explain xkcd - User contributions [en]

Talk:2817: Electron Holes

2023-08-20T07:05:50Z

162.158.86.243: /* Anode ray */ new section

I must admit... I'm not entirely convinced that one _couldn't_ build an electron hole beam. It would probably be called a quasibeam, but I think it could be done. [[Special:Contributions/162.158.175.61|162.158.175.61]] 05:11, 19 August 2023 (UTC)

Would an electron "vacuum" be an electron hole gun? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 05:30, 19 August 2023 (UTC)

Is it worth mentioning that "pewpewpew" was one of the incorrect pronunciations of Perseids in [https://www.explainxkcd.com/wiki/index.php/2814:_Perseids_Pronunciation 2414]? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 05:34, 19 August 2023 (UTC)
: Foreshadowing! Note it there? [[Special:Contributions/162.158.86.182|162.158.86.182]] 08:11, 19 August 2023 (UTC)

Objection, Your Honor! Don't know if electron quasibeams (see comment above) can be done, but the "a beam consisting of a lack of something is not possible" in the current explanation is too wide. Think of antisound devices! I think a "vacuum beam" going through normal gas pressure is very possible. And what about the Meissner effect, which could be seen as a beam of absence of a magnetic field? [[Special:Contributions/198.41.242.211|198.41.242.211]] 07:25, 19 August 2023 (UTC)
:Anti-sound just exactly(/sufficiently) compliments the sound you're trying to 'remove'. On its own, it is sound in its own right.
:Projecting a vacuum (which would, incidentally, quash sound except for that which travels round it or is caused by its creation/collapse) sounds like it needs a whole army of Maxwell's demons carrying their own 'portable hatches' to allow air molecules to leave the volume of the beam whilst batting away any that threaten to move into it. (That might be interesting to see, if noisy.)
:The Meissner Effect is an interesting (practical) version of this. Upon decreasing the possibility of an interior field, an identical increase is detetected immediately outside of it (conserving flux across the whole system, or so it seems to be/makes most sense).
:Which is not to say that there's no such thing as "a nothing", in the whole weird world of science, or variously vagues analogues to it (if you don't dig too deep, maybe). Some might suggest quantum vacuum decay might be the ultimate substantial 'nothing', but not that we know how to study it... let alone harness it. Yet! [[Special:Contributions/172.71.242.5|172.71.242.5]] 10:23, 19 August 2023 (UTC)

When the [https://en.wikipedia.org/wiki/Positron positron] was first predicted it was modeled as an electron hole, a gap in the hypothetical "sea" of negative-energy electrons filling all space. Sadly, AFAIK modern quantum field theory has done away with that idea, so while a gun that shoots a positron beam is theoretically possible, it probably wouldn't qualify as an electron hole beam. [[User:Hmj|Hmj]] ([[User talk:Hmj|talk]]) 08:03, 19 August 2023 (UTC)
:I (separately) mentioned positrons in an edit summary just now. Of course, adding the two concepts together makes for an even ''more'' ridiculous thing... A 'positron hole beam'. You know all those positrons we (don't, in general terms) have floating around us? This now projects a concentrated ''lack'' of them! [[Special:Contributions/172.71.242.5|172.71.242.5]] 10:23, 19 August 2023 (UTC)

I firmly believe the printer deserved it. It knows what it did. [[Special:Contributions/162.158.19.95|162.158.19.95]]

== Anode ray ==

A contributor wrote, "Here, the electron hole gun might refer to the anode ray tubes." An anode ray is a beam of positive ions; these are actual particles and not "quasiparticles", and therefore the comic does not refer to them. [[Special:Contributions/162.158.86.243|162.158.86.243]] 07:05, 20 August 2023 (UTC)

2775: Siphon

2023-05-14T23:11:51Z

162.158.86.243: fix typo

{{comic
| number = 2775
| date = May 12, 2023
| title = Siphon
| image = siphon_2x.png
| imagesize = 310x378px
| noexpand = true
| titletext = ADDITIONAL NOTES: Fixed a bug that caused some rocks to generate virtually infinite heat while just sitting there.
}}

==Explanation==
{{incomplete|Created by a SIPHONIC WINDS - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
[[Cueball]] and [[Megan]] have set up a simple experiment to test how a {{w|siphon}} works, using the gravitational force on an upper reservoir of liquid and molecular cohesion to move a liquid upward through a tube, traversing a higher peak to reach a lower exit. [[Randall]] has also mentioned siphons in [https://what-if.xkcd.com/143/ whatif 143] and in his book, "how to," section "how to make a pool."

