Wikipedia:Reference desk/Archives/Science/2023 May 24

= May 24 =

Would an ocean of electrons be a superfluid?
There is no doubt that an ocean of electrons would be a super conductor, but would one also be a superfluid? Byron Forbes (talk) 00:22, 24 May 2023 (UTC)


 * You'd need an extremely large force to hold it together. What do you imagine the inter-electron distance to be? Using the same distance as the inter-molecule distance of water, 0.31&thinsp;nm, the number of electrons in 1&thinsp;cm3 of electron fluid equals the number of water molecules in 1&thinsp;cm3 of water. A back-of-the-envelope calculation comes out at 33.5×1018 electrons, which will have a combined charge of 5.36&thinsp;C. Imagining this as consisting of two parts, each with halve this charge, separated by a distance of 1&thinsp;cm, the electrostatic force by which they repel each other will exceed 600&thinsp;TN. So you cannot just put this in a viscometer; to determine its viscosity needs to be done theoretically. I am inclined to think that the electrons will pack in a regular lattice to minimize the potential energy; deforming it may then require a huge amount of energy. But I am not enough of a theoretical physicist to make a more definite assertion. --Lambiam 13:12, 24 May 2023 (UTC)
 * You may be interested in Randall Munroe's What If question about putting a large mass of electrons together. It doesn't end well. Blythwood (talk) 17:12, 24 May 2023 (UTC)
 * Superconductivity is actually the flow of superfluid electron liquid through a conductor. Ruslik_ Zero 20:13, 25 May 2023 (UTC)
 * Of course! :) Byron Forbes (talk) 20:54, 25 May 2023 (UTC)
 * Superfluidity ir a must, But |but it is not enough. I wonder if Cooper pairs will not emerge at near absolute zero, if you worked hard enough to contain them. Zarnivop (talk) 19:36, 26 May 2023 (UTC)

Energy of particles in a collider.
Does anyone know how they calculate this?

Is it as simple as the force of the E field multiplied by the distance of the accelerator multiplied by how many times the particle has gone through the accelerator?

So E = F * D * laps? Byron Forbes (talk) 03:59, 24 May 2023 (UTC)


 * That would be true for a cyclotron, though there you would usually just use the maximum possible radius to get the final energy of the particles. I you are talking about a synchrotron (like the LHC) it's more complicated as you can't use static electric fields but need some kind of resonator (e.g. a microwave cavity) in which an standing electromagnetic wave is induced. The energy gain per lap then depends on when in the phase of the em wave your particle arrives at the resonator. A little counter-intuitively you don't want your particle to get there when the E-field is strongest as that will mean losing most of you particles (then ones that are not perfectly in phase). Additionally, the field won't be static for the time it takes the particle to cross the gap and it likely also not be homogenous at the edges.140.181.85.173 (talk) 11:33, 24 May 2023 (UTC)
 * Do you know if it's assumed that the E field is able to impart the same force at relativistic speeds as non relativistic?
 * I know we don't know exactly what an E field is, but we know they change at c so might they not be able to impart all of their force to a relativistic particle? Byron Forbes (talk) 23:47, 24 May 2023 (UTC)
 * The E-field is still imparts the same energy to the particle even close to c but this increase in energy no longer translates into an increase in velocity (or just a very tiny one). Another thing to consider, especially for light particles like electrons, is the energy loss through synchrotron radiation which scales with the fourth power of the Lorentz factor and is a big limiting factor when trying to accelerate electrons with circular accelerators. 140.181.85.173 (talk) 07:10, 25 May 2023 (UTC)

Pest detection
In a large food warehouse, or in a big city, are microphones and cameras used to detect rodents? What about microphones to detect termites or other insects? If cameras and microphones aren't being used, are there any startup companies or academic work being done on it? Rich (talk) 20:13, 24 May 2023 (UTC)
 * Cameras are definitely in use. Abductive  (reasoning) 20:49, 24 May 2023 (UTC)
 * This mentions sound detection for agricultural applications. This discusses the state of technology as of 2021 for "Stored product" applications.  -- Jayron 32 15:13, 25 May 2023 (UTC)