October 2017

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


Ears

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


Jet Lag

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


Logical

Explanation:
White Hat says that problems in society could be avoided if people relied on logic and science rather than feelings—but when Cueball presses him to back up his claim, White Hat insists that his claim must be true, because it just seems obvious (to White Hat), and what the opposition (which he dismissively refers to as "these idiots") believes is crap in his opinion. Since White Hat refers to all people in general and since he falls in the same trap as he complains about, using his feelings for his case instead of logic and science, White Hat's argument is both fallacious and hypocritical.
The title text is White Hat's opinion, where he states that he has always said that people just need more common sense . He then adds, but not the kind of common sense that lets them figure out that he is condescending (i.e. talking down to them) and basically thinks that they are stupid. If they did, they would probably realize that White Hat considers himself smarter than them, and likely feel insulted and take retribution. (At the same time, he may himself lack this form of "common sense," as Cueball's question could be seen as a veiled insult highlighting White Hat's hypocrisy.)
When people talk about "common sense", they often really mean "they should think like I do". Using a term like "common sense" as a proxy for one's personal point of view implies that everyone else should have the same point of view. This discredits the fact that each person has their own point of view, completely valid to their own mind, and any attempts to push someone else's idea of a "common sense" upon them usually feels like "being talked down to" because of the implicit "fact" that that person's point of view is "common" and makes "sense", and therefore they must be smarter than you if you don't agree with their "common sense".
Ironically, there is some inconclusive scientific evidence against White Hat's position. It is possible that effective rational thought depends on feelings and emotions as a preprocessing step. For example, people with damage to the ventromedial prefrontal cortex lose their ability to have gut reactions to decision options. In Antonio Damasio 's research, they were unable to make good decisions in everyday life. This may be because every option seems emotionally as good as any other and the brain is not good at conscious processing of large numbers of alternatives. See Descartes' Error by Damasio (1994) and The Righteous Mind by Haidt (2012).
[White Hat is spreading his arms and facing Cueball.] White Hat: We wouldn't have all these problems if people just learned to be more logical and science-driven instead of relying on feelings . Cueball: Oh? What study are you basing that on? White Hat: It just seems obvious! White Hat: I mean, look at the crap these idiots believe!


State Borders

Explanation:
In this comic, graphic designers take control of the United States, but the only thing they do is to change the state and national borders, using primarily aesthetic criteria. State and national borders have generally emerged from some combination of political decisions, natural boundaries, control of natural resources, and, to some degree, from chance. As the comic implies, some borders originally resulted from surveying errors, but became encoded by law and tradition, and thus were never changed.
Despite the caption's rather blasé reaction to the graphic designers' master plan, the changes they propose could be rather tumultuous. Political boundaries are difficult to change because rewriting them places entire populations in different states or even different countries. Even within the US, changing a population from one state to another has serious implications. A different state means different laws, tax obligations, public benefits, business regulations, infrastructure support, etc. It would also mean that control of some very substantial natural resources would be transferred from one state to another. More significantly, the suggestion to cede portions of the US to Canada and Mexico would be a much bigger deal, forcing residents of those areas to either leave their homes, businesses, and communities or surrender their current nationality and apply for citizenship in another country. The joke behind the comic is that graphic designers would tend to ignore these practical concerns and pay more attention to a map looking orderly.
This comic hints at the fact that it is indeed Randall who wants to see these changes made.
In the title text, the graphic designers have a civil war between the ones that favor "panhandles" in the borders, such as the Oklahoma one which is enlarged in the map, the Florida one which is removed in the map, and maybe others such as the Texas region known as the "Texas panhandle". However, as graphic designers, they get too caught up in making the flag designs for their faction to actually fight. Randall has shown interest for vexillology (the study of flags) in the past.
[An outline map of the United States is shown, including state boundaries. The following edit marks are shown in red text:] [Minnesota's Northwest Angle is circled] Give to Canada [Border between Wisconsin and Michigan's Upper Peninsula is crossed out] This should be Wisconsin [New York's Long Island is circled, with arrows and question marks pointing to New Jersey and Connecticut] Move Long Island to NJ or CT or make it its own state [New York's eastern border has been straightened] [Wyoming's western border is moved to align with that of Colorado. The Montana/Idaho and Idaho/Utah borders are extended to reach the new border. Similarly, Colorado's eastern border is moved to align with that of Wyoming, and the Nebraska/Kansas border has been extended] Align to grid [West Virginia's northern panhandle has been given to Ohio and part of its eastern panhandle has been given to Maryland. In return, Western Maryland has been given to West Virginia. The altogether effect is that West Virginia and Maryland have more compact shapes] Clean Up [Rhode Island has been enlarged to encompass southeastern Massachusetts, and Delaware now takes up the entire Delmarva Peninsula] Enlarge Rhode Island & Delaware [The Oklahoma Panhandle has been extended west until it reaches Nevada, taking the northernmost parts of Arizona and New Mexico with it] If we're going to have a panhandle, why not commit to it? [The Missouri Bootheel has been given to Arkansas] Fix this thing [The part of Virginia west of the Appalachian Mountains has been given to Kentucky] [The southwestern and eastern borders of Nevada have been extended into Arizona until they meet a point. A part of California is slightly extended to reach the revised border] [Parts of Arizona and New Mexico have been ceded to Mexico, and part of Texas has been given to New Mexico, so that the southern borders of Arizona and New Mexico and the northern border of the Trans-Pecos area of Texas collectively form a straight line] Clean Up [Parts of northeastern Texas have been given to Arkansas and Louisiana] [The northern and southern borders of Tennessee have been straightened] Straighten to fix survey errors [A line has been traced along the coasts of South Carolina, Georgia, and northern Florida] Good curve! Keep. [Alaska's southeastern panhandle has been circled] Let's be honest - this should be Canada, too. [The Alabama/Florida border has been erased, and Alabama's eastern border has been extended south until it meets the Gulf of Mexico] Why should Florida get Alabama's coastline? It has plenty.
[Caption below the panel:] It was scary when graphic designers seized control of the country, but it turned out they just wanted to fix some things about the state borders that had always bothered them.


Bun Trend

Explanation:
In this comic, Beret Guy takes his bun shenanigans to the state government, reporting to the governor that the number of buns around the capitol has shown a rapid increase. The governor is confused, then finally comes to grasp that Beret Guy is talking about rabbits , lots of which can be seen if he would just go outside (by the way, there is a small one RIGHT NOW !).
Elections in the United States often have a blank spot on the ballot for the voter to write the name of a write-in candidate . Beret Guy thinks he works for the governor because he wrote his name in on the ballot. This does not mean that he actually works for the governor. [ citation needed ]
The governor finally takes appropriate action by calling security, and Beret Guy confronts his fate with poise and honor. Indeed, the readiness with which he accepts his removal almost seems to suggest that he doesn't belong, which would be an unusual level of awareness for his character. Alternatively, Beret Guy might have misinterpreted the governor's request for security as a question of whether he works in security, or simply ignorance. This also may be an ironic reference to the rapid turnover in President Trump 's staff.
"Buns" have been mentioned previously in 1682: Bun and 1871: Bun Alert .
Beret Guy's uncertain position in the government is very similar to the way he treats and operates his business.
In the title text, experts characterize the ecological impact of a large number of bunnies as "adorable" instead of giving information on how the rabbits are affecting the environment.
[Beret Guy holds a stick and points at a board next to him. The board contains a picture of a rabbit, a data point graph, and other notes.] Beret Guy: Good morning, Governor. Our tracking systems show a rapid increase in the number of buns around the Capitol.
[Hairy is sitting at an office desk and facing Beret Guy in a frameless panel.] Hairy: Buns? Beret Guy: Yes; there's been a long-term upward trend, but it has accelerated recently. Hairy: The trend in... rabbits. Beret Guy: Yes.
[Beret Guy takes out his phone.] Hairy: So... so what? Beret Guy: So if you want to see some buns, there are lots of them outside! [Beret Guy's phone vibrates] Phone: beep! Beret Guy: Ooh! Beret Guy: There's a small one right now!
[Zoom-in on Beret Guy.] Hairy (offscreen): Do you... actually work for me? Beret Guy: Almost certainly. We had an election, right? I wrote my name in on the thing. Hairy (offscreen): Security? Beret Guy: It's been an honor to serve.


