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Technical Analysis

Technical Analysis

https://www.xkcd.com/2101

https://www.explainxkcd.com/wiki/index.php/2101:_Technical_Analysis

[A series of red and green box-and-whisker plots form a line that starts in the bottom left corner of the image and wiggles up to the top right corner, with a series of peaks and troughs that resemble a typical stock market diagram. The diagram is annotated with lines, arrows and text.] [Title in top left corner] The basics of technical analysis [A roughly horizontal section with mostly green boxes:] Allegro [A horizontal bracket encompasses the next three sections] Prologue [Slope becomes slightly negative. Mostly red boxes, bordered with a black line above and below:] Decline [A roughly horizontal section with mostly green boxes, bordered with a black line above and below:] Doldrums [Line curves upwards with mostly green boxes, with a dashed black line below:] Spline [Three green boxes at minor peaks in the line are circled and indicated with arrows:] [Hmm!] [A section with slight positive slope and a mixture of red and green boxes, with a solid black line below:] Lumbar support [Slope increases. All green boxes, with a black line through the centre:] Renewal [A sharp upwards incline, with two large green boxes:] Hark! The cliffs! [Two black dots and a dashed black line connect two major peaks:] These two points define a line! Promising signal [Inside trough between two major peaks is a roughly drawn black triangle:] Bathtub [Slope becomes negative, mostly red boxes with a black line through the centre:] Declination [At the lowest point of the trough:] Inflection [Slope becomes positive, mostly green boxes with a black line through the centre:] Uptalk [Slight negative slope, with large error bars. Mixture of red and green boxes. One red box is marked with an arrow:] Yikes! [Negative slope, all red boxes. Gap between two central boxes is circled:] Wrong! [Line rises then falls. Mixture of red and green boxes with non-parallel dashed black lines above and below:] If I add some lines here I can convince myself I'm doing something more than just seeing patterns in a graph of a random walk. [Positive slope, all green boxes with a black line through the centre:] Slope! [One error bar on a green box is circled:] Could be an omen? [Arrow indicating peak:] Red + Green = Christmas! [Positive slope, all green boxes with a wiggly black arrow through the centre. A separate arrow points off the edge of the page:] Likely to continue forever

There are two recognized methods to attempt to predict the stock market, each with its own pros and cons: Random Walk theory suggests that neither of these methods are particularly useful at predicting the future of the stock market (see link for a funny story about dart throwing monkeys). The theoretical value of a stock is its net present value , which is the sum of all its future earnings, with earnings in the future discounted appropriately to account for the time value of money . Because these earnings are never fully predictable, traders may have different ideas about the true value of a stock, and buy the stock if they believe the currently offered prices are particularly low, or sell it when the prices are high. Technical analysis, however, does not even attempt to understand the earnings of the stock, instead focusing on the shapes and patterns that result from traders making their moves. While there is a human behavioral component to stock trading, it is not clear that one can extract much information from the shapes of stock charts. To the extent it does work, a substantial part of its success may be simply an artifact of the herd behavior of traders who engage in technical analysis, a zero-sum game. The comic displays a stock price chart , annotated with labels which purport to be technical analysis. These labels are nonsense from the perspective of technical analysis, but do accurately describe the graph itself: " allegro " (a musical term used to set the tempo at the beginning of a score), " prologue " (an introductory section of a play, book, or similar), " lumbar support" (the thing in a chair shaped to better support your back), "bathtub" (possibly a reference to the so-called " Bathtub curve "), " uptalk " (a speech pattern). One label celebrates that "these two points define a line! Promising signal." (In geometry, any two points define a line.) The shape of the chart is similar to the exponential behavior of cryptocurrencies when they are successful, where price (positional height on the chart) roughly increases while volatility (height of the bars or candles themselves, and of the peaks and troughs, on the chart) does the same. Technical analysis used to be an esoteric domain held by well-paid stock analysts, but as cryptocurrency has spread, and as financial companies have made it easier for members of the public ("retail investors", as opposed to "institutional investors") to engage in investment trading, people from all walks of life have begun staring at charts like this. The title text is a quote from James Tobin (from his 1984 paper On the efficiency of the financial system ) that raises a question of very talented people building systems to make themselves a lot of money without actually accomplishing anything worth money. The quote was about the stock market and high speed traders in particular. It comments on the 'financialization' of the economy, where activities like speculation and abstracted financial products have become an increasingly large part of the economy, as opposed to investment in productive industry. Interestingly, this comic appeared the day after Oxfam reported that the world's 2,200 billionaires had added 12% to their wealth in 2018, while the 3.8 billion people comprising the poorest half of the world's population had lost 11%. Perhaps this prompted what appears to be Randall's jab at those whose business is merely making money. [A series of red and green box-and-whisker plots form a line that starts in the bottom left corner of the image and wiggles up to the top right corner, with a series of peaks and troughs that resemble a typical stock market diagram. The diagram is annotated with lines, arrows and text.] [Title in top left corner] The basics of technical analysis [A roughly horizontal section with mostly green boxes:] Allegro [A horizontal bracket encompasses the next three sections] Prologue [Slope becomes slightly negative. Mostly red boxes, bordered with a black line above and below:] Decline [A roughly horizontal section with mostly green boxes, bordered with a black line above and below:] Doldrums [Line curves upwards with mostly green boxes, with a dashed black line below:] Spline [Three green boxes at minor peaks in the line are circled and indicated with arrows:] [Hmm!] [A section with slight positive slope and a mixture of red and green boxes, with a solid black line below:] Lumbar support [Slope increases. All green boxes, with a black line through the centre:] Renewal [A sharp upwards incline, with two large green boxes:] Hark! The cliffs! [Two black dots and a dashed black line connect two major peaks:] These two points define a line! Promising signal [Inside trough between two major peaks is a roughly drawn black triangle:] Bathtub [Slope becomes negative, mostly red boxes with a black line through the centre:] Declination [At the lowest point of the trough:] Inflection [Slope becomes positive, mostly green boxes with a black line through the centre:] Uptalk [Slight negative slope, with large error bars. Mixture of red and green boxes. One red box is marked with an arrow:] Yikes! [Negative slope, all red boxes. Gap between two central boxes is circled:] Wrong! [Line rises then falls. Mixture of red and green boxes with non-parallel dashed black lines above and below:] If I add some lines here I can convince myself I'm doing something more than just seeing patterns in a graph of a random walk. [Positive slope, all green boxes with a black line through the centre:] Slope! [One error bar on a green box is circled:] Could be an omen? [Arrow indicating peak:] Red + Green = Christmas! [Positive slope, all green boxes with a wiggly black arrow through the centre. A separate arrow points off the edge of the page:] Likely to continue forever

Internet Archive

Internet Archive

https://www.xkcd.com/2102

https://www.explainxkcd.com/wiki/index.php/2102:_Internet_Archive

[Ponytail and Cueball are walking to the right.] Ponytail: The Internet Archive is so weird. If it didn't exist, it would sound totally implausible. Cueball: Seriously. [Ponytail and Cueball continue walking to the right.] Cueball: Do you ever worry about how reliant we are on systems that someone happens to maintain for some reason but which could disappear at any time? [Ponytail and Cueball are seen in silhouette from a distance.] Ponytail: Yeah - the same thing freaks me out about having a body. Cueball: I know, right?? I don't even know what half these parts do ! Ponytail: And yet if they stop, we die! Cueball: Probably best not to think about it.

The Internet Archive is a project that is invaluable for internet research. It is a public archive of information, including public domain books and music. It also runs the Wayback Machine , an archive of backups of web pages all over the Web at various times that can be used to see past versions of a page, even if that site has since shut down. The Internet Archive accepts submissions of any type of information, including new backups of web pages and newly-made public domain content. Ponytail and Cueball first remark upon how weird the concept of the Internet Archive is, commenting that it would seem like an implausible concept if not for the fact that it already existed. This revisits a point that Randall made in 2085: arXiv : in the title text for that comic, he wrote, Both arXiv and archive.org are invaluable projects which, if they didn't exist, we would dismiss as obviously ridiculous and unworkable. Our culture has an overarching theme of equating profit with success, so when efforts succeed due to inherent public benefit, this can often yield surprise. They then become more philosophical, and wonder about invaluable systems that are maintained by a just a few individuals, meaning that they could disappear if any of those people stopped doing what they were doing. They relate this to the function of the human body , which does contain many systems whose function and inner workings are unknown to the average person. Again, as in 2085: arXiv , the two try not to "jinx things" by drawing attention to the improbability of this system working perfectly. In arXiv, when Megan exclaims that being able to post research papers as free PDFs on arXiv "makes no sense at all", Ponytail responds, "Shhh, you'll jinx it!" Here, Cueball tells Ponytail, "Probably best not to think about it." This is ironic as the inclusion of this information in a popular comic like xkcd is drawing attention to it. As an example of "invaluable systems maintained by just a few individuals", the title text refers to the " npm left-pad incident ", a 2016 incident where a package for the npm package manager was removed from the software library by its author. As this particular package was used by many projects, both directly and indirectly, this caused a severe disruption in the software world. Randall is relieved that cases like this do not occur more frequently. This topic appears to stay on his mind for a while, since 2347: Dependency covers a similar theme. [Ponytail and Cueball are walking to the right.] Ponytail: The Internet Archive is so weird. If it didn't exist, it would sound totally implausible. Cueball: Seriously. [Ponytail and Cueball continue walking to the right.] Cueball: Do you ever worry about how reliant we are on systems that someone happens to maintain for some reason but which could disappear at any time? [Ponytail and Cueball are seen in silhouette from a distance.] Ponytail: Yeah - the same thing freaks me out about having a body. Cueball: I know, right?? I don't even know what half these parts do ! Ponytail: And yet if they stop, we die! Cueball: Probably best not to think about it.

Midcontinent Rift System

Midcontinent Rift System

https://www.xkcd.com/2103

https://www.explainxkcd.com/wiki/index.php/2103:_Midcontinent_Rift_System

[A map of North America shows the Midcontinent Rift System as a red line curving through the Great Lakes and down through the midwestern United States.] 1.1 billion years ago, the North American continent began to split in half. [Black Hat stands at a lectern with a "Vote 2020" sign on it. He gestures to an image of the globe with a giant crowbar inserted in the rift with an arrow indicating applying pressure to widen the rift.] Black Hat: We don’t know why it stopped. If elected, I vow to finish the job. Thank you. [Ponytail, Black Hat, Megan, and Cueball walk to the right away from a set of stairs. Cueball is looking at a phone and Ponytail is looking at a device or paper with writing on it.] Ponytail: Great job up there. Black Hat: Thanks! How are my polling numbers? Ponytail: Well, I’m seeing some weakness in the Midwest. Black Hat: So am I. So am I.

Recently, USA politics has caused polarization of the public. [1] It is said to be “split” in two camps (liberal, mostly loyal to the Democratic Party , and conservative, mostly loyal to the Republican Party ). Here Black Hat is trying to get elected to some sort of federal office in the at the time upcoming 2020 elections by promising he will actually split America in two. His presentation illustrates, using a giant crowbar, the completion of the Midcontinent Rift , which is a large crack that started to form about 1.1 billion years ago, but failed to completely sever the continent. Around the same time, the rift was also mentioned in "How To", Chapter 9: How to build a lava moat. It is unclear why anyone would vote for such a thing, but people directly affected (the Midwest) are likely to vote against Black Hat . While Black Hat and his campaign advisor Ponytail speak of weakness in the Midwest, they are talking about two different things: Black Hat refers to the physical weakness of the North American Plate in the Midwest due to the geological rift which he thinks could be exploited by a large enough crowbar, while Ponytail is referring to a political weakness for Black Hat’s campaign in the Midwest due to the likely-unpopular proposal (different regions of the US have different voters and populations who have different priorities and stances, so candidates and their campaigns’ platforms will likely be more popular in some regions and less popular in others). In this case a successful or attempted completion of the rift would likely result in the destruction of millions of houses, buildings, and other man-made structures, not to mention the deaths of many humans (if proper evacuation were not fully implemented and enforced) as well as millions of animals that could not be evacuated. The proposal would also cause huge economic impacts; the Midwest produces a significant proportion of America’s food supplies and hosts important economic centres, such as Chicago and Cleveland. So the popularity among those directly or even indirectly affected is likely quite low. The successful passing of a highly destructive measure such as this would generally involve more direct and overwhelming compensation of the many interests that would otherwise be harmed, to incentivize them to vote against their present livelihood. The title text is a pun. A wedge issue is a controversial issue which splits apart a demographic group. It is often introduced to create controversy within an opponent’s base so that if the opponent takes any position on the issue, half the voters will desert the opponent. Here the joke is that the “wedge issue” is an actual wedge to split apart the United States. It could potentially be a wedge issue, as while most people would oppose such a measure, some people could be convinced that it would benefit certain Midwestern cities by making them port cities, which would result in an economic boom and make trade easier if those cities weren't destroyed. Also, some die-hard liberals living outside the Midwest might favor the destruction of the Midwest because it tends to vote conservative. Ponytail seems to state that Black Hat's proposal is only unpopular in the Midwest. [A map of North America shows the Midcontinent Rift System as a red line curving through the Great Lakes and down through the midwestern United States.] 1.1 billion years ago, the North American continent began to split in half. [Black Hat stands at a lectern with a "Vote 2020" sign on it. He gestures to an image of the globe with a giant crowbar inserted in the rift with an arrow indicating applying pressure to widen the rift.] Black Hat: We don’t know why it stopped. If elected, I vow to finish the job. Thank you. [Ponytail, Black Hat, Megan, and Cueball walk to the right away from a set of stairs. Cueball is looking at a phone and Ponytail is looking at a device or paper with writing on it.] Ponytail: Great job up there. Black Hat: Thanks! How are my polling numbers? Ponytail: Well, I’m seeing some weakness in the Midwest. Black Hat: So am I. So am I.

Biff Tannen

Biff Tannen

https://www.xkcd.com/2104

https://www.explainxkcd.com/wiki/index.php/2104:_Biff_Tannen

[Cueball talks while walking up behind White Hat, who is reading in an armchair.] Cueball: You know, in the universe where Biff Tannen took Marty McFly’s sports almanac back in time, the people wouldn’t have any counterfactuals to work with. Cueball: Their world would be the world. [In a frame-less panel White Hat turns his head to look at Cueball as he keeps talking.] Cueball: They would have spent decades debating which structural problems enabled the rise of BiffCo, the decline of the city, and general social decay. Cueball: Everyone would find reasons it confirmed their pet theory. [White Hat turns his head back to his book.] Cueball: I'm going to write a book set in that universe. I'll call it Hill Valley Elegy . White Hat: ... I hate you.

Cueball is expounding a theory to White Hat regarding the alternate timeline seen in the movie Back to the Future II , in which the character Biff Tannen stole a time machine and used it to travel 60 years into the past to 1955. In that timeline, Future Biff gave his younger self a sports almanac containing 50 years of outcomes of sporting events, which enabled his younger self to earn millions from betting on horse races . The end result of this is that the now-altered present of 1985 has become a corporate dystopia due to the actions of the exceedingly wealthy Biff and his company, BiffCo. Cueball's theory is that the people now living in this dystopian 1985 would never know that their timeline was altered; as far as they are concerned, theirs is the true timeline. Because of this, they would seek to analyze every detail of Biff Tannen's rise to power, inventing their own theories as to his success and arguing with each other over the supporting evidence. However, in the third panel, it becomes clear that this has all merely been Cueball's elaborate setup for a bad pun, causing White Hat to voice his disapproval. Back to the Future II This comic is based on Back to the Future II . In this movie, the character Biff Tannen steals the time machine , which is the main plot device, and uses it to go back in time from 2015 to 1955. He then gives Marty McFly’s sports almanac , containing the outcomes of 50 years (1950–2000) worth of sporting events, to his own younger self. His younger self uses this sports almanac to make millions by successfully betting on horse races . He then forms a company, and calls it BiffCo . In the movie, the protagonists reverse this, by going back to 1955 and stealing the almanac back soon after Biff delivered it. It is heavily implied that the universe where BiffCo exists, also called “ 1985A ” in the movie, stops existing after this change, since the Biff from 1985A tries to kill Marty to stop him from doing this. However, Cueball imagines the 1985A timeline as continuing to exist in parallel, rather than being destroyed by the almanac heist as the movie seems to imply. This is consistent with the multiverse theory. The movie is set in the fictional town of Hill Valley, California . When the protagonists return to 1985, they find that Biff has turned the town’s “Courthouse Square” into a 27-story casino, and generally taken over Hill Valley. This has apparently resulted in the town being overrun by armed gangs, and beset by crime, violence, corruption, and an overall atmosphere of quasi-dystopian misery. This is what Cueball refers to as “the decline of the city, and general social decay”. Counterfactuals Cueball mentions that this universe – that is, the 1985A Back to the Future timeline – would not have any counterfactuals to work with. This is often short, in epistemology , for counterfactual conditionals , that is, conditional statements about what would be true if something were true that we know for a fact is not true. Randall’s “ what if? ” series is based on counterfactuals, since it explores hypotheticals—conditionals which are contrary to fact. For example, the first “what if?” post, about what would happen if you tried to hit a baseball that was thrown at 90% the speed of light, is a counterfactual, because we know for a fact that a baseball has never been thrown at such a speed [ citation needed ] . In the case of the 1985A universe, they would not have any information on the counterfactuals , that is, the facts about what would happen if Biff did not have this almanac. Hillbilly Elegy Hillbilly Elegy: A Memoir of a Family and Culture in Crisis is a book, published in June 2016, that gives an account of growing up in a poor Rust Belt town, and gives a broader, probing look at the struggles of America’s white working class. This comic is a play on the title of this book, which has been described as explaining the “social, regional, and class” issues in white working-class America. The white American working class was a key factor in the election of U.S. President Donald Trump, and many critics have interpreted the book as an explanation of his election, which was deemed improbable by many analysts before it happened. Netflix had purchased the rights to an upcoming film adaptation of the book three days before this comic, prompting another wave of criticism of the book’s theories. Cueball is proposing a similarly-titled book, set in the Back to the Future II 1985A timeline, that would describe the supposed factors leading to the rise of Biff Tannen in Hill Valley. In that universe, while the rise of Biff—and the subsequent decay of the city—is the result of his using a future sports almanac to cheat at sports betting, the rest of the population would have to guess at the structural societal issues that might have caused Biff’s otherwise inexplicable success. Thus, Cueball compares such blind guessing with the analysis contained in Hillbilly Elegy . White Hat’s reaction This makes White Hat angry. This may be for various reasons: Relationship to political events Randall is known to have supported Hillary Clinton , the main opponent of Donald Trump, in the 2016 U.S. presidential election, having made a comic just to promote her and several Sad comics followed Trump’s election. This may add to explaining the comic in the following ways: The title text continues the comparison to the election situation by mentioning thinkpieces from newspapers that would appear in the Back to the Future II 1985A universe where Biff has taken over. Various thinkpieces did appear in real life newspapers in an attempt to explain Trump’s rise to power after his election, and asking whether it was inevitable. As Back to the Future II ’s important October 2015 setting date approached, commentators began noting the similarities between the older version of the character Biff Tannen and then presidential candidate Donald Trump. When the comparison was brought to the attention of the film’s writer, Bob Gale , in an interview, he claimed that elements of Tannen’s personality were actually based on Trump, who was already well known in the late 1980s for his work in real estate and tabloid controversies. Thus, there is a real connection between Biff Tannen and Donald Trump. This supports the comparison between the two made by Randall. That being said, actor Tom Wilson has denied that his performance of the role was in any way based on Trump. [Cueball talks while walking up behind White Hat, who is reading in an armchair.] Cueball: You know, in the universe where Biff Tannen took Marty McFly’s sports almanac back in time, the people wouldn’t have any counterfactuals to work with. Cueball: Their world would be the world. [In a frame-less panel White Hat turns his head to look at Cueball as he keeps talking.] Cueball: They would have spent decades debating which structural problems enabled the rise of BiffCo, the decline of the city, and general social decay. Cueball: Everyone would find reasons it confirmed their pet theory. [White Hat turns his head back to his book.] Cueball: I'm going to write a book set in that universe. I'll call it Hill Valley Elegy . White Hat: ... I hate you.

Modern OSI Model

Modern OSI Model

https://www.xkcd.com/2105

https://www.explainxkcd.com/wiki/index.php/2105:_Modern_OSI_Model

[A light gray shape that surrounds seven stacked dark gray rectangles centered above each other, all with labels. The light gray shape is connected but sometimes only on one side of the dark rectangles. It goes above and below the top and bottom rectangles. At the top there is a heading:] Modern OSI Model [The first black rectangle has two lines of text. It is supported by the light gray shape on both sides:] Application (Facebook) [Pulling the second rectangle out to the right would collapse the tower, with the top tipping to the right:] Presentation [Pulling the third rectangle out to the left would collapse the tower, with the top tipping to the left:] Session [The fourth rectangle is supported on both sides:] Transport [Pulling the fifth rectangle out to the left would collapse the tower making it tip to the left:] Network [Between the fifth and sixth dark rectangles is a label for the entire light gray shape:] Google & Amazon [The sixth rectangle is supported on both sides:] Data link [The seventh rectangle is supported on both sides:] Physical

The Open Systems Interconnection (OSI) Model is a conceptual model for network communications that defines 7 layers of functionality, where higher layers add increasing complexity to lower layers through associated protocols and standards. The 7 layers in the standard OSI Model are: In practice, the OSI model abstracts the communication between two end points, like a Facebook client and Facebook servers all the way from the application layer on the server, down to the wire on which the data is transmitted, and back up to the application layer where the user views the data. As Facebook is one of the most used websites in the world with more than a billion users, Randall claims that the "application" layer (what the client sees and uses) is mostly Facebook . A light gray shape labeled "Google & Amazon" surrounds all seven layers of the model in an irregular shape indicating that Google and Amazon, by dint of their size and dominance at multiple layers of the model influence the entire structure. An example of Google's influence would be their introduction of new protocols like QUIC and SPDY as replacements for the existing TCP protocol that was a foundation of the web, and their accompanying modifications of the original HTTP protocol. The significance of the irregular pattern of the "Google & Amazon" blob isn't clear. It is likely that it is in reference to the irregular way in which their modifications to the OSI stack have evolved. Potentially with extensions to the left representing the influence of Google, and extension to the right representing the influence of Amazon. However, it is also notable that the irregular structure of the stack is reminiscent of a Jenga tower. Jenga is a game in which blocks are removed from a vertical stack and added back to the top until the whole collapses. This may be a commentary on the instability of the network stack in general, or on how Google and Amazon's additions and changes to it have destabilized the networking protocols. Or, the specific blocks to be pulled out (presentation, session, and network) may be the ones whose removal collapses the tower while the other ones can be easily removed and replaced (like the center blocks in Jenga), implying that between Google and Amazon, even if these were pulled out, the tower would remain standing. What this says about the three layers that would destabilize the tower is unclear. The title text refers to Horcruxes used by Voldemort in the Harry Potter book series. A Horcrux is a magical artifact used to house a wizard's soul, preventing them from dying if their body is destroyed. Since they can only be created by murdering other people, they are heavily forbidden, and before Voldemort it was unheard of for a wizard to use more than one. Voldemort used seven -- the same number of layers in the OSI model. However, while Voldemort hid his seven Horcruxes in different places to make himself that much harder to kill, Randall's have all been collected in Google and Amazon, defeating the purpose of using more than one. Alternatively, transforming each layer of the OSI model into a horcrux may be regarded as a strategy to prevent them from being destroyed since doing so would destroy networking. This strategy would fail in the modern world, since some of the envisioned layers were not used in the more common modern TCP/IP networking model and in the case of cloud infrastructure potential exists to provide even more shortcuts. The title text may also be a reference to a prior comic about Randall mixing up things that come in groups of seven, like data layers and Horcruxes. [A light gray shape that surrounds seven stacked dark gray rectangles centered above each other, all with labels. The light gray shape is connected but sometimes only on one side of the dark rectangles. It goes above and below the top and bottom rectangles. At the top there is a heading:] Modern OSI Model [The first black rectangle has two lines of text. It is supported by the light gray shape on both sides:] Application (Facebook) [Pulling the second rectangle out to the right would collapse the tower, with the top tipping to the right:] Presentation [Pulling the third rectangle out to the left would collapse the tower, with the top tipping to the left:] Session [The fourth rectangle is supported on both sides:] Transport [Pulling the fifth rectangle out to the left would collapse the tower making it tip to the left:] Network [Between the fifth and sixth dark rectangles is a label for the entire light gray shape:] Google & Amazon [The sixth rectangle is supported on both sides:] Data link [The seventh rectangle is supported on both sides:] Physical

Sharing Options

Sharing Options

https://www.xkcd.com/2106

https://www.explainxkcd.com/wiki/index.php/2106:_Sharing_Options

[Cueball floating in midair is communicating with a small floating screen that resembles a smartphone. Other people and clouds visible floating by in background.] Screen: Welcome to social media! When you put stuff here, you have two options: (1) You can make it available to a small set of 300 or so approved friends. [Cueball is still floating and talking with the smartphone. Other people and clouds visible floating by in background.] Screen: Or (2) you can share permanent copies of it all with billions of people, including internet scammers, random predatory companies, and hostile governments. [In a frameless panel, Cueball has stopped moving and is facing the screen] Cueball: Why would anyone pick option two? Screen: Two is the default. Cueball: Yikes. [Cueball is still floating and talking with the smartphone. Other people and clouds visible floating by in background. Cueball has his hand raised] Cueball: So those are the only two options? There’s nothing in in between? Screen: I don’t understand. Like what? [Cueball continues floating and talking with the smartphone. Other people and clouds visible floating by in background.] Cueball: I mean...there are numbers between 300 and a billion. Screen: Huh? Name one. Screen: Pretty sure I would have heard of those.

Cueball is floating, talking to a screen that looks like a smartphone with a virtual assistant. Ponytail and other characters also fly in the background. The screen is explaining his options for sharing information on social media , he can make it available only to those he selects, or he can make it available to everyone, including various high risk groups. The drawing may represent a Virtual Reality cyberspace. The comic might be set in the distant future, where VR will have become commonplace and be embraced by Cueball and his friends. This cyberspace may be the social network’s cyberspace where everyone interacts. The clouds could represent the cloud server where the data of the social network is stored. The virtual assistant seems to have a face and have very advanced AI, which can even be arrogant by assuming that it already knew the information about the “option in between”. Many social media sites allow users to control who can see content (posts, pictures, etc.) that users share. Several high profile social media sites have sparked controversy by automatically widely sharing user data, unless the user restricts access. The settings for controlling the sharing of data are not always obvious to the user, or easy to use. Access may be limited to immediate friends, or be available to all users (public); some platforms allow intermediate levels of control. As most social media sites are free to use, the business model for these companies involves a mixture of selling advertising space on their website and selling data on its users. Targeted advertising takes data on users’ past behavior and things that they have liked, and uses this to predict what adverts they may be interested in or be most vulnerable to. Targeted adverts are more valuable to advertisers as they avoid paying to show adverts to individuals who are unlikely to be interested in their products; but can lead to users feeling that they are being spied on. While the terms and conditions for social media websites will include details of how data will be used, the length of these documents and legal terminology may deter users from reading them, meaning that they may be unaware that their data is being exploited in this way. Regulation has been slow to catch up with changing online trends; however, the European Union have recently introduced General Data Protection Regulations (GDPR) which aims to regulate how user data can be shared. GDPR was featured in comic 1998: GDPR . Data from social media may be used for marketing, for law enforcement, mass surveillance and social control, for investigative journalism, for criminal activity, confidence games , among other things. Internet scammers use online information to manipulate people, often to commit fraud. They may acquire personal data using web crawlers to automatically scan social networks for personal information (particularly emails) to scam their owners. Those bots called web crawlers can get the information without scammers' manual browsing of the victims' profile. Those people who set their social network account as public (the 2nd option in the comic) are more likely victims of scammers since they can access their profiles without being the victim's friend or follower. Other examples of questionable uses for social media on xkcd include 300: Facebook . Randall is making a point that there ought to be some option between sharing posts only with your friends and making them completely public. The title text shows that he would specifically like to know when corporations read regular peoples' posts. This also could be a stab at the sharing policies between Facebook and the just-announced end of Google+. Google+ allowed users to create multiple groups called 'circles'. Posts could then be shared by targeting specific circles. For example: "I'm in the hospital" could be shared with just the family circle, but the "I got a promotion" could be shared with the family circle, the co-workers circle, and the general public circle. Facebook provides an option to share with “friends of friends,” leaving the decision about how widely a post is shared not with the posts creator, but with the posts recipients. The comic is set in the future of VR, yet the fact that Internet companies like Facebook, Tencent and Twitter try hard to collect and sell user data won't change. This may suggests that Randall believe those companies will never reconsider their approach regarding user privacy. [Cueball floating in midair is communicating with a small floating screen that resembles a smartphone. Other people and clouds visible floating by in background.] Screen: Welcome to social media! When you put stuff here, you have two options: (1) You can make it available to a small set of 300 or so approved friends. [Cueball is still floating and talking with the smartphone. Other people and clouds visible floating by in background.] Screen: Or (2) you can share permanent copies of it all with billions of people, including internet scammers, random predatory companies, and hostile governments. [In a frameless panel, Cueball has stopped moving and is facing the screen] Cueball: Why would anyone pick option two? Screen: Two is the default. Cueball: Yikes. [Cueball is still floating and talking with the smartphone. Other people and clouds visible floating by in background. Cueball has his hand raised] Cueball: So those are the only two options? There’s nothing in in between? Screen: I don’t understand. Like what? [Cueball continues floating and talking with the smartphone. Other people and clouds visible floating by in background.] Cueball: I mean...there are numbers between 300 and a billion. Screen: Huh? Name one. Screen: Pretty sure I would have heard of those.

Launch Risk

Launch Risk

https://www.xkcd.com/2107

https://www.explainxkcd.com/wiki/index.php/2107:_Launch_Risk

[A large spaceship rocket is standing on it's launchpad, just decoupled from the tower that supports it ready for launch. At the very top of the rocket where the astronauts are sitting there are two lines coming out, indicating the speak from the two astronauts inside the rocket. Next to the top of the rocket there is a speech bubble drawn with jagged line indicating sound from a loudspeaker. It is the countdown to the launch.] Astronaut 1: How you feeling? Astronaut 2: Honestly, pretty nervous. Astronaut 1: I know it seems dangerous, but just remember: you're more likely to be struck by lightning than to be selected to become an astronaut. Astronaut 2: Oh that's a good- Astronaut 2: ...Wait. Countdown: T-Minus 20...19...

This comic deals with the faulty application of general statistics based on a large population, such as all Americans, to specific situations with vastly different statistics, such as astronauts. A manned rocket ship is about to be launched into space. Mission control counts down from "T-minus 20," where "T" stands for the time at which the rocket is scheduled to launch. In the capsule, one astronaut asks another how they are feeling. The second admits that they are nervous. The first one offers a supposedly reassuring observation that they are more likely to be struck by lightning than to be selected to become an astronaut. Such comparisons are commonly used to illustrate that a particular probability is very small, and therefore not worth worrying about. The second astronaut is about to agree that they have a good point, but then realizes the problem with their argument: the likelihood of being selected as an astronaut is a moot point, because they both already are astronauts. The comparison ignores the relevant concern, which is the danger involved in being an astronaut and launching into space. The second astronaut's nervousness is understandable as space missions are historically quite dangerous, and have numerous avenues for potentially fatal failure, certainly far beyond the minuscule risk of being struck by lightning, approximately 1 in 14,600 throughout your entire life . The title text creates additional confusion by referencing another common statistical reference point, the probability of dying in a shark attack. In addition to shark attacks being uncommon, they are also less likely to kill their victim than is commonly assumed. Still, while shark attacks are more frequently fatal than rocket launches, this comparison is once again useless, as the astronaut is not in any danger of sharks, but is literal seconds from launching into space. The astronaut is presumably not especially reassured by the "pretty high" survival rate. Of the 557 people who who have been in Earth orbit, 18 (3%) have died in related accidents, not specifically at launch ( List of spaceflight-related accidents and incidents , Astronaut/Cosmonaut Statistics ). Of the 93 incidents logged for 2018 in the Global Shark Attack File , 4 (4.3%) were fatal, but the statistic has been higher in the past when there was likely less education against provoking sharks. A large metal rocket, such as depicted would be more likely to be struck by lightning than nearby structures. However launch controllers generally monitor weather carefully to reduce the chances of attempting to launch when lightning is likely. A spacecraft launch can also trigger lightning, by creating a conductive path through electrically charged clouds. Apollo 12 was struck by lightning twice during the launch phase. Thankfully backup systems allowed the flight to proceed. For more information, see NASA: Lightning and Launches The perceived value of risk is a recurring topic and is also featured in 795: Conditional Risk and 1252: Increased Risk . [A large spaceship rocket is standing on it's launchpad, just decoupled from the tower that supports it ready for launch. At the very top of the rocket where the astronauts are sitting there are two lines coming out, indicating the speak from the two astronauts inside the rocket. Next to the top of the rocket there is a speech bubble drawn with jagged line indicating sound from a loudspeaker. It is the countdown to the launch.] Astronaut 1: How you feeling? Astronaut 2: Honestly, pretty nervous. Astronaut 1: I know it seems dangerous, but just remember: you're more likely to be struck by lightning than to be selected to become an astronaut. Astronaut 2: Oh that's a good- Astronaut 2: ...Wait. Countdown: T-Minus 20...19...

Carbonated Beverage Language Map

Carbonated Beverage Language Map

https://www.xkcd.com/2108

https://www.explainxkcd.com/wiki/index.php/2108:_Carbonated_Beverage_Language_Map

[A map of the United States divided into purple, red, green, blue, and yellow colored regions.] [A purple area in North West Washington.] Fanta [A blue area spanning the Western border of Washington and Oregon.] Söde [A yellow area spanning the remainder of Washington, North Western Oregon, Northern Idaho and the North Western corner of Montana.] Ichor [A green area spanning the North Eastern corner of Oregon, central Idaho and the majority of Montana.] Spicewater [A blue area spanning Eastern Montana, the North Eastern corner of Wyoming and the majority of North and South Dakota.] Refill [A red area spanning Eastern North and South Dakota, the majority of Minnesota, Northern Wisconsin and Michigan North of the lakes.] Mead [A green area spanning the border between Minnesota and Wisconsin.] Canadian Ale [A yellow area spanning the South Eastern corner of Minnesota, the North Eastern corner of Iowa and the majority of Wisconsin.] Aether [A green area in North East Wisconsin.] Mouthwater [A purple area covering most of Michigan south of the lakes.] Kid's coffee [A red area covering Northeast & central New York.] Hydro [A green area covering Vermont and spanning the border with New York.] [No word for them] [A yellow area covering Maine and the majority of New Hampshire.] Sugar milk [A red area spanning Eastern Massachusetts and the border with New Hampshire.] Harvard tea [A blue area covering Rhode Island and spanning Eastern Connecticut, central Massachusetts and the South West corner of New Hampshire.] Bubbler [A yellow area spanning the South Eastern corner of New York, the South Western corner of Massachusetts, Western Connecticut and Northern New Jersey.] Mouth Buzz [A red area spanning North Eastern California, Southern Oregon, the South Western corner of Idaho and the majority of Nevada.] You-know-what [A blue area spanning South Western Idaho, Eastern Nevada, the majority of Utah and the border of Utah and Arizona.] Softie [A green area spanning Northern Utah and the majority of Colorado.] Punch [A yellow area covering the majority of Wyoming.] Fizz ooze [A purple area spanning the South Eastern corner of Wyoming, the North Eastern corner of Colorado, the North Western corner of Kansas, Southern South Dakota, the majority of Nebraska and Iowa, and Northern Missouri.] Tickle juice [A blue area spanning Eastern Iowa, Southern Wisconsin, the majority of Illinois and Indiana, the Southern border of Michigan, the Western border of Ohio and North Western Kentucky.] Capri [A green area spanning South Eastern Michigan, the majority of Ohio and Pennsylvania, South Western New York, Northern West Virginia and Western Maryland.] Medicine [A purple area spanning Eastern Pennsylvania and Southern New Jersey.] Brad's Elixir [A red area spanning the South Eastern corner of Pennsylvania, Eastern Maryland, Delaware and Northern Virginia.] Hot Water [A yellow area spanning Eastern Kentucky, the Southern border of Ohio, Southern West Virginia, the majority of Virginia and Northern North Carolina.] Broth [A blue area in Western California, North of San Francisco.] True water [A yellow area in Western California, South of San Francisco.] Crypto [A green area in South Western California, North of Los Angeles.] Yum [A blue area in South Western California, close to Los Angeles.] Sparkle fluid [A purple area in South Western California, close to San Diego.] King cola [A yellow area spanning South Eastern California, Southern Nevada and the North Western corner of Arizona.] Tab [A green area spanning the South Eastern corner of California and the majority of Arizona.] Ohio tea [A red area spanning Eastern Arizona, the majority of New Mexico, Southern Colorado and the border between New Mexico and Texas.] Fun wine [A blue area spanning Northern Texas, South Western Kansas and the majority of Oklahoma.] Sugar oil [A red area spanning Central and Eastern Kansas, Southern Nebraska, Central Missouri and South Western Illinois.] Bubble Honey [A yellow area spanning Southern New Mexico and Western Texas.] Diet [A blue area in Southern Texas.] Code red [A green area spanning the majority of Texas and the Southern border of Oklahoma.] The wet drink [A purple area spanning Eastern Texas, the South Eastern corner of Oklahoma, the majority of Arkansas, Southern Missouri and Western Louisiana.] Carbonated beverage [A yellow area spanning Eastern Louisiana, Eastern Arkansas, Southern Missouri, the South Western corner of Tennessee, the majority of Mississippi and the South Western corner of Alabama.] Skim shake [A green area spanning the majority of Tennessee, Southern Kentucky, Northern Alabama, Northern Georgia and Western North Carolina.] Regular [A purple area covering the majority of North Carolina.] Fluid [A red area spanning Eastern Mississippi, Central Alabama, Northern Georgia and the South Western border of South Carolina.] Tang [A yellow area covering the majority of South Carolina.] Coke zero [A blue area in Central Georgia.] Fool's Champagne [A purple ares spanning Southern Alabama, Southern Georgia and Northern Florida.] Formula [A yellow area in Eastern Florida, near Orlando.] Carbo [A blue area in Western Florida, near Tampa.] Quicksilver [A red area in Southern Florida, South of Tampa and Orlando.] Glug [A green area in Southern Florida, near Miami.] Water plus [A yellow area corresponding to Hawaii except for the island of O'ahu.] Pepsi [A red area corresponding to the Hawaiian island of O'ahu.] Crystal Pepsi [A blue area covering the majority of Alaska.] Boat drink [A red area in Southern Alaska, near Anchorage.] Melt In the original version of this comic "elixir" was misspelled as "elixer", however this was later corrected.

In the US, people in various parts of the country refer to carbonated beverages by different names such as "soda", "pop", "coke", and others. Generally, the West Coast and Northeast say "soda", the South says "coke" and the rest of the country says "pop". There are various maps of where these different names are used, including popvssoda.com and this map on Laughing Squid . Such maps were trending and popular in 2013. xkcd's map is a satire of those maps – these regional terms are fake. Not only are there far more terms than are actually used by Americans, many are terms for other beverages (mead), unrelated liquids (quicksilver), or trademarked beverage names less popular than Coke / Coca Cola ( Code Red ) – and in one case, something that's not even tangible ( "Crypto" ). [A map of the United States divided into purple, red, green, blue, and yellow colored regions.] [A purple area in North West Washington.] Fanta [A blue area spanning the Western border of Washington and Oregon.] Söde [A yellow area spanning the remainder of Washington, North Western Oregon, Northern Idaho and the North Western corner of Montana.] Ichor [A green area spanning the North Eastern corner of Oregon, central Idaho and the majority of Montana.] Spicewater [A blue area spanning Eastern Montana, the North Eastern corner of Wyoming and the majority of North and South Dakota.] Refill [A red area spanning Eastern North and South Dakota, the majority of Minnesota, Northern Wisconsin and Michigan North of the lakes.] Mead [A green area spanning the border between Minnesota and Wisconsin.] Canadian Ale [A yellow area spanning the South Eastern corner of Minnesota, the North Eastern corner of Iowa and the majority of Wisconsin.] Aether [A green area in North East Wisconsin.] Mouthwater [A purple area covering most of Michigan south of the lakes.] Kid's coffee [A red area covering Northeast & central New York.] Hydro [A green area covering Vermont and spanning the border with New York.] [No word for them] [A yellow area covering Maine and the majority of New Hampshire.] Sugar milk [A red area spanning Eastern Massachusetts and the border with New Hampshire.] Harvard tea [A blue area covering Rhode Island and spanning Eastern Connecticut, central Massachusetts and the South West corner of New Hampshire.] Bubbler [A yellow area spanning the South Eastern corner of New York, the South Western corner of Massachusetts, Western Connecticut and Northern New Jersey.] Mouth Buzz [A red area spanning North Eastern California, Southern Oregon, the South Western corner of Idaho and the majority of Nevada.] You-know-what [A blue area spanning South Western Idaho, Eastern Nevada, the majority of Utah and the border of Utah and Arizona.] Softie [A green area spanning Northern Utah and the majority of Colorado.] Punch [A yellow area covering the majority of Wyoming.] Fizz ooze [A purple area spanning the South Eastern corner of Wyoming, the North Eastern corner of Colorado, the North Western corner of Kansas, Southern South Dakota, the majority of Nebraska and Iowa, and Northern Missouri.] Tickle juice [A blue area spanning Eastern Iowa, Southern Wisconsin, the majority of Illinois and Indiana, the Southern border of Michigan, the Western border of Ohio and North Western Kentucky.] Capri [A green area spanning South Eastern Michigan, the majority of Ohio and Pennsylvania, South Western New York, Northern West Virginia and Western Maryland.] Medicine [A purple area spanning Eastern Pennsylvania and Southern New Jersey.] Brad's Elixir [A red area spanning the South Eastern corner of Pennsylvania, Eastern Maryland, Delaware and Northern Virginia.] Hot Water [A yellow area spanning Eastern Kentucky, the Southern border of Ohio, Southern West Virginia, the majority of Virginia and Northern North Carolina.] Broth [A blue area in Western California, North of San Francisco.] True water [A yellow area in Western California, South of San Francisco.] Crypto [A green area in South Western California, North of Los Angeles.] Yum [A blue area in South Western California, close to Los Angeles.] Sparkle fluid [A purple area in South Western California, close to San Diego.] King cola [A yellow area spanning South Eastern California, Southern Nevada and the North Western corner of Arizona.] Tab [A green area spanning the South Eastern corner of California and the majority of Arizona.] Ohio tea [A red area spanning Eastern Arizona, the majority of New Mexico, Southern Colorado and the border between New Mexico and Texas.] Fun wine [A blue area spanning Northern Texas, South Western Kansas and the majority of Oklahoma.] Sugar oil [A red area spanning Central and Eastern Kansas, Southern Nebraska, Central Missouri and South Western Illinois.] Bubble Honey [A yellow area spanning Southern New Mexico and Western Texas.] Diet [A blue area in Southern Texas.] Code red [A green area spanning the majority of Texas and the Southern border of Oklahoma.] The wet drink [A purple area spanning Eastern Texas, the South Eastern corner of Oklahoma, the majority of Arkansas, Southern Missouri and Western Louisiana.] Carbonated beverage [A yellow area spanning Eastern Louisiana, Eastern Arkansas, Southern Missouri, the South Western corner of Tennessee, the majority of Mississippi and the South Western corner of Alabama.] Skim shake [A green area spanning the majority of Tennessee, Southern Kentucky, Northern Alabama, Northern Georgia and Western North Carolina.] Regular [A purple area covering the majority of North Carolina.] Fluid [A red area spanning Eastern Mississippi, Central Alabama, Northern Georgia and the South Western border of South Carolina.] Tang [A yellow area covering the majority of South Carolina.] Coke zero [A blue area in Central Georgia.] Fool's Champagne [A purple ares spanning Southern Alabama, Southern Georgia and Northern Florida.] Formula [A yellow area in Eastern Florida, near Orlando.] Carbo [A blue area in Western Florida, near Tampa.] Quicksilver [A red area in Southern Florida, South of Tampa and Orlando.] Glug [A green area in Southern Florida, near Miami.] Water plus [A yellow area corresponding to Hawaii except for the island of O'ahu.] Pepsi [A red area corresponding to the Hawaiian island of O'ahu.] Crystal Pepsi [A blue area covering the majority of Alaska.] Boat drink [A red area in Southern Alaska, near Anchorage.] Melt In the original version of this comic "elixir" was misspelled as "elixer", however this was later corrected.

Invisible Formatting

Invisible Formatting

https://www.xkcd.com/2109

https://www.explainxkcd.com/wiki/index.php/2109:_Invisible_Formatting

[A text editor, with some options. They are superscript in one section, bold, italic and underscore in another section and alignments in the third section. The word "not ", including the following space, is highlighted in blue. There is a cursor below it.] Text: ...ere, but would not have to mo... Action: Select [The cursor is on the "bold" option and the selected word is bolded.] Text: ...ere, but would not have to mo... Action: Click [The cursor is next to the "to". No text is highlighted.] Thought bubble: ...Nah, the bold is too much. Text: ...ere, but would not have to mo... [The word "not" is now highlighted in blue again, but the following space is not.] Text: ...ere, but would not have to mo... Action: Select [The cursor is on the "bold" option and the selected word is not bolded.] Text: ...ere, but would not have to mo... Action: Click [The cursor and the blue highlighting are gone. The space after "not" has a dashed box around it, and an arrow points to it.] Text: ...ere, but would not have to mo... Arrow: Hidden bold space [Caption below the panels:] When editing text, in the back of my mind I always worry that I'm adding invisible formatting that will somehow cause a problem in the distant future. There are also other occasions where a hidden bold space may be a problem for later editors etc. These include: Popular modern word processing programs have features which may make it easier to notice improperly formatted invisible characters. In the tutorials linked here, one may learn how to view invisible characters in Microsoft Word , Pages and LibreOffice Writer , however even with this on it would be difficult to spot a bolded space (which looks like a bolded dot – now visible but so small it's still hard to tell if it's bold or not). In the older word processor WordPerfect , one could do this with the “Reveal Codes” feature, which showed you character codes, separate from the characters themselves, around the characters. For example, a bolded space would look something like " [BOLD≻ ≺BOLD] ". Web sites which allow content to be edited by users but generate the formatting code automatically often have versions of the invisible formatting problem; for example, eBay listings which use anything other than the default font rapidly accumulate hard spaces, font end and begin transitions, and other invisible formatting if they are subsequently edited, which can slow page loading and cause other problems. This is also seen in blogs etc.

In various word processor programs, when highlighting text, whether by clicking-and-dragging or double-clicking, it is easy to highlight characters which have no visible effects when markup is applied (ie italics or bold ), such as a space or the end-of-paragraph passage. Since in most fonts the word space looks identical between the bold, the italicized, and the regular, this has no effect on how the end user will read the document, but could theoretically cause a problem in certain occasions, most notably in computers which might parse a bold space differently or incorrectly. This problem is compounded if the text cursor does not indicate clearly the space is in bold or italics when a user hovers their mouse over it. Randall worries about this. In the pictured case, Randall does not appear to have selected the word by double-clicking, since the cursor is depicted past the end of the word instead of on top of it; rather, he has clicked-and-dragged the mouse cursor to select it. The space character is a relatively thin character, which makes it hard to avoid and to notice, but even so most people don’t worry if they've selected it and tend not to bother fixing. Randall later uses the same click-and-drag method to have the bold removed, but this time omits the space, retaining its bold formatting on that character. Since it is a blank character, there is no easy way to tell it is still bold — even if it is slightly longer in the bold font, this may be hard to notice. This is the situation the comic is highlighting, no pun intended . Usually, if one were to highlight a word via double-clicking, the word and the space following would both become highlighted. Therefore, this problem could have been avoided if Randall had used this method to highlight, as the space would have been automatically included both times, thus removing markup on the space character as well. Though Randall is likely thinking of computer-related problems caused by his invisible formatting, there is also a chance that his bold space would cause other, non-computer-related issues. As Randall has bolded the word "not" but then changed his mind, it indicates that he believes writing not is too strongly-worded. With an invisible bold space, whoever the document was intended for could notice Randall's bold space and figure that the word "not" was originally bolded. Depending on the context, a bolded "not" could be enough to change the tone of the text from polite and formal to dismissive (eg. "We believe you are not suitable for this position." vs "We believe you are not suitable for this position.") In the title text, Randall says that he “fixes” this by running the text through OCR , which turns physical copies or images into text. Although this would "fix" the invisible formatting (since the OCR is unable to detect it), this would usually ruin even more formatting, and add inaccuracies to the text. This way, no one can tell which bugs were introduced by him and which ones by the OCR, which he facetiously suggests is better somehow. As the title text explains, Randall finds it very important to control all information he publishes. Real-world examples are governments changing the impact of reports for political reasons. Attempted tampering of this kind can be revealed by bold spaces. Another example would be a casual and short one-sentence reply e.g. to a romantic interest, which one takes one hour to formulate to sound as natural as possible. There are also other occasions where a hidden bold space may be a problem for later editors (see the Trivia section below). Randall’s background in computer programming could also make him more attentive to these types of technical problems, and therefore add this as a reason for his worries about invisible formating. [A text editor, with some options. They are superscript in one section, bold, italic and underscore in another section and alignments in the third section. The word "not ", including the following space, is highlighted in blue. There is a cursor below it.] Text: ...ere, but would not have to mo... Action: Select [The cursor is on the "bold" option and the selected word is bolded.] Text: ...ere, but would not have to mo... Action: Click [The cursor is next to the "to". No text is highlighted.] Thought bubble: ...Nah, the bold is too much. Text: ...ere, but would not have to mo... [The word "not" is now highlighted in blue again, but the following space is not.] Text: ...ere, but would not have to mo... Action: Select [The cursor is on the "bold" option and the selected word is not bolded.] Text: ...ere, but would not have to mo... Action: Click [The cursor and the blue highlighting are gone. The space after "not" has a dashed box around it, and an arrow points to it.] Text: ...ere, but would not have to mo... Arrow: Hidden bold space [Caption below the panels:] When editing text, in the back of my mind I always worry that I'm adding invisible formatting that will somehow cause a problem in the distant future. There are also other occasions where a hidden bold space may be a problem for later editors etc. These include: Popular modern word processing programs have features which may make it easier to notice improperly formatted invisible characters. In the tutorials linked here, one may learn how to view invisible characters in Microsoft Word , Pages and LibreOffice Writer , however even with this on it would be difficult to spot a bolded space (which looks like a bolded dot – now visible but so small it's still hard to tell if it's bold or not). In the older word processor WordPerfect , one could do this with the “Reveal Codes” feature, which showed you character codes, separate from the characters themselves, around the characters. For example, a bolded space would look something like " [BOLD≻ ≺BOLD] ". Web sites which allow content to be edited by users but generate the formatting code automatically often have versions of the invisible formatting problem; for example, eBay listings which use anything other than the default font rapidly accumulate hard spaces, font end and begin transitions, and other invisible formatting if they are subsequently edited, which can slow page loading and cause other problems. This is also seen in blogs etc.

Error Bars

Error Bars

https://www.xkcd.com/2110

https://www.explainxkcd.com/wiki/index.php/2110:_Error_Bars

[A line graph with eight marks on the Y-axis and five marks on the X-axis. The graph has four points represented by dots and connected by three lines between them. Each dot has error bars coming out of the top and bottom of it. The horizontal line delineating the end of each error bar has another set of smaller error bars attached to it. These second error bars in turn have a still smaller third set of error bars attached to the end of them. There is a final fourth set of very small error bars attached to the third set, for a total of 56 error bars] [Caption below the panel:] I don't know how to propagate error correctly, so I just put error bars on all my error bars.

On statistical charts and graphs, it is common to include error bars showing the probable variation of the actual value from the value shown (or the possible error of the value shown). Since there is always uncertainty in any given measurement, the error bars help an observer evaluate how accurate the data shown is, or the implications if the true value is within the likely error, rather than the exact value shown. There are statistical methods for calculating error bars (they can show a standard deviation , a standard error , or a confidence interval ) but the fact that there are multiple ways of calculating them - plus general unfamiliarity with statistical methods - means that people often misinterpret or misunderstand them. As charts may be of data that has been mathematically processed, the known error from the recording process must also be mathematically processed in order to determine the likely error in the final result - a process called propagation of error. Different transformations of the data result in different transformations of the error, and the correctness of the transformations used can sometimes depend on the subtle differences in the distribution of the source data. At a loss as to how to correctly propagate all the possible sources of error, Randall instead puts error bars on the ends of his error bars to reflect his uncertainty in the original error bars. However, since his second error bar calculations are also suspect, he puts a third set of error bars on them. This repeats ad infinitum (though only four levels are drawn), creating a fractal-like object. In the title text, he says that the effect size of some variable being calculated is 1.68 and follows it with a 95% confidence interval, or CI (a range of possible values which, under repeated sampling, would contain a number within the interval 95% of the time), which would normally be represented by something like "1.68 (95% CI 1.56 - 1.80)." Since he is stating that those bounds are uncertain, he starts with "1.68 (95% CI 1.56" but then puts the 95% CI for that lower bound of the interval, "95% CI 1.52," followed by the lower bound for that value, "95% CI 1.504," and so on. He goes 11 layers deep before resorting to an ellipsis. In real life, there is not enough data to compute an error bar on error bars. The data being measured have a sampling distribution, e.g. one might make ten measurements of something which come out to 1, 1, 1.1, 1, 1.4, 1, 1, 0.5, 1, and 1, suggesting it is probably close to 1, so there is a range of values that could likely be. However, properties such as the average and standard deviation do not themselves typically have ranges. If one is uncertain that one has computed these correctly, there is not enough data to compute one's own uncertainty in one's skills in any meaningful way; one can claim error bars on error bars, as in this example, but those are just guesses with no statistically useful backing. One way to make the nested error bars valid might be (if one had the time and money) to run the entire experiment ten times, calculating sigmas each time; then there would be a valid (although not necessarily useful) sigma on the sigmas. Then one would have to run the set of ten runs ten times for the next "level" of sigmas, etc. The difficulty of doing this entire process, especially when considering that Randall is only nesting error bars out of ignorance, makes this comic all the more absurd. [A line graph with eight marks on the Y-axis and five marks on the X-axis. The graph has four points represented by dots and connected by three lines between them. Each dot has error bars coming out of the top and bottom of it. The horizontal line delineating the end of each error bar has another set of smaller error bars attached to it. These second error bars in turn have a still smaller third set of error bars attached to the end of them. There is a final fourth set of very small error bars attached to the third set, for a total of 56 error bars] [Caption below the panel:] I don't know how to propagate error correctly, so I just put error bars on all my error bars.

