explain xkcd - User contributions [en]

1991: Research Areas by Size and Countedness

2018-05-09T20:22:56Z

Stumpy3521: /* Explanation */

{{comic
| number = 1991
| date = May 9, 2018
| title = Research Areas by Size and Countedness
| image = research_areas_by_size_and_countedness.png
| titletext = Mathematicians give a third answer on the vertical axis, "That question is poorly defined, but we have a sub-field devoted to every plausible version of it."
}}

==Explanation==
{{incomplete|Created by a VERY BIG AND NUMEROUS RESEARCH FIELD - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This is a 2-dimensional chart that is about different research fields. The vertical axis is the accuracy of the quantity of the studied object, and the horizontal axis is how large the studied object is.

Entymology on the graph is possibly a reference to [[1012: Wrong Superhero]].

;Upper left quadrant (Small & count known)

{| class = "wikitable"
! Research field
! Explanation
|-
|{{w|Elementary particle physics}}
|Elementary particle physics is concerned with the study of subatomic particles, of which there are 17. Most notably, until recently it was uncertain whether the {{w|Higgs boson}} was one of the elementary particles, but scientists have a "pretty good estimate" because the mathematical models don't predict the existence of many other particles
|-
|{{w|Dentistry}}
|Dentistry is the study of teeth. Humans grow 32 teeth, which is a "pretty good estimate" since it is very rare for {{w|Hyperdontia|more than 32 teeth to grow}} and it is rather common for {{w|wisdom teeth}} to be surgically extracted
|-
|{{w|Shakespeare}} studies
|Shakespeare studies is concerned with the works of William Shakespeare. Generally, 36 plays are attributed to him, but between 1 and 3 additional plays are considered "lost" (i.e. at some point between being first published or performed and scholars seriously studying Shakespeare, all known copies, references, and fragments were destroyed, making it impossible to determine whether Shakespeare actually wrote them or whether they actually existed as separate plays), and {{w|Shakespeare apocrypha|some 20 more}} are believed to have been written by him, but not signed. To make matters worse, some plays that ''were'' published or performed under Shakespeare's name are believed to have been written as collaborations (not fully by him) or mis-attributed (we don't know who wrote them but, everyone says it was him).
|-
|{{w|Ornithology}}
|Ornithology studies birds. As with all animal classifications, we aren't really certain how many species there are, and are [https://www.amnh.org/about-the-museum/press-center/new-study-doubles-the-estimate-of-bird-species-in-the-world constantly revising the figure], but all estimates remain in the low thousands, so we do have a "pretty good estimate"
|-
|{{w| literature}}
|
|}

;Lower left quadrant (Small & count unknown)

{| class = "wikitable"
! Research field
! Explanation
|-
|{{w|Mycology}}
|
|-
|Entymology
|It is unclear whether [[Randall]] means {{w|entomology}} or {{w|etymology}} (probably neither; it's likely that this wasn't a mistake).
|-
|{{w|Microbiology}}
|
|-
|{{w|Pharmacology}}
|
|}

;Upper right quadrant (Big & count known)

{| class = "wikitable"
! Research field
! Explanation
|-
|Marine Mammology
|
|-
|Presidential History
|
|-
|{{w|Railway}} Engineering
|
|-
|{{w|Geology}}
|
|-
|{{w|Cosmology}}
|Cosmology is the study of the universe. There is an asterisk with the note "Depends on who you ask", relating to the estimate of how many universes there are. While it might seem obvious that there is only one universe, some branches of physics believe that our universe is part of a {{w|multiverse}}, and this remains an open and contested subject in the field.
|
|}

;Upper right quadrant (Big & count unknown)

{| class = "wikitable"
! Research field
! Explanation
|-
|{{w|Botany}}
|
|-
|{{w|Paleontology}}
|
|-
|{{w|Black Hole}} Astronomy
|
|-
|{{w|Exobiology}}
|
|-
|{{w|Theology}}
|How many gods?
|}

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

{{comic discussion}}

1991: Research Areas by Size and Countedness

2018-05-09T15:29:21Z

Stumpy3521:

1990: Driving Cars

2018-05-07T19:01:41Z

Stumpy3521: /* Explanation */

{{comic
| number = 1990
| date = May 7, 2018
| title = Driving Cars
| image = driving_cars.png
| titletext = It's probably just me. If driving were as dangerous as it seems, hundreds of people would be dying every day!
}}

==Explanation==
{{incomplete|Created by a SCARY CAR- Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic is a joke about how dangerous cars are. It says how it is a giant machine, and Cueball is only able to drive it because he took a driving test. This is similar to other comics (need links) where Randall comments on how odd some of our "routine" everyday tasks are quite unusual when viewed from a certain perspective.