Research Risks

Explanation:
This is a comparison of the possibility of the subjects of various sciences being a threat to humanity. It can either be an autonomous threat to the local population (i.e. by escape from a lab), or as part of a supervillain's scheme to rule the world .
In general, areas of study that could be used by supervillains, but are unlikely to "break free" refer to technologies that are unlikely to be self-propagating or self-maintaining, but could be used as weapons or for some other form of control. Subjects that could break free, but are unlikely to be used by supervillains are all living organisms (which could presumably breed and multiply without human intervention), but which have little potential as weapons.  Areas of study that fall in both categories are either more controllable forms of biology (microbiology, genetic engineering), forms of technology that could become self-propagating (robotics), or a study where a release could be dangerous without being self-propagating (chemistry).
The category of a low risk of either could, of course, contain many fields of study, as most research fields have limited potential for weaponry and little danger of going out of control on a large scale.
See the chart below for detailed explanations of each scatter point.
There have so far been several similar comics with such scatter plots . See for instance 1242: Scary Names , 1468: Worrying , 1501: Mysteries and 1701: Speed and Danger .
The title text is related to the Molasses Storage entry at the bottom left of the chart, and references the Great Molasses Flood , also known as the Great Boston Molasses Flood. It occurred on January 15, 1919 in the North End neighborhood of Boston , Massachusetts (the state in which Randall lives). A large molasses storage tank burst and a wave of molasses rushed through the streets at an estimated 35 mph (56 km/h), killing 21 and injuring 150. The joke in the title text is that in 2031 (14 years after the release of this comic) the Canadian Space Agency has an even more serious disaster, which will be known as the orbital maple syrup delivery disaster. The title text claims that this disaster then became the deadliest confectionery containment accident, thus killing more than 21 people.
Note : percentages refer to the position of the center of the smallest enclosing rectangle around each name. 0% and 100% correspond to the low and high arrow tips, respectively.
[A chart with two crossing lines with double arrows. Each arrow is labeled:] Y axis top: High Y axis bottom: Low X axis left: Low X axis right: High
[Near each of the "high" ends of the two axis there is a label written in gray, with a line pointing to the relevant axis:] Y axis: Risk of your research being used by a supervillain for world domination X axis: Risk of the thing you're studying breaking free from your facility and threatening the local population
[The following points are on the charts upper left quadrant (in reading order):] Prosthetics Neuroscience Laser Optics Pharmacology Materials Science Sociology History Psychology
[The following points are on the charts upper right quadrant (in reading order):] Robotics Genetic Engineering Chemistry Microbiology
[The following points are on the charts lower left quadrant (in reading order):] Geology Linguistics Paleontology Astronomy Molasses Storage Dentistry
[The following points are on the charts lower right quadrant (in reading order):] Botany Entomology Mycology Marine Biology Ornithology


Cast Iron Pan

Explanation:
White Hat is discussing tips for maintaining Cast-iron cookware . Cast-iron cookware is well-loved and often promoted by cooking aficionados, but requires more effort and care to maintain than many other modern forms of cookware. This strip satirizes both the amount of effort involved, and the attitude of connoisseurs who look down on people who are unwilling to put in such effort. In typical xkcd fashion, the comic starts off somewhat realistic and escalates to absurdity.
White Hat tells the old myth (debunking articles: Lifehacker , The Kitchn , Serious Eats ), that "you shouldn't wash your cast iron pan with soap since it destroys the seasoning ", to Cueball . Seasoning is the process of treating the surface of a pan with a stick-resistant coating formed from polymerized fat and oil on the surface. Although it may not be a problem to use soap on your seasoned cast iron pan, you should still proceed with care with how you treat it.
White Hat starts to exaggerate; he tells him that if he ever as much as let soap touch the pan he should just throw it away, as that fact alone would prove that he would not be up to taking care of such a precious possession. This is a kind of scare tactic that might make Cueball believe this and anything else he tells him.
White Hat continues to give dubious advice to the point of absurdity, and Cueball becomes more and more wary of it.
His next word of advice is to apply moisturizer to the pan daily to keep it fresh. Cueball asks why and is told that it is to avoid the pan getting wrinkles . This implies that the pan would age like a human and get wrinkles. This is, of course, nonsense [ citation needed ] , but Cueball is not yet ready to dismiss White Hat's advice.
The final piece of advice is that twice a year Cueball should fill the pan with iron filings and leave it in direct sunlight for 24 hours. Both details are intended to be absurd. For one, neither the iron filings nor the sunlight appear to serve any actual purpose . Second, 24 continuous hours of direct sunlight is impossible to achieve in most places. North of the Arctic Circle (often shortened to simply "the Arctic ") there will be at least one day a year where the sun does not set. While one might assume that a combined total of 24 hours over couple of days would be sufficient, White Hat implies that it's necessary to travel to very remote locations in very specific parts of the year to meet an extreme requirement. He further casts an unwillingness to meet this unreasonable standard as rendering a person unworthy of cast iron.
White Hat's strict tone "If you're not willing to travel to the Arctic, you don't deserve cast iron" might also suggest that cast iron is a special almost-legendary metal similar to Damascus steel or its fictional counterpart Valyrian steel and requires distant travel to obtain/maintain. This is likely a parody of the level of reverence cast iron cookware tends to receive in certain circles.  Despite there being alternatives that are much easier to maintain, a significant number of cooks insist that cast iron has qualities that make it worth the amount of effort involved.
In the title text, White Hat mentions that, if you wish to evenly space the two 24 hours of sun each year, it is easiest to alternate between the Arctic and the Antarctic regions. But this will mean that you have to travel a long distance at least once a year; even if you already lived inside one of the Polar Circles , you would have to travel to the other at least once a year.
It is implied that you do not have to space them evenly. As he mentions, some people just go to the Arctic twice a year near the equinoxes .  However, according to White Hat, this is not the same, probably because it doesn't lead to an exact six-month spacing and the sun would stay very low on the horizon and the sunlight would not be as intense.
In order to accomplish this other scheme, it also means that they would actually have to go very close to the North Pole (or South Pole ), as this is the only place with midnight sun around the equinoxes. So, in principle, this would be much more cumbersome than just going inside the southernmost part of the Arctic region at the summer solstice , and similarly the northernmost part of the Antarctic region at the northern hemisphere's winter solstice (which will be the summer solstice in the southern hemisphere).
When looking at it like this, it may seem that White Hat actually means that you should always go to the poles, rather than just to a place with 24 hours of sunlight, in order to have the sun high in the sky as well.
[White Hat is holding a pan by the handle pointing to the frying surface as he shows it to Cueball.] White Hat: Never clean a cast-iron pan with soap. It destroys the seasoning. Cueball: Got it.
[White Hat shift the pan to his right hand and lowers it to his side holding a finger up in front of Cueball.] White Hat: If you ever let soap touch the pan, throw it away. You're clearly not up to taking care of it. Cueball: Wow, okay.
[In a frame-less panel White Hat has taken the pan back to the first hand holding on the the edge while he holds his other hand close to the frying surface.] White Hat: Apply moisturizer to the pan daily to keep it fresh. Cueball: ...Moisturizer? White Hat: Do you want it to get all wrinkly? Cueball: ...I...guess not.
[White Hat has shifted the pan to the second hand again holding it by the handle away from Cueball, while pointing at Cueball with the other hand.] White Hat: Twice a year, fill the pan with iron filings and leave it in direct sunlight for 24 hours. Cueball: Wait. 24 hours of sun? White Hat: If you're not willing to travel to the Arctic, you don't deserve cast iron.


Making Progress

Explanation:
Megan has procrastinated made progress on a large backlog of problems. While she started the day with lots of problems, she has entered those problems into a spreadsheet. While this could potentially allow her to tackle her problems in a more organized way and fix them more quickly, the humor lies in that none of the problems have actually been solved. Additionally, it's questionable whether this was worth the hours of effort she put into making the spreadsheet, and even whether the spreadsheet has made her problems any easier to tackle in the first place. The comic questions the usage of spreadsheets for anything beyond organization.
In the title text she reveals that even her spreadsheet has a problem, because "#REF Circular Dependency detected" is a spreadsheet error meaning that a formula is (possibly indirectly) using its own cell in the equation. This is probably because she has used the Count() function to find the number of problems to be solved, but since one of those problems is not knowing how many problems she has, it is trying to include itself in the count.
This counting problem may also be a metaphor for circular dependencies within the problems themselves, such that a solution to one problem would help solve another problem, but solving the first problem depends on a solution to the second problem (e.g. organizing a cluttered mess of objects requires room to work, which is not available because of all the clutter).
Arguably, this has introduced a further problem, so she actually now has (#REF Circular Dependency detected)+1 problems. It's also possible, since Megan has chosen to interpret the error message as a numeric value representing the number of problems she has, that she is simply not good at using her spreadsheet software, which may be another problem that needs adding to her list. The use of COUNT() has, rather than returning an exact amount of problems to solve, implied that her original problems cause so many more that she does indeed have "countless problems".
The error shown is similar to two different errors in the popular spreadsheet program Microsoft Excel : #REF! , which means that an invalid reference has been made (such as to a cell or sheet that has since been deleted), and circular references , which means that a certain cell's content has been made to depend, at some stage, on its own content, recursively . The latter could be because it directly refers to itself, or because it refers to another cell which, in some way, refers back to it. Most versions of Excel do not show circular references in the cell, next to where a #REF! error would be; rather they show an error message box and arrows drawn over the sheet which connect the dependencies of the cells involved in the error. However, since the comic does not specify which spreadsheet software Megan is using, Randall can simply make the errors up, to make the joke more quickly understandable, while clearly referencing errors that show in actual spreadsheet software.
[Megan is sitting and looking at a laptop.] Megan: I started the day with lots of problems. Megan: But now, after hours and hours of work, Megan: I have lots of problems in a spreadsheet .


