explain xkcd - User contributions [en]

3037: Radon

2025-01-14T13:37:03Z

172.68.245.207:

{{comic
| number = 3037
| date = January 13, 2025
| title = Radon
| image = radon_2x.png
| imagesize = 740x291px
| noexpand = true
| titletext = A good ²³⁸Umbrella policy should cover it.
}}

==Explanation==
{{incomplete|Created by a PLANET INSURANCE SALESMAN - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238, the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, roughly 2.8 ppm of the planet is made of uranium<ref>https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview</ref>; this is about 0.00028% of the planet, which weighs about 5.9722*10^24 kilograms<ref>https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html</ref>. Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is  1.672216*10^19 kilograms of uranium across the entire planet. Thus, radon gas is not ''that'' uncommon a phenomenon, and {{w|Radon mitigation|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over long enough time; that is, the windows and doors are closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon, being denser than air, naturally tends to settle in lower areas like basements. Its concentration is further increased in basements due to higher levels of radon generation there and the typically poor air circulation in such spaces. Radon mixes completely with air, and does not "settle out". Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.

The actual amount of uranium experienced in any given environment, according [[Randall|Randall's]] own [[Radiation|Radiation chart]], is 10 microsieverts worth of radiation, on average, over a year; the amount in one's body, in contrast, is about 390 microsievert over that same timeframe, again on average. The lowest dose linked to any serious risk is in the millisievert range, over thousands of times ''stronger'' than any of these sources. Thus the ''radiation'' from radon buildup in a normal house is not of concern, as long as it is properly managed in time. Instead it is radon's ''toxicity'' that is the problem, both from the radon itself and its "daughter" isotopes, that poses a danger to humans.

In the comic Cueball is getting his house inspected; this is common in preparation for selling the home. Inspector Ponytail finds an excessive level of radon in the basement. Often when problems are found in a home, it's due to the age of the building, since technology has improved over time and building codes have added requirements in parallel.

But rather than inquire about the age of the home, Ponytail asks about the age of the planet on which it was built. The answer would be the same for all houses on Earth.{{cn}} Apparently she's an interplanetary inspector, testing properties on many different planets with different levels of radon - maybe even different solar systems, since most planets in a system form within a few million years of each other. Earth's age of 4.5 billion years is about the same as the half-life of U-238, so radon levels are high because much of the original uranium is still in the process of decaying.

The sun found in our solar system is an example of a G-type main-sequence star, also known as a yellow dwarf. In 4 to 7 billion years, the Sun's outer layers will expand, turning it into a red giant. This process will render the Earth uninhabitable for humans within approximately 5 billion years.

The title text for this comic mentions {{w|umbrella insurance}}, which is what insurance companies in the United States pay when the payment extends over their own policies. It makes a joke with the isotope representation of Uranium-238 being 238U, and is something that Cueball might need to consult with after handling the issue of radon gas in his home; most states in the United States, for instance, require property disclosure forms to be filled out if radon levels surpass a certain threshold.<ref>https://www.eli.org/sites/default/files/files-pdf/Final%202022%20Radon_0.pdf</ref>

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

:[Cueball is on the left, and is approached by Ponytail, who is reading a Geiger counter in her hand and is holding a toolbox in her other hand.]
:Ponytail: Radon levels in your basement are pretty high.
:Ponytail: When was the planet under this home built?

:[Ponytail stops walking and lowers the Geiger counter]
:Cueball: Uhh, about 4½ billion years ago, I think?
:Ponytail: Oof. I was afraid of that.

:[A frameless panel]
:Ponytail: This planet was contaminated with uranium when it formed. You really should have let it fully decay before building.
:Ponytail: Wait another 100 billion years and these rocks will be fine.

