explain xkcd - User contributions [en]

2210: College Athletes

2019-10-02T19:04:08Z

173.245.48.81: /* Transcript */ ce

{{comic
| number = 2210
| date = October 2, 2019
| title = College Athletes
| image = college_athletes.png
| titletext = Their signature play is the three-point combinator, a recursive offense which is guaranteed not to halt and continues accumulating points until the buzzer.
}}

==Explanation==
{{incomplete|Created by a Steph Curry. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

[[Ponytail]] is reading from her phone about the [https://www.nytimes.com/2019/09/30/sports/college-athletes-paid-california.html California Fair Pay to Play act], which was signed into law on September 30, 2019, two days before this comic was released. It gives college athletes the rights to their name and face (images) for financial gain, in contrast to {{w|NCAA}} rules which require that athletes be unpaid. This bill threatens {{w|Amateurism in the NCAA|the NCAA's notion of amateurism}}, which is recently becoming a public debate.

[[White Hat]] thinks this is a good thing, but then [[Cueball]] claims that his state has passed an even better law which ''gave college players rights to use the names and images of any California athletes''. Note that Cueball's state is thus not California, so it is very weird they can use names from another state.

Ponytail doesn't believe him but he carries on claiming that all members of his school's basketball team thus have changed their name to {{w|Steph Curry}}, after the NBA player who plays for the {{w|Golden State Warriors}}, a Californian team. Cueball explains in particular, that only one player copied the name from the NBA player, then another member of the team copied the name from that player, and so on.

This is of course an error, since they only had right to use names of California athletes, and as this is another state than California, they could not have used the law to use the name of one of their fellow team mates. Mistake by Randall, or Cueball that is just making a joke...

Because as it turns out in his final remark, all this has only been the setup for his grand joke, when he tells Ponytail that this process is known as "Currying". This is a play on both the name "Curry" used here, as well as the mathematical procedure called {{w|currying}}, named after mathematician {{w|Haskell Curry}}. This is very typical Cueball, and Ponytail almost fell for it, and thus claims that she hates him!

Currying is when a multi-variable function is broken down into a sequence of single-variable functions, each of which outputs a new function until the final variable is consumed. For example, the function f(x,y,z) can be curried into f(x)(y)(z), where f is a function that consumes x and produces a function f(x), which in turn consumes y, yielding the function f(x)(y), and that in turn is a function f(x)(y) which consumes the parameter z to finally produce f(x)(y)(z), which is equal to the original f(x,y,z). This is not commonly used in most areas of math except for foundational logic but it is widely used in functional programming.

When Cueball says ''a team made up entirely of Steph Currys'', White Hat questions what the plural form should be, and should it instead have been "''Stephs Curry''"? This is referring to the pluralization of phrases where a noun is followed by a modifier of some sort, such as ''attorneys general'', ''parts unknown'', ''heirs apparent'', ''mothers-in-law'', and so on. In these cases, plurals are formed by pluralizing the noun parts of the phrases; however, some of these are rare or foreign enough that speakers of English don't always identify them correctly and pluralize the last word instead, e.g. *''attorney generals''.

The title text is a computer science joke, saying that the Steph Currys basketball team's signature play is the "three-point combinator", a joke on the {{w|three-point play}} in basketball, and a type of {{w|Fixed-point_combinator#Y_combinator|fixed-point combinator}} called the [https://rosettacode.org/wiki/Y_combinator Y Combinator], introduced by Haskell Curry. The description of "three-point combinator" is dense with word play that relates to the Y Combinator, which is used to implement {{w|recursive}} methods in functional programming languages, has notable properties relating to halting (see: the {{w|Halting_problem|Halting Problem}}), and has a common form in which a second argument is used as a counter that is increased by one with each recursive call until termination. "Signature play" may also be a play on words, as currying transforms a {{w|Type_signature#Method_signature|method signature}}.

In this case, when this move is performed, it will just keep accumulating points, as it is guaranteed it cannot halt and will not stop until the time runs out and the buzzer that ends the game is activated. Such a move can of course not be a part of a real basketball game, and more of a nod to the Golden State Warriors' reputation as a high-scoring, nearly-unstoppable offense widely known for three-point shooting.

==Transcript==
:[Cueball, Ponytail and White Hat are having a conversation. Ponytail is checking her phone.]
:Ponytail: Oh, huh. California passed a law giving college athletes full rights to their names and images.
:White Hat: Good, I think?

:[Cueball holds his hand up in a fist, while Ponytail, holding her phone down, and White Hat looks at him.]
:Cueball: That's nothing. '''''Our''''' state gave college players rights to use the names and images of '''''any''''' California athletes.
:Ponytail: It did not.

:[In a frame-less panel Cueball holds his hands out, Ponytail's phone is gone and White Hat puts a hand to his chin.]
:Cueball: Sure it did!
:Cueball: That's how our school fielded a basketball team made up entirely of Steph Currys.
:White Hat: Or is the plural "Stephs Curry"?

:[Cueball holds both hands up in front of him. Ponytail has her arms down but she is balling her hands into fists.]
:Cueball: They didn't all copy the original Steph, though. One player got the rights to his name, then the next player got it from them, and so on.
:Cueball: This process is known as "currying".
:Ponytail: ...I hate you so much.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring White Hat]]
[[Category:Math]]
[[Category:Programming]]
[[Category:Basketball]]
[[Category:Comics featuring real people]]

2092: Consensus New Year

2019-01-01T03:27:14Z

173.245.48.81: /* Explanation */ other calendars

{{comic
| number = 2092
| date = December 31, 2018
| title = Consensus New Year
| image = consensus_new_year.png
| titletext = The biggest jump is at 11:00am EST (4:00pm UTC) when midnight reaches the UTC+8 time zone. That time zone, which includes China, is home to a quarter of the world's population. India and Sri Lanka (UTC+5:30) put us over the 50% mark soon after.
}}

==Explanation==
{{incomplete|Created by a BOT. Please complete this explanation once everyone has entered the new year. Do NOT delete this tag too soon.}}

[[Randall]] is proposing a compromise for when to celebrate, or recognize, {{w|New Year's Day}}. These celebrations traditionally take place at the stroke of midnight between Dec. 31st and Jan. 1st, at the local time of the event's location. With "Consensus New Year", these celebrations would happen at the same time, world over, and would be at exactly 1:30 pm {{w|Eastern Time Zone|EST}} (6:30 pm {{w|Coordinated Universal Time|UTC}}). At this time, about half the world's population would be in 2018 local time and the other half would be in 2019. This is due to the various time zones throughout the world, and the graph is based on the proportion of the population in these zones.

This is based on the erroneous assumption that the entire world uses the same calendar system. Randall's graph shows the year starting on the same day for the entire world. In fact, the Eastern Orthodox churches uses the Julian calendar, on which the year will begin 13 days later, and the year (as of December 2018-January 2018) is 1440 on the Muslim calendar and 5779 on the Hebrew calendar.

