explain xkcd - User contributions [en]

1490: Atoms

2024-08-27T04:16:54Z

172.69.58.152: /* Trivia */

{{comic
| number = 1490
| date = February 23, 2015
| title = Atoms
| image = atoms.png
| titletext = When I was little I had trouble telling my dad apart from the dog. I always recognized my mom because she had a bunch of extra plutoniums in her middle. I never did ask her why...
}}

==Explanation==
This comic shows another quirky and fantastical ability of [[Beret Guy]].

In this comic, [[Megan]] is preparing a sample of what appears to be some mineral for {{w|elemental analysis}}. It seems to be some kind of {{w|silicate}} containing a small amount of {{w|iron}} (a common example of this would be {{w|red sandstone}}), and she is running a test to see if it contains {{w|beryllium}} (a rarer element whose best-known natural form is as a component of {{w|emerald}}). Such analyses typically involve many instruments and steps to prepare the sample. However, Beret Guy seems to be able to identify all the elements the substance is composed of just by eyeballing it, making him perhaps the perfect elemental analysis instrument.

To confirm this, Megan asks Beret Guy what he sees when he looks at her face, expecting that a normal person would describe the arrangement of colors and features that they see. Since Beret Guy sees the atoms Megan is composed of (mostly {{w|Composition_of_the_human_body|oxygen, carbon and hydrogen}}) he only notices the unusual atoms. In this case he sees the metal atoms her {{w|Dental_restoration#Materials_used|dental fillings}} are composed of. This shows his "atomic vision" extends beyond the surface of the substances. Megan finds this bizarre and asks Beret Guy what is wrong with him. He states that he has always suspected he contains too much {{w|zinc}}, which he believes makes people think he is weird, thus missing Megan's point: what is weird is not Beret Guy's elemental content, but his ability to apparently see everything as atoms sorted by element.

High zinc intake ({{w|Zinc toxicity|zinc toxicity}}) can cause nausea, vomiting, pain, cramps and diarrhea. It also reduces copper absorption, which affects the immune system. However, it does not grant superhuman sensory abilities.{{Citation needed}} That is solely a function of [https://coppermind.net/wiki/Tin tin].

The comic continues the theme of Beret Guy's naive misunderstandings of scientific terminology turning to be literally true. In a previous [[1486: Vacuum|comic]] his misinterpretation of the notion of energy in the vacuum resulted in him gaining significant superpowers.

In the title text, the concept is taken even further: Beret Guy found his dad indistinguishable from a dog. This is likely because all mammals are essentially made of the same basic elements. Absent a distinguishing element from either his dad or the dog, they would appear to be the same. He could, however, apparently distinguish his mother because she contained {{w|plutonium}}. This is a very unusual occurrence that cannot possibly occur naturally in humans.{{Citation needed}} Some possible explanations are:
#She had an {{w|Radioisotope thermoelectric generator|RTG}}-powered pacemaker (a few hundred were made in the 1970s).
#She lived near Los Alamos during the second world war and was a member of the [http://warisboring.com/articles/the-scientists-who-pee-plutonium/ UPPU club (translated as “You pee Pu!”)]. Alternatively, she could have been exposed to another source such as {{w|radioactive contamination from the Rocky Flats Plant}}.
#She was one of {{w|The Stepford Wives}} robots.
#She was the victim of some unidentified, unethical medical experimentation. Such as {{w|Albert Stevens}}
It is also possible that Beret Guy's mother containing plutonium is probably intended as a whimsical explanation of his powers. The presence of plutonium in his mother may be the source of his own differences: radioactive exposure (in this case, potentially in utero) is a {{tvtropes|ILoveNuclearPower|common source of superpowers}} in comic books and other fiction (though unfortunately, this does not work in real life{{Citation needed}}). It's possible the plutonium is even in her womb, therefore basically guarenteeing his exposure to it.

It's not clear whether his mother's plutonium is related to his "too many zincs". One explanation for Beret Guy having too much zinc could be that his mother's plutonium changed into zinc through the process of {{w|radioactive decay}}.

It is worth noting that the verbs "recognized" and "had" in the title text are written in past tense. This presents the possibility that Beret Guy's mother passed away due to {{w|radiation sickness}} from exposure to the radiation originating from the plutonium in her middle. This possibility is further evidenced when Beret Guy adds "I never did ask her why...", indicating that he may no longer have the opportunity to do so. This is further corroborated by [[502: Dark Flow]], where Beret Guy also appears to miss his mother.

