Alternate Histories

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


XKeyboarCD

Explanation:
In the same vein (and with the same humor) as the xkcd Phone series , the XKeyboarCD seems to be an overly inventive and borderline ludicrous keyboard intended for some unknown audience. It has an assortment of features (some fairly normal, some more exotic) which give it a..."diverse skill set". This may be in reference to Space-cadet keyboards which were made for programmers and had several keys not present on standard QWERTY keyboards.
XKeyboarCD is a play on xkcd, and keyboard. (XK eyboar CD)
54 Configurable Rubik's Keys
The tiles on a Rubik's cube (just 'colours' on actually good cubes, such as Valk cubes) resemble computer keys, so this feature makes fun of that by adding a spinnable Rubik's cube above the keyboard. The implication is that the keys would be 'configured' by twisting the sides of the cube until the desired configuration is reached, although parity means that not all configurations could be reached by conventional means by a 3x3 cube. (Parity exists on 4x4 cubes.) There can be a maximum of 53 keys (the bottom center position can't contain a key because it's the mounting position). Additionally, the top key can't be moved around, so the maximum amount of configurable keys is 52. (The four remaining centers can be moved by rotating the entire cube.) The bottom-facing keys would obviously be hard to see/reach.
Hardcoded Plastic Keys for the 5 Most Useful Emoji
This feature parodies the feature of some laptop-keyboards where it is possible to dynamically assign emojis to a small touchscreen area. There is a disaccord between hard-coded, useful and emoji, especially with the large keys in a central position on the keyboard. Which emojis would be "the most useful" is highly subjective. For example in the comic it shows the quite popular laughing with tears emoji, along with the octopus emoji and others. Notably, the "aerial tramway" was once the least-used emoji, and remains very rarely used.
Serif Lock
Serifs are small lines on the ends of certain characters in fonts such as Times New Roman and Georgia. It is dependent on the font, not on the character; "A" is represented by the same code regardless of its font. Since a given font almost always either has or doesn't have serifs, this key seems challenging to implement. This key could be implemented, however, by simply changing between a pair of fonts when it is pressed, or by using the characters in the Mathematical Alphanumeric Symbols block. What's more, the button is placed roughly where left shift is on most keyboards, liable to cause frustration.
Unlimited Key Travel
Key travel is the distance a key moves between its unpressed and pressed states. In reality, laptop keys only move a few millimeters before bottoming out, and conventional keyboards up to about a centimeter. Increased key travel may make typing more comfortable, up to a point. However, the usefulness of having unlimited key travel is unclear, and the question of how this would be physically possible in the keyboard depicted remains unanswered. The keyboard would have to be infinitely deep to allow unlimited key travel, although pushing it to the near bottom would require infinitely long fingers. At least it is the greatest possible value, trumping any other keyboard.
Diagonal Spacebar
Instead of a wide key at the bottom that typists can hit easily with either thumb, we now have a tall, narrow key that requires being pressed with the right pinkie. This would not be a good change since most peoples' pinkies are their weakest finger. Some ergonomic keyboards have a slightly curved spacebar or a separated spacebar for each thumb.
Arrow Key (Rotate to Adjust Direction)
This is essentially a jog dial , or similar rotary encoder .  These are sometimes used with keyboards: as controls for volume, video editing, or drawing.
Many computer keyboards have four arrow keys : up, left, right, and down. However, the XKeyboarCD just has one that can be rotated. This has the added bonus of allowing the arrow keys to point more than four different directions. In a keyboard, it would be awkward to operate as going from horizontally left to horizontally right, for example, would require the user to rotate the key first and then press it, which wastes precious time when playing a video game like the hoverboard comic , where you have to rapidly press arrow keys to move around. It would not let one press multiple arrow keys at once. Trackpoint devices provide similar joystick-like direction function, but are easier to control with a finger.
15 Puzzle-Style Numberpad
A 15 puzzle is a square containing fifteen smaller squares and one blank spot, which allows the squares to be moved around. The squares are shuffled and then reassembled as a game or pastime, and are usually labelled 1-15 (as is the case here) or, when assembled properly, create a picture. A numberpad in this style would be frustrating to use for typing numbers, as they could shift (or be shifted) around, but could provide a fun feature to use as a game. Alternatively the keys could be rearranged as with the Rubik`s keys. How this would be used to generate numeric input is unclear, but the presence of 16 positions suggests hexadecimal input is possible. Keyboard keypads do have around 17 keys, but only 0-9 usually have numbers whereas the XKCD keypad has numbers 1-15 in the middle of the numberpad probably also surrounded by the more conventional arithmetic operators, enter, and decimal point.
Ergonomic Design
The cylindrical portion of the keyboard is advertised as being an ergonomic design. Most ergonomic keyboards are both curved into a convex shape and split in the middle, with the blocks of keys on either side rotated around the vertical axis. This is done to follow natural arm and finger movements more closely, that is, avoid forcing the user to rotate their arms and hands to match the flat and rectangular key arrangement of a non-ergonomic keyboard.  Some ergonomic keyboards come in unconventional form factors, such as vertical keyboards, to allow the user's hands to rest in more neutral positions or to change positions throughout the day, but the cylinder shape presented here is a concave shape which requires the user to lift and twist his arms to reach certain keys (or roll the cylinder from side to side), which would be an even more strenuous motion than typing on a standard keyboard. The slogan of the keyboard — "for power users and their powerful fingers" — fits this difficulty, but makes no sense as a feature.