Opportunity Rover

Opportunity Rover

https://www.xkcd.com/2111

https://www.explainxkcd.com/wiki/index.php/2111:_Opportunity_Rover

[White Hat is watching while Science Girl and Cueball in the background hold their smartphones up to use them as cameras. A narrator (Randall) comments with text above them:] Narrator: Some people complain that we see the world through our cameras. White Hat: Kids these days... [Cueball points to the left with his hand while shouting and holding his other hand up near his mouth. Again there is narrating text, both above and below this time.] Narrator: But for me, the really exciting part of finding something new Cueball: Wow, you gotta come see this! Narrator: has always been showing it to others. [A black panel shows a space probe approaching a planet. White narrating text is above and below.] Exploring an entire new world would already be the adventure of a lifetime. Imagine having the chance to share every new sight [A queue of seven people is seen following a rover driving in front of them on a rock filled landscape. Its track is shown behind it. The people do not leave foot prints though. The rover speaks. At the top of the panel there is a last narrating text inside a small box across the top of the panel. The seven people are Cueball, Science Girl, Hairy (looking back), another Cueball holding his hand to his chin, Ponytail and finally Megan, who points forward.] Narrator: with seven billion friends. Rover: ...and here's a trench I dug with my wheel, and here's where a dust devil went right past me, and over there is the biggest cliff I've ever seen, and this is...

This comic is a tribute to the Opportunity rover and its nearly 15 year mission in which it sent back publicly available photos and research from Mars to Earth. The evening prior to this comic uploading (Feb 12, 2019), Nasa's JPL sent their final data request to the rover, in hopes that it would respond. When it did not, the rover was declared to be officially lost. The comic starts with White Hat, looking at some people taking photographs and lamenting the fact that they're taking pictures all the time, saying "Kids these days...", a common complaint of younger people by their elders. This could be considered a Straw man argument, as White Hat is lamenting that the younger generation look at the world through their camera phones and thus don't experience it directly, and believe that they lose some of the joy of the event in the process - an opinion he has expressed previously in 1314: Photos . To this Randall appears to counter that sharing and showing to others is an exciting part of the joy, an opinion which he also expressed as Cueball in 1314: Photos . He then proceeds to say that the Opportunity of exploring a completely new world is an exciting part of the exploration, and expresses joy in the fact that MER-B Opportunity was able to share its experiences in its 15-year, 45-kilometer journey on Mars with the entirety of humanity. The comic ends by thanking the Opportunity rover (and NASA) for allowing the general public the incredible experiences it had on Mars in its 15 Earth-year lifetime, to receive the pictures and data, while traversing along hostile terrain for us. The last panel shows some "followers" which represents everyone on Earth listening to the words from the rover as it transmits the incredible experiences it had on Mars in its 15 Earth-year lifetime. Note, perhaps the reference to "dust devil" suggests these may have been the last such descriptions as that may refer to the deadly global dust storm that likely killed the rover and ended the mission. The dust-devils were also likely responsible for the amazing extended missions for both rovers as they tended to blow the accumulated dust off the solar panels. The title text shows gratitude for the rover, which brought everyone on Earth, including Randall along in its journey by sending images of the journey to Earth. Also, Randall used to work for NASA, so as much joy as it brought the world at large, it probably felt just a little more personal for him. The Opportunity rover also appeared in 1504: Opportunity , while its twin rover Spirit also had a dedicated comic in 695: Spirit . [White Hat is watching while Science Girl and Cueball in the background hold their smartphones up to use them as cameras. A narrator (Randall) comments with text above them:] Narrator: Some people complain that we see the world through our cameras. White Hat: Kids these days... [Cueball points to the left with his hand while shouting and holding his other hand up near his mouth. Again there is narrating text, both above and below this time.] Narrator: But for me, the really exciting part of finding something new Cueball: Wow, you gotta come see this! Narrator: has always been showing it to others. [A black panel shows a space probe approaching a planet. White narrating text is above and below.] Exploring an entire new world would already be the adventure of a lifetime. Imagine having the chance to share every new sight [A queue of seven people is seen following a rover driving in front of them on a rock filled landscape. Its track is shown behind it. The people do not leave foot prints though. The rover speaks. At the top of the panel there is a last narrating text inside a small box across the top of the panel. The seven people are Cueball, Science Girl, Hairy (looking back), another Cueball holding his hand to his chin, Ponytail and finally Megan, who points forward.] Narrator: with seven billion friends. Rover: ...and here's a trench I dug with my wheel, and here's where a dust devil went right past me, and over there is the biggest cliff I've ever seen, and this is...

Night Shift

Night Shift

https://www.xkcd.com/2112

https://www.explainxkcd.com/wiki/index.php/2112:_Night_Shift

[Comments with peoples' profile pictures in front of them are shown in white comment boxes on a gray background.] Cueball: The Atlantic Ocean is big Ponytail: The Pacific is even bigger Cueball With Full Body Profile Picture (WFBPP): They're both very big Megan: A lot of people have TVs Hairbun: Some people don't Megan: Yeah, that's true Cueball: 24 isn't a prime number Cueball WFBPP: Neither is 25 Hairbun: Have you ever been to Colorado? Megan: No Cueball WFBPP: No Cueball: Yeah Ponytail: No [Caption below the panel:] My phone has a night shift mode to help me sleep, but instead of reducing the intensity of blue light, it reduces the intensity of opinions.

Many electronic devices have settings to adjust display color and intensity. " Night shift ," or similar modes make the display less blue. This may be useful in the evening, since blue light interferes with melatonin, the hormone which regulates the sleep cycle. Exposure to intense blue light in the evening can interfere with becoming sleepy. This comic re-imagines such a mode as influencing the content of messages to encourage sleepiness—or, at least, to dampen the emotional response that might keep someone up too late at night . In the title text, the reverse has occurred. By setting his white balance incorrectly, the opinions that Randall is reading are more intense, even about "simple" things as having visited Colorado or not (instead of his phone display merely becoming too bluish). This may be a play on angry white male , or similar, which is also characterized by violent expressions of views, and uses the word white. Randall might have meant brightness instead of white balance, with the idea that increasing the amount of light coming from the screen also increases the vehemence of the posts. This strip then references the fact that on the internet, very few people answer in the singulars of 'Yes' or 'No' or another equally short and definable answer. This may be because there is little perceived value in such a short but factual answer, when you have the opportunity to voice your opinion, sometimes at length. Also in many cultures indirect expression is the norm, or polite; a short direct answer is considered less acceptable, especially in the negative. [Comments with peoples' profile pictures in front of them are shown in white comment boxes on a gray background.] Cueball: The Atlantic Ocean is big Ponytail: The Pacific is even bigger Cueball With Full Body Profile Picture (WFBPP): They're both very big Megan: A lot of people have TVs Hairbun: Some people don't Megan: Yeah, that's true Cueball: 24 isn't a prime number Cueball WFBPP: Neither is 25 Hairbun: Have you ever been to Colorado? Megan: No Cueball WFBPP: No Cueball: Yeah Ponytail: No [Caption below the panel:] My phone has a night shift mode to help me sleep, but instead of reducing the intensity of blue light, it reduces the intensity of opinions.

Physics Suppression

Physics Suppression

https://www.xkcd.com/2113

https://www.explainxkcd.com/wiki/index.php/2113:_Physics_Suppression

[White Hat, with his hands balled into fist and held up above him, is talking with Megan.] White Hat: You physicists are suppressing my theory because it's inconvenient for your models! Megan: Wait, we have a mafia that can suppress annoying results? Megan: Why didn't they do something about the dark energy people?! Megan: We gave them a Nobel prize but I'm still mad at them!

White Hat is mad at physicists in general and directs his fury at Megan , a physicist. He has a theory and blames physicists for suppressing it. He believes that no one takes it seriously because his theory would disrupt the standard model in physics. Megan is not taking him seriously and instead states that she did not know that physicists had a Mafia that was able to suppress anyone from publishing annoying results. She continues that if such a group were there to do so, then why were they not there to stop the people who published results about dark energy? The Mafia is a criminal organization famous for their use of force to get their way, and while White Hat didn't mention the Mafia, Megan is facetious in her mentioning them because they would be an extreme example of a group that could do what White Hat seems to think is being done. She acknowledges that the "dark energy people" were awarded a Nobel Prize (in 2011 ), but she's still mad at them for the "trouble" this new concept caused for other physicists, including her. Dark energy is an unknown form of energy which is hypothesized to permeate all of space, tending to accelerate the expansion of the universe. It should be noted that White Hat doesn't state that he actually has some results, but just a theory that contradicts known physics. The reason the "dark energy people" got a Nobel Prize is that the experiments and measurements show that they were onto something real. It seems like White Hat currently only has a model, and not data, to back his theory up which is probably why his theory is being ignored (which he decides to interpret as "suppression"). The title text mentions BICEP2 (Background Imaging of Cosmic Extragalactic Polarization, 2nd generation) which was part of a series of experiments measuring the polarization of the cosmic microwave background . On 17 March 2014, it was announced, to much fanfare, that BICEP2 had detected signals (B-modes) caused by gravitational waves in the early universe (called primordial gravitational waves). A few years later, this announcement was retracted, as it was found that most, if not all, of the reported signal was actually due to interstellar dust within the Milky Way. [1] The title text notes that if there had been a physics mafia, then those results would have ended in bloodshed due to the controversy they caused. [White Hat, with his hands balled into fist and held up above him, is talking with Megan.] White Hat: You physicists are suppressing my theory because it's inconvenient for your models! Megan: Wait, we have a mafia that can suppress annoying results? Megan: Why didn't they do something about the dark energy people?! Megan: We gave them a Nobel prize but I'm still mad at them!

Launch Conditions

Launch Conditions

https://www.xkcd.com/2114

https://www.explainxkcd.com/wiki/index.php/2114:_Launch_Conditions

[A rocket sits on a launch pad and the tower to the left has retracted its access arms. The engines seem to have just started firing and a small cloud at the bottom is visible.] [The rocket still sits on the pad but the cloud is growing and extending to both sides on the ground.] [Ponytail's head, much larger than the rocket, appears above the rocket on the right. The cloud covers the full ground and hides a bigger part of the rocket.] [Zoom out. Ponytail stands behind a pedestal with a rocket model on top and the cloud is all around the bottom of the rocket and below.] Off screen: It's still pretty dry in here. Ponytail: I love the new humidifier, though.

An image of a rocket (presumably a Long March 5 ) with a progressively larger white cloud around it is shown, but no external object for scale is visible until the third panel. It is then revealed to be a model or miniature when Ponytail walks into the shot. The dialog reveals the miniature rocket is a domestic humidifier appliance, using its plumes of water mist to mimic the appearance of the exhaust plume of a full-size rocket. Modern rocket launches are backed by a Sound Suppression System avoiding damages to the rocket itself, the payload, or humans inside. This system drops vast amounts of water into the exhaust of the rocket engines and the water vaporizes immediately. This vapor mainly interrupts the sound reflections from the ground. This reduces the sound to a level the rocket can withstand but also produces a big cloud of water mist. The cloud at the ground consists mostly of water and not the exhaust of the rocket engines. This article shows how the system works: NASA's Incredible Sound Suppression System Prevents Rockets from Exploding (interestingengineering.com) . Some rockets use liquid hydrogen as a fuel, especially for upper stages, so steam is the combustion product. This comic was posted the day after the death of Peter Cosgrove was reported. He was known for photographing many Space Shuttle launches. The title text references the failed o-ring that led to the disintegration of the Challenger Space Shuttle . This disaster was a focal point of controversy, which Richard Feynman played a key role in piercing . The o-ring in question failed to expand at freezing temperatures, resulting in a leak of gas around the edges that was visible as a small vapor plume on the recording. The launch was pushed to a day with lower temperatures than the engineers had planned for. For the humidifier to vent the water mist from this opening is indeed in poor taste, even though the model does not resemble a shuttle. [A rocket sits on a launch pad and the tower to the left has retracted its access arms. The engines seem to have just started firing and a small cloud at the bottom is visible.] [The rocket still sits on the pad but the cloud is growing and extending to both sides on the ground.] [Ponytail's head, much larger than the rocket, appears above the rocket on the right. The cloud covers the full ground and hides a bigger part of the rocket.] [Zoom out. Ponytail stands behind a pedestal with a rocket model on top and the cloud is all around the bottom of the rocket and below.] Off screen: It's still pretty dry in here. Ponytail: I love the new humidifier, though.

Plutonium

Plutonium

https://www.xkcd.com/2115

https://www.explainxkcd.com/wiki/index.php/2115:_Plutonium

[Megan, Hairy, Cueball, and Ponytail are talking.] Megan: How will we keep the spacecraft supplied with heat and electricity? Cueball: We could use a power orb. They give off thousands of watts 24/7. Megan: Huh? How do you recharge it? Cueball: You don't. It's just made of a metal that emits energy. Megan: OK, come on. Hairy: Can we please be serious here? [Caption below the panel:] For something that's real, plutonium is so unrealistic.

This comic pokes fun at the properties of plutonium , claiming that it is so unrealistically powerful that it may as well be random science fiction jargon. Indeed, the ability for a metal to radiate energy sounds impossible (this comic leaves out the inherent dangers of highly radioactive material). This is reflected by Megan and Hairy treating Cueball's idea as a joke. There are devices that need substantial electrical power over long time – in the order of decades – but local sources of energy are insufficient or unavailable, yet constructing a power line or resupplying them with some power source (like fuel, fresh chemical batteries etc.) is either impossible or overly costly. Such devices include maritime beacons and buoys, automatic weather and science stations located in remote areas, and – most importantly – deep space probes and some planetary probes or science packs. Probes sent beyond Jupiter cannot effectively rely on photovoltaic panels for energy, because the great distance to the Sun means that the amount of solar radiation per unit of area is very low, requiring impractically large (and thus heavy) panels to provide enough energy. Carrying a lot of fuel adds mass to the probe, making them more expensive to launch. Instead, such devices usually use radioisotope thermoelectric generators (RTGs). In an RTG the natural radioactive decay of some unstable isotope (such as plutonium-238 or strontium-90 ) produces a lot of heat, which is then used to generate energy using thermopiles , which generate electricity directly from temperature differences using the thermoelectric effect . The key element of an RTG, a pellet of radioactive material such as plutonium dioxide, could be facetiously described as a "power orb" – a lump of a substance that gives out heat apparently out of nothing. Plutonium-238 must be produced from uranium in a nuclear reactor. Unlike plutonium-239, the alpha radiation emitted by plutonium-238 is relatively harmless, as it is quickly absorbed by surrounding material and turned to heat – but plutonium is still incredibly dangerous if it gets inside a human body unprotected. In pure form it produces a little more than half a watt of heat per gram, which slowly drops as the material decays to lead, emitting a quarter watt per gram after 100 years. Other disadvantages of RTGs include the risk of contamination in the event of a launch failure, and the relatively limited supply of plutonium. The title text references development of games. A rule or strategy within a game is often called a mechanic , meant as one particular rule (singular) out of the overall set of rules (game mechanic s ). In this context, the word mechanics is a metaphor referring to the set of rules and interactions that govern the imaginary world of the game. The mechanics of a game define the deterministic or randomized functions of events and/or characters within the game, the outcomes of actions commanded by the players, and so on. This metaphor refers to the mechanics science, and how it describes behavior of physical objects in the real world; However, contrary to real-world mechanics which "just happen" and we only try to describe how things work, in game mechanics every single rule or interaction has to be explicitly defined. The game simulates (to a given extent) an actual world. Game rules do not need to mimic the real world closely and often don't for many reasons; This results in (intended or otherwise) inconsistencies, unexpected behavior or imbalance. Game players complain about “imbalance” when a particular rule, interaction or item present in the game (such as an extremely powerful magical artifact) gives a character exploiting it a great and unjustified advantage. Inconsistencies and possible imbalances can lead to problematic game mechanics being unused or left unresolved, after the creator of those mechanics ceases their participation in the game or game development process. Things that seem like they shouldn't work but do are the main topic of 2540: TTSLTSWBD . [Megan, Hairy, Cueball, and Ponytail are talking.] Megan: How will we keep the spacecraft supplied with heat and electricity? Cueball: We could use a power orb. They give off thousands of watts 24/7. Megan: Huh? How do you recharge it? Cueball: You don't. It's just made of a metal that emits energy. Megan: OK, come on. Hairy: Can we please be serious here? [Caption below the panel:] For something that's real, plutonium is so unrealistic.

.NORM Normal File Format

.NORM Normal File Format

https://www.xkcd.com/2116

https://www.explainxkcd.com/wiki/index.php/2116:_.NORM_Normal_File_Format

[Cueball is at a computer. Someone is talking to him from off-panel.] Voice: I sent you the data. Cueball: Thanks! Cueball: …this is a Word document containing an embedded photo you took of your screen with the spreadsheet open. Voice: Yeah? Does your computer not support .NORM files? Maybe you need to update. [Caption below the panel:] Since everyone sends stuff this way anyway, we should just formalize it as a standard. Several days after this comic release Microsoft announced support for loading pictures into Excel. A photo of a printed data table shall be converted it into a fully editable table. See: Microsoft Excel will now let you snap a picture of a spreadsheet and import it (theverge.com)

Cueball's friend seems to have sent him a rather unusual datafile passed off as a new "normal" standard. People who work with data, and need data sent to them electronically, typically need it sent in a way that they can easily use it – either in a text format that can be copy-pasted, or as a spreadsheet or CSV file that can be imported into a spreadsheet program, or such. Information sent by Cueball's friend in this fashion – a photograph of a spreadsheet embedded into a word processing file – is not only aesthetically unpleasing, but essentially useless for any purpose beyond being looked at. The recipient has no choice but to retype the entire data set, or attempt to use optical character recognition (OCR) and hope that no mistakes are made in the process. Any functional relationships between data (such as formulas used to compute data values) have been lost. Further, the size of the data is bloated by being converted first from numbers and formulas into text, then from text into graphics, and then from graphics to embedded graphics in a word processing document. This adds nothing to the content, and only adds steps to the process of retrieving the data. However useless this kind of data manipulation might be, it is becoming more and more common, especially as more computer-illiterate people find "creative" ways to exchange information. Usually, their job is getting the data together in a Word file, and the only file they have is a screenshot of the spreadsheet, not the original file, so they just put the screenshot in the Word file. Cueball's friend suggests that this is now a normal way to send files, and that Cueball should update his system to support this new type of file, represented by a ".norm" suffix. In 2341: Scientist Tech Help a .norm like file is referenced. The caption acknowledges that this has become a de facto standard and that we should just accept and formalize it. The comic image links to a tweet by OpenElections that displays an Excel file produced by the City of Detroit that contains a lookup table for the city's absentee precincts in 2016. The data had been input as clip art (images) of the values, instead of being entered in the spreadsheet cells. This comic is reminiscent of the comic 763: Workaround , which also describes convoluted formats. The title text suggests that eventually compression (or at least compression with data/quality loss) will be unnecessary as technology improves in the future. SVG ( Scalable Vector Graphics ) is a vector graphic format that is fundamentally a lossless format, representing images using geometric figures. JPEG is a lossy format, representing images as an array of rectangles approximating the original image. Randall suggests that some people in the future may choose to include JPEG artifacts to SVG vector graphics for its "aesthetics", perhaps as a throwback to when lower quality JPEG images were commonplace, or as a form of glitch art . It is possible that some in the future will view JPEG artifacts as giving their images a quaint/retro feel, much the way that some people today use sepia-tone filters on their images. (And much like some people today use JPEG artifacts to give their images an intentionally low-quality appearance .) This is made even more reasonable by the fact that the SVG specification employs a lot of filters and already can embed regular pixel-based JPEG files. Furthermore, it allows JavaScript to be used to manipulate objects, meaning such an effect may be implementable in the current SVG 2.0 specification. [Cueball is at a computer. Someone is talking to him from off-panel.] Voice: I sent you the data. Cueball: Thanks! Cueball: …this is a Word document containing an embedded photo you took of your screen with the spreadsheet open. Voice: Yeah? Does your computer not support .NORM files? Maybe you need to update. [Caption below the panel:] Since everyone sends stuff this way anyway, we should just formalize it as a standard. Several days after this comic release Microsoft announced support for loading pictures into Excel. A photo of a printed data table shall be converted it into a fully editable table. See: Microsoft Excel will now let you snap a picture of a spreadsheet and import it (theverge.com)

Differentiation and Integration

Differentiation and Integration

https://www.xkcd.com/2117

https://www.explainxkcd.com/wiki/index.php/2117:_Differentiation_and_Integration

[Two flow charts are shown.] [The first flow chart has four steps in simple order, one with multiple recommendations.] DIFFERENTIATION Start Try applying Chain Rule Power Rule Quotient Rule Product Rule Etc. Done? No [Arrow returns to "Try applying" step.] Yes Done! [The second flow chart begins like the first, then descends into chaos.] INTEGRATION Start Try applying Integration by Parts Substitution Done? Haha, Nope! [Chaos, Roughly from left to right, top to bottom, direction arrows not included.] Cauchy's Formula ???? ???!? ??? ??? ? Partial Fractions ?? ? Install Mathematica ? Riemann Integration Stokes' Theorem ??? ? Risch Algorithm ??? [Sad face.] ????? ??? What the heck is a Bessel Function?? Phone calls to mathematicians Oh No Burn the Evidence [More arrows pointing out of the image to suggest more steps.]

This comic illustrates the old saying "Differentiation is mechanics, integration is art." It does so by providing a flowchart purporting to show the process of differentiation, and another for integration. Differentiation and Integration are two major components of calculus . As many Calculus 2 students are painfully aware, integration is much more complicated than the differentiation it undoes. However, Randall dramatically overstates this point here. After the first step of integration, Randall assumes that any integration can not be solved so simply, and then dives into a step named "????", suggesting that it is unknowable how to proceed. The rest of the flowchart is (we can assume deliberately) even harder to follow, and does not reach a conclusion. This is in contrast to the simple, straightforward flowchart for differentiation. The fact that the arrows in the bottom of the integration part leads to nowhere indicates that "Phone calls to mathematicians", "Oh no" and "Burn the evidence" are not final steps in the difficult journey. The flowchart could be extended by Randall to God-knows-where extents. It should be noted that Randall slightly undermines his point by providing four different methods, and an "etc", and a "No"-branch for attempting differentiation with no guidelines for selecting between them. Chain rule For any and , it follows that . Power Rule For any and , it follows that . Quotient rule For any and , it follows that if . Product rule For any and , it follows that . Integration by parts The "product rule" run backwards. Since , it follows that by integrating both sides you get , which is more commonly written as . By finding appropriate values for functions such that your problem is in the form , your problem may be simplified. The catch is, there exists no algorithm for determining what functions they might possibly be, so this approach quickly devolves into a guessing game - this has been the topic of an earlier comic, 1201: Integration by Parts . Substitution The "chain rule" run backwards. Since , it follows that . By finding appropriate values for functions such that your problem is in the form your problem may be simplified. Cauchy's Formula Cauchy's Integral formula is a result in complex analysis that relates the value of a contour integral in the complex plane to properties of the singularities in the interior of the contour. It is often used to compute integrals on the real line by extending the path of the integral from the real line into the complex plane to apply the formula, then proving that the integral from the parts of the contour not on the real line has value zero. Partial Fractions Partial fractions is a technique for breaking up a function that comprises one polynomial divided by another into a sum of functions comprising constants over the factors of the original denominator, which can easily be integrated into logarithms. Install Mathematica Mathematica is a modern technical computing system spanning most areas. One of its features is to compute mathematical functions. This step in the flowchart is to install and use Mathematica to do the integration for you. Here is a description about the intricacies of integration and how Mathematica handles those . (It would be quicker to try Wolfram Alpha instead of installing Mathematica, which uses the same backend for mathematical calculations.) Riemann Integration The Riemann integral is a definition of definite integration. Elementary textbooks on calculus sometimes present finding a definite integral as a process of approximating an area by strips of equal width and then taking the limit as the strips become narrower. Riemann integration removes the requirement that the strips have equal width, and so is a more flexible definition. However there are still many functions for which the Riemann integral doesn't converge, and consideration of these functions leads to the Lebesgue integral . Riemann integration is not a method of calculus appropriate for finding the anti-derivative of an elementary function. Stokes' Theorem Stokes' theorem is a statement about the integration of differential forms on manifolds. It is invoked in science and engineering during control volume analysis (that is, to track the rate of change of a quantity within a control volume, it suffices to track the fluxes in and out of the control volume boundary), but is rarely used directly (and even when it is used directly, the functions that are most frequently used in science and engineering are well-behaved, like sinusoids and polynomials). Risch Algorithm The Risch algorithm is a notoriously complex procedure that, given a certain class of symbolic integrand, either finds a symbolic integral or proves that no elementary integral exists. (Technically it is only a semi-algorithm, and cannot produce an answer unless it can determine if a certain symbolic expression is equal to 0 or not.) Many computer algebra systems have chosen to implement only the simpler Risch-Norman algorithm, which does not come with the same guarantee. A series of extensions to the Risch algorithm extend the class of allowable functions to include (at least) the error function and the logarithmic integral. A human would have to be pretty desperate to attempt this (presumably) by hand. Bessel function Bessel functions are the solution to the differential equation , where n is the order of Bessel function. Though they do show up in some engineering, physics, and abstract mathematics, in lower levels of calculus they are often a sign that the integration was not set up properly before someone put them into a symbolic algebra solver. Phone calls to mathematicians This step would indicate that the flowchart user, desperate from failed attempts to solve the problem, contacts some more skilled mathematicians by phone, and presumably asks them for help. The connected steps of "Oh no", "What the heck is a Bessel function?" and "Burn the evidence" may suggest the possibility that this interaction might not play out very well and could even get the caller in trouble. Specialists and renowned experts being bothered - not to their amusement - by strangers, often at highly inconvenient times or locations, is a common comedic trope, also previously utilized by xkcd (for example in 163: Donald Knuth ). Burn the evidence This phrase parodies a common trope in detective fiction, where characters burn notes, receipts, passports, etc. to maintain secrecy. This may refer to the burning of one's work to avoid the shame of being associated with such a badly failed attempt to solve the given integration problem. Alternatively, it could be an ironic hint to the fact that in order to find the integral, it may even be necessary to break the law or upset higher powers, so that the negative consequences of a persecution can only be avoided by destroying the evidence. Symbolic integration Symbolic integration is the basic process of finding an antiderivative function (defined with symbols), as opposed to numerically integrating a function. The title text is a pun that defines the term not as integration that works with symbols, but rather as integration as a symbolic act, as if it were a component of a ritual. A symbolic act in a ritual is an act meant to evoke something else, such as burning a wooden figurine of a person to represent one’s hatred of that person. Alternatively, the reference could be seen as a joke that integration might as well be a symbol, like in a novel, because Randall can't get any meaningful results from his analysis. [Two flow charts are shown.] [The first flow chart has four steps in simple order, one with multiple recommendations.] DIFFERENTIATION Start Try applying Chain Rule Power Rule Quotient Rule Product Rule Etc. Done? No [Arrow returns to "Try applying" step.] Yes Done! [The second flow chart begins like the first, then descends into chaos.] INTEGRATION Start Try applying Integration by Parts Substitution Done? Haha, Nope! [Chaos, Roughly from left to right, top to bottom, direction arrows not included.] Cauchy's Formula ???? ???!? ??? ??? ? Partial Fractions ?? ? Install Mathematica ? Riemann Integration Stokes' Theorem ??? ? Risch Algorithm ??? [Sad face.] ????? ??? What the heck is a Bessel Function?? Phone calls to mathematicians Oh No Burn the Evidence [More arrows pointing out of the image to suggest more steps.]

Normal Distribution

Normal Distribution

https://www.xkcd.com/2118

https://www.explainxkcd.com/wiki/index.php/2118:_Normal_Distribution

[A bell curve of a normal distribution, with the area between two horizontal lines shaded.] [The center of the chart is marked between the two lines:] Midpoint [The distance between the lines is marked to the right of the midpoint, with the label:] 52.7% [A label on the outside of the graph, describing the distance between the two lines:] "Remember, 50% of the distribution falls between these two lines!" [Caption below the panel:] How to annoy a statistician

In statistics, a distribution is a representation that can be understood in terms of how much of a sample is expected to fall into either discrete bins or between particular ranges of values. For example, if you wanted to represent an age distribution using bins of ten years (0-9, 10-19, etc.), you could produce a bar chart, one bar for each bin, where the height of each bar represents a count of the portion of the sample matching that bin. To turn that bar chart into a distribution, you'd get infinitely many people (technically: a number N which tends to infinity), put them into age bins that are infinitely narrow (technically: bins whose size is O(1/sqrt(N))), and then divide each bin count by the total count so that the whole thing added up to 1. It is common to ask how much of the distribution lies between two vertical lines; that would correspond to asking what percent of people are expected to fall between two ages. Many statistical samplings resemble a pattern called a " normal distribution ". A theoretically perfect normal distribution would have an infinite sample size and infinitely small bins. That would produce a bar chart matching the shape of the curve in the comic. The area between two vertical lines of the distribution represents the probability that a randomly selected X-value is between the X-values of the lines. Randall instead finds the area between two horizontal lines, which is mathematically meaningless, because the Y-axis of a probability distribution is typically taken to represent magnitude as a fraction of unity. In the age-distribution analogy above, two points with the same X-value could be understood to represent two people with the same age; but two points with the same Y-value cannot easily be understood in terms of the analogy. The items "represented" by the magnitude at any given horizontal position are indistinguishable, unordered, and interchangeable; the fact that two items happen to fall at the same position on the Y-axis doesn't mean they have anything in common. In short, Randall has invented a new probability distribution, which the title text humorously implies should be called the tangent distribution . This distribution is defined as follows: consider the area between the curve in the comic and the horizontal axis, and consider a random point (X, Y) uniformly distributed in that region. Then X has the normal distribution and Y has the tangent distribution. Areas between vertical lines in the comic give probabilities concerning X, and areas between horizontal lines in the comic give probabilities concerning Y. The comic correctly indicates that if we let R be the interval of Y values that is 52.682% of the range of Y centered at the midpoint of the range, then any randomly selected Y value has probability 1/2 of falling inside interval R . This distribution has never been discussed before, and has no known application. Moreover, the distribution of Y is not symmetric: while 50% of Y values fall inside interval R , 41% fall below R and only 9% fall above R . So the single piece of information in the comic is not a good way to describe this distribution! We do use such intervals for the normal distribution because the normal distribution is symmetric, and the center of symmetry is the mean, median, and mode. (However, it would be just about as ridiculous to observe that 50% of the X values in a standard normal distribution fall between the vertical lines X=-0.2 and X=1.41.) The title text refers to the notion of normals and tangents in geometry. Given a 2D curve or 3D surface, a line which points perpendicularly outward from a point on the curve or surface (making a 90-degree angle with the curve) is said to be normal to the curve, while a line which just grazes the curve, being exactly parallel to the curve at the point of contact, is said to be tangent to the curve at that point. The joke is that this geometrical notion of normal is completely unrelated to the statistical normal distribution . Randall observes that if you take a geometric normal and rotate it 90 degrees, you produce a tangent; thus, if you take the normal distribution and rotate it by 90 degrees, you must get something called the " tangent distribution." Saying this to a statistician would only annoy the statistician further. This is annoying to a statistician not only because the terms normal and tangent come from differential geometry and have no established meaning in probability theory. Even the word perpendicular has no established meaning in probability theory. Of course, the x and y coordinates in the comic are perpendicular (orthogonal) coordinates, but X and Y are not "perpendicular" or "orthogonal" random variables. Even if we give "perpendicular" or "orthogonal" a probabilistic meaning, and the most obvious such meaning is either independent , which even uses a symbol related to the geometric symbol for perpendicularity, or uncorrelated , which makes X and Y orthogonal vectors in the Hilbert space of random variables that are square integrable with respect to Lebesgue measure, X and Y are not perpendicular in either of these senses. So the more probability and statistics you know, the more annoying this comic becomes. It is not just about confusing novices. [A bell curve of a normal distribution, with the area between two horizontal lines shaded.] [The center of the chart is marked between the two lines:] Midpoint [The distance between the lines is marked to the right of the midpoint, with the label:] 52.7% [A label on the outside of the graph, describing the distance between the two lines:] "Remember, 50% of the distribution falls between these two lines!" [Caption below the panel:] How to annoy a statistician

Video Orientation

Video Orientation

https://www.xkcd.com/2119

https://www.explainxkcd.com/wiki/index.php/2119:_Video_Orientation

[The image shows three columns by three rows with the following headers:] Video Orientation Pros Cons [First row:] [A wide picture with a text above:] Horizontal [Pros are:] Looks normal to old people Format used by a century of cinema [Cons are:] Humans are taller than are wide I'm not turning my phone sideways [Second row:] [A tall picture with a text above:] Vertical [Pros are:] How most normal people shoot and watch video now so we may as well accept it [Cons are:] Human world is mostly a horizontal plane [Third row:] [A picture rotated by 45 degrees with a text above:] Diagonal [Pros are:] Bold and dynamic Equally annoying to all viewers Good compromise [Cons are:] None

This comic compares selected pros and cons of 3 video "orientations" (also known as angling), one of which is entirely made-up. This comic could have been inspired by articles published by Mashable , and Scientific American , which comment on how videos are now filmed vertically through smartphones. Randall's observations on horizontal vs vertical indicate that he has resigned himself to the acceptance of vertical videos. However, he does love a good compromise , so he suggests "Diagonal Orientation" as a third option to equally dissatisfy both types of user. The issue with this is that diagonal angling fails to fully capture the benefits of either horizontal or vertical angling. This is another comic claiming that an obviously bad idea keeps being done by accident "so we might as well just accept it", following on from 2116: .NORM Normal File Format a week prior. Horizontal orientation Pros: Cons: Vertical orientation Pros: Cons: Diagonal orientation Pros: Cons: The diagonal orientation is similar to the "oblique angle" or " Dutch angle " in cinema, and is often used to portray psychological uneasiness or tension in the subject being filmed. Note that while "Dutch angle" is filmed diagonally, it is projected in the classic Horizontal orientation. Circular video Pros: Cons: [The image shows three columns by three rows with the following headers:] Video Orientation Pros Cons [First row:] [A wide picture with a text above:] Horizontal [Pros are:] Looks normal to old people Format used by a century of cinema [Cons are:] Humans are taller than are wide I'm not turning my phone sideways [Second row:] [A tall picture with a text above:] Vertical [Pros are:] How most normal people shoot and watch video now so we may as well accept it [Cons are:] Human world is mostly a horizontal plane [Third row:] [A picture rotated by 45 degrees with a text above:] Diagonal [Pros are:] Bold and dynamic Equally annoying to all viewers Good compromise [Cons are:] None

Brain Hemispheres

Brain Hemispheres

https://www.xkcd.com/2120

https://www.explainxkcd.com/wiki/index.php/2120:_Brain_Hemispheres

[Cueball is shown with the right half of his brain (on the viewer's left) colored in orange and the left half (on the viewer's right) in iris blue. An iris blue box is overlaid over the right half of the body (on the viewer's left), and an orange box is overlaid over the top half. The boxes are overlapping in a greenish color on the upper right quarter of the body (on the viewer's left).] Neuroscience Fact: [An arrow pointing to the iris blue rectangle on top with the text above:] The left half of the brain actually controls the right half of the body... [An arrow pointing to the orange rectangle at the right, the text reads:] ...while the right half of the brain actually controls the top half of the body. [An arrow pointing to the overlapping area (the top left body from the viewers perspective) with the text below:] Disputed/dual control [An arrow pointing to Cueball's left leg area (on the viewer's right), not highlighted by any color, and the text is:] This leg is fully autonomous

As a general rule, each cerebral hemisphere controls the opposite side of the body; things on the left half of the body are controlled by the right side of the brain and vice-versa. Biology is complicated, of course, so as with most biology "rules" there are exceptions, such as the cranial nerves , but it's true for most motor functions, and a relatively well-known factoid, if not strictly correct in all cases. Randall spoofs this by saying that rather than controlling the left half of the body, the right brain controls the top. This leads to a Venn-diagram-like picture of the human body, with an overlap in the upper right, labelled "disputed," echoing maps that display a territorial dispute , suggesting that the halves of your brain fight for control of the region, or " dual control " like in an airplane, where the pilot and the copilot both can control the plane at any time. The reorganization also leaves a gap in the bottom left, implying that the left leg is not controlled by any part of the brain, and instead has a mind of its own. The title text is another, separate joke about the same factoid. He proposes that the hands should be referred to not by their physical location, but by the hemisphere of the brain they're connected to. Of course, this is not only silly but inconsistent: if the hands were labelled by hemispheres of the brain, the same would presumably apply to the arms. Furthermore, there would be no reason to give left/right names to the hemispheres themselves, since their placement in the skull would be irrelevant. [Cueball is shown with the right half of his brain (on the viewer's left) colored in orange and the left half (on the viewer's right) in iris blue. An iris blue box is overlaid over the right half of the body (on the viewer's left), and an orange box is overlaid over the top half. The boxes are overlapping in a greenish color on the upper right quarter of the body (on the viewer's left).] Neuroscience Fact: [An arrow pointing to the iris blue rectangle on top with the text above:] The left half of the brain actually controls the right half of the body... [An arrow pointing to the orange rectangle at the right, the text reads:] ...while the right half of the brain actually controls the top half of the body. [An arrow pointing to the overlapping area (the top left body from the viewers perspective) with the text below:] Disputed/dual control [An arrow pointing to Cueball's left leg area (on the viewer's right), not highlighted by any color, and the text is:] This leg is fully autonomous

Light Pollution

Light Pollution

https://www.xkcd.com/2121

https://www.explainxkcd.com/wiki/index.php/2121:_Light_Pollution

[Four views of the night sky are shown in separate panels. They look more like photographs than drawn comics. A caption at the top reads:] Light Pollution and the Disappearing Night Sky [The first view shows only a few bright stars visible on a fairly light gray-brownish background. The inline text on the left top is:] High Light Pollution (Cities) [In the second view more stars, and hints of a few galactic clouds, are visible against a dark-gray background.] Moderate Light Pollution (Suburbs) [A lot of stars in the third image, some partly colored, and a clear view of the Milky Way.] Low Light Pollution (Very remote areas) [The fourth and last image shows even more stars and brighter colors. A slightly fuzzy illuminated triangular grid overlays the entire sky. Embedded within it are three ghostly silhouettes of celestial sailing ships. The text on the top left reads:] No Light Pollution (How the sky should look) [Four arrows are pointing to some triangles:] Lattice of the crystal spheres [Three arrows are indicating the sailing ships:] Ships of the Sky King

This comic shows how light pollution in cities affect what you can see from the night sky. The first three panels show realistic examples of what you could see from the sky inside a large city, in the suburbs and far away from light pollution. These panels roughly correlate on the Bortle Scale to 8-9 (city), 5-6 (suburbs) and 2-3 (remote area). The last panel contrasts these for comedic effect with fake things in the sky that are not actually present in the night sky. [ citation needed ] The "Ships of the Sky King" may be a reference to an elven legend in J. R. R. Tolkien 's works, in which several elven ships sail tangentially off the planet of Middle Earth and into the sky. This story was previously mentioned in 1255: Columbus . " Crystal spheres " is an ancient theory about the heavens and what it was that held up the stars, before it was commonly accepted that space could be made of hard vacuum and celestial bodies held there by laws of inertia and gravity and vast distances. The spheres are nested inside each other concentrically. Randall proposes they are held by latticework like that which supports the Eiffel Tower, and that the lattice structure could be seen long ago when the sky was much darker. It is also a possible reference to the science fiction short-story " The Crystal Spheres " by David Brin, where the solar system is surrounded by hard crystal spheres that have to be broken before leaving as an explanation of the Fermi Paradox. Furthermore, in the lore of Dungeons & Dragons, the solar system is also enclosed in a massive crystal sphere, with other solar systems in similar solar systems, separated by "the flow". Although all crystals do have a crystal lattice , as in the meaning 3 of the word "crystal" in Merriam-Webster ( a body that [...] has a regularly repeating internal arrangement of its atoms and often external plane faces ), these lattices are sub-microscopic and would be invisible in the sky. Additionally, crystal structure was not yet known at the time that the celestial spheres theory was popular. In consensus reality, the sky does contain many invisible objects that can observe us and/or provide major structures of our society, such as satellites, nearcraft , and drones, but these are usually invisible due to size and distance more than brightness. The title text starts off sounding like a legitimate statement about light pollution. It is common to remark that the vast majority of people never see things in the night sky that were commonly seen by our ancestors every night prior to industrialization, such as the Milky Way or now-obscure phenomena such as Zodiacal light , Airglow or Gegenschein . The title text then further adds to the humor of the last panel by describing non-existent features, which could be references to H. P. Lovecraft as he often refers to beasts the possible size that “The Destroyer of Sagittarius” would have to be ( Sagittarius is one of the constellations of the zodiac and Sagittarius A* a black hole at the center of the Milky Way inside of that constellation.). He also often speaks of insanity and color, connecting the two. [Four views of the night sky are shown in separate panels. They look more like photographs than drawn comics. A caption at the top reads:] Light Pollution and the Disappearing Night Sky [The first view shows only a few bright stars visible on a fairly light gray-brownish background. The inline text on the left top is:] High Light Pollution (Cities) [In the second view more stars, and hints of a few galactic clouds, are visible against a dark-gray background.] Moderate Light Pollution (Suburbs) [A lot of stars in the third image, some partly colored, and a clear view of the Milky Way.] Low Light Pollution (Very remote areas) [The fourth and last image shows even more stars and brighter colors. A slightly fuzzy illuminated triangular grid overlays the entire sky. Embedded within it are three ghostly silhouettes of celestial sailing ships. The text on the top left reads:] No Light Pollution (How the sky should look) [Four arrows are pointing to some triangles:] Lattice of the crystal spheres [Three arrows are indicating the sailing ships:] Ships of the Sky King

Size Venn Diagram

Size Venn Diagram

https://www.xkcd.com/2122

https://www.explainxkcd.com/wiki/index.php/2122:_Size_Venn_Diagram

[A Venn diagram with five sets titled 'Big', 'Little', 'Large', 'Small' and 'Great'. Various words which can be prefixed by these titles are shown in the relevant segment.] Big: Bang Theory, Enchilada, Board, Sur Little: Orphan Annie, House on the Prairie, Richard Large: format, Millimeter Telescope, Hadron Collider Small: claims court, potatoes Great: Barrier Reef, Wall of China, Depression, Terror, aunt Big/Great: Bend, Bear Lake Big/Small: time, screen Big/Little: Dipper, Planet, lies, sister Little/Great: Blue Heron Little/Large: Professor, Forest Bat Big/Large: Toothed Aspen Large/Small: intestine, Magellanic Cloud Little/Small: wonder, soldiers Small/Great: pox, cardiac vein Large/Great: Billed Seed Finch Big/Large/Great: hearted Big/Small/Great: end Big/Little/Small: foot Big/Little/Great: league Little/Large/Great: (none) Big/Little/Large: foundation Big/Large/Small: Eyed Conger, Blue Little/Large/Small: emerald Little/Small/Great: circle, room Large/Small/Great: flying fox Big/Large/Small/Great: game, white Big/Little/Small/Great : world, one Big/Little/Large/Great : (none) Big/Little/Large/Small : frog Little/Large/Small/Great : (none) Big/Little/Large/Small/Great: Island

This comic is a Venn diagram illustrating the complete set of possible intersections of five different size adjectives: "little", "large", "small", "great" and “big”. Each unique intersection contains a short list of nouns that can be preceded by each of its intersecting adjectives. For example, "flying fox" (a type of bat) appears at the intersection of "large", "small", and "great", because the species large flying fox , small flying fox , and great flying fox all exist, but there is no such species as a "big flying fox" or a "little flying fox". Similarly, humans have organs named the small intestine and large intestine , but no "little intestine", "great intestine", or "big intestine". Some descriptors are applied in combination to their noun, rather than individually; for example, "planet" is placed in both the "little" and "big" groups in reference to the 2008 video game Little Big Planet . In the title text, Randall declares that he will start intentionally using term combinations that don't appear in the above diagram, presumably to ensure every intersection contains at least one term. A similar concept can be seen in 181: Interblag , but in a tabular form rather than a Venn diagram. The following table lists all size/noun combinations that the Venn diagram can generate, with a description of each. [A Venn diagram with five sets titled 'Big', 'Little', 'Large', 'Small' and 'Great'. Various words which can be prefixed by these titles are shown in the relevant segment.] Big: Bang Theory, Enchilada, Board, Sur Little: Orphan Annie, House on the Prairie, Richard Large: format, Millimeter Telescope, Hadron Collider Small: claims court, potatoes Great: Barrier Reef, Wall of China, Depression, Terror, aunt Big/Great: Bend, Bear Lake Big/Small: time, screen Big/Little: Dipper, Planet, lies, sister Little/Great: Blue Heron Little/Large: Professor, Forest Bat Big/Large: Toothed Aspen Large/Small: intestine, Magellanic Cloud Little/Small: wonder, soldiers Small/Great: pox, cardiac vein Large/Great: Billed Seed Finch Big/Large/Great: hearted Big/Small/Great: end Big/Little/Small: foot Big/Little/Great: league Little/Large/Great: (none) Big/Little/Large: foundation Big/Large/Small: Eyed Conger, Blue Little/Large/Small: emerald Little/Small/Great: circle, room Large/Small/Great: flying fox Big/Large/Small/Great: game, white Big/Little/Small/Great : world, one Big/Little/Large/Great : (none) Big/Little/Large/Small : frog Little/Large/Small/Great : (none) Big/Little/Large/Small/Great: Island

Meta Collecting

Meta Collecting

https://www.xkcd.com/2123

https://www.explainxkcd.com/wiki/index.php/2123:_Meta_Collecting

[The comic depicts Cueball reading from a list to White Hat, standing next to a case filled with collectables including an urn, a model ship, a compact disc, a vinyl record, a doll or figurine, a martini glass, and a teapot.] Today we're looking for a lunchbox, a snow globe, a Maytag dryer, a Harley Davidson, and a stamp. [Caption below the frame:] My hobby: Collecting one item from every category listed on Wikipedia's "List of collectables." As of 13 March 2019 at 6:44 PM ET, there was a debate on the Wikipedia talk tab about locking this page. This has now been upheld, and the page was temporarily locked. As of 25 May 2019 at 10:25 PM ET, the page was unlocked and yachts were back on the list. A previous comic, 739: Malamanteau , also caused a similar situation on Wikipedia, with many xkcd fans attempting to create the fictional page. The page has been turned into a redirect to the Wikipedia page for xkcd.

This is another comic in the " My Hobby " series. Many people's hobbies involve collecting many items of the same category: Post stamps, collectible cards, painted dolls, wine, and so on. Just about anything can be collected, however, some things are collected much more often than others. Wikipedia has a page listing the most popular categories of such collectible items. In Randall's usual style of going meta with everything, he decided to start a meta-collection—a collection of examples of different things that people can collect. He uses Wikipedia's list of collectibles for reference. In the comic, Cueball is showing to his friend his collection of various items that have nothing in common except that they're all popular collectibles. So while most people try to collect everything in one narrow category of collectibles, Cueball's collection will only be complete if he can get one item from each of the list of collectible items as cataloged by Wikipedia's list, so he has a collection of representative elements from all collections. In the title text, Randall complains about a Wikipedia editor who keeps adding yachts to the list of collectibles, probably because it would force him to buy a yacht if he ever wanted to complete his collection of collectibles. Yachts are traditionally considered immensely expensive and the vast majority of people own zero yachts, let alone a collection of them. [ citation needed ] Note that Randall does not specify how he is trying to get the page locked, and the comic itself might be a rather meta way of doing so: xkcd fans have a history of making lots of edits to Wikipedia articles Randall mentions, resulting in them being protected or locked. The article has in fact been edited and reverted about 50 times by these fans over the course of a single day and was temporarily protected on March 14th, 2019, which expired three days later. The first addition of Yachts to this page was by a user named Xkcd2123 , but it is unlikely that this user is Randall. Items are numbered on each shelf from left. [The comic depicts Cueball reading from a list to White Hat, standing next to a case filled with collectables including an urn, a model ship, a compact disc, a vinyl record, a doll or figurine, a martini glass, and a teapot.] Today we're looking for a lunchbox, a snow globe, a Maytag dryer, a Harley Davidson, and a stamp. [Caption below the frame:] My hobby: Collecting one item from every category listed on Wikipedia's "List of collectables." As of 13 March 2019 at 6:44 PM ET, there was a debate on the Wikipedia talk tab about locking this page. This has now been upheld, and the page was temporarily locked. As of 25 May 2019 at 10:25 PM ET, the page was unlocked and yachts were back on the list. A previous comic, 739: Malamanteau , also caused a similar situation on Wikipedia, with many xkcd fans attempting to create the fictional page. The page has been turned into a redirect to the Wikipedia page for xkcd.

Space Mission Hearing

Space Mission Hearing

https://www.xkcd.com/2124

https://www.explainxkcd.com/wiki/index.php/2124:_Space_Mission_Hearing

[Megan and Ponytail are standing and talking.] Ponytail: All ready for the hearing? Let's go over things one more time. Ponytail: *ahem* Ponytail: What is the main reason to fund this mission? [Close-up of Megan.] Megan: It will significantly advance out long-term goal of better understanding the formation and evolution of the Solar System, while fulfulling our mandate to develop a new generation of interplanetary spacecraft. Ponytail (off-panel): Great. [Megan and Ponytail are standing and talking. Megan's arms are raised.] Megan: And because it's space! Megan: Spaaaaaace. Megan: Pew pew pew! Megan: Space! Ponytail: Dial it back.

Megan and Ponytail are organizers of a space mission going over their upcoming presentation to a hearing that will approve the mission's funding. Megan recites the grown-up, professional, scientific justification for the mission, but soon her enthusiastic and nerdy attitude toward space breaks through, and she exclaims "space" and "pew pew pew" (An internet meme for the sound of lasers, inspired as a typical sound that media space weapons make, and now an onomatopoeia often used in gaming speak for ray weapons and spells as a joke) with childish abandon. Ponytail wants her to rein in her enthusiasm during the actual hearing as the funding is unlikely to come if they are behaving childishly instead of being professional. The joke is that most of the motivation people working in space agencies have for spending billions of dollars and other resources on interplanetary exploration is not really for all the stuffy reasons listed, but simply because they believe space is cool. Funnily, due to the vacuum in space, you would actually not hear sounds and so some part of the enthusiasm is entirely childish. The title text refers to a repurposable piece of electronics contained within specific greeting cards , which plays a prerecorded song when the card is opened. Usually, these cards play a song, like "Happy Birthday", when they are opened. Apparently, their grant application has incorporated speakers which play "spaceship noises", in order to stimulate excitement about the coolness of space in the receiver which is in contrast to the business-like atmosphere that a mission hearing would normally have. An additional joke is that the card will likely hurt their chances to get the funding instead of stimulating excitement in the receiver. [Megan and Ponytail are standing and talking.] Ponytail: All ready for the hearing? Let's go over things one more time. Ponytail: *ahem* Ponytail: What is the main reason to fund this mission? [Close-up of Megan.] Megan: It will significantly advance out long-term goal of better understanding the formation and evolution of the Solar System, while fulfulling our mandate to develop a new generation of interplanetary spacecraft. Ponytail (off-panel): Great. [Megan and Ponytail are standing and talking. Megan's arms are raised.] Megan: And because it's space! Megan: Spaaaaaace. Megan: Pew pew pew! Megan: Space! Ponytail: Dial it back.

Luna 2

Luna 2

https://www.xkcd.com/2125

https://www.explainxkcd.com/wiki/index.php/2125:_Luna_2

[Cueball is standing behind while Megan sits at a laptop.] Megan: Huh. Luna 2 , the first artificial object to touch another world, carried a sphere made of steel Soviet flag emblems. [A patterned sphere is shown blowing up to pieces.] It was designed to blow apart on impact, scattering tiny metal flags and ribbons across the surface of the moon. [Close-up of Cueball and Megan's faces.] Cueball: So the first physical contact humans had with a heavenly body... Megan: ...was throwing a shrapnel grenade full of flags at it. Cueball: Well, it's on-brand for us, at least.

This comic is referring to Luna 2 , the first man-made object to make contact with the surface of the moon, and consequently, as stated in the comic, the first man-made object to touch another world. On September 13, 1959, it hit the Moon's surface east of Mare Imbrium near the craters Aristides, Archimedes , and Autolycus . Megan is sitting in front of a computer, and telling Cueball about the Luna 2. She shows a picture of the probe and explains that the probe was designed to explode on impact, thus scattering multiple metal Soviet flags and ribbons on the surface of the Moon. They compare it to throwing a shrapnel grenade with flags in it at the moon (see Trivia ). In truth, the idea behind the two explosive spheres was rather clever. The spacecraft arrived at the moon at about 12,000 mph - and with uncontrolled orientation. But no matter which orientation that these spheres were in as they arrived at the moon, the force of the explosion would cause the commemorative plaques nearest to the direction of motion to be thrown even faster at the moon (and, presumably, be vaporized) - while the ones from the opposite side of the sphere would be slowed down by the force of the explosion and might possibly arrive at the surface intact. Cueball's observation that it is "on-brand" for humans to litter another world with an explosion of nationalist iconography immediately upon reaching it, is a reference to the vastly numerous historical instances when, upon setting foot on territory for the first time, humans "conquer" it, by planting flags on the first thing they see. Alternately, it may be "on-brand" for humanity's first interaction with a new object to be striking it with a weapon. The title text refers to the fact that for the Luna 2 mission it was more important to just get to the moon at all rather than have a sophisticated landing mechanism. This was due to the fact that it happened during the space race between the USA and USSR and both countries tried to reach significant milestones in space exploration. The metaphorical interpretation is that sometimes people get overly excited after an initial breakthrough and dive into projects without thinking them through or considering long term consequences. This often leads to the project failing or barely achieving its aim. This often goes along with the confidence to be able to "wing it" making up a solution on the spot when a problem comes up. Note that Randall makes a subtle yet strong declaration that he is an engineer, a human, and an Earthling first, and American second, by saying "we" in the title text, regarding this effort to reach the Moon. [Cueball is standing behind while Megan sits at a laptop.] Megan: Huh. Luna 2 , the first artificial object to touch another world, carried a sphere made of steel Soviet flag emblems. [A patterned sphere is shown blowing up to pieces.] It was designed to blow apart on impact, scattering tiny metal flags and ribbons across the surface of the moon. [Close-up of Cueball and Megan's faces.] Cueball: So the first physical contact humans had with a heavenly body... Megan: ...was throwing a shrapnel grenade full of flags at it. Cueball: Well, it's on-brand for us, at least.

