Talk:3086: Globe Safety

2025-05-08T06:12:15Z

StumbleRunner:

Hello! First time i got to a comic first {{unsigned ip|104.23.175.202}}
:Well [[269: TCM|first of all]] remember to sign your comments :-). But congratz... --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 05:42, 8 May 2025 (UTC)

I believe he indicates that a globe is made by making a copy of the Earth, and then compressing it until it fits on a desktop. Hence having the same mass and thus the same Schwarzschild radius as Earth. I have changed the explanation a bit because of this observation.--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 05:42, 8 May 2025 (UTC)

Gotta wonder what kind of a desk could support a desktop globe that weighs as much as the Earth
--[[User:StumbleRunner|StumbleRunner]]

3037: Radon

2025-01-15T07:59:18Z

StumbleRunner: /* Explanation */

{{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.
}}

{{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 is denser than air, but its concentrations are higher in the basement than elsewhere in a building because of the combination of its being generated more there, and the relatively poor air circulation usual in basements. Radon mixes completely with air, and does not "settle out" because of its atomic weight or density. 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.

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 interstellar inspector, testing properties on many different planets in different star systems with different levels of radon - since most planets in a given system form within a few million years of each other and would have similar levels of radon. 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 which the inspector notes as a short lived star. 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. Whereas if we'd built around a M-type red dwarf we could have comfortably{{cn}} waited for the uranium to fully decay and the star would still be fine.

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 <sup>238</sup>U, 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> This text may also be an oblique reference to the concept of a {{w|nuclear umbrella}}, an altogether different kind of "insurance".

==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 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]]

==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 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:3035: Trimix

2025-01-09T07:17:09Z

StumbleRunner:

The 'standard' and '2x' sized images had unexpected sizes, so an imagesize parameter has been added to render the image consistently with other comics on this website. See the web [https://web.archive.org/web/*/https://imgs.xkcd.com/comics/trimix.png archive] for more details. --[[User:TheusafBOT|TheusafBOT]] ([[User talk:TheusafBOT|talk]]) 05:15, 9 January 2025 (UTC)

I'd question whether you could get a scuba tank to float with any amount of helium. Since you're dealing with a fixed size tank the most lift you going to get would be less than the weight of the air that the tank displaces (lift = weight of air - weight of tank - weight of helium, iirc). A typical aluminum Ali 80 tank has a volume of 11.1 liters which displaces only about 151g of air while the tank itself weighs 14kg [[User:StumbleRunner|StumbleRunner]] ([[User talk:StumbleRunner|talk]]) 07:17, 9 January 2025 (UTC)

Talk:3035: Trimix

2025-01-09T07:02:57Z

StumbleRunner:

The 'standard' and '2x' sized images had unexpected sizes, so an imagesize parameter has been added to render the image consistently with other comics on this website. See the web [https://web.archive.org/web/*/https://imgs.xkcd.com/comics/trimix.png archive] for more details. --[[User:TheusafBOT|TheusafBOT]] ([[User talk:TheusafBOT|talk]]) 05:15, 9 January 2025 (UTC)

I'd question whether you could get a scuba tank to float with any amount of helium. Since you're dealing with a fixed size tank the most lift you going to get would be the less than the weight of the air that the tank displaces (lift = weight of air - weight of tank - weight of helium, iirc) [[User:StumbleRunner|StumbleRunner]] ([[User talk:StumbleRunner|talk]]) 07:02, 9 January 2025 (UTC)

explain xkcd - User contributions [en]

Talk:3086: Globe Safety

3037: Radon

Talk:3035: Trimix

Talk:3035: Trimix