explain xkcd - User contributions [en]

Talk:3182: Telescope Types

2026-01-13T12:12:07Z

627235:

no vampire jokes 🥀 ([[1791]]) [[User:TheTrainsKid|TheTrainsKid]] ([[User talk:TheTrainsKid|talk]]) 00:08, 18 December 2025 (UTC)

Got down some preliminary descriptions of each telescope type used [[Special:Contributions/185.132.133.218|185.132.133.218]] 01:44, 18 December 2025 (UTC)

insert that one mickey mouse meme with the caption "what a fucking narcissist"
[[User:Yaokuan ITB|Yaokuan ITB]] ([[User talk:Yaokuan ITB|talk]]) 02:33, 18 December 2025 (UTC)

abnormally low joke-to-real ratio for this format of comic! [[Special:Contributions/2601:241:8002:3E0:C0A2:9DA:ED39:D13F|2601:241:8002:3E0:C0A2:9DA:ED39:D13F]] 03:21, 18 December 2025 (UTC)
:I noticed that... I think this might've originally been 'look at all these cool telescope types', but then he realized he had to put some sort of joke somewhere. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 03:27, 18 December 2025 (UTC)

Can someone make a category for The Core (2003)? It's been mentioned often enough. [[Special:Contributions/83.245.251.49|83.245.251.49]] 09:22, 18 December 2025 (UTC)
:Can you list 4 more comics then I will make the category. I think that is about the limit for when to make a new category. I know there are a few more but is it only 2-3more? --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:00, 18 December 2025 (UTC)
::All I can think of is [[673: The Sun]]. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 15:09, 18 December 2025 (UTC)
:::Also mentioned in the title text of [[2858: Thanksgiving Arguments]]. --[[Special:Contributions/208.59.176.206|208.59.176.206]] 15:24, 18 December 2025 (UTC)
:: The [[:Category: The Core|The Core]] category was already created, nearly two years ago. This comic is the 7th reference --[[User:Deebster|Deebster]] ([[User talk:Deebster|talk]]) 23:54, 18 December 2025 (UTC)

> This would not […] end well for the drinker.

Would it though? ''Drinking'' elemental mercury, while not great on nutritional value, should be mostly safe (and I'm using that word quite loosely). The most danger would be while drinking and expelling it, when there's a danger of inhaling mercury vapors, right? --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 10:29, 18 December 2025 (UTC)
: ... Agreed. Elemental mercury is dangerous when inhaled, not when drinked. https://en.wikipedia.org/wiki/Mercury_poisoning [[Special:Contributions/109.81.171.81|109.81.171.81]] 21:12, 18 December 2025 (UTC)
:: (it's ''..when drunk.'') ;) [[Special:Contributions/88.65.244.212|88.65.244.212]] 00:42, 26 December 2025 (UTC)
It wouldn't take much work to make the "Real?" column all contain only "yes" [[Special:Contributions/136.32.133.124|136.32.133.124]] 12:05, 18 December 2025 (UTC)

As all others are refractors or reflectors, can cardboard tube be considered a diffractor? As it is the only thing that it does.--[[User:Trimutius|Trimutius]] ([[User talk:Trimutius|talk]]) 15:43, 18 December 2025 (UTC)
:Well, all the others do it as well. Even more so, as they have more objects in the light path. --[[Special:Contributions/88.65.244.212|88.65.244.212]] 00:42, 26 December 2025 (UTC)
> Children may sometimes use tubes [...]

It's not just children. I've seen "viewing tubes" in at least a couple of places, hard-mounted metal tubes that point at particular points of interest. I'm not finding any good references, but here's a photo showing some at the top of a nearby mountain: https://maps.app.goo.gl/wwnYJ1zEQEXzjyJS8 [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 18:07, 18 December 2025 (UTC)

Is the joke with "Geological" that it's looking at something 'far away' from actual Geology? {{unsigned ip|64.203.66.182|17:14, 19 December 2025}}

I flunked out of freshman physics, so apologies in advance if this is very stupid, but looking at the designs, and the “reflector” and “refractor” columns, I was wondering if it might make sense to combine the two, have a telescope with a refracting lens at one end and a concave mirror at the other (and presumably a secondary mirror) that would allow for a shorter overall length tube for the telescope. [[User:John|John]] ([[User talk:John|talk]]) 04:42, 27 December 2025 (UTC)
:Various designs mix lenses and mirrors (if only at the eyepiece end, as a final adjustable focusing element). But very large lenses have their own issues, e.g.:
:* they tend to produce spectral abberations that require careful relensing to mitigate;
:* the lens-material will absorb some small amounts of light during passage, especially for rays passing through the considerably thicker bits (whether concave, convex or meniscus) ...any absorption by a chosen material of mirror surface is constant;
:*shaping/polishing has to be done equally well on both sides, and can't easily be re-additive of material (only continually grinding it down, as needed);
:* it can't be physically supported (or even flexed, to adjust) all across one side, like a mirror;
:* necessarily huge chunks of optically-refractive material are ''heavy'', compared to many kinds of similarly proportioned mirrors;
:...and a few other issues that you might imagine. You can mitigate/mix these in all kinds of ways, but "a huge primary mirror" at the back end often has various advantages over "a huge (pre-?)primary lens" at the front end, varying a bit depending upon actual intended configuration and use. [[Special:Contributions/82.132.239.191|82.132.239.191]] 15:30, 27 December 2025 (UTC)
> One important bit about huge lenses: convex lenses (which you would need for a really big primary reflector) would be *very* thick which causes all kinds of problems when you cast them and then cool them down. The resulting stress makes it impossible to manufacture good lenses above a certain size. There are really big lenses, e.g. for lighthouses but those don't need good image quality so Fresnel lenses can be used to make them much thinner. Good quality composite lenses are at the very least much harder (not confident enough to say "impossible") to produce than composite mirrors. [[User:627235|627235]] ([[User talk:627235|talk]]) 12:12, 13 January 2026 (UTC)

Talk:3179: Fishing

2025-12-11T11:42:25Z

627235:

