Star Trek into Darkness

Explanation:
The talk page of a Wikipedia article is used to discuss changes to the article. An edit war is a dispute about a specific edit to an article, manifesting as a series of edits alternating between making and reverting the change, and usually accompanied by a more-or-less heated debate on the talk page.
Here, Randall is referring to a dispute on the Wikipedia article about Star Trek Into Darkness (an upcoming Star Trek film at the time of the comic's posting). On the day before the comic was published, the article name had a lowercase "into", and the talk page looked like this (rounded off in a friendly way, with the posting of a summary of the arguments , and an exchange of virtual hugs). In summary, the debate centers around whether "Into Darkness" should be treated as a prepositional phrase (as in "Star Trek[king] Into Darkness") or an unpunctuated subtitle (as in "Star Trek[:] Into Darkness"), whether compound prepositions like "into" should be capitalized in titles, and whether the capitalization of the title in the movie's official promotional material is relevant. The intensity and multiple facets of a debate over one tiny letter is apparently entertaining to Randall.
Cueball changes the title so that every other letter is capitalized, and adds framing tildes and asterisks (a common, but childish and ugly way of emphasizing titles online).  The title text indicates Randall's belief that such arguments are perpetual and will always arise. He suggests that the edit to the Wikipedia page will result in a dispute over variants of Cueballs "compromise" .  One new alternative has the letter cases switched (or shifted, depending on your perspective), one uses a different set of "bracketing" characters (xX_[...]_Xx instead of ~*~[...]~*~), and one uses the original title, but with a lowercase "L" instead of a capital "I" (which appear similar in many fonts).
Alternating-case text later caught on as an internet meme in 2017 (four years after this comic strip was published) for representing a mocking tone.
Megan's line of "They should have sent a poet." is a quote from the film Contact . The quote is also referenced in 482: Height .  In the movie, the line was meant to convey that only a poet could adequately capture the beauty seen; here, it indicates that prose is insufficient to capture the ironic beauty of the edit war.
The old "favorite edit war" might be the one referenced in the title text of 878: Model Rail or the one resulting from the addition of the 739: Malamanteau article to Wikipedia
[Cueball staring at computer screen.] Cueball: Oh, wow. Look at Wikipedia's Talk page for Star Trek into Darkness. I have a new favorite edit war. Megan (off-panel): Oh?
Cueball: Forty thousand words of debate over whether to capitalize "into" in the movie's title. Still no consensus. Megan: That's magnificent . Cueball: It's breathtaking. Megan: They should have sent a poet.
Cueball: Well, I'm making an executive decision. I hope both sides accept this as a fair compromise.
[A Wikipedia page titled " ~*~ StAr TrEk InTo DaRkNeSs ~*~ "]
After the publication of the comic, the debate continued with full force, complete with a section of xkcd-inspired suggestions . The article itself was soon protected, so that only administrators could edit it. A day later, the title was changed to one including a capital "Into" by the administrator Mackensen . (The debate continued on his talk page .) https://en.wikipedia.org/wiki/~*~_StAr_TrEk_InTo_DaRkNeSs_~*~ was a valid redirect link for quite some time, having not been deleted when requested in 2015 , but 2016 .
The Independent published an article about the " grammatical tizzy ", and the affair as a whole was added to Wikipedia's humorous list of the lamest edit wars .


tar

Explanation:
tar ("tape archive") is a Unix application that creates (and extracts) archives in the ".tar" format. It is typically used through the text-based terminal, using cryptic single-letter arguments such as " tar -cvf archive.tar * ". The comic alludes to the fact that despite years of use of the command, it's still hard to remember the arguments without searching for them, such as with Google.
The joke here is that a "tar" command with perfect syntax on the first try without outside help is such a daunting task that even Rob can't overcome it with confidence, and apologizes for not being able to prevent their imminent death.
The fact that Megan and White Hat assume that Rob can disarm the nuclear bomb because he uses Unix can be referring to an over-generalization fallacy that a partaker in a practice is an expert of a practice. Not all people who use Unix necessarily know how to use tar commands. Then again, since he's the only person nearby who knows any Unix and thus their only hope, their fallacy is pretty justified.
The title text points out that while much of computing changes very quickly, the tar program, which is very old (originating ca. 1975), is still around and heavily used. And yet, Randall complains he still cannot type out a line of tar command with correct flags without having to look the flags up. Tar is a very common command that Unix users will come across regularly, much like Windows users will come across .zip files. Depending on the flavor of Unix, the order of the flags, or the lack or inclusion of a '-' could render the command incorrect. Most true Unixes (AIX, HPUX, Solaris) not using the GNU utilities would give an error on the above tar example. For such a simple command, it is one that most people need to look up references to use.
There is probably also a pun on " tarbomb ," a poorly created tar archive that, when extracted, dumps a load of files into the current directory that the user has to clean up. And although the bomb looks more like Fat Man , the type of bomb that was used over Nagasaki , at least size-wise, it may also be a pun on the name of the largest ever hydrogen bomb which was called the Tsar Bomba (translation: "emperor bomb").
In 208: Regular Expressions Cueball saves the day by knowing regular expressions , although in the title text it is alluded to how easy these may also miss a character.
Rob may refer to Rob Pike , who was a member of the team at AT&T who created Unix.
[Megan and White Hat stand next to a nuclear bomb. The bomb has a hatch open on top, and a small blinking screen. The two people are shouting off-screen.] Megan: Rob! You use Unix! White Hat: Come quick!
[Megan, White Hat, and Rob look at the screen on the bomb. Rob peers closely. The screen is on the bomb, but is shown at the top of the panel in black with white letters, except "tar" and the last underscore which is in gray and "ten" which is black but written in a white box. The text reads:]
[They all stand in the same position, but without the text displayed. Beat panel.]
[Still in the same position but White Hat becomes impatient.] White Hat: ...Rob? Rob: I'm so sorry.


Expedition

Explanation:
Google Maps is a service provided by Google that offers a map of the world including satellite and aerial imagery for free. Using the scroll wheel , the user can zoom out to see a larger area. Lena River is a river in Russia, flowing into the Arctic Ocean (with a large delta ).
Clicking on the comic leads to an online Google Maps page showing the satellite imagery of the Lena Delta . Travelling south up the river will lead to the city of Yakutsk and eventually to Lake Baikal .
It appears that Cueball is simply trying to explore the world without leaving his laptop or purchasing an expensive game.
Alternatively, he may be playing Mapcrunch , this 'game' randomizes a street view location with the goal of finding the airport.
The title text states that he apparently somewhat still treats it as a game and that he has been on it for at least a decade.
In the years since, a game called GeoGuessr has been released, with the user being put into a random location in Google Street View and asked to guess where they are in the world by analyzing clues in their environment. This often necessitates the user making their way from the middle of the wilderness to some manner of civilization, exactly as in the comic.
[Cueball is at a computer.] February 4th: Departed the mouth of the Lena River, heading south. It has been nearly half an hour and still no sign of civilization. The scroll wheel tempts me, but I will not cheat. Click click click
[Caption below the panel:] My hobby: Getting lost on Google Maps satellite


Bridge

Explanation:
"If all your friends jumped off a bridge, would you jump too?" This is a common question, used to challenge a decision based on the bandwagon effect . It challenges someone to consider whether something is really a good idea, even if everyone else does it (in this case, friends). The sentence is, upon closer analysis, a straw man attack that over-extrapolates the bandwagon effect.
Cueball responds by assuming that if all of his friends jumped off a bridge, there must have been some extreme circumstance that made it logical to do so; for example, that the bridge is on fire. This points out a logical fallacy with the question: if they really are jumping off a bridge, they're probably motivated by something serious as opposed to an idiotic risk. So the humor of this comic is in all the different ways the question can be turned on its head, and made to mean something the unseen speaker probably never intended.
The title text suggests that, even if there is nothing wrong with the bridge, the person asking the question is not acting right. The proper reaction would be concern about the mental (or physical, they could be injured) state of the people jumping off for no valid reason, and not just brushing them off as unworthy of attention. This is so especially when these people are described as "all my friends", so they have presumably always behaved correctly until they decided to jump off the bridge.
[A youthful Cueball talking to an unseen parent.] Parent: No, you can't go. Cueball: But all my friends— Parent: If all your friends jumped off a bridge, would you jump too? Cueball: Oh, jeez. Probably.
Parent: What!? Why!? Cueball: Because all my friends did. Cueball: Think about it — which scenario is more likely:
Cueball: Every single person I know, many of them levelheaded and afraid of heights, abruptly went crazy at exactly the same time... Cueball: ...or the bridge is on fire?
Parent: ...I, uh...hmm. Cueball: Imagine reading this on CNN: " Many fled their vehicles and jumped from the bridge. Those who stayed behind... " Cueball: Is something good about to happen to those people? Parent: Maybe they'll find cookies? Cueball: OK, you stay. I'm jumping.