The rest of the joke is in the title text, "It's probably just me. If driving were as dangerous as it seems, hundreds of people would be dying every day!" Of course, many people ([http://asirt.org/initiatives/informing-road-users/road-safety-facts/road-crash-statistics over 3,000] world-wide, about 100 in USA) do die every day in car accidents. Furthermore, an unknown and difficult to estimate number of people die prematurely as a consequence of pollution caused by cars. Many people would, however, argue that this human sacrifice is acceptable in view of the real and perceived advantages of being able to drive giant machines from A to B.

A faded Cueball is visible above Cueball in the comic picture. This may be a previous draft that Randall drew on top of.

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

:[Cueball stands in front of a car.]
:Cueball: Time to accelerate this giant machine up to terrifying speeds and steer it using my hands, which I am allowed to do because I took a 20-minute test in high school!

:[Caption below the panel:]
:Driving freaks me out.

{{comic discussion}}

[[Category:Comics featuring Cueball]]

1670: Laws of Physics

2018-03-27T15:24:11Z

Stumpy3521: /* Explanation */

{{comic
| number = 1670
| date = April 20, 2016
| title = Laws of Physics
| image = laws_of_physics.png
| titletext = The laws of physics are fun to try to understand, but as an organism with incredibly delicate eyes who evolved in a world full of sharp objects, I have an awful lot of trust in biology's calibration of my flinch reflex.
}}

==Explanation==
[[Black Hat]], being {{w|Black Hat}}, is deliberately perverting a classic physics demonstration. In the normal version of the demonstration, a heavy ball on a pendulum is pulled to one side until it is almost, but not quite, touching the demonstrator or volunteer's nose or chin. When the ball is released at rest, it swings down and away, then back up to (almost) the same distance in the arc from where it started — but ''never'' (by the laws of physics) farther than where it started. As long as the demonstrator doesn't lean in or push the ball, it's impossible for it to strike them. It's a natural instinct to move away or protect yourself if you see a heavy object moving quickly toward you, but confidence in the physics of the demonstration means there is no reason to flinch. (Sample videos: [https://www.youtube.com/watch?v=xXXF2C-vrQE], [https://www.youtube.com/watch?v=i2GdY1OlDpA].)

In this comic, Cueball is not standing at the beginning edge of the ball's movement, but rather at the base of its swing, meaning that the ball will strike him at its maximum speed. Presumably, Black Hat is entirely aware of this and is hoping that Cueball's understanding of physics is insufficient to see through this prank. Judging from the "slack" of the rope, the ball should not hit Cueball in the head but would almost certainly hit him in a lower, and quite painful, place...

The title text refers to the fact when someone flinches during the pendulum experiment, they are commonly accused of not having faith in the laws of physics. Randall is rebutting this argument by stating that, rather than not having faith in science, he is actually in tune with it, specifically the biological processes that led to the flinch reflex. His eyes and his flinch reflex have been calibrated through millions of years of evolution. To instantly dismiss his body's natural reaction when a heavy object comes quickly towards his face does not give enough credit to these mechanisms that successfully kept him (and every one of his ancestors) alive. In other words, while flinching may indicate doubt of the laws of physics, it may equally well indicate trust in the laws of biology.

The idea of hitting someone else with a pendulum is also the topic of [[755: Interdisciplinary]].

==Transcript==
:[Black Hat is standing on a ladder, holding a heavy ball attached to a line from above. Cueball stands beneath, where if the ball swings it will smack him right in the face.]
:Black Hat: Okay, hold still.
:Black Hat: And remember, if you ''really'' believe in the laws of physics, you won't flinch.

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

737: Yogurt

2018-03-21T14:54:04Z

Stumpy3521: /* Explanation */

{{comic
| number = 737
| date = May 7, 2010
| title = Yogurt
| image = yogurt.png
| titletext = I am firmly of the opinion that if something doesn't have a year on it, every time the expiration date rolls around it is good again for the two weeks preceding that date.
}}

==Explanation==
Most packaged food has an {{w|shelf life|expiration date}} that indicates when the food will probably no longer be suitable for consumption. This could be due to any number of reasons; most products will rot or grow mold after their expiration date passes, but some processed foods will "dry out" or just generally become "unpleasant" long before they actually spoil. The expiration date is sometimes called a "best before" or "use by" date for this reason.

