explain xkcd - User contributions [en]

66: Abusive Astronomy

2014-08-13T22:35:07Z

AKohn: /* Explanation */

{{comic
| number = 66
| date = February 20, 2006
| title = Abusive Astronomy
| image = abusive_astronomy.jpg
| titletext = Medium: Pencil on paper
}}
==Explanation==
A asterism is a pattern of stars which form some sort of perceived shape in the night sky. Some of these are patterns are used to name regions of the sky, as constellations. Modern astronomy organises the sky into 88 constellations, but different cultures saw different patterns in the same night sky, going back at least as far as the Babylonians and there are many other patterns and grouping of stars. The {{w|Pleiades}}, {{w|Orion's belt}} and the {{w|Big Dipper}} are among the most common asterisms that we recognize today and are among the first taught to people with an interest in astronomy. The Pleiades is an open star cluster in the constellation of Taurus, it is a group of stars which formed from the same nebula, and are moving together. Orion's belt consists of three stars which appear close in the sky, but are in fact at great distance from each other. The Big Dipper is part of the constellation Ursa Major. It can be used to help find the north pole star {{w|Polaris}} which is an aid to night-time navigation.

During planetarium tours, the tour guide will point out popular constellations and stars, sometimes they will ask a question to get the audience involved in the presentation. Usually these people are big on showing the wonder of the galaxy and are all smiles, but people have bad days. The comic is presenting an especially aggressive way of introducing the night sky.

When astronomers in the Northern Hemisphere are showing stars to people, there will frequently be someone who points to the Pleiades and says, "There's the Big Dipper!" (both appear as a trapezium of stars, with a handle, though the Pleiades is much smaller). This gets frustrating about the 100th time that you encounter this error. So, this comic could show someone releasing their frustration on the misinformed public by pointing out that what they just pointed at is actually the Pleiades. Then, pointing out that you can always locate the Pleiades by following the line of the stars in the belt of Orion. Then, pointing out the REAL Big Dipper.

In the title text, [[Randall]] explains that he drew this comic as a line drawing on white paper, using only a pencil. The image was later inverted for publication.

==Transcript==
:Identifying star clusters:
:[Image of a star cluster.]
:This is the Pleiades, asshole.

:Orion's Belt:
:[Image of Orion's Belt.]
:Only a moron couldn't find it.

:This is the Big Dipper:
:[Image of the Big Dipper.]
:What the hell is wrong with you?

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Astronomy]]

135: Substitute

2014-05-18T02:30:36Z

AKohn:

{{comic
| number = 135
| date = July 31, 2006
| title = Substitute
| image = substitute.png
| titletext = YOU THINK THIS IS FUNNY?
}}

==Explanation==
This comic refers to the film ''{{w|Jurassic Park (film)|Jurassic Park}}'', a 1993 movie based on the 1990 novel by {{w|Michael Crichton}}. The film centers around a billionaire who bought an island and opened a zoo or theme park for dinosaurs which he has cloned from DNA recovered from blood found in fossilized mosquitoes. Naturally, everything goes haywire, and several of the creatures, among which are the {{w|Velociraptor}}s subject of this comic, try to devour every human in the theme park.

Velociraptors (often shortened to "raptors") are a species of relatively small, carnivorous {{w|dinosaur}} which play a central role in the original film, as well as its sequels. In the film, herds of Velociraptors antagonize the main characters at various points, even entering buildings. According to newer researches, the Velociraptors in the film were erroneously based on the {{w|Utahraptor}} species of dinosaur. Unlike the movie, in which they are depicted as having a reptilian skin, both species of dinosaur in reality are theorized to have been feathered. The word "raptor" also refers to modern {{w|Bird of prey|birds of prey}}.

[[Randall]] is asked to substitute for [[Miss Lenhart]] in math class. The first page of the test he devises contains three questions, which have the recurring theme of humans running from said velociraptors. As Randall says in the comic: “This material is more vital than anything you've ever learned,” the joke being that Randall is somehow fearful that such a thing could happen.

