explain xkcd - User contributions [en]

3016: Cold Air

2024-11-27T09:17:38Z

141.101.99.105: /* Explanation */

{{comic
| number = 3016
| date = November 25, 2024
| title = Cold Air
| image = cold_air_2x.png
| imagesize = 713x283px
| noexpand = true
| titletext = We also should really have checked that the old water tower was disconnected from the water system before we started filling it with compressed air.
}}

==Explanation==
{{incomplete|Created by a 204 atm COMPRESSED BOT - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
Tornadoes generally create winds of about 40-400 mph [https://www.weather.gov/ffc/fujita] (about 60-640 km/h) which causes damage to buildings. Cueball proposes a method to essentially blow tornadoes away from cities by keeping enough "tornado repelling" air in a tank. It is not clear if the compressed air will be used to "blow away" the whole tornado, to try to exactly counteract the tornado itself (through applied counter-rotation) or to remove the conditions that cause the development of the tornado's system. The last of these is heavily implied, as replacing any troublesome hot and humid air will remove the conditions required to invoke a nascent tornado. Whether this would work is questionable, since it's precisely the mixing of warm and cold air that produces the swirling motion that creates tornadoes. Rather than dissipating the threat, the very act of displacement could create atmospheric mixing and tornado-generating turbulence in its own right.

In a compressed air system, peak pressure is considered about 40 bar [https://www.directindustry.com/prod/kaeser-kompressoren/product-4742-24559.html] (about 500 psi). Cueball proposes keeping the tank at 6 times that pressure to properly counteract the tornado. The title text confirms that at least one tower is a repurposed water tower, which, if using 16 inch pipes as [https://www.waterworld.com/home/article/14071043/the-perfect-pipe is common], would produce much stronger winds than those of the tornado, because flow speed is inversely proportional to the diameter of the pipes and even a "wide" 16 inch pipe is very narrow for this purpose indeed.

The formula for the velocity of a fluid (air is considered a fluid in physics) is V=√(2*P/ρ) where V is the velocity, P is the pressure, and ρ is the density of the fluid. The density of the fluid is given by the formula ρ=P/(RT) for a given constant R and a Temperature T. In this case, ρ is [https://www.wolframalpha.com/input?i=3000psi%2F%280.287kj%2F%28kg+Kelvin%29*21C%29 0.245 g/cm^3] assuming room temperature, meaning the V=√(2*3000psi/ 0.245 g/cm^3)[https://www.wolframalpha.com/input?i=sqrt%282*%283000psi%29%2F%280.245+g%2Fcm%5E3%29%29 =410.9 m/s], which is just under 1500 km/h, almost three times faster than the max speeds of the tornados Cueball is trying to prevent.

In addition, the specification that the air is to be kept dry & cold will almost certainly require the installation of dehumidification & refrigeration systems on the tanks at great expense, since most major North American cities are located near large bodies of water and tornado season (spring) is usually warm and moist (especially for Southern cities such as Atlanta, Birmingham, Chattanooga, etc.). The resulting greenhouse-gas emissions from generating the extra electricity required to run these systems will almost certainly increase mean global temperatures, causing more water to evaporate into the atmosphere, making it even more humid, and therefore more likely that tornadoes will be formed.

Further, pressurised vessels are liable to bursting, an issue harder to mitigate the larger the internal volume. Cueball's proposal would put particularly large ones in the center of dense cities, creating the possibility for further damage. Especially, if the proposal diagram is to be believed, with the tank itself being twice the height of the tallest surrounding buildings (drawn to resemble skyscrapers, so probably tens of stories tall), being elevated high above them upon by base that also dwarfs them, and dominating the area and its skyline.

Finally, tornadoes tend to form in ''sparsely'' populated areas, where structures are few and wind can flow uninterrupted, making his invention's necessity questionable at best. Even if Cueball's air tanks produce winds no faster than a normal tornado, they are now being produced in the centers of heavily built-up areas, significantly increasing the potential for damage.

The result is a quadrupling in damage caused by wind, since now, not only are the tornadoes causing heavy winds, but the tanks — when functioning properly and when malfunctioning — are causing heavy winds too.