Immune System

Explanation:
In this comic, Ponytail is delivering an informative report to a group of listeners, likely important managers of some large company. She begins her lecture by stating she is the host of a microscopic autonomous swarm that will do anything to protect her. She is referring to the immune system, which could technically be defined as a "microscopic autonomous swarm" that will do anything to protect her -- i.e destroy pathogens such as viruses and bacteria, both of which cause multitudinous diseases in humans. Like many of the systems of the body, the immune system cannot be controlled by conscious thought, and should not be taken as unordinary.
The caption below reveals the method behind her madness. Randall claims that beginning any business presentation with a surreal description of one's own immune system is guaranteed to strengthen your case. Whether or not this is actually the case is irrelevant, the point of the comic is about "how cool the immune system is", and explains its coolness through an unconventional description of how the process works. Additionally, Ponytail's description implies more potential power over external entities than an immune system typically has, perhaps to to gain more respect/fear from the speaker's audience.
The title text elaborates further on this, stating that similar arguments can be used in negotiation. The description of the immune system is deliberately misleading, implying that the immune system may attack the other negotiator if the terms of the deal aren't satisfactory. While it is correct that your immune cells cannot be reasoned with [ citation needed ] and theoretically it could cause an anaphylactic shock in the targeted organism, the veiled threat omits the fact that the immune system 1) is unaffected by external negotiations conducted by its host, 2) is incapable of attacking things outside of the body, and 3) would have to overcome the target's own immune system.
[Ponytail is standing in front of a boardroom meeting, pointing to a presentation on a screen. Cueball, Megan and Hairbun are in the audience, sitting at a long table; an extra, unoccupied chair is in the front.] Ponytail: My body hosts an autonomous microscopic defensive swarm that will do anything to protect me. Ponytail: I have no ability to restrain it and I don't know my own power. Ponytail: So listen up. Ponytail: Sales grew by 4% this quarter...
[Caption below the panel:] Business protip: You can strengthen any presentation by opening with a reminder about how cool immune systems are.


Credit Card Rewards

Explanation:
A credit card , at its most basic form, is a loan contract to an individual from a bank . Like all contracts, the bank will offer several different types in an attempt to appeal to a large number of individuals. Unlike traditional loans which focus on a single item (car, house, boat, etc), a credit card is an unsecured loan geared towards daily and weekly transactions. Because these transactions cover a wide variety of items, credit cards can be further tweaked towards offering benefits in certain areas. For example, gas purchases, or even gas purchases through a single retail chain, can offer higher rewards on one type of plan vs. other plans.
These benefits, typically called rewards, have several different options. " Cashback " is a reward where the individual is given money back when they make a purchase that follows certain rules spelled out in the contract. "No interest " is a reward where the individual is not charged interest on their purchases if they pay the loaned money back within a specified amount of time. "Points" are similar to the cashback program, but are typically reserved towards purchasing a single large item or plan. Points towards a vacation is a popular option. Besides these three types of rewards, the number of actual rewards to pick from are limited only by the creativity and fiscal limitations of the issuing bank.
Cueball is trying to choose the optimal credit card program that will result in the biggest savings for his typical income and spending patterns. He will need to trade off the value of any benefits against the cost of any fees and interest charges that would be incurred. This could become quite complex if he is prepared to consider taking out multiple cards to access the various benefits they offer, and in order to get the best outcome he may need to regularly shift funds from one card to another to make use of introductory or short-term offers. On top of all this, the incentives on offer may change his spending behaviour, which would further impact the calculation. (This table was actually created in 1205: Is It Worth the Time? )
He then realizes that there is a cost of him spending time on optimizing his choice, so he wants to limit the time spent doing the optimizing so that it doesn't outweigh the maximum advantage he might gain from choosing the best deal. Finding a definite answer to the time at which he should stop his optimization efforts is hard, if not impossible, because the fact that he cannot complete them means that he probably cannot know for certain what the maximum advantage would be; he will have to rely on a probabilistic solution instead. To further complicate things, he will need to factor in the cost of the time spent solving the problem of how long to spend on optimizing (and, presumably, the time spent solving that problem, and so on infinitely).
Hairy challenges a hidden assumption that Cueball's time has significant value, which would imply that if he wasn't worrying about this problem. he would be doing something more productive, implying that Cueball's obsession with optimization is lame enough to suggest that he does not actually have any more worthwhile interests to pursue. His response that he "could be failing to optimize so many better things!" just further proves Hairy's point, and suggests that Cueball is aware of both the big flaw in his reasoning and the fact that, when he attempts to optimize things, it seldom really helps his situation.
The title text further expands the idea. Cueball wants to work out which optimization problems he could most productively work on first. However, his proposed idea of creating a spreadsheet to calculate this may well end up costing more in time than the benefit he would gain from working on them in priority order (particularly since, on this evidence, the potential gains from each problem are marginal at best). Furthermore, if the 'several variables' he needs to consider lead to the kind of complexity seen in the credit card problem, a spreadsheet may not be the best tool for the kind of calculations he needs to perform.
The idea of spending more time organising tasks in a spreadsheet than you actually do working on the tasks was previously featured in 1906: Making Progress .
[Cueball sits at a desk and is on his laptop. Hairy stands behind him.] Cueball: I'm trying to figure out which of these credit card rewards programs is best given my spending.
[Cueball leans backwards in a frameless panel.] Cueball: But at some point, the cost of the time it takes me to understand the options outweighs their difference in value.
[Close-up of Cueball's head and torso.] Cueball: So I need to figure out where that point is, and stop before I reach it. Cueball: But... when I factor in the time to calculate THAT , it changes the overall answer.
[Cueball has his arms outstretched.] Hairy: I question the assumption that you'd otherwise be spending your time on something more valuable. Cueball: Come on, I could be failing to optimize so many better things!


Digital Resource Lifespan

Explanation:
In this chart, Randall laments the tendency of digital resources to quickly become obsolete or non-functional.  By taking a general subject, such as xkcd's core subjects of "romance, sarcasm, math, and language", one can see that a useful tool such as a smartphone or computer app or interactive CD-ROM (essentially, software) does not have the lasting power of printed books (e.g. textbooks, for many general subjects) and microfilm/microfiche.  The printed resources, not having to rely on a computerized platform for use, are far more reliable despite being less mobile and taking up physical space. The only digital source which is still working is Portable Document Format (aka PDF) which encapsulates fixed layout flat documents, and is supported for years already by Adobe Systems and is part of ISO standards, so has a widespread support, and should be still viewable in foreseeable future.
The title text makes a statement that libraries do not require the support of original authors/experts to organize and store vast resources for any subject imaginable.  This is true, but omits the fact that ongoing efforts are required by experts in information organization and storage -- namely, librarians.  Physical books and microfilm/microfiche need controlled storage environments, manual handling for storage, retrieval, distribution (in library terms, "circulation"), and the like.  Thus, a library can require significant resources in personnel and facilities, but is usually seen as a "public good" for the benefit of society; thus, many communities and educational institutions invest in creating and maintaining a library despite the costs.
Archive.org refers to The Internet Archive , a non-profit organization that maintains the Wayback Machine , one of the largest archives of the World Wide Web . When a website is taken offline, copies of its content can often be found backed-up on the Wayback Machine. The Wayback Machine is primarily designed to back up websites , however, and will often not be able to save information stored in a site's databases , as alluded to in the comic. The Internet Archive has a part for non-website archives, but it cannot hold recent databases either due to copyright problems.
My access to resources on [SUBJECT] over time:
[Below, a timeline and a graph with gray bars is shown:]
[1980s-past 2020:] Book on subject
[Early 2000s-past 2020:] [SUBJECT].pdf
[2000-2010:] [SUBJECT] web database Site goes down, backend data not on archive.org [Small bar, 2000-2016/17:] Java frontend no longer runs
[2010-2015/16:] [SUBJECT] mobile app (Local university project) Broken on new OS, not updated
[2000-2010:] [SUBJECT] analysis software Broken on new OS, not updated
[Late 1990s-late 2000s:] Interactive [SUBJECT] CD-ROM CD scratched; new computer has no CD drive anyway.
[1980s-past 2020:] Library microfilm [SUBJECT] collection
[Caption below the panel:] It's unsettling to realize how quickly digital resources can disappear without ongoing work to maintain them.