Perl Problems

Explanation:
Perl is a scripting language that makes heavy use of regular expressions , which are good for dealing with large amounts of text quickly. In the comic, the man wearing sunglasses parodies the song " 99 Problems " in which the rapper Jay-Z says:
If you're havin' girl problems I feel bad for you, son- I got 99 problems, But a bitch ain't one.
In the comic however, the rapper tries to solve his problems with Perl's regular expressions, and ends up only creating another problem for himself, which is a reference to a famous quote by Jamie Zawinski (whose name could also be shortened to "Jay-Z"): "Some people, when confronted with a problem, think 'I know, I'll use regular expressions.' Now they have two problems." (This quote was revisited in 1313: Regex Golf .)
"program --help" is a common way, originating with the GNU project, to ask a program to show documentation on its usage and supported parameters; which, for some program, could include a "-z" command-line argument ("flag"), so the command would read "jay -z". In this case, it is just an obvious play on the rapper's name. jay is also an actual C program that is a compiler-compiler for java, but it doesn't have a "-z" flag.
This sort of problematically recursive self-reference is reminiscent of comic 927: Standards , and 1739: Fixing Problems .
[Man with sunglasses talking (or, alternatively, rapping) to Cueball.] Sunglasses: If you're havin' perl problems I feel bad for you, son-
Sunglasses: I got 99 problems,
Sunglasses: So I used regular expressions.
Sunglasses: Now I have 100 problems.


Workflow

Explanation:
Users will often try to work around bugs in software, and are sometimes able to get used to having the bugs around. Some bugs are even interpreted as features and users complain when the software authors fix them. This phenomenon has been named Hyrum's law : the law states that whatever the official feature list actually says, if a program has enough users, eventually every feature (whether intentional, unintentional, or a bug) will be relied upon by someone. A similar effect may be caused by other improvements, particularly those which involve changes in the user interface .
This comic shows a somewhat extreme example. An unnamed application had a bug causing the CPU to overheat whenever the spacebar was held down too long. In version 10.17, this bug was fixed. Soon, LongtimeUser4 complained that they relied on the fact that the CPU overheats if the spacebar is held down. They had stumbled across this "feature" (which is, again, weirder than usual) and took advantage of it to streamline their workflow, and they wanted an option to re-enable it.
Emacs (name originally derived from E ditor MAC ro S ) is a text editor originally written at MIT in 1976 and adopted into the GNU project in 1984. The control key sees extensive use in Emacs, and since it's hard to reach, users often remap it to Caps Lock or some other key. LongtimeUser4 fixed the problem very clumsily ("horrifying," as the admin puts it) and is annoyed that their kludge no longer works. The moral of the story is that you can't please everyone.
Examples of real life changes in software which, though often acclaimed by critics, caused great annoyance among the existing user base include ribbons introduced in Microsoft Office 2007 and the Start screens of both Windows 8 and Unity desktop manager bundled with Ubuntu from versions 11.10 through 17.04. In the latter case, developers included an option to use the older interface; for the rest, applications emulating old behavior were developed by third parties.
The title text makes a hyperbole to humorous effect; children will freeze to death during the winter because they won't be warmed by a rather unconventional heater. Making (or creating an illusion of) a connection between one's opinion and care for children's welfare is a common method of gaining public support, as such arguments are hard to deflect without sounding cruel and uncaring. "holding down spacebar to stay warm" could also be a reference to space heaters .
[Changelog for version 10.17 of a piece of software.] One change listed: "The CPU no longer overheats when you hold down the spacebar" Comments: LongtimeUser4 writes: This update broke my workflow! My control key is hard to reach, so I hold spacebar instead, and I configured Emacs to interpret a rapid temperature rise as "control". Admin writes: That's horrifying. LongtimeUser4 writes: Look, my setup works for me. Just add an option to reenable spacebar heating.
Every change breaks someone's workflow.


Steroids

Explanation:
This comic is about steroid usage to enhance humans performance ; it is likely inspired by Lance Armstrong 's then-recent confession to blood doping in a televised interview with Oprah Winfrey (although Armstrong's confessions did not itself include anabolic steroid use; "steroids" is a common catch-all phrase often misused to reference other forms of doping ).
This comic is making the point of the opinion that the criterion about which chemicals (steroids) humans may or may not take in to be considered the strongest or fastest is an artificial criterion. This is demonstrated by Megan explaining the whole concept to an energy sphere representing a non-humanoid intelligence; when framed the way Megan explains it, the explanation sounds rather trivial and silly. A better explanation would be to say that some chemicals make humans faster and stronger but also damage the human body, so these chemicals are banned so the competitors won't destroy themselves. Another point Megan has missed is that the competitions aren't unrestricted, they're designed around specific rules and structures, to which all participants agree. The chemicals in question are a violation of those rules, and so are both dishonest and subvert the entire purpose of the competition.
This comic is one of many instances where Randall attempts to trivialize sports.
The title text changes the perspective again by suggesting that humanity itself is trivial in the grand scheme of things and that really all we are is a "transition" state between old dust and new dust, with a bunch of emailing in between. This is a version of the saying that the Universe is just trying to turn itself into Iron, which is the atom with least energy, and it can thus neither be fused in stars or decay radioactively.
The comic was published on Ash Wednesday (Western liturgical start of Lent). The dust to dust reference calls to mind the charge, "Remember man that thou art dust and unto dust you shall return," which is traditionally spoken by priests as they place ashes on the foreheads of observers on Ash Wednesday, in addition to the idea that all atoms in the universe other than Hydrogen, Helium, and some Lithium, were created after the big-bang via Stellar nucleosynthesis , with further production and dispersal via Supernova nucleosynthesis . Thus the reference by Joni Mitchell in the song Woodstock : "We are stardust..."; and echoed by Carl Sagan : "We are star stuff."
Similar talking floating energy spheres have been used later in 1450: AI-Box Experiment , where it was clearly a different sphere and then in the Time traveling Sphere series. There is no indication of it here, but the sphere here could be another time traveler as well, back to try and understand humanity.
[Megan is walking while an energy sphere (Sphere) floats behind her and talks to her. The sphere is black but surrounded by six outwardly-curved segments that are shaded gray. The white parts in between makes it look like it irradiates light out along these lines.] Sphere: Explain to me this "steroid scandal."
[Zoom in on Megan's face while she holds a hand to her chin.] Megan: Well, uh... Megan: We humans are sacks of chemicals which stay alive by finding other chemicals and putting them inside us.
[Megan has turned around facing towards the Sphere to the left. She holds up one hand palm up.] Megan: We hold contests to see which humans are fastest and strongest. Megan: But some humans eat chemicals that make them too fast and strong.
[Megan still facing the Sphere holds her arms out.] Megan: And they win contests! Sphere: That does sound bad. Megan: It's awful!


App

Explanation:
Some websites have a mobile app designed for use on mobile devices such as smartphones and tablets. In theory this is because the main website will be more difficult to navigate on the small screen of a mobile, or some features won't work. In practice, this alternative is frequently worse than simply viewing the standard web page, for reasons offered in the comic:
The comic offers a brutally honest version of such a promotional popup.
Compounding the frustration is that some sites aggressively promote their app/mobile version with a popup message that repeats the suggestion on every visit to the site, and as the title text notes, if you reject the popup, you end up on the site's homepage, rather than the subpage you may have been trying to reach via a web search. A similar effect (where the mobile version will only load the site's main page) is described in more detail in 869: Server Attention Span .
[A popup window on top of a webpage displayed in a smartphone browser that looks like Safari.] Want to visit an incomplete version of our website where you can't zoom? Download our app! [OK] [No, but ask me again every time]


Moving Sidewalks

Explanation:
Cueball and Megan are getting ready to ride an array of mini-conveyor belts, each going at a speed multiple of the first ones. Assuming they both take the one in front of them, each conveyor belt will speed them up a little bit more with little effort on their part, ultimately reaching a point where they are going very fast and are close enough to be able to high-five each other.
The average moving walkway speed globally is 3 feet/second (~1m/sec), so Cueball and Megan would only be travelling about 2/3 average human running speed by the time they meet.  Even with the opposing forces added to their high five, it would be very unlikely for them to injure each other (though the slap would more than likely be painful).
The title text may be a reference to a music video made by OK Go, "Here It Goes Again", in which the band jumps on and off of various treadmills in a similar fashion.
A series of parallel accelerating conveyor belts is also a long distance travel mechanism used in Robert A. Heinlein's The Roads Must Roll and in Isaac Asimov's Robot Detective novels.
[Cueball and Megan on the opposite far ends of a bidirectional moving sidewalk.  Arrows indicate that one half will carry Cueball from left to right, while the other half will carry Megan from right to left.  In each direction, the sidewalk is made up of a series of individual conveyors.] Cueball: Ready? [A diagram labels various individual conveyors as follows.] [Outermost conveyors:] Moving Sidewalk [Second and second-last conveyors:] Moving Sidewalk (2x Speed) [Next conveyors:] 3x Speed [Next conveyors:] 4x Speed [Innermost conveyors:] 5x Speed [Spot between the two sidewalks, directly in the center:] High-Five Location Megan: Ready.
This comic was originally uploaded with all the arrows facing in the opposite direction, before Randall updated it with the current image.


Those Not Present

Explanation:
Cueball (likely representing Randall ), has decided to leave conversations deemed toxic, by scooting a little bit away any time somebody badmouths someone not present. In each panel, he scoots progressively further away until he reaches an area with Megan , Hairy , and Beret Guy , discussing giant squids . He decides to join them, as this conversation is far more interesting to him than one criticizing people behind their backs.
The title text jokes that the second group, is, in fact, dissing the giant squid rather than discussing how cool it is. As the squid is not present, Cueball scoots back.
Every time someone says something negative about a person who's not in the room, I scoot my chair back a few inches. [Cueball, Ponytail and two other people are sitting at a table drinking.] Person: He's not so bad, but his friends ... [Cueball scoots away from table.] Scoot scoot
Ponytail: His band is never gonna take off if... [Cueball scoots further away.] Scoot scoot
[Megan, Beret Guy, and Hairy come into view.] Off-screen: Yeah, his sister is even weirder . Off-screen: Did you see she had... Scoot scoot Beret Guy: ...and there's a video, but it's blurry...
[Cueball turns around and leans his arm on his chair.] Cueball: What're you talking about? Hairy: Giant squid! Cueball: Mind if I join you?


