Talk:Thorium

Use in cavity magnetrons filaments (used in microwave ovens)

The page on cavity magnetrons states Thorium is used in the filaments of the magnetron. It would be interesting to find references to support this and to mention it under the applications for / uses of Thorium.

No consensus to remove souce.

This edit by @2601:441:8500:b870::f1a7 removed the source

• de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.

for the content

• Four-fifths of the thorium present at Earth's formation has survived to the present.

In the edit summary it says:

• WP:CALC; also source was an old version of which we have the current versions already here

The WP:CALC says "Routine calculations do not count as original research, provided there is consensus among editors that the results of the calculations are correct, and a meaningful reflection of the sources."

But this 4/5 is not a calculation in any routine sense of the word. Johnjbarton (talk) 23:13, 29 July 2025 (UTC)

It is most certainly a calculation (I checked it myself without needing to see the source), and routine in the sense meant by the policy: there's no other way it could be done. As it explains, 'routine' does not mean 'immediately obvious to anyone'. Anyway, if you want to source it, at least figure out the correct version to use - it isn't hard to find. 2601:441:8500:B870:0:0:0:F1A7 (talk) 23:33, 29 July 2025 (UTC)

I verified the existing source already, there is no need to use another version. Johnjbarton (talk) 23:40, 29 July 2025 (UTC)

In my book $0.5^{4.5/14}\approx 0.800$ is a routine calculation. But if it's already sourced, I suppose it hardly matters. Double sharp (talk) 09:50, 30 July 2025 (UTC)

Where does $0.5^{4.5/14}$ come from? Johnjbarton (talk) 15:16, 30 July 2025 (UTC)

Age of Earth and half-life of ²³²Th are 4.5 billion years and 14 billion years respectively, but as the article never mentions age of Earth, I'm not sure is this permitted (possibly requires a footnote per WP:CALC for such cases) Nucleus hydro elemon (talk) 15:30, 30 July 2025 (UTC)

Nor is such a formula common knowledge to someone reading Thorium. Moreover the connections among the half-life, formation of the Earth, and present abundance assumes physical models of the history of the Earth and geochemically effects, none which should be assumed of any reader. Johnjbarton (talk) 15:39, 30 July 2025 (UTC)

The formula given by Double sharp is correct; if you mean you suggest it's more complicated, that's not how radioactive decay works. The fact that the age of the Earth comes in is of note, though; as the fact really has no context without it. I, however, took at least the approximate age (4 1/2 billion years) to be common knowledge.

As for my questioning the version, I mean that I would prefer, if a source is needed, this link used in the infobox as it directly goes to a page containing the fact, rather than a very long PDF. However, I don't know how to make a link there without using the URL. 73.228.195.198 (talk) 23:04, 30 July 2025 (UTC)

I have changed the source. Nucleus hydro elemon (talk) 13:46, 31 July 2025 (UTC)

Actually, that was a different place than was being discussed - but an improvement anyway! 2601:441:8500:B870:0:0:0:F1A7 (talk) 22:36, 31 July 2025 (UTC)