The English physicist {{w|Henry Moseley}} discovered the law relating the {{w|atomic number}} of elements with their {{w|characteristic x-ray|characteristic x-rays}} when bombarded by free electrons, providing physical evidence for the {{w|periodic table}}, the {{w|Bohr Model}} of the atom and the concept of {{w|atomic number}}. In doing so he developed a method of identifying elements in a substance by bombarding them in a vacuum with electrons and using {{w|x-ray diffraction}} methods to measure the resulting X-rays. A famous French chemist brought him a complicated mixture of {{w|Rare Earth element|Rare Earth elements}}, many of which had only recently been discovered, to test his method. Within a short time, Mosley amazed the chemist by identifying all the elements by number using his method and referring to his chart to name them. This comic may therefore be subtly alluding to this method by suggesting that Beret Guy's eyes can fire electrons at anything he looks at and "read" the resulting X-ray radiation, giving him the ability to identify the composite elements in a similar manner.

==Transcript==
:[Megan stands at a table and is preparing a sample for some kind of analysis in a device, when Beret Guy walks in.]
:Beret Guy: What're you doing?
:Megan: Testing a sample for beryllium.
:Beret Guy: That? Yeah, there's a bunch of berylliums.
:Megan: How do you know?

:[Megan turns to Beret Guy who takes the sample and looks at it.]
:Beret Guy: Look at it! See? Tons of oxygens and silicons, a few irons but definitely some berylliums too! Can't you see them?

:[They continue to talk.]
:Megan: No, I can’t see a list of the atoms in a thing by looking.
:Beret Guy: How do you tell what things are?

:[Zoom in on Megan.]
:Megan: This is ridiculous. Look at me. What do you see?
:Beret Guy (off-panel): You have tons of metal in your face. Lots of fillings, I guess?

:[Megan stares at Beret Guy who takes a looks at his own arm.]
:Megan: What's '''''wrong''''' with you?
:Beret Guy: Too many zincs? I’ve always worried I had too much zinc and everyone thought I was weird.

==Trivia==
*In the original version of the comic there was a typo in the title text, ''form'' instead of ''from'':
**I had trouble telling my dad apart '''form''' the dog.
Could possibly explain [[452: Mission]] if he believes all carbon based objects to be scones.

{{comic discussion}}
[[Category:Chemistry]]
[[Category:Comics featuring Beret Guy]]
[[Category:Comics featuring Megan]]
[[Category:Strange powers of Beret Guy]]

2936: Exponential Growth

2024-08-27T04:09:17Z

172.69.58.152: /* Transcript */

{{comic
| number = 2936
| date = May 22, 2024
| title = Exponential Growth
| image = exponential_growth_2x.png
| imagesize = 545x264px
| noexpand = true
| titletext = Karpov's construction of a series of increasingly large rice cookers led to a protracted deadlock, but exponential growth won in the end.
}}

==Explanation==

In this strip Black Hat begins by demonstrating {{w|exponential growth}}, using a variation of the {{w|wheat and chessboard problem}}, a classic demonstration of this mathematical principle. Exponential growth involves an initial quantity being multiplied by any number greater than one again and again. It can cause small numbers to compound into very large numbers faster than might be intuitive. This principle is important in a number of real life applications, ranging from biological growth to inflation to reaction kinetics.

The earliest versions of this story come from India and involve a man (the inventor of {{w|chess}}, in some tellings), being offered a reward by a king, and asking that a single grain of wheat (rice, in some versions) be placed on the first square of a chessboard, two on the second, and each subsequent square having twice as many grains as the one before. In the story, the king generally laughs off such a reward as being trivial, but soon learns that the reward would be impossible to pay. Since a chessboard contains 64 squares, the final square would contain 2^63 (approximately 9.2 quintillion) grains. This would be around 600 billion tonnes of wheat (even in modern times, would be centuries of global wheat production).

In some versions of the story, the man is executed for embarrassing the king/being over-greedy; in others, he's rewarded for his cleverness; in yet others he becomes king himself as a consequence. There are also other versions that [https://www.comedy.co.uk/radio/finnemore_souvenir_programme/episodes/7/5/ subvert the well-known tale] by the king not being so naïve as to fall for the 'trick' played by the creator of the problem.