Velociraptors, and in particular, the irrational fear of being attacked by them in the modern world, [[:Category:Velociraptors|appear several times]] in [[xkcd]]. This is the second such instance, the first is [[87: Velociraptors]]

==Transcript==
:[In a class room, the board says "Math" on the top-left corner, and "Mr. Munroe" in the middle. A stick figure is standing in front of it, speaking to the class.]
:Randall: Miss Lenhart couldn't be here today, so she asked me to substitute.
:Randall: I've put out your tests. Please get started.

:[A student in the first row raises the exam paper and says.]
:Student: Mr. Munroe, Miss Lenhart never taught us this.

:Randall: That's because Miss Lenhart doesn't understand how important certain kinds of math are.
:Student: But this just looks--
:Randall: This material is more vital than anything you've ever learned
:Student: But--
:Randall: No buts.

:Randall: This is a matter of life and death.

:[Excerpt from the exam paper.]
:<tt>Name: _________</tt>

:[A stick figure is standing, hands over head. A velociraptor is running towards it.]

:<tt>1. The velociraptor spots you 40 meters away and attacks, accelerating at 4 m/s^2 to its top speed of 25 m/s. When it spots you, you begin to flee, quickly reaching your top speed of 6 m/s. How far can you get before you're caught and devoured?</tt>

:<tt>2. You're at the center of a 20m equilateral triangle with a raptor at each corner. The top raptor has a wounded leg and is limited to a top speed of 10 m/s.</tt>

:[A stick figure is shown in the above situation. The picture has a legend "<tt>(Not to scale)</tt>".]

:<tt>The raptors will run toward you. At what angle should you run to maximize the time you stay alive?</tt>

:<tt>3. Raptors can open doors, but they are slowed by them. Using the floor plan on the next page, plot a route through the building, assuming raptors take 5 minutes to open the first door and halve the time for each subsequent door. Remember, raptors run at 10 m/s and they do not know fear.</tt>

==Trivia==
*Answers to the first two questions can be found in [http://fora.xkcd.com/viewtopic.php?f=7&t=120&start=40 this topic] on the forum board.

{{comic discussion}}
[[Category:Comics featuring Miss Lenhart]]
[[Category:Comics featuring Randall Munroe]]
[[Category:Comics featuring real people]]
[[Category:Comics with color]]
[[Category:Velociraptors]]

915: Connoisseur

2014-04-07T19:52:49Z

AKohn: /* Explanation */

{{comic
| number = 915
| date = June 22, 2011
| title = Connoisseur
| image = connoisseur.png
| titletext = Our brains have just one scale, and we resize our experiences to fit.
}}

==Explanation==
[[White Hat]] is fond of good wine, and he can distinguish slight differences in different types of wine. On the other hand, [[Cueball]] doesn't mind a kind of wine or another; all of them taste the same for him. When White Hat tells Cueball that he should pay more attention to types of wine, Cueball answers that wine is not different than anything else in this respect, and chooses pictures of {{w|Joe Biden}}, {{w|Vice President of the United States}}, eating a sandwich as an example.

In the last panel, apparently White Hat and Cueball are actually running an experiment to see if people will concentrate on slight differences among pictures of Joe Biden eating a sandwich, just in the same way that White Hat concentrates on slight differences among kinds of wine. The result of the experiment is clearly going to Cueball's side.

The title text presents the same idea in a different wording. The "scale of our brains" refers to a concept similar to Richard Dawkins' {{w|Middle World}}, where things too small (say, smaller than the point of a pin) or too big (bigger than what we can see from a mountaintop) are just out of our comprehension, so the things our brains understand must be neither too small nor too big, i.e. the "middle world".

However, the title text goes further in this idea: When we find things too big (like the distance to the Moon), we shrink it so that it fits into the "middle world" we're used to. Conversely, when we find things too small (say, a mote of dust), we expand it for the same reason. In a quite similar way, if all we have is pictures of Joe Biden eating a sandwich, we "resize" that subject so that we can fill books with the details about the pictures.

==Transcript==
:[White Hat is standing with Cueball. They each hold a wine glass in one hand, White Hat is holding a bottle of wine in the other. He looks at the label.]
:White Hat: How do you stand this cheap wine?
:Cueball: Wine all tastes the same to me.

:[Close-up of White Hat.]
:White Hat: You've just never had ''good'' wine. If you paid more attention, you'd realize there's a whole world here.

