Wikipedia:Reference desk/Archives/Science/2024 October 2

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October 2

Aspartame

Is aspartame zero-calorie sweetener? CometVolcano (talk) 16:14, 2 October 2024 (UTC)

The first paragraph of Aspartame#Uses answers this. --Floquenbeam (talk) 16:24, 2 October 2024 (UTC)

When and how did people notice that trovants grow?

Articles about trovants like this (or, less reliably, this) and others note that they grow over time, and that pieces are pushed out or break off and grow independently, leading to local legends that they're alive and grow and reproduce. That makes it sound like their growth has historically been noticeable to locals, enough that they developed legends about it. But the SF article I linked and others also say it takes trovants thousands of years to grow a few centimeters, which seems like something people would not notice.
When did people notice that trovants grow, and how did they notice? Is "a handful of centimetres in over 1,000 years" an average, and some trovants under some conditions grow fast enough to be noticeable? Have any of them grown around something (like a tree growing around a post, or made noticeable in some other way the fact of their growing? Did scientists only figure out recently that models predict they grow, and the local legends are only a very recent tourism marketing thing? Or what? (Ezequiel F. Médici, Alejandro D. Otero, Album of Porous Media: Structure and Dynamics (2023), page 36, says the term 'trovant' was introduced in 1907 by Gheorghe Murgoci.) -sche (talk) 23:37, 2 October 2024 (UTC)

For interest. Sean.hoyland (talk) 08:15, 3 October 2024 (UTC)

I am fairly certain that the story that these concretions grow like living entities, budding and all,^[1] is a folk myth based on appearance. They were formed underground around some organic core, like a fossil. The growth only occurs while embedded in sand containing calcite that can cement the grains into a concretion. Eventually they became exposed by erosion.  --Lambiam 09:02, 3 October 2024 (UTC)

Thanks for your responses. (Sean, your link reminds me of Mother Shipton's Cave. I can see how even a single millimeter or less of stone growth could be noticeable if it was growing over something which was not previously stone! But I had not gotten the impression that that was how people [supposedly or actually] noticed these large boulders growing; can anyone find otherwise?)
I recall seeing the statement that they grew underground and around fossils presented in one of the websites I came across while initially trying to find the answer to my question, but I also recall coming across a site that said that at least some of them don't have fossils (or anything but more sandstone) in their cores. And many sites say they grow due to rainwater (and can grow more on one side than another if one side is more exposed), although that doesn't per se contradict the idea that they form under ground into which rainwater seeps. But apart from SF, it's hard to find much of anything about them in reliable sources. I will try searching in Romanian later; ro.WP says a few things about them but with no inline sources and not much of a bibliography. -sche (talk) 20:23, 3 October 2024 (UTC)

I posted that mainly because it shows that even a couple of thousand years ago, there was the realization that the materials from which rocks are composed can change through interactions with water. And that is especially true for carbonate minerals. Not sure whether you have seen this. Sean.hoyland (talk) 13:40, 4 October 2024 (UTC) (ah..I now see that you have seen the Album of Porous Media).

I had looked this up too, and in 2008 "the International Geological Congress in Oslo claimed trovants were incorrectly classified as concretions because there was no mineral difference between the stones and the sandstone beds on which they sat. There was also no distinct nucleus inside them." howstuffworks 2024-02-27 and scienceabc 2023-02-07 (with good illustration). It appears that they legitimately do grow and bud, although I agree that it is likely folklore in the notion that humans would have observed this as a change rather than deduced it from static appearance. SamuelRiv (talk) 13:49, 4 October 2024 (UTC)

I guess the absence of a nucleus doesn't tell you whether there was a nucleus before diagenesis reorganized the system. Some of them certainly have a nucleus. Porosity and chemical gradients are presumably involved somehow in the cementation process. This is a nice picture of similar structures in situ where you can see that the depositional structures are preserved regardless of the variation in cementation. Here's another one. Sean.hoyland (talk) 15:34, 4 October 2024 (UTC)