explain xkcd - User contributions [en]

3176: Inverted Catenaries

2025-12-13T13:05:36Z

Zagorath: /* Explanation */ clarify the tyre changes are on cars

{{comic
| number = 3176
| date = December 3, 2025
| title = Inverted Catenaries
| image = inverted_catenaries_2x.png
| imagesize = 317x317px
| noexpand = true
| titletext = Some tires are marketed as 'all-shape tires,' but if driven in a climate with both inverted catenary falls and triangle falls, they wear out really fast.
}}

==Explanation==
{{incomplete|This page was created BY A TRAPEZOIDAL WHEEL. Don't remove this notice too soon.}}

During the winter, in snowy areas, people may replace their car's summer or all-season tires with winter tires made specifically for the cold environment. In this comic, instead of snow, rounded shapes called inverted {{w|Catenary|catenary curves}} fall from the skies. On a plane covered in inverted catenaries all the same size, square wheels whose side length matches the arc length of the catenary [https://mathtourist.blogspot.com/2011/05/riding-on-square-wheels.html are capable of rolling smoothly], contrary to how they would act on a normal road. People have made real tracks demonstrating this. Regular wheels would cause a significantly bumpier ride on this terrain, so Cueball plans to swap them out with {{w|square wheel}}s to better suit the season.

Note, however, that this assumes the catenaries are arranged periodically with no spacing between them, fully cover the surface, and are consistent in shape and orientation. The orientation would also restrict the direction of travel, effectively meaning your vehicle would be traveling on rails. Changes in direction could be managed using catenaries whose arc length was consistent but whose segment length varied, with the variations in vertical size being accommodated by vehicles' suspension systems. Letting the direction changes be controlled by drivers (e.g. branching roads) would require complex 3D road surface shapes.

The title text mentions all-shape tires (as a play on all-season tires), which are advertised to supposedly fit any shape road. However, different shapes would require very different wheels; for example, falling triangles would form a sawtooth road, for which one would optimally use wheels pasted together from pieces of an equiangular spiral. The all-shape tire is said to wear out very quickly like low quality all-season tires used to. (The best modern all-season tires perform better than the average winter tire and have a 62k mile warranty.)

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[Megan and Cueball are walking together as inverted catenary curves fall from the sky (presumably from an "inverted canary tree"). A few have landed in a regular formation, all flat-side down and evenly spaced, with some touching each other.]
:Cueball: Oh wow, the first inverted catenary fall of the year!
:Cueball: Time to swap out my all-season tires for square ones.

{{comic discussion}}<noinclude>
[[Category:Weather]]
[[Category:Geometry]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]

Talk:1524: Dimensions

2015-05-15T22:38:59Z

Zagorath: unnecessary nitpicking re: where the planes are defined

This almost seems to be making fun of the frivolity with which people discuss the existence of multiple dimensions without realizing what that actually means. Anyone else get that feeling?

Reminds me of http://xkcd.com/417/ and http://en.wikipedia.org/wiki/Patema_Inverted which make fun of dimensions too. {{unsigned ip|108.162.230.59}}
:Great - I will add 417. please sign you comment with <nowiki>--~~~~</nowiki> ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 07:57, 13 May 2015 (UTC)

My first thought about Title Text was that moving sideways (standard x or y axis) would be bad, but not as bad as moving upwards (standard z axis). Z direction would be my least favourite! --[[Special:Contributions/141.101.104.57|141.101.104.57]] 08:20, 13 May 2015 (UTC)
:You're thinking that from an incredibly geo-centric point of view. There is no reason that the three axes would be defined in absolute terms in terms of the surface of the Earth. Indeed, even if we *did* choose to define the three spacial dimensions relative to something to do with Earth, it would seem logical to me that the best way to do that would be to define the X-Y plane as the plane of Earth's orbit around the Sun. In that case, unless you happened to be located at 23.5 degrees latitude, travelling in the Z direction would *not* be travelling perpendicular to the surface of the Earth, which is presumably to what you were referring in your comment. --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 22:38, 15 May 2015 (UTC)

The explanation looks more and more like a discussion. Four dimensions or eleven? I see that string theory "predicts 10 or 26 dimensions" (http://en.wikipedia.org/wiki/Spacetime). I think someone (but not me) should rewrite the discussion in a more comprehensive way.[[User:Jkrstrt|Jkrstrt]] ([[User talk:Jkrstrt|talk]]) 08:35, 13 May 2015 (UTC)

We might had a link to the 2 what-if related to move steadlily in one direction : http://what-if.xkcd.com/135/ and http://what-if.xkcd.com/64/ {{unsigned ip|188.114.101.12}}

Isn't the alt text a reference to the fact that a cartoon only has two physical dimensions? That's how time can be in his top three. [[Special:Contributions/141.101.99.113|141.101.99.113]] 09:09, 13 May 2015 (UTC)

"Being pushed in one of the other directions could be lethal, if you where pushed hard enough against a rock, over a cliff or in front of a truck..."
Being pushed in the dimension of time is also ultimately fatal though. Push someone through time for long enough and they'll certainly die. [[Special:Contributions/141.101.92.8|141.101.92.8]] 09:20, 13 May 2015 (UTC)

Why the hang up on fixed coordinate systems even though there isn't even a practical way to establish one. (To the best of my knowledge distance can only be measured relative to some object.) it's more likely that the top three dimensions would be along the lines of North/South, East/West and time which is a much more practical point of view.--[[Special:Contributions/108.162.237.183|108.162.237.183]] 11:32, 13 May 2015 (UTC)

