explain xkcd - User contributions [en]

3086: Globe Safety

2025-05-11T16:43:11Z

162.158.91.126: Try to clarify and expand on event horizon. The horizon is simply the "surface" of the black hole to external observers. From outside you can't "see anything beneath it". That's how they got the name "black holes".

{{comic
| number = 3086
| date = May 7, 2025
| title = Globe Safety
| image = globe_safety_2x.png
| imagesize = 255x448px
| noexpand = true
| titletext = Frankly, given their extreme gravitational fields and general instability, even 12-inch globes should probably be banned.
}}

==Explanation==
{{incomplete|The first paragraphs might be too technical for normal users. Explain the concept of an event horizon, black hole, etc. so people aren't required to click on the Wikipedia link to understand the comic. Don't remove this notice too soon.}}
For any given amount of (stationary) mass, a value can be calculated known as the {{w|Schwarzschild radius}}, which denotes the radius of a spherical volume of space. If the mass somehow is compressed into this volume, it becomes so dense that it forms a {{w|black hole}}.

The newly-born black hole occupies that volume of space; more formally, that Schwarzschild radius then becomes the radius of that black hole's {{w|event horizon}}, the "surface" of the black hole to outside observers. When measured by a distant observer, the black hole's radius is the Schwarzschild radius. The event horizon is the "surface of no return": anything that falls into the black hole past its event horizon can't escape, and merges into it.

As for what's beyond the horizon? General relativity predicts an infinitely-dense {{w|singularity}} at the center, that anything falling past the event horizon eventually collides into. This is presumed a sign that the theory is failing at the extreme densities involved, where quantum mechanics can no longer be ignored, and some theory of {{w|quantum gravity}} is needed for a correct description; there are numerous speculative quantum qravity theories, but they remain untested at present, so the answer to what's "really" there is "we don't know (free Nobel up for grabs!)". (Relativity is a {{w|classical mechanics|"classical" theory}} which doesn't incorporate quantum mechanics at all, which is irrelevant on the scale of entire planets and stars and galaxies.)

Any arbitrary amount of mass has its corresponding value for its Schwarzschild radius. The Schwarzschild radius corresponding to the mass of the Earth is about 0.35 inches (roughly 9 mm, or a diameter of 7/10" or 18 mm), meaning if you could compress the Earth into a ball that small, it would be a black hole. The object at bottom right in the comic, with a triangular warning sign next to it, is a {{w|Black hole#Observation|depiction of a black hole}}.

{{w|Globes}}, in this context, are miniature re-creations of planet Earth, used to show its features without any of the [[977: Map Projections|typical problems of a flat map]]. [[Randall]] claims that safety standards are in place to ensure that globes are not manufactured at, below, or even close to the Schwarzschild radius of the Earth. The suggestion is that any globe of the Earth shares the same mass as the Earth and hence the same Schwarzschild radius. Such a globe might be made by creating a literal 1:1 replica of Earth and then shrinking it without distortion until it has the required size. This would, of course, give the most perfect maps; however, for each globe like this put on Earth, the Earth's mass would increase by its original amount, and in addition it would be impractical to make globes this way: such small amounts of matter of this density would [https://www.astronomy.com/science/what-if-a-tablespoonful-of-a-neutron-star-was-brought-to-earth/ immediately explode], vaporizing most or all of the Earth.

The title text suggests that globes up to 12 inches (30.5 cm) should be banned, due to their extreme density and gravitational field. The surface gravity of an object varies inversely with the square of its radius. Since the globe would have the same mass as the Earth, such a globe would exert massive, catastrophic gravitational forces at its surface. For a 12-inch globe, this would be 1.75 quadrillion times normal Earth gravity. The changes at the Earth's surface caused by these forces would immediately reduce the accuracy of the globe's representation of the area in which it is located. The gravitational effects on objects at a distance would be the same, but adding an Earth mass for each globe would still affect the orbits of satellites, other planets, etc. However, extreme gravity would exist for Earth-mass globes of any size, so the 12-inch cut-off is no less arbitrary than the 4-inch one.