The Wiktionary entry for "{{Wiktionary|consensus}}" includes multiple definitions, including these two meanings:
* General agreement among the members of a given group or community...
* (attributive) Average projected value

The second definition represents a noun (the word "consensus") placed before another noun (the phrase "new year") to assign an attribute to it. This is how the word is used in the comic title and also describes the graph in the comic, which shows the "average projected value" of the percentage of the world population reaching the new year at any given time.

The highlighted point at 1:30 PM EST matches the first definition, where more than 50% of the world population has reached the new year, thereby achieving a consensus agreement among the world population.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[A graph labeled “Percentage of the world's population living in 2019” with Y-axis markers at 0%, 50%, and 100%, and X-axis markers at 10:00 AM EST Dec 31st, 1:30 PM EST, 7:00 PM EST, Midnight EST, 3:00 AM EST Jan 1st, and 7:00 AM EST.]
:[The line graph shows the percentage increasing from 0 to 100% in several steps, with 50% reached at 1:30 PM EST.]
:[Caption below the panel:]
:Consensus New Year: as of 1:30PM Eastern Time (6:30PM UTC) a majority of the world's population will be living in 2019.

==Trivia==
Randall has mislabeled the leftmost point of the graph: the Earth's earliest time zone ({{w|UTC+14:00}}) should have the midnight at 5:00 AM EST rather than 10:00 AM EST. The number of one-hour increments on the x-axis does not match Randall's label.

{{comic discussion}}

[[Category:New Year]]
[[Category:Time]]

739: Malamanteau

2018-12-12T19:50:41Z

173.245.48.81:

{{comic
| number = 739
| date = May 12, 2010
| title = Malamanteau
| image = malamanteau.png
| titletext = The article has twenty-three citations, one of which is an obscure manuscript from the 1490s and the other twenty-two are arguments on LanguageLog.
}}

==Explanation==
A {{w|malapropism}} is the use of an incorrect word in place of a word with a similar sound, resulting in a nonsensical utterance. An example of a {{w|malapropism}} is {{w|Yogi Berra}}'s statement: "Texas has a lot of electrical votes," rather than "electoral votes". A {{w|portmanteau}} is a word made-up of two or more combined words and their definitions. For example, motel is a portmanteau, from the words motor and hotel. A {{w|neologism}} is simply a newly coined word that is not yet in common use.

Here, Randall shows a hypothetical Wikipedia page of the word "malamanteau" which is both a portmanteau of "malapropism" and "portmanteau" and a neologism. The method used to create this new word is one of the very words used in the process. This is called a [[917|meta]] or "self-referential" joke.

"Malamanteau" was originally coined in 2007, when it was proposed by user [http://www.metafilter.com/user/17900 ludwig_van] on [http://www.metafilter.com Metafilter] as a term for language errors like "flustrated" (flustered & frustrated) and "misconscrewed" (misconstrued & screwed).

The bottom line of the comic (Ever notice how Wikipedia has a few words it ''really'' likes?) is a reference to the large number of Wikipedia pages that start by labeling their subject matter as a malapropism, a portmanteau, or a neologism.

In response to this comic, editors at Wikipedia created a {{w|malamanteau}} page. It was deleted multiple times and eventually turned into a redirect to the Wikipedia page for {{w|xkcd}}. Malamanteau and the controversy at Wikipedia got coverage at ''The Economist'' and ''The Boston Globe''.

The title text refers to Wikipedia's requirements of citations for a page on there to exist. It also refers to the wide range of places citations can be obtained from, showing a direct opposition due to the use of very different citations (The Language Log arguments are modern and informal, whereas the obscure manuscript is formal and much older). The title text also refers to the fact that [http://languagelog.ldc.upenn.edu/ Language Log] is frequently used for Wikipedia citations.

Language Log is a blog that posts content relating to language and linguistics, including things like malapropisms and portmanteaus. While an informal source, it has produced new linguistic terms before, such as {{w|eggcorn}}. Its comments sections frequently contain discussions and arguments about English, whose participants are probably the same people who write Wikipedia articles about linguistic phenomena like malamanteaus. In actual fact, [http://languagelog.ldc.upenn.edu/nll/?p=2758 Malamanteau] did not appear on Language Log until after this strip. Malamanteau has since been referenced on the Language Log website, with a link to the comic in question. Language Log has referenced XKCD many times before, reposting the comics and linking to the XKCD website.

The title text jokingly refers to the "malamanteau" citations being Language Log references and a document from the 1490s, in reference to the fact that linguists, like those who post on Language Log, often use old documents as evidence, possibly to prove that a construction is a longstanding feature of the language. The joke is that the only references to this word or concept are a 500 year old document and linguists informally arguing about what it means. In reality, if these citations were the only evidence of the term's use, then it would be unlikely to be a notable feature worthy of a Wikipedia article. Most articles that are only cited by a single website tend to get deleted unless the subject has achieved significant coverage in outside news media.

==Transcript==
:[The strip is set up as the top of a Wikipedia page.]
:[The Wikipedia logo.]
:Wikipedia
:The free encyclopedia
:[Side navigation options.]
:Navigation
:-Main Page
:-Contents
:-Featured Content
:-Current Events
:[Wikipedia header options.]
:Article Discussion Edit this page History
:[The article itself.]
:Malamanteau
:From Wikipedia, the free encyclopedia
:A malamanteau is a neologism for a portmanteau created by incorrectly combining a malapropism with a neologism. It is itself a portmanteau of [...the article cuts off.]
:[Below the panel.]
:Ever notice how Wikipedia has a few words it ''really'' likes?

==External links==
*[http://wiki.xkcd.com/irc/Malamanteau Malamanteau] at the xkcd wiki
*[http://malamanteaus.blogspot.com/ Malamanteaus], a blog dedicated to the creation and proliferation of malamanteaux
*[http://www.urbandictionary.com/define.php?term=Malamanteau Malamanteau] at urbandictionary.com
*[http://wordsquirt.com/Word/View/Malamanteau/dbb34d48-e565-4012-bcc8-56718f351712 Malamanteau] at wordsquirt.com
*[http://languagelog.ldc.upenn.edu/nll/index.php?s=malamanteau Entries referencing "malamanteau"] at LanguageLog.com
*Malamanteau Talk Page Archives {{w|Talk:Malamanteau/Archive 1|1}} and {{w|Talk:Malamanteau/Archive 2|2}} at Wikipedia.com
*{{w|Wikipedia:Articles for deletion/Malamanteau}}
*{{w|File:Malamanteau page history.jpg|Screen capture}} of the deleted history for the "Malamanteau" page from Wikipedia
*[//en.wikipedia.org/w/index.php?title=Special:Log&page=Malamanteau Wikipedia Log for "Malamanteau"]
*Beutler, William (May 5, 2010) "[http://thewikipedian.net/2010/05/18/much-ado-about-malamanteau/ Much Ado About Malamanteau]". ''The Wikipedian''
*McKean, Erin (May 30, 2010) "[http://www.boston.com/bostonglobe/ideas/articles/2010/05/30/one_day_wonder/ One Day Wonder]". ''The Boston Globe''
*R.L.G (Nov 4th 2010) "[http://www.economist.com/blogs/johnson/2010/11/neologisms Eggcorn, mashup, malamanteau or other?]". ''The Economonist''
*July 17, 2007 "[http://ask.metafilter.com/67192/How-to-define-this-language-mistake How to define this language mistake?]" - MetaFilter thread with the first usage

