Douglas Engelbart (1925-2013)

Explanation:
The comic describes and references the engineer Douglas Engelbart's computer demonstration The Mother of All Demos in honor of Engelbart, who died on July 2, 2013.
The demo is renowned for the numerous technologies Douglas' team introduced, which the comic references before sliding into apocryphal claims. In the first panel he presents various inventions, including the Computer Mouse . The second panel contains the opening lyrics of Leonard Cohen's song Hallelujah . The "Secret Chord" is a reference to the "Chord Key Set" that he presented at this demo. This relatively obscure device, essentially a piano with five keys, was meant as an alternative to the well-known keyboard. The way he introduces the song is also a reference to musical demo tapes , in which an artist presents a new piece of original music, tying it back to the Mother of All Demos title. The third is a reference to contemporary internet memes, specifically cat pictures and YOLO .
The title text is a reference to recent revelations about spying by the United States National Security Agency , which was making headlines when this comic was published. While it might have seemed like an advantage at the time, in a modern context this aspect of the internet appears disturbing.
Several of the inventions presented by Douglas in 1968 were years ahead of their time, and many would prove to be very influential in the development of personal computing. Some of the technologies demonstrated found success in the following decades, while others did not.
Although the following technologies were shown in the demo, Munro's text does not follow a transcript .
Cathode ray tube
The German physicist Ferdinand Braun invented the Cathode ray tube , or CRT, in 1897. The Russian scientist Boris Rosing was the first to use the CRT to receive a video signal. CRT was the most common technology used for television screens and computer monitors in the last century, but has since been succeeded by modern devices such as OLED , plasma display , or the ubiquitous LCD . In the demo, Douglas used CRT monitors to demonstrate video conferencing, as well as collaborative real-time editing.
Computer mouse
Douglas did refer to this device as a "mouse", but officially it was named the "X-Y Position Indicator for a Display System". He filed a patent for this device on June 21, 1967 and received the patent on November 17, 1970. The demo transcript records that Douglas stated: "I don’t know why we call it a mouse...it started that way and we never did change it."
Text movement/cloning
This is well known today as "cut, copy and paste". On some early text-based systems, the user moved the cursor to the beginning of the text to be copied, typed <CTRL>+K+B , and then moved the cursor to the end of the copied text and typed <CTRL>+K+E. At the demo, Douglas demonstrated that the same task could be accomplished with the mouse. Today, many people do not use keyboard commands for cut, copy and paste, and instead use the mouse exclusively.
Joint file editing
Text editors were in the nascent stage of their development in 1968. Douglas demonstrated the first text editor capable of "joint file editing". The first successful system to implement joint file editing came 15 years later, when CVS was made available in the middle of the 1980's.
E-mail
Although not referred to as e-mail, Douglas demonstrated the exchange of "direct messages", which fulfills a similar role to modern e-mail. Nowadays, though, the name will be more familiar as the term for Twitter's private messaging function.
File sharing
The demo also demonstrated the exchange of files between users, paving the way for modern file sharing, and the associated legal and ethical debate.
Audio codec
Douglas demonstrated a "masking codec" capable of coding and decoding an audio stream. This would eventually lead to the development of the wide variety of modern audio codecs, including the MP3 codec, which was produced by the Fraunhofer Society .
From the bottom of the second panel the comic exaggerates the idea that Douglas introduced the future to a hilarious and ridiculous level.
"Hallelujah"
This song was first released by Leonard Cohen in 1984, sixteen years after Douglas's demo.
Image macros
A form of image with large text, typically block capitals in the font "Impact", superimposed over a photograph, typically for humorous effect.
LOLcats
The most famous of the image macros, featuring cats.
YOLO
As the fictional Douglas states, this is an acronym for "you only live once". The phrase has been around for at least a century, but was coined as an acronym around 2011, and became a popular catchphrase following its use in the rap song "The Motto" by rapper Drake.
San Francisco, December 9th, 1968: [We see a figure talking into a headset. It's a fair assumption that it's Douglas Engelbart.] Douglas: ...We generated video signals with a cathode ray tube... We have a pointing device we call a "mouse"... I can "copy" text... ... and we have powerful joint file editing... underneath the file here we can exchange "direct messages"... [Douglas continues to narrate. Some music is playing.] Douglas: ...Users can share files... ... files which can encode audio samples, using our "masking codecs"... The file you're hearing now is one of my own compositions... Music: I heard there was a secret chord [Douglas continues to narrate.] Douglas: ...And you can superimpose text on the picture of the cat, like so... This cat is saying "YOLO", which stands for "You Only Live Once"... ...Just a little acronym we thought up...


Settled

Explanation:
Displayed is a timeline chart showing the percentage of people in the United States who have a camera at every moment. Randall refers to the fact that today most people carry embedded camera devices using their cell phones or the even more modern smartphones .
The chart shows that after the 1980s the percentage increases rapidly, almost reaching 100% by 2013. The text below the image states that "We have conclusively settled the questions of flying saucers , lake monsters [such as the Loch Ness Monster ], ghosts , and Bigfoot ", implying that because almost everyone carries a camera the evidence should have arisen by now to settle any question about such phenomena. Of course, such evidence has not arisen — but that doesn't stop many people from continuing to believe the myths. But at least now it is hard to claim that you saw something, but didn't have a camera to capture it with. If something moved by so fast that you did not have time to take a picture, then it could also be questioned if you have time to see that it was a ghost etc.
The title text declares that, in the case of ghosts, only the questions regarding phenomena that can be captured with a camera have been settled - leaving, in other words, ghosts that can't be seen, heard, or felt are essentially indistinguishable from an absence of ghosts. The title text also makes a joke about the ghosts of Ghostbusters , a popular film that featured highly visible and noisy ghosts which left a slime. If such ghosts existed, recording them would be very easy.
[A graph with percentage from 0 to 100 on the Y-axis with three ticks with labels, top, middle and bottom. The X-axis is a timeline with years with labeled ticks at every five years interval from 1980 but also including a final tick at the year of release, 2013, which is written in a smaller font. The graph shown a red line that starts before 1980 at just above 0% and stays there through the 80s, rises a little past 1990 and reached 1-2% at around 2000, but then it rises rapidly to 10% at 2005, 75% at 2010, and around 90% at 2013, where the rise begins to flatten out asymptotically towards 100 %. There is a caption for what the Y-axis represents over the flat part of the curve:] Percentage of the US population carrying cameras everywhere they go, every waking moment of their lives: Y-axis labels: 100% 50% 0% X-axis labels: 1980 1985 1990 1995 2000 2005 2010 2013
[Caption below the panel:] In the last few years, with very little fanfare, we've conclusively settled the questions of flying saucers, lake monsters, ghosts, and Bigfoot.


Seashell

Explanation:
This method of relating the probabilities of two events is known as Bayes' Theorem .
If you put a seashell up to your ear, you might hear a sound similar to the ocean apparently inside the shell. But the idea that this sound is actually the sound of the sea is just a popular myth: hold only your hands close to your ears and you will hear the same sound, as it is the sound of your blood moving through your blood vessels that causes the sound. The comic, through an application of Bayes' Theorem, points out that most of the time when you pick up a seashell, you are in fact at the beach next to the real ocean, so hearing the ocean at that location is not all that impressive, but it's just real.
The equation should, however,  be read as follows: (The probability that I'm near the ocean, given that I picked up a seashell) is equal to (The probability that I picked up a seashell, given that I'm near the ocean) multiplied by (The probability that I'm near the ocean) divided by (The probability that I picked up a seashell).
The title text points out that most instances where the author has picked up a seashell have been at the beach, and nearly all of the times where he has picked up a seashell and not put it to his ear have been there.
This comic was released late. In the first version, the formula was incorrect, but it has since been corrected.
[At the top of the panel is an equation showing Bayes' Theorem for the probability that a person is near the ocean given that they just picked up a seashell.]
P(I'm near the ocean|I picked up a seashell) =
P(I picked up a seashell|I'm near the ocean)P(I'm near the ocean) ------------------------------------------------------------------------------------------------ P(I picked up a seashell)
[The probability that I'm near the ocean given I picked up a seashell equals the probability I picked up a seashell given I'm near the ocean times the probability I'm near the ocean all divided by the probability I picked up a seashell.]
[Cueball holds a seashell and stands to the left of the panel, to the right, a few birds are flying around and the sound of a wave crashing against the shore is depicted.] Crashhh Sploosh
Statistically speaking, if you pick up a seashell and don't hold it to your ear, you can probably hear the ocean.
Note that while this form of Bayes's theorem is often taught in statistics classes, at least one statistician tries to show in a philosophical way that unconditional probability does not exist, which would make the equation improper as stated.


QR Code

Explanation:
QR codes (quick response codes) are a type of 2D barcode that can be scanned using any of several apps on a smartphone. This comic illustrates installation of a new application that requires the smartphone to scan a QR code on its own screen. There is no conceivable purpose for such a step, so it would be completely silly. Even with two mirrors or a front-facing camera and mirror, most smartphones would be unable to simultaneously display the camera feed for the QR scanner and the QR code itself. The only way to do it would be to take a picture of the QR code with a digital camera and then scan the screen of the camera. The "12 seconds remaining" part indicates that there is a time limit for this, and thus a quick response is necessary.
If scanned, the QR code in the comic reads http://xkcd.com/1237/scan/ , a link to a nearly identical image, but the line above the QR code reads, "To continue reading," and the caption reads, "How to trap a webcomic reader in an infinite loop". The QR code is identical to the previous one. So, if scanned again, it would simply return the scanner to the same image in an "infinite loop".
[A smartphone. On the display, the following text:] "To continue installing, scan this code. 12 seconds remaining" [A particularly recursive QR code is displayed on the screen.] [Caption below the panel:] How to freak out a mobile app user.


