample inputs and the desired output. When the end goal is not to care, that is, that the output is unaffected by this input, then any examples where the output did depend on the input would be sarcasm: the use of irony to mock or to convey contempt. Randall already noticed that computers would soon beat humans in Go back in 2012 in the comic 1002: Game AIs and a year later the event is so close that it became the main topic of 1263: Reassuring . The present comic could almost be seen as a continuation of Reassuring. [A laptop sits on a desk with office chair while Cueball is sitting with his back towards the desk in a sofa while he is reading from something in his hands, a book or a smartphone.] Laptop: We computers finally beat you humans at Go. Cueball: Yup. Laptop: Sucks for you! Cueball: Mm hmm. [Same setting in a frameless panel.] Laptop: What's next? Which quintessentially human thing should we learn to do better than you? Cueball: Being too cool to care about stuff. [Same setting.] Laptop: Okay, I'll apply 10,000 years of CPU time to the initial— Cueball: Sounds like you've already lost. Laptop: Damn. This is hard. Cueball: Is it? Never noticed.

Eclipse Searches

Eclipse Searches

https://www.xkcd.com/1876

https://www.explainxkcd.com/wiki/index.php/1876:_Eclipse_Searches

[Cueball walks up to Megan while holding his smartphone up in his hand. Megan sits in an office chair in front of her desk with an open laptop on it. She turns her head towards him. A footnote to Cueball's speech is at the bottom right of the panel.] Cueball: Have you seen this cool map* showing how Google searches for "eclipse" trace the eclipse's path? Megan: Yeah! Megan: But you know what else I noticed? Cueball: What? Footnote: *wapo.st/2vkgIBv [Two panels are on top of each other. In the smaller top panel a colored graph is shown with a blue growing graph and a steeper growing red graph above it. Both are labeled. The x-axis (a black line) has labels and arrows below it in red and blue to indicate time periods. Text above the graph:] Searches for "eclipse" in the weeks before the eclipse are outpacing searches for "election" in the weeks before the 2016 election. Red line: Eclipse Blue line: Election Red x-axis labels: 2017 →|← July →|← August → Blue x-axis labels: 2016 - September →|← October →|← [Behind the top panel is a second larger panel slightly lower end more to the right. The visible part at the bottom of this panel is showing the same line graphs with the one from the election going past the election day. The x-axis labels ranges over a later time. The blue graph has a huge peak at the election day, visible in the part of the panel to the right of the top panel) and this date is written in a blue dot on the label. Similar the date of the Eclipse is written in a red dot. The red graph above the blue still ends in dots before the expected peak, as it is in the future.] Red line: Eclipse Blue line: Election Red x-axis labels: 2017 - July →|← August 21 → Blue x-axis labels: 2016 - October →|← November 8 → [Megan with her hands on the laptop and Cueball are both looking at the laptop. Beat panel.] [Cueball stands again and Megan has taken her hands down from the laptop.] Cueball: This is gonna be bad, isn't it? Megan: If you're planning to be on the road next Monday, bring water.

This comic is the first of five consecutive comics published in the week before and during the solar eclipse occurring on Monday, August 21, 2017 which was visible as a total solar eclipse within a band across the contiguous United States from west to east and visible as a partial eclipse across the entire contiguous United States and beyond. The other comics are 1877: Eclipse Science , 1878: Earth Orbital Diagram , 1879: Eclipse Birds , and 1880: Eclipse Review . Cueball comes to tell Megan about a cool map showing that searches on Google on the word Eclipse trace the same path across the USA as the totality band does, implying that those living in the zone are more interested than the rest of the US population. The " cool map " is hosted by The Washington Post and sourced from Google Trends data. The link shown in the comic is here: wapo.st/2vkgIBv (subscription required); an archived version is available here at archive.org Since the eclipse searches are outpacing the 2016 election searches now, this is saying the eclipse popularity is going to rocket upwards just before the eclipse. Cueball is thus warned by Megan that the extreme amount of social media interest in the eclipse may lead to massive traffic jams, as last days frenzy regarding the eclipse will cause an enormous amount of people to decide to go to the eclipse in the last moment, causing huge traffic jams. (These traffic jams may be analogous to long lines at the polls or traffic jams caused by people trying to get to the polls.) Also as soon as people driving on the freeway enters the totality zone it has been seen happening that people just stop their cars and get out blocking the roads. This time also the eclipse-viewers will wish to post their content on the social media which might also cause a cyber traffic jam, in which users may find that they experience delays in sending or receiving data due to a high demand on telecommunications infrastructure. Megan tells Cueball to bring water if he is on the road during the totality, the implication being that people who are on the road may be stuck in their vehicles for long periods of time, and thus need refreshments. In the graph charting interest in the 2016 US presidential election , November 8 is an important date as it was the day the election was held. August 21, 2017 refers to the date of the then upcoming solar eclipse. The title text refers to the total eclipses from 1970 and 1979 which were also visible in the US, but both only for a few states. The traffic jams will be worse than those caused by previous eclipses, as we did not have viral social media in the 1970s, and also much less traffic on the roads. [Cueball walks up to Megan while holding his smartphone up in his hand. Megan sits in an office chair in front of her desk with an open laptop on it. She turns her head towards him. A footnote to Cueball's speech is at the bottom right of the panel.] Cueball: Have you seen this cool map* showing how Google searches for "eclipse" trace the eclipse's path? Megan: Yeah! Megan: But you know what else I noticed? Cueball: What? Footnote: *wapo.st/2vkgIBv [Two panels are on top of each other. In the smaller top panel a colored graph is shown with a blue growing graph and a steeper growing red graph above it. Both are labeled. The x-axis (a black line) has labels and arrows below it in red and blue to indicate time periods. Text above the graph:] Searches for "eclipse" in the weeks before the eclipse are outpacing searches for "election" in the weeks before the 2016 election. Red line: Eclipse Blue line: Election Red x-axis labels: 2017 →|← July →|← August → Blue x-axis labels: 2016 - September →|← October →|← [Behind the top panel is a second larger panel slightly lower end more to the right. The visible part at the bottom of this panel is showing the same line graphs with the one from the election going past the election day. The x-axis labels ranges over a later time. The blue graph has a huge peak at the election day, visible in the part of the panel to the right of the top panel) and this date is written in a blue dot on the label. Similar the date of the Eclipse is written in a red dot. The red graph above the blue still ends in dots before the expected peak, as it is in the future.] Red line: Eclipse Blue line: Election Red x-axis labels: 2017 - July →|← August 21 → Blue x-axis labels: 2016 - October →|← November 8 → [Megan with her hands on the laptop and Cueball are both looking at the laptop. Beat panel.] [Cueball stands again and Megan has taken her hands down from the laptop.] Cueball: This is gonna be bad, isn't it? Megan: If you're planning to be on the road next Monday, bring water.

Eclipse Science

Eclipse Science

https://www.xkcd.com/1877

https://www.explainxkcd.com/wiki/index.php/1877:_Eclipse_Science

[Hairy is speaking into a microphone while interviewing Megan.] Hairy: Tell us, are you scientists excited for the eclipse? Megan: Sure, lots of people are! [Zoom in on Megans head.] Hairy (off-panel): Is this a big moment for science? Megan: It's a big moment for the sky. [Same setting as first panel in a wider panel.] Hairy: Are people really excited enough about science to travel to see it? Megan: Honestly, it's not that scientific. I mean, it's cool if you're into astronomy, but it's also cool if you're, like, aware of the sun. [Same setting.] Hairy: But there's lots of science involved. Megan: I guess? There's lots of science involved in the Olympics, but you don't need to be a scientist to watch. [Megan holds a hand out towards Hairy.] Megan: It's not like the concept is all that arcane or mathematical. It's a thing going in front of another thing. [Zoom in on Megan holding both arms out.] Hairy (off-panel): Then why are you so excited? Megan: I'm excited because it's a nearly once-in-a-lifetime chance to watch the sun go dark, hear birds freak out, and see a glowing ring appear in the sky with a sunset on every horizon. [Back to same setting as in the first panel.] Hairy : Will you be making any scientific observations? Megan: I will be like, "Holy shit, look at the sky." Megan: Maybe also "This is so cool." Megan: We'll see!

This comic is the second of five consecutive comics published in the week before and during the solar eclipse occurring on Monday, August 21, 2017 which was visible as a total solar eclipse within a band across the contiguous United States from west to east and visible as a partial eclipse across the entire contiguous United States and beyond. The other comics are 1876: Eclipse Searches , 1878: Earth Orbital Diagram , 1879: Eclipse Birds , and 1880: Eclipse Review . This comic reflects on various reasons scientists have for being interested in a total solar eclipse. An eclipse is an astronomical event, which most laypeople associate with science and thus might assume would be of interest to scientists. However, when the reporter probes Megan on scientific interest on the eclipse, Megan gives short and sarcastic answers, downplaying any experimental significance of the phenomenon and indicating that her only interest is in spectacle rather than science. She also makes the point that science is no more involved in an eclipse than any other spectator event, and does not work to observe phenomena without any interest in discovery. Eclipses are well-understood events and there is no lack of models for explaining the physics behind them; the alignment of bodies in space is a result of orbital mechanics which are present at all times, making the whole event only significant to the observer. While some astronomers might be testing elaborate hypotheses during an eclipse, for other scientists (e.g. organic chemists and paleontologists) it is just a once in a long time (maybe even once in a lifetime) event which is visually interesting. Some biologists may, however, be collecting data on the behavior of animals during an eclipse, which is poorly understood due to its rarity. Megan's point is that in 2017 (and for several decades/centuries previous) eclipses are thoroughly understood. Wikipedia has a listing of every eclipse that will occur in the 21st Century , to include the coordinates and time of greatest eclipse. While eclipses offer a unique opportunity for ground based observation of the Sun's outer layers the majority of the study of the sun is done by satellites that do not require an eclipse to take readings. The title text refers to a 1919 experiment during an eclipse to observe gravitational deflection of light waves. The 1919 experiment was the first strong experimental confirmation of Einstein's then-new theory. One century later, general relativity has been tested and confirmed in so many different ways that pretty solid is a vast understatement. [Hairy is speaking into a microphone while interviewing Megan.] Hairy: Tell us, are you scientists excited for the eclipse? Megan: Sure, lots of people are! [Zoom in on Megans head.] Hairy (off-panel): Is this a big moment for science? Megan: It's a big moment for the sky. [Same setting as first panel in a wider panel.] Hairy: Are people really excited enough about science to travel to see it? Megan: Honestly, it's not that scientific. I mean, it's cool if you're into astronomy, but it's also cool if you're, like, aware of the sun. [Same setting.] Hairy: But there's lots of science involved. Megan: I guess? There's lots of science involved in the Olympics, but you don't need to be a scientist to watch. [Megan holds a hand out towards Hairy.] Megan: It's not like the concept is all that arcane or mathematical. It's a thing going in front of another thing. [Zoom in on Megan holding both arms out.] Hairy (off-panel): Then why are you so excited? Megan: I'm excited because it's a nearly once-in-a-lifetime chance to watch the sun go dark, hear birds freak out, and see a glowing ring appear in the sky with a sunset on every horizon. [Back to same setting as in the first panel.] Hairy : Will you be making any scientific observations? Megan: I will be like, "Holy shit, look at the sky." Megan: Maybe also "This is so cool." Megan: We'll see!

Earth Orbital Diagram

Earth Orbital Diagram

https://www.xkcd.com/1878

https://www.explainxkcd.com/wiki/index.php/1878:_Earth_Orbital_Diagram

[An orbital map of the Earth is shown. The Sun is in the center, the Earth is at the right bottom, and the Moon is left below the Earth.] Why isn't there an eclipse every month? This is a common question! The answer is made clear by a quick look at the Earth's orbital diagram: [Label Sun:] Solar plexus [Label on the Earth's plane:] Sagittal plane [Labels on Earth's orbit (beginning at the Earth counterclockwise):] Perihelix, Declension, Obsequity, Hypothecate, Enceliopsis, Equinox ( Solstice in British English) [Two angles in the plane are labeled as:] Determinant of the date of Easter, Arctangent [The plane of the Moon is pictured in a small angle to the Earth's plane and named Astral Plane. The angle is presented between two lines (Greek Nu or Gamma and a double Greek Chi) and identified by a character that looks similar to a Greek Phi but with two vertical lines.] [The labels at the Moon's path are:] Tropopause, Prolapse, Errata. [An arrow points to the Earth at the zero meridian on the equator. The label reads:] Dimples of Venus

This comic is the third of five consecutive comics published in the week before and during the solar eclipse occurring on Monday, August 21, 2017 which was visible as a total solar eclipse within a band across the contiguous United States from west to east and visible as a partial eclipse across the entire contiguous United States and beyond. The other comics are 1876: Eclipse Searches , 1877: Eclipse Science , 1879: Eclipse Birds , and 1880: Eclipse Review . The comic claims that the reason that eclipses don't happen every month is simple to understand by looking at an orbital diagram. Ironically, the cartoon has so many parts and labels that it is far more difficult to understand than is implied. While the graph itself is based on astronomical definitions , all the labels are nonsense in this context. In effect, the comic is a new take on a common joke in which a person asks a scientist a question, the scientist begins by saying "It's really quite simple", then proceeds to give a very lengthy and highly technical explanation that non-scientists would not be expected to understand. Diagrams for eclipses commonly include things that laypeople may not find relevant, without explanation, such as the umbra and penumbra. All of the labels in the diagram are complicated words or phrases. Some are related to orbital mechanics (e.g. "equinox" and "perihelion"), while others are wholly unrelated or even made up. Each label is nonsensical in its place in the diagram. Compare/contrast with the standard Kepler Orbit diagram. The title text references warnings to not look directly into the sun, but parodies those warnings by referring to 'orbit', the anatomical term for the eye socket. All items are not drawn to scale. Neither the sizes of the celestial objects are that similar as shown nor the orbits are. The real scales are shown in this table: When the distance Sun-Earth is scaled to one meter or below neither Moon nor Earth can be seen by the human eye. Arctangent Astral plane Declension Determinant of the date of Easter Dimples of Venus Enceliopsis Equinox / Solstice Equinox and Solstice have very different meanings: Both types occur because the Earth's rotation axis is tilted (at 23.4 degrees) from its orbital plane (ecliptic) about the Sun. Jokingly insisting that two different terms are American/British variants of the same word has been the topic of 1677: Contrails . Hypothecate Obsequity Perihelix Prolapse Sagittal plane Solar plexus Tropopause Angle between the Astral and the Sagittal Planes Errata If the plane of where the Earth orbits the Sun and where the Moon orbits the Earth were completely aligned, then there would be a solar eclipse at every new moon (once every 29.5 days ) and a lunar eclipse at every full moon (half a lunar period about 14.7 days after a New Moon). However, the plane in which the Moon orbits the Earth is tilted with an inclination of 5 degrees relative to that of the ecliptic plane (the plane defined by the Earth's orbit around the Sun). Eclipses are only possible during two eclipse seasons each year (half a year apart) where for a period of 31 to 37 days the Sun is nearly aligned with the two points in the tilted Earth-Moon plane where the Moon crosses the ecliptic plane. During an eclipse season at the time of a new moon there will be solar eclipses visible from certain locations and during full moons there will be lunar eclipses. The real explanation of eclipses is evident from this xkcd comic, but is labeled with a fictional character similar to a Greek phi but with two vertical lines; the remaining labels also do not contribute to this explanation and exist only to distract or misinform or entertain the reader. Thus, there is some truth behind the statement, "The answer is made clear by a quick look," assuming a quick look means only a glance at the diagram/drawing without taking the time to read the labels. [An orbital map of the Earth is shown. The Sun is in the center, the Earth is at the right bottom, and the Moon is left below the Earth.] Why isn't there an eclipse every month? This is a common question! The answer is made clear by a quick look at the Earth's orbital diagram: [Label Sun:] Solar plexus [Label on the Earth's plane:] Sagittal plane [Labels on Earth's orbit (beginning at the Earth counterclockwise):] Perihelix, Declension, Obsequity, Hypothecate, Enceliopsis, Equinox ( Solstice in British English) [Two angles in the plane are labeled as:] Determinant of the date of Easter, Arctangent [The plane of the Moon is pictured in a small angle to the Earth's plane and named Astral Plane. The angle is presented between two lines (Greek Nu or Gamma and a double Greek Chi) and identified by a character that looks similar to a Greek Phi but with two vertical lines.] [The labels at the Moon's path are:] Tropopause, Prolapse, Errata. [An arrow points to the Earth at the zero meridian on the equator. The label reads:] Dimples of Venus

