Wikipedia:Reference desk/Archives/Science/2024 February 19

= February 19 =

Why the physical and chemical properties of element 0 is very hard to find?
Why the physical and chemical properties of element 0 (neutronium) is very hard to find (e.g. it should be as noble as helium and neon, and should be gas in the room temperature, maybe neutronium is ideal gas)? The half-life of the free neutron is longer than the half-life of the longest- lived isotope of the elements with atomic number >= 107, and some physical and chemical properties of the elements with atomic number >= 107 are already known. 61.224.147.34 (talk) 07:50, 19 February 2024 (UTC)
 * If you look at our article your will read it is a "hypothetical substance". But see Neutron, the conditions to form these are not available in the Solar System, so anything known would be hypothetical. Perhaps some clues can be gleaned by neutron star collisions. Neutrons stored in a bottle would be a dilute gas. They do not interact with light, and so is transparent. Graeme Bartlett (talk) 08:42, 19 February 2024 (UTC)
 * I don't think neutrons can be stored in a bottle. Since neutrons are neutral they do not feel the electromagnetic Coulomb barrier that keeps atoms and molecules in the bottle. For the same reason it makes little sense to talk about "chemical properties". These are determined by the electrons in atoms; neutronium has no electrons, and neutrons cannot capture electrons to form negative ions. --Wrongfilter (talk) 09:03, 19 February 2024 (UTC)
 * See ultracold neutrons for what to make your neutron storage bottle from. It appears that beryllium is best. (But it's not transparent) Graeme Bartlett (talk) 09:37, 19 February 2024 (UTC)
 * That's very interesting, thanks! Pity the article doesn't provide enough information to understand how that works. --Wrongfilter (talk) 09:52, 19 February 2024 (UTC)
 * Apparently it works by the strong interaction, as expected. Which basically illustrates why element 0 doesn't really have chemical properties; it has no electrons, which would be needed for such things like forming bonds and a normal condensed phase. Double sharp (talk) 10:24, 20 February 2024 (UTC)
 * Also, neutrons are only stable when inside atomic nuclei: free neutrons (which 'neutronium gas' would consist of) decay with a mean lifetime of about 141/2 minutes and a half-life of a little over 10 minutes. {The poster formerly known as 87.81.230.195} 176.24.45.226 (talk) 13:54, 25 February 2024 (UTC)
 * That's not the problem. As noted by the OP, all known bohrium and hassium isotopes have shorter half-lives than free neutrons, yet we know some chemistry of those elements. The problem is that a free neutron doesn't have electrons and therefore can't have chemistry. Double sharp (talk) 18:16, 25 February 2024 (UTC)

Has any gluon's velocity ever been measured?
I'm asking, because for the time being, only two particles, considered to have no mass, have been detected, one of which has empirically turned out to have a velocity, being (or sufficiently close to) the well known constant velocity C, if that particle (namely photon) is in a medium, being (or sufficiently close to) an absolute vacuum. So my question is: what about the other particle (namely gluon), as far as its measured velocity (especially in a vacuum) is concerned? HOTmag (talk) 13:04, 19 February 2024 (UTC)


 * The scale at which gluons operate (see } is less than $0.8 fm$ = $0.8 m$. At the speed of light, the time scale is less than $3 s$ or $3 rontoseconds$. The inverse of the hyperfine transition frequency of 133Cs used in atomic clocks is about $0.1 nanoseconds$ or $0.1 s$, 16 orders of magnitude larger. I do not think technology is up to measuring such short time spans. Apart from technological limitations, I think there are also fundamental limitations baked into the laws of physics as we understand them, such as quantum uncertainty. I can't think of any kind of experimental setup that might clock a gluon as being at some definite position. Bounds on gluon mass will have to be deduced from energy budget calculations of high-energy collisions. --Lambiam 17:59, 19 February 2024 (UTC)
 * Thank you for your (disappointing) reply. I hoped the gluon's velocity could be measured somehow, because I wanted to make sure that the well known hypothesis - stating that no massless particle can be a tachyon - could be emprically proved also for particles other than photons, but according to your reply I understand we will have to stay in the boundary of photons alone for emprically proving this hypothesis - which I suspect is not sufficiently reliable while it has been empirically proved for photons only. That no massive paricle can be a tachyon, is a well established fact, or rather a mathematicllay proved fact - deriving from the relativistic equation of momentum, but this fact cannot be mathematically proved for massless particles, for which we can only rely on experiments, which have actually been carried out for photons only, unfortunately, as I understand from your reply. What a pity... HOTmag (talk) 08:00, 20 February 2024 (UTC)