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IANAP, but I thought that quantum field theory (which isn't incredibly controversial) already treats particles as merely emergent convenient ways to describe co

IANAP, 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.

tux3 1y ago
A regular particle isn't really emergent, it corresponds 1:1 to the excitation of the field Quasiparticles arise out of a collection of particles, that's why they're emergent
- dinfinity 1y ago
  > A regular particle isn't really emergent, it corresponds 1:1 to the excitation of the field Maybe 'emergent' was the wrong word here. I meant that particles are convenient ways of describing behavior of the fields in many (but not all) cases, with the fields themselves considered to be the (more) fundamental description of reality.
  - colechristensen 1y ago
    Eh, in the wave-particle duality wars you may have been swayed a bit too strongly into the wave camp. Quantization exists and isn't just a convenience.
    - dinfinity 1y ago
      What? QFT doesn't preclude quantization at all. You're attacking a weird straw man here.
      - soulofmischief 1y ago
        And wave particle duality isn't some kind of scientific debate with camps on both sides.
    - rcxdude 1y ago
      Quantization exists because of the waves though. It's a consequence of standing waves being produced when an excitation is confined. It's not AFAIK an axiom of QFT, more an emergent result.
jfengel 1y ago
QFT is perfect for a single particle, but it gets harder to describe the behavior of particles en masse. It's super hard to find simplifications that reveal emergent behavior.
bkcooper 1y ago
I would assume that's mostly a function of this being for a general audience. Yes, you absolutely can talk about quasiparticles using techniques adapted from QFT. I don't know if Landau originally conceived of it that way, but there were definitely a bunch of Soviet physicists shortly after him who did.
EvgeniyZh 1y ago
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."

tux3 1y ago

A regular particle isn't really emergent, it corresponds 1:1 to the excitation of the field Quasiparticles arise out of a collection of particles, that's why they're emergent

dinfinity 1y ago
> A regular particle isn't really emergent, it corresponds 1:1 to the excitation of the field Maybe 'emergent' was the wrong word here. I meant that particles are convenient ways of describing behavior of the fields in many (but not all) cases, with the fields themselves considered to be the (more) fundamental description of reality.
- colechristensen 1y ago
  Eh, in the wave-particle duality wars you may have been swayed a bit too strongly into the wave camp. Quantization exists and isn't just a convenience.
  - dinfinity 1y ago
    What? QFT doesn't preclude quantization at all. You're attacking a weird straw man here.
    - soulofmischief 1y ago
      And wave particle duality isn't some kind of scientific debate with camps on both sides.
  - rcxdude 1y ago
    Quantization exists because of the waves though. It's a consequence of standing waves being produced when an excitation is confined. It's not AFAIK an axiom of QFT, more an emergent result.

jfengel 1y ago

QFT is perfect for a single particle, but it gets harder to describe the behavior of particles en masse. It's super hard to find simplifications that reveal emergent behavior.

bkcooper 1y ago

I would assume that's mostly a function of this being for a general audience. Yes, you absolutely can talk about quasiparticles using techniques adapted from QFT. I don't know if Landau originally conceived of it that way, but there were definitely a bunch of Soviet physicists shortly after him who did.

EvgeniyZh 1y ago

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."