Sky Spotters

Explanation:
This comic explores how people with various hobbies notice strange things in the sky.
In the first panel the plane enthusiasts White Hat and Hairy notice that there is a Piper PA-24 Comanche in the sky (apparently the most recent of several), belonging to a holding company that has filed no flight plans. Flight plans do not need to be filed for many short flights at lower altitudes in good weather, so for a small aircraft like the PA-24, the missing flight plan alone should not be unusual. Many government or company planes used for secret purposes, like FBI planes registered to fake companies , go a step further and are blacklisted from major databases. Regardless, it makes White Hat and Hairy wonder why, enough that they decide to post about it on their plane spotter forums. (See 1669: Planespotting ). The reference to red trim on the Piper PA-24 Comanche could be a reference to the livery of Janet Airlines which operates clandestine flights between Las Vegas , Area 51 , and other desert military bases , although these planes are in fact registered to the Department of the Air Force , rather than a holding company.
In the second panel Hairbun and a male bird enthusiast are wondering why there is a broad-winged hawk in the area in November when many broad-winged hawks should have migrated south to areas like Florida and Central America. They decide to send a message to their birdwatching e-mail list. (See 1824: Identification Chart and 1826: Birdwatching ). The two birdwatchers in this panel look like the old version of Cueball and Megan in 572: Together .
In the last panel, a committee from what appears to be the National Security Agency wonders how to disguise their drones so that people will not pay attention to them. The boss at the end of the table is lamenting the fact that both their bird- and plane-disguised drones have been noticed because of all these people constantly checking out the sky, also indicating that there are even more subcultures who are obsessed with things in the sky than the two mentioned already. Ponytail asks what else they could disguise their (secret) surveillance drones as, and Cueball suggests a weather balloon . But Ponytail shoots this down, since such a disguise would attract both the UFO enthusiasts and the "weather people" (presumably some regulation board that checks unauthorized use of meteorological survey balloons, or otherwise hobbyist meteorologists or perhaps even members of the Cloud Appreciation Society ). She then jokes that she doesn't know which is worse. Since most people consider UFO enthusiasts to be into conspiracies, the "weather people" may be annoyed by this. Maybe Randall is indicating that people trying to predict the weather are correct as often as those claiming to have seen a UFO...
There are numerous instances of weather balloons being labeled as UFOs by enthusiasts, one of the most notable being the Roswell UFO incident , which for years was explained by the US military as a weather balloon crash, but turned out to be a nuclear test surveillance balloon. It is now known as the most thoroughly debunked UFO claim .
In the title text, it is suggested that "lost birthday party balloons" should not attract too much attention. But then it is noted that it might make marine wildlife people angry, their concern probably being that balloons ultimately end up in some water body, which causes marine wildlife to get trapped in plastic and other synthetic material that was dumped in the water. (see Marine debris ) "Marine wildlife people with sharks" may be a reference to 585: Outreach , which also features a balloon carrying a shark. Another possible issue with disguising drones as "lost balloons" is that such balloons are quite rarely seen, and a sudden increase in the number of "lost balloons" seen would certainly raise suspicion even without a "spotting community" that focuses on them.
Among other types of people looking at the sky, the comic doesn't even get around to mentioning the subject of comic 1644: Stargazing .
[White Hat and Hairy are standing in front of some buildings. White Hat points to the sky while holding his smartphone in the other hand, while Hairy holds his smartphone up in both hands as he looks at the screen.] White Hat: That's odd—another PA-24 Comanche with red trim. Registered to a holding company, no recent flight plans. Hairy: I'll ask the forums if anyone knows who operates those.
[Hairbun and an old man with a white sailor cap are standing in a field with rolling hills behind them. Hairbun is looking at the sky through her binoculars, which she has on a string around her neck. The man also looks up but he is holding his string attached binoculars down in front of him.] Hairbun: Goodness, I think that's a broad-winged hawk! Man with sailor cap: In November?! They should be long gone by now! Hairbun: I'll email the list.
[Five people sit around a table in a boardroom, which presumably belongs to the government as the table has a circular insignia with an eagle in the center and unreadable text in the ring around the eagle and beneath the insignia. A man with slick black hair is sitting at the end of the table in an office chair. The other four are sitting behind the long side of the table; from the left they are Cueball, Megan, another version of Hairy with spikier hair, and to the right, Ponytail.] Man at the end of the table: Dammit, why are there so many different subcultures obsessed with staring at the sky? Ponytail: What else could we disguise our surveillance drones as? Cueball: Weather balloons? Ponytail: No, that gets the UFO people and the weather people. Ponytail: Don't know who's worse.


Defensive Profile

Explanation:
This comic demonstrates a theoretical feature which provides more honest interpretations of social media profiles. We see a profile for a person who says they have “no filters” and has no qualms about offending or upsetting anybody with their seemingly radical views. But the “translation” of the description reveals that it is a vastly insecure person who seems to have the problem of saying the wrong thing every time and so their profile description is a way for them to justify their comments.
The title text continues, with the aggressive “NO DRAMA ZONE” turning out to mean that the user is merely trying to keep any offended or genuinely upset comments away from their page because they simply have no idea how to emotionally handle hurting someone’s feelings.
Randall previously demonstrated another theoretical feature to address passive-aggressive behavior in 1085: ContextBot . And show Cueball having the same feeling in 1984: Misinterpretation .
The comic’s feature may be based on the context menu option of the Google Chrome web browser to have a foreign language webpage translated to the user’s selected native language. However, in Google Chrome, the user may only translate the entire page, while in this comic the user may also select some text and have only the selected part translated. Also, Google Chrome uses Google Translate for translation by default, which cannot read minds like in the comic yet (though it might be able to someday, given how much information Google has control over). However, if one uses the official Google Translate extension for Google Chrome, one may actually translate only the selected text. It is possible then that it is instead the extension which inspired the comic’s feature.
This comic not only illustrates such a feature, but implies that the “translated” thoughts are what’s actually going on behind posts of these types on social media, as if Randall can actually read those people’s minds somehow. If this implication is the intent of the comic, then Randall thinks that people who have “no filter” are actually insecure and that people who want “NO DRAMA” are actually afraid of upset comments. Alternatively, Randall hates people who post such things in their profiles, and therefore wants to belittle them in this comic as actually being insecure, rather than being as confident as their aggressive behavior implies. This explanation is corroborated by notable news near the comic’s publishing time (see below).
The style of the profile showcased in the comic resembles the profiles of the popular social media website Twitter, which while the user is logged in, shows the user’s own profile on the left side of the page in a similar style to the comic, with their picture on the left side of their name, their Twitter handle under their name (which explains the extra line of text under what is presumably the name) and their “bio” right below those. The Twitter “bio” is a space usually used for the user to explain who they are. Common details about a person which are included in their “bio” are their profession, their personal interests and the products they have for sale. Some people also write about their personality, such as the one in the comic, which is quite outspoken and frank about her opinions.
The title of this comic is “Defensive Profile”. “Defensive” is the opposite of “offensive”, which is a word that might be used to describe the contents of profiles which display such a warning as in the comic. However, the feature reveals the warnings to actually be defenses against behaviors that deeply bother the profile owner. The profile is thus proved to actually be “defensive” instead of “offensive”, at least regarding the warning text.
[A profile on an unknown social media site is displayed. The profile picture is a close-up image of Megan. The profile reads:] I speak my mind and don’t care who I offend. No filter.
[In the next panel, the text is highlighted, and a context menu has appeared. There is a mouse pointer on the option "View translation".] Copy Select all View translation [selected] Print
[In the last panel, the profile text is updated:] I don’t understand why people keep getting mad at me and I’m using this pep talk to convince myself that’s okay.


Thermostat

Explanation:
Hairy is working at a tech support office, and receives a call from Cueball . After the scripted greeting, Cueball, who has the most bizarre tech issues , tells Hairy that his thermostat – a single-purpose device used to control indoor heating and air conditioning – is showing an error screen from the Android operating system , and asking if he wants to partition the volume. The Android error seems to imply that it is trying to mount a file with .doc extension (likely a Microsoft Word document ) as the boot device . An added twist is the "(1)" in the filename, which is commonly appended when a user attempts to copy a file into a directory that already has a file with the same name. Furthermore, the extension .docx has been the default option from Microsoft Office 2007 onwards rather than the earlier .doc extension used in the comic, implying that the file is likely a rather old one.
The error message suggests a system problem at a low level of the device. Not only is the operating system missing, but the device is trying to locate the operating system inside a Microsoft Word document, something that has little to do with regulation of temperature and probably has no way of getting onto the device in the first place, let alone being considered as a bootable file.
This is so abnormal that Hairy is briefly struck silent and, upon recovering, he suggests Cueball walk into the sea as a form of suicide, rather than try to solve the issue.
The title text elaborates that the situation is so absurd that it must be divine punishment, so Hairy does not want to try and help him for fear of invoking the wrath of whatever deity is issuing it. An example of such reasoning in literature can be found in the character of Aeolus in the Odyssey , who, having made an unsuccessful attempt to assist Odysseus by giving him a bag containing unfavorable winds, refused to provide further assistance on the grounds that the gods were clearly hostile to Odysseus.
Part of the humor is in the problem being only a slight exaggeration of real software issues. The symptoms are unlikely, yet possible (a thermostat could be running Android and could generate a report as a .doc file; given some data corruption, the name of the .doc file could get into the boot script and a volume could appear unpartitioned). It would take an expert Android or Unix engineer to fix, particularly on an embedded device with no obvious way to connect remotely or attach a keyboard. In real life, it would probably be easier to just replace an embedded device whose software was this broken.
This is explored further in 2083: Laptop Issues where throwing Cueball into the ocean is mentioned. Both comics could explain the original "computer problem link to oceans" comic 349: Success .
[Hairy, with a headset on, is sitting in an office chair at a desk with his hands ready on the keyboard of his computer.] Hairy: Tech support, how can I help you?
[Cueball is on his smartphone while looking at a small blinking panel on the wall in front of him.] Cueball: The little LCD on my thermostat says Error: Android system recovery: Unrecognized boot volume "/MONTHLY ENERGY REPORT (1).DOC"
[In a frame-less beat panel Hairy just stares at his screen with his hands on his lap.]
[Back to Cueball, now with Hairy's reply coming from the smartphone in a box with a jagged arrow pointing to the smartphone.] Cueball: It's asking if I want to partition the volume. What should I do? Hairy (on the phone): Have you tried walking into the sea.