Google Trends Maps

Google Trends Maps

https://www.xkcd.com/2126

https://www.explainxkcd.com/wiki/index.php/2126:_Google_Trends_Maps

The least informative Google Trends Maps I've created over the years (All are real but not all cover the same date range) [12 maps of the United States are shown with the states colored. There are labels for the colors.] [Map 1] [Blue:] Frostbite [Red:] Heat stroke [Alabama, Arizona, Arkansas, California, Florida, Georgia, Hawaii, Idaho, Louisiana, Mississippi, Nevada, New Mexico, Oklahoma, Oregon, South Carolina, Tennessee, Texas, Utah, and Washington are red. All other states are blue.] [Map 2] [Blue:] Best church [Red:] Best strip club [Nevada is red. Alaska, North Dakota, and Wyoming are gray. All other states are blue.] [Map 3] [Blue:] Bigfoot [Red:] Mike Pence [Indiana is red. All other states are blue.] [Map 4] [Blue:] Etiquette [Red:] Sexting [Alabama, Alaska, Arkansas, Delaware, Hawaii, Iowa, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, North Dakota, Ohio, South Dakota, Tennessee, Vermont, and West Virginia are red. All other states are blue.] [Map 5] [Blue:] Little dog [Red:] Big cat [Arizona, Arkansas, California, Colorado, Idaho, Iowa, Maine, Mississippi, Nebraska, Nevada, New Jersey, New Mexico, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, and Wyoming are blue. All other states are red.] [Map 6] [Blue:] Shark attack [Red:] Childbirth [California, Connecticut, Delaware, Florida, Georgia, Kentucky, Louisiana, Maine, Massachusetts, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Virginia, and West Virginia are blue. All other states are red.] [Map 7] [Blue:] Snakes [Red:] Ants [Yellow:] Bees [Green:] Alligators [Florida is green. Iowa, Maine, Massachusetts, Minnesota, Montana, Nevada, New Jersey, New Mexico, Oregon, Pennsylvania, and Wisconsin are red. Alaska, Arizona, California, Connecticut, Hawaii, Illinois, Indiana, Michigan, New Hampshire, New York, North Dakota, Ohio, Rhode Island, Utah, Vermont, Washington, and Wyoming are yellow. All other states are blue.] [Map 8] [Blue:] Retirement planning [Red:] Bungee jumping [Alaska, Delaware, Hawaii, Idaho, Mississippi, Montana, New Mexico, North Dakota, South Dakota, Vermont, West Virginia, and Wyoming are gray. Indiana, Iowa, Kansas, Maine, Maryland, Minnesota, Missouri, Nebraska, New Hampshire, New York, North Carolina, Ohio, Virginia, and Wisconsin are blue. All other states are red.] [Map 9] [Blue:] Super Bowl [Red:] Funeral home [Alaska, Arizona, California, Colorado, Connecticut, Florida, Hawaii, Idaho, Nevada, New Jersey, New York, Oregon, Pennsylvania, Texas, Utah, and Washington are blue. All other states are red.] [Map 10] [Blue:] Resume tips [Red:] Skateboard tricks [Arizona is red. Alaska, Hawaii, Idaho, Maine, Mississippi, Montana, New Hampshire, New Mexico, North Dakota, South Dakota, Vermont, West Virginia, and Wyoming are gray. All other states are blue.] [Map 11] [Blue:] Donald Trump [Red:] What do I do [California, Connecticut, Delaware, Florida, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Oregon, Rhode Island, Vermont, Virginia, Washington, and Wisconsin are blue. All other states are red.] [Map 12] [Blue:] Existential crisis [Red:] Marco Rubio [Alaska is blue. All other states are red.]

Google Trends is a website for visualizing Google search activity by date and region. Used properly, it can give a picture of what topics people are interested in (as evidenced by what they search for) at particular times and in different places. Used improperly, it can simply amplify random noise . Randall has created several Google Trends maps of search activity in the US. Each map colors in states according to which of two (or more) search queries was more popular. As noted at the top of the comic, all of these based on real queries (though not reflecting the same time period across all maps). However, none of them seem to show any especially useful comparisons. States in gray did not return enough data for Google Trends to consider it significant. The title text uses two of these maps to paint a picture of the year 2020 (implying that these search patterns are both meaningful and likely to continue into the future). In this scenario, most of the country continues to read about Marco Rubio (except for Alaskans, still searching for help with their existential crises), and individuals are trying to learn about etiquette, sexting, or both, depending on their location. The least informative Google Trends Maps I've created over the years (All are real but not all cover the same date range) [12 maps of the United States are shown with the states colored. There are labels for the colors.] [Map 1] [Blue:] Frostbite [Red:] Heat stroke [Alabama, Arizona, Arkansas, California, Florida, Georgia, Hawaii, Idaho, Louisiana, Mississippi, Nevada, New Mexico, Oklahoma, Oregon, South Carolina, Tennessee, Texas, Utah, and Washington are red. All other states are blue.] [Map 2] [Blue:] Best church [Red:] Best strip club [Nevada is red. Alaska, North Dakota, and Wyoming are gray. All other states are blue.] [Map 3] [Blue:] Bigfoot [Red:] Mike Pence [Indiana is red. All other states are blue.] [Map 4] [Blue:] Etiquette [Red:] Sexting [Alabama, Alaska, Arkansas, Delaware, Hawaii, Iowa, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, North Dakota, Ohio, South Dakota, Tennessee, Vermont, and West Virginia are red. All other states are blue.] [Map 5] [Blue:] Little dog [Red:] Big cat [Arizona, Arkansas, California, Colorado, Idaho, Iowa, Maine, Mississippi, Nebraska, Nevada, New Jersey, New Mexico, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, and Wyoming are blue. All other states are red.] [Map 6] [Blue:] Shark attack [Red:] Childbirth [California, Connecticut, Delaware, Florida, Georgia, Kentucky, Louisiana, Maine, Massachusetts, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Virginia, and West Virginia are blue. All other states are red.] [Map 7] [Blue:] Snakes [Red:] Ants [Yellow:] Bees [Green:] Alligators [Florida is green. Iowa, Maine, Massachusetts, Minnesota, Montana, Nevada, New Jersey, New Mexico, Oregon, Pennsylvania, and Wisconsin are red. Alaska, Arizona, California, Connecticut, Hawaii, Illinois, Indiana, Michigan, New Hampshire, New York, North Dakota, Ohio, Rhode Island, Utah, Vermont, Washington, and Wyoming are yellow. All other states are blue.] [Map 8] [Blue:] Retirement planning [Red:] Bungee jumping [Alaska, Delaware, Hawaii, Idaho, Mississippi, Montana, New Mexico, North Dakota, South Dakota, Vermont, West Virginia, and Wyoming are gray. Indiana, Iowa, Kansas, Maine, Maryland, Minnesota, Missouri, Nebraska, New Hampshire, New York, North Carolina, Ohio, Virginia, and Wisconsin are blue. All other states are red.] [Map 9] [Blue:] Super Bowl [Red:] Funeral home [Alaska, Arizona, California, Colorado, Connecticut, Florida, Hawaii, Idaho, Nevada, New Jersey, New York, Oregon, Pennsylvania, Texas, Utah, and Washington are blue. All other states are red.] [Map 10] [Blue:] Resume tips [Red:] Skateboard tricks [Arizona is red. Alaska, Hawaii, Idaho, Maine, Mississippi, Montana, New Hampshire, New Mexico, North Dakota, South Dakota, Vermont, West Virginia, and Wyoming are gray. All other states are blue.] [Map 11] [Blue:] Donald Trump [Red:] What do I do [California, Connecticut, Delaware, Florida, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Oregon, Rhode Island, Vermont, Virginia, Washington, and Wisconsin are blue. All other states are red.] [Map 12] [Blue:] Existential crisis [Red:] Marco Rubio [Alaska is blue. All other states are red.]

Panama Canal

Panama Canal

https://www.xkcd.com/2127

https://www.explainxkcd.com/wiki/index.php/2127:_Panama_Canal

[Cueball is standing in front of a poster with two maps showing the Americas. He is pointing to the right one with a stick he is holding in his hand. Specifically to the red line going through the Americas from the Arctic sea above Canada near Alaska, down through North America, through the middle of Central America down through the middle of South America to end up in the Antarctic sea below the tip of South America. On the map to the left there is a similar red line indicating the Panama Canal crossing the thinnest part of Central America from the Pacific Oceanto the Atlantic Ocean. Both lines end in small dots on either "side" of the continent. The two maps have labels above them:] Atlantic-Pacific option Arctic-Antarctic option [Caption below the panel:] I still don't understand why the Panama Canal planners rejected my proposal.

The Panama Canal is, as the name suggests, a canal through the country of Panama. It is important for bridging the Atlantic and Pacific oceans, and is an important trade route. The canal is in Panama because this is the narrowest piece of land for crossing between the two oceans. When the Panama Canal was being proposed, several alternate routes were suggested such as the recently-revived Nicaragua Route . Cueball says that when the Panama Canal connecting the Caribbean Sea to the Pacific Ocean was being planned, he proposed an alternate route that connects the Arctic Ocean to the Great Southern Ocean . At the time, the northern terminus would have been inaccessible, because the Arctic Ocean was almost completely covered by ice. His suggested route runs somewhat to the east of the continental divide and has a total length of slightly over ten thousand miles, in contrast to the real-life canal which is only fifty miles long. The extra length and more-rugged terrain make his proposal much more difficult to build and maintain than the real-life Panama Canal. [ citation needed ] Moreover, while the real-life canal significantly shortens the travel distance between major cities on the east and west coasts of the Americas, his alternative offers little benefit over traveling north or south in either the Atlantic or Pacific oceans. In fact, with the lack of currents that can aid travel and the slow speed required to traverse canal locks, it would be significantly slower. In addition, ships would have to wait approximately 100 years for global warming to melt the ice in the Arctic Ocean along the northern coast of North America sufficiently for them to enter or exit the northern end of the canal. (However, since construction of this canal might take even longer, the ice might not be a problem by the time it was completed.) The title text references the now-existing Panama Canal, and the fact that Randall's canal would need to cross it at some point. The title text suggests that crossing two canals would have to be done via aqueduct , instead of the more useful at-grade crossing , most likely at Gatun Lake , which would allow boats to travel between the two canals by simply connecting them. The humor here is that this canal would be one of the most ambitious construction projects in history; an aqueduct being added to the costs is an expense on the same scale of needing an extra screw to hold something in on Apollo 11. The route depicted appears to cross the Mackenzie, Missouri, Rio Grande, and Amazon rivers anyway, so only this additional crossing is apparently "unreasonable." [Cueball is standing in front of a poster with two maps showing the Americas. He is pointing to the right one with a stick he is holding in his hand. Specifically to the red line going through the Americas from the Arctic sea above Canada near Alaska, down through North America, through the middle of Central America down through the middle of South America to end up in the Antarctic sea below the tip of South America. On the map to the left there is a similar red line indicating the Panama Canal crossing the thinnest part of Central America from the Pacific Oceanto the Atlantic Ocean. Both lines end in small dots on either "side" of the continent. The two maps have labels above them:] Atlantic-Pacific option Arctic-Antarctic option [Caption below the panel:] I still don't understand why the Panama Canal planners rejected my proposal.

New Robot

New Robot

https://www.xkcd.com/2128

https://www.explainxkcd.com/wiki/index.php/2128:_New_Robot

[Ponytail is standing on a raised platform with a robot behind her, talking to someone off-screen. The spherical floating robot is equipped with a grappling gun and an antenna that "zaps" a lightning bolt at the floor below it.] Robot: ZAP Ponytail: Our robot floats using a helium sphere, which is highly charged and can induce lightning strikes. Ponytail: It moves using a grappling gun like the hook shot from Zelda . Off-screen voice: What is the robot for ? Ponytail: Uh Ponytail: It could help with search and rescue after disasters. [Caption below the panel:] "It could help with search and rescue" is engineer-speak for "we just realized we need a justification for our cool robot."

The comic is a commentary on how many robots and engineering products are labeled as being for “Search and Rescue” purposes. Search And Rescue (SAR) involves entering an unknown, possibly hazardous disaster-stricken environment, identifying humans or other items of interest which may be hidden, partly (or completely) buried, or injured, and then figuring out how to safely extract the target and deliver it to safety. These tasks are hard enough for humans and are even more challenging for robots, which generally work better in well-controlled situations. This is why many robot challenges are themed around search-and-rescue; the techniques that are developed for handling such challenging circumstances can be applied to make other robots (such as robotic caretakers, autonomous cars, AI-assisted medicine, and other lucrative applications) more robust. The comic may be remarking that 'search and rescue' may be used as a cover for developing robots that will actually be tasked to 'search and destroy'. (See: lethal autonomous weapons .) Although search-and-rescue is a function that militaries perform, a robot that can satisfactorily perform a search-and-rescue task can easily be adapted to more destructive purposes. Randall has previously written about his concerns about human authorities misusing military robots in 1968: Robot Future . The joke is that the group of engineers who built the robot did it just because it would be cool to have a robot that can induce lightning strikes and has a grappling gun like the hook shot from (The Legend Of) Zelda. Realizing that they need to have an actual purpose for the robot the engineer presenting the robot makes up the reason that it could be used for search and rescue operations. The grappling gun can be used to pull people out or supply food to people stuck in a place. In the case that there is a dangerous amount of charge present in the atmosphere lightning can be induced which will protect other objects and people from lightning. Also, the helium sphere can allow the balloon to float in places that are hard to reach. (Another possible interpretation is that the question "What is the robot for?" meant why do the helium sphere and grappling gun need to have a robot — and the answer means that the robot is to rescue those who are hit by either the lighting or the grappling gun.) The Hookshot is a type of grappling hook that is a recurring piece of equipment in The Legend of Zelda video game franchise, first appearing in the 1991 game The Legend of Zelda: A Link to the Past . It is a machine consisting of a chain and hook, which can be used by Link , the protagonist and player character of Zelda . When used, the chain extends and sends the hook attached to it towards its target. If the hook latches onto certain objects, Link reels himself in towards that object. Link can also use it to pull enemies and objects towards him. Although it is referred to by the traditional 'Hookshot' name, the traditional Hookshot involves a bladed tip that mounts in wood; the grappling gun equipped on the robot is more reminiscent of the later Clawshot , which grasps its target on contact. In theory, the Hookshot-esque function of the robot could be used for anchoring purposes - a useful function for a flying robot in search-and-rescue situations. If it is using a Clawshot design, it could also conceivably seize the parties in need of rescue. However, merely by comparing the grappling device to the Hookshot, it is clear that its attachment was specifically designed in an effort to replicate the game's tool. The title text ominously suggests that since there are more rescue robots than required for the number of people needing rescue, another robot project will be used to place people in need of rescue, or destroy search-and-rescue robots. (Even more ominously, it is possible that this may be the project that creates a need for rescue, as the fires caused by the lightning strikes could be the disaster from which rescue is needed.) [Ponytail is standing on a raised platform with a robot behind her, talking to someone off-screen. The spherical floating robot is equipped with a grappling gun and an antenna that "zaps" a lightning bolt at the floor below it.] Robot: ZAP Ponytail: Our robot floats using a helium sphere, which is highly charged and can induce lightning strikes. Ponytail: It moves using a grappling gun like the hook shot from Zelda . Off-screen voice: What is the robot for ? Ponytail: Uh Ponytail: It could help with search and rescue after disasters. [Caption below the panel:] "It could help with search and rescue" is engineer-speak for "we just realized we need a justification for our cool robot."

1921 Fact Checker

1921 Fact Checker

https://www.xkcd.com/2129

https://www.explainxkcd.com/wiki/index.php/2129:_1921_Fact_Checker

[In a panel with light-gray background is a block of text:] An investigator claims to have discovered in some dusty archives that back in the days when the Pilgrims landed each person coming to America from England was required to bring with them eight bushels of corn meal, two bushels of oatmeal, two gallons of vinegar and a gallon each of oil and brandy. In view of the fact that nothing of importance hinges on the truth or falsity of this statement, not much time need be consumed to ascertain whether this is truth or fiction. —Kansas City Sun Friday, May 6 th , 1921 [Caption below the panel] I have a grudging respect for this 1921 newspaper fact-checker.

This comic shows a 1921 newspaper article with information about the Pilgrims coming to America. Randall has a 'grudging respect' for the author, who feels the information is so unimportant that no fact-checking has been done, and has enough integrity to inform the reader of this. The Kansas City Sun referenced by the comic was a newspaper in Kansas City, Kansas that ran from 1892 to 1924(?). (Interestingly, there was also a Kansas City Sun in Kansas City, Missouri that ran from 1908 to 1924.) PolitiFact , mentioned in the title text, is a fact-checking project which evaluates the truth or falsity of various statements made by politicians and other people involved in U.S. politics. The positions on its rating scale are "True", "Mostly True", "Half True", "Mostly False", "False", and "Pants on Fire", the last position being reserved for the most egregiously "false" claims. "Mostly Whatever", the rating identified in the title text, is presented by Randall as a rating that could apply to claims that have so little relevance or interest that they are not worth checking. See also 1712: Politifact . [In a panel with light-gray background is a block of text:] An investigator claims to have discovered in some dusty archives that back in the days when the Pilgrims landed each person coming to America from England was required to bring with them eight bushels of corn meal, two bushels of oatmeal, two gallons of vinegar and a gallon each of oil and brandy. In view of the fact that nothing of importance hinges on the truth or falsity of this statement, not much time need be consumed to ascertain whether this is truth or fiction. —Kansas City Sun Friday, May 6 th , 1921 [Caption below the panel] I have a grudging respect for this 1921 newspaper fact-checker.

Industry Nicknames

Industry Nicknames

https://www.xkcd.com/2130

https://www.explainxkcd.com/wiki/index.php/2130:_Industry_Nicknames

[A line chart is shown going from left to right between two small vertical stop lines. On the line are eight dots spread out unevenly from close to each end. The most central dot is the one with furthest distance to the nearest dots, having almost the same distance in both direction the nearest dots. The other dots are in some cases very close. Beneath each dot there goes a line down to a label written beneath each line. Above the chart there is a big title and below that an explanation. Below that again, there is a small arrow pointing to the right with a label above it.] Nicknames for Industries and Organizations Ranked by how silly it sounds when you say someone is "In the pocket of..." [Arrow label:] Sillier [Labels for the eight dots from left to right:] Cigarette companies: "Big Tobacco" Drug companies: "Big Pharma" The farming industry: "Big Ag" Automakers: "Big Car" The International Equestrian Federation: "Big Horse" The Board of Podiatric Medicine: "Big Foot" The mining industry: "Big Hole" The American Egg Board: "Big Egg"

"Big industry" is a common nickname used to describe monopolistic or near-monopolistic practices in the United States. To be "in someone's pocket" means this person can readily influence the subject's behavior, whether by bribe, blackmail, law, threat, lobbying, social status, finances, freedoms, or affection. Of the 8 industries listed, Big Tobacco and Big Pharma are nicknames that are commonly used. The mining industry may be referred to in this context by sector, as Big Coal or Big Oil (Randall uses the term "big hole", which sounds similar to these. Most but not all forms of mining involve large holes.) The U.S. automobile industry was until recent decades referred to as "Detroit," later meaning only the Big Three automobile manufacturers before falling out of common usage. Big Ag is sometimes used to describe the farming and agricultural industry, and while the rest are purely fictional, Randall could be imagining a possible future in which these industries become big players in the political arena. "Big Foot" is likely a reference to the mythical creature Bigfoot . Those who have been on the rough end of how large organizations can push not only individuals but entire communities around in a mafia-like way may take issue with a medical board being equated with such groups. Chansey , mentioned in the title text, is a type of female-only Pokémon who carries around an egg in her marsupial-like front pouch. For Chansey the phrase "in the pocket of Big Egg" would be rather literal, except that the egg is in her pocket, rather than the other way around. Randall does not specify why Chansey would be a "threat" or why a Pokémon would be bribing people. Perhaps because, if being in the pocket of Big Egg is bad, and Big Egg is in the pocket of Chansey, then Chansey controls Big Egg and is the one to worry about. [A line chart is shown going from left to right between two small vertical stop lines. On the line are eight dots spread out unevenly from close to each end. The most central dot is the one with furthest distance to the nearest dots, having almost the same distance in both direction the nearest dots. The other dots are in some cases very close. Beneath each dot there goes a line down to a label written beneath each line. Above the chart there is a big title and below that an explanation. Below that again, there is a small arrow pointing to the right with a label above it.] Nicknames for Industries and Organizations Ranked by how silly it sounds when you say someone is "In the pocket of..." [Arrow label:] Sillier [Labels for the eight dots from left to right:] Cigarette companies: "Big Tobacco" Drug companies: "Big Pharma" The farming industry: "Big Ag" Automakers: "Big Car" The International Equestrian Federation: "Big Horse" The Board of Podiatric Medicine: "Big Foot" The mining industry: "Big Hole" The American Egg Board: "Big Egg"

Emojidome

Emojidome

https://www.xkcd.com/2131

https://www.explainxkcd.com/wiki/index.php/2131:_Emojidome

[This was an interactive and dynamic comic during April 1st from its release until its completion. But the final and current image, will be the official image to transcribe. But the dynamic part of the comic as well as the "error image" displayed to services that could not render the dynamic comic is also transcribed here below.] [The final picture shows the winner of the gold medal in the Emojidome bracket tournament, as well as the runner up with the silver medal. There is no text. The winner is the "Space", "Stars" or "Milky Way" emoji, which is shown with a blue band on top of a dark blue band on top of an almost black background, indicating the light band of the Milky Way in the night sky. Stars (in both five point star shape and as dots) in light blue are spread out in all three bands of color. The large gold medal with its red neck string, is floating close to the middle of the picture, lacking any kind of neck in space to tie it around. To the left of the gold medal is the runner up, the brown Hedgehog, with light-brown face. It clutches the smaller silver medal, also with red neck string, which floats out there in space. The hedgehog with medal is depicted small enough to fit inside the neck string on the gold medal.] [This is an example of how the comic appeared during the competition. The example includes one of the final winner, Space's, matches. The dynamic part of the comic is transcribed below:] [At the top center of the comic, the two emojis battling it out are shown next to each other. The emojis displayed in the comic used the twemoji icon set. A different emoji set was shown in links to image of the tournament brackets. These matches are called bouts in the comic. The emoji from the top (or left) of the bracket is shown to the left. In this case it was space, night sky, milky way or stars vs Maglev train. Between them is the following text:] VS [There are two buttons one below each of the two emoji. If pressed the buttons became red. They could be pressed multiple times each match. The buttons have text on them:] Vote Vote [From the buttons colored hearts are released, often in bundles, and then they wave up across the emoji who's button they emanated from.] [Below the buttons there is and indicator showing how long the current battle is open for further votes. In the example the text is:] Remaining time: 24 minutes [The time began at "26 minutes" during the final rounds. It changed to "1 minute", with 1 minutes and 30 seconds left, and then 30 seconds later to "60 seconds" counting down to a few seconds. Then, before reaching 2 or 3 seconds it changed (a bit too early) to "Time's up!" Shortly there after a new bout would begin.] [Above the two emoji at the very top is a comment. The commentator is shown as a robot emoji. The comment often changed during the long final rounds. In the current example the text is:] "~future~" [But there would have been several others during the match. Given that Space won the entire Emojidome, the train lost this match. Often a final comment was posted just as the result was in. These final messages was then put at the top of the list of past bouts (matches). These bouts was displayed at the bottom of the comic below the remaining time. To the left was the following text:] Past bouts: [Below this text was a list of all previous matches, showing the two emojis, with the loser grayed out, with their final comment next to them. As soon as there where more than three a scroll bar appeared to the right, making it possible to scroll down through all these previous matches. As it was 512 emojis to begin with, there were 256 bouts in the first round, and then 255 the rest of the way to the final for a total of 511 bouts at the end. Here are the the text of the three matches that can be seen in the example (the grayed out loser was Sushi, Bee and Wizard):] 🌋 vs 🍣 "Sushi has received a technical disqualification for being very very cooked" 🐝 vs 🦉 "Owls well that ends well" 🦔 vs 🧙 "The Wizard didn't do it" [All the final bouts remarks, as well as the match ups, the score of votes, and all the other comments coming at the top during each bout can be found below in the round 1 to round 9 sections. They are thus not only a transcript.] [Finally at the bottom of the comic below the scroll-able version of the past bouts, there was a link to images of the brackets, beginning with the full long one of all 512 emojis, and the zooming in and out, plus updating with results along the way. The link was a text that explained what the link was for. In the current example the link text, which is link blue, was:] Full bracket for today's comic (round 3). [This is the image that appears when JavaScript fails or other errors occur. This is what embeds and automated programs usually see, as they load down dynamic comics. The transcript for this image is below the image:] [A tournament bracket tree is shown with eight participants each on the left and right side, for a total of sixteen, all of which are the 😰 emoji ("Face With Open Mouth and Cold Sweat"). From both sides towards the middle the brackets reduce to eight, then four, two, and one line where the latter join to a rectangle in the middle. Below is an explanation of why this is seen instead of the correct comic. It is due to an error with JavaScript. This is also why the sad emoji is used in all sweet sixteen places.] Visit xkcd.com to participate If you are on xkcd.com, then you're seeing this because of something something JavaScript. Listen, websites are hard 😰

This was the ninth April fools' comic released by Randall . The previous fools comic was 1975: Right Click from Sunday April 1, 2018. The next became 2288: Collector's Edition , which was delayed two days and released on Friday April 3, 2020. The interactive comic began at noon ET (16:00 UTC) on April 1, 2019, and ended a day later. In it, users were shown two emojis and voted for their favorite before the time ran out. 512 different emojis were paired against each other in a cup or bracket system, with only one winner. See more below under How it worked . Brackets - like the one in this comic, for finding the best emoji - are a recurring theme in xkcd. It is also relevant for this time of year, and two years ago in 2017, the first comic in April, 1819: Sweet 16 from April 3rd was a bracket, referencing March Madness . The 2019 version of the National Collegiate Athletic Association College basketball national championship tournament began March 19th and ends April 8th 2019. So this comic could also be said to reference this, although it is not so explicit here. Earlier Randall made another large and "silly" bracket in 1529: Bracket (which someone then actually made into an online voting system, just like in this comic). The title is a reference to the movie Mad Max Beyond Thunderdome , which had the tagline: "Two men enter. One man leaves." The "Thunderdome" in the film is a gladiatorial arena where conflicts are resolved by a duel to the death. In the final round, the Milky Way emoji (🌌) won against the Hedgehog emoji (🦔). The comic was updated to show the result. Clicking the comic links to a bracket of 128 emojis showing the winners: https://xkcd.com/2131/emojidome_bracket_round_of_128.png In the first round, the voting period for each bout lasted 37.5 seconds. The voting period for each bout doubled for the second, third, and fourth rounds. The voting period for each bout for the fifth round through the end was 26 minutes. The entire bracket took 24 hours 6 minutes. Remaining time of a given bout was shown on a timer beneath the voting buttons. If the time remaining was one minute or greater, the time was shown rounded to the nearest minute (e.g., "Remaining Time: 26 minutes"); thus the minute would change on the half minute (e.g., "2 minutes" changed to "1 minute" at 1 minute 30 seconds). If the time remaining was less than a minute, the time was shown in seconds (e.g., "59 seconds"). When there were two (sometimes three) seconds remaining, the timer would display "Time's Up!" through the end of the bout and for a couple of seconds after the end of the bout while the images for the next bout were loading. Then the next bout would appear and the results of the previous bout would be added to the list of past bouts, with the most recent bout at the top. Commentary was displayed above the images for each bout, and changed occasionally through the bout. In the first round, the commentary was made up of some stock phrases with a few custom phrases mixed in. Later commentary was tailored to suit each match-up and provided live updates on how each bout was progressing. A final comment was included in the list of past bouts. The competing candidates were periodically overlaid with colored hearts that floated up from the vote button oscillating in a triangle wave pattern before disappearing above the candidate. Below the current competition, the results of past bouts were shown with the "loser" displayed in greyscale, the winner in color, and the final robot-commentator comment on that match. The commentary appeared to suggest that there was some real-time feedback from the results of the competition. For instance, "It seems like our friends over Australia is joining the fun" appeared in the commentary. So did "We are getting a lot of questions on this today. This is live commentary, folks." https://i.imgur.com/8kPwjou.png , directly declaring that the commentary is live. Note that the schedule might show different emoji pictures than the main voting screen, presumably because of fonts. The image is pre-rendered. The competing candidates are chosen in order of Unicode value at first, resulting in similar emojis being compared. Examples include: 😜 squaring off against 😛 - two emojis playfully sticking their tongues out 🤩 squaring off against 😍 - two smiling emojis with symbols for eyes 😂 squaring off with 🤣 - two emojis that are crying in laughter/joy. The original title text "🤼🤼🤼🤼🤼🤼🤼🤼" consisted of eight wrestler emojis. This likely represented the round of 8, where the eight winners then can turn to the winner next to them and continue the quarterfinals, etc. The title text was updated after the final round. Notably, it appears the eggplant emoji (🍆) and the peach emoji (🍑) were left out of the bracket, alongside the middle finger emoji (🖕). The eggplant and peach are frequently used to represent a penis and vulva/buttocks, respectively. There has been no statement from Randall on why they were left out. A robot face announcer-emoji (🤖) and a link to the full bracket was added at 38 minutes in. https://www.xkcd.com/2131/emojidome_bracket.png shows 512 emojis in a single-elimination tournament. https://www.xkcd.com/2131/emojidome_bracket_256.png was added later and shows the 256 emojis that competed on the second round. https://www.xkcd.com/2131/emojidome_bracket_round_3.png was added for the third round. https://www.xkcd.com/2131/emojidome_bracket_round_4.png was added for the fourth round. The round 3 bracket was later updated with results during the Volcano vs Owl fight. There was an error where the flying saucer had beaten the stars, which was not the case. A new bracket image was created for the Round of 32 which seems to be updated with new results as they come in. https://www.xkcd.com/2131/emojidome_bracket_round_of_32.png It is not clear how the winner is decided when both emojis tied for first. This has happened twice: in Cupcake vs. Birthday Cake (🧁 vs. 🎂) with 3658 points each, where the Birthday Cake (🎂) was declared winner, and in the very first match of Grinning Face vs. Grinning Face With Smiling Eyes (😀 vs. 😁), in which no votes were cast, but the Grinning Face With Smiling Eyes (😁) was declared winner. Both of these tied bouts occurred in round 1, and both declared winners lost their subsequent match in round 2. Real data with results (clicks) can be seen as JSON-websocket at https://emojidome.xkcd.com/2131/socket , transposed into a more human-readable format at https://leet.nu/tmp/xkcd-2131.html . https://phiresky.github.io/emojidome/ , made by a redditor , shows the brackets along with the final scores and comment. [This was an interactive and dynamic comic during April 1st from its release until its completion. But the final and current image, will be the official image to transcribe. But the dynamic part of the comic as well as the "error image" displayed to services that could not render the dynamic comic is also transcribed here below.] [The final picture shows the winner of the gold medal in the Emojidome bracket tournament, as well as the runner up with the silver medal. There is no text. The winner is the "Space", "Stars" or "Milky Way" emoji, which is shown with a blue band on top of a dark blue band on top of an almost black background, indicating the light band of the Milky Way in the night sky. Stars (in both five point star shape and as dots) in light blue are spread out in all three bands of color. The large gold medal with its red neck string, is floating close to the middle of the picture, lacking any kind of neck in space to tie it around. To the left of the gold medal is the runner up, the brown Hedgehog, with light-brown face. It clutches the smaller silver medal, also with red neck string, which floats out there in space. The hedgehog with medal is depicted small enough to fit inside the neck string on the gold medal.] [This is an example of how the comic appeared during the competition. The example includes one of the final winner, Space's, matches. The dynamic part of the comic is transcribed below:] [At the top center of the comic, the two emojis battling it out are shown next to each other. The emojis displayed in the comic used the twemoji icon set. A different emoji set was shown in links to image of the tournament brackets. These matches are called bouts in the comic. The emoji from the top (or left) of the bracket is shown to the left. In this case it was space, night sky, milky way or stars vs Maglev train. Between them is the following text:] VS [There are two buttons one below each of the two emoji. If pressed the buttons became red. They could be pressed multiple times each match. The buttons have text on them:] Vote Vote [From the buttons colored hearts are released, often in bundles, and then they wave up across the emoji who's button they emanated from.] [Below the buttons there is and indicator showing how long the current battle is open for further votes. In the example the text is:] Remaining time: 24 minutes [The time began at "26 minutes" during the final rounds. It changed to "1 minute", with 1 minutes and 30 seconds left, and then 30 seconds later to "60 seconds" counting down to a few seconds. Then, before reaching 2 or 3 seconds it changed (a bit too early) to "Time's up!" Shortly there after a new bout would begin.] [Above the two emoji at the very top is a comment. The commentator is shown as a robot emoji. The comment often changed during the long final rounds. In the current example the text is:] "~future~" [But there would have been several others during the match. Given that Space won the entire Emojidome, the train lost this match. Often a final comment was posted just as the result was in. These final messages was then put at the top of the list of past bouts (matches). These bouts was displayed at the bottom of the comic below the remaining time. To the left was the following text:] Past bouts: [Below this text was a list of all previous matches, showing the two emojis, with the loser grayed out, with their final comment next to them. As soon as there where more than three a scroll bar appeared to the right, making it possible to scroll down through all these previous matches. As it was 512 emojis to begin with, there were 256 bouts in the first round, and then 255 the rest of the way to the final for a total of 511 bouts at the end. Here are the the text of the three matches that can be seen in the example (the grayed out loser was Sushi, Bee and Wizard):] 🌋 vs 🍣 "Sushi has received a technical disqualification for being very very cooked" 🐝 vs 🦉 "Owls well that ends well" 🦔 vs 🧙 "The Wizard didn't do it" [All the final bouts remarks, as well as the match ups, the score of votes, and all the other comments coming at the top during each bout can be found below in the round 1 to round 9 sections. They are thus not only a transcript.] [Finally at the bottom of the comic below the scroll-able version of the past bouts, there was a link to images of the brackets, beginning with the full long one of all 512 emojis, and the zooming in and out, plus updating with results along the way. The link was a text that explained what the link was for. In the current example the link text, which is link blue, was:] Full bracket for today's comic (round 3). [This is the image that appears when JavaScript fails or other errors occur. This is what embeds and automated programs usually see, as they load down dynamic comics. The transcript for this image is below the image:] [A tournament bracket tree is shown with eight participants each on the left and right side, for a total of sixteen, all of which are the 😰 emoji ("Face With Open Mouth and Cold Sweat"). From both sides towards the middle the brackets reduce to eight, then four, two, and one line where the latter join to a rectangle in the middle. Below is an explanation of why this is seen instead of the correct comic. It is due to an error with JavaScript. This is also why the sad emoji is used in all sweet sixteen places.] Visit xkcd.com to participate If you are on xkcd.com, then you're seeing this because of something something JavaScript. Listen, websites are hard 😰

Percentage Styles

Percentage Styles

https://www.xkcd.com/2132

https://www.explainxkcd.com/wiki/index.php/2132:_Percentage_Styles

Percentage styles in order of acceptability [A long vertical line is shown with five dots on it.] [Label at the top:] Best [Dot labels from top to bottom:] 65% [very short distance] 65 percent [at roughly quarter scale] 65 per cent [at roughly half scale] Sixty-five% [at the end] 65 per¢

On March 29, 2019, The AP Stylebook changed a long-standing rule that forbade press writers from using the percent sign (%) when writing percentages. This had long been a controversial rule, leading to much debate over the preferable way to write percentages, before the Associated Press finally conceded the point. The comic lists the best to worst ways in which you can write out phrases that are phonetically the same as "65%". They go from the common "65%" and "65 percent" to "65 per cent," which is not common in Randall's area and time, to the eccentric "sixty-five%" and "65 per¢" (using the cent currency symbol) which are not used in normal writing and would stand out like a sore thumb when read. The middle option, "65 per cent", was common in older literature, along with "65 per cent.", using "cent." as an abbreviation for "centum", which is Latin for "hundred". ("per" in Latin translates to "through", "for", and several other English prepositions.) The entire string would translate to "65 for every hundred." "Per cent" is more widely used in British English than in American English today. A small gap between the ends of the bar and the best and worst options may suggest the existence of even better and worse options not listed in this comic, such as "6ty5/¢". Other abbreviations not mentioned in the comic include "pct.", "pct" or "pc". See Percentage . The title text references the ambiguity of hard and soft C in English. In Classical Latin, "C" is always pronounced like "K". However, in English, most "C"s before E, I and Y (including "percent") are soft, and pronounced like "S". In academia, Latin students are taught the Classical Latin pronunciations of words , rather than the pronunciation used by the Catholic church. Some students of Latin may adopt the Latin pronunciation of English words derived from Latin. Such people may tend more to pronounce, even when not the correct choice, "celtic" like "keltic" (this is the correct choice, except for the basketball team ), "caesar" like "kaiser", or "cent" like "kent" (although since this involves obviously saying something others aren't going to understand unless they took the same classes, it might as well be "per kentum"). People sometimes train a cat out of a bad behavior, such as scratching upholstery, by spritzing the cat with water when the cat does the undesired behavior. In this case, Randall's friends found him so annoying they trained him out saying "per kent" by spraying him with water every time he pronounced it that way. Training people this way was previously a punchline in 220: Philosophy , while training a cat this way was previously a punchline in 1786: Trash . 65% This is the standard way of writing percentages. Randall's approval acceptability is 98%. 65 percent This one has no space, it is more common in American English. Rating: 97 percent 65 per cent This one has a space, it is more common in British English. Rating: 86 per cent Sixty-five% This one writes out the number, but not the percent sign. Rating: Sixty% 65 per¢ This one uses the cent symbol in place of the word cent, which is incorrect in this context, as cent here does not refer to a currency. Rating: 2 per¢ Percentage styles in order of acceptability [A long vertical line is shown with five dots on it.] [Label at the top:] Best [Dot labels from top to bottom:] 65% [very short distance] 65 percent [at roughly quarter scale] 65 per cent [at roughly half scale] Sixty-five% [at the end] 65 per¢

EHT Black Hole Picture

EHT Black Hole Picture

https://www.xkcd.com/2133

https://www.explainxkcd.com/wiki/index.php/2133:_EHT_Black_Hole_Picture

[Cueball is standing behind a lectern, with "Press Conference" and the EHT logo displayed on a projector screen behind him.] Cueball: We linked up our observatories, got everything aligned, and there it was: Cueball: The first image of a black hole! [Zoom in on Cueball. A question is asked from off panel.] Off-panel question: Can you share the picture? Cueball: Well, here's the thing... [Cueball lifts his arm holding his hand with its palm up.] Cueball: Turns out our telescope feed is like Pinterest, where you can't right-click to save an image. Cueball: So we tried to take a screenshot, but the key combination kept turning off the display instead. [Zoom back out to show that the image on the projector screen has changed to show a blurry picture of a white computer screen against a black background. The EHT logo remains at the bottom of the projector screen.] Cueball: I grabbed my phone and tried to take a picture of the screen, but I was too slow. The observation had ended. Cueball: We're planning to try again next year, and we'll definitely record the screen this time.

This comic references the Event Horizon Telescope , an international project dedicated to imaging black holes Sagittarius A* and M87* with angular resolution comparable in size to their event horizons. The first image of M87 was released to the public on Wednesday, April 10, 2019, five days after this comic's release, and appeared on the same day in the comic 2135: M87 Black Hole Size Comparison . The image was produced from data gathered since 2006, collected by over a dozen radio telescopes around the world and combined through a process called interferometry . Normally, a telescope's resolution is limited by the size of its aperture, but by recording radio signals at multiple sites, the minute differences between the signals can be digitally processed into an image with much higher resolution. The telescopes used for the EHT are in Hawaii, North and South America, Europe, and Antarctica, and so the effective diameter of the collective EHT is almost the size of the Earth itself. As each telescope recorded observations of the black holes, the results were written to hard drives and mailed to observatories at MIT and the Max Planck Institute for Radio Astronomy for processing. Astronomical recordings can involve astronomical amounts of data, so the raw, original, feed from a telescope may never be stored if it is too dense -- it is instead processed live by computers to capture the information of interest, and the processed result is stored. The first image released by the EHT was expected to be in April 2017, but unforeseen events delayed it by two years, to April 2019. Randall predicts this trend will continue, and makes a joke by analogy to real-world difficult experiences capturing important moments. Luckily this comic was not in any way prophetic, and five days after this comic was released the EHT team released a black hole picture for the world to enjoy. The comic shows Cueball giving a press conference on the recent photographing of a black hole. However, the photograph is a disappointment, caused by the spectacular failure of several systems: Obviously, it would be quite impractical to fail to reliably provide this in an astronomical system. Cueball describes the system as being like Pinterest , where JavaScript prevents you from right-clicking on an image so that you could save it (or at least attempts to, there are many workarounds). Cueball states that they then tried to take a screenshot, but the key combination to make a screenshot instead turned off the monitor where the picture was being displayed whenever they tried to use it, requiring extra time and effort each attempt in order to return to the view of the black hole. This could reference the fact that many mobile devices incorporate the power button in their screen shot combination and the power button can also turn off the screen. Laptops and operating systems may also have undocumented key combinations that blank the screen, which users can accidentally press when in a hurry and create further stress for themselves. Content under DRM may also prevent screenshots, and attempting to screenshot a protected video will result in a black image. As a last act of desperation, Cueball took out his phone and attempted to take a photo of the screen showing the black hole, but by that time, the observation had ended, and the photo was lost. In reality, none of this should be an issue as the picture would be immediately saved by the system and would not need to be downloaded from the site, but NASA especially knows that developers of a system can never predict the obscure happenstances that can combine to create failure at the end. Cueball then states that they would try to take a picture of a black hole again next year. The title text explains that (after presumably five years of annual tries), the picture failed again as the telescope was too zoomed in and only captured a featureless square. Since a black hole by definition returns no light sent to it, the photograph would be entirely black. Researchers however are primarily presumably trying to obtain images of the more interesting edge known as an accretion disc , which could actually be meaningfully photographed. The joke is that the black hole could only be photographed once a year, and in each year some incidental set of mistakes combined to prevent the photograph from actually being shared with anybody. This could be a reference to the cosmic censorship hypothesis , which states that a "naked" singularity cannot be viewed from outside an event horizon, where in this case the censor is some kind of "butterfly of doom" that bedevils astronomers who attempt to image one anyway, similar to some interpretations of the Novikov self-consistency principle (a possible resolution to various time travel paradoxes which asserts that any event which would lead to a paradox must have probability zero). [Cueball is standing behind a lectern, with "Press Conference" and the EHT logo displayed on a projector screen behind him.] Cueball: We linked up our observatories, got everything aligned, and there it was: Cueball: The first image of a black hole! [Zoom in on Cueball. A question is asked from off panel.] Off-panel question: Can you share the picture? Cueball: Well, here's the thing... [Cueball lifts his arm holding his hand with its palm up.] Cueball: Turns out our telescope feed is like Pinterest, where you can't right-click to save an image. Cueball: So we tried to take a screenshot, but the key combination kept turning off the display instead. [Zoom back out to show that the image on the projector screen has changed to show a blurry picture of a white computer screen against a black background. The EHT logo remains at the bottom of the projector screen.] Cueball: I grabbed my phone and tried to take a picture of the screen, but I was too slow. The observation had ended. Cueball: We're planning to try again next year, and we'll definitely record the screen this time.

Too Much Talking

Too Much Talking

https://www.xkcd.com/2134

https://www.explainxkcd.com/wiki/index.php/2134:_Too_Much_Talking

[Cueball is walking into the panel from the right] Off-screen: How was the party? Cueball: Taaalkiiiiiiing Cueball: Blablablabla Cueball: I talked so much. Too much? Probably. Cueball: My face is tired. [Cueball moving to retreat under a bed] Cueball: So many conversations. Cueball: I'm worried that all my opinions are bad. Why did I talk so much? Cueball: Time to hide under my bed and never speak to another human again. [The bed is shown, presumably with Cueball under it.] Five minutes later... [Cueball crawling out from under the bed] Cueball: I have some new opinions. Off-screen: That didn't take long.

Cueball has recently returned from a party, something which is unusual since Cueball has mostly been shown as an introverted type. Like most introverts, social interactions and obligations have worn him out, and different from most after-party regrets, he appears to have "talked too much." While at the party, he has likely expressed opinions that might be rejected or seen as embarrassing by his social circle or society as a whole, and is now remorseful and embarrassed he said such things. In his shame, he recedes under his bed, but evidently he finds new opinions to feel strongly about, and quickly returns to society. The title text presents a suggestion that will likely not go over well, as forcing those at a party to quietly listen to you is a great way to kill the party. It also does not allow others to respond to said opinions before moving on to the next. [Cueball is walking into the panel from the right] Off-screen: How was the party? Cueball: Taaalkiiiiiiing Cueball: Blablablabla Cueball: I talked so much. Too much? Probably. Cueball: My face is tired. [Cueball moving to retreat under a bed] Cueball: So many conversations. Cueball: I'm worried that all my opinions are bad. Why did I talk so much? Cueball: Time to hide under my bed and never speak to another human again. [The bed is shown, presumably with Cueball under it.] Five minutes later... [Cueball crawling out from under the bed] Cueball: I have some new opinions. Off-screen: That didn't take long.

M87 Black Hole Size Comparison

M87 Black Hole Size Comparison

https://www.xkcd.com/2135

https://www.explainxkcd.com/wiki/index.php/2135:_M87_Black_Hole_Size_Comparison

[Caption above the panel:] Size comparison: The M87 Black Hole and Our Solar System [Caption at top left of the panel:] EHT Black Hole Image Source: NSF [An image of the M87 black hole captured by the event horizon telescope on the day that this comic was published is shown, in the shape of a thick red-and-yellow ring on a black background.] [A white ring about 1/4 of the diameter of the central black portion of the image is labelled with an arrow:] Pluto [A small white circle at the center of the image is labelled with an arrow:] Sun [A small white dot on the right hand edge of the central black portion of the image is labelled with an arrow:] Voyager 1

This comic shows the picture of the M87 black hole by the Event Horizon Telescope that was published on the same day as this comic. Overlaid on the picture is a scale image of the Solar System, showing the Sun, Pluto (one of the most well-known dwarf planets ) and its orbital path, and Voyager 1 , a deep-space probe and the current farthest probe from Earth. The comic is quite similar to 1551: Pluto , in which Randall overlaid annotations onto the recently-released first images of Pluto taken by the New Horizons spacecraft. The point of the comic is to celebrate the release of this image by the Event Horizon Telescope, referenced two comics earlier, in 2133: EHT Black Hole Picture , as well as to indicate the hugeness of M87 and the awe-inspiring thing that space is. This image has been widely publicized as being the first image ever of a black hole. Science had no visual evidence of black holes at all until 2012 . In the title text Randall hypothesizes that if the Sun were at the center of M87, Voyager would be outside the event horizon. This is confirmed by a 2015 study in which the Schwartzchild radius of M87* was found to be 5.9x10^-4 pc, as opposed to the distance of 7.04x10^-4 pc, at the time the comic was written, between Voyager 1 and the Sun. The comic's scale seems to be slightly small; while the orbit of Pluto should be about 4.9 microarcseconds across, in the comic it's about 3.9 microarcseconds across. [Caption above the panel:] Size comparison: The M87 Black Hole and Our Solar System [Caption at top left of the panel:] EHT Black Hole Image Source: NSF [An image of the M87 black hole captured by the event horizon telescope on the day that this comic was published is shown, in the shape of a thick red-and-yellow ring on a black background.] [A white ring about 1/4 of the diameter of the central black portion of the image is labelled with an arrow:] Pluto [A small white circle at the center of the image is labelled with an arrow:] Sun [A small white dot on the right hand edge of the central black portion of the image is labelled with an arrow:] Voyager 1

Election Commentary

Election Commentary

https://www.xkcd.com/2136

https://www.explainxkcd.com/wiki/index.php/2136:_Election_Commentary

[Cueball is presenting a graphic on his left that shows two names followed by five digits] Cueball: Smith is leading in 3 of the 5 digits, and is tied in another. But Jones has a solid lead the thousands place, if Smith can't catch up there, it's over. Smith: 5 5 3 8 4 Jones: 5 9 1 0 2 [In each column, the higher number is marked with a check mark and the lower with a cross and greyed out. The fives in the leftmost column are marked "tie"] [Caption below the panel:] A lot of election commentary just consists of unnecessarily convoluted ways to add up who has more votes.

This comic is a joke about the way newscasters commentate elections, and how they make it far more complicated than it needs to be in an election in which the candidate with the most votes wins. It's not uncommon for these methods to be used to imply the election is neck-and-neck long past the point one candidate has an insurmountable lead. Smith has 55384 votes, while Jones has 59102 votes. Instead of comparing the votes as one number, and admitting that Jones' four thousand vote lead is likely going to earn him the win, Cueball compares each digit to see which is larger. Smith's digits in the hundreds, tens, and ones are all higher than Jones', so ultimately he implies that Smith has a chance to win, if only he could pull ahead in the thousands digit and secure a dramatic upset. In reality all that matters is who has the higher total number of votes. It should be noted that for U.S. Presidential elections, the candidate with more votes does not necessarily win. Each state (plus the District of Columbia) gets a certain number of votes, and the victor in those states usually (though not always) receives all of the state's votes. In that specific case, tracking individual victories (though in states, not in digits) is actually highly relevant to who wins. That said, the comic appears be depicting something on a much smaller scale, such as a municipal or district election, which is likely to use the more common most-votes-wins method of election. The title text is a similarly satirical twist on a common news comment during elections. Candidates often employ different strategies during the election season, with varying degrees of success. For example, if a strategy collected many votes (or important votes, see above paragraph), then it could be said that the area it affected was "crucial". Here, the area affected by Jones' strategy (an entire place value) is said to have been crucial — an obvious claim, seeing as greater place values always result in greater amounts indicated. [Cueball is presenting a graphic on his left that shows two names followed by five digits] Cueball: Smith is leading in 3 of the 5 digits, and is tied in another. But Jones has a solid lead the thousands place, if Smith can't catch up there, it's over. Smith: 5 5 3 8 4 Jones: 5 9 1 0 2 [In each column, the higher number is marked with a check mark and the lower with a cross and greyed out. The fives in the leftmost column are marked "tie"] [Caption below the panel:] A lot of election commentary just consists of unnecessarily convoluted ways to add up who has more votes.

Text Entry

Text Entry

https://www.xkcd.com/2137

https://www.explainxkcd.com/wiki/index.php/2137:_Text_Entry

[Ponytail and Cueball are sitting on a couch, with Megan standing behind them. Cueball is pointing a remote at a television. The word space is written inside a frame.] Television: O...U...R...SPACE...P...L... Remote: Click Click Click [Caption below the panel:] The weirdest thing about 2019 is obviously that Donald Trump is president, but I think the second weirdest is that you sometimes still have to type stuff in by picking letters on a screen one at a time with a cursor like you're entering a high score in a 1980s arcade game.

In this comic, Randall remarks upon something that he considers to be an absurdity of modern living; that in spite of our amazing advances in technology, there still exist user interfaces in 2019 where a person has to "pick letters" to type, a somewhat clunky and inefficient method of text entry. This can be seen when doing searches in a TV guide menu or in menus for streaming options like Netflix or Hulu . Some of these menus may allow for voice searches or support bluetooth keyboards , but the traditional method is still to select letters via a cursor. Many controllers for devices only have a few buttons, which makes it necessary to use schemes such as scrolling around a picture of a keyboard to laboriously select letters, making this extremely inconvenient and annoying to users. The fact that these haven't been replaced with better interfaces comes as a surprise to Randall, hence him believing it to be the second most weird thing in 2019. Cueball is probably looking up Our Planet which was a popular Netflix series when this comic was released. Cueball has spelled out "O U R [space] P L" so far. Randall references the " high score " in an arcade game . When achieving a high score in an arcade game, the user typically is able to enter their name or initials into the machine. These are entered by picking letters one by one (and usually under a time limit, for extra fun and/or stress ), as the comic mentions. The title text mentions the keyboard system Dvorak , a recurrent theme on xkcd, which is a keyboard layout patented by August Dvorak and William Dealey . As the Dvorak layout is optimized for more efficient typing with two hands, it is unlikely that using it would be more efficient than a standard Qwerty when limited to cursor entry methods. Another drawback would be that the Dvorak layout is visually unfamiliar to most people, even to many Dvorak typists who rarely look at their keyboard and instead rely on muscle-memory to find keys. As such it could be confusing for users to use for TV selection menus compared to either the more visually familiar Qwerty layout or showing letters in alphabetical order. Alternately, Randall may be referring to Dvorak’s placement of frequently used letters clustered in the center as a potential slight improvement over the linear A-Z layout of such interfaces (a half-measure offered ironically, of course). Although the focus of this comic is on the text entry method, Randall prefaces the comic with what he considers to be the actual weirdest thing about 2019: that Donald Trump is the president of the United States of America. Randall had previously expressed support for Trump's opponent, Hillary Clinton, in the comic 1756: I'm With Her which preceded the 2016 US Presidential Election. In that comic he did not mention Trump. Although several comics may have a relation to Donald Trump becoming president, this is the first time ever , Donald Trump has been mentioned by his full name in a standard xkcd comic. (In 1939: 2016 Election Map he is referred to by his surname). [Ponytail and Cueball are sitting on a couch, with Megan standing behind them. Cueball is pointing a remote at a television. The word space is written inside a frame.] Television: O...U...R...SPACE...P...L... Remote: Click Click Click [Caption below the panel:] The weirdest thing about 2019 is obviously that Donald Trump is president, but I think the second weirdest is that you sometimes still have to type stuff in by picking letters on a screen one at a time with a cursor like you're entering a high score in a 1980s arcade game.

Wanna See the Code?

Wanna See the Code?

https://www.xkcd.com/2138

https://www.explainxkcd.com/wiki/index.php/2138:_Wanna_See_the_Code%3F

[Cueball is walking, talking to Ponytail, who is offscreen.] Cueball: I wrote a script to automate that thing. Ponytail: Oh cool! Ponytail: ...wait, you wrote it? Ponytail: Oh no. [Cueball and Ponytail are standing next to each other and talking.] Cueball: Wanna see the code? Ponytail: I would, if you hadn't said that in the tone of voice of "Wanna see a dead body?" [Same scene as before, except Cueball has his hand on his chin.] Cueball: My code is sort of similar to a dead body, in that you can either come look at it now, or wait a few weeks until it becomes a problem. Ponytail: And because you're lucky that the people around you understand that they create more problems than they solve.

