explain xkcd - User contributions [en]

Talk:3072: Stargazing 4

2025-04-05T19:11:01Z

172.68.150.67:

Is it not possible and even likely, due to the simplistic nature of the dialog here, that the falling stars here in fact have nothing to do with black holes and merely refer to "falling stars"?
[[Special:Contributions/172.68.150.67|172.68.150.67]] 19:11, 5 April 2025 (UTC)

First comic explanation I've done. This is... somewhat harder than what I expected. [[User:MinersHavenM43|MinersHavenM43]] ([[User talk:MinersHavenM43|talk]]) 02:46, 5 April 2025 (UTC)

To be clear, the comic says grains of sand on Earth's *beaches* which presumably excludes deserts and such. I think another joke with that panel might be that Earth has more sand than just the beaches.
[[Special:Contributions/108.162.212.31|108.162.212.31]] 03:21, 5 April 2025 (UTC)

Randal is rarely wrong. Have we seen TDEs (tidal disruption events) for Sag A* or only for other supermassive black holes? --[[Special:Contributions/172.70.242.247|172.70.242.247]] 07:44, 5 April 2025 (UTC)

I don't think the voice in the title text should be identified with Randall. Furthermore it is said that we haven't seen a star fall into a black hole, which is different from a TDE. --[[Special:Contributions/172.71.102.194|172.71.102.194]] 08:23, 5 April 2025 (UTC)

She's back. SHE'S BACK!!!! /ref [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 09:10, 5 April 2025 (UTC)

This feels like Cunk on Space [[Special:Contributions/141.101.99.123|141.101.99.123]] 11:06, 5 April 2025 (UTC)

Indeed we never saw a TDE for Sag A* provided context for that --[[User:Trimutius|Trimutius]] ([[User talk:Trimutius|talk]]) 11:13, 5 April 2025 (UTC)

In the last panel and title text, Megan states it's hilarious when "stars" fall into black holes, that they can't leave Yelp reviews, and that she has a list of stars she hopes are next to fall in. Is it possible she's now conflating Hollywood stars (movie/TV personalities) with the celestial bodies? Like she has a list of entertainment personalities she bears a grudge against and wishes they would leave the country (or universe)? [[Special:Contributions/172.70.126.154|172.70.126.154]] 11:54, 5 April 2025 (UTC)Pat

Talk:3056: RNA

2025-02-27T03:12:06Z

172.68.150.67:

I really hate that feeling when you need an explanation for at least a couple frames but you're too early to read it and too dumb to write it. [[Special:Contributions/172.68.3.27|172.68.3.27]] 14:34, 26 February 2025 (UTC)
:I know, I really wish I knew about RNA so I could just kinda do it. [[User:DollarStoreBa'al|DollarStoreBa'al]] ([[User talk:DollarStoreBa'al|talk]]) 15:48, 26 February 2025 (UTC)

The 2040's guess in the title text is wild, and would be SO cool if we were able to discover that in 20 years. {{unsigned ip|162.158.146.139|14:49, 26 February 2025}}

oh God [[User:Definitely Bill Cipher|⯅A dream demon⯅]] ([[User talk:Definitely Bill Cipher|talk]]) 15:09, 26 February 2025 (UTC)

1960s: central dogma of molecular biology; 1980s: discovery of catalytic self-splicing RNA; 2000s: genomic sequencing and discovery of diverse array of non-coding RNAs; 2040s: extrapolation of RNA hypothesis, with aside to notion that life may have arisen multiple times (earlier instances extinguished by large impacts) {{unsigned|Jhonts|15:34, 26 February 2025}}
:...or assimilation of function (or extinction by superior RNA, but then we'd not see any signs, whilst maybe there were provable mergers between 'different' original systems). Maybe why there are three shared bases between DNA and RNA, but two unique ones, or other interesting aspects that create puzzles. [[Special:Contributions/172.71.178.139|172.71.178.139]] 17:53, 26 February 2025 (UTC)

Should the transcript point out the changes in the poster in each frame? Maybe in the later frames those are RNA rather than DNA. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 15:40, 26 February 2025 (UTC)
:It's unlikely to be RNA, since RNA is usually single stranded. According to a quick search, it can sometimes be double stranded as a secondary structure or in some viruses. [[User:Solid Kalium|Solid Kalium]] ([[User talk:Solid Kalium|talk]]) 15:55, 26 February 2025 (UTC)