[[Black Hat]] initially appears to be using this example, to demonstrate a mathematical principle, but actually turns out to be using it to "win" a chess match by covering the chess board in rice until his opponent quits out of frustration. Naturally, despite his claims that it's "nearly impossible to counter", under the International Chess Federation (FIDE)'s [https://www.fide.com/FIDE/handbook/LawsOfChess.pdf Laws of Chess], this would be illegal on several levels, as deliberately distracting or annoying your opponent is a violation, as is deliberately displacing the chess pieces. Black Hat being Black Hat, he likely simply doesn't care, and counts it as a win when his opponent stomps off out of annoyance.

{{w|Garry Kasparov}} and {{w|Antoly Karpov}} are both Russian chess grandmasters and former world champions. The two men famously competed for the world championship in the 1980s. The Kasparov gambit is an opening move in chess. The title text implies that Kasparov actually tried this method on Karpov, who attempted to consume all the rice with "increasingly large rice cookers", but eventually couldn't keep up. While this is obviously fictional, it fits with the principle of exponential growth. If exponential growth is unrestricted, it will eventually grow beyond the constraints of anything that could plausibly be built to contain it.

In any case, it appears that in his enthusiasm to enact his scheme, Black Hat has neglected to even set up his own pieces (or they have already been completely buried), never mind wait for the game to commence, so his opponent has nothing to resign from - indeed his king still appears to be standing as he walks away.

==Math==

The amount of rice collected on each square of the chess board is listed below. It all sums up to around 400 billion tons (or {{w|tonne}}s, the various distinctions being not so important), taking each grain as weighing approximately 0.02 grams. This is 500 times the annual world production.

The last day, alone, would require 200 billion tons. But the implicit nature of this doubling is that the amount of rice you put on at any stage is exactly equal to the amount of rice already on the board ''plus one extra grain''. So there were around 200 billion tons already, before the last square required a virtually identical additional amount.

* First row:
** a1: 1 grain
** a2: 2 grains
** a3: 4 ...
** a4: 8
** a5: 16
** a6: 32
** a7: 64
** a8: 128
* Second row
** b1: 256
** b2: 512
** b3: 1,024
** b4: 2,048
** b5: 4,096
** b6: 8,192
** b7: 16,384
** b8: 32,768
* First column of third to seventh rows
** c1: 65,536 grains (~ 1 kg)
** d1: 16,777,216 (~ 400 kg)
** e1: 4,294,967,296 (~ 100 tons)
** f1: 1,099,511,627,776 (~ 25,000 tons)
** g1: 281,474,976,710,656 (~ 6 million tons)
* Eighth row, in detail
** h1: 72,057,594,037,927,936 (~ 1.5 billion tons, more than the 2022 world harvest)
** h2: 144,115,188,075,855,872
** h3: 288,230,376,151,711,744
** h4: 576,460,752,303,423,488
** h5: 1,152,921,504,606,846,976
** h6: 2,305,843,009,213,693,952
** h7: 4,611,686,018,427,387,904
** h8: 9,223,372,036,854,775,808 (~ 200 billion tons)
* Total: 18,446,744,073,709,551,615

[https://upload.wikimedia.org/wikipedia/commons/e/e7/Wheat_Chessboard_with_line.svg Example on the chessboard (SVG diagram)]

==Transcript==

:[Black Hat is talking to Cueball standing next to him, arm raised.]
:Black Hat: Exponential growth is very powerful.

:[Closeup on Black Hat. Next to him is an image of the lower left part of a chessboard. The four leftmost squares in the bottom row have grains of rice on them -- one, two, four, and eight grains respectively.]
:Black Hat: A chessboard has 64 squares.
:Black Hat: Say you put one grain of rice on the first square, then two grains on the second, then four, then eight, doubling each time.

:[Black Hat has emptied a bag of rice on a chessboard. There are two additional bags next to him, each labeled "Rice", and a pile of rice already on the table. Some rice has spilled off, and a small pile of rice is growing at Black Hat's feet. A frustrated Hairy is walking away, fists clenched. On Hairy's side of the chessboard there is a white king and pawn.]
:[Caption above panel, representing Black Hat continuing to speak:]
:If you keep this up, your opponent will resign in frustration.
:It's called Kasparov's Grain Gambit. Nearly impossible to counter.