:[Zoom in on Cueball's head]
:Cueball: But the Sun will burn out in 5 billion years.
:Ponytail (off-panel): Yikes, you built around a short-lived yellow star? What a mess.
:Ponytail (off-panel): Hope you have good insurance.
==References==
{{reflist}}

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Physics]]
[[Category:Chemistry]]
[[Category:Geology]]
[[Category:Astronomy]]

Talk:3010: Geometriphylogenetics

2024-11-14T14:33:35Z

172.68.245.207: /* Is this a flatworld reference? */ new section

Does the phrase "maximum likelihood" have any relationship to phylogenetics? [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 03:01, 12 November 2024 (UTC)
: {{w|Computational_phylogenetics#Maximum_likelihood|Profoundly so}}. Most contemporary analyses, especially of large datasets, use either maximum-likelihood methodologies or Bayesian inference (q.v.). I will see if I can say something coherent and comprehensible about this in the explanation. [[Special:Contributions/172.71.147.58|172.71.147.58]] 03:30, 12 November 2024 (UTC)
::If it was you who added the explanation for the title text, nicely done! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 05:04, 12 November 2024 (UTC)

"Pointy circle" is, of course, an oxymoron. Randall is also making a joke about how older phylogenetic trees were based on anatomy, like saying that squares and triangles are close because they have exoskeletons with straight lines and joints. Now, the tree is (where possible) based on genetic similarity. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 05:10, 12 November 2024 (UTC)

Hippos can't swim? Did the BBC lie to us? https://youtu.be/X20NjqMiQyo?si=8pN-xwgKJEWM08ZF
[[Special:Contributions/172.68.186.135|172.68.186.135]] 06:18, 12 November 2024 (UTC)
:Fiona the Hippo begs to differ. [https://www.youtube.com/watch?v=X-YRJCSZRJU] [[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 14:40, 12 November 2024 (UTC)
::Not sure if you're being ironic, but that video shows that Fiona ''can't'' swim. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 17:23, 12 November 2024 (UTC)

Why was phylogenetic analysis required to establish this relationship? Reuleaux triangles are an intermediate form, demonstrating a close relation between circles and triangles. [[Special:Contributions/172.71.130.208|172.71.130.208]] 06:24, 12 November 2024 (UTC)

''Obviously'', he's doing phylogenetics wrong: the pentagons (& hexagons, not shown) should also be shown as descending from the circles. Plus, the ovoids (far more than a middle step between lentiform & triangle, truly an extant branch in their own right) are not represented ''at all''. A major oversight, to cut such corners, given the point he's circling about?
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 06:31, 12 November 2024 (UTC)
:There are two competing theories of the origin of circles. They are either very basal polygons (having one side) or very derived (having infinite sides). It's possible that both are true and 'circle' is a polyphyletic group. [[User:RegularSizedGuy|RegularSizedGuy]] ([[User talk:RegularSizedGuy|talk]]) 16:19, 12 November 2024 (UTC)
::Circles are priests, obviously. [[Special:Contributions/172.69.43.183|172.69.43.183]] 23:46, 12 November 2024 (UTC)

Someone should add something about how circles and triangles are related through trig in a way that the rest aren't. Sorry I am new to this and don't know how to format my comment correctly.

I'm sure you could develop a 'DNA' sequence for geometric shapes. [Number of active vertices + angle, Number of curves in each side + variation from straight + orientation from centre, thickness of stroke, etc] basically the sort of data in any drawing data of said shape. Thus you could have two circles that look every similar, but one being an extreme Reulaux triangle and the other a 10,000 sided polygon with no side curvature at all! C.f. Swift and swallow! YMMV [[User:RIIW - Ponder it|RIIW - Ponder it]] ([[User talk:RIIW - Ponder it|talk]]) 10:38, 12 November 2024 (UTC)
: The result would be a taxon x character data matrix, the first step in all forms of phylogenetic analysis. On such a small matrix, you could probably perform maximum parsimony analysis by hand, as Hennig did. However, with such a small number of characters per taxon, taxon resolution would probably be low (lots of polytomies instead of fully resolved dichotomies), and [https://wiki.christophchamp.com/index.php?title=Bootstrapping bootstrap support values] would be horrible. The resulting consensus tree would likely be [ahem] sharply criticized - not least because it would be a "mere" {{w|Analysis_of_similarities|similarity analysis}} and not a true phylogeny (not a reconstruction of descent with modification of progeny). Do not submit such a tree for peer review, and especially do not take it to a meeting of the [https://cladistics.org/ Willi Hennig Society]. You have been warned. [[Special:Contributions/162.158.42.130|162.158.42.130]] 13:56, 12 November 2024 (UTC)

