explain xkcd - User contributions [en]

Talk:3027: Exclusion Principle

2024-12-23T21:11:37Z

172.68.23.91: /* Do we need a category for quantum spin? */ reply

It should be noted, that amusingly, since the quantum gravity has yet to be full explained thanks to the fact that gravity affects, and that for all we know, Exclusion Principle may be just as valid, if not more so, to be on the list as Gravity (even though Exclusion Principle should not, generally, be on this list.) {{unsigned|LilithRose|06:48, 21 December 2024}}
: I'm in agreement. "Fundamental Forces" aren't an unalterable fact about the physical universe - they are scientists' best explanation for the unalterable facts about the physical universe until we find a better one. As a result there could be an underlying reason for the exclusion principle being just as fundamental to the universe as electromagnetism - we just don't know it yet. [[User:Kev|Kev]] ([[User talk:Kev|talk]]) 12:39, 22 December 2024 (UTC)
:: Just to be clear, there *is* an underlying reason for the exclusion principle being just as fundamental to the universe as electromagnetism, and physicists know what it is. The only thing is the exclusion principle isn't a fundamental *force*, it's a different kind of fundamental thing.

:: In short, the exclusion principle necessarily arises as a property of certain particles in any system that includes quantum mechanics. If I had to try to give a rough outline of the reason why, I'd say it's something like this:

:: Suppose you construct an equation describing a quantum system with two particles that are in different positions but are otherwise identical. In many standard examples, this equation would look like the sort of wave equation you get in many problems that use the Schrodinger equation, where the square of the equation represents the probability of the two particles being observed in a particular state.

:: Now suppose those particles swap positions. What happens to the equation? Well, since the particles are identical, the observed probabilities must be the same; if there was an observable difference from merely swapping their positions, then the particles wouldn't be identical.

:: However, since the probabilities are the *square* of the equation, that actually leaves two possible solutions for what the equation could be, for exactly the same reason that the square root of 4 has the two possible solutions of 2 and -2. Similarly, the equation of the swapped particles can either be exactly the same as for the unswapped position *or* it could be negated. Which version you get depends on the properties of the particle itself. Particles where the swapped equation stays the same are called bosons. Particles where the swapped equation negates are called fermions.

:: This negation is what causes the exclusion principle (and indeed, the behaviors unique to fermions more generally), because it means certain combinations of fermions will subtract rather than add amplitude to the final wave function, decreasing the probability of those states occurring, and in some cases even fully zeroing out the amplitude, resulting in a zero probability of certain states happening at all.

:: For example, the most familiar case of this effect is how two electrons cannot be in precisely the same state in an atom. To see why that's true, suppose that really did happen. By the logic earlier, swapping those electrons must change the sign of the equation describing them, since this is true of all fermions. However, since the two electrons are in precisely the same state after the swap (note that not even their positions changed, unlike the earlier case discussed), it must also be the case that the resulting equation is exactly the same. The only solution for the conditions y=-x and also y=x is if x=y=0, meaning the probability of this happening is zero.

:: By contrast, that above logic doesn't apply to bosons, because swapping them doesn't need to negate their wave function, so there can be some probability of two or more bosons being in completely identical states, even including identical positions.

:: If you'd like a more detailed or precise explanation, most intro to quantum mecahnics textbooks have a chapter on the exclusion principle. [[User:Gertuviti|Gertuviti]] ([[User talk:Gertuviti|talk]]) 10:39, 23 December 2024 (UTC)

== Polymagnetic topologies as "color" charge, strong vs weak, etc? ==

I'm increasingly under the impression that these forces & principles, are each an expression of complex electromagnetic interactions? I've never quite understood why they're viewed as separate forces, instead of distinct-but-related expressions of a single type of force across complex topologies.

Particularly, I'm unclear why quark\gluon "color" interactions are seen as anything other than topologically-asymmetric fields interlocking; it just looks like the behavior of polymagnet fields, to me. (By the way, I'm glad there's now a common term, "polymagnetic", for the patterned fields that I'm sure many of us assembled while playing with tiny neodymium magnets & wire, as kids! Arranging multiple cores for a smaller, denser field, & observing that the patterns could interlock, felt like major 'Aha!' moments for me, at the time.)