Enlightenment

Explanation:
This comic is a reference to a scene one might imagine in Star Wars Episode I: The Phantom Menace in which Yoda expresses doubt in a young Anakin 's potential to join the Jedi order. Yoda delivers a speech similar to the one that Ponytail gives here, except that the end of the sequence he presents is " the dark side " instead of "being an asshole". Yoda is ultimately correct; Anakin's fears lead him to join the dark side so that he may keep his loved ones from dying; this is at the expense of the stability of the galaxy, however, and his actions are in vain, as his wife dies nonetheless. The circle on the ground is also taken from the Star Wars scene, and Cueball is presumably in the Mace Windu role.
Here, Randall compares Anakin's decision to join the dark side to the propensity of many Internet commenters to correct others on their spelling and grammar, and to the extreme prevalence of criticism over commendation or confirmation. Randall's point is that correcting people, like joining the dark side, ultimately stems from insecurity.
Ponytail and Cueball challenge Megan to type the sentence "I heard you're idea's and their definately good", which contains four common misspellings ( you 're instead of you r , idea ' s instead of ideas [see greengrocers' apostrophe ], the ir instead of the y're , and defin a tely instead of defin i tely ), a misapplied verb ("heard" instead of "read"), and a grammatical error ( a missing comma [1] before the word "and").
Regarding the content, this sentence is one that is highly unlikely to be ever read in an internet argument, as almost every time people still have things they claim to know better about.
Megan thus can't bring herself to typing this sentence, having spent so much time judging others for their trivial errors, even when they're saying helpful things like the sentence in question. Instead, it is strongly implied that she smashes the computer and runs away — demonstrating the sort of anger that "Grammar Nazis" and internet wiseacres like her can feel about punctuation and spelling errors, and about content-related errors respectively. Cueball and Ponytail remark on this, both failing to use apostrophes .
The title text refers to Terry Pratchett 's novel Equal Rites , in which the characters discover that the most powerful magic is not using magic — with the distinction that not using magic because you don't know how is not the same as choosing to refrain from using magic when you do know how. Randall is comparing this with use or misuse of the rules of Standard English: not even knowing the rules is not admirable, whereas knowing the rules but choosing to disregard them is. There is also a double meaning - not writing anything at all is in fact "saying nothing".
[The two Internet Bodhisattvas Ponytail and Cueball lecture Megan encircled by a wheel placed upon the ground.] Ponytail: To achieve internet enlightenment , you must free yourself from insecurity. Megan: But insecurity keeps me humble!
[Ponytail continues talking.] Ponytail: No. Insecurity leads to conceit. Conceit leads to judgment. Ponytail: Judgment leads to being an asshole.
[A laptop is placed on a stand in front of Megan.] Megan: I'm ready. How do I begin? Ponytail: Type this sentence. [White text on black background.] I heard you're idea's and their definately good.
[The laptop has been smashed to the floor. Megan is no longer in the circle.] Ponytail: She wasnt ready. Cueball: Its a difficult road.


Social Media

Explanation:
This comic parodies how journalists tend to focus on social networking. Specifically in the case of revolutions, social media is given a lot of weight, even in countries with limited internet access. A direct parallel is made to the so-called Twitter Revolutions .
On Twitter you can send text messages with a maximum of 280 characters (140 at the time of writing). This means that there could not be much content in a single post, but often many people follow the people doing these tweets . People who are not on social media tend to react like Cueball and come to the conclusion that Twitter makes press coverage more stupid, just because those messages lack much detail. Cueball is also surprised about the stupidity of trying to link social media to the orbit of the asteroid — social media has no impact on the orbit of any space objects. [ citation needed ]
The title text continues the joke. The negativity on Twitter concerning an Earth-bound asteroid has nothing to do with the press conference that announced it but rather with the negativity of wiping out life on earth in general. Again, journalists give undue weight to social media.
It's simply that "How has Twitter affected this" has become a standard question for journalists, posed in complete disregard of the actual event.
[Cueball heads a press conference.] Cueball: NASA has confirmed that the asteroid is heading directly for us. Cueball: ...Yes, a question? Reporter 1: What role has social media played in this asteroid's orbit? Cueball: * sigh * Reporter 2: Has Twitter changed the way we respond to asteroid threats? Cueball: Well, it's made the press conference questions stupider. Reporter 3: Fascinating! Reporter 4: What about Facebook?


Quantum Mechanics

Explanation:
This comic plays with the fact that quantum mechanics is a very complex subject that is frequently misapplied by laymen. Many of the phenomena studied in quantum mechanics are contrary to common sense and can only be expressed in complex mathematics. Yet, since the field is fundamental to our understanding of reality, it is commonly cited to support broad sweeping philosophical generalizations.
The phrase “according to quantum mechanics” betrays the speaker's lack of knowledge about the subject. To a physicist, it is almost as vague as “according to physics”. Somebody who understands the subject would use a more precise term, such as “according to the uncertainty principle” or “according to a paper by such-and-such.”
Cueball explains to Ponytail that dogs must have souls . This would be against the doctrine of certain religions, including some sects of Christianity, which teach that only humans have souls. The question of whether animals have souls comes up for many reasons in theological and philosophical discussions. One major one is the wish of many dog owners to meet their pets in Heaven . For this to come to pass, it would be necessary for dogs not only to have souls, but also immortal souls. This distinction comes up in Catholicism, for example, where the commonly taught doctrine, as in Aquinas, S.C.G. II, C. 82 , is that, while animals do have souls, their souls are mortal, and therefore die with their bodies. In this case, animals cannot enter Heaven, Hell , or Purgatory .
Cueball, however, uses quantum mechanics as an argument, even though quantum mechanics is only applicable on the atomic scale and not on macroscopic objects like animals. It also only applies to matter and energy, and not to souls, which are held by most doctrines to be immaterial. His argument, however, is a reference to the concept of an ' observer ' in quantum physics, as well as theories about the collapse of wave functions . It should also be noted that science does not equate the ability to observe the world and possession of a soul, and that the latter is merely a theological concept, not used in science and not proven to exist in real world.
The vast majority of people do not have a sufficient understanding of quantum mechanics to judge whether Cueball's statement is correct. Nevertheless, Randall's message is: you don't need to understand quantum mechanics to judge the statement. No matter what the sentence is, it is almost certainly incorrect, so “you can safely ignore” it.
The title text refers to “science assertions” — that is, claims about scientific knowledge — that include the words “quantum mechanics”. If “quantum mechanics” is the most complicated term in the sentence, then the speaker probably does not know what they are talking about. If a scientist is correctly applying quantum mechanics, they will use more specific (and hence more complicated) language.
[Cueball and Ponytail stand facing each other, talking. Cueball has a small dog on a leash.] Cueball: But dogs can observe the world, which means that according to quantum mechanics they must have souls.
[Caption below the frame:] Protip : You can safely ignore any sentence that includes the phrase "According to quantum mechanics".
Anyone who is not shocked by quantum theory has not understood it.


Annoying Ringtone Champion

Explanation:
This comic satirizes the large variety of ringtones that may be used on their cell phones. While many are simply tunes that personalize a user's phone, some will use ringtones that resemble everyday sounds, such as doorbells, coughing, alarm noises, or in this case, the buzzing of a mosquito. Although rather innocuous, these ringtones can get very annoying to some people, which is what this comic is getting at.
Here, Black Hat has set his ringtone to "The sound a mosquito makes as it buzzes past your ear", the winner of the "Awful Ringtone Championship". Cueball , hearing the sound, cries out and swats the air around his head, mistaking the ringtone for an actual mosquito buzzing past his ear. In addition to being an extremely unpleasant sound, it could also cause confusion to others, as shown in the comic, thus being unanimously decided as the most annoying ringtone. Black Hat 's response is likely a pun meaning both "Oh, I've got to take this [call]" (like someone who has been interrupted by a phone call) and need to leave and respond and "Oh, I've got to take this [competition]" since the ringtone is so annoying.
The title text refers to four other annoying ringtones, apparently none of which were deemed as annoying as a mosquito buzzing:
[At the top of the frame is an annoying humming tone shown. Cueball is cringing while raising his arms above his head. Black Hat pulls out his phone looking at it.] Ringtone: h MM M MM M M M M M MM MM M MMM Cueball: Augh! Black Hat: Oh, I've gotta take this.
[Caption below the frame:] By unanimous decision, the winner of the Awful Ringtone Championship is "the sound a mosquito makes as it buzzes past your ear".


Scary Names

Explanation:
This chart humorously explores how things are often named colloquially and without regard to accuracy in correlating actual scariness with apparent scariness. It is interesting to note how people react to the items near the bottom right of the chart "scary things with not-very-scary names" when compared to how they may react to items in the upper left "not-very-scary things with scary names". Some of the entries on the chart are especially interesting examples considering that portions of the names that are associated with significant historical or cultural events and themes. i.e. Chernobyl Packet, Demon Core. All items are described in the table below including the title text on Helvetica Scenario.
On the chart, things toward the right are scary/dangerous/very bad, while things toward the top sound scary without necessarily being scary.
Note that Randall uses similar diagrams in both 388: Fuck Grapefruit , 1501: Mysteries and 2466: In Your Classroom , which also contain different items. The first two also have an extra point, and the last two extra points mentioned in the title text. Only the first and the last comics points are also off the chart, whereas for the second the description of the point is too long to fit on the chart. Extra info outside the chart is also used in the title text of 1785: Wifi , but this is a line graph.
[A scatter-plot, with 12 labeled dots. Both axis are labeled but neither has an arrow at its end. The dots are scattered from left to right and top to bottom. Below all labels are given, first for the axis, and then for each dot in approximately normal reading order, left to right top to bottom, but in the order it would make sense to read them:] Y-axis: Scariness of name X-axis: Scariness of thing name refers to
[Top left]: Chernobyl packet [Top halfway right]: Kessler syndrome [Top three quarters towards right]: Demon core [Top right]: Flesh-eating bacteria [A third down left]: Bomb calorimeter [Halfway  down three quarters towards right]: Bird flu [Halfway  down right]: Nuclear football [Dead center]: Mustard gas [Just below and right of center]: Superbug [Bottom halfway right]: Soil liquefaction [A third up three quarters towards right ]: Criticality incident [Very bottom two-thirds to the right]: Grey goo