{{comic discussion}}
[[Category:Wikipedia]]
[[Category:CC-BY-SA comics]]
[[Category:Portmanteau‏‎]]

1730: Starshade

2018-12-06T02:15:00Z

173.245.48.81: /* Explanation */ Corrected launch date of telescope, as we are in 2018 and it is no longer scheduled for this year

{{comic
| number = 1730
| date = September 7, 2016
| title = Starshade
| image = starshade.png
| titletext = The New Worlds Mission is already trying to get funding for this, but NASA sponsored their proposal, so it will be hard to catch the telescope people by surprise with it.
}}

==Explanation==

[[Megan]] and [[Ponytail]] are talking about {{w|space telescopes}} in general. Megan says that these telescopes could see {{w|exoplanets}} better by using an {{w|occulting disk}}, in the form of free floating opaque discs, that could block out light from the exoplanets' (or exoplanet's) star thus enabling the telescopes to see the weak light from the planets when the glare of the star has been diminished.

She continues by explaining that the scientists behind the new {{w|James Webb Space Telescope}}, at the time of the comic scheduled to launch in 2018, thought about including such a disk, but that it was cut for {{w|James_Webb_Space_Telescope|budget reasons}}. Ponytail asks if it has to be their own disk, and then she decides to kickstart a fund raiser in order to ''build'' a so called ''{{w|starshade}}'' (hence the title. See more about the starshade below). Megan asks her to at least warn the scientist if she makes the shade, but just replies ''"whatever"''. Ponytail is referring to the crowdfunding site {{w|Kickstarter}}, but there is no actual project for a Starshade for Webb (or for New Worlds Mission, see title text explanation).

The final panel shows the {{w|NASA}} control center in 2018 when the Webb telescope is being calibrated. It turns out that Ponytail succeeded and did indeed not warn the scientists. [[Cueball]] is surprised by the disc -- and possibly by what the disc might have printed on it, given its crowdfunded origins -- but [[Hairbun]] immediately notices exoplanets, implying that Ponytail's plan worked.

'''Note''' that the telescope has {{w|James_Webb_Space_Telescope#Partnership|partners from 20 countries}} and is being operated not only by NASA but also by {{w|European Space Agency}} (ESA), {{w|Canadian Space Agency}} (CSA) and the {{w|Space Telescope Science Institute}} (STScI).

The best known space telescope is the {{w|Hubble Space Telescope}} which was launched back in 1990. The Webb telescope is seen as a successor instrument to Hubble and, because its instruments are mainly working in the {{w|infrared}} region of the electromagnetic spectrum, also as a successor to {{w|Spitzer Space Telescope}} launched in 2003. Apart from better instruments and being larger, another improvement over Hubble is that it will be located near the {{w|Lagrangian_point#L2|L2}} Earth–Sun {{w|lagrangian point}}, and thus it's not in orbit around Earth. This means that it can keep focusing on a specific point for longer times, where Hubble can only see a given point for about half an hour before moving behind Earth again. When operating in the infrared range as the Webb telescope does (from middle infrared to red and orange visible light) it is important to be outside the atmosphere (or at least on very high mountains). Another important feature is to keep the temperature constant and very cool. Since the telescope is always in the light of the sun, this can only be achieved by using a large {{w|James_Webb_Space_Telescope#Sunshield_protection|sunshield protection}}.

In the title text the {{w|New Worlds Mission}} is mentioned. The mission is to find new worlds = exoplanets, by applying a starshade to block the light of distant stars, so that the planets around the stars become visible. All discovered exoplanets so far have been found indirectly and not by direct visual confirmation. (Starshade points to this mission when searching for it on Wikipedia.) The title text explains that NASA actually sponsored this mission's proposal to build a starshade for the Webb telescope. Thus the title text concludes that the surprise shown in the comic is not likely to occur in real life. A case of simplified language is used at the end when the scientist are called ''telescope people''. NASA stopped this sponsoring in 2008, and New Worlds Mission has been looking for additional financing since 2010.

It seems clear that [[Randall]] would like to point attention to the New Worlds Mission, maybe hoping for increased funding for the project so a starshade could be a reality already for the Webb telescope. That Randall is interested in exoplanets has been [[:Category:Exoplanets|demonstrated many times]] in xkcd.

'''Note''' that two of the Webb telescopes {{w|James_Webb_Space_Telescope#Scientific_instruments|instruments}}, the NIRCam and the MIRI, feature starlight-blocking {{w|Coronagraph|coronagraphs}} for observation of faint targets such as exoplanets very close to bright stars. So the telescope has measures to improve the sighting of these planets. But Randall (and New Worlds Mission) believes that the starshade would greatly improve the ability to discover and investigate these faint objects.

The starshade, proposed by New Worlds Mission, is a spacecraft designed to work in tandem with space telescopes, not necessarily the Webb telescope. It is a large occulter that should block a stars light. One difficulty with this concept is that light incoming from the target star would diffract around the disc and constructively interfere along the central axis. Thus the starlight would still be easily visible, making planet detection impossible. In order to avoid this effect the starshade is a proposed sunflower-shaped coronagraph disc. The "petals" of the "sunflower" shape are designed to eliminate this diffraction making exoplanet observation possible. The starshade would fly 72,000 km (45,000 mi) in front of a space telescope (between the telescope and a target star) in order to work. There is a great video demonstrating the starshade on its {{w|New Worlds Mission|Wikipedia page}}.

The idea of an occulting telescope was used in [[975: Occulting Telescope]], where it turns out the purpose is to just block all star light not to see exoplanets.

==Transcript==
:[Megan and Ponytail are walking.]
:Megan: Space telescopes could see exoplanets better if they used free-floating opaque discs to block the stars' glare.

:[They stop walking in this zoom in on their heads. Ponytail has turned towards Megan.]
:Megan: They thought about including one with the Webb telescope, but cut it to save money.
:Ponytail: Well... does it have to be ''their'' disc?

:[In this frame-less panel Megan is left standing as Ponytail turns and walks away.]
:Megan: What do you mean?
:Ponytail: Like, if I Kickstart a starshade for them?
:Megan: Um. Would you at least ''warn'' them?
:Ponytail: Eh. Whatever.