Some products don't list the year as part of the expiration date, on the assumption that by the time the year becomes an issue, the food will obviously be spoiled. [[Cueball]] is encountering this issue; clearly the yogurt has gone bad - it's raising "stink lines" and appears to have visible mold - but the expiration date only lists "May 12th" and it's currently May 7th, so the characters reason that it must still be good since the expiration date hasn't passed yet. Somehow, they fail to notice the terrible smell coming off of it.

The {{w|Gregorian calendar}} was initially adopted in the Catholic European countries in 1582 to correct the slow drift of the seasons relative to the calendar year that occurred under the Julian calendar. The Protestant and Orthodox countries were slower to adopt it. The British Empire, including the American colonies, adopted the Gregorian calendar in 1752. Cueball (in a seemingly sarcastic manner) wonders whether the expiration date might have been printed under the Julian Calendar, i.e., at least several hundred years ago.

The {{w|Gregorian calendar}} (our current calendar) is mostly the same as the {{w|Julian calendar}} with two major differences:

*The Julian calendar overestimated the length of a year by 10 minutes 48 seconds or about 1 day every 128 years. The Gregorian calendar has 97 leap days every 400 years instead of 100, which reduces the error to about 1 day in 3300 years.
*As each country adopted the Gregorian calendar, it was necessary to skip the appropriate number of days to realign the {{w|Vernal Equinox}} with March 21. When the British Empire adopted the Gregorian calendar in 1752, 11 days had to be skipped, so in the English-speaking countries, September 2, 1752 under the Julian calendar was immediately followed by September 14, 1752 under the Gregorian calendar; there was no September 3–13 in that year.

The last line spoken by Cueball may mean one of two things: either 1) he is continuing to be sarcastic toward his friend, or 2) he is genuinely considering that it may not have gone bad, despite all the clues saying otherwise.

The title text is Randall's own (slightly absurd) view: for a short period of time preceding the expiration date of any food, no matter how many years have passed, it suddenly becomes good to eat again.

==Transcript==
:[Cueball is holding a yogurt cup at arm's length. Waves of stink are rising from it.]
:Cueball: Oh God, how old is this yogurt in your fridge?
:[Someone speaks from off-panel.]
:Person: What's the expiration date?

:[Cueball holds up the cup to look at the bottom.]
:Cueball: May 12th, but there's no year.
:[From off-panel again.]
:Person: It's May 7th. So it's fine.

:[Now the second person is on panel, and Cueball speaks from off-panel. The second person is sitting down working on a laptop.]
:Cueball: I'm not sure. When it was packaged, was civilization using the Gregorian or Julian calendar?
:Person: ''Okay,'' I'll throw it out.
:Cueball: No, it might still be good!

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

1437: Higgs Boson

2018-03-21T14:50:57Z

Stumpy3521: /* Explanation */

{{comic
| number = 1437
| date = October 22, 2014
| title = Higgs Boson
| image = higgs_boson.png
| titletext = 'Can't you just use the LHC you already built to find it again?' 'We MAY have disassembled it to build a death ray.' 'Just one, though.' 'Nothing you should worry about.' 'The death isn't even very serious.'
}}
==Explanation==
[[Cueball]] and [[Ponytail]] are applying for a large amount of grant money to find the {{w|Higgs boson}}. Under scrutiny, they have been forced to admit that they have "lost" the particle which had been previously "found". This is a humorous play on the term "finding" when applied to fundamental particles. The common usage means to discover or observe the existence of a class of particles, rather than to know the current location of an individual particle.

''The Higgs boson'' is an {{w|elementary particle}} that is predicted by a physical model of the universe (the '{{w|Standard Model}}'). Observing evidence that Higgs bosons really exist is a key test of this model: if a search for the Higgs boson had failed to find evidence confirming its existence then the Standard Model would have been shown to be an incorrect description of reality. Finding the Higgs boson was one of the main reasons why the {{w|Large Hadron Collider}} (LHC) was built: to create energies high enough for the Higgs boson to become manifest. The point is, once evidence for its existence has been observed it is not possible to 'lose' the Higgs boson in a way implied by Cueball and Ponytail.

In the title text, the off-screen questioner wonders why Cueball and Ponytail can't use the LHC to find the particle again. The implication is that this would avoid spending another $3 billion. Their responses imply that the pair have already dismantled the LHC and converted its components into a {{w|death ray}} (most likely a {{w|particle-beam weapon}} to be exact). The ostensibly reassuring platitudes offered mimic those used to placate those who were worried about possible apocalyptic consequences of commissioning the LHC, for instance the creation of {{w|black hole}}s, {{w|strange matter}}, a {{w|vacuum bubble}} or proton-eating {{w|magnetic monopole}}s.