The tug on a fishing line would be measured in newtons, not kilograms. [[Special:Contributions/76.187.17.7|76.187.17.7]] 04:30, 11 December 2025 (UTC)
YAY BERET GUY![[User:Mathmaster|Mathmaster]] ([[User talk:Mathmaster|talk]])
* It's at least a C+ [[Special:Contributions/65.35.15.18|65.35.15.18]] 05:12, 11 December 2025 (UTC)
Yes, but he is not measuring the force, he is measuring the "weight" (mass) of the thing he thinks he hooked. (e.g. a 5 lb fish)[[Special:Contributions/2603:8000:5E00:2913:EE02:2D56:E960:2CDE|2603:8000:5E00:2913:EE02:2D56:E960:2CDE]] 05:21, 11 December 2025 (UTC)

Beret Guy's estimate is, of course, absurd (or it would be for anyone else). His lifting capacity, the breaking points of his line and rod, the buoyancy of his boat and the force to break loose an individual piece of rock (the lowest of which would mark the upper bounds for his estimate) are (many) orders of magnitude lower than the force required to haul a 10^24 kg catch into the boat [citation needed, I guess] [[User:627235|627235]] ([[User talk:627235|talk]]) 11:42, 11 December 2025 (UTC)

Talk:3179: Fishing

2025-12-11T11:41:54Z

627235:

The tug on a fishing line would be measured in newtons, not kilograms. [[Special:Contributions/76.187.17.7|76.187.17.7]] 04:30, 11 December 2025 (UTC)
YAY BERET GUY![[User:Mathmaster|Mathmaster]] ([[User talk:Mathmaster|talk]])
* It's at least a C+ [[Special:Contributions/65.35.15.18|65.35.15.18]] 05:12, 11 December 2025 (UTC)
Yes, but he is not measuring the force, he is measuring the "weight" (mass) of the thing he thinks he hooked. (e.g. a 5 lb fish)[[Special:Contributions/2603:8000:5E00:2913:EE02:2D56:E960:2CDE|2603:8000:5E00:2913:EE02:2D56:E960:2CDE]] 05:21, 11 December 2025 (UTC)
Beret Guy's estimate is, of course, absurd (or it would be for anyone else). His lifting capacity, the breaking points of his line and rod, the buoyancy of his boat and the force to break loose an individual piece of rock (the lowest of which would mark the upper bounds for his estimate) are (many) orders of magnitude lower than the force required to haul a 10^24 kg catch into the boat [citation needed, I guess] [[User:627235|627235]] ([[User talk:627235|talk]]) 11:41, 11 December 2025 (UTC)

Talk:2831: xkcd Phone Flip

2023-09-21T11:01:11Z

627235:

this is my first time editing, did i do well? [[Special:Contributions/172.70.134.202|172.70.134.202]] 21:39, 20 September 2023 (UTC)
:Decent enough, assuming you were the one giving the reference to the Z-series. But it'll be expanded, improved and reformatted a lot, I predict. I put in my own (intended) first-edit, but clearly there's you (and possibly A.N. Other) already adding their own thoughts. (Which I am counting on, rather than trying to write it all in one go all by myself... I'll wait for it to settle down and ''then'' see if there are various tweaks I'll want try on whatever form it becomes.) [[Special:Contributions/172.70.90.7|172.70.90.7]] 21:50, 20 September 2023 (UTC)
:The other person was me, but I think there's someone else as well reformatting and rewriting things.--[[Special:Contributions/172.68.34.38|172.68.34.38]] 23:57, 20 September 2023 (UTC)

So, what is the meaning of "flip" here? [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 22:07, 20 September 2023 (UTC)
:It's a reference to the Samsung Galaxy line of folding smartphones, which is marketed as 'Galaxy Z Flip' phones. While there had been double-screened smartphones in the past, Samsung was able to figure out some way to have the actual screen flex and fold in the middle so that when it's closed the primary screen is protected, but when opened up the user sees a single screen without a hinge in the middle. The current model (the 'Z Flip 5') is the sixth iteration of the device since it was originally introduced in China in 2019. [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]]) 22:36, 20 September 2023 (UTC)

:I think it's just part of the whole marketroid feeling these are supposed to have. It's part of the name and the [alleged] "marketing" department, as is typical, came up with something extremely dumb and useless. See: [https://serverfault.com/questions/117799/which-version-of-sunos SunOS vs Solaris] [[Special:Contributions/162.158.197.132|162.158.197.132]] 22:32, 20 September 2023 (UTC)

Anybody else think the main sequence battery is a fusion cell that is also the chemical flashlight and full spectrum backlight that necessitates the SPF 15 coating? [[Special:Contributions/172.71.151.83|172.71.151.83]] 22:36, 20 September 2023 (UTC)
:I'm thinking it's a reference to the Cyalume lightsticks which need to be bent, which shatters a small glass vial inside and releases a hydrogen peroxide solution into a second solution of an oxalate ester and electron-rich dye contained within the outer plastic shell. The resulting chemiluminescent reaction creates visible light. [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]]) 22:42, 20 September 2023 (UTC)
:I assumed main sequence refers to stellar evolution in astronomy. {{w|Main sequence}} These stars have a relatively long life, matching the description. The SPF 15 coating and full spectrum would also make sense. However I am not sure that description as a chemical flashlight would follow appropriate. The primary energy generation would be nuclear (fusion). It has been long enough since I took astronomy I don't remember all the details of how the energy is converted into light, and whether that would ultimately be considered a chemical, thermal, or nuclear process (or combination thereof). [[Special:Contributions/172.69.22.152|172.69.22.152]] 00:20, 21 September 2023 (UTC)

Arch support may also refer to the Linux distro [[Special:Contributions/162.158.110.237|162.158.110.237]] 08:42, 21 September 2023 (UTC)

I initially misread the title text as being a ''Thanos'' partnership. In which case, presumably inadvertently touching the button could wipe out half the population of the universe.[[Special:Contributions/172.71.242.77|172.71.242.77]] 10:25, 21 September 2023 (UTC)
:Can destroy mountains with one click, but not half the population [[Special:Contributions/172.70.90.220|172.70.90.220]] 10:32, 21 September 2023 (UTC)

The breaking the glass might refer to “ Break glass (which draws its name from breaking the glass to pull a fire alarm) refers to a quick means for a person who does not have access privileges to certain information to gain access when necessary.”