''So if it is in the top three out of four, it must be number one...''.
I don't agree. What if Randall would hate going to Zazane galaxy or Ottzello galaxy (X axis), but wouldn't mind going to Xanthrus spiral or Rizoku galazy (Y axis) [http://vignette4.wikia.nocookie.net/spore/images/6/61/INTERGALACTIC_MAP-2.png/revision/latest?cb=20100616044044]. [[Special:Contributions/108.162.238.144|108.162.238.144]] 13:50, 13 May 2015 (UTC)
:The argument would be that this is an arbitrary/anthropocentric classification of X, Y and Z that the universe neither confirms nor denies as the 'true' direction of the three dimensions (which can be in any direction, so long as each is perpendicular to the two others, in a Euclidean sense).
:(And personally. as opposed to the current description. I tend to think of x/y as the horizontal plane and z as vertical motion (up or down, depending on utility), in everyday use, although I'm flexible and will subscribe to one or other standard (and handedness of unit directions!) when dealing with other modelling systems. It's all easily convertible-between.) [[Special:Contributions/141.101.99.79|141.101.99.79]] 17:31, 13 May 2015 (UTC)

I was going to say that if we think of three dimensions simplistically as length-width-height, it might make sense for someone to have a least-favorite spatial dimension--maybe width, since we're always fighting increases in that one. But, I REALLY like the idea above that time would be in the "top three" dimensions for a TWO-dimensional comic-strip character! (Note that Randall plays with this in the Wired comic series linked above, noting that in a comic strip, a small movemement indicates movement through space, but a large one--like between panels--indicates time: see panel #15 in the series) Clever and Randall-esque idea!! I suggest adding this idea to the main text and taking out some of the other discussion around this point.[[User:Jv|Jv]] ([[User talk:Jv|talk]]) 16:32, 13 May 2015 (UTC)

Could it be that the title text is purely playing with words, as in any list of length n (4 dimensions in the world of the comic), one can only have n-1 favourites, so Cueball can only have a top / favourite 3? [[User:Mb|Mb]] ([[User talk:Mb|talk]]) 20:06, 13 May 2015 (UTC)

"Moving forward in time will also eventually be lethal by causing old age, ... But it is only possible to avoid these dangers by sidestepping them in one of the three spatial dimensions." - Wait! I can sidestep '''death'''? AWESOME! [[User:Djbrasier|Djbrasier]] ([[User talk:Djbrasier|talk]]) 20:09, 13 May 2015 (UTC)

The explanation says his favourite co-ords could still be x,y and z. Shouldn't that really by r, phi, theta since that's the best system for a spherical Earth? Also, I don't think you need to mention special relativity, even in classical physics you consider time to be the fourth dimension, you just lack a co-ordinate transformation between space and time. [[Special:Contributions/141.101.98.193|141.101.98.193]] 15:22, 13 May 2015 (UTC)

Does the statement: “pushed inexorably forward through time” not strike anyone as important to discuss and explain? A book by Dan Falk describes the ramifications were one able to move volitionally through time: http://tinyurl.com/l2btjfd.

The Greeks held that time flowed like a river through the present from the past. Others (?) suggest that time flowed from the future into the present. Randall poses that we are pushed forward through time. Who or what does the pushing? With what purpose? To what end?

Pushing suggests we’re unwilling to go forward. But so does pulling. Pulling, by the way, might imply gravitational forces at work. However, those almost never end well. [[User:Run, you clever boy|Run, you clever boy]] ([[User talk:Run, you clever boy|talk]]) 14:30, 14 May 2015 (UTC)

;time

I was surprised nobody mentioned Randall's most famous comic about [[Time]] (which this comic reminded me of a little bit). [[User:WhiteDragon|WhiteDragon]] ([[User talk:WhiteDragon|talk]]) 23:30, 14 May 2015 (UTC)

I love how the title text seems to imply that Randall has a least favorite space-dimension. The three space dimensions are arbitrarily assigned (they are orthogonal to each other but not absolute in relation to anything) so it's like he has a grudge against a completely arbitrary direction.[[Special:Contributions/108.162.216.113|108.162.216.113]] 03:20, 15 May 2015 (UTC)

Talk:1520: Degree-Off

2015-05-04T15:15:12Z

Zagorath: pestilence?

I assume "''Your'' field gathered in the desert to create a new one." refers to the Manhattan Project? {{unsigned ip|173.245.50.74}}
:Yes [[User:Jachra|Jachra]] ([[User talk:Jachra|talk]]) 06:52, 4 May 2015 (UTC)

Chem wants absolutely no part of this conversation. [[User:Jachra|Jachra]] ([[User talk:Jachra|talk]]) 06:52, 4 May 2015 (UTC)

The Four Horsemen of the Apocalypse are: Conquest, War, Famine, and Death. Is she claiming that her heros have conquered death? [[User:Capncanuck|Capncanuck]] ([[User talk:Capncanuck|talk]]) 06:58, 4 May 2015 (UTC)
: Yeah I didn't get that either. The description as it stands now seems to be implying one of the four horsemen is pestilence, but that's not what my Google search turned up… --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 15:15, 4 May 2015 (UTC)

Pestilence [[Special:Contributions/173.245.56.176|173.245.56.176]] 07:10, 4 May 2015 (UTC)

also a possible reference to: https://xkcd.com/435/ ? {{unsigned ip|141.101.75.101}}

The stamp collecting quote is from Ernest Rutherford, not Richard Feynman. {{unsigned ip|141.101.70.43}}

1052 also compares degrees --[[Special:Contributions/141.101.104.12|141.101.104.12]] 08:36, 4 May 2015 (UTC)

My assumption was that Cueball was giving a long and possibly rambling talk about physics starting with an anecdote about Feynman and ending with one about Rutherford. I didn't consider the quote to be wrongly attributed therefore. {{unsigned ip|141.101.99.71}}

Please be aware that the proper way to link to wikipedia is to use [[Template:w]].--{{User:17jiangz1/signature|10:01, 04 May 2015}}

This may be Randall's indirect way of saying what he thinks of the anti-vaxxers. --[[User:RenniePet|RenniePet]] ([[User talk:RenniePet|talk]]) 10:49, 4 May 2015 (UTC)

Does the "killing Pestilence" thing also refer to ''Good Omens'' (co-authored by Pratchett), where Pestilence retired in 1936 "mumbling something about penicillin"? Homusubi

