explain xkcd - User contributions [en]

2748: Radians Are Cursed

2023-03-10T20:31:40Z

162.158.90.208: /* Transcript */ facts

{{comic
| number = 2748
| date = March 10, 2023
| title = Radians Are Cursed
| image = radians_are_cursed_2x.png
| imagesize = 394x437px
| noexpand = true
| titletext = Phil Plait once pointed out that you can calculate the total angular area of the sky this way. If the sky is a sphere with radius 57.3 degrees, then its area is 4*pi*r^2=41,253 square degrees. This makes dimensional analysts SO mad, but you can't argue with results.
}}

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

This comic presents a series of Math Facts, appearing to be in a sequential order.

The first fact states that the {{w|unit circle}} has a radius of one, which is precisely its definition. Randall labels this fact as being "normal," complete with a large green checkmark to verify this.

The second fact states that one {{w|radian}} is equal to the length of a circle's radius, which isn't actually the way that the unit is defined. Instead, radians are usually defined as the angle encompassing the arc of a circle equal to its radius. This comic's logic is thus somewhat erroneous at best. Also, while Randall uses the unit circle in the fact's associated diagram, any circle could theoretically be used to show the conventional definition. However, this fact is still labeled as also being "normal."

The third fact states that one radian is equal to 57.3 degrees. The more usual conversion factor between the two units is that pi radians is equal to 180 degrees, though the conversion given by Randall is still indeed true (albeit rounded). This is again labeled "normal."

The fourth and final fact, however, is a questionable application of the {{w|transitive property}}, stating that because it was determined in earlier facts that a radian is equal to the radius of the unit circle (still not entirely correct) as well as 57.3 degrees, then the radius of the unit circle must be equal to 57.3 degrees. This is usually not how degrees are supposed to work in mathematics, and is thus the only fact labeled "cursed" by Randall, hence the title of the comic.

The title text is referring to Phil Plait's claim about the size of the sky, which was published on his blog: http://www.badastronomy.com/bitesize/bigsky.html. Dimensional analysis utilizes the rationale that both sides of an equation need to have the same unit. Radius typically refers to a length, which has SI units of meters. The surface area has SI units of square meters. The units of Phil Plait's "angular area" is as the title text mentions, square degrees, a unit not used in any scientific unit system. Thus the comic's dimensional analysts (not a profession, but instead the adherents of the mathematical technique) are made quite angry by the application of Randall's strange and unconventional logic.

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

:[Title:]
:Math facts

:[A diagram of a circle is shown with radius labeled as “1”]
:The unit circle has a radius of one  ✓ Normal
:[The diagram now has another (unlabeled and lighter) radius at a 57.3 degree angle. The arc between the points where the radii touch the circle is labeled as “1”]
:One radian equals the length of a circle’s radius  ✓ Normal
:[The diagram now is completely unlabeled except for the arc, which is labeled as “57.3°”]
:One radian is 57.3 degrees  ✓ Normal
:[The first diagram is shown; however, the radius is labeled as “57.3°”]
:The unit circle has a radius of 57.3 degrees  X Cursed

{{comic discussion}}

[[Category:Math]]
[[Category:Geometry]]
[[Category:Facts]]
[[Category:Comics featuring real people]]

123: Centrifugal Force

2023-03-09T02:32:12Z

162.158.90.208: /* Trivia */

{{comic
| number = 123
| date = July 3, 2006
| title = Centrifugal Force
| image = centrifugal force.png
| titletext = You spin me right round baby, right round, in a manner depriving me of an inertial reference frame. Baby.
}}

==Explanation==
[[Black Hat]] has strapped {{w|James Bond}} to a centrifuge and claims that the {{w|Centrifugal force|centrifugal}} force will be lethal. Bond objects that there is no such thing, but just {{w|Centripetal force|centripetal}} force. The notion of centrifugal force is a common one, as we experience it whenever we turn. Teachers will initially teach Newtonian mechanics in an inertial frame, and in inertial frames, the centrifugal force is zero. Instead, a body that moves in a circle does so because of a centripetal force (acting towards the center of the rotation). This is a reasonable (and correct) view, but it is a subtle point that many students find hard to grasp, as it seems to contradict their personal experience of centrifugal forces. For the sake of exposition, teachers may claim that "There is no such thing as centrifugal force." This, however, is also a misconception, which is addressed in the explanation below:
;Observers' point of view (Black Hat, us, etc.)
:James Bond is moving in a circle, and is therefore accelerating. The force keeping him there is an inward force of contact against the centrifuge, a centripetal force. Via Newton's {{w|Newton's laws of motion#Newton's third law|third law}}, since the centrifuge is pushing Bond inward, Bond is pushing the centrifuge outward. The centrifuge's material is strong enough not to break under this force, however.
;James Bond's point of view
:In James Bond's frame of reference, Bond is at rest. He is kept there by two forces: the above-mentioned inward force of contact against the centrifuge, and an ''outward centrifugal force''. He feels both forces.

As mentioned in the explanation, as the centrifuge rotates faster, the forces needed to keep him in motion get larger, so the force he feels gets larger. This will eventually kill him. The conclusion will be the same regardless of which frame of reference is chosen.