I was so frustrated by my own feeling of "this complex thing I know very little about, really seems to have a very basic underlying principle that's being widely misconstrued", that [https://www.perplexity.ai/search/i-m-increasingly-under-the-imp-Q83bSr8pRXqMf64_VxKMZQ I've petitioned a mindless bot to hear my case.] (You'd have to scroll at least about halfway down, to get to any prompts even slightly interesting.) I'm probably wasting ''everyone's'' time with this, but it has been bothering me, more & more for ''decades,'' & my reading so far hasn't lessened that.

Why is everyone so insistent that these 'other' forces aren't magnetism? Seems like quite literally ''everything'' is magnetism, to me. Besides a formal education in the matter, what the heck am I missing, here?

[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 15:38, 21 December 2024 (UTC)

:I don't know what you mean by "complex topologies." Which topology? The reason we know the strong and weak interactions are not the electromagnetic interaction is that they have completely different gauge symmetries, among other reasons. The electromagnetic interaction has local symmetry group U(1), and the strong interaction has SU(3). Behaviorally-speaking, they are completely different in almost every respect, affecting different sets of particles, having different strengths, having different potentials, different ranges, carried by different fields, etc. Just as an example, an electron doesn't interact via the strong force ''at all.''

:It is likely that at extremely high energies, the electromagnetic, weak, and strong interactions are all unified. A theory describing this hypothetical union is called a grand unified theory or GUT, and detecting this experimentally is a major objective of modern physics. The unified "electroweak" interaction has already been observed at lower energies. But that doesn't mean the weak interaction is "just magnetism" or that electromagnetism is "just weak." They are both a consequence of a broken symmetry. The fully symmetric grand unified field would not resemble any one of the interactions that we see at lower energies but would be a symmetric combination of all of them. [[User:EebstertheGreat|EebstertheGreat]] ([[User talk:EebstertheGreat|talk]]) 16:38, 21 December 2024 (UTC)

: I absolutely won't claim any kind of knowledge, but Richard Behiel's video series on quantum mechanics, culminating in his 3-hour video on electromagnetism as a gauge theory is INCREDIBLE and absolutely explained a lot to me[[Special:Contributions/172.71.191.51|172.71.191.51]] 23:24, 22 December 2024 (UTC)Bumpf

== Actually explaining the Pauli Principle ==

:"Electrons don't like to be in the same 'spot'" is plain wrong. "Same quantum number set" is the buzzword - remember, two electrons fit in the s orbital, one spin up, one spin down. "Spin-statistics theorem" is a good place to start to ponder about the why. [[Special:Contributions/162.158.95.145|162.158.95.145]] 09:40, 22 December 2024 (UTC)
:: Way too complicated, please change the universe so that "same spot" is good enough [[User:Kev|Kev]] ([[User talk:Kev|talk]]) 12:35, 22 December 2024 (UTC)

== Do we need a category for quantum spin? ==
I'm seeing well over a dozen comics closely involved with spin in search. [[Special:Contributions/172.69.33.237|172.69.33.237]] 20:18, 23 December 2024 (UTC)
:Can there be more than one article in any given quantum spin category? [[Special:Contributions/162.158.74.24|162.158.74.24]] 20:38, 23 December 2024 (UTC)
::Only if they're on different wiki pages. [[Special:Contributions/172.70.211.83|172.70.211.83]] 21:06, 23 December 2024 (UTC)
:Probably. I sometimes wonder if Randall is riffing off of how bad Wikipedia's article on {{w|Spin (physics)}} is. For a good time, see https://en.wikipedia.org/wiki/Spin_(physics)#Higher_spins [[Special:Contributions/172.68.23.91|172.68.23.91]] 21:11, 23 December 2024 (UTC)

3021: Seismologists

2024-12-06T20:01:16Z

172.68.23.91: adding a simple Transscript

{{comic
| number = 3021
| date = December 6, 2024
| title = Seismologists
| image = seismologists_2x.png
| imagesize = 327x270px
| noexpand = true
| titletext = And even when they're not distracted, they usually get kicked out for illegal under-the-net 'subduction spikes'.
}}

==Explanation==
{{incomplete|Created by a ROGUE SEISMOLOGIST - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
[In this comic, [[Megan]], [[Ponytail]] and [[Hairy]] are playing beach volleyball.]
Ponytail: Ooh, a strike-slip fault!
[underneath the comic it says "Why seismologists are bad at beach volleyball".