This comic is the fifth and latest comic in the Code Quality series: Cueball declares that he has written a script to automate some (presumably time-consuming or tedious) task, which pleases Ponytail at first... until she remembers how messy Cueball's code tends to be, and gets worried. Cueball offers to show her his code, but Ponytail remarks that it sounds like he's creepily inviting her to see a dead body. Magnanimously, Cueball accepts the comparison, noting that his code does have at least one similarity to a deceased corpse: although unpleasant, if Ponytail allows it to go unchecked, it causes problems which will get increasingly worse over time. In the "dead body" analogy, a recently-deceased corpse is easier to deal with than one that has been left for a few weeks, which will be decayed, unpleasantly smelly, and will likely have attracted disease-spreading vermin. Ponytail then makes a near threatening comment where she says that he is lucky that people understand both that his code causes more problems than it solves and that dead bodies create more problems than they solve. Most likely this means that they understand that killing him would cause more problems than it solves (the problem solved would no doubt be his code). This may be a reference to the concept of technical debt in software development: the idea that an initially poor implementation accrues a sort of "compound interest" over time, becoming increasingly difficult to repair the longer it is left unfixed. This happens because any future development might have to take unorthodox or unrecommended measures to work around the problems that are already there, making the system increasingly complex and fragile the more that is added to it. In the title text, "downstream" has a double meaning, as it is a term that applies to a situation where a dead body would decompose in or near some river, and as well to a software engineering concept: In the river situation, the dead body will contaminate the water or groundwater that it feeds from and have consequences for organisms that come in contact with that water. In the software engineering analogue, "downstream" refers to software derived from, or depending on, "upstream" software like the cadaver that Cueball devised. The causality with flowing water and software is reasonably comparable: both can be seen as a stream of atoms that are (almost) endlessly divisible and recombinable. [Cueball is walking, talking to Ponytail, who is offscreen.] Cueball: I wrote a script to automate that thing. Ponytail: Oh cool! Ponytail: ...wait, you wrote it? Ponytail: Oh no. [Cueball and Ponytail are standing next to each other and talking.] Cueball: Wanna see the code? Ponytail: I would, if you hadn't said that in the tone of voice of "Wanna see a dead body?" [Same scene as before, except Cueball has his hand on his chin.] Cueball: My code is sort of similar to a dead body, in that you can either come look at it now, or wait a few weeks until it becomes a problem. Ponytail: And because you're lucky that the people around you understand that they create more problems than they solve.

Email Settings

Email Settings

https://www.xkcd.com/2139

https://www.explainxkcd.com/wiki/index.php/2139:_Email_Settings

Email Settings [A list of controls with radio buttons and checkboxes] Default reply behavior ( ) Reply ( ) Reply All (*) Forward to address book Vacation autoresponder (*) While on vacation ( ) Always [x] Reply to all newsletters with "Thank you for the newsletter!" Attachment limit ( ) 300 KB (*) 1.4 MB ( ) 5 MB (Beta) Default email format (*) Plain text ( ) HTML ( ) CSS [x] Reply to HTML emails with "Whoa, buddy, what's all this code?" Character set ( ) ASCII (Unicode 0-127 only) (*) Non-ASCII (Unicode 128+ only) Smart autocomplete ( ) Do not suggest replies ( ) Suggest replies (*) Automatically respond to all emails with suggested reply Important emails (*) Show ( ) Hide Show unread email count... (*) Now ( ) On my projected day of death Signature (*) "That's my email. Hope you liked it!" ( ) None

The comic shows some email settings with a few less-than-helpful options. Plain text is self-explanatory; plain text with no special formatting options. HTML means that it can have markup to allow for bold text, colors, etc. CSS is in reference to Cascading Style Sheets, which is a styling option often combined with HTML, but useless on its own. With emails, it is typically used as inline CSS. Email Settings [A list of controls with radio buttons and checkboxes] Default reply behavior ( ) Reply ( ) Reply All (*) Forward to address book Vacation autoresponder (*) While on vacation ( ) Always [x] Reply to all newsletters with "Thank you for the newsletter!" Attachment limit ( ) 300 KB (*) 1.4 MB ( ) 5 MB (Beta) Default email format (*) Plain text ( ) HTML ( ) CSS [x] Reply to HTML emails with "Whoa, buddy, what's all this code?" Character set ( ) ASCII (Unicode 0-127 only) (*) Non-ASCII (Unicode 128+ only) Smart autocomplete ( ) Do not suggest replies ( ) Suggest replies (*) Automatically respond to all emails with suggested reply Important emails (*) Show ( ) Hide Show unread email count... (*) Now ( ) On my projected day of death Signature (*) "That's my email. Hope you liked it!" ( ) None

Reinvent the Wheel

Reinvent the Wheel

https://www.xkcd.com/2140

https://www.explainxkcd.com/wiki/index.php/2140:_Reinvent_the_Wheel

[Beret Guy is talking to Ponytail.] Beret Guy: We don't want to reinvent the wheel, so every day we Google image search "wheel", and whatever object comes up, that's what we attach to our vehicles. Beret Guy: Sure, external dependencies carry risks, but so far they've all been pretty good wheels.

" Reinventing the wheel " is an idiom/metaphor that refers to duplicate effort to recreate something that has already been created or perfected previously without adding any value in the process. The phrase relates to the idea that the round wheel was invented a long time ago and there is no way to make it better, as a circle is the most optimal shape. While the phrase includes the word "wheel", it isn't typically directly associated with the wheel but instead uses the word "wheel" because of the easily understandable meaning - a simple object with no improvements that can be made. That being said, we have actually reinvented the wheel at one point in time - a tire is a modern improvement to the wheel, which reduces bumps and shocks that people in the car would feel from uneven road surfaces. In this comic, Beret Guy works for an automotive company (or this is his own company ), and he is explaining to Ponytail their decision to not reinvent the wheel for the automobiles that they produce, using the phrase in a literal sense instead of figuratively. Instead of determining for themselves what wheel to use, they want to use whichever wheel is presumably considered the "best" wheel by the world, using a daily Google image search for "wheel" to determine the highest ranked wheel, and then using that wheel on the vehicles they produce that day. In reality, this would be a very bad way of choosing the wheels of the automobiles Beret Guy's company produces. In addition to being extremely inefficient, as they might have to change the wheels they use every day, it may also result in copyrights and lawsuits against his company. The point of the comic is to make fun of programmers who take the idea that you should never reinvent the wheel too seriously. When these people have a problem, they may Google to find a solution to that problem, and when they find a piece of online code, they use it in their own code, even if it wasn't initially designed to handle the task for which it is being used and thus may have unintended side effects or other issues. Another way that programmers may go too far in avoiding reinventing the wheel is in using external dependencies. It can be valuable to use external libraries, especially for applications where certain tasks have strange edge cases that a 'reinvention' is likely to miss or require lots of development effort to correctly implement (like time ). However, using someone else's code means taking on the risk of security vulnerabilities, and when the library is updated on live installations, the user also takes on the risk that the library might become unavailable or otherwise break. In this case, Beret Guy's company updates their wheel "library" on a daily basis from Google's image search. Google is unlikely to shut down a core search product, but they might change the API that Beret Guy's company uses (unless he's just going to their website himself), and they have been known to shut down projects that people like, such as Google Reader . On the day this comic was released, Randall changed the Header text of xkcd, adding a reference to Google Reader . The popular programming language Python manages external dependencies with packages called "wheels" which are "published to the cheese shop", which may or may not be an intended reference. In any event, Beret Guy is in effect reinventing the wheel by doing a new search for wheels on Google Images every day. If the wheel he finds on Google Images on a given day is suitable for his company's needs, the company would likely be better off using the same wheel on succeeding days (unless circumstances change which make that unfeasible), compared to trying to doing a new search for wheels every day. In addition, Beret Guy's company might be forced to create new wheel-producing machinery every day, although if Beret Guy can transmit soup and air through electrical cords, it may simply be a matter of copying the image then pasting it in real life. The title text indicates that Beret Guy is currently using bicycle wheels for his vehicles, requiring his vehicles to be lighter as bicycle wheels cannot carry a lot of weight. He says this "reduce[s] overhead", which is both literally true, that his vehicle weighs less, and refers to the usual figurative desire of reducing overhead costs of development by using external libraries. If the former interpretation is correct, this raises the question of why Beret Guy's company didn't try to lighten the load of its vehicles beforehand. Finally, the narrator (supposedly Beret Guy) explains that at one point a wheel of cheese was near the top of the Google images search. If it had reached the top, it would have been disastrous as a wheel of cheese is completely unsuited for use as a vehicle's wheel. [ citation needed ] Beret Guy implies that his company would have used it if it reached the first position even though he knows that it would be unsuitable for usage in vehicles, further demonstrating Beret Guy's lack of business knowledge. On the day the comic was released a bicycle wheel came up first when searching for "wheel", see image in the Trivia section below. [Beret Guy is talking to Ponytail.] Beret Guy: We don't want to reinvent the wheel, so every day we Google image search "wheel", and whatever object comes up, that's what we attach to our vehicles. Beret Guy: Sure, external dependencies carry risks, but so far they've all been pretty good wheels.

UI vs UX

UI vs UX

https://www.xkcd.com/2141

https://www.explainxkcd.com/wiki/index.php/2141:_UI_vs_UX

[Two underlined headings are above two columns of text with seven lines. The left "symbol" (labelled "Designer") is explained by the text to the right (labelled "What they are responsible for").] UI: Elements of the interface that the user encounters UX: The user's experience of using the interface to achieve goals UZ: The psychological roots of the user's motivation for seeking out the interaction U∝: The user's self-actualization UΩ: The arc of the user's life U∞: Life's experience of time U⚫: The arc of the moral universe

UI vs UX is a discussion in software engineering of the differences between user interface design (UI) and user experience design (UX). As explained in the comic, UI design is typically concerned with the elements of the interface that a user encounters, while UX design is more concerned about the user's overall experience in using such interface. UX design can be seen as more holistic & abstract than UI. This comic extends the idea, adding increasingly all-encompassing, abstract & fanciful design perspectives. To start, the two real categories are: UI - Elements of the interface that the user encounters This standard software engineering practice involves trying to come up with a user interface - icons, colors, placement or text and elements, etc. that works well together, that isn't confusing, and that hopefully makes it easy for the user to view the information they need to digest, as well as make whatever choices the user is expected to make. They also look at things like how long it takes to move from one screen or task to another, etc. UX - The user's experience of using the interface to achieve goals Sometimes a UI designer makes choices that they think are easy for the user, but it turns out not to be as easy as expected when it comes to real users and practical situations. So the UX designer focuses on observing how a user uses a product, both how they use the user interface as well as other less technical aspects of their experience such as how they come to find out about the product, what they tell others about the product, etc. The comic takes this to absurd levels by adding these additional categories: UZ - The psychological roots of the user's motivation for seeking out the interaction The comic says that UZ is the investigation of the psychological roots of why the user even wants to use the interface. This is not normally something that computer programmers do [ citation needed ] , and is usually best left in the hands of psychologists [ citation needed ] . "The psychological roots of motivation" is a buzzword phrase from management theory which may not have a particularly well-defined meaning. Motivation is itself the psychological root of behavior. While motivations certainly have causes, they are usually not clear enough to meaningfully treat in formal or clinical contexts. Uα - The user's self-actualization " Self actualization " is the most abstract, immaterial form of motivation, meaning the need to find comfort in one's own goals and achievements. Available only when more material needs such as those for food, shelter, warmth, security, and a sense of belonging are met, it forms the pinnacle of Maslow's hierarchy of needs . α is alpha , the first letter of the Greek alphabet. It's often used to show the "beginning" or "first" of something (including in philosophical contexts). And as the first Greek letter, it can be thought of "beyond Z" in a sense; the Atlantic hurricane name list uses the Greek alphabet this way, for example (as 944: Hurricane Names alludes to). UΩ - The arc of the user's life "The arc of one's life," means the overall thematic elements present in a person's existence. It occurs in the philosophical humor novel The World According to Garp , which remarks on how easily the arc of any human life can turn on a single sexual relationship. Continuing the philosophical theme, Ω is omega , the last letter of the Greek alphabet. As such, it's often used to show the "last", "end", or "ultimate" of something. U∞ - Life's experience of time "Life's experience of time" is a very rare phrase which does not seem to have a coherent meaning across the handful of times it occurs. ∞ (U+221E) is the mathematical symbol for infinity , again furthering the philosophical abstraction. U ⬤ - The arc of the moral universe "The arc of the moral universe is long, but it bends toward justice," is a famous line from a speech by Martin Luther King , referring to the slow pace at which social progress is often achieved, and paraphrasing parts of a 1853 sermon by abolitionist minister Theodore Parker : "I do not pretend to understand the moral universe. The arc is a long one. My eye reaches but little ways. I cannot calculate the curve and complete the figure by experience of sight. I can divine it by conscience. And from what I see I am sure it bends toward justice." President Obama had the sentence from King's speech woven into a rug in the Oval Office. The ⬤ is a filled-in circle the size of the letters around it, represented here by the Unicode " black large circle " character ( U+2B24 ). Continuing the philosophical abstraction, it comes well after the Greek alphabet and most mathematical symbols in Unicode, and is especially unlikely to be used as a text character in its own right like this. [ citation needed ] The title text refers to a higher power bending the moral arc, but mirrors the UI and UX categories, with the implication that the list continues in a spiral through ever more rarefied levels of higher powers, with even less likely symbols denoting them. U[unprintable glyph] - The elements a higher power uses to bend that moral arc Essentially UI for the higher power's moral arc bending utility. U[even more unprintable glyph] - The higher power's overall experience bending that moral arc Essentially UX for the higher power's moral arc bending utility. [Two underlined headings are above two columns of text with seven lines. The left "symbol" (labelled "Designer") is explained by the text to the right (labelled "What they are responsible for").] UI: Elements of the interface that the user encounters UX: The user's experience of using the interface to achieve goals UZ: The psychological roots of the user's motivation for seeking out the interaction U∝: The user's self-actualization UΩ: The arc of the user's life U∞: Life's experience of time U⚫: The arc of the moral universe

Dangerous Fields

Dangerous Fields

https://www.xkcd.com/2142

https://www.explainxkcd.com/wiki/index.php/2142:_Dangerous_Fields

[A line chart is shown going from left to right with two arrows on either side. On the line are ten dots spread out unevenly from close to each end. The first four dots are clustered together on the left side. Then follows 5 more dots unevenly spaced, all to the left of center. On the far right of the line, near the end, there is one dot. Beneath each dot, there goes a line down to a label written beneath each line. Above the chart, there is a big title and below that is an explanation. Below that again, there is a small arrow pointing to the right with a label above it.] Probability that you'll be killed by the thing you study By field [Arrow pointing right, labeled:] More likely [Labels for the ten dots from left to right:] Mathematics (0 pixels from first field, 0.00% of overall range of fields) Astronomy (9px, 1.35%) Economics (16px, 2.40%) Law (22px, 3.30%) Criminology (77px, 11.56%) Meteorology (96px, 14.41%) Chemistry (156px, 23.42%) Marine Biology (166px, 24.92%) Volcanology (206px, 30.93%) Gerontology (666px, 100.00%)

This is a graph of fields of study, ordered by how likely one is to die because of something that that field studies, with mathematics being the least dangerous and gerontology being the most. Gerontology, the scientific study of old age, is shown as much more dangerous than the other fields, so it is far on the right side of the graph. The joke is in the distinction between the danger of studying the thing, and the overall death rate from the thing. Studying aging doesn't put you at much more risk of aging than the general population. However, studying volcanoes is likely to put you in dangerous environments. The title text is about Epidemiology , the study of health and disease conditions in populations. In the event of an epidemic, there is a strong chance that epidemiologists in the search for the cause, transmission, and treatment will be exposed and become victims of the disease in their own right. However, the title text refers more broadly to the role of epidemiology in maintaining detailed statistical records of diseases and other causes of death, such that eventually any epidemiologist (whatever the cause of death) will become one of their own statistics. [A line chart is shown going from left to right with two arrows on either side. On the line are ten dots spread out unevenly from close to each end. The first four dots are clustered together on the left side. Then follows 5 more dots unevenly spaced, all to the left of center. On the far right of the line, near the end, there is one dot. Beneath each dot, there goes a line down to a label written beneath each line. Above the chart, there is a big title and below that is an explanation. Below that again, there is a small arrow pointing to the right with a label above it.] Probability that you'll be killed by the thing you study By field [Arrow pointing right, labeled:] More likely [Labels for the ten dots from left to right:] Mathematics (0 pixels from first field, 0.00% of overall range of fields) Astronomy (9px, 1.35%) Economics (16px, 2.40%) Law (22px, 3.30%) Criminology (77px, 11.56%) Meteorology (96px, 14.41%) Chemistry (156px, 23.42%) Marine Biology (166px, 24.92%) Volcanology (206px, 30.93%) Gerontology (666px, 100.00%)

Disk Usage

Disk Usage

https://www.xkcd.com/2143

https://www.explainxkcd.com/wiki/index.php/2143:_Disk_Usage

[This comic shows a pie chart with 10 slices, each with a label and a line pointing to these ten different sized slices. There is a caption above the chart:] Disk Space Usage Report [The labels on each slice is given in anti-clockwise order starting from the 12 o'clock position. The percentages are estimated from the image and are noted in the square brackets before the transcript:] [18%] Photos [1%] Good Photos [3%]: Documents [6%]: Everything you've streamed since 2017 [9%]: A single five-year-old PowerPoint presentation [21%]: "System" [2%]: Unused [9%]: "Cache" [23%]: "Other" [8%]: Why are there two full backups of my phone from 2015 deep in a settings folder?

Many personal computers provide a way to obtain a graphical breakdown of how their storage space is being used, most commonly by representing the filesystem as a pie chart in which each slice represents the proportion of the total storage space being taken up by a particular item. In this comic, Randall has illustrated the usage of his hard disk drive in just such a way, although as is common for him, the items in his hard drive start off seemingly normal and become increasingly strange: Photos Digital photographs are a common item to be stored on a hard disk; many people take lots of photographs with their smartphone or a camera and will commonly transfer them to a disk drive for safekeeping, editing, or organizing. With the high resolution of modern cameras and the ease of taking photos, it is common for photo collections to consume a significant amount of disk space. Good photos On the flipside, the ease of taking photographs means that it is very easy to take bad photographs, particularly as most people are not experienced at photography. The pie chart is rather bluntly indicating that of the many photographs Randall has taken, only a vanishingly small fraction of them are actually good. Documents On a file system, "Documents" is generally used as a catch-all term for the user's personal files. Everything you've streamed since 2017 Streaming is a term that refers to accessing audio or video content on the Internet without downloading the entire media file first - it is instead played while it's being retrieved. An example of streaming is watching a YouTube video. Assuming a weekly 2h live stream (@4Mbps) between 2017-01-01 and 2019-04-29, these recordings would be 425GB in size. When these files take up 6% of all the used disk space, the full amount of used space would be roughly 7TB, which is plausible, given the rise of 10TB hard disks in 2016 . It might also be referring to temporary media files that were stored on the disk while it was being "streamed" for viewing or listening from the Internet and never deleted when done. A single five-year old PowerPoint presentation Almost a tenth of the entire disk space is taken up by a single file, a presentation made five years ago in Microsoft PowerPoint . It's unclear why Randall has kept this file or why it is so huge - possibly it is important to him for some reason, or perhaps he can't bear the thought of throwing information away, regardless of how much storage it requires. While it's possible that the file may genuinely be long or detailed enough to require so much space, it could also be that the file is bloated due to PowerPoint's strategy of converting compressed graphics to full-resolution bitmaps for historical cross-platform compatibility . This has been known to result in PowerPoint decks that are much larger than the sum of their component files. "System" This would be files related to the computer's Operating System . While these files will generally show up on a disk usage analysis, it is generally recommended to leave them alone, as they may be critical to the computer's operation. A well-known trolling tactic involves tricking unsuspecting users into deleting their critical system files (eg. the "System32" folder on Windows), which renders the operating system unusable. Unused Parkinson's law , the computer storage corollary, says that data expands to fill the space available for storage. As such, this sliver representing the unused portion of the storage device will always be tiny. "Cache" The operating system and other programs often keep copies of data they've used or downloaded in case they need to use that data again; such data is usually stored in cache files. Often these can be deleted without too much ill effect, but some programs have different ways of deleting their own cache files. "Other" People attempting to organize their files will often end up creating a directory called "Other" or "Misc" for any files that they could not categorize. On Randall's hard disk, this "Other" directory takes up a significant amount of disk space, indicating that either his categorization system isn't working very well, or he doesn't have the discipline to properly maintain his file organization. Alternatively, this could be a category defined by the usage report, which would include anything it can't categorize - often a strangely large portion of the files. Why are there two full backups of my phone from 2015 deep in a settings folder? Full backups of an old phone may have been stored to "settings" by a version of backup or file synchronization software which wanted to keep the resulting backup images in a location away from user control so they would be less likely to modify any of their component files, which might, for example, tend to clobber new versions with the modified old versions. Renaming a device under such circumstances might lead to duplicate backup images. Another possible explanation is that folder names like "Other", "Cache" and "System" refer to storing porn while trying to hide this fact by using unsuspicious folder names. Hence the quotes. Alarmingly, the "Unused" portion of the pie chart is extremely small, which means the disk is nearly full with very little remaining capacity. Users don't usually worry about what is using space on their computer disk until they get an alert about the disk running out of space - this is likely when a user would resort to viewing this type of graph to figure out what they can delete to free up disk space. The title text references the management UI of a hypothetical disk cleaning utility. The following options are mentioned in its menu: Optimize space usage A common nondescript phrase often found in such tools. Encrypt disk usage report Often, one might want to encrypt data on the disk, not reports about said data. This may suggest that the unusual disk usage is embarrassing enough that the user may want to encrypt the usage report, preventing other people from reading it. Convert photos to text-only Plain-text documents take less space than pictures. The most high-compression option would be to replace the photo file with a text file containing a short description of the photo, for example using an AI algorithm like CaptionBot . Scanned documents can be automatically transcribed (OCR). However, applying such an algorithm to photos will result in garbage. One alternative, could be that the tool turns image files into text files by changing the extension to .txt. This would not save any space, and would only make the files more difficult to open. Another alternative would be converting the images into so called ASCII art , by converting regularly sampled blocks of pixels to ASCII characters that closely approximate the general shape and at times color of those pixels, potentially saving a general impression of the content of the images while significantly reducing file size. Delete temporary files Another real option. Temporary files are often not deleted automatically, so deleting them can save a significant amount of disk space. Delete permanent files A made-up term, that might refer to the user's documents, pictures, etc. You would not want to delete them. Delete all files currently in use Deleting files that are in use would most definitely result in data loss or program crashes, including perhaps even the program doing the deleting, making it effectively single-use. Windows explicitly disallows deleting open files & Linux, etc. provide locking mechanisms to prevent it, since it can cause data loss. Deleting all open files would be catastrophic, especially if it included system utilities & the kernel. If the program is capable of deleting all files in use anywhere on the planet, it would be considerably worse (& looking at these options, it's hard to say for sure the program won't try to go that far). Optimize menu options Those options could really do with some optimization. (a reference to the first entry?) Download cloud, Optimize cloud Here, the cloud probably refers to cloud storage (online storage). Cloud storage would be too large by many orders of magnitude to fit, let alone download onto a desktop computer, but in 908: The Cloud , the cloud is depicted as (ultimately) running on a single desktop-sized server in Black Hat 's house. Perhaps the "Optimize cloud" option would be used to enable such an arrangement. Upload unused space to cloud "Uploading empty space" is a) impossible and b) would result in less space being available, which is the opposite of what a disk cleaner utility is supposed to do. Note that "unused space" may contain actual data. Often, when a file is deleted, the operating system just marks the content as available. The result is that it stays there until overwritten by new data. There are many data recovery tools that takes advantage of it in order to "undelete" files. [This comic shows a pie chart with 10 slices, each with a label and a line pointing to these ten different sized slices. There is a caption above the chart:] Disk Space Usage Report [The labels on each slice is given in anti-clockwise order starting from the 12 o'clock position. The percentages are estimated from the image and are noted in the square brackets before the transcript:] [18%] Photos [1%] Good Photos [3%]: Documents [6%]: Everything you've streamed since 2017 [9%]: A single five-year-old PowerPoint presentation [21%]: "System" [2%]: Unused [9%]: "Cache" [23%]: "Other" [8%]: Why are there two full backups of my phone from 2015 deep in a settings folder?

Adjusting a Chair

Adjusting a Chair

https://www.xkcd.com/2144

https://www.explainxkcd.com/wiki/index.php/2144:_Adjusting_a_Chair

[Cueball is shown adjusting a chair by pressing a button on the bottom of the chair. There is a caption in a frame over the top of the panel:] Adjusting a chair: [The seat back of the chair swings backward with him rather fast as shown by a few movement lines.] Chair: Clunk [Cueball leans forward against the new chair position and presses another button.] [The chair extends to several times its previous height, very fast as shown by many lines beneath the seat.] Chair: Hiss [At the top of this very high seat Cueball leans forward and presses another button.] [The seat expands in all directions, so Cueball only sits in the middle of it with his legs on top of the inflated cushion.] Chair: Poof [The chair is now a massive contraption. It has 5 bases, each with wheels as the original chair. The main's seat is in the middle of the contraption with a single trunk going up from the five bases connecting them and the large cushion of the seat. Two entire chairs are branching out from underneath this central seat, they are each hanging in a thin wire more or less upside down to each side of the main trunk. Two poles are coming up from the central seat, each with a new seat and two back-to-back seat backs. Yet another seat is supported by a thin rod connecting the two top seats, looking almost like a table between the two chairs. Cueball is still on the main seat's cushion. He is holding on to one of the poles above him as he leans down and attempts to press yet another button beneath the seat. There is a caption in a frame over the top of the panel:] Two hours later...

This comic shows Cueball 's attempts to adjust a swivelling chair. This comically culminates in a massive chair with a big central seat and several other chairs branching off of it as Cueball continues learning how to to adjust it. The chair also apparently has so many controls it takes two hours to discover them all (although Cueball may have shown off his newly-discovered abilities in the mean time, so it might not take two hours of continuous experimentation). As many people have experienced, these chairs can be quite difficult to raise, lower, or manoeuvre if one does not know how. Typically, the chairs have multiple knobs and levers underneath the seat, which requires the user to rely on muscle memory to find them, since these levers are commonly used while sitting in the chair. There are often several ways to manipulate each control (may be rotated, moved laterally, vertically, or axially.) One usually needs to experiment with the levers and knobs in a new chair to understand how to work the chair, and it appears Cueball is experimenting with them. Each step gets farther away from what real-life office chairs could do. In sequence, Cueball finds his chair doing more and more surprising things: The title text refers to a common claim on such chairs, that the chair offers 360 degrees rotation and several degrees of freedom. This is a double entendre, depending on if "360 degrees" or "degrees of freedom" is interpreted as an object. However, here it means there are 360 mechanical degrees of freedom , which is the number of independent parameters that define the configuration of an object; in other words, the chair has 360 different levers and options, far more than a standard chair [ citation needed ] . [Cueball is shown adjusting a chair by pressing a button on the bottom of the chair. There is a caption in a frame over the top of the panel:] Adjusting a chair: [The seat back of the chair swings backward with him rather fast as shown by a few movement lines.] Chair: Clunk [Cueball leans forward against the new chair position and presses another button.] [The chair extends to several times its previous height, very fast as shown by many lines beneath the seat.] Chair: Hiss [At the top of this very high seat Cueball leans forward and presses another button.] [The seat expands in all directions, so Cueball only sits in the middle of it with his legs on top of the inflated cushion.] Chair: Poof [The chair is now a massive contraption. It has 5 bases, each with wheels as the original chair. The main's seat is in the middle of the contraption with a single trunk going up from the five bases connecting them and the large cushion of the seat. Two entire chairs are branching out from underneath this central seat, they are each hanging in a thin wire more or less upside down to each side of the main trunk. Two poles are coming up from the central seat, each with a new seat and two back-to-back seat backs. Yet another seat is supported by a thin rod connecting the two top seats, looking almost like a table between the two chairs. Cueball is still on the main seat's cushion. He is holding on to one of the poles above him as he leans down and attempts to press yet another button beneath the seat. There is a caption in a frame over the top of the panel:] Two hours later...

Heists And Escapes

Heists And Escapes

https://www.xkcd.com/2145

https://www.explainxkcd.com/wiki/index.php/2145:_Heists_And_Escapes

[Seven different room scenarios are shown with characters attempting to get inside or outside, each with a label below them.] [Cueball and Ponytail trying to exit a room.] Escape rooms [Cueball and Megan trying to enter a room.] Heist movies [A small version of Cueball stands in the middle of a room while a Hairy on the left and Cueball on the right are trying to enter.] Home Alone (1990) [A room is shown inside a larger room. Two characters try to enter from outside and two others try to exit from the inner room while Megan and Cueball are standing between them.] The Battle of Winterfell [Four rooms are shown inside of each other. Two characters try to enter from outside while three Cueballs in each room are standing while asleep.] Inception (2010) [Smaller rooms are recursively shown inside of larger ones, with two characters trying to escape from each.] The Divine Comedy (1320) [At the bottom a more complicated combination of various rooms shown in gray, with arrows labeled with question marks showing escape routes for two characters in black. On the left is a large room labelled Truman Show, and on the right is the nine-level Dante's Inferno. Between them is the river Styx. Inside the Truman Show are the Bank, which contains a Room with the two people in it, a Vault with a money bag in it, and The Dead; and Kevin McCallister's House and Subconscious.] [Label in the bottom in black:] My plan for the greatest escape room game of all time Judging by the depicted scene, the Battle of Winterfell referenced in the comic seems to refer to the battle taking place in the 3rd episode of the 8th season of the TV show Game of Thrones. While there is no official naming of all battles in the show, this is in line with the naming on most blogs and other discussions published around the premiere of that episode. However several wikis and other more long term reviews of the show refer to this battle as the "Battle of Ice and Fire". On these sites the "Battle of Winterfell" refers to the battle in the 10th episode of the 5th season between Stannis Baratheon and the Boltons.

The top six panels show a stylized version of various options where people try to get into or out of rooms. There are always two xkcd figures trying to get into or out of a room. One is always rattling, possibly at a locked door. While no door is drawn, the position of their hands indicates this. The second figure always has their hands at head height, possibly looking for weaknesses in the structure. The characters in each panel vary and there seems to be no specific pattern to them. The six top panels show these scenarios: At the end, Randall proposes a combination of all of these things, and also combining it with others, to form the "greatest escape room game of all time": The escape room begins in a small room, shown with Cueball and Megan standing inside, who likely represent the participants of the escape room. An arrow leads out from that room into a larger bank, where some more characters labeled The Dead, referencing The Battle of Winterfell, are standing. An arrow leaves from them that merges into Cueball and Megan’s, implying they join them as they escape the room. The arrows continue outside the bank, into a larger room labeled Truman Show , inspired by the film where the protagonist was living in a constructed reality show, although he did not know it. The path branches upwards around or into Kevin McCallister’s house, with the arrows inside spitting yet again, either exiting the house again or entering Kevin McCallister’s subconscious, a reference to the movie Inception . The arrows once again split and continue either downwards or to the right, both exiting McCallister’s house. The path to the right splits, the top path crossing Styx , a river in Greek mythology that forms the boundary between Earth and the Underworld, represented by Dante’s Inferno, taken from The Divine Comedy , and the other returning to the line that leads downwards. The line that leads to Dante’s Inferno is met by the line that leads around Kevin McCallister’s house. It can be assumed that this is not a breaking into the underworld as portrayed in some movies, but due to the simplicity of the paths (note that unlike for the escape the line just crosses Styx) it is the possibility of failing prior puzzles and dying. In that case the escape room puzzle would continue with escaping from the underworld to rejoin the puzzles. Both paths lead downwards back across Styx, rejoining the other lines below McCallister’s house. The lines continue to the bank and spit to either re-enter the bank or exit the escape room entirely. The line that re-enters the bank either returns to The Dead or into the bank’s vault, which the line also exits the escape room. The title text refers to this article , which claims that Kevin McCallister is dead, and is actually a ghost. [Seven different room scenarios are shown with characters attempting to get inside or outside, each with a label below them.] [Cueball and Ponytail trying to exit a room.] Escape rooms [Cueball and Megan trying to enter a room.] Heist movies [A small version of Cueball stands in the middle of a room while a Hairy on the left and Cueball on the right are trying to enter.] Home Alone (1990) [A room is shown inside a larger room. Two characters try to enter from outside and two others try to exit from the inner room while Megan and Cueball are standing between them.] The Battle of Winterfell [Four rooms are shown inside of each other. Two characters try to enter from outside while three Cueballs in each room are standing while asleep.] Inception (2010) [Smaller rooms are recursively shown inside of larger ones, with two characters trying to escape from each.] The Divine Comedy (1320) [At the bottom a more complicated combination of various rooms shown in gray, with arrows labeled with question marks showing escape routes for two characters in black. On the left is a large room labelled Truman Show, and on the right is the nine-level Dante's Inferno. Between them is the river Styx. Inside the Truman Show are the Bank, which contains a Room with the two people in it, a Vault with a money bag in it, and The Dead; and Kevin McCallister's House and Subconscious.] [Label in the bottom in black:] My plan for the greatest escape room game of all time Judging by the depicted scene, the Battle of Winterfell referenced in the comic seems to refer to the battle taking place in the 3rd episode of the 8th season of the TV show Game of Thrones. While there is no official naming of all battles in the show, this is in line with the naming on most blogs and other discussions published around the premiere of that episode. However several wikis and other more long term reviews of the show refer to this battle as the "Battle of Ice and Fire". On these sites the "Battle of Winterfell" refers to the battle in the 10th episode of the 5th season between Stannis Baratheon and the Boltons.

Waiting for the But

Waiting for the But

https://www.xkcd.com/2146

https://www.explainxkcd.com/wiki/index.php/2146:_Waiting_for_the_But

[Ponytail is talking to Cueball, while holding her hands up with both palms up. Cueball is thinking as shown with a thought bubble.] Ponytail: Listen, I'm all in favor of reducing car accidents, I think arson is a serious crime, and I'm a big fan of those "No Animals Were Harmed" disclaimers at the end of movies... Cueball (thinking): Uh-oh. [Caption below the panel:] The longer you have to wait for the "but", the worse whatever comes after it is going to be.

Often arguments are made in the form of "I think X, but Y", where Y is almost but not quite contradictory to X. More specifically, the argument would go "I am not [something generally considered distasteful], but [a more specific statement most people consider part of that general statement]". The first part of such a statement can sometimes be viewed as an apology or an excuse because the person talking knows that the second part might upset people. A common example would be "I'm not a racist, but I don't think we should let refugees from Africa into Europe." The idea of denying help to people from Africa will be seen as racist by many people, so the speaker tries to preempt that opinion of themself. In this comic, Cueball is having a conversation with Ponytail , who lists several seemingly unrelated but agreeable positions, such as reducing car accidents , treating arson as a serious crime, and approving of "No Animals were Harmed" disclaimers in modern media, with Cueball wondering when the "but.." of the statement will come, and conjuring increasingly outrageous images of what Ponytail could have in mind that involves violating all of them, for example some sort of reckless fiery car stunt involving animals. The title text gives another example of a sentence that will probably be followed by a "but". Multi-level marketing schemes and the Spanish Inquisition are both considered bad in very different ways, so the implication that if the speaker has to apologize in advance for sounding like defending both of them, they must have a remarkably troubling idea in mind, involving somehow using a version of the Spanish Inquisition as an MLM scheme. Another possible explanation would be that when people hear a sentence that starts with "Listen, I'm" they tend to wait for the "but", and the longer it takes the more tension it may cause them, while the speaker may never intend to say "but". Similar ideas were used for 365: Slides and 559: No Pun Intended . [Ponytail is talking to Cueball, while holding her hands up with both palms up. Cueball is thinking as shown with a thought bubble.] Ponytail: Listen, I'm all in favor of reducing car accidents, I think arson is a serious crime, and I'm a big fan of those "No Animals Were Harmed" disclaimers at the end of movies... Cueball (thinking): Uh-oh. [Caption below the panel:] The longer you have to wait for the "but", the worse whatever comes after it is going to be.

Appendicitis

Appendicitis

https://www.xkcd.com/2147

https://www.explainxkcd.com/wiki/index.php/2147:_Appendicitis

[Cueball is seated on an medical examination table, clutching his stomach, while Ponytail stands dressed in a doctor's coat holding a file on a clipboard in her left hand.] Ponytail: Well, we zapped you with energy beams, and it looks like one of your stupid organs is a traitor. Cueball: ...which one? Ponytail: I dunno, appendix? Gallbladder? One of the little ones that sucks. Cueball: What should I do? [Closeup on Ponytail. She holds her left hand in a clenched fist.] Ponytail: You could quash the revolt with the ruthless deployment of chemical and biological weapons. Cueball (off-screen): ...antibiotics? Ponytail: But certain victory comes only through the sword . Cueball (off-screen): Surgery. [Closeup on Ponytail with her fists raised.] Ponytail: While we're inside, we'll look around-if we see any signs of insurrection elsewhere, we will not hesitate to act. There can be no armistice. Your parts must fall in line or be crushed. Cueball (off-screen): Um. [Zoom out again to the entire scene. Ponytail points her left hand up.] Ponytail: When the battle is won, we will salt your abdomen so no new organs can ever sprout up to trouble you again. Cueball: Maybe I should get a second opinion. Ponytail: Only if you care what a weaker doctor would say.

Cueball , representing Randall , is visiting Doctor Ponytail , this time to diagnose some medical condition. From her description, zapped you with energy beams , it sounds like they just took an x-ray image , maybe in the form of a CT scan , and Ponytail is following up on the results. It appears that he may have appendicitis , the title of the comic, which could be treated through antibiotics , or through an appendectomy surgery. As is typical for Doctor Ponytail, she characterizes the diagnosis in a strange and not-entirely-helpful way, in this case likening Cueball's inflamed appendix to a social uprising or rebellion. In some ways, this is not a bad metaphor - Cueball is an organism, and as such, functions best when all of his organic parts are working correctly in unison. People often express the similar sentiment of being "betrayed by their own body" to describe a biological function that isn't working right. However, Doctor Ponytail insists on talking only in metaphor, preventing Cueball from getting any useful medical detail about his condition. Antibiotic treatment is described as using "chemical / biological weapons", while the appendectomy is described as "victory through the sword". She further describes more extreme "battle tactics", like crushing all other rebellions in his body. Lastly, she mentions "salting his abdomen" to prevent other rebellions. This is a reference to the salting the earth tactic in battle, which was a ritual to symbolize a curse on a conquered city and would have theoretically hindered future crop production, thus preventing that city from being rebuilt. It is likely that the medical usage would be the application of saline solution, salt in water, which is used for cleaning wounds. After all this explanation, Cueball begins to question Ponytail's methods, and requests to see a different doctor to get a second opinion . The title text appears to be Randall speaking directly to the reader addressing a recent appendicitis and his current health state. He continues the comic's joke with a meta reference pondering the repercussions if his organs subsequently discover this comic. The title text of 2508: Circumappendiceal Somectomy , from August 2021, seems to indicate that while antibiotics may have cured this event, a later infection required surgery anyway, a bit more than two years after this comic was released. [Cueball is seated on an medical examination table, clutching his stomach, while Ponytail stands dressed in a doctor's coat holding a file on a clipboard in her left hand.] Ponytail: Well, we zapped you with energy beams, and it looks like one of your stupid organs is a traitor. Cueball: ...which one? Ponytail: I dunno, appendix? Gallbladder? One of the little ones that sucks. Cueball: What should I do? [Closeup on Ponytail. She holds her left hand in a clenched fist.] Ponytail: You could quash the revolt with the ruthless deployment of chemical and biological weapons. Cueball (off-screen): ...antibiotics? Ponytail: But certain victory comes only through the sword . Cueball (off-screen): Surgery. [Closeup on Ponytail with her fists raised.] Ponytail: While we're inside, we'll look around-if we see any signs of insurrection elsewhere, we will not hesitate to act. There can be no armistice. Your parts must fall in line or be crushed. Cueball (off-screen): Um. [Zoom out again to the entire scene. Ponytail points her left hand up.] Ponytail: When the battle is won, we will salt your abdomen so no new organs can ever sprout up to trouble you again. Cueball: Maybe I should get a second opinion. Ponytail: Only if you care what a weaker doctor would say.

Cubesat Launch

Cubesat Launch

https://www.xkcd.com/2148

https://www.explainxkcd.com/wiki/index.php/2148:_Cubesat_Launch

[Megan is holding a cube attached by a string to a quad-copter drone flying above her head. She talks to Cueball standing next to her.] Megan: A spot on a CubeSat launch costs a lot, but you can get a drone and a spool of fishing line for cheap. Cueball: Uh oh. [A wide shot of Megan flying the drone with the cube at her feet while Cueball stand behind her looking after the drone that flies up to the left.] Megan: No no, watch. Megan: This is gonna go great. [Wide shot of a rocket standing on its launch pad with the support tower. The, now very small, drone is approaching, string attached, from the right.] [Slim shot of the rocket as the drone attaches to the rocket, just under the tip with the payload. The string goes down and out to the right.] Megan (off-panel): Perfect! [A huge cloud is emitted from the bottom of the rocket as it lift off the ground every so slightly.] Foom [As the rocket is taking off it begins tilting in the direction of the string. Two off-panel voices come from Megan and Cueball's direction.] Off-panel voice #1: Should it be tilting already? Off-panel voice #2: Hey, move your leg. [Close up of Megan and Cueball struggling in tangle of string that surrounds Megan while she is holding the cube in one hand and the remote for the drone in the other. Cueball uses both hands to try and help her out of the tangle. The string goes out to the left towards the rocket.] Megan: Ugh, let go, I can get- Cueball: -No, lift your other arm- [Three slim panels follow, one above the others, of the rocket, with string, tilting increasingly to the right and down as if pulled by the string. In the final panel of the three the tip of the rocket is now further than where the string goes down to the bottom of the panel. So the string now goes back left from where it is attached to the rocket, rather than to the right as in all previous panels.] [Megan entangled in the string with the cube in her hand and Cueball hanging below her holding on to the string, are flying through the air, as the string goes up right, and with small lines drawn above it to indicate it is moving to the right. On the ground Science Girl holds a hand to her mouth looking up at them, while a guy looking like Cueball runs away with hands over his head.] Megan and Cueball (screaming): Aaaaaa [A disheveled looking Megan and Cueball both with plaster casts on their arms stand before four people, Hairbun, another Cueball like guy, Ponytail and Hairy. They are the members of an interview panel and are sitting behind a desk like table with a large label on its front:] Launch accident investigation board Megan: Listen. Megan: Space exploration is never going to be completely safe.

A CubeSat (aka U-class spacecraft) is a miniature artificial-satellite with cubic dimensions of 10 cm × 10 cm × 11.35 cm (~ 4 in × 4 in × 4.5 in), and masses of about 1.33 kg (2.9 lbs) per unit. CubeSats are put into orbit from the International Space Station or launched as secondary payloads. As of January 2019, at least 900 CubeSats have successively achieved orbit, and at least 80 have been destroyed in launch failures. Their common functions include: Earth observation, amateur radio transmitters, as well as testing prototype small-satellite technology. The comic begins with Megan telling Cueball that being officially part of a CubeSat launch is fairly expensive (starting at around $40,000), [1] but she has an idea for a much cheaper alternative: use a fishing line on a drone to attach to a rocket (that is similar visually to the European Vega rocket) just before launch, with the CubeSat attached to the other end of the fishing line so it gets pulled into space. In reality, this plan would fail for multiple reasons. Upon realizing her plan, Cueball immediately responds with "uh-oh", indicating his concern, but Megan assures him that it will be fine, before piloting the drone towards the rocket. She successfully connects the drone to the rocket, and the rocket lifts off. Whatever her plan was, it goes wrong almost immediately. The unexpected force on the rocket from the side causes it to tilt and go off course. Perhaps if the rocket's control software employed adaptive control techniques, it could have maintained control in the presence of this unexpected force. It is implied that it's not due to the comparatively small force of the CubeSat, but because Cueball is standing on the fishing line. However in real life the force from Cueball stepping on the line would still be very small and would be unable to cause a scenario like this. Megan and Cueball get tangled in the fishing line and are carried away. While the fate of the rocket is not shown, it is likely that its unplanned attitude change would activate the automatic termination sequence or result in manual activation of the destruction protocol. Megan and Cueball miraculously survive and are brought to an investigative board to explain their actions. Megan attempts to defend herself using flawed logic: something was bound to go wrong sooner or later, so it's not her fault that she was the cause. This logic does not account for the fact that this particular rocket's chance to crash was greatly increased by the drone attempting to connect to it. She isn't totally to blame for the accident anyways, since the launch should have been scrubbed as soon as the drone came anywhere near the rocket, and the failure of Mission Control to do so is negligence on their part, and hence they are more responsible for the failure of the mission than Megan and Cueball as they did not follow proper protocol and allowed the launch to occur under unsafe conditions. The title text describes that the supposedly huge damages they caused were partly covered by the earnings from a water skiing championship, which Cueball and Megan presumably won by being dragged across the water by the rocket. This might be a tangential reference to an incident in the Tintin adventure The Black Island , wher Thomson and Thompson blunder into and win an aerobatics competition when they compel a mechanic with no flying experience into taking off in pursuit of that volume's antagonists. Alternatively, it may simply be a case of the title text being largely irrelevant to the comic itself and simply something Randall found funny. This topic of CubeSats has been covered in older comics: 1866: Russell's Teapot and in 1992: SafetySat . [Megan is holding a cube attached by a string to a quad-copter drone flying above her head. She talks to Cueball standing next to her.] Megan: A spot on a CubeSat launch costs a lot, but you can get a drone and a spool of fishing line for cheap. Cueball: Uh oh. [A wide shot of Megan flying the drone with the cube at her feet while Cueball stand behind her looking after the drone that flies up to the left.] Megan: No no, watch. Megan: This is gonna go great. [Wide shot of a rocket standing on its launch pad with the support tower. The, now very small, drone is approaching, string attached, from the right.] [Slim shot of the rocket as the drone attaches to the rocket, just under the tip with the payload. The string goes down and out to the right.] Megan (off-panel): Perfect! [A huge cloud is emitted from the bottom of the rocket as it lift off the ground every so slightly.] Foom [As the rocket is taking off it begins tilting in the direction of the string. Two off-panel voices come from Megan and Cueball's direction.] Off-panel voice #1: Should it be tilting already? Off-panel voice #2: Hey, move your leg. [Close up of Megan and Cueball struggling in tangle of string that surrounds Megan while she is holding the cube in one hand and the remote for the drone in the other. Cueball uses both hands to try and help her out of the tangle. The string goes out to the left towards the rocket.] Megan: Ugh, let go, I can get- Cueball: -No, lift your other arm- [Three slim panels follow, one above the others, of the rocket, with string, tilting increasingly to the right and down as if pulled by the string. In the final panel of the three the tip of the rocket is now further than where the string goes down to the bottom of the panel. So the string now goes back left from where it is attached to the rocket, rather than to the right as in all previous panels.] [Megan entangled in the string with the cube in her hand and Cueball hanging below her holding on to the string, are flying through the air, as the string goes up right, and with small lines drawn above it to indicate it is moving to the right. On the ground Science Girl holds a hand to her mouth looking up at them, while a guy looking like Cueball runs away with hands over his head.] Megan and Cueball (screaming): Aaaaaa [A disheveled looking Megan and Cueball both with plaster casts on their arms stand before four people, Hairbun, another Cueball like guy, Ponytail and Hairy. They are the members of an interview panel and are sitting behind a desk like table with a large label on its front:] Launch accident investigation board Megan: Listen. Megan: Space exploration is never going to be completely safe.

Alternate Histories

Alternate Histories

https://www.xkcd.com/2149

https://www.explainxkcd.com/wiki/index.php/2149:_Alternate_Histories

[Megan and Cueball are walking together] Megan: In alternate history stories where the allies lost WWII, sometimes they have their own fiction with the premise "what if the allies had won ?" which differs from our world since they'd be speculating and wouldn't predict everything. Cueball: Yeah, I think they do that in Man in the High Castle . [Megan and Cueball continue walking together] Megan: But within those stories, they should have "what if the allies had lost ?" fiction which is even more removed from our world. Cueball: Uh oh. Megan: So how deep does it go? [Cueball and Megan, wearing tall black ball-topped hats and large bracelets and presumably from some alternate history, are walking together. There is a caption in a frame over the top of the panel] 500 levels in: Megan: In my alternate history, Scotland never develops hovercraft, so Canada's cybernetic horses defeat the Belgium-Madagascar-New Jersey alliance. Cueball: Wow! [Alternate history Cueball and Megan continue walking together] Cueball: Then who becomes God-Emperor of Missouri, if not Laura Ingalls Wilder? Megan: Senator Truman! Cueball: He survives the accident?! Megan: Yeah, the pajama craze never catches on, so he's wearing normal clothes when he walks by the printing press...

Alternate histories are a common device in speculative fiction. One of the most common (even cliche) uses of alternate history is to posit a world in which the Axis Powers achieved victory in World War II . This is presumably so compelling because it was a relatively recent event in which a series of relatively minor changes could have altered world history in major ways. One of the standard literary works along this line is Philip K. Dick's The Man in the High Castle , where the world is split into spheres of influence controlled by the Empire of Japan and Nazi Germany . This novel has been developed into a popular TV series of the same name on Amazon Prime. At one point, The Man in the High Castle discusses the fiction of their own world, which includes their own alternate histories in which the Allies had won the war instead. The Grasshopper Lies Heavy is one such novel. Because these stories are speculative, they don't entirely match the 'real' history of our world, differing in key ways. This results in an "alternate-alternate" history where the Allies won World War II, but the details still differ rather significantly than the history of World War II in our reality -- most notably, The Grasshopper Lies Heavy depicts a post-World War II world defined by a Cold War between the United States and the British Empire, rather than one between the United States and Soviet Union. In one sense, this functions as a meta-critique of the very concept of alternate histories, highlighting the reality that we can never know the details of what would have happened if history had gone differently. In this comic, Megan and Cueball discuss this fictional device. Then in typical xkcd fashion, things start to get exaggerated to ridiculous proportions: Megan points out that, if characters in our stories have their own fiction, then the characters in their stories presumably have their own body of fiction, and so on, creating a recursive loop. If each alternate history contains its own alternate history, presumably each iteration would deviate more and more from our own reality, because each would be speculation based on increasing layers of speculation. Eventually (by the 500th iteration) the history would differ so wildly from our own as to be completely absurd to us, with very few elements being even recognizable. The 500th iteration timeline apparently includes hovercraft and cybernetic horses. Hovercraft are a real technology which does have military applications as landing craft, but their use in actual warfare has been limited. Cybernetic horses do not exist in our timeline yet [ citation needed ] , but Boston Dynamics is getting close. In our timeline, Scotland is part of the United Kingdom, and would likely not develop military technology independently. New Jersey is a state in the United States and Madagascar was controlled by France during World War II; neither of these would normally be able to pursue an independent foreign policy that would have allowed them to join alliances and fight wars unless their parent governments also did. Belgium was occupied by the Axis Powers early in the war. These three regions developing a alliance and fighting against Canada (which was also an Allied power) would require a highly unlikely combination of events. How this war would be affected by the lack of Scottish hovercraft is unclear. This scenario also apparently contains a theocracy of some variety in Missouri, which (remarkably!) is vaguely plausible. Interestingly, even within the bounds of the exceedingly meta-fiction, it is bordering on impossible for the scenario to come into existence; the reason for this is that while the ending would become evermore bizarre, the actual events will only be able to vary so much, as they are based on predetermined scenarios that occur before the changes take place. Unless at least two wars are being modified, or the events are based on a later occurrence, (basically the two are discussing something different entirely, albeit still a historical scenario) the idea of so many implausible things occurring is unlikely no matter what the circumstances, unless they all happened over the course of the war. Of course, it's possible several of those 500 iterations involve BAD alternate histories fiction. Or possibly fiction based on history which was deliberately falsified. It's unlikely, but it's worth noting that "cybernetic horses" could be a reference to cyber forces , since in 1418: Horse that substitution is suggested. Laura Ingalls Wilder was an American author, best known for her Little House on the Prairie series. In the 500th iteration timeline, she apparently became "God-Emperor of Missouri", despite not being known as a political figure in our timeline. Harry S Truman , in our timeline, became 33rd President of the United States, following the death of Franklin Delano Roosevelt. In the 500th iteration timeline, Truman apparently died in an accident involving pajamas and a printing press while still a senator (presumably a U.S. senator, since in our reality he was serving in the United States Senate prior to being nominated as Roosevelt's vice president in 1944). He apparently remained a significant enough figure for 500th-iteration Megan to speculate that he would have become God-Emperor of Missouri if he'd survived. The title text continues the discussion about Truman, mentioning a photograph of Truman screaming in horror as he is hoisted by newspaper-printing machinery. This plays off a famous photograph from our world where Truman is the one hoisting up a copy of the Chicago Tribune in triumph, as said newspaper erroneously claimed he was defeated in the 1948 United States presidential election by Thomas Dewey . [Megan and Cueball are walking together] Megan: In alternate history stories where the allies lost WWII, sometimes they have their own fiction with the premise "what if the allies had won ?" which differs from our world since they'd be speculating and wouldn't predict everything. Cueball: Yeah, I think they do that in Man in the High Castle . [Megan and Cueball continue walking together] Megan: But within those stories, they should have "what if the allies had lost ?" fiction which is even more removed from our world. Cueball: Uh oh. Megan: So how deep does it go? [Cueball and Megan, wearing tall black ball-topped hats and large bracelets and presumably from some alternate history, are walking together. There is a caption in a frame over the top of the panel] 500 levels in: Megan: In my alternate history, Scotland never develops hovercraft, so Canada's cybernetic horses defeat the Belgium-Madagascar-New Jersey alliance. Cueball: Wow! [Alternate history Cueball and Megan continue walking together] Cueball: Then who becomes God-Emperor of Missouri, if not Laura Ingalls Wilder? Megan: Senator Truman! Cueball: He survives the accident?! Megan: Yeah, the pajama craze never catches on, so he's wearing normal clothes when he walks by the printing press...