Eclipse Birds

Eclipse Birds

https://www.xkcd.com/1879

https://www.explainxkcd.com/wiki/index.php/1879:_Eclipse_Birds

[Cueball and Megan standing together looking to the right.] Cueball: I heard that during an eclipse the birds all freak out. Megan: I guess we'll see! [Beat panel, the white background sky turns at the top slightly darker.] [As the sky turns to dusk sounds can be heard. It's written above Cueball and Megan inside squiggly bubbles.] Chirp Chirp! Chirp! Peep peep peep! Squawk! [The sky is now nearly dark, more at the top of the panel. The sounds continue, written in similar bubbles.] Chirp! Clank clank clank The time is upon us! Peep! Kachunk Prepare the blood cauldron! Cueball: Wow. Megan: Isn't nature amazing?

This comic is the fourth of five consecutive comics published in the week before and during the solar eclipse occurring on Monday, August 21, 2017 which was visible as a total solar eclipse within a band across the contiguous United States from west to east and visible as a partial eclipse across the entire contiguous United States and beyond. The other comics are 1876: Eclipse Searches , 1877: Eclipse Science , 1878: Earth Orbital Diagram , and 1880: Eclipse Review . During an eclipse, birds and other animals show atypical behavior like they do in the case of the darkness in the night and the following sunrise. Birds stop singing during totality, then greet the return of the sun with a "dawn chorus". Owls, however, become active as do mosquitoes. But it's not easy to find studies about this behavior because the main focus lies mostly on the eclipse itself. And total solar eclipses are rare -- roughly every 18 months and then mostly not in the same region of this world. A nice article can be found here: Effects of the 2001 total solar eclipse on African wildlife . Hippos were so confused that their daily routine even on the next day was not back to normal. Baboons stopped feeding and a sun squirrel that fed in the afternoons didn't do so, while other larger animals like crocodiles, zebras, or lions were not affected. Butterflies settled and did not restart flying, mosquitoes appeared and settled before reappearing in the evening. Also, bees moved into a hive and didn't come out until the next morning. After the 2017 eclipse, NASA published some highlights . A video presents chirping crickets in Jefferson City, Missouri. The California Academy of Sciences supports a citizen science project about life responds . In this comic, Cueball tells Megan that this will happen. However, instead of just cheeping and screeching in a different pattern than birds actually do during an eclipse, in the comic, the birds begin to prepare to make a sacrifice to appease their gods, similar to how ancient cultures like the Aztecs are said to have acted . Megan remains strangely nonchalant, offering only a clichéd admiration of nature as the birds around her use fluent English to set up a sacrificial ritual. In the title text, it turns out that the birds are about to sacrifice Megan, and Cueball tells them to stop. But Megan tells him it is OK as she wants to try experiencing being carried to a blood cauldron as she won't get another chance until the next eclipse in the US on 8th of April, 2024 . (A small region around Carbondale, Illinois will experience two total eclipses in 7 years). [Cueball and Megan standing together looking to the right.] Cueball: I heard that during an eclipse the birds all freak out. Megan: I guess we'll see! [Beat panel, the white background sky turns at the top slightly darker.] [As the sky turns to dusk sounds can be heard. It's written above Cueball and Megan inside squiggly bubbles.] Chirp Chirp! Chirp! Peep peep peep! Squawk! [The sky is now nearly dark, more at the top of the panel. The sounds continue, written in similar bubbles.] Chirp! Clank clank clank The time is upon us! Peep! Kachunk Prepare the blood cauldron! Cueball: Wow. Megan: Isn't nature amazing?

Eclipse Review

Eclipse Review

https://www.xkcd.com/1880

https://www.explainxkcd.com/wiki/index.php/1880:_Eclipse_Review

[A scatter plot with five labeled dots is drawn. The x-axis reads "How cool it sounds like it would be" and the y-axis is labeled with "How cool it is to see in person".] [Bottom left] Planetary conjunction [Bottom middle] Supermoon [Low left-center] Lunar eclipse [Low-center middle] Partial solar eclipse [Upper right, with a dotted arrow above it pointing up] Total solar eclipse

This comic is the last of five consecutive comics published in the week before and during the solar eclipse occurring on Monday, August 21, 2017 which was visible as a total solar eclipse within a band across the contiguous United States from west to east and visible as a partial eclipse across the entire contiguous United States and beyond. The other comics are 1876: Eclipse Searches , 1877: Eclipse Science , 1878: Earth Orbital Diagram , and 1879: Eclipse Birds . The comic is another comparison graph, like 1775: Things You Learn or 1701: Speed and Danger . It contrasts how cool something sounds and how cool it actually is . It has five points on it, planetary conjunction, supermoon, lunar eclipse, partial solar eclipse, and total solar eclipse. While the four other things than total solar eclipse are relatively close to each other on the "how cool to see" scale, the graph is not even high enough to plot the total solar eclipse point as indicated by the dotted arrow showing that this point should be way higher up. This is as opposed to leaving the point out, as Randall did with the coconut in 388: Fuck Grapefruit , where it is only mentioned in the title text. This could be an indication that if the scale had been high enough to fit the total solar eclipse point, then the rest of the points would be on the x-axis without any indication of which would be cooler. A total solar eclipse correctly sounds like it is the coolest of the five, but it is vastly cooler to see it in person by a wide margin. It seems like Randall is trying to convince those who missed the eclipse this time to go watch in seven years when another total solar eclipse is visible in the USA. Planetary Conjunction In a planetary conjunction two or more planets are visible close together in the night sky. This happens relatively often because all planets lie in roughly the same plane around the sun (the Sagittal ecliptic ). This looks like two big stars close to each other, and isn't particularly exciting. Supermoon A supermoon is a full moon or a new moon that approximately coincides with the Moon's closest approach in its elliptic orbit around the Earth. This results in a larger-than-usual apparent size of the lunar disk, but a typical human doesn't recognize the difference. Nevertheless, in recent years the press has often announced supermoons as important astronomical events. The opposite of a supermoon is called a micromoon. A "supermoon" sounds very cool, but like a planetary conjunction it's almost indistinguishable in the average night sky (see 1394: Superm*n , and this list ) of other comics that have referred to the term). Lunar Eclipse A lunar eclipse occurs during the full moon and, like at a solar eclipse, happens only when the Moon is in the region where the orbital planes of the Moon and the Earth intersect. The Earth's shadow falls on the Moon, causing it to appear dark red. The moon doesn't generally darken completely due to some light still reaching the Moon through the outer layers of the Earth's atmosphere. As with solar eclipses, lunar eclipses occur on average once every six months, but they can be viewed by anyone who is on the night-time side of Earth during the eclipse, as opposed to only being visible from a small strip of the Earth's surface. A lunar eclipse looks noticeably different from a usual full moon, making it fairly cool. Partial Solar Eclipse There are three types of non-total solar eclipses . A partial eclipse occurs when the Sun and Moon are not exactly in line with an observer on Earth, and thus the Moon doesn't fully obscure the Sun. An annular eclipse occurs when the Sun and Moon do line up with an observer on Earth, but the Moon is too far away from earth to block the entire Sun. The Sun appears as a very bright ring, which is also called an annulus. A hybrid eclipse is an eclipse which is total when viewed from some parts of the earth, but is annular when viewed from others. These mixed eclipses are comparatively rare, even when compared with total eclipses. A large percentage of the continental United States experienced a partial eclipse along with the total solar eclipse on August 21st. A partial solar eclipse is quite cool, but nowhere near as dramatic as a sky-darkening total solar eclipse. Total Solar Eclipse The total solar eclipse is the topic of this and the four preceding comics. It occurs during the new moon, and happens only when the Sun and Moon are exactly in line with an observer on Earth and when the Moon appears large enough to fully obscure the Sun. Unlike a lunar eclipse, only a small portion of the Earth lies within the Moon's shadow at any given time, roughly a disc with a diameter of approx. 100 km. The disc moves very fast over the Earth's surface, meaning that at any given location eclipses can't last longer than a few minutes. At locations outside of this shadow-disc , in a region over a few thousand kilometers, the eclipse is partial. In the title text Randall reveals that he had traveled to a location in Missouri (possibly the Shaw Nature Reserve ) because at his home in Massachusetts the eclipse was only partial. And, without a doubt, the total solar eclipse was the coolest thing he ever has seen in his life. [A scatter plot with five labeled dots is drawn. The x-axis reads "How cool it sounds like it would be" and the y-axis is labeled with "How cool it is to see in person".] [Bottom left] Planetary conjunction [Bottom middle] Supermoon [Low left-center] Lunar eclipse [Low-center middle] Partial solar eclipse [Upper right, with a dotted arrow above it pointing up] Total solar eclipse

Drone Training

Drone Training

https://www.xkcd.com/1881

https://www.explainxkcd.com/wiki/index.php/1881:_Drone_Training

[Black Hat stands in front of a store counter facing White Hat who stands behind.] Black Hat: My drone keeps flying into the wrong rooms. Do you have anything to discourage it? White Hat: Sir, this is a pet store. Black Hat: Yeah, I was thinking one of those spray bottles for cats. White Hat: I don't think you can train a drone. [White Hat hands a spray bottle over the counter.] Black Hat: Eh, they say that about cats, too. Plus, these days they probably all come with deep learning or whatever. Drones, I mean. Maybe cats too. White Hat: Fine, here's a bottle. Black Hat: Do you sell a shock collar that can fit around a Roomba? White Hat: I'm going to have to ask you to leave.

In this comic, Black Hat enters a pet store run by White Hat . He wants to buy something to help him train his drone, which keeps flying into the wrong rooms. This is absurd as drones are semi-autonomous flying machines, not living creatures like dogs or cats, which can be trained to do tricks, or stay in the correct areas (inside his property). Alternatively, Black Hat could be developing a way to make drones sentient/autonomous in other to annoy other drone-owners when their drones don't obey them or to allow Black Hat's drones to annoy other people without Black Hat having to control them. He also wants a shock collar for his Roomba , which would train it to stay inside or at least on his lawn. Cat repellents are devices or substances for training cats or repelling them from furniture or other areas. An example of a cat repellent spray which can be created at home as shown here: Friendly (but Effective) Cat Repellent . Roomba is an autonomous robotic vacuum cleaner and controlling it by electric shocks from a shock collar , normally used for dogs, is more than questionable. Those collars are legal in the US but banned in nine other countries. A Roomba was previously mistaken for a dog in 1558: Vet . This might be playing with the concept of machine learning. Knowing Black Hat, he might be poking fun at people's assumptions that modern robots are more advanced than they actually are. It is also possible, however, that he just wants to terrify people with the idea of robot abuse/conditioning, and even more likely that he genuinely believes he can force robots to obey him via inflicting suffering. The title text may mean one of three things: The endeavor will become a total flop when the Roomba gets rid of the collar and terrorizes the neighborhood; as a result dogcatchers from the animal control service will arrest this "wild animal." Or animal control services will confiscate the Roomba to save it from its abusive owner. Or, possibly, the text refers to White Hat, who also owns a Roomba, and it will be taken into custody because it has not been trained with a shock collar. [Black Hat stands in front of a store counter facing White Hat who stands behind.] Black Hat: My drone keeps flying into the wrong rooms. Do you have anything to discourage it? White Hat: Sir, this is a pet store. Black Hat: Yeah, I was thinking one of those spray bottles for cats. White Hat: I don't think you can train a drone. [White Hat hands a spray bottle over the counter.] Black Hat: Eh, they say that about cats, too. Plus, these days they probably all come with deep learning or whatever. Drones, I mean. Maybe cats too. White Hat: Fine, here's a bottle. Black Hat: Do you sell a shock collar that can fit around a Roomba? White Hat: I'm going to have to ask you to leave.

Color Models

Color Models

https://www.xkcd.com/1882

https://www.explainxkcd.com/wiki/index.php/1882:_Color_Models

[A simple flowchart is shown. The text above the panel reads:] Evolution of my understanding of color over time: [On the left side is a vertical dashed line in gray, on top it's labeled:] Grade school [And at the bottom the label reads:] Now [Header above the chart:] "Color" is... [The chart starts with three items, one left and an other on the right, a third is below in the middle.] ...three primary colors mixed together ...a rainbow, and each color is a wavelength ...unknowable ("maybe what I see as blue, you see as...") [Arrows from the left and the middle item point to a new left one, while two other arrows from the middle and the right item lead to one at the right.] ...three-ish primary colors mixed together (RGB/RYB/CMYK) ...a mix of infinite wavelengths filtered through three eye pigments [The arrows of both items point to one in the middle:] (something about the opponent color model) [The remaining items are all in the middle and each is connected by one arrow downwards to the next.] ...an abstract multidimensional gamut (CIE 1931, L*a*b*, etc) ...an abstract multidimensional gamut filtered through inconsistently-implemented device color profiles ...a hyperdimensional four-sided quantum Klein manifold? Is that a thing? ...hopefully somebody else's problem.