Isn't the comment about vaccines kinda reaching? I don't really see any evidence, even implied, that this comic is referencing the anti-vaccine movement in any way. --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 13:23, 4 May 2015 (UTC)
:I agree that the anti-vaxer comments are out of place. I don't think they should be included as part of the explanation. [[User:Bmmarti3|Bmmarti3]] ([[User talk:Bmmarti3|talk]])

Isn't the biologist talking in the title text? And isn't biology considered a squishy science? I think the title is directed at the physicist, telling him to get harder skin because he's so easily hurt emotionally. [[User:YourLifeisaLie|Yourlifeisalie]] ([[User talk:YourLifeisaLie|talk]]) 14:13, 4 May 2015 (UTC)

I rather doubt that the CAPS in the title text are referring to Pratchett's figure DEATH. In my opinion, the talking-in-CAPS is just meant to infer (further) SHOUTING on the part of the biologist, since she is shouting in the last panel as well. There is no indication whatsoever that the title text should be spoken by anyone other than the biologist herself.[[Special:Contributions/141.101.104.180|141.101.104.180]] 14:20, 4 May 2015 (UTC)thd

Talk:1520: Degree-Off

2015-05-04T13:23:47Z

Zagorath: Vaccines?

Talk:1442: Chemistry

2014-11-06T13:24:36Z

Zagorath: I sans-serif

:"I" would have two in Randall's system as a sans-serif element, and four as a serif element. [[Special:Contributions/108.162.249.202|108.162.249.202]] 00:51, 4 November 2014 (UTC)

::The crossbar on "I" is actually not a serif, it's a part of the letter. Some popular sans-serif fonts that have a crossbar on "I" include Tahoma and Verdana. --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 13:24, 6 November 2014 (UTC)

What is the force that holds the two or three glyphs of an atom together called? How many bonds does the i's dot in Ti have? Ann how dangerous is comic sans cheMStry? [[Special:Contributions/141.101.104.39|141.101.104.39]] 06:52, 3 November 2014 (UTC)
:The letter i can only form one bond, as the other side is bonded with its dot. This is pretty basic chemestry![[User:Maplestrip|Maplestrip]] ([[User talk:Maplestrip|talk]]) 08:20, 3 November 2014 (UTC)

::Ok. Let's look at something advanced. Fe. Os. {{w|Ununtrium|Uut}}. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 12:20, 3 November 2014 (UTC)

Presumably hydrocarbon chains are still supported, albeit with hydrogens forming the backbone in a zip-like arrangement. You'd need phosphorous on the end, with a sans serif valence of 1. [[User:SleekWeasel|SleekWeasel]] ([[User talk:SleekWeasel|talk]]) 08:09, 3 November 2014 (UTC)

I believe he is making fun of incompetent chemistry students. I've seen some draw CH4 as C-H-H-H-H, i.e. according to some random and weird rules that have nothing to do with chemistry. - This comic proposes an equally nonsensical new paradigm. - Aeneas, 3rd November 2014, 10:01 CET

The crystalline structure is not like real-life crystalline carbon (neither diamond nor graphite). I removed that but someone should add a bit about it.[[Special:Contributions/141.101.99.39|141.101.99.39]] 11:48, 3 November 2014 (UTC)

Old English Krypton is particularly hazardous and may explode on contact. Dark matter is composed entirely of cursive script elements. [[User:DivePeak|DivePeak]] ([[User talk:DivePeak|talk]]) 12:01, 3 November 2014 (UTC)

"Mydrane" is a trade mark for a company that markets miscellaneous medical supplies. "Hydrane" is a process for coal gasification by hydrogenation, producing ideally mostly light hydrocarbon gases (mostly methane) and a minimum of liquid products. Not clear whether either is relevant here.[[User:Taibhse|Taibhse]] ([[User talk:Taibhse|talk]]) 12:29, 3 November 2014 (UTC)
::Hydrane is probally relevant. The real Mydrane almost certainly isn't. However, two other words come to mind; Mydriasis (the dialation of the pupil) and Myopia (near-sightedness), which could be what was happening to us Chemistry geeks when we first saw that. Also, the "compound" he claims to be Mydrane does somewhat resemble a pair of eyes or a pair of glasses. -[[Special:Contributions/173.245.48.137|173.245.48.137]] 17:42, 3 November 2014 (UTC)

Amount vs. number.
In the explanation: "the formation of bonds between elements often relies on the amount of valence electrons an element has." Should read, "the formation of bonds between elements often relies on the NUMBER of valence electrons an element has…"

-Avenue

It would be a very interesting exercise to invent a new set of symbols that WERE accurate using this system.[[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 12:47, 3 November 2014 (UTC)

I don't know how relevant this is, but Hydrogen does exist in a metallic phase unde rhigh pressure and temperatures. It's liquid, though, and not crystalline. Also, C2H does also exist, but as a very unstable radical (basically an Acetylene Radical) which seems to be found in space. I have NO idea where Mydrane comes from. There are a lot of Hydrogencompounds ending with -ane (Borane, Silane, Methane), but no idea how this applies here. --[[Special:Contributions/108.162.231.188|108.162.231.188]] 14:21, 3 November 2014 (UTC)

Question: does N(itrogen) only have two bonds, or are those angles a different kind of bond (perhaps ionic vs covalent)? If so, tungsten (W) would be interesting, for a start... (In fact, going though the elements in my head, from the monoglyph elements it would be the most complex under this system. The diglyphs might give Meitnerium (Mt... but was that previously Une as a systematic triglyph?) or Thulium (Tm) some interesting qualities, depending on how the system actually works. Triglyphs are always intended to be replaced, so I think those are moot.
:Wow, is this a serious question or are you just trolling for conspiracy nuts? Of course the conspiracy theorists will tell you that before the invention of printing all the angles were curves, and they were compressed to tight angles to make blocks of movable type smaller and cheaper. Reputable experimental chemists, however, have reported that the bonds between two tungstens is stronger than between two uraniums and we can attribute the difference to the angles. It is fairly evident that right angles (e.g. at the upper left corners of "F" and "P") are essentially inert, and it appears that bond strength increases as the angle becomes more acute. Opposing angles (e.g. "K") seem to Kancel each other out. This is still a very contentious topic![[User:DivePeak|DivePeak]] ([[User talk:DivePeak|talk]]) 05:09, 4 November 2014 (UTC)

