explain xkcd - User contributions [en]

Talk:3087: Pascal's Law

2025-05-09T21:48:17Z

172.70.110.59:

I remember learning about this and thinking it was intuitive, but I didn't really think of these consequences. Maybe everybody is making powerful lifting machines for lifting cars and houses with your bare hands, rather than explaining the article, that there isn't one yet. Pascal's law basically says that if you make one end of a container of fluid X times larger, then any force exerted on the small end is multiplied by X on the large end, so you can make it near-infinite by making the small end very small. But you'll need a little more machinery added (like a gear system) if you want the distance actually moved to be higher. Actually I think that might undo the gains in force entirely. That might be how it happens, it might swap distance for force so the same work is performed. [[Special:Contributions/172.70.111.110|172.70.111.110]] 21:46, 9 May 2025 (UTC)

Talk:3086: Globe Safety

2025-05-08T13:26:36Z

172.70.110.59: a 12 inch earth mass

Hello! First time i got to a comic first --[[Special:Contributions/172.69.176.76|172.69.176.76]] 06:17, 8 May 2025 (UTC){{unsigned ip|104.23.175.202}}
:Well [[269: TCM|first of all]] remember to sign your comments :-). But congratz... --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 05:42, 8 May 2025 (UTC)
::Sorry.
::I now realize that that was an extremely trollish thing to do. --[[Special:Contributions/172.70.92.140|172.70.92.140]] 07:09, 8 May 2025 (UTC) ٠ـ٠
:: Also i MAY OR MAY NOT have permanently altered the editing process of this talk by including arabic numbers in an emoticon.

I believe he indicates that a globe is made by making a copy of the Earth, and then compressing it until it fits on a desktop. Hence having the same mass and thus the same Schwarzschild radius as Earth. I have changed the explanation a bit because of this observation.--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 05:42, 8 May 2025 (UTC)

Gotta wonder what kind of a desk could support a desktop globe that weighs as much as the Earth
--[[User:StumbleRunner|StumbleRunner]]
:[...] desk? Convince me that such a globe wouldn't plunge straight through the Earth's crust and into the mantle. I sense a marketing problem. [[Special:Contributions/172.71.147.69|172.71.147.69]] 07:07, 8 May 2025 (UTC)

Radius. <s>Is there a typo in the comic where 7/10" should be 7/20", i.e., 0.35" as later written? Or would a 7/10" Earth collapse into a black hole nonetheless?</s>[[Special:Contributions/172.71.154.129|172.71.154.129]] 06:40, 8 May 2025 (UTC)
:Nope… the Schwarzchild radius is 0.35", which is indeed 7/20", but the measurement shown on the globe is the diameter, not the radius, so 7/10" is correct. [[Special:Contributions/172.71.178.143|172.71.178.143]] 06:49, 8 May 2025 (UTC)

Isn't there also a jab at the weird way USsians use power-of-two fractions for inch measurements? I've never seen something like 7/10" before, it would be approximated as 11/16".[[Special:Contributions/172.71.95.69|172.71.95.69]] 09:18, 8 May 2025 (UTC)
: It isn't a weird USian thing - it's just the historical way that inches (being a non-metric unit) were divided. The same way that an inch is a 1/12 division of a foot, which is a 1/3 division of a yard, etc. [[Special:Contributions/141.101.98.83|141.101.98.83]] 10:23, 8 May 2025 (UTC)

I think we have a bigger problem: there are millions of globes on Earth! I haven't done the calculations, but that might be enough to turn Earth into a black hole already; if not, I expect at least it would turn it into a star. --[[Special:Contributions/104.23.190.34|104.23.190.34]] 11:44, 8 May 2025 (UTC)

BTW. what would be a 12-inch object with a mass of Earth? Neutron star? Neutron planet? Neutron meteoroid? -- 12:46, 8 May 2025 (UTC)

Crunching the numbers (thanks to Copilot.microsoft.com):
* A sphere with a 30 cm radius has a volume of about 1.13×10-2 m³.
* Compressing Earth's mass into that volume gives a density of roughly 5.3×1028 g/cm³.
That is way way denser than a neutron star. It's doubtful that such a sphere would remain at that density; it would likely explode immediately, or if prevented from doing so, continue to shrink down past 9mm and become a black hole.

