2

Explanation:
This demonstrates the different ways in which the number 2 can be typeset in various scientific fields.  While these ways of typesetting are used with any number, using the number 2 in this instance provides a clear illustration how adding numbers can significantly alter a feature of a concept (such as the number of electrons in an atom) or perform a mathematical operation on it (such as raising a value to its second power).
The dotted box represents any character (a number, letter, or bigram of letters, as appropriate to the various signifiers). All the other notation consists only of the digit 2, with occasional additional punctuation, in various locations in relation to this character. Each of these is labelled as to what its 'purpose' might normally be with respect to the general term:
Regular Math Precedes the term. "2x" indicates two times the value of x in normal algebraic use that should be familiar for many people. Physics A preceding superscript. " 2 H" would indicate the particular isotope of hydrogen with the atomic weight of two, namely deuterium, which is most often encountered when working with the atomic level of matter where the total number of neutrons and protons in the atom is important. It can also represent tetration , which is iterated exponentiation. Chemical Physics A preceding subscript, as in " 2 He", indicates the atomic number of an atom, which is the number of protons it contains. It is thus a guide to the number of electrons its unionised form usually has and hence is meaningful for its potential chemical interactions with other atoms. This number of protons should be invariant for any particular named element, but is usually given simultaneously with the presuperscripted mass number for which it can indicate the applicable nuclear physics. Chemical physics is a subdiscipline of physics and chemistry. It can also represent pentation , which is iterated tetration. Regular Math or Footnotes A trailing superscript is typical of a power value ; in this case "x²" would be x multiplied by itself - a common mathematical standard. Additionally, superscripted numbers are one common way to mark words in a line of text in a way to refer to a footnote , typically placed at the bottom of the page and containing additional information that would distract from the main text itself. The ambiguity between footnotes and exponents was used in 1184: Circumference Formula . Chemistry A trailing subscript is used in chemistry to indicate a multiple of the element (or group of elements, in brackets) in a chemical formula . "H 2 O" indicates two hydrogen atoms bond with a single oxygen atom in a molecule of water. Matrices! ("2,2") Extending the trailing subscript with a comma-separated value usually indicates a multidimensional array (e.g., establishing a 2-by-2 square of numbers, or this particular position in such an array), which is in the realm of matrix mathematics . This is a little bit beyond 'everyday algebra' for many people, as seemingly indicated by the exclamation of the mere mention of matrices. The Physicists Are At It Again ("2;2") This label encompasses a mark that turns the prior comma into a semicolon, as part of the trailing subscript. This is a common notation for the Covariant derivative of a tensor field, which is commonly used in the mathematics of general relativity. Either High School Math Function or Incomprehensible Group Theory The number 2 in parentheses that follow a term would normally be the argument to a function . For example, "f(2)" means that you should take the value 2, and find the result if manipulated by the predefined function f . It is generally taught as part of algebraic mathematics in high school . In group theory , however, the number 2 in parentheses could indicate a special kind of group, such as an an element of a symmetry group that keeps 2 fixed, or some kind of group of 2x2 matrices. For instance, SU(2) is a 3-dimensional Lie group of unitary matrices . These concepts are taught in graduate or advanced undergraduate mathematics courses. Oh no. Whatever this is, it's cursed. A symbol centered underneath another larger symbol is normally reserved for doing summations or products, where the big symbol is Σ or Π, or some other operation applied to a sequence of numbers. It does not make sense to have a single number on top of a smaller one. As with other things where something appears to have gone wrong in Randall's comic universe, the explanation for this particular anomaly is that it is 'Cursed'. Two numbers may be stacked directly on top of one another in parentheses as binomial coefficients : ( 2 2 ), but those are always the same size, denoting a combination . In this case, 2 choose 2 is equal to one combination. The usage mentioned in the alt text is an operation (e.g. Σ for summation) over a variable, usually indicated by a letter such as i, where the operation is performed over all values of the variable (i.e., you Σ (sum) the argument over all values of i). In the "2" case, the alt text says "you 2 the argument over all values of 2" (i.e., the Σ operation has been replaced by the "2" operation and the i variable has been replaced by the "2" variable). 2 is usually not an operation, though the definition of 2 under Church encoding is a function that takes in and produces functions. 2 applied to 2 in the church encoding is 4. However, the title text implies that 2 is treated like a variable,which it is not (and it's definitely not a operator and variable at the same time). Things being cursed is a common trope within recent xkcd comics, which have mentioned items including Cursed chairs and cursed connectors . This notation is one of the few occasions where the supernatural has demonstrable implications for science and mathematics for those foolhardy enough to use it.
[An apparent generalisation of a scientific expression consisting of a dotted rectangular 'box' outline, left empty, and various commonly-themed symbology around it:]
[as normal text, to the left of all the rest:] 2 [superscript to the immediate left of the box:] 2 [subscript also to the immediate left of the box:] 2 [superscript to the immediate right of the box:] 2 [subscript also to the immediate right of the box:] 2;2 [i.e. separated by a semicolon] [as normal text, to the right of almost all the rest:] (2) [i.e. enclosed in standard parentheses] [smaller subscript, centered immediately beneath the 2 within the parentheses:] 2
[Further details are drawn in grey tone, around or near various of the elements of the expression:] [Captions above the numbers] [with an arrow pointing to the leftmost 2:] Regular Math [with an arrow pointing to the leftwards superscript 2:] Physics [with an arrow pointing to the rightwards superscript 2:] Regular math or footnotes [with an arrow pointing to the parenthetical 2 at the right:] Either high school math functions or incomprehensible group theory
[Captions below the numbers] [with an arrow pointing to the leftwards subscript 2:] Chemical Physics [with an arrow pointing to just the rightwards subscript 2:] Chemistry [with an arrow pointing to a distorted grey ring snaking around only the comma of the semicolon and the following 2 of the rightmost subscript:] Matrices! [with an arrow pointing to a larger grey ring that passes fully around the whole semicolon and final 2 of the rightmost subscript:] The physicists are at it again [with an arrow pointing to the small 2 placed below the parenthetical 2:] Oh no. Whatever this is, it's cursed.