A ?

Explanation:
After the update to Apple's iOS 11.1 , many (though not all) iPhone users suffered from a strange bug, where the autocorrection changed any input of the single lowercase letter "i" to either "A" or "!" followed by a space and a Unicode variation selector 16 (U+FE0F, on iOS displayed as a question mark in a square). [1] Using a replacement character (U+FFFD) to approximate this display, the result of typing "i took" might be "A � took" or "! � took". In a handwritten text, the "�" symbol could then be mistaken for a censored word, signifying indignation against the person taking out the trash. This problem previously manifested as an "I" followed directly by the VS-16 "emojify character", turning them into an " �" without the "A". [2]
The note in this comic is the equivalent of starting a text message with "i took out..." and triggering the iOS bug. The joke revolves around acceptance of the bug through repetition has influenced the writer's hand written style.
The codes in the title text refer to "A �" and "! �" respectively. The text provides a way to keep the "bug" active with the U+FFFD approximation, (which can be realized through the use of a Cydia tweak) even after it is patched. Although this would have no practical use, it is still a fun way [ citation needed ] for iPhone users to keep the infamous bug fresh in everyone's mind, and to make sure that the Apple company never lives down the embarrassing incident.
The statement in the title text "no update can never take this away from you" is a double negative , which is a considered non-standard grammatical use in modern English, although common in many dialects.  Taking literally it could actually mean "any update can take this away from you". This may be a typo or a colloquial use, with the intended meaning to be "ever" instead of "never" with some exaggeration.
[A picture of a yellow post-it note with a handwritten message:] A ⍰ took out the trash but the dishwasher still needs to be run
[Caption below the panel:] Apple can try to fix the autocorrect bug, but I've already incorporated it into my handwriting.


Twitter Verification

Explanation:
Some Twitter users (such as Randall Munroe , Coldplay , and, prior to being suspended, Donald Trump) have a verification checkmark next to their name.  This checkmark is used to indicate that the user is who they say they are, rather than being a fake account made by someone else using their picture and name. This helps fans find the real accounts of their favorite celebrities. However, since the most notable people benefit from this the most, there is some ambiguity in the granting of the verified mark, as it also seems to be interpreted as a status symbol to indicate the notable celebrities. Some even see this as Twitter actively endorsing the user. For this reason, Twitter has removed verified checkmarks from real accounts of celebrities because of political controversies in the past. Examples of this are political commentator Milo Yiannopoulos (before he was banned from the service). One recent controversial decision regarding the verified mark is that Twitter gave a verification checkmark to Jason Kessler , the organizer of a recent far-right rally in Charlottesville, Virginia.  This drew attention to Twitter's verification system, so they temporarily suspended it.
The alt-text comments on the lack of foresight on Twitter's part when implementing the verified system: as it by design separates users between an in-group and an out-group, it seems to imply endorsement or, at least, favors some users to the detriment of others. This in turn automatically creates the twin sets of "people who shouldn't have been verified, but were" and "people who deserve to have been verified, but weren't." As the internet is populated by various large and strongly opinionated groups [ citation NOT needed ] , neither set will ever be empty and Twitter will always be seen as either endorsing unworthy or snubbing worthy people.
The last line of dialogue is a typical English sentence and has nothing to do with the Twitter Moments feature, which can be used to compile several tweets with a shared theme into a browsable gallery. The character depicted is the (at the time of publication) Twitter CEO Jack Dorsey , judging by the beard.
[A bearded figure, depicting the Twitter CEO Jack Dorsey, is standing behind a podium with the blue Twitter bird logo.] Jack: Everyone calm down— Jack: We just need to go figure out how to bestow a global in-or-out status badge on some people, at our discretion, without anyone reading anything into who gets one. Jack: This should only take a moment.


Nightmare Email Feature

Explanation:
Most modern email clients provide tools to help their users read, write, and keep track of email efficiently. For instance, the user may receive a notification if the email body contains wording that suggests a file has been attached, but there is no actual attachment, in order to prevent them forgetting to include the intended file in the email.
This comic suggests a similar feature, one which would inform not the user, but the recipient of the message, how long the email has been revised before being sent. This is an expansion of a common feature of collaboration tools used by law firms, and modern word processors such as Microsoft Word 2016. Randall calls this his nightmare email feature, implying he spends too much time in revision of what should be simple email messages and that making himself - or worse, the recipient - aware of the actual time would make him anxious.
In the case shown it seems that the sender and recipient of the e-mail had recently met, and the recipient suggested meeting again this weekend. It then took 47 minutes to write a short reply in which the sender ends up saying only that they enjoyed the thing referred to, but, alas, they have no time this weekend, and then lets the other suggest a possible time for a dinner... or something. Of course there could be more to the email above the panel, but it seems to be a very short answer to another e-mail, and it increases the nightmare for the writer (and the impact of the joke) if this was all that was written in 47 minutes.
If the text had been written out in less than 2 minutes, it would not have been a problem, but it seems the writer of this e-mail had to think a lot about how it was phrased. This could lead the recipient to wonder what took so long. Was it that they did not enjoy it, but ended up writing this to be nice? They only write that they are busy this weekend, thus not giving any reason as to why, and the last part allows them the possibility of also being "busy" on whatever time is suggested for dinner. Also, "or something" is very non-committal. Alternatively it could be the opposite, for a case where the writer enjoyed the time a lot, and is really looking forward to another meeting, but tries to seem relaxed and open minded, to not scare the other person away. All of this would also be true if it had been written in 2 minutes, but then at least there would have been the excuse of not having spent a lot of time thinking about how the reply was phrased.
The title text describes a similarly uncomfortable feature, which would inform the recipient how long a message has been sitting in the user's drafts folder, thus highlighting their procrastination, as well as demonstrating that "(...)didn't see your message until just now" is a lie, or at least it was only true when the original message was written, and now three days later another message should have been written instead. This feature would also be able to catch anyone who tries to avoid the feature depicted in the comic by saving the email in "drafts" while making revisions outside the mailing software, either mentally or in another word processing program.
Randall has explored a related anxiety-inducing feature of instant messaging in 1886: Typing Notifications .
Applying the feature in the comic to this explanation: it sat incomplete in this wiki for approximately 2 months and 26 days (since the comic's creation), before an unregistered user removed its incomplete tag.
[A panel with a short email message, with the first line partly obscured by the top of the panel. Below that, in light gray font, is an information message from the email client.] Enjoyed it! I'm busy this weekend, but let me know if you're free sometime next week and want to get dinner or something.
Total time spent revising this email before sending: 47 minutes 12 seconds ...
[Caption below the panel:] My nightmare email feature


