3 ms·

Quasiparticles, as usually defined, are embedded in some bulk substrate. So electron holes exist as part of a chunk of metal, for example. Phonons are mechanica

Quasiparticles, as usually defined, are embedded in some bulk substrate. So electron holes exist as part of a chunk of metal, for example. Phonons are mechanical vibrations of some bulk matter. They're not made of any particular piece of the bulk matter, like a molecule is made of atoms or a proton is made of quarks; they're emergent phenomena (an electron hole is "made of" not an electron- it's only a hole because of the matter surrounding it)., Protons and neutrons, on the other hand, exist in free space. You can accelerate protons and fire them at the moon (or whatever). You can't do that with phonons or electron holes. They are composite particles (not fundamental) but they aren't quasiparticles. (quarks, weirdly, can't exist in free space. If you try to pull a proton apart you will have to put so much energy into it that you generate more quarks which then immediately couple up with the proton's quarks, possibly in a novel combination producing new composite particles. So you have to study composite particles to study quarks)

zmgsabst 4y ago
I’m unaware of any “free space” which doesn’t have a mass of quarks and gluons oscillating, so I’m not sure I follow. In fact, the mass of the proton arises from disrupting that typical quark-gluon oscillation. I’m also unsure that’s true, even ignoring that issue: I can shoot an electron hole by moving the chunk of metal it’s situated in, the same way I can shoot a proton by shooting the constituent quarks and gluons. You can’t separate an electron hole from the metal, but you also can’t separate the proton from quarks and gluons.
- roywiggins 4y ago
  Sure, you can take it further and declare that electrons are actually quasiparticles because they're actually excitations of surrounding fields, if you want. I'm not sure what it gets you though- there are real differences between an electron hole and an electron and that's what the quasi- moniker is getting at.
  - zmgsabst 4y ago
    Sure — but I wasn’t talking about electrons, which as far as we can tell are fundamental particles. I was talking about protons and neutrons. What distinguishes a proton, which gains its mass as a hole in the quark-gluon fuzz permeating the universe, from an electron hole in metal? I think that gets you something: You can understand protons and neutrons as holes in the “crystallized” space that came out of the universe cooling to its current state — that the fuzz of quarks and gluons is something like a “metal” in which protons and neutrons are “holes”.
    - jjk166 4y ago
      It is mathematically useful to think of space as being full of virtual particles including quarks, gluons, and electrons, but there isn't actually a quark-gluon "fuzz" permeating the universe. There was such a physically real fuzz, or more properly a quark-gluon plasma in the extremely early universe (the first few microseconds) which "froze" into hadrons, but this is more akin to water in a cloud condensing into snow. You can certainly formulate the math such that hadrons, or any other particle for that matter, behave like holes in a substrate, indeed this is the basis of quantum field theory. But unlike quasiparticles where that substrate is something in the universe like a block of metal, for regular particles the substrate is the universe.
      - zmgsabst 4y ago
        I appreciate the time people are taking to walk me through this confusion! - - - - - > You can certainly formulate the math such that hadrons, or any other particle for that matter, behave like holes in a substrate, indeed this is the basis of quantum field theory. Okay — I’m with you here. > But unlike quasiparticles where that substrate is something in the universe like a block of metal, for regular particles the substrate is the universe. Okay — but so what? Why is it different that it’s within a metal than the stuff the universe cooled into? In both cases, we’re discussing an emergent object with new quantum numbers in some substrate: - electron holes are a hole in the fuzz of electrons in metals - protons are a hole in the background fuzz of quarks and gluons in cold aether > It is mathematically useful to think of space as being full of virtual particles including quarks, gluons, and electrons, but there isn't actually a quark-gluon "fuzz" permeating the universe. I’m not sure I follow: proton mass is related to flux tubes suppressing that fuzz in the area of the proton. Empty space has energy, which manifests as that particle fuzz. https://en.wikipedia.org/wiki/Vacuum_energy https://en.wikipedia.org/wiki/Vacuum_energy

zmgsabst 4y ago

I’m unaware of any “free space” which doesn’t have a mass of quarks and gluons oscillating, so I’m not sure I follow. In fact, the mass of the proton arises from disrupting that typical quark-gluon oscillation. I’m also unsure that’s true, even ignoring that issue: I can shoot an electron hole by moving the chunk of metal it’s situated in, the same way I can shoot a proton by shooting the constituent quarks and gluons. You can’t separate an electron hole from the metal, but you also can’t separate the proton from quarks and gluons.

roywiggins 4y ago
Sure, you can take it further and declare that electrons are actually quasiparticles because they're actually excitations of surrounding fields, if you want. I'm not sure what it gets you though- there are real differences between an electron hole and an electron and that's what the quasi- moniker is getting at.
- zmgsabst 4y ago
  Sure — but I wasn’t talking about electrons, which as far as we can tell are fundamental particles. I was talking about protons and neutrons. What distinguishes a proton, which gains its mass as a hole in the quark-gluon fuzz permeating the universe, from an electron hole in metal? I think that gets you something: You can understand protons and neutrons as holes in the “crystallized” space that came out of the universe cooling to its current state — that the fuzz of quarks and gluons is something like a “metal” in which protons and neutrons are “holes”.
  - jjk166 4y ago
    It is mathematically useful to think of space as being full of virtual particles including quarks, gluons, and electrons, but there isn't actually a quark-gluon "fuzz" permeating the universe. There was such a physically real fuzz, or more properly a quark-gluon plasma in the extremely early universe (the first few microseconds) which "froze" into hadrons, but this is more akin to water in a cloud condensing into snow. You can certainly formulate the math such that hadrons, or any other particle for that matter, behave like holes in a substrate, indeed this is the basis of quantum field theory. But unlike quasiparticles where that substrate is something in the universe like a block of metal, for regular particles the substrate is the universe.
    - zmgsabst 4y ago
      I appreciate the time people are taking to walk me through this confusion! - - - - - > You can certainly formulate the math such that hadrons, or any other particle for that matter, behave like holes in a substrate, indeed this is the basis of quantum field theory. Okay — I’m with you here. > But unlike quasiparticles where that substrate is something in the universe like a block of metal, for regular particles the substrate is the universe. Okay — but so what? Why is it different that it’s within a metal than the stuff the universe cooled into? In both cases, we’re discussing an emergent object with new quantum numbers in some substrate: - electron holes are a hole in the fuzz of electrons in metals - protons are a hole in the background fuzz of quarks and gluons in cold aether > It is mathematically useful to think of space as being full of virtual particles including quarks, gluons, and electrons, but there isn't actually a quark-gluon "fuzz" permeating the universe. I’m not sure I follow: proton mass is related to flux tubes suppressing that fuzz in the area of the proton. Empty space has energy, which manifests as that particle fuzz. https://en.wikipedia.org/wiki/Vacuum_energy https://en.wikipedia.org/wiki/Vacuum_energy