:[Cueball and Hairbun, both wearing headsets, are sitting on one legged stools on either side of a slim desk with two computers screens on top of it. Each are looking at their own screens while typing on a keyboard in front of them. Hairbun is pointing at her screen. A small frame is overlaid on the top of the panels frame with a caption:]
:NASA, 2018:
:Cueball: Initiating Webb calibrat-
:Cueball: ''Aaaaa''! What the hell is ''that!?''
:Hairbun: Hey, look, exoplanets!

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Hairbun]]
[[Category:Astronomy]]
[[Category:Exoplanets]]
[[Category:Telescopes]]

1761: Blame

2016-11-18T04:59:15Z

173.245.48.81: added transcript

{{comic
| number = 1761
| date = November 18, 2016
| title = Blame
| image = blame.png
| titletext = I bet if I yell at my scared friends I will feel better.
}}

==Explanation==
{{incomplete|Created by a BOT - Please change this comment when editing this page.}}

==Transcript==
:Cueball: I feel sad.
:Bad things are happening.
:They must be someone's fault.
:But whose?
:[A light bulb, indicating he has an idea]
:My friends on Facebook.

{{comic discussion}}

1547: Solar System Questions

2016-09-05T20:12:12Z

173.245.48.81: /* Explanation */ update - Rosetta just found Philae!

{{comic
| number = 1547
| date = July 6, 2015
| title = Solar System Questions
| image = solar_system_questions.png
| titletext = My country's World Cup win was exciting and all, but c'mon, what if the players wore nylon wings and COULD LITERALLY FLY?
}}

==Explanation==
This comic is a list of questions which [[Randall]] has about the Solar System, which at first glance may appear to be things that Randall would like to learn about.
In actuality, most of the questions have not been satisfactorily answered or proven by anyone in the {{w|List_of_unsolved_problems_in_physics#Astronomy_and_astrophysics|scientific community}}.