Temperature Preferences

Explanation:
This is a chart of major (and not-so-major) populated areas showing seasonal temperature patterns. The chart is a guide to where one might like to live depending on how much summer heat and winter cold they enjoy. There are four focused zones:
The summer heat axis is determined by humidex , a system that combines heat and humidity to generate an estimate of perceived "summer discomfort".
Note that if the values from this table are charted, the result is similar but not exact to how Randall drew the comic.  For instance, he shows Kinshasa as having a “colder” winter than Honolulu, but the average low in the coldest month for Kinshasa (20°C) is hotter than the average low in Honolulu (18.9°C).  In general these differences are minor, but a few stand out:
It is not certain if these differences are a due to errors, the use of a different data set, or deliberate “Easter Eggs” set to see if anyone would notice.
According to Randall:
However, given the great variability of weather patterns across the globe, it's not altogether clear how useful this would actually be to someone looking to choose where to live, since it's not clear exactly what "love/hate hot/cold" would mean.  It's also not clear that the relationship between temperature and discomfort is linear. More likely is that there is a small temperature band where each degree of change causes significantly more discomfort, and beyond which it's just "too hot/cold".
Hottest and coldest month therefore may not be the best measure.  For example, is one or two very cold days better or worse than a month's worth of moderately cold days?  Shown in the table below for each place are the number of days above 32°C (90°F) and the number of days below 0°C (32°F), taken from Weatherbase.com (Randall's source).  For most people a temperature above 32°C is considered hot and a temperature below 0°C is considered cold.  So, for instance, someone who loves heat might want to live in Tehran (with three months above 32°C) rather than Beijing (with only one month) even though the peak month Humidex in Beijing is higher.  Someone who loves cold might want to live in Santa Fe, where it never gets particularly cold (only -8°C) but where it is below freezing almost half of the year (179.8 days on average).  In general though, the places with the most hot or cold days also have the hottest and coldest extremes.
Once again, Turpan stands out for its misery, with days above 32°C totaling four months and days below 0°C totaling four months.  In fact, on average there is at least one day every month of the year that the temperature is either above 32°C or below 0°C.  This includes almost every day in June, July and August being hot and every single day in December, January and February being below freezing.
Some of the most extreme climates on earth are not shown on this comic, however, perhaps because some of them are uninhabited. Eismitte (a camp established in the center of Greenland in the 1930s) and Vostok Station (in the center of Antarctica) both see temperatures far colder than McMurdo, although being in the middle of ice caps neither can be inhabited without outside support.  The areas around Oymyakon and Verkhoyansk in eastern Siberia also see temperatures colder than McMurdo and are actual towns, although summer temperatures are much higher.  In both places the summer weather is generally average (Humidex of 22°C to 23°C) but they have seen record highs of 34°C  to 37°C  and record lows of almost -68°C, giving them the greatest temperature swings on earth. Bouvet Island is a small island in the South Atlantic Ocean, near the latitude where there are no land masses to interrupt storms and currents (south of South America but north of Antarctica).  As a result it has one of the most consistent climates on earth, with a high and low almost always within a few degrees of 0°C all year long – a perpetual state of almost to just freezing, combined with clouds, fog, wind and rain from ocean storms. Death Valley in California, Shahdad in Iran, and Murzuk in Libya all vie for having the highest temperature in the world, although not the highest Humidex.
The relevant temperature data for these extreme locations, where known, is in the second table for comparison.
The title text refers to a quote sometimes attributed to Mark Twain ; however, as it points out, the quote is misattributed , and it is unknown who created it. The text then goes on to claim that the person who originally said the quote never visited McMurdo Station , a US Antarctic research center, which is certainly a colder place than San Francisco.
The comic as originally published had a "smudge" or scattering of gray pixels, visible in the center of the image between the labels for Madrid and Lubbock. A new version of the image was later uploaded with this removed.
By editing the image to increase the contrast between the background and the "smudge", as shown here, it is possible to see dots and grid lines. This would seem to be a scatter graph, likely one showing temperature data used by Randall as a reference while making this comic, and accidentally left visible when the comic was first uploaded. A similar thing happened in 1561: Water Phase Diagram , where a phase diagram from Wikipedia was faintly visible in the original version of the comic .
[A chart labeled:] Where to live based on your temperature preferences [In gray, the data source is mentioned below:] Climate data from weatherbase.com
[A chart with two lines with single arrows. Each arrow is labeled:] Y axis bottom: Cold winters X axis right: Hot/humid summers (measured via Humidex, which combines heat and dew point)
[Near each of the corners of the chart there is a gray blob, labeled:] Top left: If you hate cold and heat Top right: If you hate cold and love heat Bottom left: If you love cold and hate heat Bottom right: If you love cold and heat
[The following city names intersect with the top left blob [hate cold and heat] (in reading order):] Mexico City Quito Addis Ababa Bogotá San Francisco Wellington
[The following city names intersect with the top right blob [hate cold and love heat] (in reading order):] Bangkok Ho Chi Minh City Manila Singapore Mumbai Jakarta Dar Es Salaam Honolulu Lagos Rio [de Janeiro] Dhaka Kinhasa Miami Karachi Dubai Cairo Hong Kong Delhi Riyadh Guangzhou Lahore Sabha Houston Needles El Paso Baghdad Dallas
[The following city names intersect with the bottom left blob [love cold and hate heat] (in reading order):] Reykjavik (with arrow pointing left) Berlin Stockholm Oslo Calgary Halifax Daqaidam Kiev Casper Yumen St Petersburg Volgograd Moscow Ottawa Vladivostok Thunder Bay Duluth Urumqi Altay Regina Irkutsk Abakan Ulaanbaatar Blagoveshchensk (also on bottom right blob) Fairbanks McMurdo (with arrow pointing down-left) Yellowknife (with arrow pointing down) Hailar
[The following city names intersect with the bottom right blob [love cold and heat] (in reading order):] [Washington] DC Shanghai Tehran Saint Louis New York Xi'An Salt Lake City Kansas City Beijing Seoul Sapporo Pyongyang Sioux Falls Turpan Jinzhou Minneapolis Shenyang Fargo Tongliao Qiqihar Blagoveshchensk (also on bottom left blob)
[The following city names do not intersect with any blob (in reading order):] Nairobi São Paulo Brisbane Los Angeles Perth Cape Town Sydney Athens Santiago Barcelona Melbourne Rome Buenos Aires Jerusalem Atlanta Raleigh Madrid Chengdu Tokyo Dublin Portland Richmond London Istanbul Edinburgh Vancouver Paris Flagstaff Santa Fe Tashkent Wuhan Geneva Lubbock Boston Budapest Kabul Toronto Omaha


How to Make Friends

Explanation:
This comic follows a sample interaction, purportedly showing how to make friends. We see Cueball 's strategy for making friends. It does incorporate various points of advice for building friendships, which are completely sound in the abstract. But it's clearly not helping him -- he's out of sync with the interaction context and makes bigger social gaffes by following the abstract advice. Escalating awkwardness ensues.
It starts out with a common way of making friends or interacting with friends, hanging out over a meal. However, Cueball suggests doing so with awkwardly literal phrasing; whereas most people use expressions such as “have lunch” or “grab a bite to eat”, Cueball explicitly invites Hairy to “eat food”. The fact that he feels the need to clarify that they’ll be eating food, as opposed to any other orally consumable items, indicates his lack of confidence to clearly communicate his intentions.
Before Hairy can even respond, Cueball then says that they could instead “sit together and talk without eating.” Although this is indeed another common way to make friends, it’s kind of an odd way to phrase it, especially since he didn’t even give Hairy a chance to reply to his initial suggestion. Cueball then says he doesn’t need to eat (meaning not right now , especially as a prerequisite to talking), but he immediately feels compelled to clarify that he does need to eat (meaning in general ). Again, it’s weird that he clarified, as his original wording probably would have been understood. He then awkwardly remarks about how he can eat later if Hairy would rather just talk. The overall implication is that Cueball’s awkwardness and over-explanation would put off a typical person, although some people find it endearing .
This is a situation that Randall has encountered before, in 1746: Making Friends , in which he offered "advice" to play dead to attract new friends and/or turkey vultures; presumably he has "learned" from his unsuccessful attempts and is trying more conversational approaches, but apologizes to the reader as he hasn't quite figured that out either.
The title text says Cueball wants to be friends at Hairy, rather than with him, which isn’t how friendship usually works. “At” implies that Cueball considers being friends to be a unilateral action that he needs to direct towards Hairy, like “smiling at” or “pointing at”, and does not understand that it is typically a mutual activity of building a relationship, which would be indicated by being friends with him. “At” can even carry a degree of animosity (compare: “he just phoned up to wash his head at us” ).
[First panel with words, with the words in the center white and on a black oval background, which is in turn on the white background:] Presenting:
How to make friends
[Second panel with Cueball and Hairy facing each other:] Cueball: Want to go eat food together? Cueball: We could also sit together and talk without eating. I don't need to eat. I mean, I do need to eat. But if you don't want to eat then we can just talk. I can eat later.
[Third panel with words, same format as first panel:] Okay
It turns out I still haven't figured out how to do this.
Sorry


NEXUS

Explanation:
Cueball is confusing NEXUS , a USA and Canada border control pre-screening program , with Hexxus , the villains from the animated film FernGully .
Trusted traveller programs like Nexus allow people who match certain criteria to apply for a membership and subsequently save time when boarding airplanes or crossing borders via use of expedited lanes.
FernGully is a story set in an Australian rainforest inhabited by fairies including Crysta, who accidentally shrinks a young logger named Zak to the size of a fairy. Together, they rally the fairies and the animals of the rainforest to protect their home from the loggers and a malevolent pollution entity, Hexxus. Hexxus has previously been mentioned in 1750: Life Goals as an especially hard-to-spell word and in 1767: US State Names (as a replacement for Texas).
The title text is confusing Cisco (a telecoms & tech brand which has a line of switches called Nexus ) with:
[Megan and Cueball walking through an airport.] Sign: Apply for NEXUS Save time at the border Megan: Maybe we should sign up for this. Cueball: No way. I refuse to have anything to do with Nexus after what they did to FernGully.