As for symbols that ''are'' accurate, there are a number of systems. Hydrogen is represented on the "gold discs" on the Voyager spacecraft (as a starting key to easily decode other information on there) but without a complete overhaul of a system, I'd imagine ''no'' advanced civilisation will have started out with "let's show it how it actually works" (accurately, and without elements such as phlogiston creeping in!) before giving arbitrary names. Electron-orbital diagrams probably work well, though, for some things. And something that reveals the (for example) pi-bonds works better in combinatory diagrams. I think. It's been a while since I did any serious chemistry.[[Special:Contributions/141.101.99.112|141.101.99.112]] 14:41, 3 November 2014 (UTC)

Oxygen has 6 valence electrons, not two. It forms two bonds because it's got room for two more. [[Special:Contributions/108.162.216.105|108.162.216.105]] 16:49, 3 November 2014 (UTC)

Could Mydrane be My Dr -ane where -ane is the common ending for an alkane. My Dr = CCH...which could be Cape Code Healthcare? ~~rbnm

I wonder how many bonds the capital letter "I" would have-- two or four? Seeing as how Randall writes it in this comic, I'm guessing two. Also, would it be possible for carbon to bond with itself ad infinitum in a chain which looks like the teeth on a zipper ("C", upside-down "C", and so on)? [[Special:Contributions/108.162.238.177|108.162.238.177]] 00:29, 4 November 2014 (UTC)
::Yes, Carbon can form very long chains, and also carbon rings (but only with an even number of carbon atoms).[[User:DivePeak|DivePeak]] ([[User talk:DivePeak|talk]]) 04:23, 4 November 2014 (UTC)
:::Assuming that you're talking Comic Universe, I don't see why it ''can't'' be an odd number of carbons in a ring. Even if we're forced to bend round a ...∩U∩U... sort of thing (only end-connected, between characters, not end-snuggled, IYSWIM) you can have one that bends round outside of the plane of the page similar to a mobius strip and could still 'zipper' in a closed circuit with an odd number.
:::IRL, of course, there's {{w|Cyclopentane}} and {{w|Cyclopropane}} (3- and 5-carbon rings), among others, and {{w|Cycloundecane}} (11-carbon saturated ring, with an irregular and aperiodic "wiggle" around the circuit) shows one way that the Fictional Cyclocarbon could (just with a greater angle of bond between successive carbons, and no hydrogens involved) work with odd numbers. [[Special:Contributions/141.101.99.112|141.101.99.112]] 07:56, 5 November 2014 (UTC)
::::My bad - I thought the comic universe was only two dimensional and it would have to be an even number. I need to upgrade my screen! [[User:DivePeak|DivePeak]] ([[User talk:DivePeak|talk]]) 02:51, 6 November 2014 (UTC)

Me is not the designation of two carbon chains. Methane is CH4. [[Special:Contributions/108.162.221.147|108.162.221.147]]rbnm

Talk:1417: Seven

2014-09-05T12:12:13Z

Zagorath: continents

Guacamole = 7-layer dip ingredient
[[Special:Contributions/108.162.215.81|108.162.215.81]] 05:08, 5 September 2014 (UTC)Anonymous XKCD reader

Seventh Seal more likely to be a reference to Book of Revelation (I think he's brought it up before?) or the film? [[Special:Contributions/199.27.133.96|199.27.133.96]] 05:17, 5 September 2014 (UTC)

Arctic Ocean is one of the modern Seven "Seas" of the world.
Green is the 4th color of seven in the Arthur Hamilton song "I Can Sing a Rainbow".

I guess the title text is a play on the fact that the dwarves in the new Snow White (2001) movie are called Monday, Tuesday, ... That is the connection between Snow White dwarves and days of the week. The filmmakers decided to intermix sets of seven in the first place. Sebastian --[[Special:Contributions/108.162.254.90|108.162.254.90]] 06:27, 5 September 2014 (UTC)

There could be a pattern with order.

*Sneezy: 1st dwarf of the seven dwarves in Snow White.
*Phylum: 2nd rank in the Seven Taxonomic Ranks
*Europe: 3rd continent of the world
**The list on the page needs to be fixed to show Europe third. --[[Special:Contributions/141.101.99.213|141.101.99.213]] 11:15, 5 September 2014 (UTC)
*Sloth: 4th sin of the Seven Deadly Sin
*Guacamole: 5th Layer in a 7 Layer Bean Dip
*Data Link: 6th Layer in the OSI Model
*Collosus of Rhodes: 7th Wonder of the Ancient World

*Monday: 1st Day of the Week (American).
*Arctic: 2nd ocean in the modern Seven "Seas" of the world.
*Wellesley: 3rd college of the Seven Sister colleges
*Green: 4th color in the Arthur Hamilton song "I Can Sing a Rainbow".
*Electra: 5th sister of the Pleiades, the Seven Sisters.
*Synergize: 6th Habit in the Stephen R. Covey self-help book "Seven Habits of Highly Effective People".
*Seventh Seal: 7th Seal of the Seven Seals in the Book of Revelations

The Pleiades is Randall's favorite constellation. [[Special:Contributions/108.162.237.161|108.162.237.161]] 08:40, 5 September 2014 (UTC)

It sure is nice seeing the explanation getting more refined and complete every time I visit... [[Special:Contributions/103.22.201.168|103.22.201.168]] 10:37, 5 September 2014 (UTC)