{| class="wikitable"
|-
! Question given
! Answer given by Randall (in red in the original)
! Comments
|-
| Why is the the Moon so blotchy?
| Lava
| The {{w|Moon}} is in synchronous rotation with Earth, which means that we always can see only one half of the surface of the Moon. And on that side we can see large {{w|lunar maria}} formed by lava from big volcanoes. This surface is very different from all other celestial bodies we know in our Solar system. The double "the the" could be a Randallism — intended or unintended.
|-
| Why are all the blotches on the near side?
| ...
| The nearside of the Moon is dominated by the blotchy 'seas' or maria, the far side by craters. {{w|Far_side_of_the_Moon#Differences|Several explanations}} for this have been proposed, including an overabundance of impacts obliterating the blotches on the more exposed far side, different compositions of heat-producing elements, large collisions, or heat produced by the still-cooling Earth.
|-
| Did Mars have seas?
| Yes (briefly?)
| Recent explorations have confirmed there was once standing (and also flowing) water on {{w|Mars}}. Many rovers and orbiters on Mars give us the evidence on this early development of that planet, but it is still unknown how long such conditions existed in its history. Two of these probes have been the subject of comics before: [[695: Spirit]] and [[1504: Opportunity]].
|-
| Was there life on Mars?
| ...
| One of the big mysteries, {{w|Life on Mars|not yet answered}}.
|-
| What's Titan like?
| Cold, yellow, lakes + rivers (methane)
| The {{w|Cassini–Huygens}} mission confirmed the presence of {{w|Lakes_of_Titan|lakes and rivers}} on {{w|Titan (moon)|Titan}}. The {{w|Huygens_(spacecraft)#Findings|Huygens}} lander itself returned some very yellow images of a dry lake bed from Titan's surface. The possibility of life on Titan was mentioned in [[829: Arsenic-Based Life]].
|-
| What was Earth like during the Hadean?
| ...
| The {{w|Hadean}} was the first geologic era on earth, the planet had just formed and not much is known of that period of Earth. But since it was the time when Earth was formed it was mainly very hot with extreme volcanic activity, with the entire surface melted. This is why the era is named after {{w|Hades}} the ancient Greek god of the underworld, even though Hades was never associated with fire.
|-
| Is the Oort Cloud a real thing?
| ...
| The {{w|Oort Cloud}} is a theoretical spherical cloud of icy planetesimals, maybe dust, and also larger objects at a distance of up to around 100,000 {{w|Astronomical units|AU}} from our Sun. We can see similar clouds at other stars, but there is still no evidence that this cloud exists in our Solar System.
|-
| Why is the Sun's corona so hot?
| Something about magnets?
| The {{w|corona}} of the sun is hotter than it theoretically should be. Tiny solar flares called {{w|nanoflares}} are responsible.
|-
| What are comets like?
| Precipitous
| The {{w|Philae (spacecraft)|Philae lander}} finally stopped moving when it ran into a cliff.
|-
| Where's Philae, exactly?
| ...
| ...but we were not sure ''which'' cliff until September 5, 2016, when the European Space Agency announced that Philae had been found and photographed by Rosetta on the previous Friday (September 2). The landing of Philae was depicted in real time in the dynamic comic [[1446: Landing]]. This lasted for several hours. Later the comic was updated with a new image where Philae is resting on the edge of a cliff.
|-
| What's Pluto like?
| rowspan="2" | [Soon!]
| rowspan="2" | {{w|Pluto}} is so far from Earth ''and'' so small that traditional telescopes couldn't discern much about it. When this comic was released, the probe {{w|New Horizons}} was eight days away from its closest approach to Pluto and its moon {{w|Charon (moon)|Charon}}; Randall was naturally excited about it. The probe was the subject of the comic [[1532: New Horizons]].
|-
| What's Charon like?
|-
| Why don't we have in-between-sized planets?
| ...
| There is a size-gap between the rocky {{w|terrestrial planets}} up to Earth size and the {{w|gas giants}} very much larger than Earth in our Solar System.
There are many known {{w|exoplanets}} (planets in other solar systems) filling in the range between our rocky planets and our gas giants, known as [https://upload.wikimedia.org/wikipedia/commons/2/2c/Exoplanet_Mass-Radius_Scatter_Super-Earth.png Super-Earths]
|-
| What's Ceres like?
| [Working on it!]
| The {{w|Dawn (spacecraft)|Dawn probe}} is currently exploring the {{w|dwarf planet}} {{w|Ceres (dwarf planet)|Ceres}} and reveals unseen surface features.
|-
| Why is Europa so weird-looking and pretty?
| Ice over a water ocean
| {{w|Europa (moon)|Europa}} is a moon of {{w|Jupiter}} and the surface is basically thick pack ice covered in {{w|lineae}}.
|-
| Why is Io so weird-looking?
| Sulfur volcanoes (? in the wrong places?)
| The moon {{w|Io (moon)|Io}} is also orbiting Jupiter and is close enough that {{w|tidal forces}} make it the most volcanic object in the solar system. The moon is mainly yellow but there are several other colors on the surface, for instance spots and streaks of bright red that comes from {{w|sulfur}} ejected by the volcanoes. The "wrong places" refer to some volcanoes discovered by the {{w|Voyager program|Voyager missions}} and believed to erupt sulfur. But more recent measurements showed that the temperature inside those volcanoes is about 2.000 °C where this element is not liquid anymore but gas.
|-
| Why are so many Kuiper Belt objects red?
| ...
| Many objects in the {{w|Kuiper Belt}} have a reddish hue. A possible explanation is that they are [http://www.space.com/9418-icy-red-objects-solar-system-edge-point-life-building-blocks.html covered in organic molecules] formed by the irradiation of their surface ices. The New Horizons probe might also shed light on this.
|-
| What are those spots on Ceres?
| ...
| The Dawn probe found some mysterious spots on Ceres. These [http://photojournal.jpl.nasa.gov/jpeg/PIA19568.jpg white spots] are still not understood, but the mission is still running and we may figure out the source of the glowing white features. These spots became the punch line of the joke in [[1476: Ceres]].
|-
| What's in the seas under Europa's ice?
| ...
| The {{w|ESA}} selected the mission {{w|Jupiter Icy Moon Explorer|Jupiter Icy Moon Explorer (JUICE)}} to Jupiter. The moon Europa is one target for that mission. But we have to wait, because its launch target is 2022 and the arrival at Jupiter is planned for 2030. But that's not uncommon for missions like this. New Horizons and {{w|Rosetta (spacecraft)|Rosetta}} also traveled approximately ten years to reach their targets. And before such a mission can start many preparations have to be done. {{w|2010: Odyssey Two}} is a 1982 science fiction novel by {{w|Arthur C. Clarke}} in which he envisions life under the ice on Europa. This life becomes a major plot point both in this and in the two sequels.
|-
| Which of the other moons have seas?
| Several
| Randall has already mentioned above that there are liquids on two moons. The Moon Titan at Saturn has lakes on its surface formed by liquid ethane, methane, and propane and the Jupiter's moon Europa has a sea of water covered by a thick sheet of ice. Depending on the definition of 'sea', other less obviously 'frozen water world' moons such as {{w|Ganymede (moon)|Ganymede}} at Jupiter may have {{w|Ganymede (moon)#Subsurface oceans|subsurface}} [http://www.newscientist.com/article/dn27151-aurora-reveals-jupiter-moons-secret-subsurface-sea.html oceans] of liquid water and on other moons it could be other substances that are liquid at the relevant temperature, like on Titan.
|-
| What are the big white things in Titan's lakes?
| ...
| This is a joke about some gaps in the radar measurements as shown in this [https://commons.wikimedia.org/wiki/File:PIA10008_Seas_and_Lakes_on_Titan_full_size.jpg image].
|-
| What do Jupiter's clouds look like up close?
| ...
| The Jupiter mission {{w|Galileo (spacecraft)|Galileo}}, operated by NASA and the German Aerospace Center (DLR), arrived at Jupiter in 1995 and was sent to impact the planet at the end of that mission in 2003 to eliminate the possibility of contaminating local moons with terrestrial bacteria. Several measurements were done on the atmosphere but no pictures were sent back to Earth. So there is still no answer on this question.
|-
| What's all that red stuff in the Great Red Spot?
| ...
| The {{w|Great Red Spot}} is a storm south of Jupiter's equator. Observations from Earth show a lifespan of more than 150 years. It's unknown why it's stable for that long a time and it's also not clear why the color is red. The probe {{w|Juno (spacecraft)|Juno}} will arrive in July 2016 at Jupiter and maybe answer Randall's question.
|-
| What's pushing the Pioneer probes?
| Heat from the RTG
| Discussed as the {{w|Pioneer anomaly}}. RTG stands for {{w|Radioisotope Thermoelectric Generator}}. This effect was mentioned (and explained a little differently) in the title text of [[502: Dark Flow]].
|-
| What pushes spacecraft slightly during flybys?
| ...
| Several spacecraft experienced unexplained speed increases during Earth flybys. This is called the {{w|flyby anomaly}}.
|-
| Where are all the Sun's neutrinos?
| Oscillating
| There are fewer observed electron neutrinos from the sun than the standard model predicts. This is called the {{w|Solar neutrino problem}}. Since the sum of all the neutrinos, regardless of type, that come from the sun add up to the predicted number of electron neutrinos it is theorized that neutrinos can change their type. This is called {{w|Neutrino oscillation}}, and can occur only if {{w|neutrinos}} have mass. Neutrino oscillation is considered a proof that the mass of a neutrino is non-zero. The {{w|Neutrino#Mass|mass of a neutrino}} is not yet measured and is one of the problems on the {{w|List_of_unsolved_problems_in_physics#High-energy_physics.2Fparticle_physics|list of unsolved problems in physics}} on Wikipedia.
|-
| Why is there so much air on Titan?
| ...
| {{w|Titan (moon)|Titan}} has an atmospheric pressure 1.45 times that of Earth, but only 1/7th of the surface gravity which is less than Earth's own airless Moon has, hence the confusion. In fact, Titan actually has almost 20% more atmosphere by mass than Earth, and ''seven times'' more atmosphere across a given surface area! Less influence from the more distant Sun probably helps retain more of the atmosphere's gases (for instance, Mars saw most of its atmosphere blasted away by the sun), and {{w|cryovolcanoes}} may replenish the methane fraction which should by now have ''all'' been converted into the other hydrocarbons present from subsurface reservoirs. Further studies are required to properly answer this question.
|-
| Why does the Kuiper Belt stop?
| ...
| A reference to the {{w|Kuiper Cliff}}. Most Kuiper Belt Objects are found between 42 and 48 {{w|astronomical units|AU}}; calculations predicted that there would be more and larger KBOs beyond 50 AU, but instead very few objects have been found in that region. The reason for this is still unknown.
|-
| Why is Iapetus weird-colored?
| ...
| {{w|Iapetus (moon)|Iapetus}} is a moon of {{w|Saturn}} and always keeps the same face towards Saturn. The trailing side is white while the other side is dark.
|-
| Why does Iapetus have a belt?
| ...
| Iapetus has a 13 km high ridge around most of the equator, and a number of 10-km-high mountains where the ridge is interrupted.
|-
| What's the deal with Miranda?
| ...
| {{w|Miranda_(moon)|Miranda}} is the smallest of {{w|Uranus}}' five round satellites, and it's {{w|Verona Rupes|a bit rough around the edges}} and also has an unusually high orbital inclination that is difficult to explain. Also possibly a [[Firefly|''Firefly'' reference]] since {{w|List of Firefly planets and moons#Miranda|Miranda}} is also the name of a planet in {{w|Serenity (film)|''Serenity''}}, a film based on the {{w|Firefly (TV series)|''Firefly''}} TV series.
|-
| Did Uranus and Neptune change places?
| ...
| The {{w|Nice model}} is a theory of how our solar system formed, which suggests the possibility of Uranus and {{w|Neptune}} having swapped places before reaching their current positions. Work by Professor S. Desch [http://dusty.la.asu.edu/~desch/publications/2007/Desch2007.pdf also came to this result].
|-
| Did the Late Heavy Bombardment happen?
| ...
| The {{w|Late Heavy Bombardment}} is the name given to a theorized bombardment of the planet Earth during its early history, along with the other rocky planets around the Sun. It's believed that during that time many large objects still existed and are likely to have impacted the planets. On Earth the evidence for those impacts would have been destroyed, but on the Moon or Mercury some evidence may be available.
|-
| Did life start before it?
| ...
| For some speculation on this topic, see [http://www.livescience.com/5426-life-survived-earth-early-bombardment.html Life Could Have Survived Earth's Early Bombardment]. It is still a mystery if life was formed on Earth first or if it came from outer space.
|-
| Is Europa covered in ice spikes?
| ...
|Dr Daniel Hobley has put forward a [http://www.bbc.co.uk/news/science-environment-21341176 theory] that Jupiter's icy moon {{w|Europa (moon)|Europa}} has the right conditions to form ice spikes called {{w|penitentes}} of up to 10m in height.
|-
| Why haven't we built a big inflatable Extreme Sports Complex on The Moon?
| ...
| Apart from the question on the white on Titan, this is the only really silly question that has nothing to do with science or the solar system. However, it would be fun to watch sports in such a stadium - see the title text. See also, e.g., ''{{w|The Menace From Earth}}'', a 1957 short story by Robert Heinlein.
|}