Teachers of mechanics are well aware of this; however, in introductory expositions, these ideas are often not taught. In theoretical mechanics, one describes the positions and velocities of the particles in a model relative to a frame of reference. This means that a time is chosen to be time 0, and positions are chosen to be (0,0,0), (1,0,0), (0,1,0), and (0,0,1). With these chosen, the position and time of any particle in the system can be described. It is an axiom of Newtonian Mechanics that there exist "Inertial Frames." In an inertial frame, a particle will remain at rest or at a constant speed unless acted on by an external force, and Newton's second law takes a simple form: F = ma. The surface of the Earth approximates an inertial frame. In a non-inertial frame, such as one rotating with a giant centrifuge, or moving with an accelerating vehicle, a particle will accelerate, relative to the frame. Newton's second law, when formed in such a frame, is much more complicated, as it has terms for the linear acceleration of the frame, the angular acceleration of the frame, the centrifugal force, and the {{w|Coriolis force}}. These extra terms are sometimes called "fictitious forces," as they result from the choice of the frame of reference. The mathematics required to describe problems in a non-inertial frame is more sophisticated, and all problems may be solved using an inertial frame. Thus is reasonable that teachers at school level "{{w|lie to children}}" and teach the mechanics in inertial frames.

James Bond was almost killed by a centrifuge in {{w|Moonraker (film)|Moonraker}}. The final statement by Black Hat is that said by {{w|Auric Goldfinger}} in {{w|Goldfinger (film)|Goldfinger}} in response to James Bond's question "Do you expect me to talk?"

The title text is inspired by {{w|Dead or Alive (band)|Dead or Alive's}} famous song from 1985, "{{w|You Spin Me Round (Like a Record)|You Spin Me Round}}."

Randall feels very strongly that the centrifugal force is a real thing. He links to this comic in the first footnote of his [[what if?|What if?]] article [https://what-if.xkcd.com/92/ One-Second Day] and the 6th footnote of [https://what-if.xkcd.com/157/ Earth-Moon Fire Pole], stating that it is a real thing, and that he will go so far as to strap arguers to a centrifuge that he or someone he knows apparently owns.

As can also be seen in the [https://twitter.com/bohacekp/status/531500491180875776/photo/1 footnote on page 132] in his [[what if?#The book|What if? book]], he will even fight you about it. From the book: 
"Furthermore, if you're on the equator, you're being flung outward by a centrifugal force1."
 "1Yes, centrifugal. I will fight you."
 (The article itself is about what happens if you lose all your DNA, so it has not much to do with this "real" force... The sentence is just stating that the actual weight loss from losing all your DNA is similar to the weight loss you would experience by moving from the poles to the equator due to this force.)

==Transcript==
:[James Bond, drawn as Cueball, is strapped to a giant wheel suspended from the ceiling. Black Hat is standing next to two levers.]
:Black hat: How do you like my centrifuge, Mister Bond? When I throw this lever, you will feel centrifugal force crush every bone in your body.
:[Same scene, but a closer shot.]
:Bond: You mean centripetal force. There's no such thing as centrifugal force.
:Black hat: A laughable claim, Mister Bond, perpetuated by overzealous teachers of science. Simply construct Newton's laws in a rotating system and you will see a centrifugal force term appear as plain as day.
:[Closer shot, only Bond's head is visible.]
:Bond: Come now, do you really expect me to do coordinate substitution in my head while strapped to a centrifuge?
:Black hat: No, Mister Bond. I expect you to die.

==Trivia==
*This comic is available as a signed print in the [https://store.xkcd.com/products/signed-prints xkcd store].

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Physics]]
[[Category:Comics featuring Cueball]]
[[Category:Footer comics]] 
[[Category:Comics with xkcd store products]]
[[Category:Fiction]]

2747: Presents for Biologists

2023-03-09T02:31:37Z

162.158.90.208: /* Explanation */ wlink

{{comic
| number = 2747
| date = March 8, 2023
| title = Presents for Biologists
| image = presents_for_biologists_2x.png
| imagesize = 396x353px
| noexpand = true
| titletext = A lot of these are actually non-venomous, but I can see which species you mistook them for. If you pause the crane for a sec I can give you some ID pointers for next time!
}}

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

In this strip, [[Black Hat]] is a supervillain subjecting '{{w|James Bond}}' (portrayed by [[Hairy]], or very like him) to a death trap, similar to [[123: Centrifugal Force]] (presumably Mr. Bond managed to escape in that instance). This time, however, he also has another victim, [[Hairbun]], being subjected to the same device – a pit full of snakes, into which the victims are slowly lowered (upside-down and suspended by just one ankle) entirely at the whim or mercy of the antagonist.

While Bond voices typical defiance at Black Hat's scheme, Hairbun instead gushes over the sight of an unfamiliar snake species within the pit, asking Black Hat to lower her faster before that creature either escapes (there seemingly being very little to prevent any snake escaping the pit) or just moves to the other end of the pit.

The caption reveals that Hairbun is a biologist. For her, the contents of this death trap would be happily considered a suitable birthday present, and apparently even these circumstances don't dampen the experience sufficiently to reduce her interest.

