Hidden variables - Bell - The Law of Malus?

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SUMMARY

This discussion centers on the application of Malus' Law to challenge the concept of hidden variables in quantum mechanics, particularly in the context of Bell's Theorem. The author argues that if vertically polarized photons are directed through a lens rotated at 30° (R30°), approximately 3/4 of them pass through, suggesting they are tagged to do so. However, the application of Malus' Law indicates that only 1/4 of the photons would pass through both R30° and L30°, thereby questioning the validity of hidden variable theories. The author acknowledges the necessity of Bell's Theorem for refuting local realism but highlights a critical flaw in the tagging argument.

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  • Understanding of Bell's Theorem in quantum mechanics
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Physicists, quantum mechanics students, and researchers interested in the foundations of quantum theory and the debate surrounding hidden variables and local realism.

Zafa Pi
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Invariably in the lay literature when it comes time to show that EPR hidden variables are incompatible with QM, Bell's Theorem is invoked (e.g. Greene's "Fabric of the Cosmos", Zeilinger's "Dance of the Photons", Rosenblum's "Quantum Enigma", ...).

I don't see why a simple application of Malus' Law (old as the hills) doesn't accomplish it, to wit:
If we have a zillion vertically polarized photons beamed into a polarized lens whose axis is rotated 30° to the right of vertical (R30°), then about 3/4 get thru. So that 3/4 have been tagged (hidden) with the instruction to pass thru R30°. The same goes for L30°. Thus at least 1/2 of the zillion have been tagged to go thru both. But Malus tells us that only 1/4 go thru both.

I haven't found a thread that mentions this. Nor do I see why this doesn't refute hidden variables.
Admittedly to refute local realism one seems to need something like Bell's Theorem with entangled pairs.
 
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I'm sorry I didn't think this thru. Once a tagged photon passes thru R30° it's no longer vertically polarized so there is no tag for L30°.
 

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