explain xkcd - User contributions [en]

Talk:2656: Scientific Field Prefixes

2022-08-09T02:22:14Z

108.162.250.198:

Interestingly enough, the last time I was at a dentist, I ask them if they had seen any research work on how to do dentistry in zero-g, like if you got a toothache halfway to Mars.
[[Special:Contributions/162.158.107.56|162.158.107.56]] 01:58, 9 August 2022 (UTC) BCS

Those who say that there's no such thing as High-Energy Theology should be taken with a pinch of salt. Or even a {{w|Lot's wife|Lot}}! [[Special:Contributions/172.70.91.80|172.70.91.80]] 02:05, 9 August 2022 (UTC)

I'm a little concerned with Theoretical Theology. How much more theoritical can base theology be? [[Special:Contributions/108.162.250.198|108.162.250.198]] 02:22, 9 August 2022 (UTC) Beechmere

1868: Eclipse Flights

2022-05-21T01:05:37Z

108.162.250.198: Undo revision 270757 by Explain xkcd server admin (talk)

{{comic
| number = 1868
| date = July 26, 2017
| title = Eclipse Flights
| image = eclipse_flights.png
| titletext = The captain has turned on the 'fasten seat belt' sign.
}}

==Explanation==

A {{w|total solar eclipse}} occurred on {{w|Solar eclipse of August 21, 2017|Monday, August 21, 2017}}. It was visible as a total eclipse in {{w|umbra|a narrow band}} across the contiguous United States from Oregon on the Pacific coast to South Carolina on the Atlantic. [[Cueball]] asks [[Megan]] what she is doing, which turns out to be mapping the flights of aircraft that will be flying through the path of totality during the eclipse. She has found between 50 to 100 such flights.

While most flights during the eclipse are coincidental, a few airlines had special flights planned for the occasion. Alaska Airlines, [https://www.usatoday.com/story/tech/science/2017/07/20/solar-eclipse-2017-flights-offer-unobstructed-potentially-longer-view/493343001/ for example,] chartered an invitation only flight for about 50 astronomers and serious eclipse chasers.

On the map, the center of the greatest eclipse is shown on the border between {{w|Illinois}} and {{w|Kentucky}}. Cueball says that the airlines and pilots will be prepared and aware of the situation, but Megan wonders what it would be like on a plane with an unprepared crew. The last panel shows a plane flying into the area of the eclipse with one of the crew telling the passengers that the end of the world has come.

In many cultures such as ancient Egypt, the end of the world is represented by a great darkness and the sun going out. During past eclipses, people were said to have believed the world was ending much like this comic (except without planes). This could also be a reference to [[1391: Darkness]] as in that comic the reporters also believed a natural event to be the world ending although in a different setting.

The title text refers to the 'fasten seat belts' signs on display for the passengers, as a precautionary measure for turbulence. Many pop-culture depictions of the end of the world feature storms, earthquakes, tsunamis, volcanic eruptions, etc; as the captain believes that the end of the world is upon them, he feels it safe to ensure his passengers are prepared for turbulence from any of the phenomena that occur during the end times. However, the precaution of having one's seat belt fastened is vastly insufficient when confronted with such catastrophic events.

This was the first reference to the Eclipse within a month of the totality. It was followed less than three weeks later by [[1876: Eclipse Searches]]. The 2017 eclipse was mentioned as early as 2013 in the title text of [[1302: Year in Review]]. And this year's New Year comic, [[1779: 2017]], also mentions it. Both comics express concern, in the title text, that it would be canceled/not happen.

==Transcript==
:[Cueball is standing behind Megan, looking over her shoulder as she's seated in front of her laptop.]
:Cueball: What's that?
:Megan: Flight plans. Looks like there will be 50 to 100 flights whose route puts them in the path of the eclipse next month.

:[A map with a shaded path of the eclipse and red planes traveling is shown, with nine planes inside the path and one inside the eclipse shadow..]

:Cueball: I'm sure the airlines will be prepared. Pilots know that stuff.
:Megan: But can you imagine being on the one flight where the pilot ''didn't?''

:[A more detailed plane is shown flying into a curtain of darkness.]
:Captain: *KSSCHHH* [sound of intercom being activated]
:Captain: This is your captain speaking. If you look out the right side of the plane, you'll see, uhh...
:Captain: Folks, this appears to be the end times.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics with color]]
[[Category:Total Solar Eclipse 2017]]

2184: Unpopular Opinions

2022-05-21T00:48:33Z

108.162.250.198: Undo revision 270741 by Explain xkcd server admin (talk)

{{comic
| number = 2184
| date = August 2, 2019
| title = Unpopular Opinions
| image = unpopular_opinions.png
| titletext = I wasn't a big fan of 3 or Salvation, so I'm trying to resist getting my hopes up too much for Dark Fate, but it's hard. I'm just a sucker for humans and robots traveling through time to try to drive trucks into each other, apparently.
}}

==Explanation==
Everybody has their own preferences as to what movies they like and dislike, and when your like or dislike of a movie seems to be different than the majority of people, you could call your preference the "unpopular opinion" because your opinion is the less prevalent one. This often takes the form of "I hate this movie and I don't understand why everybody else seems to like it", but this comic is talking about the opposite form, which it categorizes as less common, namely "I like this movie and don't understand why everybody else seems to hate it." The comic points out that it's relatively common to hate movies others appear to like, but the converse, in which you like a movie others seem to hate, is much harder to find.