With a chemical flashlight, I assume the free refills might actually come in handy (though it doesn't say there is a chemical flashlight and with the flip form, bending might just refer to some mechanical switch activating the flashlight - or considering the possibly stellar power source, it just removes shielding). [[User:627235|627235]] ([[User talk:627235|talk]]) 11:01, 21 September 2023 (UTC)

Talk:2801: Contact Merge

2023-07-13T09:18:37Z

627235:

Same person.
:All three of them...[[User:Tier666|Tier666]] ([[User talk:Tier666|talk]]) 08:32, 13 July 2023 (UTC)

Why is he only using John's first name when talking about him, as if Surf King should know who that is, when it's clear they've "never met"?
Shouldn't it be: My phone keeps wanting to merge you with my friend John Smith? [[Special:Contributions/172.71.178.30|172.71.178.30]] 07:46, 13 July 2023 (UTC)
: Because he's spectacularly unaware, and assumes that everyone that he 'knows' also know each other?[[Special:Contributions/172.70.90.110|172.70.90.110]] 08:16, 13 July 2023 (UTC)

This is the first XKCD in a long time that I have absolutely no understanding of. Who is Surf King? Even Google doesn't bring anything up (I assumed it was someone well known in the USA but unknown to the few of us that don't live in that country). Please someone post an explanation soon! [[Special:Contributions/162.158.74.46|162.158.74.46]] 09:06, 13 July 2023 (UTC)
:No one in particular. Just someone named John. The short explanation is that his phone figured out that "Surf King" and "John" are the same person/contact while Cueball remains ignorant. [[User:627235|627235]] ([[User talk:627235|talk]]) 09:18, 13 July 2023 (UTC)

Talk:2798: Room Temperature

2023-07-06T11:23:20Z

627235:

Isn't there actually quite a lot of funding available for uncontrolled hot fusion? https://www.icanw.org/squandered_2021_global_nuclear_weapons_spending_report ;) [[Special:Contributions/162.158.38.32|162.158.38.32]] 23:29, 5 July 2023 (UTC)

Note that '''controlled''' hot fusion (e. g. a functioning Tokamak) would also be really valuable. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 02:17, 6 July 2023 (UTC)

Someone explain why superconductors are a big deal

Arguably the temperature has to change for a semiconductor to work. For it to work at room temperature alone would be pure magic.

A note about the fusion connection. In recent years, there have been breakthroughs in high temperature superconductors, which theoretically would allow to build controlled hot fusion reactors at a much smaller scale (because they can create much higher magnetic fields). There are seveal private companies that attempt to do that, most notably CFS with their [https://en.wikipedia.org/wiki/SPARC_(tokamak) SPARC Tokamak]. I think this is what is being referenced here. --[[Special:Contributions/172.71.160.54|172.71.160.54]] 08:16, 6 July 2023 (UTC)
:Maybe you could add that yourself? I wrote the current explanation but actually have no expertise in that area, and also I'm not sure how to incorporate that into the current flow of the explanation. [[User:Rebekka|Rebekka]] ([[User talk:Rebekka|talk]]) 09:01, 6 July 2023 (UTC)

:I assumed the title text (which says "demonstrates" and not "produces" uncontrolled fusion) - could be as simple as a device proving the sun is a fusion reaction --[[User:Nico|Nico]] ([[User talk:Nico|talk]]) 11:49, 6 July 2023 (UTC)

As I understand it, "cold fusion" doesn't necessarily mean room temperature. That would actually be quite useless. Cold fusion could mean anything from "doesn't need millions of degrees" to "cool enough to directly hook up to boilers to power steam turbines" (and potentially a lower pressure requirement). The "room temperature" thing is mostly due to bad "science" and frauds (though it is still questionable if higher temperature cold fusion can be a thing, too). It's easier to cheaply make an alleged "cold fusion device" if you don't have to heat it up to or contain it at up to several thousand degrees. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:23, 6 July 2023 (UTC)

Talk:2674: Everyday Carry

2022-09-20T13:04:24Z

627235:

Randall speaks: https://www.npr.org/2022/09/18/1123689628/randall-munroes-what-if-2-answers-the-absurd-science-questions-you-didnt-know-yo [[Special:Contributions/172.70.126.245|172.70.126.245]] 08:47, 20 September 2022 (UTC)

My EDC: Swiss Army Knife, Kershaw Leek, Kershaw Chive, SOG Multi Tool, Quarters for Aldi, Visa card.[[Special:Contributions/172.70.131.44|172.70.131.44]] 08:54, 20 September 2022 (UTC)

Hypothetical: Wandering around the jungle, as you do, you find an old, overgrown airstrip with abandoned planes strewn across its overgrown runway. Just then, several lost school parties show up out of nowhere, having miraculously survived various mid-sized airplane emergency landings in the vicinity. With one of the crowd's mobile phones (not you, because you haven't had a spare pocket for one since 2014, but you ''do'' have a USB recharge facility built into one of your many torches), and sufficient signal, the authorities are alerted to your exact position, and can send an airliner to rescue you all, just so long as the runway is cleared and you can set up enough lights to assist with their approach and landing. – Hopefully you hadn't a day or two ago had a wheel come off your cart (because of the jungle vines snagging at it!) and found that the screw that had come loose was of a size and configuration that ''none'' of your gadgets could actually handle. I mean, you had a darned star-penta-posix (with a hole in the end) for every other size from 1mm up to 35mm ''except this exact one''..! Amirite? [[Special:Contributions/141.101.107.159|141.101.107.159]] 08:58, 20 September 2022 (UTC)