{{comic discussion}}

Talk:3020: Infinite Armada Chess

2024-12-05T05:48:59Z

172.68.23.91:

== Did I do well? ==

Added a very very basic explanation.
[[Special:Contributions/172.68.147.132|172.68.147.132]] 04:25, 5 December 2024 (UTC)

Well, yes but I wonder if just one tiny fix is needed. If you replace the white side with a simplyfied artillery tower, you reinvented space invaders.

I was personally hoping for an explanation of the Infinite Armada thing, and I feel like a link to the TV Tropes page doesn't really. Explain that at all. So I would love a bit of an expansion on that part! Just want to be sure I didn't miss some reference or something. [[Special:Contributions/172.68.23.91|172.68.23.91]] 05:48, 5 December 2024 (UTC)

== Out of bounds error ==

I think that since the error was "out of bounds", not "out of memory", it's referring to indexing outside of the region of memory that the program allocated to deal with the board. This would happen since instead of addressing rank 1..8, you could address rank 9, 10, 0, or -1. Unless bounds checking is performed when converting the board coordinates into linear array indices, you'd get an out-of-bounds error (or worse, succeed in reading or modifying memory that you weren't intending to). --[[Special:Contributions/172.71.30.253|172.71.30.253]] 05:45, 5 December 2024 (UTC)

Talk:3014: Arizona Chess

2024-11-20T20:34:06Z

172.68.23.91:

I added a basic explanation, how did I do? [[Special:Contributions/172.70.115.129|172.70.115.129]] 14:56, 20 November 2024 (UTC)
:''pat pat'' Good job. [[User:Fephisto|Fephisto]] ([[User talk:Fephisto|talk]]) 15:28, 20 November 2024 (UTC)
I guess chess timers work based on the IERS. [[Special:Contributions/172.71.223.126|172.71.223.126]] 15:32, 20 November 2024 (UTC)
: See "{{w|Chess_clock|chess clocks}} don't work that way" comment, below. If they did, they would almost certainly reference {{w|Coordinated_Universal_Time|Zulu time}}, which doesn't recognize daylight saving or other local time adjustments. This would go badly for Cueball. Moreover, White Hat could be forgiven for thinking that he had won the game when the clock went "beep" in the third panel, because beeping/flag falling in a chess clock <em>should</em> signal end of match because Cueball's time had run out (the fourth panel asserts that Cueball's time did not, in fact, expire). A minor additional irregularity in what is already a seriously contrived situation. [[Special:Contributions/172.68.23.91|172.68.23.91]] 20:34, 20 November 2024 (UTC)

If white hat had conserved 20 seconds through the course of the game, they would have won. Cueball must have been sweating if they were relying on this strategy. [[User:Radialsymmetry|Radialsymmetry]] ([[User talk:Radialsymmetry|talk]]) 15:35, 20 November 2024 (UTC)

Here's one building that might qualify (it appears to be a shed or outbuilding belonging to a house in Mesquite, Nevada): https://www.google.com/maps/@36.808703609641505,-114.05009436731552,55m

I believe that's the only one that straddles the Arizona border with a Pacific Time Zone state (California and Nevada), so (head-)canonically, that's where the comic is set.

No, chess clocks don't work that way. They are simple timers that do not refer to actual time of day in any way, any more than a stopwatch does. Randall just made it work that way for the sake of the joke.

