explain xkcd - User contributions [en]

1123: The Universal Label

2014-04-18T19:06:58Z

Beolach: /* Explanation */

{{comic
| number = 1123
| date = October 19, 2012
| title = The Universal Label
| image = the universal label.png
| titletext = Works for any grocery or non-grocery. Even thyme is just H and time.
}}

==Explanation==
All matter in the universe was created through {{w|nuclear fusion}} of hydrogen atoms over billions of years. A detailed explanation of this process is available [http://www.irregularwebcomic.net/3280.html here]. In many countries, food products must have their ingredients displayed somewhere on their packaging. Because all matter was originally created through stellar nuclear fusion from hydrogen over time, the ingredients of any item (food or otherwise) can technically be described fully as only being made from hydrogen and time.

There is a game called [http://newbrict.github.io/Fe26/ <nowiki>Fe[26]</nowiki>] that simulates fusion in a star to create elements, that is based on [http://gabrielecirulli.github.io/2048/ 2048], which is mentioned in [[1344: Digits]].

The title text is a pun on the words {{w|thyme}} (a herb) and time, as the two words are homophones. Also, the H is the chemical symbol for hydrogen. Of course, the word "thyme" can also be made by adding the letter "h" to the letters "tyme".

==Transcript==
:'''Ingredients:'''
:Hydrogen, Time

{{comic discussion}}
[[Category:Physics]]
[[Category:Language]]

1344: Digits

2014-04-18T18:19:51Z

Beolach: /* Explanation */

{{comic
| number = 1344
| date = March 19, 2014
| title = Digits
| image = digits.png
| titletext = It's taken me 20 years to get over skyline tetris.
}}

==Explanation==
[http://gabrielecirulli.github.io/2048/ 2048] is a popular browser-based game in which players must move tiles in a 4 by 4 grid with numbers on them. When two tiles of the same number touch they can be merged into one tile with a value of the two tiles combined. So when two 4-tiles touch and are merged they form one 8-tile. The player can move the tiles by pressing an arrow key (or swiping in a direction on the mobile version), which will move all the tiles in that direction. Every time the player makes such a move another tile will appear on a random cell. The goal of the game is to get a tile with the number 2048.

In the comic the room number can be seen as 4 tiles with the values 8, 2, 2 and 4. If these occur in the game the player can merge the two 2-tiles into one 4-tile. This will then cause two 4-tiles to lie next to each other, so these can be merged into one 8-tile. Finally, the two 8-tiles can be merged into one 16-tile.

[[File:8224.gif]]

This can be done in the opposite direction as well.

The title text refers to {{w|Tetris effect}}, which takes its name from the game {{w|Tetris}}. People who play Tetris for extended periods tend to imagine real-life objects (like skylines) as tetris landscapes and pieces. Randall, as many others,[http://s3-external-1.amazonaws.com/wootdesigncontestentries/fackoph/chicago_skyline_%28Tetris_Redux%29-q71p5a-s.jpg] apparently got hooked on Tetris so much when it came out that, for 20 years, he would look at city skylines and see Tetris-like patterns in it. Similarly, he has now been hooked onto 2048 and notices number patterns that would be desirable to obtain during the game.

Comics [[724: Hell]] and [[888: Heaven]] also refer to Tetris.

There is another game named [http://newbrict.github.io/Fe26/ <nowiki>Fe[26]</nowiki>] that simulates fusion in a star to create elements, as described in [[1123: The Universal Label]]. It is "Created by Dimitar Dimitrov and Kevin O'Connor for ASTR-1960@RPI. Based on 2048 by Gabriele Cirulli. Based on 1024 by Veewo Studio and conceptually similar to Threes by Asher Vollmer."

==Transcript==
:[A guy is walking and Cueball is following him.]
:Guy: The talk is in room 8224.
:Cueball: Ooh, nice.
:Guy: What?
:Cueball: ...Sorry. Nothing.