:I’m reminded of the incircle and circumcircle of a triangle. Triangles are the only shape where all polygons of that edge count are guaranteed to have an incircle and a circumcircle (unless, of course, it is degenerate). [[Special:Contributions/172.71.24.5|172.71.24.5]] 13:34, 12 November 2024 (UTC)

Sorry, but I don't believe in this "Theory of Polygon Evolution". I believe all abstract polygons were created in their current state by intelligent mathematicians. [[User:Mathmannix|Mathmannix]] ([[User talk:Mathmannix|talk]]) 12:21, 12 November 2024 (UTC)

:Heathen - The One True Creator is Euclid! 😉 [[User:RIIW - Ponder it|RIIW - Ponder it]] ([[User talk:RIIW - Ponder it|talk]]) 12:38, 12 November 2024 (UTC)

Reminds me of pedigree genetic charts as well, anyways you geomreationists are so absurdly wrong it's laughable /j [[Special:Contributions/108.162.238.130|108.162.238.130]] 13:24, 12 November 2024 (UTC)

'''Obviously''' both triangles and squares descended from circles. But, while triangles evolved from circles with protrusions that extended into points for improved dynamics, squares evolved from circles that developed flattened sides for more stability. Looking forward at their descendants, we see that both shapes have crab-like descendants. But again, developed from very different mechanisms: The evolved triangles's points split and reformed into the crab claws, while the squares evolved into rectangles which developed concave ends that eventually consolidated into the crab claw shape. [[2314: Carcinization]] [[Special:Contributions/162.158.41.73|162.158.41.73]] 20:11, 12 November 2024 (UTC)

It also reminds me of the quadrilateral family tree (google it, I guess), which has always bothered me exactly because it shows just how unapplicable phylogenetics is to geometry, or they are just super incestuous in a time-traveling sort of way? [[Special:Contributions/172.70.43.29|172.70.43.29]] 20:14, 12 November 2024 (UTC)
:Also (re-)interbreeding. c.f. parallelograms that (regularised) become rhombi, but also the "kite" branch can lead, by regularising, to a rhombus. And rhombi descend to the special case of squares, as do special cases of rectangles (differently special cases of parallelograms than rhombi). If anything, the most interesting sub-family of quadrilateral are all the ones that (while not self-intersecting, adding further complications) manage not to be a rhombus, parallelogram ''or'' trapezium. [[Special:Contributions/172.69.43.183|172.69.43.183]] 23:46, 12 November 2024 (UTC)

[https://en.wikipedia.org/wiki/Flatland Circles are descended from polygons and squares are descended from triangles], at least according to the renowned expert [https://en.wikipedia.org/wiki/Edwin_Abbott_Abbott Edwin Abbott Abbott]. [[Special:Contributions/172.71.175.23|172.71.175.23]] 21:48, 12 November 2024 (UTC)

Exciting new research may have found the universal common ancestor, which is being called a 'point'.[[Special:Contributions/172.70.86.111|172.70.86.111]] 09:32, 13 November 2024 (UTC)

If anyone would like to peer review me, I've filled in the "missing links" https://jimmysfiles.com/misc/evolution-of-shapes.png {{unsigned ip|172.69.194.78|10:18, 13 November 2024}}
:Nice! I did a very different ancestor reconstruction. Not to take any of this too seriously, but making an ancestor that is intermediate between the descendants (as in your triangle subtree) is rarely parsimonious because it requires mutations on both branches. So I end up with a circle as the root. I do like what you did with the quadrilaterals though, where changing an angle or side length counts as a mutation. Maybe angles are more fundamental in shape DNA than concepts like parallel and symmetric; who knows?
:[[File:geometriphylogenetics_annotated.png]]
: --[[User:Quantum7|Quantum7]] ([[User talk:Quantum7|talk]]) 13:44, 14 November 2024 (UTC)

== Is this a flatworld reference? ==

Intentional or unintentional, treating geometric shapes as related life forms is quite reminiscent of flatworld.