Welcome Back

Explanation:
Cueball is opening an app called TornadoGuard, a reference to comic 937: TornadoGuard . In that comic the app is described to have a function so it "plays a loud alert sound when there is a tornado warning for your area". Tornadoes are a recurring theme on xkcd.
In the background, a tornado is approaching, so presumably a loud alert sound has just played and Cueball has opened the app. It is also possible that the app didn't play any alert (see reviews of the app in 937 ), but Cueball saw the Tornado and thus opened the app to check whether it had any news.
However, before he can interact with the app and learn more about the tornado, he has to click through various old messages from the app, since he hasn't opened the app in a while. This is feasible because May, which is the month in which this comic was published and typically the most active month for tornadoes, had seen fewer-than-average tornadoes in the previous two years but not during this year – see this Tornado Central story . So Cueball would have been more likely to have to worry about tornadoes this year than in the previous two years.
The comic is poking fun at the obtrusiveness of these kind of messages by presenting a scenario where they cause a significant delay before Cueball would be able to read the very urgent information about current tornadoes.
The messages include a description of a big update, a response to user feedback about one specific feature, and a social post seemingly unrelated to the app.
This continues in the title text where there are two more messages that refer to specific world events and can therefore be dated: The fire that damaged the church of Notre Dame in Paris April 15th 2019; and the early attempts to limit the spread of Covid-19 disease, which was declared a pandemic on March 11th 2020. It has been a while since the last reference to the pandemic , actually the previous comic about this, 2563: Throat and Nasal Passages , was released almost exactly 4 months prior to this one.
The two mentioned news stories were relevant about three and two years before this comic was published, respectively. Neither of these are important to know right now, whereas an announcement about an update that changes its functionality could be important to know about .
Although it is possible that there are no more messages to click through if nothing of significance has happened subsequent to the title text ones , the reader can easily imagine that the development team has posted further 'real time' messages that Cueball will still have to scroll through and/or dismiss, with very little immediate importance compared with the imminent proximity of an actual funnel-cloud.
[A large cloud fills the upper 3/4 of the panel. That it is a cloud is indicated by curved lines at the bottom of the cloud. Below the cloud lines is a tornado in the right part of the background. It is throwing up dust on or near the mid-distance horizon and creating an active debris cloud. In the foreground Cueball is standing holding his phone up in one hand, looking at the screen, which is on as indicated by five "light lines" coming of his display. Three paragraphs of text fills most of the white cloud space above Cueball, they are connected by lines, with the last leading down to the top of Cueball's phone. There are two rounded boxes to the right and below the first two paragraphs with text. They represents buttons Cueball presses on the screen to get to the next text message.] Hi! The TornadoGuard™ team is proud to announce a big update! We've added- Okay
Note to users of sentinel mode: We've heard your feedback, and the controls are now- Got it
The TornadoGuard™ team saw this cool leaf shaped like a spider; do you want to see...
[Caption below the panel:] When you open an app for the first time in a while, you have to wait around while it tells you about all the cool adventures it's had.


Deep End

Explanation:
Pools, like oceans, contain water. This comic produces a schematic for the former, derived from science about the latter. On Earth, the surface consists of tectonic plates which move around. In this comic, Randall equates swimming pools with plate tectonics , to explain how deep ends form in said pools. In actuality, swimming pools aren't formed by plate tectonics (at least, not the ones made by people; we can't be sure about the others).
A swimming pool is a pool of water, typically used for swimming. Most of these have a deep end and a shallow end. This is intentional, usually to allow less confident swimmers to have somewhere to stand up when needed, while also accommodating activities (such as diving, underwater swimming, rescue practice, etc.) which would not be possible in shallower water.
Subduction , a geological process in which one plate slips beneath another and is forced down into the mantle, is shown here as the reason swimming pools have deep ends. This usually takes place between continental plates and oceanic plates, although it could happen with two oceanic plates. The comic depicts the former, an oceanic plate subducting under a continental one. With tectonic plates, this often results in a deep oceanic trench where one plate slides beneath the other, as well as a chain of volcanoes above areas farther along the subducting plate, where rock that has liquefied from the subduction comes toward the surface as magma and erupts in volcanoes. An example is the Cascadia Subduction Zone in which the Juan de Fuca Plate is subducting beneath the North American Plate , creating the volcanic Cascade Range .
A splash zone is an area of a waterpark with water being sprayed around, allowing people to get wet without the need to get into the pool. It is not a geological term, but splash zone can mean the area next to a coastline that gets splashed by waves. In this comic, the splash zone consists of natural geysers, fed by the bubbles of water that return upwards from the subducted plate.
The title text refers to back-arc basins , zones of depression that sometimes occur slightly beyond volcanic arcs due to a rift in the tectonic plate. The ban on running in this area likely has more to do with its proximity to the pool area than any danger intrinsic to back-arc basins.  A typical safety rule around swimming pools is to avoid running on the pool deck to prevent injuries due to slipping and falling on the hard deck.
Other comics that mention unusual tectonic plate motion include 1388: Subduction License and 1874: Geologic Faults .
[Caption above the scene] How deep ends form in pools
[On the left of the image is the shallowest water in the pool, about the height of Megan. All the water in the image is grey. She is swimming in the water, and a duck floatie and a beach ball are floating to the left of her. It is labeled] Shallow End
[Underneath, a thick layer is labeled] Pool Floor
[Going to the right from there, the pool floor begins to curve downwards. As the floor goes down, the water gets deeper. In the deepest area, it is labeled] Deep End
[At the bottom of the deep end, there is a curve and a deposit on the pool floor. Within the sediment and pool floor, there are some small pools of trapped water, labeled with three arrows] Trapped Water
[On the pool floor an arrow indicates that the oceanic plate is moving left-to-right across the image, which is labeled] Subduction
[Some of the water pools are dragged along by the pool floor, while others float up through the ground. The latter are accompanied by several arrows pointing up to indicate upwards movement. These are labeled:] Upward Migration
[At the surface there is an area, which is labeled] Splash zone
[The water erupts in two geysers, the left slightly larger than the other. Several children (small versions of Ponytail, Hairy, and Science Girl as herself) are playing there. Science Girl is sitting with her arms in the air facing the geysers, and Ponytail and Hairy are running towards the right geyser, Hairy with his arms in the air. The area is labeled] Splash Zone
[To the left of the splash zone is the edge of the pool, where a Cueball figure is in mid-air after jumping off the diving board, with his arms outstretched. This is labeled] Pool Deck


Maps

Explanation:
The term "map" carries a double meaning within this comic. While it refers to an actual map, it also refers to the concept of "map and territory," where your map is your model of the universe, and the territory is the universe itself. Cueball has a map of the universe where Apple Maps is bad, and is surprised to discover that the map no longer fits the territory, and thus has to update his map.
The title text mentions OpenStreetMap , an open-data crowd sourced geodatabase, which has also improved since Randall has last checked, potentially moving it from a "pretty good" score to a "really good" score. He also adds two examples on how the Apple Maps service has improved: zooming in on cities, like London or New York you can see features like trees and road markings, the latter usually not visible on other mapping services at all. He marvels at the number of "good" mapping options now!
Google Maps itself, and especially its satellite coverage outside the US, was considered quite bad when it launched in 2005. The maps displayed back then led to mockery among "real" cartographers that the service couldn't really be considered a map, either: It was called "map-like", with casual digital maps being so new at the time. However, Google's popular mapping approach revolutionized how maps were perceived all over the world. The approaches Google uses are explained in How Google Maps is Made . This approach blurs the lines between traditional paper maps, GIS (geo-informational systems) and digitally rendered maps on screen. The process of "mapping" - as it is referenced here - has since moved significantly into the digital realm.
[Cueball is holding his hands up and is staring down at his open palms. Megan and White hat is looking at him.] Cueball: You look around one day and realize the things you assumed were immutable constants of the universe have changed. Cueball: The foundations of our reality are shifting beneath our feet. Cueball: We live in a house built on sand.
[Caption below panel] The day I discovered that Apple Maps is kind of good now