Time Robot

Explanation:
The comic starts with a scene similar to one in the 1984 science fiction action film The Terminator . In the movie a killing robot (played by Arnold Schwarzenegger ) is sent back in time to kill Sarah Connor, the main female protagonist of the movie. A human, Kyle Reese, also travels back in time to protect her (and he acquires a sawed-off shotgun which Cueball holds in the strip).
However, in the following panels, Cueball explains that, even if he succeeds protecting Megan from the killing robot, we all are hunted by an unstoppable enemy trying to kill us – time. He goes on to point to the similarities between the time and a Terminator. The clock visible in the third panel features a red light in the place of a 3-hour marker, which is a reference to glowing red eyes of a Terminator.
In the final panel, "come with me if you want to live" is a famous phrase from the movie , but in this case, amended with the facts about the inevitability of eventual death.
Also, the title text is a play on a quote from The Terminator , where Sarah Connor starts to believe that " There's no fate but what we make for ourselves. ". It is also a reference to the character " Death " in Terry Pratchett 's Discworld novels. In the Discworld novels, Death's voice is always depicted in small caps and he is often caught making sometimes bizarre philosophical statements about life and death.
652: More Accurate is also riffing on Kyle Reese's introductory "Come with me if you want to live" line to Sarah Connor. The theme of the inevitability of the ravages of time is underlying 926: Time Vulture .
[Cueball runs towards Megan with a shotgun in hand.] Cueball: I'm from the future! Cueball: You're being stalked by an unstoppable robotic assassin!
[Close up of Cueball's head.] Cueball: Of course, in a sense, we're all being stalked by an unstoppable robot. Cueball: A robot called time .
[Cueball looking at a clock.] Cueball: I see it in the mirror. I see wrinkles, grey hairs. Cueball: I hear its metallic footsteps in the relentless rhythm of the ticking clock.
[Cueball reaches out to Megan.] Cueball: Anyway, uhh - come with me if you want to live for a while. Cueball: You'll still die eventually. Cueball: We all will.


Pickup Artists

Explanation:
A pickup artist is a person who considers himself skilled at picking up (finding, attracting and seducing) women (or men), through various psychological tactics and tricks. The term " pickup " in "pickup basketball" means informal and spontaneous. In pickup basketball the players are not part of an organized league or team but rather are just people who are available to play at that time and location. Beret Guy thinks (or wants to think) that what pickup artists really do is gather spontaneously to practice artistry , like the visual arts . This makes the world seem a happier place, especially considering his own disposition for (eccentric) art, and generally ability to always see the best in every situation.
Randall does not believe that pick-up artists have healthy attitudes towards women and has elaborated on this previously in 1027: Pickup Artist (also featuring Hairy ) and in 800: Beautiful Dream .
The title text also shows Beret Guy's belief that the " friend zone " is a physical place. The "friend zone" refers to the state of a relationship in which one party has romantic interests, but the other person only wants to be friends. Once the friend zone is established, it is said to be difficult to try to move beyond that point into a romantic relationship. Beret Guy however believes (perhaps intentionally, like with pickup artist) that a physical place filled with his friends should be a fun place to visit. Randall previously expressed criticism towards trying to just slip into a romantic relationship from the friend zone in 513: Friends .
[Beret Guy is talking with Hairy.] Beret Guy: What've you been up to lately? Hairy: I've been hanging out with some pickup artists. Hairy: I'm learning a lot! Beret Guy: Oh, that sounds like fun!
[Caption below the panel:] The world seems like a happier place if you think "pickup artist" is like "pickup basketball player".
This comic is one of a small set of comics with the same or almost the same title as another comic (the only difference being the use of the plural form of "artist").


ISO 8601

Explanation:
When abbreviating the date into numerical form, various areas of the world tend to list the year, month, and day in different orders (as well as with different delimiting symbols), which can cause confusion particularly when the day value is 12 or lower allowing it to be easily interpreted as the month and vice versa. As a public service announcement , this comic states that there is in fact one international standard for writing numeric dates, set by the International Organization for Standardization in its ISO 8601 standard: YYYY-MM-DD.
The comic then proceeds to list several discouraged ways of writing out the date of the comic's publication, as they do not match the standard. It begins with several commonly used ones in countries around the world, but then begins to list increasingly uncommon ways, ranging from strange (Roman numerals) to quirky (binary, Unix time) to essentially impossible (painting the numbers onto a black cat).
The title text provides a perfect example of the kind of ambiguity that can arise when non-standard formats are used. The ISO standard was in fact published on 1988-06-05 and amended on 2004-12-01. This is mentioned in the title text in MM/DD/YY format; however, there is no way to naturally figure this out, particularly with the second date.
With the year truncated to two digits and all three numbers at 12 or lower, the date referring to December 1, 2004 (the digits pairs 12, 01 and 04) has a number of misinterpretations. Usually 12 th Jan '04 (if written as US-style but read as European, or vice-versa) but with ISO-influenced "YY MM DD" ordering as one side or other of the misunderstanding it can easily become the 12 th day of April 2001, the 4 th day of December 2001 and the 4 th of January 2012. It takes two such communication errors to 'become' the 1 st day of April 2012.
Date formats were again the subject in 1340: Unique Date and 2562: Formatting Meeting .
The other mentioned formats are:
Public Service Announcement:
Our different ways of writing dates as numbers can lead to online confusion. That's why in 1988 ISO set a global standard numeric date format. This is the correct way to write numeric dates:
2013-02-27
The following formats are therefore discouraged: 02/27/2013 02/27/13 27/02/2013 27/02/13 20130227 2013.02.27 27.02.13 27-02-13 27.2.13 2013. II. 27. 27 ⁄ 2 -13 2013.158904109 MMXIII-II-XXVII MMXIII LVII ⁄ CCCLXV 1330300800 ((3+3)×(111+1)-1)×3/3-1/3 3 2 27 2013 [the numbers 2013, 02, and 27 written overlapping each other] 10/11011/1101 02/27/20/13 2 0 5 3 1 1 2 67 4 37 8 [A black cat with 2-27-13 scrawled across its body in dripping white paint.] Cat: Hissss


Virus Venn Diagram

Explanation:
Randall uses an Euler diagram (technically not a Venn diagram ) to make fun of clueless computer users. The circles in the diagram don't overlap, meaning problems that people suspect are caused by viruses are never really caused by viruses, and problems that are actually caused by viruses are never suspected by people to be caused by a virus.
When computers don't function as expected, a common response from ordinary users is "Maybe it has a virus ?".  However, most of these situations can be explained by faulty hardware (freezing, blue screen, etc.) or software (crashes, errors, apparent lack of response to input, etc.), a general lack of maintenance (too slow to start up, too much clutter on screen, etc.), or user error.  A virus can potentially cause those symptoms, but it's much more common for them either to cause immediate and massive damage (rendering the computer completely unusable, wipe the disk, display obvious propaganda, etc.), or to remain stealthy with no obvious symptoms (logging keystrokes, exfiltrating sensitive information, receiving commands in the background, etc.).  Of course there is no clear separation and there is always some overlap between the two scenarios, so the diagram is not meant to be taken literally.
The title text refers to the technological singularity , a hypothetical point in the future when superintelligence emerges in computers, so that they can build new computers with ever increasing intelligence. It is seen as impossible to predict what would happen beyond this point; hence the term "singularity". 1084: Server Problem makes a joke on this.
"Defragging" is short for disk defragmentation , an easy, user-friendly action that PC users can undertake to supposedly make their computers run faster. It is therefore a common all-round recommendation to do this, regardless of the problem. Randall suggests the same clueless users would encounter the singularity and attempt defragging. It probably won't help much.
[Euler diagram with two circles that don't intersect. One circle is green, while the other is slight dark blue.] Green circle: Computer problems that make people say "Maybe it has a virus?" Blue circle: Computer problems caused by viruses


PGP


Rembrandt Photo

Explanation:
Rembrandt was a 17th-century Dutch artist. Megan shows Cueball an alleged photo of Rembrandt's parents at the time that his mother became pregnant; his conception . Since photography wasn't invented until the 19th century, it can't be a real photo. Megan responds to Cueball's disbelief by stating that it is an artist's conception: an artistic imagination and depiction of an event.
The joke thus is a pun on the phrase 'artist's conception' that can mean two different things: one, Rembrandt's mother becoming pregnant with him and two, the creation of the image.
The title text refers to James McNeill Whistler who painted a portrait of his mother, known to Whistler himself as "Arrangement in Grey and Black No1" but more commonly known as " Whistler's Mother ". As a joke on this, Megan seems to want to show a photo of Whistler's mother, which would probably be pornographic or at least different from the famous portrait. The ::click:: is Megan switching to that picture on her laptop.
[Megan is holding a laptop. Cueball is sitting at a desk and turned around to face Megan.] Megan: Hey, look - Rembrandt's parents having sex! Cueball: Waugh! Why do you- Cueball: ...Wait, how can there be a photo of that? Megan: It's an artist's conception.


