explain xkcd - User contributions [en]

2785: Marble Run

2023-06-05T22:39:39Z

DrGaellon: Explained the three objects mentioned in the alt text

{{comic
| number = 2785
| date = June 5, 2023
| title = Marble Run
| image = marble_run_2x.png
| imagesize = 438x512px
| noexpand = true
| titletext = I have so many plans. It would incorporate a Galton board, a Ranque-Hilsch marble vortex tube, and a compartment lined with pinball bouncers with a camera-and-servo Maxwell's Demon that separated the balls into fast and slow sides.
}}

==Explanation==
{{incomplete|Created by MAXWELL'S DEMON - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

Cueball knows that he is going to end up building a cool marble run (like how a marble will eventually get to the bottom of a marble run), but he wants to take a long and interesting path to get there. In the last panel, it plays off the fact that he is acting like one of the marbles in a cool marble run. He, like the marble, is going to take a long route, one that is interesting, to get to the place where he is inevitably going to get to (building cool marble runs).

A [https://en.wikipedia.org/wiki/Galton_board Galton board] is a device that demonstrates the normal bell-curve distribution. It is the inspiration for pachinko-style games.

A [https://en.wikipedia.org/wiki/Vortex_tube Ranque-Hilsch vortex tube] is a device for separating compressed gas into hot and cold streams. It would not work on marbles, as it is dependent on the physics of gasses.

[https://en.wikipedia.org/wiki/Maxwell%27s_demon Maxwell's Demon] is a thought experiment by James Clerk Maxwell which would violate the Second Law of Thermodynamics. If implemented, it would, in fact, separate the balls into fast and slow streams (the original thought experiment involved a "demon" controlling a door between two chambers; the demon would only allow fast-moving molecules to move in one direction through the door and slow-moving molecules in the other direction. This would cause one chamber to warm and the other to cool and would decrease the total entropy of the system, which is forbidden by the Second Law.)

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

:[Megan is walking towards Cueball and showing her phone. Cueball holds a hand to his face and looks away.]
:Megan: Check out this cool video of a Rube Goldberg marble run.
:Cueball: No! Not yet.

:[Megan has lowered her phone. Cueball has his hand in a fist.]
:Cueball: I've always known I'm doomed to eventually become one of those people who builds elaborate marble runs in their garage.
:Cueball: I can feel the pull.
:Cueball: So satisfying.

:[Close-up on Cueball.]
:Cueball: I just want to do as many other things as I can before I give in and disappear into that world.

:[Megan and Cueball are walking.]
:Megan: So you know where you're going to end up, but you're trying to take a really interesting and circuitous path to get there.
:Cueball: Exactly. Bounce around, maybe go off a few jumps.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]

1574: Trouble for Science

2015-09-07T12:26:39Z

DrGaellon: Fixed link to be direct

{{comic
| number = 1574
| date = September 7, 2015
| title = Trouble for Science
| image = trouble_for_science.png
| titletext = Careful mathematical analysis demonstrates small-scale irregularities in Gaussian distribution
}}

==Explanation==
Five newspaper headlines are shown:

;Many Commercial Antibody-Based Immunoassays Are Unreliable
This sentence is true. See Kebaneilwe Lebani, [http://espace.library.uq.edu.au/view/UQ:352531 Antibody Discovery for Development of a Serotyping Dengue Virus NS1 Capture Assay], 2014. In this PhD thesis, 11 references are given.

;Problems With the p-Value as an Indicator of Significance

;Overfeeding of Laboratory Rodents Compromises Animal Models

;Replication Study Fails to Reproduce Many Published Results

;Controlled Trials Show Bunsen Burners Make Things Colder
This is a joke.

==Transcript==

{{comic discussion}}

[[Category:Science]]
[[Category:Biology]]
[[Category:Chemistry]]
[[Category:Math]]

1574: Trouble for Science

2015-09-07T12:23:24Z

DrGaellon: Added remaining headlines, fixed to Title Case

{{comic
| number = 1574
| date = September 7, 2015
| title = Trouble for Science
| image = trouble_for_science.png
| titletext = Careful mathematical analysis demonstrates small-scale irregularities in Gaussian distribution
}}

==Explanation==
Five newspaper headlines are shown:

;Many Commercial Antibody-Based Immunoassays Are Unreliable
This sentence is true. See Kebaneilwe Lebani, [http://espace.library.uq.edu.au/mwg-internal/de5fs23hu73ds/progress?id=Gv4yxghu7eDamGI-7Q_1LbB17e2FL9ky_YXqq1fiuIQ,&dl Antibody Discovery for Development of a Serotyping Dengue Virus NS1 Capture Assay], 2014. In this Phd thesis 11 references are given.

