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Wavefunction collapse problem
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Wavefunction collapse problem
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nilak
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Wavefunction collapse problem
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28/04/2018 07:41:20 »
According to QM a system that has an associated wavefunction in a superposition of eigenstates of a position operator, collapses upon a measurement to a single eigenstate. Depending on the measurement precision in practice the result gives a linear combinations of close eigenstates. However, I don't think it is a measurement problem. The theoretical collapse to a single state doesn't seem to be a good idea.
Basically, when we do a measurement, it involves a designed system which can only be made of materials which are made of atomic structures. In any case, it involves an interaction between two particles that have never definite positions. For example we detect a transition of an electron to a different energy level. Therefore any collapse of a i.e. photon wavefunction is triggered by the interaction of the photon with a massive particle. But the interaction doesn't happen at a definite position. The photon energy quantum is absorbed by the electron but it doesn't happen at a point in space because the electron position is still in a superposition of eigenstates. In this case I would say, the photon wavefunction collapses and the position we get is the superposition of eigenstates of the electron that has absorbed the photon quantum, not a single point in space.
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nilak
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Re: Wavefunction collapse problem
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03/08/2018 11:15:01 »
Spin example
While the position of a detected particle cannot be found with infinite precision although theoretically the detection appears at a single definite point when determining the spin, thing look more clear. For example we create a magnetic field between a magnet poles (C shape) and check the polarization of electrons. The magnetic field is assumed to be in a known direction. That's because the spin of the atoms interacts with the particles acordingly. However the spin of each atom in the magnets is unknown before any interaction but is a matter of probability. If you have for example much stronger magnetic filed and take each individual atom in the initial system of magnets, these atoms will align predominantly acording to the direction of the magnet they compose but each atom spin is not definite before measurement.
Now we know that if we prepare electrons in a magnetic field, their spin will become definite and known after they exit the magnetic field according to QM. However according this hypothesis most of the electrons will behave as having the expected spin. They will actually not have a definite spin, but a very high probability for the prepared spin.
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Last Edit: 15/08/2018 22:55:22 by
nilak
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