Snare

Explanation:
This comic paints another one of Black Hat 's evil activities as an unlikely supervillain.
As Cueball states, there have been some strange discoveries in the news including a gigantic ring strung with superstrong mesh, a long pole, and a gigantic winch . As Cueball outlines these items, Black Hat responds casually to each detail, seeming preoccupied with his computer. Cueball realizes that the pole, ring and net combination sounds like a butterfly net , albeit one of immense size. Given Black Hat's history of nefarious activities and the specific length of the pole (260 miles or 420 km, the same as the height of the International Space Station's orbit above Earth), Cueball infers and then accuses Black Hat of wanting to catch the International Space Station (ISS) by winching the pole up so that the Space Station orbit leads it to fly into the net, therefore catching it.
Black Hat does not deny the charge, but he dissimulates by saying it is not necessarily the ISS that he intends to catch, but just an international space station.  While his statement implies that it could be targeted at some other international space station, it is transparently obvious which one he is targeting since there's only one international space station in existence. [ citation needed ] Any international space station that he can catch must be the ISS. (As for non-international space stations, the only one in orbit at the time of the comic’s publication was the Chinese Tiangong-1 , which has since deorbited.)
The title text is a reference to how butterfly collections are usually presented. The insects are mounted in glass display cases, each skewered through the body with a pin, and labeled. The text is spoken by Black Hat, who again tries to imply that he is not to blame, as it may not be meant for his collection of satellites. Perhaps he is just catching a space station for a friend.
The real buildings may belong to these structures:
[Cueball is talking to Black Hat. Black Hat is using a laptop.] Cueball: They said on the news that they found a giant ring lying in a field outside Chicago. Strung with some kind of superstrong mesh. Black Hat: Mhm? Cueball: Then they found a 260 mile long shaft connected to the ring, running from Chicago to St. Louis. In St. Louis they found a gigantic winch. Black Hat: Did they. Cueball: It sounds kind of like... Cueball: ...a butterfly net. Cueball: ...are you planning on catching the International Space Station? Black Hat: I'm planning to catch an international space station. Black Hat: Not sayin' which.


Six Words

Explanation:
The six words are: "It works in Kerbal Space Program ".
The Kuiper Belt is a region of the outer Solar System beyond the orbit of Neptune consisting of numerous small icy bodies, including the dwarf planets Pluto and Eris . An Oberth maneuver is a spaceflight maneuver, specifically an engine burn performed during the flyby of a celestial body. The point of this is to optimize usable energy, because rocket burns are more effective to perform at high speeds than at low speeds. The more massive the body and the lower the altitude, the higher the flyby speed will be, and the greater the performance gain due to the Oberth effect. The theoretical way to use rocket fuel most efficiently is therefore to execute the burn during a flyby of the most massive celestial body available, as close as possible.
Cueball is proposing to implement an "Oberth Kuiper Maneuver", and the proposal diagram shows the spacecraft using gravity assists to travel first towards (presumably) Venus for a first boost, then towards Jupiter for another swing by, aiming it back towards the Sun , the most massive Solar System body, to perform an Oberth maneuver at the point of closest approach, as indicated by a small dot along the spacecraft trajectory. It is possible that the diagram might only be a simplified outline of a more complex flight plan. For example, the trajectory from Earth to Venus would require two separate burns in deep space. The first burn would occur immediately after escaping Earth's sphere of influence. The second burn would occur about halfway to Venus. Alternatively, Cueball may have gotten it wrong, or Randall may simply not have concerned himself with such things for the purpose of a webcomic sketch.
An Oberth maneuver in the close vicinity of the Sun, while theoretically possible and extraordinarily effective at the speeds the spacecraft would reach, would however be very difficult to carry out in real life, because the neighborhood of the Sun is an extremely hostile environment [ citation needed ] and the spacecraft could be incinerated during a too-close flyby.
Cueball's argument for why the maneuver will work in real life is that it works in Kerbal Space Program (KSP), a sandbox spaceflight simulator game. While KSP does simulate a lot of the physics of space flight, it is (necessarily) simplistic in its modeling of orbital dynamics. For example, KSP does not do any N-body simulations , so if one were flying a rocket from Earth to the moon, in the game the rocket would only be affected by Earth's gravity until it reaches a certain point where it will only be affected by the moon's gravity, unlike in real life where the rocket would feel the effects of both celestial bodies at all times. Therefore, orbits modeled using KSP would poorly reflect the actual orbital behavior of a probe traveling through the solar system on a multi-year mission involving multiple fly-by maneuvers.
Another reason why using KSP would not inspire confidence is that many players playing the game use a 'trial-and-error' method, field testing designs and inevitably either crashing them or running out of fuel stranding the craft in deep space. Inside a game this is not a major issue as one can simply reload an earlier save with no repurcussions, but in real life this would result in expensive costs constructing new spacecraft and even loss of human life, which NASA would likely frown on.
The humor in referencing KSP in the comic lies in using a simple game program to simulate complex space missions which in reality take a great number of experts to plan and implement. Fly-by maneuvers, used to minimize the fuel needed to reach a destination, need to be very carefully timed - often to within seconds - so the use of Kerbal Space Program to simulate them isn't a good enough argument for NASA to agree to implement the proposal, and implies simplistic thinking on the part of the proposer; therefore one should not say it at NASA.
The title text refers to Orbiter , which is another spaceflight simulator program. The title text suggests that the argument doesn't work for NASA, not because it's not scientifically sound, but because NASA relies on the Orbiter simulator rather than the Kerbal simulator (although the proposed maneuver would appear to work in both).
[Caption above the frame:] The six words you never say at NASA:
[A diagram shows a possible trajectory path for a space probe starting at Earth and involving two slingshots around two other planets, and finally the Sun. There is a title above and a label beneath the diagram. The diagram is being presented by Cueball in front of three other Cueball-like guys. Behind Cueball Ponytail appears to be taken by surprise by his six words, and holds her hand to her mouth.] Title: Proposal: Label: Oberth Kuiper Maneuver
Cueball: And besides— Cueball: It works in Kerbal Space Program.


10-Day Forecast

Explanation:
The 10-day forecast is a prediction of the weather extending 10 days into the future (with the accuracy decreasing exponentially). However, when Cueball checks the forecast for his local area, it apparently predicts progressively extreme lightning storms, a plague of insects which appear to be locusts, what appears to be The Rapture , and the appearance of a demon-like creature. Upon the arrival of the creature (or perhaps The Antichrist , Woden , or Mothra ) appearing, the forecast falls into static and nothingness with the day stuck on Tuesday, meaning that the world has ended.
When asked about this, Megan casually explains that Cueball put a minus (-) sign in front of his ZIP code. A ZIP code is a numeric postal code used in the United States, but many more countries use similar systems. As ZIP codes are tied to a geographic location, it is also often used to specify a local region for the purposes of weather reports.
Many computer systems that let the user write in a number only work with certain numbers (such as positive numbers). Numbers the system is not designed to work with, such as negative numbers, may lead to errors or unpredictable behavior (or, more often, the system will just refuse to proceed until you input a valid number). When this happens with the number of a video game level, it can result in data of another type being loaded, creating a level with a corrupted or physically-impossible landscape; this is sometimes known as a " Minus World ".
Megan states that you get this result for any negative zip code. This may be an error deliberately put in by the programmers creating the system, to freak out any people who make a mistake.
Cueball, on the other hand reacts as if this negative zip code actually represents an actual geographical location, or a real-life Minus World, and that the weather forecaster is indeed showing an accurate forecast for the (corrupted) area. Since Megan stated that the forecast is always like that for these zip code Cueball expresses that he would never move there.
In the title text, Megan agrees with Cueball's desire not to move to that ZIP code area, the punchline being that her reason isn't to avoid the apocalypse, but to retain access to Amazon Prime, which shows that her priorities are amusingly bizarre. The service Amazon Prime is provided by Amazon , where the user pays a flat annual fee and in exchange they get access a number of "enhanced" Amazon services, including free two-day shipping, free access to a library of streaming videos, and the ability to borrow books.
Later, a Five-Day Forecast was also made into a comic.
[Cueball sits behind a computer desk when Megan calls to him.] Megan (off-panel): Is it going to rain this weekend? I have a thing. Cueball: Lemme check. *type type* Cueball: ...Uhh. What?
[A caption is written above ten small panels in two rows. In each panel is an indication of the weather. Below each panel a label tells which day it is referring too.] Your 10-day forecast: [A yellow sun.] Today [Two gray clouds in front of the sun.] Tomorrow [Thunderstorms, with three gray clouds and a single lightning bolt.] Friday [Extreme thunderstorms with many large gray clouds and seven lightning bolts] Saturday [A swarm of insects, with one large black one close by and seven others close enough to discern details. The rest of the swarm is grayed out and just shown as small dots behind these other eight insects.] Sunday [Images of distorted people with very long legs. One Megan, one Cueball and someone in the background.] Monday [A humanoid figure with two large horns or a winged helmet silhouetted against a bleak red background. The ground beneath the figure is black.] Tuesday [Grey static] Tuesday [Black screen] Tuesday [Black screen] Tuesday
[Megan has entered the panel and stands behind Cueball looking at his laptop over his shoulder. She points to the screen. Cueball holds his hand to his chest.] Megan: ...Oh! You typed a minus sign in the ZIP code. The negative ZIP codes are all like that. Cueball: Let's never move there.