Rose Petals

Explanation:
This comic strip is playing with romantic movies and gestures used in them. In such movies, one often used romantic gesture is spreading rose petals in the house or apartment , making a way towards the bedroom in which a romantic interest/lover is waiting surrounded by roses for a love-making session. The joke is that these petals don't lead from the front door to the bedroom and Cueball 's lover, but in the opposite direction instead from the bedroom out onto the street. It appears that someone has set up a box of rose petals and an electric fan atop a Roomba (an autonomous robotic vacuum cleaner) as a method of automatically creating such a trail. The title text suggests that despite the other party's intentions of setting this up as a joke to trick Cueball, Cueball ended up having a lovely time with the Roomba.
[Cueball enters a living room, to see a line of red rose petals on the floor.] [Cueball follows the line of rose petals.] [Cueball observes that the line of rose petals leads out the front door, down the driveway, and along the sidewalk.] [The rose petals leads up to a table fan behind what appears to be an inverted mailbox filled with rose petals with its back removed. Both are sitting on a Roomba which is motoring down the sidewalk. The fan is on, and is blowing the rose petals out the slit in the front of the mailbox. The contraption is making a sound and the Roomba has its brand written on it] Whirrrrrr Roomba


Circumference Formula

Explanation:
The circumference C of a circle is 2 π r , where r is the radius of the circle. Randall then makes a footnote about r , using 2 . This creates a typographical ambiguity, since a superscript 2 can also be an exponent (as in x 2 ). The comical purpose of this ambiguity is that the formula initially makes an appearance of a mistake and confusion with the formula for the area of the circle: A = π r 2 . If and only if the reader realizes that the superscript text is a reference to a footnote will they understand that the author has in fact supplied the correct formula.
The title text makes a related joke. Randall has used r' (r- prime ) and r" (r-prime-prime, typically pronounced as r double prime ). The title text can be explained thusly:
Like many symbols, prime has widely differing meanings depending on context. In mathematics prime is often employed to distinguish corresponding components in analogous systems. For example, in a description of a basic physical system, if the velocity of an object is denoted with the variable v , the velocity of that object at time=0 may be denoted with v′ . Playing off this use of prime, Randall has selected the radius of Earth Prime , a concept used in speculative fiction with parallel universes and multiple Earths. Earth Prime is our Earth (or at least the Earth from which the protagonists originate).
However, other disciplines use prime to mean other things. In timekeeping and navigations ' denotes minutes (fractions of hours or degrees, respectively) and " denotes seconds (fractions of minutes). In the United States and some other places not using meters to measure distance, ' denotes feet and " denotes inches .
The suggestion of using r' or r" does not cause any mathematical confusion, but using the former to denote the radius of a specific object and the latter to denote a radius using a specific unit of measurement would be highly esoteric.  Furthermore, r' and r" can be used in calculus as a method of denoting, respectively, a first derivative and a second derivative.  For someone attempting to use the formula and some derivative representing a circle's radius, trouble could result quite easily.
2 These are not intended to indicate the presence of a footn... oh, never mind.
Circumference of a circle: 2πr 2 2 The circle's radius


Ineffective Sorts

Ineffective sorts

Explanation:
The comic gives examples of four non-functional sorting algorithms written in pseudo - Python .
The first sort is an unfinished merge sort . The merge sort works recursively by dividing a list in half and performing a merge sort to each half. After the two halves are sorted, they are merged, taking advantage of the fact that the two halves are now in correct order and thus the merge can be done efficiently. The author of the merge sort in the comic appears to have given up on writing the sorted-merge part of the sort, which is why it's a half-hearted merge sort, but instead concatenates the halves without sorting. In its current state, the sort would divide the list into elements of size one, then recombine them in their original unsorted order, but in nested lists - making the original data more difficult to work with. The author acknowledges this failing with the comment "Ummmmm... Here. Sorry."
The second sort is an "optimized" variant of bogosort . A standard bogosort works by randomly shuffling the elements in the list until they are sorted. In a comment, the author points out that this variant of bogosort runs in O(n log(n)), whereas standard bogosorts actually have an expected runtime of O(n·n!) but may never finish. This variant of bogosort finishes so much faster because in most cases it does not actually sort the list, instead reporting a fictitious error in the operating system (a "kernel page fault") if the list isn't ordered after shuffling log(n) times.  The bogosort is "optimized" because no comparison sort algorithm can possibly do better than O(n log(n)) in the worst case.
The third sort parodies a programmer explaining a quicksort during a job interview. The quicksort works by choosing an index as a pivot value and sorting all elements less than the pivot before the pivot and all the elements greater than the pivot after the pivot. It then does a quicksort to the section less than the pivot and the section greater than the pivot until the whole list is sorted. The interviewee flounders for a little while, then asks whether they can use the standard libraries to call a quicksort. The joke being, the standard library contains a quicksort, and the programmer would rather rely on that (possibly even pass it off as his own work) than his own example of quicksort. While it's commonly a good idea in real projects, this would surely count as a failure on interview.
The final sort is just a mess. First it checks to see if the list is sorted, and exits if it is. Then it rotates the list by a random amount 10,000 times (as if cutting a deck of cards) and exits if the list is ever sorted. Next, in desperation, it checks if the list is sorted three times. Finally, realizing that they have no chance of success, the author performs the computer equivalent of a Rage Quit and attempts to destroy the computer rather than admit defeat. First, the program attempts to schedule a shutdown of the computer in five seconds, then attempts to delete the current directory, then attempts to delete the user's home directory (presumably the grader's files), and finally all the files on the computer. rm is a POSIX command; the -r and -f flags mean that the remove command will remove all contents of the specified directories and will not prompt the user beforehand. Under the guise of " portability ", the program runs the equivalent Windows rd command with switches to delete all files from the "C:" drive without prompting. Finally, the program returns a list containing the numbers one through five in order.
In the title text, StackOverflow ( link ) is a question-and-answer site where programmers can ask and answer questions on programming. The author of this code takes advantage of the hopes that someone on StackOverflow knows what they are doing and has posted code to sort a list... and somebody implemented stacksort ; well, sort of.
Ineffective sorts


Bumblebees

Explanation:
This is the first comic using a fact that is not a Fun fact . Instead it is a Science Fact.
There is an often repeated legend that according to the laws of aerodynamics, bumblebees cannot fly. No theories of aerodynamics or mechanics have ever claimed such a thing, and the legend likely originates from a mathematical error that appeared in a 1934 book, written by a scientist who acknowledged that the conclusion was probably wrong.
Here, Randall makes fun of the urban legend with some wordplay. "Fly" in English can refer to both flying under one's own power and the act of piloting a flying vehicle. The comic puts a bumblebee on top of a control column inside of an airplane and lets it fly the entire plane. But physicists are still confused and don't know how the bees are able accomplish this.
The strip also creates a fallacy that when experts can't explain something, they must not be able to understand it. In this particular case, experts are unable to explain why bees can fly airplanes because they can't fly airplanes. [ citation needed ]
This strip could be a reference to Bee Movie , in which the main character, Barry B. Benson, enlists the help of other bees to land a plane with the last reserves of pollen on Earth. The opening quote of the movie repeats the Bumblebee legend, followed by saying, "The bee, of course, flies anyway, because bees don't care what humans think is impossible."
The title text mentions that sociologists are also unable to explain why many people repeat this obviously wrong urban legend .
[Caption above the panel:] Science fact: [A black and yellow bumblebee sits on the control column in the cockpit of an airplane. With lots of instruments and buttons in front of it. There is a caption below the panel:] Physicists still can't explain how bumblebees can fly airplanes.


Aspect Ratio

Explanation:
Aspect ratio is the relationship between the width and height of an image (and in this case, a video) and is denoted in a ratio of <width>:<height> - usually either in lowest common denominator, or with a decimal width to a height of "1". Up until the 1990s, all televisions and most computer monitors (CRT tube and LCD) were in the standard 4:3 aspect ratio, called "fullscreen" (meaning the width is 4/3 or 1.33... times the height). When HDTV was developed, the standard for television screens changed to 16:9 (width being 16/9 or 1.77... times the height), called "widescreen" (although widescreen can also refer to a number of even wider ratios used in feature films). Computer monitors are now available in widescreen ratios, though fullscreen remains common as well.
Letterboxing is a process whereby an image which does not fully fill a screen is expanded to fill the screen by the addition of further material (mattes). Usually this is done with the addition of black bars in the empty space. One example of why this was necessary was widescreen films on VHS cassette. VHS could only record and play back 4:3 images. Thus, in order to display a widescreen film, the rest of the VHS's 4:3 image had to be filled with horizontal black bars at the top and bottom of the image. Those bars were part of the video information recorded on the cassette.
When DVDs were introduced, many DVDs also had letterbox bars on the DVD's full screen image. With the increased popularity of widescreen televisions, DVD players were improved to offer anamorphic widescreen , in which the full widescreen image is horizontally rescaled (shrunk) into a 4:3 size, which the player then was able to display stretched horizontally back to the proper widescreen aspect.
With the advent of Blu-ray, video is generally encoded in whatever its proper aspect ratio is intended to be, and the player itself is left to appropriately matte the image.
The problem with letterboxed video (such as a 16:9 video letterboxed for 4:3) is that if one tries to watch the video on a 16:9 widescreen, where the image should fill the whole screen, instead the 4:3 letterboxed image fills part of the screen with further vertical mattes on the left and right of the image, thus producing an image much smaller than it needs to be, with mattes on all four sides. Some TVs or media players can zoom to help resolve the issue, although the video resolution usually suffers. By encoding only the video itself and allowing the player to do the matting, the video can be seen as large as possible on any given screen.
Animorphs is a late-90's to early-00's young adult book series about shape-shifting teens who turn into animals to fight body-snatching aliens. Sony held the rights to create a film, but never made use of them, beyond creating URLs for a proposed movie on December 11, 2012. Animorphs has since been mentioned in the title text of 1360: Old Files as well as being the main joke in 1380: Manual for Civilization and 1817: Incognito Mode .
In this comic, Randall appears to be complaining about the issue of widescreen videos which have been rescaled to 4:3 by "squashing" the video horizontally to make it narrower, and in the process causing everything to appear thinner/taller than it really is, causing an unpleasant experience. This is akin to crushing a car to the 3:4 ratio while putting black bars on both sides, which Randall uses as disproportionate retribution .
A note is that, if someone managed to "expand" the car, the car would not be "un-crushed" and probably even destroyed even more, referencing the bigger damage done when "squashed" video is attempted to be "expanded" to its original ratio, distorting the video quality. When an image is converted to 3:4, the pixels are resized to squares. When resized to 16:9, the pixels therefore have a longer side and a shorter side.
[A gray car is crushed in a large black clamp.] Whenever someone uploads a letterboxed 16:9 video rescaled to 4:3, I do this to their car.


