- #1

DrChinese

Science Advisor

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## Main Question or Discussion Point

1. I have previously stated my opinion that Bohmian Mechanics (BM, or dBB), insofar as it is a hidden variable theory (HV), must be non-contextual. On the other hand, most Bohmians consider BM to be contextual in order to satisfy the requirements of Bell, Kochen-Specker (KS), etc.

It seems contradictory to me that: BM asserts there are well-defined values for all observables at all times, yet those values are both a) contextual (dependent on how measured); and b) match the usual QM predictions (such as the cos^2(theta) relationship for photon polarization).

2. Today, Ghose introduced a paper entitled: "On Entangled Multi-particle Systems in Bohmian Theory". From the abstract:

From the paper:

This conclusion seems reasonable to me. It would seem that there should be initial conditions which lead to entangled states compatible with QM; which Ghose says is not true for his example.

3. In other words, I think that BM will always have problems with physical explanations of entanglement scenarios. Which was, in fact, the best thing it had going for it after Bell. I guess my question is this: are there other ways to formulate non-local theories (which are compatible with the QM predictions) OTHER than the Bohmian approach? Perhaps there is a another kind of non-local interaction which comes into play when an observation is made? In the Bohmian approach, the particle positions are paramount; but perhaps there is something else which happens which is explicitly non-local. If you want non-local, is Bohmian the only choice?

It seems contradictory to me that: BM asserts there are well-defined values for all observables at all times, yet those values are both a) contextual (dependent on how measured); and b) match the usual QM predictions (such as the cos^2(theta) relationship for photon polarization).

2. Today, Ghose introduced a paper entitled: "On Entangled Multi-particle Systems in Bohmian Theory". From the abstract:

*"Arguments are presented to show that in the case of entangled systems there are certain difficulties in implementing the usual Bohmian interpretation of the wave function in a straightforward manner. Specific examples are given."*From the paper:

*"The analyses of the two constrained systems considered above in this paper show that the Quantum Equilibrium Hypothesis (QEH) cannot be invoked for wave functions of entangled multiparticle systems in general. Wave functions (3) and (13) are examples. In the first example (3) the initial conditions cannot be chosen to fit the quantum mechanical distribution at arbitrary times, and in the second example (13) the particle distribution is incompatible with QEH at all times, independent of initial conditions."*This conclusion seems reasonable to me. It would seem that there should be initial conditions which lead to entangled states compatible with QM; which Ghose says is not true for his example.

3. In other words, I think that BM will always have problems with physical explanations of entanglement scenarios. Which was, in fact, the best thing it had going for it after Bell. I guess my question is this: are there other ways to formulate non-local theories (which are compatible with the QM predictions) OTHER than the Bohmian approach? Perhaps there is a another kind of non-local interaction which comes into play when an observation is made? In the Bohmian approach, the particle positions are paramount; but perhaps there is something else which happens which is explicitly non-local. If you want non-local, is Bohmian the only choice?