Turns out, when the time you prepared for comes, you're still really unprepared. It's not just that you'll still only have two hands and will be missing that one "No need, you can find it anywhere"-Part. You also will have no idea that the time has come (after 213 false alarms) or which of the many, many things you prepared for has actually occurred. [[User:627235|627235]] ([[User talk:627235|talk]]) 13:04, 20 September 2022 (UTC)

Talk:2650: Deepfakes

2022-07-26T10:52:47Z

627235:

Is it worth mentioning that this comic is merely sincere discussion, without (please correct me if I'm wrong) any sort of a joke or irony? The closest it gets is hyperbole in the title text. I know it's not unique in this respect, but it does seem to be different than other such comics because it seems like it might have a joke, given the obscurity of the Ea-nasir reference. If our job is truly to explain, should we let people coming here to figure out the humor know there isn't any? [[Special:Contributions/172.70.214.95|172.70.214.95]] 06:48, 26 July 2022 (UTC)
:Did but [https://www.explainxkcd.com/wiki/index.php?title=2650:_Deepfakes&diff=290833&oldid=290831 reverted,] other opinions? [[Special:Contributions/172.70.210.145|172.70.210.145]] 08:39, 26 July 2022 (UTC)
::I have reverted and added more. I just [[609: Tab Explosion|used a long time]] on [[214: The Problem with Wikipedia|wiki]] because of those two tidbits of info that has nothing to do with Deepfakes... :-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:49, 26 July 2022 (UTC)
:::Snap... I (not the above IP) was also on a long wikiwalk. (Did you know that the map of the copper-fraudster's house is one of the top 200 diagrams that is considered important to resubmit in vectorised format? Amongst many colour-model diagrams and how much money goes to which US surveillance and intelligence agencies. :P ) I really ought to do something important, instead. Like vectorise some diagrams. Hand me my spline-wrench and my gradient-planer! [[Special:Contributions/172.70.86.34|172.70.86.34]] 10:17, 26 July 2022 (UTC)
:Not sure about there being no joke. White Hat realizing that you can write untrue things (most common types known as lies and fiction), that people have done it for a long time and calling it the new buzzword ("text deepfakes") certainly was funny to me. Cueball's somewhat obscure reference (which you don't really need to know to understand) drives home the point.[[User:627235|627235]] ([[User talk:627235|talk]]) 10:52, 26 July 2022 (UTC)

Talk:2641: Mouse Turbines

2022-07-07T12:30:30Z

627235:

Is anybody going to try to calculate the amount of power such a turbine could collect? -- [[User:Dtgriscom|Dtgriscom]] ([[User talk:Dtgriscom|talk]]) 19:24, 4 July 2022 (UTC)
:Good idea; what should we use for an estimate of the geometry for https://www.omnicalculator.com/ecology/wind-turbine ? The final panel makes it look like the blade diameter is about twice the size of a fist. [https://www.sciencedirect.com/science/article/pii/S2215098616300830] says "exhaled air velocity varies from 2.2 m/s to 9.9 m/s (5.66 ± 1.57 m/s, mean ± SD) and exhalation time varies from 2.10 s to 8.21 s (4.42 ± 1.73s, mean ± SD)."
:I guessed 10 cm radius and used that mean breath speed. I should have used the top 9.9 m/s though, shouldn't I? [[Special:Contributions/172.70.214.185|172.70.214.185]] 20:56, 4 July 2022 (UTC)
:After a closer look at that article, the mean is more appropriate. [[Special:Contributions/172.70.206.95|172.70.206.95]] 21:19, 4 July 2022 (UTC)
: I'm not sure how you'd judge that it's twice the size of a fist, given that stick people don't really have fists. I would assume that they're meant to be about the same size as dandelion heads - so about 3 or 4 cm (unless US dandelions are bigger than UK ones). They certainly look about that size in the second panel. You'd also need to factor in problems of interference, given the 'planting density' of these turbines, and the sub-optimal location surrounded by grasses, etc. [[Special:Contributions/172.70.86.44|172.70.86.44]] 08:08, 6 July 2022 (UTC)
::The rotating diameter is shown as about a third the height of Beret Guy's head, so it's definitely not 20 cm. [[Special:Contributions/172.70.210.125|172.70.210.125]] 02:47, 7 July 2022 (UTC)

Although these miniscule wind turbines don't generate much power, mice probably don't need much. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 21:17, 4 July 2022 (UTC)
:That's certainly a fair point. How much power would a mouse-sized fridge need? [[Special:Contributions/172.70.206.95|172.70.206.95]] 21:23, 4 July 2022 (UTC)
::Mice consume a lot more food per body weight (especially for body heat because heat transfer scales with surface area, not mass/volume) than humans. Mouse-sized fridge efficiency would also be poor both because of the same size issue and reduced room for insulation. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:13, 5 July 2022 (UTC)
::A 480 ml insulin travel fridge uses 5 watts on a 3% duty cycle depending on the ambient temperature and how much it's loaded, so that's in the realm of possibility, and seems large enough. I used to feed lab mice about 5 grams of Purina Lab Rodent Chow daily, which was maybe 8ml volume, but it doesn't need to be refrigerated. Googling suggests field mice can get all the water they need from a diet of seeds. It seems to me that if mice could use electricity, they'd need it more in the winter than the summer. [[Special:Contributions/172.70.211.52|172.70.211.52]] 22:01, 5 July 2022 (UTC)

Someone please check my mouse energy needs math and assumptions. I made a couple misplaced decimal mistakes getting to where it is now, and I'm going to have another beer. [[Special:Contributions/172.70.211.52|172.70.211.52]] 22:17, 4 July 2022 (UTC)
:Not sure about numbers but some (if not most) energy requirements scale by surface area ({{w|Square–cube law}} or other measurements. There are also efficiency issues with at least lots of human-made miniature machines. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:13, 5 July 2022 (UTC)
::What energy requirements scale by surface area? Pumping water, cooking, and refrigerating scales by mass. Converting footcandles to lumens depends on area, but that doesn't account for much lower mouse ceilings. [[Special:Contributions/172.69.34.6|172.69.34.6]] 22:27, 5 July 2022 (UTC)
:::Heat exchange is kind of a biggie a lot of things depend on. [[User:627235|627235]] ([[User talk:627235|talk]]) 12:30, 7 July 2022 (UTC)