How has it been a full day and no full explanation yet? {{unsigned|DollarStoreBa'al|20:22, 26 February 2025}}
:My guess is that most readers are physics/coding/maths oriented [[Special:Contributions/172.71.241.100|172.71.241.100]] 22:04, 26 February 2025 (UTC)
:Hardly a full day. It was early, but only about six hours before your (DSB's) query. Which was start of the working(/schooling) day, in the US, if not earlier. Those of that territory who are more used to spotting new comics in the early evening might not yet have gotten around to looking.
:Though I prefer to be in it for the long-haul, it takes time to bash a decent explanation into shape, and when ''I'' first saw it, I made a minor (in-context) witicism and resolved to return later when either I could bash the early-bird editors' efforts into shape or else form the bits of it that (inexplicably) no-one else had thought of. I'm currently pondering quite ''which'' of these two scenarios I'll find when I check... ;) [[Special:Contributions/172.70.162.162|172.70.162.162]] 22:37, 26 February 2025 (UTC)

The link to bases of rna💀[[Special:Contributions/172.68.150.67|172.68.150.67]] 03:12, 27 February 2025 (UTC)

Talk:3020: Infinite Armada Chess

2024-12-05T14:01:47Z

172.68.150.67: /* Hit me up when this becomes real. */

Did I do well? Added a very very basic explanation. [[Special:Contributions/172.68.147.132|172.68.147.132]] 04:25, 5 December 2024 (UTC)

Well, yes but I wonder if just one tiny fix is needed. If you replace the white side with a simplyfied artillery tower, you reinvented space invaders.{{unsigned ip|172.71.160.70|04:57, 5 December 2024 (UTC)}}

I was personally hoping for an explanation of the Infinite Armada thing, and I feel like a link to the TV Tropes page doesn't really. Explain that at all. So I would love a bit of an expansion on that part! Just want to be sure I didn't miss some reference or something. [[Special:Contributions/172.68.23.91|172.68.23.91]] 05:48, 5 December 2024 (UTC)
: Likewise. I get the comic, but I assumed the 'armada' part was a reference that I just did not get. But it seems it is just a word choice. [[Special:Contributions/172.71.102.105|172.71.102.105]] 09:39, 5 December 2024 (UTC)

I think that since the error was "out of bounds", not "out of memory", it's referring to indexing outside of the region of memory that the program allocated to deal with the board. This would happen since instead of addressing rank 1..8, you could address rank 9, 10, 0, or -1. Unless bounds checking is performed when converting the board coordinates into linear array indices, you'd get an out-of-bounds error (or worse, succeed in reading or modifying memory that you weren't intending to). --[[Special:Contributions/172.71.30.253|172.71.30.253]] 05:45, 5 December 2024 (UTC)
:It was "Out of Bounds memory access". That means it was trying to access a memory address that was out of the bounds of the computer, as if it were trying to access the ω-th index of the board array, which would put it out of the memory range of any computer [[User:Firestar233|guess who]] ([[User talk:Firestar233|if you want to]] | [[Special:Contributions/Firestar233|what i have done]]) 06:15, 5 December 2024 (UTC)
:: There is no hint that the bounds are those of the computer, the simplest explanation really is that the bounds are those of an array. The error message does come up. In addition, to try to access the memory at the ω-th index, you would need to construct the ω-th index itself first (which would fail or not terminate) [[User:Jmm|Jmm]] ([[User talk:Jmm|talk]]) 07:01, 5 December 2024 (UTC)
::: The specific message, "RuntimeError: Out of bounds memory access", is a WebGL error issuing from its WASM cross-platform browser implementation. This implies to me that an attempt to render an infinite chessboard failed in a fairly trivial way, because of a poor implementation. It's very unlikely that there had been a problem with the [https://github.com/official-stockfish/Stockfish/tree/master/src Stockfish playing algorithm] yet, which would have failed with a different message if it ran out of memory, such as "Killed", which is all that shells like Bash print when one of their job processes is killed by the kernel's OOM killer, or by anything else for that matter. [[Special:Contributions/172.70.215.21|172.70.215.21]] 12:58, 5 December 2024 (UTC)

Is this a reference to [https://youtu.be/rav29N0-h2c infinite chess by Naviary?] [[User:HaruruChanDesu|HaruruChanDesu]] ([[User talk:HaruruChanDesu|talk]]) 11:21, 5 December 2024 (UTC)

"it does not really need to consider the infinitely many pieces" => a chess Engine would need to consider the infinitely many pieces (or have a way to abstract them), even if some pieces are currently stuck because the engine recursively evaluates moves and counter-moves (i.e. evaluates the game up to some depth).

