Biff Tannen

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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

Explanation:
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.]