https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=Beret&feedformat=atomexplain xkcd - User contributions [en]2024-03-29T15:10:12ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=2893:_Sphere_Tastiness&diff=3350052893: Sphere Tastiness2024-02-13T17:42:50Z<p>Beret: /* Explanation */ Added Hertzsprung-Russel reference</p>
<hr />
<div>{{comic<br />
| number = 2893<br />
| date = February 12, 2024<br />
| title = Sphere Tastiness<br />
| image = sphere_tastiness_2x.png<br />
| imagesize = 388x392px<br />
| noexpand = true<br />
| titletext = Baseballs do present a challenge to this theory, but I'm convinced we just haven't found the right seasoning.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a STRANGELY TASTY MOON MADE OF RUSSIAN PELMENI - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
<br />
This comic graphs the tastiness vs. size of four roughly spherical objects: {{w|melons}}, {{w|grapes}}, {{w|Earth|Earth}} and the {{w|Moon}}. Based on the the fact that melons and grapes are (in this context) relatively small and tasty to most people, and that planetary scale bodies are relatively large and made of rocks and metals (therefore not being remotely tasty), [[Randall]] postulates the existence of an intermediate body, one which is approximately 800 meters in diameter and "tastes okay".<br />
<br />
This is likely a parody of the {{w|Hertzsprung-Russel Diagram}}, which graphs the relative sizes and luminosities of astronomical bodies, typically stars. <br />
<br />
This is the second comic in a row to feature fruit, graphs and predictions, and continues the theme of a logarithmic axial scale to facilitate plotting a linear regression. Here the line is interpolated between known data, rather than extrapolated beyond it. Such interpolation is quite common in scientific analysis, and is often useful, but this example clearly leads to a ludicrous conclusion. Using such ridiculous analyses to show the dangers of flawed and/or sloppy methodology is a common theme in XKCD.<br />
<br />
There are multiple ways in which this analysis is flawed, and therefore why the conclusion is unsupportable:<br />
* there are only four data points, which is insufficient to extrapolate from.<br />
* these clusters represent entirely different sub-classes of spherical object (fruit vs. astronomical bodies) while other subclasses are not represented at all (the title text mentions this flaw).<br />
* as tight clusters of [[2533: Slope Hypothesis Testing|similarly sourced data]], it effectively reduces it down to two useful data points. This also makes the choice of log-median interpolation unjustified.<br />
* the 'tastiness' scale has no indication of what assessment (subjective or objective) it records. Nor does it even have graduations, making it unknown if the graph is linear-log or log-log (or otherwise), changing the implied meaning behind the choice of straight-line interpolation.<br />
<br />
The title text points out that {{w|baseball (ball)|baseballs}} seem to refute this theory since they're not usually thought of as tasty, but they're between the sizes of grapes and melons, which would place them in the bottom left of the graph, way off the fit line. Baseballs are typically made of a combination of a rubber or cork center wrapped in yarn, and covered by either horsehide, cowhide or synthetic leather. In point of fact, there are many, many common round objects that completely fail to conform to this graph, but rather than acknowledge that this analysis is fatally flawed, Randall suggests that the problem is that we lack "the right seasonings". While seasonings can improve the taste of foods, it's implausible that the inedible components of baseballs would be rendered "tasty" with any conceivable combination of seasonings. This argument lampoons the use of "cherry picking" and motivated reasoning, which researchers include only data points which fit their hypothesis, and make up reasons to exclude those which don't. This is obviously very poor science, but less exaggerated versions are all too common in scientific studies. <br />
<br />
The comic refers to this plot as research. This is an exaggeration, since two clusters of paired points are rarely considered sufficient for research purposes. But plotting a justifiably sufficient quantity of data points on a logarithmic plot, and then drawing a line through them, is a common way to visualize an actual exponential relationship more comprehensibly. An example of that is the {{w|Gutenberg–Richter law}} where the magnitude of earthquakes (an intrinsically logarithmic scale) in a particular region is plotted together with the frequency of occurance, typically resulting in a statistically significant straight line.<br />
<br />
Other fruit opinions have previously been mentioned in [[388: Fuck Grapefruit]], but it is unknown what the line would be like if Randall included grapefruit.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Graph with Y axis using an arrow indicating tastiness from "Not Tasty" to "Tasty" and X axis labelled "Sphere Diameter (meters)" with a logarithmic scale running from 10<sup>-5</sup> to around 10<sup>8</sup> (with 10<sup>-3</sup>, 10<sup>0</sup>, 10<sup>3</sup> and 10<sup>6</sup> labelled).]<br />
<br />
:[The graph contains two points for "Grapes" and "Melons" at the "Tasty" end of the Y axis, between 10<sup>-2</sup> and 10<sup>-1</sup> meters, and two points for "The Earth" and "The Moon" at the "Not Tasty" end, both around 10<sup>7</sup> meters. A straight dashed line shows a linear interpolation between the points. There's a circle with a question mark about halfway between them.]<br />
<br />
:[Caption below the panel:]<br />
: My research suggests the existence of an 800-meter sphere that tastes okay.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Charts]]<br />
[[Category:Food]]<br />
[[Category:Astronomy]]<br />
[[Category:Baseball]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2847:_Dendrochronology&diff=3271832847: Dendrochronology2023-10-27T20:02:11Z<p>Beret: </p>
<hr />
<div>{{comic<br />
| number = 2847<br />
| date = October 27, 2023<br />
| title = Dendrochronology<br />
| image = dendrochronology_2x.png<br />
| imagesize = 332x444px<br />
| noexpand = true<br />
| titletext = These anomalies are known as Miyake events, named for the pioneering scientist who discovered them and was tragically devoured by a carnivorous tree.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by TOM BOMBADIL'S ARCH NEMESIS - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
<br />
{{w|Dendrochronology}} is a scientific method of using tree rings to tell the age of a tree and learn about historical climate from features found in each ring. It's based on the fact that trees add a new ring each year, so counting the rings will tell a tree's age in years. Additionally, climate and ecology affect the size and composition of that year's ring, so scientists can use them to estimate what conditions were like each year.<br />
<br />
In some cases, tree rings contain remnants of specific events, such as large volcano eruptions, atomic tests, or droughts. The comic posits that in 1635 trees were {{w|carnivorous}}, and the ring for that year contains the bones of the animals (or humans) that they ate. Apparently this was just a temporary condition, since the rings after this have no bones.<br />
<br />
The title text says that anomalous years like this are called {{w|Miyake event}}, after a scientist named Miyake who discovered them and was then eaten by the trees. In actual fact, Miyake events are periods when there are a larger than normal amount of certain isotopes that are created by cosmic rays. Evidence of these events are often found in ancient tree rings, and Fusa Miyake discovered them when investigating tree rings from years 774-775; but he wasn't devoured by the trees.{{citation needed}}<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
Dendrochronologists can date wood samples by identifying growth ring anomalies that correspond to specific events. For example, it's often possible to spot the horrible summer of 1635 when trees turned carnivorous. <br />
<br />
{{comic discussion}}</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=704:_Principle_of_Explosion&diff=309900704: Principle of Explosion2023-04-07T04:15:34Z<p>Beret: "But it could also be considered kinky; something Mrs. Lenhart's son would not like to hear about." ... HOW. WHAT??</p>
<hr />
<div>{{comic<br />
| number = 704<br />
| date = February 19, 2010<br />
| title = Principle of Explosion<br />
| image = principle_of_explosion.png<br />
| titletext = You want me to pick up waffle cones? Oh, right, for the wine. One sec, let me just derive your son's credit card number and I'll be on my way.<br />
}}<br />
<br />
==Explanation==<br />
[[Cueball|Cueball's]] friend (who also looks like Cueball) explains the {{w|principle of explosion}}, a classical theorem of logic, which shows that if within a system of logic you can use the axioms and rules of deduction to derive (prove) a contradiction, it then becomes possible to derive any statement at all within that system (whether it’s actually true or not). In particular, if you start by assuming a self-contradictory statement, you can derive anything.<br />
<br />
Cueball then proceeds to misinterpret (perhaps intentionally) that you can derive any ''fact'' about the physical world. His formula of {{w|propositional logic}} in the third panel reads "'''P''' and not '''P'''", where '''∧''' is the formal logic symbol for "and" and '''<sup>¬</sup>''' is the symbol for "not". '''P''' stands for a proposition. As "'''P''' and not '''P'''" is shorthand for "'''P''' is both true and false", this forms a contradiction from which the principle of explosion can begin. Humorously and to his friend's bewilderment he then successfully manages to 'derive' the phone number for his friend's mom. <br />
<br />
:'''An example from math''': If you assume that √2 is a rational number, you can 'prove' things that are obviously false, such as the fact that some numbers must be both even and odd. Consequently, you can draw the conclusion that √2 must be an irrational number (provided such a thing exists at all! - luckily, it does and obeys the same calculation rules as for rational numbers; this is how {{w|proof by contradiction}} works.)<br />
<br />
:This can be seen in a {{w|Truth Table}}:<br />
:{| class="wikitable"<br />
|-<br />
! P<br />
! ¬P<br />
! P ∧ ¬P<br />
! P ∧ ¬P ⇒ Q<br />
|-<br />
| T<br />
| F<br />
| F<br />
| T<br />
|-<br />
| F<br />
| T<br />
| F<br />
| T<br />
|}<br />
<br />
:The formula P ∧ ¬P ⇒ Q is true in every possible interpretation. No matter what propositions are substituted for P and Q the implication is true. So if a single example of a contradiction were found, then every proposition would be true, (and simultaneously false).<br />
<br />
After deriving the phone number Cueball instantly calls his friend's mom, who turns out to be [[Miss Lenhart|Mrs. Lenhart]]. She asks Cueball out, without any preamble, to his friend's vexation. It does not get better when it is obvious that she wishes to drink "cheap" {{w|boxed wine}} with him, and Cueball is free tonight! There is definitely a hint of {{w|Mrs. Robinson}} over Mrs. Lenhart here. <br />
<br />
In the title text we hear more of Cueball's (one-sided) conversation with Mrs. Lenhart. She asks him to pick up waffle cones, a variety of {{w|ice cream cone}}. And when he sounds bewildered by this she explains that it is for drinking the wine. This is probably not a very good idea, since waffles are typically not water proof and would also dissolve into the wine. The rest of the title text is just more of the main comic's derivation joke, since Cueball will use a second to derive her son's credit card number, so he can buy the cones at his expense.<br />
<br />
In reality, Cueball really could start with the principle of explosion and "prove" a statement such as "Mrs. Lenhart's phone number is {{w|867-5309}}", but the same could be said of any conceivable phone number, most of which don't actually belong to Mrs. Lenhart, and because his axiom system is inconsistent, he has no way of knowing which is correct. Likewise for his friend's credit card number. Much like {{w|The Library of Babel}}, an axiom system which can prove ''any'' statement might as well prove nothing. Perhaps Cueball already knows these phone and credit card numbers, and is just talking about the principle of explosion to mess with his friend.<br />
<br />
==Transcript==<br />
:[Cueball's Cueball-like friend is talking to him.]<br />
:Friend: If you assume contradictory axioms, you can derive anything. It's called the principle of explosion.<br />
:Cueball: ''Anything?'' Lemme try.<br />
<br />
:[Cueball is writing on a piece of paper on a desk.]<br />
<br />
:[Cueball is holding up a piece of paper to his friend, while holding a phone.]<br />
:Cueball: Hey, you're right! I started with '''P∧<sup>¬</sup>P''' and derived your mom's phone number!<br />
:Friend: That's not how that works.<br />
<br />
:[The friend is looking at the piece of paper, while Cueball is talking to someone on a phone. The desk from before can be seen to the right.]<br />
:Cueball: Mrs. Lenhart?<br />
:Friend: Wait, this ''is'' her number! How—<br />
:Cueball: Hi, I'm a friend of— Why, yes, I ''am'' free tonight!<br />
:Friend: ''Mom!''<br />
:Cueball: No, box wine sounds lovely!<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Miss Lenhart]]<br />
[[Category:Multiple Cueballs]]<br />
[[Category:Logic]]<br />
[[Category:Your Mom]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2707:_Astronomy_Numbers&diff=3052972707: Astronomy Numbers2023-01-26T07:47:50Z<p>Beret: /* Explanation */ Resolved "incomplete" tag</p>
<hr />
<div>{{comic<br />
| number = 2707<br />
| date = December 5, 2022<br />
| title = Astronomy Numbers<br />
| image = astronomy_numbers_2x.png<br />
| imagesize = 593x315px<br />
| noexpand = true<br />
| titletext = I adopted a cat that weighs 12 solar masses. Laser pointers love chasing it.<br />
}}<br />
<br />
==Explanation==<br />
<br />
Space [https://www.youtube.com/watch?v=Hv1spjsvu-A is big] and the things that are in space can also end up being very big themselves. As a result, most quantities in astronomy have huge scales. For example, Earth has a mass 10<sup>23</sup> times more than the average human, and the Sun is 10<sup>5</sup> times more than that, which itself is 10<sup>12</sup> times less massive than the Milky Way. The same applies to speeds, distances, and time, which can often be measured in terms of light speed, light-years, and millions or billions of years. Because of this, it's a truly unusual occurrence for anything in space to end up in the fairly narrow range of scales of mass, size, speed, or time that humans can easily grasp.<br />
<br />
[[Ponytail]], apparently a scientist researching something related to Earth's orbit, finds that on the date in question (January 1, although the year is not specified), Earth will be approaching the sun at a velocity of 65 miles per hour—an extremely common and normal-sounding velocity to American ears, often used as a speed limit on highways in the US. Ponytail is clearly a little thrown off by this, and remarks that she finds it "suspicious" when reasonably human-scaled numbers come up.<br />
<br />
She then extends this discomfort to things that should be measured in regular numbers, such as the weight of cats. The vet, [[Megan]], is seemingly used to this problem (perhaps she gets a lot of astronomers, or Ponytail has a hypochondriac cat), so she restates the 12-lb weight of Ponytail's cat in solar masses. Since using this unit yields an ''incredibly'' small number, 3×10<sup>-30</sup> (a three preceded by a decimal point and 29 zeroes), it evidently sounds more plausible to the astronomer. This weight is in fact about 13 lb 2 oz (about 5.5 kilograms), slightly heavier than the initial figure given for the cat, but within [[2585: Rounding|rounding error]] for the single digit of precision that Megan uses. According to [[2205:_Types_of_Approximation | 2205: Types of Approximation]] that rounding error is unusually small for an astronomer, though. Also, the usage of weight gives the word "scales" in "scales should all be incomprehensible" a double meaning because scales are used to weigh things, including cats. A scale that returns weights in solar masses would indeed be incomprehensible to most people. However, this could be unintentional on Randall's part.<br />
<br />
The Earth's orbital velocity around the Sun is far above any "normal" scales (around 30 kilometers per second or 108,000 kilometers per hour). However, Earth has a pretty circular orbit around the Sun, so most of this speed ends up being tangential (sideways) rather than radial (towards or away from) the Sun, which is the value relevant for Ponytail's calculations. On January 1, Earth's radial velocity is close to its smallest value because we reach our closest point to the Sun in the first few days of January each year (in 2023, {{w|Perihelion|perihelion}} happens on January 4) so by January 1, it's nearly come to a standstill before it starts traveling away from the Sun again. On the other hand, by April 3, 2023, Earth will be receding from the Sun by almost 500 meters per second or 1800 kilometers per hour, a less normal speed for the average person to encounter in everyday life.{{citation needed}} 65 miles per hour is approximately equal to 105 kilometers per hour, although the even more typical scientific value (in {{w|International System of Units|SI}} derived units) would be 29 meters per second.<br />
<br />
The title text suggests that laser pointers "love chasing" a new cat with a weight of 12 solar masses (an inversion of the typical cat behavior of [[729: Laser Pointer|chasing laser pointer dots]]). A 12 solar mass cat would have the dominant gravitation well in our solar system, which would make everything fall towards the cat – including laser pointers. Furthermore, all gravitational fields bend light towards their center; a 12 solar mass object could bend light quite a lot. The path of the light from a laser pointer aimed near such a cat would bend towards it or "chase" it. In fact, anything with 12 solar masses would have a Schwarzschild radius of around 36 kilometers, so any cat-sized thing with that mass would be a black hole, drawing all light within a 72-kilometer sphere around it into its singularity.<br />
<br />
==Transcript==<br />
:[Ponytail is standing in front of a whiteboard writing on it with a pen, while Cueball looks over her shoulder from behind her. On the board is an almost circular ellipse with a cross that centers on a dot towards the left side of it. On the right side there is a small circle on the ellipse's line. There are several lines of wiggles representing unreadable text. To the left of the ellipse there are two lines near the top of and four near at the bottom of the ellipse. Ponytail is writing a fifth line below these almost under the ellipse. At the bottom to the left there is a rectangular frame with a line of text beneath it and at the bottom left corner there is a line forming a half closes rectangle around two dots.]<br />
:Ponytail: …And we need to correct for our elliptical orbit. On January 1<sup>st</sup>, Earth will be approaching the sun at a rate of ...let's see...<br />
:Ponytail: 65 miles per hour.<br />
:Ponytail: Weird. Okay.<br />
:Cueball: Weird?<br />
<br />
:[Ponytail has turned towards Cueball, the pen is no longer in her hand and the white board is no longer shown.]<br />
:Ponytail: I get suspicious whenever I see a normal number in astronomy. We're not supposed to have those. Feels wrong.<br />
:Ponytail: Scales should all be incomprehensible.<br />
<br />
:[Megan in a lab-coat raised her hand palm up towards an animal carrier cage standing on her desk. The cage has a handle and five air holes are at the top. Behind two of them something black inside the cage can be seen. Ponytail is standing on the other side of the desk looking at Megan. Above the top of the panels frame there is a panel with a label:]<br />
:Earlier, at the vet:<br />
:Megan: Your cat weighs 12 lbs.<br />
:Ponytail: Ridiculous, nothing weighs "12". You must mean 10<sup>-20</sup>? Or 10<sup>40</sup>?<br />
:Megan: Fine. Your cat weighs 3x10<sup>-30</sup> solar masses.<br />
:Ponytail: Okay. Better.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Astronomy]]<br />
[[Category:Cats]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2712:_Gravity&diff=3016132712: Gravity2022-12-17T07:09:10Z<p>Beret: </p>
<hr />
<div>{{comic<br />
| number = 2712<br />
| date = December 16, 2022<br />
| title = Gravity<br />
| image = gravity_2x.png<br />
| imagesize = 740x700px<br />
| noexpand = true<br />
| titletext = It's a long way down.<br />
}}<br />
<br />
*To experience the interactivity, visit the [http://xkcd.com/2712/ original comic].<br />
==Explanation==<br />
{{incomplete|Created by HOTBLACK DESIADO’S TAX RETURNS - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
In this interactive comic, the viewer pilots a small spaceship throughout a vast area in space. The viewer is capable of exploring various bodies and planets within the play area, many containing easter eggs alluding to What If? 2 and previous xkcd comics. The flight mechanics are largely, if not entirely Newtonian, so the player vessel is capable of using the gravity of planets to alter its trajectory or even enter orbit. The player's spaceship has several indicator circles around it which appear when a gravitational body comes into range, showing the direction towards their center of gravity. <br />
<br />
Throughout the play area are coins that change your rocket ship into different rockets and even non-space based vehicles, including humans. <br />
<br />
The comic was released as a promotion for Randall's new book [https://xkcd.com/what-if-2/ What If? 2], which was released in September and is available for purchase. Many of the planets contain references to various What If? articles.<br />
<br />
The comic is similar to [http://xkcd.com/1608/hoverboard hoverboard], which celebrated Thing Explainer instead.<br />
<br />
===Spoiler Alert!===<br />
<br />
The following is an incomplete table of features:<br />
<br />
{|class="wikitable sortable"<br />
! <br />
! <br />
!<br />
! colspan="4"|References<br />
! <br />
|-<br />
! Description<br />
! Transcript<br />
! Tiles (X, Y)<br />
! What If<br />
! XKCD<br />
! Movies<br />
! Other<br />
! Explanation<br />
|-<br />
|'''Earth'''<br />
|<br />
|(14360, 14360)<br />
|<br />
|<br />
|<br />
|<br />
|The starting planet. The player begins on the launch pad in a landed position.<br />
|-<br />
|'''Europa'''<br />
|<br />
|(13180, -2540)<br />
|<br />
|<br />
|<br />
|<br />
|Europa, one of Saturn's many moons (in real life). A broken, icy crust has a single path into its core.<br />
|-<br />
|Europa's crust<br />
|"It's so unfair we don't get to compete in EuroVision."<br />
"The region of the solar system where liquid water can exist on the surface is the habitable zone, and the region where it can exist beneath the surface of moons is the Eurozone."<br />
<br />
"WHIRRRR"<br />
|<br />
|Y<br />
|<br />
|<br />
|<br />
|Europa's crust, with a single entrance into the core demarcated by an octopus leaving a hole. <br />
Cueball states that Europa is in the Eurozone, a pun on the ''other'' Eurozone, with liquid underneath its surface.<br />
<br />
A roomba whirs across the icy crust.<br />
<br />
Cueball has a hairdryer and is melting the surface of the crust. A direct reference to [https://what-if.xkcd.com/35/ What If's Hairdryer].<br />
|-<br />
|Europa's core<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|A watery ocean with octopi looking out into the great unknown using telescopes. This is a reference to octopi's intelligence here on earth! There's also a secret path leading to a book club, through the wreck of the Edmund Fitzgerald. <br />
|-<br />
|'''B-612'''<br />
|"Asteroid deflection mission to earth. The package is delivered. Commencing planetary threat neutralization." <br />
|(2610,3700)<br />
|<br />
|Y<br />
|<br />
|<br />
|A reference to [https://xkcd.com/618/ Asteroid]. The little prince is having his asteroid blown up as it was heading towards Earth, apparently.<br />
|-<br />
|'''Dog park planet'''<br />
|<br />
|(1240, 11230)<br />
|<br />
|<br />
|<br />
|<br />
|A planet with a dog park. Covered in dogs, along with dog walkers and some fences. There's a hole being dug by two dogs and a dog bone empty space in the center.<br />
|-<br />
|'''What If? 2 scenario planet'''<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|'''The Sun'''<br />
|<br />
|(-14950, 12080)<br />
|<br />
|<br />
|<br />
|<br />
|Difficult to escape from if you hit the core. <br />
|-<br />
|Sun's core <br />
|<br />
|<br />
|Y<br />
|<br />
|<br />
|<br />
|Difficult to escape from. Can be escaped by rotating around the sun until an escape-like velocity could be reached.<br />
|-<br />
|'''Soupiter'''<br />
|<br />
|(-800, -9040)<br />
|Y<br />
|<br />
|<br />
|<br />
|A planet made of soup, with a core. As commented by Cueball, noodle soup. Has several small versions of other planets floating around it.<br />
|-<br />
|'''Earth without Japan'''<br />
|<br />
|(-7680, -5850)<br />
|Y<br />
|<br />
|<br />
|<br />
|Earth, except it's missing japan.<br />
|-<br />
|'''Just Japan'''<br />
|<br />
|<br />
|Y<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|'''A blob labeled "Pigeons"'''<br />
|<br />
|(-9020, -2490)<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|'''Starship Enterprise'''<br />
|<br />
|<br />
|<br />
|<br />
|Y<br />
|<br />
|Star Trek reference<br />
|-<br />
|'''Dinosaur planet'''<br />
|<br />
|<br />
|<br />
|<br />
|Y<br />
|<br />
|An homage to [https://www.qwantz.com/ Dinosaur Comics], a webcomic Randall has mentioned several times before. All the dinosaurs on the planet are black-and-white versions of the clip art dinosaurs in that comic. Also references the Jurassic Park movies, in which the long grass depicted is a plot point in later films.<br />
|-<br />
|'''What If? 1 scenario planet'''<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|'''Cat blocking traffic flowing through portals'''<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|'''Edge of the Universe'''<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|It's actually just a planet labeled "edge of the universe", since there's no real edge. <br />
|-<br />
|'''A tree larger than the planet it's growing on'''<br />
|<br />
|<br />
|<br />
|Y<br />
|<br />
|<br />
|May be a reference to [https://www.explainxkcd.com/wiki/index.php/2:_Petit_Trees_(sketch) Petit Trees]. More probably, a reference to ''The Little Prince'', a french children's novel about a traveller from a distant asteroid. In the novel, baobab trees are a serious threat to the Prince's home asteroid, as they are so large that their roots would engulf the asteroid entirely. Randall has alluded to The Little Prince numerous times before, especially in what-if articles.<br />
|-<br />
|'''Milliways'''<br />
|<br />
|<br />
|<br />
|<br />
|Y<br />
|<br />
|Hitchhiker's guide to the galaxy reference<br />
|-<br />
|'''The Great Attractor'''<br />
|<br />
|<br />
|<br />
|Y<br />
|<br />
|<br />
|<br />
|-<br />
|'''Present'''<br />
|<br />
|(22820,-18920)<br />
|<br />
|Y<br />
|<br />
|<br />
|The XKCD cast react to giving each other What if 2? as a present.<br />
|-<br />
|'''Black hole cluster'''<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|A cluster of black holes with extremely high gravitational strength, set to the maximum of 2048. Not particularly easy to land on with multiple conflicting gravitational fields, but once landed on, rather difficult to escape.<br />
|}<br />
<br />
==Data Dump==<br />
<br />