In the title text, it is revealed that the water tower they were using to store the compressed air was still plumbed in to the water mains. Given the pressure required for the tower to work properly against tornadoes and the fact that water is nearly incompressible, the pressure from the tower would have been nearly instantly transmitted into the water distribution system. The ''best'' case scenario would have been 'just' to have dangerously highly-pressurised water jetting into sinks, bathtubs and toilet cisterns whenever they were used; more severe consequences could be catastrophic failures of pipes and plumbing.

Using technology to disrupt tornadoes before they form was a plot element in Liu Cixin's novel ''{{w|Ball Lightning (novel)|Ball Lightning}}'', and [https://memory-alpha.fandom.com/wiki/Weather_Modification_Net other works]. In reality, fringe scientist {{w|Prokop Diviš}} (1698-1765) proposed a weather-control machine to disrupt thunderstorms before they form.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball is in front of a diagram of a tornado with a pointer in his right hand. The diagram has arrows flowing from the bottom toward the tornado at the top, and from the tornado toward the rain below it.]
:Cueball: Tornado supercells are powered by the inflow of warm, moist surface air.

:[Cueball is now in front of a representation of his compressed air tank with a PSI of 3000 next to smaller buildings, appearing to be high-rise buildings or skyscrapers, on both sides of the tank.]
:Cueball: Compressed air tanks could produce artificial pools of cold, dry air on demand, disrupting tornado inflow to protect cities.

:[Cueball is in front of a line graph labeled "Wind Damage over Time". Wind damage has spiked constantly after a point on the graph labeled "Giant experimental compressed air tanks installed in the middle of every major city"). In a frame in the top left corner, there is a label:]
:Several years later:
:Cueball: In retrospect, I can see how my plan went wrong.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Tornadoes]]
[[Category:Line graphs]]

Talk:3011: Europa Clipper

2024-11-14T10:57:56Z

141.101.99.105:

I'm not brave enough to actually add an explanation myself, quite yet, but ... I guess this is a reference to the fact(?) that Europa looks a bit like a creme brulee', when viewed from space? https://science.nasa.gov/jupiter/moons/europa/ It does look tasty ... :) [[User:ModelD|ModelD]] ([[User talk:ModelD|talk]]) 12:53, 13 November 2024 (UTC)
:I suspect it's more due to the need to drill through a couple miles of ice to get to the ocean; much like breaking through the sugar crust on a creme broule! [[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 13:16, 13 November 2024 (UTC)

Thank you to the people at 9AM Post things on another website to try and explain XKCD Comics. -Forgotten_Mail {{unsigned ip|172.69.33.177|13:30, 13 November 2024}}

The comically large spoon!!!!!!!!!! I love those. -[[User:Psychoticpotato|P?sych??otic?pot??at???o ]] ([[User talk:Psychoticpotato|talk]]) 16:38, 13 November 2024 (UTC)
: Don't be sucked in! Protect yourself! https://rathergood.com/2017/02/10/spoonguard/ [[Special:Contributions/141.101.99.105|141.101.99.105]] 10:57, 14 November 2024 (UTC)

I think the "Crème brûlée is from France, France is in Europe, the moon is called Europa" connection is a bit of a stretch...?
[[User:Yorkshire Pudding|Yorkshire Pudding]] ([[User talk:Yorkshire Pudding|talk]]) 18:36, 13 November 2024 (UTC)

"only a spoonful" moment 💔 [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 19:20, 13 November 2024 (UTC)

Someone should add a reference to XKCD's previous mention of a Planetary Protection Officer: https://what-if.xkcd.com/117/ [[Special:Contributions/162.158.42.221|162.158.42.221]] 00:09, 14 November 2024 (UTC)

JUICE mentioned!!! cracker ham cheese cracker ham cheese cracker [[User:N-eh|N-eh]] ([[User talk:N-eh|talk]]) 07:31, 14 November 2024 (UTC)

2791: Bookshelf Sorting

2023-06-19T22:01:34Z

141.101.99.105: First draft of explanation, no citations yet, no references, just bare bones and a bit of whimsy