XKeyboarCD

XKeyboarCD

https://www.xkcd.com/2150

https://www.explainxkcd.com/wiki/index.php/2150:_XKeyboarCD

[Headings above a drawing of a very special keyboard:] Introducing the XKeyboarCD A keyboard for powerful users and their powerful fingers® [The keyboard has many more keys than a usual Keyboard. Usual keyboards for stationary computers typically have a few of the rows with 21 keys, and then some with fewer. This Keyboard has 28 keys on the top row. The other rows have special keys that make it difficult to compare, but there is basically also room for 28 in the bottom row, except one spot where there is one key in a space for 2x2 keys. Begining from the bottom and coutning keys there are 27. Skipping those that take up space in two or more rows, when going to the next row from the bottom there are 23, then 24, then 18, then 27 and finally 28 keys in the top row, for a total of 147 keys (vs 105 on a regular keyboard). Then there are 54 extra keys above the keyboard to the left (27 shown) and 156 in 6 rows of 26 to the right for a total of 357 keys 330 shown. All six rows have keys all the way over with no empty space in between, as there are on regular keyboards. Also there are no space between the top row (with F1 button etc) and those below. At each side of the keyboard the keys do no align at the edges, which is normally the case. The keyboard has several special features, most of which are labeled. The only special features that is not labeled is a small square with 2x2 keys that are elevated a bit above all other keys. It is in the region above the normal position of the four arrows. All eight other special features have an arrow pointing to them from their labels. Here below is a description of the labeled items as well as a transcript of their labels. They are listed in the order of their labels first above and then below the keyboard going from left to right.] [Five keys close to the QWERTY keys positions have colorful emoji on them. They each take up the space of 2x2 normal keys, although it is not clear if all the "normal" keys have the same size:] Hardcoded plastic keys for the 5 most useful emoji 😰 😂 🐙 🏇 🚡 [A cube with 3x3 keys on each side hangs above the keyboard to the left supported by a small rod. Three sides are fully visible, 27 keys:] 54 configurable Rubik's keys [Just right of the middle above the main keyboard is a cylinder with keys inside in 6 rows of 26 keys (126 in all). It either decreases in diameter into it making it look almost like a tunnel, or is drawn as if it almost disappear in the far distance, being much deeper than it should be.] Ergonomic design [In the region where the normal numberpad would be there are 15 numbers from 1 to 15 in a 4x4 grid leaving space for an empty key hole. There is a row of keys both above and below this grid. The numbers do not come in order from 1 to 15, but rather in a jumble. Also the empty hole is not a full key spot. Instead it is in the second row of numbers, with a bit more space to the left than to the right of the middle of the three keys.] 15 puzzle-style numberpad 1 8 4 12 7 Empty area 11 3 15 6 10 9 2 5 13 14 [To the left in the second row (below the Caps Lock position) the outer key is twice as wide as the other normal keys.] Serif Lock [An arrow points to the eight key in the bottom row, but is probably just referring to all the keys in general:] Unlimited key travel [There is a segment of the keyboard that seems to be empty of keys, but still white like the rest of the keys, not black as where keys are actually missing. It is where on a regular keyboard, the normal keys are separated from the special function keys. But it turns out it is indeed a long key going vertically:] Diagonal spacebar [Where the four arrow keys are on a regular keyboard there is a 2x2 key segment that only has one key in the middle with black background around it. It has an arrow head on it pointing right. That is if the key had not been turned about 45 degree counter clockwise, so the arrow points up to the right.] Arrow key (rotate to adjust direction)

In the same vein (and with the same humor) as the xkcd Phone series , the XKeyboarCD seems to be an overly inventive and borderline ludicrous keyboard intended for some unknown audience. It has an assortment of features (some fairly normal, some more exotic) which give it a..."diverse skill set". This may be in reference to Space-cadet keyboards which were made for programmers and had several keys not present on standard QWERTY keyboards. XKeyboarCD is a play on xkcd, and keyboard. (XK eyboar CD) 54 Configurable Rubik's Keys The tiles on a Rubik's cube (just 'colours' on actually good cubes, such as Valk cubes) resemble computer keys, so this feature makes fun of that by adding a spinnable Rubik's cube above the keyboard. The implication is that the keys would be 'configured' by twisting the sides of the cube until the desired configuration is reached, although parity means that not all configurations could be reached by conventional means by a 3x3 cube. (Parity exists on 4x4 cubes.) There can be a maximum of 53 keys (the bottom center position can't contain a key because it's the mounting position). Additionally, the top key can't be moved around, so the maximum amount of configurable keys is 52. (The four remaining centers can be moved by rotating the entire cube.) The bottom-facing keys would obviously be hard to see/reach. Hardcoded Plastic Keys for the 5 Most Useful Emoji This feature parodies the feature of some laptop-keyboards where it is possible to dynamically assign emojis to a small touchscreen area. There is a disaccord between hard-coded, useful and emoji, especially with the large keys in a central position on the keyboard. Which emojis would be "the most useful" is highly subjective. For example in the comic it shows the quite popular laughing with tears emoji, along with the octopus emoji and others. Notably, the "aerial tramway" was once the least-used emoji, and remains very rarely used. Serif Lock Serifs are small lines on the ends of certain characters in fonts such as Times New Roman and Georgia. It is dependent on the font, not on the character; "A" is represented by the same code regardless of its font. Since a given font almost always either has or doesn't have serifs, this key seems challenging to implement. This key could be implemented, however, by simply changing between a pair of fonts when it is pressed, or by using the characters in the Mathematical Alphanumeric Symbols block. What's more, the button is placed roughly where left shift is on most keyboards, liable to cause frustration. Unlimited Key Travel Key travel is the distance a key moves between its unpressed and pressed states. In reality, laptop keys only move a few millimeters before bottoming out, and conventional keyboards up to about a centimeter. Increased key travel may make typing more comfortable, up to a point. However, the usefulness of having unlimited key travel is unclear, and the question of how this would be physically possible in the keyboard depicted remains unanswered. The keyboard would have to be infinitely deep to allow unlimited key travel, although pushing it to the near bottom would require infinitely long fingers. At least it is the greatest possible value, trumping any other keyboard. Diagonal Spacebar Instead of a wide key at the bottom that typists can hit easily with either thumb, we now have a tall, narrow key that requires being pressed with the right pinkie. This would not be a good change since most peoples' pinkies are their weakest finger. Some ergonomic keyboards have a slightly curved spacebar or a separated spacebar for each thumb. Arrow Key (Rotate to Adjust Direction) This is essentially a jog dial , or similar rotary encoder . These are sometimes used with keyboards: as controls for volume, video editing, or drawing. Many computer keyboards have four arrow keys : up, left, right, and down. However, the XKeyboarCD just has one that can be rotated. This has the added bonus of allowing the arrow keys to point more than four different directions. In a keyboard, it would be awkward to operate as going from horizontally left to horizontally right, for example, would require the user to rotate the key first and then press it, which wastes precious time when playing a video game like the hoverboard comic , where you have to rapidly press arrow keys to move around. It would not let one press multiple arrow keys at once. Trackpoint devices provide similar joystick-like direction function, but are easier to control with a finger. 15 Puzzle-Style Numberpad A 15 puzzle is a square containing fifteen smaller squares and one blank spot, which allows the squares to be moved around. The squares are shuffled and then reassembled as a game or pastime, and are usually labelled 1-15 (as is the case here) or, when assembled properly, create a picture. A numberpad in this style would be frustrating to use for typing numbers, as they could shift (or be shifted) around, but could provide a fun feature to use as a game. Alternatively the keys could be rearranged as with the Rubik`s keys. How this would be used to generate numeric input is unclear, but the presence of 16 positions suggests hexadecimal input is possible. Keyboard keypads do have around 17 keys, but only 0-9 usually have numbers whereas the XKCD keypad has numbers 1-15 in the middle of the numberpad probably also surrounded by the more conventional arithmetic operators, enter, and decimal point. Ergonomic Design The cylindrical portion of the keyboard is advertised as being an ergonomic design. Most ergonomic keyboards are both curved into a convex shape and split in the middle, with the blocks of keys on either side rotated around the vertical axis. This is done to follow natural arm and finger movements more closely, that is, avoid forcing the user to rotate their arms and hands to match the flat and rectangular key arrangement of a non-ergonomic keyboard. Some ergonomic keyboards come in unconventional form factors, such as vertical keyboards, to allow the user's hands to rest in more neutral positions or to change positions throughout the day, but the cylinder shape presented here is a concave shape which requires the user to lift and twist his arms to reach certain keys (or roll the cylinder from side to side), which would be an even more strenuous motion than typing on a standard keyboard. The slogan of the keyboard — "for power users and their powerful fingers" — fits this difficulty, but makes no sense as a feature. The title text references sound changes in languages. Every language (and indeed, every dialect) routinely undergoes changes in its sounds and phonemes, in a mostly regular and systematic, but not totally predictable way (otherways the dialects would sound the same and also the century, when a shift occurs, and the rate of change are not predictable). While not only vowels are affected, in languages with many vowels such as English, they're particularly likely to shift around and/or merge. While having dynamic keycaps that change can actually come in handy, the feature of only having vowels change in response to sound shifts is a bit less so. One normally enters the spelling and not the pronunciation of words (except with some Asian input systems). The spelling and pronunciation do not change at the same time. Firstly, while changes in how we pronounce words are always ongoing, the way we write words down tends to stay relatively static, and thahs wiy wuhd faynd thaet werds biykahm ihnkaammpriyhehnsihbuhl duew tuow nhw laager biyigg sphld es thy wor bifffrr. Second, English only uses five glyphs (aeiou) and a variety of methods to represent four times as many vowel sounds, so the software would need to have a way to handling that (in some dialects "bird" and "turn" for example, have the same vowel but are represented by "ir" and "ur", as it also can be by the "er" in the bird called the " tern " - or not). Third, vowel shifts are not ubiquitous: the Caught-cot merger , for example, is a phenomenon happening across some parts (but not all) of the US and UK. Therefore, while some people would say "caught" and "cot" have the same vowel it should be spelled the same by the keyboard, but others would say they're two different vowels and should not be spelled identically. Fourth, sound shifts tend to occur over a relatively long period of time (in terms of human lifetimes), so a user would probably find the keycaps only change once or twice. All in all, this is not a very useful feature. An alternative explanation is that the keys actually map to the International Phonetic Alphabet and converts what you type into English words (and the vowel changes). The IPA is an alphabet used in linguistics and language teaching, designed to represent every phoneme present in languages of the world unambiguously, with optional modifiers to indicate more subtle nuances in pronunciation, intonation and speech pathology. This alphabet consists of 107 letters and 56 modifiers (with some letters shared with the Latin and Greek alphabets), which would explain the large number of keys. In that case, the feature remains questionable since it only handles vowel shifts and not consonants, and anybody who'd use an IPA-keyboard would probably need to type out the phonology of other languages and appreciate not having to find a key has moved because English has undergone a vowel shift. This is the second time that the "xkcd" has been used around a middle word, which uses some of the xkcd letters to form this word. The first was 1506: xkcloud - XKC lou D, to spell ClouD with the C and D from XKCD, in that comic the letters were all lowercase. In this comic the Keyboard, has an X before the word and a C before the D with the xkcd letters capitalized. [Headings above a drawing of a very special keyboard:] Introducing the XKeyboarCD A keyboard for powerful users and their powerful fingers® [The keyboard has many more keys than a usual Keyboard. Usual keyboards for stationary computers typically have a few of the rows with 21 keys, and then some with fewer. This Keyboard has 28 keys on the top row. The other rows have special keys that make it difficult to compare, but there is basically also room for 28 in the bottom row, except one spot where there is one key in a space for 2x2 keys. Begining from the bottom and coutning keys there are 27. Skipping those that take up space in two or more rows, when going to the next row from the bottom there are 23, then 24, then 18, then 27 and finally 28 keys in the top row, for a total of 147 keys (vs 105 on a regular keyboard). Then there are 54 extra keys above the keyboard to the left (27 shown) and 156 in 6 rows of 26 to the right for a total of 357 keys 330 shown. All six rows have keys all the way over with no empty space in between, as there are on regular keyboards. Also there are no space between the top row (with F1 button etc) and those below. At each side of the keyboard the keys do no align at the edges, which is normally the case. The keyboard has several special features, most of which are labeled. The only special features that is not labeled is a small square with 2x2 keys that are elevated a bit above all other keys. It is in the region above the normal position of the four arrows. All eight other special features have an arrow pointing to them from their labels. Here below is a description of the labeled items as well as a transcript of their labels. They are listed in the order of their labels first above and then below the keyboard going from left to right.] [Five keys close to the QWERTY keys positions have colorful emoji on them. They each take up the space of 2x2 normal keys, although it is not clear if all the "normal" keys have the same size:] Hardcoded plastic keys for the 5 most useful emoji 😰 😂 🐙 🏇 🚡 [A cube with 3x3 keys on each side hangs above the keyboard to the left supported by a small rod. Three sides are fully visible, 27 keys:] 54 configurable Rubik's keys [Just right of the middle above the main keyboard is a cylinder with keys inside in 6 rows of 26 keys (126 in all). It either decreases in diameter into it making it look almost like a tunnel, or is drawn as if it almost disappear in the far distance, being much deeper than it should be.] Ergonomic design [In the region where the normal numberpad would be there are 15 numbers from 1 to 15 in a 4x4 grid leaving space for an empty key hole. There is a row of keys both above and below this grid. The numbers do not come in order from 1 to 15, but rather in a jumble. Also the empty hole is not a full key spot. Instead it is in the second row of numbers, with a bit more space to the left than to the right of the middle of the three keys.] 15 puzzle-style numberpad 1 8 4 12 7 Empty area 11 3 15 6 10 9 2 5 13 14 [To the left in the second row (below the Caps Lock position) the outer key is twice as wide as the other normal keys.] Serif Lock [An arrow points to the eight key in the bottom row, but is probably just referring to all the keys in general:] Unlimited key travel [There is a segment of the keyboard that seems to be empty of keys, but still white like the rest of the keys, not black as where keys are actually missing. It is where on a regular keyboard, the normal keys are separated from the special function keys. But it turns out it is indeed a long key going vertically:] Diagonal spacebar [Where the four arrow keys are on a regular keyboard there is a 2x2 key segment that only has one key in the middle with black background around it. It has an arrow head on it pointing right. That is if the key had not been turned about 45 degree counter clockwise, so the arrow points up to the right.] Arrow key (rotate to adjust direction)

A/B

A/B

https://www.xkcd.com/2151

https://www.explainxkcd.com/wiki/index.php/2151:_A/B

[Cueball is sitting behind a computer desk, facing to the right, gesturing at the screen. Ponytail stands behind him and Hairy stands in front of him, both taking notes in a pad.] Cueball: I like this one more because it encodes Mycenaean Greek. The other one just looks like gibberish. [Caption below the panel:] Linear A/B testing Versions of the script engine used in early versions of the Opera web browser were named after ancient writing scripts: Linear A, Linear B, Futhark (the oldest form of the runic alphabets used by Germanic tribes), and Carakan ( Javanese script known as Aksara Jawa, a modern variant of Aksara Kawi).

A/B testing is a form of controlled experiment in which test subjects are randomly split into two groups, A and B, and each group is shown a slightly different version of the same thing. This is most often used for market research, as it allows researchers to discover which of two options are received more favorably by consumers. For example, a website might employ A/B testing by randomly showing 50% of visitors a version with a different font. By checking their site traffic analytics afterward, the site operators can see which version of the site received the most user engagement, which might tell them that the alternate font is a better choice. Linear A is an as-of-yet undeciphered writing system of the ancient Minoan civilization (a civilization based on the island of Crete ). It appears similar to the deciphered Linear B writing system, but if the pronunciation rules of Linear B are applied to Linear A, it produces a language unrelated to any known language. Linear B , on the other hand, has been deciphered. It is a syllabic script that was used for writing Mycenaean Greek , the earliest form of Greek for which we have evidence. It predates the Greek alphabet by several centuries and likely evolved out of the earlier Linear A writing system. While not completely consistent with the definition of A/B testing presented above, the comic jokingly suggests that the choice of writing system could be decided through A/B testing, with the "A" and "B" literally being Linear A and Linear B. The test subject apparently can read Linear B (which encodes Mycenaean Greek), but not Linear A (which produces what's seemingly gibberish when read through the rules of Linear B). It is also a pun on the common phrase "[it's] Greek to me ", which people use to refer to something as gibberish, but here, it is the Greek text which is comprehensible to Cueball , while instead the other one isn't. The title text explains the selection of script code (i.e. programming language ) used to create the web site. Aksara Kawi is a script (i.e. a writing system) that was used on the island of Java (today part of Indonesia) from the 8th century until 1500 AD. Referring to it as "Java script" is a pun on JavaScript , which is a browser scripting language for creating web pages. Here, Linear A ("Crete script") is selected as the "script" language over Aksara Kawi because it rendered faster in testing. [Cueball is sitting behind a computer desk, facing to the right, gesturing at the screen. Ponytail stands behind him and Hairy stands in front of him, both taking notes in a pad.] Cueball: I like this one more because it encodes Mycenaean Greek. The other one just looks like gibberish. [Caption below the panel:] Linear A/B testing Versions of the script engine used in early versions of the Opera web browser were named after ancient writing scripts: Linear A, Linear B, Futhark (the oldest form of the runic alphabets used by Germanic tribes), and Carakan ( Javanese script known as Aksara Jawa, a modern variant of Aksara Kawi).

Westerns

Westerns

https://www.xkcd.com/2152

https://www.explainxkcd.com/wiki/index.php/2152:_Westerns

[A horizontal timeline spanning between the years 1840 and 2020. Every decade is indicated by a tick below the line, and labeled every 50 years. Two ranges are highlighted by brackets and labeled:] [1862-1898:] The "Wild West" era [1902-2019:] Western films, books, video games, etc [Caption below the panel:] It's weird to realize that the Western genre has now existed for three times longer than the period it's based on.

The " western " genre refers to narrative works set in the American " Old West " west of the Mississippi River between the years of 1865 (when the Civil War ended) and 1895 (when the US Census officially declared the frontier to be closed). These dates are naturally somewhat arbitrary, but most works in the genre are set more or less in that relatively narrow window of time. This definition may be too narrow, however, as many events related to the American West took place before the Civil War. The fur trade was significant in the western frontier from the early 1800s to about 1845. The Oregon Trail saw its first wagon trail in 1836, and along with variants such as the California and Utah/Mormon trail, was regularly and heavily used beginning around 1845-1847. The California Gold Rush took place in 1849. Stories of fur trapping, wagon trains, and mining all feature heavily in the "western" genre, making the disparity between the length of real history and the length of historical fiction less great. This era in American history was marked by aggressive settling of western lands. The US had pursued an expansionist policy known as " Manifest Destiny ", which had the primary goal of extending US borders across the continent. This led to various strategies to increase the lands under US control (ranging from diplomatic efforts to expansionist wars), displacing, containing, and eliminating native peoples from the land, and encouraging American settlement in the western territories. Settlers were encouraged to go west with the promise of cheap or free land for agriculture, mineral riches, and freedom from the dangers of large cities. These sparsely populated lands quickly gained a reputation for being dangerous, unpredictable, and violent. The men and women who settled them were admired as rugged individualists, civilizing a wild frontier through hard work, courage and persistence. The mythos of the "wild west" arguably continues to impact American culture to this day. The timeline in this strip suggests that the Western genre began almost immediately after the frontier closed. This matches the "official" timeline. The first critically recognized Western novel, The Virginian , was published in 1902, and one of the earliest silent films, The Great Train Robbery , was made in 1903. However, it should be noted that pulp novels and magazines set in the frontier, as well as "Wild West Shows" that toured the eastern states and Europe had begun decades earlier. And the end of the "Wild West" era can be considered to have lasted into the 1910's, or even the 1920's. In other words, Westerns were an established genre while the real western frontier was still in existence. The genre transitioned from a contemporary setting to a historical one without significant disruption. The Western genre has varied in popularity, but has never gone away, and continued to produce popular works throughout the 20th century and into the 21st. Artists who grew up admiring Western heroes have proceeded to use the genre for their own visions, and have reinterpreted the setting across multiple generations, and an evolving media landscape. Literature, music and live performances gave way to film, then television, and now video games. This strip points out the irony that the actual Old West took place over a fairly limited time and space, but the setting has managed to accommodate a genre that's maintained popularity for over a century (at least three times as long as the actual frontier era) and is consumed both throughout the US and across the world. The title text is in reference to the popular video game Red Dead Redemption 2 , which takes place in an Old West setting. Red Dead Redemption 2 has already sold in excess of 24 million copies, while at the 1890 census the entire West - even going by the widest definition, counting every state and territory west of the Mississippi - had a population of just 16.8 million. The region now counted by the US Census Bureau as the "Western United States" was even smaller, at just 3.64 million. Assuming every copy sold represents one player (some sold may not have been played, but others sold may account for multiple players), not only are there more RDR2 players than there were people in the Wild West at its height, there may be more than lived in the region at all during the frontier years. A similar question was asked in what if? WWII Films . [A horizontal timeline spanning between the years 1840 and 2020. Every decade is indicated by a tick below the line, and labeled every 50 years. Two ranges are highlighted by brackets and labeled:] [1862-1898:] The "Wild West" era [1902-2019:] Western films, books, video games, etc [Caption below the panel:] It's weird to realize that the Western genre has now existed for three times longer than the period it's based on.

Effects of High Altitude

Effects of High Altitude

https://www.xkcd.com/2153

https://www.explainxkcd.com/wiki/index.php/2153:_Effects_of_High_Altitude

Effects of High Altitude How life is different at one mile above sea level (e.g. in Denver) [Eight small panels, each containing an image with a caption at the top:] [A pot on a stovetop, with steam rising from the pot] Water boils at 202°F [A baseball flying through the air] Baseballs and golf balls fly 5-10% farther [Five wavy arrows hitting a curved surface, two at a low point and three at a high point] Sunburns develop significantly faster [Scrabble tiles for letters Q, X and Y with point values 12, 9 and 5, respectively] Scrabble letters are worth 16% more [Cueball looking down at a broken hand mirror on the floor] Breaking a mirror only causes 5½ years of bad luck [Cueball and Megan are talking. Megan is gesturing] 40 is the new 28 Megan: 50 is the new 40, and when you account for elevation it's more like 37. [Five black balloons floating] Nuclear war can be started with only 94 red balloons. [Cueball and Ponytail are talking. Ponytail is looking at her phone] People make marijuana jokes slightly earlier Cueball: Hey, what time is it? Ponytail: 4:17 Blaze it!

This comic starts out with three effects of high altitude related to the air getting "thinner" and the lower air pressure. Denver is one mile (5280 feet or 1609 meters) above sea-level (as marked on the steps of the State Capitol). At this elevation, the average atmospheric pressure is about 83% of sea level pressure, or about 840 mbar instead of 1013 mbar, and gravity is 99.94% of gravity at sea level at the same latitude, or 9.796 m/s 2 instead of 9.801 m/s 2 . This has a number of effects: As usual for xkcd, the effects of high altitude are extended in a comically absurd manner, applying this "slightly less" rule to things that have nothing to do with altitude: This point increase would have little impact in the board game when two players sit across each other. However, it would imply that scrabble played via internet should require players to state their altitude at the beginning of the online game which then assigns advantages to higher-altitude players. This advantage seems arbitrary, unless the altitude difference is really significant enough to impede the thinking ability of the higher-altitude party. In the title text, One Hundred and One Dalmatians is a Disney franchise (based on a children's book), where the villain, Cruella de Vil , aims to capture and kill 99 Dalmatian puppies (97 in the book) to have the perfect spotted fur coat. (The title includes the parents [book: and other Dalmatian caregivers] of the Dalmatian puppies.) The comic claims that, at a higher altitude in Flagstaff (6903 ft / 2104 m), she would only have needed 89 Dalmatians, possibly implying that puppies at higher altitudes are bigger (perhaps because there is less air pressure to compress them ) or that Cruella de Vil at high altitudes is smaller (possibly because of the higher humidity and lower temperature ). Effects of High Altitude How life is different at one mile above sea level (e.g. in Denver) [Eight small panels, each containing an image with a caption at the top:] [A pot on a stovetop, with steam rising from the pot] Water boils at 202°F [A baseball flying through the air] Baseballs and golf balls fly 5-10% farther [Five wavy arrows hitting a curved surface, two at a low point and three at a high point] Sunburns develop significantly faster [Scrabble tiles for letters Q, X and Y with point values 12, 9 and 5, respectively] Scrabble letters are worth 16% more [Cueball looking down at a broken hand mirror on the floor] Breaking a mirror only causes 5½ years of bad luck [Cueball and Megan are talking. Megan is gesturing] 40 is the new 28 Megan: 50 is the new 40, and when you account for elevation it's more like 37. [Five black balloons floating] Nuclear war can be started with only 94 red balloons. [Cueball and Ponytail are talking. Ponytail is looking at her phone] People make marijuana jokes slightly earlier Cueball: Hey, what time is it? Ponytail: 4:17 Blaze it!

Motivation

Motivation

https://www.xkcd.com/2154

https://www.explainxkcd.com/wiki/index.php/2154:_Motivation

[Cueball and Ponytail sitting at a desk, working on their laptops.] Cueball: What are you working on? Ponytail: Playing a game that involves exactly as much planning, problem-solving and boring drudgework as the actual job I'm avoiding. [Zoom in on Cueball, leaning back with one arm on the back of his chair.] Cueball: Haha, yeah, I've definitely been there. [Zoom back out to Cueball and Ponytail sitting at a desk, working on their laptops.] Cueball: What's your job these days, anyway? Ponytail: Video game playtester. Cueball: ... Ponytail: Look, motivation is weird, ok?

Motivation is an important part of human psychology . It arouses a person to act towards a desired goal. It is a driving force which promotes action. As Ponytail is feeling unmotivated to do her job, she decides to procrastinate by playing a video game on her laptop instead, with the hope that she will eventually be more motivated to do her assigned task. Cueball seems to understand her sentiment, and admits to being in the same situation in the past, seemingly assuming she's referring to games that feel like work. Games are sometimes criticized for feeling like work. This is usually aimed at games that simulate an actual or historical job which can frequently cause the player to have to check each individual plant as if he were an actual gardener, or work out a cost-benefit analysis as if he were an actual manager. This is more generally applied to any video game grinding , also known as farming. This is why when Cueball asks Ponytail what she's doing, she replies that she's playing a game that involves exactly as much planning, problem-solving and boring drudgework as the actual job she's avoiding. Cueball then laughs and says that he has definitely been there before, before asking Ponytail what her job is. The punch line for this comic comes when Ponytail admits that her actual job is a video game playtester , someone whose job is to test and play video games. So it seems that Ponytail is avoiding doing her task to test video game X by playing video game Y. As a result, her original statement can be interpreted in a completely different way: Instead of comparing the game she's playing to a regular job, implying that grinding is as difficult and boring as an actual job, playing games is her actual job, and she's simply comparing two games she's playing. Though being a game tester can be seen as glamorous and fun to people who enjoy playing video games ("I get to play video games all day at work"), it is less rewarding than it may seem , as game testers often aren't playing the game but are testing it by constantly doing mundane tasks and running through a game that they may not like to identify bugs and problems, which is far less enjoyable than playing a game one likes for fun, even if it requires a grind. The title text continues Ponytail's admission, adding that she had originally been assigned to play video game Y in the first place, and was previously procrastinating by playing video game X. Her company may have caught on to her procrastination, as they then changed her assignment to work on video game X that she was already playing to procrastinate. To further procrastinate herself, Ponytail changed to play video game Y, the original video game that she was assigned. However, this would not serve to have her work on her original task to test video game Y. Testing a video game is very different from playing a video game while procrastinating. For example, video game testers must intentionally make "mistakes" to verify that the game responds correctly and, more importantly, report on what worked or didn't work. Playing normally, while attempting to win, would not yield the data obtained from proper testing. [Cueball and Ponytail sitting at a desk, working on their laptops.] Cueball: What are you working on? Ponytail: Playing a game that involves exactly as much planning, problem-solving and boring drudgework as the actual job I'm avoiding. [Zoom in on Cueball, leaning back with one arm on the back of his chair.] Cueball: Haha, yeah, I've definitely been there. [Zoom back out to Cueball and Ponytail sitting at a desk, working on their laptops.] Cueball: What's your job these days, anyway? Ponytail: Video game playtester. Cueball: ... Ponytail: Look, motivation is weird, ok?

Swimming

Swimming

https://www.xkcd.com/2155

https://www.explainxkcd.com/wiki/index.php/2155:_Swimming

[The single panel comic is around 4 times higher than it is wide (317×1284 pixels). A Cueball is watching from the beach while Megan with another character is standing neck deep in water near an extreme drop off (continental shelf?) and another Cueball is swimming further. This part of the comic is at the very top, and the characters are drawn much smaller than usual.] Megan: It's OK, I can still touch bottom here. [As the tall image is scrolled down, there are some deep water fish, a jellyfish, and an octopus, a bottom ledge with a beach umbrella on it, and another drop off.] [Caption below the panel:] I love swimming, but occasionally I realize I don't know how deep the water under me is and it freaks me out.

This comic is about an irrational fear about the depth of water beneath oneself, also known as thalassophobia . Whenever you don't explicitly know how deep the water is, and cannot see the bottom, there is nothing preventing the sea/lake/riverbed from being exceptionally far away. This phenomenon is actually quite common with many bodies of water having a relatively shallow shelf extending a short ways out from land. These typically end with little to no warning, giving rise to the fear that is depicted here. It is an irrational fear because if one is swimming, the depth of the water underneath is not important to safety as long as one can reliably get back to shore. (This fear may be due to excessively worrying about what happens if one stops swimming, thinking that walking should be safer because almost everyone spends more time walking than swimming, ignoring the fact that the safest thing to do in this case is to keep swimming.) If one is wading, presumably one would feel the bottom drop away. Following the safety saying "Walk out, swim back" would help avoid this situation. Here, Megan and Cueball are in in the ocean, with Cueball treading water and Megan standing on the seabed, with another girl in the water and another Cueball watching from the beach. Megan mentions that she can still touch bottom, thus thinking it is safe. In front of her however the seabed drops off steeply, becoming nearly vertical. Fish and jellyfish are in the water below, while at the bottom of the frame, but not the sea floor, a small ledge holds an octopus and a beach umbrella. The beach umbrella may be from the beach, to give human scale. It could also be a Lemmings reference. The title text alludes to the fact that humans live at or near the bottom of a vast sea of air: the atmosphere. Every day, most people never rise far from the floor of the atmosphere. However, this is nowhere near as perilous as descending to the bottom of a sea of water. Indeed, surviving a rise to the top of the atmosphere requires life support measures. Also, unlike in water, humans are far too dense to "swim" (fly) in the atmosphere. [The single panel comic is around 4 times higher than it is wide (317×1284 pixels). A Cueball is watching from the beach while Megan with another character is standing neck deep in water near an extreme drop off (continental shelf?) and another Cueball is swimming further. This part of the comic is at the very top, and the characters are drawn much smaller than usual.] Megan: It's OK, I can still touch bottom here. [As the tall image is scrolled down, there are some deep water fish, a jellyfish, and an octopus, a bottom ledge with a beach umbrella on it, and another drop off.] [Caption below the panel:] I love swimming, but occasionally I realize I don't know how deep the water under me is and it freaks me out.

Ufo

Ufo

https://www.xkcd.com/2156

https://www.explainxkcd.com/wiki/index.php/2156:_Ufo

[Mulder from The X-Files depicted as Hairy sits in his office chair at his desk and points to his computer screen while looking over his shoulder and addressing Scully off-panel, who replies.] Mulder: Hey Scully, have you seen these Navy UFO videos? Scully (off-panel): Oh, the History Channel thing? [In a frame-less panel, Scully walks in from the right towards Mulder, who has turned around in his chair facing towards her (the desk is not included). He is leaning on the back of the chair with one arm. Scully has shoulder length hair, not similar to any of the regular women in xkcd.] Scully: I don't know about the other two videos, but in one of them, if you take the angles and ranges on the HUD and do a little geometry, it kind of suggests the object isn't really moving. It just looks like it because the plane's camera is panning. [Zoom in on Scully.] Scully: The pilots got excited for the same reason we did. Then the media got into it. Scully: But I think what they saw was a round, white object floating at 13,000 feet. [Zoom out again to shown that Mulder sits straight up in his chair with hands in his lap and the desk with computer behind him. Scully stand in front of him.] Mulder: So your theory is that the military claims to have footage of aliens, but you think it's a giant cover-up to hide that it's a weather balloon? Scully: Some kind of balloon, yes. Mulder: Pretty weird conspiracy. Scully: Maybe the shadowy forces that control the world just want to believe, too.

This cartoon makes fun of conspiracy theories , by suggesting that authorities, like the Navy, could be promoting mysterious explanations for mundane phenomena (such as a weather balloon ). UFO is an acronym for an unidentified flying object . This comic is most likely inspired by reports of US Navy pilots seeing unexplained objects. The "History Channel thing" could refer to this upcoming series . By a weather balloon, it is possible they could mean Cory Doctorow 's balloon, which he has appeared in past comics with. This comic features Fox Mulder and Dana Scully , two fictional FBI agents from the television show The X-Files . In the show, Mulder is usually a believer in all manner of conspiracies and supernatural phenomena, whereas his partner, Scully, is reflexively skeptical of any claims of the paranormal. A fighter aircraft's head-up display (HUD) projects information about the aircraft and its surroundings on a glass panel in front of the pilot. This allows the pilot to fly and fight without looking down at gauges and panels in the cockpit. When the pilot selects a radar contact to track, information including the angle and range to that contact is displayed on the HUD. The HUD is also overlaid on video recorded by the airplane's on-board camera. Scully has examined the tracking information recorded in one video and concluded that the unidentified object was relatively stationary. Her opinion is that the object is likely a mundane weather balloon, rather than an extraterrestrial craft. "Maybe the shadowy forces that control the world just want to believe" is an allusion to "I Want to Believe", a phrase from the The X-Files associated with Mulder and his iconic UFO poster. The title text also contains critique about governments that fail to acknowledge the severity of humanity-induced (anthropogenic) climate change and use their influence to actively hide evidence (such as the US government till 2021 that ordered US government agencies to stop or minimize research and reporting on climate change ), which even by Mulder's standards seems too crazy for a conspiracy, yet happens in reality. The government wanting to cover up a balloon to the point of allowing people to think it was aliens supposedly did happen, as documents declassified in the 90's revealed the existence of a top secret project to use high altitude spy balloons to detect evidence of Soviet nuclear tests, known as " Project Mogul ." One of these balloons was the source of the debris in the famous Roswell incident . To maintain secrecy, the government claimed it was instead a weather balloon despite this not being quite consistent with the descriptions of the debris, and how they didn't make an effort to properly refute things when 30 years later UFO enthusiasts started claiming it was an alien spaceship (the whole incident was quite obscure and quickly forgotten until someone published some claims about the events decades later, in 1978). [Mulder from The X-Files depicted as Hairy sits in his office chair at his desk and points to his computer screen while looking over his shoulder and addressing Scully off-panel, who replies.] Mulder: Hey Scully, have you seen these Navy UFO videos? Scully (off-panel): Oh, the History Channel thing? [In a frame-less panel, Scully walks in from the right towards Mulder, who has turned around in his chair facing towards her (the desk is not included). He is leaning on the back of the chair with one arm. Scully has shoulder length hair, not similar to any of the regular women in xkcd.] Scully: I don't know about the other two videos, but in one of them, if you take the angles and ranges on the HUD and do a little geometry, it kind of suggests the object isn't really moving. It just looks like it because the plane's camera is panning. [Zoom in on Scully.] Scully: The pilots got excited for the same reason we did. Then the media got into it. Scully: But I think what they saw was a round, white object floating at 13,000 feet. [Zoom out again to shown that Mulder sits straight up in his chair with hands in his lap and the desk with computer behind him. Scully stand in front of him.] Mulder: So your theory is that the military claims to have footage of aliens, but you think it's a giant cover-up to hide that it's a weather balloon? Scully: Some kind of balloon, yes. Mulder: Pretty weird conspiracy. Scully: Maybe the shadowy forces that control the world just want to believe, too.

Diploma Legal Notes

Diploma Legal Notes

https://www.xkcd.com/2157

https://www.explainxkcd.com/wiki/index.php/2157:_Diploma_Legal_Notes

[An official document with a title at the top between two images of graduation hats on either side:] Congratulations, Class of 2019! Your diploma grants you many new powers and privileges. These include: You may now legally perform marriages and arrest people. If you have your diploma with you, you can use grocery store express lanes with any number of items. All graduates are entitled to delete one word of their choice from the Oxford English Dictionary. The university will mail you your working lightsaber within 6-8 weeks. You can send mail without stamps. You have earned the right to challenge the British royal family to trial by combat. If you defeat them all, the throne is yours. You may now ignore "Do Not Pet" warnings on airport security dogs.

A class of 2019 graduate, presumably for some college or university, is given some rather unusual privileges for graduating. A common line in degree granting ceremonies is "the degree of X is conferred with all the rights and privileges pertaining thereto." This dates from the Roman Empire and continued through the rise of the university as an institution in medieval times. In the Roman era, the rights and privileges accorded to physicians and scholars included exemption from certain civic duties and military services, immunity from certain levies and from being summoned to court unduly, and even granting a state salary. In the medieval era, rights generally mirrored those of ecclesiastical figures and included immunity from civil law (instead scholars were subject to canon, or church law), as well as safe conduct on their travels between jurisdictions. While true that some degrees do grant professional privileges today, generally additional accreditation beyond the degree is required (passing the bar, medical certification, etc.) to gain anything most people would consider a privilege or right or incur any obligation. (The obligation to pay your student loans back exists regardless of completing your degree). You may now legally perform marriages and arrest people. Depending on the jurisdiction, these may or may not be privileges that one already has by virtue of being in a particular jurisdiction or being part of a particular culture. In some cultures, a couple might be recognized as married if they meet certain conditions (as opposed to being legally recognized by a religious or civil authority), such as being recognized by the community or after the birth of their first child . Because states often provide benefits (tax reductions, social services, etc) for being married, they often require that, in order to receive the benefits, that a marriage have a registered person recognize the marriage, which is likely the privilege that this graduating class' diploma is supposedly granting. In common law jurisdictions, citizen's arrest is legal without a warrant in some situations, although in many cases, it is better to let a police officer arrest criminals due to potential legal and safety issues that might arise. The privilege granted by graduating might grant or extend this privilege, depending on where the graduating class is located. If you have your diploma with you, you can use grocery store express lanes with any number of items. It has become common for a small number of checkout lanes of a larger store to be explicitly reserved as "express" lanes for the use of those with, for example, fewer than 10 items. This lets someone with a few items (handheld, in a basket, or possibly in a low-capacity cart) who will pass through quickly avoid being held up by people purchasing larger numbers of items who will take longer. In some cases, shoppers may try to argue the true meaning of "fewer than N items" in their favor, for example by arguing that "3 for the price of 2" promotions should only count as two items. The prevailing interpretation of "express" may be driven by the opinion of the surrounding shoppers who are also queuing for an express checkout lane and who may express displeasure at the taking of such liberties. Whether or not it is genuinely more beneficial to have the privilege of using the express lane with any number of items is arguable due to various complex factors, but the new holder of the diploma (who is, ironically, now possibly capable of defining the number of items more rigorously depending upon the academic subject just mastered) need not concern themselves with counting the number of items in their basket or ever needing to wait behind slow shoppers ever again (provided they always carry their diploma with them when they do their shopping). All graduates are entitled to delete one word of their choice from the Oxford English Dictionary. The Oxford English Dictionary (OED) is the principal historical dictionary of the English language, published by Oxford University Press. It is unclear what benefit deleting a word from the OED would provide, and doing so would prevent anyone else from looking up the word which would typically be seen as a disadvantage. As the OED is often used as an authority on which words are valid words in the English language (for example for word games such as Countdown ), perhaps the intention is that such "deleted" words are in fact removed from the English language itself. For example, Lake Superior State University has an annual tradition of publishing a list of "banished words" that they consider to be overused. A different interpretation is the right to delete literally one word from the text of the dictionary. While mostly useless, it could be used to alter some definitions, removing some details or even completely reversing the meaning by deleting "not". The OED contains around 228000 words . Given that US universities and colleges alone are expected to award around 1.9 million bachelor's degrees each year, this policy could lead to a rapid collapse of the OED. The university will mail you your working lightsaber within 6-8 weeks. Doctoral degree recipients wear various forms of dress or other items. For example, in Finland a doctoral sword is traditional. A lightsaber is a fictional weapon from the Star Wars universe which is used in a manner similar to a sword but which would likely be highly-regulated if it did exist in the real world due to its extreme power (in Star Wars, lightsabers are capable of cutting or burning through most materials and is only stopped by few things such as another lightsaber). Building a lightsaber is an important part of becoming a Jedi Knight, but Apprentices must find and assemble the parts themselves as part of their training and education; the only lightsabers they are given by the Temple are low-powered training lightsabers. "6-8 weeks" is a meme made popular on Stack Overflow meaning that the person making the estimate has no idea how long something is actually going to take or whether it's even going to happen at all. You can send mail without stamps. The franking privilege allows sending mail without stamps and is often granted to legislators conducting "official business." A group of legislators elected at the same time may sometimes be referred to as the "class of year " (such as "the congressional freshman class of 2019..." ), which may be seen as a parallel to a year of graduates from a university. You have earned the right to challenge the British royal family to trial by combat . If you defeat them all, the throne is yours. "Trial by combat" or "ritual combat" was a manner to settle disputes where two individuals would engage in a duel, with the winner being declared right. This type of ritual combat was depicted in the film Black Panther , with the winner of the combat declared the king of Wakanda. T'Challa, the Black Panther, was victorious in a fight against M'Baku, but was defeated by Erik Killmonger. The British royal family consists of the descendants and relatives of the current Queen, Queen Elizabeth II. However, the line of succession to the throne consists of potentially over 4,000 individuals; it is possible that a challenger would have to duel all of them, starting at the bottom of the line. The British royal family was also referenced in 2003: Presidential Succession . You may now ignore "Do Not Pet" warnings on airport security dogs. Security dogs are typically used in airports for the purpose of identifying explosives, drugs, or other prohibited items by smell. Although these dogs often work in private areas of the airport, they may sometimes be seen in public areas. Since dogs, in most western societies, are primarily kept as pets, it's a common reaction to want to interact playfully with the animals. This is prohibited for security dogs for multiple reasons. Petting the dog can distract it and otherwise prevent it from carrying out its job. In some cases the dogs may be aggressive to unsolicited contact. Criminals might deliberately attempt to distract or even poison security dogs to prevent detection. As such, the dogs typically carry a warning to not pet them and someone who ignores the warning will likely be detained for questioning. However, according to this comic, the holder of the diploma is supposedly permitted to pet such dogs with no consequences, despite the warnings. The title text builds on the items about lightsabers and the British royal family and advises that, because several of the younger royals also have diplomas, they have received their lightsaber already. Thus you should wait at least the 6-8 weeks until your lightsaber arrives to have a fair chance, given that lightsabers is a very lethal weapon. Also some of them may even be proficient with the weapon. Special mention goes to Catherine, Duchess of Cambridge , aka Kate Middleton, who was supposedly on the varsity lightsaber team at St Andrews . [An official document with a title at the top between two images of graduation hats on either side:] Congratulations, Class of 2019! Your diploma grants you many new powers and privileges. These include: You may now legally perform marriages and arrest people. If you have your diploma with you, you can use grocery store express lanes with any number of items. All graduates are entitled to delete one word of their choice from the Oxford English Dictionary. The university will mail you your working lightsaber within 6-8 weeks. You can send mail without stamps. You have earned the right to challenge the British royal family to trial by combat. If you defeat them all, the throne is yours. You may now ignore "Do Not Pet" warnings on airport security dogs.

Qualifiers

Qualifiers

https://www.xkcd.com/2158

https://www.explainxkcd.com/wiki/index.php/2158:_Qualifiers

[Cueball is standing next to White Hat.] Cueball: Ok, so, listen, the thing is, well, like, I'm just saying, and maybe it's just me, but, I mean, here's the thing, I could be way off here, but, look, I gotta say, [Caption below the panel:] When I forget what I was going to say, I just keep prefixing qualifiers until I think of something new.

This comic shows how qualifiers , which are usually used when the person speaking is concerned about offending their conversational partner, may also be used to delay saying something when a person is nervous or loses their train of thought momentarily. Again, this is a comic related to social interactions and especially displaying that Cueball/Randall has problems coping with simple social norms. In this comic, Cueball is talking with White Hat . Cueball has lost his original train of thought during a conversation, so he keeps using qualifiers until he comes up with something to say. Here he has used more than a dozen common qualifiers, including "OK", "so", "listen", "like", and "but". The title text says that after 20 minutes he says "hi", a reversal of expectations and a comedic play on how there was a huge buildup to something insignificant. He simply couldn't think of something new to say, and "hi" was the best he could come up with. White Hat presumably kept listening, although normal people would stop Cueball well before this. [ citation needed ] While this scenario has probably happened to many people some time in their life, it is highly unlikely that one would keep on for such an extensive amount of time. It is also highly unlikely that the listener would have such patience to keep listening to this endless stream of qualifiers, although it actually fits in White Hat's unusual mentality. [Cueball is standing next to White Hat.] Cueball: Ok, so, listen, the thing is, well, like, I'm just saying, and maybe it's just me, but, I mean, here's the thing, I could be way off here, but, look, I gotta say, [Caption below the panel:] When I forget what I was going to say, I just keep prefixing qualifiers until I think of something new.

Comments

Comments

https://www.xkcd.com/2159

https://www.explainxkcd.com/wiki/index.php/2159:_Comments

[Single panel comic depicting a screenshot of an Internet article, showing the article title, lines of wavy characters representing the article text, and several comments from readers of the article with their profile pictures.] Backlash: Internet users are outraged over news stories using a handful of random comments to support arbitrary narratives! [Close-up of Megan:] I can't believe how easy it is to create an impression of peer consensus. [Close-up of Hairy:] This dynamic is so easily manipulated and it freaks me out. xkcd.com/1019 [Full picture of Hairbun:] Everytime I share something and a friend responds "Haha, did you see the top comments..." it just reminds me how influential these things are in shaping the impressions of even relatively internet-savvy readers. [Close-up of Cueball on a black background:] NPR got rid of comments in 2016 when they realized they all came from a handful of visitors posting hundreds of times a month. [Full picture of two guys, Cueball and Hairy:] Eventually social norms will adapt to this stuff, but it needs to hurry up. [Close-up of Ponytail:] I have nine followers and created my account last month; how am I being quoted in this news article?? One of the comments to the article references an earlier xkcd comic 1019: First Post , which compares the cost of buying election ads on news sites versus paying college student to wait for news articles and submit the first comments to every news article.

This comic represents a news article that bemoans how sometimes lazy journalists will, instead of taking time to research the genuine public opinion on a certain issue, simply cherry pick comments as evidence to support their thesis. The irony is that the article is likely basing its own narrative of outrage among Internet users on random comments as well. For example, an anonymous Twitter account from Northern Ireland with 159 followers got used as an example in the first paragraph of a NY Times article about how U.S. Millennials think. The commenters create the narrative here, by pointing out how easy it is for commenters to push a point of view, and how little editorial control or fact checking there is in such a process. The final commenter reveals that the article itself is cherry picking from a handful of random comments to support its arbitrary narrative of internet outrage, proving the real joke. The link in one of the comments is to 1019: First Post , which also refers to manipulating comments to change public opinion of a topic. It specifically mentions "creating an impression of peer consensus", a line which is near-quoted in the first comment included in this comic. Another comment mentions a National Public Radio ("NPR") decision to remove comments from their website in 2016 because they represented only a tiny fraction of their readers. The statement released by NPR suggested they had decided to use social media channels to engage readers instead of using an on-site commenting system. The last of the comments may be from the user "Mary" who, in the NPR article, was explicitly cited to have said that the comments have been too violent. But it is unclear how this is possible given that this article claims to have been published after the comments having been turned off. This may also be a reference to 1303: Profile Info , as both of the characters would decrease the efficiency of the ad/article by being chosen as a quote. The title text refers to the ability to edit webpages using in-browser tools, like "Inspect Element." However, such changes are temporary and only on the machine used for viewing the web site; anyone else loading the page will not see them, and refreshing the page causes the changes to be replaced with the real content. This would mean that no other users would be able to see the comments, and news sources could not use them to influence public opinion. [Single panel comic depicting a screenshot of an Internet article, showing the article title, lines of wavy characters representing the article text, and several comments from readers of the article with their profile pictures.] Backlash: Internet users are outraged over news stories using a handful of random comments to support arbitrary narratives! [Close-up of Megan:] I can't believe how easy it is to create an impression of peer consensus. [Close-up of Hairy:] This dynamic is so easily manipulated and it freaks me out. xkcd.com/1019 [Full picture of Hairbun:] Everytime I share something and a friend responds "Haha, did you see the top comments..." it just reminds me how influential these things are in shaping the impressions of even relatively internet-savvy readers. [Close-up of Cueball on a black background:] NPR got rid of comments in 2016 when they realized they all came from a handful of visitors posting hundreds of times a month. [Full picture of two guys, Cueball and Hairy:] Eventually social norms will adapt to this stuff, but it needs to hurry up. [Close-up of Ponytail:] I have nine followers and created my account last month; how am I being quoted in this news article?? One of the comments to the article references an earlier xkcd comic 1019: First Post , which compares the cost of buying election ads on news sites versus paying college student to wait for news articles and submit the first comments to every news article.

Ken Burns Theory

Ken Burns Theory

https://www.xkcd.com/2160

https://www.explainxkcd.com/wiki/index.php/2160:_Ken_Burns_Theory

[Cueball is standing next to Megan.] Cueball: Lincoln was "President" in The Civil War (1990), the same office held by Johnson in The Vietnam War (2017). Cueball: And Baseball (1994) briefly showed 1960s "protesters." I think they were protesting Johnson's war! Cueball: It all fits! [Caption below the panel:] I have a fan theory that every Ken Burns miniseries exists within a single cohesive universe.

Some fiction writers and filmmakers set some (or all) of their works in a common, or shared, universe , meaning that characters in one work can conceivably meet characters in another work via conventional travel. Often, it's unmentioned or even outright denied that two distinct works take place in the same universe, but nevertheless fans may try to find a way to relate them to a common storyline (such as the examples of fan theories described in this Mental Floss article ). Ken Burns is an American filmmaker renowned for his historical documentaries; thus, all his documentary series are set in a common universe - namely, the real one - and usually the setting is a small part of that (real) universe: the United States in the last two centuries. The series mentioned are The joke here is that Cueball is trying to find the common features between Ken Burns' series to set them in a common universe, as a fiction fan would do, "discovering" similarities between series that are simply facts in American history. For example, several series have an office named "President", which Cueball "guesses" to be the same for Lincoln and Johnson , and which obviously is just the President of the United States . Cueball has also drawn inferences from facts established in one series to draw conclusions about another, when he ( correctly ) concludes that the 1960s protesters depicted in Baseball were protesting "Johnson's war" as depicted in The Vietnam War . The title text continues the joke by saying these stories are set in the "KBCU", an acronym which stands for "Ken Burns Cinematic Universe" similar to the popular Marvel Cinematic Universe (MCU). Doris Kearns Goodwin , mentioned in the title text, is a famous historian who has written biographies of several U.S. Presidents. She is also a fan of baseball's Boston Red Sox and a sportswriter who appeared in the Baseball miniseries. Cueball states that having a character that had written biographies of both presidents, while also a sportswriter was "unrealistic". It's not uncommon for writers trying to fit different stories into a single 'universe' to cause a single character to become important in both, even though it makes little narrative sense. This can be denounced as "trying too hard" to fit the stories together. Finding that certain aspects of reality seems unrealistic is quite common . This is because our judgment of realism is based on our own experiences and our (often flawed) perception of probabilities. Because the complexities of the world generally exceed any person's experience, and because it's natural for highly unlikely events to occur sometimes, real events can seem implausible. In this case, people tend to think of sports journalism and political biography as being very different fields. The odds that one person would do work in both fields important enough to be relevant to all three documentaries under discussion feels unlikely. As a result, we (or rather, Cueball) deem it as unrealistic, even though it actually happened. [Cueball is standing next to Megan.] Cueball: Lincoln was "President" in The Civil War (1990), the same office held by Johnson in The Vietnam War (2017). Cueball: And Baseball (1994) briefly showed 1960s "protesters." I think they were protesting Johnson's war! Cueball: It all fits! [Caption below the panel:] I have a fan theory that every Ken Burns miniseries exists within a single cohesive universe.

An Apple a Day

An Apple a Day

https://www.xkcd.com/2161

https://www.explainxkcd.com/wiki/index.php/2161:_An_Apple_a_Day

[Megan is facing straight out of a slim panel as she stands behind a lectern addressing the reader.] Megan: An apple a day keeps the doctor away. Megan: Or at least, it used to. [The comic zooms out revealing that Megan and the lectern are standing on a podium. Megan is pointing behind her, with a stick, to at a poster prominently featuring Doctor Ponytail with three apples over her head.] Megan: Over time, some doctors have developed a resistance to apples. Keeping them away takes two or three apples instead of one. Megan: And there are worrying signs that a few doctors may have become completely immune. [The comic zooms in again on Megan behind the lectern.] Megan: So we must stockpile our finest apples in reserve, using them to fend off only the very worst doctors. Megan: Honeycrisps still work on most of them, but we don't know for how long.

" An apple a day keeps the doctor away " is a common English proverb and rhyme . The suggestion is that eating one apple daily will keep you healthy, and therefore reduce your necessity to go to the doctor or, more literally, to have the doctor come to you as was likely the case when this proverb was first used. Megan is giving a talk, starting with the common proverb, before continuing with "At least, it used to." In a normal scenario, this might have been to imply that eating apples is no longer enough to stay healthy. However, in this comic, this expression is reinterpreted to mean that an apple used to repel a doctor. It also suggests that keeping doctors away is of great importance, presumably because doctors in this scenario are undesirable. The method of action of apples is not specified; they could act as repellents, analogous to insect repellent , or possibly as lethal agents, as antibiotics are to bacteria , or fungicides are to fungi . Megan continues with her reinterpretation, mentioning that doctors have become resistant to apples so two or even three may be needed. As control agents become more widely used, organisms which are less sensitive to the control may become more common, as is happening with mosquitoes becoming insensitive to repellents , or antimicrobial resistance , and pesticide resistance . Such resistant organisms may require higher doses, or use of multiple control agents. In the worst cases, doctors have become completely immune to apples (i.e., superbugs ). A poster behind Megan shows Doctor Ponytail with three apples above her. Megan advocates using the 'finest' apples only in these cases (a reference to multidrug-resistant pathogens , where some antibiotics are only used as a last-resort to reduce the development of resistance to them). This comic is a clear reference to the overuse of antibiotics in modern society, leading to an increase in antimicrobial resistance ("Superbugs"), which has seen increasing awareness in the last few years. The World Health Organization had the first Antibiotic Awareness Week in 2015, where a talk similar to the one in the comic would seem appropriate. Similar problems occur in growing plants, where various pests (whether insect, fungi, microbes, or plants) adapt to control measures, making control less effective. In the title text, this is taken further: "Gran-negative" is a pun on Gram-negative , a category of bacteria. A well-known technique called Gram staining distinguishes two classes of bacteria (Gram positive versus Gram negative) on the basis of properties of their cell walls. In this case, Granny Smith apples are supposedly effective against Gran-positive doctors (since the name begins with "Gran"), making them ineffective against new Gran-negative doctors. Honeycrisp and Granny Smith are two different cultivars of apples. Granny Smith apples are a refreshingly tart green apple, which have mixed reviews among apple eaters. Conversely, Honeycrisp are a very sweet apple, considered by some to be "an ideal apple for eating raw", and is the state fruit of Minnesota. [Megan is facing straight out of a slim panel as she stands behind a lectern addressing the reader.] Megan: An apple a day keeps the doctor away. Megan: Or at least, it used to. [The comic zooms out revealing that Megan and the lectern are standing on a podium. Megan is pointing behind her, with a stick, to at a poster prominently featuring Doctor Ponytail with three apples over her head.] Megan: Over time, some doctors have developed a resistance to apples. Keeping them away takes two or three apples instead of one. Megan: And there are worrying signs that a few doctors may have become completely immune. [The comic zooms in again on Megan behind the lectern.] Megan: So we must stockpile our finest apples in reserve, using them to fend off only the very worst doctors. Megan: Honeycrisps still work on most of them, but we don't know for how long.

