explain xkcd - User contributions [en]

3085: About 20 Pounds

2025-05-07T18:27:59Z

172.71.147.21: /* Explanation */ asking not demanding

{{comic
| number = 3085
| date = May 5, 2025
| title = About 20 Pounds
| image = about_20_pounds_2x.png
| imagesize = 666x278px
| noexpand = true
| titletext = In addition to gravity, burritos interact through the strong, weak, and electromagnetic forces, which is believed to be a major contributor to their popularity.
}}

==Explanation==
{{incomplete|Created by a £20 20-LB PARTICLE. Are any categories missing? Don't remove this notice too soon.}}

The nature of {{w|dark matter}} is a significant unsolved problem in physics. In an effort to solve the problem, [[Cueball]] and [[Ponytail]] appear to have used occult methods to conjure a supernatural {{w|oracle}} (something which would present its own challenges to our understanding of the physical world) in order to ask it for an answer. There may be a pun here, in that they are using 'dark magic' to communicate with something from the 'dark realm' on the assumption that it will know about dark matter. However, the word 'dark' in this context simply means that we do not know how to observe it; dark matter is not evil or satanic (though [[Randall]] may consider it [[:Category:Comics with cursed items|cursed]]). The oracle is used very similarly to how people have been using and customizing large language models.

In general, not all forces interact with all particles; indeed, {{w|gravity}} is believed to be the only force that interacts with everything. If a force doesn't interact with a particle, then the particles existence cannot be observed via disturbances in that force. In particular, something that doesn't interact with electromagnetism cannot be 'seen', as photons will pass through it completely unaffected, and likewise cannot be felt, because collision is a side effect of the {{w|Pauli exclusion principle}}.

Even {{w|neutrino}}s—famous for {{what if|73|interacting with ''almost'' nothing}}—still in fact interact via the {{w|weak force}}, allowing them to be detected with sufficiently large tanks of dense material (as most atoms do in fact interact with the weak force, however weakly). A particle that interacts with ''nothing'' except gravity could only be detected by a {{w|LIGO|gravitational telescope}}.

However, even if a particle does interact via a given force, an interaction is possible only if energy is conserved. If dark matter is entirely due to a single kind of particle with the fundamental mass of ''about twenty pounds'' (a rather vague measurement, in the rough vicinity of 10 kilograms, but in line with how apparently all-knowing oracles legendarily avoid unambiguous statements), this is an absolutely ludicrous amount of energy for particle physics. Any interaction would have to involve an equally ludicrous amount of other particle mass being in exactly the right place and time, a coincidence that could easily reach "never in the history of the universe" levels. By comparison, the {{w|top quark}}, otherwise the heaviest single particle with a mass over a hundred times that of the proton, is still nevertheless around a tenth of a trillionth of a trillionth of a pound.

Under more normal circumstances, we might still hope to observe the properties of the particle via creating it ourselves under controlled laboratory conditions. But again, there is no reasonable way to focus the energy required into a single particle interaction. The {{w|Large Hadron Collider|most powerful particle accelerator in the world}}, for example, peaks at about ten thousand times the mass of the proton—a solid billion times less energy than required—so it's out too.

Despite all this, twenty pounds is also much too ''small'' to be detectable via gravitational interaction—its {{w|Perturbation (astronomy)|influence on the orbits of planets}}, say, or the strength of its {{w|gravitational lensing}} effect, would be entirely negligible. Thus in the scenario posed by the comic, there is essentially no plausible way to observe more about dark matter while on Earth. Even if we did find some such particles naturally occurring, and had instruments that could measure such small gravitational forces, since it would interact only via gravity, the only properties it could have other than mass would be its decay rates from other particles—which, again, would all be essentially nil due to its mass.

The oracle proceeds to break expectations by suggesting that Ponytail and Cueball go out for {{w|burrito}}s, something generally considered non-scientific. When faced with the apparent futility of continuing to try to investigate dark matter, the oracle predicts that going out for burritos is precisely as productive as any other approach—i.e., not at all. It justifies the suggestion by burritos being "pretty" good, again neither exactly quantifying the oracularity, and likely not even giving the optimal idea (for choice of food, or of any other "what now?" diversion that it might give).