:[Close-up on the other man, who spreads his arms, sloshing his wine slightly.]
:Cueball: But that's true of ''anything!'' Wine, house music, fonts, ants, Wikipedia signatures, Canadian surrealist porn—
:Cueball: Spend enough time with any of them and you'll become a snobby connoisseur.

:[This panel has no border and is next to but aligned further down than the first three panels.]
:[The full frame of the two characters again. White Hat now has the bottle at his side.]
:White Hat: But some things do have more depth than others.
:Cueball: If you locked people in a box for a year with 500 still frames of Joe Biden eating a sandwich, by the end they'd be adamant that some were great and some were terrible.
:White Hat: You're exaggerating.
:Cueball: Oh yeah?

:[This panel is below the others, and is indented about a third of the way to the right. It is wide.]
:A YEAR LATER:
:[A box. Voices emanate from inside.]
:Voice #1: Sure, most closed-mouth frames are boring, but in #415, the way the man's jaw frames the mayo on his hand is pure perfection, and—
:Voice #2: What a surprise- ''you'' praising a mayo frame. Listening to you, I'd think there was nothing else in The Sandwich. Frankly, the light hitting J.B.'s collar through the lettuce would put #242 in my top ten even if he had ''no'' mayo on his hand at ''all''.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring White Hat]]
[[Category:Politics]]

1108: Cautionary Ghost

2014-03-24T23:48:26Z

AKohn:

{{comic
| number = 1108
| date = September 14, 2012
| title = Cautionary Ghost
| image = cautionary_ghost.png
| titletext = But then the Ghost of Subjunctive Past showed up and told me to stay strong on 'if it were'.
}}

==Explanation==
This comic is a comment on the futility of arguing over the commonly mocked usage of the word "literally" to mean "figuratively, with great emphasis." The comics [http://www.explosm.net/comics/2923/ Cyanide & Happiness] and [http://www.theoatmeal.com/comics/literally Oatmeal] are examples of this sort of derision.

The comic employs the device used in {{w|Charles Dickens}}'s ''{{w|A Christmas Carol}}'', in which the ghosts of Christmas past, present, and future awaken the main character in the middle of the night to show him the negative causes and effects of his selfish and uncharitable behaviour.

The similarity between the two "different" futures suggests that the man's struggle to get people to stop using "literally" incorrrectly will have no meaningful effect on the world, and so the man (and by extension, everyone else) may as well stop wasting time and energy on it.

The title text indicates that a second apparition encouraged the man to continue the fight on a different grammatical issue: the use of the phrase "if it were," which is frequently incorrectly substituted with "if it was." {{w|English_subjunctive#Use_of_the_past_subjunctive|'Subjunctive past tense'}} is most commonly used in a counterfactual condition (i.e. when referencing something that is not the case). For example, the sentence "If I were rich, I wouldn't have to work for a living," contains the prescribed usage. However, some people would phrase this sentence as: "If I 'was' rich, I wouldn't have to work for a living." This usage grates on the ears of many people -- including, apparently, the man in the comic. The comic appears to suggest that "if I were" is a more important issue than the incorrect usage of the word "literally."

Another xkcd comic, [[725: Literally]], also refers to the overly mocked usage of "literally."

==Transcript==
:[A man wakes up to an apparition hovering over their bed.]
:Apparition: OOOOOOOOOOOOooooo
:Man: A ghost!?
:Apparition: I bring a cautionary vision of things to come!
:Apparition: This is the future:
:[Two people are standing between a pair of houses. There is a tree. An airplane flies past.]
:Apparition: And this is the future if you give up the fight over the word "literally":
:[Two people are standing between a pair of houses. There is a tree. An airplane flies past. The cynical might suggest the panel is copy pasted.]
:[Back to the man in bed. ]
:Man: They looked exactly the same.
:Apparition: OOOOOOOOOOOooooo
:Man: Ok, I get it.
:Apparition: Seriously, this is duuuuumb .