Interstellar Asteroid

Explanation:
ʻOumuamua is the first detection of an interstellar asteroid passing through the Solar System originating from another solar system.
Megan 's list of objects with a similar shape ratio:
As soon as Megan lists off the last item, she is about to start speculating within her own speculative scenario about who or what might be in the coffin before Cueball interrupts her. Cueball attempts to bring Megan back down to earth by reminding her that she has too little data to work with (one data point), but Megan is far too excitable to listen to reason. A good example of the dangers of speculating irresponsibly, it would seem.
It could also be argued that Megan with this makes fun of many news outlets whose first reaction to a new space body often seems to be to search for something to compare its shape to, such as with the 'rubber duck' comet . Making fun of media covering science news is a recurring theme on xkcd.
The title text suggests taking reciprocal action by sending asteroids away when the solar system receives them. This would, of course, be difficult, given the amount of energy needed to shift asteroids outside of the Sun's gravity hold. On top of that, it appears to imply that some non-human entity is sending these rocks, which is an inane idea. This could be a reference to the movie Starship Troopers , where a race of aliens mankind is at war with supposedly hit Earth with asteroids. Given that a typical interstellar traveler -- like the one spotted now in real life -- spends millions of years getting from one star system to another, the movie's idea is plain stupid; in fact, the movie gives no proof the aliens were actually responsible, leading to a common fan theory that the asteroid was indeed random space junk and the aliens are being framed by the human government as pretense for war.
[Megan walks towards Cueball while looking at her phone. Cueball sits in front of his laptop.] Megan: Hey, you know that asteroid that tumbled past from another star system? It's apparently really long and skinny. Megan: Like a ratio of 6:1 or 10:1. Cueball: Weird. Wonder what it's shaped like.
[Megan lowers her phone and looks up. Cueball looks backward.] Megan: Without more data, it would be irresponsible to speculate further. Cueball: So...you're going to? Megan: Absolutely.
[Frameless panel focusing on Megan.] Megan: Here are some objects with a similar shape ratio: Megan: The 1:4:9 monolith from 2001: A Space Odyssey . Megan: A star destroyer. Megan: A huge eggplant emoji.
[Same setting with Megan and Cueball.] Megan: A statue of Weird Al. An iPhone XXXXX. Voltron. Megan: A giant space coffin. But who could be inside? We can only guess. I'll start: Cueball: This is all based on how many data points, again? Megan: One. But it's a perfect fit!


Emoji Sports

Explanation:
This comic, as the heading indicates, arbitrarily selects emoji and uses them to make up very bizarre sports. Although some of these might be completely normal, most of them take things to a completely absurd level.
The title text is a reference to the Triple Crown , which is an highly prestigious award given to a three-year-old thoroughbred horse who wins the Kentucky Derby , the Preakness Stakes , and the Belmont Stakes , the first three of the four listed events. The joke is that if Horse Hole was a real sport, then one who won a major competition for it, the Missouri Horse Hole, in addition to the three main horse racing events, would win a "Quadruple Crown".
Please note that some emoji may not be supported by your browser, in which the emoji will appear as a black rectangle, and if there is a male/female version of the emoji, a male/female sign will appear next to the rectangle.
New sports created from random emoji
[Man Playing Water Polo + Volcano] 🤽♂🌋 	Lavaball
[Woman Playing Handball + Person Fencing] 🤾♀🤺 	Bladeball
[Woman Dancing (2 emojis) + Soccer Ball] 💃💃⚽ 	Fancyball
[Hole + Horse Racing (3 emojis)] 🕳🏇🏇🏇 	Horse hole
[Kitchen Knife + Basketball + Pick] 🔪🏀⛏ 	Basketball shredding
[Egg + Telescope + Woman Detective] 🥚🔭🕵♀ 	Eggspotting
[Skier + Crocodile] ⛷🐊 	Alligator jumping
[Woman + Fishing Pole + Merman] 👩🎣🧜♂ 	Merfishing
[Man + Badminton + Fairy + Badminton + Woman] 👨🏸🧚🏸👩 	Tinkerball
[Curling Stone + Hedgehog + Curling Stone] 🥌🦔🥌 	Hedgehog curling
[Clamp + Hamburger] 🗜🍔 	Burger clamping
[Woman Astronaut + Bow and Arrow + Satellite] 👩🚀🏹🛰 	Consequence archery
[Owl + Right Arrow + Open Mailbox] 🦉➡📬 	Owlstuffing
[Fork and Knife + Candle + Fork and Knife] 🍴🕯🍴 	Candle eating
[Flag in Hole + Bomb + Woman Golfing] ⛳💣🏌♀ 	Consequence golf
[Pointing Right + Snake + Pointing Left] 👉🐍👈 	Snake shaming
[Fire + Woman Climbing + Fire] 🔥🧗♀🔥 	Hell escape
[Video Game + Avocado + Video Game] 🎮🥑🎮 	Multiplayer avocado


The Moon and the Great Wall

Explanation:
This is a reference to the myth that the Great Wall of China is the only manmade object [ citation needed ] that can be seen from the Moon (or from space) with the naked eye. Sadly, it cannot . In fact, it's barely visible from the orbit of low satellites.
This comic mocks the myth by conflating it with another saying about the Moon, and how the Moon's craters and valleys are visible to the naked human eye. Indeed, the Moon is the only celestial body for which this is true, as all other bodies (with the potential exception of the Sun, see the title text) can only be seen as tiny points of light by the unaided human eye. There is nothing special about the Great Wall of China in this factoid, though; the Moon’s features can be seen equally well from practically any place on Earth with a view of the Moon. [ citation needed ]
The title text states that one is sometimes able to see large sunspots if any are present and conditions are ideal. However, looking directly at the sun with the naked eye risks extensive damage to the eye and should NEVER be done. It could, however, be possible to see them when the Sun is seen through a thin cloud cover or maybe at sunset/sunrise. (It's possible to see very large sunspots with solar eclipse glasses or other adequate protection , but that's not unaided human eye.)
[Megan is holding her arm up towards Ponytail as they stand atop a large brick wall with merlons along the top. They are standing to the left of a tower with three small windows as well as merlons on the top.] Megan: Did you know that the moon's craters and plains are the only structures on the surface of a celestial body that can be seen with the naked eye from the Great Wall of China?


Interferometry

Explanation:
Interferometry is the practice of overlapping two different waves to get a different signal, which can be used to determine the distance between two reflecting surfaces. An astronomical interferometer uses this principle to build an array of separate telescopes that are able to work together as a single telescope, effectively providing higher resolution using a process known as aperture synthesis .
In the comic, Beret Guy and Cueball are walking Beret Guy's dogs when Beret Guy makes a comment on how interferometry is really cool. Beret Guy states that two dogs placed at a consistent interval will function as a larger dog — a play on the astronomical interferometer. While this idea works on waves, it probably won't work on dogs [ citation needed ] (though since h/p=λ it might), which is why Cueball is confused and starts to correct him. Before he can respond, however, Beret Guy jumps on his "large" dog and appears to be floating in midair. The existence of large dog is further proven when it gives out a large bark. Cueball looks on speechless while Beret Guy appears to exhibit another of his strange powers .
In 1614: Kites , Beret Guy is "walking" a dog. It is possible that one of the dogs in this comic is the dog from Kites.
The title text states that the effective giant dog is not any more 'good' than the two original dogs. This is analogous to sensitivity for astronomical interferometers. Interferometry does not increase the light-gathering area, so it cannot view dim objects as well as a single large telescope could. This is also a reference generally to dog-owners calling their dogs "good dog" or "good boy/girl" when they behave well; presumably, Beret Guy's giant interferometry dog is only as well-behaved as the dogs they are derived from. (However, as interferometry does collect more light than any individual telescope used, the interferometry dog is presumably more good than either individual dog. Considering the destructive potential of a giant bad dog, this is a good thing.) It may also be a reference to the They're Good Dogs, Brent meme.
[Cueball is walking behind Beret Guy, who is walking two small dogs on two leashes.] Beret Guy: Interferometry. Is so cool!
[They stop and Beret Guy is holding the leashes in his hand. He has taken them off the dogs and points at the dogs, which he has placed facing outward so they are standing a couple of paces apart. The distance between them is indicated by a labeled line.] Beret Guy: If you put two small dogs a large distance apart, they can function as a single giant dog. Line: d
[Cueball begins to speak but is cut off by Beret Guy yelling as he jumps into the space above the two dogs, with each leg a good distance above one of the dogs. (The leashes have disappeared, as well as the distance line).] Cueball: I'm not sure that's- Beret Guy: Hyah!
[As Cueball watches, Beret Guy floats on top of the invisible giant dog about a meter above the two small dogs, and then rides away with the two small dogs still seen below as they run to the right, leaving Cueball standing in the dust the "big" dog creates in its wake. The invisible giant dog barks from a position just in front of Beret Guy's face, far above the two small dogs.] Invisible giant dog: WOOF Beret Guy: Away!