extracted from a JSON blob near the bottom of <code>https://xkcd.com/2712/comic.js</code>.<br />
I believe this to be all the data but i'm not sure. this should probably be on a different page but i'll leave that up to the smart people<br />
<pre style="height:10em;overflow-y:scroll;"><br />
{<br />
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"consumable": "yes",<br />
"effect": "transformship|ship-tintin",<br />
"image": "coin",<br />
"loc": [<br />
359,<br />
-815<br />
],<br />
"size": [<br />
40,<br />
40<br />
]<br />
},<br />
"coin-figure": {<br />
"consumable": "yes",<br />
"effect": "transformship|ship-figure",<br />
"image": "figure",<br />
"loc": [<br />
-15050,<br />
-2984<br />
],<br />
"size": [<br />
40,<br />
40<br />
]<br />
},<br />
"coin-regular": {<br />
"consumable": "yes",<br />
"effect": "transformship|ship2",<br />
"image": "regular",<br />
"loc": [<br />
-29976,<br />
-8077<br />
],<br />
"size": [<br />
40,<br />
40<br />
]<br />
},<br />
"coin-soccerball": {<br />
"consumable": "yes",<br />
"effect": "transformship|ship-soccer",<br />
"image": "soccerball",<br />
"loc": [<br />
15293,<br />
11140<br />
],<br />
"size": [<br />
40,<br />
40<br />
]<br />
}<br />
},<br />
"locations": {<br />
"b612": {<br />
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],<br />
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"width": 2048<br />
},<br />
"earth": {<br />
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14360<br />
],<br />
"radius": 3275,<br />
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],<br />
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},<br />
"europa": {<br />
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13180,<br />
-2540<br />
],<br />
"radius": 1625,<br />
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},<br />
"goodhart": {<br />
"gravity": 5000,<br />
"height": 8192,<br />
"loc": [<br />
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],<br />
"radius": 1625,<br />
"width": 8192<br />
},<br />
"greatattractor": {<br />
"gravity": 450000,<br />
"height": 4096,<br />
"loc": [<br />
-297000,<br />
-125000<br />
],<br />
"radius": 800,<br />
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},<br />
"japanmoon": {<br />
"gravity": 50,<br />
"height": 2048,<br />
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],<br />
"radius": 67,<br />
"width": 2048<br />
},<br />
"maw1": {<br />
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],<br />
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},<br />
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},<br />
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},<br />
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},<br />
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},<br />
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],<br />
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},<br />
"maw2": {<br />
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-8831<br />
],<br />
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},<br />
"maw3": {<br />
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"height": 2048,<br />
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],<br />
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},<br />
"maw4": {<br />
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],<br />
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},<br />
"maw5": {<br />
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},<br />
"maw6": {<br />
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"loc": [<br />
-29328,<br />
-7575<br />
],<br />
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},<br />
"maw7": {<br />
"gravity": 2000,<br />
"height": 2048,<br />
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-7426<br />
],<br />
"radius": 18,<br />
"width": 2048<br />
},<br />
"maw8": {<br />
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-7160<br />
],<br />
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},<br />
"maw9": {<br />
"gravity": 2000,<br />
"height": 2048,<br />
"loc": [<br />
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-6910<br />
],<br />
"radius": 18,<br />
"width": 2048<br />
},<br />
"nojapan": {<br />
"gravity": 80,<br />
"height": 2048,<br />
"loc": [<br />
-7680,<br />
-5850<br />
],<br />
"radius": 200,<br />
"width": 2048<br />
},<br />
"origin": {<br />
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"height": 4096,<br />
"loc": [<br />
0,<br />
0<br />
],<br />
"radius": 630,<br />
"width": 4096<br />
},<br />
"outside": {<br />
"gravity": 200,<br />
"height": 16384,<br />
"loc": [<br />
0,<br />
-14500<br />
],<br />
"radius": 125,<br />
"width": 16384<br />
},<br />
"peeler": {<br />
"gravity": 50,<br />
"height": 2048,<br />
"loc": [<br />
-9270,<br />
620<br />
],<br />
"radius": 40,<br />
"width": 2048<br />
},<br />
"pigeons": {<br />
"gravity": 100,<br />
"height": 2048,<br />
"loc": [<br />
-9020,<br />
-2490<br />
],<br />
"radius": 160,<br />
"width": 2048<br />
},<br />
"present": {<br />
"gravity": 300,<br />
"height": 2048,<br />
"loc": [<br />
22820,<br />
-18920<br />
],<br />
"radius": 195,<br />
"width": 2048<br />
},<br />
"qwantz": {<br />
"gravity": 1400,<br />
"height": 4096,<br />
"loc": [<br />
11060,<br />
24870<br />
],<br />
"radius": 850,<br />
"width": 4096<br />
},<br />
"remnant": {<br />
"gravity": 9000,<br />
"height": 4096,<br />
"loc": [<br />
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3800<br />
],<br />
"radius": 537,<br />
"width": 4096<br />
},<br />
"roads": {<br />
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"loc": [<br />
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],<br />
"radius": 30,<br />
"width": 16384<br />
},<br />
"soupiter": {<br />
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"height": 4096,<br />
"loc": [<br />
-8000,<br />
-9040<br />
],<br />
"radius": 812,<br />
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},<br />
"steerswoman": {<br />
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"height": 4096,<br />
"loc": [<br />
-35070,<br />
-2500<br />
],<br />
"radius": 520,<br />
"width": 4096<br />
},<br />
"sun": {<br />
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"height": 16384,<br />
"loc": [<br />
-14950,<br />
12080<br />
],<br />
"radius": 540,<br />
"width": 16384<br />
}<br />
},<br />
"player": {<br />
"animation": "player.png",<br />
"animcount": 4,<br />
"startloc": [<br />
0,<br />
750<br />
],<br />
"targetheight": 59<br />
},<br />
"tile_height": 1024,<br />
"tile_source": "tile",<br />
"tile_width": 1024<br />
}<br />
<br />
</pre><br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
Welcome!<br />
<br />
To celebrate the world of what if? 2, here is your very own planet to explore!<br />
<br />
Give someone the science question-and-answer book what if? 2 for Christmas:<br />
xkcd.com/whatif2<br />
<br />
{{comic discussion}}<br />
[[Category:Space]]<br />
[[Category:Book promotion]]<br />
[[Category:Interactive comics]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2708:_Mystery_Asterisk_Destination&diff=3009712708: Mystery Asterisk Destination2022-12-09T17:02:48Z<p>Beret: /* Explanation */ Resolved "incomplete" tag</p>
<hr />
<div>{{comic<br />
| number = 2708<br />
| date = December 7, 2022<br />
| title = Mystery Asterisk Destination<br />
| image = mystery_asterisk_destination_2x.png<br />
| imagesize = 288x248px<br />
| noexpand = true<br />
| titletext = If you ever see the † dagger symbol with no unmatched footnote, it means the writer is saying the phrase while threatening you with a dagger.<br />
}}<br />
<br />
==Explanation==<br />
<br />
This comic pertains to the use of asterisks and other symbols for footnotes or endnotes. It jokes that when an asterisk appears after a word without a corresponding footnote, it refers to this comic. Missing footnotes can be frustrating, and this comic may provide closure for some readers, similar in spirit to [[391: Anti-Mindvirus]], and opposite to the tension created by the unmatched parenthesis in [[859: (]].<br />
<br />
The title text jokes that unmatched instances of † (the dagger symbol, also used for footnotes) are threats being made by the author to the reader with a physical dagger. As of this writing, it states "If you ever see the † dagger symbol with no '''''un'''''matched footnote...", forming a double negative. This is likely a typo intended as "...no matching footnote."<br />
<br />
An unpaired asterisk or dagger often does not refer to a footnote, and thus does not constitute a mystery. Examples include programming languages and mathematical expressions using asterisks such as for the multiplication operator, and dates of birth and death which are sometimes indicated with an asterisk or dagger respectively.<br />
<br />
==Transcript==<br />
:[A blank panel with text at the bottom.]<br />
:'''*'''Whenever you see a mystery asterisk that doesn't have a matching footnote, it points here.<br />
<br />
{{comic discussion}}</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2689:_Fermat%27s_First_Theorem&diff=3001382689: Fermat's First Theorem2022-12-01T07:51:24Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2689<br />
| date = October 24, 2022<br />
| title = Fermat's First Theorem<br />
| image = fermats_first_theorem_2x.png<br />
| imagesize = 280x248px<br />
| noexpand = true<br />
| titletext = Mathematicians quickly determined that it spells ANT BNECN, an unusual theoretical dish which was not successfully cooked until Andrew Wiles made it for breakfast in the 1990s.<br />
}}<br />
<br />
==Explanation==<br />
<br />
This is a reference to {{w|Fermat's Last Theorem}}, humorously implying that {{w|Pierre de Fermat}} created a similar theorem as a child. Fermat's Last Theorem states that no three positive integers ''a'', ''b'', and ''c'' satisfy the equation ''a''<sup>''n''</sup>+''b''<sup>''n''</sup>=''c''<sup>''n''</sup> for any integer value of ''n'' greater than 2. It is notable for having remained unproved for hundreds of years, despite many attempts to prove it; it's called his 'last' theorem because it was the last one left without proof or disproof. The Taniyama–Shimura conjecture (now known as the Modularity theorem) and the epsilon conjecture (now known as Ribet's theorem) together imply that Fermat's Last Theorem is true. The epsilon conjecture, proposed by Jean-Pierre Serre, became provable thanks to Ken Ribet in 1986. {{w|Andrew Wiles}}, with assistance from his former student {{w|Richard Taylor (mathematician)|Richard Taylor}}, succeeded in proving a special case of the Taniyama-Shimura conjecture for semistable elliptical curves in 1995, which finally established the proof of Fermat's Last Theorem. (The full Modularity theorem was subsequently established as correct by Wiles's former students Brian Conrad, Fred Diamond and Richard Taylor, and Christophe Breuil in 2001.)<br />
<br />
The young Fermat here didn't try to prove the mathematical equation, but simply tried to read it as words, treating the "+" sign as a "t" so that "A<sup>N</sup>+" can be read as "ANT". His interpretation was quickly disproved because there's no "A" between "B" and "C", and no "O" between "C" and "N". It's unclear if this is considered Fermat's First Theorem because it was the first he made, or because it was the first to be conclusively disproved.<br />
<br />
In the title text, the "words" are "ANT BNECN", treating the equals sign "=" as an "E"; while "=" doesn't look especially close to "E", it is similar in that it contains horizontal bars in a horizontally symmetrical arrangement (and of course, it can be read as "equals", which begins with "E"). If the letter E is written in sans-serif block text in white on a black background, the "negative space" between the Upper Bar, the Middle Bar and the Lower Bar of the E form a =. The comic shows a blackboard with white letters. The text then references Wiles, asserting that he proved this modified form of Fermat's First Theorem as well by cooking this "ant bnecn" (whatever "bnecn" is) as breakfast.<br />
<br />
[[2492: Commonly Mispronounced Equations]] also contains equations pronounced as if they were words in the ordinary sense.<br />
<br />
==Transcript==<br />
<br />
:[A Hairy-like boy, representing Pierre de Fermat as a child, stands at a blackboard holding a piece of chalk. To his right is Miss Lenhart. The following text is somewhat crudely written on the blackboard:]<br />
:A<sup>N</sup> + B<sup>N</sup> = C<sup>N</sup><br />
:SPELLS<br />
:ANT BACON<br />
<br />
:[Caption below the panel]: <br />
:Fermat's ''First'' Theorem was quickly disproved<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Math]]<br />
[[Category:Comics featuring Miss Lenhart]]<br />
[[Category:Comics featuring real people]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2694:_K%C3%B6nigsberg&diff=3001372694: Königsberg2022-12-01T07:45:57Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2694<br />
| date = November 4, 2022<br />
| title = Königsberg<br />
| image = konigsberg_2x.png<br />
| imagesize = 448x343px<br />
| noexpand = true<br />
| titletext = At first I thought I would need some gold or something to pay him, but then I realized that it was the 18th century and I could just bring a roll of aluminum foil.<br />
}}<br />
<br />
==Explanation==<br />
<br />
[[File:Konigsberg_bridges.png|frame|right|{{w|Königsberg}}, Prussia in Euler's time, showing the Pregel river and its seven bridges. Two of the original seven bridges no longer exist,[https://goo.gl/maps/ChdBoeQMr3AQPi446] although there are three new bridges. The Baltic port city is now Kaliningrad, a Russian exclave.]]<br />
<br />
This comic is about the {{w|Seven Bridges of Königsberg}}, a seminal {{w|graph theory}} problem solved by the famous mathematician {{w|Leonhard Euler}}.[https://www.maa.org/press/periodicals/convergence/leonard-eulers-solution-to-the-konigsberg-bridge-problem] The problem was whether a path through the city crossing each of the seven bridges just once exists, without crossing the river forks any other way. In 1736, Euler proved that no such path exists. This result is considered to be the first theorem of graph theory and the first proof in the theory of networks[http://www-personal.umich.edu/~mejn/courses/2004/cscs535/review.pdf] — a subject now generally regarded as a branch of {{w|combinatorics}} — and presaged the development of {{w|topology}}. Combinatorial problems of other types had been considered since antiquity. {{w|Graph (discrete mathematics)|Graphs}} are a data structure common in many algorithmic problems in computer science.<br />
<br />
[[Cueball]] attempts to cheat on the final exam in his algorithms class by traveling back in time to commission the construction of an eighth bridge before Euler could learn of the problem, allowing a trivial solution that would remove the rationale for further analysis. He hopes that this would alter his present-day timeline in such a way that the test becomes easier because graph theory might never have been developed. The use of the word "tried" implies failure, which is probably a good thing since his success would create a {{w|Temporal_paradox#Grandfather_paradox|paradox}}. [[:Category:Time travel|Time travel]] is a recurring topic on xkcd and examples where attempts to change the past fails has also been used before like in [[1063: Kill Hitler]].<br />
<br />
With the addition of the eighth bridge, it becomes possible to cross each bridge exactly once, starting at the north bank and ending on the larger eastern island, or vice-versa. However, there is still no way to traverse each bridge exactly once and return to the starting point, because the altered graph would have an {{w|Eulerian trail|Euler trail}} but not an Euler cycle. Thus the problem might still have been interesting to Euler.{{Citation needed}} (Adding a ninth bridge connecting the north bank to the east island would render the problem completely trivial.) We can't say whether Euler or others would have developed graph theory anyway, or whether Cueball's exam would have been any easier or more difficult.<br />
<br />
An alternative modification allowing an easy solution is to remove bridges. During World War II, two bridges to the central island connecting it to the north and south banks were destroyed by bombing, so today there is an Eulerian trail across the five remaining bridges.<br />
<br />
The title text alludes to the fact that ordinary {{w|aluminum foil}}, which was not commercially available until 1911, would have been a tremendously valuable curiosity in the 18th century, which didn't even have {{w|tin foil}}. Aluminum was a highly priced metal before the 1880s when inexpensive methods were developed to refine it. The {{w|Washington Monument#Aluminum_apex|Washington Monument}} was constructed with a tip made of pure aluminum due to its value and conductive capacity. Aluminum had not been extracted in its pure form at the time of Euler, and was known only in compounds such as {{w|alum}}, so the metal would have been unique and exotic. The value of aluminum and the use of it as the tip of the Washington Monument was also mentioned in [[1608: Hoverboard]] where a heist to steal the tip is [https://www.explainxkcd.com/wiki/images/6/6f/1608_0995x1083y_Tip_of_Washington_monument.png depicted].<br />
<br />
==Transcript==<br />
:[Cueball, standing next to two men wearing wigs, pointing with a pointer at a map showing the seven bridges problem, with an extra bridge added in dashed lines]<br />
:Cueball: Lord Mayor of Königsberg, I will reward you handsomely if you construct this bridge before my friend Leonhard arrives.<br />
<br />
:[Caption below the panel:]<br />
:I tried to use a time machine to cheat on my algorithms final by preventing graph theory from being invented.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring real people]]<br />
[[Category:Time travel]]<br />
[[Category:Math]]<br />
[[Category:Programming]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2704:_Faucet&diff=3000802704: Faucet2022-11-30T06:41:32Z<p>Beret: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 2704<br />
| date = November 28, 2022<br />
| title = Faucet<br />
| image = faucet_2x.png<br />
| imagesize = 315x414px<br />
| noexpand = true<br />
| titletext = It's okay, they can figure out which control positions produce scalding water via a trial-and-error feedback loop with a barely-perceptible 10-second lag.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a SCALDING AND CONFUSED FAUCET - Please change this comment when editing this page. You are encouraged to delete this tag too soon.}}<br />
<br />
A variety of {{w|Tap (valve)#Nomenclature|faucet}} controls have been designed for the control of a shower or sink's water output; however, Randall seems to find all the existing options to be inadequate in some way and posits in this comic that engineers share a desire to create a more ideal design. The comic shows one such engineer, looking unkempt and rambling like a madman as he explains to an off-screen character how his new faucet design works. The off-screen character promptly tells him that he should get some sleep, a request which the engineer ignores in favor of continuing the search for the "perfect" water faucet.<br />
<br />
In general, a faucet's output has two independent parameters: flow velocity and temperature; some particularly frustrating faucet controls only offer one degree of freedom which simultaneously turns up the flow rate and the temperature, and thus cannot fully explore the shower-space (making it sometimes difficult to find a comfortable setting). Some faucets can adjust both parameters but only have a single lever which must be angled along degrees of freedom which are not always labeled clearly or intuitively, and this may also irk Randall. Other faucets have two independent controls for the flow of cold water and hot water; however, while these are highly granular, it can be difficult to adjust the parameters independently e.g. change the temperature without changing the flow, or changing the flow without changing the temperature. <br />
<br />
While two-handle faucets may seem simple in the abstract, they are imperfect in practice. In older houses or those with hot water systems based on tankless or instant hot water heaters, the hot water pressure is rarely the same as the cold water pressure. This can cause problems with cold water flowing back into the hot line, creating temperature drifts, unexpected changes in temperature based on slight input changes, and non-reproducibility in shower settings.<br />
<br />
Newer systems include "thermostatic valves" which are designed to alleviate these problems; ideally, they contain one control for temperature and one for flow, which would seem to fit the "non-confusing" brief and solve Randall's problems. However, designing a system technically functional and making it intuitive (and making it work in practice for all water supply systems) is non-trivial, so Randall may have had trouble with even these faucets in the past.<br />
<br />
The experience of a shower being affected by a significant change in usage of water elsewhere in the building (a running washing machine clicking into or out of a rinse-cycle, or the sudden use of a flush-toilet) is a typical one in any place without deliberately over-engineered plumbing. Purpose built hotels ''may'' have an in-built degree of resilience of this kind, but over many temporary stay-overs by guests (each new set having to become familiar with the plumbing) will develop wear and tear that later guests will not be automatically aware of — including the gradual wearing off of the traditional red and blue arrows intended to show the polarity of hot-and-cold controls.<br />
<br />
The title text is a hyperbolic and slightly sarcastic explanation of the merits of a faucet system, presumably from the engineer who designed it. It describes that the user can identify an undesirable result, e.g. of scalding water, through a trial-and-error feedback loop. But, with a decidedly long delay in response time as the scalding (then non-scalding) mix works its way through the system, it means that they are left waiting for any adjustments made to prove themselves as useful (or not) whilst still experiencing the prior state of the water.<br />
<br />
==Transcript==<br />
:[A designer with short, messy hair and a scuffed face stands in front of a whiteboard. He is holding a pen and is sketching with it above his head. His other empty hand is also held up above his head, possibly touching part of the sketch. On the whiteboard are various scribbles, pieces of illegible text, drawings of waves, arrows, and side views and cross sections of a faucet. In the center of the whiteboard, drawn with soft, sketched lines is the faucet, the designers empty hand is touching it. It has a vertical wall-mounted square base with a semicircle above. Attached to the semicircle is a tightly curled helical tube that curls twice, this is the one the designer is drawing on at the moment. Below it is a drawing of a spout with a stream of water going almost to the bottom of the board. On the floor around the designers feet is an upright can, a large piece of crumpled paper, and 6 smaller pieces of crumbles or ripped paper and one larger flat piece if paper. He talks to someone off-panel, who replies from a star burst on the right border of the panel.]<br />
:Designer: ...So you tighten the spiral to make the water hotter, and to adjust the flow rate you just-<br />
:Off panel voice: You need to sleep.<br />
:Designer: '''''No! I can do this!'''''<br />
<br />
:[Caption below the panel:]<br />
:Every designer's dream is to finally invent a non-confusing faucet control.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Dreams]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2697:_Y2K_and_2038&diff=3000792697: Y2K and 20382022-11-30T06:36:59Z<p>Beret: /* Explanation */ Resolved "incomplete" tag</p>
<hr />
<div>{{comic<br />
| number = 2697<br />
| date = November 11, 2022<br />
| title = Y2K and 2038<br />
| image = y2k_and_2038_2x.png<br />
| imagesize = 527x190px<br />
| noexpand = true<br />
| titletext = It's taken me 20 years, but I've finally finished rebuilding all my software to use 33-bit signed ints.<br />
}}<br />
<br />
==Explanation==<br />
<br />
[[File:Year 2038 problem.gif|thumb|An animation of the 2038 bug in action. The {{w|integer overflow}} error occurs at 03:14:08 UTC on 19 January 2038.]]<br />
<br />
The Y2K bug, or more formally, the {{w|year 2000 problem}}, was the computer errors caused by two digit software representations of calendar years incorrectly handling the year 2000, such as by treating it as 1900 or 19100. The {{w|year 2038 problem}} is a similar issue with timestamps in {{w|Unix time}} format, which will overflow their {{w|Signed number representations|signed}} 32-bit binary representation on January 19, 2038.<br />
<br />
While initial estimates were that the Y2K problem would require about half a trillion dollars to address, there was widespread recognition of its potential severity several years in advance. Concerted efforts among organizations including computer and software manufacturers and their corporate and government users reflected unprecedented cooperation, testing, and enhancement of affected systems costing substantially less than the early estimates. On New Year's Day 2000, few major errors actually occurred. Those that did usually did not disrupt essential processes or cause serious problems, and the few of them that did were usually addressed in days to weeks. The software code reviews involved allowed correcting other errors and providing various enhancements which often made up at least in part for the the cost of correcting the date bug.<br />
<br />
It is unclear whether the 2038 problem will be addressed as effectively in time, but documented experience with the Y2K bug and increased software modularity and access to source code has allowed many otherwise vulnerable systems to already upgrade to wider timestamp and date formats, so there is reason to believe that it may be even less consequential and expensive. The 2038 problem has been previously mentioned in [[607: 2038]] and [[887: Future Timeline]].<br />
<br />
This comic assumes that the 38 years between Y2K and Y2038 should be split evenly between recovering from Y2K and preparing for Y2038. That would put the split point in 2019. The caption points out that it's now, in 2022, well past that demarcation line, so everyone should have completed their "Y2K recovery" and begun preparing for year 2038. It is highly unlikely that there are more than a very few consequential older systems that still suffer from the Y2K bug, as systems built to operate this millennium handle years after 1999 correctly. The topic of whether or not Y2K was actually as big of a problem as it was made out to be remains hotly debated. The main arguments falling into the general camps of "nothing bad happened, Y2K would have overwhelmingly been an inconvenience rather than a problem" vs. "very little happened ''only'' because of the massive effort put into prevention". It is unlikely that there will ever be a conclusive answer to the question, with the truth probably being somewhere in between those two extremes. Whatever the answer to that question may be, the reaction to Y2K did result in a significant push towards, and raise in public awareness of, clean and futureproofed code.<br />
<br />