Pale Blue Dot

Explanation:
The Pale Blue Dot is a picture of the Earth taken in the year 1990 by the Voyager 1 space probe at a distance about 6 billion kilometers (3.7 billion miles). It was part of the Family Portrait , a series of images of the entire Solar System from beyond it.
The picture was taken at the request of Carl Sagan , a well known space scientist at that time. In 1994 Sagan wrote the book " Pale Blue Dot: A Vision of the Human Future in Space " inspired by this picture. In the book, Sagan waxed eloquent about the picture in a widely quoted passage. The complete passage can be found in Wikiquote , and you can hear Carl Sagan himself reciting it in this YouTube video .
Cueball quotes from a condensed version of this passage until he is interrupted by several Hecklers who begins  an argument over which speck in the picture is actually the Earth. Then, when Cueball cries out in exasperation that it doesn't matter, one heckler takes it the wrong way and points out that he just said that the picture doesn't matter. This pokes fun at the fact that the Pale Blue Dot picture has very little to no visual attractiveness, apart from the intellectual interest relying on the viewer's knowledge that the central speck is actually our home planet, Earth, seen from a very great distance.
The first two sentences of the title text are also a quotation from Sagan's paean to the Pale Blue Dot picture, but then the text veers humorously into non-scientific mysticism that starkly contrasts with the attitude and intent of the original work.
The title text evokes Cosmicism , a philosophy developed and exemplified by the fictional Cthulhu Mythos . This Mythos is expounded in fantasy/horror works of H.P. Lovecraft and, later, August Derleth, and features a cosmology in which humanity is depicted as inconsequential within a greater existence that is unknowable and frightening. Cosmicism asserts that humanity is doomed to death and destruction through the workings of vastly more powerful supernatural forces way beyond our understanding. There are many instances in the fiction of H.P. Lovecraft of factions that embrace the destruction of humanity and actively work towards bringing about that end through the invocation of the unknowable and powerful forces that supporters of Cosmicism believe surround everything.
The text also references Ba'al , originally a Semitic deity that has been since associated with demonic or otherwise evil forces. The name Ba'al, and other variants of the same, has been included in many other fictional works often as a villain or antagonist. For example, the fictional System Lord Ba'al from the television show Stargate . The title text supplants all of the supernatural forces associated with Cosmicism in the works of other authors with Ba'al. Cueball, who continues his discourse in the title text, may be acting as a Cosmicist and is calling on a Congress, to which he is speaking, to fund the space exploration program as a means to join with Ba'al, the Eater of Souls. The fact that a Ba'al cultist would be speaking in front of a government body in such a manner is absurd [ citation needed ] and thus hilarious.
Ba'al, the Eater of Souls (sometimes as Ba'al the soul eater) has been mentioned later in 1419: On the Phone and 1638: Backslashes .
[Cueball stands in front of a large gray picture of the Pale Blue Dot . (There is no evidence that there is any blue in this comic). He holds up a stick with one hand towards it. He is interrupted by several hecklers from off-panel.] Cueball: Consider this Pale Blue Dot. That's here. That's home. That's us. Everyone you love, every human being who ever was, every saint and sinner in the history of our species lived out their lives on this mote of dust suspended in a sunbeam. All our- Heckler 1 (off panel): I think that's a stuck pixel. We're the speck on the left. Cueball: ...Ok, this Pale Blue Dot is everything you- Heckler 2 (off panel): No, you were right before. That one is earth. Cueball: Look, it doesn't matter! Heckler 3 (off panel): I knew it! Heckler 4 (off panel): I think this is just a lens cap picture.


The Mother of All Suspicious Files

Explanation:
The save dialog box shows a download from the address http://65.222.202.53 , an IP address that hosted JavaScript malware during a recent attack on the Tor anonymity network , with a very long file title. Many of the extensions used inside there indicate executable code; multiple file extensions are sometimes used to disguise a trojan program as a document.
You can also see common download syntax for a pirated movie, Hackers , likely included to appear malicious to anyone skimming but is actually a movie about hackers, making it a benign reference rather than malicious. It is described as " _BLURAY_CAM ", which contradicts itself (" _BLURAY " would imply it was ripped from a copy on Blu-ray Disc , while " _CAM " would mean it was copied by pointing a camera at the screen in the cinema). " _BLURAY_CAM " would probably indicate a search-keyword-stuffed fake copy; fake pirated media often contain viruses (although this is more likely to be a problem with newer media, before the first real pirated copy appears).
The URL contains the path " ~tilde/pub/cia-bin/etc ". The first part is a public folder of a user named "tilde" (which is also the name for the ~ symbol ), " cgi-bin " is a common folder on a web server for server-side executables ( Randall changes the name to " cia -bin "), and " etc " is a standard folder for configuration files – normally never accessible through a web server. The program "init.dll" isn't executable at all, it's a Windows Dynamic Link Library which can't be run standalone, and is rarely referenced in URLs (even though such syntax is still being employed, even on reputable websites (Google search) or here at eBay , indicating the webserver is a Microsoft ASP server). The question mark indicates the start of a parameter list, and in this case we have only one named " FILE ".
The "Save" button is greyed out, suggesting that it is disabled; you can click only the "Cancel" button. For security reasons, some browsers (like Firefox) disable the "Save" button for a few seconds before enabling it. This prevents users from accidentally accepting a download while entering input, like a malicious CAPTCHA.
The complete content sent to the server, starting with " /~tilde... " and ending with " ...out.exe ", is exactly 256 characters long. On HTML 3 specifications you have a limitation of 1024 characters, whereas later HTML specifications don't have this limit; it just depends on the web server's capabilities. But posting parameters directly at the URL is still a worse choice.
The content of the parameter is shown here:
The title text suggests changing from http to https , as if encrypting a suspicious file before downloading it is somehow better than downloading it unencrypted. http (Hypertext Transfer Protocol) and https (Hypertext Transfer Protocol – Secure) are the two common protocols for getting web pages and web downloads. http is the simple download, whereas https adds an SSL encryption layer so the item being downloaded cannot be viewed unencrypted by anyone except the end recipient. Changing http to https is a common suggestion to improve security when browsing the web from an insecure network (such as a public WiFi hotspot) to avoid surveillance or hijacking to a malicious website; Google automatically switches to https for all mail accounts and is starting to do so with searches. The end recipient will still get whatever nasties were in the original, however — encrypting it doesn't change the content at all.
The IP address referenced in the comic, 65.222.202.53 , was, at the time this article was authored, being used by the shellcode of a JavaScript zero-day exploit for the Tor Browser Bundle being run by the FBI to phone home over the clearnet [1] and deanonymize visitors to websites on Freedom Hosting that are serving child pornography. [2]
As the last extension in the file is .exe, a Windows computer would run the file like an application. Usually, it is not safe to run unknown .exe files.
[Browser download warning box containing the following text.] WARNING! This type of file can harm your computer! Are you sure you want to download: http://65.222.202.53/~TILDE/PUB/CIA-BIN/ETC/INIT.DLL?FILE=__AUTOEXEC.BAT.MY%20OSX%20DOCUMENTS-INSTALL.EXE.RAR.INI.TAR.DOÇX.PHPHPHP.XHTML.TML.XTL.TXXT.0DAY.HACK.ERS_(1995)_BLURAY_CAM-XVID.EXE.TAR.[SCR].LISP.MSI.LNK.ZDA.GNN.WRBT.OBJ.O.H.SWF.DPKG.APP.ZIP.TAR.TAR.CO.GZ.A.OUT.EXE [Cancel and Save buttons (Save button disabled)]


Sphere

Explanation:
Megan has taken or visited an astronomy class and has become more conscious and aware about the colossal size of the universe, and our own minuscule place in it. She ponders that she can only observe and learn about the rest of the universe; she cannot explore it directly as she is trapped, probably by the constraints of our gravity well, time and human technology.
The sphere she mentions here is the Earth , whose surface is roughly spherical in shape. The figure of the Earth is an irregular shape which can be better approximated as an oblate spheroid , or more specifically as a geoid .
Her disinclination to make " small talk " with Cueball is a reference to how astronomers and people of other 'big-science' specializations can be so focused on their topic that they become disconnected from the simple details of everyday life. This has also been touched upon in 663: Sagan-Man and 786: Exoplanets .
The concept of "small talk", which is usually used as a colloquial term meaning insignificant chatter with others, is taken quite literally by Megan to be small in size. The word itself is juxtaposed with the size of the universe shortly after, which also ties into her previous sentence of being trapped on a "sphere". It seems that astronomy, which deals with ideas of a vastly large scale, has expanded Megan's views to the point where she feels insignificant herself, as well as other matters that concern her. Her gaze outwards also reinforces this suggestion, especially during her conversation with Cueball. She does not engage in eye-to-eye contact, instead replying without looking directly at him. This implies that she is disregarding the current conversation as insignificant as well, which furthers the assumption of Megan's expanded scope of viewpoint.
The title text is a continuation of this theme. The name "Society of Astronomers Trapped on the Surface of a Sphere" or, "SATSS", follows a common naming practice for scientific communities, Society, or Association, or Union of <Scientists> of <Country, Nationality, or What Ever>.
Cueball: How are you? Megan: Trapped on the surface of a sphere. [A beat.] Cueball: That astronomy class has made you suck at small talk. Megan: The universe is too big for small talk.