Felsius

Explanation:
Just like in 1292: Pi vs. Tau , Randall tries to unify two measurement systems by averaging both values, with little success (however this is a matter of opinion).
There are several temperature scales actively used in different parts of the world of for different purposes, including Celsius and Fahrenheit , but e.g. also Kelvin and Rankine .
The debate on whether to use Fahrenheit or Celsius is, just like the one between United States customary units (which uses Fahrenheit), imperial units (outdated system that used Fahrenheit), and metric units (which use Celsius or Kelvin), one that is mostly restricted to the US. While Fahrenheit is a widely used temperature scale in the US, most other countries have already switched from Fahrenheit to Celsius or have always used Celsius. In scientific circles, even in the US, only Celsius (and Kelvin) are used.
The conversion factors between Celsius and Fahrenheit are:
°C = (°F − 32) × 5 / 9 °F = °C × 9 / 5 + 32
which makes the average (mean) value of °C and °F: °⋲ = °C × 7 / 5 + 16.  The step-by-step derivation of this is:
°⋲ = (°C + °F) / 2 = (°C + (°C × 9 / 5 + 32)) / 2 = (°C + °C × 9 / 5 + 32) / 2 = (°C × 5 / 5 + °C × 9 / 5 + 32) / 2 = (°C × (5+9) / 5 + 32) / 2 = (°C × 14 / 5 + 32) / 2 = °C × 7 / 5 + 16
Randall chose to name his new unit of temperature Felsius (a portmanteau of Fahrenheit and Celsius).
Comically enough, the Felsius scale discards the main advantages of either temperature scale. The Celsius scale is based around 0 °C as the melting point of water and 100 °C as the boiling point, which is an advantage Felsius does not preserve. Fahrenheit is often argued to be a convenient temperature measure for human comfort, as 0 °F is very cold and 100 °F is very hot. Many places on earth which humans inhabit fall reasonably well within these extremes the majority of the time, but Felsius does not preserve this advantage of the Fahrenheit scale either.
The title text states that the symbol he chose to represent this unit also is the average of two other symbols. Visually, it is assumed to be a combination of Celsius and Fahrenheit (a C with a crossbar), but it is actually the unrelated symbols for the euro (€) and the Greek lunate epsilon (ϵ). Randall's symbol has a single crossbar, like the Greek lunate epsilon, but the crossbar continues to the left, like the Euro symbol. (In this explanation and the transcript, we have used the mathematical symbol U+22F2 , which may appear too large or too small depending on the font.)
In doing all this, Randall has fallen into the trap of creating a new temperature scale/standard: see 927: Standards .
Randall has also compared Celsius and Fahrenheit scales earlier in 1643: Degrees and in 526: Converting to Metric he tries to give users of the Fahrenheit scale an idea about what a given Celsius temperature would feel like.
This is an example of Argument to Moderation , also known as the false middle point fallacy.  A famous use of this fallacy is in the Bible, the Judgment of Solomon .  The true mother of a disputed baby is discovered [1] by proposing the "compromise" of cutting the baby in half. Perhaps Randall has a similar strategy in proposing Felsius, an absurd compromise, in order to somehow discover the "true" temperature scale.
Note that this is not the first time Randall has proposed a controversial third way .
[A thermometer is shown where the temperature is indicated, with a red column of liquid, to be just above room temperature. This can be seen from the five labels belonging to five lines pointing at the scale. None of these coincide with the 14 ticks on the actual scale for the thermometer. Below the last label is the formula for calculating the temperature on this scale.] 92°⋲ world heat record 68°⋲ body temperature 47°⋲ room temperature 16°⋲ water freezes –9°⋲ 0°F °⋲=7×°C/5+16=(7×°F–80)/9
[Caption below the panel:] Since the Celsius vs Fahrenheit debate has proven surprisingly hard to resolve, as a compromise I've started using Felsius (°⋲), the average of the two.

An implementation of Felsius is available at Weather In Felsius , using a location based on user's IP address and accepting US ZIP codes (permanent dead link).


Solar Panels

Explanation:
This handy decision tree aims to help in finding out whether a given object should have solar panels installed on it.
The root question is whether the object of choice moves. If it doesn't and has no nearby empty space that would be more practical for the solar panel installation, then yes, the object should be equipped with the solar panels. If the object is static, but you could more easily install the panels somewhere else nearby, probably that's the best place. An example of this is a slanted rooftop of a house or a field on a hillside: it's certainly possible to put solar panels there, but if a flat surface, like a flat-roofed house or a level field, is available, it would generally be easier to put them on that. This way, you can select the optimal direction for the panels to face, which might not be possible on a given incline, or even have them move to track the sun . However, if the house has a side that is turned towards the sun (south in the Northern hemisphere) then a house roof could be even better than on the ground, which is why the title text says "sure" for rooftops. For another example of things where "putting next to it" instead of "on it" is generally the easier (and arguably better) option, see the "highway surfaces" of the title text.
If the object moves, the next question is whether its batteries can be recharged or swapped with ease, in which case batteries may be a better option than solar panels, if the purpose of the panels is to power the object. The idea is that solar panels on a vehicle sound like an interesting idea, but batteries can be much more easily (and economically) recharged from a fixed electrical station than using solar panels on the vehicle as a power source. It may be possible to have solar panels on the electrical station , but that is a separate device to consult the table on.
Finally, if the object moves and batteries are not an option, the last question is whether the object heats up during operation. If so, solar panels may not work well. Randall doubts it mockingly, see also the title text regarding his Haha Good luck final option.
Solar panels can only produce electrical power equal to about 20% of the solar radiation they receive. Thus, a device that heats up during use likely consumes much more power than the amount which could be produced by solar panels covering its surface - so "good luck". Obviously, many animals are also "moving objects" fitting this condition, and installing solar panels on them is bound to be a challenge.
Moreover, solar panels do not work effectively when excessively hot [1] (solar panels are typically designed to operate in temperature ranges of 15-25 Celsius, 59-77 Fahrenheit, 288.15-298.15 Kelvin, 518.67-536.67 Rankine, 12-20 Réaumur, 15.38-20.63 Rømer, 127.5-112.5 Delisle, 4.95-8.25 Newton, 5.968 546×10⁻²¹ - 6.174 608×10⁻²¹ joules of translational kinetic energy or 37-51 Felsius ).
But if changing batteries is not an option, and heat production and power requirements are low, then solar panels can be an excellent solution on a moving object. An excellent case for this is on space probes and satellites, which are typically powered entirely by solar panels (and reliably receive sunlight, because there are no clouds to interfere). Randall is well aware of this, as shown with the comics 695: Spirit and 1504: Opportunity about the two solar-powered Mars rovers , although in this comic he seems to have only been concerned with Earthbound objects.
The flow chart, however, does not mention if the thing in question actually needs solar panels, but according to the title text it works very well, and thus Randall implies that if the answer is sure then it is relevant to put solar panels there. The more solar panels in place, the fewer fossil fuels are needed, and this is in line with Randall's general interest in reducing climate change .
The title text suggests that this flow chart is very broadly applicable to anything the Sun hits.
Rooftops are classed as "sure", and those are, indeed, an active subject of solar installation (though, if there's suitable land nearby, it might not be the most efficient).
Highway surfaces are classed as "probably not".  There have been proposals and experiments a concerning photovoltaic pavement covering roadways with solar panels , but these have proven to be impractically expensive and prone to damage.  The flow chart suggests that, since many highways are near land that could be used for solar panels, that will usually be the more viable option.
Sailboats are classed as "maybe".  Unlike boats with motors, sailboats don't consume enough power to heat up, only requiring enough power to provide electricity for whatever equipment and appliances are on board. Since some sailboats are at sea long enough that swapping or recharging batteries may be difficult, solar panels could be a viable option.
Multiple other moving objects, including jets, cars, and wild deer ends up on the haha good luck result.  While these examples seem unrelated, they all have the same limitation: they consume far more power while moving than could realistically be harnessed from solar panels (as demonstrated by the fact that they noticeably heat up).  There are some experimental solar-powered cars, but these tend to be exceptionally low power (and resultingly low-performance) vehicles. Wild deer are clearly a humorous option, as they'd have little use for the electricity from solar panels, and would likely resist any efforts to install them.  Nonetheless, Randall includes them to make the point that the chart is effective, even with ridiculous examples.
[A flow chart that features four questions in bubbles. Each question has yes/no options in bubbles overlain to the left and right on the question bubble. Curved arrows points from the yes and no bubbles to either the next question or the result. The result written at the bottom is not inside bubbles. The chart has two main branches, that ends up in five places using only four different results, as the middle result is shared by both branches. Above the chart, there is a caption:] Should I put solar panels on it?
Does it move around? Yes Does it have regular chances to recharge or swap batteries? Yes Probably not No When running, is it hot to the touch? No Maybe Yes Haha good luck No Is there an empty space nearby where it would be easier to put them? Yes Probably not [Uses the same sentence as the one in the first branch.] No Sure