The title text explains how Hairbun has expertly spotted that the supervillain included some less dangerous snakes, probably {{w|Coral snake#North American coloration patterns|in error}}. Ever the professional, she suggests the possibility of her advice to help him avoid these errors in the future. She would need a short stay of execution, to do so, but is apparently not particularly fazed by how things end up immediately afterwards.

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

:[Hairy and Hairbun are hanging upside down from ropes attached to one of their ankles. Underneath them, there is a pit with many snakes. Hairbun is pointing down, while Black Hat to the left is operating a lever.]
:Hairy: You won't get away with this!
:Hairbun: Ooh! Ooh! That one is a new species for me!
:Hairbun: Hey, can you lower me faster? It's getting away!

:[Caption below the panel:]
:There's a surprising amount of overlap between "Good presents for biologists" and "Things villains want to do to James Bond."

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Hairbun]]
[[Category:Biology]]
[[Category:Animals]]
[[Category:Fiction]]

2747: Presents for Biologists

2023-03-09T02:31:22Z

162.158.90.208: /* Transcript */ james bond

{{comic
| number = 2747
| date = March 8, 2023
| title = Presents for Biologists
| image = presents_for_biologists_2x.png
| imagesize = 396x353px
| noexpand = true
| titletext = A lot of these are actually non-venomous, but I can see which species you mistook them for. If you pause the crane for a sec I can give you some ID pointers for next time!
}}

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

In this strip, [[Black Hat]] is a supervillain subjecting 'James Bond' (portrayed by [[Hairy]], or very like him) to a death trap, similar to [[123: Centrifugal Force]] (presumably Mr. Bond managed to escape in that instance). This time, however, he also has another victim, [[Hairbun]], being subjected to the same device – a pit full of snakes, into which the victims are slowly lowered (upside-down and suspended by just one ankle) entirely at the whim or mercy of the antagonist.

While Bond voices typical defiance at Black Hat's scheme, Hairbun instead gushes over the sight of an unfamiliar snake species within the pit, asking Black Hat to lower her faster before that creature either escapes (there seemingly being very little to prevent any snake escaping the pit) or just moves to the other end of the pit.

The caption reveals that Hairbun is a biologist. For her, the contents of this death trap would be happily considered a suitable birthday present, and apparently even these circumstances don't dampen the experience sufficiently to reduce her interest.

The title text explains how Hairbun has expertly spotted that the supervillain included some less dangerous snakes, probably {{w|Coral snake#North American coloration patterns|in error}}. Ever the professional, she suggests the possibility of her advice to help him avoid these errors in the future. She would need a short stay of execution, to do so, but is apparently not particularly fazed by how things end up immediately afterwards.

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

:[Hairy and Hairbun are hanging upside down from ropes attached to one of their ankles. Underneath them, there is a pit with many snakes. Hairbun is pointing down, while Black Hat to the left is operating a lever.]
:Hairy: You won't get away with this!
:Hairbun: Ooh! Ooh! That one is a new species for me!
:Hairbun: Hey, can you lower me faster? It's getting away!

:[Caption below the panel:]
:There's a surprising amount of overlap between "Good presents for biologists" and "Things villains want to do to James Bond."

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Hairbun]]
[[Category:Biology]]
[[Category:Animals]]
[[Category:Fiction]]

1429: Data

2023-03-03T08:26:17Z

162.158.90.208: /* Transcript */ annoy

{{comic
| number = 1429
| date = October 3, 2014
| title = Data
| image = data.png
| titletext = If you want to have more fun at the expense of language pedants, try developing an hypercorrection habit.
}}

==Explanation==
"Kirk vs. Picard" is a debate that many ''{{w|Star Trek}}'' fans engage in — specifically which was a better captain of the {{w|Starship Enterprise|starship ''Enterprise''}} on the TV show. Captain {{w|James T. Kirk}} and {{w|Jean-Luc Picard}} each were captains of the ship in different periods (Kirk was captain of USS ''Enterprise'' (NCC-1701) in {{w|Star Trek: The Original Series|The Original Series}}, while Picard was captain of USS ''Enterprise''-D (NCC-1701-D) in ''{{w|Star Trek: The Next Generation|The Next Generation}}''), but fans argue over who was the "best". Most third-place candidates are pretty distant, resulting in a more multi-faceted debate. [[Cueball]] seems to be looking at results of polling for this ''third'' most popular character.

The humor in this comic stems from the fact that the Latin word ''data'' is a plural form of the word ''datum'' ‘a piece of information’, and that originally English followed Latin's lead and treated ''data'' as plural. However, in more recent English, usage of ''datum'' has faded to the extent that [http://statistics.about.com/od/Glossary/a/What-Is-The-Plural-Of-Data.htm ''data'' is treated as a collective noun]. This usage is becoming increasingly (but not universally) accepted as grammatically correct — the ''Wall Street Journal'', for instance, recently announced that it is moving away from saying "data are," while the ''New York Times''' manual of style allows for both variants depending on usage scenario; ''USA Today'', however, is consistently using ''data'' as a plural ("data are"). Naturally, the purists insist on the form that is correct from the Latin grammar point of view and see "data is" as an example of a subject-verb agreement error. This type of "error" is present in the beginning of the sentence that Cueball is citing ("According to this polling data," while certain traditionalists would hold that the grammatically correct variant would be "According to these polling data").