Randall is describing how his level of understanding of colors has changed by age. The chart starts with two tracks of understanding color. In grade school he learned about the primary colors, and the very simple model of colors, as shown in the left track. Mixing of color solids, as in painting (or finger painting being probably the earliest exposure to color mixing), is intuitive for a child. The process is subtractive, and the more colors you mix the darker and closer to black you get. Color is seen by the eyes when light bounces off the solid colors and becomes light of different wavelengths that the eye can then see. However at this level, things just "look" like different colors without understanding light's role. The color models mentioned in the second point of the left track are the additive model RGB (red-green-blue) and the subtractive models RYB (red-yellow-blue) and CMYK (cyan-magenta-yellow-key, used in color printing). The right track is about mixing of colored light, as in prisms and light waves, where mixing colors is additive and the more you mix the lighter and closer to white you get. But this is without a real understanding of light bouncing off surfaces, and is limited to an understanding of different colors of light and how they mix. The first exposure in grade school is usually by shining white light through a prism to separate it into the different visible colors. Meanwhile, philosophically, color is unknowable because it's impossible to say if everyone has the same qualia for colors. E.g. "Maybe what I see as blue, you see as my idea of purple, but we both call it blue because we've been brought up to know to call that color blue?." The opponent color model connects these two models, by considering how the signals from rods and cones are processed, after different wavelengths of light are absorbed by different rods and cones in the eyes. The "complex multidimensional gamut" mentions two more models: CIE 1931 and L*a*b* . These are more detailed models based on the opponent color model, which precisely define how a particular color maps to the different channels that our eyes see. However, understanding how the eye sees color still isn't enough, because not every device can display all the colors your eye can see. Your laptop might have a different gamut from that of your phone, and when you print the page, you might see yet another color. To handle this issue, web browsers use "color profiles", so that an image can be tagged with the color space it uses and the browser can handle it appropriately. Unfortunately, browsers do this inconsistently and not very well. Further complicating the matter, ostensibly identical device may show colors differently (depending on how they are adjusted, variations between devices, aging of the device, and the viewing environment). Devices and software exist to attempt to match systems to reproduce colors consistently, however most systems are not set up this way, color correction can be complicated, and the corrections have to be frequently readjusted. The "hyperdimensional four-sided quantum Klein manifold" is a joke, and could also be a pun upon the color Klein Blue . A Klein manifold is described by the Klein bottle , where the bottle was originally a surface (a mix-up of the German words Fläche for surface and Flasche for bottle). It is a two-dimensional manifold, or simply just a surface with some special characteristics. Randall is here projecting an "abstract multidimensional gamut" onto an even more complicated surface, presumably in order to eliminate the errors in color rendering caused by previous attempts to eliminate the errors in color rendering. The Klein bottle has to be projected into 4 dimensional (4-D) space for this to work, as it would otherwise intersect with itself. The “quantum” may be a reference to the "color" charge in Quantum chromodynamics . Eventually it appears Randall has given up, realizing color is very difficult and hoping somebody else will deal with the difficulty in describing, understanding and using the concept of colors. The title text expands on this joke, implying that the reason for the "unknowable" answer in the comic is that everyone's browser shows colors slightly differently. Despite the complexity and thoroughness of color models, this common software can't get it right. [A simple flowchart is shown. The text above the panel reads:] Evolution of my understanding of color over time: [On the left side is a vertical dashed line in gray, on top it's labeled:] Grade school [And at the bottom the label reads:] Now [Header above the chart:] "Color" is... [The chart starts with three items, one left and an other on the right, a third is below in the middle.] ...three primary colors mixed together ...a rainbow, and each color is a wavelength ...unknowable ("maybe what I see as blue, you see as...") [Arrows from the left and the middle item point to a new left one, while two other arrows from the middle and the right item lead to one at the right.] ...three-ish primary colors mixed together (RGB/RYB/CMYK) ...a mix of infinite wavelengths filtered through three eye pigments [The arrows of both items point to one in the middle:] (something about the opponent color model) [The remaining items are all in the middle and each is connected by one arrow downwards to the next.] ...an abstract multidimensional gamut (CIE 1931, L*a*b*, etc) ...an abstract multidimensional gamut filtered through inconsistently-implemented device color profiles ...a hyperdimensional four-sided quantum Klein manifold? Is that a thing? ...hopefully somebody else's problem.

Supervillain Plan

Supervillain Plan

https://www.xkcd.com/1883

https://www.explainxkcd.com/wiki/index.php/1883:_Supervillain_Plan

[On the left of this single panel comic Black Hat sits on a high throne, showing a fist, and looking down to Cueball and Magan who stand in front of him on the right.] Black Hat: ... then, after our drones take control of the cities, we will detonate the devices. California will break off from the mainland and drift out to sea! Megan: How far out to sea? Will it put any of the cities in the UTC-9 time zone? Black Hat: What? I don't know. Megan: One request: Can we make sure this doesn't happen during the daylight saving changeover? [Caption below the panel:] You can tell when someone's been a programmer for a while because they develop a deep-seated fear of time zone problems.

In this comic Black Hat is a supervillain , befitting his character . He plans to use drones and explosives to move the entire State of California into the Pacific, a la Lex Luthor in the 1978 Superman movie. His henchmen are Cueball and Megan . The latter appears to be a programmer who is concerned that the mission (and hence the drones' coding) may have to account for time/date adjustments, such as time zones and daylight saving time (DST), which would be a factor if the event took place on the wrong date or the landmasses were pushed too far apart. (Though by coding the drones on UTC, the drones would not need to change time zones, except for displaying the local time for some reason, which would likely be unneeded.) In computer programming, working with dates and times can be complicated. Think about leap years or leap seconds , the non existing year zero which even worse for scientists does exist in astronomical calendars , or the Y2K and year 2038 problem. Nevertheless in this comic there is only a time zone problem mentioned. To handle this the tz database , also known as tzdata , provides all relevant information for every country back to 1970 and, less accurate, before. But it's still up to the programmer to use this data in useful ways. Supervillains have reason to fear daylight saving time issues. In 1999, two coordinated car bombings ended up killing the terrorists transporting the bombs when they exploded one hour early. Details explained e.g. on the Darwin Awards site. Time zones and DST can give seemingly nonsensical results when used improperly. For example, a flight going west might leave at 02:00pm and reach its destination at 03:00pm while the reverse flight will leave at 02:00pm and arrive at 05:00pm. In both cases, the travel time is two hours, but the one hour difference between the two time zones makes it seem otherwise. You might even find yourself arriving at your destination at an earlier time than your departure! DST can also makes a given time mean two different things, if after 01:59am you go back to 01:00 am, 01:30am can either be one hour after 00:30am, or one hour before 02:30am. Or in the reverse change, some dates don't actually exist, like 02:30 when going straight from 01:59 to 03:00. Humans often avoid this issue by being in only one place at the same time [ citation needed ] , or by sleeping when the DST changes happen, but computer communications often span over large distances, and drones don't need to sleep at night. Megan wants to make sure she won't have to deal with the difficult problem of communication between drones and other systems with those issues, where a single poorly communicated date can have disastrous effects (although possibly far less disastrous than moving California into the sea [ citation needed ] ). California is currently located entirely within the UTC-8 time zone (at standard time PST , while in summer PDT is at UTC-7 ). But after Black Hat's actions California is at risk of floating West into the next time zone at UTC-9 . However, in reality, time zones in the United States are determined by Department of Transportation regulations , and California's time zone is not defined based on its longitude. Consequently, even if California were pushed out to sea, its time zone would remain the same unless the Department of Transportation issued a regulation otherwise, so Megan can rest easy. (On the other hand, Black Hat could alter the time zone of any of the East Coast states except Maine if his drones could push the state east of 67°30' W. longitude, since the Eastern Time Zone's eastern boundary is mostly based on longitude, except for Maine.) Note: Megan should be happy Black Hat hasn't planned to involve Arizona in his scheme . A "tick tock article" is a term in journalism for a step by step account of an event or timeline, such as this one recounting the end of the 2011 MLB regular season . Such an article published for an event during the change to or from Daylight Saving Time would need to account for the changeover, making the timeline confusing for those unaware of the switch. [On the left of this single panel comic Black Hat sits on a high throne, showing a fist, and looking down to Cueball and Magan who stand in front of him on the right.] Black Hat: ... then, after our drones take control of the cities, we will detonate the devices. California will break off from the mainland and drift out to sea! Megan: How far out to sea? Will it put any of the cities in the UTC-9 time zone? Black Hat: What? I don't know. Megan: One request: Can we make sure this doesn't happen during the daylight saving changeover? [Caption below the panel:] You can tell when someone's been a programmer for a while because they develop a deep-seated fear of time zone problems.

Ringer Volume/Media Volume

Ringer Volume/Media Volume

https://www.xkcd.com/1884

https://www.explainxkcd.com/wiki/index.php/1884:_Ringer_Volume/Media_Volume

[A x-y-graph is shown and the header above is:] Trying to turn down the volume before a video starts playing: [At the line graph the horizontal axis is labeled with the text "Time" and an arrow pointing to the right. The vertical axis represents the volume but has no label. There are two signed lines, "Ringer volume" in black and "Media volume" in gray roughly at the same level. Below are eight smartphone screens showing the running app over time.] [The first seven screens showing a circle indicating that an app is loading. At the second screen a volume control is depicted with an arrow to the lower button.] TAP TAP TAP TAP [The "Ringer volume" decreases four times.] [Further in time before the third screen the volume control is depicted again with an arrow to the upper button.] TAP TAP TAP TAP [The "Ringer volume" increases to normal.] [Nothing happens on the 4th screen but at the 5th the volume control is shown again with an arrow to the lower button.] TAP TAP TAP [The "Ringer volume" decreases three times.] [Before the 6th screen the volume control is shown, again with an arrow to the upper button.] TAP TAP TAP [The "Ringer volume" increases back to normal.] [At the 7th screen there is again the volume control with an arrow to the lower button.] TAP TAP TAP TAP [The "Ringer volume" decreases four times.] [Before the 8th screen the volume control is shown with an arrow to the upper button and the tapping starts:] TAP TAP [The "Ringer volume" increases two times, still below normal, and the video starts at the screen.] TAP TAP [The "Media volume" increases two times above normal.] Person in the video: HELLO, AND WELCOME TO...

Most smartphones , when this comic was published, have multiple system-level sound volume settings, such as, phone call ringer volume, timed alarm volume, phone communication volume, and media volume (which covers video, music, games and such). For comparison, personal computers tend to expose the user to a master sound volume control by default, which affects all the sounds emitted by system. Applications that emit sound (other than basic interface sounds, such as clicking) tend to implement a separate volume control. Further, smartphones often have a pair of hardware buttons for raising or lowering sound volume. However, they don't differentiate which of the available volume controls the user wants to adjust. Smartphone operating systems tend to adjust the volume level of the currently emitted sound type, with some defaulting to the phone call ringer in the case no sound is playing. Adjusting arbitrary volume control is usually possible using a system settings app controlled by touch screen, which can take more time than pressing dedicated buttons, and/or stopping the program currently being used, depending on the smartphone in question. The comic demonstrates, using a time axis, a typical annoyance generated by this kind of setup. A implied user wants to play a video clip but expects its sound volume to be too loud, so the user starts to preemptively press the volume down button. However, since the video clip just started loading while the user preemptively pressed the button, this adjusts the phone ringer volume instead of media volume. The user proceeds to raise the ringer volume and waits until the information box about ringer volume being adjusted disappears from screen, then tries again. Since the video is still loading this still doesn't work. Apparently the application needs to start emitting sound before the possibility of adjusting that sound with volume buttons arises. This is exactly what eventually happens - the video starts uncomfortably loud and the user's delayed reaction while attempting to readjust ringer volume level leads, in fact, to raising the media volume. At this point the graph ends, though the user is implied in the title text to proceed to reduce the video's volume directly afterwards. Despite most applications implementing separate sound controls, Windows has also offered the option to adjust volume on per-activity basis since at least Windows 95. You can access this feature on Windows 10 by right-clicking the speaker icon on the tray, and selecting the "Open Volume Mixer" option. This setup is roughly equivalent to opening system settings on a smartphone, in that user can see multiple volume controls and select to adjust some. Additionally, some versions of Windows made the system tray volume control only affect the currently focused program, sort of analogously to described smartphone behavior, in that a single interface area can correspond to different volume controls depending on the context. However, this feature has been removed in more recent versions, presumably to reduce user confusion. The title text presents a method of exploiting the phenomenon presented in the main comic by putting important parts of an advertisement very early in the video clip in loud audio form. Since user may have problems with adjusting video sound volume before it starts playing, this will result in the important part of ad (here, product name) emitted very loudly, to the levels of narrator of title text expecting it to reach people in other rooms than one the smartphone is in. [A x-y-graph is shown and the header above is:] Trying to turn down the volume before a video starts playing: [At the line graph the horizontal axis is labeled with the text "Time" and an arrow pointing to the right. The vertical axis represents the volume but has no label. There are two signed lines, "Ringer volume" in black and "Media volume" in gray roughly at the same level. Below are eight smartphone screens showing the running app over time.] [The first seven screens showing a circle indicating that an app is loading. At the second screen a volume control is depicted with an arrow to the lower button.] TAP TAP TAP TAP [The "Ringer volume" decreases four times.] [Further in time before the third screen the volume control is depicted again with an arrow to the upper button.] TAP TAP TAP TAP [The "Ringer volume" increases to normal.] [Nothing happens on the 4th screen but at the 5th the volume control is shown again with an arrow to the lower button.] TAP TAP TAP [The "Ringer volume" decreases three times.] [Before the 6th screen the volume control is shown, again with an arrow to the upper button.] TAP TAP TAP [The "Ringer volume" increases back to normal.] [At the 7th screen there is again the volume control with an arrow to the lower button.] TAP TAP TAP TAP [The "Ringer volume" decreases four times.] [Before the 8th screen the volume control is shown with an arrow to the upper button and the tapping starts:] TAP TAP [The "Ringer volume" increases two times, still below normal, and the video starts at the screen.] TAP TAP [The "Media volume" increases two times above normal.] Person in the video: HELLO, AND WELCOME TO...

Ensemble Model

Ensemble Model

https://www.xkcd.com/1885

https://www.explainxkcd.com/wiki/index.php/1885:_Ensemble_Model

[Inside this single panel comic the header on top reads:] In an ensemble model , forecasters run many different versions of a weather model with slightly different initial conditions. This helps account for uncertainty and shows forecasters a spread of possible outcomes. [To the left side a picture shows several gray overlapping swirling lines emitted from a point, then gradually diverging rightwards. Below are two smaller pictures; the first shows the lines connected to several loops and in the second it's still a similar figure to the above but moving into the opposite direction with the point emerged to a spiral.] [The text right to the pictures reads:] Members in a typical ensemble: A universe where… …rain is 0.5% more likely in some areas …wind speeds are slightly lower …pressure levels are randomly tweaked …dogs run slightly faster …there's one extra cloud in the Bahamas …Germany won WWII …snakes are wide instead of long …Will Smith took the lead in The Matrix instead of Wild Wild West …swimming pools are carbonated …sliced bread, after being banned in January 1943, was never re-legalized. 2149: Alternate Histories also deals with the alternative history setting of Germany winning WW2 and subsequently more weird alternate history settings.

