Sunday, 10 April 2011

Part of LH models non-issue for scientific community

Last week Joy Christian notified me that when only about 86 % of all events (of all particles) are counted in an EPR-like experiment, it is always possible to obtain the quantum results in a local realistic way. Even in 1970 this was known to Bell, when he wrote

"On the other hand, if no restrictions whatever are imposed on the hidden variables, or on the dispersion free states, it is trivially clear that such schemes can be found to account for any experimental results whatever. Ad hoc schemes of this kind are devised every day when experimental physicists, to optimize the design of their equipment, simulate the expected results by deterministic computer programs drawn on a table of random numbers." (1)

I found such a limit mentioned in the arxiv article from Reid et al. in which they summarize the current (well..., 2008) state of the EPR debate:

"The original Bell inequalities requires a threshold efficiency of 83 % (η ~ 0.83) per detector (Garg and Mermin (1987); Clauser and Shimony (1978); Fry et al. (1995)), in order to exclude all local hidden variable theories. For lower efficiencies, one can construct local hidden variabe theories to explain the observed correlations (Clauser and Horne (1974); Larsson (1999))." (2)

  1. Introduction to the hidden variable question, J.S.Bell, 1970,
  2. The Einstein-Podolsky-Rosen paradox: from concepts to applications, M.D. Reid et al.2008,
  3. Using linear programming to construct better criteria for closing the detection loophole in EPR experiments, James H. Bigelow, 2008,

Tuesday, 5 April 2011

Comments on the simulation from de Raedt

Discussing the model from de Raedt with Antony Crofts he suggested to check the fraction that was actually counted in the simulation. To my surprise the time window implemented by de Raedt causes the program to use only 0.9% from the total result set.

So, yes, the model produces the quantum expectation, but the simulation does not mimic the results obtained by Weihs et al. (2), on which the simulation is based, because the simulation leaves out much more 'clicks' in comparison to the actual experiment.

Imo. this should have been mentioned in the findings of de Raedt (1).

  1. A computer program to simulate Einstein–Podolsky–Rosen–Bohm experiments with photons, K. De Raedt , H. De Raedt , K. Michielsenc,
  2. Violation of Bell’s inequality under strict Einstein locality conditions
    Gregor Weihs, Thomas Jennewein, Christoph Simon, Harald Weinfurter, and Anton Zeilinger,