==North America vs. Europe==
One difference between the way parts of North America change time and the way parts of Europe do is that the various North American time zones fall back/jump forward at 2AM local time, while European time zones all change at the same instant (01:00 UTC/WET (02:00 CET, 03:00 EET). That means that the same "trick" could work by sitting on the line between any American time zones at the changeover, but not by sitting on the European lines. [[Special:Contributions/172.70.47.138|172.70.47.138]] 15:37, 20 November 2024 (UTC)

Should the comment about Hawaii be kept? It seems irrelevant. [[Special:Contributions/172.70.111.129|172.70.111.129]] 15:42, 20 November 2024 (UTC)
:removed [[user talk:lettherebedarklight|youtu.be/miLcaqq2Zpk]] 16:15, 20 November 2024 (UTC)

== Which songs would go well with this scene? ==

His World comes to mind... [[User:CalibansCreations|'''<span style="color:#ff0000;">Caliban</span>''']] ([[User talk:CalibansCreations|talk]]) 17:13, 20 November 2024 (UTC)

3011: Europa Clipper

2024-11-14T20:05:00Z

172.68.23.91: /* Explanation */ not a precise measurement

{{comic
| number = 3011
| date = November 13, 2024
| title = Europa Clipper
| image = europa_clipper_2x.png
| imagesize = 333x356px
| noexpand = true
| titletext = They had BETTER make this a sample return mission.
}}

==Explanation==

{{incomplete|Created by a JOVIAN DESSERT. Please consider deleting this tag too soon, but refrain from doing so.}}

[[File:Animation of Europa Clipper trajectory around Jupiter.gif|thumb|right|The ''Europa Clipper's'' projected course around {{w|Jupiter}}, represented as the stationary <span style="color:green;">green</span> dot. In <span style="color:gold;">gold</span> is Jupiter's moon {{w|Callisto (moon)|Callisto}}, in <span style="color:cyan;">cyan</span> is the moon {{w|Europa (moon)|Europa}} — the primary target of the spacecraft's study — and in <span style="color:#FF4500;">orange-red</span> is the innermost of Jupiter's four {{w|Galilean moons|"Galilean"}} moons, {{w|Io (moon)|Io}}. The spacecraft's track is shown in <span style="color:magenta;">magenta</span>. Jupiter's largest moon {{w|Ganymede (moon)|Ganymede}} is not shown, but its gravitational pull affects the ''Clipper's'' trajectory. A mission goal is to achieve a 6:1 {{w|orbital resonance}} with Europa [https://www.researchgate.net/profile/Martin-Ozimek/publication/383115312_AAS_24-433_Europa_Clipper_Mission_Analysis_Pump_Down_Trajectory_Design/links/66bcd845311cbb094938dbd6/AAS-24-433-Europa-Clipper-Mission-Analysis-Pump-Down-Trajectory-Design.pdf by September 2034]. ]]

The ''{{w|Europa Clipper}}'' space probe was launched from the {{w|Kennedy Space Center}} in Florida on [https://europa.nasa.gov/mission/about/ October 14, 2024]. It is expected to arrive at Jupiter and begin exploration of Jupiter's moons, particularly {{w|Europa (moon)|Europa}}, in April of 2030.

Europa is an icy moon. Water ice covers its surface. Around 15 to 25 kilometers (10 to 15 miles) beneath the ice, there is expected to be liquid water which may contain some [https://europa.nasa.gov/why-europa/ingredients-for-life/ basic forms of life]. To sample this liquid, its icy crust would need to be breached. The thickness of the ice dwarfs the ''Europa Clipper's'' 31 meter span.

Europa's surface of ice over liquid water can be compared to the caramelized crust on the popular dessert {{w|crème brûlée}}, perhaps because the {{w|Cassini-Huygens}} probe, after landing on Saturn's moon Titan in January of 2005, found that its surface had what was described as [https://www.sciencenews.org/article/world-unveiled-cr%C3%A8me-br%C3%BBl%C3%A9e-titan a "crème brûlée" consistency]. The hard surface of the caramel cream dessert is traditionally cracked open with a spoon, and so [[Randall]] posits that such equipment will be deployed by the ''Europa Clipper''.

In truth, no such spoon is present on the probe, and Europa's icy crust is too thick to be penetrated by a spoon of such size. Advanced measures are needed to prevent contamination of liquid water by Earth's organisms such as {{w|tardigrade}}s, {{w|deinococcus radiodurans}}, or {{w|bacillus subtilis}}. The ''Europa Clipper's'' course has been charted to avoid any contact with the surface of Europa (although it will fly through sparse material it ejects into space) so as to prevent {{w|Planetary protection|contamination by microorganisms from Earth}}. The successful deployment of any spacecraft's instrument is considered a cause for celebration because deployable spacecraft instruments often fail to correctly extend, unfurl or undock. The ''Clipper'' has a magnetometer that will be used at the end of a 8.5 meter boom (not apparent in the comic which, spoon extension aside, is an otherwise fairly accurate depiction) as part of its study of the moons' environment.