An ensemble model is a combination of multiple, similar models to show a wider range of possible outcomes. The graphs on the left are tracks of predictions from multiple models. In this comic, Randall starts out describing actual changes that ensemble models show, but sinks into absurdity, describing strange alternate universes and scenarios that likely would not be necessary in an actual model. The upper graph shows a typical plot of predicted wind speeds over time from various ensemble members. The graph shows that it is predicted that the storm will strengthen, with varying degrees of weakening depending on the ensemble member. The graph at the left bottom is a typical map of isobars (lines of equal pressure ) for various ensemble members with the ensemble members showing slightly different configurations. The bottom right graph is a typical hurricane path-prediction graphic, starting in the Atlantic moving westwards and then turning to north, often with the Caribbean Islands or the US coast in the path. Some hurricanes don't reach mainlands and after turning north they head eastwards and can reach Europe still as strong storm. The term universe is in mathematics a class that contains all the entities of an ensemble in a given situation. Don't be confused with the more common usage of the words universe , the entire space where we live, and multiverse , a hypothetical set of possible universes. The first three outcomes are real while the others are less serious. They are explained below: …rain is 0.5% more likely in some areas …wind speeds are slightly lower …pressure levels are randomly tweaked These realistic outcomes are only possible under calm weather conditions. Predicting these values with an accuracy better than 1% indicates that the model is stable even when the initial conditions are slightly changed. Modern weather forecasts at normal circumstances are often not good as this and for a hurricane or tornado the variances are much higher. …dogs run slightly faster This is where the comic diverges from reality; there is no reason to have the locomotion speed of dogs as a parameter in a usual weather model [ citation needed ] . The speed of dogs might be a parameter in a wildlife model, where the speed of a predator might affect the predator/prey ratios. In terms of weather models, dogs traditionally chase cats, so running faster might affect the number of cats. Cats prey on birds, which in turn eat insects. So faster dogs might increase the number of birds, reducing the number of butterflies. Butterflies in turn affect the weather through the butterfly effect (that is that the movement of a butterflies wings may change the development of tornados, or other weather, in difficult to predict ways, as for instance with the quantum weather butterfly ). …there is one extra cloud in the Bahamas This situation is most likely too specific and subtle a difference to be useful to the model. …Germany won WWII "What if Germany won World War II" is a very popular subject for alternate history stories. …snakes are wide instead of long Snakes being wider than they are long (think "eyes and mouth in the middle of their body and a tail on both sides") in present reality would have enormous consequences for zoology and other fields of biology, including evolutionary biology. It would also have an impact on art history, especially where it involves paintings depicting certain scenes from the book of Genesis. Compared to these effects, the expected upshot for meteorology seems to be limited. …Will Smith took the lead in The Matrix instead of Wild Wild West Actor Will Smith famously [ citation needed ] turned down the lead role of Neo in The Matrix , instead taking the role of Captain James T. West in the widely-panned action-comedy Wild Wild West . The role of Neo ultimately went to Keanu Reeves . Besides the significance of the role and what many surmise might have happened if Smith had pulled off the role in the iconic and groundbreaking film trilogy, another possible reason behind calling out Will Smith in particular is that he has turned down other offered roles that would place him in an ensemble cast, rather than the lead. …swimming pools are carbonated A simple calculation reveals this as a serious greenhouse problem. In the United States alone there are no less than 5,000,000 private owned pools. Conservatively assumed, a volume of 25,000 liters per pool gives 125 billion liters of carbonated soda. According to Wikipedia the U.S. sales reached around 30 billion bottles of water in 2008 (including non-carbonated water) which is much less than all of the pool water. While all those bottles are not considered to have an impact on the greenhouse effect, this scenario gets even worse. Open a bottle of carbonated water and pour the content into a glass. Sooner or later the bubbles fade, meaning you have to open the next bottle and pour it in and so on. In a pool at the bottom the pressure is high enough to hold the carbon dioxide, but on the surface it behaves like the glass. So, while a glass needs new carbonated water every two hours, or ten times per day, it would be about three times per day for the pool, which leads to 1095 times per year. The total number in this scenario would be 125 trillion liters of carbonated soda, ejecting carbon dioxide, per year. Even taking into account the pressure at the bottom of the pool: Randall has shown in Soda Sequestration this effect would be minimal. …sliced bread, after being banned in January 1943, was never re-legalized. Sliced bread was in fact banned in the US for about two months in early 1943, as a supposed wartime conservation measure. The issue was not the bread itself, but that the pre-sliced loaves required a heavier wax paper wrapping to prevent them from drying out too quickly. The title text suggests that Randall has been pitching an absurd "alternate-universe crime drama" to Netflix , apparently based on the premise that a permanent sliced-bread ban would spawn a criminal underground (similar to those created by alcohol and drug prohibitions in actual history). The first half of the sentence is set up to imply that production had started on the series but a breakdown in communication has occurred between them, playing on the reader's expectations. The conclusion of the sentence nonetheless makes it clear that Netflix has zero interest in the pitch, and so Randall has become overzealous in pushing his idea, to the point that Netflix employees are changing their numbers (presumably they can't block his number because he has resorted to calling from many different phones). He has even taken to infiltrating Netflix's corporate headquarters using ill-gotten security codes, which is definitely illegal [ citation needed ] , much like Elaine 's "meetings" with Steve Jobs in 1337: Part 3 . However, it is clear that Netflix is uninterested and is attempting to prevent Randall from contacting them (or trespassing into the building). [Inside this single panel comic the header on top reads:] In an ensemble model , forecasters run many different versions of a weather model with slightly different initial conditions. This helps account for uncertainty and shows forecasters a spread of possible outcomes. [To the left side a picture shows several gray overlapping swirling lines emitted from a point, then gradually diverging rightwards. Below are two smaller pictures; the first shows the lines connected to several loops and in the second it's still a similar figure to the above but moving into the opposite direction with the point emerged to a spiral.] [The text right to the pictures reads:] Members in a typical ensemble: A universe where… …rain is 0.5% more likely in some areas …wind speeds are slightly lower …pressure levels are randomly tweaked …dogs run slightly faster …there's one extra cloud in the Bahamas …Germany won WWII …snakes are wide instead of long …Will Smith took the lead in The Matrix instead of Wild Wild West …swimming pools are carbonated …sliced bread, after being banned in January 1943, was never re-legalized. 2149: Alternate Histories also deals with the alternative history setting of Germany winning WW2 and subsequently more weird alternate history settings.

Typing Notifications

Typing Notifications

https://www.xkcd.com/1886

https://www.explainxkcd.com/wiki/index.php/1886:_Typing_Notifications

[A sequence of eight panels representing the same conversation in an electronic chat. The header always reads:] What did you think of my show? Did you like it? Be honest! [The reply area on the first seven panels is empty, but on the 2nd, 3rd, 5th, and 7th the input is activated and showing three dots.] [On the last panel the reply area reads:] It was great! [Caption below the panels:] My least favorite aspect of typing notifications

Randall has sent an instant message to someone and is now watching the screen expecting a reply. The message contains simple questions about a show Randall had undertaken and he insists on an honest answer. The phone indicates that the respondent is typing a response, but then pauses, resumes typing, and pauses a second time, before sending a simple "It was great!" Typing notifications, often called "typing awareness indicator", is a feature of some instant messaging systems. It lets you know when the other person in a conversation is typing and preparing a reply. It may appear in different forms, like the literal text "[Contact] is typing." or often has a empty answer (possibly a different color) containing three animated dots. It gives the sender confidence that their message has been received and the other one is working on a reply. When the final response is received it is anodyne "It was great", suggesting that the first two deleted drafts could be far more critical. The fact that you know that a message has been deleted or edited twice provokes you to imagine what the deleted drafts may have contained. The issue with typing notifications that Randall is talking about might also just be the difficulty to interpret them. The distant contact might just have been doing something else at the same time, had a bad, unsteady internet connection, started typing in the wrong conversation, or corrected a typo, but because Randall has interpreted the long pauses the same way one would read face-to-face interactions, the typing notifications make it seem like they weren't honest. If one partner of a conversation takes their sweet time to reply, possibly deleting their text and starting from scratch as shown in this comic, the typing notification feature can lead to anxiety, as the person waiting for a response starts to overthink the issue. Thoughts come to mind like the other person might not be honest, try to carefully word a sensitive subject or not care enough about you to quickly reply. If finally the answer arrives and consists of just a laconic "ok" or similar, these feelings become even stronger, leading to thoughts like the other person is trying to hide something. This phenomenon has become so widespread that many people have written about it in newspapers and blogs, calling it texting anxiety . The caption below the screens summarizes that what Randall dislikes the most about these systems of notification that the other party on the conversation is actively working on a reply is the lengthly alternation between indications that the other party is composing a reply, amidst pauses wherein one presumes the other party is thinking carefully about what they are wanting to say, then more typing as in response to their deep thinking, etc. until at the end of this extended period when one expects the other side to have written a book's worth of notes given the time and work they appear to have dedicated to the reply -- and all they get is a simple 3-word reply. It leaves him wondering what all the other party really typed, and really thought, that they ended up not sending. This type of notification was mentioned as rule no. 1 in the much later 2235: Group Chat Rules . One way around giving your text receiver texting anxiety would be to open a blank note and work out what you want to say there. Since you're not typing in the messaging app, there's no typing notification. In the title text, Randall expresses that he likes to watch when the recipient reacts and is trying to write an answer but he's also happy to not receive notifications that the texter is composing a response in a blank note file. Typically, one composes responses in blank notes when they need to be careful or thoughtful about how they respond (as well as avoid alerting the recipient, via the notifications, that they've received their text and are preparing a response). If Randall were to be notified about such actions, it would confirm his above fears that the writer was being tactful and guarded in their response, which would just lead to more anxiety about what they were trying to hide. Also, it would expose him if he wanted to compose his own message privately. [A sequence of eight panels representing the same conversation in an electronic chat. The header always reads:] What did you think of my show? Did you like it? Be honest! [The reply area on the first seven panels is empty, but on the 2nd, 3rd, 5th, and 7th the input is activated and showing three dots.] [On the last panel the reply area reads:] It was great! [Caption below the panels:] My least favorite aspect of typing notifications

Two Down, One to Go

Two Down, One to Go

https://www.xkcd.com/1887

https://www.explainxkcd.com/wiki/index.php/1887:_Two_Down,_One_to_Go

[There are three rows equally filled with squares and above are year dates beginning from 2002 until 2017. The first year (2002) is cut on the left and the color is light gray. It fades in to black, which it becomes in in 2005. To the left of the three rows the text reads:] Total eclipse Aurora Meteor storm [Below the year 2017 the squares in the first two rows are checked.]

In this comic, Randall lists three of the most spectacular astronomical sights: a total solar eclipse , an aurora (Aurora Borealis in the northern hemisphere and Aurora Australis in the south), and a meteor storm . In 2017, the first two of these phenomena happened within weeks of each other for observers in much of the US - a coincidence that Randall celebrates. In the title text, Randall suggests the next meteor storm could be 2034, probably because this is predicted to be a good year for Leonids . Randall then continues by saying that if he manages to see a supernova during the daytime, he will drop the goal for the meteor storm and call it 3 of 3. This is because such an event is so unlikely that he hasn't even included it in his bucket list, and he would be happy to switch between the two types of events if he had the chance. A few stars, when they turn supernova, could be so bright that they can be seen during the day time here on Earth. The brightest supernova recorded in human history was SN 1006 which was sixteen times brighter than Venus but still not bright as the full moon. SN 1054 is an other example. When such an extremely rare event might happen is impossible to predict. There is a (very small) chance that the giant star Betelgeuse will go supernova within Randall's lifetime, allowing him to tick this off the list too. Randall even mentioned that this could not happen soon enough in 1644: Stargazing . Note that if you could see it during the day time, it would be one of the brightest objects in the night sky after the Moon. Also keep in mind that if Betelgeuse were to go supernova in Randall's lifetime, he wouldn't see it since it's over 600 light years away. For Randall to see it during his lifetime, it must have already gone supernova some 600 odd years ago, and we won't know that until we actually see it 613-881 years after it happened. Astronomical backgrounds [There are three rows equally filled with squares and above are year dates beginning from 2002 until 2017. The first year (2002) is cut on the left and the color is light gray. It fades in to black, which it becomes in in 2005. To the left of the three rows the text reads:] Total eclipse Aurora Meteor storm [Below the year 2017 the squares in the first two rows are checked.]

Still in Use

Still in Use

https://www.xkcd.com/1888

https://www.explainxkcd.com/wiki/index.php/1888:_Still_in_Use

[Cueball is trying to take out a trash bag from his garbage can.] Trash: Sorry, you can't empty the garbage yet. A paper towel in here is currently in use by some object in your house.