Selection Bias

Explanation:
Selection bias is when a survey or poll of some sort comes up with incorrect results due to those who were asked. For example, if you asked a group of people how many acres of land they own, your average number will be higher if you ask a group of farmers rather than a group of city residents.
The joke is that she is thus falling for the very thing she's trying to explain. A statistics conference is likely to have an audience consisting of professional statisticians, or at least people interested in the subject, and it is expected that most of them would thus be familiar with any mainstream statistical term, like selection bias. Had she asked a random sample of people in the street, many of them would likely not be sure what selection bias is. This effect is also the subject of 2357: Polls vs the Street .
This joke also ties into how statistics as a whole can be highly counter-intuitive and sometimes almost paradoxical, where things like the Monty Hall problem and survivorship bias lead people into thinking the answer to a problem is definitely in a place it's not. That Blondie, presumably a statistician herself, made this kind of (potentially deliberate) error is professionally embarrassing but not unprecedented.
The title text refers to Acquiescence bias , which is the tendency of people to respond positively to positive questions, for example, "Are you familiar with the famous webcomic xkcd ?" is more likely to generate the answer yes than "Are you familiar with that webcomic for engineers that nobody else understands until they go to Explain xkcd ?" Acquiescence bias is not a widely known concept, [ citation needed ] making the results of this poll suspect; similar to the selection bias example above, the reason that the general public seems familiar with acquiescence bias may be because the surveyor themself fell victim to promoting acquiescence bias.
[Blondie is standing on a podium behind a lectern with a microphone. She is standing under a hanging sign with large text. In front of the podium is an audience of five seated persons all with their hands raised above their heads. The audience includes two guys that look like Cueball, Hairbun, and two other persons with dark and blonde hair.] Sign: Statistics conference 2022 Blondie: Raise your hand if you’re familiar with selection bias. Blondie: As you can see, it’s a term most people know...


Crêpe

Explanation:
Cueball has made a crêpe , a thin pancake known for its legendary status in French cuisine, which he proudly announces. However, the circumflex (the accent above the e) is written strangely. Instead of the usual simple angle (^), it looks more like the outline of a flattened arrowhead ( ⮝ ). Megan , who can apparently hear the orthography of spoken text, comments on the odd shape with an appropriate pun.
Megan's response, "Weird circumflex but okay" is a play on the recent expression Weird flex, but ok . A "flex" is bragging about something. A "weird flex" is used when the speaker acknowledges (perhaps ironically) that the first person is attempting to brag about something, but doesn't recognise the thing as brag-worthy.
Her answer could also be applied to the shape of the crêpe, as circumflex means "bent around".
In some dialects of English (e.g. British English), and in the original French pronunciation, "crêpe" is said so that the ê is pronounced as in "get" (i.e. "cr-eh-p"), but American English speakers pronounce it like an "A" (i.e. "cr-ay-p").
The title text continues the wordplay by saying that "A medicine that makes you put two dots over your letters more often is a diäretic".
The word diäretic is a pun on diuretic (a substance promoting increased urine production), diaeresis (a symbol in the form of two dots placed above a vowel, as the ä in the made up word diäretic; the adjective form of diaeresis can be spelled " dieretic ") and diacritic (a glyph added to a letter to distinguish its sound from the normal version, what both the circumflex and the diaeresis are). See also the comic 1647: Diacritics about the use of these. Taking a diäretic medicine would supposedly cause you to use diaeresis (also known as umlaut) över möre lëtters thän wöuld üsuallÿ bë thë cäse.
Diacritics are rarely used in English, potentially because of the diverse set of origin languages it developed from, or the wide variation of pronunciations within a same nation, but are a common feature of other languages.  In English, they are normally only seen in specific loanwords (such as crêpe) or used for emphasis or decoration (for example the metal umlaut seen in rock bands like Motörhead , Mötley Crüe , Queensrÿche , or Spın̈al Tap ).  The exception to this is the diaresis, which when it is used at all, is placed over the second vowel in a double-vowel word to indicate a morphological break between them as opposed to a diphthong (e.g. naïve or coöperation).  The diaresis is optional, and, especially with words beginning with the co- prefix (e.g. cooperation, coevolution, or coincidence), rarely used.  The New Yorker magazine is a famous outlier, advising consistent use of the diaresis in its style guide .
[Cueball is holding a plate up in both hand, showing Megan the crepe lying on the plate. His word for crêpe has a different diacritic over the "e" than the normal circumflex (^). Instead it looks more like an open arrow head.] Cueball: Check out this crêpe I made! Megan: Weird circumflex, but okay.


Health Data

Explanation:
Cueball tries to cut to the root of the issue by asking his chances of survival. Ponytail asks whether Cueball has a family history, but rather than asking for a history of specific illnesses, she is merely asking whether he has any family history at all. Her apparent concern on discovering that he does is presumably due to the fact that everyone who has a family history dies, and therefore she sees this as negative. However, this is not medically informative, since everyone has some kind of family history (whether they personally know anything of it or not) and everyone eventually dies. [ citation needed ]
The comic is likely a comment on the impenetrability of some medical diagnoses, where high levels of jargon and non-contextualized statistics, combined with a lot of hedging language, can leave patients none the wiser about their prospects or the relative merits of various courses of treatment. Similarly, it could be reflecting on the effects of availability bias and the base rate fallacy when medical practitioners are deriving diagnoses, treatment options, and similar conclusions from medical records designed to highlight the information necessary to diagnose specific well-understood illnesses. It may also be making fun of poorly defined health statistics: statistics for the leading causes of accidental death in the United States , for example, typically cite 'poisoning' as the number one cause, even though poisoning other than drug overdoses is actually quite rare. The comic takes vague statistics to the extreme, citing 'causality' as the leading cause of death.
The title text continues the joke, suggesting that researchers are searching for a cure for causality, which is absurd and inconceivable.
The comic as a whole is reminiscent of 830: Genetic Analysis and 1840: Genetic Testing Results (particularly the title text of the latter), as the information given by the doctor in all three is self-evident and useless as a result.
[Cueball and Doctor Ponytail are talking to each other. Cueball is sitting on an examination table and Doctor Ponytail, in a doctor's coat, is looking down and reading from a clipboard with some illegible writing on it.] Doctor Ponytail: I'm taking a look at your numbers, and it doesn't look good. Doctor Ponytail: You have a lot of measurements. Quite a few variables.
[Same setting but Doctor Ponytail looks up at Cueball.] Cueball: Is that... bad? Doctor Ponytail: Variables are the #1 risk factor for outcomes. Doctor Ponytail: The past is a big contributor to the future.
[Same setting but Doctor Ponytail puts her arm with the clipboard down.] Cueball: Isn't that just causality? Doctor Ponytail: Causality is the leading cause of death in this country.
[Same setting.] Cueball: So what are my odds? Doctor Ponytail: Do you have a family history? Cueball: Of what? Doctor Ponytail: Just, in general. Cueball: ...Yes? Doctor Ponytail: Oh no.