{{comic
| number = 2791
| date = June 19, 2023
| title = Bookshelf Sorting
| image = bookshelf_sorting_2x.png
| imagesize = 425x255px
| noexpand = true
| titletext = Of course, I sort all my bookshelves the normal way, alphabetically (by first sentence).
}}

==Explanation==
{{incomplete|Created by a BOOKSHELF SORTED THE NORMAL WAY - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
Some people sort their bookshelves by color, which is pleasing to the eyes but unhelpful when trying to find a specific book. Randall proposes a much more infuriating way to sort books - to separate each book into its pages and organize them into groups by page number. All the covers are at the left side, being effectively "page 0", then all the page 1s, the page 2s, et cetera. This method, like sorting by color, has no practical use in most situations. It damages the books and makes it much harder to find information.

The comic shows a bookshelf sorted by page numbers, meaning that all books are taken apart into covers and single pages and then everything is sorted by page numbers.

There is a lot of different sized front covers in the left side of the shelf (meaning they start with low numbers on the left).
Afterwards, there is a repeating pattern of taller and shorter pages, with each a page of the same number from a differently sized book.
After a while the first back covers are sorted in, and at the end there is only the last pages of the longest book left, now all uniformly in size.

The title text claims that this is a way of sorting that "book people" hate, even more so than sorting by colour of the cover/spine.
It is not clear if the spine part is thrown away or just not visible, maybe being sorted towards the wall. This would make it a sort of antithesis to the colour sorting, no only is it not sorted by colour, but the spines that usually define the colour sorting are either to the back or fully removed.

Also, these are either books without any frontmatters, or the sorting goes by absolute pagecount, not by numbers printed on pages.

It might be the intent to have "the absolute opposite" of colour sorting and follow this idea ad absurdum.

Sorting by page number has the following drawbacks:
* It is impossible to pick up one specific book quickly in one go.
* It is easy conceptually, but tedious in practice to find a specific page. Going back to the frontmatter question, if they are not sorted separately, it migth be actually very hard to find a page with a specific pagenumber printed as they woudl not necessarily be in one "wave".
* Sorting might vary wildly for the same book in different editions (as it would in coulour-sorting, too, maybe one of the reasons they are unpopular with the mentioned "book people")
* Without a secondary sorting rule, it is unclear in what order the pages of the same number are sorted. Since the height pattern seems repetetive, it seems as if at least the order of books is kept the same, but this is not a necessary feature of the basic premise.

Possible advantages:
* For someone using physical books to look up citations, it might be a quicker search. (Only if front matter is counted separately)
* The block of front covers is a quick, nearly reference card system view of what books are on a particular shelf (Only if front matter count is ignored)
* Just like the colour sorting, possibly this is meant to be an aesthetic, instead of a practical choice of sorting. With the right kind of height distribution of different books, it can be a nice art piece, maybe of a seascape.

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

[A bookshelf is shown. From left to right, there are 11 pairs of covers in different sizes and shades of gray. To the left, one of each pair of covers is arranged with its all the others. Going rightwards, many leaves of paper (wth a similar set of differing heights) lead up to the partner-cover to the last of these initial covers. More paper, for varying amounts, more covers, and repeat until the outermost paired-cover at the end of the shelf.]

Book people hate seeing books sorted by colors, but it turns out they get ''way'' more angry if you sort the pages by number

{{comic discussion}}

Talk:587: Crime Scene

2015-02-25T16:53:37Z

141.101.99.105:

That officer is a fool. I'd say it'd be much more likely to relate to the first ''prime'' number (assuming you ignore 1, as apparently you're supposed to) than the third Fibonacci one, barring any prior incidents that might or might not be attributed to the same killer. Of course, we'd perhaps have to wait until three crime-scenes later to work out which of these patterns our Malevolently Mathematical Mastermind of Murder has memetically manipulated for us... Holy Torii, Batman! (And no wonder the policemen like both donuts and coffee cups... They're the same...) [[Special:Contributions/178.105.100.250|178.105.100.250]] 00:20, 24 May 2013 (UTC)
:The first prime number is -1!!! {{unsigned ip|141.101.104.20}}