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

821: Five-Minute Comics: Part 3

2014-01-26T00:07:26Z

AKohn: /* Explanation */

{{comic
| number = 821
| date = November 19, 2010
| title = Five-Minute Comics: Part 3
| image = five minute comics part 3.png
| titletext = Resulting in The Little Rock 9x + C.
}}

==Explanation==
This is the third and final "five-minute comics" post Randall made during November 2010. The introduction to the comic explains everything you need to know about the circumstances behind it.

*{{w|Pearl Harbor}} is a US Navy base that was {{w|Attack on Pearl Harbor|attacked}} in 1941 by Japanese airplanes, which prompted the US to join World War II. Of the attacks, Japanese Admiral Isoroku Yamamoto is claimed to have said "I fear all we have done is to awaken a sleeping giant and fill him with a terrible resolve" (although this claim is disputed, as the quote first appeared in the 1970 film ''Tora! Tora! Tora!'' and isn't substantiated by any sources that would have heard him say it).
:The attacks were made on ''December'' 7, 1941, not November 7. Thus, Randall is correct in depicting a Navy base going about its usual business.

*{{w|Breastfeeding in public}} is a touchy subject in parts of the world. In the US, it is considered by some to be inconsiderate to others who would prefer not to see such a display. Of course, women breastfeeding in public are generally feeding their infants, not other adults. The situation presented in the comic is an absurd exaggeration of the debate.

*"s" is the command in {{w|sed}} to perform a pattern search-and-replace; the syntax has also been adopted by other text-processing utilities, including {{w|Perl}} (a favorite subject of xkcd), and has entered into the geek lexicon as something that could appear in general conversation. The specific command "s/I think that/I saw a study once that said/g" means "Find all occurrences of the phrase 'I think that', and replace it with the phrase 'I saw a study once that said'." This will, indeed, improve the persuasiveness of an article, as the existence of scientific evidence will make people more likely to believe what's said, while most people won't even think to actually look up the study in question.

*Arson is the crime of intentionally setting fire to a structure. {{w|Billy Joel}} will no doubt claim {{w|We Didn't Start the Fire|he didn't start the fire}}.

*Coca-Cola is a fizzy cola-flavored soft drink, commonly abbreviated as "coke." {{w|Pop Rocks}} are a candy that contain tiny bubbles of gas, so that as the sugary candy dissolves on your tongue, it creates a popping sensation. For a long time, it was claimed that drinking the two together would cause one's stomach to explode; this was finally put to rest as some people (the Mythbusters in particular) started actually trying it, and discovered that nothing happened.
:Randall, of course, just thinks outside the box.

*After ''{{w|Brown v. Board of Education}}'' ruled that schools could not segregate based on race, nine African American students from Little Rock, Arkansas enrolled in the previously-segregated Little Rock Central High School. The school board could not officially deny them attendance, but members of the community (and, after Arkansas governor Orval Faubus intervened, the Arkansas National Guard) formed a blockade to physically prevent them from entering the school building. The governor claimed this was within his power even after ''Brown v. Board'', because the students were enrolled without issue, they were just physically blocked from entering the school building. After determining that the right to enroll in a school does, implicitly, include the right to actually attend classes there, president Eisenhower ordered the 101st Airborne Division to accompany the students and force the National Guard to stand down, thus integrating the school. This incident became known as the {{w|Little Rock Nine}}.
:However, {{w|Integral|integration}} also has a meaning in mathematics. This is indicated in the comic with the soldiers lifting up a giant integral sign to place beside the school, in order to (mathematically) integrate it. Normally, an integral only makes sense on functions; however, since this is the Little Rock ''Nine'', if we take the integral of the constant function ''f''(''x'') = 9, we do, in fact, get 9''x'' + ''C'', as stated in the title text.