:Great, now I'll spend the rest of my life noticing numbers that would make good 2048 combos.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Video games]]
[[Category:Math]]

Talk:1047: Approximations

2014-04-17T19:14:56Z

Beolach:

They're actually quite accurate. I've used these in calculations, and they seem to give close enough answers. '''[[User:Davidy22|Davidy22]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 14:03, 8 January 2013 (UTC)

I only see a use for the liters in a gallon one. The rest are for trolling or simple amusement. The cosine identity bit our math team in the butt at a competition. It was painful. --[[User:Quicksilver|Quicksilver]] ([[User talk:Quicksilver|talk]]) 05:27, 17 August 2013 (UTC)

The 'Seconds in a year' ones remind me of one of my favorite quotes: "How many seconds are there in a year? If I tell you there are 3.155 x 10^7, you won't even try to remember it. On the other hand, who could forget that, to within half a percent, pi seconds is a nanocentury" -- Tom Duff, Bell Labs. [[User:Beolach|Beolach]] ([[User talk:Beolach|talk]]) 19:14, 17 April 2014 (UTC)

Annoyingly this explanation does not cover 42 properly, it does not say that Douglas Adams got the number 42 from Lewis Carroll, who is more relevant to the page because he was a mathematician named Charles Lutwidge Dodgson. He was obsessed with the number forty-two. The original plate illustrations of Alice in Wonderland drawn by him numbered forty-two. Rule Forty-Two in Alice in Wonderland is "All persons more than a mile high to leave the court", There is also a Code of Honour in the preface of The Hunting of the Snark, an extremely long poem written by him when he was 42 years old, in which rule forty-two is "No one shall speak to the Man at the Helm". The queens in Alice Through the Looking Glass the White Queen announces her age as "one hundred and one, five months and a day", which - if the best possible date is assumed for the action of Through the Looking-Glass - gives a total of 37,044 days. With the further (textually unconfirmed) assumption that both Queens were born on the same day their combined age becomes 74,088 days, which is 42 x 42 x 42. --[[Special:Contributions/139.216.242.254|139.216.242.254]] 02:43, 29 August 2013 (UTC)

:: This explanation covers 42 adequately, and would probably be made slightly worse if such information were added. The very widely known cultural reference is to Adams's interpretation, not Dodgson's original obsession. Adding it would be akin to introducing the MPLM into the explanation for the hijacking of Renaissance artists' names by the TMNT. I definitely concede that it does not cover 42 exhaustively, but I think it can be considered complete and in working order without such an addition. If it really irks you, be bold and add it! --[[User:Quicksilver|Quicksilver]] ([[User talk:Quicksilver|talk]]) 00:37, 30 August 2013 (UTC)

"sqrt(2) is not even algebraic in the quotient field of Z[pi]" is not correct. Q is part of the quotient field of Z[pi] and sqrt(2) is algebraic of it. The needed facts are that pi is not algebraic, but the formula implies it is in Q(sqrt(2)). --DrMath 06:47, 7 September 2013 (UTC)

13/15 is a better approximation to sqrt(3)/2 than is e/pi. Continued fraction approximations are great! --DrMath 07:23, 7 September 2013 (UTC)

How could he forget 1 gallon ≈ 0.1337 ft³?! [[Special:Contributions/67.188.195.182|67.188.195.182]] 00:51, 8 September 2013 (UTC)

Worth mentioning that Wolfram Alpha now officially recognizes the [http://www.wolframalpha.com/input/?i=e%5E-%28%281%2B8%5E%281%2F%28e-1%29%29%29%5E%281%2Fpi%29%29 White House switchboard constant] and the [http://www.wolframalpha.com/input/?i=%287%5E%28e-1%2Fe%29-9%29*pi%5E2 Jenny constant]. [[Special:Contributions/86.164.243.91|86.164.243.91]] 18:28, 8 October 2013 (UTC)

Maybe we should add the [Extension:LaTeXSVG LaTeX extension] to make it easier to transcribe these equations. -- [[Special:Contributions/108.162.219.220|108.162.219.220]] 23:02, 16 December 2013 (UTC)