The title text refers to replacing the 32-bit signed Unix time format with a hypothetical new 33-bit signed {{w|Integer (computer science)|integer}} time and date format, which is very unlikely as almost all contemporary computer data structure formats are allocated no more finely than in 8-bit bytes. Doing this may seem complicated to new software developers, but recompiling with a larger size of integers was a normal solution for the Y2K bug among engineers of [[Randall]]'s generation, who learned to code when computer memory space was still at a premium. Taking 20 years to develop and implement such a format is not entirely counterproductive, as it would add another 68 years of capability, but it is a far less efficient use of resources than upgrading to the widely available and supported 64-bit Unix time replacement format and software compatibility libraries.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
[A timeline rectangle with 37 short dividing lines between the two ends, defining it into 38 minor sections, with the label "2000" above, associated with the leftmost edge, "2038" associated with the rightmost edge and "2019" directly over the centermost division that starts the section which covers that year, which is also extended to form a dotted line divided the whole height of the timeline into two equal 19-section halves. The left half has the label "Recovering from the Y2K bug" and the right half is labeled "Preparing for the 2038 bug". A triangular arrowhead labeled "Now" is also above indicating a rough position most of the way through the section that would represent the year 2022.]<br />
<br />
[Caption:] Reminder: By now you should have finished your Y2K recovery and be several years into 2038 preparation.<br />
<br />
{{comic discussion}}<br />
[[Category:Calendar]]<br />
[[Category:Computers]]<br />
[[Category:Programming]]<br />
[[Category:Timelines]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2691:_Encryption&diff=3000782691: Encryption2022-11-30T06:34:57Z<p>Beret: /* Explanation */ Resolved "incomplete" tag; this does not appear to have any relationship to Elon buying twitter, as twitter is not an encrypted messaging app, and in any case it has nothing to do with the completeness of this explanation</p>
<hr />
<div>{{comic<br />
| number = 2691<br />
| date = October 28, 2022<br />
| title = Encryption<br />
| image = encryption_2x.png<br />
| imagesize = 235x380px<br />
| noexpand = true<br />
| titletext = WARNING: PEOPLE NAMED EVE ARE PROHIBITED FROM INSTALLING THIS APP!<br />
}}<br />
<br />
==Explanation==<br />
<br />
When teaching encryption / cryptography, it is common to use a story about sending messages from {{w|Alice and Bob|Alice to Bob}} (Party "A" and Party "B" respectively). Cueball claims to have created a texting app that only allows for this one thing. It does not, however, allow "Bob" to reply, making the usefulness of the app questionable at best. It is unclear how it enforces the name restriction, but it is possible that the app figures out the name of the phone's owner. The title text mentions Eve, who in the typical story represents an "eavesdropper", someone who attempts to intercept the messages between Alice and Bob. The fact that persons named Eve are 'forbidden' from installing the app suggests that it might not actually be as secure as Cueball advertises -- it may be that he naively thinks that it's just the name that makes the eavesdropper, and that by excluding all Eves, Alice's messages to Bob will remain private. It is not clear which phones will support this app, but it appears to be perfectly suited for the [[:Category:xkcd Phones|xkcd Phones]].<br />
<br />
Note also that Eve being forbidden to install the app parallels another Eve being forbidden to eat an apple (an app-le?) in a common retelling of the Biblical story of the Garden of Eden (though the actual Biblical text doesn't refer to an apple). Spoiler alert: The Biblical Eve ate the forbidden fruit anyway, and this Eve is probably going to install the app anyway...<br />
<br />
The comics [[177: Alice and Bob]] and [[1323: Protocol]] are also about Alice and Bob.<br />
<br />
Even if the assumption that you could divine people's roles and motives from their names were correct, if the names of the users don't need to be verified, it seems possible for a bad actor to circumvent the security features of the app by simply lying about their name. Genuine users could also undermine the security with double installations and a complete mess of a contact list in which everyone's names are somehow identified as "Alice" or "Bob", in order to increase its utility to them. Also, it would appear that "Bob" needn't be the commonly used name of the message receiver, in this scenario – it could also be a diminutive of what he is actually known by. Thus a user might claim to be "Bob" whichever his given name is.<br />
<br />
This may be related to the announcement that Signal would be discontinuing support for SMS/MMS messages.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Cueball showing a phone to a long-haired woman, identified in the caption as Alice]<br />
:Cueball: The app will let you send messages to your friend Robert, or my brother.<br />
:Alice: Can they reply?<br />
:Cueball: No.<br />
<br />
:[Caption below the panel]:<br />
:My new secure texting app only allows people named Alice to send messages to people named Bob.<br />
<br />
{{comic discussion}}<br />
[[Category: Comics featuring Cueball]]<br />
[[Category: Cryptography]]<br />
[[Category: Smartphones]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=No_One_Was_Hurt&diff=299940No One Was Hurt2022-11-26T05:21:58Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| date = July 6, 2022<br />
| title = No One Was Hurt<br />
| image = no_one_was_hurt.png<br />
| titletext = See how the smoke obscures things so you don't see the approaching tornado until the firework streamers start to swirl right before the lightning hits the launcher. Thank God Cousin Ed was filming in slow motion. And, uh, that no one was hurt.<br />
| lappend = 404<br />
}}<br />
<br />
==Explanation==<br />
<br />
This comic was originally uploaded normally on the [[xkcd]] website as number [[2642]], before being taken down and replaced by [[2642: Meta-Alternating Current]]. This was most likely done in response to the wave of shootings across the country during the 2022 {{w|Independence Day (United States)|US Independence Day}} celebrations, including {{w|Highland_Park_parade_shooting|a deadly mass shooting at the parade in Highland Park, Illinois}} which was recorded on video where people were injured and killed. So, a comic about 4th of July (Independence Day) celebrations where someone could have been hurt can be seen as in bad taste.<br />
<br />
[[Ponytail]] is about to show [[Cueball]] and [[Megan]] a video of a dramatic accident from a 4th of July celebration, likely with {{w|fireworks}}, in which nobody ended up harmed. Randall suggests that being told nobody got hurt implies such a video will be particularly interesting or exciting. This is because if the disclaimer is needed, it implies that there was a certain degree of peril created by the events in the video, and this would typically create excitement for the viewer. Here is [https://www.youtube.com/watch?v=Y5QBiZIxWbA&ab_channel=BYUUniverse an example video] in which probably no one was hurt.<br />
<br />
The title text describes a particularly dramatic fireworks show interrupted by a tornado and thunderstorm, the joke being that the speaker seems more appreciative that it was recorded in slow-motion video than that nobody was harmed.<br />
<br />
=== Citations ===<br />
<br />
The Wikipedia article {{w|Mass shootings in the United States|"Mass shootings in the United States"|m|}} lists mass shootings in the USA, {{w|List_of_mass_shootings_in_the_United_States_in_2022|"List of mass shootings in the United States in 2022"}} more thoroughly lists those that happened in 2022, {{w|Highland Park parade shooting|"Highland Park parade shooting"}} details the specific shooting in Illinois, and {{w|Mass shootings in the United States|"Mass shootings in the United States"}} discusses US mass shootings instead of just listing them. The [https://www.gunviolencearchive.org/reports/mass-shooting Gun Violence Archive] website tracks mass shootings in the USA.<br />
<br />
==Transcript==<br />
:[Ponytail is showing her phone to Cueball and Megan.]<br />
:Ponytail: Okay, first of all, no one was hurt...<br />
:[Caption below the panel]:<br />
:How you know you're about to see a really good 4th of July video<br />
<br />
{{comic discussion}}<br />
[[Category:Deleted comics]]<br />
[[Category:Extra comics]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Comics featuring Megan]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2698:_Bad_Date&diff=2999392698: Bad Date2022-11-26T05:19:24Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2698<br />
| date = November 14, 2022<br />
| title = Bad Date<br />
| image = bad_date_2x.png<br />
| imagesize = 666x261px<br />
| noexpand = true<br />
| titletext = "Even split between us, this will pay way better than the Jumanji sponsorship I came into the date with."<br />
}}<br />
<br />
==Explanation==<br />
<br />
This comic is a spoof of Internet {{w|Influencer marketing|influencers}}. These are people with large social media followings who mention products in their videos in exchange for payment from the companies that produce these products, as a form of advertising. <br />
<br />
In the comic, Megan and Cueball are not intentionally live-streaming their date, but someone around them is uploading video footage of their date, because they were having an argument about the movie {{w|Jumanji}}. Megan realized that they can capitalize on this by getting a sponsor.<br />
<br />
The argument then shifts to whether they're going to sleep together after the date. Cueball says he won't go home with Megan because she doesn't have the [[2096|mattress brand sold by their sponsor]]. She responds by pointing out a feature of that brand: their same-day delivery policy. This argument could easily be a TV commercial for the mattress, though Cueball's ultimate retort suggests (whether he wants it to or not) that there still won't be a "happy ending" conclusion to this play-acting, either fictionally or once real life resumes.<br />
<br />
The title text hints, however, that Megan was already before the date going to promote the {{w|Jumanji (franchise)|Jumanji franchise}}, for her own gain. Megan's realization that she could not discuss this subject since Cueball had not seen it leads to her initial reaction starting their date to be shared, but not for the reason she had anticipated. But then when she sees they are still going viral, she is ready to use this new situation to bring in a lot of "mattress money". And as it turns out even when splitting with Cueball she will earn more. Since Cueball presumably came into the date with the intention of finding a romantic partner rather than gaining a sponsorship, he will probably get even less happy with Megan. Alternatively, as he plays along with her in the last frame, he sees this as an acceptable or even preferable arrangement (considering that the date wasn't going all too well in the first place).<br />
<br />
==Transcript==<br />
:[Cueball and Megan are sitting at a table in a restaurant with their meals still on their plate and filled wine glasses. Megan hands her cellphone over the table to Cueball.]<br />
:Megan: ''Psst — this date is going so badly that the people around us are posting it live.''<br />
:Megan: ''Look.'' <br />
<br />
:[Zoom in just on Cueball in his chair. He is holding the cellphone while he sees a video. What the video shows is shown above him in a frame. The "video" window shows a scene from earlier in their date. And below the picture there is a title and below that an eye with the number of followers shown. In the scene they are sitting as in the first panel, but both have their arms raised. Cueball's arms towards Megan and she has her arms above her head. Small lines from above her head from where her speech line comes out indicates that she is agitated and speaks loudly.]<br />
:Megan in video: Unbelievable– Have you even ''seen'' Jumanji?<br />
:Video caption: Date disaster 252k following<br />
:Cueball: ''Oh no.''<br />
<br />
:[Zoom in on Megan in her chair.]<br />
:Megan: ''But it's okay: I got us a sponsorship.''<br />
:Megan: ''You just need to play along...''<br />
<br />
:[Scene expands to include the two nearest people at the two nearby tables. Both are typing frantically at their phones, (indicated with vibration lines on either side of their phones), using both hands, to document the date disaster live. Ponytail is to the left of them with food on her plate and a glass of water on her table and Hairy is to the right with a wine glass on his table. Cueball has raised one hand with a finger pointing up. Megan points a finger towards Cueball but is looking down at her phone held up in the other hand, to check their following.]<br />
:Cueball: I could '''''never''''' go home with someone with such bad taste in mattresses. I need the soft support of the ProFirm 3000.<sup>®</sup><br />
:Megan: Wait, I can order one! With same-day delivery, it can–<br />
:Cueball: '''You had your chance.'''<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Comics featuring Hairy]]<br />
[[Category:Romance]]<br />
[[Category:Internet]]<br />
[[Category:Social networking]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2692:_Interior_Decorating&diff=2999382692: Interior Decorating2022-11-26T05:17:32Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2692<br />
| date = October 31, 2022<br />
| title = Interior Decorating<br />
| image = interior_decorating_2x.png<br />
| imagesize = 281x424px<br />
| noexpand = true<br />
| titletext = It all came flat-packed in Pandora's Box.<br />
}}<br />
<br />
==Explanation==<br />
<br />
The {{w|Damocles|sword of Damocles}}, {{w|Siege Perilous}}, {{w|Chekhov's gun}}, and {{w|Pandora's box}} are mythical objects associated with impending threats. These names are now used metaphorically for complex concepts related to danger. Cueball seems to have either taken inspiration from these tales and named some objects after them or (possibly with Beret Guy's help) managed to obtain the genuine items, using them as decorations in his house.<br />
<br />
The Sword of Damocles refers to a (likely apocryphal) lost history of Sicily, in which Damocles was said to be an obsequious courtier who envied the king's power and luxury. The king offered to let Damocles serve as king for a day, but during that day, arranged for a sword to be hung above the throne, suspended from its pommel by a single hair. This was to teach Damocles the lesson that, along with the privileges of being king, there was also perpetual and inescapable danger and anxiety. The term has passed into general use for any tenuous situation in which serious harm is perpetually a clearly present threat.<br />
<br />
The Siege Perilous, in {{w|Matter of Britain|Arthurian legend}}, is a seat at the Round Table, reserved by Merlin for the knight destined to retrieve the Holy Grail. It was said to be fatal to any unworthy person who sat in it. The term is used as a metaphor for any situation that's exceptionally dangerous to anyone not fully prepared.<br />
<br />
Chekhov's Gun is a writing principle highlighting the importance of conservation of detail. The term originates from playwright Anton Chekhov, who repeatedly used the example of an unfired gun to advocate removing superfluous elements from a narrative. In one such case, he said "If in the first act you have hung a pistol on the wall, then in the following one it should be fired. Otherwise don't put it there." (It should be noted that, like most artistic rules, experienced writers will deliberately violate this advice when appropriate, especially to creatively misdirect similarly experienced audiences.) Cueball might not want Megan touching it because doing so means it will be fired shortly afterwards, following through its core concept.<br />
<br />
Pandora's Box is a tale from Greek Mythology. According to myth, Pandora was the first woman, created by Hephaestus, and was given a jar (later translated as "box") and told never to open it. Eventually she did, and unleashed all the miseries into the world. The term has come to represent any situation where a small but ill-considered action results in numerous, often intractable, problems. <br />
<br />
Given that two of the objects are potential hazards (the sword and the gun) and the third explicitly fatal, it is quite apt that they would come in such a box.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
:[Cueball and Megan stand in a room. At one wall a sword hangs by a thread above a chair. On another wall a rifle is fastened to a board with illegible writing. Megan has one arm stretched towards the rifle.]<br />
:Cueball: Yeah, I think the sword of Damocles looks nice hanging over the Siege Perilous.<br />
:Cueball: Hey, don’t touch Chekhov’s gun!<br />
<br />
:[Caption below panel:]<br />
:My home decorating theme is "ominous metaphorical objects."<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Fiction]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2691:_Encryption&diff=2999372691: Encryption2022-11-26T05:15:19Z<p>Beret: /* Explanation */ Added some stuff, removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2691<br />
| date = October 28, 2022<br />
| title = Encryption<br />
| image = encryption_2x.png<br />
| imagesize = 235x380px<br />
| noexpand = true<br />
| titletext = WARNING: PEOPLE NAMED EVE ARE PROHIBITED FROM INSTALLING THIS APP!<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by ALICE FOR BOB - Please change this comment when editing this page.''Possibly connected to Elon buying Twitter? thoughts? talk about secure messaging apps'' Do NOT delete this tag too soon.}}<br />
<br />
When teaching encryption / cryptography, it is common to use a story about sending messages from {{w|Alice and Bob|Alice to Bob}} (Party "A" and Party "B" respectively). Cueball claims to have created a texting app that only allows for this one thing. It does not, however, allow "Bob" to reply, making the usefulness of the app questionable at best. It is unclear how it enforces the name restriction, but it is possible that the app figures out the name of the phone's owner. The title text mentions Eve, who in the typical story represents an "eavesdropper", someone who attempts to intercept the messages between Alice and Bob. The fact that persons named Eve are 'forbidden' from installing the app suggests that it might not actually be as secure as Cueball advertises -- it may be that he naively thinks that it's just the name that makes the eavesdropper, and that by excluding all Eves, Alice's messages to Bob will remain private. It is not clear which phones will support this app, but it appears to be perfectly suited for the [[:Category:xkcd Phones|xkcd Phones]].<br />
<br />
Note also that Eve being forbidden to install the app parallels another Eve being forbidden to eat an apple (an app-le?) in a common retelling of the Biblical story of the Garden of Eden (though the actual Biblical text doesn't refer to an apple). Spoiler alert: The Biblical Eve ate the forbidden fruit anyway, and this Eve is probably going to install the app anyway...<br />
<br />
The comics [[177: Alice and Bob]] and [[1323: Protocol]] are also about Alice and Bob.<br />
<br />
Even if the assumption that you could divine people's roles and motives from their names were correct, if the names of the users don't need to be verified, it seems possible for a bad actor to circumvent the security features of the app by simply lying about their name. Genuine users could also undermine the security with double installations and a complete mess of a contact list in which everyone's names are somehow identified as "Alice" or "Bob", in order to increase its utility to them. Also, it would appear that "Bob" needn't be the commonly used name of the message receiver, in this scenario – it could also be a diminutive of what he is actually known by. Thus a user might claim to be "Bob" whichever his given name is.<br />
<br />
This may be related to the announcement that Signal would be discontinuing support for SMS/MMS messages.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Cueball showing a phone to a long-haired woman, identified in the caption as Alice]<br />
:Cueball: The app will let you send messages to your friend Robert, or my brother.<br />
:Alice: Can they reply?<br />
:Cueball: No.<br />
<br />
:[Caption below the panel]:<br />
:My new secure texting app only allows people named Alice to send messages to people named Bob.<br />
<br />
{{comic discussion}}<br />
[[Category: Comics featuring Cueball]]<br />
[[Category: Cryptography]]<br />
[[Category: Smartphones]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2688:_Bubble_Universes&diff=2999352688: Bubble Universes2022-11-26T05:11:41Z<p>Beret: Removed incomplete tag, and removed reference to economic inflation, as nowhere in the comic is money, finances, or economics mentioned</p>
<hr />
<div>{{comic<br />
| number = 2688<br />
| date = October 21, 2022<br />
| title = Bubble Universes<br />
| image = bubble_universes_2x.png<br />
| imagesize = 740x188px<br />
| noexpand = true<br />
| titletext = The theory finally unifies cosmic inflation and regular inflation.<br />
}}<br />
<br />
==Explanation==<br />
<br />
A {{w|Eternal_inflation#Overview|bubble universe}} is a concept in the {{w|Inflation (cosmology)|inflation theory of cosmology}} in which our observable universe is just one of many "bubbles" of matter and radiation that formed after the {{w|Big Bang}}.<br />
<br />
The comic seems to be recursive, where one Cueball's bubble universe contains another Cueball doing the same thing, blowing bubbles, seeming to contain the whole scene within one of the bubbles in the original scene. This may reference cosmological models like the {{w|Big Bounce}}, in which a new universe emerges from a previous universe. A similar view is in the "{{w|turtles all the way down}}" view of the universe, but here the universe is suspended in bubbles, and those bubbles suspended in a universe suspended in bubbles, "all the way down" (or at least one layer down).<br />
<br />
The title text claims this theory "Finally unifies cosmic inflation and regular inflation." Cosmic inflation refers to the expansionary phase of the universe shortly after the Big Bang; this would explain why that happened with the simple proposition that it was a bubble and inflated like regular bubbles do. (Ignoring various issues – like the sheer size of the universe, at least in terms of its own scale.)<br />
<br />
The scene looks like it could be part of an infinite recursion. The two Cueballs and grounds are similar but not identical, a self-similarity (also known as expanding symmetry or unfolding symmetry) common in [https://en.wikipedia.org/wiki/Fractal fractals].<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
[Cueball blowing expanding bubbles. In the largest one is a whole new universe with another Cueball blowing similar bubbles. The bubbles are progressively darker: the first ones are regular transparent/white bubbles, and as they grow, they turn gray then dark, to match the black night sky, with stars, galaxies, planets and other astronomical bodies] <br />
<br />
<br />
{{comic discussion}}<br />
[[Category:Space]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Multiple Cueballs]]<br />
[[Category:Puns]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2687:_Division_Notation&diff=2999342687: Division Notation2022-11-26T05:09:00Z<p>Beret: Removed incomplete tag; concern had been addressed</p>
<hr />
<div>{{comic<br />
| number = 2687<br />
| date = October 19, 2022<br />
| title = Division Notation<br />
| image = division_notation_new_2x.png<br />
| imagesize = 235x310px<br />
| noexpand = true<br />
| titletext = Science tip: Scientists hardly ever use the two-dot division sign, and when they do it often doesn't even mean division, but they still get REALLY mad when you repurpose it to write stuff like SALE! ALL SHOES 30÷ OFF!<br />
}}<br />
<br />
==Explanation==<br />
<br />
In this comic there is another one of [[Randall|Randall's]] [[:Category:Tips|Tips]], this time a [[:Category:Science tip|Science Tip]], however, it is only mentioned in the title text. See below for more.<br />
<br />
This comic pokes fun at some of the ways to write the {{w|Division (mathematics)|division}} operation in math. In this comic, [[Randall]] has used A as the dividend (the number being divided) and B as the divisor (the number that A is divided by). Division is the fourth simplest arithmetic operation in mathematics, after addition, subtraction, and multiplication.[https://plato.stanford.edu/entries/principia-mathematica/#PartIVRelaArit]<br />
<br />
The first two of the seven notations shown are the {{w|division sign}} (÷) and the {{w|long division}} notation used for {{w|short division}} and {{w|long division}} in beginning arithmetic. (Note: division typography is only used in some countries, and there are [https://en.wikipedia.org/wiki/Long_division#Notation_in_non-English-speaking_countries different notations in the non-English speaking world]). These methods of division are often used by school children because the ÷ sign is what most people use when first learning division, and the short division format is usually the first algorithm learned for dividing arbitrary dividends, typically starting with the easier abbreviated short division form.<br />
<br />
The expression on the third line, A/B, is the way division is usually written in software code. The four simple arithmetic operations in programming usually are +, -, *, /. This line was not in the [[media:division_notation_2x.png|first version]] of the comic. This is most commonly seen in regular mathematics as it somewhat saves space, and is easy to type with the slash key. Additionally, it uses standard {{w|ASCII}} characters instead of sophisticated notation. A notable exception is {{w|APL_(programming_language)|APL}}, which uses an idiosyncratic character set modeled after traditional arithmetic.<br />
<br />
The expression on the fourth line, <sup>A</sup>/<sub>B</sub>, is how division is usually written by hand {{Citation needed}}. It is nearly identical to the fraction notation that follows, but the diagonal line allows each number to be bigger while still fitting into a single line of text. The third line's representation is the best approximation of this line's notation on a computer, without using more obscure Unicode characters. The Unicode character set can be used to accurately represent division as on the fourth line in plain text, using a small set of precomposed fractions (⅔, ⅕, etc.), regular numerals and [https://unicode-explorer.com/c/2044 U+2044 FRACTION SLASH] (e.g. 22⁄7, provided font support exists), or superscript and subscript numerals (e.g. ²²/₇, or ²²⁄₇ with the fraction slash). Using any of these requires a greater knowledge of Unicode, and the know-how (and, possibly, patience) to type them, so it is likely that only a Unicode enthusiast would type division like this. You could also use HTML, like this: <sup>22</sup>/<sub>7</sub>.<br />
<br />
The fifth notation is the way division is written in science and intermediate and higher mathematics: <table style="display: inline-table; line-height: 0.75em; vertical-align: middle; font-size:10pt; text-size-adjust: none;"><tr><td><u>A</u></td></tr><tr><td>B</td></tr></table>, i.e. the dividend on the top of the expression, over the divisor on the bottom with a horizontal line separating them. This is how a {{w|Fraction|fraction}} would be written. It has the advantage of clearly separating the numerator and denominator when they are longer expressions, such as polynomials, without needing to add parentheses. This format is mostly used in written and professionally typeset math, as it can't be typed without something like {{w|MathML}}, {{w|LaTeX}} or HTML tables.<br />
<br />
