Wikipedia:Reference desk/Archives/Science/2024 September 4

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September 4

Cat

Can anyone explain how it is technically possible for a cat to be simultaneously alive and dead at the same time? I've seen this referenced in pop culture a few times, but I don't understand. 146.200.107.107 (talk) 00:59, 4 September 2024 (UTC)

See Schrödinger's cat and Schrödinger's cat in popular culture. It's one of those things that if you understand it you probably don't really know what it's really about. DuncanHill (talk) 01:14, 4 September 2024 (UTC)

The cat knows if it's alive. It's just that someone outside the cat's box might not know. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:51, 4 September 2024 (UTC)

If the cat in the box has a philosophical bend and knows Latin as well as the Schrödinger equation and wave function collapse, it might think, Miror si vivo vel non. Ergo vivo. But, actually, we as outside observers do not know whether the cat knows anything. If it does not know whether it is alive or dead, it is more likely dead. The cat may be in a superposition, though, of a state of knowing and a state of not knowing it is alive.  --Lambiam 08:43, 4 September 2024 (UTC)

Cats that are alive know they're alive. They don't have to overthink it. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:32, 4 September 2024 (UTC)

The question is, does a cat count as an observer for quantum physical purposes? And can its quantum state be collapsed inside the box but not yet outside? {The poster formerly known as 87.81.3230.195} 94.6.83.137 (talk) 12:24, 4 September 2024 (UTC)

This all sounds like animal cruelty. Better they should seal Schrodinger in a box and see how he likes it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:18, 4 September 2024 (UTC)

To make it clear to others, this was a thought experiment that Schrödinger described to illustrate his opinion that the Copenhagen interpretation of quantum mechanics led to (in his opinion) absurd conclusions: neither he nor any other physicist has proposed carrying it out with a real cat. For one thing, the cat would likely have to be listed as one of the authors of the resulting paper, which would be silly :-). {The poster formerly known as 87.81.230.195} 94.6.83.137 (talk) 04:30, 6 September 2024 (UTC)

Silly indeed. That could never happen. PianoDan (talk) 03:35, 10 September 2024 (UTC)

Whenever quantum whatever is mentioned in pop culture it's probably better to just enjoy it as it is, because it's probably completely off the rails.

If you accept that reality is real, then a macroscopic event really happens in real life and the cat really lives or dies, one or the other. So the original trigger to the experiment (a beta decay, say) is probabilistic based on a superposition of states. Note we need to remain ignorant for as long as possible as to whether the particle has decayed if we keep the superposition across the system -- see Zeilinger's quote in the superposition article -- you can see how that would be a problem if you expect the cat itself to be entangled with the particle. The question is, when and by what nature does the system decohere? In some sense, we know how to describe the experiment from when it begins to some midpoint and how to describe it from some midpoint to when it ends, but somewhere in the middle the magician critically slips the other cards into his pocket -- so when did that happen (or maybe it wasn't a card trick to begin with)? SamuelRiv (talk) 18:21, 4 September 2024 (UTC)

I don't get the other people's responses, but I thought it had to do with multiple universes. That is, after an incident happens to a cat in a box, the scenario is split into 2 additional universes: 1 in which you open the box and the cat is dead, and the other where you open the box and the cat is alive. 66.99.15.162 (talk) 20:55, 4 September 2024 (UTC).

The many-worlds interpretation is just one of many attempted interpretations of quantum mechanics. Although Hugh Everett III is usually credited as the originator of the interpretation, he merely aimed at presenting a mathematical model including "measurements". The popularization framing this as splitting into multiple universes is due to Bryce DeWitt; Everett had no high opinion of this, considering it "bullshit".^[1]  --Lambiam 22:41, 4 September 2024 (UTC)

Self-moved to New Question Sep 10 (talk) 04:20, 10 September 2024 (UTC)

Colour of PmCl₃

At the infobox for promethium(III) chloride we find two different sources for this compound's colour, one calling it purple and the other calling it yellow. Probably few have seen this compound (considering the short half-life of Pm), but what's the story here? Is it perhaps similar to how the colour of NdCl₃ varies under lighting conditions (between purple and yellow as well)? Double sharp (talk) 04:40, 4 September 2024 (UTC)

I would expect most trivalent compounds of promethium have similar colour. But there may also be radiation damage to the material. Also perhaps the compound is not pure and contains neodymium. Graeme Bartlett (talk) 21:49, 6 September 2024 (UTC)

Checking my textbook, (Advanced Inorganic Chemistry by Cotton and Wilkinson) it says trivalent salts of Pm are pink. So none of the above. Graeme Bartlett (talk) 10:44, 8 September 2024 (UTC)

Native germanium

Resolved

Is native germanium actually a thing? Mindat lists it, but the source is rather lacking in details, and does not mention Ge proportions beyond 37.6%. Maybe I'm misunderstanding the paper. Double sharp (talk) 13:08, 4 September 2024 (UTC)

According to the definition in Native element mineral, it would be counted as "native", even though it is an intermetallic compound with palladium, rhodium (or possibly platinum and nickel in your ref). But not known as pure or close to pure as a mineral. Graeme Bartlett (talk) 00:44, 5 September 2024 (UTC)

Thanks. Double sharp (talk) 15:44, 6 September 2024 (UTC)