Bonding

Explanation:
This is source code written in the Java programming language which models a parent and a child playing a game of catch .  Normally this game is played with the parent throwing a ball to their child, who catches it and throws it back, and repeated back-and-forth. The comic title "Bonding" refers to the building of relationship between the parent and the child. The joke lies in the puns using the words try , throw , catch , and Throwable .  These can refer to actions in the real-life game, but are also keywords in the Java language that are used for exception handling , a method of signaling error conditions and responding to them.  Also, the terms "parent" and "child" are usually interpreted more abstractly in programming, as generic terms used in hierarchical data structures .
The program, as written, will recursively call the aim method alternately on the parent and the child indefinitely, causing each to take turns throwing and catching the Ball object.  Note that unlike the real game, this program actually has the same person both throwing and catch the same ball on their turn.  The ball is passed onto the other person by aiming it at them, which causes the person to both throw and catch the ball, and aim it back, perpetuating the cycle.  This program will also eventually crash with a stack overflow error.
The title text refers to the Eclipse IDE , which is a tool commonly used to develop software in Java. "Building character" is something that you would expect a parent to do, in order to instill in his child positive traits, such as confidence and athleticism. This is possibly a reference to Calvin and Hobbes , where Calvin's dad often encourages him to build character in a number of ways, including playing baseball. This is made more likely by other references combining technology with Calvin and Hobbes, such as xkcd comics 409: Electric Skateboard (Double Comic) , 702: Snow Tracking and 1002: Game AIs . However, here, "build" might also be a play on the term of " building " a program, while " character " refers to a data type in programming languages. It may also refer to the common notion that programming in C++ or Java builds character due to their powerful but sometimes finicky libraries.
To compile this Java source code, the two classes would need to be in a .java file.
The program defines two classes (types of objects):
The program executes in the following order:


Voyager 1

Explanation:
Voyager 1 is a U.S. space probe launched in 1977 to study the outer reaches of the Solar System and beyond. Popular press has on several occasions announced that it "has left the solar system" at each point when a boundary has been confirmed or a major event has taken place. This underscores the fact that there is no strictly defined and recognizable boundary of the solar system, or at least we haven't found one yet.
On the day of this comics release (2013-03-22) it was announced that Voyager 1 had entered a new region of space . At this point Voyager 1 had passed through the Heliopause and entered the Interstellar medium , although this latter was first confirmed about half a year later in September 2013.
The chart shows that Voyager 1 has left the Solar System 22 times, but in the title text only 16 are mentioned.
The title text lists several such possible boundaries, (and how many times Voyager 1 has passed them) together with fictive humorous ones:
See also Voyager over the “heliocliff,” but Solar System transition mysterious on Ars Technica.
About eight years later, Voyager 1 leaving the solar system was brought up again in 2414: Solar System Compression Artifacts .
[A heading at the top of a white panel, then a line and below this 22 tally marks in two rows, four times five (three of these at the top) and then two extra.] Number of times Voyager 1 has left the Solar System


Time


The Past

Explanation:
"The past is a foreign country, they do things differently there" is the opening line of " The Go-Between ", a novel by Leslie Poles Hartley (1895–1972), published in London in 1953. Black Hat notes that a country's past military tends to be less advanced than its current one, and that countries in the past had larger oil reserves as they had consumed less oil then.
If a country from the past existed in its old state today, other countries would likely leap at the opportunity to exploit its oil reserves.
Or: Black Hat could be considering sending the modern troops of a country from today back in time to rob the oil from the countries in the past. It could be profitable to invent a time machine for just that.
"Mozart in Mirrorshades" is a short story by Bruce Sterling and Lewis Shiner, which features the use of time travel to exploit earlier eras' natural resources.
Also, in the Hitchhiker's Guide to the Galaxy series, time has been exploited to use as energy. They say: "The Past is like a foreign country. They do things exactly the same there."
The "If history has taught us anything" phrase is used to start several quotes:
"If history has taught us anything, Arthur muses, it is that men with mustaches must never achieve positions of power." - Tom Rachman, The Imperfectionists "If anything in this life is certain, if history has taught us anything, it is that you can kill anyone." - Michael Corleone, The Godfather
The title text starts by fitting the usual pattern of this phrase, but in the second half humorously subverts it. It extends the "past as a foreign country" metaphor by implying that lessons learned from history can count as military intelligence to use against it.
A more recent movie, Christopher Nolan's Tenet (film) , also deals with destroying the past.
[Cueball and Black Hat talking.] Cueball: Well, you know what they say. The past is a foreign country- Black Hat: -With an outdated military and huge oil reserves! Black Hat: Hmmm...


Humming

Explanation:
Services like MusicBrainz and SoundHound can detect a recorded song's acoustic fingerprint and match it with an existing song. This lets them identify the title and artist of an unnamed recorded musical extract. In this comic, Megan hacks the acoustic fingerprint database to add her own entry with a message to Cueball , in which she asks him to buy cat food .
HTTP error code 406 means Not Acceptable. When a client requests data from a server, the client lists the data formats that it can accept. If a server is unable to provide data in any format that the client accepts, the server returns error 406 Not Acceptable. For example, this can occur if a client requests XML but the server supports only JSON. In the title text, the standard meaning of the error message is ignored and the text "Not Acceptable" is taken literally: The server is offended by Randall 's humming.
[Megan is humming a tune.] Cueball: Hey. Cueball: What's that?
[Megan is still humming the same tune.] Cueball: What are you humming? Cueball: Should I know the tune? Cueball: ...Hmm...
[Cueball gets out his phone and opens up a music recognition program.] Phone: Identify song Phone: Recorded Phone: > Live [beta]
Phone: Identifying...
[A zoom in on the phone screen. An album cover with a picture of Megan on it.] Positive match: Check it out! By I hacked the audio fingerprint database Feat. MEEEEEE Track: We're out of cat food (pick some up?)