Siphons are commonly used in modern society (e.g., most American residential toilets are flushed by siphon action). Siphons should not be confused with [[#Trivia|capillary action]].

Apparently, even though Cueball and Megan have set up the experiment correctly, the water no longer demonstrates a siphon by flowing from the upper bucket to the lower. Cueball observes in surprise that "it's true," that Siphons doesn't work anymore. Thus indicating that this is a very recent development, and Megan remarks that it was honestly weird that it ever worked, and muses over why we ever thought that was a normal thing.

The punchline of the comic comes in the caption, which delivers a piece of ''Physics News'': "The 2023 update to the universe finally fixed the "siphon" bug." The joke here is that the entire complex and multifaceted system of {{w|physics}} in and of itself is treated as though it's simply the logic (or perhaps the sometimes unintentional result of various default configuration options like in a video game - see [[1620: Christmas Settings]]), and that siphoning (rather than being an interesting physical phenomenon worth studying) was nothing more than a bug in the Universe, that has now somehow been fixed.

In reality, siphons still very much exist in our universe. Siphons require filling beforehand to function, either by initially actively sucking liquid through or by immersing the siphon tube in liquid then ensuring it retains its contents as one end is brought over to its position lover than the other end, so it is plausible to imagine skeptical people “proving” they do not function by refraining from providing the initial priming. However, the small amount of water in the bottom of the bucket near Megan indicates that there was water in the tube, and that this just ran down on either side, leaving the tube empty and a bit water in Megan's bucket, and a bit more in Cueball's bucket. So they did set up the experiment correctly, but since the latest update siphons do not work anymore. Or as they state it, the universe now works correctly and the siphon bug has been corrected.

{{w|simulation hypothesis|The idea}} that we live in a computer simulation is also prevalent in our modern pop culture, most famously shown in {{w|The matrix}} (See [[566: Matrix Revisited]]).

The title text is an additional note to the 2023 physics update stating that the update has: "Fixed a bug that caused some rocks to generate virtually infinite heat while just sitting there."

This is a reference to radioactive materials that keep emmiting energi (heat) almost indefinitely (on a human timescale. This is mainly a reference to {{w|uranium}} and {{w|Thorium}} and their decay chain, which are the main reason for keeping the Earths core warm.

This is similar to the comic [[2115: Plutonium]], because {{w|plutonium}} (man made though) are used to power space crafts. In that comic the title text has the same idea that someone controls the universe: ''It's like someone briefly joined the team running the universe, introduced their idea for a cool mechanic, then left, and now everyone is stuck pretending that this wildly unbalanced dynamic makes sense.''

The entire comic is one of many where Randall muses over strange aspects of our universe, and wonders why we (people) ever think that it seems normal, the way the Universe works (or how humans works - see for instance [[1268: Alternate Universe]]).

==Transcript==
:[Cueball is standing next to two buckets while Megan is looking on from the other side of the buckets. The left bucket is on a stool and is almost filled with water while the other is on the ground and has a very small amount of water in it. Cueball is holding an empty tube between the two buckets. The end to the left is deep into the water in the left bucket while the other end hangs into the empty bucket to the right.]
:Cueball: Wow, it's true—the water doesn't flow up the tube anymore.
:Megan: Honestly, it's weird that it ever did.
:Megan: Why did we think that was normal?

:[Caption below the panel:]
:Physics news: The 2023 update to the universe finally fixed the "Siphon" bug.