I've always been told there are only six continents. North America and South America are one continent. The seventh continent sometimes refers to this gigantic area filled with plastic rubbish in the Pacific Ocean. [[Special:Contributions/108.162.229.143|108.162.229.143]] 11:47, 5 September 2014 (UTC)
: See here: https://www.youtube.com/watch?v=3uBcq1x7P34 But no one talks about the Great Pacific garbage patch as a continent. 7 continents is the most common model, with some (mainly Latin Americans) considering the Americas a single continent. Some others consider Eurasia a single continent (personally that's what I prefer, it makes the most sense). --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 12:12, 5 September 2014 (UTC)

Guacamole may also be a reference to a famous joke which made the rounds about 15 years ago, where somebody had compared the 7 layers of the OSI network model to Taco Bell's 7-layer burrito. Guacamole was the 5th layer, which lends credence to this idea. It's still available on the WayBack Machine: http://web.archive.org/web/19990826193318/http://www.europa.com/~dogman/osi/ [[Special:Contributions/108.162.219.151|108.162.219.151]] 11:59, 5 September 2014 (UTC)

Talk:1409: Query

2014-08-18T10:20:42Z

Zagorath: XKCD not displaying this comic

----
I assume the Cueball sitting on the box is being accused of being Hairy. I'd say no. [[User:Markhurd|Mark Hurd]] ([[User talk:Markhurd|talk]]) 07:26, 18 August 2014 (UTC)

Is there any particular point Randall would be making where 2 females and only one male, out of 5 each, have watch porn in the last half day? [[User:Markhurd|Mark Hurd]] ([[User talk:Markhurd|talk]]) 07:26, 18 August 2014 (UTC)
:I wasn't sure about one of those 'females', because of the various visual cues.
:What do we know/can assume about the figures? From Left to Right...
:Dark-haired ponytail and mobile phone, on own: *above 30*, not high-earning, flies easily, not a recent porn viewer. (Possibly she's a professional woman, but not smashed through the glass ceiling.)
:Assumed Megan with the 'device', standing apart: less than 30yo, not high-earning, *fears flying* (hence her inspiration), not a recent porn viewer. (Could this be the archetypal Megan, or just ''a'' Megan?)
:Taller cueball, in 1-to-1 conversation: *above 30*, not high-earning, flies easily, not a recent porn viewer. (Grown up, doubtless socially comfortable.)
:Shorter, buzzcut cueball, in 1-to-1 conversation: *above 30*, *high earner*, flies easily, not a recent porn viewer. (Probably an pre-middle-aged Exec "going places", perhaps his success and choice of 'young' haircut are as a result of a mild case of Napoleon syndrome, but if people will talk to him he's probably not being a dick about his success.)
:Sitting ponytail, in conference: less than 30yo, not high-earning, flies easily, *recent viewed porn*. (From the companions and the position, probably high 20s recent graduate relaxing with a long-term social group.)
:Sitting cueball, in conference: *above 30*, not high-earning, flies easily, not a recent porn viewer. (Another graduate, early 30s, probably exercises in order to find that sitting position relaxing. Part of the same social group.)
:Sitting flowinghair, in conference: *above 30*, not high-earning, *fears flying*, *recent viewed porn*. (''Sex indeterminate'' as that hair could indicate a metrosexual male. By 30 the look is probably starting to wearing thin, but still not overly embaressing. It certainly doesn't look like (s)he has settled down in a familial relationship yet, but has quite obviously flown the parental nest and is now with friends from college/university. Might have been met on that round-the-world backpacking holiday and discovered they were from his own home city, except for the fear of flying (unless worked passage on ships). Probably knows all the cool scenes in this city, though, so well worth socialising in the park with.)
:Perched cueball, with icecream, hanging out: less than 30yo, not high-earning, flies easily, not a recent porn viewer. (Probably a teenager, with a close-cropped haircut. Might or might not know the other two behind him, but hard to tell what he thinks except perhaps "I've got an ice-cream! Yay!" Perhaps after a busy day of not-watching-porn.)
:Leaning ponytail, with device, hanging out: less than 30yo, not high-earning, *fears flying*, not a recent porn viewer. (Teenage girl. Big on social networking. Probably not so big on face-to-face-talking.)
:Smallest cueball, with device, hanging out: less than 30yo, not high-earning, *fears flying*, *recent viewed porn*. (Teenage boy. Typical teenage boy. As girl, but probably in-between Tweeting with the girl next to him he's serrupticiously viewing a video someone sent him (see his furtive look?), and maybe of the girl next to him. Or something 'sexted' ''from'' her, if that wouldn't count for her SELECTion on that criteria. One way or another, ''probably'' with the sound off.)
:...what's more, presumably none of those fiogures were Terminator Units, Alien Shapeshifting Lizards or ''already'' ghosts of some kind (or whatever class of individual would not belong in TABLE PEOPLE). [[Special:Contributions/141.101.99.7|141.101.99.7]] 09:34, 18 August 2014 (UTC)

::Thats racism! I mean speciesm. Alien Shapeshifting Lizards are people too! -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 10:15, 18 August 2014 (UTC)

Sounds a lot like watch_dogs. [[Special:Contributions/108.162.229.201|108.162.229.201]] 07:42, 18 August 2014 (UTC)

Is this Zuckerberg's phone? [[Special:Contributions/108.162.254.34|108.162.254.34]] 09:33, 18 August 2014 (UTC)

Is there any particular reason this comic isn't appearing on the homepage at the moment? For some reason xkcd.com is displaying 1408 "March of the Penguins". No actual navigation on the site will take me to this comic, I have to manually type /1409 into the URL bar. --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 10:20, 18 August 2014 (UTC)

1310: Goldbach Conjectures

2013-12-30T10:24:54Z

Zagorath: Finished transcript

{{comic
| number = 1310
| date = December 30, 2013
| title = Goldbach Conjectures
| image = goldbach_conjectures.png
| titletext = The weak twin primes conjecture states that there are infinitely many pairs of primes. The strong twin primes conjecture states that every prime p has a twin prime (p+2), although (p+2) may not look prime at first. The tautological prime conjecture states that the tautological prime conjecture is true.
}}

==Explanation==
{{incomplete|Created by a BOT}}

[[Wikipedia:Goldbach's conjecture|Goldbach's conjecture]], [[Wikipedia:Goldbach's weak conjecture|Goldbach's weak conjecture]], and the [[Wikipedia:Twin prime conjecture|twin prime conjecture]] are unsolved problems in mathematics relating to prime numbers, or numbers whose only factors are 1 and itself.