==Transcript==
:[A standard globe of the Earth is shown. It stands on a typical stand which holds it by two arms at the poles, so it can turn around like the Earth does. The Earth is turned so it shows Australia at the bottom and most of Asia, including the entire India to the left. Only the very tip of Alaska can be seen of the Americas. Above the globe there is a double ended arrow that goes to two small lines that align with the edges of the globe (indicating the diameter). The arrow has been split in the middle and two lines of text are written in the gap. Above this text there is another line of text.]
:Remember:
:4 inches minimum

:[Beneath the globe there are two small drawings. The left shows the Earth and to the left of the Earth there is a double ended arrow ending at two lines that indicated the diameter of the Earth going from top to bottom. The distance of this is written in inches to the left. From the Earth an arrow points to another drawing, this time the typical depiction of a black hole, with a "hat" like shape. A triangular warning sign is shown a the top right of the black hole with an exclamation mark inside.]
:7/10"

:[Caption below the panel:]
:The Earth's Schwarzschild radius is about 0.35 inches, which is why safety regulations require desktop globes to be at least 4 inches in diameter.

{{comic discussion}}<noinclude>

[[Category:Astronomy]]
[[Category:Maps]]

Talk:3074: Push Notifications

2025-04-10T09:07:36Z

162.158.91.126: dmesg

So...this is the April Fool's comic, if I'm not mistaken... Oh ye of little faith! [[Special:Contributions/172.71.26.106|172.71.26.106]] 20:00, 9 April 2025 (UTC)

I turned this on thinking it would just be a few every so often but I quickly realized how this is xkcd and it doesn't "joke". I had to turn this off because it disrupted my schoolwork by popping up every fricking 5 minutes

Apparently my employer (or ublock) is keeping me from experiencing the full effect of any notifications. All I get is "An *actual* error has occurred. [[Special:Contributions/162.158.91.173|162.158.91.173]] 20:52, 9 April 2025 (UTC)
:Yeah, I'm confused too. I've tried Chrome and got nothing. I've tried Edge and got effectively nothing. I progressed one message further, but nothing showed up. No notifications, popups, or whatever. And I have never installed an add-on for Edge. Edge did give me access to the game over screen by disabling notifications, but when I tried to re-enable them, nothing happened.
:
:Is this a mobile-only thing? [[User:EebstertheGreat|EebstertheGreat]] ([[User talk:EebstertheGreat|talk]]) 02:51, 10 April 2025 (UTC)
:
:I'm having the same issue. Firefox doesn't work, which I understand, but neither does Safari. I haven't gotten a single notification. [[User:Mushrooms|Mushrooms]] ([[User talk:Mushrooms|talk]]) 06:57, 10 April 2025 (UTC)
::Problem solved! Turns out I *was* getting notifications, I just wasn't seeing them. --[[User:Mushrooms|Mushrooms]] ([[User talk:Mushrooms|talk]]) 07:07, 10 April 2025 (UTC)

What the heck are the "Zoom Notification" ones, with just a pair of numbers? Now that I've been sitting with this for a little bit, they're by far the most common notifications, and the most mysterious. What is "zoom"ing or should be zoomed-in-on or whatever, and what do the two numbers signify? [[Special:Contributions/172.68.22.75|172.68.22.75]] 20:35, 9 April 2025 (UTC)
:I think they're coordinates. So far (x,y) has had x from 4 fo 73 (that I've seen) and y from 2 to 28. That gives a tad over 2000 possible combinations, but omething tells me there won't be more than 500 or so in total. Quite a few y=24 (not yet adjacent by x), and any given x has 0 to 3 different y partners (so far). They ''do'' repeat (I'm not recording how many times, but I'm scatterplotting what I get). The ones prefixed with "oh look!" are tightly clustered in x=6..13 and y=4..11, so far, with no non-"oh look!" ones there, so I'm plotting them in a different marker. I ''suspect'', after many many more Zoom Notifications, I'll be left with (enough of) a pixelated image's pixels (of two types, background colour excluded), or else I'm doing it wrong and I should be drawing lines between the dots, but I never managed to grab them all, so I'm relying on it being a random "spraygun droplets" sort of image-reveal. (Still some way to go...) [[Special:Contributions/172.71.241.66|172.71.241.66]] 23:08, 9 April 2025 (UTC)
: Also, Zoom is a video chat app, if you didn't know that. That's the joke. [[User:EebstertheGreat|EebstertheGreat]] ([[User talk:EebstertheGreat|talk]]) 02:53, 10 April 2025 (UTC)