Externalities

Explanation:
This was the fourth April fools' comic released by Randall . The previous fools comic was 1037: Umwelt from Sunday April 1st 2012. The next was 1350: Lorenz released on Tuesday April 1st 2014.
This comic isn't a static image - even the title text changes depending on which part of the image you're hovering over. It presented a competition for students to see who could come closest to breaking a Skein hash but also an aid appeal for the Wikimedia Foundation.
There are quite a few references in the comic to Baidu . Baidu is a large Chinese Internet services company that employs thousands, whose shares are publicly traded on world stock exchanges. It's the predominant Internet search provider of China, and is sometimes called the "Google of China". It offers parallels for the Chinese market of many of the services that Google provides and offers its own encyclopedic wiki with a restricted edit policy to serve as a replacement for Wikipedia. Wikipedia reports that Baidu's search engine handled 56% of Chinese internet search queries in Q4 2010. and that in October 2012, Baidu ranked 5th overall in the Alexa Internet rankings. Given that explanation for the Baidu references in #1193 is still solicited for explainxkcd, Baidu apparently is not well known yet among savvy XKCD readers.
Baidu Search results reputedly follow the censorship dictates of the Chinese authorities, causing it to return censored responses to searches for politically sensitive terms like "Tianamen Square massacre" or "Falun Gong" when executed by web browsers that are connected via Chinese ISPs. When you execute such searches via Baidu in the US, the top links returned for these topics do seem to reflect Chinese government sensibilities although the uncensored English language Wikipedia articles for these topics are listed high in the query results. Baidu's reputation for censorship provides background for Megan's reply "but nothing about Tianamen Square" in response to the "Come and find your future at Baidu" employment enticement of panel one and also provides the background to understand the "It takes great minds to stifle other great minds" slogan of the second panel.
The blank regions in the above image are dynamically generated from various sources.
For the two days until comic 1194 appeared, a competition was underway to see who could come closest to breaking a Skein hash .  The first text line of the first panel contains a link to http://almamater.xkcd.com . This page contained the text:
Currently looking for Skein 1024 1024 input matching
On this page, users were invited to enter "Your school's domain name" — presumably intended to be their college alma mater. (At least in the beginning, only a few top-level domains were accepted.) If the user entered an acceptable domain (by xkcd's rules, which apparently changed during the 48 hours of the competition), they could then enter data values one at a time. For each data value entered, xkcd returned a hash value and the number of bits by which it differed from the target value. The object was to achieve the lowest possible number of differing bits, ideally zero.
A ranking page showed the lowest value achieved for each domain name entered, but not the data that achieved it. The first name on the list was substituted in various panels, and the third-place school showed in panel five. No data values were reported by xkcd, but various results were posted by users of the xkcd forums and on other websites, leading to copycat submissions, so that occasionally large numbers of institutions would show the same moderately low value.
After the end of the contest, the data submission page vanished, replaced by the final list of rankings, which shows that Carnegie Mellon University achieved the best score with 384 bits incorrect out of 1024.  The rankings only show a few hundred out of the several thousand domains submitted—presumably Randall chose to chop the copycat submissions off the end of the list, retaining only honestly obtained results.
In some cases, Megan's reply seems to correspond to the company.
The text in the second panel is based on the company in the first panel:
The text in the form varies independently of the text at the top, sometimes related to the organization in 3rd place:
The title text documents the different sources of data in the comic. The different title texts are:
[This was a dynamic image where the text changed during April 1st. The main title text also changed after the dynamic part was finished, and there are even different title text for different part of the comic. This transcript is of the final version of the comic, (no longer dynamic or changing), as displayed at present on xkcd, there are still four different title texts for specific panels. These four title text are for that reason included here in the transcript.]
[The basic title text for the entire comic is: "This comic went up on April 1st, and the panels changed throughout the day in response to readers doing things like breaking hashes, edited a rapidly-shuffling set of target Wikipedia articles, and donating to Wikimedia Foundation. (The vandalism is over now and CMU won the hashing contest.)" The other three title text are only active over certain panels.]
[The first panel with the caption and Megan below has it's own title text. A part of that panel is a link, and in the section where this link is active there is no title text at all. The title text for the rest of the first panel is: "Happy April 1st, everyone!"]
[A panel with only text is above the first drawing. There is a link on the top part of the text to http://almamater.xkcd.com/ (the link is now broken).] Ahoy, carnegie melonites! Come find your future at Baidu.
[Below, not in a frame, is Megan.] Megan: But nothing about Tiananmen Square.
[Caption floating above the frame of the next panel:] It takes great minds to stifle other great minds. [Ponytail sits at a desk, hand to her chin, with two Cueball-like guys with their hands on the table.] Ponytail: Let's block Canada Cueball-like guys: Sounds good.
[Ponytail crouches on a moving Roomba (labeled) with a steaming mug of coffee in one hand and a smartphone in the other. Above her is a caption. The Roomba makes a noice] We're a convenient four hour drive from New York City (15,000 hours by Roomba.) Whirrrrrrr Roomba
[Ponytail and Hairy corners Cueball as he walks out of a door, and a black haired ponytailed girl is moving towards him wielding a giant butterfly net. There is a caption above them:] Our recruiters are on the hunt for unaware CMU graduates
[The fifth panel has it's own title text only active within (or very close to) the frame. It is: "uic has the third best hash. See the full standings at http://almamater.xkcd.com/best.csv" (The link is now broken)]
[There is a caption above a website application. There is three fields to be filled, with each their caption and text:] or uic graduates, provied any of them manage to fill out the application correctly. Name which one Email forget it Education Riding the L all night long
[Caption floating above the frame of the next panel:] At Baidu, Inc., you'll have the opportunity to work on cutting-edge projects. [Cueball sits at a computer.] Cueball: What does "make dog" do? Off-screen voice: Experimental dog generator. Don't click on it; the default size isn't set, so- *click*
[The last three panels has their own title text, only active within a frame that could contain all three panel. Outside that "frame" (all the way around) is the other title text. Within the title text is: "The dog gains a pound for every $10 donated to the Wikimedia Foundation via this link. Currently at $51135.33."]
[Small insert panel, going in above the next larger panel: Cueball stares at the screen.] Kzzzt *bip* Off-screen voice: Uh oh.
[A giant dog looks down at the desk where the computer once was, now only the wires are left. Cueball, leaning way back in his office chair, holding his hand to his mouth, stares up at it.]
[Again a smaller insert panel above the large one with the dog. A graphic showing two sliders and a dog (similar to the one in the previous panel). Next to the dog with arrows pointing to it are a thermometer graphic and an equation. Below is an e-mail type text and finally a caption. There are arrows over and under "God" and "dogs" between the g and d's.] d(x)=R [email protected] , Inc. Play God with dogs. TM


Stratigraphic Record

Explanation:
We have no rock formations on Earth older than about 3.5 billion years, as the comic points out, because everything solid from before that time has been subducted down into the Earth's mantle , by tectonic movement . The title text hints at the cooler Moon which stopped re-melting its surface much sooner, so we theoretically could learn something about Earth's history from examining our Moon's surface and makeup. Zircons are a type of mineral found in the Earth's crust , some of which have been estimated to be as old as 4.4 billion years, older than any other mineral.
Anyways, here the Earth is anthropomorphized and actively teases the narrator; first it asks the narrator to draw in closer, as if it's about to tell us a secret, but then it whispers "I'll never tell".
[Image of the Earth in color as seen from far off in space with pitch black around the Earth. Two blocks of text are above and below the Earth in white rectangles:] Nearly 4.5 billion years ago, Earth had liquid water. But all the crust older than 3.5 billion years has been recycled into the mantle by subduction.
[Same image of Earth, but now with only the middle of the panel black. Above and below is white sections (without a frame) with text:] A billion years of the stratigraphic record, the memory of the hills, is forever lost to us. What was it like here, four billion years ago?
[A slimmer panel as the first, with two smaller white rectangles with text above and below:] Earth, What secrets do you have?
[Similar panel, but now without the white rectangles. Instead a line comes up from the Earth as it speaks with white text, and in small letters, unlike normal xkcd text:] Earth: come closer
[Zoom in on the Earth so it now fills almost the entire panel from left to right.]
[Further zoom in on the Earth so now only part of the Earth can be seen in the panel. There is still black above, but not on the other three sides of the panel, which is filled with the Earth. It shows the northern part of the Earth with Alaska, Canada and some of mainland USA with one of the great lakes visible at the top right. The sea ice at the North Pole is also visible as are a small part of Russia near Alaska. Again the Earth speaks as in the first panel:] Earth: i'll never tell.


Flowchart

Explanation:
Flowcharts are diagrams used to show the logical flow of an algorithm , process, or program. Flowcharts are a recurring theme in xkcd . In this comic, Randall uses the fact that flowcharts can indeed be used to show a loop in the procedure: in this case, the reader will theoretically become trapped in a loop of reading the text in the diamond, following the line marked "YES," and ending back up in the diamond. Those familiar with flowcharts will notice though that, while diamonds usually contain decision questions (which can be answered multiple ways), the diamond here actually includes a statement instead.
The title text contains a suggested solution to the loop: the way to escape the loop is to use a marker and add an additional "NO" arrow proceeding from the diamond to a rounded box labelled "END" before you start the algorithm at "START." This suggests that the decision question in the diamond could more properly be phrased as "Is this flowchart a trap?" However, to follow this suggestion, you would need to actually have the marker that you are about to write instructions to go get. Thus, you must also add the instruction "get a marker" somewhere before the flowchart actually begins (before "START"), so that you actually have the marker by the time you get to the flowchart in the comic. And since you did not have a marker and could thus not write this way out, you are still trapped!
Of course, the reader could disregard the algorithm, but this would break the conventions of following the flowchart. This is perhaps part the comic's purpose - to suggest that a problem cannot be solved from within the confines of its own conventions.
Randall has made use of flowcharts before, and previously released another comic named 518: Flow Charts .
[A flow chart is shown with two boxes and two arrows. The first box rectangular:] Start
[From the first box there is a short arrow straight down to a diamond shaped box:] Hey, wait, this flowchart is a trap!
[An arrow continues down below from the bottom corner of the diamond box, where there is labeled, and quickly it turns left (in the direction of the arrow), going out under the diamond and then turns left two more times to end up on the right corner of the same box where the arrow points back again.] Yes


Subways

Explanation:
The comic shows the maps of all North American subway networks. In reality, none of these systems are interconnected, but in the diagram subways from different cities that have the same color on the official subway map have whimsically named connections, such as the "Ohio-California Tunnel" connecting the Green Lines of Cleveland and Los Angeles, or the "Rocky Mountain Tunnel" connecting the Blue Lines of Chicago and San Francisco. Vancouver and San Francisco are connected through a station called Richmond, which appears to double as Richmond, British Columbia and Richmond, California . The "Springfield Monorail" is fictional, from the animated series The Simpsons (see Marge vs. the Monorail ), but its approximate location on this map would suggest the Seattle Monorail , or perhaps Springfield, Oregon, which Matt Groening revealed was the inspiration for the  Simpsons' hometown .
The Urban Mass Transit Systems of North America map (right) created by Yale Professor Bill Rankin on his web site Radical Cartography in 2006 presents all of the subway systems in North America at the same scale using geographic, instead of topological, layout.
The networks on xkcd's map are displayed with absolutely no consideration to geographic position, in order to connect like-colored routes together. While Vancouver is the most North-West, Mexico City being the most South, and San Francisco the most west, distances are not accurate (in reality, Vancouver is closer to Chicago than to Toronto for example) and cities are often arranged in the wrong direction from one another:
The map's design is modeled after the system map of the Massachusetts Bay Transportation Authority in Boston where Randall is from.
Not all cities with a subway are shown on the map. Missing from the map:
Subways of North America [A subway-line style (bold colored, 45-degree aligned lines with white bars indicating stations) map has been constructed by combining and linking various parts of the subway maps from many different cities, as if all of the transit systems were connected directly. The cities include (from top to bottom, left to right) Vancouver, Montreal, San Francisco, Toronto, Boston, Chicago, Los Angeles, Cleveland, New York City, Philadelphia, Baltimore, Washington DC, Miami, Atlanta, Monterrey, San Juan, Santo Domingo, and Mexico City.]