The second error in the same sentence is due to the fact that {{w|Data (Star Trek)|Data}} is a character from ''Star Trek: The Next Generation.'' Since it is a character's name, when used to refer to the character, "Data" should always be treated as singular.

By reversing the verb agreement in both cases, Cueball is going out of his way to annoy grammatically obsessed people.

The title text suggests the mocking of language pedants/amateur {{w|Grammar Nazi|grammar Nazis}} by {{w|Hypercorrection|hypercorrecting}} one's use of language. The sentence itself is an example of this:
*The general rule is that words starting with a consonant should be preceded by ''a,'' while words starting with a vowel should be preceded by ''an.'' However,
*The letter ''h'' is a special case, since in words like ''honor'' (/ˈɒnəɹ/) and ''hour'' (/ˈaʊəɹ/) the ''h'' is silent so the words actually start with a vowel sound, thus leading to the use of ''an.''
*Beyond this, there is a longstanding controversy over whether to use ''a'' or ''an'' with words that in some accents start with a silent ''h'' and in others they don't (see [http://boards.straightdope.com/sdmb/showthread.php?p=3328463#post3328463 Straightdope]). The [http://www.oxfordlearnersdictionaries.com/definition/english/historical?q=historical Oxford Learner's Dictionary] says about ''historical'': Some speakers do not pronounce the ‘h’ at the beginning of '''historical''' and use ‘an’ instead of ‘a’ before it. This now sounds old-fashioned.
*In the title text [[Randall]] adds the word ''hypercorrection'' to the list that includes ''historical'' and ''history''. In this invented accent, the pronunciation would be "ypercorrection".

This comic complements two of the [[:Category:My Hobby|My Hobbies]] comics [[326: Effect an Effect]] (which discusses the trolling of amateur grammar Nazis) and [[1405: Meteor]] (which mocks pedantry). This comic could also just as well have been labelled as one of Randall's Hobbies.

This comic also appears to be an example of {{w|self-irony}} as the author himself has previously exhibited certain inclination to insist on grammatically strict mode of usage of words loaned from Latin. One such example is the fact that [http://fora.xkcd.com/ xkcd's online discussion forums] are called ''fora'', which is a correct plural nominative form of ''forum'' in Latin.

==Transcript==
:[Cueball reading off a smart phone to someone off-screen.]
:Cueball: According to this polling data, after Kirk and Picard, the most popular Star Trek character are Data.
:Off-screen voice: ''Augh!''
:[Caption below the frame:]
:Annoy grammar pedants on all sides by making "data" singular '''except''' when referring to the android.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Star Trek]]
[[Category:Language]]
[[Category:Pedantic]]
[[Category:How to annoy]]

Talk:1638: Backslashes

2016-02-03T10:07:14Z

162.158.90.208:

It should be noted that this also occurs in almost every programming language where "\" is the escape character. i.e.
print("Hello")
> Hello
print("\"Hello\"")
> "Hello"
print("\\Hello\\")
> \Hello\
Oh, and by the way, isn't this the third comic to mention "Ba'al, the Soul Eater"? Maybe we should start a category. (Others are [http://www.explainxkcd.com/wiki/index.php/1246:_Pale_Blue_Dot 1246] (title text) and [http://www.explainxkcd.com/wiki/index.php/1419:_On_the_Phone 1419].)
[[Special:Contributions/173.245.54.29|173.245.54.29]] 06:14, 3 February 2016 (UTC)
:[[:Category:Ba'al|Did that]] before seeing you comment, so yes I agree. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:47, 3 February 2016 (UTC)

;I don't think the regex is invalid

According to <tt>man grep</tt> you need to specify the <tt>-E</tt> option to use extended regex; without it unescaped parentheses are not interpreted, so they don't need to match.

My - very wild - guess is that it was the command he used to find the line with the most special characters, but I am not confident enough to edit the article (if someone can confirm?). {{unsigned ip|141.101.66.83}}

If it was supposed to do that, it doesn't work. Running it on my bash history matches no lines, and I have lots of special characters in there [[Special:Contributions/197.234.242.243|197.234.242.243]] 07:12, 3 February 2016 (UTC)

Explain it to me like I'm dumb. What is this comic going on about? I think the explanation needs more examples like that hello, above, because that's almost understandable. --[[Special:Contributions/198.41.238.231|198.41.238.231]] 07:47, 3 February 2016 (UTC)
:I agree. But I cannot help either.--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)

This is the third time Randall has mentioned Ba'al the Soul Eater xD [[User:International Space Station|International Space Station]] ([[User talk:International Space Station|talk]]) 08:26, 3 February 2016 (UTC)
:Yes, that was already mentioned a few hours before you comment, see the first comment. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)