The sixth, "fancy," notation uses a negative exponent. The exponent -1 is equivalent to {{w|Multiplicative inverse|reciprocation}}. It can be used to keep an entire division expression on one line. Note that AB<sup>-1</sup> is equal to <sup>A</sup>/<sub>B</sub> only if A and B are in a commutative ring (and B has an inverse). If A and B are, for example, matrices, AB<sup>-1</sup> is not the same in general as B<sup>-1</sup>A (and the notation <sup>A</sup>/<sub>B</sub> is never used in this case as it would be ambiguous). The AB<sup>-1</sup> format is also often used to express physical units.<br />
<br />
The final form of notation declares a function. The writer defines a new function, F, that takes in the parameters A and B, before listing out the function's definition (trailing off in increasingly smaller text). Defining things as functions is very normal for mathematics, but likely not very efficient at all to commonly do for the simple operation of division. Occasionally a highly formalized definition such as this could be a setup for an elaborate and extensive proof, hence Randall warns the reader they should escape while they still can. Integer division can be defined in terms of multiplicative inequalities and the remainder, or modulo ('%' in most programming languages) operator. This situation is likely to occur in many sorts of algebra, where one might have to define what "division" means for two elements of a mathematical object such as a group, ring, or magma. One example would be an object G, such that, for two elements A and B of G, "A divided by B" is defined as an element C such that CB=A, or alternatively as an element C such that BC=A. These definitions will differ if multiplication in G is not commutative. Furthermore, if such a C is not unique, the function F(A,B) will need to include a method to select a unique value for "A divided by B" for each A and B. Thus, the F(A,B) in the comic might not even refer to a uniquely defined operation, but simply to the property of a function F(A,B) that is a valid division operation on G, given some definition of division. You were warned.<br />
<br />
The title text is a [[:Category:Science tip|Science Tip]]. It discusses how the division sign (÷) has fallen out of favor in most professional contexts (the ISO-80000 guidelines even specify the symbol "should not be used") yet has resisted all efforts to repurpose it as a new function. Specifically, it pokes fun at how similar the division sign is to a {{w|percent sign}} (%). A scientist might be really mad at the use of the division sign as an alternative to a percent sign because it is the wrong symbol in that context, ever though they never use it for the original meaning any more. The use of ÷ instead of % is something that may appear on signs for discount offers.<br />
<br />
==Transcript==<br />
{{incomplete transcript| Really should have descriptions instead of 'span styles'... Consider giving it descriptive labels instead (or at least as well as)... Do NOT delete this tag too soon.}}<br />
:[The transcript has both formatted text for visuals and a description at the start of the line.]<br />
:[Underlined text:] <u>Division notation</u> <br />
<br />
:[A [Division sign] B is above, B [Long division symbol] A is below. They are connected by a close brace.] <table style="display: inline-table; line-height: 1em; vertical-align: middle; font-size:10pt; text-size-adjust: none;"><tr><td>A÷B</td></tr><tr><td>B⟌A</td></tr></table>} <br />
:[Label on the right:] Schoolchild<br />
<br />
:A/B <br />
:[Label:] Software engineer<br />
<br />
:[A/B except the A is slightly above and the B is slightly below, and the slash is more diagonal to fit them.] <sup>A</sup>⁄<sub>B</sub> <br />
:[Label:] Normal person or Unicode enthusiast<br />
<br />
:[A fraction with A on the top and B on the bottom.] <table style="display: inline-table; line-height: 0.8em; vertical-align: middle; font-size:10pt; text-size-adjust: none;"><tr><td><u>A</u></td></tr><tr><td>B</td></tr></table> <br />
:[Label:] Scientist<br />
<br />
:[AB with -1 in superscript.] AB<sup>-1</sup> <br />
:[Label:] Fancy scientist<br />
<br />
:F(A, B) [text gets smaller] such that [text gets smaller] F(G)= [Text is too small to read] <br />
:[Label:] Oh no, run<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Math]]<br />
[[Category:Science]]<br />
[[Category:Programming]]<br />
[[Category:Science tip]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2450:_Post_Vaccine_Social_Scheduling&diff=2999302450: Post Vaccine Social Scheduling2022-11-26T05:04:19Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2450<br />
| date = April 14, 2021<br />
| title = Post Vaccine Social Scheduling<br />
| image = post_vaccine_social_scheduling.png<br />
| titletext = As if these problems weren't NP-hard enough.<br />
}}<br />
<br />
==Explanation==<br />
<br />
This comic is another in a [[:Category:COVID-19|series of comics]] related to the {{w|COVID-19 pandemic}}, specifically regarding the [[:Category:COVID-19 vaccine|COVID-19 vaccine]].<br />
<br />
The comic shows a timeline of a multitude of (presumably) friends and acquaintances getting two doses of the SARS-CoV-2 vaccine. Due to the recommended delay between shots, as well as the few weeks needed to build antibodies after the second shot, planning get-togethers becomes complicated by who is free to meet, or not yet.<br />
<br />
The diagram is some form of Scheduling Diagram, maybe akin to a {{w|Gantt chart}}, which helps to coordinate the status of several individual 'processes' (personal vaccination schedules) and demonstrate where dependent activities (meet-ups) are mutually possible.<br />
<br />
Eventually, everyone can start getting together, but during the time where some people have only received one, neither, or only got the second recently, the scheduling is complicated. The complication is increased by the fact that people who have received one or two doses of vaccine, but haven't gone through the whole waiting period, can be expected to have some protection, but possibly not full protection (as represented by the dashed line). In that case, there's the added question of how important it is that the person is at an event, and how much risk the people involved are willing to tolerate. This may be the reason for the "movie" set, in which all participants will have received both doses, but one will not have completed the final waiting period.<br />
<br />
The title text references NP-hardness, a theme that has come up in past comics. {{w|NP-hardness}} describes a particular level of computational difficulty. Scheduling problems are normally NP-hard. But when extra challenges such as having to deal with whether or not people are vaccinated they become even more difficult.<br />
<br />
In this case though, {{w|Critical Path}} dependencies seem trivial enough. Events (vertical lozenges across the dot-marked timelines of those included) are as trivial to validate as possible for those selected to attend. Fixed events in time can be scanned to show all those allowed to participate at that moment. Movable events can be rescheduled until (enough of) those hoped to be included are 'valid'. Complications may arise for those whose presence relies upon [[2441|the status of others]] potentially attending, or the need to maintain time between two events (in either order) with part-shared attendees as a precautionary 'cool-down' isolation. It is not obvious that either of these issues factor in, any more than basic scheduling conflicts would.<br />
<br />
The third person is scheduled for a movie before being fully vaccinated may be a direct reference to [[2441: IMDb Vaccines]], discussing the number of people that needs to be vaccinated to record a particular scene. Other than each line's identifying portrait (which are not of the Throne Room characters) no explicit age/vulnerability information is given to justify this, presumably the chart's users are aware of the specifics.<br />
<br />
The third person in the table is included in a movie viewing (for which masks could be worn) shortly after their second immunization, but not included in the dinner group until the full benefit of the vaccine takes hold. CDC guidelines permit vaccinated individuals to visit inside a home or private setting without a mask with one household of unvaccinated people who are not at risk for severe illness. Therefore the movie gathering conforms to CDC recommendations provided that the single unvaccinated person is not at increased risk of severe illness and the movie is in a home or private setting.<br />
<br />
The third person in the table appears to have received the second shot twice. This is possibly a reference to [[2422: Vaccine Ordering]]. Another interpretation is that she lied about her first dose being her second dose to be invited to the movie.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[From top to bottom, eleven people are standing on the left side of the image: Danish, Cueball #1, Hairbun, Black Hat, Ponytail, Science Girl, White Hat, Hairy, Blondie, Cueball #2, and Megan, with even-numbered characters standing slightly further to the left. Each character’s first and second doses of the vaccine are labeled ① and ②, respectively. The time before each character’s first dose is drawn with a grey solid line; the time between their first dose and after they are fully vaccinated (two weeks after their second dose) is drawn with a grey dashed line; the time after they are fully vaccinated is drawn with a black solid line. Black Hat, Science Girl, Blondie, Cueball #2, and Megan have all received their first doses before the comic’s time frame. Social activities are drawn with an ellipse around the top and bottom members, and each participating character is identified with a large filled-in circle on their timeline. The ellipses are labeled :]<br />
: DINNER GAMES MOVIE BIRTHDAY DINNER CABIN<br />
<br />
:[The events that happen, in chronological order (from left to right), are:<br />
<br />
* Cueball #1 receives his first dose;<br />
* Blondie receives her second dose;<br />
* Ponytail receives her first dose;<br />
* Hairy receives his first dose;<br />
* White Hat receives his first dose;<br />
* Danish receives her first dose;<br />
* Black Hat receives his second dose;<br />
* Blondie is fully vaccinated;<br />
* Science Girl receives her second dose;<br />
* Cueball #2 receives his second dose;<br />
* Megan receives her second dose;<br />
* Hairbun receives her first dose (erroneously labeled as ②);<br />
* Ponytail receives her second dose;<br />
* Black Hat is fully vaccinated;<br />
* Black Hat and Blondie go to dinner;<br />
* Danish receives her second dose;<br />
* Cueball #1 receives his second dose;<br />
* Science Girl is fully vaccinated;<br />
* Cueball #2 is fully vaccinated;<br />
* Megan is fully vaccinated;<br />
* Hairy receives his second dose;<br />
* White Hat receives his second dose;<br />
* Science Girl, Blondie, Cueball #2, and Megan play games;<br />
* Ponytail is fully vaccinated;<br />
* Hairbun receives her second dose;<br />
* Hairbun, Black Hat, and Ponytail go to the movies or make a movie (the label is just "Movie");<br />
* Danish is fully vaccinated;<br />
* Cueball #1 is fully vaccinated;<br />
* Hairy is fully vaccinated;<br />
* White Hat is fully vaccinated;<br />
* Danish, Cueball #1, Ponytail, White Hat, and Hairy attend a birthday party;<br />
* Hairbun is fully vaccinated;<br />
* Hairbun and Blondie go to dinner;<br />
* Black Hat, Science Girl, White Hat, Hairy, and Cueball #2 go to a cabin.<br />
<br />
:[Caption below the panel:]<br />
:Post-Vaccine Social Scheduling<br />
<br />
{{comic discussion}}<br />
[[Category: COVID-19]]<br />
[[Category: COVID-19 vaccine]]<br />
[[Category: Timelines]]<br />
[[Category: Programming]]<br />
[[Category: Comics featuring Cueball]]<br />
[[Category: Comics featuring Megan]]<br />
[[Category: Comics featuring Hairy]]<br />
[[Category: Comics featuring Ponytail]]<br />
[[Category: Comics featuring Hairbun]]<br />
[[Category: Comics featuring Blondie]]<br />
[[Category: Comics featuring Science Girl]]<br />
[[Category: Comics featuring White Hat]]<br />
[[Category: Comics featuring Danish]]<br />
[[Category: Comics featuring Black Hat]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2690:_Cool_S&diff=2999272690: Cool S2022-11-26T04:59:07Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2690<br />
| date = October 26, 2022<br />
| title = Cool S<br />
| image = cool_s_2x.png<br />
| imagesize = 325x327px<br />
| noexpand = true<br />
| titletext = Although I hear they were caught cheating off of Rosalind, who sat at a desk in front of them.<br />
}}<br />
<br />
==Explanation==<br />
<br />
The '{{w|Cool S}}' is a stylized drawing of the letter "S". It is a popular doodle among teenagers and pre-teens as it can be quickly hashed out using six vertical lines which are then connected with an appropriate pattern of diagonal lines. The drawing has been around for a very long time, and may be independently discovered simply because it is a logical progression of combining a series of straight lines in an interesting manner.<br />
<br />
Randall first draws the steps to make the Cool S. Then he draws a chain of repeats of this pattern, excluding the end caps, making something that looks like a twisted rope. Finally he separates the two strands and adds cross bars, creating something that turns out to have a visual similarity to the discovered helical structure of {{w|DNA}}. However, although the final diagram is a double helix, the chirality, or "handedness", is backwards: an actual DNA molecule usually winds in the opposite direction (clockwise, if you're looking at it end-on). (The tutorial at [http://realerthinks.com/correctly-draw-dna/ How to (correctly) draw DNA] describes this in more detail.) It is possible for left-handed DNA segments, called Z-DNA, to form in purine-pyrimidine alternating regions; but this is much less common than the more typical conformations of B-DNA and A-DNA. (B-DNA is the most common and is elongated with accentuated major grooves: see {{w|Nucleic acid structure}}. This asymmetry can be seen in the spacing between strand segments, which alternates between short and long distances, as opposed to A-DNA and Z-DNA where these distances are much more uniform.)<br />
<br />
He posits that the helical shape of DNA was originally discovered when somebody decided to doodle this extended S pattern. <br />
<br />
Understanding the shape of the DNA molecule was an important step towards understanding how it duplicates itself and serves as a template for RNA. In real life, {{w|Francis Crick}} and {{w|James Watson}} were awarded a Nobel Prize for this discovery.<br />
<br />
The title text is a reference to {{w|Rosalind Franklin}}, who made a material contribution to the discovery of DNA but was [https://web.archive.org/web/20160927113256/http://www.biomath.nyu.edu/index/course/hw_articles/nature4.pdf controversially not included in the Nobel Prize]. Many are quick to assume she was excluded simply due to sexism, although she had also been dead for five years and Nobel Prizes are not awarded posthumously, regardless of the nature of the contribution. Franklin's boss at the time of the discovery, {{w|Maurice Wilkins}}, was also named on the prize. Wilkins had shared some of Franklin's data with Watson, who then shared what he saw with Crick. None of the three men ever told Franklin that Watson and Crick had based their model on her data.<br />
<br />
This account is reminiscent of how {{W|August Kekulé}} said he identified the ring structure of the benzene molecule. He claimed to have had a dream in which the atoms were moving around, with the last grabbing onto the first like the classic image of a snake grabbing its tail, forming a ring of six lines.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
:[10 drawings evolving from simple dashes, to a "cool S" symbol, to a representation of DNA. Unless otherwise stated, each drawing adds to the previous drawing]<br />
:First drawing - three vertical lines side by side over three equally sized vertical lines<br />
:Second drawing - Two diagonal lines added from the bottom of the top left line to the top of the bottom middle line, and the bottom of the top middle line to the top of the bottom right line<br />
:Third drawing - Four diagonal lines added from the top of the top left line and top right line, and the bottom of the bottom right line and bottom left line. The two lines at the top meet above the top middle line, at a 90 degree angle. The two lines at the bottom meet below the bottom middle line, at a 90 degree angle, making an incomplete "Cool S", missing two lines.<br />
:Fourth drawing - Two diagonal lines added. One from top of the bottom left line, pointing towards the bottom of the top middle line; it stops halfway where it intersects with the line between the top of the bottom middle line and the bottom of the top left line drawn in the second drawing. One from bottom of the top right line, pointing towards the top of the bottom middle line; it stops halfway where it intersects with the line between the bottom of the top middle line and the top of the bottom right line drawn in the second drawing. forming a complete "Cool S"<br />
:Fifth drawing - Resets the last few steps and is the same as the second drawing.<br />
:Sixth drawing (located under the first drawing, making a new line of drawings) - The lines from the fifth drawing remain present and untouched, but there are now three vertical lines side by side above and below, with a gap left between them and the previous lines.<br />
:Seventh drawing - The pattern between the middle two sets of three lines established in the second drawing is repeated above and below, such that for each pair of three lines, Two diagonal lines are added from the bottom of the top left line to the top of the bottom middle line, and from the bottom of the top middle line to the top of the bottom right line<br />
:Eighth drawing - The pattern between the middle two sets of three lines established in the fourth drawing is both reimplemented, and repeated in the upper and lower two sets of lines. One from top of the bottom left line, pointing towards the bottom of the top middle line; it stops halfway where it intersects with the line between the top of the bottom middle line and the bottom of the top left line drawn in the second drawing. One from bottom of the top right line, pointing towards the top of the bottom middle line; it stops halfway where it intersects with the line between the bottom of the top middle line and the top of the bottom right line drawn in the second drawing.<br />
:Ninth drawing - <br />
:Tenth drawing - <br />
<br />
:[Caption below the panel]:<br />
:The structure of DNA was originally discovered by a group of especially cool middle school researchers.<br />
<br />
{{comic discussion}}<br />
[[Category:Biology]]<br />
[[Category:Comics featuring real people]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2528:_Flag_Map_Sabotage&diff=2999242528: Flag Map Sabotage2022-11-26T04:56:19Z<p>Beret: /* Explanation */ removed incomplete tag; while a visual aid would certainly be nice, it is not necessary to understanding this comic and does not warrant a tag</p>
<hr />
<div>{{comic<br />
| number = 2528<br />
| date = October 13, 2021<br />
| title = Flag Map Sabotage<br />
| image = flag_map_sabotage.png<br />
| titletext = Delaware hopes to explore the western edge of areas marked with the Belgian flag, once the tornadoes die down.<br />
}}<br />
<br />
==Explanation==<br />
<br />
The comic refers to a type of map that colors countries using the national flag designs; see [https://i.pinimg.com/originals/41/0f/36/410f3661d1cee3b255b82a111f99d242.jpg here] for such a map of Europe. Randall proposes a new flag specifically designed to troll such maps. Most obviously, the flag includes a legend with multiple common flag colors to indicate random regional attributes. Hence, the mere act of placing this flag on a map would cause people to misinterpret this legend as applying to the entire map, giving wildly false information about regions of other countries. This trick is reminiscent of [[327: Exploits of a Mom]], with Mrs. Robert's son <code>Robert'); DROP TABLE Students;--</code>. <br />
<br />
In addition to the legend, the flag consists of two red fields, one of which has an irregular-shaped border, the other of which is a straight line. The irregular shape is similar to a geographical border based on natural features (such as rivers and coastlines), while borders not based on such features tend to be straight lines. Red is the most common color on national flags, so if any bordering country had red on their flag, it would risk bordering these red fields, confusing where the border lay (as well as designating the entire red region as "greater Delaware"). If this flag is intended for the USA (although the text mentions "our new country"), the red regions would be continuous with the red strips on both sides of Canada's flag and the red field on the right of Mexico's flag, disguising the border still further. <br />
<br />
The title text refers to the flag of Belgium, which consists of three vertical stripes in the order (left to right) black, yellow, and red. The western part of Belgium would, according to the legend, be unexplored, while the eastern part would be Greater Delaware. The middle would therefore be a tornado zone separating the unexplored area from Greater Delaware. Depending on how the flags are aligned it might be possible to explore from the south, where the blue-white-red stripes of the French flag contain another piece of Greater Delaware that may be conveniently located to help said exploration. Exploring from the Netherlands (red, white, and blue horizontal stripes) is not viable as rebel forces are positioned between Greater Delaware and the unexplored region. <br />
<br />
This is not the first time Randall has made a flag for a new country! See [[1815: Flag]]<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[A flag displays a white country-shaped area surrounded by a red field. Inside the shape sits a map legend.]<br />
<br />
:[Label of map legend] Map Legend<br />
:[Bright blue rectangle] Disputed territory<br />
:[Green rectangle] Newly independent<br />
:[Blue rectangle] Demilitarized zone<br />
:[Yellow rectangle] Tornado warning<br />
:[Dark blue rectangle] Held by rebel forces<br />
:[Red rectangle] Greater Delaware<br />
:[Black rectangle] Unexplored<br />
<br />
:[Caption below panel]<br />
:Our new country's flag sabotages those maps where geographic areas are colored in with flag patterns.<br />
<br />
<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics with color]]<br />
[[Category:Maps]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2634:_Red_Line_Through_HTTPS&diff=2999222634: Red Line Through HTTPS2022-11-26T04:50:41Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2634<br />
| date = June 17, 2022<br />
| title = Red Line Through HTTPS<br />
| image = red_line_through_https.png<br />
| titletext = Some organization has been paying to keep this up and it hasn't been removed from search results. Seems like two votes of confidence to me.<br />
}}<br />
<br />
==Explanation==<br />
<br />
This comic pokes fun at the lack of security implied by a poor {{w|https}} connection as implied by the "red line through (<span style="color:red"><s>https</s></span>)". The red line is supposed to be a clear warning to the user that the connection is not secure, and that anything about the site, or that you send to the site (like passwords) may be observed or modified in transit by anyone. <br />
<br />
Although a lack of the https protocol in a web process does allow for third party tampering and deception, it also implies that the site is rather old; and, if it has been maintained for this long, it is probably not malicious, as most malicious sites are either reported and taken down or allowed to become defunct by their operators after a short amount of time.<br />
<br />
There are a wide variety of reasons why an HTTPS connection might not be secure. A list of reasons associated with dangerous misconfigurations can be found on [https://badssl.com/ badssl.com].<br />
<br />
The title text essentially explains the joke, noting that maintaining a website costs money and that there are regulatory agencies responsible for taking down sketchy domains, and so if a website is still up despite these obstacles, it is probably trustworthy.<br />
<br />
==Transcript==<br />
:[White Hat is sitting in an office chair at his desk facing his laptop while Cueball is standing behind him looking over his shoulder.]<br />
:White Hat: What does the red line through https mean?<br />
:Cueball: Oh, just that the site hasn't been updated since 2015 or so.<br />
:Cueball: And since it's been around that long it means it's probably legit.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring White Hat]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Computer security]]<br />
[[Category:Internet]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=1245:_10-Day_Forecast&diff=2997881245: 10-Day Forecast2022-11-24T20:25:36Z<p>Beret: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 1245<br />
| date = July 31, 2013<br />
| title = 10-Day Forecast<br />
| image = 10 day forecast.png<br />
| titletext = Oh, definitely not; they don't have Amazon Prime.<br />
}}<br />
<br />
==Explanation==<br />
The 10-day forecast is a prediction of the weather extending 10 days into the future (with the accuracy decreasing exponentially). However, when [[Cueball]] checks the forecast for his local area, it apparently predicts progressively extreme lightning storms, a plague of insects which appear to be locusts, what appears to be {{w|Rapture|The Rapture}}, and the appearance of a demon-like creature. Upon the arrival of the creature (perhaps {{w|The Antichrist}} or {{w|Woden}}) appearing, the forecast falls into static and nothingness with the day stuck on Tuesday, meaning that the world has ended.<br />
<br />
When asked about this, [[Megan]] casually explains that Cueball put a minus (-) sign in front of his ZIP code. A {{w|Zone Improvement Plan|ZIP code}} is a numeric postal code used in the United States, but many more countries use similar systems. As ZIP codes are tied to a geographic location, it is also often used to specify a local region for the purposes of weather reports.<br />
<br />
Many computer systems that let the user write in a number only work with certain numbers (such as positive numbers). Numbers the system is not designed to work with, such as negative numbers, may lead to errors or unpredictable behavior (or, more often, the system will just refuse to proceed until you input a valid number). When this happens with the number of a video game level, it can result in data of another type being loaded, creating a level with a corrupted or physically-impossible landscape; this is sometimes known as a "{{tvtropes|MinusWorld|Minus World}}".<br />
<br />
Megan states that you get this result for any negative zip code. This may be an error deliberately put in by the programmers creating the system, to freak out any people who make a mistake.<br />
<br />
Cueball, on the other hand reacts as if this negative zip code actually represents an actual geographical location, or a real-life Minus World, and that the weather forecaster is indeed showing an accurate forecast for the (corrupted) area. Since Megan stated that the forecast is always like that for these zip code Cueball expresses that he would never move there.<br />
<br />
In the title text, Megan agrees with Cueball's desire not to move to that ZIP code area, the punchline being that her reason isn't to avoid the apocalypse, but to retain access to Amazon Prime, which shows that her priorities are amusingly bizarre. The service Amazon Prime is provided by {{w|Amazon.com|Amazon}}, where the user pays a flat annual fee and in exchange they get access a number of "enhanced" Amazon services, including free two-day shipping, free access to a library of streaming videos, and the ability to borrow books.<br />