Cueball is trying to remove the trash bag from his garbage can. However, the can refuses to let him do so, citing that a paper towel in the trash is being used by some object in his home. This comic draws parallels between the act of emptying a physical rubbish bin and emptying the recycle bin integrated into a desktop computing environment like Windows, macOS, most Linux derivatives, and others. It originated with the Xerox Alto , but was first commercially introduced on Apple Lisa in 1982 called Wastebasket and, while it was adopted by most other desktop environment operating system, using slightly different names, the main purpose still remains: A user can restore a file after they have deleted it -- hence the most common name recycle bin , you still can get your paper towel and use it again. In many (earlier) command line based systems like DOS or UNIX/Linux (besides the desktop interfaces) a removed file was gone. Some undelete commands exist, but there are hard restrictions because the then free space on the hard drive must not have been used again and often file names aren't fully recoverable. But sometimes when attempting to delete files, a running program may still have the file marked as in use. The operating system will therefore prevent the file's deletion, but some do not tell the user which program is using the file. Preventing the file from being deleted from the file system in this case may be a correct behavior, because the document is still being worked on. But sometimes it may happen erroneously, perhaps because of a program not closing the file properly, a glitch in the operating system, or user error. The user then is required to find the cause of the problem and rectify it before the file can be deleted. This may be difficult because error messages may not reveal the affected file or the program blocking its removal. Similar problems may occur when unmounting (or "safely removing") a removable storage device. The title text may refer to a simple solution to these sorts of problems: Wait a while, perhaps overnight, and see if the (unknown) application(s) have closed the open file(s). Alternatively, the user can shut down the system to make absolutely sure that nothing is using anything. This is usually effective and harmless -- programs that falsely flagged something in the recycle bin as "in use" usually won't recreate the problem when the computer finishes booting up -- but this is really not a convenient solution for the user because all applications are closed. Advanced users may be inconvenienced by unhelpful error messages but at least are likely to know the tools available to solve the problem. However, a less experienced user just trying to free some space is not only annoyed, their only solution is to reboot or shut down the computer. Some tools: [Cueball is trying to take out a trash bag from his garbage can.] Trash: Sorry, you can't empty the garbage yet. A paper towel in here is currently in use by some object in your house.

xkcd Phone 6

xkcd Phone 6

https://www.xkcd.com/1889

https://www.explainxkcd.com/wiki/index.php/1889:_xkcd_Phone_6

[A smartphone is shown, the screen is slightly wider than the case, in the middle is a photo lens, and at the right bottom a small extra part is added to the screen.] [On top a bracket ranges nearly over the entire width of the case. The text reads:] Full-width rear camera [The label at the photo lens is:] Front camera (centered for eye contact during video chat) [The label on the extra part says:] Extra screen [At the bottom below the case a label reads:] Wireless charging port [The labels left to the phone are:] 4k pixels (50x80) Radium backlight Sterile packaging College-ruled Broad spectrum SPF 30 Pre-seasoned Burns clean coal Includes applicator Fonts developed by NASA Shroud of turn-style facial transfer unlock High thread count CPU Screen goes past the edge Safe for ages 6-8 months, 10 months, 18 months-3 years, and 12 years and older [The labels right to the phone are:] CDC partnership: Phone automatically administers seasonal flu vaccine to cheek every year 12-function Dishwasher safe GPS transmitter 3-G acceleration Portable, solar-heated Pore-cleaning strip Maximum strength Never needs sharpening Can survive up to 30 minutes out of water Exclusive Audubon Society app identifies birds and lets you control their flight [Text below the phone:] Introducing The xkcd Phone 6, VIII, 10, X, 26, and 1876 We didn't start this nonconsecutive version number war, but we will not lose it. ™®©°

This is the sixth entry in the ongoing xkcd Phone series , and once again, the comic plays with many standard tech buzzwords, and horribly misuses all of them, to create a phone that sounds impressive but self-evidently isn't to even the most ignorant customer. The previous comic in the series 1809: xkcd Phone 5 was released 7 months before this one and the next 2000: xkcd Phone 2000 was released 8 and a half months later. This comic was released the day after Apple announced their new iPhone 8 and the higher-end iPhone X (pronounced iPhone 10) with facial recognition features. Front camera (centered for eye contact during video chat) A front camera has become a common feature of smartphones. The camera lens is located on the same side of the phone's case as the main screen, making it possible to capture the image of the user's face looking at the screen and display the interlocutor's face on the screen simultaneously, enabling video chat. However, as the camera is usually located above the screen, when the user looks at the displayed image of the other person they direct their eyes at the center of the screen and not at the camera's lens. This makes it appear on the other end of the chat as if the person talking was looking down and not making eye-contact, which can be an uncomfortable situation for many people. For this reason, professionals involved in movie or TV-making, like actors or reporters, are trained to look straight into the camera's lens while talking, which creates impression of looking straight at the viewer's face. During a video chat, however, looking into the lens of an above-screen camera does not allow one to see the interlocutor's face clearly because it is then in the peripheral field of vision. To solve this conundrum, Randall proposes locating the camera lens right in the middle of the screen. The user looking at the the other person's face on the screen would then also be looking at the lens, creating an impression on the other end of the chat that they are looking straight at the other person. This is absurd, since the lens would then take place of some of the center pixels of the screen, which would probably mean that it could not display the center part of the captured image of the other person's face. This could include features such as eyes and/or lips, which play an important part in non-verbal communication. Locating the camera lens in this way would probably also interfere with the touch-screen function. It would probably make other applications on the phone difficult to use, since virtually no user interface is designed to accommodate a blind spot in the center. The idea of having the camera in the middle of the screen is only currently absurd, however, as advances in technology may eventually enable such a feature to work without disturbing the appearance or function of the phone's display, unlike the visual disturbance clearly indicated in the comic. For instance, previous technological advancements have improved the functionality of the display, starting with adding touch sensing. The touch sensitive hardware of the phone is located in a thin layer above the hardware, that generates the image for the display, and capacitive touch sensing technology is less obtrusive than previous resistive sensing. While it has yet to be released to market, certain manufacturers are aiming to place a phone's fingerprint reader underneath the screen, for seamless functionality. Although it may be difficult at this point, figuring out a way to have a camera capture images through the array of pixels on the screen is not completely beyond imagination. Full-width rear camera Historically, there has been an 'arms race' among phone manufacturers to increase the 'size' of the rear camera, in terms of the number of pixels they can capture. This is not typically accompanied by equivalent increases in physical size, though. Phone cameras tend to have lenses which are quite small, and round or square -- measuring the same in width as in height. On this phone, the 'full-width' lens appears to be a long, thin strip, like an oval or rectangle shape. This could allow the camera to gather a lot more light, potentially working in low light situations. However the lens would be more vulnerable to damage and dirt. Unless a very large sensor was used, focusing the image could be a problem, since cell phones are typically not very deep. CDC partnership - phone automatically administers seasonal flu vaccine to cheek every year U.S. Centers for Disease Control and Prevention is a government agency tasked with addressing public health concerns, such as infectious diseases, including seasonal flu. A common way of limiting the spread of an infectious disease is vaccination , which most often involves administering a specially prepared vaccine via an intramuscular injection , though researchers have investigated other delivery systems, including aerosol, or microneedle injection. Uptake of vaccination is often poor, and many governments routinely use various different campaigns and techniques to try to encourage more people to get themselves vaccinated. This feature implies that the phone would automatically perform some form of injection once a year, administering a vaccine via a small aperture while the user is holding the phone to their cheek during a call. However, the placement of this component is dubious, as it would line up with the user's ear, rather than their cheek, during a phone call. It may be designed to detect the fraction of a second during which your cheek would be in the appropriate position (perhaps after a phone call, as you may be dropping the phone from your ear), and administer it at that moment; this would conveniently prevent disturbances to a majority of conversations. A further absurdity to this feature is that the vaccine is different every year, in order to account for various mutations causing different, and typically new, strains of the virus, which is the reason it has to be administered yearly. The CDC bases the combination of strains on a best-guess of what will be the most significant strains in circulation over the upcoming year, so in order to have the current year's vaccine, the user would have to physically load the new version into the phone for later administration, or there would have to be a mechanism to synthesize the concoction on-board the phone, and an associated logistics framework and digital standards for OTA delivery of specifications for the year's vaccine. 12-function Most smartphones can be used for more than twelve different things [ citation needed ] . However, this may refer to the twelve basic functions of algebra (identity, squaring, cubing, square root, logarithm, exponential, reciprocal, sine, cosine, greatest integer, absolute value, and logistic), or the twelve function keys on a modern keyboard (more than the ten on the original IBM PC keyboard). Alternatively, it may be a reference to calculators: basic models are sometimes referred to as four function calculators (addition, subtraction, multiplication and division), and complex scientific calculators may advertise 250 or more functions. Dishwasher safe Waterproofing has become a much-pushed feature of many recent smartphones, with manufacturers competing on the claimed resilience of their models. A phone that was truly dishwasher safe would be ahead in this race, as it would have to be able to withstand high-pressure jets of water, high temperatures, and caustic effects of detergent over significant periods. This is often listed as a selling point of items used for preparing, serving, or storing food, such as plastic containers or crockery, which a normal person might want to clean using a dishwasher, but it seems excessive for phones, which are rarely cleaned with anything more than a quick wipe, and most people would not intentionally attempt to clean in a dishwasher. GPS transmitter Many smartphones have a receiver for the Global Positioning System , which allows a phone to compute its position based on signals from the constellation(s) of GPS satellites. However, a device with a "GPS transmitter" would broadcast signals that would interfere with the GPS receivers of all devices nearby. This might be used in some form of differential GPS, broadcasting signals from a known location to allow more precise determination of other locations, or such a system might be used to confuse or control devices, such as drones, which navigate using GPS. 3-G acceleration This is a mixture of three unrelated concepts with similar names. In computer graphics, " 3-D acceleration " refers to GPU hardware that speeds up handling of three-dimensional data, such as shapes rotating in space. In physics, "3 Gs of acceleration" refers to speed increasing at a rate of 3 times the acceleration of Earth's gravity, or approximately 30 m/s². In cellular networks, 3G refers to a standard for data communication. GPUs, accelerometers, and compatibility with 3G networks are all normal features of modern smartphones. "3-G acceleration", however, is not a real term, and doesn't describe any meaningful feature of a phone. It appears to suggest that either the phone is capable of self-propelling with 3 Gs of acceleration, which doesn't seem particularly useful, or, perhaps more feasibly, that it has some way of increasing the data transfer rate over a 3G connection. Portable, solar-heated Portability is pretty much the entire point of using a mobile phone, so advertising portability is rather redundant. Solar power charging could be a very useful feature on a phone, but solar heating usually applies to plumbing, where a water tank is heated by the sun and used to supply hot water to taps. Technically, as the sun heats up everything it shines on, the phone is in fact solar heated. However, since avoiding overheating is a particular challenge in smartphone design, deliberately capturing solar energy simply in order to heat the device would seem rather counter-productive. Pore-cleaning strip Pore-cleaning strips are sticky strips designed to be applied to the skin and then pulled away to remove dirt and oils from the pores, with the intention of reducing spots and improving the complexion. The location shown for this feature would be inconvenient and irritating, as it would come into contact with the face every time the phone was held to the ear to make a call; something sticky on that location would be very annoying for clean-shaven people and extremely painful for anyone with facial hair. It would probably also result in that strip of the screen becoming obscured by an accumulation of facial gunk. Pore strips have been mentioned before in 777: Pore Strips . This may act as a sensor for the Shroud of Turin-style facial transfer unlock , whereby the phone would collect the dirt, oils, and microflora from the user's face when it is pressed against the phone, and use it to verify their identity. Maximum strength Medicines are often sold as "Maximum strength", usually indicating that they contain the highest dose of active ingredients allowed by law, or allowed without a prescription. For phones, there are sometimes "hardened" or "ruggedized" versions, which are designed to survive harsher environmental conditions, such as surviving drops and collisions, excessive water, dust, etc. Maximum strength here could indicate such a "ruggedized" phone, though this would be hard to achieve with a screen that extended past the edges. Never needs sharpening Phones do not need to be sharpened in the first place [ citation needed ] . This is a feature more likely to be found in a knife advertisement -- the slogan is infamous for hawking knives that cannot easily be sharpened, like a serrated blade -- or a mechanical pencil. Since the screen goes past the edge, it might be sharp enough to cut through things, much like a knife, though the phone would be unsafe to carry and handle if that were the case [ citation needed ] . Might also refer to sharpening the camera, which usually means adjusting the lens till an object is in focus. Most phones have autofocus and rarely need to be manually sharpened. Can survive up to 30 minutes out of water This is a play on the common IP-rating of water resistance, which is typically rated for submersion to a rated depth for 30 minutes. A phone which could only be used or carried for 30 minutes before it needed to be immersed in water would be rather inconvenient, although the phone short circuiting would likely not be an issue, as the phone is "dishwasher safe." Alternatively, either this phone's target market could be whales, dolphins, or other marine life, such as octopodes, or the feature could be optional. While such a feature would prove to be extremely useful for aquatic customers, the "solar-heated" feature would undoubtedly be inhibited significantly as water depths increased. Exclusive Audubon Society app identifies birds and lets you control their flight The National Audubon Society is a non-profit organization dedicated to the conservation of nature, and mainly of birds, which also organizes open birdwatching events. There are apps that attempt to identify bird species, for example, from a photo or audio recording of a bird made by the smartphone itself, though the Audubon Society's own app does not offer anything this interactive. An app allowing you to control the bird's flight would be way cooler and might work using the built-in GPS transmitter, confusing their navigation systems. However birds do not use GPS to navigate [ citation needed ] , and it would fly in the face of the Audubon Society's core activity. This is a reference to drones (which could be thought of as artificial "birds") which are often controlled by a smartphone app. This may also be a reference to 1425: Tasks , in which an app that can recognize if a bird is on camera is proposed. Extra screen Some phones advertise an additional display or display mode, often giving access to basic information, such as battery level and notifications without needing to activate the main screen function. Typically, this would be a low-power mode of operation of the normal screen, or else a form of display on another surface of the phone, such as the side or rear. Here, it seems to be an oddly shaped rectangular extension on the bottom of the main screen. This may have been added to make up for the loss of screen estate due to the center camera. Wireless charging port A port for wireless charging is an oxymoron, since wireless charging has no wires and thus has no need for a port, unless it is required for fuel for a fuel cell (see clean coal, below). This may be a jab at Apple's removal of the headphone port from their previous phones. Safe for ages 6-8 months, 10 months, 18 months-3 years, and 12 years and older Usually an item is deemed safe for a particular age or older, or (in the case of toys) is recommended for a particular age range. This is unusual in that it's a hodge-podge of age ranges with no apparent reason why some ages are safe and others are not. It may be a parody of drug commercials that list several age ranges for which the drug had to be separately approved. Screen goes past the edge A parody of the trend of "edge to edge" displays in recent generations of smartphones, or phones whose screens curve partway around the edge of the phone. In this case the screen is wide enough that it could curve partway around the edge, except the spillover does not actually form to the curves, resulting in a screen that is wider than the body of the phone. If the spillover is rigid, this would make the phone rather uncomfortable to hold, and the spillover is at risk of chipping off. High thread count CPU A CPU thread is a task the CPU performs. Several threads may share memory, making them a process. Threads are meant to run in parallel and the operating system distributes the workload on the available hardware execution units. These execution units are sometimes called hardware threads, especially when there is more than one per processing unit (or core). For example, the Intel Core i7 7700 is considered a 4-core, 8-thread CPU. The vague "high thread count" statement could make sense in this context, however, it is most likely a joke about bedding, where it is an actual selling point; the thread count of a textile signifies the density of fibres in the material, and a high thread count is an indicator of a high quality fabric. Shroud of Turin-style facial transfer unlock The Shroud of Turin contains an image of the body and face of a man, originally believed to be Jesus Christ , before the Shroud was found to be 1200 years too young. Some theories suggest the image was created by interaction with or transfer from the body that was wrapped in the shroud. Presumably, to unlock this phone, the user would have to physically press their face against the phone, the way the Shroud-Man's image was allegedly transferred to the shroud. This is probably a reference to the iPhone X's FaceID unlock, which uses a photograph of your face, augmented with spatial information, to unlock itself, and which had attracted significant criticism immediately before this comic came out. Fonts developed by NASA This may be a reference to many advertisements that claim that their product uses technology developed by NASA in an attempt to make it seem more impressive. NASA technology does often tend to be quite strong and advanced, as they claim at their spin off website. Between 1975 and 1992 NASA used the "worm" logotype in its insignia; it was a special font that omitted the horizontal bar in the capitalized letter A. However, it would not be particularly impressive to use this, since fonts have very little to do with NASA's core operations [ citation needed ] , and it potentially implies that it would not support many other common, and perhaps more readable, fonts. This may also be riffing on the urban legend that NASA invested vast amounts of research in developing a pen that could write in space, rather than just using a pencil. Includes applicator This is found on the packaging for many products, such as tampons, cosmetics, and paints. An applicator for a phone would be absurd, since the phone cannot be applied, spread, inserted, or attached to something else. However, this may be referring back to the aforementioned yearly vaccine. Burns clean coal Clean coal is coal that is burned so that it does not give off as much soot, sulphur dioxide, nitrogen oxides, mercury, or other pollutants as "normal" coal, or methods of burning coal that give off relatively less pollutants. This may be advertised by energy companies trying to appear to be using clean energy, due to pollution concerns. Coal burning power plants are usually quite large, so a traditional coal fired thermal-electric plant in a cell phone would be absurd. fuel cells , which produce electricity by oxidizing some fuel, can be small enough to fit in a cell phone, but they do not typically burn coal. The cordless charging port might be a receptacle for refueling the phone, using liquid or a fuel cartridge. Pre-seasoned Pre-seasoned typically refers to cast iron cookware which is ready to use out of the box, as opposed to needing to season it with oil and heat. It can also refer to packaged meats which are ready to cook without needing to be seasoned with herbs and spices, or timber that has been dried and is ready for use. A more technical definition of 'seasoning' means operating devices, usually calibrated standards or battery cells, for a while in the factory, to make sure the device meets constant performance requirements without deviating or diminshing too much. In this sense it could apply to the battery of the phone. Broad-spectrum SPF 30 The xkcd phone somehow gives a sun protection factor (SPF) 30 level of protection from sunlight, meaning that it blocks all but 1/30 of skin-burning UVB radiation from sunlight, though it is not clear whether it is the user or the phone itself which is protected. Phones do not typically require protection from sunlight [ citation needed ] . On the other hand, if, when placed between the user and the sun, the phone allows >3% of the radiation through, this would be remarkably more translucent, and therefore less effective, than most phones (which allow much less than 1% of UVB, or any other visible or near-visible wavelength, through). It would also be an inefficient method of protection, since it would only be able to protect a relatively small patch of skin. College-ruled College-ruled is a style of notebook paper having narrower than normal lines, in order to fit more text per page. That the phone is college-ruled suggests that there are lines permanently displayed on the screen, which could obscure any images on the screen, and make any text that doesn't line up with the lines hard to read. Defective screens can show similar patterns; for example, the iPhone 6 "touch disease" causes regularly spaced vertical lines to appear on top of the screen. Here, it is possible that the manufacturer is trying to pass off screen defects as features. Sterile packaging Useful for medical supplies, less so in a phone. There are numerous studies and resulting 'news' articles looking at the number of bacteria, fecal samples, and so forth, that can be found on the typical phone, typically with a sensationalist take on how you will be 'shocked' to discover this. However, sterile packaging would do little to counter this, since most of this contamination is accumulated after the user removes the phone from the packaging and begins using it. Radium backlight The discovery of the radioactive element radium sparked a brief fad in which manufacturers of consumer products began coating them with a paint containing radium and a radioluminescent substance, such as zinc sulfide, which converted the radiation from the radium into visible light. In particular, some clock and watch makers painted the faces or hands of their timepieces, allowing the time to be read at night without an external power source for the light. However, it was eventually realized that regular exposure to radium could result in radiation poisoning, particularly for the workers assembling and painting the products. A radium-based backlight would therefore be both potentially dangerous (especially for an object carried on one's person much of the time) but also largely useless, as the radioluminescent light is rather dim compared to conventional phone back lights. 4K pixels (50×80) "4K" typically denotes a screen with a width of ~4000 pixels, such as 4K TVs, which have 3840×2160 pixels, or about 8.3 million pixels total. That would be an outstanding resolution for a cell phone. Here, however, the "fine print" in parentheses clarifies that 4000 is actually the total number of pixels, not the width, which would be remarkably low resolution for a smart phone. As a comparison, the old Commodore VIC-20, with a resolution of 176 × 184, would have over 8 times the pixels of this phone. It is more comparable to the screen resolution of the sturdy Nokia 3310, which boasted a total of 4032 pixels, positioned 84 × 48. In the caption below the phone Randall presents many different version numbers: The "nonconsecutive version number war" referenced below the version names refers to several recent phones, and possibly operating systems, released consecutively with nonconsecutive version numbers, including: Randall's ludicrous naming scheme aims to 'defeat' all of these by eclipsing them. By counting parallel version numbers xkcd defeated Apple 6:2. The symbols at the end are ™ for trademark, ® for registered trademark, and © for copyright. The degree symbol ° after the letter C could be a play with degree Celsius. The use of all four symbols after the phrase is ridiculous, as ™ and ® indicate trademarks with opposite registration statuses, slogans can't be copyrighted, and the degree symbol usually has no meaning when applied to text. In the title text Randall recognises privacy concerns about the facial recognition feature. A picture of a face will only be used for facial recognition, but never stored on the device nor transmitted to the internet. A small side effect may be that the famous selfie pictures aren't possible anymore, as well as video calls. Ironic, considering that the reason the camera is in the middle is to allow easier video calls. [A smartphone is shown, the screen is slightly wider than the case, in the middle is a photo lens, and at the right bottom a small extra part is added to the screen.] [On top a bracket ranges nearly over the entire width of the case. The text reads:] Full-width rear camera [The label at the photo lens is:] Front camera (centered for eye contact during video chat) [The label on the extra part says:] Extra screen [At the bottom below the case a label reads:] Wireless charging port [The labels left to the phone are:] 4k pixels (50x80) Radium backlight Sterile packaging College-ruled Broad spectrum SPF 30 Pre-seasoned Burns clean coal Includes applicator Fonts developed by NASA Shroud of turn-style facial transfer unlock High thread count CPU Screen goes past the edge Safe for ages 6-8 months, 10 months, 18 months-3 years, and 12 years and older [The labels right to the phone are:] CDC partnership: Phone automatically administers seasonal flu vaccine to cheek every year 12-function Dishwasher safe GPS transmitter 3-G acceleration Portable, solar-heated Pore-cleaning strip Maximum strength Never needs sharpening Can survive up to 30 minutes out of water Exclusive Audubon Society app identifies birds and lets you control their flight [Text below the phone:] Introducing The xkcd Phone 6, VIII, 10, X, 26, and 1876 We didn't start this nonconsecutive version number war, but we will not lose it. ™®©°

