explain xkcd - User contributions [en]

Talk:2413: Pulsar Analogy

2021-01-20T05:01:16Z

162.158.74.85:

I tried applying the right-hand-rule with the y-axis pointing to the right. :( I hurt my hand.
[[User:Avitzur|Avitzur]] ([[User talk:Avitzur|talk]]) 23:22, 18 January 2021 (UTC)
:Rotate your paper then do the right hand rule :)
:Hand joint exercises. Gentle motions with the wrist bent backwards, and bent forwards; 3-5 circles in both directions and both postures, twice a day. [[Special:Contributions/162.158.62.41|162.158.62.41]] 00:48, 19 January 2021 (UTC)
[[Special:Contributions/172.69.35.149|172.69.35.149]] 23:38, 18 January 2021 (UTC)

The analogy doesn't seem to be inaccurate in the way currently indicated. In both cases (tape measure and pulsar), conservation of ''angular'' momentum is what produces the result. With the tape measure, a small fast-spinning thing turns into a large slow-spinning thing; the opposite happens with a pulsar. [[Special:Contributions/172.69.35.150|172.69.35.150]] 00:05, 19 January 2021 (UTC)
:Isn't a tape measure bigger, not smaller, and slow-spinning, not fast-spinning, when it is elongated? This is very confusing. Thinking of how pulling the tape out stores energy. [[Special:Contributions/162.158.62.41|162.158.62.41]] 00:49, 19 January 2021 (UTC)
::A tape measure starts off not spinning. It's the acceleration of the tape as it moves in that starts the rotation, because the motion of the tape measure is not precisely radial. Same principle, different problem. [[User:Ltmauve|Ltmauve]] ([[User talk:Ltmauve|talk]]) 02:29, 19 January 2021 (UTC)
:::As the tape retracts, the tape inside the case is spinning. Once it is fully retracted, the case spins. Small spinny --> large spinny.
:::Of course, on a frictionless surface there's some slow retrograde rotation of the case + extended tape that speeds up as the tape retracts, but the case should completely stop spinning once the tape is fully retracted in that scenario, which is opposite of the analogy being drawn. [[Special:Contributions/172.69.34.12|172.69.34.12]] 02:43, 19 January 2021 (UTC)
::::On a frictionless surface, it would ''never'' stop spinning. Once the case starts to spin, there's nothing to slow it down. --[[Special:Contributions/172.69.63.183|172.69.63.183]] 17:45, 19 January 2021 (UTC)
:::::On a frictionless surface, before the extended tape measure is released, it has no net angular momentum. After it is released, the winding tape carries angular momentum, so the case+extended tape must spin in the opposite direction for the entire tape measure system to continue to have no net angular momentum. When the tape suddenly stops, it will no longer carry any angular momentum, so the case must stop spinning entirely for the system to continue to have no net angular momentum. Because of friction, we usually don't see the retro-rotation of the case until the tape is almost completely wound up. See also dlvozza's Impact Driver comment. [[Special:Contributions/172.69.35.85|172.69.35.85]] 21:27, 19 January 2021 (UTC)
::: It seems to me like the reason the full tape measure spins is somewhat similar to an Impact Driver. Shooting slow motion videos of retracting my tape measure I see a small rotation in the opposite direction of the rotation in the end (likely due to the device maintaining angular momentum as the spring inside spins up) and then a quick snap when the tape is fully retracted, followed by the tape spinning very quickly in the opposite direction. As for my comparison to an impact, this reminds me a lot of how those work, with some inner barrel spinning at a very high speed, and then mechanically imparting that energy onto the body of the driving head, causing it to turn with a high torque. Typically when you start an impact spinning you can feel a small torque opposite to how the driver end spins because of the inner barrel spinning up. In the tape measure the inner spinning barrel is the tape itself and the spring to retract it, the driver head is the outer shell of the tape measure. [[User:dlvozza|dlvozza]] ([[User talk:dlvozza|talk]]) 19:48, 19 January 2021 (UTC)

