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pittsburghjoe
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Do we yet have an explanation for the Measurement Problem that Einstein would have been satisfied with?
rubi said:I don't know whether Einstein would have been satisfied with it, but there is a resolution of the measurement problem that preserves locality. It's called consistent histories. It's just a version of Copenhagen, which interprets time evolution as a stochastic process in the framework of quantum mechanics. The similarities to the theory of classical stochastic processes are striking, so it seems like a very natural way to explain quantum mechanics and. The resolution of the measurement problem and locality follows in a natural way, so Einstein would certainly at least have considered it a worthwhile candidate after he had learned about Bell's theorem.
Yes, like I said, it's just a version of Copenhagen. But it explains nicely the appearance of the projection operators in ##\mathrm Tr(P_n U(t_n) \cdots P_1 U(t_1)\rho)##, since the probabilities in classical stochastic processes are defined using the exact same formula with the only restriction being that only commuting ##P_n## are allowed. So it becomes apparent that the projections don't contribute to time evolution and observation plays no distinguished role. In that sense, quantum time evolution is just a non-commutative generalization of a classical stochastic process.atyy said:But of course, it is not realistic, unlike classical stochastic processes.
rubi said:Yes, like I said, it's just a version of Copenhagen. But it explains nicely the appearance of the projection operators in ##\mathrm Tr(P_n U(t_n) \cdots P_1 U(t_1)\rho)##, since the probabilities in classical stochastic processes are defined using the exact same formula with the only restriction being that only commuting ##P_n## are allowed. So it becomes apparent that the projections don't contribute to time evolution and observation plays no distinguished role. In that sense, quantum time evolution is just a non-commutative generalization of a classical stochastic process.
That's not related to a distinguished role of observers. In consistent histories, you need to choose a set of alternatives that you want to assign probabilities to. However, the physics is independent of this choice. The paper is concerned with the question of whether one choice can be singled out by asking the alternatives to behave classically. It's however not required that this choice must be made.atyy said:It is not agreed on that observation plays no distinguished role in consistent histories - who chooses which consistent family occurs? Or do you think there is no need for attempts such as https://arxiv.org/abs/1106.0767 to fix a non-existent problem?
rubi said:That's not related to a distinguished role of observers. In consistent histories, you need to choose a set of alternatives that you want to assign probabilities to. However, the physics is independent of this choice. The paper is concerned with the question of whether one choice can be singled out by asking the alternatives to behave classically. It's however not required that this choice must be made.
Nobody knows - since this would require time travel. I don't think there has been one that would fit with the point of view Einstein consistently expressed in the Einstein-Bohr letters, but, as a scientist, Einstein would have to take the modern point of view seriously even if he does not find it satisfying.Do we yet have an explanation for the Measurement Problem that Einstein would have been satisfied with?
Nbody can know for sure and it doesn't matter. What matters is how the experiment informs the way physical models work today and into the future.What do you think he would say when confronted with the results of the quantum eraser experiment?
The quantum measurement problem refers to the discrepancy between the principles of quantum mechanics and our classical understanding of the measurement process. It is the question of how a quantum system can exist in multiple states simultaneously, but upon measurement, only one state is observed.
There are several proposed explanations for the quantum measurement problem, including the Copenhagen interpretation, the many-worlds interpretation, and the decoherence theory. Each offers a different perspective on how to reconcile quantum mechanics with our classical understanding of measurement.
The Copenhagen interpretation, proposed by Niels Bohr and Werner Heisenberg, suggests that the act of measurement causes the wave function of a quantum system to collapse into a single state, thus explaining the observation of only one state.
There is no clear consensus on whether the quantum measurement problem can be solved definitively. Some argue that it is a fundamental issue in our understanding of quantum mechanics, while others believe that further research and experimentation could lead to a resolution.
Decoherence theory suggests that the interaction of a quantum system with its surrounding environment causes the system to lose its coherence and collapse into a single state, thus explaining the observation of only one state. This theory is seen as a bridge between the Copenhagen interpretation and the many-worlds interpretation.