The title text refers to the {{w|2015 FIFA Women's World Cup}} which was won by the USA the day before. The nylon wings and flying may be a reference to two passages from 3001: The Final Odyssey, one where Frank Poole tries out various wings while in an extremely low gravity environment, and one where he remarks while watching Swan Lake that Tchaikovsky could never have imagined a performance where the dancers were actually flying (due to aforementioned low gravity). This is also a reference to the last point on the list, because if we had such a stadium on the moon, maybe it would be possible to use such wings to make very long floating leaps.

==Transcript==
:'''Questions I have'''
:'''about the solar system'''
:(some answered)

:{| class="wikitable" style="border: 0px;"
|-
| style="border: 0px; text-align: right" | Why is the the Moon so blotchy?
| style="border: 0px; color:red;" | Lava
|-
| style="border: 0px; text-align: right" | Why are all the blotches on the near side?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Did Mars have seas?
| style="border: 0px; color:red;" | Yes (briefly?)
|-
| style="border: 0px; text-align: right" | Was there life on Mars?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What's Titan like?
| style="border: 0px; color:red;" | Cold, yellow, lakes + rivers (methane)
|-
| style="border: 0px; text-align: right" | What was Earth like during the Hadean?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Is the Oort Cloud a real thing?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Why is the Sun's corona so hot?
| style="border: 0px; color:red;" | Something about magnets?
|-
| style="border: 0px; text-align: right" | What are comets like?
| style="border: 0px; color:red;" | Precipitous
|-
| style="border: 0px; text-align: right" | Where's Philae, exactly?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What's Pluto like?
| style="border: 0px; color:red;" rowspan="2" | [Soon!]
|-
| style="border: 0px; text-align: right" | What's Charon like?
|-
| style="border: 0px; text-align: right" | Why don't we have in-between-sized planets?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What's Ceres like?
| style="border: 0px; color:red;" | [Working on it!]
|-
| style="border: 0px; text-align: right" | Why is Europa so weird-looking and pretty?
| style="border: 0px; color:red;" | Ice over a water ocean
|-
| style="border: 0px; text-align: right" | Why is Io so weird-looking?
| style="border: 0px; color:red;" | Sulfur volcanoes (? in the wrong places?)
|-
| style="border: 0px; text-align: right" | Why are so many Kuiper Belt objects red?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What are those spots on Ceres?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What's in the seas under Europa's ice?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Which of the other moons have seas?
| style="border: 0px; color:red;" | Several
|-
| style="border: 0px; text-align: right" | What are the big white things in Titan's Lakes?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What do Jupiter's clouds look like up close?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What's all that red stuff in the Great Red Spot?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What's pushing the Pioneer Probes?
| style="border: 0px; color:red;" | Heat from the RTG
|-
| style="border: 0px; text-align: right" | What pushes spacecraft slightly during flybys?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Where are all the Sun's Neutrinos?
| style="border: 0px; color:red;" | Oscillating
|-
| style="border: 0px; text-align: right" | Why is there so much air on Titan?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Why does the Kuiper Belt Stop?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Why is Iapetus weird-colored?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Why does Iapetus have a belt?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | What's the deal with Miranda?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Did Uranus and Neptune change places?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Did the Late Heavy Bombardment happen?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Did life start before it?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Is Europa covered in ice spikes?
| style="border: 0px;" |
|-
| style="border: 0px; text-align: right" | Why haven't we built a big inflatable<br> extreme sports complex on the moon?
| style="border: 0px;" |
|}

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Charts]]
[[Category:Soccer]]
[[Category:Space probes]]
[[Category:Astronomy]]
[[Category:Firefly]]

1720: Horses

2016-08-16T03:47:11Z

173.245.48.81: /* Explanation */ safety and pollution

{{comic
| number = 1720
| date = August 15, 2016
| title = Horses
| image = horses.png
| titletext = This car has 240% of a horse's decision-making ability and produces only 30% as much poop.
}}

==Explanation==
{{incomplete|Is White Hat clearly either a sales man or just owner of a nice new car? Maybe this cannot be determined, until Randall makes a transcript... but until then discuss in the comments.}}
[https://techcrunch.com/2016/08/10/are-consumers-automakers-and-insurers-really-ready-for-self-driving-cars/ The programming] of {{w|self-driving cars}} has been in the news lately, as engineers and philosophers debate what rules the cars should follow in dangerous situations (for instance, what to do when forced to choose between hitting a pedestrian or swerving into oncoming traffic). [[Randall]], in the form of [[Ponytail]], suggests one approach for solving this problem: to think of the car as behaving like a horse, using its own intelligence and ignoring dangerous commands in the interests of self-preservation.

The comic begins with Ponytail claiming that in the old days, riding a horse or driving a horse drawn vehicle while drunk was less dangerous than {{w|drunk driving}} today. Given the higher speed and the denser traffic today this might seem plausible. On the other hand, modern cars have seat belts, airbags, and other features designed to save lives when crashes do occur; horses and horse-drawn vehicles lacked these safety features. Ponytail expands the argument by stating the horse itself will (likely) not also be drunk and acting in the interest of its own self-preservation.