Currently the description starts off “Pulsars are dead stellar cores” and that phrase seems very bizarre to me, since <b>all</b> stellar objects are <I>dead. </I>Do astronomers routinely anthropomorphize to such a degree as to call some stars alive and others dead? I would think more literal language like “A pulsar is the very compact and highly magnetized remains of a star after a nova or supernova explosion” but if the acceptable astronomical parlance is to say “dead star” far be it for me to demand a change[[Special:Contributions/162.158.63.94|162.158.63.94]] 05:26, 19 January 2021 (UTC)
:I find the "dead star" also odd. Sure, I know what is meant, but in the same way I know what is meant by the tape measure analogy. Neither is accurate. Side note: I removed the part about the measures' lifespan and how you could repair it as this gives no benefit for the explanation and is totally irrelevant. [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 10:18, 19 January 2021 (UTC)
:The word "dead" can be used to refer to inactivity in an object that was never classically alive. i.e. dead volcanoes --[[Special:Contributions/188.114.102.60|188.114.102.60]] 15:55, 19 January 2021 (UTC)
:Humans aren't the only things that can be alive or dead, so calling it anthropomorphization is way off mark. But besides that, stellar objects aren't all "dead", they're non-living. You have to be alive and then die to be dead, in the biological sense. But in this case, it's called a "dead stellar core" because it no longer has sustained fusion reactions which is what stars are known for, just like a battery that's used up all of its charge is called "Dead" - not because we're assigning human qualities, but because it doesn't do what it's supposed to. Same with any non-living thing that doesn't function as expected being referred to as dead. --[[Special:Contributions/172.69.63.183|172.69.63.183]] 17:41, 19 January 2021 (UTC)
:Astronomers also ''bio''morphise stars by talking about when they are "born" – the moment sustained fusion starts in the core. [[Special:Contributions/172.69.35.7|172.69.35.7]] 21:34, 19 January 2021 (UTC)

The increased angular velocity as the star shrinks is analogous to the way an ice skater's rotational velocity changes as they draw their arms in and out, no? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 23:59, 19 January 2021 (UTC)

Currently, the explanation doesn't say anything about the last panel, and should probably emphasize the core of the joke in that the explanation starts out kind of reasonable, albeit imperfect, but then gets progressively much worse when it is elaborated on in the last 2 panels (the initial analogy is a lot more reasonable than the stuff about the laser, and the fourth panel is just nonsense.)--[[Special:Contributions/162.158.74.85|162.158.74.85]] 05:01, 20 January 2021 (UTC)

Talk:2411: 1/10,000th Scale World

2021-01-14T18:26:57Z

162.158.74.85:

This sounds like a cool theme for a game jam. [[User:Bwisey|Bwisey]] ([[User talk:Bwisey|talk]]) 07:30, 14 January 2021 (UTC)

The comment about airplanes being close to the speed of a bullet in the explanation wouldn't be relevant due to the scale, so they wouldn't be fast compared to the scale of the people here, and with some rough calculations, I think it would take multiple seconds to pass through the thickness of a human body, so if the people were normal properties and the plane moving at its speed being proportional to its scale (thus making its speed seem normal from the perspective of someone shrunk down and on the plane looking at the rate at which it travels compared to its own length or looking at the model surroundings rather than the giant person), it shouldn't cause significant injury. Granted, as such speeds it wouldn't be able to fly, but the same sort of concerns apply to a lot else here, like the thundercloud and the rate the atmosphere gets thinner at altitude.--[[Special:Contributions/162.158.74.207|162.158.74.207]] 07:54, 14 January 2021 (UTC)

"Also, airplane speed very similar to the speed at which a bullet is fired" - That is true for real world aircraft; it is not at all given for the 1/10000th scale world. (It depends on if time is scaled or just spatial dimensions) [[Special:Contributions/162.158.134.84|162.158.134.84]] 09:59, 14 January 2021 (UTC)

The rant about private vs public research seems a tad coat-racky. [[User:Yngvadottir|Yngvadottir]] ([[User talk:Yngvadottir|talk]]) 12:08, 14 January 2021 (UTC)
: I agree, so I removed it. There's no indication that Randall meant anything more by it than the usually fun activity of playing with balloons would be harmful if done to weather balloons. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 13:45, 14 January 2021 (UTC)

