metacristi
Muse
- Joined
- Sep 17, 2002
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- 760
Mark
I presume you referred at von Neumann's attempt to prove that hidden variable theories are impossible.These theories are deterministic,openly opposing to the bold claim of Heisenberg and Bohm that standard QM is the most complete description of quantum events possible (implying that quantum events are intrinsically random).Though his first four postulates are valid logically the fifth and the most important in his attempt is not sound.He begins there from the false premise that in hidden variables theories 'identically prepared samples' can be defined exactly as in the usual copenhagenist view.Or they are not identical.Whilst in the copenhagenist view the state vector represent the most we can know about the system in the hidden variables theories this does not hold for there should be added another vector,the so called 'hidden' vector,not known,which accounts for the unique outcome.In other words the vector of state we can calculate using the mathematical formalism of QM is the same but the definition of the initial state implied by hidden variables theories is not identical with that in the copenhagenist view.This invalidate also von Neumann's proof against hidden variables.And indeed no more than 20 years later Bohm would provide a counterexample to von Neumann's proof in the form of a fully causal interpretation the so called Bohm's Interpretation of QM which shows clearly that non local hidden variable theories are feasible and compatible with the predictions of QM.Of course physicists assume also that the standard formalism is correct,so far all experiments support it,and we have vast amount of empirical confirmations.As far as I know there are other mathematical attempts to prove that hidden variables are impossible but there is no general consensus that they really succeeded.Moreover there are mathematical studies (Stapp,sometimes after 1995) which seems to prove that only locality should be blamed for the violation of Bell's inequalities.Basically there is no good reason now to claim that the principle of realism should be abandoned,non local hidden variables theories are still viable.In spite of some problems (Bohm's Interpretation is not Lorentz invariant implying the existence of a sort of ether=privileged system of reference;as of now there is no relativistic theory with hidden variables) neither is there a satisfactory explicit explanation for the spooky action at distance (copenhagenist also interpret the results of Aspect's experiments as proving the existence of some sort of connection at distance).I'm afraid the intrinsic explanation provided by copenhagenists (rather simply accepting that such a spooky connection does exist) and quantum electrodynamics is not enough to make the strong claim that hidden variables theories are not feasible or,even stronger,that hidden variables do not exist.
Would you help me out here? How does this work around the logic in Von Neumann's Chain? I have been struggling with this for some time...
I presume you referred at von Neumann's attempt to prove that hidden variable theories are impossible.These theories are deterministic,openly opposing to the bold claim of Heisenberg and Bohm that standard QM is the most complete description of quantum events possible (implying that quantum events are intrinsically random).Though his first four postulates are valid logically the fifth and the most important in his attempt is not sound.He begins there from the false premise that in hidden variables theories 'identically prepared samples' can be defined exactly as in the usual copenhagenist view.Or they are not identical.Whilst in the copenhagenist view the state vector represent the most we can know about the system in the hidden variables theories this does not hold for there should be added another vector,the so called 'hidden' vector,not known,which accounts for the unique outcome.In other words the vector of state we can calculate using the mathematical formalism of QM is the same but the definition of the initial state implied by hidden variables theories is not identical with that in the copenhagenist view.This invalidate also von Neumann's proof against hidden variables.And indeed no more than 20 years later Bohm would provide a counterexample to von Neumann's proof in the form of a fully causal interpretation the so called Bohm's Interpretation of QM which shows clearly that non local hidden variable theories are feasible and compatible with the predictions of QM.Of course physicists assume also that the standard formalism is correct,so far all experiments support it,and we have vast amount of empirical confirmations.As far as I know there are other mathematical attempts to prove that hidden variables are impossible but there is no general consensus that they really succeeded.Moreover there are mathematical studies (Stapp,sometimes after 1995) which seems to prove that only locality should be blamed for the violation of Bell's inequalities.Basically there is no good reason now to claim that the principle of realism should be abandoned,non local hidden variables theories are still viable.In spite of some problems (Bohm's Interpretation is not Lorentz invariant implying the existence of a sort of ether=privileged system of reference;as of now there is no relativistic theory with hidden variables) neither is there a satisfactory explicit explanation for the spooky action at distance (copenhagenist also interpret the results of Aspect's experiments as proving the existence of some sort of connection at distance).I'm afraid the intrinsic explanation provided by copenhagenists (rather simply accepting that such a spooky connection does exist) and quantum electrodynamics is not enough to make the strong claim that hidden variables theories are not feasible or,even stronger,that hidden variables do not exist.