What to Bring

What to Bring

https://www.xkcd.com/1890

https://www.explainxkcd.com/wiki/index.php/1890:_What_to_Bring

[Text in the top-left corner of the comic:] "Should you bring _____ to ______?" [The comic is laid out like a grid, with implements down the left-hand side (A knife / A gun / Water / A lid) and the type of "fight" across the top (A knife fight / A gun fight / A wood fire / An oil fire). The grid illustrates the "match-ups", with a green square denoting a "correct" match-up and a red square denoting a Very Bad Idea.] [From the top left corner, going from left to right, top to bottom, with each first item being on its own line in the grid, the squares are as follows:] [Green square, two combatants face off against each other with knives, equally matched.] A knife to A knife fight [Red square, a person with a knife faces off against someone with a gun, and is clearly outmatched.] A knife to A gun fight [Red square, a person holds a knife in a wood fire while saying "OW OW OW".] A knife to A wood fire [Red square, the person with the knife scrapes at the oil inside the pan that's on fire while saying "OW OW OW". The scraping accompanied by the text "SCRAPE SCRAPE".] A knife to An oil fire [Green square, the person with the gun points it at the opponent with the knife, who exclaims, "Dude!"] A gun to A knife fight [Green square, two combatants point guns at one another, equally matched.] A gun to A gun fight [Red square, the person with the gun shoots pointlessly three times at the wood fire, which carries on blazing. The shooting is accompanied by the text "BLAM BLAM BLAM".] A gun to A wood fire [Red square, the person with the gun shoots at the flaming pan, which does nothing to put it out. The shooting is accompanied by the text "BLAM".] A gun to An oil fire [Red square, the person with the water throws it uselessly in the face of the person holding the knife.] Water to A knife fight [Red square, the person with the water throws it uselessly in the face of the person holding the gun.] Water to A gun fight [Green square, the person throws the water on the fire and successfully extinguishes it, which makes a "SPLOOSH" sound.] Water to A wood fire [Red square, the person is shown reeling back from the oil fire, the water glass going flying, as the oil fire explodes with a "FOOM".] Water to An oil fire [Red square, the person with the lid comically places it on the head of the person with the knife, who stands there in confusion.] A lid to A knife fight Red square, the person with the lid ineffectually places it on top of the gun the other person is pointing at them. A lid to A gun fight Red square, the person with the lid holds it near the wood fire, which does nothing to put out the fire. A lid to A wood fire [Green square, the person places the lid on top of the oil fire, which suffocates and extinguishes it.] A lid to An oil fire

This comic derives its humor from combining two common but unrelated pieces of advice: "never bring a knife to a gun fight", and "never put water on an oil fire". The corollary to these phrases is that a knife is only useful for a knife fight, and water is only useful for a wood fire (or similar solid and porous fuel). Randall creates a confusion matrix applying each of the solutions (knives, guns, lids, and water) to each of the situations (knife fight, gun fight, wood fire, oil fire) to predict the likely outcomes. The squares in the table are highlighted in green to answer "Yes" to the question, where the specified object is appropriate or advantageous for the situation, or red to answer "No", usually because the object would not be helpful in resolving the situation. The grid concludes that, not only are both pieces of advice correct (bringing knives to gun fights, and using water on oil fires would both end in likely disaster), but only the prescribed solutions are appropriate for each situation (e.g. any solution other than a lid would be ineffective for an oil fire, and potentially very dangerous). The sole exception to this trend is bringing a gun to a knife fight, which would give you a major tactical advantage over your opponent. The ultimate point of this comic may be in the title text. There is a phrase in American English, "to bring a knife to a gun fight," which means "to be so naive as to be unprepared." While Randall may be commenting specifically on managing conflict escalation by being adequately prepared for the situation, it is also possible that he is subtly expressing his opinion about the virtues of restraint. [Text in the top-left corner of the comic:] "Should you bring _____ to ______?" [The comic is laid out like a grid, with implements down the left-hand side (A knife / A gun / Water / A lid) and the type of "fight" across the top (A knife fight / A gun fight / A wood fire / An oil fire). The grid illustrates the "match-ups", with a green square denoting a "correct" match-up and a red square denoting a Very Bad Idea.] [From the top left corner, going from left to right, top to bottom, with each first item being on its own line in the grid, the squares are as follows:] [Green square, two combatants face off against each other with knives, equally matched.] A knife to A knife fight [Red square, a person with a knife faces off against someone with a gun, and is clearly outmatched.] A knife to A gun fight [Red square, a person holds a knife in a wood fire while saying "OW OW OW".] A knife to A wood fire [Red square, the person with the knife scrapes at the oil inside the pan that's on fire while saying "OW OW OW". The scraping accompanied by the text "SCRAPE SCRAPE".] A knife to An oil fire [Green square, the person with the gun points it at the opponent with the knife, who exclaims, "Dude!"] A gun to A knife fight [Green square, two combatants point guns at one another, equally matched.] A gun to A gun fight [Red square, the person with the gun shoots pointlessly three times at the wood fire, which carries on blazing. The shooting is accompanied by the text "BLAM BLAM BLAM".] A gun to A wood fire [Red square, the person with the gun shoots at the flaming pan, which does nothing to put it out. The shooting is accompanied by the text "BLAM".] A gun to An oil fire [Red square, the person with the water throws it uselessly in the face of the person holding the knife.] Water to A knife fight [Red square, the person with the water throws it uselessly in the face of the person holding the gun.] Water to A gun fight [Green square, the person throws the water on the fire and successfully extinguishes it, which makes a "SPLOOSH" sound.] Water to A wood fire [Red square, the person is shown reeling back from the oil fire, the water glass going flying, as the oil fire explodes with a "FOOM".] Water to An oil fire [Red square, the person with the lid comically places it on the head of the person with the knife, who stands there in confusion.] A lid to A knife fight Red square, the person with the lid ineffectually places it on top of the gun the other person is pointing at them. A lid to A gun fight Red square, the person with the lid holds it near the wood fire, which does nothing to put out the fire. A lid to A wood fire [Green square, the person places the lid on top of the oil fire, which suffocates and extinguishes it.] A lid to An oil fire

Obsolete Technology

Obsolete Technology

https://www.xkcd.com/1891

https://www.explainxkcd.com/wiki/index.php/1891:_Obsolete_Technology

[Ponytail sits in front of an old computer. Megan stands behind her.] Ponytail: Whoa, this is running MS-DOS! It's weird how new technology takes forever to reach some industries. Megan: Yeah. Like how we still use gunpowder for fireworks, even though we've had nuclear weapons for over 70 years.