2606: Weird Unicode Math Symbols

2023-07-05T14:52:28Z

172.70.110.59: /* Table of symbols */ GPT3 obviously has no idea whatsoever, and this explanation is made significantly worse by including it.

{{comic
| number = 2606
| date = April 13, 2022
| title = Weird Unicode Math Symbols
| image = weird_unicode_math_symbols.png
| titletext = U+2A0B ⨋ Mathematicians need to calm down
}}

==Explanation==
This comic proposes joke explanations for various {{w|unicode symbols}} with obscure or no known uses, see the [[#Table of symbols|table]] below.

It may have been inspired by this blog post [https://ionathan.ch/2022/04/09/angzarr.html U+237C ⍼ RIGHT ANGLE WITH DOWNWARDS ZIGZAG ARROW]. It was posted four days prior to this comic's release. The blog post went viral (in a limited sense) the same day the comic was published, perhaps as a consequence of it mentioning one of the symbols of the comic, Larry Potter. This caused the blogger to update his post with a [[33: Self-reference|reference]] to both xkcd and explain xkcd:
:"XKCD #2606 mentions ⍼ and its Explain XKCD entry cites this post"

The title text includes yet another special symbol ⨋, and this symbol prompts [[Randall]] to ask Mathematicians to calm down. See more details in the table below, where the title text symbol is mentioned in the last entry.