<br />
Later, a [[1606: Five-Day Forecast|Five-Day Forecast]] was also made into a comic.<br />
<br />
==Transcript==<br />
:[Cueball sits behind a computer desk when Megan calls to him.]<br />
:Megan (off-panel): Is it going to rain this weekend? I have a thing.<br />
:Cueball: Lemme check.<br />
:<small>*type type*</small><br />
:Cueball: ...Uhh. What?<br />
<br />
:[A caption is written above ten small panels in two rows. In each panel is an indication of the weather. Below each panel a label tells which day it is referring too.]<br />
:'''Your 10-day forecast:'''<br />
:[A yellow sun.] <br />
:Today<br />
:[Two gray clouds in front of the sun.] <br />
:Tomorrow<br />
:[Thunderstorms, with three gray clouds and a single lightning bolt.]<br />
:Friday <br />
:[Extreme thunderstorms with many large gray clouds and seven lightning bolts]<br />
:Saturday <br />
:[A swarm of insects, with one large black one close by and seven others close enough to discern details. The rest of the swarm is grayed out and just shown as small dots behind these other eight insects.]<br />
:Sunday <br />
:[Images of distorted people with very long legs. One Megan, one Cueball and someone in the background.]<br />
:Monday <br />
:[A humanoid figure with two large horns or a winged helmet silhouetted against a bleak red background. The ground beneath the figure is black.]<br />
:Tuesday <br />
:[Grey static]<br />
:Tuesday <br />
:[Black screen]<br />
:Tuesday <br />
:[Black screen]<br />
:Tuesday<br />
<br />
:[Megan has entered the panel and stands behind Cueball looking at his laptop over his shoulder. She points to the screen. Cueball holds his hand to his chest.]<br />
:Megan: ...Oh! You typed a minus sign in the ZIP code. The negative ZIP codes are all like that.<br />
:Cueball: Let's ''never'' move there.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics with color]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Weather]]<br />
[[Category:Comics with lowercase text]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2644:_fMRI_Billboard&diff=2994102644: fMRI Billboard2022-11-19T08:27:06Z<p>Beret: goddammit</p>
<hr />
<div>{{comic<br />
| number = 2644<br />
| date = July 11, 2022<br />
| title = fMRI Billboard<br />
| image = fmri_billboard.png<br />
| titletext = [other side] If the first word of an instruction you're given starts with the same letter as your crush's name, for that step imagine the experimenter is your crush.<br />
}}<br />
<br />
==Explanation==<br />
<br />
{{w|Functional magnetic resonance imaging}}, or fMRI, is a method of imaging brain activity by detecting blood flow changes apparent from magnetic differences between oxygenated and deoxygenated {{w|hemoglobin}}. Scientists use fMRI to try to detect deception and false memories,[https://www.sciencedirect.com/science/article/pii/S0149763419301873] plan brain surgery,[https://www.sciencedirect.com/science/article/pii/S2213158217303133] and understand the relationship between brain structures and cognition,[https://www.sciencedirect.com/science/article/pii/S0149763419300879] among many other investigations. Volunteer research subjects [https://www.clinicaltrials.gov/ participate in such studies] by lying inside large toroidal scanners while conducting tasks with projected images, sounds, and the like.<br />
<br />
This comic shows a billboard erected by a neuroscience department in an attempt at sabotaging a rival department's volunteer subject compliance with their fMRI study instructions, by suggesting behaviors which would likely produce unexpected results, such as recalling a frightening memory after seeing similar stimulus slides, or imagining the lab technician is a romantic interest when reading words that begin with the same letter as their name. This is funny because academic department rivalries do not usually lead to sabotage,{{citation needed}} and in the rare cases when they do, it's usually clandestine instead of so absurdly blatant. The comic also shows neuroscience in terms of the technologies used to study it, and how experiment instructions can influence its development.<br />
<br />
Following such suggestions or even inadvertently remembering them during an fMRI could very well interfere with its results. fMRI experiments are often criticized because they have low {{w|statistical power}} and can easily be confounded by experiment subject error in following instructions, among many other variables. In a famous 2009 study, a dead fish was shown to have apparent evidence of brain activity when scanned with ordinary fMRI techniques.[http://prefrontal.org/files/posters/Bennett-Salmon-2009.pdf] In 2015, discovery of a statistical error invalidated at least 40,000 fMRI studies.[https://www.sciencealert.com/a-bug-in-fmri-software-could-invalidate-decades-of-brain-research-scientists-discover] Subsequently in 2017, many more fMRI results were further discredited due to poor software parameter selection.[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5487467]<br />
<br />
The title text indicates that the sabotaging instructions are printed on both sides of the billboard, suggesting that it might have been erected on the grounds of the targeted rival department. Alternately, the instructions on the other side may be intended to disrupt research at the other institution.<br />
<br />
==Transcript==<br />
:[A large, building-sized billboard rises over what appears to be a college campus. The sign is supported by two sturdy planks disappearing behind one of two long one story buildings lying next to each other. The board is higher than the buildings and almost as long as the one it stands behind. That building seems to have a flat roof where the other has a peaked roof. It could, though, be a matter of perspective, and that both buildings have the same kind of peaked roof. There are several windows visible in both buildings and a door in the middle of the one with the billboard. There is a forest behind the buildings. In front of the main building there is a path with a round area just outside the door. The path goes past the next building, with yet another round area between the buildings. These round areas are where two paths crosses. Megan is standing outside the door, Cueball walks towards the round area between the buildings, Ponytail sits on the grass between the two paths going away from the buildings, she sits near a tree. Closer to the tree and also closer to the buildings another Ponytail like girl is standing together with Hairbun. The sign reads:]<br />
: ⚠ Student fMRI study volunteers ⚠<br />
: Remember, when you're in the scanner, if you see a slide that's similar to one they already showed you, think as hard as you can about your scariest memory.<br />
<br />
:[Caption below panel:] <br />
:A rival neuroscience department keeps trying to sabotage our experiments.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Comics featuring Hairbun]]<br />
[[Category:Science]]<br />
[[Category:Psychology]]<br />
[[Category:Biology]]<br />
[[Category:Scientific research]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2644:_fMRI_Billboard&diff=2994092644: fMRI Billboard2022-11-19T08:26:11Z<p>Beret: /* Explanation */ removed incomplete tag. I think that whoever wrote this tag knew what they wanted, and they should have added it themselves</p>
<hr />
<div>{{comic<br />
| number = 2644<br />
| date = July 11, 2022<br />
| title = fMRI Billboard<br />
| image = fmri_billboard.png<br />
| titletext = [other side] If the first word of an instruction you're given starts with the same letter as your crush's name, for that step imagine the experimenter is your crush.<br />
}}<br />
<br />
<br />
{{w|Functional magnetic resonance imaging}}, or fMRI, is a method of imaging brain activity by detecting blood flow changes apparent from magnetic differences between oxygenated and deoxygenated {{w|hemoglobin}}. Scientists use fMRI to try to detect deception and false memories,[https://www.sciencedirect.com/science/article/pii/S0149763419301873] plan brain surgery,[https://www.sciencedirect.com/science/article/pii/S2213158217303133] and understand the relationship between brain structures and cognition,[https://www.sciencedirect.com/science/article/pii/S0149763419300879] among many other investigations. Volunteer research subjects [https://www.clinicaltrials.gov/ participate in such studies] by lying inside large toroidal scanners while conducting tasks with projected images, sounds, and the like.<br />
<br />
This comic shows a billboard erected by a neuroscience department in an attempt at sabotaging a rival department's volunteer subject compliance with their fMRI study instructions, by suggesting behaviors which would likely produce unexpected results, such as recalling a frightening memory after seeing similar stimulus slides, or imagining the lab technician is a romantic interest when reading words that begin with the same letter as their name. This is funny because academic department rivalries do not usually lead to sabotage,{{citation needed}} and in the rare cases when they do, it's usually clandestine instead of so absurdly blatant. The comic also shows neuroscience in terms of the technologies used to study it, and how experiment instructions can influence its development.<br />
<br />
Following such suggestions or even inadvertently remembering them during an fMRI could very well interfere with its results. fMRI experiments are often criticized because they have low {{w|statistical power}} and can easily be confounded by experiment subject error in following instructions, among many other variables. In a famous 2009 study, a dead fish was shown to have apparent evidence of brain activity when scanned with ordinary fMRI techniques.[http://prefrontal.org/files/posters/Bennett-Salmon-2009.pdf] In 2015, discovery of a statistical error invalidated at least 40,000 fMRI studies.[https://www.sciencealert.com/a-bug-in-fmri-software-could-invalidate-decades-of-brain-research-scientists-discover] Subsequently in 2017, many more fMRI results were further discredited due to poor software parameter selection.[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5487467]<br />
<br />
The title text indicates that the sabotaging instructions are printed on both sides of the billboard, suggesting that it might have been erected on the grounds of the targeted rival department. Alternately, the instructions on the other side may be intended to disrupt research at the other institution.<br />
<br />
==Transcript==<br />
:[A large, building-sized billboard rises over what appears to be a college campus. The sign is supported by two sturdy planks disappearing behind one of two long one story buildings lying next to each other. The board is higher than the buildings and almost as long as the one it stands behind. That building seems to have a flat roof where the other has a peaked roof. It could, though, be a matter of perspective, and that both buildings have the same kind of peaked roof. There are several windows visible in both buildings and a door in the middle of the one with the billboard. There is a forest behind the buildings. In front of the main building there is a path with a round area just outside the door. The path goes past the next building, with yet another round area between the buildings. These round areas are where two paths crosses. Megan is standing outside the door, Cueball walks towards the round area between the buildings, Ponytail sits on the grass between the two paths going away from the buildings, she sits near a tree. Closer to the tree and also closer to the buildings another Ponytail like girl is standing together with Hairbun. The sign reads:]<br />
: ⚠ Student fMRI study volunteers ⚠<br />
: Remember, when you're in the scanner, if you see a slide that's similar to one they already showed you, think as hard as you can about your scariest memory.<br />
<br />
:[Caption below panel:] <br />
:A rival neuroscience department keeps trying to sabotage our experiments.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Comics featuring Hairbun]]<br />
[[Category:Science]]<br />
[[Category:Psychology]]<br />
[[Category:Biology]]<br />
[[Category:Scientific research]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2634:_Red_Line_Through_HTTPS&diff=2994082634: Red Line Through HTTPS2022-11-19T08:22:50Z<p>Beret: /* Explanation */ added incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2634<br />
| date = June 17, 2022<br />
| title = Red Line Through HTTPS<br />
| image = red_line_through_https.png<br />
| titletext = Some organization has been paying to keep this up and it hasn't been removed from search results. Seems like two votes of confidence to me.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete| Needs to be more thoroughly explained, but not TOO thoroughly for the love of god!}}<br />
<br />
This comic pokes fun at the lack of security implied by a poor {{w|https}} connection as implied by the "red line through https". Although a lack of the https protocol in a web process does allow for third party tampering and deception, it also implies that the site is rather old; and, if it has been maintained for this long, it is probably not malicious, as most malicious sites are either reported and taken down or allowed to become defunct by their operators after a short amount of time.<br />
<br />
The title text essentially explains the joke, noting that maintaining a website costs money and that there are regulatory agencies responsible for taking down sketchy domains, and so if a website is still up despite these obstacles, it is probably trustworthy.<br />
<br />
==Transcript==<br />
:[White Hat is sitting in an office chair at his desk facing his laptop while Cueball is standing behind him looking over his shoulder.]<br />
:White Hat: What does the red line through https mean?<br />
:Cueball: Oh, just that the site hasn't been updated since 2015 or so.<br />
:Cueball: And since it's been around that long it means it's probably legit.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring White Hat]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Computer security]]<br />
[[Category:Internet]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2634:_Red_Line_Through_HTTPS&diff=2994072634: Red Line Through HTTPS2022-11-19T08:20:52Z<p>Beret: /* Explanation */ I redid the entire explanation. It was too much. It was very badly written. I'll accept any corrections to errors I have made here, but please do not revert this page to the state I found it in.</p>
<hr />
<div>{{comic<br />
| number = 2634<br />
| date = June 17, 2022<br />
| title = Red Line Through HTTPS<br />
| image = red_line_through_https.png<br />
| titletext = Some organization has been paying to keep this up and it hasn't been removed from search results. Seems like two votes of confidence to me.<br />
}}<br />
<br />
==Explanation==<br />
<br />
This comic pokes fun at the lack of security implied by a poor {{w|https}} connection as implied by the "red line through https". Although a lack of the https protocol in a web process does allow for third party tampering and deception, it also implies that the site is rather old; and, if it has been maintained for this long, it is probably not malicious, as most malicious sites are either reported and taken down or allowed to become defunct by their operators after a short amount of time.<br />
<br />
The title text essentially explains the joke, noting that maintaining a website costs money and that there are regulatory agencies responsible for taking down sketchy domains, and so if a website is still up despite these obstacles, it is probably trustworthy.<br />
<br />
==Transcript==<br />
:[White Hat is sitting in an office chair at his desk facing his laptop while Cueball is standing behind him looking over his shoulder.]<br />
:White Hat: What does the red line through https mean?<br />
:Cueball: Oh, just that the site hasn't been updated since 2015 or so.<br />
:Cueball: And since it's been around that long it means it's probably legit.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring White Hat]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Computer security]]<br />
[[Category:Internet]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2695:_Soil&diff=2987902695: Soil2022-11-16T18:27:05Z<p>Beret: Removed incomplete tag</p>
<hr />
<div>{{comic<br />
| number = 2695<br />
| date = November 7, 2022<br />
| title = Soil<br />
| image = soil_2x.png<br />
| imagesize = 547x217px<br />
| noexpand = true<br />
| titletext = You might want to bring your frost-sensitive plants in from the patio. The high-level aerosols may result in short-term cooling across the entire backyard.<br />
}}<br />
<br />
==Explanation==<br />
<br />
<br />
[[Beret Guy]] seems to be using {{w|volcano}} seeds to grow a tiny volcano to fertilize [[Cueball]]'s garden. In reality, volcanoes are caused by the pressure of {{w|magma}} (underground lava) from below the Earth's crust pushing up through it, not seeds.{{Citation needed}}<br />
<br />
Volcanic soil is [https://www.sciencedirect.com/topics/earth-and-planetary-sciences/volcanic-soil generally fertile] and replenishes depleted elements in the soil, just like commercial fertilizers. However, the process of eruption is destructive to whatever plants are ''presently'' in the garden, as Cueball points out. Beret Guy's announcement in the final panel resembles the voice-over from a nature documentary.<br />
<br />
In the first panel, Beret Guy states that he made these seeds himself, presumably using his proven skill at [[2446: Spike Proteins|exotic bioengineering]]. It is unclear whether his volcano is capable of {{w|Plant propagation|self-propagating}} but, until his 'help' with maintaining the garden, there would probably be no particular risk of volcanic activity.<br />
<br />
The title text alludes to the fact that sulfate {{w|aerosol}}s from volcanic eruptions may cause a [https://www.sciencedirect.com/topics/earth-and-planetary-sciences/volcanic-soil short-term cooling effect] because the aerosols in the atmosphere block out energy from the sun. This expands on the comedy from a small scale volcano by adding small scale volcano effects. Realistically a small supply of aerosols would be blown away and dispersed by wind. Not to mention the fact that, of course, the currently flowing lava is potentially harmful to all plants near the garden anyway.<br />
<br />
==Transcript==<br />
:[Cueball is standing, holding a trowel, in a vague outdoor area. Beret Guy is kneeling, one hand on the ground, as he carefully pours the contents of a small bag into a hole in the ground with the other.]<br />
:Cueball: Thanks for the gardening help!<br />
:Beret Guy: I made these seeds myself!<br />
<br />
:[Beret Guy is now standing next to a small eruption coming from the ground.]<br />
<br />
:[Beret Guy looks down on a knee-high volcano in full eruption. It produces a large plume above and smaller clouds above that, which are mainly drifting away from Beret Guy. Lava flows down from the top of the volcano.]<br />
:Beret Guy: The infusion of nutrient-rich volcanic soil will revitalize your garden.<br />
<br />
:[Beret Guy spread his arms out to the sides as he looks at the now waist-high volcano. The plume is much bigger, more lava is flowing from the top and there are flames on its sides. Cueball speaks from off-panel.]<br />
:Cueball (off-panel): All my plants are on fire.<br />
:Beret Guy: But soon, life will return to these slopes!<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Beret Guy]]<br />
[[Category:Strange powers of Beret Guy]]<br />
[[Category:Volcanoes]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=26:_Fourier&diff=29569326: Fourier2022-09-30T06:23:02Z<p>Beret: /* Explanation */ Resolved "incomplete" tag</p>
<hr />
<div>{{comic<br />
| number = 26<br />
| date = November 2, 2005<br />
| title = Fourier<br />
| image = fourier.jpg<br />
| titletext = That cat has some serious periodic components<br />
}}<br />
<br />
==Explanation==<br />
<br />
<br />
A {{w|Fourier transform}} is a mathematical function transformation often used in physics and engineering.<br />
<br />
The theory is that any line graph can be represented as the sum of a bunch of sine waves of different frequencies and amplitudes. (The most obvious application is in analyzing a sound recording in terms of the different frequencies of sounds used.) So, for any line graph, you can produce another graph of the frequencies and their amplitudes. This can be done by evaluating an integral based on the function, which is referred to as "taking the Fourier transform" of the function. The form of the integral that needs to be taken is actually shown in the third line of the comic [[55: Useless]]. <br />
<br />
Unfortunately, Cueball has applied this "transform" to his cat. Indeed, whatever he has done has literally ''transformed'' his cat into the shape of an amplitude line graph. Although the cat seems to be alive and largely unharmed, it is clearly not in its familiar shape, and it is not clear if this condition is permanent or not. Notably, the fact the cat is still alive relates to an important property of Fourier transformation: the information of the original graph is fully preserved, and can even be reversed to produce the original graph. How a reverse Fourier transformation would apply to a transformed cat has yet to be seen.<br />
<br />
Cueball is, in this particular comic, likely Jon from ''{{w|Garfield}}''. The name of Garfield's vet in the comic is Liz, and a recurring joke in that strip is Jon calling Liz to report various strange ailments befalling Garfield.<br />
<br />
"Periodic components" in the title text refers to the spikes in the graph. Because sine waves repeat themselves as you go along, the presence of large amounts of one particular sine wave in the Fourier transform graph (each spike) shows that the overall result (the initial graph) is likely to have parts that also repeat themselves, like a {{w|periodic function}}. In other words, the cat has repeating parts.<br />
<br />
==Transcript==<br />
:[Cueball talks on phone. A grotesque-looking cat with many sharp vertical points looks on.]<br />
:Cueball: Hi, Dr. Elizabeth? Yeah, uh ... I accidentally took the Fourier transform of my cat...<br />
:Cat: Meow!<br />
<br />
==Trivia==<br />
*This was the 27th comic originally posted to [[LiveJournal]].<br />
**The previous was [[25: Barrel - Part 4]]. <br />
**The next was [[27: Meat Cereals]].<br />
*Original title: "Wednesday's Drawing - Fourier"<br />
*There were no original [[Randall]] quote for this comic.<br />
*This comic was posted on [[xkcd]] when the web site opened on Sunday the 1st of January 2006.<br />
**It was posted along [[:Category:First day on xkcd|with all 41 comics]] posted before that on LiveJournal as well as a few others.<br />
**The latter explaining why the numbers of these 41 LiveJournal comics ranges from 1-44.<br />
*One of the original drawings drawn on [[:Category:Checkered paper|checkered paper]].<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics posted on livejournal| 27]]<br />
[[Category:First day on xkcd]]<br />
[[Category:Checkered paper]]<br />
[[Category:Comics with color]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Math]]<br />
[[Category:Cats]]<br />
[[Category:Comics with lowercase text]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=26:_Fourier&diff=29569126: Fourier2022-09-30T06:20:02Z<p>Beret: /* Explanation */ Added garfield reference</p>
<hr />
<div>{{comic<br />
| number = 26<br />
| date = November 2, 2005<br />
| title = Fourier<br />
| image = fourier.jpg<br />
| titletext = That cat has some serious periodic components<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Missing reverse transform, or commentary on whether it is meaningful to take it. [to my uneducated eye it looks like half of a real-valued graph, but is phase information missing?] Missing guesses as to possible meaning of the name Elizabeth.}}<br />
<br />
A {{w|Fourier transform}} is a mathematical function transformation often used in physics and engineering.<br />
<br />
The theory is that any line graph can be represented as the sum of a bunch of sine waves of different frequencies and amplitudes. (The most obvious application is in analyzing a sound recording in terms of the different frequencies of sounds used.) So, for any line graph, you can produce another graph of the frequencies and their amplitudes. This can be done by evaluating an integral based on the function, which is referred to as "taking the Fourier transform" of the function. The form of the integral that needs to be taken is actually shown in the third line of the comic [[55: Useless]]. <br />
<br />
Unfortunately, Cueball has applied this "transform" to his cat. Indeed, whatever he has done has literally ''transformed'' his cat into the shape of an amplitude line graph. Although the cat seems to be alive and largely unharmed, it is clearly not in its familiar shape, and it is not clear if this condition is permanent or not. Notably, the fact the cat is still alive relates to an important property of Fourier transformation: the information of the original graph is fully preserved, and can even be reversed to produce the original graph. How a reverse Fourier transformation would apply to a transformed cat has yet to be seen.<br />
<br />
Cueball is, in this particular comic, likely Jon from ''{{w|Garfield}}''. The name of Garfield's vet in the comic is Liz, and a recurring joke in that strip is Jon calling Liz to report various strange ailments befalling Garfield.<br />
<br />
"Periodic components" in the title text refers to the spikes in the graph. Because sine waves repeat themselves as you go along, the presence of large amounts of one particular sine wave in the Fourier transform graph (each spike) shows that the overall result (the initial graph) is likely to have parts that also repeat themselves, like a {{w|periodic function}}. In other words, the cat has repeating parts.<br />
<br />
==Transcript==<br />
:[Cueball talks on phone. A grotesque-looking cat with many sharp vertical points looks on.]<br />
:Cueball: Hi, Dr. Elizabeth? Yeah, uh ... I accidentally took the Fourier transform of my cat...<br />
:Cat: Meow!<br />
<br />
==Trivia==<br />
*This was the 27th comic originally posted to [[LiveJournal]].<br />
**The previous was [[25: Barrel - Part 4]]. <br />
**The next was [[27: Meat Cereals]].<br />
*Original title: "Wednesday's Drawing - Fourier"<br />
*There were no original [[Randall]] quote for this comic.<br />
*This comic was posted on [[xkcd]] when the web site opened on Sunday the 1st of January 2006.<br />
**It was posted along [[:Category:First day on xkcd|with all 41 comics]] posted before that on LiveJournal as well as a few others.<br />
**The latter explaining why the numbers of these 41 LiveJournal comics ranges from 1-44.<br />
*One of the original drawings drawn on [[:Category:Checkered paper|checkered paper]].<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics posted on livejournal| 27]]<br />
[[Category:First day on xkcd]]<br />
[[Category:Checkered paper]]<br />
[[Category:Comics with color]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Math]]<br />
[[Category:Cats]]<br />
[[Category:Comics with lowercase text]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2667:_First_Internet_Interaction&diff=2939682667: First Internet Interaction2022-09-02T20:56:43Z<p>Beret: </p>
<hr />
<div>{{comic<br />
| number = 2667<br />
| date = September 2, 2022<br />
| title = First Internet Interaction<br />
| image = first_internet_interaction.png<br />