The title text references sound changes in languages. Every language (and indeed, every dialect) routinely undergoes changes in its sounds and phonemes, in a mostly regular and systematic, but not totally predictable way (otherways the dialects would sound the same and also the century, when a shift occurs, and the rate of change are not predictable). While not only vowels are affected, in languages with many vowels such as English, they're particularly likely to shift around and/or merge. While having dynamic keycaps that change can actually come in handy, the feature of only having vowels change in response to sound shifts is a bit less so. One normally enters the spelling and not the pronunciation of words (except with some Asian input systems). The spelling and pronunciation do not change at the same time.
Firstly, while changes in how we pronounce words are always ongoing, the way we write words down tends to stay relatively static, and thahs wiy wuhd faynd thaet werds biykahm ihnkaammpriyhehnsihbuhl duew tuow nhw laager biyigg sphld es thy wor bifffrr. Second, English only uses five glyphs (aeiou) and a variety of methods to represent four times as many vowel sounds, so the software would need to have a way to handling that (in some dialects "bird" and "turn" for example, have the same vowel but are represented by "ir" and "ur", as it also can be by the "er" in the bird called the " tern " - or not). Third, vowel shifts are not ubiquitous: the Caught-cot merger , for example, is a phenomenon happening across some parts (but not all) of the US and UK. Therefore, while some people would say "caught" and "cot" have the same vowel it should be spelled the same by the keyboard, but others would say they're two different vowels and should not be spelled identically. Fourth, sound shifts tend to occur over a relatively long period of time (in terms of human lifetimes), so a user would probably find the keycaps only change once or twice. All in all, this is not a very useful feature.
An alternative explanation is that the keys actually map to the International Phonetic Alphabet and converts what you type into English words (and the vowel changes). The IPA is an alphabet used in linguistics and language teaching, designed to represent every phoneme present in languages of the world unambiguously, with optional modifiers to indicate more subtle nuances in pronunciation, intonation and speech pathology. This alphabet consists of 107 letters and 56 modifiers (with some letters shared with the Latin and Greek alphabets), which would explain the large number of keys. In that case, the feature remains questionable since it only handles vowel shifts and not consonants, and anybody who'd use an IPA-keyboard would probably need to type out the phonology of other languages and appreciate not having to find a key has moved because English has undergone a vowel shift.
This is the second time that the "xkcd" has been used around a middle word, which uses some of the xkcd letters to form this word. The first was 1506: xkcloud - XKC lou D, to spell ClouD with the C and D from XKCD, in that comic the letters were all lowercase. In this comic the Keyboard, has an X before the word and a C before the D with the xkcd letters capitalized.
[Headings above a drawing of a very special keyboard:] Introducing the XKeyboarCD A keyboard for powerful users and their powerful fingers®
[The keyboard has many more keys than a usual Keyboard. Usual keyboards for stationary computers typically have a few of the rows with 21 keys, and then some with fewer. This Keyboard has 28 keys on the top row. The other rows have special keys that make it difficult to compare, but there is basically also room for 28 in the bottom row, except one spot where there is one key in a space for 2x2 keys. Begining from the bottom and coutning keys there are 27. Skipping those that take up space in two or more rows, when going to the next row from the bottom there are 23, then 24, then 18, then 27 and finally 28 keys in the top row, for a total of 147 keys (vs 105 on a regular keyboard). Then there are 54 extra keys above the keyboard to the left (27 shown) and 156 in 6 rows of 26 to the right for a total of 357 keys 330 shown. All six rows have keys all the way over with no empty space in between, as