Meteor Showers

Explanation:
This comic spoofs the way that astronomical events are often reported in the mass media — events are often tagged with undeserved superlatives or described as being more dramatic than they actually are. In some cases, outright misinformation is spread. This phenomenon occurs in part by the result of over-eager scientists, but mostly because of journalists with no deeper knowledge on the subject they write about.
Meteor showers typically occur regularly each year. It always happens at the same days because the Earth is crossing the dust path of a particular comet . Sometimes meteor showers are in fact likely to be relatively spectacular when the peak of the shower occurs while your part of the world is in darkness and there is little moonlight. However, even in these cases it must be understood that there is nothing unusual about the meteor shower itself. The shower consists of small particles about one millimeter in diameter. Only their high speed lets them produce enough light to be visible from Earth's surface. The names of the showers refer to the constellation from which they appear to radiate.
Most of the meteor showers listed in the comic are real, but some are made up (and indicated as such below).
While keeping pets inside may be reasonable on days when fireworks are let off in the beginning of a new year, no regular meteor shower poses much danger to pets.
Apparently a play on the tricuspid valve in mammalian hearts, or possibly on bicuspid teeth. The mention of "Region 2" is a reference to region locking , a digital rights management (DRM) scheme intended to restrict media to certain areas. [ citation needed ] DRM of course does not apply to natural events.  However, meteor showers are also geographically restricted, and the visible area might roughly coincide with a DRM region (Though Region 2 covers a large and scattered area, not being strictly geographical).
Since indoor lights and window glass make them harder to see, it would take a very bright meteor (like the Chelyabids two entries below) to be visible without going outside.
This fictional shower would collect shooting stars into the origin to prepare for the real Eta Aquariids meteor shower associated with Halley's comet and diverging from Eta Aquarii in Aquarius; the real shower peaks around May 6th. Due to perspective, meteor showers appear to radiate outwards from a certain point in the sky. Meteor showers may be seen to converge on a point on the opposite side of the sky, but with the earth in the way there would only be a few visible going past the edge, seen as nearly parallel streaks overhead, so the convergence point would hardly be notable.
A reference to the February 15, 2013, Chelyabinsk meteor whose explosion shattered windows within a large radius.
A meteor large enough to reach the lower atmosphere could produce sound audible to observers on the ground, but this is very unusual.
This shower is mostly observed via its effects on radio and TV signals, and therefore a good target for conspiracy theorists responding to June's Invisible Meteors - NASA Science .
The "50/50 mix of meteors and shooting stars" is a joke, as "meteor" and "shooting star" are synonymous.
This is saying that they are indistinguishable from stars, or that the stars themselves are actually meteors.
Dromaeosaurids are a family of dinosaurs containing the genus Velociraptor , well-known from the movie Jurassic Park in which they are presented as a deadly menace, fast and especially intelligent to the point of understanding how to open a door; this representation of Velociraptors is a recurrent topic in xkcd .
Erupting from the ground is the funny inverse of falling from the sky, what meteors always do.
Probably a reference to Pyramidal cells , a type of neuron. The "tau" reference has two possibilities. The "visible even when eyes are closed" could refer to the Tau particle, a heavy sibling of the electron. When they traveled outside of Earth's magnetosphere on their way to the Moon, Apollo astronauts saw flashes of light about every three minutes even with their eyes closed; these were caused by high energy particles (cosmic rays) penetrating their eyes and brain. The other possibility is that it refers to Tau protein , a normal structural protein within brain neurons. In Alzheimer's Disease, abnormal Tau proteins can aggregate within pyramidal cells to form insoluble skeins. The number of these " neurofibrillary tangles " roughly correlate with the severity of cognitive impairment.
This may have something to do with the fact that "draconids" etymologically means "of the dragon", which could make for a fearsome meteor shower. And if you run it will track you down, albeit slowly. This may also be a reference to Boo , a character in the Mario series of video games that is slow but follows you if you turn your back on them. In the game Terraria, meteors (or rather, "meteor heads") follow this exact behavior.
Rather than taking place over the course of a week, all the meteors in the shower happen at the same time. This would involve about 3000 meteors appearing simultaneously, which would be quite an impressive sight.
There was a very active Leonid shower (a "meteor storm") in 1966, and a precursor to it in 1965. The article Is God Dead? was published in Time Magazine on April 8 of 1966. Perhaps this suggests that the meteors killed God earlier in the year when they and He were further out in the solar system?
Meteors usually don't reach the surface of the Earth, being destroyed in the atmosphere. If they do approach the surface, deflecting them with tennis racquets would probably not be the most effective strategy [ citation needed ] , unless Randall is implying that the Geminid swarm is composed of tennis balls.
The title text refers to the folk wisdom that lightning strikes the tallest thing around, but this has never been applied to meteors, where it is basically the size (area) that determines the likelihood of an impact with a given object. Randall expressed frustration over how "maddeningly inexact" the lightning statement is, and elaborated on the problem mathematically, in the what if? Today's topic: Lightning .
[A list of 16 meteor showers, with a caption above, labels on the three columns and then every other row in gray, beginning with a gray row beneath the line below the column labels.]
The xkcd guide to meteor showers Name Peak Notes Quadrantids January 4 th Bring pets inside during peak activity Tricuspids January 21 st Not viewable in region 2 countries Centaurids February 6 th Too faint to see without going outside Beta Aquariids February 10 th Inverted shower converges toward Aquarius instead of radiating away Chelyabids February 15 th Only one meteor per shower, but it's big. Lyrids April 22 nd Meteors sometimes scream Daytime Zeta Perseids June 9 th Likely a NASA hoax June Boötids June 27 th 50/50 mix of meteors and shooting stars Southern Delta Aquariids July 19 th Meteors very bright, but stationary Dromaeosaurids July 22 nd Fast, highly intelligent, can open doors Perseids August 12 th Instead of falling from sky, meteors erupt from ground Tau Pyramids August 15 th Visible even when eyes are closed Draconids October 8 th Very slow, but follow you if you run Orionids October 21 st Entire shower happens at once Leonids November 17 th In 1966, unusually active Leonid shower killed God Geminids December 13 th Can be deflected with tennis rackets


Old Accounts

Explanation:
Cueball is very dramatically following the described process of removing himself from a social network by first unfriending each contact in reverse order that he friended them. Such actions are not necessary on any well-designed website. Actively unfriending people individually could be perceived as rude, antisocial, or in need of help.  On the other hand, if a user simply abandons his or her account without cleaning it up, then even years later, it will still be sitting there, gathering friends' statuses, opinions and comments.
The reverse order to unfriend people refers to practice of correct resource management in computer programming.  Computer programs typically require access to many resources at a time, and some of those resources may only be available insofar as the program has access to other more basic resources.
For example, if you wanted to watch a movie from a rental service, you would first acquire a keep case with a disk inside of it, and then you would remove the DVD from the case in order to play it on a TV.  Once you had watched the movie, you would put the DVD back inside the case.  Then you would return the case to the store.  The process for "releasing" these two resources (the DVD and the keep case) follows the reverse order of how they were obtained: the case was retrieved from the store before the disk was removed, but the disk must be put back before you return the case.
A computer program must release resources in a valid order, though it is often difficult for programmers to ensure this, due to the many paths of execution a program can follow.  If resources are released in the wrong order, then a newer resource may reference an older resource that has already been destroyed, and when attempting to use the remaining resource, a variety of bad things could happen if the program attempted to access the already lost resource.
While resources do not always need to be released in exactly the reverse order of how they were obtained, doing so ensures that, as each resource is released, none of the resources that existed when it was acquired (and thus which it could be dependent upon) will have been released yet.
In the case of unfriending users on a social networking site, it is imagined that Cueball or any other user could have made newer friends through older friends, and as such, that the newer friend should not exist without the older friend and must therefore be released first.
The title text appears to be referencing related issue affecting databases used on websites such as social networking sites. When an account is deactivated, the database entries for users that were friends with the account may maintain a link to it.  This would result in the database storing useless data, so a well-designed database might try to mitigate this.  A well-written program accessing the database would be able to recognize that this data should be ignored.  Since no user account would be directly dependent on the existence of another account, the accounts can safely be deleted without worrying about resource management as described earlier.
Ultimately, the inefficiency of a database containing useless data about deleted accounts is negligible, and in fact it may not even be worthwhile to take the time to update all the entries compared to how little time it would save when performing lookups. "Database linkage accumulation slowdown" really is a thing that Randall just made up. This may be a satire of popular fears of made-up technological problems, often held by those who are not technologically savvy.
[Caption above the frame:] The internet is filled with derelict accounts aggregating news about friends long forgotten.
[Cueball sits at a desk, typing on a laptop.] Cueball: *Click* Computer (friend): Uhh, is everything OK? Cueball: *Click* Computer (another friend): Dude, what the hell? Cueball: *Click*
[Caption below the frame:] When you find yourself drifting away from a community, remember to clean up after yourself by slowly unfriending everyone, one by one, in the reverse order that you added them.


Anti-Glass

Explanation:
Black Hat makes an attachment for eyeglasses which shines a laser light at people using Google Glass . The quote "The best defense is an indiscriminate offense" plays off the adage " The best defense is a good offense ". Black Hat's goal seems to be to interfere with the Google Glass user potentially recording the person with the laser, and possibly blinding Google Glass users, undermining the project. By mailing one to the children of every Google executive, who are likely to be Google Glass users, he's clearly aiming to disrupt the entire Google Glass project. "Silicon Valley" is a term for where many technologically up-to-date people live who are more likely to work in the computer industry and use Google Glass.
The "viral marketing campaign" excuse seems to play off how battery-powered LED placards were mistaken for terrorism in the 2007 Boston bomb scare . He pretends that his terrorism is actually a viral marketing campaign, but seems to have not thought this excuse through. He then tries to get them to look into a laser light.
The title text shows the irony between Black Hat's needlessly complicated technical solution, and his apparent hate of Google Glass, a relatively new technology. In addition, he remarks that he wouldn't do something as old-fashioned as shining a laser in peoples' eyes, as this does not live up to his technical expertise.
However, he could shine a laser through the peephole, which would have the same effect on the police officers.
It seems generally that Randall is no fan of Google Glass, which was also shown later in 1304: Glass Trolling . It was the second time they are mentioned in xkcd after 1215: Insight , but this was the first direct mocking of people wearing these glasses. Google Glass has become a recurring theme in xkcd.
[Two police officers stand outside an apartment door. The male officer is bald (and half cut of by the left frame of this thin panel), and the other is Ponytail, both are wearing peaked caps with white emblem. Ponytail is holding a pair of glasses down in one hand. The glasses have a small white box with a smaller tip in the front attached to one of the frames. A person (turns out to be Black Hat) answers through the door which has a peephole.] Ponytail: Police. Open up. Ponytail: Did you make this glasses attachment? Black Hat (off-panel through door): Oh, yeah.
[Black Hat is sitting in an office chair at his laptop with his back to the door. The door is not visible but the officers voices come through it off-panel from the left.] Ponytail (off-panel): What's it do? Black Hat: It detects when someone near you is wearing Google Glass and shines a laser pointer at their eyepiece. Ponytail (off-panel): Why?? Black Hat: The best defense is an indiscriminate offense.
[Cut back a frame-less panel with a wider view of the two officers outside the apartment so the male officer is not cut off.] Male officer: It seems you've mailed these devices to people across Silicon Valley, including the children of every Google executive. Black Hat (off-panel through door): Yeah. It's a viral marketing campaign for an upcoming movie.
[Same scene but with frame around the panel.] Male officer: What movie? Black Hat: Haven't decided yet. Anything good coming out this fall? Male officer: Sir, open the door. Black Hat: First stare at the peephole for a sec.