The title text observes that burritos interact through all four known {{w|fundamental interactions}}, making burritos popular. The electromagnetic force mediates the chemical reactions leading to a burrito's taste, the strong force keeps atomic nuclei together, and gravity gives burritos heft, all of which are helpful for enjoying them. It's hard to see how the weak force, which takes part in radioactive decay, helps with burrito enjoyment or popularity, but the weak force is responsible for the nuclear fusion that allowed the complex elements of the burrito to exist in the first place.

==Transcript==
:[Cueball and Ponytail are standing in front of a pentacle with lit candles at the corners. A black sphere, the oracle, is floating above the middle of the pentacle.]
:Ponytail: Dear oracle,
:Ponytail: What is the nature of dark matter?
:Oracle: It's about 20 pounds.

:[Close up of oracle]
:Off-panel: What?
:Oracle: Dark matter is a particle. It weighs about 20 pounds.
:Oracle: It only interacts through gravity.

:[Same view as first panel]
:Cueball: Only gravity, huh?
:Cueball: So none of our experiments are really going to tell us any more about it, then.
:Oracle: Afraid not.

:[Same view as first and third panels, except Cueball lifted his forearm.]
:Cueball: So what do we do?
:Oracle: You should go out for burritos.
:Ponytail: How will that help?
:Oracle: Well
:Oracle: Burritos are pretty good.

{{comic discussion}}<noinclude>
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Physics]]
[[Category:Food]]

Talk:3081: PhD Timeline

2025-04-26T02:02:41Z

172.71.147.21:

What an age we live in... --[[User:DollarStoreBa'al |DollarStoreBa'al]][[User talk:DollarStoreBa'al | Converse]][https://www.explainxkcd.com/wiki/index.php/Special:Contributions/DollarStoreBa%27al My life choices] 15:48, 25 April 2025 (UTC)
:[https://www.cnn.com/2025/04/25/politics/fbi-director-wisconsin-judge-arrested/index.html It only gets rougher... ] It's enough to radicalize a person. [[Special:Contributions/172.69.65.187|172.69.65.187]] 16:09, 25 April 2025 (UTC)
:When even Randall starts freaking out, it usually indicates the most entertaining timeline. [[Special:Contributions/162.158.245.161|162.158.245.161]] 00:58, 26 April 2025 (UTC)

Events like this are scary, and they're even scarier if you have a personal or geographic connection to them like Randall does. I can understand why he would feel frustrated about his inability to do something concrete, and if this comic raises awareness for the situation then it has done a good thing. Not sure why I thought this comment was necessary; maybe it's just a way of processing the emotions that the comic made me feel. [[User:Dextrous Fred|Dextrous Fred]] ([[User talk:Dextrous Fred|talk]]) 15:49, 25 April 2025 (UTC)

I dont want to start an argument, but I am glad Randall Munroe is making a specific, reasonable point. A lot of times I see people saying either "there is no antisemitism on campus, nobody should ever get deported, ACTUAL terrorists should get green cards", and others say "EVERYONE WHO DISAGREES WITH ME SHOULD GET DEPORTED, EVERYONE WHO DISAGREES WITH ME IS A TERRORIST." I think both of them are extreme points obviously, and I am glad Randall is just taking the side, for now, of "this specific person did not violate their green card visa."