I'm confused by the statement that smaller turbines are less "efficient". There's nothing about efficiency at that link. [[Special:Contributions/172.70.114.43|172.70.114.43]] 22:33, 4 July 2022 (UTC)
:The graph shows the ratio between size and output has risen from about half to 85%. What is a better term for this? I'm pretty sure one of the multiple definitions of efficiency is technically correct, but it can never hurt explaining better. [[Special:Contributions/172.69.33.113|172.69.33.113]] 22:42, 4 July 2022 (UTC)
:Changed to "relative power output" but I'm not sure that captures the idea very well either. [[Special:Contributions/172.69.33.113|172.69.33.113]] 22:44, 4 July 2022 (UTC)

Well wind turbines may not scale down ideally but still better than nuclear power plants. I suspect those have fixed minimal size and it's pretty big. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:32, 4 July 2022 (UTC)

:Apparently nuclear power can be [https://technology.nasa.gov/patent/LAR-TOPS-294 "as small as a button cell"] but mice are vulnerable to radioactive hazards, and haven't solved the waste disposal problem. [[Special:Contributions/172.70.214.185|172.70.214.185]] 23:45, 4 July 2022 (UTC)

::Batteries based on radioactive decay (such as RTGs, thermionic cells, betavoltaic cells) are not nuclear power plants. That term specifically refers to power plants based on nuclear fission reactors. [[User:Zmatt|Zmatt]] ([[User talk:Zmatt|talk]]) 11:38, 6 July 2022 (UTC)

Isn't the power output of a solar panel directly dependent on its size (and wether it's covered with snow, angle to the sun, clouds? And prolly something I'll think of as soon as I hit save).[[Special:Contributions/172.70.131.106|172.70.131.106]] 23:55, 4 July 2022 (UTC)
:Yes, but the power per size doesn't increase with size like wind turbines do. [[Special:Contributions/172.69.33.63|172.69.33.63]] 00:01, 5 July 2022 (UTC)

What is the smallest Tesla Powerwall available for purchase? [[Special:Contributions/172.70.206.163|172.70.206.163]] 02:00, 5 July 2022 (UTC)
:You probably want an {{w|18650}} or similar cell, which are [https://www.youtube.com/watch?v=PsJMj7FtroY frequently discarded on the street] and thus easily obtainable by mice. [[Special:Contributions/172.69.33.171|172.69.33.171]] 03:02, 5 July 2022 (UTC)

Why doesn't pico hydro have the same problems scaling down as wind? They're both fluid turbines. [[Special:Contributions/172.70.214.185|172.70.214.185]] 02:24, 5 July 2022 (UTC)
:For the same reasons that small fans have several vanes, but large wind turbines have only three. I remember reading something about the physics (it's a laminar versus turbulent thing) but I can't remember the details now. I'll update here if I can find it. [[Special:Contributions/172.70.210.125|172.70.210.125]] 03:08, 5 July 2022 (UTC)
:[https://www.sciencefocus.com/science/why-do-wind-turbines-have-three-blades/ Here's part of it,] but doesn't really get to the heart of the matter. [[Special:Contributions/172.70.210.125|172.70.210.125]] 03:10, 5 July 2022 (UTC)
:I think it has more to do with the relative magnitude of drag in gases instead of liquids. I don't have a good source though. [[Special:Contributions/172.70.211.36|172.70.211.36]] 03:21, 5 July 2022 (UTC)
::Turbine efficiency (especially for very small turbines) mostly depends on pressure differential and mass throughput. Water has three orders of magnitude higher density than air. Also, even with just a meter of water column, water offers a 10 kPa pressure differential while you only rarely get that much of a pressure differential in air (at the same height) even between areas of high and low pressure usually at least dozens (and commonly hundreds) of miles apart (there may be exceptions for things like tornadoes but good luck using their wind power), certainly not between the high and low pressure sides of a turbine. Efficiency in practice mostly depends on moved mass (of turbine blades, etc) compared to moved medium (water or air), friction (mount, generator, maybe a gearbox) compared to total power input and (if electricity is desired) generator efficiency which itself depends on generator size and rotation speed (hence the need for a gearbox). For a very small turbine, all those things would need to be extremely light as well. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:13, 5 July 2022 (UTC)

Who is Beret Guy telling to make a wish - Megan or the mice? -- [[User:Ken g6|Ken g6]] ([[User talk:Ken g6|talk]]) 04:48, 5 July 2022 (UTC)

[https://www.cornel1801.com/animated/Secret-of-NIMH-1982/pictures/64.jpg I must tell you about NIMH.] - [[Special:Contributions/172.70.254.81|172.70.254.81]] 16:13, 5 July 2022 (UTC)

Sometimes the explanation is funnier than the comic. [[Special:Contributions/172.68.133.159|172.68.133.159]] 03:28, 6 July 2022 (UTC)

Uh, what happened to the image!? Does anyone know how to fix it? [[Special:Contributions/172.70.110.65|172.70.110.65]] 20:22, 6 July 2022 (UTC)

Talk:2642: Meta-Alternating Current

2022-07-07T12:26:40Z

627235:

And today, we are reminded that [[Randall]] used to be a physicist (or at least has a physics degree). Not worth mentioning in the article, but while inverters can't reverse each other, transformers can. (Has Randall done the transformer/Transformer pun yet as an excuse to mock the movies?) [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 11:10, 7 July 2022 (UTC)
: I haven't picked up the physics reference yet. I see electrical engineering here. Randall strikes me as somebody who would study physics given the opportunit, though. It's notable that this webcomic started while Randall was in college, if I recall right. [[Special:Contributions/172.70.230.75|172.70.230.75]] 11:58, 7 July 2022 (UTC)