;Protip - Does anyone see the correct equation?
Maybe this is just an other Wolfram Alpha error, like we recently have had here: [[1292: Pi vs. Tau]]. All equations still look invalid to me.
*''√2 = 3/5 + π/(7-π)'': is impossible because √2 is an irrational number and no equation can match.
*''cos(π/7) + cos(3π/7) + cos(5π/7) = 1/2'': could only match if ''cos(x) + cos(3x) + cos(5x) = 1/2'' would be valid, because ''π/7'' is also an irrational number.
*''γ = e/34 + e/5 or γ = e/54 + e/5'': would mean that a sum of two irrational numbers do fit to the Gamma Constant. Impossible.
*''√5 = 13 + 4π / 24 - 4π'': √5 and π are irrational numbers, there is no way to match them in any equation like this.
*''Σ 1/nn = ln(3)e'': doesn't make any sense either.
Maybe [[:Category:Comics featuring Miss Lenhart|Miss Lenhart]] can help.
--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:41, 17 December 2013 (UTC)

cos(π/7) + cos(3π/7) + cos(5π/7) = 1/2 is exactly correct.

Let a=π/7, b=3π/7, and c=5π/7, then
(cosa+cosb+cosc)⋅2sina=2cosasina+2cosbsina+2coscsina=sin2a+sin(b+a)−sin(b−a)+sin(c+a)−sin(c−a)=sin(2π/7)+sin(4π/7)−sin(2π/7)+sin(6π/7)−sin(4π/7)=sin(6π/7)=sin(π/7)=sina

Hence, cos(π/7) + cos(3π/7) + cos(5π/7) = sin(π/7) / 2sin(π/7) = 1/2
[[Special:Contributions/108.162.216.74|108.162.216.74]] 01:57, 16 January 2014 (UTC)

:What is this: sin(6π/7)=sin(π/7) ? A new math is born... --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 20:49, 16 January 2014 (UTC)

::Actually it does. My proof is geometric: the sines of two supplementary angles (angle a + angle b = π (in radians)) are equivalent because they necessarily have the same x height in a Cartesian plane. Look on a unit circle, or even a sine function. Also, Calculus and most other mathematics use radians over degrees because they make the functions simpler and eliminate irrationality when a trig function shows up, but physics uses degrees because it's easier to understand and taught first. Anonymous 01:27, 13 February 2014 (UTC)
::As an aside, just how far along in math are you? Radian measure is taught in high school (at least the good ones). Anonymous 13:24, 13 February 2014 (UTC)
:::Sure, I was wrong at my last statement. sin(6π/7)=sin(π/7) is correct by using the radian measure. But just change π/7 to π/77 would give a very different result on that formular here. I still can't figure out why PI divided by the number 7 should be that unique, PI divided by 77 should be the same. My fault is: I still can't find the Nerd Sniping here. And we all do know that Randall did use wrong WolframAlpha results here. According to the last question: I'm very well on Math, that's because I want to understand this. This is like 0.999=1. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 22:01, 13 February 2014 (UTC)
::::Ah, I see. I think it has to do with the way e^i*π breaks down, as one of the answers shown in the corresponding link explains, but other answers rely on various angle identities (including the supplementary sines one in the proof above). Anonymous 03:10, 14 February 2014 (UTC) (PS, have you checked [[545]] lately? I answered your question there, too)
:::::As per the derivation from january 16 , you can use any a,b,c that satisfies this set of equations: 2 a = b - a, a + b = c- a, c + a = π - a. This is due to the fact that sin(x) = sin(π-x), and what was derived the 16th. [[Special:Contributions/173.245.53.199|173.245.53.199]] 12:38, 21 February 2014 (UTC)

;So, still incomplete?