:Hi, expert-on-the-Öztürk-case but not-an-immigration-expert-really here. For clarity, Öztürk held an F-1 student visa but was not a lawful permanent resident (LPR) (green card holder), unlike the similar case of Mahmoud Khalil (Columbia university) who was a green card holder. And "green card visa" is not a thing, there's a "green card," which you cannot "violate" (although you could commit crimes that might have consequences for your LPR status), and you generally don't hear "violate their visa" although it's true that a visa is related to and may restrict that work you can do in the country. Regardless, no allegations have been made that Öztürk violated anything laws or rules or did anything other than lend her name to speech in a newspaper. [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 22:51, 25 April 2025 (UTC)

as always, based randall, at least for now. [[User:Tzelofachad|Tzelofachad]] ([[User talk:Tzelofachad|talk]]) 16:04, 25 April 2025 (UTC)
:Did you mean "biased"? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 16:31, 25 April 2025 (UTC)
::Did you mean "biased towards due process?" [[User:CharlesT|Nyrrix]] ([[User talk:CharlesT|talk]]) 16:51, 25 April 2025 (UTC)
::It's probably "based", as that's a term that can either be used in support or mockery of a philosophical position (because of Poe's Law, hard to know which in most cases, including here). It's more usually used in 4chan-like responses (and I doubt Randall would be considered "based" in those other places) than hereabouts, so perhaps it needs some clarification for those not (or not enough) in that sort of crame of mind. [[Special:Contributions/141.101.99.94|141.101.99.94]] 17:06, 25 April 2025 (UTC)
:Yes, Randall Munroe clearly only cares about this one incident because he does not at all care about politics. He's definitely not using this as an illustrative case on the countless other identical incidents happening under the Trump administration. /s /s /s /s /s. [[User:DrMeepster|'''Dr.'''Meepster]]
(<[[User_talk:DrMeepster|chat]]> •
<[{{fullurl:{{FULLPAGENAME}}|action=edit}} reply]>) 16:53, 25 April 2025 (UTC)

I really hope this is one of those comics that does NOT stand the test of time. In other words, I hope the next generation of graduate students sees this and thinks "oh, that must've been written in 2025, we don't have to worry about those kinds of things anymore." Perhaps "hope" isn't the right word, it implies I have hope. Maybe "pray fervently" is the right phrase. Sigh. [[Special:Contributions/198.41.227.72|198.41.227.72]] 16:30, 25 April 2025 (UTC)
:Sure ... "Oh, that was before third world war, we don't have to worry about those kinds of things anymore." -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 00:08, 26 April 2025 (UTC)
:We can go back to considering how the Ph.D. became a participation trophy for the financial benefit of the awarding institution - and, in the sciences, a source of slave labor. [[Special:Contributions/172.71.146.61|172.71.146.61]] 01:51, 26 April 2025 (UTC)

How do we edit the Categories? This should have category Politics. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 16:31, 25 April 2025 (UTC)
:Usually, once at least one other category (not created from templates like {{template|comic}}) you can edit the page and see the other cat(s) at the bottom, beyond the comic-discussion template. Or edit the Transcript section (or any Trivia one, whatever's the last one) as that'll also have the tail-end of the page. So long as you know there's a category "Foo", you should be able to work out how to add "Category:Foo".
:But don't add Foo if it doesn't exist, hoping that someone will tire of the redlink that's created. You may be wrong about it needing to exist, or miss the ''actual'' "Category:comics featuring Foo", and unless someone is feeling generous it's possible that your edit just gets reverted as not properly researched, or checked... I ''think'' there actually is a Politics category, by that name, but I'm trying to answer the general question, not yet going out there to look it up for certain (at which point, I may have just added it myself, making it useless to have explained how you could 'easily' do it... At least in this instance).
:'''TL;DR;''', though, look at the source (wiki-edit) of another comic that is about Politics and is so categorised. Go all the way to bottom, and you'll see which 'tag' you might want to put at the bottom of this one. Should be obvious. [[Special:Contributions/141.101.99.94|141.101.99.94]] 17:06, 25 April 2025 (UTC)
I think I've added that category now [[Special:Contributions/104.23.190.60|104.23.190.60]] 19:33, 25 April 2025 (UTC)

I'm so tired of this administration :( [[User:CharlesT|Nyrrix]] ([[User talk:CharlesT|talk]]) 16:49, 25 April 2025 (UTC)
:Are you a citizen of the USA? If so, are you dead? In exile? In jail? Have your assets been seized? No to these? Then this is your administration and mine. Own it, or act. "Tired" doesn't cut it. [[Special:Contributions/172.71.147.21|172.71.147.21]] 02:02, 26 April 2025 (UTC)