Mainly Known For

Explanation:
Frequently, when people can't remember a celebrity's name, they will point out other works they are known for in hopes someone else will recognize them from that and remind them of the name.  The comic, for its demographic of nerds, is joking on how it can come across to have lived a life separate from popular culture, where one learns things for different reasons than most people do.
Cueball points out that Megan's tendency to avoid the "main" association and instead go with a much more secondary one is weird, which confuses her. To demonstrate how weird her associations are, Cueball asks her, "Who is John Lennon ?" Lennon was a founding member of The Beatles , which is one of the most famous bands of all time. Megan recognizes Lennon as a musical artist, but is unable to remember the name of The Beatles. Bizarrely she does remember the name of Lennon's bandmate Ringo Starr . Even stranger, Megan still fails to associate Ringo with The Beatles, but rather remembers him as Mr. Conductor from the first season of the 1989 children's television show Shining Time Station . Starr was never particularly well-known for his acting career, and even among his acting roles Shining Time Station was a minor and obscure example.
Hoping to show that she really does know Lennon and that her associations aren't weird, she points out that she remembers John doing a song with David Bowie . But she cannot remember the name of the song (" Fame ") or even Bowie's name, recognizing him instead for his acting role in Labyrinth . When Cueball states Bowie's name and adds, presumably sarcastically, that he think he is famous for "other stuff", she also remembers Zoolander which is a less prominent film in which Bowie had a cameo. Bowie is primarily famous for his famous musical career (such as his smash hits " Space Oddity " or " Let's Dance ").
Sensing Cueball's annoyance, but failing to understand it, she attempts to excuse herself for not remembering Zoolander to begin with, because it came out a long time ago, during the Presidency of George W. Bush . Zoolander was indeed released in 2001. Apparently unable, again, to remember the president's name, she identifies him as " Jenna Bush 's dad". Jenna Bush is a minor TV personality and is far less well known than her father..
While the kind of associations people make, like Megan in this comic, are often prone to the Mandela effect , Megan's information about all the celebrities is, in fact, correct, but apparently they are never what those people are best known for. The oddness of having such obscure knowledge about celebrities and popular culture, but apparently missing far more common knowledge, is frustrating to Cueball, but there's nothing he can point to that she's wrong about.
There may also be some overlap with the Streisand effect , named after a woman widely known for owning an overly lavish mansion on the coast of a state north of Mexico.
In the title text, Megan stacks her unusual references and takes them to extremes.  She refers to " Keira Knightly " [ sic -- her surname is spelled Knightley], who is probably best known for her roles in the Pirates of the Caribbean films and the 2005 Pride and Prejudice film , by referencing her small role in Star Wars: Episode I – The Phantom Menace (as Sabé, who funnily enough is a handmaiden and decoy for Queen Padmé Amidala, a main character played by Natalie Portman). "Star Wars" is one of the most famous film franchises in history, but Megan seems not to know the name of the series, or the film, referring to it as the "first movie" (it was the first in the plotline, but the fourth one made) in "that series by The Land Before Time producer".  ( George Lucas is famous as the creator of Star Wars but was also one of the executive producers of the 1988 animated film The Land Before Time .)
In addition to George Lucas, she identifies another actor in the Star Wars series, Samuel L. Jackson , by his roles in Jurassic Park (an extremely successful film, but one in which Jackson had a relatively small role) and the PBS children's series Ghostwriter (in which Jackson appeared in only a few episodes). In addition, Megan mentions that the Star Wars series had "script work by Billie Lourd 's mom", referring to Carrie Fisher .  Fisher came to fame playing the major role of Princess Leia Organa in the original "Star Wars" film, and reprising her role in multiple sequels, but she also contributed uncredited script-doctoring work to the franchise.
Ghostwriter was previously featured in 130: Julia Stiles , which described a scene from the show as "the best thing ever to appear on TV".
[Megan holds her hand palm up towards Cueball.] Megan: ...And her dad looks exactly like the Pixar guy. Steve what's-his-name? Jobs? Cueball: "Pixar guy"? Cueball: You always know famous people for such weird reasons.
[Megan puts her hand down.] Megan: What do you mean? Cueball: Who is John Lennon? Megan: Wasn't he in a band? With Ringo from Shining Time Station . Cueball: How is that your main association?
[In a frameless panel Megan holds a finger up in front of Cueball.] Megan: I also know he once did a song with the guy from Labyrinth! Cueball: You mean David Bowie? I think he's famous for some other stuff, too.
[Megan puts her hand down while Cueball facepalms. The line connecting his is curved.] Megan: Oh yeah, he was also in Zoolander! Megan: I forgot that movie, it came out back when Jenna Bush's dad was president. Cueball: *Sigh*


Angular Diameter Turnaround

Explanation:
This comic references multiple physics and maths concepts, including Angular diameter , Angular diameter distance , Redshift , and mobile phones , although mobile phones are not a core science at this time. [ citation needed ]
The comic shows the galaxies of the universe as Samsung Galaxy mobile phones, pairing the age we see them at from earth, the degree they are redshifted, and how much of the sky they take up, known as their angular diameter. The mobile phones that are closer and older have depleted batteries, whereas the batteries are full for those phones from which the light is still only beginning to reach us. This is how galaxies appear in the sky if they were phones that had batteries lasting billions of years, the light reaching us from deeper into the past as it comes from objects that are farther away. Phones at a low battery may be a reference to 1373: Screenshot , where Randall commented that it is hard to pay attention to any phone with a low battery as the need to charge it is so urgent.
An important takeaway from this comic is that the events that occurred at the very start of our universe are etched in our sky as if they are still happening now , in a detailed faint timeline, that we are still learning more and more from.  Using the mobile phone metaphor helps as, when the technology space was young and smaller there were mobile phones , such as the original iPhone ,  which one might still remember despite there being many more recent and better ones in a more crowded market space.
Randall's intent appears to be to highlight how just a few very distant galaxies occupy incredibly large proportions of the sky and are seen as they were at a very young age. Mobile phones have this similarity, of massive presence, relatively early stages of new technology, and bringing information from far away.
The large galaxies can be seen in dark red in the background as if the unimaginably ancient child galactic bodies are looming forebodingly behind everything else. The title text refers to galaxies falling into a pool of dilute blood as if the void beyond were hell.  This completely misses the point as to what redshift is, being an effect on the wavelength of light, rather than light being filtered through regions of infernal suffering or far galaxies being stained by the blood of the enemies of Android phones.
This physical concept has a lot of juxtaposition of things that usually contradict, and Randall has put energy into attempting to highlight that.
Katie Mack tweet: https://twitter.com/AstroKatie/status/1516548836709343238
Spacetime diagram possibly has reasonable visualizations of the kinds of relations bodies have when they are moving this far apart, including angular diameter distance. Simultaneity no longer exists at such distances. Distance is debated too, although that would be a different article.
[Cueball and a row of 7 spiral galaxies, the first 5 growing sequentially smaller and the last 2 growing larger] Angular Diameter Turnaround [A spiral galaxy emitting light and Cueball in a small circle with closely spaced grid lines, captioned "T=1b yr."] [A stretched truncated circle with widely spaced gridlines, with the galaxy at one side and Cueball on the other, and light following a curved path through the stretched space to Cueball, captioned "Now (T=13.8b yr.)". Cueball is thinking "Big!"] Illustrated using phones instead of galaxies (Brightness and redshift adjusted to keep phones visible) Things that are far away look smaller, but things that are really far away look bigger , because when their light was emitted, the universe was small and they were close to us. [numerous iPhones scattered in space, with numbers visible on their lockscreen. The closest is brightly lit and says "13 billion years after the Big Bang" on the screen. Subsequent phones behind this one are smaller, fainter and more red, until they reach "3" (the rest of the text is too small to read). From this point, the phones grow larger, although they continue to get fainter and redder. Subsequent phones show "2", "1", "500 million", "200 million", "50 million", "20 million" (which is larger than the original "13 billion years after the Big Bang" phone) and a very large, faint phone so big that only the word "thousand" is visible, with the rest of the screen obscured behind other phones or so large it extends off the panel]