===Table of symbols===
{| class="wikitable"
|+ Symbols
|-
! Codepoint !! Symbol !! Unicode Name !! Actual use !! Randall's meaning || Explanation
|-
| U+29CD || ⧍ || Triangle with Serifs At Bottom || No known mathematics use, but resembles the {{w|National Park Service}} cartographic symbol for a campsite.[https://github.com/nationalparkservice/symbol-library/] || Shark || May look like a shark fin sticking out of the water.
|-
| U+23E7 || ⏧ || Electrical Intersection || Indicates where wires branch off || Traffic circle || Looks like a diagram of a {{w|roundabout}} as might be shown on a minimap beside a routing direction.
|-
| U+2A33 || ⨳ || {{w|Smash product}} || The quotient of the product of the underlying spaces of two {{w|pointed space}}s, where points in the {{w|product space}} are identified if they contain either labeled point as an element. || Hashtag || Looks somewhat like the {{w|Number sign|hash}} symbol (#) – commonly used for indicating tags called {{w|hashtag}}s in social media – turned by 45 degrees.
|-
| U+2A7C || ⩼ || Greater-Than with Question Mark Above || Used in proofs to indicate a greater-than relation that should exist but hasn't been proven yet (non-rigorous) || Confused alligator || One metaphor used when teaching inequality signs in primary school is that the sign looks like an alligator mouth "eating" the larger number. Question marks are commonly used in cartoons to indicate confusion on the part of a character.
|-
| U+299E || ⦞ || Angle with S Inside || Plural for the angle symbol (∠) [https://www.quora.com/Unicode-How-is-the-s-in-triangle-glyph-used-in-mathematics][https://www.birdvilleschools.net/cms/lib2/TX01000797/Centricity/Domain/1114/Homework%20Helper%20Unit%203%20ch%209-10.pdf] rarely used || Snack || May look like a mouth eating an S, where the S symbolizes some snack food, or the word "snack".
|-
| U+2A04 || ⨄ || {{w|Arity|N-ary}} Union Operator with Plus || Disjoint union[https://books.google.com/books?id=531cAgAAQBAJ&pg=PA165&lpg=PA165&dq=%E2%A8%84&source=bl&ots=oYXkMNXP-T&sig=ACfU3U2QvMRBkD7uVG0OSumKI0JQtjTIKA&hl=en&sa=X&ved=2ahUKEwios862ypL3AhWXVTABHTnQALQQ6AF6BAgKEAM] (joining a family of sets that have no elements in common) || Drink refill || Looks like a cup with a plus to indicate adding drink to the cup.
|-
| U+2B48 || ⭈ || Rightwards Arrow Above Reverse Almost Equal To || Pairs with ⭂ which could conceivably mean {{w|Assignment (computer science)|assignment}} of an {{w|Approximation|approximation}}, but neither seem to be in use. Possibly intended to describe ill-defined projections. || Snakes over there || Looks like two squiggles to represent snakes and an arrow indicating the direction where they may be found.
|-
| U+225D || ≝ || Equal To By Definition || Indicates an equation where the left side is to be defined as the right side[https://www.reddit.com/r/math/comments/1z1mty/can_someone_please_explain_the_equal_to_by/] usually used in proofs to indicate a definition is being introduced|| Definitely, for sure || "Def" is a contraction of "definitely" used in slang; the equal sign looks like a double underline, indicating heavy emphasis.
|-
| U+237C || ⍼ || Right Angle with Downwards Zigzag Arrow || No purpose is known.[https://ionathan.ch/2022/04/09/angzarr.html] Speculation includes a diode with a gate, proof by contradiction, a proofreaders' mark to split a word, and indication of polarization direction. || Larry Potter || Looks like the letter "L" and a lightning bolt. {{w|Harry Potter (character)|Harry Potter}} is known for having a lightning bolt-shaped scar on his forehead. The character {{w|Legal_disputes_over_the_Harry_Potter_series#Nancy_Stouffer|Larry Potter}} figured in a fraudulent legal claim against J.K. Rowling.
|-
| U+2A50 || ⩐ || Closed Union with Serifs and Smash Product || Indicates that a collection of topological spaces is {{w|Union-closed sets conjecture|closed}} when taking arbitrary unions and smash products. That is, if you take the union of any collection of topological spaces in the collection (even uncountably many), or the smash product of them, the result will also be in that collection. This is apparently important because the sets can't be isomorphic (one cannot be rearranged to be exactly the other.) [https://mathoverflow.net/questions/196084/counterexample-for-associativity-of-smash-product] || Spider caught with a cup and index card || Spiders or other bugs found within someone's house or workspace may be caught with a glass and something flat, often a card or a magazine, to be released outside. The projecting lines of the smash product symbol resemble the legs of a spider. Confusingly, some fonts display this symbol with different numbers of "legs": eight, as a 45°-rotated hash symbol, or six as an asterisk.
|-
| U+2A69 || ⩩ || Triple Horizontal Bar with Triple Vertical Stroke || Emblem of the Romanian {{w|Iron Guard}} fascist political movement; Loosely resembles part of the {{w|International Association for Cryptologic Research|IACR}} logo, as depicted in [[153: Cryptography]]; possibly a four-by-four {{w|tic-tac-toe}} board.[https://pages.cs.wisc.edu/~sandlund/NumericalTicTacToe.pdf] || ℍ𝕒𝕤𝕙𝕥𝕒𝕘 || Hash symbol with one extra vertical and horizontal line, or perhaps a hash symbol which has been accidentally double-struck or overprinted.
|-
| U+2368 || ⍨ || APL Functional Symbol Tilde Diaeresis || Used for a two-argument operation to [https://aplwiki.com/wiki/Commute commute] (swap) its arguments or allow it to use a single provided argument in both argument slots, and to convert a value into a [https://aplwiki.com/wiki/Constant constant] function || :/ || Looks like a confused or disappointed face. Randall's use is in fact common among {{w|APL (programming language)|APL}} programmers in the comments, as documented [https://aplwiki.com/wiki/APL_Orchard#Emoticons here] and [https://aplwiki.com/wiki/Humour#Glyph_puns here].
|-
| U+2118 || ℘ || Script Capital [''sic''] P || A stylized {{w|round hand}} 'p' used by Weierstrass for his "{{w|Weierstrass elliptic function|p-function}}," with features of both capital 𝒫  and small 𝓅. Sometimes also used as the {{w|power set}} operator.
|| Snake || This symbol coils around like a long snake, with a tapering-off tail on one end and a small "head" on the other.
|-
| U+2AC1 || ⫁ || Subset with Multiplication Sign Below || Indicates that one set is subset of another by means of a product || <div style="writing-mode: vertical-rl; text-align: center;">User experience</div> || Looks like the letters "Ux" sideways; UX is a common abbreviation for {{w|user experience}}.
|-
| U+232D || ⌭ || {{w|Cylindricity}} || A symbol used in geometric dimensioning and tolerancing (GD&T) to represent a parameter called "cylindricity" which describes the statistical deviation of an ensemble of surfaces from a reference cylinder. [https://cimquest-inc.com/metrology-minute-cylindricity/ example use] || Rolling dough between your hands to shape it into a ball || Looks like two flat hands (perhaps like stick-figure arms) rolling a ball between them. Rolling dough between one's hands to make it into a ball is an important step in making many kinds of pastry and bread.
|-
| U+2A13 || ⨓ || Line Integration with Semicircular Path Around Pole || Very rare symbol for half of a closed {{w|Contour integration|contour}} or {{w|Line integral|line}} integral which contains the {{w|Origin (mathematics)|origin}} in its interior. Contour integrals which circle the origin are very important in complex analysis. If such an integral were split into two parts, each could be represented by this symbol (which can be mistaken for ⨔, the integral not including the {{w|Zeros and poles|pole}}, with a wider and more complete arc around an offset dot.) [https://math.stackexchange.com/questions/2299363/where-is-the-%E2%A8%93-integral-symbol-defined]
|| Integral that avoids a bee on the whiteboard || Looks like an {{w|integral}} symbol with a bump that goes around a dot, as if a professor was drawing an integral on a whiteboard but did not want to disturb a bee that had landed right in the path of their marker.
|-
| U+2A0B (title text)|| ⨋ || Summation with Integral || The sum of the sum of the discrete elements (∑) and the integrals (∫) over the connected pieces. This symbol requires context to be meaningful but could occur, for instance, when computing probabilities using mixed distributions.
[https://twitter.com/fermatslibrary/status/1308743505309822977 see also]
|| Mathematicians need to calm down || Each of the two symbols is specifically used to represent a kind of summation that is calculated completely differently from the other. Combining them could produce frustration for people unfamiliar with the usage. The comment given may make fun of mathematicians' tendency to form increasingly complex expressions in their work. It may as well be a pun on the pronounciation of the letter {{w|Esh_(letter)|Esh}} (Shhhh).
|-
|}