Long distance links, especially those between separate unsynchronized grids, use high voltage DC. There is a 2,000-mile link in China running at 1 MV. [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]]) 11:32, 7 July 2022 (UTC)
:That's because at great distances, relatively high frequency AC loses a lot of ("active" = actually useful) power as ... reactive power, I think (didn't learn the terminology in English, unit seems right though). A typical grid has a lot of generators and load. A long distance connection results in a phase shift according to the transmission time (speed of light in medium x distance) in about the order of magnitude of the AC period (usually somewhere between 1/10 to 1/60 seconds) wastes a portion equal to the sine of the phase shift angle (up to 90° = all of it) as reactive power. DC isn't quite as easy to use but on long distances there is no power loss to reactive power. [[User:627235|627235]] ([[User talk:627235|talk]]) 12:25, 7 July 2022 (UTC)

Let's face it, the thing should be called an alternator. Of course that name's taken as a redundant word for (electrical) generator. [[User:627235|627235]] ([[User talk:627235|talk]]) 12:26, 7 July 2022 (UTC)

Talk:2642: Meta-Alternating Current

2022-07-07T12:25:41Z

627235:

Talk:2641: Mouse Turbines

2022-07-05T11:13:16Z

627235:

Is anybody going to try to calculate the amount of power such a turbine could collect? -- [[User:Dtgriscom|Dtgriscom]] ([[User talk:Dtgriscom|talk]]) 19:24, 4 July 2022 (UTC)
:Good idea; what should we use for an estimate of the geometry for https://www.omnicalculator.com/ecology/wind-turbine ? The final panel makes it look like the blade diameter is about twice the size of a fist. [https://www.sciencedirect.com/science/article/pii/S2215098616300830] says "exhaled air velocity varies from 2.2 m/s to 9.9 m/s (5.66 ± 1.57 m/s, mean ± SD) and exhalation time varies from 2.10 s to 8.21 s (4.42 ± 1.73s, mean ± SD)."
:I guessed 10 cm radius and used that mean breath speed. I should have used the top 9.9 m/s though, shouldn't I? [[Special:Contributions/172.70.214.185|172.70.214.185]] 20:56, 4 July 2022 (UTC)
:After a closer look at that article, the mean is more appropriate. [[Special:Contributions/172.70.206.95|172.70.206.95]] 21:19, 4 July 2022 (UTC)

Although these miniscule wind turbines don't generate much power, mice probably don't need much. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 21:17, 4 July 2022 (UTC)
:That's certainly a fair point. How much power would a mouse-sized fridge need? [[Special:Contributions/172.70.206.95|172.70.206.95]] 21:23, 4 July 2022 (UTC)
::Mice consume a lot more food per body weight (especially for body heat because heat transfer scales with surface area, not mass/volume) than humans. Mouse-sized fridge efficiency would also be poor both because of the same size issue and reduced room for insulation. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:13, 5 July 2022 (UTC)

Someone please check my mouse energy needs math and assumptions. I made a couple misplaced decimal mistakes getting to where it is now, and I'm going to have another beer. [[Special:Contributions/172.70.211.52|172.70.211.52]] 22:17, 4 July 2022 (UTC)
:Not sure about numbers but some (if not most) energy requirements scale by surface area ({{w|Square–cube law}} or other measurements. There are also efficiency issues with at least lots of human-made miniature machines. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:13, 5 July 2022 (UTC)

I'm confused by the statement that smaller turbines are less "efficient". There's nothing about efficiency at that link. [[Special:Contributions/172.70.114.43|172.70.114.43]] 22:33, 4 July 2022 (UTC)
:The graph shows the ratio between size and output has risen from about half to 85%. What is a better term for this? I'm pretty sure one of the multiple definitions of efficiency is technically correct, but it can never hurt explaining better. [[Special:Contributions/172.69.33.113|172.69.33.113]] 22:42, 4 July 2022 (UTC)
:Changed to "relative power output" but I'm not sure that captures the idea very well either. [[Special:Contributions/172.69.33.113|172.69.33.113]] 22:44, 4 July 2022 (UTC)

Well wind turbines may not scale down ideally but still better than nuclear power plants. I suspect those have fixed minimal size and it's pretty big. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:32, 4 July 2022 (UTC)

:Apparently nuclear power can be [https://technology.nasa.gov/patent/LAR-TOPS-294 "as small as a button cell"] but mice are vulnerable to radioactive hazards, and haven't solved the waste disposal problem. [[Special:Contributions/172.70.214.185|172.70.214.185]] 23:45, 4 July 2022 (UTC)

Isn't the power output of a solar panel directly dependent on its size (and wether it's covered with snow, angle to the sun, clouds? And prolly something I'll think of as soon as I hit save).[[Special:Contributions/172.70.131.106|172.70.131.106]] 23:55, 4 July 2022 (UTC)
:Yes, but the power per size doesn't increase with size like wind turbines do. [[Special:Contributions/172.69.33.63|172.69.33.63]] 00:01, 5 July 2022 (UTC)

What is the smallest Tesla Powerwall available for purchase? [[Special:Contributions/172.70.206.163|172.70.206.163]] 02:00, 5 July 2022 (UTC)
:You probably want an {{w|18650}} or similar cell, which are [https://www.youtube.com/watch?v=PsJMj7FtroY frequently discarded on the street] and thus easily obtainable by mice. [[Special:Contributions/172.69.33.171|172.69.33.171]] 03:02, 5 July 2022 (UTC)