After passing the regex through bash, you get <nowiki>\\[[(].*\\[\])][^)\]]*$</nowiki> That is, the literal character \, followed by [ or (, followed by any number of any characters, followed by \, followed by ] or ), followed by any number of characters that aren't ) or ], until the end of the line. [[Special:Contributions/108.162.216.44|108.162.216.44]] 08:33, 3 February 2016 (UTC)
:It sounds like you know what you are talking about. Anyone who can explain it good enough for the explanation, and correct the explanation of the title text if it is wrong to say that it would not work. I have added this as the reason for incomplete. But maybe also examples are needed for people with not programming skills/knowledge. We also enjoy xkcd ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)
For fun:
cat ~/.bash_history | xargs -d "\n" -n 1 -I {} bash -c 'chars="$(echo "$1" | grep -o "[a-zA-Z0-9 ]" | wc -l)"; echo "$(( 100 - $(( $chars * 100 / ${#1} )) )) $1"' _ {} | sort -nrk 1 | less

Outputs your bash_history, ordered by relative gibberishness. This was copied by hand from desktop to mobile, might well have a few typos.--[[Special:Contributions/162.158.90.208|162.158.90.208]] 10:04, 3 February 2016 (UTC)

Talk:1638: Backslashes

2016-02-03T10:06:18Z

162.158.90.208:

Talk:1638: Backslashes

2016-02-03T10:04:34Z

162.158.90.208:

It should be noted that this also occurs in almost every programming language where "\" is the escape character. i.e.
print("Hello")
> Hello
print("\"Hello\"")
> "Hello"
print("\\Hello\\")
> \Hello\
Oh, and by the way, isn't this the third comic to mention "Ba'al, the Soul Eater"? Maybe we should start a category. (Others are [http://www.explainxkcd.com/wiki/index.php/1246:_Pale_Blue_Dot 1246] (title text) and [http://www.explainxkcd.com/wiki/index.php/1419:_On_the_Phone 1419].)
[[Special:Contributions/173.245.54.29|173.245.54.29]] 06:14, 3 February 2016 (UTC)
:[[:Category:Ba'al|Did that]] before seeing you comment, so yes I agree. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:47, 3 February 2016 (UTC)

;I don't think the regex is invalid

According to <tt>man grep</tt> you need to specify the <tt>-E</tt> option to use extended regex; without it unescaped parentheses are not interpreted, so they don't need to match.

My - very wild - guess is that it was the command he used to find the line with the most special characters, but I am not confident enough to edit the article (if someone can confirm?). {{unsigned ip|141.101.66.83}}

If it was supposed to do that, it doesn't work. Running it on my bash history matches no lines, and I have lots of special characters in there [[Special:Contributions/197.234.242.243|197.234.242.243]] 07:12, 3 February 2016 (UTC)

Explain it to me like I'm dumb. What is this comic going on about? I think the explanation needs more examples like that hello, above, because that's almost understandable. --[[Special:Contributions/198.41.238.231|198.41.238.231]] 07:47, 3 February 2016 (UTC)
:I agree. But I cannot help either.--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)

This is the third time Randall has mentioned Ba'al the Soul Eater xD [[User:International Space Station|International Space Station]] ([[User talk:International Space Station|talk]]) 08:26, 3 February 2016 (UTC)
:Yes, that was already mentioned a few hours before you comment, see the first comment. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)

After passing the regex through bash, you get <nowiki>\\[[(].*\\[\])][^)\]]*$</nowiki> That is, the literal character \, followed by [ or (, followed by any number of any characters, followed by \, followed by ] or ), followed by any number of characters that aren't ) or ], until the end of the line. [[Special:Contributions/108.162.216.44|108.162.216.44]] 08:33, 3 February 2016 (UTC)
:It sounds like you know what you are talking about. Anyone who can explain it good enough for the explanation, and correct the explanation of the title text if it is wrong to say that it would not work. I have added this as the reason for incomplete. But maybe also examples are needed for people with not programming skills/knowledge. We also enjoy xkcd ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)
For fun: <nowiki>cat ~/.bash_history | xargs -d "\n" -n 1 -I {} bash -c 'chars="$(echo "$1" | grep -o "[a-zA-Z0-9 ]" | wc -l)"; echo "$(( 100 - $(( $chars * 100 / ${#1} )) )) $1"' _ {} | sort -nrk 1 | less</nowiki> outputs your bash_history, ordered by relative gibberishness. This was copied by hand from desktop to mobile, might well have a few typos.--[[Special:Contributions/162.158.90.208|162.158.90.208]] 10:04, 3 February 2016 (UTC)

526: Converting to Metric

2015-11-21T20:42:04Z

162.158.90.208: /* Length */

{{comic
| number = 526
| date = January 5, 2009
| title = Converting to Metric
| image = converting to metric.png
| titletext = According to River, "adequate" vacuuming systems drain the human body at about half a liter per second.
}}
==Explanation==
Most people will eventually develop an intuitive feel for how big certain measurements are (e.g., how long an inch or a foot is, how much a pound weighs). This comic points out that people who were brought up using the {{w|United States customary units|United States system of customary units}} probably don't have the same intuitive understanding for metric units and attempts to provide some benchmarks for these people. Most of the benchmarks are common sense, highly-useful ones (e.g., if it's 30 degrees centigrade [86 °F], you'd be quite comfortable outside dressed for the beach) but some of the benchmarks are humorous and/or completely useless. Benchmarks include:

===Temperature===
* {{w|Extremes on Earth|Earth's hottest}}: 60⁠°C [140 °F]: The hottest temperature recorded on earth is actually {{W|List_of_weather_records#Heat|"only" 56.7}}. There have been reports of ten-twenty degrees higher (70-80⁠°C) but these measurements are not verified or accepted as world records.
* Various heat waves: {{w|Dubai}} is a city in the United Arab Emirates, and is smack-dab in the middle of an equatorial desert, so their heat waves can get ''hot!''. The southern Unites States will typically be a few degrees hotter than the northern United States simply because it's closer to the equator, but as mentioned they're both above "Beach Weather".
*30°C [86 °F]: A little too hot so perfect for a trip to the beach.
*20°C [68 °F]: Is defined as room temperature in many experimental settings. For some this would feel a little cool. But 25°C [77°] would as mentioned be too warm for room temperature...
*10°C [50 °F]: Definitely wear a jacket. Especially if there is just a little breeze.
*0⁠°C [32 °F]: The freezing point of water (32°⁠F)
*-5 to -10°C: In Moscow -10°C is not really that cold - it can go "spit goes clink" cold in {{W|Moscow#Climate|Moscow}}, whereas -5°C [23 °F] in {{W|Boston#Climate|Boston}} may be very cold...
*-20°C: FuckFuckFuckCold and -30°C - Fuuuuuuuuuuuuck!: This is implied to be basically what some people would say when they step outside at this temperature. In reality, it would be best to keep ones's mouth firmly closed. At -30°C, without taking wind chill into account, exposed skin will feel painful in under a minute and frostbite could begin in as little as ten minutes [http://www.ec.gc.ca/meteo-weather/default.asp?lang=En&n=5FBF816A-1]. The differing statements seem to imply that at -20°C, the user would be saying "fuck" repeatedly, whereas at -30°, the user is incapable of closing their mouth after starting the first "fuck", and so extends it into one long one.
*-40⁠°C: Spit goes "clink": As shown in the drawing your spit would freeze ''before'' it hits the ground. This is the crossing point of the two temperature scales i.e. -40°C = -40 °F.

===Length===
*1 cm [.4 inch] : Width of microSD card and 3 cm - Length of SD card: Refers to the {{w|MicroSD card|memory cards}} used in cell phones, digital cameras, etc.
*12 cm [almost 5 inches]: CD-ROM is a common object so nice to know it is a dozen centimeters.
*14 cm [5 1/2 inches]: Most males would probably exaggerate the size of their penis, but 14–15 cm is very average.
*15 cm [almost 6 inches]: A Bic pen
*80 cm [31 1/2 inches]: A typical doorway is also of standard size. This is barely over the minimum size typically required by codes for buildings [30 inches or 76.2 cm], but more than 50% over the size required for aircraft emergency exits. (It may seem illogical that larger doors are required in buildings than in airplanes, given airplanes are arguably more dangerous. However, there is no real disadvantage to using larger doors in buildings, which are not significantly pressurized, but using larger doors in aircraft would increase the force on the door caused by cabin pressure proportionally.)
*1 m [39.37 inches]: {{w|Lightsaber|Lightsaber blade}}: Refers the weapon used in the {{w|Star Wars}} movie franchise. Canonically, the length of a lightsaber's blade varies greatly depending on the setting of the weapon, but "one meter" is by no means a bad approximation.
*170 cm [5 feet, 7 inches]: {{w|Summer Glau}}: Refers to the height of the actress who portrays the character River Tam on the TV show {{w|Firefly (TV series)|Firefly}}.
*200 cm [6 feet, 6 and 3/4 inches]: Darth Vader: Refers to the height of the main antagonist from Star Wars.
*2.5 m [a little over 8 feet]: Ceiling - of course very much depending on which type of building you are in!
*5 m [a little over 16 feet]: Car length - also very much depending on the car...
*16 m 4 cm: Human tower of Serenity crew: Again, this refers to the Firefly TV show, which takes place mostly on a space ship called Serenity.
**Presumably, if all the crew of Serenity were stacked on top of each other, this would be their combined height.
**The comic depicts four characters from the show standing on top of each other; the bottom figure is the crew's captain, {{w|Malcolm Reynolds}} in his signature coat. Judging from the other drawing of Summer Glau from the volume section, she is standing on top of the captain.
**The other five members of the crew should also be stacked on top of these four to reach the 16m height - giving them an average height of 1.82 m (12 cm more than Summer Glaus height!)