<div style="display: flex; justify-content: center; align-items: center; margin: 1em 0;">
<div style="text-align: center; margin: 0 1em;">
[[File:Europa_-_Perijove_45_(cropped).png|200px|alt=Europa]]
<div>Europa</div>
</div>
<div style="text-align: center; margin: 0 1em;">
[[File:2014_0531_Crème_brûlée_Doi_Mae_Salong_(cropped).jpg|200px|alt=Crème brûlée]]
<div>Crème brûlée</div>
</div>
<div style="text-align: center; margin: 0 1em;">
[[File:Europa_Clipper_spacecraft_model.png|200px|alt=The Europa Clipper spacecraft]]
<div>The ''Europa Clipper'' spacecraft</div>
</div>
</div>

The title text expands on the joke by stating that the spacecraft "had BETTER" return samples of Europa to Earth. However, the ''Europa Clipper'' is not a {{w|sample-return mission}}.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[A space probe with two rectangular solar panels, a circular dish of the front, and a very large spoon extending beneath, longer than the span of both solar panels]

:[Below the panel:]
:Good news: NASA's '''''Europa Clipper''''' is en route to Europa and has successfully deployed its crème brûlée spoon.

==Trivia==
Initially, the ''Europa Clipper'' mission was planned to include a lander component, but it was removed from the project early on. The Europa Lander proposal lags significantly behind the Clipper in development and has not secured funding. An actual sample return mission is currently far into the future of {{w|Ocean Worlds Exploration Program|the pertinent plans for exploration}}.

In Arthur C Clarke's novel '''2010''', the monolith aliens tell humanity ''"All these worlds are yours - except Europa. Attempt no landing there."'' Contrary to the suggestion of the comic, no landing or any other physical interaction beyond observation of the surface of Europa is planned.

In {{w|Greek mythology}}, {{w|Europa (consort of Zeus)|Europa}} was said to be a {{w|Phoenician}} princess who {{w|Zeus}}, the king of the gods, abducted after transforming himself into a bull. The name of the continent Europe derives from a northern province and/or river of ancient Greece that may have been associated with this legend. Although, as with {{w|Asia#Etymology|Asia}}, the region/continent name may have instead been derived from one of the {{w|Europa (Greek myth)|totally different Europas}}, namely a member of the many {{w|Oceanids}} (daughters of a pair of water-themed Titans that legendarily predate Zeus's times). Jupiter's moon was thematically {{w|Europa (consort of Zeus)#Moon of Jupiter|named after the princess}} in relatively recent times, much as the {{w|Tethys (mythology)|Oceanid Europa's mother}} features in a differently themed naming of Saturnian moons. With the caramel cream dessert believed to have been [https://archive.org/details/lagastronomieaug00sabb/page/272/mode/2up invented in Europe], there is an extremely vague and contrived possibility that mythology, rather than any more mundane cullinary analogy, could have inspired [[Randall]] to start down the path of eventually suggesting that the spacecraft may encounter crème brûlée and require a spoon.

{{comic discussion}}
[[Category:Space]]
[[Category:Space probes]]
[[Category:Food]]

3011: Europa Clipper

2024-11-14T15:17:22Z

172.68.23.91: (ec) restore explanation

{{comic
| number = 3011
| date = November 13, 2024
| title = Europa Clipper
| image = europa_clipper_2x.png
| imagesize = 333x356px
| noexpand = true
| titletext = They had BETTER make this a sample return mission.
}}

==Explanation==

{{incomplete|Created by a JOVIAN DESSERT. Please consider deleting this tag too soon, but refrain from doing so.}}