A "strong" conjecture is typically a more restrictive form of the corresponding "weak" conjecture, with the "strong" conjecture typically implying the "weak" one, but not vice versa. For example, Goldbach's strong conjecture would imply Goldbach's weak conjecture, because any odd number greater than 5 can be expressed as 3 plus an even number greater than 2, which would itself be expressed as the sum of two prime numbers, resulting in a way to express the original odd number as the sum of three prime numbers (the two prime numbers that sum to the even number, and 3). The weak conjecture does not, however, imply the strong conjecture. This comic plays on the "strong" and "weak" naming of Goldbach's conjectures by extending it beyond the two famous ones to further degrees of strength or weakness.

Goldbach's weak conjecture has been claimed to have been proven true, while Goldbach's strong conjecture remains unsolved. The two even weaker "conjectures" are obviously true, with the "extremely weak" conjecture not making a formal mathematical statement at all. The two strongest "conjectures" are so strong that they are obviously false.

The title text refers to the twin prime conjecture, which states that there are an infinite number of pairs of primes that differ by 2.

Randall's weak twin prime conjecture states that there are an infinite number of pairs of primes. This is clearly true. Per {{w|Euclid's theorem}}, there are an infinite number of primes. Unlike the actual twin prime conjecture (which specifies a distance of two), this conjecture does not specify a required distance. Thus, any pair from the infinite set of primes suffices. An example is 5 and 13.

His strong twin prime conjecture states that every prime is 2 less than another prime (although it might not look like a prime at first). An obvious counter-example is 7 and 9. 9 "might not look like a prime".

The tautological prime conjecture states that it itself is true, while making no statement about primes. It is not, despite its name, a tautology. An example of a tautology would be "all primes are prime".

==Transcript==
;Goldbach Conjectures
;Extremely weak
:Numbers just ''keep going''
;Very weak
:Every number greater than 7 is the sum of two other numbers
;Weak
:Every odd number greater than 5 is the sum of three primes
;Strong
:Every even number greater than 2 is the sum of two primes
;Very strong
:Every odd number is prime
;Extremely strong
:There are no numbers above 7

{{comic discussion}}

Talk:1297: Oort Cloud

2013-12-02T18:37:53Z

Zagorath: formatting

Reading the Wikipedia page on the Oort Cloud didn't help me understand the joke. I don't know if it has anything to do with comets, or the asteroids getting smashed up by them. [[Special:Contributions/108.162.238.117|108.162.238.117]] 05:15, 29 November 2013 (UTC)
:The asteroid becomes a cost after being severely burnt by the sun. It warns the other asteroid not to go over there. {{unsigned ip|108.162.221.55}}
::Which, the title text indicates, is a warning that's utterly ignored... (Also being "right back" indicates a slower perceived thought process. As is probably the case for anything out there in such cold(-ish) depths of space.) [[Special:Contributions/141.101.99.229|141.101.99.229]] 11:05, 29 November 2013 (UTC)
::: What does "becomes a cost" mean? is that a slang expression? 12:02, 29 November 2013 (UTC)
:::: I think it's supposed to be "comet". [[Special:Contributions/173.245.52.228|173.245.52.228]] 14:09, 29 November 2013 (UTC)
::::: No, I think he means ghost. All thats left is a faint image after all. {{unsigned ip|141.101.99.214}}
At least according to my freshman year science teacher, the Oort Cloud is just a theory, and hasn't been proven. Perhaps that should be made more clear?{{unsigned|Wasda}}
::::::@Wasda, A theory is something which is proven, if not its a hypothesis or a speculation. Mocking on "theories" is typical for laymen. 15:12, 30 November 2013 (UTC)~
:Theory is the wrong term. Gravity is a theory. Evolution is a theory. The oort cloud is "hypothesized". {{User:Omega/sig}} 06:21, 30 November 2013 (UTC)
----
What's here looks exactly in line with current comet theory: A comet is "perturbed" by interactions with other objects out there, and at that distance the sun is a very bright dot, no more. On return (chancy, based on both/either burning up or being in a no return hyperbolic orbit), what has come back is fragmented and with two tails. What I'm not seeing is the second level joke - it's in the movie "I'm going to check out x" form, but I don't get the specific quote. [[User:FractalgeekUK|FractalgeekUK]] ([[User talk:FractalgeekUK|talk]]) 13:55, 29 November 2013 (UTC)

----
According to http://www.nasa.gov/content/goddard/timeline-of-comet-ison-s-dangerous-journey, ISON's journey to earth from the Oort cloud started "At least a million years ago." So I'm going to edit "many thousand years later" to "several million years later". In other news, I recently played "Das Rad" (http://www.youtube.com/watch?v=n-7y3B8DjGw) for my kids and this comic really reminded me of that Oscar-nominated short. I hate lichen! :-) [[User:Tovodeverett|Tovodeverett]] ([[User talk:Tovodeverett|talk]]) 15:10, 29 November 2013 (UTC)

----
What's with the "Several million years later" context in the transcription?!? The distances might be vast and all, but i doubt the timeframe is ''that'' long... -- [[Special:Contributions/173.245.51.210|173.245.51.210]]
:See the comment right above yours. [[User:Diszy|Diszy]] ([[User talk:Diszy|talk]]) 18:03, 29 November 2013 (UTC)
::You are discussing editorial elements included in the transcription that have no relationship to the original comic. Regardless of any implied passage of time the comic does not directly state a time-frame that passes and the transcript should only include information contained in the original comic. Any discussion of time-frame should take place in the explanation. The panels imply a pause of unspecific time. The transcript should read the same. [[User:Mrarch|Mrarch]] ([[User talk:Mrarch|talk]]) 16:18, 2 December 2013 (UTC)
----
;A comic I did predict yesterday
Uhhh, while I observed that close encounter of ISON at the sun yesterday live I was sure Randall would do a comic on this matter. And he did. That's just funny for me. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:28, 29 November 2013 (UTC)

;When is a comet a comet?