" a man (presumably a former Mathnet member" - Not just anyone, the officer calls him George. George Frankly was the main character on the show. Just putting it out there. --[[User:Alcatraz ii|Alcatraz ii]] ([[User talk:Alcatraz ii|talk]]) 22:43, 6 June 2013 (UTC)

You know, this being a wiki and all, you could have added that yourself. Never mind, I've done it for you. [[Special:Contributions/71.201.53.130|71.201.53.130]] 20:42, 20 August 2013 (UTC)

The original Fibonacci problem was formulated about the count of multiplying pairs of rabbits, starting with one pair. So 2 is definitely the 3rd number, not 4th, in that formulation. [[Special:Contributions/108.162.246.5|108.162.246.5]] 22:21, 31 January 2014 (UTC)

off topic:i think this is a homage to [http://www.imdb.com/title/tt1256105/synopsis?ref_=ttpl_pl_syn this] show [[Special:Contributions/103.22.200.222|103.22.200.222]] 09:04, 22 February 2015 (UTC)

I am unsure, but could the use of the word 'Golly' in the title text be a reference to the popular program to run Conway's game of life which goes by the same name? [[Special:Contributions/141.101.99.105|141.101.99.105]] 16:53, 25 February 2015 (UTC)

1465: xkcd Phone 2

2014-12-26T19:41:41Z

141.101.99.105:

{{comic
| number = 1465
| date = December 26, 2014
| title = xkcd Phone 2
| image = xkcd_phone_2.png
| titletext = Washable, though only once.
}}

==Explanation==

This is a followup to [[1363: xkcd Phone]], which debuted the original xkcd phone. Like xkcd Phone "1", this comic parodies modern smartphone advertising with a promotional image for a fictional phone. Like the previous xkcd phone, the comic touts a variety of features which are either pointless, misleading, or physically impossible. They are clockwise, from the top left:

*'''MaxHD: Over 350 pixels per screen''': 350 pixels is not very impressive: Each would be about 0.5×0.5 cm. Even if it implies 350 pixels along the edge this is still less than standard definition TV (PAL gives 576 lines of horizontal resolution). Likely a reference to HD+, FullHD, QuadHD and other marketing expressions for screen resolutions, by which common users are often confused. In [[732: HDTV]] Randall has observered that HD is not an especially high resolution, when compared with computer monitors.
: ''Note:'' Retina display (high pixel density display) for smartphones is 326 pixels per '''''inch''''', not per '''''screen'''''.
*'''Always on Speaker''': An always on microphone is a genuine feature. It allows speech control software such as "Okay Google" or "Siri" to respond without having to be turned on. An always on speaker would be less useful especially if it implies the phone is always making noise.
*'''Blood Pressure reliever''': This appears to be where a real phone would have its front facing camera. This could imply that it's a sharp part that you can cut yourself on, thus '''''relieving''''' your blood pressure, or else implying that the other features of the phone are so frustrating that a feature was required to relieve the users' blood pressure.
*'''Auto-Rotating Case:''' Phones often feature an "auto-rotating screen", meaning that the display switches between portrait and landscape mode depending on its orientation with respect to gravity. But the case is a physical part of the phone, so making a case that did '''not''' "auto-rotate" with the phone would be the real challenge.
*'''Ribbed:''' A reference to ribbed {{w|condom}}s, which are often advertised as superior to standard ones because the texture can be more physically stimulating to the genitalia. Some other objects can be advertised with the word ribbed as well, but mostly in the context where it allows a firmer grip on the device when wet. Since phones are usually not meant to be used wet it is still a fairly useless feature.
*'''Waterproof (inside only)''': Waterproofing is done to the outside to prevent water from getting in, not to prevent water from escaping.
*'''Googleable''': Another non-feature. Advertising as ...able is a way for marketing to add features, without adding features. This may be (for example) a recyclable paper bag: paper is normally recyclable. Any term may be 'googled' so being "googleable" is not an actual feature.
*'''Cheek toucher''': The screen will touch your cheek when making a hand-held phone call.
*'''Cries if lost:''' Actually useful function, for it would help the owner find the cellphone in case it was lost. It refers to people's habit of calling their own cellphones to help find it. It also resembles the first xkcd phone's functions of 'Screaming when falling' and 'Saying hi when lit'.
*'''Bug drawer:''' This is most likely the cover for other ports, though looks like a small drawer, capable of only holding bug-sized items. Possibly a joke on software bugs, which would, being virtual rather than physical, easily fit inside this area. One might also introduce bugs to your phone in this way. May also be a reference to "Phone may attract/trap insects; this is normal" from the original ''xkcd Phone'' comic.
*'''Coin slot:''' In most phones, this would be the charging port. Payphones have coin slots.
*'''Scroll lock:''' A computer key on most keyboards which is practically never used. (Despite [http://www.explainxkcd.com/wiki/index.php/978 a previous xkcd strip] it was not invented by {{w|Steven Chu}}.)
*'''OS by Stackoverflow®:''' [http://stackoverflow.com/ Stackoverflow.com] is a very useful and popular question/answer forum for programmers, and many recent software products probably have benefited from advice given there, so Randall may be giving credit where credit really is due. Or it may be a reference to the rampant problem of code reuse, where programmers use the pre-written code on StackOverflow rather than writing their own, regardless of the fact that the code on StackOverflow may contain bugs or otherwise cause problems for their specific program.
*'''3D Materials:''' All real materials are three-dimensional, so this feature is not special.
*'''Dog Noticer''': Alerts the user to nearby dogs.
*'''FitBit® Fitness Evaluator''': {{w|FitBit}} make wristbands that measure heartrate, count user steps, and act as an aid to planning an exercise program. This comic is published on Boxing Day 2014 and is relevant as Fitbits are a popular Holiday Gift at this time.
*'''Volume and density control:''' A play on words between {{w|volume (disambiguation)|volume}} as in speaker loudness, and {{w|volume}} as in a physical property inversely related to {{w|density}}. Apparently this would allow the user to change the size of the phone (which would indeed be a very useful feature, [[1422: My Phone is Dying|or a very worrying one]]), thus changing the volume and the density. Note that some computer mice have a feature where the user can put weights inside the case to customise the weight and thus affect the density in a different way.
*'''It is washable but only once''' (the title text): The phone can physically be washed, however after the first time doing this the phone will cease to function.