[[File:Animation of Europa Clipper trajectory around Jupiter.gif|thumb|right|The ''Europa Clipper's'' projected course around {{w|Jupiter}}, represented as the stationary <span style="color:green;">green</span> dot. In <span style="color:gold;">gold</span> is Jupiter's moon {{w|Callisto (moon)|Callisto}}, in <span style="color:cyan;">cyan</span> is the moon {{w|Europa (moon)|Europa}} — the primary target of the spacecraft's study — and in <span style="color:#FF4500;">orange-red</span> is the innermost of Jupiter's four {{w|Galilean moons|"Galilean"}} moons, {{w|Io (moon)|Io}}. The spacecraft's track is shown in <span style="color:magenta;">magenta</span>. Jupiter's largest moon {{w|Ganymede (moon)|Ganymede}} and its second largest moon {{w|Titan (moon)|Titan}} are not shown, but their gravitational pull affects the ''Clipper's'' trajectory. A mission goal is to achieve a 6:1 {{w|orbital resonance}} with Europa by September 2034.[https://www.researchgate.net/profile/Martin-Ozimek/publication/383115312_AAS_24-433_Europa_Clipper_Mission_Analysis_Pump_Down_Trajectory_Design/links/66bcd845311cbb094938dbd6/AAS-24-433-Europa-Clipper-Mission-Analysis-Pump-Down-Trajectory-Design.pdf] ]]

The ''{{w|Europa Clipper}}'' space probe was launched from the {{w|Kennedy Space Center}} in Florida on October 14, 2024. It is expected to arrive at Jupiter and begin exploration of Jupiter's moons, particularly {{w|Europa (moon)|Europa}}, in April of 2030.

Europa is an icy moon. Water ice covers its surface. Beneath the ice, there is expected to be liquid water, which might contain living microbes.[https://europa.nasa.gov/why-europa/ingredients-for-life/] To sample this liquid, its crust (water ice) would need to be broken.

Europa's icy surface may be compared to the caramelized crust on the popular dessert {{w|crème brûlée}}, which is traditionally cracked with a spoon before eating. The carmel cream dessert is believed to have been [https://archive.org/details/lagastronomieaug00sabb/page/272/mode/2up invented in Europe], after which the moon and the space probe were named. In {{w|Greek mythology}}, Europa was a {{w|Phoenician}} princess who {{w|Zeus}}, the king of the gods, abducted after transforming himself into a bull. The continent Europe was named after Europa. Thus [[Randall]] suggests the spacecraft might encounter crème brûlée, and has therefore been equipped with a spoon for the purpose of collecting samples, as spoons are the traditional {{w|tableware}} provided for eating such desserts. Perhaps because the {{w|Cassini-Huygens}} probe, after landing on the surface of Saturn's moon Titan in January of 2005, found that its surface had what was described as [https://www.sciencenews.org/article/world-unveiled-cr%C3%A8me-br%C3%BBl%C3%A9e-titan a "crème brûlée" consistency].

No such spoon is present on the ''Europa Clipper.''{{cn}} Its course is designed to avoid contact with Europa so as to prevent {{w|Planetary protection|contamination by microorganisms from Earth}}. The spacecraft is, however, equipped with a magnetometer at the end of a 8.5 meter deployable boom. Deployable instruments on spacecraft have often failed to deploy correctly, so the successful deployment of any instrument is considered a cause for celebration.

The title text expands on the joke by stating that the spacecraft "had BETTER" return samples of Europa to Earth. However, the ''Europa Clipper'' is not a {{w|sample-return mission}}.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[A space probe with two rectangular solar panels, a circular dish of the front, and a very large spoon extending beneath, longer than the span of both solar panels]

:[Below the panel:]
:Good news: NASA's '''''Europa Clipper''''' is en route to Europa and has successfully deployed its crème brûlée spoon.

==Trivia==
The Clipper spacecraft was at one point to be developed alongside a lander, which was later dropped from being part of the same (or very closely partnered) mission. The latest version of the {{w|Europa Lander}} proposal is far behind the Clipper in implementation, not yet even being guaranteed funding.

Any actual sample return mission is currently far into the future of {{w|Ocean Worlds Exploration Program|the related plans for exploration}}, along with the possibility of digging deep enough into the ice to finally confirm or dismiss some of the more interesting theories about the world concerned.

In Arthur C Clarke's novel '''2010''', the monolith aliens tell humanity ''"All these worlds are yours - except Europa. Attempt no landing there."'' Contrary to the suggestion of the comic, no landing or any other physical interaction beyond observation of the surface of Europa is planned.