*Cell phones with advanced computing capabilities, typically at least requiring fully-featured Internet browsing, multimedia capabilities, and the ability to run software applications, are called "smartphones." Most cell phones also have a "vibrate" function that allows someone in a public situation to receive calls without alerting others; the phone will discreetly vibrate rather than activate a ringtone, thus privately notifying the owner that a call is incoming. A semi-common problem with this feature is that a vibrating phone on a table that has a slight slope will slowly - or, if the slope is bad enough, rather quickly - slide down the slope, possibly falling off the table and breaking. If our smartphones ever decided to kill us, this would possibly be their only method of attack.
**Randall later covered this in his [[what if?]] blog. [http://what-if.xkcd.com/5/]

*The Three Little Pigs is a children's fairy tale about three pigs who build their houses out of, respectively, straw, sticks, and bricks. A wolf comes along and eats the pigs living in the straw and stick houses, but he can't knock down the brick house, because his only method for breaking them down is to blow on them until the material falls to pieces. The moral is something of an understated {{w|Murphy's law}}, that is, plan for the worst (getting your house knocked over) and it won't happen. Of course, a standard brick house is ''no'' match for the ''worst'' possible thing that could happen, the wolf dropping a nuke down the chimney.
:The 119 Little Pigs seems to be a variant where the pigs build their houses out of the 119 chemical elements. The 38th little pig builds his house out of {{w|strontium}}, which is, of course, the 38th element on the Periodic Table. One wonders what happened to the pigs who are stuck making their houses out of elements that are gaseous or liquid at room temperature, or those whose houses would react with the air and/or undergo nuclear decay.
:Although given the water content in exhaled breath, it's {{w|Alkali metal#Reaction with water (alkali metal hydroxides)|easy to see}} how the wolf would huff, puff, and blow down the houses made of {{w|lithium}}, {{w|sodium}}, {{w|potassium}}, {{w|rubidium}}, {{w|caesium}}, and {{w|francium}}. Though making a houses out of hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine and krypton would all be very difficult as they are gasses at room temperature. Also, there would be issues such as death from the toxicity of the elements, e.g. fluorine would kill the fox. The piggies may have difficulty collecting enough metal, as they would have trouble collecting enough Technetium (43), which doesn't naturally occur, and Astatine, of which approximately 1 ounce exists on earth.

*"Fastest gun in the West" is a boast commonly made in Western movies, where it is used to mean that a person is the fastest at drawing his gun in a duel (or, alternatively, can fire his gun the fastest). It doesn't actually describe the gun itself, and certainly doesn't describe how fast the gun can gallop across the land.

*"It's what separates the ''men'' from the ''boys''" is a phrase used to describe "macho" activities that, apparently, only "real men" will participate/do well in; all the other men haven't grown up yet, and are thus "boys." {{w|Centrifuge}}s are used to rapidly separate a material from the liquid it's suspended in, so apparently they can also be used to separate men from boys.

*Narnia is the mythical land in ''{{w|The Chronicles of Narnia}}''. In the books, time passes differently in Narnia, such that one can spend many years in Narnia and come out to find that almost no time at all has passed on Earth; conversely, during a short trip back to Earth, hundreds of years could pass in Narnia. {{w|Lucy Pevensie|Lucy}} is taking advantage of this by putting a computer in Narnia to perform extremely fast computation. {{w|Folding@home}} and {{w|SETI@home}} are distributed computing projects that aim to solve extremely large computational problems by pooling together computer resources of thousands of home computers who volunteer for the project; Folding@home looks at how proteins are folded, which has applications in medical science, and SETI@home analyzes EM waves from space, looking for signs extraterrestrial intelligent life amongst the cosmic background noise. Running through all of that data in a few hours would be quite an accomplishment indeed, although, as Peter points out, the idea has many problems:
**The book was written in 1957 and it occurs even earlier than that, long predating personal computers, so Lucy shouldn't even have one.
**Even if it occurs in an alternate universe where the PC was invented before 1957, the storage that would be needed to store the entire Folding@home and SETI@home databases would be far beyond her means, since the characters in the book are foster kids who don't have any money.
**Even if she somehow pulled that much storage space together, the time needed for one computer to run through those databases is on the order of millennia. A computer would not continuously run for that long without careful treatment, which Narnia is not equipped for.
**Even if we handwave around that issue (''"Aslan, use your power to keep all dust away from this computer for the next ten thousand years, please"''), the wall socket powering the computer is on the Earth side. Mains power outlets in the UK provide alternating current with an amplitude of 230 volts and a frequency of 50 hertz. The 50Hz part is what's important here: all devices designed to work with UK mains power expect a 50Hz sine wave. The time difference between Earth and Narnia would substantially elongate the sine wave in a method similar to the Doppler effect, which would probably prevent the computer from functioning at all, though ignoring this, the electricity costs would be too high.
**The time differential doesn't occur while people are entering/exiting Narnia (though they do occur while the wardrobe's open) or the Pevensie children would have had had some difficulty surviving the transition. Since the cables of the computer are crossing between the worlds, it seems unlikely that the time differential is even active yet.