===Speed===
:Here both the SI unit m/s as well as the more used unit kph (km per hour) is given.
*5 kph [3 mph] - 1.5 m/s: Walking at a normal pace
*13-25 kph [8-15 mph]: Jogging to sprinting.
*35 kph [21.75 mph] - 10 m/s: Fastest human: As of 2009, the fastest a human has been recorded to run in a single sprint is actually 45 kph, a record set by {{w|Usain Bolt}}.
*45-55 kph: Both cats and rabbits go much faster than normal people.
*75 kph [46.6 mph] - 20 m/s: Raptor: It's a comic written by [[Randall]], of course a reference to the {{w|velociraptors}} from ''{{w|Jurassic Park (film)|Jurassic Park}}'' was going to be here.
*100 kph - 25 m/s: A slow highway (62 mph).
*110 kph [68.35 mph] - 30 m/s: Interstate (65 mph): Refers to the {{w|Interstate|American highway system}}. (65 mph would actually be only 104.6 kph.)
*120 kph - 35 m/s: Speed you actually go when it says "65": People routinely break the aforementioned speed limit, and the police typically don't mind as long as it's not posing any danger. For the record, 120 kph is 74 mph.
*140 kph - 40 m/s (87-89mph): Raptor on hoverboard: The {{w|hoverboard}} is probably a reference to the ''{{w|Back to the Future Part II}}'', though it's a fairly common trope in older science fiction stories. Randall obviously did a lot of google searching on this subject the week before - see [[522: Google Trends]].

===Volume===
*3 ml: The amount of blood in a fieldmouse. A similar amount is used in comic [[434: xkcd Goes to the Airport]], but instead of a fieldmouse, the measurement of blood is of a churchmouse, an imaginary animal created by Lewis Carroll. Click [[434: xkcd Goes to the Airport|here]] for a more on [[434: xkcd Goes to the Airport|comic 434]].
*5 ml: A teaspoon - a very common measure.
*30 mL: Nasal passages and 40mL - Shot glass: The comic points out that you could just about fill a shot glass using the mucus from your nose. Since shot glasses are usually used for mixed drinks, the comic jokes that this mucus could constitute a new, disgusting drink - and this is depictured in the drawing.
*350 ml: Soda can (this is roughly correct for the cans used in the U.S., which hold 12 fluid ounces; in Europe, soda cans commonly hold 330ml or 500 ml).
*500 ml: Water bottle (this is the also the volume of a European water bottle).
*3 L: Two-liter bottle: Refers to a bottle which contains two liters (in the US usually soda). There is debate as to the reason for the discrepancy in volume. It may be a reference to stereotypical Americans consuming a lot of high-calorie foods and drinks.
*5 L: An adult male has about 5 L of blood in his body (An ''adequate'' vacuuming system could drain this blood out in 10 s - as per the title text!)
*30 L: Milk crate: Refers to a {{w|Milk crate|type of small box}} originally used to transport milk but now often in demand to be used as bicycle basket, storage spaces, etc.
*55 L: Summer Glau: Again, this refers to the actress from Firefly.
*65 L: {{w|Dennis Kucinich}}: An American politician belonging to the {{w|Democratic Party (United States)|Democratic party}}, noted for his relatively strong (for the US) leftist views.
*75 L: {{w|Ron Paul}}: An American politician belonging to the rival {{w|Republican Party (United States)|Republican party}}, noted for his strong rightist views.
*200 L: Volume of refrigerator.
*As shown in the drawing of this part of the comic, the three persons mentioned above - Glau, Kucinich and Paul (summing up to 195 L) - could in principle all fit inside a standard refrigerator. Cueball thus attempts to push them all inside of one - though it would obviously be very uncomfortable for all parties involved to be trapped in such a small space with not much room between them.

===Mass===
*3 g: {{w|M&M's|Peanut M&M}}: A small chocolate candy with a peanut inside
*100 g: Cell phone - this very much depends on the age of the cell phone, and the type etc.
*500 g [1 lb.]: A bottle of water contains 500 ml according to the volume section and thus have mass of 500 g.
*1–3 kg: Different types of laptops. The newest and the best is the lightest...
*5 kg [11 lb.]: {{w|LCD monitor}}: A modern flat-screen-style monitor.
*15 kg: {{w|CRT monitor}}: An older-style, cathode ray tube-based monitor.
**This ends the section on computer screens, which overrode the normal sequence by weight as the next two feline inspired entries are lighter than the two before. This was presumably done so that the reader's eye will be confused or amused at seeing (in the comic's caseless captioning font) CRT immediately followed by CAT in the vertical text column.
*4 kg: Cat and 4.1 kg - Cat (with caption): Refers to the internet's love of putting {{w|Lolcat|captions on cats}}. Usually, this is done in a graphics program, but here the cat is actually physically carrying around his caption. The "with caption" part is most likely a reference to [[262: IN UR REALITY]], where [[Black Hat]] glues captions to cats, after running out of staples.
*60 kg [130 lb.]: Lady - for instance if she is Summer Glau - could be her again depicted in the comic - average weight of an adult woman.
*70 kg [150 lb.]: Dude - here depicted as Cueball who is the average guy, and 70 kg is average weight for an adult man.
*150 kg: Shaq: {{w|Shaq|Shaquille O'Neal}}, a famously tall basketball player.
*200 kg [440 lb.]: Your mom
*220 kg: Your mom (incl. 20 kg of cheap jewelry) and
*223 kg: Your mom (also incl. 3 kg of makeup)
*These last refers to a common type of {{w|Your mom}} joking insult whereby someone insults someone else's mother in a creative way. Here, the comic slyly calls your mom fat, then implies she wears way too much jewelry and finally also almost 7 pounds of makeup. This is a common theme in [http://www.explainxkcd.com/wiki/index.php/Category:Your_Mom xkcd]. (Twenty kg of "cheap" jewelry has several times the volume than 20 kg of gold jewelry, because of the difference in density.)