Do disasters in the model have consequences in the real Earth, like in the first row of xkcd #1515? Not being allowed to create megatsunamis or trigger the Yellowstone Supervolcano would support this, but being allowed to step on cities that do not have especially pointy towers would oppose it.[[Special:Contributions/162.158.186.220|162.158.186.220]] 14:07, 14 January 2021 (UTC)

This, ladies, gents, and variations thereupon, is the ''xkcd'' I know and love. [[User:Lightcaller|Lightcaller]] ([[User talk:Lightcaller|talk]]) 14:34, 14 January 2021 (UTC)

I would really like this on a poster. [[Special:Contributions/172.68.57.33|172.68.57.33]] 16:12, 14 January 2021 (UTC)

Wouldn't an airplane be to the people about twice the speed of a garden snail? [[User:Sarah the Pie(yes, the food)|Sarah the Pie(yes, the food)]] ([[User talk:Sarah the Pie(yes, the food)|talk]])

: I thought comparisons of scale were an oft-revisited theme for xkcd, so was disappointed not to find a category for them; though I tried to list some of them, I didn't find nearly as many of them as I thought there ought to be. Only just noticed the reference in discussion here to 1515, which kind of supports my suspicion that there are lots I didn't find. --[[User:Pi one|Pi one]] ([[User talk:Pi one|talk]]) 17:06, 14 January 2021 (UTC)

I like how the curvature of the world is drawn to scale as well. IE: imperceptibly curved. [[Special:Contributions/108.162.216.182|108.162.216.182]] 17:13, 14 January 2021 (UTC)

Probably not actually related to the comic, but the notes in the explanation about how "earth on this scale would be the size of an asteroid" made me think of the Little Prince, which Randall is known to be fond of. -MeZimm [[Special:Contributions/162.158.74.85|162.158.74.85]] 18:26, 14 January 2021 (UTC)

Talk:2398: Vaccine Tracker

2020-12-15T02:53:15Z

162.158.74.85:

🎵 A B C D E F G H I've got a cure! 🎶
[[Special:Contributions/162.158.74.85|162.158.74.85]] 02:53, 15 December 2020 (UTC)

2296: Sourdough Starter

2020-04-20T21:31:40Z

162.158.74.85: /* Explanation */ added a blurb on symbiosis and parasites

{{comic
| number = 2296
| date = April 20, 2020
| title = Sourdough Starter
| image = sourdough_starter.png
| titletext = Once the lockdown is over, let's all get together and swap starters!
}}

==Explanation==
{{incomplete|Created by a BOT WITH AN EXTREMELY CONVOLUTED PARASITIC LIFE CYCLE. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Recently, because of the coronavirus, many people are forced to stay home in quarantine. Something that many people are doing with their time is baking bread with sourdough starters. In this comic, a joke is made that coronavirus is actually an organism which lives symbiotically with yeast in sourdough starters, and leads a parasitic lifestyle inside of humans, sourdough starter, and bread.

Parasites are organisms that usually cannot survive without the presence of another host organism. Many parasites have distinct cycles in order to propagate themselves, which are indirect in nature. For example, Toxoplasma gondii will first go through mice, affecting their nervous systems and making them extremely reckless, in order to get the system caught and eaten by a cat, which is the target host for the parasite. It has been said that the parasite may also infect other animals too, with unintended side effects... To this end, Randall proposes that the coronavirus is possibly one such parasite, using humans as a vector in order to infect yeast. Since many humans (bakers) work with yeast a lot, that is a convoluted, though not entirely impossible, way for the virus to spread to its host.

The word symbiont suggests symbiosis, which is not a parasitic relationship, but rather one of mutual benefit. This adds to the convulation, since although we usually regard symbiosis as good, as opposed to parasitism, the virus causes a lot of harm in another species to do it.

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

[Cueball stands in front of kitchen counter while holding a jar.]

Cueball: My sourdough starter is coming along nicely!

Theory: The coronavirus is a yeast symbiont with an ''extremely'' convoluted parasitic life cycle.

{{comic discussion}}

2296: Sourdough Starter

2020-04-20T21:24:36Z

162.158.74.85: /* Transcript */