Wikipedia:Reference desk/Archives/Science/2021 April 8
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April 8[edit]
Superfluids[edit]
Why can't the heavier noble gases (neon, argon, etc.) go superfluid at low temperature like helium? Double sharp (talk) 14:17, 8 April 2021 (UTC)
- Superfluidity is a quantum effect caused by the fact that bosons can occupy simultaneous quantum states while fermions cannot. So, you need two things to make a superfluid 1) a boson which 2) has a relatively small number of possible quantum states. Atomic helium-4 (and also dimeric helium-3 and atomic lithium-6) meet both of those conditions. Larger noble gases, like neon and argon, are likely lacking in one or the other things: either they are not bosons (i.e. they have a net half-integer quantum spin, making them fermions) or they have too many sub-particles, meaning the number of quantum states that each individual atom can occupy is so large that the ensemble of atoms cannot "line-up" in the same quantum state necessary for superfluidity. --Jayron32 14:40, 8 April 2021 (UTC)
- Each noble gas has a stable boson as its most abundant isotope. One of the most commonly used atoms for forming a Bose–Einstein condensate is rubidium-87, so larger nuclei can achieve a large occupation number in the ground state. Any of the noble gases should be able to form a superfluid, if only they were fluid at the relevant temperature. --Amble (talk) 15:25, 8 April 2021 (UTC)
- Helium is special because it remains a liquid all the way to absolute zero. (As long as the pressure isn't too high; it can freeze at higher pressure). The other noble gases only have a liquid state within a range of temperatures. Below that line, regardless of pressure, they form a solid. They don't go superfluid because they aren't fluid at the relevant temperatures. --Amble (talk) 14:55, 8 April 2021 (UTC)
- LOL, now I feel stupid for missing that. Thanks to both of you for the answers. Double sharp (talk) 15:06, 8 April 2021 (UTC)
- Once you start thinking about the "super" part, it's easy to forget about the "fluid". --Amble (talk) 15:26, 8 April 2021 (UTC)
- Could they form a supersolid, then? I'm a little unclear on just how those are supposed to behave. --Trovatore (talk) 00:57, 10 April 2021 (UTC)
- I don't know. Just from the article, the examples of supersolidity are in BEC gases, not natural crystals. --Amble (talk) 14:33, 11 April 2021 (UTC)
- Can a classical crystal become a Bose–Einstein condensate when sufficiently cooled? Our article treats the case of ideal gases and weakly interacting particles (I assume this means there's limited interaction, not that the interaction is via the weak force), but doesn't really say what happens for highly interacting particles (maybe the theory becomes intractable?). --Trovatore (talk) 18:23, 14 April 2021 (UTC)
- I don't know. Just from the article, the examples of supersolidity are in BEC gases, not natural crystals. --Amble (talk) 14:33, 11 April 2021 (UTC)
- Could they form a supersolid, then? I'm a little unclear on just how those are supposed to behave. --Trovatore (talk) 00:57, 10 April 2021 (UTC)
- Once you start thinking about the "super" part, it's easy to forget about the "fluid". --Amble (talk) 15:26, 8 April 2021 (UTC)
- LOL, now I feel stupid for missing that. Thanks to both of you for the answers. Double sharp (talk) 15:06, 8 April 2021 (UTC)
If a doctor does a perineal surgery/incision on a man by hand, just how easy would it be for them to subsequently access this man's prostate?[edit]
If a doctor does a perineal surgery/incision on a man by hand, just how easy would it be for them to subsequently access this man's prostate without the help of any robots or anything like that? Futurist110 (talk) 21:45, 8 April 2021 (UTC)
- This again? --Jayron32 13:52, 9 April 2021 (UTC)
- This does not involve reproduction. The prostate is not a reproductive organ. Or am I not allowed to ask any questions about surgery in general here? Because I thought that the prohibition was limited to questions of a reproductive nature. Futurist110 (talk) 20:32, 9 April 2021 (UTC)
- You must know that this is similar in theme, seeing as the prostate is part of the male reproductive system. This is not dissimilar from your constant line of questions about vasectomies, for example. Why do you feel the need to ask questions on this theme in the first place? --OuroborosCobra (talk) 21:49, 9 April 2021 (UTC)
- Sheer curiosity. Or is that not an acceptable reason? Futurist110 (talk) 00:02, 10 April 2021 (UTC)
- If you were to go to medical school and study urology, it might well answer your questions now and in future. ←Baseball Bugs What's up, Doc? carrots→ 09:35, 10 April 2021 (UTC)
- Sheer curiosity. Or is that not an acceptable reason? Futurist110 (talk) 00:02, 10 April 2021 (UTC)
- "The prostate is a part of the male reproductive system". [1] Alansplodge (talk) 21:52, 9 April 2021 (UTC)
- You must know that this is similar in theme, seeing as the prostate is part of the male reproductive system. This is not dissimilar from your constant line of questions about vasectomies, for example. Why do you feel the need to ask questions on this theme in the first place? --OuroborosCobra (talk) 21:49, 9 April 2021 (UTC)
- This does not involve reproduction. The prostate is not a reproductive organ. Or am I not allowed to ask any questions about surgery in general here? Because I thought that the prohibition was limited to questions of a reproductive nature. Futurist110 (talk) 20:32, 9 April 2021 (UTC)