;Problems With the p-Value as an Indicator of Significance

;Overfeeding of Laboratory Rodents Compromises Animal Models

;Replication Study Fails to Reproduce Many Published Results

;Controlled Trials Show Bunsen Burners Make Things Colder
This is a joke.

==Transcript==

{{comic discussion}}

[[Category:Science]]
[[Category:Biology]]
[[Category:Chemistry]]
[[Category:Math]]

Talk:1184: Circumference Formula

2013-03-25T23:23:16Z

DrGaellon:

:Tau x Radius, superscript 2
:Leaves one wondering what the superscript 1 refers. {{unsigned|‎74.215.40.250}}
::It's 2''πr''2, '''not''' ''τr''2. —[[Special:Contributions/173.199.215.5|173.199.215.5]] 05:37, 11 March 2013 (UTC)
:::You're missing the point. ''τ'' == 2''π'' and is considered better than using ''π'' by some people {{unsigned|138.195.69.136}}
::::Only for very loose definitions of "better." [[Special:Contributions/71.201.53.130|71.201.53.130]] 14:59, 11 March 2013 (UTC)
::::Whoa! Never heard about that before, but after 2 hrs or so, I think I'm getting convinced! Check this site out: http://tauday.com/ What do you think? –[[User:St.nerol|St.nerol]] ([[User talk:St.nerol|talk]]) 18:06, 11 March 2013 (UTC)

::I think tau is pointless. Using tau what then happens to Euler's famous formula, the most beautiful equation of them all? Pi shows up in so many different ways and places in mathematics. Tau appears pretty much only in the formula for a circle's circumference. Why bother needlessly proliferating symbols? [[User:J Milstein|J Milstein]] ([[User talk:J Milstein|talk]]) 18:17, 11 March 2013 (UTC)

:::RE: Euler's Identity: e^(tau*i) - 1 = 0 --[[User:Max Nanasy|Max Nanasy]] ([[User talk:Max Nanasy|talk]]) 18:27, 11 March 2013 (UTC)
::::Ok, that works [[User:J Milstein|J Milstein]] ([[User talk:J Milstein|talk]]) 17:05, 13 March 2013 (UTC)
::::Why not just e^(tau*i) = 1. Do you routinely do 2 + 2 - 4 = 0?[[Special:Contributions/206.181.86.98|206.181.86.98]] 20:31, 13 March 2013 (UTC)
:::::Because:
:::::* Symmetry wrt the original Euler's Identity (e^(pi*i) + 1 = 0)
:::::* According to http://en.wikipedia.org/wiki/Euler's_identity#Mathematical_beauty, "in algebra and other areas of mathematics, equations are commonly written with zero on one side of the equals sign."
:::::--[[User:Max Nanasy|Max Nanasy]] ([[User talk:Max Nanasy|talk]]) 00:35, 14 March 2013 (UTC)
::::::I think Euler only did that because he disliked negative numbers. It really is less a deal than people make of it.[[Special:Contributions/206.181.86.98|206.181.86.98]] 03:02, 15 March 2013 (UTC)
:::[http://tauday.com/tau-manifesto The tau manifesto] fairly well convinced me that all occurances of π in mathematics utimately trace back from the formula C = 2''πr''. If so, π naturally ''enter'' calculations as 2π. Can anyone find a counterexample to this thesis? –[[User:St.nerol|St.nerol]] ([[User talk:St.nerol|talk]]) 00:29, 14 March 2013 (UTC)
::::How could there be a counter-example? I think it is true. In complex analysis, it really should be 2π, and thus Gaussian integrals. And then number theory applications. Even [http://www.jstor.org/discover/10.2307/2589152?uid=3739704&uid=2&uid=4&uid=3739256&sid=21101976916347 this] neat result really stems from trig identities, so it really is a result for 2π. [[Special:Contributions/206.181.86.98|206.181.86.98]] 02:59, 15 March 2013 (UTC)
:From what I understand, the thesis from the tau-proponents is that 2*pi is the fundamental natural constant, and that virtually ''every time'' that pi shows up without the factor 2, there originally was a factor two that was cancelled out. –[[User:St.nerol|St.nerol]] ([[User talk:St.nerol|talk]]) 01:53, 12 March 2013 (UTC)