there are on regular keyboards. Also there are no space between the top row (with F1 button etc) and those below. At each side of the keyboard the keys do no align at the edges, which is normally the case. The keyboard has several special features, most of which are labeled. The only special features that is not labeled is a small square with 2x2 keys that are elevated a bit above all other keys. It is in the region above the normal position of the four arrows. All eight other special features have an arrow pointing to them from their labels. Here below is a description of the labeled items as well as a transcript of their labels. They are listed in the order of their labels first above and then below the keyboard going from left to right.]
[Five keys close to the QWERTY keys positions have colorful emoji on them. They each take up the space of 2x2 normal keys, although it is not clear if all the "normal" keys have the same size:] Hardcoded plastic keys for the 5 most useful emoji 😰 😂 🐙 🏇 🚡
[A cube with 3x3 keys on each side hangs above the keyboard to the left supported by a small rod. Three sides are fully visible, 27 keys:] 54 configurable Rubik's keys
[Just right of the middle above the main keyboard is a cylinder with keys inside in 6 rows of 26 keys (126 in all). It either decreases in diameter into it making it look almost like a tunnel, or is drawn as if it almost disappear in the far distance, being much deeper than it should be.] Ergonomic design
[In the region where the normal numberpad would be there are 15 numbers from 1 to 15 in a 4x4 grid leaving space for an empty key hole. There is a row of keys both above and below this grid. The numbers do not come in order from 1 to 15, but rather in a jumble. Also the empty hole is not a full key spot. Instead it is in the second row of numbers, with a bit more space to the left than to the right of the middle of the three keys.]
15 puzzle-style numberpad 1 8 4 12 7 Empty area 11 3 15 6 10 9 2 5 13 14
[To the left in the second row (below the Caps Lock position) the outer key is twice as wide as the other normal keys.] Serif Lock
[An arrow points to the eight key in the bottom row, but is probably just referring to all the keys in general:] Unlimited key travel
[There is a segment of the keyboard that seems to be empty of keys, but still white like the rest of the keys, not black as where keys are actually missing. It is where on a regular keyboard, the normal keys are separated from the special function keys. But it turns out it is indeed a long key going vertically:] Diagonal spacebar
[Where the four arrow keys are on a regular keyboard there is a 2x2 key segment that only has one key in the middle with black background around it. It has an arrow head on it pointing right. That is if the key had not been turned about 45 degree counter clockwise, so the arrow points up to the right.] Arrow key (rotate to adjust direction)


A/B

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


Westerns

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


Effects of High Altitude

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


Motivation

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


Swimming

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

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


Ufo

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


Diploma Legal Notes

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


Qualifiers

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


Comments

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


Ken Burns Theory

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


An Apple a Day

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


Literary Opinions

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


Chernobyl

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


Glacier

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


Millennials

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


Stack

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


Motivated Reasoning Olympics

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


Reading in the Original

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


Predictive Models

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