The comic on mobile has the title text has a youtube video URL, and if you click on the comic on desktop version, it links to the youtube video of the arrest. This isn't reflected in the description currently. [[Special:Contributions/172.70.126.121|172.70.126.121]] 16:51, 25 April 2025 (UTC)

The video URL is '''https://www.youtube.com/watch?v=JyypeEEOklM''' and appears to be "'''CBS Boston [282K subscribers]'''" so probably legit?
I will try to add the URL. --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 17:08, 25 April 2025 (UTC)
:For the sake of consistency, I copy-pasted the "note" from [[1723]] into this comic. '''I also think we should have a category and perhaps a template to make adding notes like this easier and more uniform.''' [[Special:Contributions/172.69.67.22|172.69.67.22]] 21:11, 25 April 2025 (UTC)
::Well, you can create it right now if you want! --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 22:08, 25 April 2025 (UTC)

Is this the first with an out of site link? {{unsigned}}
:No this happens often. For instance this comic {{xkcd|1723}}. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 20:09, 25 April 2025 (UTC)

Again, let's keep the explanation as neutral as possible. Facts only. [[User:Dogman15|Dogman15]] ([[User talk:Dogman15|talk]]) 18:49, 25 April 2025 (UTC)
: the problem is facts have a heavy anti trump bias. You CAN NOT state basic facts and not be against this regime [[Special:Contributions/162.158.112.187|162.158.112.187]] 00:05, 26 April 2025 (UTC)
:: I think it's important to emphasize that neutrality is simply a bias towards the truth rather than towards anything else. On a technical level, being unbiased precludes being neutral and being neutral precludes being unbiased, even if people mostly use the word "unbiased" in the same way as "neutral". In other words, bias isn't inherently a bad thing.[[Special:Contributions/172.71.102.219|172.71.102.219]] 00:48, 26 April 2025 (UTC)

Of course, the bit I was correcting (with bad grammar, and lack of facts) got totally changed about before I tried to post it. "''For instance citizens usually {{w|Deportation of Americans from the United States|cannot be deported for any reason}} (only extradited, although the US typically refuses to comply with requests even from countries that freely extradite to it), and would instead be subject only to local legal penalties, but relatively minor allegations have resulted in visitors' extraditions.''" was what I wrote. Now, I ''think'' that was neutral enough, but it doesn't fit there now anyway. [[Special:Contributions/172.70.58.113|172.70.58.113]] 22:45, 25 April 2025 (UTC)

:Ack, I think I'm the one who changed it before you could. My bad. Anyway, seconded. Opinion on the conflict in Gaza itself is not needed in this explanation; the edit that suggested that the student could be materially linked to Hamas by providing a link to an opinion poll of how Palestinians feel about the Oct 7 attacks is, in my opinion, very disingenuous, especially considering Ozturk is not Palestinian but Turkish, making the cited data even more blatantly irrelevant than it already would have been. [[User:Psycherprince|Psycherprince]] ([[User talk:Psycherprince|talk]]) 23:05, 25 April 2025 (UTC)

This article could potentially be a reasonable place to try to establish a norm of separately including opposing sides of political topics (rather than the usual edit conflicts). [[Special:Contributions/172.70.110.176|172.70.110.176]] 00:35, 26 April 2025 (UTC)

Step 6: Try not to lose your visa when traveling or studying abroad by being a nuisance, since visas (in any country) can be denied or revoked for virtually any reason. [[Special:Contributions/162.158.112.168|162.158.112.168]] 01:06, 26 April 2025 (UTC)
:Pray the leopards never eat your face.
::I'll bring decoy meat and try not to insult the cheetahs while visiting. [[Special:Contributions/162.158.112.186|162.158.112.186]] 01:45, 26 April 2025 (UTC)