This comic mocks people who criticize an industry for using obsolete technology, even when said technology is sufficient for the task at hand. The claim often comes with the implication that those in charge of the industry are behind the times and cannot adapt to the cutting edge. What these critics often fail to realize is that there are cost benefits to sticking with "obsolete" infrastructure, and that upgrading to the newest tech can introduce unwanted side effects and other risks. Here, Ponytail acts as one such critic, complaining that the business is taking "forever" to get with the times. Megan uses sarcasm to deliver her counterargument: despite the advent of nuclear weapons, fireworks use the ancient technology of gunpowder (invented in the 9th century), because fireworks are used by civilians for celebratory purposes and should have as few lethal side effects as possible. As they use gunpowder, fireworks do claim a handful of lives and cause thousands of injuries each year due to improper handling procedures; between June 18th and July 18th of 2016 (thus including the Independence Day celebrations on July 4th), fireworks caused an estimated 11,000 injuries, of which 7,000 had to be treated in hospitals. In the whole year of 2016, four people died ( U.S. stats ). Nuclear explosions, meanwhile, have "detrimental effects" [ citation needed ] on human health in the same way sledgehammers have "detrimental effects" [ citation needed ] to chicken eggs. For example, should a nuclear explosion at a firework display be too powerful, the spectators, and possibly the neighborhood around the display, would be vaporized instantly. Fallout from a nuclear reaction could spread radiation across a wide area, leading to increased risks of cancers and other detrimental [ citation needed ] genetic mutations. In other words, sometimes using newer technology is "overkill" for the purpose, and it might be costlier to switch to a newer technology. For example, many industrial machines were designed and sold in the 1990s when floppy disks were the prevalent means of storing the instructions, but those machines still have one or two or even more decades of usable lifetime left, and the instruction files still fit on those floppy disks. So, in 2017, there are several companies that thrive on buying, refurbishing and selling floppy disks. This report portrays one of these companies. MS-DOS is a computer operating system made by Microsoft that was dominant during much of the 1980s. When Microsoft released the Windows line of operating systems, they encouraged people to switch to the new platform, which many did. MS-DOS became essentially obsolete when Microsoft released Windows 95 in 1995. However, there remain rare circumstances in which MS-DOS (or another command-line operating system) is still preferred, such as when no mouse, touchscreen, or other pointing hardware is available, or when the hardware does not support a newer operating system. To make matters simpler, there is DOSBox , a free and open-source MS-DOS emulator which is actively maintained and extended. Likewise, FreeDOS is a free and open-source operating system designed to run on both older and newer computers which is compatible with programs written for MS-DOS. The title text uses a different twist, criticizing the current use of fax machines. In many respects, faxing is obsolete compared to e-mail; it supports only black-and-white images, it complicates the process of modifying sent text by rendering it as images, it consumes the recipient's paper and toner and, in some countries, requires the recipient to pay a fee. Fax machines are a peculiar topic among "obsolete" technology; in some fields, like lawyer offices, pharmacies and medical practices, they staunchly hold their ground, as they offer a way to quickly transfer handwritten and hand-signed documents. Confidentiality is also an issue; fax, which uses a landline, is more difficult to intercept than internet-based traffic. In some countries, a telecopy is a valid document, having the same legal value as the original. A patient can thus call their doctor to fill a prescription, which is faxed to the pharmacy where the patient can fetch their drugs, saving precious time. In the same manner, a legal request can be sent to the receiver, without having to use a courier or express mail. But rather than argue on any of the above points, the title text instead claims that faxing is obsolete due to being electron-based, while neutrino -based communication would be faster. In 2017, neutrino detectors are heavy and expensive, used for nuclear research only. Electronic communications travel at a fair share of the speed of light and the advantage of path would be at most a factor of π/2, so neutrino-based communication would normally be far too expensive compared to the speed gain. Even in the most extreme case (communicating between antipodes ), the time saved would be a few hundredths of a second – insignificant for almost all purposes, but potentially enough to gain an edge in high-frequency trading , as suggested in a 2012 Forbes article. Real-world fax detractors would rather replace it with other electronic communication systems, not neutrinic ones. [Ponytail sits in front of an old computer. Megan stands behind her.] Ponytail: Whoa, this is running MS-DOS! It's weird how new technology takes forever to reach some industries. Megan: Yeah. Like how we still use gunpowder for fireworks, even though we've had nuclear weapons for over 70 years.

USB Cables

USB Cables

https://www.xkcd.com/1892

https://www.explainxkcd.com/wiki/index.php/1892:_USB_Cables

[15 USB cables are shown lying in a column. They are mostly very similar, with small differences. To the right of the cables there are 12 labels, as three of the labels belongs to three sets of two cables.] [2 cables] Carry power but not data Carries data but not power Too short Charges phone slowly Won't auto-activate portable charger [2 cables] Has annoying ferrite lumps Heavy and not very flexible [2 cables] Frayed Plug doesn't fit through case Needs to be twisted to keep working Weird shape The good one [Caption below the panel:] The law of USB cables: No matter how many you get, you only ever have one good one.

In this comic, Randall states the 'Law of USB cables': You will never have more than one which has no problems now matter how many you get. Now that most devices charge off USB, having a cable (specifically, USB-A (the big end) to Micro-B or USB-C (the small end)) is essential. However, most USB cables are cheaply made, and carrying them around quickly damages them. This comic lists some common (and not so common) problems with USB cables. The title text refers to the popular meme " Tag yourself, I'm... " which is used with pictures containing lots of strange objects, phrases or other elements. The phrase prompts people to identify individual elements from the image that they personally feels matches their own identity, usually self-deprecatingly. (The meme stems from Facebook, where people can place tags identifying themselves in photos, but has spread to other websites without an actual tagging system.) Here, Randall suggests that, like a USB cable, he's frayed. "I'm frayed" is also a pun on the sentence "I'm afraid" that is commonly added to the end of a comment which the speaker believes may leave a negative impression on the listener. [15 USB cables are shown lying in a column. They are mostly very similar, with small differences. To the right of the cables there are 12 labels, as three of the labels belongs to three sets of two cables.] [2 cables] Carry power but not data Carries data but not power Too short Charges phone slowly Won't auto-activate portable charger [2 cables] Has annoying ferrite lumps Heavy and not very flexible [2 cables] Frayed Plug doesn't fit through case Needs to be twisted to keep working Weird shape The good one [Caption below the panel:] The law of USB cables: No matter how many you get, you only ever have one good one.

Thread

Thread

https://www.xkcd.com/1893

https://www.explainxkcd.com/wiki/index.php/1893:_Thread

[A mock-up of a “tweet” from the site twitter.com is shown. It contains a mock-up of a user photo of the fictional character F’nor that resembles Hairy , including a tiny line sketch of F’nor’s brown dragon Canth flying overhead. Below the tweet are several action buttons typical of a Twitter post for comments, replying, likes, etc.] F’nor @fnor Thread: The greatest threat to our life on Pern 1/1 On Friday, the header was replaced with a message from Randall about how he would be visiting the U.K. on the following week. It read as follows:

F'nor is a character from the popular [ citation needed ] sci-fi/fantasy series Dragonriders of Pern by Anne McCaffrey . He is posting a Twitter comment (a " thread " that's only one comment long, hence "1/1") about " Thread ", a massively destructive alien organism from the same series. Pern is a fictional human-colonized planet and the main setting of the series. Typically, when starting a series of tweets (used to post content longer than 140 characters), one will start the first tweet with "Thread: " and end it with 1/X. The second tweet will read 2/X, and so on. If X, the total number of tweets, is unknown at the start, it will be listed or 1/many or omitted: 1/ Here, there is a play on the Twitter thread and the actual threat to Pern. The use of threads on Twitter became significantly more common in 2016 and through 2017. The title text dubs this "Threadfall." In the Pern novels, Threadfall is also the name for the beginning of 50-year cyclic periods when Thread attacks the world of Pern and its inhabitants, which occur between relatively safe "Intervals" of around 200 years. Since according to the title text Threadfall occurred in 2016, it should be expected to continue for ~50 more years until the mid-2060s, when the next Interval will begin. [A mock-up of a “tweet” from the site twitter.com is shown. It contains a mock-up of a user photo of the fictional character F’nor that resembles Hairy , including a tiny line sketch of F’nor’s brown dragon Canth flying overhead. Below the tweet are several action buttons typical of a Twitter post for comments, replying, likes, etc.] F’nor @fnor Thread: The greatest threat to our life on Pern 1/1 On Friday, the header was replaced with a message from Randall about how he would be visiting the U.K. on the following week. It read as follows:

Real Estate

Real Estate

https://www.xkcd.com/1894

https://www.explainxkcd.com/wiki/index.php/1894:_Real_Estate

[Ponytail and Cueball sit in office chairs on either side of a desk. Ponytail looks at a piece of paper she is holding in her hand, more papers lie on the table. Cueball sits with his hands in his lap, thinking in a thought bubble before he replies to her remark.] Ponytail: The sellers offer to drop their price by $10,000 and cover the driveway repairs. Cueball [thinking]: These are all staggeringly large amounts of money that I have no idea how to even think about, let alone compare. Cueball [speaking]: Tempting. We'll need a few hours to consider it. [Caption below the panels:] Me in any financial negotiation.

In this comic, Cueball is speaking with Ponytail , his real estate agent, about an ongoing negotiation over the price of a house he is looking to buy. This is probably his first time buying a house and he is very overwhelmed by the process, a very common feeling among first-time home buyers. The housing market is so complicated and ever-changing, that it is almost impossible for the layman to have any concept of what a piece of property is worth. One must rely on the opinions of their real estate agent, building inspector, friends and family, along with research regarding the housing market in the area (average property values, what houses recently sold for, etc). Despite the comic mocking it as an obvious stalling tactic, telling the agent that you need time to think about it is a good strategy to research further while seeming to know what you're doing. In the caption Randall makes it seem that he is in Cueball's situation in any financial negotiation, not only for such large ones as when buying real estate. In the title text Randall mentions that he tried to convert the prices into the equivalent numbers of pizzas that amount could buy (most pizza parlors charge roughly 15 dollars for a 16-inch/40 cm pizza, so this price cut could net him over 650 pizzas even before the driveway repairs). Thinking of the price of an object (or a reduction in the price) in terms of the number of pizzas (or similar objects) that amount could buy is a good strategy for weighing the pros and cons of a smaller purchase, but doesn't help in this situation, as the number of pizzas is so large that it becomes meaningless in itself. For example, a $300k house would represent 20k pizzas, or enough to have a pizza for breakfast, lunch, and dinner for about 18 years! A better strategy would be to compare the large price to his average monthly cost of living (rent, utility bills, car payments, et al), or to compare to the comparatively stable average cost to build on-site, or the price of factory built homes. This comic is in line with the much older 616: Lease and the more recent 1674: Adult regarding buying real estate and not feeling grown up (see also 905: Homeownership ). This comic (and the title text) also alludes to the fact that humans are generally very bad at comprehending/visualizing very large numbers; mathematician Spencer Greenberg has similarly suggested trying to convert very large numbers into different units (such as US national debt into US national debt per person) in an effort to bring the magnitudes down into something more comprehensible, something that Randall humorously attempts to do with the aforementioned conversion to quantities of pizza. [Ponytail and Cueball sit in office chairs on either side of a desk. Ponytail looks at a piece of paper she is holding in her hand, more papers lie on the table. Cueball sits with his hands in his lap, thinking in a thought bubble before he replies to her remark.] Ponytail: The sellers offer to drop their price by $10,000 and cover the driveway repairs. Cueball [thinking]: These are all staggeringly large amounts of money that I have no idea how to even think about, let alone compare. Cueball [speaking]: Tempting. We'll need a few hours to consider it. [Caption below the panels:] Me in any financial negotiation.

Worrying Scientist Interviews

Worrying Scientist Interviews

https://www.xkcd.com/1895

https://www.explainxkcd.com/wiki/index.php/1895:_Worrying_Scientist_Interviews

[A chart consisting of a line with double arrows that has 12 dots progressing from left to right. Each dot has a line going to a label above or below the line. Above the labels is another label belonging to an arrow to its right that points right. Above this is a larger caption:] How worried you should be if you see local reporters interviewing scientists about a breaking news story, by field: More worried ---> [The chart shows the following titles left to right (least to most worrisome), some above and some below the line however that doesn't affect their relative positions. They are listed here in ascending worrisomeness for ease of viewing.] Archeologist Economist Nutritionist Criminologist Ornithologist Botanist Marine biologist Entomologist Astronomer Virologist Vulcanologist Astronomer who studies the sun

When a new development occurs, news channels will often interview an expert in the field to educate laymen in what, exactly, is happening. Thus, when you turn on the local news and see a scientist being interviewed, it is likely that something new has come up regarding their field of study that could affect you. How much it affects you could range from an interesting bit of information about your local area, to the complete annihilation of the human race. So, to help identify how serious the issue likely is, Randall has made this chart showing how worried you should be depending on the field of the scientist. A table has been arranged to explain the amount of worry needed for each field below. To the far left, the least worrying are archaeologist and economist . An archaeologist studies ancient human civilizations, which would be unlikely to harm any modern person. Economists study and explain the trends of finances and resources, which are also unlikely to pose an immediate threat. [ citation needed ] Following this, it shows nutritionists and eventually criminologists . A nutritionist studies nutrition in the human body, and is likely discussing which food options are healthy or unhealthy. While this may be important, it is not a cause for immediate concern. A criminologist, however, studies criminal behaviour. If a criminologist is being interviewed on the news, there is likely a change in criminal actions within the neighbourhood, be it more or less. It is also possible there may be a serial criminal working in the area. However, because crime is a relatively rare occurrence, and one for which precautions can be taken, it is still unlikely to be an immediate threat to the viewer. It then moves past researchers studying different types of organisms, before reaching astronomers. Still only very few events would be local regarding astronomy, but it could of course be regarding a pending meteor strike. A virologist studies viral infections and their spread, and a vulcanologist studies volcanoes . Viruses spread quickly, and can be fatal, meaning a breaking news development in one's locale regarding viruses is likely to mean imminent danger. Volcanoes, depending on their size, can potentially demolish entire countries, thus having one making headlines nearby is also very concerning. The last point to the right (most worried) "Astronomer who studies the Sun", also called a " solar physicist " (mentioned in the title text), could be really troublesome, but not especially locally. If there are serious problems with the Sun it will be a world-wide problem. But you should still be worried. The title text mentions that the reason they are not called solar physicists, is that before they can tell the reporter this, they are interrupted by the anxious reporter who wishes to know what's wrong with the Sun. This is not really something that happens so often [ citation needed ] that the title texts "They always try" has any real meaning. And this is also why no one knows or uses the term solar physicists... [A chart consisting of a line with double arrows that has 12 dots progressing from left to right. Each dot has a line going to a label above or below the line. Above the labels is another label belonging to an arrow to its right that points right. Above this is a larger caption:] How worried you should be if you see local reporters interviewing scientists about a breaking news story, by field: More worried ---> [The chart shows the following titles left to right (least to most worrisome), some above and some below the line however that doesn't affect their relative positions. They are listed here in ascending worrisomeness for ease of viewing.] Archeologist Economist Nutritionist Criminologist Ornithologist Botanist Marine biologist Entomologist Astronomer Virologist Vulcanologist Astronomer who studies the sun

Active Ingredients Only

Active Ingredients Only

https://www.xkcd.com/1896

https://www.explainxkcd.com/wiki/index.php/1896:_Active_Ingredients_Only

[A picture of a pack of cold medicine. At the top there is a large advert in three lines. In a black line, to the right of the advert, white text states what kind of medicine is in the pack. Below to the left is a square frame listing ingredients. Most of the text inside this frame is unreadable scribbles. To the right of the frame is another advert inside a black frame. On the side of the box are also unreadable scribbles, both at the top and down next to the ingredients list. At the bottom of the box it can be seen how the pack can open up.] Active Ingredients Only TM We're not here to waste your time® Cold Medicine Active ingredients [Six lines of scribbles, with first a name, then a statement in brackets and finally a column right of this with a short line of scribbles.] Inactive ingredients None No binders!