All Adobe Updates

Explanation:
This comic was probably a reaction to the installation service Ninite removing Adobe Flash Player from their free version the previous day.
The comic makes fun of Adobe Systems software that delivers new versions of Adobe products to users' computers, such as Adobe Updater (which replaced Adobe Update Manager ) and Adobe Download Manager (which replaced Akamai ). These software increments might either be technical (to fix compatibility or security issues), or they might add new features that would go unnoticed. In addition, these updates are downloaded automatically by default, but the operating system might install them only if a user allows it to. The frequency of software changes (and changes in the way Adobe allows users to download new software) could result in confused users. In this case, the comic is saying that you must update the program before it can actually check for updates, something it already seems to be doing.
There is an actual message that a specific version of these updaters display:
The Adobe Updater must update itself before it can check for updates. Would you like to update the Adobe Updater now?
In fact, the general necessity of such update managers has often been questioned, as they require the user to "download software in order to download other software". Other notable examples of companies who use update managers include Google and Sun / Oracle , with the latter being also mentioned in the title text.
The two buttons 'OK' and 'Download' are implied to have the same effect, indicating the user has no real choice. Or, alternatively, 'OK' may simply just close the dialog without taking any action, as that is common in informational popups in many pieces of software. In that case, the placement of the 'OK' button implies that it is the default action, meaning most users will just ignore the update. Given the extreme frequency and perceived lack of changes (to your average end user), this anecdotally seems to be what most people do. Statistics for the high rate of un-patched systems in the wild support the anecdotal evidence.
The language of the message also plays with repeated up and down , as in "there is an up date for the Adobe down load manager..." to give the whole process a feel of preposterousness verging on Carrollian literary nonsense .
The title text also suggests that using update helper software which in turn must be updated bears the risk of creating a dependency hell .  The "version 21.1.2 of the Oracle..." may refer to the Rush suite 2112 , where moment V is titled Oracle and contains the lyrics "I stand atop a spiral stair, An oracle confronts me there."
[Cueball is sitting at a laptop with a window with a red title bar floating over his head.] Adobe Update There is an update for: Adobe Download Manager This update will allow you to download the new updates to the Adobe Update Downloader. [OK] [Download]


Geologist

Explanation:
Geology is the study of the physical and chemical makeup of the Earth and geologists are sometimes called rock hunters, sometimes derisively.
Hunters, after killing an especially difficult or rare beast, sometimes remove its head and hang it up on a wall as a trophy . Cueball , as a geologist, "kills the Earth" by shooting at it. He removes its "head," a chunk of rock, and hangs it up on his office wall. Above the trophy it says Earth, and below it gives it lifespan from 4,500,000,000 BCE (Before Common Era )), which is the current age of the Earth, and then until the day where he shot Earth, which is also the day this comic was released 2013-04-12. The topic of hunting things that are not usually hunted is also in 640: Tornado Hunter
The title text is probably a reference to a chicken running around with its head cut off. A few billion years (7,600,000,000 years) is also about how much longer the Earth is expected to last, assuming it gets swallowed up by the expanding Sun at the end of the Sun's life .
[Cueball, wearing earmuffs and goggles and holding a gun and a rock hammer in his hands, is walking away from his van in the background towards a group of rocks. The largest of these rocks is almost as tall as Cueball, but five smaller rocks are scattered on the ground, with a bit of grass growing at their bases. The van has text on its side:] Dept. of Geology
[Zoom in on Cueball close to the base of the largest rock. He has put the rock hammer on the ground next to him and aims his gun at the ground and shoots three holes in the earth, the last hole is just forming, as smoke comes out of the end of the gun.] Blam Blam Blam
[Zoom out again with Cueball hacking away at the top of tallest rock formation with his rock hammer. The gun has been left near the three holes in the ground. The van can again be seen as can most of the text.] Clink Clink ept. of ology
[Cueball, without his head gear, sits at his desk in his office reading a piece of paper he holds in his hands. Three other papers are lying on the otherwise empty desk. Behind him various items hangs on the wall most likely images and diplomas etc. One of them is blank, two looks like images, and four has unreadable text. The last item is the top of the rock that he just chipped off in the previous frame. It has been attached to a mount as a hunting trophy. Above and below there are labels:] Earth 4,500,000,000 BCE - April 12, 2013


Silence

Explanation:
4'33" is a 1952 composition by American avant-garde composer John Cage consisting of four minutes and thirty-three seconds of silence. More specifically, 4'33" consists entirely of faint ambient sounds coming from the environment, while all the players silently hold their instruments. The noise of the audience is considered part of the composition. It is Cage's most famous work, and the subject of many music jokes. Note that John Cage wrote plenty of other non-silent things.
Megan is using an app on her smartphone that analyzes music that is playing and uses an online database to figure out what it is; popular real-world examples include Shazam and SoundHound . She does this in an empty room, correctly matching 4'33" . Cueball attempted to use the same app in 1192: Humming , but Megan hacked it there.
The title text refers to the fact that since 4'33" is composed of the ambient sounds in an environment, if that environment is a recording studio, live music venue etc. the ambient sound is a band playing another song.
[Megan is walking with a phone in her hand.]
[Megan stops.]
[Megan raises her phone.] Phone: Identify song recorded Phone: > LIVE [Beta]
[Megan is in an empty room.] Phone: Listening...
[The phone screen.] Positive match: 4'33" John Cage


Authorization

Explanation:
Computer operating systems were initially written for the business environment. Thus they were made to be accessible to multiple employees, or users , but only fully accessible to administrators (or admins). Regular users can access and use programs on the computer, but only the admin is allowed to make changes to how the computer runs.  This same split level of security continues to this day, even in privately owned, or "home", computers.
The joke here is that the most important things on a computer are no longer the programs that it runs, but the private personal data it accesses (usually online). Anyone who wished to do real mischief on an active computer could do considerable damage without ever caring what the admin password was. The admin password, in effect, now guards a vault no one cares about.
This comic pokes fun at the authorization mechanisms surrounding most operating systems' administrator accounts. It makes the argument that the user's data is more valuable than the integrity of the system. This is arguably true for most personal systems, although it is probably not true in a shared-server setup, where a system compromise could lead to the exposure of many users' data.
Essentially, once a user is logged in , they can typically access all of their data without any further restriction. Modifying the operating system (for example, to install drivers ) requires a separate password.
In fact, this password protection also hinders installation of malware , which is otherwise possible even remotely, with the malware then being able to e.g. steal passwords, enabling a hacker anywhere in the world to access your accounts without ever needing to touch your computer. So having your computer set up to not to ask you for an administrator's password arguably implies a bigger risk of identity theft than allowing others to access your system physically while being logged in does.
The title text alludes to the security practice where computers automatically lock the user out after a few minutes, requiring a password from the user in order to continue using it. Instead, Randall's computer automatically switches to his brother's account, presumably compromising his data instead of Randall's. The fact that Randall's brother has an account on Randall's computer even though Randall does not live with his childhood family (so his brother would not need to use his computer often) could be because Randall does not want his brother to be able to access his files, PayPal, etc… when he uses his computer, which would indicate that either Randall is cynical, his brother is not trustworthy, or Randall is simply following the principle of least privilege .
[Diagram showing several connected bubbles. One in the center says "User account on my laptop," surrounded by "Dropbox," "Photos & files," "Facebook," "Gmail," "PayPal," and "Bank," which are connected to the middle bubbles and to each other. Below the middle bubble is one labeled "Admin account," which is covered in spikes, and has a "door" to the bubble above it.] If someone steals my laptop while I'm logged in, they can read my email, take my money, and impersonate me to my friends, but at least they can't install drivers without my permission.


Integration by Parts

Explanation:
Integration by parts is an integration strategy that is used to evaluate difficult integrals by trying to find simpler integrals derived from the original. It is commonly a source of confusion or irritation for students when they first learn it, due to the fact that there is really no way to accurately predict the proper u/dv separation just by looking at an integral. Integration by parts requires patience, trial and error, and experience.
Randall shows a somewhat complicated math problem and, in an attempt to "help", simplifies it into a more compact integral. This is the first part of performing integration by parts, which involves the guessing. Having gotten it into integration by parts format, he then leaves without describing the actual solution. The general integral ∫ (u dv) is equal to uv - ∫ (v du) , and this is the more tedious part of the math and where problems will arise if you picked the wrong u and dv at the beginning. The narrator makes a point of leaving here, so we can't ask for help or complain if the choice of u and dv was wrong.
The title text points out that if the integral of x can be divided so that u = x and dv = dx and implying v = x, then it leads to the result (1/2)x². This implies the original integral was just ∫x dx, and not needing integration by parts in the first place. Mathematics teachers and extreme math geeks will also cringe at this answer, however, since an indefinite integral requires an integration constant. The correct answer is actually (1/2)x² + C, as Randall hints. The +C symbolizes that an indefinite integral can be shifted by any constant and still gets the same answer on the reverse derivative . Definite integrals specify a range that they're valid on and thus there is no need to add this constant.
A Guide to Integration by Parts:
Given a problem of the form: ∫f(x)g(x)dx=? Choose variables u and v such that u=f(x) dv=g(x)dx Now the expression becomes: ∫udv=? Which definitely looks easier. Anyway, I gotta run. But good luck!