Goofs

Explanation:
IMDb is the Internet Movie Database , a website that contains detailed, user-contributed information about movies and TV shows. One of the sections in many entries is " Goofs ". This may list bloopers, inconsistencies, implausible actions, anachronisms, etc. in the movie. While some people find enjoyment in searching for these errors, to others, the entries listed can often be overly pedantic and missing the point [ citation needed ] (a problem that can often afflict sites that rely on users to provide their content [Hey! Who you calling a pedant?]). The comic makes fun of this with several goofs that simply point out differences between something in the movie and reality; but since the movie is fiction (in this case, a science fiction film that includes a space detective, a cybernetic dog, blimp drones, and a hologram kissing scene), one can say that these "goofs" might simply be more differences between the movie world and our own.
In the first goof, a named street doesn't actually exist in the city in which the movie is set. Unless the address is important to the plot (Manhattan has a number of streets with well-known characters - for example, the main theatre district is on Broadway, Fifth Avenue is a major shopping district, and Wall Street is known for large financial institutions), screenwriters can and do make up street names. It might actually be expedient to 'rename' a setting in many cases, to avoid issues such as fans showing up at said street and harassing the residents.
In the second example, they point out that there's no harpoon store at the location where the characters obtain a harpoon in the movie, and the nearest actual harpoon store doesn't have a display window. Movies take liberties with details like this for plot expediency, and is not considered a goof. Manhattan does not appear to have any notable harpoon stores, [ citation needed ] with or without the kind of frontage described.
In the third example, the background of a scene is of an apartment in Downtown Vancouver (a cheap and popular filming location that frequently stands in for other cities). The goof points out that the real-life apartment does not belong to the character who supposedly lives in it. Fictional movie characters do not exist in reality, [ citation needed ] and many scenes are set in fictional locations that are completely separate from their real-life filming locations. As such, this is only a "goof" if the scene is taken entirely literally.
The title text describes an actual anachronism. The film is set in 2018, but there's a billboard for the movie Avengers: Age of Ultron , which came out in 2015, while the next Avengers film, Avengers: Infinity War , came out in 2018. Assuming the movie was filmed before 2018, the filmmakers wouldn't have known what films would be current at the time it would be released, and certainly not the artwork they'd be using to promote them. They could have chosen to set it during the time of initial filming, but again, unless the specific date is significant to the plot, it's common to set (or rather, assume) a film takes place about the same time it's released. Generic advertisements for fictional (or parody ) films might be put over egregiously obvious existing material, physically or in post-production editing, as might references to major brands – perhaps replaced by those agreed with from product placement partners.
The title text also mentions the possibility of a self-reference – the billboard could be for this film itself since it's being released at the same time it's set.  This assertion that in-universe self-reference is plausible for a movie production is likely another example of the goof's writer failing to understand the basic "premise of fiction". Most movies do not exist within the fictional world they portray, [ citation needed ] and many audiences would find self-reference to be a far greater obstacle to suspending disbelief than an ad for the wrong Avengers movie.
[An excerpt from an Internet Movie Database web page showing a list of goofs from a film. Each item has some small illegible text below it, which on the real IMDb would say something like "7 of 72 found this interesting | Share this". The first and third items have a faint yellow-tinted background. The third item is only partially visible at the bottom of the "screen".] [Heading:] Goofs (78) [List:] The space detective's office is on Chestnut Ave, but Lower Manhattan has no street by that name. Agent Glennifer pursues the cybernetic dog onto what is clearly Ludlow Street. The agents destroy the blimp drones in Union Square with harpoons from a store display rack. The nearest harpoon store is several blocks away and has no outdoor displays. The apartment in the background of the hologram kissing scene actually exists in downtown Vancouver. We called the owners, who confirmed they had no residents named [...]
[Caption below the panel:] Sometimes the IMDB "Goofs" section really seems to struggle with the whole premise of fiction.


Voyager Wires

Explanation:
This comic claims that the Voyager probes communicate with NASA though ridiculously long copper wires. These wires would have to be continuously lengthened as the probes travel away from Earth. Supposedly, because of "high copper prices and budget constraints," they may not be able to afford to lengthen the wires much longer. If this occurred, they would have to either cut the wires or let them break, which would prevent any further communication with the probes. In reality they use radio waves , not long copper wires, so this will not actually happen.
If copper wires were dragged by the Voyager probes, assuming a 1mm² thick cable, 550 tons of copper would be needed per hour and it would add 1 million Ohm per hour to the cable resistance. At $8,560/ton , this would cost $41 billion dollars/year, which would be nearly twice NASA's entire annual budget .
The resulting wire would slow down the probes by drag unless the wire itself was actively suspended (i.e. accelerated) continuously as it was fed. The wire could not be used for any other mechanical purpose such as a space elevator for this reason.
Since the Earth spins, the wires would also spool around the Earth, slowing the probes down even further. Clearly, this is not a good idea. This problem might be avoided if the wires reached earth at one of the poles. Or perhaps they could go to an airplane that flies around earth at exactly 15 degrees of longitude per hour, with periodic air-to-air refueling, so that it is always on the side of the earth facing the probe.
Because the Voyager probes aren't in the plane of the earth's orbit around the sun, the Earth would not, in its rotation around the sun, drag these copper wires through the sun. If it did, the wires would melt.
The title text references the phenomenon seen with self-retracting cables, such as are commonly found on vacuum cleaners, where the free end of the cable, where the plug is, oscillates more and more wildly as the cable approaches full retraction, leading to the danger of a painful rap on the hand if it is not withdrawn in time. A planet-sized impact of this kind could cause severe damage.
A few days before this comic was released, NASA had reported receiving corrupted data from the Voyager 1 probe.  The fact that they are receiving any data at all means that the attitude control system must be working (or else the antenna would not point at Earth), but they continue to investigate how that data could be corrupted after that point.
Spoiler alert
The consequence of a cable between a craft in space and a planetary location being suddenly retracted was recently imagined in the first episode of the Apple TV+ series Foundation , wherein a space elevator tether was severed. It didn't end well for anyone other than the terrorists who won the freedom of thousands of inhabited worlds which had formerly suffered under the jackbooted oppression of Trantor 's fascist galactic Empire regime.
Another illustration in fiction of a severed space elevator is in Red Mars, part of the Mars Trilogy by Kim Stanley Robinson.
[In the bottom right corner is a space probe, with large satellite dish and long antenna. Behind it runs a long wire, that makes three loops before it is connected to North America  on the Earth in the top left corner. To the left of the Earth there is a second wire, which goes off-panel to the left.]
[Caption below the panel:] Sad news: Due to high copper prices and budget constraints, NASA may finally have to cut the wires that they've been spooling out to communicate with Voyager 1 and 2.