===Title text===
The title text refers once again to Summer Glau's Firefly character, {{w|River Tam}}, who (after being subjected to a long series of medical experiments) is severely mentally ill and often comes out with macabre — though scientifically accurate — pronouncements.

==Transcript==
:'''Guide to Converting to Metric'''

:[There are five frames with tables for different units. Between the two upper frames is the following text:]
:The key to converting to metric is establishing
:new reference points. When you hear "26°C",
:instead of thinking "That's 79°F" you should think,
:"that's warmer than a house but cool for swimming."
:Here are some helpful tables of reference points:

:[The frame to the left of the above text:]
:Temperature:
:{| class="wikitable"
|60°C||Earth's hottest
|-
|45°C||Dubai heat wave
|-
|40°C||Southern US heat wave
|-
|35°C||Northern US heat wave
|-
|30°C||Beach weather
|-
|25°C||Warm room
|-
|20°C||Room temperature
|-
|10°C||Jacket weather
|-
|0°C||Snow!
|-
| -5°C||Cold day (Boston)
|-
| -10°C||Cold day (Moscow)
|-
| -20°C||Fuckfuckfuckcold
|-
| -30°C||Fuuuuuuuuuuck!
|-
| -40°C||Spit goes "clink"
|}
:[Next to the last three entries we see Cueball spitting on the ground. The spit bounces.]
:Cueball: Ptoo
:Spit: Clink!

:[The frame to the right of the above text:]
:Length
:{| class="wikitable"
|1 cm||Width of microSD card
|-
|3 cm||Length of SD card
|-
|12 cm||CD diameter
|-
|14 cm||Penis
|-
|15 cm||BIC pen
|-
|80 cm||Doorway width
|-
|1 m||Lightsaber blade
|-
|170 cm||Summer Glau
|-
|200 cm||Darth Vader
|-
|2.5 m||Ceiling
|-
|5 m||Car-length
|-
|16 m 4 cm||Human tower of Serenity crew
|}
:[To the right of the table is a human tower of four of the people from the Serenity crew. The head of the upper person is right below the first entry.]

:[The frame below to the left:]
:Speed
:{| class="wikitable"
|kph|| m/s||
|-
|5||1.5||Walking
|-
|13||3.5||Jogging
|-
|25||7||Sprinting
|-
|35||10||Fastest human
|-
|45||13||Housecat
|-
|55||15||Rabbit
|-
|75||20||Raptor
|-
|100||25||Slow highway
|-
|110||30||Interstate (65 mph)
|-
|120||35||Speed you actually go when it says “65”
|-
|140||40||Raptor on hoverboard
|}

:[The frame below in the middle:]
:Volume
:{| class="wikitable"
|3 mL||Blood in a fieldmouse
|-
|5 mL||Teaspoon
|-
|30 mL||Nasal passages
|-
|40 mL||Shot glass
|-
|350 mL||Soda can
|-
|500 mL||Water bottle
|-
|3 L||Two-liter bottle
|-
|5 L||Blood in a human male
|-
|30 L||Milk crate
|-
|55 L||Summer Glau
|-
|65 L||Dennis Kucinich
|-
|75 L||Ron Paul
|-
|200 L||Fridge
|}
:[Next to the entry on nasal passages and shoot glass (starting one entry higher and finishing one entry lower) are the following text:]
:So, when it's blocked
:the mucus in your
:nose could about
:fill a shot glass.
:[Below this text is a drawing of a mucus filled shot glass.]
:Related: I've
:invented the
:worst mixed
:drink ever.
:[Below this next to the four last entries we see Cueball shoving Summer Glau, Dennis Kucinich and Ron Paul into an open fridge. Above the fridge in a loosely drawn ellipse are the following text:]
:55+65+75<200

:[The frame below to the right:]
:Mass
:{| class="wikitable"
|3 g||Peanut M&M
|-
|100 g||Cell phone
|-
|500 g||Bottled water
|-
|1 kg||Ultraportable laptop
|-
|2 kg||Light-medium laptop
|-
|3 kg||Heavy laptop
|-
|5 kg||LCD monitor
|-
|15 kg||CRT monitor
|-
|4 kg||Cat
|-
|4.1 kg||Cat (with caption)
|-
|60 kg||Lady
|-
|70 kg||Dude
|-
|150 kg||Shaq
|-
|200 kg||Your mom
|-
|220 kg||Your mom (incl. cheap jewelry)
|-
|223 kg||Your mom (also incl. makeup)
|}
:[Next to the entries of cat and cat (with caption) are two drawings of cats. The second one has a caption across its chest.]
:Cat (with caption): Mrowl?
:[Below this and next to the lady and dude entries (and the Shaq entry) are drawings of Megan and Cueball.]

{{comic discussion}}
[[Category:Charts]]
[[Category:Comics featuring real people]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Velociraptors]]
[[Category:Your Mom]]
[[Category:Firefly]]