The comment that "The death isn't even very serious" in the title text may be a reference to Isaac Asimov's "I, Robot." Robopsychologist Dr. Susan Calvin tells supercomputer The Brain not to worry about death, that it wasn't a "big deal," when the robot is working on an equation relating to hyper drive. The Brain was able to deliver the solution, since anyone using the hyperdrive would be briefly "dead" (no longer exist), but in the end, they would arrive safe and sound.

This also implies that the death ray was only able to produce one death, as opposed to the many deaths such a weapon could be expected to cause, just as it is implied that the LHC only produced a single Higgs boson, which was subsequently misplaced. In [[401: Large Hadron Collider]] the proton stream from the LHC was used to cause the eventual death of a helicopter.

==Transcript==
:Offscreen: Tell us about your proposal.
:Ponytail: We're requesting $3 billion in funding to find the Higgs boson.

:Offscreen: ...wait. Didn't you already find it a year or two ago?
:Cueball: Yes, well, um.

:Ponytail: ...OK, this is embarrassing.
:Cueball: See, the thing is—

:Offscreen: Don't tell us you lost it already.
:Ponytail: Look.
:Ponytail: In our defense, it's ''really'' small.

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

1959: The Simpsons

2018-02-23T16:33:00Z

Stumpy3521: /* Explanation */

{{comic
| number = 1959
| date = February 23, 2018
| title = The Simpsons
| image = the_simpsons.png
| titletext = In-universe, Bart Simpson and Harry Potter were the same age in 1990. Bart is perpetually 10 years old because of a spell put on his town by someone trying to keep him from getting his Hogwarts letter.
}}

==Explanation==
{{incomplete|Created by a TED CRUZ - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

''{{w|The Simpsons}}'' is an American {{w|animated sitcom}} centered on the lives of the fictitious {{w|Simpson family}}. ''{{w|The Simpsons}}'' is a very long-running series, having started with {{w|Simpsons Roasting on an Open Fire|a Christmas episode}} in 1989, with the rest of {{w|The Simpsons (season 1)|the first season}} airing in 1990. As of the publication of this strip, it's still in production, having been on the air for 28 years with the same characters and primary cast. The decision was made early in the series that the characters wouldn't age, meaning that the parents. {{w|Homer Simpson|Homer}} and {{w|Marge Simpson|Marge}}, remained perpetually in their mid-thirties. The three children, {{w|Bart Simpson|Bart}}, {{w|Lisa Simpson|Lisa}}, and {{w|Maggie Simpson|Maggie}}, have remained 10, 8 and 1 year old, respectively. One of the interesting impacts of this dynamic is that the audience and the world have significantly aged over the course of the show, but the characters remain the same age. A rather dramatic example is that many of the early fans were similar in age to the children, but have now grown up, many have gotten married and had children of their own, and now closer in age to the parents. This is both a commentary on the longevity of the show, and another entry in XKCD's [[:Category:Comics_to_make_one_feel_old|genre of comics that emphasize how surprising the passage of time can be]].

The title text further relates this to the {{w|Harry Potter}} series, providing an explanation for why nobody has aged. Harry Potter is the protagonist in a series of young adult novels (later adapted into films) about the adventures of a boy wizard in his magical school, {{w|Hogwarts}}. The series begins when Harry is accepted to Hogwarts, at age 11, and the timeline implies that he was born in 1980. When "The Simpsons" began, Bart was 10, implying he was also born in 1980. Unlike Bart Simpson, Harry and his compatriots explicitly age over the course of the series. This strip ties the two series together, joking that the lack of aging in the Simpsons is a result of magic from the Harry Potter universe, intended to stop Bart from ever turning 11, for fear that he'd be accepted to Hogwarts.

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

:[A black frame containing a table of two columns and three rows, mostly in grey. The columns are titled 1990 and 2018, the rows are titled Lisa, Bart, and Homer & Marge. Lisa & Bart's ages now, as well as Homer & Marge's age in 1990, are in black, surrounded by a black circle visually grouping these three entries together.]

:Fun Fact:
:{| class="wikitable style="border:none;"|
|-
| || 1990 || 2018
|-
| Lisa || 8 || 36
|-
| Bart || 10 || 38
|-
| Homer & Marge || 36-ish || 64-ish
|-
|}

:[Caption below:]
:If you were Bart and Lisa's age during the first few seasons of The Simpsons, this year you're the same age as Homer and Marge.

{{comic discussion}}

[[Category:Fun fact]]