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Hairy]]
[[Category:Chess]]
[[Category:Math]]
[[Category:Food]]
[[Category:Comics featuring real people]]

Talk:892: Null Hypothesis

2024-03-26T21:17:08Z

172.69.58.152: Fixed my comment. ~~~~

If you get a 50% discount at two shops and buy stuff from both of them, you have a 100% discount. Math. That's how it works, bitches. '''[[User:Davidy22|{{Color|purple|David}}y²²]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 10:05, 9 March 2013 (UTC)
:I would feel entirely justified punching someone who said that unironically. Pennpenn [[Special:Contributions/108.162.249.205|108.162.249.205]] 00:59, 27 January 2015 (UTC)
:I mean, if the two items cost the same, then you would technically get a 100% discount on one. [[User:Beanie|Beanie]] ([[User talk:Beanie|talk]]) 13:31, 30 April 2021 (UTC)

That's a misleading thing about percentages. Like this:
Prices of coffee increase by 2% this year, then by 3% next year. That's a 1% increase between years, or a 50% increase between years (from 2 to 3). So which is it? 1 or 50?
[[Special:Contributions/141.101.98.240|141.101.98.240]] 08:26, 18 December 2013 (UTC)
:It's a 50% increase and an increase of 1 percentage point. There's a difference between the two. [[Special:Contributions/162.158.158.235|162.158.158.235]] 16:37, 23 April 2020 (UTC)

That's why they've invented the "base points" in financials, to denote the percentages of percentages. It's 1% absolute but 50bpp (base point percentage). [[Special:Contributions/108.162.246.11|108.162.246.11]] 18:35, 20 January 2014 (UTC)

Oh really. If you say it increased by 2% this year, then by 3% next year. It increased 3%. Unless you mean it will increase by 3% from LAST YEAR to NEXT YEAR. Then it really increased by 2% then .97%. But for this purpose let's throw that out and make it simple. It increased by 2% this year, and will increase by 3% next year. 50% isn't how much it increased, but how much the increase increased. That's called acceleration. The rate of increase per year is always 2 or 3%. So, 1% doesn't factor into this equation at all no matter how you do the math. The answer is 1.02*1.03. It increased by 5.06% over the last two years. [[Special:Contributions/108.162.216.114|108.162.216.114]] 14:59, 18 August 2014 (UTC)

Don't these discussion points belong in a different comic? Or perhaps the garbage? Except (1), he lol'd me. [[Special:Contributions/108.162.219.58|108.162.219.58]] 21:23, 5 February 2014 (UTC)

:They should be on [[985: Percentage Points]] or [[1102: Fastest-Growing]] --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 11:35, 23 October 2014 (UTC)

Every time I learn what the null hypothesis is, I forget about it by the next day. I guess my brain is trying to organize the information and it thinks the /dev/null/ folder would be a good place for it. [[Special:Contributions/172.69.58.152|172.69.58.152]] 21:17, 26 March 2024 (UTC)

2910: The Wreck of the Edmund Fitzgerald

2024-03-23T21:01:31Z

172.69.58.152: /* Transcript */

{{comic
| number = 2910
| date = March 22, 2024
| title = The Wreck of the Edmund Fitzgerald
| image = the_wreck_of_the_edmund_fitzgerald_2x.png
| imagesize = 463x672px
| noexpand = true
| titletext = You know that asteroid that almost destroyed Earth in the 90s? Turns out the whole thing was secretly created by Michael Bay, who then PAID Bruce Willis and Ben Affleck to look heroic while blowing it up!
}}

==Explanation==
{{incomplete|Created by ONE OF THE FBI'S MOST WANTED, FOR CRIMES AGAINST SHIPPING - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

The comic features [[Cueball]] identifiable as a {{w|minstrel}}, {{w|bard}} or {{w|Folk music|folk singer}}, performing a {{w|narrative song}} on a jetty. It parodies {{w|Gordon Lightfoot}}'s song '{{w|The Wreck of the Edmund Fitzgerald|The Wreck of the ''Edmund Fitzgerald''}}', recounting the fate of the {{w|SS Edmund Fitzgerald|SS ''Edmund Fitzgerald''}}, a vessel famously wrecked on the {{w|Great Lakes}} and thus a promising subject for a musical retelling. The words begin with some of the original lyrics of Lightfoot's song, but soon become a direct reference to the art of songwriting itself. Rather than describing the disaster itself, the song turns out to be a description of how the disaster occurred ''for the sake of'' the song.

