One of the properties of electrons is spin. The stern-gerlach expt demonstrated spin on a macrosopic scale. Does spin play a role in the change of conductivity? In other words, does an externally applied magnetic field change the temperature at which superconductivity occurs or perhaps the slope of rising resistivity?
'Strange metals' point to a whole new way to understand electricity
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Re: 'Strange metals' point to a whole new way to understand electricity
#42Earlier quoted context omitted.
But the specific word they were looking for is "quintic". (And the corresponding word for 4th-degree, in case anyone is curious, is "quartic"; one sometimes sees "biquadratic", which unfortunately is also sometimes used to describe a particular subset of quartics.)
Oh right, silly me. Wow, my own vocabulary deserted me there, huh? Yeah I think generally "sextic" is the highest you see before people stop doing that, and that one's somewhat uncommon I'd say. ("Quintic" is actually fairly common, contrary to what I said earlier, oops.) The fact that seventh-degree would be "septic" might be one reason stop with the words at that point!
I'm pretty sure that more than half the times I've seen "quintic" are in one single context: talking about the fact that while you can solve polynomial equations of degree 1-4 by doing arithmetic and taking n'th roots, this stops being possible once you get as far as quintic equations. (The "insolubility of the quintic".)
Re: 'Strange metals' point to a whole new way to understand electricity
#43So superconductivity is a laminar flow of electron goop? Ok, it's different in that liquid flows through pipes and electrons flow through crystal lattices or whatever, so electrons go between and around the material while liquid is bounded by it. It makes me speculate that electron flow through a metal is sort of like liquid flowing through a compressible boundary tube, whereas flow through a non-metal has rigid wall…
TL;DR: the analogy is helpful at a high level, but has limitations when you look closely. > Ok, it's different in that liquid flows through pipes and electrons flow through crystal lattices or whatever, so electrons go between and around the material while liquid is bounded by it. This is not perfect, but it works at a high level. The main difference with e.g. water flows is that what restricts electron flux is traps…
How should we visualize what pushes the electron goop forward? If it's like water pressure, that would make the hindmost goop bunch up with the foremost goop.
Presumably electricity has something to do with positive charge at the back of the 'pipe' and negative charge at the 'front' (or have I got those backward?), perhaps a better visualization would be that they're all rolling down an inclined plane together?
Re: 'Strange metals' point to a whole new way to understand electricity
#44Earlier quoted context omitted.
Why don't photons have a position operator?
It’s really not accurate to say that a photon has no position at all. How would a photodiode work? You have to be careful with this stuff. https://physics.stackexchange.com/questions/492711/whats-the...
Photons certainly appear to have a real physical location with 1e9 FPS imaging capabilities:
"Visualizing video at the speed of light — one trillion frames per second" (2012) https://youtube.com/watch?v=EtsXgODHMWk&
But is there an identity function for a photon(s), and is "time-polarization" necessary for defining an identity function for photons?
Re: 'Strange metals' point to a whole new way to understand electricity
#45Earlier quoted context omitted.
TL;DR: the analogy is helpful at a high level, but has limitations when you look closely. > Ok, it's different in that liquid flows through pipes and electrons flow through crystal lattices or whatever, so electrons go between and around the material while liquid is bounded by it. This is not perfect, but it works at a high level. The main difference with e.g. water flows is that what restricts electron flux is traps…
How should we visualize what pushes the electron goop forward? If it's like water pressure, that would make the hindmost goop bunch up with the foremost goop. Presumably electricity has something to do with positive charge at the back of the 'pipe' and negative charge at the 'front' (or have I got those backward?), perhaps a better visualization would be that they're all rolling down an inclined plane together?
Current flows due to a difference in electric potential, which is called voltage. This is similar to the difference in gravitational potential that causes a ball to roll downhill. If imagining electricity like water, then voltage is lifting up one end of the pipe (or water going over a waterfall of a certain height).
Re: 'Strange metals' point to a whole new way to understand electricity
#46IANAP, but I thought that quantum field theory (which isn't incredibly controversial) already treats particles as merely emergent convenient ways to describe common excitations of the fields. I'm surprised it isn't mentioned here at all.
Theoretical condensed matter here (though not an expert on strange metals specifically).
The idea is that in a quantum many-body system, a (low-energy) state can often be represented as a set of independent excitations of the field, which are called quasiparticles. The "particle" picture for the Fermi liquid already operates in a framework of quantum fields. "No quasiparticles" means that there is no such representation, i.e., you can't say something like "these two states differ by an addition of a particle with such-and-such properties."