Literary Opinions

Literary Opinions

https://www.xkcd.com/2162

https://www.explainxkcd.com/wiki/index.php/2162:_Literary_Opinions

[Megan is walking with a finger raised toward Cueball, who is seated in a chair with a book.] Megan: Literary opinion: Megan: I firmly believe that William S. Burroughs, Hunter S. Thompson, Chuck Palahniuk, and David Foster Wallace are different names for the same person. Cueball: ...I see. [Megan puts down her hand.] Megan: Fear and Loathing in Las Vegas and Fight Club ? Same book with different covers, I bet. Cueball: I have both. Want to open them and check? Megan: I do not. [Cueball turns back to his book.] Megan: Moving on: my next opinion-- Cueball: You should start a book club for discussing the books you refuse to read. Megan: --is that E.B. White and T.H. White are the same person. Cueball: Ok, that I believe.

Megan is telling Cueball about some of her literary opinions: She believes that William S. Burroughs , Hunter S. Thompson , Chuck Palahniuk , and David Foster Wallace are different names for the same person. Many authors write under pen names for some of their works, or even several different pen names. Sometimes people come to believe that different people are actually a same person, which is known as the Fregoli delusion ; the person is usually believed to change appearance. She then says that Fear and Loathing in Las Vegas (by Thompson) and Fight Club (by Palahniuk) are the same book with different covers, probably because the title and promotional images for both hint at fighting taking place in a big city (i.e., she is literally judging the books by their covers ), when in reality the books are vastly different. Books sometimes have different covers and titles in different regions . That said, Fight Club does contain a plot twist where two "different" things turn out to be the same thing (see 109: Spoiler Alert for more information). Cueball's attempt at a reality check (proposing to actually open the books she is talking about) is met with disinterest. It becomes clear that Megan just wants to share her weird beliefs and does not care if they can be proven false - a theme that previously appeared in 1717: Pyramid Honey . As a last resort, Cueball humorously proposes she should start a book club to discuss the books she has not read. This may be to congregate all people who criticize books without reading them, or in hopes that it will be attended by people who have read the book and can prove to Megan her opinions are baseless. Megan finishes telling him her opinion anyway, which is that E.B. White and T.H. White are the same person. This is apparently an opinion that Cueball can agree with, as he tells her that he believes it. This is likely a joke that the two names are hard to distinguish due to the having the same last name with only initials instead of a first name. In reality, the books they authored are very different, with E.B. White writing children's books ( Charlotte's Web , Stuart Little , etc.) and T.H. White writing adult books about King Arthur ( The Sword in the Stone and its sequels), although his works were adapted into a Disney movie so they could, to some degree, be considered children's books. The title text continues with this, with Megan saying that she can distinguish between John Steinbeck and John Updike , or between Gore Vidal and Vidal Sassoon , but she can't do so simultaneously. Again this is likely due to the similarities in their names. However, John Steinbeck and John Updike are also easy to confuse because they are both giants of 20th century American literature, whereas Gore Vidal has almost nothing in common with Vidal Sassoon (see chart below). Additionally, the mention of simultaneity could be a nod to the Heisenberg uncertainty principle , which states that there is a trade-off in precision when simultaneously measuring position and momentum. It could also be a nod to how the brain cannot simultaneously interpret two different things at once, similar to looking at the Rabbit-duck illusion ; at any moment, one can only see a duck or a rabbit in the image, but not both at exactly the same time. [Megan is walking with a finger raised toward Cueball, who is seated in a chair with a book.] Megan: Literary opinion: Megan: I firmly believe that William S. Burroughs, Hunter S. Thompson, Chuck Palahniuk, and David Foster Wallace are different names for the same person. Cueball: ...I see. [Megan puts down her hand.] Megan: Fear and Loathing in Las Vegas and Fight Club ? Same book with different covers, I bet. Cueball: I have both. Want to open them and check? Megan: I do not. [Cueball turns back to his book.] Megan: Moving on: my next opinion-- Cueball: You should start a book club for discussing the books you refuse to read. Megan: --is that E.B. White and T.H. White are the same person. Cueball: Ok, that I believe.

Chernobyl

Chernobyl

https://www.xkcd.com/2163

https://www.explainxkcd.com/wiki/index.php/2163:_Chernobyl

[Ponytail and White Hat facing each other.] Ponytail: Did you like Chernobyl ? White Hat: Yeah! White Hat: But I still don't understand the meltdown. Can you explain it...simpler? [Zoom in to closeup of Ponytail holding one hand out with palm up, with White Hat off-panel to the right.] Ponytail: Well, the graphite– White Hat (off-panel): Already too complicated. Ponytail: Uh...they put the reactor in an unstable– White Hat (off-panel): Nope, sorry. [Zoom back out to full view of Ponytail and White Hat, with Ponytail holding hand to her chin.] Ponytail: Hmm, ok. Ponytail: Long ago, humans banged rocks together to make fire. White Hat: Ok... [Full view of Ponytail and White Hat, who has both hands held straight out to both sides.] Ponytail: 30 years ago, we banged some rocks together too hard. White Hat: Oh no! Ponytail: Yeah, we messed up real bad.

Ponytail and White Hat discuss the HBO miniseries Chernobyl which depicts the 1986 Chernobyl nuclear plant meltdown and the fact that none of them needs to state that they refer to the series, not to the power plant shows the impact the miniseries had on language, at least at this time. White Hat asks Ponytail for an explanation of how the meltdown occurred, but his understanding of science is so limited that he finds even the first part of the first sentence of Ponytail's explanation too complicated to understand. Ponytail starts explaining the role of graphite in the reactor's core as the neutron moderator, but White Hat immediately interrupts her, as if he doesn't understand the word graphite . Ponytail tries starting the explanation from another angle, stating that the nuclear reactor was inadvertently put in an unstable state moments before the disaster, but White Hat interrupts again. Realizing that White Hat does not understand what a reactor is, even though the reactor is the entire subject of the reactor meltdown, Ponytail resolves to use plain words every person should know, and to employ a metaphor. She compares the purpose of a nuclear reactor as a heat-generating device to primitive humans' way of heating by starting a fire. She goes on describing how a fire can be started by banging rocks (pieces of flint) to create sparks, which in turn would light a fire. Seeing that White Hat understands this simple activity, she compares starting a runaway nuclear fission reaction to banging rocks too hard, presumably splitting or crushing them and injuring the wielder. Nuclear reactions are often simplistically described and illustratively pictured as forcibly colliding colored balls representing various nuclear particles or nuclei, resulting in creating other balls, joining some into bigger ones, or splitting some into smaller ones. Fission reaction, in particular, involves a neutron causing a heavy nucleus to split into smaller parts, including more neutrons, that may cause further splits, and so on. To facilitate nuclear reactions, particles need to carry great amounts of energy as compared to their tiny sizes and masses. This may evoke a mental image of hitting rocks too hard so they split. Alternatively, banging some rocks too hard may suggest to a person not entirely familiar with the process of starting fire by the use of flint, that instead of providing small sparks and lighting a controlled fire by striking flint moderately, overdoing it may create a huge uncontrolled fire – and it is what has happened in Chernobyl, a huge fire caused by reactor overheat and subsequent explosion and core meltdown, with additional harmful effect of spreading radioactive particles over large area by the fire's fumes. The title text explains the cause of the accident using an analogy with the volume of an audio system. To sustain a controlled nuclear fission chain reaction, various mechanisms are involved in controlling the level of neutrons produced and consumed by the nuclear fuel. Due to various design flaws and operation errors leading up to the Chernobyl disaster, the reactor core was producing less heat than desired by the reactor operators, who were preparing to conduct a simulated power outage experiment. To increase heat production, the operators pulled out almost all available control rods without diagnosing the cause first, akin to turning the volume knob to maximum on a sound system while there was no signal on input because of some condition independent from volume setting and not readily recognized by the operator. Then the commencement of the experiment, which reduced the coolant water supply, further enhanced the positive feedback loop of the neutron production. Seeing a rapid rise in the power output, the operators began an emergency shutdown. A critical design flaw of the reactor caused the neutron production to increase temporarily in the reactor once the emergency shutdown started in this condition, which resulted in a runaway reaction caused by the multiple positive feedback loops taking place, ending up with dramatic increase of generated heat, coolant water rapidly boiling, steam explosion breaching the pressure vessel and breaking the coolant lines, and melting of the reactor core. The extreme heat of the melted core caused remaining water to split, and the accumulated hydrogen finally caused a chemical explosion that finally destroyed the reactor. Per the title text, this is analogous to a input signal returning to normal on a sound system that has the volume turned all the way up, creating a "deafening blast of sound." [Ponytail and White Hat facing each other.] Ponytail: Did you like Chernobyl ? White Hat: Yeah! White Hat: But I still don't understand the meltdown. Can you explain it...simpler? [Zoom in to closeup of Ponytail holding one hand out with palm up, with White Hat off-panel to the right.] Ponytail: Well, the graphite– White Hat (off-panel): Already too complicated. Ponytail: Uh...they put the reactor in an unstable– White Hat (off-panel): Nope, sorry. [Zoom back out to full view of Ponytail and White Hat, with Ponytail holding hand to her chin.] Ponytail: Hmm, ok. Ponytail: Long ago, humans banged rocks together to make fire. White Hat: Ok... [Full view of Ponytail and White Hat, who has both hands held straight out to both sides.] Ponytail: 30 years ago, we banged some rocks together too hard. White Hat: Oh no! Ponytail: Yeah, we messed up real bad.

Glacier

Glacier

https://www.xkcd.com/2164

https://www.explainxkcd.com/wiki/index.php/2164:_Glacier

[Knit Cap and Beret Guy are standing to the left of a glacier.] Knit cap person: Glaciers are so neat. You can't see it, but this ice is slowly advancing. [Zoom in on Beret Guy, who has his hand to his mouth, thinking.] [Zoomed in, Beret Guy exits to the left of the panel.] [Beret Guy enters the panel from the left, carrying two fencing sabres.] [Beret Guy uses a blow dryer to attach one of the sabres to the glacier.] Whirrrr [Beret Guy is holding the blow dryer and looks at the sabre that is attached to the glacier.] [Beret Guy stands in a defensive position with sabre in hand, ready to defend against the "advancing" glacier.] The author of The Sword in the Stone , T. H. White, was mentioned two comics ago in 2162: Literary Opinions .

A glacier is a wall of dense ice. Though glaciers tend to appear still, they are actually slowly moving, typically by around 10 inches (25 cm)/day. Beret Guy and Knit Cap are facing the forward edge of a glacier. Knit Cap wearing a knit cap remarks that glaciers are amazing, mentioning the fact that though we can't see it, the ice is slowly advancing. After considering this, Beret Guy leaves, then returns with two sabres and a hairdryer. He uses the hairdryer to melt a part of the glacier, which he then attaches a sabre to. This use of the hair dryer may be another example of Beret Guy's strange powers , since the dryer does not appear to be plugged into anything. After he attaches the sabre to the glacier, he then takes a defensive position. "Advancing" is a basic forward movement in fencing, and Beret Guy appears to feel it is unfair for the glacier not to have a weapon. The title text refers to The Sword in the Stone , a famous sword in the legends of King Arthur, and Norway , a country known for its glaciers. In the original legend, the sword is set into solid rock, and enchanted so that only the true King could draw it out. The legend has been alluded to in a previous comic . The title text might be making any of several implications about a Norwegian adaptation, including: [Knit Cap and Beret Guy are standing to the left of a glacier.] Knit cap person: Glaciers are so neat. You can't see it, but this ice is slowly advancing. [Zoom in on Beret Guy, who has his hand to his mouth, thinking.] [Zoomed in, Beret Guy exits to the left of the panel.] [Beret Guy enters the panel from the left, carrying two fencing sabres.] [Beret Guy uses a blow dryer to attach one of the sabres to the glacier.] Whirrrr [Beret Guy is holding the blow dryer and looks at the sabre that is attached to the glacier.] [Beret Guy stands in a defensive position with sabre in hand, ready to defend against the "advancing" glacier.] The author of The Sword in the Stone , T. H. White, was mentioned two comics ago in 2162: Literary Opinions .

Millennials

Millennials

https://www.xkcd.com/2165

https://www.explainxkcd.com/wiki/index.php/2165:_Millennials

[White Hat and Cueball facing each other.] White Hat: I'm just saying– White Hat: All these millennials will be in for a shock when they have to grow up and enter the real world. [Zoom in on Cueball's head and upper body.] Cueball: Except... Cueball: "Millennials" started reaching adulthood about 20 years ago. [Zoom out to full view of White Hat and Cueball facing each other in a frameless panel.] Cueball: Which means that some millennials can't respond to your criticism because they're busy taking their kids to check out colleges. [White Hat and Cueball facing each other.] White Hat: But ...no, millennials are college kids! Cueball: Maybe they're not the ones failing to grow and change over time here.

According to the definitive chronology of generations , millennials are born between 1982 and 1999. Those born in 1982 reached adulthood (18 years) in 2000. As of writing of this comic (mid 2019), this is about 20 years ago. When the term became widespread around 2012, replacing the previous term "Generation Y", the average millennial was 21 years old, so the image was popularized of millennials as "college kids". The parlance of the word in everyday usage seems to be expanding so that it now includes not just those that were originally Gen Y, but also some younger Gen Xers, as well as current teens and college kids (many of whom are actually Gen Z/Generation 💅). In this strip, White Hat expresses a sentiment of prejudice against millennials, claiming they aren’t prepared for “the real world.” This is a sentiment that sometimes can be found among those of older generations. However, Cueball refutes this by saying that many millennials have been adults for almost 20 years, and those that had kids early on are taking them to college. This is due to another common misunderstanding, where the definition of “millennial” has changed so much, and expanded so often, that nobody really knows what it means anymore. White Hat refuses to accept this, saying millennials are the college kids, to which Cueball says that maybe White Hat is the one not growing up and accepting that millennials are, in fact, adults. The title text builds on this, complaining that Randall has been having these discussions for over a decade. The title text begins with the word "ironically," for what appears to be an entirely sincere complaint, possibly in reference to Alanis Morissette's pop song " Ironic ," which is often said to be a generation-defining hit among millennials, and which was widely criticized for misusing the word. Alternatively, Randall may simply be using "ironically" to mean "strangely". White Hat has been similarly confused by what ages different generations are in 973: MTV Generation . [White Hat and Cueball facing each other.] White Hat: I'm just saying– White Hat: All these millennials will be in for a shock when they have to grow up and enter the real world. [Zoom in on Cueball's head and upper body.] Cueball: Except... Cueball: "Millennials" started reaching adulthood about 20 years ago. [Zoom out to full view of White Hat and Cueball facing each other in a frameless panel.] Cueball: Which means that some millennials can't respond to your criticism because they're busy taking their kids to check out colleges. [White Hat and Cueball facing each other.] White Hat: But ...no, millennials are college kids! Cueball: Maybe they're not the ones failing to grow and change over time here.

Stack

Stack

https://www.xkcd.com/2166

https://www.explainxkcd.com/wiki/index.php/2166:_Stack

[Single-panel with a label at the top and 8 box layers stacked vertically, with in and out arrows at the top representing normal data flow and an arrow out of each box to the left or right representing exploit data flow] The Modern Tech Stack Compromised by a customer (arrow to the right) Compromised by a former employee (arrow to the left) Compromised by a current employee (arrow to the right) Compromised by bitcoin miners (arrow to the right) Compromised by unknown hackers (arrow to the left) Compromised by our own government (arrow to the right) Compromised by a foreign government (arrow to the left) Massive undiscovered hardware vulnerability (arrow to the right) Comic 1636: XKCD Stack also has a hypothetical technology stack, with farcical layers.

In software engineering, a tech stack is the set of technology platforms and tools that a company or app uses. A common tech stack is LAMP , composed of a Linux operating system , an Apache Web server , a MySQL database , and the PHP programming language. In this instance, all of the layers represent systems which have been subverted or compromised ("hacked") by various entities, instead of various software technologies. The stack resembles an OSI network architecture, with an eighth layer added representing the user itself. Compromised by a customer: The user experience, above the OSI layers. Compromised by users doing something wrong or ill-advised. Compromised by a former employee: In the OSI model, this would be the application layer. The application may include a hidden spyware in its codebase. Recent examples of compromise: Desjardins Group Compromised by a current employee: This is the presentation layer. See above. Probably, that was compromised by a mistake of a current unexperienced employee. Compromised by Bitcoin miners: This is the session layer, where SSL historically resided. Cryptographic exploits may cause compromise of whole communication. Examples of compromise: Dozens of bitcoin mining viruses. Compromised by unknown hackers: This is the transport layer. IP and port spoofing is a possible compromise. Compromised by our own government: This is the network layer. It refers to communication intercepts by governments. Examples of compromise: Cisco (for US citizens) Compromised by a foreign government: This is the data link layer. This layer may be compromised by malrouting packets. Examples of compromise: Huawei (for non-Chinese citizens) Massive undiscovered hardware vulnerability: This is the physical layer. An undiscovered hardware vulnerability may cause compromises further up in the stack. Examples of compromises: Intel Management Engine , Meltdown , Row hammer In the title text, Randall expresses sympathy for a situation where someone spends a significant length of time on something that then becomes completely unnecessary. In this case, it's the state-sponsored hackers who develop an exploit of some hardware component, which then becomes completely useless because the target database on that hardware is totally open anyway to anyone with a web browser (which is essentially everyone). While he's not suggesting he agrees with their hacking, he has some sympathy for their wasted effort. [Single-panel with a label at the top and 8 box layers stacked vertically, with in and out arrows at the top representing normal data flow and an arrow out of each box to the left or right representing exploit data flow] The Modern Tech Stack Compromised by a customer (arrow to the right) Compromised by a former employee (arrow to the left) Compromised by a current employee (arrow to the right) Compromised by bitcoin miners (arrow to the right) Compromised by unknown hackers (arrow to the left) Compromised by our own government (arrow to the right) Compromised by a foreign government (arrow to the left) Massive undiscovered hardware vulnerability (arrow to the right) Comic 1636: XKCD Stack also has a hypothetical technology stack, with farcical layers.

Motivated Reasoning Olympics

Motivated Reasoning Olympics

https://www.xkcd.com/2167

https://www.explainxkcd.com/wiki/index.php/2167:_Motivated_Reasoning_Olympics

[Cueball is holding a trophy with a 2 engraved on it, showing it off to Ponytail] Cueball: Check it out, I won first place at the Motivated Reasoning Olympics! Ponytail: That trophy says "second." Cueball: Well, the guy who won was caught cheating in an earlier round, so the board is almost certain to strip him of his win once they review the...

Cueball is talking to Ponytail about the trophy he won for winning the “Motivated Reasoning Olympics” (hence the title). Ponytail rightly points out that the trophy says he only got second place. Cueball then displays the " motivated reasoning " skills that won him the trophy, by claiming that the athlete who beat him cheated in an earlier round and that the judges were “certain” to disqualify him after reviewing. Here, the cognitive dissonance that should result from believing that he won first place but having a trophy that says second place is reduced by Cueball's motivated reasoning. He has developed a narrative that explains away the inconsistent fact of the label on the trophy, and thus, convinces himself that there couldn't have been any shortcoming in his own performance. These are all characteristics of motivated reasoning. The title text is a continuation where Cueball suggests the judges are biased in favor of the original winner, whom they approve of. He further states that this is evidence of corruption and is the reason why his league split off from the official state-sponsored league just prior to the Motivated Reasoning Olympics. Of course, motivated reasoning is an emotion-biased decision-making phenomenon, by definition, so he should expect the judging to be biased. [Cueball is holding a trophy with a 2 engraved on it, showing it off to Ponytail] Cueball: Check it out, I won first place at the Motivated Reasoning Olympics! Ponytail: That trophy says "second." Cueball: Well, the guy who won was caught cheating in an earlier round, so the board is almost certain to strip him of his win once they review the...

Reading in the Original

Reading in the Original

https://www.xkcd.com/2168

https://www.explainxkcd.com/wiki/index.php/2168:_Reading_in_the_Original

[Cueball is addressing Megan. He is holding a hand with a thumb up out toward her. Megan is spreading her arms out as she replies.] Cueball: It's in the "Languages" box in the lower left. It took a while to learn, but I find I get so much more out of it by reading it as it was intended . Megan: That's not how that works! [Caption below the panel:] People get mad when I tell them I only read Wikipedia in the original Greek.

Many academics and aficionados argue that studying texts in the original language is more valuable than reading translations. The argument is that translations are rarely able to fully capture all of the nuances, linguistic subtleties and intent of the original author, and may even alter the meaning in some way due to the translator's interpretation and word choices. The drawback to this is that it requires the reader to be sufficiently fluent in whatever language the text is written. Critically, a reader of the original source also needs to understand the cultural and historical context of the original work, something a professional translator might deal with much better. This can even happen when working with archaic texts in the same language, as certain references and phrases may have had a significance which was lost over time. Cueball's commenting that he read works "in the original Greek" implies a high-level of literary scholarship, as this phrase is associated with scholars studying ancient Greek texts, which form a significant part of the foundational works of Western literature. A similar thing happens with dubbed movies or TV series/anime, with many people remarking that they instead prefer to watch the original version (sometimes with subtitles), instead of the dubbed version. The joke in this comic is that Cueball has apparently taken the time to learn Greek in order to read the Greek-language Wikipedia in that language, believing it to be the "original" one. Wikipedia was originally launched as a single English-language edition encyclopedia, but Cueball apparently treats it as though it was originally written in Greek. (An Ancient Greek Wikipedia test project also exists, but is not nearly as large as the modern Greek one and isn't available through the languages box.) Wikipedia has editions in about 300 languages; the 'languages' box that Cueball mentions does link to the corresponding page in other languages when they are available, but such pages are not usually translations of each other, having been written separately. Cueball's dedication to appearing to be a committed scholar is therefore contrasted with the ignorance of not understanding that Greek is not the original language of every text. Megan, recognizing that Wikipedia articles were not originally in Greek, exclaims that "That's not how that works!" The movie Star Trek VI: The Undiscovered Country has a joke concerning someone speaking of a foreign "original" language of something that actually was originally written in English: Chancellor Gorkon says, "You have not experienced Shakespeare until you've read it in the original Klingon ." (In reality, Shakespeare lived in England, and wrote in English, not Klingon.) [ citation needed ] The title text combines two jokes. First, the reference to pages being "much shorter" is because the English language Wikipedia has the most editors and is the most developed; outside of areas of intense interest to Greeks, most pages would be more complete on the English Wikipedia, which would normally be a sign to Cueball that his interpretation that Greek was the original text is incorrect. Second, the way he explains away this contradiction is an etymology joke, since "Wikipedia" was coined from two parts, " wiki ", from Hawaiian, and " pedia ", from Greek. However, words having roots in different languages is common and does not signify any link between the separate languages; for example, while the word "Wikipedia" does have etymological roots in Hawaiian and Greek, it is not true that the site was originally composed of texts written in Hawaiian and Greek. In Hawaiian, wiki means quick. In Greek, the suffix pedia is related to learning, which makes Wikipedia mean "quick learning" when combining these two languages. [Cueball is addressing Megan. He is holding a hand with a thumb up out toward her. Megan is spreading her arms out as she replies.] Cueball: It's in the "Languages" box in the lower left. It took a while to learn, but I find I get so much more out of it by reading it as it was intended . Megan: That's not how that works! [Caption below the panel:] People get mad when I tell them I only read Wikipedia in the original Greek.

Predictive Models

Predictive Models

https://www.xkcd.com/2169

https://www.explainxkcd.com/wiki/index.php/2169:_Predictive_Models

[Cueball is sitting in an office chair at a desk typing on a laptop. Above him is the text he writes along with what the predictive text tool suggests, the latter in grey text. The TAB at the end is in a small frame.] Cueball typing: Long live the revolution. Our next meeting will be at | the docks at midnight on June 28 [tab] Cueball: Aha, found them! [Caption below the panel:] When you train predictive models on input from your users, it can leak information in unexpected ways.

Predictive text is a feature on many systems where as you type the system automatically suggests likely words or phrases to follow what you have written to that point. For instance, if you type "I'm heading" the system may suggest "home" or "back" as likely words to follow. Predictive systems usually use prior input to generate their predictions, so if you frequently type "Totally amazing!" the system will suggest "amazing!" every time you type "totally" even if you actually want to type "totally true" sometimes. In the comic, Cueball is using predictive text to uncover a plot against his organization/government, but instead of using only his personal input, the system is using input from all users. By typing in an obscure phrase related to revolution and a meeting, he gets the predictive text algorithm to display where and when the next supposedly secret meeting will be held based on other users input. This works because it is unlikely that anyone else other than revolutionaries would be typing this phrase, thus the only data the algorithm has to predict from is the actual message from the revolutionaries on their next meeting. The caption of the comic is pointing out that systems which use prior input for predictive purposes in this way can end up leaking information that might otherwise be considered private. (However, this method may produce outdated information. On June 29, 2019, typing in Google "Long live the revolution. Our next meeting will be at" gave the predicted completion "long live the revolution. our next meeting will be at comic con 2018", which would not be useful information to anyone looking for revolutionaries, because Comic-Con 2018 was already over.) The title text shows the revolutionaries using the same technique. By typing in "We will arrest the revolution members" they are hoping that the algorithm will suggest the time and date of their planned arrest, since no one other than the authorities would be typing in that phrase. Pressing the key [tab] to autocomplete that text produces "WE WILL ARREST THE REVOLUTION MEMBERS [AT THE JULY 28TH MEETING]", and the revolutionaries then say "Cancel the meeting! Our cover is blown." The revolutionaries have apparently made the serious mistake of holding secret meetings on regular, predictable dates (such as the 28th day of each month, the last date guaranteed to exist in any month of the Gregorian Calendar), and the authorities have successfully figured this out, either through the predictive-text attack or by other means. Both examples assume that the revolutionaries and the authorities would be talking about very secret information in the clear on a network accessible to their adversaries. In the real world people engaged in sensitive activities would communicate via code, encryption, or both, or would do so through what they believe to be secure channels. There is still the danger of secret information leaking via non-secret channels, however. Side-channel attacks use information gained from the implementation of a system to deduce supposedly protected information. A famous example occurred in World War II. The Germans kept tank production figures a secret, but they gave items like engine blocks sequential serial numbers. The Allies wanted to know exact tank production figures, so they solved the German tank problem by using statistical methods to analyze the distribution of these numbers on captured vehicles. They were able to predict tank production figures extremely accurately, to the point they predicted 270 tanks in a month when 276 were actually built. Thus the secret information on tank production leaked. Some systems require frequent password change, in an effort to limit danger from a password being discovered. However, people respond by choosing passwords in patterns, so it is easy to predict what subsequent passwords will be, given old ones, thus defeating the purpose of requiring frequent changes. Passwords Evolved: Authentication Guidance for the Modern Era Although the comic title is "Predictive Models", the term Predictive modelling usually refers to computer programs that try to predict outcomes from data aggregation, such as reviewing health records to identify people most at risk from certain diseases based on weight, prior injuries, etc., before testing directly for the diseases themselves. This is similar to but not precisely like the example in the comic, since predictive text is using direct input to predict further input, while predictive modelling is using related input (such as make and model of a car along with driver acceleration patterns) to predict a different output (such as likelihood of a crash). Both predictive text and predictive modelling could leak information as the comic suggests, however. Predictive text and the possibility to leak unintended information has been parodied on xkcd before in 1068: Swiftkey . [Cueball is sitting in an office chair at a desk typing on a laptop. Above him is the text he writes along with what the predictive text tool suggests, the latter in grey text. The TAB at the end is in a small frame.] Cueball typing: Long live the revolution. Our next meeting will be at | the docks at midnight on June 28 [tab] Cueball: Aha, found them! [Caption below the panel:] When you train predictive models on input from your users, it can leak information in unexpected ways.

Coordinate Precision

Coordinate Precision

https://www.xkcd.com/2170

https://www.explainxkcd.com/wiki/index.php/2170:_Coordinate_Precision

[Single panel containing a table with two columns for "Lat/Lon Precision" and "Meaning" and a caption above the table.] Caption: What The Number of Digits in Your Coordinates Means [Row 1] Lat/Lon: 28°N, 80°W Meaning: You're probably doing something space-related [Row 2] Lat/Lon: 28.5°N, 80.6°W Meaning: You're pointing out a specific city [Row 3] Lat/Lon: 28.52°N, 80.68°W Meaning: You're pointing out a neighborhood [Row 4] Lat/Lon: 28.523°N, 80.683°W Meaning: You're pointing out a specific suburban cul-de-sac [Row 5] Lat/Lon: 28.5234°N, 80.6830°W Meaning: You're pointing to a particular corner of a house [Row 6] Lat/Lon: 28.52345°N, 80.68309°W Meaning: You're pointing to a specific person in a room, but since you didn't include datum information, we can't tell who [Row 7] Lat/Lon: 28.5234571°N, 80.6830941°W Meaning: You're pointing to Waldo on a page [Row 8] Lat/Lon: 28.523457182°N, 80.683094159°W Meaning: "Hey, check out this specific sand grain!" [Row 9] Lat/Lon: 28.523457182818284°N, 80.683094159265358°W Meaning: Either you're handing out raw floating point variables, or you've built a database to track individual atoms. In either case, please stop.

This cartoon gives increasingly precise latitude and longitude coordinates for a location on the planet Earth. However, a given pair of coordinates covers a trapezoidal region of land, and thus leaves some ambiguity; therefore, greater precision requires an increasing count of decimal places in your coordinates. This comic uses this information to roughly identify how precise a given coordinate length might be. The increasing precision of coordinates in this cartoon are similar to the increasing magnification in the short documentary "Powers of 10," which can be found here . (Also parodied in #271:Powers of One ). The coordinates at 28.52345°N, 80.68309°W (in decimal degrees form; in geographic coordinate system form using degrees, minutes, and seconds, 28° 31′ 24.4″N, 80° 40′ 59.1″W) are pointing to the Rocket Garden at the Kennedy Space Center in Merritt Island, Florida —specifically, the tip of the Delta rocket. The sixth entry in the table, with seven digits of precision, includes the caveat that, while your coordinates map to areas small enough on the Earth's surface to indicate pointing to a specific person in a room, "since you didn't include datum information, we can't tell who". This is a reference to the geodetic datum or geodetic system — different ways of dealing with the fact that the Earth is neither perfectly spherical nor perfectly an oblong ellipsoid. The various datums do not make much difference at six digits of precision, but at seven, there is enough skew depending on which system is in use that the person in a room you are referring to with the coordinates is ambiguous. It is unstated, but the remaining lines in the table with ever-greater precision suffer from this same issue and are equally ambiguous without datum information. The final entry, with seventeen digits of precision, suggests that either the user is referring to individual atoms in the much-larger-scale whole-Earth coordinate system, or (perhaps more likely) has not bothered to format the values from the GPS module for viewing in the software UI in any way whatsoever, resulting in a value that is meaninglessly precise because the measurement wasn't that accurate to begin with. Even if the value is accurate, locating individual atoms by coordinates is not actually useful in most cases, and the motions of multiple systems within our physical world (continental drift, subtle vibrations, Brownian motion , etc.) would render the precise value obsolete rather quickly. For the decimal places past the 5th on the latitude, the digits given are actually the first part of the decimal expansion of the constant e (2.7182818284), while for the decimal places past the 5th on the longitude, the digits given are part of the decimal expansion of the constant π (3.14159265358) starting with the second digit (4). The title text references how at sufficiently small distances, our understanding of reality itself begins to break down. Smaller than the Planck length , which is more than a quintillion times smaller than the diameter of a proton, the ideals of Euclidean geometry no longer apply and space itself may be composed of a quantum foam where the very geometry of spacetime itself fluctuates, meaning coordinate systems based on an assumption that space doesn't change would no longer work. String theory, on the other hand, assumes that at a short enough distance the world is composed of ten space dimensions, which precludes the use of a two-dimensional coordinate system (not that our “normal” three dimensions don't do so in themselves). The actual number of longitude digits needed to identify a point to a particular precision depends on its latitude. Near the poles, you need fewer longitude digits than at the equator – starting with one digit fewer at around lat. 85°, past all constantly inhabited human settlements, and with two digits fewer at lat. 89.5°, inaccessible to anyone but polar researchers and the occasional guided tour. The number of latitude digits for some particular accuracy stays essentially the same everywhere. *Since the Earth is not exactly spherical, the actual length of one degree of latitude varies between 110.574 km (68.707 mi) at the equator and 111.694 km (69.403 mi) at the poles, while one degree of longitude is 111.320 km (69.171 mi) at the equator, 55.800 km (34.673 mi) at lat. 60°, and 0 km (0 mi) at the poles. [Single panel containing a table with two columns for "Lat/Lon Precision" and "Meaning" and a caption above the table.] Caption: What The Number of Digits in Your Coordinates Means [Row 1] Lat/Lon: 28°N, 80°W Meaning: You're probably doing something space-related [Row 2] Lat/Lon: 28.5°N, 80.6°W Meaning: You're pointing out a specific city [Row 3] Lat/Lon: 28.52°N, 80.68°W Meaning: You're pointing out a neighborhood [Row 4] Lat/Lon: 28.523°N, 80.683°W Meaning: You're pointing out a specific suburban cul-de-sac [Row 5] Lat/Lon: 28.5234°N, 80.6830°W Meaning: You're pointing to a particular corner of a house [Row 6] Lat/Lon: 28.52345°N, 80.68309°W Meaning: You're pointing to a specific person in a room, but since you didn't include datum information, we can't tell who [Row 7] Lat/Lon: 28.5234571°N, 80.6830941°W Meaning: You're pointing to Waldo on a page [Row 8] Lat/Lon: 28.523457182°N, 80.683094159°W Meaning: "Hey, check out this specific sand grain!" [Row 9] Lat/Lon: 28.523457182818284°N, 80.683094159265358°W Meaning: Either you're handing out raw floating point variables, or you've built a database to track individual atoms. In either case, please stop.

Shadow Biosphere

Shadow Biosphere

https://www.xkcd.com/2171

https://www.explainxkcd.com/wiki/index.php/2171:_Shadow_Biosphere

[Cueball and Megan are standing facing each other. A shadowy figure is behind Megan.] Shadowy figure: These days most of our funding comes in from the shadow biotech industry. Megan: Did you hear something? Cueball: I think it's the wind. [Caption below the panel:] The shadow biosphere exists, but if you study it, you become a shadow biologist.

A shadow biosphere is a hypothetical microbial biosphere of Earth that uses radically different biochemical and molecular processes than currently known life. Although life on Earth is relatively well-studied, the shadow biosphere may still remain unnoticed because the exploration of the microbial world targets primarily the biochemistry of the macro-organisms. Because organisms based on RNA would not have ribosomes, which are usually used to detect living microorganisms, they would be difficult to find in normal circumstances. The comic suggests that this hypothetical biosphere exists, and its study is funded by "shadow biotech" corporations. The field would be called "shadow biology", so people that study it would be "shadow biologists". However, this is reinterpreted to mean "shadow" biologist, meaning that anyone that studies it becomes undetectable. A "shadowy" figure, presumably a shadow biologist, is telling this to Megan and Cueball , but they are not shadow biologists and can't hear him. The title text references desert varnish , an orange-yellow to black coating found on exposed rock surfaces in arid environments, which has been suggested as a potential candidate for a shadow biosphere. Unless a building was made with already-varnished rocks, it would be impractical to cover a building in desert varnish (it forms naturally on rocks over thousands of years). Ignoring its impracticality, the joke is that if a building were covered in desert varnish, it would supposedly be invisible to biologists who don't study the shadow biosphere. [Cueball and Megan are standing facing each other. A shadowy figure is behind Megan.] Shadowy figure: These days most of our funding comes in from the shadow biotech industry. Megan: Did you hear something? Cueball: I think it's the wind. [Caption below the panel:] The shadow biosphere exists, but if you study it, you become a shadow biologist.

Lunar Cycles

Lunar Cycles

https://www.xkcd.com/2172

https://www.explainxkcd.com/wiki/index.php/2172:_Lunar_Cycles

Understanding lunar cycles Nodal precession [A diagram showing a broad cosine-like wave with wavelength labelled as 18.6 years. To the right are two diagrams showing an orbital cycle moving in and out of plane.] Apsidal precession [A diagram similar to the one above but with a slightly shorter wavelength, labelled as 8.9 years. To the right are two diagrams showing an elliptical orbit around a planet and the same orbit rotated.] Phase [A diagram similar to those above with a shorter wavelength, labelled as 29.5 days. To the right is a diagram showing four phases of the moon: New, Waxing crescent, Waxinf gibbos, Full.] Distance [A diagram similar to those above with a shorter wavelength, labelled as 27.5 days. To the right is a diagram showing the distance of the moon from the Earth over time, with distances marked by arrows.] Earth-Moon relative size [A wave with long wavelength with an arrow pointing to the minimum labelled 'Earth bigger' and an arrow pointing to the maximum labelled 'Moon bigger'. To the right are two diagrams of the moon and Earth, one showing the Earth bigger than the Moon and the other showing the Moon bigger than the Earth.] Lunar shape [A wave with long wavelength with an arrow pointing to the minimum labelled 'Circle' and an arrow pointing to the maximum labelled 'Square'. To the right is a diagram showing a circle, a circle transforming into a square with outward arrows at each corner and a square transforming into a circle with inward arrows.] Lunar mood [A wave with long wavelength with an arrow pointing to the minimum labelled 'Bad' and an arrow pointing to the maximum labelled 'Good'. To the right are four emojis: :), :|, :(, :|] [A superimposed graph of all the above waves. Different points on the graph are labelled: Harvest moon, Supermoon, Blue moon, Skinny Jeans popular, Super blood moon, Golden age of TV, Dire moon, Pork moon, Two week window in which astrology works, Total eclipse of the sea.]

This comic shows a mixture of real, scientific lunar cycles and cycles that are comedic or fictional in nature. The light gray "phase × distance" plot does not correspond to the product of periods given for phase and distance, which look like this instead. A harvest moon is the traditional name for the full moon closest to the autumnal equinox, but there is nothing astronomically significant about it. A supermoon is a full or new moon when the Moon is closest to the Earth, resulting in a slightly larger-than-usual apparent size. A full supermoon is roughly 14% larger in diameter than when the Moon is furthest away. See also 1394: Superm*n . A blue moon was originally a description of the very rare occurrence of atmospheric conditions that gave the Moon a bluish tinge, hence the expression "once in a blue moon" for something that happens only rarely. However, the actual blue-hued appearance of the moon is so rare that it the phrase "blue moon" has been reinterpreted as referring to a merely uncommon event: the occurrence of two full moons in a single calendar month. That kind of "blue moon" naturally does not look any different from a regular full moon. A blood moon refers to the moon during a lunar eclipse. While the popularity of skinny jeans ( slim-fit pants ) does change over time, the idea that this is connected to a lunar cycle is also a joke. The Golden Age of Television is said to have occurred in the 1940s and 50s, and the 2000s. Pork moon cakes have been prepared in the rural areas west of Shanghai since more than a thousand years ago, for the Chinese Mid-Autumn Festival . "The Vampire of the Dire Moon " is a recently introduced, uncommon card from the Magic: The Gathering card game. Astrology is a pseudoscience which claims that the positions of the celestial bodies can be used to predict human affairs. The chart jokingly suggests that astrology actually does work, but only within a very specific two-week timeframe. Finally, while the idea of a total eclipse of the sea seems absurd, an eclipse was famously used to explain the migration of maritime animals : biologists were beginning to unravel the mystery of this ‘false bottom’–a layer in the ocean that looks the the sea floor on the sounder but isn’t–which covered much of the ocean. This false bottom rises in up at night and sinks down during the day. This rising and falling is in fact caused by the largest migration of animal on Earth–everything from fish, shrimp and jellyfish, moving hundreds of meters in unison up and down each day.... the moon moved into its place in front of the sun, daylight rapidly faded, and the scientists solved the migration mystery: the deep layer of animals began to rise. Bioluminescent creatures started to shine, and nocturnal creatures started a frantic upward thrust. As the world grew darker, they swam upward nearly 80 meters. But this frantic migration didn’t last long. As the moon receded and the sun revealed itself, the massive animal layer did an about-face, scrambling back into the safety of the darkness. (Backus, Clark, and Wing (1965) "Behaviour of certain marine organisms during the solar eclipse of July 20, 1963" Nature 4975: 989-91.) The Antikythera mechanism mentioned in the title text is an ancient Greek machine, rediscovered in 1901, designed to calculate astronomical positions. The title text jokes that there is a set of gears on said mechanism that is used to predict the popularity of "skinny jeans" and "low-rise waists." Since it was likely created in the 1st or 2nd century B.C., it is impossible for the creators to have had any knowledge of skinny jeans or low-rise waists - both are modern-day clothing fashions [ citation needed ] . Understanding lunar cycles Nodal precession [A diagram showing a broad cosine-like wave with wavelength labelled as 18.6 years. To the right are two diagrams showing an orbital cycle moving in and out of plane.] Apsidal precession [A diagram similar to the one above but with a slightly shorter wavelength, labelled as 8.9 years. To the right are two diagrams showing an elliptical orbit around a planet and the same orbit rotated.] Phase [A diagram similar to those above with a shorter wavelength, labelled as 29.5 days. To the right is a diagram showing four phases of the moon: New, Waxing crescent, Waxinf gibbos, Full.] Distance [A diagram similar to those above with a shorter wavelength, labelled as 27.5 days. To the right is a diagram showing the distance of the moon from the Earth over time, with distances marked by arrows.] Earth-Moon relative size [A wave with long wavelength with an arrow pointing to the minimum labelled 'Earth bigger' and an arrow pointing to the maximum labelled 'Moon bigger'. To the right are two diagrams of the moon and Earth, one showing the Earth bigger than the Moon and the other showing the Moon bigger than the Earth.] Lunar shape [A wave with long wavelength with an arrow pointing to the minimum labelled 'Circle' and an arrow pointing to the maximum labelled 'Square'. To the right is a diagram showing a circle, a circle transforming into a square with outward arrows at each corner and a square transforming into a circle with inward arrows.] Lunar mood [A wave with long wavelength with an arrow pointing to the minimum labelled 'Bad' and an arrow pointing to the maximum labelled 'Good'. To the right are four emojis: :), :|, :(, :|] [A superimposed graph of all the above waves. Different points on the graph are labelled: Harvest moon, Supermoon, Blue moon, Skinny Jeans popular, Super blood moon, Golden age of TV, Dire moon, Pork moon, Two week window in which astrology works, Total eclipse of the sea.]

Trained a Neural Net

Trained a Neural Net

https://www.xkcd.com/2173

https://www.explainxkcd.com/wiki/index.php/2173:_Trained_a_Neural_Net

[White Hat is looking at a smartphone in his hand, while he talks to Cueball, who lifts a hand palm up towards White Hat.] White Hat: Oh, hey, you organized our photo archive! Cueball: Yeah, I trained a neural net to sort the unlabeled photos into categories. White Hat: Whoa! Nice work! [Caption below the panel:] Engineering Tip: When you do a task by hand, you can technically say you trained a neural net to do it.

An artificial neural network , also known as a neural net, is a computing system inspired by a human brain, which "learns" by considering lots and lots of examples to develop patterns. For example, these are used in image recognition - by analyzing thousands or millions of examples, the system is able to identify particular objects. Neural networks typically function with no prior knowledge, and are "trained" by feeding in examples of the thing that they are told to analyze. Here, Cueball is telling White Hat how he trained a neural net to sort photos into categories. The joke in the comic, is the engineering tip from the caption. It states that since a human brain is already a neural network, albeit a biological one instead of an artificial one, then by teaching oneself (or others) to do a task, you are de facto training a neural network to do so. So instead of designing and training an artificial neural net that could do this task, all Cueball did was manually sort the photos into categories (although he could then use those sorted images to train an artificial neural network). This is the first time such a tip has been used, but engineering tip just continues the tips trend that Protip began long ago. It is not advisable to say this in real life, because you might then be expected to use your already-trained neural net to do a similar task (or redo the same task) with much greater speed, thus ruining the façade. However, presenting work done by humans as work done by machines has been done in real life, perhaps starting with The Turk in 1770 and continuing into the present day by various AI-themed startups. For example, Engineer.ai described itself as using "natural language processing and decision trees" to automate app development, but was actually employing humans . The title text is a continuation of this joke, as instead of designing and training two artificial neural nets named "Emily" and "Kevin", all he has done is train two people with those names to manually respond to support tickets. Again, doing this in real life is not advisable, as people are offended when they are referred to by programmers as deterministic automata with no free will. [ citation needed ] Neural networks have been trained to perform other tasks that are routine for humans, but formerly more difficult for computers, such as driving cars, playing games like chess, go, and Jeopardy!, and communication skills like extracting phonological information from speech as per Figure 1 here . In 1897: Self Driving , Randall suggested that crowdsourced applications like ReCAPTCHA, that have been used to train neural nets to recognize objects necessary for safe driving in photographs, may also be used for Wizard of Oz experiments . An example of such a Wizard of Oz experiment for phonological training as a form of peer learning has been explored, and related work is occurring on automating vocational training. The extent to which computer neural nets are analogous to human neurobiology is a topic which fascinates the scientist and layperson alike. While there is no fully universal consensus on the matter, at least one apparently longstanding theoretical paradigm has received attention recently. [White Hat is looking at a smartphone in his hand, while he talks to Cueball, who lifts a hand palm up towards White Hat.] White Hat: Oh, hey, you organized our photo archive! Cueball: Yeah, I trained a neural net to sort the unlabeled photos into categories. White Hat: Whoa! Nice work! [Caption below the panel:] Engineering Tip: When you do a task by hand, you can technically say you trained a neural net to do it.

First News Memory

First News Memory

https://www.xkcd.com/2174

https://www.explainxkcd.com/wiki/index.php/2174:_First_News_Memory

[Ponytail, Cueball, Megan, Hairy, White Hat, Black Hat and Hairbun are all at a party, discussing their earliest news memories.] [Panel with Ponytail, Cueball, Megan, and Hairy] Ponytail: What's your first news memory? Cueball: I always like this question! Mine was the 1988 election. Megan: Berlin wall for me. You? [Frame-less panel with Megan, Hairy, White Hat, and Black Hat] Hairy: Watching the Challenger launch in class. We were so excited; everyone was horrified when it blew up. Hairy: It was 1995. Hairy: Our teacher got fired soon after. [Panel with Hairy, White Hat, Black Hat, and Hairbun] White Hat: Mine's the 2016 election. Hairbun: ...aren't you in your 30's? White Hat: Look, we're not all great about keeping up with the news, OK? [Panel with White Hat, Black Hat, and Hairbun] Black Hat: My first memory is when we landed on the moon. Black Hat: My second memory is my mom telling us we were moving to Earth instead, to blend in with the humans. Hairbun: This explains a lot.

Seven xkcd characters are discussing their "first news memory", their first memory of an event that was reported by the news media. A person's "first news memory" can vary based on their age, the region where they grew up, and how in touch with the news they are. The following is a breakdown of the memories given by the characters, in typical xkcd fashion: Four people are standing in-frame: Ponytail , Cueball , Megan , and Hairy . Ponytail gets the ball rolling by posing the question. Cueball recalls the election coverage from the year 1988. As Randall lives in the US, this is probably the 1988 US presidential election in which George H. W. Bush defeated Michael Dukakis. Megan recalls the removal of the Berlin wall , which began in 1989. The view pans right to show Megan, Hairy, White Hat , and Black Hat standing around. Hairy recalls the Challenger explosion , which occurred in 1986. Many schools allowed teachers to bring a television to the classroom to show their students the launch, sadly unaware of the impending disaster the children would witness. However, Hairy remembers watching the footage in 1995, so Hairy's teacher was knowingly showing the students recorded footage of a disaster. Presumably, knowingly showing a number of young schoolchildren a traumatizing event led to the teacher's dismissal. The view pans right to show Hairy, White Hat, Black Hat, and Hairbun standing around. White Hat says that his first news memory was about the 2016 election (presumably the 2016 US presidential election ), which is only three years prior to the publication date of this comic. As he is in his thirties, this implies that he spent most of his life not paying attention to the news. The view pans right, leaving just White Hat, Black Hat, and Hairbun in-frame. Black Hat 's first sentence is normal in the context of the question, albeit making him older than the others. Given only the sentence 'we landed on the moon,' the 'we' is inferred to be 'the United States of America' or 'the human race.' The first moon landing occurred on July 20, 1969. However, Black Hat goes on to say that 'my second memory is my mom telling us we were moving to Earth instead, to blend in with the humans.' This gives a completely different meaning to his first memory, as it is now implied that Black Hat is a humanoid alien who moved to the Moon, but whose mother then decided to move to Earth. Whether any news coverage resulted is unclear. Hairbun then remarks that this revelation explains Black Hat's odd (and usually disruptive) behavior. It is unclear whether Black Hat is telling the truth, but knowing Black Hat, and considering the fact that this would be unlikely to receive news coverage, he is likely intentionally trying to unnerve others. Another possibility is that Black Hat was the youthful victim of a prank by his own mother, with Hairbun's comment implying that such an upbringing accounts for the trollish aspects of Black Hat's character in the present day. The title text gives the claim that flashbulb memories of big events can be unreliable. Randall (or another character in the comic, possibly Hairbun) denies this claim, claiming to remember watching on CNN as the Challenger spacecraft crashed into the Berlin Wall. This is an inaccurate memory of these two events, as the Challenger explosion occurred in 1986 over the Atlantic Ocean, just east of Cape Canaveral, Florida, and did not occur near the Berlin Wall (in Berlin, Germany). Also, the Berlin Wall was intentionally demolished starting in 1989; it was not damaged by a space shuttle. It is possible that this memory also conflates those events with those of the September 11 attacks since the latter did involve three winged craft crashing into and destroying landmark structures. [Ponytail, Cueball, Megan, Hairy, White Hat, Black Hat and Hairbun are all at a party, discussing their earliest news memories.] [Panel with Ponytail, Cueball, Megan, and Hairy] Ponytail: What's your first news memory? Cueball: I always like this question! Mine was the 1988 election. Megan: Berlin wall for me. You? [Frame-less panel with Megan, Hairy, White Hat, and Black Hat] Hairy: Watching the Challenger launch in class. We were so excited; everyone was horrified when it blew up. Hairy: It was 1995. Hairy: Our teacher got fired soon after. [Panel with Hairy, White Hat, Black Hat, and Hairbun] White Hat: Mine's the 2016 election. Hairbun: ...aren't you in your 30's? White Hat: Look, we're not all great about keeping up with the news, OK? [Panel with White Hat, Black Hat, and Hairbun] Black Hat: My first memory is when we landed on the moon. Black Hat: My second memory is my mom telling us we were moving to Earth instead, to blend in with the humans. Hairbun: This explains a lot.

Flag Interpretation

Flag Interpretation

https://www.xkcd.com/2175

https://www.explainxkcd.com/wiki/index.php/2175:_Flag_Interpretation

[8 panels in 2 rows, 4 panels per row - each panel shows a flagpole in a different state of flying flag(s) with a caption at the bottom of the panel below the flagpole.] [The US flag at half mast.] Caption: Someone important died [The same flag at three-quarter mast.] Caption: Someone died but we're not sure how we feel about them [The flag at the base of the mast.] Caption: Everyone important died [Two identical flags at full mast.] Caption: Someone important was successfully cloned [Two identical flags at half mast.] Caption: An important person died battling their evil clone [An upside-down flag at half mast.] Caption: Nobody has died for weeks and that seems good but statistically it's very alarming. [A normal-sized flag at half mast and five tiny flags at full mast.] Caption: Someone diverted a trolley to save five people by killing one important person [A flagpole with no flag.] Caption: The person who knows where the flag is stored at night died.

In many countries including the United States (whose flag is depicted in the comic), it is customary to lower the flag to half staff when important public figures die. This is normally done by raising the flag to full height, then immediately "lowering" it to half height. In the US, regulations regarding flying the flag at half staff specify the length of time for the flag to be flown at half staff, and are based on the importance of the person who has died. There are no regulations where the flag would be flown at any height other than full height or half staff, and there are no regulations where multiple flags would be flown. The definition of half-staff, or half-mast, differs between countries and does not necessarily imply flying the flag at half the height of the pole or mast. For example, in the USA the flag is usually flown at half the height of the pole, whereas UK practice is to leave space for an 'invisible flag' above the flown flag, which may mean flying the flag near the top of the pole depending on its height. These differing practices contribute to confusion and ambiguity concerning the flag height, which is exploited in the comic. Randall, as usual, makes a humorous list of fictional additional traditions. The title text is a reference to The Persistence of Memory and other paintings and sculptures by Salvador Dalí which include watches and other objects that are melting. [8 panels in 2 rows, 4 panels per row - each panel shows a flagpole in a different state of flying flag(s) with a caption at the bottom of the panel below the flagpole.] [The US flag at half mast.] Caption: Someone important died [The same flag at three-quarter mast.] Caption: Someone died but we're not sure how we feel about them [The flag at the base of the mast.] Caption: Everyone important died [Two identical flags at full mast.] Caption: Someone important was successfully cloned [Two identical flags at half mast.] Caption: An important person died battling their evil clone [An upside-down flag at half mast.] Caption: Nobody has died for weeks and that seems good but statistically it's very alarming. [A normal-sized flag at half mast and five tiny flags at full mast.] Caption: Someone diverted a trolley to save five people by killing one important person [A flagpole with no flag.] Caption: The person who knows where the flag is stored at night died.