In real life, the reason for sinking on {{w|Lake Superior}} is still unknown, but it's speculated that the ship's hull broke up in the rough waters of a storm.[https://www.youtube.com/watch?v=wIg90sVSwSE] This comic implies that the ''real'' reason for her sinking is that the songwriter bribed a mechanic to sabotage the ship into sinking, or misled the crew into making bad decisions, thus giving him sufficient material for a new song.

As a punchline, the verse goes on to reveal that another even greater maritime disaster, the {{w|Sinking of the Titanic|sinking of the RMS ''Titanic''}}, occurred for the sake of a {{w|Titanic (1997 film)|film}}. While the tale of Lightfoot causing the first disaster is feasible, since the song came out a few months after the accident, this second tale is not, since the director of the film, {{w|James Cameron}}, was born more than 40 years after the ''Titanic'' sank.

The title text continues this particular cycle by suggesting that an even bigger potential disaster was orchestrated {{tvtropes|RecycledInSpace|in space}}, as the real life basis for yet another film, ''{{w|Armageddon (1998 film)|Armageddon}}''.

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

:[Cueball is holding a guitar and singing on a pier. Two pairs of connected eighth notes are on the left and right of Cueball, as well as a detached eighth note on his right. Three seagulls fly in the background on his left. Four pillars of the pier and the water below it are also shown. Throughout the comic, alternate lines of the song are indented as indicated below.]
:Cueball:
:The ship was the pride
:of the American side
::It was due to set
::sail for Cleveland
:As the big freighters go,
:it was bigger than most
::With a crew and good
::captain well seasoned

:[Zoom on Cueball, without the pier, water, and seagulls. A pair of connected eighth notes to his right, a half note and a detached eighth note to his left.]
:Cueball:
:But taking a walk on
:the shore by the dock
::Was a songwriter named
::Gordon Lightfoot
:He was humming a tune
:but it didn't have words
::For it's challenging
::trying to write good

:[Close-up on Cueball's face. A quarter note and a pair of connected eighth notes to his right, a detached eighth note and a quarter note to his left.]
:Cueball:
:Poor Gordon sought glory
:but needed a story
::His career in folk
::music imperiled
:He mulled over this as
:he watched them do work
::On the hull of the
::''Edmund Fitzgerald''

:[Zoom back to second panel. A pair of connected eighth notes to Cueball's right, a separated eighth note and a pair of connected eighth notes to his left.]
:Cueball:
:Perhaps it was wrong,
:what he did for a song
::He should never have
::bribed that mechanic
:But his maritime crimes
:are no worse than the time
::Young James Cameron
::sank the ''Titanic''

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring real people]]
[[Category:Songs]]

Talk:2902: Ice Core

2024-03-05T00:05:41Z

172.69.58.152: τ for tortuosity? someone find an optics guy and get some equations...

Akin to [[2729: Planet Killer Comet Margarita]], which perhaps needs mentioning in the upcoming Explanation... [[Special:Contributions/162.158.74.118|162.158.74.118]] 23:04, 4 March 2024 (UTC)

Added a short explanation, but it'll definitely need more work. [[Special:Contributions/172.70.210.235|172.70.210.235]] 23:11, 4 March 2024 (UTC)

The title text raises a lot of questions. It's a play on the mixed drink Long Island Iced (or Ice) Tea of course. But why the underscore? Why does the T look funny (tau?)? Why isn't tea spelled out?[[Special:Contributions/172.69.6.189|172.69.6.189]] 23:44, 4 March 2024 (UTC)Pat
:Yes, Randall did use tau in the title text. I recently made mention of that in my most recent edit. I'm not sure why he used it but maybe instead of a "Gone Island Ice Tea", it's a "Gone Island Ice Tau"? [[User:OmniDoom|OmniDoom]] ([[User talk:OmniDoom|talk]]) 23:58, 4 March 2024 (UTC)

Tau is tortuosity in a lot of equations involving porous material (including ice), and also represents time in some engineering disciplines. It's written as "Ice_τ", and I have no idea what the oddly specific underscore is. Maybe it's "I x c x e" from some equation that involves τ? And somehow could be relevant to a sunken island? [[Special:Contributions/172.69.58.152|172.69.58.152]] 00:05, 5 March 2024 (UTC)