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Name: Unknown
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: Around 1993


Question:
I have a question about Bell's Inequality Theorem. He talks about measuring a pair of photon twins with polarization detectors. If both detectors are set 0 degrees the they will receive the same message. If one detector is turned 30 degrees it will be different, one out of four measurements. I agree up to here. But then he says if you turn the other detector 30 degrees the other way, the rate of differences will increase to 3 out of four (cos^2 (60)=3/4). I disagree because if we are measuring a SIGNAL, it is going to be sent Horizontally or Vertically for error free transmission at 0 degrees (H always equals 0, V always = 1). So with all V signals, turning one detector 30 degrees will give a 1 three out of four times. Turning the other detector 30 degrees the other way will still give 1 three out of four times. So they will both get the same (right or wrong) message 5 out of 8 times (9/16+1/16). NO VIOLATION of Bell's Theorem. If the photons are sent at random, though, the detectors will be different 3/4 of the time, but they should be. At 90 degree separation they are always different (opposite). Move one towards the other 30 degrees and it will be non-opposite ONE out of FOUR times. Non-locality is not proven (to me) as the messages at one detector do not depend on the setting of the other.



Replies:
The 3/4 difference is a result of a quantum mechanical calculation of probabilities, not based on classical reasoning about signals that are horizontal or vertical. Maybe the author did not explain this properly, but that is the key difference of quantum mechanic; you cannot understand it by classical reasoning. The two photons are really coupled.

A. Smith



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