| titletext = To that stranger on the KOOL Tree House chat room, I gotta hand it to you: You were, ultimately, not wrong.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by BROWN DAY - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
{{comic discussion}}</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=886:_Craigslist_Apartments&diff=292124886: Craigslist Apartments2022-08-06T07:18:24Z<p>Beret: /* Explanation */ Added more detail about house of leaves, and removed the suggestion of the ancient greek labyrinth, as that is clearly not the reference being made here.</p>
<hr />
<div>{{comic<br />
| number = 886<br />
| date = April 15, 2011<br />
| title = Craigslist Apartments<br />
| image = craigslist apartments.png<br />
| titletext = $1600 / 1386153BR 3BATH, MODERN SLIDING DOORS, GUEST ROOMS, GARBAGE DISPOSAL. FREE MANDATORY PARKING (ENFORCED). CONVENIENT TO ALDERAAN.<br />
}}<br />
<br />
==Explanation==<br />
This is a comic about the potential pitfalls in finding an apartment on {{w|Craigslist}}. Just as in Craigslist, some of the posts are re-posted several times. Additionally, lots of posts use lots of tildes, exclamation points or asterisks as above to set their posts apart from others.<br />
<br />
'''BR''' means bedroom, e.g. 3BR means that apartment has 3 bedrooms (common measurement of apartment size).<br />
<br />
*'''$1600 / 2BR <nowiki>~~~</nowiki> Hardwood floors, utilities included. Cats OK, limit one per square foot.'''<br />
:This ad is aimed at people who compulsively keep a number of cats much greater than is appropriate to the living space.<br />
<br />
*'''$1100 / **** GREAT DEAL SQUARE HOUSE DOOR IN FRONT!!! ****'''<br />
:This is the first repetition of an entry that appears multiple times. It is also extremely generic, telling the reader little useful about the house. The square house might be a garage, or just a regular square house. Beside that, most houses have a door in front. There's nothing special about a door. It's possible this refers to an elevator. The different places it appears on the page could be the different floors it stops on.<br />
<br />
*'''$2300 / 3BR !!!!!!!! Elegant apartment permanently lit by strobe light!!!! No floor.'''<br />
:A strobe light is a very bright light that, instead of remaining on, flashes very quickly. It's frequently used in parties. A constant strobe light and the stated lack of a floor would probably make living in the apartment somewhat difficult. It is not clear whether "no floor" means a dirt floor with no foundation or tiling, or whether there is literally some form of pit where a floor would be.<br />
<br />
*'''$980 / 1BR New "hammock"-style dwelling. Water and heat free from same dispenser. Viking landlord.'''<br />
: This is a post to live as an oarsman on a {{w|Viking ship}}. The water and heat presumably both come from the sky, in the form of rain and sunlight.<br />
<br />
*'''$1550 / 2BR (one inside the other). Has running water, in a sense. Free heat in short, intense bursts. Klein stairs.'''<br />
: This is a vague ad for a very unusual apartment. First off, the ad indicates that the two bedrooms are nested. This is an impractical layout, and it is very rare to see this.{{Citation needed}} Possibly this refers to a {{w|tesseract}}, a four-dimensional cube. This conjecture is supported by mention of a Klein Bottle. Running water "in a sense" is both vague and concerning. The note about heat is similar. Short intense blasts of heat are not a comfortable way to heat a room. Depending on how intense the blasts are, they also may be dangerous or deadly. (Alternatively, the house could have a {{w|geyser}} inside, which would explain both the 'free heat in short, intense bursts', along with the 'water that runs in a sense'.) A {{w|Klein bottle}} is a surface which has no difference between "inside" and "outside", similar to a mobius strip but with an extra dimension. It is physically impossible to build a Klein bottle in a three-dimensional space. It isn't certain what Klein stairs are, but they probably aren't very useful. This may be a pun on "clean" stairs.<br />
<br />
*'''$3200 / 1BR W/trimmed carpet and pert fixtures. Previous tenants clean. Call now, want you inside. $120/night (no animals)'''<br />
:This is a disguised "adult services" (sex) posting, with references to trimmed pubic hair, an attractive body, a desire for penetrative sex, and a lack of {{w|Sexually transmitted disease|STD}}s. This is supported by the fact that $120 per night is highly expensive for an apartment but more usual as a sex worker's rate. Craigslist no longer allows posts for this, because prostitution is illegal in most places in the US. This post tries to evade the adult services ban by pretending to be something else. "No animals" would normally be assumed to mean "no pets", but in this context probably refers to STDs (possibly {{w|Pediculosis pubis|crabs}} or {{w|scabies}}) or {{w|bestiality}}.<br />
<br />
*'''$2100 / 3BR on scenic Ash Tree Lane. Builder unknown; house has always existed. Walls shift; center of house may contain minotaur.'''<br />
: This {{w|Minotaur}} house is an ad for the house in the novel ''{{w|House of Leaves}}''. In the novel, a family moves into a house only to discover that its outer dimensions don't match its inner ones; in essence, it's larger on the inside. This soon escalates into rooms that appear and disappear at random, a door in an outer wall that leads into an apparently endless labyrinth, and walls that shift and warp. The novel also contains numerous crossed out references to the Minotaur.<br />
<br />
*'''$600 / 5BR Three floors w/pool, rooftop garden, beautiful glass facade, no catch, 5-min drive to historic Pripyat.'''<br />
:This is an ad for a residence in the {{w|Chernobyl Nuclear Power Plant}}, located near to the town of {{w|Pripyat}}, in northern Ukraine. The NPP is a 3-level structure, and contains a pool for temporary spent nuclear fuel storage. The rooftop now has plants growing on it after years of neglect, and the glass facade references radioactive glassy minerals created by the explosion. Pripyat was founded in 1970 to serve the power plant, so is only 'historic' in the sense that it is associated with the Chernobyl disaster.<br />
<br />
*'''$7100 / 60BR Sleek modern w/extreme running water. Previous tenants may resist entry. Contains all new wiring and is a submarine.'''<br />
:This house is a submarine, as indicated by the advertisement, presumably operated by a navy. The "previous tenants", being members of the armed forces, would undoubtedly resist entry of someone attempting to board their submarine. The sixty bedrooms refers to the crew members' bunks on board the ship, which are in extremely tight quarters and can be very uncomfortable. This may also be a reference to [[496: Secretary: Part 3]], which makes reference to [[Black Hat]] stealing a submarine, presumably for [[405: Journal 3]] - apparently this is him trying to get rid of it.<br />
<br />
*'''$1616 / 3BR + 2Bath, tub full of blood. Closet full of board games which play themselves. Pets OK but won't survive long.'''<br />
: This is an ad for a house in a generic horror movie.<br />
<br />
*'''$1600 / 1386153BR 3bath, modern sliding doors, guest rooms, garbage disposal. Free mandatory parking (enforced). Convenient to Alderaan.'''<br />
:Appearing in the title text, this is a reference to the {{w|Death Star}} in ''Star Wars''. {{w|Alderaan}} is the home planet of {{w|Princess Leia}}, which was obliterated by the Death Star. Mandatory parking references the tractor beams used to drag nearby ships (such as the Millennium Falcon) into the base. The garbage disposal refers to an iconic scene from Star Wars aboard the Death Star, in which the heroes are in danger of being crushed to death inside a trash compactor chamber. It seems somewhat inconvenient that this "apartment" has over a million bedrooms but only three bathrooms. The guest rooms are probably the detention blocks such as [http://starwars.wikia.com/wiki/Detention_Block_AA-23 Detention Block AA-23].<br />
<br />
==Transcript==<br />
:[The comic is a single panel, presented as an apartment search.]<br />
:[Title bar.]<br />
:All apartments<br />
:Search for: [_______] in: All apartments ( ) Title only (*) Entire post Search<br />
:Rent: [Min] [Max] 0+ BR [ ] Cats [ ] Dogs [ ] Has image<br />
:[Date bar.]<br />
:Fri Apr 15<br />
:[Begin the apartment listings.]<br />
:$1600 / 2BR <nowiki>~~~</nowiki> Hardwood floors, utilities included. Cats ok, limit one per square foot.<br />
:$1100 / **** GREAT DEAL SQUARE HOUSE DOOR IN FRONT!!! ****<br />
:$2300 / 3BR !!!!!!!! Elegant apartment permanently lit by strobe light!!!! No floor.<br />
:$1100 / **** GREAT DEAL SQUARE HOUSE DOOR IN FRONT!!! ****<br />
:$980 / 1BR New "hammock"-style dwelling. Water and heat free from same dispenser. Viking landlord.<br />
:$1550 / 2BR (one inside the other). Has running water, in a sense. Free heat in short, intense bursts. Klein stairs.<br />
:$1100 / **** GREAT DEAL SQUARE HOUSE DOOR IN FRONT!!! ****<br />
:$1100 / **** GREAT DEAL SQUARE HOUSE DOOR IN FRONT!!! ****<br />
:$3200 / 1BR W/trimmed carpet and pert fixtures. Previous tenants clean. Call now, want you inside. $120/night (no animals)<br />
:$2100 / 3BR on scenic Ash Tree Lane. Builder unknown; house has always existed. Walls shift; center of house may contain minotaur.<br />
:$1100 / **** GREAT DEAL SQUARE HOUSE DOOR IN FRONT!!! ****<br />
:$600 / 5BR Three floors w/pool, rooftop garden, beautiful glass facade, no catch, 5-min drive to historic Pripyat.<br />
:$7100 / 60BR Sleek modern w/extreme running water. Previous tenants may resist entry. Contains all new wiring and is a submarine.<br />
:$1616 / 3BR + 2Bath, tub full of blood. Closet full of board games which play themselves. Pets ok but won't survive long.<br />
<br />
{{comic discussion}} <br />
[[Category:Comics with color]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2608:_Family_Reunion&diff=2306902608: Family Reunion2022-04-18T20:52:11Z<p>Beret: added explanation</p>
<hr />
<div>{{comic<br />
| number = 2608<br />
| date = April 18, 2022<br />
| title = Family Reunion<br />
| image = family_reunion.png<br />
| titletext = Grandma says that because of differences in primate and feline lifespans, the cat is actually my 17,000,000th cousin 14,000,000 times removed.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by THE GIRL YOU DIDN'T KNOW WAS YOUR RELATIVE (WHOOPS) - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
<br />
Because all humans are descended from a common ancestor, every human is, at some point, related to every other human, albeit distantly. Similarly, all life forms are descended from a common ancestor, and thus ''all'' life forms are distantly related. This makes every interaction with another life-form, technically, a family reunion, if not in the traditional sense.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
{{comic discussion}}</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2586:_Greek_Letters&diff=2275912586: Greek Letters2022-02-26T03:55:11Z<p>Beret: inserted link</p>
<hr />
<div>{{comic<br />
| number = 2586<br />
| date = February 25, 2022<br />
| title = Greek Letters<br />
| image = greek_letters.png<br />
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. Do NOT delete this tag too soon.}}<br />
<br />
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. <br />
This comic gives a (non-)explanation of what they typically mean.<br />
<br />
The letters are:<br />
<br />
* '''π (lower-case pi)''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). This usage of pi commonly applies to equations in introductory geometry classes, which would be considered "simple" by advanced mathematicians. However, pi also shows up seemingly randomly in extremely advanced and complicated equations (that have nothing to do with a circle), as part of the solution to an infinite series or whatnot. (There are also {{w|Pi_(letter)#Lowercase_Pi|several advanced equations}} which use pi to represent variables other than the ratio of the circumference to the diameter.)<br />
<br />
* '''Δ (capital delta)''' — Typically used to refer to a change in quantity.<br />
<br />
* '''δ (lower-case delta)''' — Also typically used to refer to a change in quantity, but unlike the capital delta, this is only for infinitesimal changes and is used in derivative and integration expressions in mathematics hence the text's reference to "a mathematician's fault".<br />
<br />
* '''θ (lower-case theta)''' — Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based on.<br />
<br />
* '''Φ (lower-case phi)''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. <br />
<br />
* '''ϵ (lower-case lunate epsilon)''' — In lunate form, typically used to signify set membership. Given that set theory is a very pure branch of mathematics, the comic suggests it can be ignored. Alternatively, the normal epsilon is typically used to refer to very small quantities which go to zero in the limit. In this interpretation, the comic suggests that because these quantities are very small, they are unimportant, when in reality the study of quantities that go to zero gives rise to limits and calculus.<br />
<br />
* '''υ,ν (lower-case upsilon and lower-case nu)''' —<br />
<br />
* '''μ (lower-case mu)''' — The SI prefix for "micro" = 10<sup>-6</sup>, representing very small quantities: a micrometer (μm) is tens of times smaller than the width of a human hair, a microgram (μg) is one single fine speck of flour, both of which are barely visible with the bare human eye nor feelable through the skin.<br />
<br />
* '''Σ (capital sigma)''' — Typically used as a symbol for summation of a series of numbers.<br />
<br />
* '''Π (capital pi)''' — Typically used as a symbol for multiplication of a series of numbers.<br />
<br />
* '''ζ (lower-case zeta)''' — Frequently used with number theory, in particular the {{w|Riemann zeta function}}, which is a the focus of a famously unsolved problem in highly advanced mathematics.<br />
<br />
* '''β (lower-case beta)''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by subscript, or compacted into matrix notation) would be used. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.<br />
<br />
* '''α (lower-case alpha)''' — Possibly referring to alpha radiation, which certainly could kill someone. Quite likely refers to angular acceleration, or the acceleration of spinning systems, which are capable of killing people in a number of [https://xkcd.com/123/ interesting ways]...<br />
<br />
* '''Ω (capital omega)''' — This symbol has been used for a {{w|Omega_function|variety of mathematical functions}}. Also used for the symbol for {{w|ohms}}, a unit for electrical resistance.<br />
<br />
* '''ω (lower-case omega)''' — Lower-case omega is used for the {{w|Transfinite_number|lowest transfinite ordinal number}}, a specific way of referring to a type of infinity in a mathematically robust way. The line about dying here among the transfinite equations may be in reference to the literally infinite scope of the branch of mathematics.<br />
<br />
* '''σ (lower-case sigma)''' — In statistics, commonly refers to the standard deviation of a distribution. Statistics often attempts to use simplified models to explain real-world phenomena.<br />
<br />
* '''ξ (lower-case xi)''' —<br />
<br />
* '''γ (lower-case gamma)''' — Gamma ray is the most powerful classification of electromagnetic radiation AKA "light", and powerful lights are frequently associated with high-tech, futuristic devices and weapons, hence "space noises". Alternatively, this might be a reference to the Lorentz factor, an important variable in special relativity calculations.<br />
<br />
* '''ρ (lower-case rho)''' — often used to measure density, such as air density that a wing might be travelling through.<br />
<br />
* '''Ξ (capital xi)''' —<br />
<br />
* '''ψ (lower-case psi)''' — Psi looks exactly like a trident. This is hilarious. In quantum mechanics it's used to describe the wave function of a particle, leading to a bad pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, and the supergolden ratio.)<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
:[Header:]<br />
:What Greek letters mean in equations<br />
<br />
:[What follows is a list of Greek letters, with explanations <s>(quote unquote)</s> next to them.]<br />
:π This math is either very simple or impossible.<br />
:Δ Something has changed.<br />
:δ Something has changed and it's a mathematician's fault.<br />
:θ Circles!<br />
:Φ '''''O R B S'''''<br />
:ϵ Not important, don't worry about it.<br />
:υ,ν Is that a V or a U? Or...oh no, it's one of ''those''.<br />
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.<br />
:Σ Thank you for purchasing ''Addition Pro''®!<br />
:Π ...and the ''Multiplication''® expansion pack!<br />
:ζ This math will only lead to more math.<br />
:β There are just too many coefficients.<br />
:α Oh boy, now '''''this''''' is math about something real. This is math that could '''''kill''''' someone.<br />
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.<br />
:ω A lot of work went into these equations and you are going to die here among them.<br />
:σ Some poor soul is trying to apply this math to real life and it's not working.<br />
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.<br />
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''<br />
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.<br />
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.<br />
:ψ You have entered the domain of King Trition, ruler of the waves.<br />
<br />
{{comic discussion}}</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2586:_Greek_Letters&diff=2275902586: Greek Letters2022-02-26T03:51:03Z<p>Beret: </p>
<hr />
<div>{{comic<br />
| number = 2586<br />
| date = February 25, 2022<br />
| title = Greek Letters<br />
| image = greek_letters.png<br />
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. Do NOT delete this tag too soon.}}<br />
<br />
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. <br />
This comic gives a (non-)explanation of what they typically mean.<br />
<br />
The letters are:<br />
<br />
* '''π (lower-case pi)''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). This usage of pi commonly applies to equations in introductory geometry classes, which would be considered "simple" by advanced mathematicians. However, pi also shows up seemingly randomly in extremely advanced and complicated equations (that have nothing to do with a circle), as part of the solution to an infinite series or whatnot. (There are also {{w|Pi_(letter)#Lowercase_Pi|several advanced equations}} which use pi to represent variables other than the ratio of the circumference to the diameter.)<br />
<br />
* '''Δ (capital delta)''' — Typically used to refer to a change in quantity.<br />
<br />
* '''δ (lower-case delta)''' — Also typically used to refer to a change in quantity, but unlike the capital delta, this is only for infinitesimal changes and is used in derivative and integration expressions in mathematics hence the text's reference to "a mathematician's fault".<br />
<br />
* '''θ (lower-case theta)''' — Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based on.<br />
<br />
* '''Φ (lower-case phi)''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. <br />
<br />
* '''ϵ (lower-case lunate epsilon)''' — In lunate form, typically used to signify set membership. Given that set theory is a very pure branch of mathematics, the comic suggests it can be ignored. Alternatively, the normal epsilon is typically used to refer to very small quantities which go to zero in the limit. In this interpretation, the comic suggests that because these quantities are very small, they are unimportant, when in reality the study of quantities that go to zero gives rise to limits and calculus.<br />
<br />
* '''υ,ν (lower-case upsilon and lower-case nu)''' —<br />
<br />
* '''μ (lower-case mu)''' — The SI prefix for "micro" = 10<sup>-6</sup>, representing very small quantities: a micrometer (μm) is tens of times smaller than the width of a human hair, a microgram (μg) is one single fine speck of flour, both of which are barely visible with the bare human eye nor feelable through the skin.<br />
<br />
* '''Σ (capital sigma)''' — Typically used as a symbol for summation of a series of numbers.<br />
<br />
* '''Π (capital pi)''' — Typically used as a symbol for multiplication of a series of numbers.<br />
<br />
* '''ζ (lower-case zeta)''' — Frequently used with number theory, in particular the {{w|Riemann zeta function}}, which is a the focus of a famously unsolved problem in highly advanced mathematics.<br />
<br />
* '''β (lower-case beta)''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by subscript, or compacted into matrix notation) would be used. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.<br />
<br />
* '''α (lower-case alpha)''' — Possibly referring to alpha radiation, which certainly could kill someone. Quite likely refers to angular acceleration, or the acceleration of spinning systems, which are capable of killing people in a number of interesting ways...<br />
<br />
* '''Ω (capital omega)''' — This symbol has been used for a {{w|Omega_function|variety of mathematical functions}}. Also used for the symbol for {{w|ohms}}, a unit for electrical resistance.<br />
<br />
* '''ω (lower-case omega)''' — Lower-case omega is used for the {{w|Transfinite_number|lowest transfinite ordinal number}}, a specific way of referring to a type of infinity in a mathematically robust way. The line about dying here among the transfinite equations may be in reference to the literally infinite scope of the branch of mathematics.<br />
<br />
* '''σ (lower-case sigma)''' — In statistics, commonly refers to the standard deviation of a distribution. Statistics often attempts to use simplified models to explain real-world phenomena.<br />
<br />
* '''ξ (lower-case xi)''' —<br />
<br />
* '''γ (lower-case gamma)''' — Gamma ray is the most powerful classification of electromagnetic radiation AKA "light", and powerful lights are frequently associated with high-tech, futuristic devices and weapons, hence "space noises". Alternatively, this might be a reference to the Lorentz factor, an important variable in special relativity calculations.<br />
<br />
* '''ρ (lower-case rho)''' — often used to measure density, such as air density that a wing might be travelling through.<br />
<br />
* '''Ξ (capital xi)''' —<br />
<br />
* '''ψ (lower-case psi)''' — Psi looks exactly like a trident. This is hilarious. In quantum mechanics it's used to describe the wave function of a particle, leading to a bad pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, and the supergolden ratio.)<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
:[Header:]<br />
:What Greek letters mean in equations<br />
<br />
:[What follows is a list of Greek letters, with explanations <s>(quote unquote)</s> next to them.]<br />
:π This math is either very simple or impossible.<br />
:Δ Something has changed.<br />
:δ Something has changed and it's a mathematician's fault.<br />
:θ Circles!<br />
:Φ '''''O R B S'''''<br />
:ϵ Not important, don't worry about it.<br />
:υ,ν Is that a V or a U? Or...oh no, it's one of ''those''.<br />
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.<br />
:Σ Thank you for purchasing ''Addition Pro''®!<br />
:Π ...and the ''Multiplication''® expansion pack!<br />
:ζ This math will only lead to more math.<br />
:β There are just too many coefficients.<br />
:α Oh boy, now '''''this''''' is math about something real. This is math that could '''''kill''''' someone.<br />
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.<br />
:ω A lot of work went into these equations and you are going to die here among them.<br />
:σ Some poor soul is trying to apply this math to real life and it's not working.<br />
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.<br />
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''<br />
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.<br />
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.<br />
:ψ You have entered the domain of King Trition, ruler of the waves.<br />
<br />
{{comic discussion}}</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2586:_Greek_Letters&diff=2275892586: Greek Letters2022-02-26T03:50:02Z<p>Beret: added some things</p>
<hr />
<div>{{comic<br />
| number = 2586<br />
| date = February 25, 2022<br />
| title = Greek Letters<br />
| image = greek_letters.png<br />
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. Do NOT delete this tag too soon.}}<br />
<br />
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. <br />
This comic gives a (non-)explanation of what they typically mean.<br />
<br />
The letters are:<br />
<br />
* '''π (lower-case pi)''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). This usage of pi commonly applies to equations in introductory geometry classes, which would be considered "simple" by advanced mathematicians. However, pi also shows up seemingly randomly in extremely advanced and complicated equations (that have nothing to do with a circle), as part of the solution to an infinite series or whatnot. (There are also {{w|Pi_(letter)#Lowercase_Pi|several advanced equations}} which use pi to represent variables other than the ratio of the circumference to the diameter.)<br />
<br />
* '''Δ (capital delta)''' — Typically used to refer to a change in quantity.<br />
<br />
* '''δ (lower-case delta)''' — Also typically used to refer to a change in quantity, but unlike the capital delta, this is only for infinitesimal changes and is used in derivative and integration expressions in mathematics hence the text's reference to "a mathematician's fault".<br />
<br />
* '''θ (lower-case theta)''' — Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based on.<br />
<br />
* '''Φ (lower-case phi)''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. <br />
<br />
* '''ϵ (lower-case lunate epsilon)''' — In lunate form, typically used to signify set membership. Given that set theory is a very pure branch of mathematics, the comic suggests it can be ignored. Alternatively, the normal epsilon is typically used to refer to very small quantities which go to zero in the limit. In this interpretation, the comic suggests that because these quantities are very small, they are unimportant, when in reality the study of quantities that go to zero gives rise to limits and calculus.<br />
<br />
* '''υ,ν (lower-case upsilon and lower-case nu)''' —<br />
<br />
* '''μ (lower-case mu)''' — The SI prefix for "micro" = 10<sup>-6</sup>, representing very small quantities: a micrometer (μm) is tens of times smaller than the width of a human hair, a microgram (μg) is one single fine speck of flour, both of which are barely visible with the bare human eye nor feelable through the skin.<br />
<br />
* '''Σ (capital sigma)''' — Typically used as a symbol for summation of a series of numbers.<br />
<br />
* '''Π (capital pi)''' — Typically used as a symbol for multiplication of a series of numbers.<br />
<br />
* '''ζ (lower-case zeta)''' — Frequently used with number theory, in particular the {{w|Riemann zeta function}}, which is a the focus of a famously unsolved problem in highly advanced mathematics.<br />
<br />
* '''β (lower-case beta)''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by subscript, or compacted into matrix notation) would be used. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.<br />
<br />
* '''α (lower-case alpha)''' — Possibly referring to alpha radiation, which certainly could kill someone. Quite likely refers to angular acceleration, or the acceleration of spinning systems, which are capable of killing people in a number of {{https://xkcd.com/123/|interesting ways}}...<br />
<br />
* '''Ω (capital omega)''' — This symbol has been used for a {{w|Omega_function|variety of mathematical functions}}. Also used for the symbol for {{w|ohms}}, a unit for electrical resistance.<br />