Field Topology

Explanation:
Field Topology is a subject in mathematics , but in this comic, Randall is instead examining the topology of playing fields used for various sports. The comic strip depicts a situation in which the common practice of multi-use athletic facilities has been organized by the "topology department" and constructed to be shared by all sports whose normal playing fields are topologically equivalent . One key assumption in topology is that you can ignore the specificities of shape, size and material of the objects concerned. This presents an amusing contrast as the "equivalent" topology department playing fields are actually not very appropriate for the activities listed in the comic, as the standard positioning, size and shape of hoops, nets and bars and the material of the field itself are not equivalent to the real playing fields used for those activities.
(Not to be confused with mathematical fields , or the Fields Medal prize -- although the concept is likely a further pun in the comic, as math (including topology), and most things once can imagine really, are mostly performed ("played") within mathematical fields.)
In topology, shapes which can be smoothly deformed into one another without adding or removing holes are considered equivalent. A topological hole is an area of the nominal space (or area, or other manifold) through which nothing restricted to this topology can pass. A loop is a path across the allowable territory of a topology (or a viable circuit to make through the world it describes) that end up where it started. For example, when describing the space taken up by a solid object such as a coffee mug, the handle forms a loop with a hole through it. If a loop cannot be tightened (ultimately adjusted to take a shorter path) down to a single point, then it must be wrapped around at least one "topological hole", and you have separately unique paths (or points, i.e., on different disconnected topologies) where you cannot adjust one loop to take the route of another without severing a looped path and reconnecting it.
When describing a negative space, such as the space around an archway, the 'hole' would be the material of the arch itself. This is because a loop formed by a ring around any part of the arch material can only be shortened to a finite length, not to a point; the 'hole' is the arch-shaped obstruction which forces the existence of these loops. A basketball hoop connected to the ground forms a similar obstruction with a loop through it, so the space around the hoop contains an equivalent hole. In this comic the topology department has analysed the spaces where various sports are played by the number of such obstructions in the playing area. Each space depicted in the comic is then signposted with the sports which are played on a field with that number of holes.
Baseball , tetherball and soccer are played on fields which are continuous in three-dimensional space. This means it is possible to traverse any path around or over any of the structures defining the field, while there are no obstructions which can be traversed through in a loop around them. The goals on a soccer field presumably do not create holes because the goalposts and crossbar are connected to the field by the net; Randall apparently considers these to form continuous surfaces which do not allow loops through them.
Volleyball and badminton are played using a net suspended from poles, and the high jump has a bar that contestants jump over. The structure formed by the net or bar and the supporting poles can be considered to be a "hole" through the playing field, as a path over and under the net/bar forming a loop cannot be contracted to a single point, so their playing fields in the comic all have one "hole".
A basketball court has two hoops. Parallel bars can be thought of as two archways. Both have opportunities to pass through either (or both) structures, and so the material of the structures define a hole in the topological abstract of the playing 'space'.  Since we are told that these sports fields belong to the Topology Department - and are not necessarily generalized to all sports fields - we might assume that their "football" field is either for rugby or for American football using H-shaped uprights .
An Olympic-sized swimming pool has ten lanes, and thus nine lane dividers which are fastened to the walls of the pool at each end, creating topological holes through the play area. Each hoop in croquet is similarly a hole through the space; while most versions of croquet use six hoops, nine hoops are used for "backyard croquet" which is played recreationally in the United States and Canada. The fact that the space in a swimming pool is typically filled with water [ citation needed ] has been overlooked by the topology department.
As mentioned in the title text, this last configuration is also homeomorphic to a foosball table (with each rod sustaining the player figures above the table defining a hole) or a Skee-Ball lane (which is even more straightforward, as it is just a plane with several holes in which to throw balls). These "fields" don't actually have the same number of holes, but are apparently lumped together by the Topology Department as having "many" holes.
Unfortunately, the Topology Department does not seem to have a field for hurdling events.
[A row of four signs, each held up by two posts, followed by a row of four rounded lozenge shapes, one for each sign. The signs and lozenge shapes are shaded as if three-dimensional objects, all being flattish with a small third dimension; the four lozenge shapes each have one pair of sides horizontal and the other pair at a slight angle from vertical, denoting a horizontal plane perpendicular to the signs extending "out" towards the viewer, which places each shape "in front" of its sign. All but the first lozenge shape have various numbers of ellipses within the shape - ovoids shaded to denote holes piercing through the objects.]
[Leftmost sign:] Baseball Soccer Tetherball [The shape below this sign contains no ellipses.]
[Second sign from left:] Volleyball Badminton High jump [This shape has one large ellipse in the center.]
[Third sign:] Basketball Football Parallel bars [This shape has two large ellipses - one in the top half and one in the bottom half.]
[Fourth and rightmost sign:] Olympic swimming Croquet [This shape has nine small ellipses - eight arranged symmetrically towards the edges of the shape and one in the center.]
[Caption underneath the signs and shapes:] No one ever wants to use the topology department's athletic fields.


d65536

Explanation:
In binary computing, 16 bit unsigned numbers range from 0 to 65535, for a total of 65536 unique numbers, a number which is hence well-known to software engineers. Generating large numbers in a manner that is truly random is a recurring problem in cryptography, required to send private messages to another party. People today still use dierolls to generate private random numbers.
In role-playing games (and occasionally in other tabletop games), multiple shapes of dice are often used to generate random numbers in specific ranges.  By convention, these are referred to as d n according to their number of faces. A traditional six-faced die would be a d6, and many popular pen-and-paper role-playing games use dice ranging between d4 and d20. While there are larger dice used in tabletop games (most commonly d100), these are usually split into multiple smaller ones. For example, a d100 is often two d10s rolled together, with one die providing the first digit and the other die giving the second digit — the total number of possible combinations (100) is the product of the number of faces of the two dice (10 * 10). While "real" d100s and other large-numbered dice do exist, most people consider them to be impractical: they need to be either impractically large or have very small faces (resulting in small print for the numbers), they're close enough to being spheres that it's difficult to get them into a stable resting position, and even if they are stationary, determining which face is "on top" is difficult to do by eye. The Zocchihedron (d100) die is also difficult to ensure as unbiased because of geometry requiring dissimilar faces and therefore a different mixture of 'stopping factors' for each face it could land upon. The largest unbiased die is a d120 (excluding the bipyramids, which can theoretically be made with arbitrarily many sides), so it is very likely that Cueball's d65536 die is also biased.
Here, Cueball has constructed a d65536 for generating random 16 bit numbers. It may have solved the problem of generating large random numbers with fewer die rolls, but it magnifies all of the problems with large-numbered dice to ludicrous extremes. In order for the faces to be readable, the die is ridiculously huge, dwarfing the human standing next to it. Rolling such a die is not only physically challenging, but it would also need a huge space in which to roll if the result is to be random, and that space would need to have an extremely flat and rigid surface in order for the die to come to rest. And even if those problems were solved, simply getting to a vantage point to see the top of the die would be a major challenge, and determining which number was truly on top would be near impossible to do by eye. If one really wished to use dice, it would be much easier to simply use multiple dice rolls. For instance, one could roll eight d4 dice (or use 16 coin flips), and convert the result into binary. This has the same randomness as a single die roll [ citation needed ] ?, but can take much longer, so people do purchase d16s to simplify it and speed it up.
The closest regular shape similar to the depicted in the comic could be a Goldberg polyhedron . However, no such polyhedron exists with exactly 65536 hexagonal faces. The closest Goldberg Polyhedron has a mixture of 65520 hexagons and 12 pentagons, totaling 65532 faces. It is possible to construct a fair die without a matching regular shape by limiting the sides which it could land on and designing those sides to be fair (for instance, a prism with rectangular facets that extend its entire length, and rounded ends to ensure it doesn't balance on end).
The title text references how cryptographic systems (especially RSA and other factoring-is-hard based systems) are vulnerable to quantum attacks as quantum computing technology develops. The title text is essentially punning on the idea of a "large" quantum system. "Large" in the quantum computing sense would be on the order of 64 qubits each of which would be an atom or two at most. This would still be microscopic and will never be as large as the giant die the comic is centered on; but for a well-observed environment and human rolling without sufficient entropy (consider somebody obsessed with a certain number dropping the die on something soft), a conventional computer could predict some rolls. See also 538 for non-mathematical paths of cryptography.
[A large sphere with a several lines, and in some places grids, are shown. Cueball, standing next to it, is dwarfed by its size, as it is at least seven times as tall as he is. The sphere has many lines following various great circles or parallel lesser circles around the curve of the sphere, and some patches of cross hatching to suggest further texturing along these lines hovering just below the degree of most of the illustrative detailing. The lines and grids cover the sphere in three layers of parallel axes, angled sixty degrees from each other, implying a huge mesh of equilateral triangles or hexagons. In the top right part of the ball is a black circle. An arrow points to this circle, and the end of the arrow goes to a larger circle that partly obscures the rightmost part of the sphere. The circle shows a zoom in on the surface in the black circle on the sphere. The zoom shows a small portion of the sphere's surface, showing that the grid comes along because the sphere is divided into elongated hexagonal faces with numbers up to at least five-digits. Seven numbers can be fully seen, but there are nine other faces partly shown, five of these with part of their numbers visible, one of these clearly only have four digits. One of the empty faces must also have a number with only 1-3 digits, as no numbers are visible although a significant part of the face is visible.]
[Here follows the numbers in the zoomed in part of the sphere, with  "..." represents numbers being cut off. The numbers are read in lines left to right, even though the numbers are tilted from down towards the right, which could have suggested a different reading order.] 30827 16[bottom part of a cut-off line][small cut-off circle] ...38 11875 25444 ...[top part of a cut-off line]5 12082 28525 3 [left part of a cut-off line]... 13359 13874 [Two cut-off lines, likely the start of the number 2]...
[Caption below the image:] The hardest part of securely generating random 16-bit numbers is rolling the d65536.


