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Is it possible to have a quantum theory where there is no "measurement"? The universe simply evolves according to the Dirac or Shroedinger equations, and the ph

Is it possible to have a quantum theory where there is no "measurement"? The universe simply evolves according to the Dirac or Shroedinger equations, and the phenomenon that we call measurement is an emergent, statistical property? The motivation for the question is that in quantum physics there are two phases: 1. The phase where everything is quantum, and things evolve according to Dirac or Schroedinger. The state of a system at any given time then determines its state at all times in the future and in the past. Everything is in all possible classical states at once. 2. Some measurement happens that is irreversible. The quantum state collapses, and information about the quantum state before the collapse is lost. The result is a single classical state. I haven't read TFA, but having something like phase 2 be emergent from phase 1 seems like a major breakthrough. Phase 2 is then an illusion. This seems better than the status quo. (I am not a physicist).

sampo 4y ago
> Is it possible to have a quantum theory where there is no "measurement"? The universe simply evolves according to the Dirac or Shroedinger equations, and the phenomenon that we call measurement is an emergent, statistical property? Doesn't the many-worlds interpretation fit your description? It of course has it's own weirdness. https://en.wikipedia.org/wiki/Many-worlds_interpretation https://en.wikipedia.org/wiki/Many-worlds_interpretation
- ogogmad 4y ago
  Is MWI (which appears to only assert that there is a wavefunction for the whole universe) a form of superdeterminism?
  - drdeca 4y ago
    Not really, I don’t think? Just determinism (sorta.)
gus_massa 4y ago
Yes. My preferred version is something-something-decoherence https://en.wikipedia.org/wiki/Quantum_decoherence https://en.wikipedia.org/wiki/Quantum_decoherence The people that work in that are call it "Decoherence", but it's not finished, there are still a lot of details to fix, and perhaps it will need still like 50 or 100 years of hard work before it's completed. So it's too green and I prefer a funny name like "something-something-decoherence" to avoid confusion. And perhaps it's the wrong explanation.

sampo 4y ago

> Is it possible to have a quantum theory where there is no "measurement"? The universe simply evolves according to the Dirac or Shroedinger equations, and the phenomenon that we call measurement is an emergent, statistical property? Doesn't the many-worlds interpretation fit your description? It of course has it's own weirdness. https://en.wikipedia.org/wiki/Many-worlds_interpretation https://en.wikipedia.org/wiki/Many-worlds_interpretation

ogogmad 4y ago
Is MWI (which appears to only assert that there is a wavefunction for the whole universe) a form of superdeterminism?
- drdeca 4y ago
  Not really, I don’t think? Just determinism (sorta.)

gus_massa 4y ago

Yes. My preferred version is something-something-decoherence https://en.wikipedia.org/wiki/Quantum_decoherence https://en.wikipedia.org/wiki/Quantum_decoherence The people that work in that are call it "Decoherence", but it's not finished, there are still a lot of details to fix, and perhaps it will need still like 50 or 100 years of hard work before it's completed. So it's too green and I prefer a funny name like "something-something-decoherence" to avoid confusion. And perhaps it's the wrong explanation.