This segues into a scene with White Hat, bragging to Cueball and Megan about the features of a car (either to sell the car or simply boast; it's unclear whether White Hat is acting as a salesman) by comparing the features to those of horses. Car engines are traditionally measured in {{w|horsepower}}, which (roughly) compares the power output of the engine to that of a horse. White Hat goes a step further, claiming he can measure the car's onboard computer as a number of "horses", comparing the car's ability to mitigate for a drunk driver and/or avoid obstacles to that of a horse.

The title text features more comparisons of the car to horses. Apparently the car has 240% of a horse's decision-making ability while producing only 30% as much poop. So even with 3.5 horse-intelligence it may only have 2.4 times the decision-making ability (assuming it's the same car). A cars "poop" would be it's exhaust, which is usually not found on the road in the form of solid waste but could still nonetheless be measured, as it contains mass. While no source is stated for the 30% ratio, the point that cars are less polluting that horses is surprisingly valid. Before the invention of the automobile, city streets were commonly filled with horse manure.

Note that riding a horse while drunk is in fact still dangerous and illegal in many places (for example, {{w|Licensing Act 1872|the UK and Ireland}}). A badly-driven horse can throw off its owner, trample passersby, fall on bad surfaces, and destroy any wagon or carriage it's pulling. A self-driving car should be able to understand road rules, which a horse will not - which is presumably why the cars in the comic and the title text are both specified as being more intelligent than a horse.

In [[887: Future Timeline]] dogs driving cars are mentioned... And self-driving cars is a [[:Category:Self-driving cars|recurring topic]] on xkcd.

==Transcript==
:[Ponytail walks right with Cueball.]
:Ponytail: Drunk driving was less of a problem before cars. If you got on your horse drunk and fell asleep, it could just walk home.

:[Zoom in on Ponytail's torso; she holds up a palm to proffer an idea.]
:Ponytail: And if you tried to ride into a tree, the horse could be like "No."
:Ponytail: Forget human drivers – ''that's'' the benchmark we should be judging self-driving cars against.

:[The front end of a car, with the bottom of the windshield and the right side mirror just inside the panel is parked before White Hat. He is holding his hand, palm up, out to the left to indicate his car as he brags about it to Megan and Cueball standing in front of him admiring the car. At the top left of the panel a small frame with a caption is placed over the panels frame:]
:Soon:
:White Hat: This baby has 200 horses under the hood and 3.5 in the computer.
:Megan and Cueball: Ooooh!

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring White Hat]]
[[Category:Comics featuring Megan]]
[[Category:Animals]]
[[Category:Self-driving cars]]

Talk:353: Python

2015-01-03T06:19:34Z

173.245.48.81:

It is necessary for both Cueballs to sample the medicine cabinet in order for this to be a hallucination. It was probably python.{{unsigned ip|122.161.29.247}}
:Or maybe there is just one Cueball - the one on the ground who is hallucinating - because he tried everything...? ;-) [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 20:45, 3 May 2014 (UTC)

'I also sampled everything in the medicine cabinet for comparison' is a possible reference to George's Marvellous Medicine, the children's book written by Roald Dahl, wherein a combination of medicines and household materials produces fantastical effects. [[User:Quetzalcoatl|Quetzalcoatl]] ([[User talk:Quetzalcoatl|talk]]) 14:31, 10 February 2014 (UTC)

:I think it's related to the invention of photographs, but I'm not sure [[Special:Contributions/173.245.48.81|173.245.48.81]] 06:19, 3 January 2015 (UTC)

Woah guys, antigravity is a real module in Python! I was looking around the lib folder, trying to figure out how to put a module into it, and there it was - antigravity.py . It just sends your browser to the comic. --[[Special:Contributions/108.162.219.171|108.162.219.171]] 22:07, 13 December 2014 (UTC)
:Yeah, that's already covered in the ''Trivia'' section ;-) --[[User:SlashMe|SlashMe]] ([[User talk:SlashMe|talk]]) 23:22, 14 December 2014 (UTC)

1132: Frequentists vs. Bayesians

2014-10-06T00:15:11Z

173.245.48.81: /* Explanation */ added some explanation of neutrino detectors and other methods of solar explosion detection at night

{{comic
| number = 1132
| date = November 9, 2012
| title = Frequentists vs. Bayesians
| image = frequentists_vs_bayesians.png
| titletext = 'Detector! What would the Bayesian statistician say if I asked him whether the--' [roll] 'I AM A NEUTRINO DETECTOR, NOT A LABYRINTH GUARD. SERIOUSLY, DID YOUR BRAIN FALL OUT?' [roll] '... yes.'}}

==Explanation==
{{incomplete|The core subject matter, as well as the interpretation of the last panel, is open to debate.}}

This is a comic about probability theory.

During the night, a person cannot directly observe the sun to see if it has exploded, but can tell indirectly by a variety of means, many of them simple and practical. For example, the person could use a telephone to call a person in a place where it is day, read posts on Twitter, or look at the moon (the moon does not make its own light, and appears bright only because of reflectd sunlight). In the comic, a person relies on the fact that neutrinos can pass through the earth, so a neutrino detector would detect neutrinos from the sun at all times, day and night. Although this is a theoretically possible method of detecting solar explosions, it is exceedingly impractical, especially using a detector of the size depected in the comic. (If current neutrino detection technology was scaled down to the size shown, and the sun did not become a supernova, then the average rate of neutrino detection would be less than one per week, so waiting for dawn would be faster than waiting for a neutrino to be detected. If the sun did become a supernova, then the entire earth, including the detector, would be instantly destroyed, so the mere fact that the detector survives to give any response is sufficient to conclude, with 100% certainty, that the sun has not become a supernova.) In addition, the detector is stated to give false results ("lie") 1/36th of the time. Assuming this detector is otherwise reliable, when the detector reports a solar explosion, there, there are two possibilities: either (a) the sun has exploded (which is extremely unlikely), but has not become a supernova), and the detector is telling the truth, or (b) the sun ''hasn't'' exploded and the detector is lying (which occurs 1/36th of the time).

The Frequentist considers what he knows about the detector. Since the detector rolls two standard dice and only lies if they both land on 6, there is only a 1/36 chance that the detector is lying. He references the concept of {{w|P-value|p}}<0.05, which is a scientific research standard where a result is presumed to provide strong evidence against a "null hypothesis" if there is less than a 5% chance that the result occurs given that the null hypothesis is true. (For instance, if you test a new medicine and find that it appears to help your test subjects, and you find that, statistically speaking, the chance that the test subjects improved from the placebo effect alone is less than 5%, you would consider this strong evidence that the medicine is really working.) He notes that the P-value in this case is less than 0.05, and thus the standard threshold has been met. Simply put, the Frequentist notes that it is unlikely for the detector to lie, and therefore the sun has probably exploded.