==Trivia==
Siphons are separate from a similarly counter-intuitive phenomenon of {{w|capillary action}}, where a liquid flows through narrow spaces (even upwards, entirely against gravity) in that a siphon need not be of such small diameter. Capillary action will also move liquid into an initially empty channel, whilst a siphon must be 'primed', by filling the tube, in order to draw liquid over a high point to ultimately always drop down into a lower container. Capillary action is caused by surface tension and attractive forces between the liquid and the walls of the channel; the liquid level will rise until the weight of the column of liquid matches the attractive forces. A siphon requires that the weight of the liquid column on the "higher" side of the channel peak not exceed atmospheric pressure, or else the liquid will split, leaving a {{w|Torricelli's_experiment|partial vacuum}}. Capillary action can lift liquid higher than the maximum height of the "higher" side of a siphon with the same liquid, if the attractive forces are strong enough.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Physics]]

Talk:2761: 1-to-1 Scale

2023-04-11T06:59:05Z

162.158.86.243: Note that the display would be larger than earth itself

Really want an explanation for this one. [[User:JobbieJimmies|Melomaniac]] ([[User talk:JobbieJimmies|talk]]) 03:23, 11 April 2023 (UTC)

My comment got deleted by a bot!!! [[User:Unreliable Connection|2659: Unreliable Connection]] ([[User talk:Unreliable Connection|talk]]) 03:23, 11 April 2023 (UTC)
:RIP... [[User:JobbieJimmies|Melomaniac]] ([[User talk:JobbieJimmies|talk]]) 03:25, 11 April 2023 (UTC)
:No, UC, it just got overwritten by the 'bot, when it did its job and (re)created the wholeinitial state of the various pages to depict the new comic coming out. (Noting that you'd not set them all up fully/correctly.)
:That you had spotted it already and had ''just'' gotten in ahead of the 'bot clearly isn't something it was prepared to handle. But as someone spotting it can usually wait a short while for the 'bot to catch up, I don't think it's a problem. In fact, you could have just copied your old contributions into the now receptive page(s), with nary any comment. Too late now. [[Special:Contributions/172.70.90.101|172.70.90.101]] 03:44, 11 April 2023 (UTC)

:: This may have broken the next link on the previous page. --[[Special:Contributions/172.71.160.36|172.71.160.36]] 06:41, 11 April 2023 (UTC)

The lines represent the surfaces of the planets I think, so it's basically all the planets overlaid on top of each other. [[Special:Contributions/172.71.142.35|172.71.142.35]] 03:28, 11 April 2023 (UTC)

:Yup, I think it's what he meant - but I find it unlikely that the gas giants would have this clear cutoff of a "surface". [[Special:Contributions/162.158.189.241|162.158.189.241]] 03:34, 11 April 2023 (UTC)

I’d think the same citation as stands for ridiculously large would also cover larger than currently exists on earth, and his that citation is not in fact needed? [[Special:Contributions/162.158.174.186|162.158.174.186]] 06:53, 11 April 2023 (UTC)

:It seems like the gas-covered worlds are explicitly those with clearly cutoff "surfaces," so maybe in those cases the cutoff is some specific gas density -- which occurs at a consistent radius throughout the planet, thus creating a flat surface. While for rocky worlds (except Venus, which is treated like a gas planet here), a density cutoff can lead to bumpiness due to terrain. [[User:Trimeta|Trimeta]] ([[User talk:Trimeta|talk]]) 03:57, 11 April 2023 (UTC)

On Twitter there seems to be concern that all planets are depicted flat. This may make this a contribution/mockery of the ongoing [https://en.wikipedia.org/wiki/Flat_Earth Flat Earth] discussions in some corners of the internet. --[[Special:Contributions/198.41.242.132|198.41.242.132]] 06:49, 11 April 2023 (UTC)

The display for an uncropped version of the image would not only be larger than any display on earth. It would be larger than earth. [[Special:Contributions/162.158.86.243|162.158.86.243]] 06:59, 11 April 2023 (UTC)