Where's our (in)complete judge? [[Special:Contributions/199.27.128.186|199.27.128.186]] 19:21, 18 December 2013 (UTC)
:The protip is still a mystery. I'm calling for help a few lines above. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:16, 18 December 2013 (UTC)

284: Tape Measure

2014-04-11T18:27:05Z

Beolach: /* Explanation */

{{comic
| number = 284
| date = July 2, 2007
| title = Tape Measure
| image = tape_measure.png
| titletext = This sequence was later reproduced in the International Tape-Extending Federation archives, retitled 'The Founding of the Sport'.
}}

==Explanation==
[[Cueball]] acts like a small boy, finding a tape measure and then playing with it. He then extends it to 8 feet (approx. 2.5 meters), wondering whether or not that was a record, which makes him imagine a sport where extending the tape measure as far as possible was the goal. (Tape measure strips are bent upward lengthwise to support itself when oriented correctly, much like how one can better hold a sheet of paper horizontally by creating a slight dip. However, as a tape measure is extended, the weight of the strip eventually overcomes the support offered by the bend, causing it to collapse. Skillfully holding the tape measure at an angle can redirect some of the weight load and allow for a longer total extension; it is implied that this technique can be explored to the point of becoming its own sport.)

The title text refers to a future where this sport exists and this comic is a representation of the origin of this sport.

During the real-life meet-up at the time & place mentioned in [[240: Dream Girl]], fans [http://thephoenix.com/Boston/News/48208-wisdom-of-crowds/ participated in a tape-measure length competition].

==Transcript==
:[Cueball finds a tape measure.]
:Cueball: Hey, a tape measure.

:[Cueball extends the tape measure.]
:''extend extend''

:[The tape measure falls.]
:''clatter''

:[Cueball tries again.]
:''click''
:''schwoop''

:''extend extend''

:''extend''

:Cueball (thinking): Ooh, eight feet. I wonder if that's a record.

:[Cueball imagines an olympic stadium, with three people extending tape measures]
:Audience: ''Gooo! Goooo! Gooooooo!''

{{comic discussion}}
[[Category:Comics featuring Cueball]]

Talk:202: YouTube

2014-03-31T22:18:56Z

Beolach:

In the transcript, it says simpleplan2009's comment was posted 3 minutes ago. However, in the image, it clearly says 5 minutes. [[User:Caagr98|Caagr98]] ([[User talk:Caagr98|talk]]) 19:01, 17 April 2013 (UTC)
:I agree. In theory a 3 and a 5 could be hand-written to be hard to differentiate, but here it is clear. Changed. (And added the first line.) [[User:Markhurd|Mark Hurd]] ([[User talk:Markhurd|talk]]) 10:56, 19 April 2013 (UTC)
::Changed it back, as the actual transcript on the comic page (as seen in the webpage source, and upon which the comic searches are based) says "3". I've added the reasoning in the explanation. [[User:NixillUmbreon|NixillUmbreon]] ([[User talk:NixillUmbreon|talk]]) 15:31, 20 January 2014 (UTC)
:::The image is the first source for the transcript here. Randall's transcript simply doesn't match the image.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 22:11, 20 January 2014 (UTC)

On Gunpistolman's comment, is [http://www.phys.ufl.edu/~det/phy2060/heavyboots.html the heavy boots story] worth a mention? [[User:B jonas|B jonas]] ([[User talk:B jonas|talk]]) 16:31, 1 November 2013 (UTC)
:Not needing a mention in the explanation, but thank you for the link. Richard Feynman would be glowing in his grave at the state of science education in this country. {{unsigned ip|108.162.219.223}}

The British sketch comedy TV show ''That Mitchell and Webb Look'' has an excellent [https://www.youtube.com/watch?v=P6MOnehCOUw Moon Landing Sketch] with similar humor to this joke. [[User:Beolach|Beolach]] ([[User talk:Beolach|talk]]) 22:18, 31 March 2014 (UTC)

381: Mobius Battle

2014-03-20T21:48:28Z

Beolach: /* Explanation */

{{comic
| number = 381
| date = February 8, 2008
| title = Mobius Battle
| image = mobius battle.png
| titletext = Films need to do this more, if only to piss off the people who have to feed it into the projector.
}}

==Explanation==
[[File:mobius battle.gif|right|frame|The Möbius comic strip as an animated GIF.]]
A {{w|Möbius strip}} is an object with only one surface and one edge. It can be simulated in our universe by taking a strip of paper and twisting it 180 degrees before attaching both ends together.