*''{{w|The Honeymooners}}'' is a classic American sitcom. The show stars Ralph and Alice Kramden, and Ralph frequently makes empty threats of the form "One of these days, Alice...," followed by a combination of onomatopoeia. For example: "One of these days, Alice... BANG! ZOOM! Straight to the moon!" (Alice inevitably replies "Ahhh, shut up.")
:Here, Randall takes the pattern to a ridiculous and not-at-all threatening place.

==Transcript==
Because of a family illness, instead of regular comics, this week I'll be sharing some strips that I drew as part of a game I played with friends. Each comic had to be written and drawn in five minutes.

--Randall

====Comic #1====
:Pearl Harbor. November 7th, 1941.
:[There is a beach, with some ships floating in a crescent shaped harbor.]

:[The same bay, again.]

:[The boats continue to move about the harbor.]

:[The boats do their thing. A title explains.]
:(We're going to be here a while, since the attack wasn't until December.)

====Comic #2====
:[Cueball is sitting on a bus, Megan in front of him.]
:I know it's natural and all, but I really wish women on the bus wouldn't try to breastfeed me.
:Woman: C'mon, have some milk. Right here.
:Me: I'm ''reading''.

====Comic #3====
:s/I think that/I saw a study once that said that/g
:Instant persuasiveness multiplier!

====Comic #4====
:[A newspaper front page. Billy Joel is between two policemen.]
:Times
:Billy Joel Arrested for Arson

====Comic #5====
:[One person has a cord leaving their mouth, the other is holding a handset on the end of it to their ear.]
:Handset: Hee hee hee... *giggle*
:I hear that if you drink coke and eat pop rocks, you vomit up a corded telephone handset on which you hear creepy little girls giggling.

====Comic #6====
:[Three soldiers are holding a large integral sign, while a fourth points a gun at the Little Rock High School.]
:1957: Eisenhower orders the military to integrate Little Rock High School.

====Comic #7====
:[A smartphone is vibrating across a table, towards a person.]
:The smartphones got ''too'' smart... and developed a taste... for BLOOD!
:Fortunately, the only way they could move was by turning on their vibrate while on a sloped table.

====Comic #8====
:[Cueball is reading to his child.]
:Cueball: And the wolf went to see the 38th little pig, who had built his house out of strontium.
:Cueball: And the wolf was all, "Ok, what is ''with'' this shit?"
:The 119 Little Pigs

====Comic #9====
:[Cueball is holding up a gun.]
:Cueball: Fastest gun in the west!

:[The gun is galloping across the desert.]
:''gallop gallop''

:[There is a podium, with a gun in each position.]
:Winner!

====Comic #10====
:[A picture of a centrifuge dominates the panel.]
:Centrifuges: They're what separate the men from the boys.

====Comic #11====
:[A computer monitor is plugged in, and cables run into a wardrobe.]
:Lucy: Time passes differently in Narnia, so by putting the CPU and storage for my machine there, I was able to run through the Folding@Home and Seti@Home databases in about an hour.
:Peter: There are so many problems with that.

====Comic #12====
:[Someone is talking to Alice.]
:Person: One of these days, Alice... Wham, zoom, sploosh, fwoom, splash, gurlle, wheeeee, fwoosh, aren't waterslides fun?!

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Five-minute comics]]

Exoplanet (disambiguation)

2013-12-03T19:55:55Z

AKohn: Undo revision 54190 by AKohn (talk) oops

Two different comics are titled '''Exoplanets''':
* [[786: Exoplanets]]
* [[1071: Exoplanets]]

{{disambig}}

Exoplanet (disambiguation)

2013-12-03T19:54:57Z

AKohn: added #1298

Three different comics are titled '''Exoplanets''':
* [[786: Exoplanets]]
* [[1071: Exoplanets]]
* [[1298: Exoplanets]]
{{disambig}}