==Transcript==
<big>Weird Unicode Math Symbols</big>
And their meanings

{|
| U+29CD || ⧍ || Shark
|-
| U+23E7 || ⏧ || Traffic circle
|-
| U+2A33 || ⨳ || [The word "hashtag" with the letters slanted counterclockwise]
|-
| U+299E || ⦞ || Snack
|-
| U+2A04 || ⨄ || Drink refill
|-
| U+2B48 || ⭈ || Snakes over there
|-
| U+225D || ≝ || Definitely, for sure
|-
| U+237C || ⍼ || Larry Potter
|-
| U+2A50 || ⩐ || Spider caught with a cup and index card
|-
| U+2A69 || ⩩ || [The word "hashtag" but with extra horizontal and vertical lines]
|-
| U+2368 || ⍨ || :/
|-
| U+2118 || ℘ || Snake
|-
| U+2AC1 || ⫁ || [The words "user experience" rotated clockwise 90 degrees]
|-
| U+232D || ⌭ || Rolling dough between your hands to shape it into a ball
|-
| U+2A13 || ⨓ || Integral that avoids a bee on the whiteboard
|}

{{comic discussion}}
[[Category:Unicode]]
[[Category:Math]]
[[Category:Harry Potter]]

2793: Garden Path Sentence

2023-06-24T04:47:44Z

172.70.110.59:

{{comic
| number = 2793
| date = June 23, 2023
| title = Garden Path Sentence
| image = garden_path_sentence.png
| imagesize = 273x273px
| noexpand = true
| titletext = Arboretum Owner Denied Standing in Garden Path Suit on Grounds Grounds Appealing Appealing
}}