Commercial medicine typically has one (or a few) "Active" ingredient and many "Inactive" ingredients. Active ingredients are the actual medicine, while inactive ingredients -- such as preservatives, dyes, or binders -- are added to dilute the active ingredient to a healthy level and help the body absorb the dose of active ingredient. Randall thus presents a pack of cold medicine that has "Active Ingredients Only", which is the name of the brand as can be seen since it has "™" after the name (the unregistered trademark symbol). It has six active ingredients and no inactive ingredients. This is a spoof of the current trend of advertising food as containing "no additives and no preservatives". Cold medicines are commonly packaged in blister packs, with each dose contained separately, and vegans commonly open up gelatin capsules and discard the capsule, ingesting only the contents of the pill (note that this may not be safe . Please consult your pharmacist or doctor before doing this). By removing the inactive ingredients of the gelatin and the requirement to open it up, the slogan We're not here to waste your time , is justified. This slogan is also trademarked. The slogan is a registered trademark (®) while the product name is a common law trademark. This means that the slogan likely stays the same, while the product name changes from time to time. In the title text, the medicine company promises their product "Contains the active ingredients from all competing cold medicines, plus the medicines for headaches, arthritis, insomnia, indigestion, and more, because who wants THOSE things?" This may be be a follow-up (or a wish from Randall) after 1618: Cold Medicine , where Cueball wishes to try all possible types of cold medicine at once. The provided justification for combining all these medications is simple: These medicines cure unpleasant symptoms, so taking them all must be a good thing. What this ignores is that taking medicine intended to solve symptoms one doesn't have can be potentially harmful, and would likely be unavoidable for this product's consumers unless they are suffering from all these conditions simultaneously. Furthermore, mixing medications can often lead to unintended reactions and side effects, and is typically advised against. Another joke is that popular cold medicines contain no antiviral ingredients at all, and treat symptoms only -- while it might make your runny nose less runny, it will do just as much to clear the rhinovirus causing your runny nose as a sugar pill. This part of the comic may be a follow-up to 1526: Placebo Blocker , where a sugar pill is offered to treat a headache. A secondary joke is by claiming the active ingredients from all "competing" cold medicines, the company producing this "Active Ingredients Only" may choose whom they say they are competing against. Some cold medications treat only pain and fever, for example, and do nothing for cough, congestion, runny nose and sneezing. Doctors recommend medicines which aid for the particular symptoms of the cold one is experiencing. [A picture of a pack of cold medicine. At the top there is a large advert in three lines. In a black line, to the right of the advert, white text states what kind of medicine is in the pack. Below to the left is a square frame listing ingredients. Most of the text inside this frame is unreadable scribbles. To the right of the frame is another advert inside a black frame. On the side of the box are also unreadable scribbles, both at the top and down next to the ingredients list. At the bottom of the box it can be seen how the pack can open up.] Active Ingredients Only TM We're not here to waste your time® Cold Medicine Active ingredients [Six lines of scribbles, with first a name, then a statement in brackets and finally a column right of this with a short line of scribbles.] Inactive ingredients None No binders!

Self Driving

Self Driving

https://www.xkcd.com/1897

https://www.explainxkcd.com/wiki/index.php/1897:_Self_Driving

[Inside a frame there is the following text above an image:] To complete your registration, please tell us whether or not this image contains a stop sign: [The square image is a drawing of a road leading up to a sign post with a hard to read word at the top part of the eight-sided sign. The sign also has two smaller signs left and right with unreadable text. The image is of poor quality, but trees and other obstacles next to the road can be seen. Darkness around the edges of the image could indicate that it is night and the landscape is only lit up by a cars head lights.] Sign: Stop [Beneath the image there are two large gray buttons with a word in each:] No Yes [Beneath the buttons are the following text:] Answer quickly – our self-driving car is almost at the intersection. [Caption beneath the frame:] So much of "AI" is just figuring out way to offload work onto random strangers.

This comic references the approach of using CAPTCHA inputs to solve problems, particularly those involving image classification, which are not solvable by computers, specifically reCAPTCHA v2's fallback puzzle, and hCaptcha's puzzle, both of which are based on identifying road features and vehicles. A reCAPTCHA version of this puzzle would ask "check all squares containing a STOP SIGN" using one or more images derived from Google Street View . Such an approach can serve to create the learning set as the basis for training an artificial intelligence (AI) to better recognize or respond to similar stimuli. This approach was used by Google, the owners of reCAPTCHA, to identify house numbers in Street View to improve their mapping, and nowadays Google also uses CAPTCHAs to identify vehicles, street signs and other objects in Street View pictures. This might be a reasonable way to help improve the performance of the AI in a self-driving car that responds to video input, by reviewing images it might encounter and flagging road signs, etc. that it should respond to. Later a similar approach to learning important things, for the robots, was used in 2228: Machine Learning Captcha . However, the temptation might be to simply sidestep the hard problem of AI by having all instances 'solved' by "offloading [the] work onto random strangers" through CAPTCHAs. For example, this has been used to defeat CAPTCHAs themselves; people were asked to solve CAPTCHAs to unlock pornographic images in a computer game, while the solution for the CAPTCHA was relayed to a server belonging to cybercriminals. (See PC stripper helps spam to spread and Humans + porn = solved CAPTCHA ). Alarmingly, the developers of this ' self driving ' car seem to have gone for the lazy approach. Instead of teaching an AI, the CAPTCHA answer is used in real time to check whether the "self-driving" car is about to arrive at an intersection with a stop sign. This information is pretty critical, as failing to mark the stop could cause an accident. The user is unlikely to respond to the CAPTCHA in time to avert disaster, not to mention that any interruption to the car's internet connection could prove fatal. Self driving cars have become a recurrent theme on xkcd. The system depicted is a Wizard of Oz experiment (as is the "Mechanical Turk" which a popular crowdworking system is named after) whereas actual self-driving cars, to the extent that they can use reCAPTCHA-style human detection systems, would involve an asynchronous decision system. Other synchronous decision systems which actually exist are political voting and money as a token of the exchange value of trade. The title text explains that this method could be called "crowdsourced steering", crowdsourcing meaning sending the data on the internet to let several users provide their ideas and input on a problem. People would naturally suspect that this is considerably less safe than a car which is actually capable of self-driving; if the internet can barely collectively steer a videogame character , what chance do they have steering an actual, physical vehicle? This also suggests that Randall is a bit skeptical of the current stage of AI, as this doubts whether the AI technology really is working in the way that we expect. It also comments on how what we call 'progress' actually is putting our work onto other people. [Inside a frame there is the following text above an image:] To complete your registration, please tell us whether or not this image contains a stop sign: [The square image is a drawing of a road leading up to a sign post with a hard to read word at the top part of the eight-sided sign. The sign also has two smaller signs left and right with unreadable text. The image is of poor quality, but trees and other obstacles next to the road can be seen. Darkness around the edges of the image could indicate that it is night and the landscape is only lit up by a cars head lights.] Sign: Stop [Beneath the image there are two large gray buttons with a word in each:] No Yes [Beneath the buttons are the following text:] Answer quickly – our self-driving car is almost at the intersection. [Caption beneath the frame:] So much of "AI" is just figuring out way to offload work onto random strangers.

October 2017

October 2017

https://www.xkcd.com/1898

https://www.explainxkcd.com/wiki/index.php/1898:_October_2017

[Megan and Cueball are walking.] Megan: Want to feel old? Cueball: Why do you always start your factoids that way? Of course I don't want to feel old. I already feel old. [Slim beat panel where they keep walking.] [In a frame-less panel only Cueball is shown walking.] Cueball: ...Fine, hit me. [Megan holds her hand up as they again are shown walking together. Cueball balls his hands up into fists in response to her comment.] Megan: If you broke a mirror back when the Aaron Sorkin Facebook movie came out, your seven years of bad luck would be over this week. Cueball: Dammit.

Randall once again makes us feel old by referencing an old movie that our memory puts as recent. The movie in question is The Social Network , written by Aaron Sorkin and directed by David Fincher , which was released seven years and three days prior to this comic, on October 1, 2010. Seven years is also how long some people believe bad luck will follow you after breaking a mirror . Megan has often tried to make Cueball feel old and he thus claims he doesn't want to hear another of her factoids that will make him feel older, as he already feels old. Megan actually complies, but in the end Cueball gets too curious and ask her to hit him with the fact, which he immediately regrets. A mirror was previously broken by Black Hat in 1136: Broken Mirror . However, as of October 2017, there are still 2 years left of bad luck. The title text refers to the the 2016 US presidential election which took place on November 8, 2016, almost 11 months before this comic, and Randall/Cueball cannot understand that this is not longer ago. Donald Trump won in a surprise victory over Hillary Clinton ( Randall 's preferred of the two, see 1756: I'm With Her ). A common refrain, especially among comedians, is that Donald Trump's tumultuous presidency so far has been so stressful and eventful that the election feels like it took place far longer than 11 months ago. Backward telescoping is a psychological effect that causes people to overestimate the elapsed time since an event. Interestingly, the title of this comic is patterned on the previous "this will make you feel old" comic " November 2016 ," which was published in the early hours of November 9th, while the presidential election's ballots were still being counted. Some people (including explain xkcd editors, writing in that explanation's trivia section, see that for more details, also on this special title name) felt that Randall could have published something more timely, and commented that the election had made them feel old enough as it was. By using the same sort of title and making this joke, Randall brings the whole thing full circle. Shortly after the election Randall made several comics that could indicate his emotions regarding the result, but references to the election have become fewer and farther apart and here he again indicates that he has not been happy with the election result and what has followed, causing him to feel that all these bad things could not really have happened in less than a year, but they did. [Megan and Cueball are walking.] Megan: Want to feel old? Cueball: Why do you always start your factoids that way? Of course I don't want to feel old. I already feel old. [Slim beat panel where they keep walking.] [In a frame-less panel only Cueball is shown walking.] Cueball: ...Fine, hit me. [Megan holds her hand up as they again are shown walking together. Cueball balls his hands up into fists in response to her comment.] Megan: If you broke a mirror back when the Aaron Sorkin Facebook movie came out, your seven years of bad luck would be over this week. Cueball: Dammit.

Ears

Ears

https://www.xkcd.com/1899

https://www.explainxkcd.com/wiki/index.php/1899:_Ears

[Cueball is sitting with his back towards Megan who is lying on her back on a grassy hill. Both are looking up at a sky with small puffy clouds (one large, two small, and four tiny). In the background fields are visible below their vantage point.] [Same setting, but with the clouds removed, to make room for Cueball's text.] Cueball: Do you ever just look up at the sky and wonder... [Same setting, zoomed a bit out to make more of the background fields visible, still with the clouds missing due to the text from the two people.] Cueball: "What are normal peoples' ears shaped like, that earbuds stay in without falling out?" Megan: Man, who knows what's going on in there.

Cueball and Megan are sitting in a park together and appear to be cloudwatching. Cueball asks if Megan has ever looked up in the sky and wondered, suggesting that he is thinking deep thoughts while allowing his mind to wander, what "normal" people's ears are shaped like; that their earbuds stay fitted inside their ears instead of falling off. It is possible, but not evident, that Cueball is listening to some audio device through earbuds , and his wondering is caused because he looked up at the sky and they fell out, leading to his thoughts about what it would be like to have "normal shaped ears" that would allow him to wear earbuds without this happening. (This joke is directed towards a large group of people who cannot use earbuds successfully because they fall out.) Megan's response could either be making fun of Cueball (whatever goes on in his head with the random conversation points he tends to bring up) or agreeing with him that earbud wearers' ears are mysterious. The comic appears to be a variation on a famous and often-quoted fragment from Voltaire 's satirical novella Candide , wherein Dr. Pangloss states that we live in ' the best of all possible worlds ', among other reasons because '…noses were made to wear spectacles, and so we have spectacles'. The title text is a play on conspiracy theories wherein the human race is being assimilated by aliens, and the person coming up with the conspiracy theory thinks he is one of the few "free" survivors. The use of "brain slugs" in particular may be a reference to the Animorphs book series, a nostalgic favorite of Randall's, in which humanity is being colonized by parasitic alien slugs called Yeerks , that enter a human's brain through the ears and can control them. Randall/Cueball here is suggesting that the reason most humans can wear earbuds is because the Yeerks hold the earbuds in place. Another possibility, given the earbud/music reference, is that Randall is making a joke about earworms . [Cueball is sitting with his back towards Megan who is lying on her back on a grassy hill. Both are looking up at a sky with small puffy clouds (one large, two small, and four tiny). In the background fields are visible below their vantage point.] [Same setting, but with the clouds removed, to make room for Cueball's text.] Cueball: Do you ever just look up at the sky and wonder... [Same setting, zoomed a bit out to make more of the background fields visible, still with the clouds missing due to the text from the two people.] Cueball: "What are normal peoples' ears shaped like, that earbuds stay in without falling out?" Megan: Man, who knows what's going on in there.

Jet Lag

Jet Lag

https://www.xkcd.com/1900

https://www.explainxkcd.com/wiki/index.php/1900:_Jet_Lag

[Hairy, with more messed up hair than usual, is rubbing his eyes while small "sleepy" bubbles form over his head, while walking towards Ponytail.] Hairy: Sorry, I just woke up. Ponytail: It's 3 PM! ...Oh, of course, you're still jet lagged. Hairy: I-yeah, that's it! I definitely didn't spend half the night reading Wikipedia articles about random maritime disasters. [Caption below the panel:] I love traveling, because my sleep schedule is as messed up as always, but suddenly I have an excuse.

Jet lag is a physiological condition widely attributed to the effect of changing one's longitude fast enough that one's "body clock" is unable to adapt to the official clock. (The actual causes are somewhat more complex, and may be influenced by the cramped conditions on the airplane. The effect of travel between the east coast of North America and the west coast of South America, which are at nearly the same longitude, and differ by only one hour in official clock time, is much more severe than the effects of setting clocks ahead an hour in the spring and behind an hour in the fall. Some White House staffers get jet lag when they travel on commercial flights but not when they travel on Air Force One.) Symptoms include a sleep cycle which does not match the solar cycle as it usually would. [ citation needed ] Hairy , representing Randall , has just woken up at 3 o'clock in the afternoon, and Ponytail mentions he must be still jet lagged (possibly from a recent trip). Hairy then denies much too specifically that he has actually been up to some late-night Wikipedia browsing and reading about maritime disasters . In the caption Randall confesses that he loves traveling, because he can then use jet lag as a nice excuse for what is actually his usual messed up sleep cycle. In the title text, Randall states that he had to do some important research. But what he lists, are clearly also just topics he read in Wikipedia: proposed interstellar space missions, basketball statistics , canceled skyscrapers , and every article linked from " Women in warfare and the military in the 19th century ." Randall has earlier illustrated this issue in 214: The Problem with Wikipedia . Randall has previously discussed his oft-changing sleep cycle in 320: 28-Hour Day and 448: Good Morning , and has alluded to it more subtly in 68: Five Thirty , 92: Sunrise , and 776: Still No Sleep . We can thus see that this is a habit of Randall's that has persisted for more than a decade, as has his obsession with Wikipedia. [Hairy, with more messed up hair than usual, is rubbing his eyes while small "sleepy" bubbles form over his head, while walking towards Ponytail.] Hairy: Sorry, I just woke up. Ponytail: It's 3 PM! ...Oh, of course, you're still jet lagged. Hairy: I-yeah, that's it! I definitely didn't spend half the night reading Wikipedia articles about random maritime disasters. [Caption below the panel:] I love traveling, because my sleep schedule is as messed up as always, but suddenly I have an excuse.