{{comic discussion}}
[[Category:Space]]
[[Category:Space probes]]
[[Category:Food]]

3011: Europa Clipper

2024-11-14T11:39:13Z

172.68.23.91: /* Explanation */ detail

3010: Geometriphylogenetics

2024-11-12T05:07:18Z

172.68.23.91:

{{comic
| number = 3010
| date = November 11, 2024
| title = Geometriphylogenetics
| image = geometriphylogenetics_2x.png
| imagesize = 316x391px
| noexpand = true
| titletext = There's a maximum likelihood that I'm doing phylogenetics wrong.
}}

==Explanation==
{{incomplete|Created by A EUCLIDIAN GENOME - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

{{w|Phylogenetics}} refers to the practice of examining relationships among things that follow the principle of "descent with modification of progeny". In the course of descent with modification, one thing may give rise to two (the progeny), different modifications happen to each, and those modifications become established. Iterated "splits" over time yield a tree of objects; it is the purpose of phylogenetics to recover ("reconstruct") these trees, and use the information gained to inform study of the things contained. Phylogenetics has been most commonly applied to the classification/taxonomy of biological species and investigations of their evolutionary history, but it has also been used to examine the evolution of genes and biosynthetic pathways, and in the study of human languages and their evolution. Data for phylogenetic analyses may come from any attributes ("characters") of the things being examined; {{w|Computational_phylogenetics|rigorous techniques}} for these analysis became available starting in the {{w|Willi_Hennig|1950s}}. In phylogenetic studies of organisms, their DNA is far and away the most data-dense source of information, and consequently, most present-day investigations are based on analyses of selected genes and, increasingly, whole genomes. It is commonplace for such studies, especially on relatively understudied creatures, to reconstruct an evolutionary history (a phylogeny) that is radically different from what had previously been assumed - hence, "phylogenetic revolution".

This comic presents a tree, which purports to be a phylogenetic tree and resembles one, in which the endpoints ("terminal taxa") are geometric shapes, hence "geometriphylogenetics", a portmanteau of "{{w|geometry}}" and "phylogenetics". The claim, that triangles are more closely related to circles and ellipses than to squares, rectangles, pentangles, and the like, is a riff on the findings, and even the wording, of authentic phylogenetic research papers. The absurdity, and the joke, is that geometries do not change over time via descent with modification of progeny, therefore phylogenetic principles and techniques are inapplicable to their study. Moreover, geometries do not contain DNA, so genetic analysis, even if relevant, is impossible.

The title text alludes to {{w|Computational_phylogenetics#Maximum_likelihood|maximum likelihood}}, one of the most robust, and most frequently used, methodologies for phylogenetic analysis. The method builds a number of trees from the data, assigns to each a probability that it conforms to a pre-selected model of evolution, and then selects the tree that has the highest likelihood of conformity to the model. The key to the joke is that maximum likelihood is a probabilistic method; "there is a high probability that I'm doing phylogenetics wrong". Which is, in fact, the case.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[A tree diagram, or a dendrogram is shown, consisting of lines that branch off from left to right, starting with one horizontal line on the left. Eight results are shown on the right: ellipse on Path 1, circle on Path 2, triangle on Path 3, parallelogram on Path 4, trapezoid on Path 5, square on Path 6, rectangle on Path 7, and a pentagon on Path 8. The paths are listed in order top to bottom.]
:[Path 3 and the triangle are bold black, while the other branches are dimmer. The paths are connected as follows: Path 2 and 3 are connected, then both connect together to Path 1; Path 4 and 5 are connected, as are Path 6 and 7, and these two paths are connected altogether; Path 8 is then connected to the branch containing Paths 4 to 7. All of Paths 1 to 3 are then connected to Paths 4 to 8, the branches all culminating in a single line on the left.]

:[Caption below the panel:]
:The phylogenetic revolution continues:
:Triangles were long believed to be related to squares, but genetic analysis proves that they are actually very pointy circles.

{{comic discussion}}

[[Category:Geometry]]
[[Category:Biology]]
[[Category:Charts]]
[[Category:Statistics]]