Increased Risk

Explanation:
The panel satirises the common misunderstanding of the concept of percentage. Quoting a percentage change without mentioning the base probability that this ratio acts on is meaningless (outside of arithmetic for arithmetic's sake). Most everyday communication, however, succumbs to such incompleteness. In the aftermath of this ambiguity, people tend to conflate relative and absolute changes.
If the probability of a shark attack at the North beach is 5 per million, then the probability of shark attack at the South beach is still not more than 6 per million. The difference between these values is not enough to normally justify choosing one beach over the other, even though a "20% greater" chance sounds significant when stated out of this larger context.
Cueball parodies the concern by noting that by going to a beach three times instead of two, their chances of attack by dogs with handguns in their mouths (a ludicrous and unrealistic scenario as dogs cannot buy guns [ citation needed ] and are not likely to pick one up off the ground) increases by 50%. If the chance of the dog attack is one per billion on each visit to the beach, then the chance of attack increases over multiple visits; regardless it's still one in a billion for any specific visit. This does not change the overall improbability of there ever being a dog swimming with a gun in its mouth.
Beret Guy misunderstands Cueball's probability, exhibiting the gambler's fallacy by believing that since they haven't been attacked in their first two trips, the chance of attack by dogs with handguns is higher on this outing.
This is a common misunderstanding of statistics. While the overall probability of an attack in three trips would be higher than in a single trip, it doesn't change the fact that in each individual trip, the probability is still the same; whether or not they managed to avoid being attacked in their first two trips, the results of these trips do not factor into the probability equation of the third trip.
This also can be illustrated by coin flips: if one flips a "fair" coin ten times in a row, no matter what the result of each previous flip is (even if it were nine heads in a row), the odds of getting heads on the tenth coin flip theoretically remains 50%. In other words, past experience does not impact subsequent flips.  In practice, if the odds on each flip were 50%, then the odds of nine heads in a row would be 0.2%, so after it might be worth considering the possibility that the coin has been bent or weighted to alter the odds, or even a counterfeit with "heads" on both sides.
The caption clarifies Cueball's point, but without sarcasm.
Then again, the title text objects to this point (that a tiny risk increased by 50% is still tiny). If this 50% increment is done repeatedly, the risk can get arbitrarily high, while the statement says that it is still tiny. This can be compared to the Sorites paradox (the "paradox of the heap"), which involves a "heap" of sand from which grains of sand are removed individually. If one assumes that, after removing a single grain, a heap of sand is still considered a heap of sand, and that there are a limited number of grains of sand in the heap, then one is forced to accept the conclusion that it can still be considered a heap of sand even if there is only a single grain of sand (or even none at all).
Being shot by a swimming dog with a handgun in its mouth is also specifically referenced in what if? 146, Stop Jupiter .
[Cueball, Ponytail, and Beret Guy are standing around. Cueball and Ponytail have beach towels. Ponytail is looking at her cell phone. Beret Guy has his hands up to his face, looking distressed.] Ponytail: We should go to the north beach. Someone said the south beach has a 20% higher risk of shark attacks. Cueball: Yeah, but statistically, taking three beach trips instead of two increases our odds of getting shot by a swimming dog carrying a handgun in its mouth by 50%! Beret Guy: Oh no! This is our third trip!
[Caption below the panel:] Reminder: A 50% increase in a tiny risk is still tiny .


Exoplanet Names

Explanation:
On the 14th August 2013, the International Astronomical Union (IAU) issued a document about public naming of astronomical objects. It stated, "IAU fully supports the involvement of the general public, whether directly or through an independent organized vote, in the naming of planetary satellites, newly discovered planets, and their host stars."
The text above the image states the fact above and then notes that the IAU immediately regret this decision. As we can see from Cueball's question, from Ponytail's facepalm, and the fact that even Megan is speechless, the suggestions are appalling. It becomes even worse when Hairbun tells them that an automatic filter has already been applied to the results, one designed to remove inappropriate entries that don't meet certain criteria. This implies that the list would have been even worse if presented in its unfiltered form (as seen below in the table).
The naming document also contained, amongst other things, guidelines that suggested names should meet. These include stipulations such as "16 characters or less", "preferably one word", being "pronounceable (in as many languages as possible)", "not too similar to an existing name of an astronomical object", avoiding commercial names, and being "respectful of intellectual property". If we go down the list, we can see that many of Randall's suggestions do indeed violate the guidelines. Which is part of the joke as it reflects the tendency of internet submissions to ignore such softly suggested guidelines.
The randomness and inappropriateness of the suggested names reflects the commonly expected response from anonymous submitters on the internet. Many forums and contests that call for online response and do not apply strict control over the responses receive similar collections of random, inappropriate and obscure submissions that are often only tangentially related to the original subject. For example, Greenpeace held a naming contest for one of the whales recently tagged in their research and preservation campaign and even after selecting the finalists the online voting resulted in naming the whale "Mr. Splashypants". PepsiCo had even less restrictive controls in their marketing campaign that asked the internet to name a new flavour of Mountain Dew. They had to shut down the contest in order to avoid naming the new beverage "Hitler did nothing wrong" which was the current leader at the time and only marginally the most inappropriate of the top ten voted suggestions. Even more recently is the case of Boaty McBoatface , in which the internet decided to dub a British research vessel "Boaty McBoatface". The boat was given the name RRS Sir David Attenborough in the end, with its Autonomous Underwater Vehicle being called "Boaty McBoatface."
The document also states that naming suggestions may be sent to the email that Randall included in the title text.
This comic was updated in 1555: Exoplanet Names 2 .
[Text above the first frame of the comic:] August 2013: The International Astronomical Union decides to start naming exoplanets, and—for the first time ever—asks for suggestions from the general public. They immediately regret this decision. [Ponytail is facepalming while Megan and Cueball are looking at a computer screen on a desk. Hairbun points to the screen.] Cueball: Can't you filter out the worst ones? Hairbun: This is after the filter!
[Below is a table showing the list of planet names as seen on the computer screen with gray background around the edges of the table.]
[The table is in two separate columns, but there is only headings over the left, so the right column is a direct continuation of the left. In the table it is mentioned when the right column begins. There is a small arrow pointing from the word "Planet" down to the second column of the table. The headings in the comic are not inside the table as they are here below. The text at the bottom of the left list seems to continue on below, at least the last entry is cut below the middle, although it is still easy to read. Similarly the text at the top right list, seems to continue from above, the top entry missing the very top of the text. This is as if the list is much longer and here is just shown part of the list. To further indicate this the first entry in the right list begins at "c" instead of at "b" which is else the case for all other instances.]
Star Planet Suggested Name Gliese 667 b Space Planet c PILF d A Star e e'); DROP TABLE PLANETS;-- f Blogosphere g Blogodrome h Earth Tau Ceti b Sid Meier's Tau Ceti B c Giant Dog Planet d Tiny Dog Planet e Phil Plainet f Unicode Snowman Gliese 832 b Asshole Jupiter Gliese 581 b Waist-deep Cats c Planet #14 d Ballderaan e Eternia Prime f Taupe Mars g Jelly-Filled Planet Epsilon Eridani b Skydot c Laser Noises Gliese 176 b Pandora c Pantera Kepler-61 b GoldenPalace.com [Below is the right column.] Upsilon Andromidae c Stampy d Moonchild e Ham Sphere HD 20794 b Cosmic Sands c Legoland d Planet with Arms HD 85512 b Lax Morality HD 40307 b Good Planet c Problemland d Slickle e Spare Parts f New Jersey VI g How Do I Join the IAU Gliese 163 b Neil Tyson's Mustache c [email protected] d Hair-Covered Planet Pi Mensae b Moon Holder HD 189733 b Permadeath Kepler-22 b Blue Ivy Kepler-3284 b Blainsley Kepler-3255 b Unicorn Thresher Kepler-2418 b Spherical Discworld Kepler-1686 b Emergency Backup Earth Kepler-3010 b Feeeoooooooop Kepler-442 b Liz


Preferred Chat System

Explanation:
As more options become available for communication, it becomes more difficult to determine the social etiquette of communicating with others. It is customary (or at least rarely incorrect) to return a communication from someone using the same medium as the initial contact. For example, a voicemail is generally returned with a phone call (perhaps resulting in another voicemail), and an email with an email, etc. However, sometimes people respond through a different channel, such as texting a response to a voicemail or emailing a reply to a text. This can create confusion that Randall is pointing out, because the recipient may be unsure whether to go back to their original communication method, or if the response was a signal that the recipient prefers the new method. Similarly, it becomes important for people to know what type of communication is preferred by a recipient, or most likely to reach the recipient quickly and generate the most useful response.
Randall portrays the difficulty Cueball is facing when communicating with a seemingly irrational recipient. Today's multitude of social networks and communication systems amplifies the problem. After several misses, Cueball is leaving a voicemail for his intended recipient to clarify the best way to reach them. He initially tried texting the recipient, to which they made one reply on the instant-messaging service Google Talk (commonly called GChat). This is unusual because instant messaging services are usually used to engage in longer conversations than one message. Cueball further is confused because the recipient, although silent on Google Talk, continues responding on IRC . Cueball then attempted to communicate by email, but the response came on Skype , another instant messaging service that features voice and video chat along with text. The recipient mentions that the email " woke [them] up ", implying that they have e-mail configured to make an audible alert, possibly by being forwarded to a cell phone.
Cueball clarifies that he appreciates that the recipient is very quick to respond, but his confusion stems from his inability to determine the proper medium to use. As he finishes his voicemail, an owl flies towards him carrying a written message. This appears to be a reference to owl post , which is a form of communication in the Harry Potter lore which itself is presumably based on the real-world usage of carrier pigeons . The owl post message indicates that the voicemail was received, and suggests using Google Voice next time, which is yet another form of voice and text communication, one that bypasses the standard telecom companies and gives the user a range of controls such as which device is called depending on who is calling or what time of day it is, or to simply ignore the call altogether.
Randall seems to have an interest in bird-related communications; RFC 1149 - IP over Avian Carriers has been mentioned in previous comics.
The title text mentions a pager , a low-tech, low-cost wireless telecommunications device that beeps or vibrates when it receives a message. Simpler pagers can display numbers, usually the caller's phone number plus a couple of additional digits, while more sophisticated ones can receives text messages. The usual intent of a pager is for the recipient to call the number back or, today, to tell you that your table is ready. Pager use peaked in the 1980s and 1990s, but declined thereafter as cellular phones became ubiquitous. There can be absolutely no need for this hyper-connected individual to use a pager, and having your own cellphone forward messages to your pager makes almost no sense. The question in the beginning of the owl-message further suggests, that the reciever did not actually recieve the voicemail, but just had Cueball's phone number displayed on his pager.
A possible suggestion is that they are intentionally using such an abundance of communications options to, perversely, make it harder to have a conversation with them. So far, it seems to be working. If this is true, the person Cueball is trying to contact may very well be Black Hat.
Another suggestion is that Cueball is attempting to contact Beret Guy, as Beret Guy is known for doing odd things such as this.
This comic is closely related to a later comic, 1789: Phone Numbers .
[Cueball stands, talking on his cell phone.] Cueball: Sorry for the voicemail, but I'm confused about how to reach you. Cueball: When I text you, you reply once on GChat, then go quiet, yet answer IRC right away. I emailed you, and you replied on Skype and mentioned that the email "woke you up". Cueball: You're very responsive - I just have no sense of how you use technology. [An owl flies into the panel.] Cueball: ?!? [The owl perches on Cueballs's head. It has delivered a note to Cueball.] Note: did you try to call me? use my google voice number next time.