Made a new page called [[3074: Push Notifications/Table of Notifications]], much like [[1506: xkcloud/List of Permalinks]]. I’m hoping that we can put all of the possible notifications into the table, along with any possible images that go along with it and an explanation (if necessary). '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 21:26, 9 April 2025 (UTC)
:I think it might be a good idea to make the table something more like source/name/notification, because there are chains of notifications where the name changes, like the How Many Times Can You Click This? notification. --[[User:Magicalus|Magicalus]] ([[User talk:Magicalus|talk]]) 23:19, 9 April 2025 (UTC)
::Might even want to track the URL that the notification leads to in the cases where it opens a new tab. [[Special:Contributions/172.71.142.57|172.71.142.57]]
:Did you mean a page much like [[1506:_xkcloud/List_of_Permalinks]]? [[Special:Contributions/162.158.175.171|162.158.175.171]] 01:25, 10 April 2025 (UTC)
:: Weird, someone changed that. I just reverted it. --[[User:Jacky720|Jack]] ([[User talk:Jacky720|t]]|[[Special:Contributions/Jacky720|c]]) 02:07, 10 April 2025 (UTC)
:::Yes, the user {{diff|371988|behind this change}} appears to have a keyboard->leopard sort of autochanger active (for cloud->butt) (unless they're deliberately doing it alongside deliberate changes to try to get it under the radar?)... I reverted something else they did, with the intention to check everything else (in Right Click's explanation) and unreverting the actually good changes. [[Special:Contributions/172.70.162.160|172.70.162.160]] 08:39, 10 April 2025 (UTC)

I clicked on the silence notifications at a cost button a lot and it set Cueball's PC on fire?

I found what is presumably the source code (?) of the comic through the transcript. It’s all JS pages. No idea what they mean (I’m not good with code), but I’m sure that there are some on here that can help dissect it. '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 21:50, 9 April 2025 (UTC)
:https://xkcd.com/3074/marconi/manifest.json
:https://xkcd.com/3074/marconi/static/js/42.4f5b21b3.js
:https://xkcd.com/3074/marconi/static/js/index.js?v=1

: I found this list of states in there, saved to the "iU" variable: intro, wordgame, gameover, biglaptop, boat, default, floating, longdesk, missing, nekotree, nekotree2, nekowater, nodesk, onfire, peek, shark, spinning, squirrel, squirreldesk, squirrelplant, standing, sword, tallchair, tentacle, water, wizard, bigplant, catchair, catonhead, compiling, floor, plant, reverse. Presumably, this is all the images we're looking for. I'll get back to you if I identify what chooses them or all their actual filepaths. --[[User:Jacky720|Jack]] ([[User talk:Jacky720|t]]|[[Special:Contributions/Jacky720|c]]) 00:43, 10 April 2025 (UTC)

: I found more urls:
:https://xkcd.com/3074/marconi/static/js/async/marconi-sw.e9d36d05.js
:https://xkcd.com/3074/marconi/static/js/async/491.7b4e7556.js
:https://xkcd.com/3074/marconi/static/js/async/491.7b4e7556.js --[[Special:Contributions/172.69.23.45|172.69.23.45]] 03:11, 10 April 2025 (UTC)

I have a sneaking suspicion the Zoom Notifications are sketching out an image of some sort
(Update: after plotting like 60 of them no apparent pattern is to be found) [[User:SkiesShaper|SkiesShaper]] ([[User talk:SkiesShaper|talk]]) 22:24, 9 April 2025 (UTC)
: I've plotted 397 and it seems to be forming some kind of animal. Maybe a cat, given the comic theme? [[Special:Contributions/172.68.35.119|172.68.35.119]] 23:24, 9 April 2025 (UTC)
:That could make sense yeah - there is definitely an organic sort of pattern emerging from the points I've been plotting out [[User:SkiesShaper|SkiesShaper]] ([[User talk:SkiesShaper|talk]]) 00:35, 10 April 2025 (UTC)
: I'm pretty sure it's a turtle. I have 311 points so far and while it isn't clear, it looks like a turtle. [[User:IMW|IMW]] ([[User talk:IMW|talk]]) 01:51, 10 April 2025 (UTC)
:: After plotting more I think the "Oh look" coordinates help with drawing out a butterfly sitting on the left side of the turtle. [[User:IMW|IMW]] ([[User talk:IMW|talk]]) 03:36, 10 April 2025 (UTC)
: when the image is saved, it appears to have a hex code as a file name. could be some other thing though [[User:Pncak|Pncak]] ([[User talk:Pncak|talk]]) 04:07, 10 April 2025 (UTC)