The idea of the Möbius strip has been used here to create a comic strip that could potentially loop forever. In it, a man is standing in front of a ball. Then another man runs in and kicks the first man out of the panel. The second man then turns away, retaining the first man's original position, only flipped horizontally. Because of the nature of the Möbius strip, if the comic strip were to be printed out in such a way that the comic could be seen on both sides of the paper, the comic would repeat, so that the second man would become the first man, and someone else, potentially the original first person, would push them out of the comic becoming himself the first man.

The comic's viability as a Möbius strip is preserved the use of symmetrical letters in a palindromic word to denote laughing ("HAHAHAH") as well as using symmetrical punctuation for the other character's [http://en.wiktionary.org/wiki/grawlix#English grawlixes.] A similar use of a Möbius strip in story-telling can be seen in [https://www.youtube.com/watch?v=4mdEsouIXGM Wind and Mr. Ug] by Vi Hart.

Finally, at the title text, [[Randall]] jokes that he would like to see actual films do this solely as a joke on projectionists, who would have no way to feed a Mobius strip film reel properly into a normal projector.

==Transcript==
:[A man is standing next to a ball, a flash appears on the left side of the panel.]
:[Another man comes in from the left, preparing to kick the ball.]
:[The other man kicks the ball into the first man's head.]
:[The first man is lying outside of the frame, second man points and laughs.]
:Second man: HAHAHAH
:First man: <nowiki>!#^*!*</nowiki>
:[Second man is now standing next to the ball.]
:[To the right, the strip above is looped around like a film strip, but a one-half-turn is put into the loop to make it a Mobius strip.]

{{comic discussion}}
[[Category:Comics featuring Cueball]]

633: Blockbuster Mining

2014-03-20T21:09:19Z

Beolach: /* Explanation */ - added a paragraph for the title text

{{comic
| number = 633
| date = September 7, 2009
| title = Blockbuster Mining
| image = blockbuster mining.png
| titletext = The 2007 Bridge To Terebithia trailer put me off too much to see that particular movie, but I am cautiously optimistic about Where The Wild Things Are.
}}

==Explanation==
[[Cueball]] has acquired the {{w|intellectual property}} rights to produce a movie, but is unsure of how to make it appealing to a wide audience. An off-screen character suggests hiring {{w|Michael Bay}}, a director and producer well known (and occasionally criticized) for his style of film adaptation. Cueball is unsure that the IP would be a good fit for a summer blockbuster, but is dismissed.

The following panels depict violent and gritty scenes from a spy thriller, starring an unknown and brutal female spy. In the last panel, she is revealed to be {{w|Harriet the Spy}}, the 11 year old protagonist of a bestselling children's book written by Louise Fitzhugh, as well as other spinoff books written by various other authors.

The comic references Hollywood's search for new stories to adapt to film, and how poor (not to mention {{w|Hansel & Gretel: Witch Hunters|violent}}) some of these adaptations can be. There is additional humor in the fact that the original novel is about school-child concerns such as friends and is not violent.

The {{w|Bridge to Terabithia (2007 film)|film adaptation}} of {{w|Bridge to Terabithia (novel)|Bridge to Terabithia}} had trailers that made it appear to have very little in common with the themes and tone of the novel. The actual movie is one of Hollywood's better book adaptations, but the trailers were extremely misleading & off-putting to fans of the novel, as in the title text. Viewers who were unfamiliar w/ the novel & saw the movie w/ expectations based on the trailer were also unprepared for the actual movie. The trailer was essentially every single special-effect shot from the movie, giving the impression it was a special-effects extravaganza, which would have been very inappropriate based on the novel, and does not reflect the actual content of the movie.