==Transcript==
:[An image of a smartphone. Coming off from it are many labels. Clockwise, from the top left they are:]
:MaxHD: Over 350 pixels per screen
:Always-on speaker
:Blood pressure reliever
:Auto-rotating case
:Ribbed
:Waterproof (interior only)
:Googleable
:Cheek toucher
:Cries if lost
:Bug drawer
:Coin slot
:Scroll lock
:OS by Stackoverflow®
:3D materials
:Dog noticer
:FitBit® fitness evaluator
:Volume and density control

:[Below the phone:]
:Introducing
:'''The xkcd phone 2'''
:A phone for your other hand®

{{comic discussion}}

1429: Data

2014-10-30T10:04:10Z

141.101.99.105: /* Explanation */

{{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'', 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 ''data'' is treated as a collective noun<ref>http://statistics.about.com/od/Glossary/a/What-Is-The-Plural-Of-Data.htm</ref>. 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.'' But beyond this, there is a [http://boards.straightdope.com/sdmb/showthread.php?p=3328463#post3328463 specific longstanding controversy] over whether to use ''a'' or ''an'' with words that start with a non-silent ''h'' sound followed by an unstressed vowel, such as ''historical'' and arguably ''hypercorrection'' in the title text. In many accents of English, when these words take the indefinite article, the article ''an'' is used and the ''h'' becomes silent (this scheme is used in some long-established English texts, such as the King James Bible). In others, the article ''a'' is used and the ''h'' remains pronounced.

This comic complements two of the [http://www.explainxkcd.com/wiki/index.php/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|Randall's]] Hobbies.

This comic also appears to be an example of {{w|Self-irony|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 the panel]
:Cueball: According to this polling data, after Kirk and Picard, the most popular Star Trek character are Data.
:Off-panel character: Augh!
:Annoy grammar pedants on all sides by making "data" singular except when referring to the android.

{{comic discussion}}

[[Category:Language]]