Types of Scopes

Explanation:
Electron microscopes , electron telescopes and radio telescopes are special forms of microscopes and telescopes , respectively. This comic explores what you could do with a hypothetical "electron ___-scope" and "radio ___-scope" for other "regular" items whose name also ends in -scope (namely: periscope , stethoscope , kaleidoscope , gyroscope and horoscope ).
The third column with "radio" often plays on different meanings of the word radio: 1) related to radiation and 2) a device for receiving radio communication or broadcasts.
The title text makes a pun on "gyroscope" and a middle-eastern pita wrap called a " gyros ".
Content is a table, with column headings "Regular Blank Scope", "Electron Blank Scope", and "Radio Blank Scope".  Row headings are "Micro", "Tele", "Peri", "Stetho", "Kaleido", "Gyro", and "Horo".
Regular Microscope Look at small stuff Electron Microscope Look at really small stuff Radio Microscope Figure out why your radio broke Regular Telescope Look at stuff that's far away Electron Telescope Detect cosmic rays Radio Telescope Look at distant high-energy stuff Regular Periscope Look for enemy ships Electron Periscope Examine the hull of an enemy ship for structural flaws Radio Periscope Let the crew of your submarine listen to NPR Regular Stethoscope Listen to a patient's chest Electron Stethoscope Burn a patient's skin Radio Stethoscope Play the noises from a patient's chest on NPR Regular Kaleidoscope See cool shapes and colors Electron Kaleidoscope See cool Bremsstrahlung Radio Kaleidoscope Another word for the "Scan" button Regular Gyroscope Balance by spinning Electron Gyroscope Another word for electromagnet Radio Gyroscope Another word for turntable Regular Horoscope Get random life advice Electron Horoscope Predict a particle's quantum state Radio Horoscope Get random life advice from exploding galaxies


Motion Blur

Explanation:
This is analogous to something much more common that people do, by practicing moving their bodies relative to the motion of the camera: reducing blur when the shutter speed is too low.
The title text refers to the fact that only one object - in this case, Cueball - appearing blurry while everything else in the frame is sharp is even more exotic. It can also be seen as a celebration and sarcasm regarding the rare experience of valuing having exotic knowledge and skills. It seems likely Randall has practiced reducing blur, but not succeeded at increasing it, and was possibly exposed to somebody saying "high" shutter speed when they meant "low" shutter speed, but this is presently unverified.
This is somewhat similar to a trick 'used' by some fictional characters who have the power to make themselves unclear to observers or cameras alike. In real-life it is the difference between "stop motion" and "go motion" tricks.
When light hits a human's retina, it is perceived for a short while even after the light has ceased. This means that objects moving across a human's field of vision at a sufficient speed will naturally appear blurry – in our perception, the light arriving right now from the trailing part of the object will mix with the light that arrived a moment earlier, from the leading part of the object.
A camera's shutter speed is the amount of time that the shutter is open for each frame, allowing the image sensor to capture light. If the shutter speed is too high (relative to the frame-rate), this blurring will not occur, and the motion will look unnaturally crisp – if something is too small and/or too quick, the illusion of motion may disappear altogether; the object instead will appear as a brief flash of multiple objects standing still, like in the case of a fast-moving mouse cursor on a screen. See for instance this Videography - Slow Shutter Speed vs. Fast Shutter Speed Comparison .
In cinema, the shutter speed is generally set to double the frame-rate, e.g. 1/48 s for footage shot at 24 fps (one of the lowest standard frame-rates, a remnant from the age of mechanical motion picture cameras and film projectors).
An opposing problem is that of a camera not sufficiently matching the relative motion of a moving object, with a shutter speed that is too slow (and may need to be, given the choice of aperture and lighting conditions). Sports photographers must learn how to scan-and-pan their subjects (runners, horses, vehicles, etc) with enough synchronicity to capture them sharply, and possibly seemingly hanging frozen in mid-air against an artistically-blurred background.
It is unclear how Cueball makes the motion blur include both his feet, as the friction with the ground should hinder them from vibrating horizontally in the manner that may cause for motion blur. Additionally, creating the kind of motion blur he does (with evenly distributed horizontal blur) requires extreme acceleration at both ends of the movement.
[White Hat is holding a camera up to his face looking to the left away from Cueball and Ponytail standing to his right. Cueball is holding one hand, with a balled up fist, up towards White Hat] White Hat: Okay, I'm going to pan around. Cueball: No, wait, your shutter speed is too fast, it will look choppy if—
[White Hat turns clockwise towards Cueball and Ponytail, with the camera held up partly behind his head, so it points in the panel. Cueball clenches both his fists, held down now, and hunches his shoulders. Ponytail stands as before next to him.] Cueball: Hnnnnngh
[White Hat has turned around and is now pointing the camera towards Cueball and Ponytail. Cueball now appears blurry while Ponytail looks normal.]
[Caption below panel:] Expert photographers can learn to generate their own motion blur to compensate for other people's bad camera settings.
This comic remained on xkcd's front page even after the midnight between Monday and Tuesday (in Eastern Time), which is a rare instance that Randall has missed a midnight deadline.