== Hit me up when this becomes real. ==

I would like to try this out. [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 12:29, 5 December 2024 (UTC)
:It should be easy enough. You will rarely get the queens out in play from deep in the array. So maybe just put two chess boars together and put some placeholder in for queens in the extra fields. If ever a queen in the bottom row is moved, place extra queens that can now be moved into the 2-3 squares that would be outside the board...--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 12:39, 5 December 2024 (UTC)
:It might be something one could set up in Infinite Chess, although having limits on the chessboard may be difficult. [[Special:Contributions/172.68.150.67|172.68.150.67]] 14:01, 5 December 2024 (UTC)

While I understand how to play chess, I don't get the bit about "having a bunch of queens doesn't go very well". At first glance, the linked chess layout looks pretty solid. Can someone please enlighten me? Also, what does the TV Tropes link about Title Drop have to do with Infinite Armada, aside from that being the title of the comic? [[Special:Contributions/172.70.230.77|172.70.230.77]] 13:10, 5 December 2024 (UTC)

:: ... Nd6. [[Special:Contributions/172.70.91.246|172.70.91.246]] 13:31, 5 December 2024 (UTC)

3015: D&D Combinatorics

2024-11-23T01:44:43Z

172.68.150.67: /* Explanation */

{{comic
| number = 3015
| date = November 22, 2024
| title = D&D Combinatorics
| image = dnd_combinatorics_2x.png
| imagesize = 328x446px
| noexpand = true
| titletext = Look, you can't complain about this after giving us so many scenarios involving N locked chests and M unlabeled keys.
}}

==Explanation==
{{incomplete|Created by a BOT THAT GRABBED A CURSED ARROW - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

Dungeons and Dragons (D&D) is a role-playing game that usually has a "Dungeon Master" (narrator) that takes a team of players through scenarios where they attack monsters and go on quests.

Often, there will be semi-random events: e.g., when attacking a monster, often, a player would roll a die and deal damage based on what that die returns. D&D also uses a variety of dice, from regular d6 (6-sided, cubic dice) to other polyhedral dice, with the number of faces denoted by dX (e.g., d10 is a 10-sided die, with numbers from 1 to 10 on it). Common sets include: d4, d6, d8, d10, d12, d20, and occasionally d100 (typically not, however, the [[2626:_d65536|d65536]]).

With these, you can simulate events with a wide variety of denominators. In this case, Cueball gives a combinatorial problem:

* There are 10 arrows.
* 5 arrows are cursed.
* You randomly take two.
* What are the odds that neither of them are cursed?

There are: "10 choose 2" (45) ways to choose two arrows, of which there are "5 choose 2" (10) ways to choose 2 arrows that are non-cursed. As a result, the odds of taking all non-cursed arrows is 2/9.

The Dungeon Master in this case has to map that probability into rolling multiple dice, whose sums are also not evenly distributed: i.e. if rolling 3D6 (3 six-sided dice) and a D4 (1 four-sided die), the sums can range from 4 to 22. It's pretty hard to do this in one's head, but it does happen that the odds of rolling 16 or more with this combination is 2/9, matching the probability that we want to simulate.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
[Cueball, Megan, Ponytail, White Hat, and Knit Cap are sitting at a table. Everyone is looking at Cueball. Ponytail is facepalming. The table is covered in sheets of paper and assorted dice.] 
Cueball: I grab 2 of the 10 arrows without looking and fire them, hoping I didn't grab one of the 5 cursed ones. Did I? 
Ponytail: Sigh. Umm. Okay. 
Ponytail: Roll... Uh... Hang on... 
Ponytail: Roll 3d6 and a d4. You need... 16 or better to avoid the cursed arrows.

Caption: I got '''''way''''' more annoying to play D&D with once I learned that our DM has a combinatorics degree and can't resist puzzles.

{{comic discussion}}