==Explanation==
{{incomplete|Created by THE OLD WHO MAN THE BOAT.}}

A {{w|garden-path sentence}} is one in which the first or most obvious attempt at parsing the beginning of a sentence leads to the wrong meaning, causing confusion when the sentence is completed. A classic example of a garden path sentence is "The old man the boat.", leading to an initial incorrect parsing of "the old man" as a noun phrase, and therefore no verb before the noun "the boat". The actual way to parse this sentence is to treat "the old" as a noun and "man" as a verb, meaning "take one's place at" or "to work at, run, or operate" , so the sentence means "The old people are operating the boat."

Possible grammatically correct interpretations of the sentences in this comic are:

There was a court case regarding green walkways. The case was resolved with a sentence relating to an olive garden path. That sentence was vacated (cancelled) by a judge. That judge was flying an airplane. The airplane struck multiple birds. The plane overturned, but righted (turned right-side-up) and landed safely.

After (bird strikes)1, (judge)2, (who ordered)3 (olive garden-path sentence)4 in (case of green walkways)5 (vacated)3, (overturned but rights and lands safely.)2

# "[[wikipedia:bird strike|bird strike]]s": Airplane colliding with birds in flight
# "judge ... overturned but rights and lands safely": The judge (and presumably the plane they were in) flipped over but was able to get right-side up again and land safely
# "who [[wikipedia:Court order|ordered]] ... [[:wikipedia:Vacated judgment|vacated]]": The same judge had previously issued a ruling cancelling something
# "Olive Garden path [[wikipedia:Sentence (law)|sentence]]": The thing that was cancelled was a punishment related to garden paths at [[wikipedia:Olive Garden|Olive Garden]].
# "[[wikipedia:Legal case|case]] of [[wikipedia:Green|green]] walkways": The punishment was in a court case about green-colored walkways (likely the same garden paths listed above, which may have supposed to have been an olive shade of that color)

Another way to break it down is, "After [the] bird strikes, [the] judge... [is] overturned, but [she] rights and lands safely." And she was "[the] judge who ordered [that the] olive garden-path sentence (the legal sentence concerning an olive-colored path) in (what is known as) [the] Case of [the] Green Walkways [be] vacated."

This comic also pokes fun at newspaper headlines, which typically do not have punctuation or articles, leading to such ambiguities.

For another valid parsing of the sentence, here are some explanatory notes that aid in understanding:
* A criminal court case occurred involving green-colored walkways.
* The sentence handed down in the case involved a specific walkway (a garden path) and a specific shade of green (olive).
* A certain judge had ordered that the sentence be vacated (a legal term meaning undone or expunged).
* That judge was recently piloting a plane which, due to being struck by birds, overturned.
* The judge righted the plane (turned it right-side-up) and landed safely.

Certain combinations of words in the sentence are particularly easy to parse incorrectly. For example:
* "bird strikes judge" can be interpreted to mean the a bird deliberately hit the judge with an appendage or weapon
* "Olive Garden" is the name of a restaurant chain, and "ordered Olive Garden" could mean "placed an order for food from Olive Garden"
* "Garden path sentence" is a type of (written language) sentence
* "in case of" can mean "in the event of" (e.g. "in case of emergency, break glass")
* "vacated" and "overturned" can both mean "undone" in a legal context, and "rights" can refer to legal or constitutional rights

The title text is also an example of a garden path sentence. The meaning is probably the following: Arboretum owner, [who was] denied [legal] standing in [the] garden-path [law]suit on grounds (the reason) [that the garden] grounds [are] appealing, [is] appealing [the ruling]

==Transcript==
{{incomplete transcript}}
:[Newspaper, with a picture of a plane next a judge, and a picture of a map with the path of an airplane, with the following headline]
:After bird strikes judge who ordered olive garden path sentence in case of green walkways vacated overturned but rights and lands safely

{{comic discussion}}

[[Category:Language]]
[[Category:Aviation]]
[[Category:Animals]]