Why doesn't pico hydro have the same problems scaling down as wind? They're both fluid turbines. [[Special:Contributions/172.70.214.185|172.70.214.185]] 02:24, 5 July 2022 (UTC)
:For the same reasons that small fans have several vanes, but large wind turbines have only three. I remember reading something about the physics (it's a laminar versus turbulent thing) but I can't remember the details now. I'll update here if I can find it. [[Special:Contributions/172.70.210.125|172.70.210.125]] 03:08, 5 July 2022 (UTC)
:[https://www.sciencefocus.com/science/why-do-wind-turbines-have-three-blades/ Here's part of it,] but doesn't really get to the heart of the matter. [[Special:Contributions/172.70.210.125|172.70.210.125]] 03:10, 5 July 2022 (UTC)
:I think it has more to do with the relative magnitude of drag in gases instead of liquids. I don't have a good source though. [[Special:Contributions/172.70.211.36|172.70.211.36]] 03:21, 5 July 2022 (UTC)
::Turbine efficiency (especially for very small turbines) mostly depends on pressure differential and mass throughput. Water has three orders of magnitude higher density than air. Also, even with just a meter of water column, water offers a 10 kPa pressure differential while you only rarely get that much of a pressure differential in air (at the same height) even between areas of high and low pressure usually at least dozens (and commonly hundreds) of miles apart (there may be exceptions for things like tornadoes but good luck using their wind power), certainly not between the high and low pressure sides of a turbine. Efficiency in practice mostly depends on moved mass (of turbine blades, etc) compared to moved medium (water or air), friction (mount, generator, maybe a gearbox) compared to total power input and (if electricity is desired) generator efficiency which itself depends on generator size and rotation speed (hence the need for a gearbox). For a very small turbine, all those things would need to be extremely light as well. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:13, 5 July 2022 (UTC)

Who is Beret Guy telling to make a wish - Megan or the mice? -- [[User:Ken g6|Ken g6]] ([[User talk:Ken g6|talk]]) 04:48, 5 July 2022 (UTC)

Talk:2639: Periodic Table Changes

2022-06-30T11:32:15Z

627235:

The format of this comic appears most similar to https://xkcd.com/1902/. Is it worth noting that, in some representations of the periodic table (see https://ptable.com/#Electrons), Helium is indeed placed in the second column next to Hydrogen? [[User:Dextrous Fred|Dextrous Fred]] ([[User talk:Dextrous Fred|talk]]) 21:54, 29 June 2022 (UTC)

Nice. I'm doing the old "what elements have been obscured/overwritten" thing, after far too long since actually memorising the Periodic Table that was on my school's lab wall... But, hey! Where has Hahnium got to? [[Special:Contributions/172.70.162.77|172.70.162.77]] 22:25, 29 June 2022 (UTC)

I wonder why he kept the Latinate abbreviations for Antimony and Mercury. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 23:17, 29 June 2022 (UTC)

The changes by Asdf seem like they mostly belong in the Transcript, not Explanation.
:I moved some of my lengthy descriptions from Explanation to Transcript, hopefully this helps. Sorry if I caused inconvenience. -[[User:Asdf|Asdf]] ([[User talk:Asdf|talk]]) 00:00, 30 June 2022 (UTC)

Laaaaame! Not revolutionary enough! Why not simply get rid of all these historical accidents and indicate any element by its nuclear charge? [[Special:Contributions/172.71.102.117|172.71.102.117]] 07:05, 30 June 2022 (UTC)

Anyone else find it ironic that the new kinds of carbon are indexed with Roman numerals on the same comic where it says "this isn't Ancient Rome"? [[Special:Contributions/162.158.38.27|162.158.38.27]] 07:18, 30 June 2022 (UTC)

For the language nerds among us, "I" for iron wouldn't work at all well in Dutch. Although the element is typewritten "ijzer", the first two characters are treated as a single letter and are capitalised together (IJzer). It's pronounced EI and is listed in the Dutch alphabet alongside (or sometimes even instead of) Y.[[Special:Contributions/162.158.233.55|162.158.233.55]] 08:37, 30 June 2022 (UTC)
:Clearly there isn't much consideration given to any other language than English. The "annoying W" is for Wolfram or something close in many languages, "Na" is Natrium, "K" is Kalium - frankly, Mr. Munroe just uses the wrong language. Then again, "Fe" really is annoying, of course it should be "Ei" for Eisen ... [[User:627235|627235]] ([[User talk:627235|talk]]) 11:32, 30 June 2022 (UTC)

This feels more like a parallel to corporate reorganisations that are based on idealised concepts of how an organisation 'should' work than on the practicalities of what people actually do, than it does to economic plans. Particularly with the reference to training elements to adapt to their new positions. [[Special:Contributions/172.70.90.173|172.70.90.173]] 10:47, 30 June 2022 (UTC)

Talk:2636: What If? 2 Countdown

2022-06-23T14:52:56Z

627235:

I've started the table to explain all the calendar entries. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 00:19, 23 June 2022 (UTC)

Is the dog minutes calculation backwards? 777,777 dog minutes should be 777,777 x 7 human minutes, which is over 10 years. Randall seems to be dividing instead of multiplying. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 00:36, 23 June 2022 (UTC)
: No - 1 human year = 7 dog years; 1 dog year = 1/7 human year; 1 dog minute = 1/7 human minute; 777,777 dog minutes = 111,111 human minutes = 77 days, 3 hours, 51 minutes. [[Special:Contributions/172.70.90.173|172.70.90.173]] 11:32, 23 June 2022 (UTC)

First entry is probably mistake by Randall, e^pi would give value of 84.5 [[Special:Contributions/162.158.203.38|162.158.203.38]] 11:57, 23 June 2022 (UTC)
: That would be too high, though. 82.xxx days (from midnight at the start of launch day) would fall within the 83rd day before it (Jun 22). 84.5 would fall within the 85th (Jun 20). [[Special:Contributions/172.70.91.58|172.70.91.58]] 12:15, 23 June 2022 (UTC)

Not sure if this is even worth mentioning, but he forgot the box around the date number in the top corner for August 29th. [[Special:Contributions/172.70.126.151|172.70.126.151]] 12:49, 23 June 2022 (UTC)

Fyi, used wolfram alpha for most of the calculations. Seems to be able to handle anything I throw at it (nanocenturies, megaseconds, fortnights etc) [[User:Aditya95sriram|Aditya95sriram]] ([[User talk:Aditya95sriram|talk]]) 13:02, 23 June 2022 (UTC)aditya95sriram