How Hacking Works

How Hacking Works

https://www.xkcd.com/2176

https://www.explainxkcd.com/wiki/index.php/2176:_How_Hacking_Works

[Two panels with a caption below each panel:] [Three masked characters standing near a desk with a computer inside a home. One of the masked characters is holding a notebook.] Masked Character 1 [holding a walkie-talkie]: Control, we have flown to the USA and breached the target's house. Masked Character 2: They wrote all their passwords in a book labeled "Passwords"! Masked Character 3: The fool! [Caption below the panel:] How people think hacking works [Two Cueball-like characters, each sitting on opposite sides of a single desk with laptops in front of them] Cueball 1: Hey look, someone leaked the emails and passwords from the Smash Mouth message boards. Cueball 2: Cool, let's try them all on Venmo. [Caption below the panel:] How it actually works

In similar spirit to 538: Security , this comic deals with how many people perceive hacking and security best practices, and how it differs from the actual reality. Specifically, the comic points out the flaw in the argument of some security-minded people that writing passwords down on a sheet of paper is a massive operational security vulnerability, not accounting for the threat model of the general public: reused passwords being leaked from seemingly benign places. The first panel shows a group of masked men, who have apparently flown to the US from a different country and broken into someone's house. They find a book labeled "Passwords" that contains all the passwords of their target, and one reports this using a walkie-talkie , while another remarks that the target is a fool for writing down their passwords. While it is true that storing passwords on paper is generally a bad idea, one has to keep in mind the alternatives—password reuse or unencrypted password documents on a computer—that non-technical people might otherwise engage in. These are far easier to exploit for a casual attacker that goes for quantity over quality. In addition, given the larger group of potential attackers are the remote attackers, storing passwords on a piece of paper, while horrible for security from a local "in person" attacker, is actually pretty effective against a remote attacker being able to gather up your passwords. The second panel goes into detail how such an attack is usually executed: First, a database containing usernames/emails and associated passwords or insufficiently salted password hashes is stolen from an improperly secured website. Randall's example uses a fictional breach of a small forum dedicated to the band Smash Mouth , but even large companies are not immune to leaks. Assuming the passwords were not hashed, the crooks then go on and automatically try to log in to a popular payment service, Venmo , with the harvested credentials. Even though the success rate might be just fractions of a percent, due to the scale and cheapness of the attack (which can be automated, requiring no sustained effort from the crooks), it is likely still profitable. Such an attack has previously been discussed in 792: Password Reuse . Although writing passwords on paper can allow users to create unique complex passwords without being limited by human memory, and therefore protect themselves from these sorts of mass-breach attacks, their passwords are now more vulnerable to insider attacks by e.g. family members, close friends, or co-workers. The way recommended by most security experts to prevent these kinds of attacks is to use a password manager - a secure application that stores all of your passwords in an encrypted vault that only you can access. This way, you only need to remember one password - the master password to your vault - and all of your other passwords can be as long, different, and random as you like. This means that even if a crook manages to get one of your passwords, they won't be able to use it to access any other sites, and so the attack shown in the comic would fail. Websites can also support two-factor authentication , where the user must supply a randomly changing code from a second device, such as a cell phone application or standalone keyfob, to log in. The title text is referring to Smash Mouth's song " All Star ," where the first line of the lyrics is "Somebody once told me the world is gonna roll me." The singer subsequently admits that he is not "the sharpest tool in the shed," which would be consistent with re-using simple passwords across multiple accounts (including financial accounts). [Two panels with a caption below each panel:] [Three masked characters standing near a desk with a computer inside a home. One of the masked characters is holding a notebook.] Masked Character 1 [holding a walkie-talkie]: Control, we have flown to the USA and breached the target's house. Masked Character 2: They wrote all their passwords in a book labeled "Passwords"! Masked Character 3: The fool! [Caption below the panel:] How people think hacking works [Two Cueball-like characters, each sitting on opposite sides of a single desk with laptops in front of them] Cueball 1: Hey look, someone leaked the emails and passwords from the Smash Mouth message boards. Cueball 2: Cool, let's try them all on Venmo. [Caption below the panel:] How it actually works

Gastroenterology

Gastroenterology

https://www.xkcd.com/2177

https://www.explainxkcd.com/wiki/index.php/2177:_Gastroenterology

[The first five panels appear in a single row.] [Ponytail, wearing a lab coat, and a guy wearing a scrubs hat rush in from the right side of the panel. Ponytail is holding a water bottle. There is a desk on the left of the panel with two jars.] Hat guy: Hurry, they're right behind us! [Zoom in on Ponytail, behind the desk, pouring the two smaller jars into the water bottle.] An arrow points to the left jar: Probiotic An arrow points to the right jar: Antibiotic [A borderless panel. Zoom out on Ponytail shaking the water bottle to mix the two substances.] Shake Shake Shake [Ponytail throws the water bottle toward the right side of the panel, at something off-screen.] [Hat guy and Ponytail run toward the left side of the panel, as the water bottle explodes.] BOOM [The last panel is the only panel in its row, appearing at the far right end of the row and slightly narrower than the fifth panel above it.] [Megan and Ponytail sitting at a table, facing each other, having a meal.] Megan: So what's gastroenterology like? Ponytail: Pretty boring. Lotta paperwork.

Gastroenterology is the study of the normal function and diseases of the digestive system: esophagus, stomach, small intestine, colon and rectum, pancreas, gallbladder, bile ducts and liver. Antibiotics are substances that kill bacteria. They are effective at treating bacterial infections, including in the gut; unfortunately, they can also kill the normal gut bacteria. Probiotics are harmless or helpful bacteria which are sometimes used to replace the bacteria killed by an antibiotic. This reduces chances of re-infection by pathogens, and allows the natural gut microbiome to recover more effectively; comic 1471 was about the same theme. Probiotics are included in many foods, such as yogurt, as well as supplements, and are marketed as having health benefits. The comic plays on the names probiotic and antibiotic. When matter and antimatter are mixed, they annihilate each-other, rapidly releasing energy (an explosion). This comic imagines a similar process when probiotics and antibiotics are mixed: Ponytail and a nurse runs into a room, with someone chasing after them, leading the nurse to exclaim that “they’re right behind us.” Ponytail mixes the probiotics and antibiotics, and throws the jar like a grenade, before continuing to run with the nurse. The reaction between the probiotics and antibiotics causes the jar to explode, presumably killing the pursuer. In reality, antibiotics and probiotics are often used simultaneously during treatment, but they are taken so that they do not mix (taken at different times or by different methods). Mixing them as in the comic, would just cause the antibiotic to kill the probiotic bacteria. Explosive reactions between antibiotics and probiotics are highly unlikely. [ citation needed ] Matter and antimatter would react pretty much instantly upon mixing, not a short time later, as in the comic. (Also, one could not keep antimatter in a normal jar, or pour it in an atmosphere). The reaction shown is similar to the reaction between a strong acid and a strong base, which could cause an explosion after a short delay if kept in a tightly sealed container like a water bottle, as in the explosion here. In the last panel, Ponytail is giving a more mundane summary of what gastroenterology is like (lots of paperwork). This is similar to Indiana Jones saying that archaeology is boring. The explosion sequence might be: In the title text, Ponytail adds that her work makes her aware of a child coughing as the server was bringing food at the restaurant table, exposing the food to possible germs that could cause a gastrointestinal infection. [The first five panels appear in a single row.] [Ponytail, wearing a lab coat, and a guy wearing a scrubs hat rush in from the right side of the panel. Ponytail is holding a water bottle. There is a desk on the left of the panel with two jars.] Hat guy: Hurry, they're right behind us! [Zoom in on Ponytail, behind the desk, pouring the two smaller jars into the water bottle.] An arrow points to the left jar: Probiotic An arrow points to the right jar: Antibiotic [A borderless panel. Zoom out on Ponytail shaking the water bottle to mix the two substances.] Shake Shake Shake [Ponytail throws the water bottle toward the right side of the panel, at something off-screen.] [Hat guy and Ponytail run toward the left side of the panel, as the water bottle explodes.] BOOM [The last panel is the only panel in its row, appearing at the far right end of the row and slightly narrower than the fifth panel above it.] [Megan and Ponytail sitting at a table, facing each other, having a meal.] Megan: So what's gastroenterology like? Ponytail: Pretty boring. Lotta paperwork.

Expiration Date High Score

Expiration Date High Score

https://www.xkcd.com/2178

https://www.explainxkcd.com/wiki/index.php/2178:_Expiration_Date_High_Score

[Title up in the panel:] What's the most expired item you've found in your house? Calculate your Expiration Date High Score (must be something you purchased) [Equation in a circle:] Score = (year you found item) minus (year item expired) divided by (your age when you found it), multiplied by 100 [Megan and Cueball talking in a kitchen, with Megan holding a can.] Megan: These beans expired in 2010! That's... let's see... 24.3! New personal best! Cueball: You're never going to beat your mom's jar of pickles from 1978. Megan: Maybe there are more cans in there. Remind me not to look until 2030. Cueball: This is the worst competition. The formula suggests Megans age to be 37, if this comic plays in 2019, when it was released. That puts her birth year to either 1982 or 1981 (depending on whether this plays before or after her birthday in 2019). This is in slight contrast to 630: Time Travel , which implies her birth year to be 1983.

Randall is introducing the rules of the game Expiration Date High Score hence the title. If you find an item which you purchased, but is now past its expiration date , you get a score which is what percent of your lifetime elapsed between when the item expired and when you found it. Megan , looking in a cupboard, find a can of beans that expired in 2010 (9 years ago), and that gives her a score of 24.3. Megan's age is thus revealed to be 37, found by substituting 2019 and 2010 into the formula 100*(2019-2010)/<age> = 24.3 and solving for the age. This is consistent with 630: Time Travel , in which Megan's date of birth is given as 1983. Cueball then remarks that she will never beat her mom's jar of pickles that was from 1978. Megan then wonders if there are more cans (from 2010 or before) in the cupboard, and asks Cueball to remind her to not look any further until 2030. At that time the can would have been 20 years old and she would be 48, giving such a can a score of 100*(2030-2010)/48 = 41.6. That would thus beat her mom's high score. If her mom's jar had expired in 1978 (not clear from the text), and for instance was found last year in 2018, then the formula for the mother's score would be 100*(2018-1978)/<Mom's age>. And this should then not be more than 41, thus revealing the mother age to be around 100 years old today (98 last year). Of course the jar could have had an expiration day some years later, or have been found earlier. Otherwise Megan's mom would have been above 60 when giving birth to Megan. Of course Megan could also just take this extra long wait in case the next can is not from 2010 but only 2013 etc. Cueball's final remark is that this is a terrible competition, the worst ever. Because keeping food that can spoil could potentially be dangerous, if not so, at least disgusting when finally trying to get rid of it later. Many perishable items, such as food, cosmetics, medications, batteries, or condoms, have expiration dates, or sometimes best by dates. The only other rule is, that it has to be something you have purchased yourself, so that heritages or stuff that was left in the basement when one moved in, does not count. A score of 100 or higher would indicate the item expired when you were born or before you were born, meaning it was already expired when you purchased it. The joke is, that owning expired items without noticing for a long time, is here getting you a high score, while in reality it is not considered favorable to have food that has expired long time ago. [ citation needed ] The other joke is both the items in the comic (a can of beans and a jar of pickles) do not go bad with time but in fact remain edible indefinitely (as long as the jar/can is not opened and is undamaged.) Food going bad, in the sense that it will make you sick if you eat it, is most often caused by harmful bacteria growing in the food. Less often caused by fungi or yeast growing in the food and creating a poisonous substance, like methanol (wood alcohol.) The process of canning food involves boiling it to kill all possible pathogens, then sealing it in a can/jar while the food is still hot, with no air bubble. As long as this process is done correctly, the jar lid will have an airtight seal, so as long as the can is not punctured, or does not have a hole become rusted through, no bacteria/virus/yeast/fungi can get in and the food cannot spoil. Some food may discolor over time in the jar/can, or the texture may change, but it cannot go bad in a way that makes it unsafe to eat. Megan's mom could not have a jar of pickles with a 1978 expiration date because in 1978 jars and cans of food did not have expiration dates. Since then many countries introduced laws and regulations requiring companies to put expiration dates on perishable goods. In some instances this can have the negative effect of people throwing out good food by blindly following the suggested expiration date. This behavior can incentivize companies to adjust the expiration date, or put expiration dates on non-perishable goods, so that people will re-buy the products sooner. The title text continues the conversation from the comic. Cueball remarks that they moved since 2010... Thus the beans were apparently bought while living in a different home, meaning they were moved along with their other belongings. This is somewhat unusual as many people take moving as an opportunity to go through their old stuff and get rid of things they no longer need. Since the rules clearly states that you have to have bought it yourself, it could not have been in the house when they moved in, they had to have brought it along (unless they later bought something that was already expired). But given Megan's final answer that "some of us were just born to be champions" indicates that she did bring it along, anticipating this game, and thus given her self a great score. And as is clear she is willing to wait 11 years to try to beat her mom's score. It is not clear why they are keeping items for long periods of time in order to win. An easier way to win this game would be to buy food that is already expired. One could obtain a score of 100 simply by buying something that expired when one was born, and finding it the next day. [Title up in the panel:] What's the most expired item you've found in your house? Calculate your Expiration Date High Score (must be something you purchased) [Equation in a circle:] Score = (year you found item) minus (year item expired) divided by (your age when you found it), multiplied by 100 [Megan and Cueball talking in a kitchen, with Megan holding a can.] Megan: These beans expired in 2010! That's... let's see... 24.3! New personal best! Cueball: You're never going to beat your mom's jar of pickles from 1978. Megan: Maybe there are more cans in there. Remind me not to look until 2030. Cueball: This is the worst competition. The formula suggests Megans age to be 37, if this comic plays in 2019, when it was released. That puts her birth year to either 1982 or 1981 (depending on whether this plays before or after her birthday in 2019). This is in slight contrast to 630: Time Travel , which implies her birth year to be 1983.

NWS Warnings

NWS Warnings

https://www.xkcd.com/2179

https://www.explainxkcd.com/wiki/index.php/2179:_NWS_Warnings

[Heading on top of frame:] Alert: Everyone Just Keep An Eye Out In General [A map of the 48 contiguous states of the United States, surrounded by several warning polygons that cover most or all of the area, along with parts of neighboring countries or the sea.] [The following warning headers are printed in different colors around the map of the United States, some of which are cut off by the frame. Assumptions about text outside of the frame are given in square brackets.] Gale Warning, Tornado Warning, Flash Flood Warning, Air Quality [Alert] Frost Advisory, Severe Thunderstorm Warning, Dense Fog Advisory [Hurricane Force W]ind Watch, Tropical Storm Warning, Ice Stor[m Warning] [Extreme Cold] Warning, Heat A[dvisory] [Flood] Advisory, Snow [Squall Warning] [Storm Surge] Warning, Brisk W[ind Advisory] [Lake Effect Snow] Watch, Coastal Fl[ood Advisory] Dense Smo[ke Advisory] [Severe Weather Sta]tement, Gale War[ning] [Lakeshore Flood] Advisory, Wind Chill Ad[visory] [Extreme] Cold Warning, Blizzard Warn[ing] Hurricane Warning, Extreme Fire [Danger] [Freezing Fog Adv]isory, Tsunami Warning, Avalanche W[arning] [Ice S]torm Warning, Frost Advisory, Fire Warning, Volcano Warn[ing] Ashfall Advisory, Red Flag Warning, Radiological Hazard Warning [Text below frame:] When the National Weather Service needs to take a day off, they just issue warnings for everything so no one is caught by surprise.

The National Weather Service (NWS) is a United States federal agency that is tasked with issuing national weather forecasts and extreme weather alerts . This comic portrays the NWS as a person that needs breaks, which is absurd, as it is an important service and would probably always have staff active, even on holidays. For example, the NWS continued to work during federal government shutdowns , as it was considered an essential service for the protection of life and property. Even if one of the NWS's 122 local weather offices were to be incapacitated, contingency plans are in place to ensure that nearby offices act as emergency cover; as happened in March 2019 with flooding in Nebraska forcing the NWS office in Valley to evacuate. Regardless, in this comic the NWS has decided to take a break, and so has opted to issue every extreme weather alert possible for the entire contiguous portion of the United States (including DC, but not Alaska or Hawaii) to make sure no one is caught by surprise by extreme weather, since the NWS will not be able to issue warnings. As the NWS could not be sure which areas will need to get warned of severe incidents, the NWS has decided to issue warning polygons that cover the entire United States (ostensibly except Alaska and Hawaii). A layer of humor is that this would necessitate warnings where they would be highly unlikely to occur in real life; examples include issuing blizzard warnings for Florida, where any amount of snow is rare, and tsunami warnings for areas very far from any ocean coastline. Each of the text warnings within the map are coloured, which matches the NWS color coding used for a given warning event. The title text mentions how some of the warnings that have been issued require action to get to safety that contradicts the other warnings, for example, an evacuation warning and a shelter in place order, since doing one would mean failing to do the other. This confusing scenario would likely prompt many concerned citizens to call emergency services for clarification, but the 911 outage alert would advise against this, adding another layer to the absurdity of the occurrence of the NWS taking a break. This comic was likely inspired by the heat wave that impacted two-thirds of the US for more than a week. NWS and tornado warnings was later mentioned in the title text of 2219: Earthquake Early Warnings . Assumptions about text outside of the frame are given in square brackets. This page from the NWS lists all the warnings and colors, including all the hex codes for them which we stole referenced. [Heading on top of frame:] Alert: Everyone Just Keep An Eye Out In General [A map of the 48 contiguous states of the United States, surrounded by several warning polygons that cover most or all of the area, along with parts of neighboring countries or the sea.] [The following warning headers are printed in different colors around the map of the United States, some of which are cut off by the frame. Assumptions about text outside of the frame are given in square brackets.] Gale Warning, Tornado Warning, Flash Flood Warning, Air Quality [Alert] Frost Advisory, Severe Thunderstorm Warning, Dense Fog Advisory [Hurricane Force W]ind Watch, Tropical Storm Warning, Ice Stor[m Warning] [Extreme Cold] Warning, Heat A[dvisory] [Flood] Advisory, Snow [Squall Warning] [Storm Surge] Warning, Brisk W[ind Advisory] [Lake Effect Snow] Watch, Coastal Fl[ood Advisory] Dense Smo[ke Advisory] [Severe Weather Sta]tement, Gale War[ning] [Lakeshore Flood] Advisory, Wind Chill Ad[visory] [Extreme] Cold Warning, Blizzard Warn[ing] Hurricane Warning, Extreme Fire [Danger] [Freezing Fog Adv]isory, Tsunami Warning, Avalanche W[arning] [Ice S]torm Warning, Frost Advisory, Fire Warning, Volcano Warn[ing] Ashfall Advisory, Red Flag Warning, Radiological Hazard Warning [Text below frame:] When the National Weather Service needs to take a day off, they just issue warnings for everything so no one is caught by surprise.

Spreadsheets

Spreadsheets

https://www.xkcd.com/2180

https://www.explainxkcd.com/wiki/index.php/2180:_Spreadsheets

[Cueball is at his computer. In the air on either side of him are an angel version of Cueball, with a halo and wings, and a devil version of Cueball, with horns and a pitchfork.] [The angel's dialogue appears in regular print, while the devil's dialogue appears in white print in black speech balloons.] Angel: Don't use a spreadsheet! Do it right . Devil: But a spreadsheet would be so easy . Angel: In the long run you'll regret it! [Closeup on Cueball, the angel, and the devil.] Angel: Take the time to write real code. Devil: Just paste the data! Tinker until it works! Devil: Build a labyrinth of REGEXREPLACE() and ARRAYFORMULA()! Devil: Feel the power! [Closeup on the devil.] Angel (off-panel): Fight the temptation! Devil: Ever tried QUERY() in Google Sheets? It lets you treat a block of cells like a database and run SQL queries on them. [Another shot of Cueball at his computer with the angel and devil at either side.] Angel: Don't listen to-- Angel: ... wait, really? Devil: Yes, and let me tell you about IMPORTHTML() ... Angel: Oooh... Spreadsheets used for complex tasks and evolving into complex algorithms was also the punchline of 1667: Algorithms .

Cueball is doing some task on his computer, with an angel and devil on either side of him , trying to influence his work. The angel is telling him to do things the "right" way, while the devil is telling him to do his work using a spreadsheet , which is considered by professional software engineers to be a shortcut or a hack. Spreadsheets provide an array of cells, which can contain information or instructions. Spreadsheets are a common end-user development tool, allowing non-developers to easily create code. However they can be hard to maintain, thus they are often mocked by developers as a wrong approach to programming. Although it is not clear from the cartoon that this is meant, the "right" alternative to using a spreadsheet for some tasks may involve a database or a more general programming language. The punch line comes when the angel becomes so intrigued by the spreadsheet functions, Google Sheets in particular, that it gives up trying to dissuade Cueball, and asks for more information from the devil. In the title text, Randall mentions a time when he created a calendar grid in Google Sheets using a list of dates. This is described as being done in a "single-cell formula", and taking a long time to run. This shows the power and complexity of spreadsheets. The procedure taking a long time to run, and freezing up the computer for 15 seconds every time it ran, was probably not what Randall's brother had in mind when he requested help. His brother learned he might need to be wary about what he gets back when asking Randall for assistance. All functions mentioned in this comic can be found in Google Sheets , but functions similar to some of them can be found in most modern spreadsheet applications. REGEXREPLACE (text, regular_expression, replacement) ⇒ Replaces part of a text string with a different text string using regular expressions . ARRAYFORMULA (array_formula) ⇒ Enables the display of values returned from an array formula into multiple rows and/or columns and the use of non-array functions with arrays. QUERY (data, query, [headers]) ⇒ Runs a Google Visualization API Query Language query across data. IMPORTHTML (url, query, index) ⇒ Imports data from a table or list within an HTML page. SEQUENCE (rows, columns, start, step) ⇒ Returns an array of sequential numbers, such as 1, 2, 3, 4. REGEXMATCH (text, regular_expression) ⇒ Whether a piece of text matches a regular expression. [Cueball is at his computer. In the air on either side of him are an angel version of Cueball, with a halo and wings, and a devil version of Cueball, with horns and a pitchfork.] [The angel's dialogue appears in regular print, while the devil's dialogue appears in white print in black speech balloons.] Angel: Don't use a spreadsheet! Do it right . Devil: But a spreadsheet would be so easy . Angel: In the long run you'll regret it! [Closeup on Cueball, the angel, and the devil.] Angel: Take the time to write real code. Devil: Just paste the data! Tinker until it works! Devil: Build a labyrinth of REGEXREPLACE() and ARRAYFORMULA()! Devil: Feel the power! [Closeup on the devil.] Angel (off-panel): Fight the temptation! Devil: Ever tried QUERY() in Google Sheets? It lets you treat a block of cells like a database and run SQL queries on them. [Another shot of Cueball at his computer with the angel and devil at either side.] Angel: Don't listen to-- Angel: ... wait, really? Devil: Yes, and let me tell you about IMPORTHTML() ... Angel: Oooh... Spreadsheets used for complex tasks and evolving into complex algorithms was also the punchline of 1667: Algorithms .

Inbox

Inbox

https://www.xkcd.com/2181

https://www.explainxkcd.com/wiki/index.php/2181:_Inbox

[Megan and Cueball are sitting at a desk, facing each other, each working on their laptop computers.] Megan: Answering email is the worst. It just leads to getting more email. Cueball: Yeah, email is a trap. [Beat panel.] [Megan looks up from her work on the computer.] Megan: I bet the reason the Ancient Romans got so much done was that they had no concept of Inbox Zero. Cueball: That explains it.

Email differs from "snail" mail, in that people often expect a prompt reply. Replying to an email may lead to another email response, thus leading to a "loop" of constant replies and responses. Since an individual email is quick and cheap to send, people send lots of them. Thus people get a lot of emails, and may spend a large portion of their day dealing with email. Megan observes that maybe the Romans got a lot done because they did not spend time on email. In doing this she plays on the email handling strategy named Inbox Zero, which they might not have had because the Roman number system had no symbol for zero. This is of course redundant, as email did not exist at the time. [ citation needed ] Inbox Zero is an approach to email inbox management espoused by Merlin Mann, with the idea that people should spend as little time as possible in their email inbox. To achieve this, one should check one's inbox as few times as practical, and quickly deal with all new emails by deleting, delegating, sending a short reply where possible or categorizing them for later tasks. Basically it's a continuation of the "touch it once" strategy for dealing with physical mail. The ancient Romans are one of the model historical societies, well revered for their culture and life. A common misconception is that Romans did not have a concept of the number zero. The Romans were aware of the concept of zero, but there is no numeral for 0 in the Roman numeral system, as Roman numerals do not have place values like Arabic numerals. A value of ten or greater is represented in Arabic numerals using 0 as a placeholder for empty place values. Roman numerals do not have such a placeholder digit, and so did not have a numeral for zero; the word nulla was used to refer to "zero" in the sense of "nothing". Various sources indicate that this eventually gave use to N as a Roman numeral for "zero", and such is the case for modern users of Roman numerals. The title text refers to Hannibal's crossing of the Alps , a famous military campaign by Hannibal against the Romans. Randall claims that Hannibal needed to invade Rome to tell them to stop sending him so many emails. The reason for this was that Rome's email was sent from a " no-reply " email address, so Hannibal had no way of replying by email, and had to tell them in person. The real reason for Hannibal to cross the Alps was because he wanted to conquer Rome. He did not conquer Rome, so he never sent his "unsubscribe" message. [Megan and Cueball are sitting at a desk, facing each other, each working on their laptop computers.] Megan: Answering email is the worst. It just leads to getting more email. Cueball: Yeah, email is a trap. [Beat panel.] [Megan looks up from her work on the computer.] Megan: I bet the reason the Ancient Romans got so much done was that they had no concept of Inbox Zero. Cueball: That explains it.

When I'm Back at a Keyboard

When I'm Back at a Keyboard

https://www.xkcd.com/2182

https://www.explainxkcd.com/wiki/index.php/2182:_When_I%27m_Back_at_a_Keyboard

[Cueball is walking while holding his phone in both hands. A line from the screen on the phone goes to the text above him, indicating what he writes:] Cueball (texting): Sure, I can reply once I'm back at a keyboard and can type more easily. [Caption below the panel:] I say this a lot for someone who routinely types thousands of words in text message conversations when someone brings up Jurassic Park .

Cueball is texting someone on his phone. However, since with a full sized physical keyboard you can type with all of your fingers, which is usually a much faster and more accurate way than using an on-screen keyboard on a smartphone, Cueball cuts off the conversation and says he will get back to whoever he was talking to when he can type on an actual keyboard, presumably at home and on his computer. While there are multiple techniques for making a smartphone increasingly easier to enter words into using its on-screen virtual keyboard , such as keyboard swiping, on-the-fly spelling and grammar checkers, and voice recognition to minimize using the keyboard at all, the combination of a full-sized keyboard along with a generous sized screen is hard to beat for speed and accuracy when typing larger blocks of text. The joke is that despite claiming to be more proficient with a physical keyboard, rather than a digital one, Randall still goes into long rants through messages on his smartphone, whenever anybody brings up Jurassic Park . There might also be a reference on Dennis Nedry, a character from the first Jurassic Park film. The programmer is responsible for a security sabotage and intends to be away from his keyboard only for a short while, but dies (not altogether) unexpectedly, worsening the situation in the park. The title text shows a typical sentence from Randall after having been in a chat over his phone. Before the sentence he has written 1500 words on his phone, all related to Jurassic Park, more or less. When he finally have written his fingers off he then says that he will have to stop now but once back at a keyboard, and even though he just typed 1500 words on his phone, he is ready to type even more (5000 words) using his keyboard. The widespread uptake of mobile devices has stark implications for user-generated content sites on the internet. According to a 2014 New York Times article, only one percent of the changes to Wikipedia articles were made via mobile devices, although they displayed about a third of all Wikipedia page views that year. [Cueball is walking while holding his phone in both hands. A line from the screen on the phone goes to the text above him, indicating what he writes:] Cueball (texting): Sure, I can reply once I'm back at a keyboard and can type more easily. [Caption below the panel:] I say this a lot for someone who routinely types thousands of words in text message conversations when someone brings up Jurassic Park .

Icon Swap

Icon Swap

https://www.xkcd.com/2183

https://www.explainxkcd.com/wiki/index.php/2183:_Icon_Swap

[A histogram of books finished over time. Spikes occur at certain points, with arrows marked "Icon Swap" pointing to the point before them.] [Caption below the panel:] I'm not saying I have a problem compulsively checking news and social media on my phone, but when I replace the social media app icon with my eBook reader, I read a half-dozen books before I get used to the change.

Randall denies having a social media addiction . However, he concludes that he must have some problem, as he opens his social media / news apps many times a day. He tries to remedy this addiction by rearranging the icons on his phone’s app launcher. Specifically, he swaps the app icon with that of an eBook reader, so opening the "social media app" would lead to the eBook reader, and vice versa. In this case, when he swaps a social media/news app with his E-book reading app, he ends up reading more books (as shown by the graph) because he is used to having his media app in its place, and is opening it up through muscle memory . This results in the punch line, where he says that this causes him to read "a half-dozen" books before his muscle memory adjusts and not he stops opening his reader as often. Presumably, he changes the icons again in order to trick his muscle memory when he makes a conscious decision to read more books or use less social media. Alternatively, Randall does not realize that he is reading books instead of a social media feed, and often gets through many books before realizing. In the title text, Randall says that there is probably an eBook app in development that will use "breaking news alerts", typically sent as push notifications , about what is happening in the book, to prompt readers to continue reading more pages. This parallels how a news app works, which would send an alert when a new event occurs. This topic is similar to one he went over in 477: Typewriter , where he is compulsively trying to check news websites despite using a typewriter. [A histogram of books finished over time. Spikes occur at certain points, with arrows marked "Icon Swap" pointing to the point before them.] [Caption below the panel:] I'm not saying I have a problem compulsively checking news and social media on my phone, but when I replace the social media app icon with my eBook reader, I read a half-dozen books before I get used to the change.

Unpopular Opinions

Unpopular Opinions

https://www.xkcd.com/2184

https://www.explainxkcd.com/wiki/index.php/2184:_Unpopular_Opinions

[Ponytail, Cueball, and Megan are all looking at their cell phones. Cueball is in the middle, facing out, holding his phone in both hands, while the two women face towards him with only one hand on their phones. Ponytail is tapping on the phone as shown by small lines over her fingers. they talk to each other, but before that, there is the following text above them:] Unpopular positive opinion challenge: Name a movie that... (1) you genuinely like (not "so bad it's good") (2) came out in your adult life post-2000, and (3) is rated below 50% on Rotten Tomatoes. Ponytail: Wow, this is harder than I thought. Cueball: ...Terminator Genisys? Megan: Seriously?! Cueball: I like time travel, OK?? [Caption below the panel:] When people talk about their "unpopular opinions" about movies, they usually mean hating something everyone likes, but liking something everyone hates is much harder.

Everybody has their own preferences as to what movies they like and dislike, and when your like or dislike of a movie seems to be different than the majority of people, you could call your preference the "unpopular opinion" because your opinion is the less prevalent one. This often takes the form of "I hate this movie and I don't understand why everybody else seems to like it", but this comic is talking about the opposite form, which it categorizes as less common, namely "I like this movie and don't understand why everybody else seems to hate it." The comic points out that it's relatively common to hate movies others appear to like, but the converse, in which you like a movie others seem to hate, is much harder to find. To illustrate how hard it is to like a movie everyone else seems to dislike, the comic presents a challenge whereby you 1) identify a movie you definitely like, which 2) came out during your adult life (so it isn't tainted by childhood nostalgia ), and which 3) the majority of other people don't like, as measured informally by having a popularity rating below 50% on the Rotten Tomatoes website (a website that aggregates reviews of films). Supposedly you will find it hard to find a movie that meets all three criteria. The rules prohibit a movie that the viewer finds "So Bad, It's Good" - the enjoyment of the movie must be genuine, for its positive qualities, rather than ironic enjoyment of its negative qualities. The image in this comic gives an example of this effect, namely the movie Terminator Genisys , the fifth in the Terminator series, released in 2015. This series, about time-travelling killer robots, included the highly rated Terminator 2 (93% on Rotten Tomatoes), while Terminator Genisys is only 26%. The title text refers to three movies in the Terminator franchise, Terminator 3: Rise of the Machines (2003), Terminator Salvation (2009), and Terminator: Dark Fate (due out later in 2019). The Terminator movie series has featured both time travel and trucks driving or attempting to drive into people, and Randall apparently finds himself drawn to such movies. He hopes that Dark Fate will be a good movie, but has low expectations, considering the less than stellar ratings of the last 3 movies (69%, 33%, and 26%). A Tomatoes search ordered by release date limited to qualifying movies can help individuals verify the difficulty of finding such movies for themselves. [Ponytail, Cueball, and Megan are all looking at their cell phones. Cueball is in the middle, facing out, holding his phone in both hands, while the two women face towards him with only one hand on their phones. Ponytail is tapping on the phone as shown by small lines over her fingers. they talk to each other, but before that, there is the following text above them:] Unpopular positive opinion challenge: Name a movie that... (1) you genuinely like (not "so bad it's good") (2) came out in your adult life post-2000, and (3) is rated below 50% on Rotten Tomatoes. Ponytail: Wow, this is harder than I thought. Cueball: ...Terminator Genisys? Megan: Seriously?! Cueball: I like time travel, OK?? [Caption below the panel:] When people talk about their "unpopular opinions" about movies, they usually mean hating something everyone likes, but liking something everyone hates is much harder.

Cumulonimbus

Cumulonimbus

https://www.xkcd.com/2185

https://www.explainxkcd.com/wiki/index.php/2185:_Cumulonimbus

[Drawing of a small cloud with with a label beneath:] Cumulus [Drawing of a medium sized tall hourglass shaped cloud with a label beneath:] Cumulonimbus [Drawing of a large cloud, larger at the top than at the bottom, with a label beneath:] Cumulonimbulonimbus [Drawing of a huge and very complicated cloud in three layers, with a label beneath:] Cumulonimbulonimbulocumulonimbus

This comic follows the naming of clouds. As with other lists (like in 2022: Sports Champions ), it starts off as normal but then gets more unusual until it is unrealistic. Cumulus The first panel shows a cumulus cloud , from the Latin for "heap". These are common clouds and are relatively small. Cumulus clouds form when warm (and thus rising) moist air condenses when it hits the dew point , the temperature at which relative humidity hits 100%. Cumulus clouds with sharp, defined borders are still growing. When they stop growing (because the rising moist air is exhausted), they get fuzzy and fluffy, and eventually dissolve. Cumulo nimbus The second panel shows a cumulonimbus cloud , from the Latin for "heaping raincloud", with the upper part about the same size as the lower part. Though somewhat like the cumulus cloud, it is more prone to causing rain and lightning. Cumulonimbus clouds, like cumulus clouds, grow vertically because of their moist warm air, but they have enough energy to reach the top of the troposphere , giving them the distinctive anvil shape shown in the comic and their tendency to produce nasty weather. Cumulo nimbulo nimbus The third panel shows an even bigger cloud and names it cumulonimbulonimbus (Latin for "heaping rainy raincloud"). Here the scientific facts end and the humor begins. The cloud has the upper part about twice as large as the lower part. The humor here comes from building up an even bigger name by adding another "nimbus" element for the cloud as its size increases, suggesting that its growth as compared to the second cloud shown has made it even more "rainy". Cumulo nimbulo nimbulo cumulo nimbus The fourth panel shows an absurdly large cloud with three major layers and gives it the name cumulonimbulonimbulocumulonimbus (Latin for "heaping rainy rainy heaping raincloud"). This is a combination of the third and second cloud names in this comic, and indeed the fourth cloud looks a lot like the second one emerging out of the top of the third. This cloud may look like a super soaker , ready to spray water on everyone, or perhaps a faucet ready to open and pour water down. Alto cumu lenticulo strato nimbulo cirrus lenticulo mamma noctilucent The title text takes this comic to its logical extreme by naming a new cloud that has the longest name of them all and is also supposedly the rarest. Its name can be translated as "mid-altitude, heaped, lense-shaped, layered, grey, rainy, wispy, breast-like and lit at night". It mentions a common joke in weather communities, making fun of the common trope that thunderstorms form when "warm moist air" meets "cold dry air," an extreme oversimplification. A complicated cloud needs complicated processes, so Randall adds in "cold slippery air," then cursed air and nanobots , which makes the cloud impossible since neither of those exist. [ citation needed ] The name of this cloud is a compound of the following cloud names: altocumulus : "heap up high"; these clouds are mid-altitude white patches. lenticular cloud , often shaped like a flying saucer. stratus : a layered cloud, effectively above-ground fog. nimbus : a grey cloud producing continuous rain. cirrus : a cloud that looks like thin, wispy strands. "lenticulo" gets repeated, perhaps indicating that there's a second disc in the cloud. mammatus : a breast-like cloud structure that forms at the bottom of some thunderstorm clouds, which signifies sinking air and is associated with severe storm activity and, in the central United States, tornado formation. noctilucent : a cloud-like structure formed from ice crystals, often formed after volcano eruptions and other cataclysmic events and illuminated by a just-set sun. The International Cloud Atlas defines the cloud types that are recognized by the WMO, the World Meteorological Organization . It was first published in 1896. Similarly, IUPAC publishes a manual that allows chemists to name chemical compounds in a consistent manner. The Altocumulenticulostratonimbulocirruslenticulomammanoctilucent may thus be a pun on IUPAC, which (theoretically) offers a unique name for each possible strand of DNA and other complex molecules (such as Titin ). Therefore, Randall might have seen a unique cloud that has never been observed before, but yet, thanks to IUPAC-like cloud naming rules, he came up with a "valid" name for his observation. [Drawing of a small cloud with with a label beneath:] Cumulus [Drawing of a medium sized tall hourglass shaped cloud with a label beneath:] Cumulonimbus [Drawing of a large cloud, larger at the top than at the bottom, with a label beneath:] Cumulonimbulonimbus [Drawing of a huge and very complicated cloud in three layers, with a label beneath:] Cumulonimbulonimbulocumulonimbus

Dark Matter

Dark Matter

https://www.xkcd.com/2186

https://www.explainxkcd.com/wiki/index.php/2186:_Dark_Matter

[Megan walks with Cueball. She is holding a hand out while telling Cueball something.] Megan: Dark matter density in the solar system is around 0.3 GeV/cm 3 Cueball: Is... that a lot? [As they continue to walk and talk she spreads her arms out.] Megan: In terms of mass, it means the Earth contains one squirrel worth of dark matter at any given time. Cueball: Wow. [In a frame-less panel Cueball stops while Megan walks past him. Megan is face-palming herself while looking down.] Cueball: Is there any way to find out which squirrel it is? Megan: No, it's not literally- [Cueball holds his hand with one finger up in front of Megan, while she has turned towards him and is holding both arms up, possible with balled fist, as she shouts back at him, shown both with large fat letters and with small lines emanating above her head.] Cueball: Oh, that explains why they weigh enough to set off those spinning bird feeders! Megan: Dark matter isn't squirrels!

Megan and Cueball are talking about dark matter , the mysterious invisible mass observed indirectly by the rate at which galaxies rotate. Megan states that dark matter's density in the solar system is 0.3 GeV/cm 3 , as claimed, for example, by Bovy and Tremaine (2012) "On the local dark matter density" in The Astrophysical Journal . Cueball does not understand what that means, so Megan explains that it equates to one squirrel's mass of dark matter in the volume of the Earth . In the final two panels, Cueball humorously misinterprets this as implying dark matter is actually one or more squirrels, and thereby provides the mass which causes squirrels to spin on bird feeders designed to deter them while birds, with lower mass, do not. This enrages Megan. The gigaelectronvolt (GeV) is a unit of energy that can be converted to a mass using Einstein's formula E = mc 2 . It is typically used for subatomic particles, such as weakly interacting massive particles (WIMPs), one of several contending possibilities for the still-open question of the composition of dark matter, and one which Megan's uniform density figure implies constitutes most of it. For example, the mass of a proton is 0.938 GeV/ c 2 . However, it is common to omit the c 2 denominator, representing masses as GeV or MeV. A mass represented as 0.3 GeV is equal to 5.35 × 10 −25 grams [1] . Since the Earth's volume is 1.083 × 10 27 cm 3 Megan's figures imply that a squirrel has a mass of about 1.3 lb (1.083 x 5.35 × 10 27−25 g = 580 g [2] ), a typical weight for several species of common squirrels. Squirrels are a recurring topic on xkcd, but are not a serious alternative to WIMPs as a scientific explanation for the composition of dark matter . Since the September 2015 detection by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and subsequent confirmation by the Virgo interferometer of gravitational waves from unexpectedly many merging black holes substantially more massive than those produced by stellar collapse, primordial black holes (PBHs) have become a popular alternative explanation to WIMPs (or squirrels), attracting proponents at NASA, and other cosmologists for several reasons. But PBHs remain controversial, because if they constituted more than a very small portion of dark matter, alternative explanations would be almost entirely excluded. Other alternative hypotheses for the observations suggesting dark matter, such as theories involving the gravitational force varying over different distances , often upset cosmologists as much as Megan is shown to be, because they violate the cosmological principle among other issues. Part of this frustration may be due to the fact that even after many decades of careful, tremendously expensive, and often stunningly beautiful experiments, none of the many explanations for dark matter or the observations suggesting it have as yet any support from direct empirical observations. To help resolve this mystery, the title text imagines using a spinning bird feeder like a particle accelerator , colliding squirrels at relativistic speeds as if they were subatomic particles, to detect dark matter particles like the CERN accelerator discovered the Higgs boson . (Note, however, that accelerating even one squirrel to relativistic velocities would destroy the feeder along with any nearby birds, not to mention the squirrels, and the surrounding city.) [Megan walks with Cueball. She is holding a hand out while telling Cueball something.] Megan: Dark matter density in the solar system is around 0.3 GeV/cm 3 Cueball: Is... that a lot? [As they continue to walk and talk she spreads her arms out.] Megan: In terms of mass, it means the Earth contains one squirrel worth of dark matter at any given time. Cueball: Wow. [In a frame-less panel Cueball stops while Megan walks past him. Megan is face-palming herself while looking down.] Cueball: Is there any way to find out which squirrel it is? Megan: No, it's not literally- [Cueball holds his hand with one finger up in front of Megan, while she has turned towards him and is holding both arms up, possible with balled fist, as she shouts back at him, shown both with large fat letters and with small lines emanating above her head.] Cueball: Oh, that explains why they weigh enough to set off those spinning bird feeders! Megan: Dark matter isn't squirrels!

Geologic Time

Geologic Time

https://www.xkcd.com/2187

https://www.explainxkcd.com/wiki/index.php/2187:_Geologic_Time

[Megan, arms spread out, is delivering a long-winded explanation to Hairbun and Cueball.] Megan: Imagine Earth's history as a football field, from the planet's formation at one end to today at the other. Megan: Complex life would be largely limited to the final ten yards. Dinosaurs appear at the five-yard line, the age of mammals happens in the last 1½ yards, and humans arise in the final few millimeters. Megan: All of written history would fit in a strip narrower than a single hair. Megan: "Two weeks" would be too small to see even with a powerful microscope. Hairbun: Mm hmm. [Caption below the panel:] Geologists always try this when they're late turning something in.

Analogies to explain the passage of billions of years are often used in popular science explanations, to help compress these huge spans of time into something the human mind can comprehend; the football field analogy is one such analogy. The Earth is approximately 4.54 billion years old ; if you were to present a timeline of Earth as long as a football field (100 yards or 91 meters), then each inch of that length would comprise more than 1.26 million years of Earth's history and each millimeter nearly 50,000 years. Megan , a geologist , tells a story about how small the timespan of human history is compared to Earth's total history. She does this to juxtapose it with normal human time-scales, to imply that her being two weeks late turning in her project is immaterial by the standards of the Earth's tremendous age. She tries to sell this story to Cueball and Hairbun , but Hairbun's response does not seem to bode well for Megan. Megan's delay of two weeks would map to about eight nanometers on the football field. The most powerful electron microscopes have a magnification of ten million, which would make it look like about eight centimeters (about three inches), so her statement about it being "too small to see even with a powerful microscope" is a bit of an exaggeration. The most powerful optical microscope has 6500x magnification,( New York Times, March 8, 2011 ) which would indeed be inadequate. Randall states in the caption that this is a trick that geologists always try to use when being late turning something in. In the title text, Hairbun and Cueball reply by turning Megan's own argument against her. They promise to pay her for her work in what could be considered a short amount of time on the geological scale - which could easily be many, many times longer than Megan's own lifespan. Megan, like all working people, wants to be paid in a timely manner for her work, and would be deeply dissatisfied to have her payment delayed for so long. Thus, Hairbun and Cueball's rebuttal proves a point: when other people require you be punctual, it's easy to dismiss them as just being impatient; when you're the one who needs other people to be punctual, it's not so easy to criticize yourself. The comparison with a football field is a typical, but doubtful practice to explain people what the size of an area is ( 1257: Monster ). Here it is used as an analogy with a one-dimensional timescale. [Megan, arms spread out, is delivering a long-winded explanation to Hairbun and Cueball.] Megan: Imagine Earth's history as a football field, from the planet's formation at one end to today at the other. Megan: Complex life would be largely limited to the final ten yards. Dinosaurs appear at the five-yard line, the age of mammals happens in the last 1½ yards, and humans arise in the final few millimeters. Megan: All of written history would fit in a strip narrower than a single hair. Megan: "Two weeks" would be too small to see even with a powerful microscope. Hairbun: Mm hmm. [Caption below the panel:] Geologists always try this when they're late turning something in.

E Scooters

E Scooters

https://www.xkcd.com/2188

https://www.explainxkcd.com/wiki/index.php/2188:_E_Scooters

[Cueball is getting off his e-scooter, with his bicycle helmet hanging on the handlebars. He has stopped right in front of White Hat who addresses him.] White Hat: Hey, you got one of those e-scooters! Cueball: Yeah! [Cueball is now standing next to the e-scooter holding on to the handlebars with one hand. Both he and White Hat look down at the scooter.] White Hat: So what do you think? I hear so much about these things. [A large panel with just White Hat who is spreading his arms out.] White Hat: Are they impractical and unsafe toys? Or a last-mile transit revolution? [Closeup on White Hat holding both arms out and up with palms held up.] White Hat: A low-carbon car replacement? Or Silicon Valley sidewalk clutter? [In a frame-less panel only Cueball and his e-scooter is shown.] Cueball: Well, having given it lots of thought, here is my opinion on scooters: [Cueball is bending at the knees and holding on to the handlebars with both hands as White Hat is looking at him. Cueball starts making machine noises.] Cueball: Zooooooom! Cueball: Neeeeeoooormm Cueball: Vrrrm Vrrmvrmm Cueball: Wheeee! [Cueball continues making sounds as in the previous panel. White Hat seems to have taken a step back.] Cueball: Pew pew pew! Cueball: Bzzzzt Kaboom! White Hat: Wait, why are there lasers? Cueball: Pew!

At the time of publishing, motorized scooters or e-scooters were very popular, especially with the rise of ride-share companies such as Lime and Bird that use apps allowing users to rent the scooters by the minute. ( Randall uses "e scooter" or "E Scooter" for the comic's title. But in the comic White Hat does say e-scooter, which is also the way the Wikipedia article on e-scooters mentions them.) Cueball drives up to White Hat on his e-scooter. White Hat asks him for his thoughts on the scooter; he is interested as he has heard so much about them. However, instead of just waiting to hear Cueball's response, White Hat then goes on to list four opinions he has heard other people say about e-scooters: When White Hat finally stops talking, Cueball tells him that he has given this a lot of thought and says he will give him his opinion on e-scooters. But instead of choosing an opinion from White Hat's list, or any logical opinion at all for that matter, Cueball starts making engine/vehicle sounds. This may indicate he doesn't care about any of White Hat's complicated opinions and is just excited about the fun of riding an e-scooter. In the last panel Cueball also makes "pew pew pew" sounds and other sounds from shooter-type video games, perhaps indicating that for him, riding a scooter is akin to the fun he gets from playing such video games. Some people consider e-scooters as a "low-carbon car replacement", as they are better for the environment than polluting gas cars (while others consider the resources used in their creation and their disposal a bigger threat). Additionally, e-scooters have been touted as a form of "last-mile transit" - used to cover the "last mile" to your destination after taking other forms of public transportation. However, others consider e-scooters a public nuisance, as users often leave them on the sidewalk haphazardly; hence the question about them being clutter. The comment about them being specifically "Silicon Valley" clutter is due to the expense, the city-infrastructure needed, and the high-tech nature of these devices. Many of the e-scooter companies are also from the Silicon Valley area. Scooters have also been seen as dangerous ("unsafe toys"), as many users do not wear helmets when riding e-scooters (though Cueball is seen with a helmet in the comic, although not wearing it) or ride them at high speed on sidewalks with many pedestrians. Some cities have gone so far as to ban e-scooters from their communities . Cueball's response of making onomatopoeic sounds which mimic the e-scooter is humorous for two reasons. First, e-scooters are fun and may seem futuristic, like something from his childhood. This would bring out a youthful and childish joy children have when making engine noises when playing with toy cars. He is acting like a kid because riding a scooter makes him feel like one. The second reason this is funny is that the scooters, being battery-powered, are nearly silent. He is making the sounds a traditional motorized scooter makes to fill in the audible gap. It is unclear why the scooter has lasers. Part of the joke is that there is no good or logical explanation for them. This forces the reader to come up with their own devious or honorable plan Cueball is executing. Not knowing why makes it more sinister and mysterious. The title text refers to Dean Kamen, an American inventor best known for founding the Segway company. At the time of the invention of the Segway, it was billed as a revolution in personal transit, with articles (and Kamen himself) speculating that future cities might be entirely rebuilt around it and similar personal transporters. That buzz quickly died down, and Segways became the subject of a great deal of mockery. The text implies that Kamen might resent the fact that a similar vision has re-emerged and is once again being taken seriously, but without his invention. However, Segway actually manufactures scooters for e-scooter rental agency Lime . [Cueball is getting off his e-scooter, with his bicycle helmet hanging on the handlebars. He has stopped right in front of White Hat who addresses him.] White Hat: Hey, you got one of those e-scooters! Cueball: Yeah! [Cueball is now standing next to the e-scooter holding on to the handlebars with one hand. Both he and White Hat look down at the scooter.] White Hat: So what do you think? I hear so much about these things. [A large panel with just White Hat who is spreading his arms out.] White Hat: Are they impractical and unsafe toys? Or a last-mile transit revolution? [Closeup on White Hat holding both arms out and up with palms held up.] White Hat: A low-carbon car replacement? Or Silicon Valley sidewalk clutter? [In a frame-less panel only Cueball and his e-scooter is shown.] Cueball: Well, having given it lots of thought, here is my opinion on scooters: [Cueball is bending at the knees and holding on to the handlebars with both hands as White Hat is looking at him. Cueball starts making machine noises.] Cueball: Zooooooom! Cueball: Neeeeeoooormm Cueball: Vrrrm Vrrmvrmm Cueball: Wheeee! [Cueball continues making sounds as in the previous panel. White Hat seems to have taken a step back.] Cueball: Pew pew pew! Cueball: Bzzzzt Kaboom! White Hat: Wait, why are there lasers? Cueball: Pew!