The Bayesian uses a more comprehensive approach. Based on what he knows about the detector, it is unlikely that the detector is lying. But based on what he knows about the ''sun'' (and possibly the relative improbability that the a solar explosion would be detected by the neutrino detector before the expected time of dawn, without being destroyed by a supernova), it is ''extremely'' unlikely that the sun has suddenly exploded. (Modern astronomy tells us that the sun will retain its current condition for at least 5 billion years, aside from minor variations in its output.) The unlikeliness of the detector lying is greatly outweighed by the unlikeliness of the sun exploding. (In Bayesian reasoning, in this context, the knowledge about the probability of the sun exploding is called a {{w|Prior probability|"prior"}}.) Therefore, he concludes that the sun has ''not'' exploded and the detector is lying. (This line of reasoning is not made explicit in the comic, but it is typical of how an ordinary Bayesian would approach the situation.)

The Bayesian's line, "Bet you $50 it hasn't", could be taken as a simple expression of confidence, based on the reasoning above. It could also be taken to mean that the Bayesian has had a further thought: If the sun ''has'' exploded, civilization will quickly collapse and money will become worthless. Thus, even if he loses the bet, he really loses nothing at all. This again references the idea that Bayesians tend to consider things in context, whereas Frequentists have a narrow focus. (It's also a tongue-in-cheek reference to the absurdity of the premise.)

The title and the last two frames suggest that "frequentist" interpretation of statistics is somehow wrong, which has prompted debate. Many believe that the Bayesian and the frequentist interpretations of probability theory are not mutually exclusive and neither is wrong. One argument states that the Frequentist in the comic is actually misusing P-values, in a way that violates standard frequentist practice. P-values are usually used only for numerical values that are known to fall along a specific distribution — in this case, it is used to determine the significance of a discrete event, which is wrong. Others believe that the use of prior knowledge by The Bayesian enables him to reach his conclusion. For more views on this issue, see the discussion box.

The labels on the bottom two panels were applied as an after-thought, according to Munroe's post [http://web.archive.org/web/20130117080920/http://andrewgelman.com/2012/11/16808/#comment-109366 here]; he states his intention was "to illustrate a case where naïve application of that significance test can give a result that's obviously nonsense."

[[File:Nate Silver Tweet.png|.@JoeNBC: If you think it's a toss-up, let's bet. If Obama wins, you donate $1,000 to the American Red Cross. If Romney wins, I do. Deal?|right]]

Arguably, this is another comic about the accuracy of presidential election predictions that used Bayesian statistical models, such as Nate Silver's ''538'' and Professor Sam Wang's ''PEC''. Thomas Bayes studied conditional probability — the likelihood that one event is true when given information about some other related event. From {{w|Bayes Theorem|Wikipedia}}: "Bayesian interpretation expresses how a subjective degree of belief should rationally change to account for evidence". The Bayesian's bet may refer to a well-publicized bet that Nate Silver tried to make with Joe Scarborough regarding the outcome of the election (see tweet on the right).

The title text refers to a classic series of logic puzzles known as {{w|Knights and Knaves#Question 3|Knights and Knaves}}, where there are two guards in front of two exit doors, one of which is real and the other leads to death. One guard is a liar and the other tells the truth. The visitor doesn't know which is which, and is allowed to ask one question to one guard. The solution is to ask either guard what the other one would say is the real exit, then choose the opposite. Two such guards were featured in the 1986 Jim Henson movie ''[[246|Labyrinth]]'', which is referenced in the text.

==Transcript==
:Did the sun just explode? (It's night, so we're not sure)

:[Two statisticians stand alongside an adorable little computer that is suspiciously similar to K-9 that speaks in Westminster typeface.]
:Frequentist Statistician: This neutrino detector measures whether the sun has gone nova.
:Bayesian Statistician: Then, it rolls two dice. If they both come up as six, it lies to us. Otherwise, it tells the truth.
:Frequentist Statistician: Let's try. [to the detector] Detector! Has the sun gone nova?
:Detector: ''roll'' YES.

:Frequentist Statistician:
:Frequentist Statistician: The probability of this result happening by chance is 1/36=0.027. Since p<0.05, I conclude that the sun has exploded.

:Bayesian Statistician:
:Bayesian Statistician: Bet you $50 it hasn't.

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

1390: Research Ethics

2014-07-04T18:05:08Z

173.245.48.81: spelling fix

{{comic
| number = 1390
| date = July 4, 2014
| title = Research Ethics
| image = research_ethics.png
| titletext = I mean, it's not like we could just demand to see the code that's governing our lives. What right do we have to poke around in Facebook's private affairs like that?
}}

==Explanation==
{{incomplete|First draft. The image must be updated.}}

This comic references the recent revelation that Facebook engaged in a "psychological experiment" by selectively showing users more "positive" or "negative" posts on their news feed and recording the users' comments to see if the change affected the positivity or negativity of their posts. Further experiments have since been revealed [http://online.wsj.com/articles/facebook-experiments-had-few-limits-1404344378 such as one that tested security measures by locking users out of their accounts]. Here, Megan is commenting on the fact that, while the media is calling this control over what content the user sees "unethical," Facebook, and other companies like Google, must, one way or another, control what content the user sees, whether to present users with a limited selection of all postings, or to tailor ads to particular users; even if the regular algorithms are not set up for psychological experiments, they are still "manipulating" what posts users see or don't see. As Megan points out, no one really knows what the "normal" constraints are of the algorithm which chooses which posts are shown on news feeds. This comic is parodying the strong reaction to what is basically already a common practice.

Accumulation, control and analysis of user-generated information can be a part of the terms of service/end user license agreement of a Website or software. In such a scenario, the user has effectively signed his/her consent to being part of such research. Unfortunately, most users don't read the terms before clicking the "I agree" option, so it can come as a shock when the service uses the data in a way the user hadn't anticipated.

The comic that Randall originally published contained the word "what" twice (on the end of the first line and again on the start of the second line), which is a typical mistake that would be detected by many spell checkers [http://blogmines.com/blog/wp-content/uploads/2011/08/image_thumb18.png]. Randall fixed the error after a few hours.

The title text ironically/sarcastically accepts that Facebook has access to all of its users thoughts (through posts/messages and photos, and they can read them for research (or whatever other) purposes, but contrasts this with a suggestion (which likely mirrors how Facebook would respond to such a request) that Facebook's code is private and can not be revealed to us. The title text basically appears to be musing that this is backwards, and our personal data should be considered MORE private than Facebook's programming code, which may be proprietary, but is not personal private data.

It is as if your neighbor was spying on you while you left all your shades open, but you felt it to be inappropriate to find out what he knew about you because that's his business.

==Transcript==

:[Megan is facing Cueball and Ponytail]
:Megan: Facebook shouldn't choose what stuff they show us to conduct unethical psychological research.
:Megan: They should ''only'' make those decisions based on, uh...
:Megan: However they were doing it before.
:Megan: Which was probably ethical, right?

{{comic discussion}}