Epistemic view of the wave function leads to superluminal signal

In summary, a question has been raised about the possibility of superluminal communication in quantum mechanics if the same state is represented by two distinct wave functions. A reference to the Wheeler-Zurek book "Quantum theory and measurement" is suggested for sources up to 1982, and a resource on modern topics in QM foundations is recommended. The PBR theorem is mentioned and it is noted that it is similar to Einstein's incompleteness argument. The discussion then moves on to the role of Born's rule in the relativistic regime and how it is addressed by QFT. Finally, the conversation turns to a discussion about the second particle in an entangled pair and what happens to it when the first particle is measured in
  • #36
MichPod said:
But how does this "detection event" happen to appear only at one particular coordinate, while the quantum field is spread over the whole screen? I.e. what causes the "wave collapse" on measurement in your way of interpretation?
Presumably the chaoticity of the macroscopic nonlocal observables (field correlations) of the screen, together with conservation of energy. The latter implies that there can be at most one detection event, the former means that it happens at an unpredictable position.

That field intensity is responsible for the firing rate of the Poisson process at one spot of the screen (i.e., the occurrence of detection events) is a local feature described in any textbook of quantum optics, e.g., in Mandel and Wolf.
 
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  • #37
A. Neumaier said:
the only thing left of the particle picture is the detection event.

But isn't it that in cathode tube and cloud chamber the charged particles are deflected by the mass/charge ratio,this sounds even weirder to me than EPR if the electrons were all jumbled up yet displayed individuality.
 
  • #38
ftr said:
the charged particles are deflected by the mass/charge ratio
The electron field of a cathode ray also has a definite mass/charge ratio. One doesn't need individual electrons for that.
 
  • #39
A. Neumaier said:
There is no consistent relativistic multiparticle theory,

do you mean that there is no consistant QFT bound state, or Dirac multiparticle(>2).
 
  • #40
ftr said:
do you mean that there is no consistent QFT bound state, or Dirac multiparticle(>2).
In an interacting relativistic QFT there may be bound states, but one cannot say that these are composed of 2 or 3 particles, say. There are no multiparticle states, since the Hilbert space of a QFT is not a Fock space. See https://physics.stackexchange.com/questions/398200/

This means that interacting relativistic QFTs are field theories, not multiparticle theories. Particles exist only as asymptotic (i.e., approximate, essentially free) states.
 
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  • #41
A. Neumaier said:
Presumably the chaoticity of the macroscopic nonlocal observables (field correlations) of the screen, together with conservation of energy. The latter implies that there can be at most one detection event, the former means that it happens at an unpredictable position.

That field intensity is responsible for the firing rate of the Poisson process at one spot of the screen (i.e., the occurrence of detection events) is a local feature described in any textbook of quantum optics, e.g., in Mandel and Wolf.

But what then prevents a creation of a superimposed state of a screen+electron field where each possible detection event of the electron "happened" with some probability amplitude? We know that a linearity of Shredinger equation in QM does not prevent that to happen yet the measurement postulate demands a collapse to "happen". Then what is different in principle when you consider QFT or your interpretation of QFT? (disclaimer: I do not know qft nor quantum optics and I cannot learn enough just in one morning, so I cannot make any argument, just want to understand briefly how you resolve this problem, if possible).
 
  • #42
MichPod said:
But what then prevents a creation of a superimposed state of a screen+electron field where each possible detection event of the electron "happened" with some probability amplitude?
In the thermal interpretation, states are described by density operators of the form ##\rho=e^{-S/k}##, where ##S## is an entropy operator and ##k## the Boltzmann constant. The notion of superposition becomes irrelevant on this level; one cannot superimpose two density operators. Pure states, where superpositions are relevant, appear only in a limit where the entropy operator has one dominant eigenvalue and then a large gap. For example, this is the case near equilibrium if the Hamiltonian has a nondegenerate ground state and the temperature is low enough. For this one needs a sufficiently tiny system. A system containing a screen is already far too large.

MichPod said:
We know that a linearity of Schroedinger equation in QM does not prevent that to happen yet the measurement postulate demands a collapse to "happen". Then what is different in principle when you consider QFT or your interpretation of QFT?
We observe only a small number of field and correlation degrees of freedom. The quantum dynamics coarse-grained to a dynamics of these degrees of freedom is the one we actually observe. This coarse-grained system (at increasing level of coarse-graining described by the Kadanoff-Baym equations, Boltzmann-type equations, and hydrodynamic equations) behaves like a classical, highly chaotic dynamical system. Compare with the Navier-Stokes equations, which are one example of such a coarse-grained system.
 
<h2>1. What is the epistemic view of the wave function?</h2><p>The epistemic view of the wave function is a philosophical interpretation of quantum mechanics that suggests the wave function is not a physical entity, but rather a representation of our knowledge or information about a system.</p><h2>2. How does the epistemic view of the wave function lead to superluminal signals?</h2><p>According to the epistemic view, the wave function collapses upon measurement, which means that new information about the system is instantly transmitted to a distant observer. This collapse of the wave function can appear to be faster than the speed of light, leading to the appearance of superluminal signals.</p><h2>3. Is the epistemic view of the wave function widely accepted?</h2><p>No, the epistemic view is a controversial interpretation of quantum mechanics and is not widely accepted by the scientific community. Many physicists favor the more traditional view of the wave function as a physical entity.</p><h2>4. Are there any experiments that support the epistemic view of the wave function?</h2><p>There are no direct experiments that support the epistemic view of the wave function. However, some aspects of the view have been tested indirectly through experiments on quantum entanglement and the violation of Bell's inequalities.</p><h2>5. What are the implications of the epistemic view of the wave function for our understanding of quantum mechanics?</h2><p>The epistemic view challenges our traditional understanding of quantum mechanics and raises questions about the nature of reality and the role of observation in shaping it. It also has implications for the development of new quantum technologies and our ability to make accurate predictions about quantum systems.</p>

1. What is the epistemic view of the wave function?

The epistemic view of the wave function is a philosophical interpretation of quantum mechanics that suggests the wave function is not a physical entity, but rather a representation of our knowledge or information about a system.

2. How does the epistemic view of the wave function lead to superluminal signals?

According to the epistemic view, the wave function collapses upon measurement, which means that new information about the system is instantly transmitted to a distant observer. This collapse of the wave function can appear to be faster than the speed of light, leading to the appearance of superluminal signals.

3. Is the epistemic view of the wave function widely accepted?

No, the epistemic view is a controversial interpretation of quantum mechanics and is not widely accepted by the scientific community. Many physicists favor the more traditional view of the wave function as a physical entity.

4. Are there any experiments that support the epistemic view of the wave function?

There are no direct experiments that support the epistemic view of the wave function. However, some aspects of the view have been tested indirectly through experiments on quantum entanglement and the violation of Bell's inequalities.

5. What are the implications of the epistemic view of the wave function for our understanding of quantum mechanics?

The epistemic view challenges our traditional understanding of quantum mechanics and raises questions about the nature of reality and the role of observation in shaping it. It also has implications for the development of new quantum technologies and our ability to make accurate predictions about quantum systems.

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