==Transcript==
:Cueball: We've acquired some new rights, but I'm not sure it's in the spirit to make it a blockbuster-
:Voice: Do it anyway. Take $100 million, hire Michael Bay.
:Cueball: But--
:Voice: ''NEXT!''

:[Panel is inverted, white on black background.]
:Harriet: They said if I were captured I should take my own life.
:Harriet: But I'd just as soon take yours.
:[Harriet is pointing two handguns at two men with machine guns.]

:''BOOM''
:[Harriet explodes off a cliff, carrying a rectangular object and a gun. In the background is a helicopter, some mountains, and the sea.]

:[Panel is inverted, white and red on black background.]
:Man: Stop! I'll talk!
:Harriet: No, I know everything, this is just for fun.
:[Harriet is holding a bloody pipe. Man is tied to a chair. There is blood pooling on the ground under the chair.]

:[Crosshairs follow a man.]
:Harriet: I'll be watching.

:[The panel is inverted colour, white on black.]
:Harriet
:the
:[in red] ''SPY''
:[A bloody spiral notebook, with blood streaks leading from it.]

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics with color]]

780: Sample

2014-02-10T22:00:10Z

Beolach: /* Explanation */ - Adding details on the title-text

{{comic
| number = 780
| date = August 16, 2010
| title = Sample
| image = sample.png
| titletext = There are two or three songs out there with beeps in the chorus that sound exactly like the clock radio alarm I had in high school, and hearing it makes me think my life since junior year has been a dream I'm about to wake up from.
}}

==Explanation==
This strip suggests that even a band with the most brilliant and catchy music would soon become the most hated band in the world if it included sound effects of car horns, cell phones, or alarm clocks in its songs. Listeners would mistake the sound effects for the real thing.

For comparison, "{{w|Indiana Wants Me}}", a 1970 hit single by {{w|R. Dean Taylor}}, had the sound of police sirens removed from later pressings because drivers were reportedly mistaking the sound effects for actual police cars and pulling over.

This can also be a reference to an unusual anti-piracy method, where P2P and Torrent networks are seeded with altered copies of songs that contain obnoxious sounds at random points.

The title-text refers to the common sensation of having sounds from the real-world incorporated into a dream, especially as one is waking up. This gives a (false) sensation that is the reverse of the dream described in [[557: Students]].

==Transcript==
:HOW TO BECOME THE MOST HATED BAND IN THE WORLD:
:Record an album that's nothing but brilliant, catchy instant classics guaranteed popularity and airtime,
:[Cueball at the steering wheel of a car.]
:Music: So far from hooome but I can't sto— HONK
:Cueball: AUGH! WHAT?
:With a sample of a car horn, cell phone, or alarm clock inserted randomly in each song.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Music]]

1123: The Universal Label

2013-05-20T17:47:55Z

Beolach: /* Explanation */ - Add link to Irregular Webcomic #3280

{{comic
| number = 1123
| date = October 19, 2012
| title = The Universal Label
| image = the universal label.png
| titletext = Works for any grocery or non-grocery. Even thyme is just H and time.
}}

==Explanation==
All matter in the universe was created through {{w|nuclear fusion}} of hydrogen atoms over billions of years. A well written, detailed explanation of this process is available [http://www.irregularwebcomic.net/3280.html here]. In many countries, food products must have their ingredients displayed somewhere on their packaging. Because all matter was originally created through stellar nuclear fusion from hydrogen over time, the ingredients of any item (food or otherwise) can technically be described fully as only being made from hydrogen and time.

The title text is a pun on the words {{w|thyme}} (a herb) and time, as the two words are homophones. Also, the H is the chemical symbol for hydrogen. Of course, the word "thyme" can also be made by adding the letter "h" to the letters "tyme".

==Transcript==
:'''Ingredients:'''
:Hydrogen, Time

{{comic discussion}}
[[Category:Physics]]