2743: Hand Dryers

2023-02-28T03:28:07Z

172.71.147.21:

{{comic
| number = 2743
| date = February 27, 2023
| title = Hand Dryers
| image = hand_dryers_2x.png
| imagesize = 618x309px
| noexpand = true
| titletext = I know hand dryers have their problems, but I think for fun we should keep egging Dyson on and see if we can get them to make one where the airflow breaks the speed of sound.
}}

==Explanation==
{{incomplete|Created by a DYSON ENGINEER - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
A {{w|hand dryer}} is an electrical device which usually uses hot air to dry the user's hands after they have just washed them. In the 30 or so seconds it takes for user's hands to be dried, the user may feel as though the air coming from the hand dryer isn't actually warm, hence seeming like they "take forever to heat up," while in reality the water evaporating from the user's wet hands absorbs heat energy from them, as well as the heated air, as {{w|evaporation}} is an endothermic process. Thus, the user does not ''feel'' that the air from the dryer is warm, even though it is, and will only start to do so once their hands have been significantly dried. Interestingly, this absorption of heat through evaporation is how human {{w|sweat}} has its cooling effect, which means that even warm ambient air can be made to feel colder by being wafted across a person's skin.

Randall has apparently procured a small airplane, accompanied by a banner with a message explaining this phenomenon. He elaborates in the caption that he's spent dozens of years feeling angered with the engineers of these hand dryers, as he was under the comic's erroneous impression that the air from the dryers was not actually warm. In a presumable act of justice for hand dryer engineers everywhere, he now considers it his personal mission to explain to the public why this is actually a misconception. And indeed, it seems to be working - a person on the ground has already been [[1053: Ten Thousand|enlightened]] by Randall.

In the title text, the {{w|speed of sound}} is (obviously) the speed of a sound wave in a given medium, usually air. Breaking the {{w|sound barrier}} is often touted as a significant achievement for powered aircraft (this was first safely achieved in the 1940s, and became significantly 'easier' with the development of the jet engine). Here, Randall thinks it would be a good idea to try and get the {{w|Dyson (company)|Dyson company}} (a technology company known for making high-tech, fancy, and expensive air-moving devices such as vacuum-cleaners, fans and hand dryers) to design a hand dryer whose airflow would break this sound barrier. This would probably not be possible to achieve with such a relatively small device as a hand dryer, nor would such a hand dryer really be practically useful, given that air currents faster than the speed of sound would probably injure the hands of the dryer's users, among other unintended effects.{{citation needed}}

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

:[An airplane tows a banner. In the distance, there are three small clouds and three birds]

:[On the banner is written:] It seems like hand dryers take forever to heat up, but that's because the evaporation cools your skin, so the hot air feels cold until the water is gone.

:Voice coming from the bottom of the panel: Ohhh!

:[Caption below the panel:] I spent decades mistakenly annoyed at hand dryer engineers, so now I'm on a mission to save others from the same fate.

{{comic discussion}}
[[Category:Engineering]]
[[Category:Aviation]]

Talk:2731: K-Means Clustering

2023-02-01T10:48:15Z

172.71.147.21:

{{w|K-means_clustering|The wikipedia article}} does not clear anything up [[Special:Contributions/162.158.78.228|162.158.78.228]] 13:53, 30 January 2023 (UTC)Bumpf

The "Convergence of ''k''-means" animation is reasonably distinctive for a two-dimensional case, showing at least the motivation for the problem . Could it be attached here? [[User:Mia yun Ruse|Mia yun Ruse]] ([[User talk:Mia yun Ruse|talk]]) 14:08, 30 January 2023 (UTC)

Yeah, this is probably the least explanatory Explain xkcd I've read in the past 3 years. Still a lot of heavy math. [[Special:Contributions/162.158.186.95|162.158.186.95]] 16:50, 30 January 2023 (UTC)

This feels very similar to the joke "There are 10 types of people: those who know binary and those who don't." Except that the real joke here is that Ponytail doesn't have anything meaningful to justify her version. [[Special:Contributions/172.70.206.150|172.70.206.150]] 17:45, 30 January 2023 (UTC)