Columbus

Explanation:
The comic starts with White Hat telling the two children shown on the first panel that Christopher Columbus knew the world was round, but that others believed it to be flat. However, this is a false narrative known as the Myth of the Flat Earth . Educated people in Columbus's time knew the world was round, and knew the approximate radius of the Earth. Columbus claimed that the distance to sail west from Canary Islands to Japan to be about 3,700 km, drastically lower than others believed, but he was wrong about this . If another continent and the " West Indies " had not been fortuitously in the right place, Columbus and his crew probably would have died at sea.
As White Hat begins his explanation, Megan objects, though not explaining why. White Hat continues, so Megan interrupts, saying that Columbus went in a straight line as the world curved away, ending up in Valinor and the Undying Lands . Megan's story is an allusion to The Silmarillion , by J. R. R. Tolkien , set in the same world as The Lord of the Rings and The Hobbit . The claim that Columbus sailed on a tangent to the surface alludes to how the elves' ships leave the curved sea surface and sail in a straight line to reach Valinor on the same route that they sailed when the world was still flat. The mentions of a silmaril and the morning star are a reference to Eärendil the Mariner , the only mortal sailor to reach the Undying Lands, with one of the Silmarils (though Eärendil's journey occurred at the end of the First Age and the world was only changed into a sphere near the end of the Second Age). Megan humorously conflates these myths, suggesting that they are all equally false. Columbus in fact wasn't the first to claim the world was round; the ancient Greeks had discovered it long before. It was, however, disputed by some Christian scholars in late antiquity due to disagreements over its congruence with biblical canon. In Megan's telling, Columbus ends up as the morning star, which is actually the planet Venus (the same fate as Eärendil's in Tolkien's mythology).
The joke is that when White Hat tells her to stop making up the story, Megan pointedly replies "You first", indicating that she originally complained about White Hat's retelling of the Columbus story because his account didn't really happen, and so he was also "making things up". Megan's fantasy tale was then delivered to make a point.
The title text refers to the transfer of smallpox to the Americas by Europeans, which caused the deaths of untold millions of Native Americans. The introduction of smallpox to the Undying Lands would indeed make their name ironic.  However, the Undying Lands are named after immortal Valar , Maiar , and Elves living there, not because they confer immortality.  A more proper name would be the Lands of the Undying, and Valar, Maiar, and Elves are not susceptible to diseases in Tolkien's mythos in any case.
Similar discussions between White Hat and Megan can be found in 1605: DNA and 1731: Wrong , in the latter Megan even finishes with a similar *sigh* as she started with here.
[White Hat talks to two children sitting in front of him on the floor to the right. A boy with hair like Hairy with his arms round his knees and behind him Science Girl with two hair buns, sitting cross leged on her knees. Megan interrupts him from off-panel right.] White Hat: Everyone said the world was flat, but Columbus knew it was round. Megan (off-panel): *Sigh* no, no, no.
[Megan walks in holding a hand palm up. White Hat partly lifts his arm closest to her. The children between them turn their heads towards her. The boy leans back on one hand.] Megan: So he took his ships and sailed west— Megan: —in a line tangent to the surface. The sea fell away, and he landed in Valinor.
[White Hat has taken his arm down, Megan holds her arms out to each side. The children still looks at her, now also Science Girl leans back on one arm.] Megan: A Silmaril on his brow, he wanders the heavens as the morning star, still believing he reached India. White Hat: Stop making stuff up. Megan: You first.


Questions

Explanation:
Google , a rather popular [ citation needed ] internet search engine, has a feature known as autocomplete that guesses at search queries before they are fully typed out. These guesses are generally made based on popular searches by other people. From time to time, a particularly strange or hilarious one may be found, as is evidenced in this comic.
The largest pictured questions are: "Why are there slaves in the bible" and "Why are there ants in my laptop".
All of the questions in the comic are "why" questions, so many of them are predicated on false assumptions, such as "Why are there pyramids on the moon". Originally, all these questions and many more (33,171 in total) could be found at http://xkcd.com/why.txt . ( Archived Version )
Regarding the title text: in the Peter Jackson films of The Lord of the Rings trilogy , Arwen becomes sickly for unspecified reasons as the plot advances, apparently giving Aragorn a more personal reason to fight. The only explanation given is by Elrond, who says "As Sauron's power grows, her [Arwen's] strength wanes." This subplot is entirely absent from the original novels .
The tables below have been created so as to split the comic into almost entirely arbitrary blocks, which have then been identified with similarly arbitrary numbers. As a general rule, section numbers work top to bottom, then right to left.
http://www.reddit.com/r/xkcd/comments/1l3na7/questions/cbvigrd , answers to all the questions.
[This strip is a rectangular word cloud, titled 'Questions found in Google autocomplete'. Embedded in the cloud are 5 single panels, with illustrated questions. These are described at the end. Questions are given in roughly columnar order. None of the questions have question marks.]
Questions found in Google Autocomplete
Why do whales jump Why are witches green Why are there mirrors above beds Why do I say uh Why is sea salt better Why are there trees in the middle of fields Why is there not a Pokemon MMO Why is there laughing in TV shows Why are there doors on the freeway Why are there so many svchost.exe running Why aren't there any countries in antarctica Why are there scary sounds in Minecraft Why is there kicking in my stomach Why are there two slashes after HTTP Why are there celebrities Why do snakes exist Why do oysters have pearls Why are ducks called ducks Why do they call it the clap Why are Kyle and Cartman friends Why is there an arraow on Aang's head Why are text messages blue Why are there mustaches on clothes Why are there mustaches on cars Why are there mustaches everywhere Why are there so many birds in Ohio Why is there so much rain in Ohio Why is Ohio weather so weird Why are there male and female bikes Why are there bridesmaids Why do dying people reach up Why aren't there varicose arteries Why are old Klingons different Why is programming so hard Why is there a 0 ohm resistor Why do Americans hate soccer Why do rhymes sound good Why do trees die Why is there no sound on CNN Why aren't Pokemon real Why aren't bullets sharp Why do dreams seem so real Why aren't there dinosaur ghosts Why do iguanas die Why do testicles move Why are there psychics Why are hats so expensive Why is there caffeine in my shampoo Why do your boobs hurt Why aren't economists rich Why do Americans call it soccer Why are my ears ringing Why are there so many Avengers Why are the Avengers fighting the X men Why is Wolverine not in the Avengers Why are there ants in my laptop Why is Earth tilted Why is space black Why is outer space so cold Why are there pyramids on the moon Why is NASA shutting down Why is there Hell if God forgives Why are there tiny spiders in my house Why do spiders come inside Why are there huge spiders in my house Why are there lots of spiders in my house Why are there spiders in my room Why are there so many spiders in my room Why do spider bites itch Why is dying so scary Why is there no GPS in laptops Why do knees click Why aren't there E grades Why is isolation bad Why do boys like me Why don't boys like me Why is there always a Java update Why are there red dots on my thighs Why is lying good Why is GPS free Why are trees tall Why are there slaves in the Bible Why do twins have different fingerprints Why are Americans afraid of dragons Why is there lava Why are there swarms of gnats Why is there phlegm Why are there so many crows in Rochester, MN Why is psychic weak to bug Why do children get cancer Why is Poseidon angry with Odysseus Why is there ice in space Why are there female Mr Mimes Why is there an owl in my backyard Why is there an owl outside my window Why is there an owl on the dollar bill Why do owls attack people Why are AK47s so expensive Why are there helicopters circling my house Why are there gods Why are there two Spocks Why is Mt Vesuvius there Why do they say T minus Why are there obelisks Why are wrestlers always wet Why are oceans becoming more acidic Why is Arwen dying Why aren't my quail laying eggs Why aren't my quail eggs hatching Why aren't there any foreign military bases in America Why is life so boring Why are my boobs itchy Why are cigarettes legal Why are there ducks in my pool Why is Jesus white Why is there liquid in my ear Why do Q tips feel good Why do good people die Why are ultrasounds important Why are ultrasound machines expensive Why is stealing wrong Why is YKK on all zippers Why is HTTPS crossed out in red Why is there a line through HTTPS Why is there a red line through HTTPS on Facebook Why is HTTPS important Why are there weeks Why do I feel dizzy Why are dogs afraid of fireworks Why is there no king in England
[We see Cueball from the torso up, with arms outstretched.] Cueball: Why aren't my arms growing
[Megan stands with a grey ghost on either side of her.] Megan: Why are there ghosts
[Beret Guy stands, looking at a squirrel.] Beret Guy: Why are there squirrels
[Cueball stands.] Cueball: Why is sex so important.
[We see Ponytail from the torso up.] Ponytail: Why aren't there guns in Harry Potter