Not completely sure Earth Prime is from Sliders, but it's true it's the [http://en.wikipedia.org/wiki/Earth_Prime only one named exactly that] ... -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 09:54, 11 March 2013 (UTC)

There's also a [http://dc.wikia.com/wiki/Prime_Earth Prime Earth] now. Just so DC can screw with us. [[User:Hogtree Octovish|Hogtree Octovish]] ([[User talk:Hogtree Octovish|talk]]) 10:40, 11 March 2013 (UTC)

I still don't get it.[[Special:Contributions/49.176.102.213|49.176.102.213]] 12:41, 11 March 2013 (UTC)

:If you don't get it, you don't need to get it [[User:J Milstein|J Milstein]] ([[User talk:J Milstein|talk]]) 18:07, 11 March 2013 (UTC)

Well, that was lame. --[[Special:Contributions/87.122.60.227|87.122.60.227]] 17:19, 11 March 2013 (UTC)

This comic illustrates the strategy of "The Unconsummated Asterisk", from the essay "Mathmanship" by Nicholas Vanserg (available at [http://e-science.ru/forum/index.php?act=attach&type=post&id=7701]).
<blockquote>
The other side of the asterisk gambit is to use a superscript as a key to a real footnote. The knowledge‐seeker reads that S is – 36.714 calories and thinks "Gee what a whale of a lot of calories" until he reads to the bottom of the page, finds footnote 14 and says "oh."
</blockquote>
For bonus points, Randall could have used also "Pi-Throwing":
<blockquote>
For example every schoolboy knows what π stands for so you can hold him at bay by heaving some entirely different kind of π into the equation. The poor fellow will automatically multiply by 3.1416, then begin wondering how a π got into the act anyhow, and finally discover that all the while π was osmotic pressure. If you are careful not to warn him, this one is good for a delay of about an hour and a half.
</blockquote> [[User:Chymicus|Chymicus]] ([[User talk:Chymicus|talk]]) 19:01, 11 March 2013 (UTC)
:Another good one is π as a symbol for profit in financial discussions. -[[User:DrGaellon|DrGaellon]] ([[User talk:DrGaellon|talk]] | [[Special:Contributions/DrGaellon|contribs]]) 23:23, 25 March 2013 (UTC)

I believe the current description of prime as denoting derivatives is true but irrelevant. Since the area and circumference refers to geometry (not really calculus), it's more likely that the title text is referring to the common use of primes in geometry. For example, there might be two or more parallel lines that are denoted by x, x′, x′′, etc. Wikipedia also notes another geometric use of {{w|prime}}: "if a point is represented by the Cartesian coordinates (x, y), then that point rotated, translated or reflected might be represented as (x′, y′)." [[User:S|S]] ([[User talk:S|talk]]) 23:32, 11 March 2013 (UTC)

that is so wrong, i feel my mind corrupted now. -- [[User:Anarcat|Anarcat]] ([[User talk:Anarcat|talk]]) 23:57, 11 March 2013 (UTC)

This explanation was hillarious -- where is the up-vote button ?? [[User:Spongebog|Spongebog]] ([[User talk:Spongebog|talk]])

:+1 [[User:Smperron|Smperron]] ([[User talk:Smperron|talk]]) 16:33, 13 March 2013 (UTC)

So, where's todays comic? How many times has Randal been late?[[Special:Contributions/70.199.225.225|70.199.225.225]] 16:15, 13 March 2013 (UTC)

:Today's comic was posted just a few minutes ago. I'm anxiously awaiting its explanation as it picks on a programming language I'm not familiar with (possibly SQL). [[User:Smperron|Smperron]] ([[User talk:Smperron|talk]]) 16:33, 13 March 2013 (UTC)

It uses pseudocode. The new one is about sorting algorithms in general, not any particular language. [[Special:Contributions/130.245.231.101|130.245.231.101]] 17:00, 13 March 2013 (UTC)

Perhaps it's just me, but did no one see the "square the circle" gag...? --[[Special:Contributions/128.232.142.37|128.232.142.37]] 09:24, 14 March 2013 (UTC) No one but you saw the square-the-circle gag, because it's not there. For it to be there, it would require this: (2πr)² [[User:J Milstein|J Milstein]] ([[User talk:J Milstein|talk]]) 15:31, 14 March 2013 (UTC)