Girls and Boys

Explanation:
This comic is a play on the popular school-yard taunt , "Girls go to college, to get more knowledge; boys go to Jupiter, to get more stupider," also commonly heard as "Boys go to Mars, to get more candy bars; girls go to Jupiter, to get more stupider." The words "boys" and "girls" may be interchanged, depending on the gender of the person chanting. The schoolyard taunt embodies the competitiveness and separation commonly seen between young boys and girls, and ideas about the superiority of one's gender.
It should be noted that, historically, most higher education was preferentially or exclusively reserved for men, but that changed rapidly over the course of the 20th century. By the late 1970s more women than men were enrolling in college, and that trend has only increased, to the point where women make up nearly 60% of undergraduate students in American colleges and universities. This is an issue of substantial concern, because it reflects national trends in men failing to achieve academically. This comic may be pointing out that this gendered competition, which is often inculcated from an early age, is counter-productive, because it focuses on one gender succeeding at the expense of the other. In truth, human achievement is maximized when both men and women are given opportunities to gain skills and succeed.
The comic subverts the original rhyme by having both girls ( Megan ) and boys ( Cueball ) go to college to gain knowledge, and then using that knowledge to go to Jupiter as part of a space program , working in cooperation with other men (another Cueball-like guy) and women ( Ponytail ).
Going "to Jupiter, to get more stupider" is ironic considering that human beings have not yet even gone to Mars, so to go to Jupiter would take a huge amount of knowledge, investment, and further development of current technology. Likewise, people in space programs going to Jupiter would have advanced degrees, a great deal of knowledge, and a motivation to seek out more knowledge. Space programs and going to Jupiter would require the cooperation of many different people, men and women included, rather than the divisive atmosphere of the schoolyard.
The title text points out that by going to Jupiter you would get more knowledge , which is generally the purpose of any space program; that is, the purpose is to advance science, and it wouldn't actually be dumb at all. Therefore, the task of going to Jupiter is absolutely dependent on going to college, cooperation, and getting more knowledge; entirely the opposite of what the schoolyard taunt suggests.
[Megan facing left is sitting on a stool at a table while studying. She is bent over her paper writing on it, while her laptop is standing open on top of two books lying in front of her. In front of her, just inside the panel to the left is the back and neck of another student sitting on a chair visible, with only the rear leg and back of the chair shown. Behind her just inside the panel to the right is the front end of another table, one leg visible, and here lies a pile of paper, as tall as the two books. Two frames above Megan narrates the poem:] Girls go to college To get more knowledge
[Cueball facing right, is sitting on a chair at a table also studying. He is holding a piece of paper up in one hand head turned toward it. His other hand holds a page, with text shown as thin lines, in the open book lying in front of him. His laptop is standing open behind the book. In front of him, just inside the panel to the right is the back and arms of another student sitting on a chair visible, with only the rear leg and back of the chair shown. Behind him just inside the panel to the left is the front end of another table, one leg visible, and here lies a pile of four books. Two frames above Cueball narrates the poem:] Boys go to college To get more knowledge
[Space launch control room with Megan and Cueball standing in the middle of the room working together. Megan sitting behind a table with a rectangular item on top, holds a model of the capsule that goes on the top of a space craft in her hand pointing to it with the other hand while Cueball standing to the right gestures at the model as well. To the left sits Ponytail in an office chair, she is wearing a head-set and sits in front of screen, just inside the panel, she seems to be controlling something, but no keyboard is visitable. Above her is another screen attached to the wall (off-panel). The the right there sits a Cueball-like guy on a chair, who is also working on some screen, which is mainly off-panel as is the front of his head. On the wall behind there hangs two pictures. The first shows the curve of a white planet against black space, two continents or clouds visible. There is an insert in the top left corner with a small drawing, and some text or number (unreadable) in the top right corner. The other picture seems to show a space craft with two large solar panels, white on the black black background of space. Has some similarities to the international space station. There are four white lines representing text labels pointing to different parts. One frame at the top narrates the poem:] Girls and boys
[A large gray rocket with two lifter rockets, one on each side, launch into the black night, rising up with white fire out the end on top of a huge pile of gray exhaust smoke, that billows out filling the entire width at the ground level, where gray lines stars out on the black ground. A white rectangle right above the tip of the rocket narrates the poem (which first ends in the title text):] Go to Jupiter
Going to Jupiter was most famously explored in the film 2001 and its sequel 2010 , where a space ship lands on the moon Europa . The film Outland is set on a mining operation on Jupiter's moon Io .


Time Machines

Explanation:
Cueball activates a time machine to go back into the past. The time machine rewinds time, but in the process rewinds the event where the time machine itself was turned on, turning the time machine off in the process. He is now a few seconds in the past, prior to having activated the time machine, but he is baffled that he does not seem to have accomplished anything and turned off the time machine unintentionally. It would seem that the time machine is the world's most technologically-advanced " useless machine " (a device whose only purpose is to switch itself off when it is switched on).
The title text mimics a countdown to an event. "T minus 10," for example, means 10 seconds until the event. When the event is the activation of a time machine traveling back in time, after 10 seconds it will once again be "T minus 10," and a second later it will be "T minus 11," counting up rather than down. This casts doubt on the value of the countdown because, from the perspective of the time traveler, the event has already taken place.
Cueball is only able to travel back in time a few seconds because in this comic time is seen as continuous and linear from Cueball's point of view, so he can only travel back in time to the moment he activated the machine (the first series of "E"s is the machine warming up and the second series of "E"s is that in reverse) the logic behind this is that because time appears to be continuous, Cueball's input was required for the machine to work. Since it does not appear to be a traveling vessel, it is also possible that Cueball could trap himself in the past by traveling to a time before the machine was created, and it would remain in the present.
[Small caption above the first panel:] The problem with time machines: [Cueball has his hands on the lever of a time machine.]
[Cueball flips the switch from OFF to ON.] Switch: Click Time machine: E E E E E E EEEE
Time machine: EEEE E E E E E E Switch: Click [Cueball flips the switch from ON to OFF.]
[Cueball looks at his palms.] Cueball: ???
This comic's title is very similar to 716: Time Machine .


Detail

Explanation:
Google Earth is a mapping software service provided by Google that allows people to view the Earth from above. If zoomed in to maximum magnification, one can obtain clear views of individual streets and homes.
An image's resolution is the smallest length detectable in that image. In terms of Google Earth, this refers to the real-life distance corresponding to one pixel in an aerial image. Randall points out that the level of detail in Google Earth's images has been increasing exponentially since its introduction, as aerial imaging technology improves and better ways of collecting the data are found. Each tick in the scale represents a resolution improvement by 1000 times.
In quantum mechanics , the Planck length is (in layman's terms) the smallest measurable distance, defined as approximately 1.6×10 −35 meters, or around 10 20 times smaller than the diameter of a proton. As the graph indicates, this may be called the "resolution" of the universe.
Randall extrapolates the exponential trend of Google Earth's increasing resolution, 'revealing' that by the year 2120 or so, Google Earth's resolution will approach and even possibly exceed the Planck length, an obviously fanciful and impossible idea. Current laboratory instruments cannot even get close to measuring the Planck length, barely able to reach the level of the atom. (Which, by the chart's prediction, will be surpassed by Google Earth at around 2040.)
Other comics exploring unwarranted extrapolation include 605: Extrapolating , 1007: Sustainable and 1281: Minifigs .
The title text refers to controversy that Google received at one point regarding their use of vehicle-mounted Street View cameras to take images of streets and houses, and how such photography could constitute an invasion of privacy. Google defended itself by stating that the cameras can see nothing more than a pedestrian walking by. Given the trendline in this comic however, Google would need to produce resolution in the nanometer range by 2031, which (using today's technology) would require the use of scanning electron microscopes . The same 'invasion of privacy' defense would obviously not work here, as 1) current scanning electron microscopes in labs can only be used with small specimens at very close range, and are completely unsuitable for observing something as large as a house or for observations from a passing car, and 2) most pedestrians are not equipped with scanning electron microscopes. [ citation needed ]
My Neighborhood's Resolution in: [A two-axis graph with years from 2000 to 2100 plotted on the x-axis and resolution from 1 meter to the Planck length plotted on a logarithmic scale on the y-axis. Three points in a line close to (~2010, 1 meter) are plotted at the bottom left of the graph; they have a strong positive correlation. Two trendlines are drawn on the graph; one is labeled "Earth" and remains constant at the Planck length over time; the other is labeled "Google Earth" and connects the aforementioned three points, extending upward in a straight line and approaching the Planck length around 2100. Both trendlines break up into question marks before the point they would intersect.]