Old Game Worlds

Old Game Worlds

https://www.xkcd.com/2189

https://www.explainxkcd.com/wiki/index.php/2189:_Old_Game_Worlds

[A light gray drop down menu is shown with three sections split up with three grays lines split up with section titles in the same gray font. Beneath each section title is 3, 4 and 6 lines of black text. An white arrow cursor hovers over the second last option, which is thus highlighted with a dark gray background and white text.] New Games Subnautica Russian Subway Dogs Kerbal Space Program Old Games Worms Armageddon Elasto Mania Katamari Damacy Mario Kart Very Old Games Link's Awakening Escape Velocity SimCity Prince of Persia Super Mario Bros MS Flight Simulator 3 [A colorful scene is shown from the Super Mario Bros. side-scrolling game, the first level World 1-1. Mario with red hat and trousers is standing on the brown blocks beneath the blue sky. Another character in the game, Goomba, is standing in front of some green bushes. Above them is narration text:] Narrator: It feels weird that you can go into old games and the whole world is still there. Goomba: Mario? Mario: It'sa me! Goomba: What are you doing here? [Mario stands between an e-scooter, a dismounted and broken Question Mark Box lying on its side and a cellphone tower. Narration continues above:] Narrator: Part of me expects to find that everything's changed. [Mario looks at a damaged green but rusty Warp Pipe and there is a quadcopter drone flying by over his head. Weeds are growing both from the pipe and from the blocks he is walking on. Narration continues above:] Narrator: That pipes have rusted, walls have crumbled, bad guys have moved on. [Mario has moved on to World 1-4, the castle has been replaced with a bakery. The blocks beneath his feet are now smaller and gray and above them is black background. The character Toad with the white hat with red circles is standing in front of a bakery disc with shelves of bread and cake behind it. There is a green sign on the front of the brown disk. Toad talks to Mario with white text in the black background. Above the black part of the image is more narration in a frame-less white section:] Narrator: That even our game worlds can't escape the passage of time. Toad: Thank you, Mario! Toad: But this is a Panera now! Sign: Panera

Randall sits at his computer looking at a menu of games which have been ordered into three sections, New, Old and Very old games (see List of games below). At the bottom of this list, 2nd to last, he chooses to click on Super Mario Bros. which then opens as shown in the next four panels. This comic explores the difference between the real world, where artificial structures require constant upkeep and communities change with time, and the digital worlds of video games, where everything is static until the plot demands otherwise. Although online games do require server maintenance by the owners and sometimes receive major changes to their content, offline games are - and always have been - perpetual existences, unchanging so long as the data is intact. (This is later revisited in 2221: Emulation ) As the narration explores this incongruity, and theorizes about the idea of it not being so, the comic displays the alternative with the ubiquitous video game - Super Mario Bros. (1985) - as an example. Mario arrives in World 1-1 to find a Goomba expressing surprise that the plumber has deigned to return to the place where his first journey began. As he advances, he finds both signs of progress - a cellphone tower , an e-scooter , a drone - and signs of disrepair - damaged Warp Pipes , loose blocks. At World 1-4, he finds Toad ; in the game, Toad would warn him that the Princess is being held in another castle , but now, he's informing Mario that the castle has been remodeled into a Panera bakery. This reflects common experiences of a person returning to a place they once knew well, but haven't seen in a long time. The atmosphere of the place may be changed by modern elements that hadn't existed before. Buildings and other infrastructure may have decayed or fallen into disrepair. And areas that have not been neglected will often be redeveloped, meaning that landmarks you remember may be repurposed or demolished to make room for something new. This tends to stir up feelings of nostalgia and loss in real life, when the settings of your memory no longer exist in the form that you remember. The title-text abruptly switches to Mario's acceptance of the changes to World 1, and deciding to make the most of it by purchasing a cinnamon roll . "Coins" are the omnipresent currency of the Mushroom Kingdom and most other locations Mario visits in the Mario series, taking the form of large nondescript golden circles, usually with a rectangular indent in the middle. The concept of an old, dilapidated version of the world of the original Super Mario Bros. was explored by Nintendo themselves in the Mushroomy Kingdom stage featured in multiple Super Smash Bros. games. The first panel shows a list of games in approximately reverse chronological order of their release: The first game in the Mario Kart series was Super Mario Kart from 1992. As can be seen that Mario Kart game would be older than Link's Awakening. So it seems likely Randall was referring to Mario Kart 64 from 1997, the first in the series to begin with Mario Kart leaving out the Super. With this in mind all the games in the two bottom sections are older than all those in the previous section. But they are not listed chronologically within the three sections. Russian Subway Dogs is the newest game from 2018 (and at the time of this comic's release in August 2019, is the only one of the 13 games mentioned in this comic that does not currently have a Wikipedia entry). Super Mario Bros., the game most prominently featured in the comic, is the oldest of the 13. The first version of Microsoft Flight Simulator , MS flight simulator 1.0 , was from 1982, but the list this comic specifies the third version, released in 1988. Although the games in this comic appear to be grouped by date of their release, the time span covered by these groupings is not uniform. The first three games mentioned are from 2014-2018. The next four date from between 1997-2004, and the last six from between 1985-1996. With the earliest games grouped as 1985-1996, uniform grouping could split the later games between a group released in 1997-2008 and a group of games released in 2009 or later. If grouped by decades, 1985-1995 would potentially place the Escape Velocity game in the Old Games section instead of the Very Old Games section. Although some of these games did have releases intended to run on a 'Personal Computer' , the list in this comic seems to focus on games released for gaming consoles , with no mention of games released for first or second generation consoles which pre-dated the Nintendo Entertainment System (such as Pong published by Atari; Brain Wave, Haunted House, Interplanetary Voyage, & Wipeout for the Magnavox Odyssey ; & Adventure for the Atari 2600 ). [A light gray drop down menu is shown with three sections split up with three grays lines split up with section titles in the same gray font. Beneath each section title is 3, 4 and 6 lines of black text. An white arrow cursor hovers over the second last option, which is thus highlighted with a dark gray background and white text.] New Games Subnautica Russian Subway Dogs Kerbal Space Program Old Games Worms Armageddon Elasto Mania Katamari Damacy Mario Kart Very Old Games Link's Awakening Escape Velocity SimCity Prince of Persia Super Mario Bros MS Flight Simulator 3 [A colorful scene is shown from the Super Mario Bros. side-scrolling game, the first level World 1-1. Mario with red hat and trousers is standing on the brown blocks beneath the blue sky. Another character in the game, Goomba, is standing in front of some green bushes. Above them is narration text:] Narrator: It feels weird that you can go into old games and the whole world is still there. Goomba: Mario? Mario: It'sa me! Goomba: What are you doing here? [Mario stands between an e-scooter, a dismounted and broken Question Mark Box lying on its side and a cellphone tower. Narration continues above:] Narrator: Part of me expects to find that everything's changed. [Mario looks at a damaged green but rusty Warp Pipe and there is a quadcopter drone flying by over his head. Weeds are growing both from the pipe and from the blocks he is walking on. Narration continues above:] Narrator: That pipes have rusted, walls have crumbled, bad guys have moved on. [Mario has moved on to World 1-4, the castle has been replaced with a bakery. The blocks beneath his feet are now smaller and gray and above them is black background. The character Toad with the white hat with red circles is standing in front of a bakery disc with shelves of bread and cake behind it. There is a green sign on the front of the brown disk. Toad talks to Mario with white text in the black background. Above the black part of the image is more narration in a frame-less white section:] Narrator: That even our game worlds can't escape the passage of time. Toad: Thank you, Mario! Toad: But this is a Panera now! Sign: Panera

Serena Versus the Drones

Serena Versus the Drones

https://www.xkcd.com/2190

https://www.explainxkcd.com/wiki/index.php/2190:_Serena_Versus_the_Drones

[A panel at the top of the comic has a quote and to the right of the quote is a picture of Randall's new book. It is black with large blue text and smaller white text. On the book cover, in white drawings, are seen Megan with a ladder and either Black or White Hat (hard to say on black background). Both are looking up on Cueball who is floating in the air with a quadcopter drone beneath either leg, trying to plug in an electric light bulb in a naked lamp hanging down near him. It seems he has already removed the broken light bulb, as he has one in both hands. And now he tries to put in the new one. The blue text stating title and author can be read.] "It's a pretty bad idea." —Serena Williams on my idea Book: How To Book: Randall Munroe [Caption below this panel above another set of panel:] Which types of sports equipment would be most effective at bringing down a rogue photography drone? My new book features a real-world test by Serena Williams. [A large panel shows Serena Williams, with curly hair and a very large ponytail, swinging her tennis racket to smash a tennis ball towards, and hitting, a quadcopter drone flying towards her. As the ball hits a small explosion seems to happen with the drone which is stopped in mid air. Above the drone are two other drones flying towards her, with one more below. There is a broken drone on the ground in front of her. Three tennis balls lie behind her.] [Three smaller panels are beneath the large panel. The first panel is smaller than the other two and a bit higher up than they are and is overlaying the second panel. It shows Serena jumping with the racket held high. No drones are shown, but her shadow can be seen beneath her.] [In the next panel she is seen smashing her racket into one of the drones, breaking a rotor off, she is still hanging in the air, her shadow beneath her and her legs partly behind the previous panel, which is covering most of the left part of this panel. Another drone is flying above her.] [In the final panel she is seen standing again, turning around facing the other way, taking another swing at two drones that try to evade her. The ground is now filled with debris from several smashed drones.] [Caption beneath the panels, with the "here" in link blue color... The entire image is a link, so no need to click on the here though.] To read an excerpt about Serena's drone battle, click here or go to blog.xkcd.com

Another comic which is a promotion of Randall's up coming book How To , to be released less than 3 weeks after this comic's release, on September 3, 2019. And this time permanent - as opposed to Disappearing Sunday Update from about two weeks before. It stars Serena Williams , an American professional tennis player and former world No. 1. Most book advertisements feature laudatory quotes from famous people or reviewers, but here, Serena Williams is quoted as saying "It's a pretty bad idea" about Randall's idea of her attacking drones as given by the title of the comic. That idea is one of the chapters in the book and Serena Williams actually agreed to go and shoot tennis balls after an old drone with a broken camera. This can be read in the Blag post that is linked at the bottom of the comic: Serena Versus the Drones . Unlike other books, "It's a pretty bad idea" is a pretty good quote for his "How To" book given that many of Randall's humorous explorations of scientific methods of doing usual and unusual things are pretty bad ideas. As usual with Randall there is no need to click on the link, as the entire image is a link to the blog post. This was mentioned in 1572: xkcd Survey , and even earlier in the banner for his book tour for the what if? book. The title text says that Serena Williams said that if she wanted to defend herself against drones and if she had to use sports equipment, she would use a tennis racket and ball. Notably, according to the Blag post, this would be ineffective compared to throwing. [A panel at the top of the comic has a quote and to the right of the quote is a picture of Randall's new book. It is black with large blue text and smaller white text. On the book cover, in white drawings, are seen Megan with a ladder and either Black or White Hat (hard to say on black background). Both are looking up on Cueball who is floating in the air with a quadcopter drone beneath either leg, trying to plug in an electric light bulb in a naked lamp hanging down near him. It seems he has already removed the broken light bulb, as he has one in both hands. And now he tries to put in the new one. The blue text stating title and author can be read.] "It's a pretty bad idea." —Serena Williams on my idea Book: How To Book: Randall Munroe [Caption below this panel above another set of panel:] Which types of sports equipment would be most effective at bringing down a rogue photography drone? My new book features a real-world test by Serena Williams. [A large panel shows Serena Williams, with curly hair and a very large ponytail, swinging her tennis racket to smash a tennis ball towards, and hitting, a quadcopter drone flying towards her. As the ball hits a small explosion seems to happen with the drone which is stopped in mid air. Above the drone are two other drones flying towards her, with one more below. There is a broken drone on the ground in front of her. Three tennis balls lie behind her.] [Three smaller panels are beneath the large panel. The first panel is smaller than the other two and a bit higher up than they are and is overlaying the second panel. It shows Serena jumping with the racket held high. No drones are shown, but her shadow can be seen beneath her.] [In the next panel she is seen smashing her racket into one of the drones, breaking a rotor off, she is still hanging in the air, her shadow beneath her and her legs partly behind the previous panel, which is covering most of the left part of this panel. Another drone is flying above her.] [In the final panel she is seen standing again, turning around facing the other way, taking another swing at two drones that try to evade her. The ground is now filled with debris from several smashed drones.] [Caption beneath the panels, with the "here" in link blue color... The entire image is a link, so no need to click on the here though.] To read an excerpt about Serena's drone battle, click here or go to blog.xkcd.com

Conference Question

Conference Question

https://www.xkcd.com/2191

https://www.explainxkcd.com/wiki/index.php/2191:_Conference_Question

[Hairy stands on a podium having just addressed a crowd of seated people. Beret Guy stands in the middle of the crowd, addressing Hairy. One of Beret Guy's hands is raised at chest height. The front row consists of Cueball, Ponytail, another Hairy, Megan, Hairbun, Danish and another Cueball.] Beret Guy: I have a question. Beret Guy: Well, less of a question and more of a comment. Beret Guy: I guess it's less of a comment and more of an utterance. Beret Guy: Really it's less an utterance more an air pressure wave. Beret Guy: It's less an air pressure wave and more a friendly hand wave. Beret Guy: I guess it's less a friendly wave than it is a friendly bug. Beret Guy: I found this bug and now we're friends. Do you want to meet it?

Usually, at a conference or other event involving a speaker addressing a crowd, members of the crowd are given the chance to ask questions. This is intended so that people can perhaps ask the speaker to elaborate on a point they've made, or to ask the speaker's opinion on a topic related to their talk. Occasionally, people at such an event will use (or, rather, abuse) the opportunity to ask a question to instead provide their own (unsolicited) opinion or statement. Such statements are often preceded with something along the lines of "I have a question. Well, less of a question and more of a comment." This formulation in particular has attracted a lot of criticism for not adding anything to the discussion and for pulling focus away from the speaker. In the comic, this idea is taken to an extreme, with Beret Guy not only transforming the opportunity to ask a question into an opportunity to make a statement through successive rephrasing, turning this into an opportunity to show off a bug he has found. This is accomplished by using a multitude of synonyms in a continuum of relatable word pairs, except near the last: "question" and "comment" are similar, as are "comment" and "utterance", but the extremes, the difference between the first and the last in the entire set (in this case "question" and "friendly bug") is profound. In a way, this segue is meant to be similar to how, in the lines of a color spectrum, red fades into yellow: gradually, and with no abrupt transitions in color ( YMMV : CGA versus 4K ). Question. A question is what the crowd member is expected to provide, such that the speaker or a panel member could provide a related answer. Comment. A comment by a crowd member, is when they just say something they believe, without expecting an answer, giving the speaker or panel members nothing to do. This may be seen as annoying by everyone else, as the crowd did not come to hear the opinion of other crowd members. But answers to relevant questions would be interesting to the crowd and the panel. Utterance. An utterance is just making a noise, which may or may not be actual words, or if actual words it may not be a complete sentence. Air Pressure Wave. Sounds are literally pressure waves in the air. So this could be a simple sound, or not a sound at all depending on the severity of the wave. It might be the person simply blowing. Friendly Hand Wave. Now instead of using his mouth to generate an air pressure wave, he's producing it with his hand, in a manner intended to be interpreted as "friendly". Many times hand waves are done in a friendly manner, designed more for the visual appeal than the amount of air pressure waves they generate. Friendly Bug. Now he is no longer doing anything himself, except to point out the fact that he has found a bug or insect , which he anthropomorphizes as being friendly. Want to meet it? He has decided that he and the friendly bug are actual friends and ironically comes full circle by finally asking a question, though presumably whether the speaker wants to meet a bug is not related to the topic of the speaker's talk. The title text takes the opposite route of Beret Guy, and each step instead refers to successively worse forms of magic spells that would, presumably, have a negative effect upon the listener. Starting from a mere utterance and then using Beret Guy's "it is less than" scheme, it progresses over worse and worse curses, ending with an unforgivable curse! Utterance. It begins with "utterance", which was also used by Beret Guy. See above. Incantation. Incantation , or a spell, is a magical formula intended to trigger a magical effect on a person or objects. It is not necessarily with evil intent. Malediction. A malediction is another word for curse (the prefix "mal" being a Latin root meaning "evil"). This is always with evil intent. Word of Power. "Word of Power" could refer to the dragonish form of magic in The Elder Scrolls V: Skyrim , or the early 1st edition Dungeons & Dragons high level spells . Unforgivable Curse. The term " Unforgivable Curse " refers to a set of three spells from the Harry Potter series, said to be so evil that their use on another person is unforgivable and illegal. The three spells are able to mind control ( Imperius ), torture ( Cruciatus ), and kill ( Avada Kedavra ) their target. It is unclear which spell is implied, though if it was accurate to call it a singular word of power, it is unlikely to be the killing curse. The title text can be interpreted as a reply by Hairy (the speaker) to Beret Guy, indicating his annoyance at the topic being derailed. It could also be representative of Randall's feelings towards those who abuse the opportunity to ask a question in order to make a statement. Randall has recently done some book tours and was at San Diego Comic-Con last month where he served on various panels, so he probably has had personal first-hand experience with these kinds of circuitous non-questions. [Hairy stands on a podium having just addressed a crowd of seated people. Beret Guy stands in the middle of the crowd, addressing Hairy. One of Beret Guy's hands is raised at chest height. The front row consists of Cueball, Ponytail, another Hairy, Megan, Hairbun, Danish and another Cueball.] Beret Guy: I have a question. Beret Guy: Well, less of a question and more of a comment. Beret Guy: I guess it's less of a comment and more of an utterance. Beret Guy: Really it's less an utterance more an air pressure wave. Beret Guy: It's less an air pressure wave and more a friendly hand wave. Beret Guy: I guess it's less a friendly wave than it is a friendly bug. Beret Guy: I found this bug and now we're friends. Do you want to meet it?

Review

Review

https://www.xkcd.com/2192

https://www.explainxkcd.com/wiki/index.php/2192:_Review

[A profile picture of Cueball in a small frame is next to five solid yellow stars. Below this is a review:] ★★★★★ Great graphics, huge world [Caption below the comic:] My overall review of Earth

This comic is a five of five star review of planet Earth , by Randall , depicted as Cueball in his profile picture. The review is written as a video game review, praising the size and realism of the world. The comic's humor draws from the fact that Earth is a completely real object and shouldn't be rated on the same lines as a video game, and the fact that there's no place that the Earth can be reviewed (with the possible exception of The Hitchhiker's Guide to the Galaxy ). The "huge world" remark is a play on Open world games like Minecraft , which are praised when their size allows hundreds of hours of exploration; exploring Earth would allow more than a lifetime of novelties. The title text states that the 'controls are hard to figure out', possibly alluding to the fact that it takes a lot of time to learn how to walk and talk, a rather basic thing in most video games, or to the fact that it is in general hard to navigate around in one's life, as has been the subject of many comics. Earth (or humans and other life forms on Earth) has many problems at the moment, such as climate change , overpopulation , gun violence , sexual violence , censorship , poverty , and increasing depression , to name just a few. However, this comic also serves as a reminder that, overall, the world is a five-star world. It reminds us to look around: there's so much world to explore! And also that it is worth preserving for future generation to play around on. It is not a game that grows outdated and will be replaced by a new and better version next year... While there aren't any games that can recreate the detail that reality has (Due to the computing power required to do such a thing would be on an intergalactic level to recreate earth 1 to 1 in a simulation), there are some games that can either attempt to have a map that is similar in area, the graphic levels become close to reality, or difficult game-play/hard to learn controls. Examples of such games that attempt these things would be: Minecraft, No Man's Sky , The Elder Scrolls V: Skyrim , Grand Theft Auto V , The Legend of Zelda: Breath of the Wild , The Witcher 3: Wild Hunt , QWOP , Getting Over It with Bennett Foddy , and any of the Souls (series) , which includes Demon's Souls , Dark Souls , Dark Souls II , and Dark Souls III . Some people like to include games like Bloodborne , Sekiro: Shadows Die Twice , and Elden Ring into the same series as the Souls series due to similarity's to those games, and because they were developed by the same company. [A profile picture of Cueball in a small frame is next to five solid yellow stars. Below this is a review:] ★★★★★ Great graphics, huge world [Caption below the comic:] My overall review of Earth

Well-Ordering Principle

Well-Ordering Principle

https://www.xkcd.com/2193

https://www.explainxkcd.com/wiki/index.php/2193:_Well-Ordering_Principle

[Megan rubs a lamp held in her hands. A genie appears from the end of the lamp. The genie resembles the top half of Cueball's body, with a head, torso, and crossed arms, but with a squiggle representing a puff of smoke in place of his legs.] Genie: Greetings, mortal. You have freed me. I will grant you one wish. Megan: Hmm. [Megan holding the lamp to her side. The genie is off-panel.] Megan: It's been over 30 years since Back to the Future came out. Since then, probably hundreds of thousands of people have tried to dress as Marty McFly for Halloween. Genie: OK, and? [Megan, holding the lamp to her side, talking to the genie, who is floating in the air.] Megan: Of those people, one of them must have done the worst job. Megan: My wish is to see their costume. [Megan still holding the lamp and talking to the genie. The genie is exasperated, and has his hands raised.] Genie: Not a billion dollars? Flight? Infinite wishes? Megan: These wish things are always traps. Megan: Just show me the worst McFly and we'll call it even.

In the comic, Megan has found a genie lamp. A genie (or Jinn ) in a lamp is a supernatural, immortal being from many fairy tales, the most well known that from Aladdin , who grants one or more wishes to the person who frees it, such as by polishing or opening the lamp. Instead of wishing for multiple wishes, flight, money, or other "traditional" wishes, Megan instead wishes to see the worst Marty McFly Halloween costume. Marty McFly , played by actor Michael J. Fox , is a main character of the science fiction film about time travel Back to the Future , which was released, we are reminded , over thirty years ago, starting a series of sequels. The films are popular, so many people dress up as McFly or Doc Brown, the other main character, on Halloween , a holiday on October 31 when it is traditional in the USA to wear different costumes . McFly's outfit in the original film consists of little more than an orange vest, jean jacket, checkered shirt, jeans, and sneakers. It would seem difficult to get this wrong. In the final panel, the genie questions why she would wish for something so mundane, when he has the power to grant wishes beyond her wildest dreams. Megan, being savvy of tropes, used in fiction since biblical times, points out that encounters with wish-granting entities often turn out to be traps. Genies in fiction will often interpret wishes in ways the wisher did not intend, and particularly mean-spirited ones will twist a mortal's desire into their own personal hell . Even when the wish-granting entity isn't malicious, they're often portrayed as carrying unintended consequences, such that extremely consequential wishes become extremely dangerous. So Megan tries to play it safe by wishing for something innocuous and with little room for harmful side-effects. Unfortunately, Megan appears to have forgotten the overarching trope: all wishes can be twisted against the wisher. The genie may also be reluctant to fulfill the wish due to the insurmountable practical difficulties of fulfilling such subjective, ill-defined request. The well-ordering principle is a mathematical fact stating that every non-empty set of positive integers contains a least element. This principle would apply to Megan's request if there was guaranteed to be an absolute worst costume of Marty McFly. However, subjective preference , while reflexive and transitive , is not well-founded (or symmetric or necessarily antisymmetric or (semi-)connex for that matter) and is therefore considered to be a preorder , also called a quasiorder. This means that the genie may not be able to fulfill Megan's wish if the selection is based on the preferences of any one person. For example, the genie may have no opinion on the quality of any McFly costume, or might judge them on criteria completely different from Megan's. Her own criteria might apply to some pairs of costumes but not others, leading to ambiguity as to which is the worst, and no way to say whether any of the candidate possibilities are as bad as the others. While Megan isn't explicitly wishing for a common or widely-shared opinion , the title text contemplates organizing a "nationwide" search. People's preferences can be combined, such as with a mean opinion score which, while not strictly well-ordered, is usually able to identify a single worst costume, or at least a set of costumes tied for worst place according to aggregate subjective preferences. There are many other ways to combine preferences (e.g. voting) but none of them meet all of the criteria considered desirable, as demonstrated by Arrow's impossibility theorem . There is no way to exclude the possibility that even an omniscient and omnipotent genie might be technically unable to fulfill the wish, at least without, for example, changing one or more persons' preferences or modifying the space-time continuum to retroactively change the quality of some costumes of the past. The genie could fulfill the wish by showing Megan every McFly costume ever worn, which would necessarily show her the worst by any possible definition, but could be the trap she was hoping to avoid because viewing all the "hundreds of thousands" would take an inordinately long time. The title text may explain why Megan is interested in this wish: any means available to her would be restricted to a geographic area's (nationwide) photographs or drawings from memory. It is likely the worst costume was either never photographed, or isn't remembered accurately by those who saw it (it is "lost to time" -- which usually is just a figure of speech, but may actually be literally true in this case given the Back to the Future series' central theme of time travel). By asking the genie to show her, she might be able to see the truly worst costume without being restricted to only those for which evidence remains. Such a wish fulfillment might even require actual time travel to the time and location where the costume existed. The title text can also be interpreted as Randall's wish to know about the worst costume. So this is not Megan but Randall who has the wish to see this costume. The best we can do today is to look through all the available photos of McFly costumes. But even if one of those could be agreed upon to be the worst, there is no guarantee that there is not even worse versions that is not documented for posterity. In this interpretation, what Randall really would like is to use a dangerous genie wish to get around these difficulties. An additional, subtle pun plays on the word "well". In European folklore, water wells are often associated with spirits which may grant wishes, similar to genies. Thus, Megan's explanation of why she made a simple request of the genie is a statement of her "well-ordering principle"; her principle for ordering wishes from wells. (See also the Well series ). [Megan rubs a lamp held in her hands. A genie appears from the end of the lamp. The genie resembles the top half of Cueball's body, with a head, torso, and crossed arms, but with a squiggle representing a puff of smoke in place of his legs.] Genie: Greetings, mortal. You have freed me. I will grant you one wish. Megan: Hmm. [Megan holding the lamp to her side. The genie is off-panel.] Megan: It's been over 30 years since Back to the Future came out. Since then, probably hundreds of thousands of people have tried to dress as Marty McFly for Halloween. Genie: OK, and? [Megan, holding the lamp to her side, talking to the genie, who is floating in the air.] Megan: Of those people, one of them must have done the worst job. Megan: My wish is to see their costume. [Megan still holding the lamp and talking to the genie. The genie is exasperated, and has his hands raised.] Genie: Not a billion dollars? Flight? Infinite wishes? Megan: These wish things are always traps. Megan: Just show me the worst McFly and we'll call it even.

How to Send a File

How to Send a File

https://www.xkcd.com/2194

https://www.explainxkcd.com/wiki/index.php/2194:_How_to_Send_a_File

[Randall, depicted as Cueball, stands with his arms spread out] Randall: It feels weird that it's 2019 and yet I still sometimes find that the easiest way to move a file around is to email it to myself. [Randall has raised a hand to his chin,] Randall: If only there were a better way... [A picture of Randall's new book is shown to the left of the text. The book is black with large blue text and smaller white text. On the book cover, in white drawings, are seen Megan with a ladder and White Hat. Both are looking up on Cueball who is floating in the air with a quadcopter drone beneath either leg, trying to plug in an electric light bulb in a naked lamp hanging down near him. It seems he has already removed the broken light bulb, as he has one in both hands. And now he tries to put in the new one. The blue text stating title and author can be read but not the white trext. The "blog.xkcd.com" link is in link blue color.] Book: How To Book: Randall Munroe My new book How To is out next week! If you want to learn how to send data, you can visit blog.xkcd.com for a sneak preview of Chapter 19: How to Send a File [Beneath a heading are three pictures next to each other of a laptop computer. The first picture shows a regular laptop computer, with a labeled arrow pointing to the lower half of the computer. The second picture shows the laptop in a lighter outline, with scissors instructing to cut horizontally on a dotted line across the middle of the laptop. The third picture shows a laptop in two pieces cut over between the screen and the rest. There is a very jagged edge on both parts, which has been moved away from each other.] Exclusive advice from How To: When sending a file, it helps to know which part of your device the file is stored in. Label: Files are usually in this part

Similar to 2190: Serena Versus the Drones , this is another teaser ad for Randall's new (at the time the comic came out) book, How To , due to be released a week from this comic's release, on September 3, 2019. This also prompted a change to the xkcd Header text . The comic shows an image from of one of the chapters, and containing being a link to a larger piece of that chapter, or perhaps the entire chapter. This comic discusses transferring files, previously discussed in 949: File Transfer and in what if 31 . The snippet from his book that is shown in this comic shows scissors cutting off the (top) screen of a laptop, presumably as a way to give the "bottom" portion to someone for file transfer. This is probably not a good idea. [ citation needed ] The chapter linked to shows other methods of getting your files to another person and, in fact, explicitly states that breaking a computer to send files is not a good idea. The title text hints at other amazing content in the upcoming book, including discussion of butterfly migration (does it cause predictable tornadoes in Kansas? Can they carry coconuts to England?). It also threats that using the books idea for file transfer will make sure you will never see those files again, i.e. they will be lost for good if you try the book's method at home. The chapter preview, that the comic links to, discusses using butterflies as a method of sending files from one person to another on the form of flash media attached to butterflies, or encoded in DNA, and goes pretty in depth into these particular methods of data transmission as opposed to the more traditional methods that are detailed in traditional computer science books. [Randall, depicted as Cueball, stands with his arms spread out] Randall: It feels weird that it's 2019 and yet I still sometimes find that the easiest way to move a file around is to email it to myself. [Randall has raised a hand to his chin,] Randall: If only there were a better way... [A picture of Randall's new book is shown to the left of the text. The book is black with large blue text and smaller white text. On the book cover, in white drawings, are seen Megan with a ladder and White Hat. Both are looking up on Cueball who is floating in the air with a quadcopter drone beneath either leg, trying to plug in an electric light bulb in a naked lamp hanging down near him. It seems he has already removed the broken light bulb, as he has one in both hands. And now he tries to put in the new one. The blue text stating title and author can be read but not the white trext. The "blog.xkcd.com" link is in link blue color.] Book: How To Book: Randall Munroe My new book How To is out next week! If you want to learn how to send data, you can visit blog.xkcd.com for a sneak preview of Chapter 19: How to Send a File [Beneath a heading are three pictures next to each other of a laptop computer. The first picture shows a regular laptop computer, with a labeled arrow pointing to the lower half of the computer. The second picture shows the laptop in a lighter outline, with scissors instructing to cut horizontally on a dotted line across the middle of the laptop. The third picture shows a laptop in two pieces cut over between the screen and the rest. There is a very jagged edge on both parts, which has been moved away from each other.] Exclusive advice from How To: When sending a file, it helps to know which part of your device the file is stored in. Label: Files are usually in this part

Dockless Roombas

Dockless Roombas

https://www.xkcd.com/2195

https://www.explainxkcd.com/wiki/index.php/2195:_Dockless_Roombas

[Cueball and Megan walk in from the right and sees two Roombas on the ground in front of them.] Cueball: Are those... Roombas? Megan: Yeah, the dockless rental apps have really taken off. [Cueball stops and turns to look at Megan, who has also stopped, as Beret Guy comes walking in from the left with his smartphone in his hand.] Cueball: What? [As Cueball and Megan turn to look at Beret Guy, he stops between the two Roombas, looking down at the Roomba to his left. He taps his smartphone and the Roomba makes a sound.] Smartphone: Tap tap Roomba: Unlock [Beret Guy is squatting down on the Roomba as it drives him away, while Cueball and Megan turns to stare after him,] Roomba: Whirrrr

In this comic Cueball discovers two Roombas outside, and Megan explains that they are dockless Roombas for rent. Cueball is confused, but then Beret Guy walks in, activates one with an app on his smartphone , and rides away standing on it. A Roomba is a small automated (robotic) vacuum cleaner designed to clean a room or other bounded area by repeatedly and automatically going over the floor, vacuuming, until it has made multiple passes, and either runs low on power or is turned off. The "intelligence" of various models can vary from relatively random operation with basic techniques to get around obstacles, to models that generate a general mental map of the area and contents and attempt to be deliberate in passing over all reachable areas. A Roomba generally includes a recharging "dock", which it can find and automatically connect with when it gets low on power, allowing it to recharge and perhaps automatically begin another round of cleaning. Roombas are a recurring theme on xkcd. In 1193: Externalities it was Ponytail that drove a Roomba. And in 1486: Vacuum Beret Guy flew on a regular vacuum cleaner. A dockless scooter is a system of sharing personal scooters whereby they can be left anywhere for someone else to use, rather than returned to a particular home location. They are typically activated via a smartphone app. The term "dockless" in the name refers to the fact they have no predefined home, or place to dock. Like a Roomba, they do need recharging, but no special station is needed for that -- anyone can pick them up and recharge them overnight from a standard power outlet, receiving a fee from the scooter company for this service. In the past several years they have become popular in many large cities around the world. Scooters have recently been featured in 2188: E Scooters . The humor here is replacing the scooters with Roombas, which people would then ride. There are multiple problems with this idea: The title text refers to the controversy in many cities surrounding dockless scooters, which can be dangerous to pedestrians when in use and can block sidewalks and driveways when not. Dockless scooters were introduced in many cities before there were any regulations about scooter use, with some critics claiming scooters exploited loopholes in existing law and regulation, and leading some cities to pass legislation to specifically ban or curtail the use of dockless scooters. Here it is the Roombas that exploit loopholes in those scooter laws, which initially bothers city officials before they realize the positive benefit of the Roombas cleaning their streets as they are ridden. [Cueball and Megan walk in from the right and sees two Roombas on the ground in front of them.] Cueball: Are those... Roombas? Megan: Yeah, the dockless rental apps have really taken off. [Cueball stops and turns to look at Megan, who has also stopped, as Beret Guy comes walking in from the left with his smartphone in his hand.] Cueball: What? [As Cueball and Megan turn to look at Beret Guy, he stops between the two Roombas, looking down at the Roomba to his left. He taps his smartphone and the Roomba makes a sound.] Smartphone: Tap tap Roomba: Unlock [Beret Guy is squatting down on the Roomba as it drives him away, while Cueball and Megan turns to stare after him,] Roomba: Whirrrr

Nice To E-Meet You

Nice To E-Meet You

https://www.xkcd.com/2196

https://www.explainxkcd.com/wiki/index.php/2196:_Nice_To_E-Meet_You

[Cueball is sitting at his desk on an office chair, while typing at his laptop. The line he is writing on the computer is shown with white text in a black box up at the top of the panel while his thoughts shown in a thought bubble with small bubbles going to it from his head.] Text: Nice to meet you! Cueball [thinking]: That sounds weird; we’re not actually meeting in person. Laptop: Type type Laptop: Delete delete [Same setting:] Text: Nice to e-meet you! Cueball [thinking]: What is this, a 1995 cyberpunk novel? Laptop: Type type Laptop: Delete [Cueball stops typing and leans back resting an arm on the back of the chair while looking at laptop, no black box shown.] Cueball [thinking]: OK. Cueball [thinking]: Chill. Cueball [thinking]: Just be normal. [Cueball resumes typing a much longer text in two black boxes, one large with five lines of text, and a small below with one line.] Text: It’s weird to think that the words I’m typing will be projected onto your retinas. It’s like my hands are touching your eyes. Text: Anyway, hi. Cueball [thinking]: Nailed it. Laptop: Type type

In this comic, Cueball is considering how to greet someone online. At first, Cueball considers simply saying "Nice to meet you!", a typical greeting used when meeting someone in person. However, he notes that since the introduction is taking place electronically, saying that he is actually "meeting" them is inaccurate; he duly discards the greeting. Next he considers replacing the word "meet" with "e-meet." The use of " e- " as a prefix for anything related to electronics was a popular naming trend in the early 1990s, such as eWorld , eBay , and as a standardized shorthand for electronic mail . Earlier cyberpunk novels, such as 1984's Neuromancer , did not use the "e-" prefix, as they were written before that linguistic trend, while the prefix generally fell out of fashion by the 2000s. Cueball using the phrase "e-meet" thus sounds anachronistic to the 1990s, and he recognizes it, discarding his greeting again. He then decides that he needs to throw off the shackles of normal conversation and simply "be normal." Being a geek, Cueball therefore writes up a long-winded exposition of how strange electronic communication actually is in terms of the photons being projected by the computer screen, comparing it to his hands touching the receiver's eyes, then concludes the greeting with a simple "Anyway, hi." This might be off-putting to a friend that Cueball had just now met. This makes it funnier that Cueball believes he just "nailed" his greeting; he clearly has no idea what he is doing. The title text continues the theme of "his hands touching the receiver's eyes"; Randall is talking about how as a construct that your mind makes, he is now "inside your head"-- and taking it that statement to its logical conclusion, he "wants to get out." The comic discusses how adhering to conversational convention during social interactions can be quite difficult, especially with the advent of new technology. Social awkwardness is a recurring theme in xkcd. Advice has been written regarding the topic of whether to use "Nice to (e-)meet you" and possible alternatives, e.g. by Forbes , Huffington Post and Grammarly . The consensus seems to be that "Nice to meet you" is fine, though a bit cliche. [Cueball is sitting at his desk on an office chair, while typing at his laptop. The line he is writing on the computer is shown with white text in a black box up at the top of the panel while his thoughts shown in a thought bubble with small bubbles going to it from his head.] Text: Nice to meet you! Cueball [thinking]: That sounds weird; we’re not actually meeting in person. Laptop: Type type Laptop: Delete delete [Same setting:] Text: Nice to e-meet you! Cueball [thinking]: What is this, a 1995 cyberpunk novel? Laptop: Type type Laptop: Delete [Cueball stops typing and leans back resting an arm on the back of the chair while looking at laptop, no black box shown.] Cueball [thinking]: OK. Cueball [thinking]: Chill. Cueball [thinking]: Just be normal. [Cueball resumes typing a much longer text in two black boxes, one large with five lines of text, and a small below with one line.] Text: It’s weird to think that the words I’m typing will be projected onto your retinas. It’s like my hands are touching your eyes. Text: Anyway, hi. Cueball [thinking]: Nailed it. Laptop: Type type

Game Show

Game Show

https://www.xkcd.com/2197

https://www.explainxkcd.com/wiki/index.php/2197:_Game_Show

[Cueball, Black Hat, and Megan are game show contestants standing behind lecterns with Hairy standing in front of them as the game show host. Black Hat, standing in the middle of the three, is holding a finger up while speaking.] Black Hat: A boat. A plane. Amelia Earhart's plane. Amelia Earhart's skeleton . The Statue of Liberty's internal support frame. The Crown Jewels. This show's entire television audience. The Greenland ice sheet. Earth's north magnetic pole. Black Hat: Am I in the Pacific Ocean? Black Hat: If so, the Atlantic Ocean. Hairy: Uhh. Hairy: Our producers are going to need some time on this one. [Caption below the panel:] The game show realized that they should have added some restrictions to their "take any item to a deserted island" challenge, but it was too late.

Many shows have situations where the participants are asked hypothetical questions. A common hypothetical question asked to ascertain what someone considers most important to them is the one item they would take to a deserted island -- to make the best of a boring situation. Black Hat is on such a game show, and he does his best to undermine the intent of the question. Instead of answering with a favorite item -- such as his favorite album or book -- he lists various things (see below ), which he doesn't own and apparently expects the show's producers to provide him, starting with somewhat reasonable means of escape (e.g., a plane) to increasingly absurd items that appear to be chosen solely based on how difficult they would be to actually provide (e.g., the entire Atlantic Ocean). The items appear to follow Black Hat's stream of consciousness, starting with a boat, then a plane, then a distinctive plane, the bones of the pilot of that plane, the internal structure (similar to bones) of the famed landmark Statue of Liberty, etc. The title text reveals that the game show has ultimately acquiesced to one of Black Hat's wishes in a way: the dog leash mentioned would allow him to water-ski home, though such a dog leash is implausible (for example, a dog leash from San Francisco to Hawaii would be over 2000 miles long). [Cueball, Black Hat, and Megan are game show contestants standing behind lecterns with Hairy standing in front of them as the game show host. Black Hat, standing in the middle of the three, is holding a finger up while speaking.] Black Hat: A boat. A plane. Amelia Earhart's plane. Amelia Earhart's skeleton . The Statue of Liberty's internal support frame. The Crown Jewels. This show's entire television audience. The Greenland ice sheet. Earth's north magnetic pole. Black Hat: Am I in the Pacific Ocean? Black Hat: If so, the Atlantic Ocean. Hairy: Uhh. Hairy: Our producers are going to need some time on this one. [Caption below the panel:] The game show realized that they should have added some restrictions to their "take any item to a deserted island" challenge, but it was too late.

Throw

https://www.xkcd.com/2198

https://www.explainxkcd.com/wiki/index.php/2198:_Throw

[As this is an interactive comic, not all possible text should be given in this transcript. Also, it is not possible to see all the different throwers or objects in one image. This transcript here includes the text that can be found when loading the page, without changing the thrower or object (the default), but also includes the text that can be found by scrolling in the two select "windows" as that would be similar to a long comic where you need to scroll as well as customization options. For further differences that occur by changing the objects refer to a table of all combinations.] [A heading with a subheading is above a line, beneath which are a sentence, that is generated by the selections in the two windows beneath this sentence:] Throw Calculator This calculator implements the approximate throwing distance estimation model from How To Chapter 10: How to throw things . How far could George Washington throw a Microwave oven? [Beneath this sentence are two "windows" with a frame around them, one to the left and one to the right, each with a heading breaking the top frame. Each also has a scroll bar to the right, which allows one to scroll down through 8 different possible selections in the left window and 16 in the right window. There are, depending on the browser zoom level, one or two selections on each line. Each window's content is given here under their respective headings. Each possible selection is a drawing with a caption beneath it.] Select a thrower You An NFL Quarterback George Washington Pikachu Carly Rae Jepsen Thor, God of Thunder Chris Hemsworth A squirrel Select an object to be thrown You A microwave oven A basketball A blender A gold bar A wedding cake A ping-pong ball An acorn Thor's Hammer A javelin George Washington Pikachu A car A silver dollar (spinning) A silver dollar (tumbling) A squirrel [Below the two windows is the result of the animation that will happen when a selection has been made. An animation of the selected thrower throwing (or failing to throw) the selected object is shown, and the object's traveling distance is measured out both in meters (SI units) and in some other unit in brackets below. If the distance is not too long compared to the size of the object and thrower, then both can be seen, and in case the object is soft it may break from the throw.] [In the pre-selected version, George Washington throws a microwave oven, which ends up several meters from him lying on a corner broken with its wire lying beneath it. The distance is given under the ruler along which the throw has occurred, with markings for approximately every meter. In this case, there are seven steps even though the distance is above 7 meters:] 7.76 meters (25.46 feet) [Clicking on "You" in the thrower box opens a new window over the above described comic parts. some of the comic can still be seen including the thrower and his item, and a new throw occurs every time something is changed in this new window. It is a customization box with several options shown below.] Your Name ____You_____ [can be changed] Height 5.8 ft [number can be changed; ft can be changed to m] Mass 160 lb [number can be changed; lb can be changed to kg] Athleticism [Below is a scale showing Black Hat, Knit Cap depicting You , George Washington, and a person with goggles and a helmet. A marker is set at You, but can be changed. Below the characters are descriptions.] Black Hat: Moving objects around is for suckers. Minimal You: I'm in decent shape and have pretty good form. Decent George Washington: I'm so good at throwing they made me president. Extremely High Goggles: I use a time machine to train for 36 hours a day. Champion Athlete [Once done the box can be clicking on a cross at the top right or just clicking outside the window on the comic behind it. Now the thrower you (and the object you) will have the weight, length and strength chosen and will be able to throw (or be thrown) with these stats. ]

This is an interactive comic made to celebrate the release of Randall's new book, How To . The comic is based on a chapter in the book. As the comic celebrates the book, which was released on Tuesday, September 3rd, 2019, the comic was thus also released on a Tuesday to coincide with the release day, replacing that week's normal Wednesday release. This was the same timing used for another of Randall's book releases, when 1608: Hoverboard came out on the Tuesday when Thing Explainer came out. Although the Hoverboard comic is much more complex than this one, they are both dynamic and interactive , with animations a part of them. Also the xkcd Header text changed to promote the release creating a large combined promotion of the book during the three full days the comic was on the front page (see more here ). In this comic the viewer can select a thrower and an object to be thrown, see this table , and get an animation of how the selected throw would work out, along with an estimated distance of the throw (both in the SI unit meter (m) and in other very arbitrary units; see this table below) if the throw was possible. Impossible throws include those where the thrower is not strong enough to throw the object, or when the thrower tries to throw themselves, which is possible as four "objects" are also listed as throwers, most prominently George Washington . As the comic picture above cannot show all the possible selections in the two windows, pictures of all can be found here The formula/guideline is apparently based on chapter 10 from the new How to book, see more under Formulas . It seemed though, that there was a special case to the calculations with Thor's hammer ( Mjolnir ). Because this comic obviously refers to the Thor from the Marvel universe , played by another possible thrower, Chris Hemsworth in the Marvel Cinematic Universe , and his hammer , which is enchanted such that only those deemed "worthy" are able to lift it. As such, despite its mass in principle being liftable by many of the characters, only Thor, God of Thunder (who is canonically worthy), is able to throw it. Also Thor is the only one who uses furlongs to measure his distances among the standard throwers. However, it is not a canonical part of this comic that only he can throw it, and its mass is not realistic, see more below. Originally , when the comic was just released, there where only 7 throwers and 15 things to throw, giving a total of 105 different combinations; see the table below. But only Thor can throw all 15, with three of the objects (George Washington, Thor's hammer, and the car) unthrowable by any of the other throwers. The smaller critters can throw only a few things, so the total number of throws is much less than 105. Still, there is an animation for all 105 combinations, but with no throw distance for many of these. But already on day one the comic was out, a new thrower was added with the standard name "You", and this person, Knit Cap , was also added to the objects that can be thrown increasing the number of throwers to 8 and objects to be thrown to 16. However, it would not be true to say that the number of options now would be 8 x 16 = 128, since the "You" can be customized when selecting it in the throwers menu (but not when selecting You in the object menu). When doing so a new window called Custom thrower will open up over the comic. The "You" option can then be customized by changing the name (from the default "You"), and defining the height (default 5.8 ft = 1.77 m) and weight (default 160 lb = 72.57 kg), where ft (feet) can be changed to m (meter) and lb (pound) can be changed to kg (kilograms). But when doing so the window will not correct the number from feet to meter etc. but stay the same. Below the above options there is line with four persons above it, defining a scale of athleticism , the default second option being the drawing of "you" which represents Decent form (i.e. a normal person). The first on the scale is Black Hat , who thinks moving things is for suckers, thus representing minimal athleticism. "You" in second position is in decent shape and pretty good form, representing decent athleticism. George Washington in third position represents extremely high athleticism, and as he states he threw so well they made him President. Finally the fourth position, representing a champion athlete, shows a person with a helmet with chin strap and goggles who states that he trains 36 hours a day by using a time machine. It is thus indicated that such athletes can only be so good by training more than is possible; for instance, if he travels 24 hours back every day, he could use 12 more of these to practice, making it 36 hours on that "normal day" and he would then still have 12 hours to eat and sleep/restitution before his next 36 hours training pass. Changing away from the decent "You" to one of the other three characters on the athleticism scale does not, however, change the character used for the animation, which stays the same. But still this gives a very large number of different "yous" to both throw and be thrown. A self-created character, unrealistically tall and heavy well over the human records for height ( 272 cm ) and/or weight ( 635 kg ), can actually be able to throw Thor's hammer (For instance 4m and 1000 kg, see more here . So it is not because it is magically inclined to only be thrown by Thor, it is just that the weight is set to 2000 kg, and only Thor of the standard characters have the strength (1000 times normal human strength) to throw such a heavy object. But if the "You" is big enough, the athletic difference with Thor will be compensated by sheer weight and height. See this table of data from the comic for the above numbers. Interestingly, Thor can throw a squirrel 257 meters. If a Custom Thrower is created, and they are 200 meters tall and 150 KG, they can throw the squirrel 256 meters (1 meter less than Thor). Thor can throw an acorn 136 meters, and the Custom Thrower will throw it 133 meters. Now, Thor can throw Thor's Hammer 19 meters. The Custom Thrower can throw it 44 meters! Apparently there is more to the enchantment of Thor's Hammer than meets the eye, as it would have been expected that if Thor can throw a squirrel and an acorn farther than an extraordinary human, then certainly he could throw his own enchanted Hammer a longer distance. This is, of course, because the Custom Thrower now throws from much higher than Thor. As to why the height doesn't affect the acorn or squirrel throwing distance in the same way it does Thor's Hammer, we'll leave that to you, the reader. The title text refers to throwing a party (a colloquial synonym of hosting a party) and first makes the assumption of actually giving hints for giving a party, and then switches to suggest a mechanism to literally throw a huge object, such as a house with a party going on inside. An aircraft steam catapult is a mechanism to launch aircraft from ships, typically used on aircraft carriers. Many of the items, even if technically possible to throw, may not be able to be thrown safely. For example: Constants and Units: As this comic is very complicated several screen shots and tables are needed for the full explanation. In order to keep this main page easy to use, these pictures and possibly some of the tables will be placed on some extra pages, as has also been done with other complex comics in the past: [As this is an interactive comic, not all possible text should be given in this transcript. Also, it is not possible to see all the different throwers or objects in one image. This transcript here includes the text that can be found when loading the page, without changing the thrower or object (the default), but also includes the text that can be found by scrolling in the two select "windows" as that would be similar to a long comic where you need to scroll as well as customization options. For further differences that occur by changing the objects refer to a table of all combinations.] [A heading with a subheading is above a line, beneath which are a sentence, that is generated by the selections in the two windows beneath this sentence:] Throw Calculator This calculator implements the approximate throwing distance estimation model from How To Chapter 10: How to throw things . How far could George Washington throw a Microwave oven? [Beneath this sentence are two "windows" with a frame around them, one to the left and one to the right, each with a heading breaking the top frame. Each also has a scroll bar to the right, which allows one to scroll down through 8 different possible selections in the left window and 16 in the right window. There are, depending on the browser zoom level, one or two selections on each line. Each window's content is given here under their respective headings. Each possible selection is a drawing with a caption beneath it.] Select a thrower You An NFL Quarterback George Washington Pikachu Carly Rae Jepsen Thor, God of Thunder Chris Hemsworth A squirrel Select an object to be thrown You A microwave oven A basketball A blender A gold bar A wedding cake A ping-pong ball An acorn Thor's Hammer A javelin George Washington Pikachu A car A silver dollar (spinning) A silver dollar (tumbling) A squirrel [Below the two windows is the result of the animation that will happen when a selection has been made. An animation of the selected thrower throwing (or failing to throw) the selected object is shown, and the object's traveling distance is measured out both in meters (SI units) and in some other unit in brackets below. If the distance is not too long compared to the size of the object and thrower, then both can be seen, and in case the object is soft it may break from the throw.] [In the pre-selected version, George Washington throws a microwave oven, which ends up several meters from him lying on a corner broken with its wire lying beneath it. The distance is given under the ruler along which the throw has occurred, with markings for approximately every meter. In this case, there are seven steps even though the distance is above 7 meters:] 7.76 meters (25.46 feet) [Clicking on "You" in the thrower box opens a new window over the above described comic parts. some of the comic can still be seen including the thrower and his item, and a new throw occurs every time something is changed in this new window. It is a customization box with several options shown below.] Your Name ____You_____ [can be changed] Height 5.8 ft [number can be changed; ft can be changed to m] Mass 160 lb [number can be changed; lb can be changed to kg] Athleticism [Below is a scale showing Black Hat, Knit Cap depicting You , George Washington, and a person with goggles and a helmet. A marker is set at You, but can be changed. Below the characters are descriptions.] Black Hat: Moving objects around is for suckers. Minimal You: I'm in decent shape and have pretty good form. Decent George Washington: I'm so good at throwing they made me president. Extremely High Goggles: I use a time machine to train for 36 hours a day. Champion Athlete [Once done the box can be clicking on a cross at the top right or just clicking outside the window on the comic behind it. Now the thrower you (and the object you) will have the weight, length and strength chosen and will be able to throw (or be thrown) with these stats. ]

Cryptic Wifi Networks

Cryptic Wifi Networks

https://www.xkcd.com/2199

https://www.explainxkcd.com/wiki/index.php/2199:_Cryptic_Wifi_Networks

[Knit Cap (who has a backpack) is checking a phone at the highest mountain in a mountainous landscape, with 5 snow covered mountain peaks behind, and a smaller peak connected to and just below that one. There seems to be no snow on those two peaks. Above is a view of the phone's screen as indicated with a zigzag line from the phone's screen to the frame with text. There is also a wifi icon at the top left and a padlock icon at the end of the second line of text. The bottom line is a gray font.] Phone: Available WiFi Networks Phone: Toshiba-U2187-OfficeLink-Net46UHZ Phone: Join other network [Caption below the panel:] Tech Trivia: No one actually knows what devices produce those cryptic WiFi networks. They just appear at random across the Earth's surface.

In the comic, Knit Cap is on top of a high mountain in a remote location (second comic in a row with knit cap). Mobile devices frequently launch a popup telling users to choose a network to connect to. Knit Cap sees a WiFi network name listed on a handheld device, perhaps a cell phone. This is something you would expect in a city, but certainly not on a mountain top, hence the joke, that what produced these WiFi networks are unknown, but seem to be distributed randomly over the face of the Earth, disregarding nearness to technology. Cryptic Wi-Fi (or WiFi) network names, called Service Set Identifiers (SSIDs) are part of the joke about not knowing where the corresponding wireless router is located, suggesting they are unexplained phenomena instead of wireless radio devices. Some of the earliest WiFi devices like printers and internet routers advertised cryptic SSIDs, as do many of them today. In 1998, Lucent introduced the WaveLAN IEEE , the first integrated circuit chip set supporting the IEEE 802.11 wireless LAN protocol, spinning off Agere Systems to produce them in 2000. WiFi followed mid-1990s short-range wireless networks like Bluetooth and radio internet protocols like the 1980s KA9Q , with roots going back to the earliest ticker tape digital telegraphy systems from the mid-1850s. Humorous SSID names are not uncommon. The SSID displayed is Toshiba-U2187-OfficeLink-Net46UHZ which is 33 characters long, unfortunately one character more than are allowed. Toshiba is a multinational electronics conglomerate manufacturing many products including untold multitudes of different kinds of printers over the years. Such devices often have embedded wireless access points including the manufacturer name in the SSID. Many network names contain words like Net, Office or Link. The code might indicate a model U2187 device from Toshiba named (or having an interface program named) OfficeLink, which has a sub-model number or operates on a wireless network designated 46UHZ. That "Hz" is an abbreviation for Hertz suggests that designation may or may not have something to do with the frequency on which the transmitting device operates. 48 microhertz corresponds to a period of 4.1 per day, or a radio wavelength 41 times as far as the Earth is from the Sun. Or U2187 could be the Unicode character code for the Roman numeral 50,000 spelled "ↇ" or a serial number for a user or a utility pole. We don't know whether the SSID is connected to a network of more than one or is just one device. The padlock icon indicates that a password is required to communicate. The "join other network" option allows for manually typing SSIDs to attempt to connect with networks which are not configured to display their SSIDs. While the most likely explanation in an office environment might be a printer plugged in somewhere nearby, other possibilities include a marsupial delivery drone, television, cryptocurrency mining rig, speaker, pacemaker, alarm system, offshore flying wind turbine, fashion accessory, autonomous antimissile defense system node, hobby project, surveillance device, balloon , distributed denial of service attack platform malware-infested coffee pot, satellite , vending machine, seawater dialysis station, telecommunication facility, solar-powered drone , distributed exoskeleton, visiting interstellar colony(?) ship, power-to-gas pipeline valve, ransomware worm nest, or anything else in the Wifi Internet of Things . Sometimes, the ionosphere reflects radio waves, vastly increasing the distance that they can travel to and from remote locations, but this skywave propagation normally affects frequencies below 30 MHz, and never above 300 MHz, so they couldn't be the cause of receiving far away Wifi signals, which are 900 MHz and above. Network names can be used to track the geographic locations of mobile devices, for example in the Wi-Fi positioning system . Google street view equipment records locations of networks to assist with geolocation . Location information can be searched in tools like Wigle or OpenWifiMap . The Institute of Electrical and Electronics Engineers (IEEE) committee number for WiFi is 802.11, which is composed of sub-committees like 802.11ad , designing the 60 GHz Multiple Gigabit Wireless System (MGWS) and 802.11ay working on multiple input, multiple output (MIMO) bandwidth enhancements. This portable Toshiba printer supports the "802.11 a/b/g/n" WiFi protocols. The software which produces SSID listings is administered by network communities and depends on mesh configurations . (Please see also 1785: Wifi .) Alternatives include bluetooth mesh networks and other ad hoc networks to provide internet connectivity services. The title text indicates that the first WiFi networking client interface displayed unexpected SSIDs. If true, this could potentially rule out all of the alternative explanations other than an alien visitation, a software bug, rogue industrial espionage, time travel, trans-multiverse or trans-dimensional communication, hardware misconfiguration, the simulation hypothesis , or the supernatural. (It is worth noting that cryptic-sounding WiFi networks generated by a time-traveling alien entity as a trap was used as a plot device in the 2013 Doctor Who episode " The Bells of Saint John .") [Knit Cap (who has a backpack) is checking a phone at the highest mountain in a mountainous landscape, with 5 snow covered mountain peaks behind, and a smaller peak connected to and just below that one. There seems to be no snow on those two peaks. Above is a view of the phone's screen as indicated with a zigzag line from the phone's screen to the frame with text. There is also a wifi icon at the top left and a padlock icon at the end of the second line of text. The bottom line is a gray font.] Phone: Available WiFi Networks Phone: Toshiba-U2187-OfficeLink-Net46UHZ Phone: Join other network [Caption below the panel:] Tech Trivia: No one actually knows what devices produce those cryptic WiFi networks. They just appear at random across the Earth's surface.

Unreachable State

Unreachable State

https://www.xkcd.com/2200

https://www.explainxkcd.com/wiki/index.php/2200:_Unreachable_State

[Cueball, sitting on an office chair at his desk with his hands over his laptop computer. There is an error message on the screen which is displayed above him with a zigzag line from the screen to the text. The exclamation mark at the top is shown in white on a black triangle.] ! Error If you're seeing this, the code is in what I thought was an unreachable state. I could give you advice for what to do. But honestly, why should you trust me? I clearly screwed this up. I'm writing a message that should never appear, yet I know it will probably appear someday. On a deep level, I know I'm not up to this task. I'm so sorry. [Caption below the panel:] Never write error messages tired.

When writing a computer program, developers often need to make assumptions about what state the system could potentially be in at the time the program is executed. For example, a program designed to fetch data from a database requires that the database be accessible at the time it tries to fetch data; if it is not, then the program needs to know how to handle that state, or it might simply hang or crash the system. A good developer will have accounted for this possibility and may give the program a way to fail gracefully; often, this is done by outputting an error message to the user, to tell them what is wrong. Sometimes, cautious developers will identify states that, in theory, should never be reachable at all - if they were, it would imply that something has gone fundamentally wrong. A paranoid developer might still decide to handle this case anyway, perhaps including a note that the situation should theoretically never happen, but they aren't confident enough to state with absolute certainty that it cannot. This comic shows Cueball reading (or possibly writing) just such an error message from a program he is using. The developer has evidently written this text while tired (possibly from overwork), and did not trust themself enough to be sure that the state is truly unreachable. The hopeless tone of the message supports this lack of confidence in their work. The title text refers to the common trope of a character being given a "magic" item and winning something because of it, then being told that the item was not actually magic and that the magic was inside them all along . It is often used as a fable to tell people to follow their dreams. The title text puts the fable in a place where it doesn't belong, saying that finding the "unreachable state" that is the error code implies that the finder can do anything. [Cueball, sitting on an office chair at his desk with his hands over his laptop computer. There is an error message on the screen which is displayed above him with a zigzag line from the screen to the text. The exclamation mark at the top is shown in white on a black triangle.] ! Error If you're seeing this, the code is in what I thought was an unreachable state. I could give you advice for what to do. But honestly, why should you trust me? I clearly screwed this up. I'm writing a message that should never appear, yet I know it will probably appear someday. On a deep level, I know I'm not up to this task. I'm so sorry. [Caption below the panel:] Never write error messages tired.