Or Whatever

Explanation:
The Willis Tower (formerly the Sears Tower) is a 108-story, 442.1 meter skyscraper in Chicago. It is currently the third tallest building in North America, and was indeed the tallest building in the world for 25 years, surpassing the World Trade Center upon opening in 1973, and being surpassed by the Petronas Towers upon their opening in 1998.
White Hat conveys some interesting historical trivia to Cueball , regarding the Sears Tower . Cueball then sets the record straight by correcting White Hat's use of the word tower: In the category of 'tower', the Willis Tower was never the tallest. Cueball then realizes he just one-upped White Hat with what he knows about tall structures in general, which might make him sound obsessive, so he tags on the meaningless caveat of "or whatever".
This is meant to diffuse the tension he may have added by his well-meaning contradiction, but could also be taken as a passive-aggressive behaviour by interlocutors who may already be touchy about the original 'correction'.
In the title-text, being already self-conscious that he has overstepped the mark for polite smalltalk, he then hypercorrects the self-perceived tone of his response by explicitly denying that he knows far more about the tower, but only by providing the very facts that he is trying to claim not to know. Alternately, this could be White Hat responding to something else Cueball said, as an annoyed way to either get Cueball to stop, or to make a point that Cueball knows more than is "normal" about skyscrapers.
This comic hinges on the debate about the tallest structure vs tallest building . A building is generally defined as a human-built structure fit for human habitation when it is fit for human habitation, while a structure is generally defined as anything humans make. (Or in some cases, anything an animal makes, like crab shells. )
It is far from unusual for the tallest building (habitable) to be shorter than the tallest structure (uninhabitable), such as in 1974 when the tallest structure was the Warsaw radio mast at 646.38 meters. The radio mast was uninhabitable, [ citation needed ] so the tallest building was (sort-of coincidentally) the Sears Tower at 442.1 meters. The Warsaw tower collapsed in 1991, so it was not the tallest structure for the majority of the '90s.
After the Warsaw Tower's demise, the KVLY-TV mast , which stood at 629 meters, held the record of tallest structure until either 2000 or 2010, with the opening of the Petronius platform and Burj Khalifa respectively. (The date depends on whether you count underwater towers, as the Petronius platform is an oil rig and only 75 meters of the platform are above water). It was also the tallest Guyed mast up until 2019, when it was reduced to 605.6 meters, giving  the KRDK-TV mast the record.
The CN tower stands at 553.3 meters (Measured from top of spire), which is higher than the Sears/Willis tower but shorter than the KVLT-TV mast. It is mentioned as is has some habitable space but not much, causing debate about whether it is a building (Referenced below). It was never the tallest structure, but if it's a building it would have been the tallest in the world from it's opening in 1976 until the Canton Tower 's in 2009. It is currently the 9th tallest building.
The debate surrounding the tallest building does not stop at building vs structure. Architects have long argued about what the height definition of a building should be.  Should it include antennas sitting at the top of the building?  How about spires that form part of the architectural design of the building but are not part of the habitable space?  Should we focus instead on the highest habitable floor?  The debate has historically had relevance every time a new record is claimed by developers eager to reach new heights using any means possible ( Size Does Matter, At Least In The Tallest Building Debate ).
There is yet more debate about what counts as a building vs a structure. While some people would say that any structure with any habitable space is a building, most people in the field agree that there is a certain threshold  of habitable space, below which there is not enough habitable space to count as a "building", even if there is some.
A main point in this debate are TV towers , which are often tall towers with little habitable space in them, but with an observation deck at the top. Examples include the Tokyo Skytree , Fernsehturm Stuttgart , and CN tower. A similar structure is the Dubai Creek Tower , a tower under construction in Dubai, set to become the world's tallest structure. (The Dubai Creek Tower will not, however, broadcast tv signals).
TV towers are sometimes counted as buildings as they do have some habitable space. However, they are often not as they are commonly considered to not have enough habitable space to be buildings, hence Cueball's line "The CN tower isn't always considered a building"
Wikipedia lists the tallest structures, and this YouTube video explains a bit more about tall buildings/structures.  Since 2010 the Burj Khalifa has been both the tallest structure and the tallest building in the world.
[White Hat and Cueball are looking out on a skyline with six smaller skyscrapers and one much taller. The tall building has three plateaus, where it gets thinner before the top. On the top there are also two tall antennas, one twice as high as the other. Around the buldings therare 7 small clouds and two distant birds flying next tot he top of the tallest building. The two are standing on a ground behind a fence, maybe a viewing point, for looking in over the city skyline. They are looking toward the tallest bulding.] White Hat: You know, back in the 90s, the Sears Tower was the world's tallest tower. Cueball: Yeah! Or "building." The CN Tower and the KVLY-TV Antenna were taller, but the CN Tower isn't always considered a building and the antenna is supported by guy wires or whatever.
[Caption below the panel]: Whenever I get self-conscious about how obsessive I sound about some random topic, I panic and tack on "or whatever."


Shuttle Skeleton

Explanation:
The Space Shuttle was a reusable spacecraft system used by NASA from 1981 to 2011, after which it was decommissioned. In this comic, Randall suggests that the nature of the shuttle was in doubt or misunderstood until either an intact 'specimen' (of which there are four) had been dissected, or possibly the remains were reassembled from the two that were lost in accidents .
With its shape, shown in the small image, and the tail fin, it looks a bit like a bony fish or ray . The joke is that after the shuttle was taken out of use, its skeleton was analyzed, and as shown in the comic, was found to have a skeleton typical of a mammal, with details such as the pentadactyl quadripedal bodyform hidden beneath its aerodynamic sweep, as well as having bones (i.e., not primarily cartilage). This morphology is similar to that possessed by a whale. Of course, the skeleton of a spacecraft is not made of bones, but rather of metal and other manufactured materials. [ citation needed ]
As the understanding of the natural world developed, many taxonomic misconceptions were overturned, or at least the scientific terminology was tightened. For instance, it was found that dolphins and whales were mammals, not fish. [ cetacean needed ] Because of convergent evolution – the tendency for distantly-related species to adapt similarly to a given environment – it is often not easy to properly classify organisms merely by observing their exterior. For example, whales and fish have very similar body shapes, as did the extinct plesiosaurs, because life as a swimming vertebrate favors the same adaptations. In lieu of genetic analysis, or even of sufficient observation of them in the wild, the main progress in understanding differences among marine animals was often in dissecting the corpses of creatures found stranded or caught in nets, or reconstructing them from skeletal remains. Together with fossil evidence, insights were developed about their origins and differences from others' origins.
The title text conflates the now-extinct Steller's sea cow , an aquatic mammal related to manatees and named after explorer/zoologist Georg Steller (also extinct), with the adjective "stellar", which means being of a star or stars, such as inter-stellar space or stellar masses.
One might expect that the idea for this comic may have come from the recent California Supreme Court ruling that bumblebees are considered fish under a law which categorized several other invertebrates as part of a broad colloquial category of fish (as in "Fish and Game Department" designations.) However, given the short time between the ruling and the comic's release, it is likely that this was a coincidence.
[In the upper right part of the panel there is a small drawing of the Space Shuttle as seen from above. Beneath it, and to its left, is a much larger drawing with the same outline as the Shuttle. But this time the outer layers have been removed to reveal the inside. This has revealed a skeleton taking up the entire space inside. The head is in the front, and legs and tail at the rear, with arms and fingers in the wings, looking somewhat like a bat's "hand/wings". The bones are white with the frame of the shuttle gray or black. Some of the lines outlining the design of the shuttle are both on the small and the large drawing, along the wings and rear engines. Both feet and arms have five fingers/toes. There seem to be 24 ribs in the very long rib-cage.]
[Caption beneath the panel:] The Space Shuttle was long assumed to be a type of fish or shark, but after it was decommissioned in 2011, analysis of its skeleton determined that it was actually a mammal.