Current explanation claims that since every human is unique, clusters can only be formed by ignoring some traits. This seems false; a cluster could depend on multiple traits, so there's no obvious limit to the number of traits that could be used when forming clusters. Perhaps they mean that clusters can only be formed by combining non-identical points into the same cluster, but that's literally the entire purpose of clustering and applies to all clustering ever, so it seems like both a trivial observation and a non-sequitur. Am I missing something? [[Special:Contributions/172.70.211.90|172.70.211.90]] 19:54, 30 January 2023 (UTC)
:Yes, the joke about why there are 8 billion clusters mentioned in the title text. [[Special:Contributions/162.158.78.220|162.158.78.220]] 20:47, 30 January 2023 (UTC)
::No, I did not miss that. --[[Special:Contributions/172.70.211.136|172.70.211.136]] 22:53, 30 January 2023 (UTC)
:While it's true that clusters can depend on multiple traits, a cluster that depends on ALL human traits at once (or a very large number of them) is useless in practice. A useful cluster depends on a relatively limited number of traits. I think that's where the "ignoring" comes in. [[Special:Contributions/162.158.146.208|162.158.146.208]] 22:30, 30 January 2023 (UTC)
::Supposing that's true, that would apply to any sample of humans. The "since all humans are unique" part would still be false, and the comment still wouldn't make sense in context as a response to the specific scenario of 8 billion humans. --[[Special:Contributions/172.70.211.136|172.70.211.136]] 22:53, 30 January 2023 (UTC)
:::Most people would object to the idea that they are fully defined by their DNA. Yet even taking just DNA, the probability of two humans having same is practically zero. Even identical twins have differences in DNA due to radiation and toxins! Sure, 99% of DNA is identical between all humans (is what makes them human), but DNA is over 6 Gigabase pairs. And how many do you think criminalists needs in DNA identification to ensure match probabilities of 1 in a quintillion? Just hundreds. Yes, every human is unique. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 02:50, 31 January 2023 (UTC)
::::Obviously humans are unique, and I never suggested otherwise. The thing that's false is the complete statement "it's necessary to ignore some traits BECAUSE all humans are unique". I actually think "it's necessary to ignore some traits" is not well-supported even if you stop there, but even if that part is true, it's definitely not a RESULT of all humans being unique. The current explanation reads like someone is twisting the topic to squeeze in a comment about their hobby horse even though it's not actually relevant. --[[Special:Contributions/162.158.90.38|162.158.90.38]] 00:37, 1 February 2023 (UTC)

Many people object to being defined by some group they belong to. E.g. people objecct to blanket statements about members of political parties ("I'm a Republican, but I'm pro-choice"), religions, age groups (the adage "If You Are Not a Liberal at 25, You Have No Heart. If You Are Not a Conservative at 35 You Have No Brain"), etc. I think this is the idea that the title text is going for. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 20:43, 31 January 2023 (UTC)

There are two types of ''people'' in the world: those ''who'' use the word “who” to refer to people and the word “that” to refer to things, and those ''who'' don’t. [[Special:Contributions/172.71.151.77|172.71.151.77]] 02:58, 31 January 2023 (UTC)
:...and those whom use "whom"..? [[Special:Contributions/172.70.162.57|172.70.162.57]] 09:00, 31 January 2023 (UTC)
::Sure, there are plenty who misuse “whom” also. “Who / he / she / they VERB” vs “PREPOSITION whom / him / her / them” - who did, who has, who owns, he did, she has, they own - for whom, by whom, about whom, for him, by her, about them. A person who, a thing that. It’s really not that complicated. [[Special:Contributions/172.71.147.21|172.71.147.21]] 10:48, 1 February 2023 (UTC)

== editorial ==

This sentence clause appears to contain a typo: ", and indicate on a graph '''of''' the data has two distinct populations".
It might be clearer as ", and indicate on a graph '''if''' the data has two distinct populations". (Fixed)