<br />
* '''ω (lower-case omega)''' — Lower-case omega is used for the {{w|Transfinite_number|lowest transfinite ordinal number}}, a specific way of referring to a type of infinity in a mathematically robust way. The line about dying here among the transfinite equations may be in reference to the literally infinite scope of the branch of mathematics.<br />
<br />
* '''σ (lower-case sigma)''' — In statistics, commonly refers to the standard deviation of a distribution. Statistics often attempts to use simplified models to explain real-world phenomena.<br />
<br />
* '''ξ (lower-case xi)''' —<br />
<br />
* '''γ (lower-case gamma)''' — Gamma ray is the most powerful classification of electromagnetic radiation AKA "light", and powerful lights are frequently associated with high-tech, futuristic devices and weapons, hence "space noises". Alternatively, this might be a reference to the Lorentz factor, an important variable in special relativity calculations.<br />
<br />
* '''ρ (lower-case rho)''' — often used to measure density, such as air density that a wing might be travelling through.<br />
<br />
* '''Ξ (capital xi)''' —<br />
<br />
* '''ψ (lower-case psi)''' — Psi looks exactly like a trident. This is hilarious. In quantum mechanics it's used to describe the wave function of a particle, leading to a bad pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, and the supergolden ratio.)<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
:[Header:]<br />
:What Greek letters mean in equations<br />
<br />
:[What follows is a list of Greek letters, with explanations <s>(quote unquote)</s> next to them.]<br />
:π This math is either very simple or impossible.<br />
:Δ Something has changed.<br />
:δ Something has changed and it's a mathematician's fault.<br />
:θ Circles!<br />
:Φ '''''O R B S'''''<br />
:ϵ Not important, don't worry about it.<br />
:υ,ν Is that a V or a U? Or...oh no, it's one of ''those''.<br />
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.<br />
:Σ Thank you for purchasing ''Addition Pro''®!<br />
:Π ...and the ''Multiplication''® expansion pack!<br />
:ζ This math will only lead to more math.<br />
:β There are just too many coefficients.<br />
:α Oh boy, now '''''this''''' is math about something real. This is math that could '''''kill''''' someone.<br />
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.<br />
:ω A lot of work went into these equations and you are going to die here among them.<br />
:σ Some poor soul is trying to apply this math to real life and it's not working.<br />
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.<br />
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''<br />
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.<br />
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.<br />
:ψ You have entered the domain of King Trition, ruler of the waves.<br />
<br />
{{comic discussion}}</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2552:_The_Last_Molecule&diff=2223472552: The Last Molecule2021-12-09T21:50:43Z<p>Beret: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 2552<br />
| date = December 8, 2021<br />
| title = The Last Molecule<br />
| image = the_last_molecule.png<br />
| titletext = Biology is really struggling; they're barely at 93% and they keep finding more ants.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a CONFUSED PARTIAL BIOCHEMIST - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
This comic jokingly proposes a situation in which chemists have discovered and catalogued every single possible molecule. Thus they declare they have "completed chemistry."<br />
<br />
In real life the number of ways to arrange atoms into molecules grows combinatorially with the number of atoms in a molecule. Since molecules can be arbitrarily large, the number of possible combinations is much much larger than the number of particles in the observable universe, making the full cataloging of all molecules impossible. Thus, a "final molecule" cannot be reached. In addition, chemistry is the study of the interaction and changing states of atoms and molecules, not simply the cataloging of all specimens of molecule. Even if we did have a list of every molecule, there are a far greater number of ways to continue studying them, so the field would still be nowhere near completed. <br />
<br />
This is reminiscent of biology's focus in previous centuries on simply cataloging the species on Earth.<br />
<br />
Further, the goal of science is not to "complete" a field, but to understand it better and better. No scientific field is considered fully understood. As readers are aware of this, part of the humor comes from the very high percentages given to the different fields. The title text in particular makes fun of Biology lagging behind due to the inherent difficulty of cataloging all species, when there's no way to know how many new ones remain to be found.<br />
<br />
Putting Biology at 93% and Physics at 98% is patently absurd. If biology ''were'' simply a matter of cataloging species, we might be at 10%. As mentioned in the comic, we don't even know how many kinds of ants there are, let alone microscopic organisms. When J.B.S Haldane, founder of the field of population genetics, was asked what could be inferred about the creator from the creation, he reportedly said, "He has an inordinate fondness for beetles". Insects aside, fundamental and important problems such as what genes promote which traits, the nature of cognition, and the mechanism behind several diseases remain complete mysteries. We know less about our own ocean floor than we do about the surface of Mars. Needless to say, Biology is nowhere close to 93% solved. As for Physics, all the elementary particles of the Standard Model of particle physics have been experimentally detected, culminating in the 2012 detection of the {{w|Higgs Boson}}. But questions such as "what is dark matter?", "how do we unify the four fundamental forces?", "how do we make nuclear fusion possible on earth?", "is the speed of light symmetrical?", and "how many dimensions does the universe have?" make it clear that the field still has a long, long way to go.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
:[Ponytail is presenting on a stage. To the top-center of the slide which Ponytail is pointing to, there is a circled "100% complete" under "Chemistry", then to the left is "Biology" which is at "93% complete" and to the right is "Physics" which is at "98% complete". The bottom of the slide shows the [[wikipedia:structural formula|structural formula]] of a molecule which is captioned "The Last One", along with a few smaller captions around it drawn as squiggles.]<br />
<br />
:Ponytail: With the discovery of the last molecule, I'm pleased to announce that chemistry is finally complete.<br />
:Ponytail: Best of luck to our competitors in their race for second place.<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Biology]]<br />
[[Category:Chemistry]]<br />
[[Category:Physics]]</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=Talk:2552:_The_Last_Molecule&diff=222333Talk:2552: The Last Molecule2021-12-09T17:00:59Z<p>Beret: </p>
<hr />
<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
<br />
Unsuccessfully tried to search for a match to the image of the chemical compound. Did find this, which is difficult to use on a cellphone: OSRA: Optical Structure Recognition: https://cactus.nci.nih.gov/cgi-bin/osra/index.cgi [[Special:Contributions/172.70.211.172|172.70.211.172]] 07:43, 9 December 2021 (UTC)<br />
:I've tried to search for SMILES of the molecule, but also got nothing: https://pubchem.ncbi.nlm.nih.gov/#query=C1(C2CC(CCC)C(CC)C2(CCCC))C%3DCC(C(%3DCCC(%3DC)CC)C(C)C)%3DC1 [[Special:Contributions/162.158.222.137|162.158.222.137]]<br />
<br />
I truly don't understand the God part of the current explanation. [[Special:Contributions/172.68.110.121|172.68.110.121]] 07:55, 9 December 2021 (UTC)<br />
:There is an article at [https://www.smithsonianmag.com/smart-news/humans-make-110000th-earths-biomass-180969141/ Smithonian Magazine] that sums it up quite nicely: Of the 550 gigatons of biomass carbon on Earth, animals make up about 2 gigatons, with insects comprising half of that and fish taking up another 0.7 gigatons. Everything else, including mammals, birds, nematodes and mollusks are roughly 0.3 gigatons, with humans weighing in at 0.06 gigatons.<br />
::About half of all known living species on earth are insects. Therefore if there was a god who created all life, it would be reasonable to assume he likes them. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
<br />
Chemistry. I love chemistry :-) There is a concept called "Chemical Space" that I learned about in school. https://en.wikipedia.org/wiki/Chemical_space may help, in short: Chemical space is a huge but finite space of all possible atom arrangements in molecules. [[Special:Contributions/162.158.91.106|162.158.91.106]] 07:59, 9 December 2021 (UTC)<br />
<br />
I've heard the claim, that we know less about our own ocean floor than we do about the surface of Mars several times before. Is there actually a credible source for this and how do we even quantify how much we know about either area? [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
:This essay might shed some light on the question. [[https://www.scientificamerican.com/article/just-how-little-do-we-know-about-the-ocean-floor/ Just How Little Do We Know about the Ocean Floor?]] From a geographical perspective, our maps of the ocean floor are much less detailed than those covering Mars. (5km resolution for ocean floor, 100m resolution for Mars - radar doesn't work underwater). [[Special:Contributions/162.158.107.18|162.158.107.18]] 09:25, 9 December 2021 (UTC)<br />
<br />
The current explanation says that there are an infinite number of chemicals. Is that true? Source? Explanation how that is possible? <br />
Obviously the number of possible molecules is huge, but is it actually a literal, mathematical infinite? Given a finite observable universe, with presumably a finite number of atoms in it. There appear to be a finite number of elements which are stable for any appreciable amount of time and capable of forming molecules.<br />
It seems like there might be practical limitations to the size of a molecule, so that you can't keep making bigger and bigger ones just by adding more atoms/subunits? <br />
If you just keep adding carbon atoms to a diamond will you eventually reach a point where forces such as gravitation become a factor and the molecular bonds fail? I can imagine that long chain molecules light years long might reach point where other forces overwhelm the bond strength? [[Special:Contributions/108.162.246.76|108.162.246.76]] 09:10, 9 December 2021 (UTC)<br />
:For obvious reasons, as long as you limit the number of atoms involved the number of possible "molecules" is - in a mathematical sense - finite. (As there is only a finite number of reasonable stable elements.) But already simple things like polymers can bind millions of atoms in a single molecule. Together with the possible variations intrinsic to such polymers a simple "material" like phenolic resin [[https://en.wikipedia.org/wiki/Phenol_formaldehyde_resin]] is a mixture of more different chemical compounds (in a strict sense) than mankind can ever describe. For all practical application this compexity is not relevant, so no one really cares about.<br />
Additionally there is no clear boundary between typical molecules and other types of condensed matter, like crystals. Same applies to biochemistry. Does chemistry include bio-molecules? If yes, the chemistry guy have to include all the gene sequencing in their to-do list.<br />
<br />
"how fast does light travel in one direction?" is not a good example for incompleteness in physics, because this question was settled by Michelson and Morley in the 19th century (answer: it travels with the speed of light)<br />
: It's not clear to me either what was meant here - seems out of place.<br />
:We know how fast light travels when it goes somewhere and comes back – that's ''c'' – but we don't know how fast it goes when only traveling in one direction. For example, light going at ''c''/2 in one direction and returning instantaneously in the other would still match our observations. We also can't reliably synchronize clocks over a distance because we'd either have to do it with a speed-of-light delay, or separate two clocks and find that relativity changed the timings. Of course, Occam's razor indicates that a consistent speed is more likely, but that's not proof. [[Special:Contributions/172.70.126.87|172.70.126.87]] 12:42, 9 December 2021 (UTC)<br />
:Observing two points (nominal source and nominal destination) from a third point perpendicularly off the mid-point between thoss two points, at an arbitrary distance, you ought to see if there's slowness or instaneity involved (at least make a comparison between bidirectional traversal). This does not remove a response bias in the signal from either end as sent towards the recorder at the observation point, but as the stand-off is increased it makes both observation paths nearer and nearer to parallel and so significantly removes the quantifiable initial 'sideways bias' that may exist.<br />
:I leave it as an excercise to the reader to produce the reasons why this might not practically work to quash all such 'inbuilt universal asymmetry', but it's a good start! [[Special:Contributions/172.70.90.141|172.70.90.141]] 13:21, 9 December 2021 (UTC)<br />
I genuinely don't understand the confusion being proposed here; in practice it's trivial to synchronize a single photon emitter with a single photon detector (such as a PMT) and confirm the speed of light across a single path, with no return trip involved. As far as I know there is know precidence in QM to suspect bidirectional travel could be a special case.<br />
<br />
To quote Randall Munroe in https://what-if.xkcd.com/114/, "The whole universe is matter, as far as we can tell. No one is sure why there is more matter than antimatter, since the laws of physics are pretty symmetrical, and there's no reason to expect there to be more of one than the other. Although when it comes down to it, there's no reason to expect anything at all." Antimatter aside, this shows that the laws of the universe are sometimes asymmetrical. I also like the point that "when it comes down to it, there's no reason to expect anything." Why should we expect the speed of light to be symmetrical? There's no real reason to. [[User:Beret|Beret]] ([[User talk:Beret|talk]]) 14:53, 9 December 2021 (UTC)<br />
:On the contrary, without any such thing as the æther (the fundament through which we would be passing) there is no reason to expect the speed of light (in any given frame of reference) to be asymmetrical. Relativistic frame-dragging and other distortions due to (or resulting in!) accelerative forces will act accordingly, but not change ''c'' itself, in proper calculations, as a function to direction. [[Special:Contributions/172.70.86.12|172.70.86.12]] 16:02, 9 December 2021 (UTC)<br />
<br />
::https://en.wikipedia.org/wiki/One-way_speed_of_light In any case, the point is that there is no reason to expect light speed to be symmetrical, either. Asymmetry in this case is not due to frame dragging, it would be some fundamental feature of photons or the universe. There is currently no experimental way to test this. [[User:Beret|Beret]] ([[User talk:Beret|talk]]) 17:00, 9 December 2021 (UTC)<br />
<br />
<br />
Maybe we can cite one of some famous declarations of physicist saying the physics is almost done [https://nautil.us/blog/the-comforting-certainty-of-unanswered-questions (taken from this site)] :<br />
<br />
:The British scientist William Cecil Dampier recalled his apprenticeship at Cambridge in the 1890s: “It seemed as though the main framework had been put together once for all, and that little remained to be done but to measure physical constants to the increased accuracy represented by another decimal place.” British physicist J. J. Thomson: “All that was left was to alter a decimal or two in some physical constant.” American physicist Albert A. Michelson: “Our future discoveries must be looked for in the sixth place of decimals.”<br />
--[[User:Marceluda|Marceluda]] ([[User talk:Marceluda|talk]]) 15:32, 9 December 2021 (UTC)</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=Talk:2552:_The_Last_Molecule&diff=222332Talk:2552: The Last Molecule2021-12-09T17:00:22Z<p>Beret: </p>
<hr />
<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
<br />
Unsuccessfully tried to search for a match to the image of the chemical compound. Did find this, which is difficult to use on a cellphone: OSRA: Optical Structure Recognition: https://cactus.nci.nih.gov/cgi-bin/osra/index.cgi [[Special:Contributions/172.70.211.172|172.70.211.172]] 07:43, 9 December 2021 (UTC)<br />
:I've tried to search for SMILES of the molecule, but also got nothing: https://pubchem.ncbi.nlm.nih.gov/#query=C1(C2CC(CCC)C(CC)C2(CCCC))C%3DCC(C(%3DCCC(%3DC)CC)C(C)C)%3DC1 [[Special:Contributions/162.158.222.137|162.158.222.137]]<br />
<br />
I truly don't understand the God part of the current explanation. [[Special:Contributions/172.68.110.121|172.68.110.121]] 07:55, 9 December 2021 (UTC)<br />
:There is an article at [https://www.smithsonianmag.com/smart-news/humans-make-110000th-earths-biomass-180969141/ Smithonian Magazine] that sums it up quite nicely: Of the 550 gigatons of biomass carbon on Earth, animals make up about 2 gigatons, with insects comprising half of that and fish taking up another 0.7 gigatons. Everything else, including mammals, birds, nematodes and mollusks are roughly 0.3 gigatons, with humans weighing in at 0.06 gigatons.<br />
::About half of all known living species on earth are insects. Therefore if there was a god who created all life, it would be reasonable to assume he likes them. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
<br />
Chemistry. I love chemistry :-) There is a concept called "Chemical Space" that I learned about in school. https://en.wikipedia.org/wiki/Chemical_space may help, in short: Chemical space is a huge but finite space of all possible atom arrangements in molecules. [[Special:Contributions/162.158.91.106|162.158.91.106]] 07:59, 9 December 2021 (UTC)<br />
<br />
I've heard the claim, that we know less about our own ocean floor than we do about the surface of Mars several times before. Is there actually a credible source for this and how do we even quantify how much we know about either area? [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
:This essay might shed some light on the question. [[https://www.scientificamerican.com/article/just-how-little-do-we-know-about-the-ocean-floor/ Just How Little Do We Know about the Ocean Floor?]] From a geographical perspective, our maps of the ocean floor are much less detailed than those covering Mars. (5km resolution for ocean floor, 100m resolution for Mars - radar doesn't work underwater). [[Special:Contributions/162.158.107.18|162.158.107.18]] 09:25, 9 December 2021 (UTC)<br />
<br />
The current explanation says that there are an infinite number of chemicals. Is that true? Source? Explanation how that is possible? <br />
Obviously the number of possible molecules is huge, but is it actually a literal, mathematical infinite? Given a finite observable universe, with presumably a finite number of atoms in it. There appear to be a finite number of elements which are stable for any appreciable amount of time and capable of forming molecules.<br />
It seems like there might be practical limitations to the size of a molecule, so that you can't keep making bigger and bigger ones just by adding more atoms/subunits? <br />
If you just keep adding carbon atoms to a diamond will you eventually reach a point where forces such as gravitation become a factor and the molecular bonds fail? I can imagine that long chain molecules light years long might reach point where other forces overwhelm the bond strength? [[Special:Contributions/108.162.246.76|108.162.246.76]] 09:10, 9 December 2021 (UTC)<br />
:For obvious reasons, as long as you limit the number of atoms involved the number of possible "molecules" is - in a mathematical sense - finite. (As there is only a finite number of reasonable stable elements.) But already simple things like polymers can bind millions of atoms in a single molecule. Together with the possible variations intrinsic to such polymers a simple "material" like phenolic resin [[https://en.wikipedia.org/wiki/Phenol_formaldehyde_resin]] is a mixture of more different chemical compounds (in a strict sense) than mankind can ever describe. For all practical application this compexity is not relevant, so no one really cares about.<br />
Additionally there is no clear boundary between typical molecules and other types of condensed matter, like crystals. Same applies to biochemistry. Does chemistry include bio-molecules? If yes, the chemistry guy have to include all the gene sequencing in their to-do list.<br />
<br />
"how fast does light travel in one direction?" is not a good example for incompleteness in physics, because this question was settled by Michelson and Morley in the 19th century (answer: it travels with the speed of light)<br />
: It's not clear to me either what was meant here - seems out of place.<br />
:We know how fast light travels when it goes somewhere and comes back – that's ''c'' – but we don't know how fast it goes when only traveling in one direction. For example, light going at ''c''/2 in one direction and returning instantaneously in the other would still match our observations. We also can't reliably synchronize clocks over a distance because we'd either have to do it with a speed-of-light delay, or separate two clocks and find that relativity changed the timings. Of course, Occam's razor indicates that a consistent speed is more likely, but that's not proof. [[Special:Contributions/172.70.126.87|172.70.126.87]] 12:42, 9 December 2021 (UTC)<br />
:Observing two points (nominal source and nominal destination) from a third point perpendicularly off the mid-point between thoss two points, at an arbitrary distance, you ought to see if there's slowness or instaneity involved (at least make a comparison between bidirectional traversal). This does not remove a response bias in the signal from either end as sent towards the recorder at the observation point, but as the stand-off is increased it makes both observation paths nearer and nearer to parallel and so significantly removes the quantifiable initial 'sideways bias' that may exist.<br />
:I leave it as an excercise to the reader to produce the reasons why this might not practically work to quash all such 'inbuilt universal asymmetry', but it's a good start! [[Special:Contributions/172.70.90.141|172.70.90.141]] 13:21, 9 December 2021 (UTC)<br />
I genuinely don't understand the confusion being proposed here; in practice it's trivial to synchronize a single photon emitter with a single photon detector (such as a PMT) and confirm the speed of light across a single path, with no return trip involved. As far as I know there is know precidence in QM to suspect bidirectional travel could be a special case.<br />
<br />
To quote Randall Munroe in https://what-if.xkcd.com/114/, "The whole universe is matter, as far as we can tell. No one is sure why there is more matter than antimatter, since the laws of physics are pretty symmetrical, and there's no reason to expect there to be more of one than the other. Although when it comes down to it, there's no reason to expect anything at all." Antimatter aside, this shows that the laws of the universe are sometimes asymmetrical. I also like the point that "when it comes down to it, there's no reason to expect anything." Why should we expect the speed of light to be symmetrical? There's no real reason to. [[User:Beret|Beret]] ([[User talk:Beret|talk]]) 14:53, 9 December 2021 (UTC)<br />
:On the contrary, without any such thing as the æther (the fundament through which we would be passing) there is no reason to expect the speed of light (in any given frame of reference) to be asymmetrical. Relativistic frame-dragging and other distortions due to (or resulting in!) accelerative forces will act accordingly, but not change ''c'' itself, in proper calculations, as a function to direction. [[Special:Contributions/172.70.86.12|172.70.86.12]] 16:02, 9 December 2021 (UTC)<br />
::https://en.wikipedia.org/wiki/One-way_speed_of_light<br />
In any case, the point is that there is no reason to expect light speed to be symmetrical, either. Asymmetry in this case is not due to frame dragging, it would be some fundamental feature of photons or the universe. There is currently no experimental way to test this.<br />
<br />
<br />
Maybe we can cite one of some famous declarations of physicist saying the physics is almost done [https://nautil.us/blog/the-comforting-certainty-of-unanswered-questions (taken from this site)] :<br />
<br />
:The British scientist William Cecil Dampier recalled his apprenticeship at Cambridge in the 1890s: “It seemed as though the main framework had been put together once for all, and that little remained to be done but to measure physical constants to the increased accuracy represented by another decimal place.” British physicist J. J. Thomson: “All that was left was to alter a decimal or two in some physical constant.” American physicist Albert A. Michelson: “Our future discoveries must be looked for in the sixth place of decimals.”<br />
--[[User:Marceluda|Marceluda]] ([[User talk:Marceluda|talk]]) 15:32, 9 December 2021 (UTC)</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=Talk:2552:_The_Last_Molecule&diff=222318Talk:2552: The Last Molecule2021-12-09T14:54:01Z<p>Beret: </p>
<hr />
<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
<br />
Unsuccessfully tried to search for a match to the image of the chemical compound. Did find this, which is difficult to use on a cellphone: OSRA: Optical Structure Recognition: https://cactus.nci.nih.gov/cgi-bin/osra/index.cgi [[Special:Contributions/172.70.211.172|172.70.211.172]] 07:43, 9 December 2021 (UTC)<br />
:I've tried to search for SMILES of the molecule, but also got nothing: https://pubchem.ncbi.nlm.nih.gov/#query=C1(C2CC(CCC)C(CC)C2(CCCC))C%3DCC(C(%3DCCC(%3DC)CC)C(C)C)%3DC1 [[Special:Contributions/162.158.222.137|162.158.222.137]]<br />
<br />
I truly don't understand the God part of the current explanation. [[Special:Contributions/172.68.110.121|172.68.110.121]] 07:55, 9 December 2021 (UTC)<br />
:There is an article at [https://www.smithsonianmag.com/smart-news/humans-make-110000th-earths-biomass-180969141/ Smithonian Magazine] that sums it up quite nicely: Of the 550 gigatons of biomass carbon on Earth, animals make up about 2 gigatons, with insects comprising half of that and fish taking up another 0.7 gigatons. Everything else, including mammals, birds, nematodes and mollusks are roughly 0.3 gigatons, with humans weighing in at 0.06 gigatons.<br />
::About half of all known living species on earth are insects. Therefore if there was a god who created all life, it would be reasonable to assume he likes them. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
<br />
Chemistry. I love chemistry :-) There is a concept called "Chemical Space" that I learned about in school. https://en.wikipedia.org/wiki/Chemical_space may help, in short: Chemical space is a huge but finite space of all possible atom arrangements in molecules. [[Special:Contributions/162.158.91.106|162.158.91.106]] 07:59, 9 December 2021 (UTC)<br />
<br />
I've heard the claim, that we know less about our own ocean floor than we do about the surface of Mars several times before. Is there actually a credible source for this and how do we even quantify how much we know about either area? [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