To illustrate how hard it is to like a movie everyone else seems to dislike, the comic presents a challenge whereby you 1) identify a movie you definitely like, which 2) came out during your adult life (so it isn't tainted by childhood {{w|nostalgia}}), and which 3) the majority of other people don't like, as measured informally by having a popularity rating below 50% on the {{w|Rotten Tomatoes}} website (a website that aggregates reviews of films). Supposedly you will find it hard to find a movie that meets all three criteria. The rules prohibit a movie that the viewer finds {{tvtropes|SoBadItsGood|"So Bad, It's Good"}} - the enjoyment of the movie must be genuine, for its positive qualities, rather than ironic enjoyment of its negative qualities.

The image in this comic gives an example of this effect, namely the movie ''{{w|Terminator Genisys}}'', the fifth in the {{w|Terminator (franchise)|''Terminator''}} series, released in 2015. This series, about time-travelling killer robots, included the highly rated ''Terminator 2'' (93% on Rotten Tomatoes), while ''Terminator Genisys'' is only 26%.

The title text refers to three movies in the ''{{w|Terminator (franchise)|Terminator}}'' franchise, ''{{w|Terminator 3: Rise of the Machines}}'' (2003), ''{{w|Terminator Salvation}}'' (2009), and ''{{w|Terminator: Dark Fate}}'' (due out later in 2019). The ''Terminator'' movie series has featured both time travel and trucks driving or attempting to drive into people, and Randall apparently finds himself drawn to such movies. He hopes that ''Dark Fate'' will be a good movie, but has low expectations, considering the [https://www.rottentomatoes.com/franchise/terminator less than stellar ratings] of the last 3 movies (69%, 33%, and 26%).

A [https://www.rottentomatoes.com/browse/dvd-streaming-all?minTomato=0&maxTomato=49&services=amazon;hbo_go;itunes;netflix_iw;vudu;amazon_prime;fandango_now&genres=1;2;4;5;6;8;9;10;11;13;18;14&sortBy=release|Rotten Tomatoes search ordered by release date limited to qualifying movies] can help individuals verify the difficulty of finding such movies for themselves.

==Transcript==
:[Ponytail, Cueball, and Megan are all looking at their cell phones. Cueball is in the middle, facing out, holding his phone in both hands, while the two women face towards him with only one hand on their phones. Ponytail is tapping on the phone as shown by small lines over her fingers. they talk to each other, but before that, there is the following text above them:]
:Unpopular ''positive'' opinion challenge:
:Name a movie that...
:(1) you genuinely like (not "so bad it's good")
:(2) came out in your adult life post-2000, and
:(3) is rated below 50% on Rotten Tomatoes.

:Ponytail: Wow, this is harder than I thought.
:Cueball: ...Terminator Genisys?
:Megan: Seriously?!
:Cueball: ''I like time travel, OK??''

[Caption below the panel:]
:When people talk about their "unpopular opinions" about movies, they usually mean hating something everyone likes, but liking something everyone hates is much harder.

==Trivia==
*On xkcd, this Friday comic was replaced already on Sunday by a "disappearing comic", which temporarily was assigned the sequence number 2185. But that was just to prevent the trouble a not numbered comic was having on the xkcd site. It was designed to disappear completely and leave no trace in xkcd's history or archives when the Monday comic, [[2185: Cumulonimbus]], was released. The original comic does also no longer appear in explain xkcd's comic navigation either, and is hence linked here: [[Disappearing Sunday Update]].

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Fiction]]
[[Category:Time travel]]
[[Category:Robots]]
[[Category:Terminator]]

1184: Circumference Formula

2022-05-04T00:35:48Z

108.162.250.198: Undo revision 235751 by X. K. C. D. (talk)

{{comic
| number = 1184
| date = March 11, 2013
| title = Circumference Formula
| image = circumference_formula.png
| titletext = Assume r' refers to the radius of Earth Prime, and r'<nowiki/>' means radius in inches.
}}

==Explanation==
The {{w|circumference}} C of a {{w|circle}} is 2{{w|pi|π}}''r'', where ''r'' is the {{w|radius}} of the circle. [[Randall]] then makes a {{w|Note (typography)|footnote}} about ''r'', using 2. This creates a typographical ambiguity, since a superscript 2 can also be an exponent (as in ''x''2). The comical purpose of this ambiguity is that the formula initially makes an appearance of a mistake and confusion with the formula for the ''{{w|area}}'' of the circle: A = π''r'' 2. If and only if the reader realizes that the superscript text is a reference to a footnote will they understand that the author has in fact supplied the correct formula.

The title text makes a related joke. Randall has used r' (r-{{w|Prime (symbol)|prime}}) and r" (r-prime-prime, typically pronounced as ''r double prime''). The title text can be explained thusly:

Like many symbols, prime has widely differing meanings depending on context. In mathematics prime is often employed to distinguish corresponding components in analogous systems. For example, in a description of a basic physical system, if the velocity of an object is denoted with the variable ''v'', the velocity of that object at time=0 may be denoted with ''v′''. Playing off this use of prime, Randall has selected the radius of {{w|Earth Prime}}, a concept used in speculative fiction with parallel universes and multiple Earths. Earth Prime is our Earth (or at least the Earth from which the protagonists originate).

However, other disciplines use prime to mean other things. In timekeeping and navigations ' denotes minutes (fractions of hours or degrees, respectively) and " denotes seconds (fractions of minutes). In the United States and some other places not using meters to measure distance, ' denotes feet and " denotes {{w|inches}}.

The suggestion of using r' or r" does not cause any mathematical confusion, but using the former to denote the radius of a specific object and the latter to denote a radius using a specific unit of measurement would be highly esoteric. Furthermore, r' and r" can be used in calculus as a method of denoting, respectively, a first derivative and a second derivative. For someone attempting to use the formula and some derivative representing a circle's radius, trouble could result quite easily.

2 These are not intended to indicate the presence of a footn... oh, never mind.

==Transcript==
:Circumference of a circle:
:2πr2
:2The circle's radius

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