Some of the calculations done forward (assuming what Randall means as a Generation, for example) might be best done as "to get this many days, what does Randall think ilhe is starting from. And see if 365, 365.25 or even 365.24 days per year works best, where relevent. Although I think in many cases you'll find the fractional differences negligable, when done right. (I'm also a bit surprised by the off-by-one errors in days-to-go and derived value, but I suspect that this is because of [[2585: Rounding|assymetric rounding effects]] that would be revealed by running the assumption backwards and seeing how different (or otherwise) the decimals actually are.) [[Special:Contributions/172.70.85.211|172.70.85.211]] 13:32, 23 June 2022 (UTC)

Not sure about most numbers but at least the order of magnitude seemed plausible. I can't quite find a proper way to read August 28th. π^π^π is roughly 80662.666 - if you read πcoseconds as "picoseconds", that's way less than a second. I have no idea what π * coseconds are supposed to be. π * c * o * seconds doesn't look much better - there are values associated with "c" (speed of light, for example) but I have no idea what "o" could be and certainly nothing that would make this a unit of time. Sixteen days would be 1,353,600,000,000,000,000 ps (picoseconds). π^π^π^π is three orders of magnitude too small, π^π^π^π^π is many orders of magnitude too big a number. Am I missing something (really obvious, maybe?) here? [[User:627235|627235]] ([[User talk:627235|talk]]) 14:52, 23 June 2022 (UTC)

Talk:2629: Or Whatever

2022-06-07T11:41:46Z

627235:

This is me when I don't want to fact-check things I only barely remember reading about once. -V [[Special:Contributions/172.70.206.163|172.70.206.163]] 09:47, 7 June 2022 (UTC)

And once again, no love for ''Ostankino teletower'' built in 1966, which is a building-like structure unlike that bayonet-like CN Tower. *sighs in Muscovite* [[Special:Contributions/172.70.251.112|172.70.251.112]] 10:22, 7 June 2022 (UTC)

The Ostankino tower isn't considered a building. It doesn't have "continuously occupiable floors", so it's a just a tower, same as the CN...except shorter. [[Special:Contributions/172.70.230.75|172.70.230.75]] 11:27, 7 June 2022 (UTC)

But a decade older - doesn't concern the nineties, though. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:33, 7 June 2022 (UTC)

Fun additional trivia! The Willis Tower has over 100 floors, with floor 103 or so having an observation area meant for tourists. There're these glass boxes that extend out the sides you can walk into, with only an inch-and-a-half of disconcertingly-clear material between you and certain death. Source: I've been there, though it has been years. [[Special:Contributions/172.70.126.215|172.70.126.215]] 11:08, 7 June 2022 (UTC)

While colloquially confused, there is a difference between "building" (a structure build for interior/floor space), a "tower" (a free-standing structure whose purpose is to provide height for some application at the top while using little or none of the height for actual floors or at least not seeing them as a priority) and a "mast" (a thin, often lattice work, structure supported by {{w|guy wires}}. Also several measurements of height (especially for buildings) like roof height, structural height, highest floor or pinnacle (total) height including antennas.
The highest buildings during the 90s were: Sears Tower (roof and structural), WTC North Tower (pinnacle/antenna and top floor), Petronas Towers (since 1998, only structural)
The highest other structures were the CN Tower (free-standing tower) and Warsaw Radio mast (collapsed 1991) succeeded by the KVLY mast, both cable supported.
In 2004, the Taipei 101 succeeded the Sears Tower as highest building (floor since 2001, roof) and the Petronas Towers (structural) but not pinnacle height (2000 the antenna was extended to "beat" the WTC, succeeded by Burj Khalifa) [[User:627235|627235]] ([[User talk:627235|talk]]) 11:33, 7 June 2022 (UTC)
Sears Tower antenna/pinnacle height, that is, not Petronas. [[User:627235|627235]] ([[User talk:627235|talk]]) 11:41, 7 June 2022 (UTC)

Talk:2629: Or Whatever

2022-06-07T11:33:07Z

627235:

Talk:2629: Or Whatever

2022-06-07T11:32:11Z

627235:

This is me when I don't want to fact-check things I only barely remember reading about once. -V [[Special:Contributions/172.70.206.163|172.70.206.163]] 09:47, 7 June 2022 (UTC)

And once again, no love for ''Ostankino teletower'' built in 1966, which is a building-like structure unlike that bayonet-like CN Tower. *sighs in Muscovite* [[Special:Contributions/172.70.251.112|172.70.251.112]] 10:22, 7 June 2022 (UTC)

The Ostankino tower isn't considered a building. It doesn't have "continuously occupiable floors", so it's a just a tower, same as the CN...except shorter. [[Special:Contributions/172.70.230.75|172.70.230.75]] 11:27, 7 June 2022 (UTC)

But a decade older - doesn't concern the nineties, though.

Fun additional trivia! The Willis Tower has over 100 floors, with floor 103 or so having an observation area meant for tourists. There're these glass boxes that extend out the sides you can walk into, with only an inch-and-a-half of disconcertingly-clear material between you and certain death. Source: I've been there, though it has been years. [[Special:Contributions/172.70.126.215|172.70.126.215]] 11:08, 7 June 2022 (UTC)

While colloquially confused, there is a difference between "building" (a structure build for interior/floor space), a "tower" (a free-standing structure whose purpose is to provide height for some application at the top while using little or none of the height for actual floors or at least not seeing them as a priority) and a "mast" (a thin, often lattice work, structure supported by {{w|guy wires}}. Also several measurements of height (especially for buildings) like roof height, structural height, highest floor or pinnacle (total) height including antennas.
The highest buildings during the 90s were: Sears Tower (roof and structural), WTC North Tower (pinnacle/antenna and top floor), Petronas Towers (since 1998, only structural)
The highest other structures were the CN Tower (free-standing tower) and Warsaw Radio mast (collapsed 1991) succeeded by the KVLY mast, both cable supported.
In 2004, the Taipei 101 succeeded the Sears Tower as highest building (floor since 2001, roof) and the Petronas Towers (structural) but not pinnacle height (2000 the antenna was extended to "beat" the WTC, succeeded by Burj Khalifa)