Apparently one of the notifications is: "The Earth is spinning at a rate of 1 rpd" This is true if you round it, but not exact. The time it takes to rotate is called a sidereal day, and there's one extra sidereal day a year. Basically, there's one solar day removed in a year, because the Earth's motion around the sun cancels it out. Think of it with a tidally locked planet. It spins around once a year, but the sun never moves. Really there's 1.0027379 rotations per day. [[User:DanielLC|DanielLC]] ([[User talk:DanielLC|talk]]) 23:02, 9 April 2025 (UTC)
: then it is rotating at 1 revolution per ''sidereal'' day, which could still be written as 1 rpd [[User:Firestar233|guess who]] ([[User talk:Firestar233|if you desire conversing]] | [[Special:Contributions/Firestar233|what i have done]]) 05:23, 10 April 2025 (UTC)

This is the most chaotic comic I've seen in a while. Part of me wants to keep notifications on to see what happens, and part of me wants to turn it all off and throw my phone in a lake [[User:Alcatraz ii|Alcatraz ii]] ([[User talk:Alcatraz ii|talk]]) 00:40, 10 April 2025 (UTC)

I am making a sheet with the cordinates: https://docs.google.com/spreadsheets/d/133jGfOM6EVuEco4j2NumOAOv6pEealyZpbDoMkESXvs/edit?usp=sharing
[[Special:Contributions/108.162.216.81|108.162.216.81]] 01:31, 10 April 2025 (UTC)

Should we start uploading different images? [[User:Firestar233|guess who]] ([[User talk:Firestar233|if you desire conversing]] | [[Special:Contributions/Firestar233|what i have done]]) 03:48, 10 April 2025 (UTC)
: And should we create a new page for the images or put them all on the same page, like with umwelt. [[User:Firestar233|guess who]] ([[User talk:Firestar233|if you desire conversing]] | [[Special:Contributions/Firestar233|what i have done]]) 03:49, 10 April 2025 (UTC)

Underneath the "Silence Notifications at a Cost" button, it says "Temporarily pause your notifications at the cost of notifying two random people". Does anyone know how for how long notifications stay silenced, or if there is a way to "unsilence" notifications? Also, when I click on the cats they just disappear. [[User:PDesbeginner|PDesbeginner]] ([[User talk:PDesbeginner|talk]]) 04:09, 10 April 2025 (UTC)
: When I click on the cats I get a push notification with a cat fact.[[Special:Contributions/172.70.127.58|172.70.127.58]] 05:35, 10 April 2025 (UTC)
Just like any other button, you can click it really fast by clicking the button and then holding "enter" or spacebar. [[User:Firestar233|guess who]] ([[User talk:Firestar233|if you desire conversing]] | [[Special:Contributions/Firestar233|what i have done]]) 04:35, 10 April 2025 (UTC)

Someone should probably comment on "April 1st (observed)". I assume it's a reference to the fact that the comic is late? --[[User:Mushrooms|Mushrooms]] ([[User talk:Mushrooms|talk]]) 07:53, 10 April 2025 (UTC)
:Aye, as in: {{wiktionary|observed}} #2 [[Special:Contributions/172.71.26.43|172.71.26.43]] 08:02, 10 April 2025 (UTC)

Is it morally wrong to spam the temporary silence button, just because I want to give other people notifications? [[User:Broseph|Broseph]] ([[User talk:Broseph|talk]]) 08:01, 10 April 2025 (UTC)

Notifications are so 2024. Ever since Trump imposed the penguin tariffs, <tt>dmesg</tt> is where it's at. [[Special:Contributions/162.158.91.126|162.158.91.126]] 09:07, 10 April 2025 (UTC)