:This essay might shed some light on the question. [[https://www.scientificamerican.com/article/just-how-little-do-we-know-about-the-ocean-floor/ Just How Little Do We Know about the Ocean Floor?]] From a geographical perspective, our maps of the ocean floor are much less detailed than those covering Mars. (5km resolution for ocean floor, 100m resolution for Mars - radar doesn't work underwater). [[Special:Contributions/162.158.107.18|162.158.107.18]] 09:25, 9 December 2021 (UTC)<br />
<br />
The current explanation says that there are an infinite number of chemicals. Is that true? Source? Explanation how that is possible? <br />
Obviously the number of possible molecules is huge, but is it actually a literal, mathematical infinite? Given a finite observable universe, with presumably a finite number of atoms in it. There appear to be a finite number of elements which are stable for any appreciable amount of time and capable of forming molecules.<br />
It seems like there might be practical limitations to the size of a molecule, so that you can't keep making bigger and bigger ones just by adding more atoms/subunits? <br />
If you just keep adding carbon atoms to a diamond will you eventually reach a point where forces such as gravitation become a factor and the molecular bonds fail? I can imagine that long chain molecules light years long might reach point where other forces overwhelm the bond strength? [[Special:Contributions/108.162.246.76|108.162.246.76]] 09:10, 9 December 2021 (UTC)<br />
:For obvious reasons, as long as you limit the number of atoms involved the number of possible "molecules" is - in a mathematical sense - finite. (As there is only a finite number of reasonable stable elements.) But already simple things like polymers can bind millions of atoms in a single molecule. Together with the possible variations intrinsic to such polymers a simple "material" like phenolic resin [[https://en.wikipedia.org/wiki/Phenol_formaldehyde_resin]] is a mixture of more different chemical compounds (in a strict sense) than mankind can ever describe. For all practical application this compexity is not relevant, so no one really cares about.<br />
Additionally there is no clear boundary between typical molecules and other types of condensed matter, like crystals. Same applies to biochemistry. Does chemistry include bio-molecules? If yes, the chemistry guy have to include all the gene sequencing in their to-do list.<br />
<br />
"how fast does light travel in one direction?" is not a good example for incompleteness in physics, because this question was settled by Michelson and Morley in the 19th century (answer: it travels with the speed of light)<br />
: It's not clear to me either what was meant here - seems out of place.<br />
:We know how fast light travels when it goes somewhere and comes back – that's ''c'' – but we don't know how fast it goes when only traveling in one direction. For example, light going at ''c''/2 in one direction and returning instantaneously in the other would still match our observations. We also can't reliably synchronize clocks over a distance because we'd either have to do it with a speed-of-light delay, or separate two clocks and find that relativity changed the timings. Of course, Occam's razor indicates that a consistent speed is more likely, but that's not proof. [[Special:Contributions/172.70.126.87|172.70.126.87]] 12:42, 9 December 2021 (UTC)<br />
:Observing two points (nominal source and nominal destination) from a third point perpendicularly off the mid-point between thoss two points, at an arbitrary distance, you ought to see if there's slowness or instaneity involved (at least make a comparison between bidirectional traversal). This does not remove a response bias in the signal from either end as sent towards the recorder at the observation point, but as the stand-off is increased it makes both observation paths nearer and nearer to parallel and so significantly removes the quantifiable initial 'sideways bias' that may exist.<br />
:I leave it as an excercise to the reader to produce the reasons why this might not practically work to quash all such 'inbuilt universal asymmetry', but it's a good start! [[Special:Contributions/172.70.90.141|172.70.90.141]] 13:21, 9 December 2021 (UTC)<br />
I genuinely don't understand the confusion being proposed here; in practice it's trivial to synchronize a single photon emitter with a single photon detector (such as a PMT) and confirm the speed of light across a single path, with no return trip involved. As far as I know there is know precidence in QM to suspect bidirectional travel could be a special case.<br />
<br />
To quote Randall Munroe in https://what-if.xkcd.com/114/, "The whole universe is matter, as far as we can tell. No one is sure why there is more matter than antimatter, since the laws of physics are pretty symmetrical, and there's no reason to expect there to be more of one than the other. Although when it comes down to it, there's no reason to expect anything at all." Antimatter aside, this shows that the laws of the universe are sometimes asymmetrical. I also like the point that "when it comes down to it, there's no reason to expect anything." Why should we expect the speed of light to be symmetrical? There's no real reason to. [[User:Beret|Beret]] ([[User talk:Beret|talk]]) 14:53, 9 December 2021 (UTC)</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=Talk:2552:_The_Last_Molecule&diff=222317Talk:2552: The Last Molecule2021-12-09T14:53:36Z<p>Beret: </p>
<hr />
<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
<br />
Unsuccessfully tried to search for a match to the image of the chemical compound. Did find this, which is difficult to use on a cellphone: OSRA: Optical Structure Recognition: https://cactus.nci.nih.gov/cgi-bin/osra/index.cgi [[Special:Contributions/172.70.211.172|172.70.211.172]] 07:43, 9 December 2021 (UTC)<br />
:I've tried to search for SMILES of the molecule, but also got nothing: https://pubchem.ncbi.nlm.nih.gov/#query=C1(C2CC(CCC)C(CC)C2(CCCC))C%3DCC(C(%3DCCC(%3DC)CC)C(C)C)%3DC1 [[Special:Contributions/162.158.222.137|162.158.222.137]]<br />
<br />
I truly don't understand the God part of the current explanation. [[Special:Contributions/172.68.110.121|172.68.110.121]] 07:55, 9 December 2021 (UTC)<br />
:There is an article at [https://www.smithsonianmag.com/smart-news/humans-make-110000th-earths-biomass-180969141/ Smithonian Magazine] that sums it up quite nicely: Of the 550 gigatons of biomass carbon on Earth, animals make up about 2 gigatons, with insects comprising half of that and fish taking up another 0.7 gigatons. Everything else, including mammals, birds, nematodes and mollusks are roughly 0.3 gigatons, with humans weighing in at 0.06 gigatons.<br />
::About half of all known living species on earth are insects. Therefore if there was a god who created all life, it would be reasonable to assume he likes them. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
<br />
Chemistry. I love chemistry :-) There is a concept called "Chemical Space" that I learned about in school. https://en.wikipedia.org/wiki/Chemical_space may help, in short: Chemical space is a huge but finite space of all possible atom arrangements in molecules. [[Special:Contributions/162.158.91.106|162.158.91.106]] 07:59, 9 December 2021 (UTC)<br />
<br />
I've heard the claim, that we know less about our own ocean floor than we do about the surface of Mars several times before. Is there actually a credible source for this and how do we even quantify how much we know about either area? [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
:This essay might shed some light on the question. [[https://www.scientificamerican.com/article/just-how-little-do-we-know-about-the-ocean-floor/ Just How Little Do We Know about the Ocean Floor?]] From a geographical perspective, our maps of the ocean floor are much less detailed than those covering Mars. (5km resolution for ocean floor, 100m resolution for Mars - radar doesn't work underwater). [[Special:Contributions/162.158.107.18|162.158.107.18]] 09:25, 9 December 2021 (UTC)<br />
<br />
The current explanation says that there are an infinite number of chemicals. Is that true? Source? Explanation how that is possible? <br />
Obviously the number of possible molecules is huge, but is it actually a literal, mathematical infinite? Given a finite observable universe, with presumably a finite number of atoms in it. There appear to be a finite number of elements which are stable for any appreciable amount of time and capable of forming molecules.<br />
It seems like there might be practical limitations to the size of a molecule, so that you can't keep making bigger and bigger ones just by adding more atoms/subunits? <br />
If you just keep adding carbon atoms to a diamond will you eventually reach a point where forces such as gravitation become a factor and the molecular bonds fail? I can imagine that long chain molecules light years long might reach point where other forces overwhelm the bond strength? [[Special:Contributions/108.162.246.76|108.162.246.76]] 09:10, 9 December 2021 (UTC)<br />
:For obvious reasons, as long as you limit the number of atoms involved the number of possible "molecules" is - in a mathematical sense - finite. (As there is only a finite number of reasonable stable elements.) But already simple things like polymers can bind millions of atoms in a single molecule. Together with the possible variations intrinsic to such polymers a simple "material" like phenolic resin [[https://en.wikipedia.org/wiki/Phenol_formaldehyde_resin]] is a mixture of more different chemical compounds (in a strict sense) than mankind can ever describe. For all practical application this compexity is not relevant, so no one really cares about.<br />
Additionally there is no clear boundary between typical molecules and other types of condensed matter, like crystals. Same applies to biochemistry. Does chemistry include bio-molecules? If yes, the chemistry guy have to include all the gene sequencing in their to-do list.<br />
<br />
"how fast does light travel in one direction?" is not a good example for incompleteness in physics, because this question was settled by Michelson and Morley in the 19th century (answer: it travels with the speed of light)<br />
: It's not clear to me either what was meant here - seems out of place.<br />
:We know how fast light travels when it goes somewhere and comes back – that's ''c'' – but we don't know how fast it goes when only traveling in one direction. For example, light going at ''c''/2 in one direction and returning instantaneously in the other would still match our observations. We also can't reliably synchronize clocks over a distance because we'd either have to do it with a speed-of-light delay, or separate two clocks and find that relativity changed the timings. Of course, Occam's razor indicates that a consistent speed is more likely, but that's not proof. [[Special:Contributions/172.70.126.87|172.70.126.87]] 12:42, 9 December 2021 (UTC)<br />
:Observing two points (nominal source and nominal destination) from a third point perpendicularly off the mid-point between thoss two points, at an arbitrary distance, you ought to see if there's slowness or instaneity involved (at least make a comparison between bidirectional traversal). This does not remove a response bias in the signal from either end as sent towards the recorder at the observation point, but as the stand-off is increased it makes both observation paths nearer and nearer to parallel and so significantly removes the quantifiable initial 'sideways bias' that may exist.<br />
:I leave it as an excercise to the reader to produce the reasons why this might not practically work to quash all such 'inbuilt universal asymmetry', but it's a good start! [[Special:Contributions/172.70.90.141|172.70.90.141]] 13:21, 9 December 2021 (UTC)<br />
I genuinely don't understand the confusion being proposed here; in practice it's trivial to synchronize a single photon emitter with a single photon detector (such as a PMT) and confirm the speed of light across a single path, with no return trip involved. As far as I know there is know precidence in QM to suspect bidirectional travel could be a special case.<br />
To quote Randall Munroe in https://what-if.xkcd.com/114/, "The whole universe is matter, as far as we can tell. No one is sure why there is more matter than antimatter, since the laws of physics are pretty symmetrical, and there's no reason to expect there to be more of one than the other. Although when it comes down to it, there's no reason to expect anything at all." Antimatter aside, this shows that the laws of the universe are sometimes asymmetrical. I also like the point that "when it comes down to it, there's no reason to expect anything." Why should we expect the speed of light to be symmetrical? There's no real reason to. [[User:Beret|Beret]] ([[User talk:Beret|talk]]) 14:53, 9 December 2021 (UTC)</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2552:_The_Last_Molecule&diff=2223162552: The Last Molecule2021-12-09T14:46:46Z<p>Beret: I've seen no reason why my explanation was removed, so I added it back.</p>
<hr />
<div>{{comic<br />
| number = 2552<br />
| date = December 8, 2021<br />
| title = The Last Molecule<br />
| image = the_last_molecule.png<br />
| titletext = Biology is really struggling; they're barely at 93% and they keep finding more ants.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a CONFUSED PARTIAL BIOCHEMIST - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
This comic jokingly proposes a situation in which chemists have discovered and catalogued every single possible molecule. Thus they declare they have "completed chemistry."<br />
<br />
In real life the number of ways to arrange atoms into molecules is growing combinatorial with the number of atoms in a molecule. Hence the number of possible combinations approaches rather quickly the number of particles in the observable universe making the full cataloging of all molecules impossible. Thus, a "final molecule" cannot be reached. In addition, chemistry is the study of the interaction and changing states of atoms and molecules, not simply the cataloging of all specimens of molecule. Even if we had a list of every molecule, there are a far greater number of ways to continue studying them, so the field would still be nowhere near completed. To quote the famous chemistry researcher, educator, businessman and philanthropist [https://en.wikipedia.org/wiki/Walter_White_(Breaking_Bad) Walter White], "Chemistry is the study of change".<br />
<br />
This is reminiscent of biology's focus in previous centuries on simply cataloging the species on Earth.<br />
<br />
Further, the goal of science is not to "complete" a field, but to understand it better and better. No scientific field is considered fully understood.<br />
<br />
Putting Biology at 93% and Physics at 98% is patently absurd. As mentioned in the comic, we don't even know how many kinds of ants there are yet. When J.B.S Haldane, founder of the field of population genetics, was asked what could be inferred about the creator from the creation, he reportedly said, "He has an inordinate fondness for beetles". Insects aside, fundamental and important problems such as what genes promote which traits, the nature of cognition, and the mechanism behind several diseases remain complete mysteries. We know less about our own ocean floor than we do about the surface of Mars. Needless to say, Biology is nowhere close to 93% solved. As for Physics, questions such as "what the actual hell is dark matter?" and "how do we unify the four fundamental forces?" and "how do we make nuclear fusion possible on earth?" and "how fast does light travel in one direction?" make it clear that the field still has a long, long way to go.</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=2552:_The_Last_Molecule&diff=2222682552: The Last Molecule2021-12-09T04:53:45Z<p>Beret: /* Explanation */ Added stuff</p>
<hr />
<div>{{comic<br />
| number = 2552<br />
| date = December 8, 2021<br />
| title = The Last Molecule<br />
| image = the_last_molecule.png<br />
| titletext = Biology is really struggling; they're barely at 93% and they keep finding more ants.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a FRUSTRATED BIOLOGIST - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
<br />
There are an infinite number of ways to arrange atoms into molecules, and chemistry is the study of the interaction of subatomic particles, atoms, and molecules, not simply the cataloging of all specimens of molecule.<br />
<br />
This is reminiscent of biology's focus on previous centuries on simply cataloging the species on Earth.<br />
<br />
Further, the goal of science is not to "complete" a field, but to understand it better and better. No scientific field, with the possible exception of optics, is considered fully understood.<br />
<br />
Putting Biology at 93% and Physics at 98% is patently absurd. As mentioned in the comic, we don't even know how many kinds of ants there are yet. When J.B.S Haldane, founder of the field of population genetics, was asked what could be inferred about the creator from the creation, he reportedly said, "He has an inordinate fondness for beetles". Insects aside, fundamental and important problems such as what genes promote which traits, the nature of cognition, and the mechanism behind several diseases remain complete mysteries. We know less about our own ocean floor than we do about the surface of Mars. Needless to say, Biology is nowhere close to 93% solved. As for Physics, questions such as "what the actual hell is dark matter?" and "how do we unify the four fundamental forces?" and "how do we make nuclear fusion possible on earth?" and "how fast does light travel in one direction?" make it clear that the field still has a long, long way to go.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
{{comic discussion}}</div>Berethttps://www.explainxkcd.com/wiki/index.php?title=Talk:1265:_Juicer&diff=221919Talk:1265: Juicer2021-12-03T06:37:25Z<p>Beret: </p>
<hr />
<div>Please delete the explanation that '{{w|ghoti}}' can be pronounced 'fish'. Sorry, I meant that 'Gushers' can be pronounced 'juicers'. [[User:Xhfz|Xhfz]] ([[User talk:Xhfz|talk]]) 12:28, 16 September 2013 (UTC)<br />
:I agree, but maybe we should move it into a trivia section at the bottom. The sentence "There are several possible readings of this comic:" and the headlines should also be removed. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 13:13, 16 September 2013 (UTC)<br />
<br />
::I don't see any merit to the "Jushers" line - it doesn't deal with the "sh" in the word, nor does it really seem to fit the text of the comment. I don't mind the two remaining alternative explanations though. My reading was the first version that the person is juicing the Gushers (the rind being a mocking reference, as indicated, to the candy's gummy shell). While I don't think Randall was going for the second alternative that the person is saying "I juice" which implys drinking the juice, but instead it's just collected. I have no doubt that if this was the intention, Randall would have drawn an insanely large number of bottles to truely demonstrate constant juicing with no drinking, and have Cueball actually present in the frame eating the candy. That said, it's an interesting and plausible alternative that I think is fair to stay. [[User:TheHYPO|TheHYPO]] ([[User talk:TheHYPO|talk]]) 13:47, 16 September 2013 (UTC)<br />
:::The bright red and blue juice in the containers points to the source being gushers. [[Special:Contributions/96.251.85.48|96.251.85.48]] 16:05, 16 September 2013 (UTC)<br />
:Quote main page: "Don't be a jerk. There are a lot of comics that don't have set in stone explanations; feel free to put multiple interpretations in the wiki page for each comic." '''[[User:Davidy22|<u>{{Color|#707|David}}<font color=#070 size=3>y</font></u><font color=#508 size=4>²²</font>]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 03:58, 17 September 2013 (UTC)<br />
:I like it, especially the parts about the frequencies of certain letter/phoneme sequences, but then again I'm a language nerd. [[Special:Contributions/65.94.50.53|65.94.50.53]] 23:10, 17 September 2013 (UTC)<br />
<br />
The heinous Batterwitch has her gnarled claws in everything! [[Special:Contributions/209.122.160.124|209.122.160.124]] 14:45, 16 September 2013 (UTC)<br />
:+1 for the homestuck reference, but let's try to keep it on topic please. --[[Special:Contributions/142.25.33.249|142.25.33.249]] 17:15, 16 September 2013 (UTC)<br />
<br />
<br />
The three bottles are obviously a reflection of the fact that there were more reds than blues in the Gushers candy packs. The final explanation reads a little contrived to anyone who ever ate the candy. The Gushers=Juicers argument makes sense from what I can tell as a multilingual. <br />
[[Special:Contributions/216.201.206.118|216.201.206.118]] 18:41, 16 September 2013 (UTC)<br />
<br />
<br />
Moved from explanation:<br />
;Hard '''g''' / soft '''g'''<!-- someone bolder than me should delete this absurd explanation--><br />
If English is not your native language (which is not the case of [[Randall]]), you could think that "Gushers" /ˈgʌʃərz/ is pronounced as "juicers" /ˈdʒusərz/. I.e., if you know nothing about English spelling you could think that both words are pronounced /ˈdʒuʃərz/.<br />
*A 'g' can signify a soft-g sound (/dʒ/ as in 'gin'). However, natives know that the soft-g sound never appears in the combination "gu".<br />
*A 'u' can signify a {{w|Close_back_rounded_vowel|close back rounded vowel}}, /u/ as in 'flute'. <br />
*The letter 'c' can be pronounced /ʃ/ as in 'ocean' /ˈoʊʃən/. The pronunciation of 'cer' as /ʃər/ is not common, except in dialectical words like "[http://dialect.redlog.net/staticmaps/q_36.html grocery"].<br />
:->My opinion is that we can mention it can sound very similar if spelled by non native English speakers. That's all.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 19:09, 16 September 2013 (UTC)<br />
<br />
Moved from explanation:<br />
;Juicer Juice Drinkers ⊂ Juicer Owners<br />
Many people buy juicers (and exercise equipment) with the notion that the bought items will make them healthier. This comic shows a juicer with three full bottles of juice, indicating that the owner of the juice machine is making healthy juice with the intention of drinking it, but not consuming juice at the rate it is produced. The comic also shows a Fruit Gusher snack, indicating the unhealthy option that the juicer owner just can't stop eating.<br />
:->I have many ideas like this, the plastic bottles could been made of poisonous material, the juicer is broken and the bottles are bought in a supermarket,... Come on, this makes really no sense.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 19:09, 16 September 2013 (UTC)<br />
::I think the juicer is being used to juice the gushers. --[[Special:Contributions/142.25.33.249|142.25.33.249]] 15:02, 17 September 2013 (UTC)<br />
:::I just saw this is in the explanation already. Yeah, this section doesn't make sense and should definitely have been removed. --[[Special:Contributions/142.25.33.249|142.25.33.249]] 15:05, 17 September 2013 (UTC)<br />
:The juice is [http://www.merigoesround.com/blog/wp-content/uploads/2012/09/betty_crocker_gushers.jpg the same color as gushers]. Note the same color on the box and in the bottle. Given how much Randall avoids color, it seems clear the narrator is making gusher juice. Definitely think this explanation should be removed, it seems to miss the joke entirely. [[Special:Contributions/207.168.168.90|207.168.168.90]] 20:52, 17 September 2013 (UTC)<br />
<br />
<br />
The idea given in the Talk area that the skin of an apple is where "most of the vitamins are" is a fallacy and should be corrected. The skin of the apple does contain more antioxidants, and has the fiber of the fruit, but the majority of the vitamins in that fruit are, indeed, in the "meat" of the apple. The title text in this comic is a sarcastic remark about how people tend to argue that the least-appealing part of something has the majority of the "goodness." (After all, it says that it's where "all" the vitamins are.) While partly true in many cases (rice, for example), it is almost never true of fruit regarding the vitamins, which is what the title text is about. (And when you think about it, who eats the rinds of oranges, lemons, mangoes, bananas, kiwis, or coconuts?)[[Special:Contributions/152.119.255.250|152.119.255.250]] 20:39, 17 September 2013 (UTC)<br />
<br />
:Aren't most vitamins antioxidants? The {{w|Antioxidant}} page lists vitamines A, C and E as examples. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 09:14, 18 September 2013 (UTC)<br />
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:: Some vitamins are antioxidants, but it doesn't change the fact that the comic's title text says, "all the vitamins." That is untrue in every fruit and is made more so by the fact that he says "rind," which is a word usually reserved for the thicker, bitter outer shell of fruit like oranges, bananas, etc. [[Special:Contributions/152.119.255.250|152.119.255.250]] 18:34, 18 September 2013 (UTC)<br />
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There is a growing body of evidence that suggests that not only do antioxidants not benefit your health, in suppressing free radicals they may actually shorten your lifespan. A study of mice in which antioxidant production was suppressed in half the population and normal in the other half found that the suppressed group live as long or slightly longer than the other group.<br />
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;Clean up needed<br />
Some articles running into chaos, people looking at an explain like this and just say Tl;dr (Too long, don't read), I don't like this massive adds to the explain section for a really simple comic. Enter statements to the explain section when it does explain the comic. Random people looking at this site are just annoyed, many statements are just individual expresses. not helpful for an explain.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 23:27, 23 September 2013 (UTC)<br />
:I must agree. Gusher is a simple word and the pronunciation is not in doubt. It is also the name of the product, and the correct pronunciation is used in commercials for the product. Nobody who needs to know how to pronounce it would be able to comprehend one percent of the guide provided in the explanation. Just...useless. [[Special:Contributions/108.162.219.58|108.162.219.58]] 21:52, 4 February 2014 (UTC)<br />
::I deleted the section that said that ''Gushers'' and ''juicers'' can both be mispronounced as ''jooshers''. A double mistake made by non-native speakers who haven't studied English doesn't need to be mentioned. [[User:Xhfz|Xhfz]] ([[User talk:Xhfz|talk]]) 22:31, 4 February 2014 (UTC)<br />
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"There is a simple rule: If your thumbnail can reach the flesh of a fruit don't remove the skin." -- I guess you could say it's a... RULE OF THUMB WAHAHAHA [[Special:Contributions/87.189.150.74|87.189.150.74]] 22:33, 5 October 2013 (UTC)<br />
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I think the "if pesticide has been sprayed on it" part should be removed. Pesticides don't reside just on the surface of the fruit; they reside inside it. Ever seen that demonstration where you grow a plant using water dyed with food colouring? The colour gets drawn into the plant along with the water. The same thing happens with pesticide. Note: this doesn't mean you shouldn't wash your fruits; there's a lot of other stuff - like dirt - on the skin. [[User:Diszy|Diszy]] ([[User talk:Diszy|talk]]) 06:26, 26 July 2014 (UTC)</div>Beret