Wikipedia says "A {{w|comet}} is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail." I see no clear suggestion on Wikipedia that a {{w|small Solar System body}} might change from being an asteroid to being a comet each time it passes by the sun and starts to outgas. It seems to me that SSSB's that contain ices and other volatiles that would outgas given enough heat are comets, but I haven't seen that question really addressed clearly by any authoritative sources. For now I'm switching the references to distant comets from "asteroid" to "comet nucleus", which is used on wikipedia and seems like a neutral term for an icy object that would show a cometary atmosphere and tail when close to the sun. Also, the oort cloud is hypothesized to have both a spherical and a disk-like structure, and is part of the solar system. Please discuss further related changes here. Thanks! [[User:Nealmcb|Nealmcb]] ([[User talk:Nealmcb|talk]]) 16:34, 1 December 2013 (UTC)
:The most false understanding is: A comet is a dirty snowball. In fact it's just a snowy rock, most of it is still rock, otherwise it would break up at a distance between Earth and Venus. And all the frozen gases are not only H<sub>2</sub>O. Furthermore a comet is a comet when we can see its shape, unless that tail is shown it's just a small object at our solar system, not more.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 22:17, 1 December 2013 (UTC)
::The wikipedia references in the article talk of objects out in the Oort cloud as "comet nuclei". Unless you can find better sources, that's what we should go with. [[User:Nealmcb|Nealmcb]] ([[User talk:Nealmcb|talk]]) 14:56, 2 December 2013 (UTC)
----
Diameter of the sun: 1,391,000 km

Distance of ISON from sun at perihelion: 1,860,000 km

ISON went within one sun diameter

One of the above statements is false. All are in the explanation. --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 18:37, 2 December 2013 (UTC)

Talk:1297: Oort Cloud

2013-12-02T18:37:01Z

Zagorath: Trilemma of sun diameter

Reading the Wikipedia page on the Oort Cloud didn't help me understand the joke. I don't know if it has anything to do with comets, or the asteroids getting smashed up by them. [[Special:Contributions/108.162.238.117|108.162.238.117]] 05:15, 29 November 2013 (UTC)
:The asteroid becomes a cost after being severely burnt by the sun. It warns the other asteroid not to go over there. {{unsigned ip|108.162.221.55}}
::Which, the title text indicates, is a warning that's utterly ignored... (Also being "right back" indicates a slower perceived thought process. As is probably the case for anything out there in such cold(-ish) depths of space.) [[Special:Contributions/141.101.99.229|141.101.99.229]] 11:05, 29 November 2013 (UTC)
::: What does "becomes a cost" mean? is that a slang expression? 12:02, 29 November 2013 (UTC)
:::: I think it's supposed to be "comet". [[Special:Contributions/173.245.52.228|173.245.52.228]] 14:09, 29 November 2013 (UTC)
::::: No, I think he means ghost. All thats left is a faint image after all. {{unsigned ip|141.101.99.214}}
At least according to my freshman year science teacher, the Oort Cloud is just a theory, and hasn't been proven. Perhaps that should be made more clear?{{unsigned|Wasda}}
::::::@Wasda, A theory is something which is proven, if not its a hypothesis or a speculation. Mocking on "theories" is typical for laymen. 15:12, 30 November 2013 (UTC)~
:Theory is the wrong term. Gravity is a theory. Evolution is a theory. The oort cloud is "hypothesized". {{User:Omega/sig}} 06:21, 30 November 2013 (UTC)
----
What's here looks exactly in line with current comet theory: A comet is "perturbed" by interactions with other objects out there, and at that distance the sun is a very bright dot, no more. On return (chancy, based on both/either burning up or being in a no return hyperbolic orbit), what has come back is fragmented and with two tails. What I'm not seeing is the second level joke - it's in the movie "I'm going to check out x" form, but I don't get the specific quote. [[User:FractalgeekUK|FractalgeekUK]] ([[User talk:FractalgeekUK|talk]]) 13:55, 29 November 2013 (UTC)

----
According to http://www.nasa.gov/content/goddard/timeline-of-comet-ison-s-dangerous-journey, ISON's journey to earth from the Oort cloud started "At least a million years ago." So I'm going to edit "many thousand years later" to "several million years later". In other news, I recently played "Das Rad" (http://www.youtube.com/watch?v=n-7y3B8DjGw) for my kids and this comic really reminded me of that Oscar-nominated short. I hate lichen! :-) [[User:Tovodeverett|Tovodeverett]] ([[User talk:Tovodeverett|talk]]) 15:10, 29 November 2013 (UTC)

----
What's with the "Several million years later" context in the transcription?!? The distances might be vast and all, but i doubt the timeframe is ''that'' long... -- [[Special:Contributions/173.245.51.210|173.245.51.210]]
:See the comment right above yours. [[User:Diszy|Diszy]] ([[User talk:Diszy|talk]]) 18:03, 29 November 2013 (UTC)
::You are discussing editorial elements included in the transcription that have no relationship to the original comic. Regardless of any implied passage of time the comic does not directly state a time-frame that passes and the transcript should only include information contained in the original comic. Any discussion of time-frame should take place in the explanation. The panels imply a pause of unspecific time. The transcript should read the same. [[User:Mrarch|Mrarch]] ([[User talk:Mrarch|talk]]) 16:18, 2 December 2013 (UTC)
----
;A comic I did predict yesterday
Uhhh, while I observed that close encounter of ISON at the sun yesterday live I was sure Randall would do a comic on this matter. And he did. That's just funny for me. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:28, 29 November 2013 (UTC)

;When is a comet a comet?