Monster

Explanation:
In this comic, officials and police are evidently trying to describe the extraordinary qualities of a huge monster by comparing it with everyday objects instead of numbers, which seems to be a recurring theme on xkcd (see 526: Converting to Metric , 1047: Approximations ) and also in the Blag article Dictionary of Numbers where Randall says that he doesn't "like large numbers without context."
This comic pokes fun at how common it is in the media to compare things of extraordinary qualities to a certain narrow set of well-known objects. The comic features people discussing a fictional monster which - apparently - can be only described by these overused comparisons. The three used by Megan , Cueball and Ponytail are:
The caption below the panel names the monster the Frequently-Made Comparisons Monster , joking that the monster was created by comparing it to things, and continues the joke by comparing the number of killed people to those that could fill a (sports) stadium (of the order tens of thousands), and the area of devastation to the smallest state in the US Rhode Island (1,214 sq mi/3,140 km 2 ) (a state Randall also used for comparison in the What if? Everybody Jump . In another What if? he uses a football stadium filled with ants as a comparison: Lethal Neutrinos .)
The title text takes the joke one step further by comparing the nuclear bomb used to destroy the monster to the bomb dropped on Hiroshima at the end of the Second World War, i.e. they dropped a relatively small nuclear bomb on it (nuclear weapons have advanced significantly since WWII). Here is an example from Wikipedia of such a comparison with the strength of a meteor strike.
[Four people are standing around a table-top crisis planning model. Cueball and Ponytail are wearing police-style hats; Megan holds a clipboard and Blondie has her hands on the table.] Megan: It's as long as a football field. Runs as fast as a cheetah. Cueball: Weighs as much as a blue whale. Blondie: Can we negotiate with it? Ponytail: No. It has the intelligence of a two-year-old child.
[Caption below the panel:] By the time the Frequently-Made Comparisons Monster was finally defeated, it had eaten enough people to fill a stadium and devastated an area the size of Rhode Island.


First

Explanation:
Firstposting , or thread sniping , is the habit of posting short messages to obnoxiously point out that you have found and seen the content first. This practice was far more common in the years leading up to this comic, when high-traffic and poorly-moderated social media sites tended to display comments in increasing chronological order by default; as such, the oldest comments would be most prominently displayed at the top, while the newest comments would be buried at the bottom.
In the first two panels, Cueball stares at his screen, implying that a long time passes before he finally points this out. He has probably submitted a post and is awaiting for comments that are not coming. Cueball might actually have mixed feelings about the practice slowly dying out. However, someone offscreen is worried he will jinx it, encouraging more people to do so.
In reality, Cueball's observation has held true, due to changes in best practices for web design. Social media sites in particular often sort comments by user rating; as such, the most appreciated comments are given the most prominence, and trollish comments like the cliche "F1rst p0st!!" are buried. Meanwhile, low-traffic forums with smaller communities still display comments from oldest to newest; in these environments, firstposters are reported and dealt with by human moderators in a timely fashion. In short, the internet as a whole does not reward or reinforce firstposting the way it once did pre-2013. However, the small children who think that posting "FIRST!!!" makes them somehow relevant or funny still remain. Only growing up and realising how unnecessary and obnoxious posting "first" is will stop them.
See also 269: TCMP and 1019: First Post .
The title text sarcastically states that no new annoying internet behaviors have emerged since the "first post" trend began which would continue to annoy users: a fact which is clearly wrong to anyone who spends a length of time on the internet. See for instance 493: Actuarial .
[Cueball sits at his desk, using a computer.]
[Cueball is still sitting at the desk, but with hands off the keyboard in his lap.]
[Cueball is in the same position as before, talking with off-panel.] Cueball: After a couple of unbearable decades, the "first post" thing seems to be dying a quiet death. Off-screen: Shh. You'll jinx it.


Bee Orchid

Explanation:
Megan is explaining the evolutionary phenomenon of mimicry of female insects which fools male insects into trying to mate with the flower ( pseudocopulation ). This causes the pollen of the flower to stick to the male bee, who may make the same mistake with another flower, allowing for pollination.
This particular orchid mimicked the solitary bee Eucera , which now only pollinates it in the Mediterranean (the bee isn't really extinct yet). This may eventually lead to the extinction of the orchid due to lack of reproduction. In most areas where it grows, the orchid is using a method of self-pollination , which can be detrimental to the genetic vitality of the species as it is a form of in-breeding.
Photographs of Ophrys apifera :

Female Eucera (Synhaolonia) guarding nests (left) and male Eucera (right):

In a similar way, some plants depend on animal species now extinct, but as the dependency was not about pollination but about spreading seeds across the land, those plant species can still last millions of years after the animal species extinction. For instance, it’s the case of the avocado .
The comic plays on the subject of levels of indirectness of memory or knowledge representation. The female bee is extinct, remembered only by the male bee's perception of her; the male bee is also extinct, but its memory of the female is preserved in the orchid's shape; the orchid, due to self-pollination, is nearing extinction, but the memory of the female bee is now preserved by Beret Guy's memory of the orchid, remembering the male bee's memory of her.
The title text culminates this theme by invoking the idea that some day human beings will, likewise, be extinct, and aliens will be able to learn about us through the distorted and faded representations of ourselves that we leave behind - Axe commercials which, like the orchid, present an idealized form to deceptively attract mates. We are left to speculate whether these aliens will be able to construct, somehow, through three levels of indirectness (the human representation, the orchid's representation and the male bee's perception) any memory of the female Eucera, and, if so, how distorted a view of the bee it will be.
[Beret Guy and Megan are walking through a wood.] Megan: There are these orchids whose flowers look like female bees. When males try to mate with them, they transfer pollen.
[Megan kneels next to a flower.] Megan: This orchid - Ophrys Apifera - makes flowers, but no bees land on them because the bee it mimics went extinct long ago.
[Megan stands.] Megan: Without its partner, the orchid has resorted to self-pollinating, a last-ditch genetic strategy that only delays the inevitable. Nothing of the bee remains, but we know it existed from the shape of this flower.
[They walk on past the flower.] Megan: It's an idea of what the female bee looked like to the male bee... Megan: ...as interpreted by a plant. Beret Guy: Wow, so...
[We see a full-colour painting of an orchid flower. It has purple-pink petals on a mottled grey background, along with the bee-like parts. It's quite a realistic painting.] ...the only memory of the bee is a painting by a dying flower.
[The flower is alone in a panel.]
[Beret Guy walks back on screen.]
[Beret Guy kneels down next to it.] Beret Guy: I'll remember your bee, orchid. I'll remember you.
[Beret Guy walks off-panel again.]


LD50

Explanation:
LD 50 is a term used in toxicology that identifies the median lethal dose of a toxin, or how much is required to kill 50% of a given population. LD 50 s are usually measured in g/kg, as the amount of toxin to kill something is usually linearly related with its mass. The lower the LD 50 , the more lethal the toxin. An LD 50 can be determined for almost any substance: for example, the LD 50 for sugar (in rats) is 29.7 g/kg. However, Botulinum toxin (commercially known as Botox in the beauty industry), the most acutely toxic substance known, has a LD 50 of roughly 1 ng/kg, or 0.000000001 g/kg, a vanishingly small amount.
The comic is making the joke that the LD 50 of papers on toxicology is 2 kg/kg, so it takes 2 kilograms of papers on toxicology to kill a person for each kilogram they weigh. The worldwide average weight of an adult is 62 kg (137 lb), so the lethal dose would be 124 kg (273 lb) of toxicology papers. Death is apparently caused by compression or smothering.
The title text says it will take less paper to kill a person if the paper is shoved down their throat instead of dropped on them, either by suffocation or by bursting the subject's stomach. A third method of delivering a toxin is by subcutaneous injections which are highly effective in administering vaccines and medications, but that number is omitted since they couldn't figure out how to do it. If they could, the amount of paper required to trigger a fatal blood vessel blockage would probably be fairly small.
[A figure in a white coat lies on the floor, crushed beneath a giant pile of binders & paper. Megan and Cueball in white coats stand next to him, looking on. Megan is holding a clipboard.]
[Caption below the panel:] The LD 50 of toxicity data is 2 kilograms per kilogram.


Shake That

Explanation:
Visiting a club, Megan is exhorted by a phrase used in several songs, to "shake what your mama gave you", a crude euphemism typically used to encourage shaking one's body parts, referring to any of the sexually appealing anatomical parts of the dancer. Taking this exhortation extremely literally, Megan proceeds to locate a mug presumably given to her by her "mama" labeled "World's greatest daughter" and shakes it.
The phrase "shake what your mama gave ya" was in use as early as 1992, when it was the title of a song by Poison Clan , a southern hip-hop group that was influential from 1990–1995. Another version by Stik-E & Da Hoodz was released in 1995 by Phat Wax records. The line gained a wider audience when it was sampled by Fatboy Slim in the similarly titled "Ya Mama" on his 2000 album Halfway Between the Gutter and the Stars . More recently the line was featured in the Lil Jon single "Stick That Thang Out". In fitting with the general thematic composition of such a song, a large part of which revolves around either goading a woman to, or describing one who is dancing seductively in a nightclub - this line asks a girl to dance, thereby swaying her hips & buttocks, or breasts, the most common male 'fetishes' — making them more conspicuous in the usually dim ambiance because of the phase lag with the rest of the body, which may be attributed to non-rigidity of the elastic structures — for purposes of her male audience's gratification (whether it be solicited or voyeuristic).
The title text refers to another lyrical cliche, "work it", which typically refers to "working" one's body; again, generally seductively. The action may be considered work either from the point of mechanical work, or as a reference to a professional dancer. This naturally leads Megan to further confusion (as indicated by the title text) when taken literally, as she responds "it's already working!" It is not entirely clear if she is again referring to the mug, or simply another generic object not displayed in the comic.
1291: Shoot for the Moon may be a continuation of this, due to Megan misunderstanding common saying or references.
[Megan stands in a disco, surrounded by dancing figures. She looks confused.] PA system: Shake what your mama gave you Megan: ??? [Megan walks out of the club door.] [We see a mug on a table, labelled "World's Greatest Daughter".] [Megan shakes the mug.]