Wikipedia says "A {{w|comet}} is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail." I see no clear suggestion on Wikipedia that a {{w|small Solar System body}} might change from being an asteroid to being a comet each time it passes by the sun and starts to outgas. It seems to me that SSSB's that contain ices and other volatiles that would outgas given enough heat are comets, but I haven't seen that question really addressed clearly by any authoritative sources. For now I'm switching the references to distant comets from "asteroid" to "comet nucleus", which is used on wikipedia and seems like a neutral term for an icy object that would show a cometary atmosphere and tail when close to the sun. Also, the oort cloud is hypothesized to have both a spherical and a disk-like structure, and is part of the solar system. Please discuss further related changes here. Thanks! [[User:Nealmcb|Nealmcb]] ([[User talk:Nealmcb|talk]]) 16:34, 1 December 2013 (UTC)
:The most false understanding is: A comet is a dirty snowball. In fact it's just a snowy rock, most of it is still rock, otherwise it would break up at a distance between Earth and Venus. And all the frozen gases are not only H<sub>2</sub>O. Furthermore a comet is a comet when we can see its shape, unless that tail is shown it's just a small object at our solar system, not more.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 22:17, 1 December 2013 (UTC)
::The wikipedia references in the article talk of objects out in the Oort cloud as "comet nuclei". Unless you can find better sources, that's what we should go with. [[User:Nealmcb|Nealmcb]] ([[User talk:Nealmcb|talk]]) 14:56, 2 December 2013 (UTC)
----
Diameter of the sun: 1,391,000 km
Distance of ISON from sun at perihelion: 1,860,000 km
ISON went within one sun diameter

One of the above statements is false. All are in the explanation. --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 18:37, 2 December 2013 (UTC)

Talk:1277: Ayn Random

2013-10-14T09:20:22Z

Zagorath: Hope my syntax works the same as on WP...

I think that should be /(\b[plurandy]+\b ?){2}/i.

[[Special:Contributions/173.66.108.213|173.66.108.213]] 05:12, 14 October 2013 (UTC)

I agree. I was confused for a while about what the b's were doing.

[[Special:Contributions/99.126.178.56|99.126.178.56]] 06:57, 14 October 2013 (UTC)

Maybe it's time to have an Ayn Rand category? --[[Special:Contributions/141.89.226.146|141.89.226.146]] 07:34, 14 October 2013 (UTC)

Can someone explain to the mathematically challenged *how* the list of names fits the regular expression? [[Special:Contributions/141.2.75.23|141.2.75.23]] 09:14, 14 October 2013 (UTC)
: Agreed, I would like to understand what the hell is going on with that. --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 09:20, 14 October 2013 (UTC)

1263: Reassuring

2013-09-11T10:00:45Z

Zagorath: /* Explanation */ expanded on previous

{{comic
| number = 1263
| date = September 11, 2013
| title = Reassuring
| image = reassuring.png
| titletext = 'At least humans are better at quietly amusing ourselves, oblivious to our pending obsolescence' thought the human, as a nearby Dell Inspiron contentedly displayed the same bouncing geometric shape screensaver it had been running for years.
}}

==Explanation==
{{incomplete}}

*Concerns advancements in computer AI.
*''{{w|Go (game)|Go}}'' is an abstract strategy board game considered computationally difficult, compared to chess. Because of the size and number of possible combinations, computers don't have an easy way to exhaustively search for the best move. Still, {{w|
Computer Go|they are getting better and better playing it}}.

This comic references XKCD Comic [[1002: Game AIs]], which discusses the capacity for computer AIs to beat humans in various games. In particular, on that graph, Go was one of the last games where a computer can still be beaten by top humans.

==Transcript==
:[Megan is sitting at a computer, and Cueball is standing behind her.]
:Megan: Looks like computers will beat humans at '''Go''' pretty soon.
:Cueball: Wow.
:Cueball: That's the last of the big ones.
:Megan: Yeah.

:Cueball: Well, at least humans are still better at, uh,
:Cueball: Coming up with reassuring parables about things humans are better at?
:Megan: Hmm.

:''type type''

:Megan: I made a Python script that generates thousands of reassuring parables per second.
:Cueball: ''Dammit.''
:Computer: Computers will never understand a sonnet Computers will never enjoy a salad comp—

{{comic discussion}}

1263: Reassuring

2013-09-11T09:58:42Z

Zagorath: Explain reference to previous comic.

{{comic
| number = 1263
| date = September 11, 2013
| title = Reassuring
| image = reassuring.png
| titletext = 'At least humans are better at quietly amusing ourselves, oblivious to our pending obsolescence' thought the human, as a nearby Dell Inspiron contentedly displayed the same bouncing geometric shape screensaver it had been running for years.
}}

==Explanation==
{{incomplete}}

*Concerns advancements in computer AI.
*''{{w|Go (game)|Go}}'' is an abstract strategy board game considered computationally difficult, compared to chess. Because of the size and number of possible combinations, computers don't have an easy way to exhaustively search for the best move. Still, {{w|
Computer Go|they are getting better and better playing it}}.

This comic references XKCD Comic [[1002: Game AIs]], which discusses the capacity for computer AIs to beat humans in various games.

==Transcript==
:[Megan is sitting at a computer, and Cueball is standing behind her.]
:Megan: Looks like computers will beat humans at '''Go''' pretty soon.
:Cueball: Wow.
:Cueball: That's the last of the big ones.
:Megan: Yeah.

:Cueball: Well, at least humans are still better at, uh,
:Cueball: Coming up with reassuring parables about things humans are better at?
:Megan: Hmm.

:''type type''

:Megan: I made a Python script that generates thousands of reassuring parables per second.
:Cueball: ''Dammit.''
:Computer: Computers will never understand a sonnet Computers will never enjoy a salad comp—

{{comic discussion}}