- #1

Cerenkov

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Hello.

A friend and I are having a good-natured argument about tests of Bell's Theorem and he has directed me to this link.

http://electron6.phys.utk.edu/phys250/modules/module 3/entangled_electrons.htm

Our understanding of quantum physics should be considered as Basic.

What we would like to understand is a little more about the match rates mentioned in the concluding section of the above article.

We read this to mean that Bell tests in favour of hidden variables would have values

But a little searching through this forum has revealed this, from 2011.

https://www.physicsforums.com/threads/violation-of-bells-theorem.496839/post-3290045

This appears to say that Bell Theorem experiments have a match rate well

So, question 1.

Are we mistaken in our understanding of the match rates from these two sources? If so, could we please be corrected in a way that someone at a Basic level can grasp?

Question 2.

Where can we find source material that gives the discovered match rates for various Bell tests?

(This Wiki page cites a list of Notable Experiments. https://en.wikipedia.org/wiki/Bell_test )

Should we start there and investigate each citation sequentially or is there a 'condensed' source which summarises what we'd like to find out?

Thanks in advance for any help given and apologies in advance for any rookie-level blunders made in this posting.

We would gladly accept gentle correction and instruction, if its needed.

Thank you.

Cerenkov.

A friend and I are having a good-natured argument about tests of Bell's Theorem and he has directed me to this link.

http://electron6.phys.utk.edu/phys250/modules/module 3/entangled_electrons.htm

Our understanding of quantum physics should be considered as Basic.

What we would like to understand is a little more about the match rates mentioned in the concluding section of the above article.

*For a large number of trials, ~50% of the time the lights on both filters will flash the same color. Experiments similar to the one described here have now been carried out many times and have always yielded this predicted result.*

Quantum mechanics predicts incompatible observables for a system. An observer cannot know the values of two incompatible observables of a system at the same time. Does this mean that the system really does not have well defined values for these observables before a measurement, or is it possible that the system has well defined values, but these values are hidden from the observer, and the observer just cannot obtain the complete information?

In 1964 J.S. Bell showed that the assumption of hidden variables is inconsistent with the outcome of the above described experiment. If there were hidden variables, we would have to observe the light flashing the same color more than 50% of the time. We will examine at a simple version of Bell's thought experiment in an in-class activity.**What is so special about that?**Quantum mechanics predicts incompatible observables for a system. An observer cannot know the values of two incompatible observables of a system at the same time. Does this mean that the system really does not have well defined values for these observables before a measurement, or is it possible that the system has well defined values, but these values are hidden from the observer, and the observer just cannot obtain the complete information?

In 1964 J.S. Bell showed that the assumption of hidden variables is inconsistent with the outcome of the above described experiment. If there were hidden variables, we would have to observe the light flashing the same color more than 50% of the time. We will examine at a simple version of Bell's thought experiment in an in-class activity.

We read this to mean that Bell tests in favour of hidden variables would have values

__above__50%.But a little searching through this forum has revealed this, from 2011.

https://www.physicsforums.com/threads/violation-of-bells-theorem.496839/post-3290045

*[Moderator's note: Fixed link to point to the specific post being referenced.]*

If, on the other hand, you care to put forth a Local Realistic dataset (i.e. like your Example 1) for the angle settings 0, 120 and 240 degrees, you will discover something very quickly. Your match rate will be greater than 33 percent. Now YOUR prediction will not match experiment (which is 25%). Try it, really (psssst you already have proven my point with your example 1)! Suddenly, the assumptions you made about this not being a meaningful test completely falls apart because YOUR predictions will be flat wrong.If, on the other hand, you care to put forth a Local Realistic dataset (i.e. like your Example 1) for the angle settings 0, 120 and 240 degrees, you will discover something very quickly. Your match rate will be greater than 33 percent. Now YOUR prediction will not match experiment (which is 25%). Try it, really (psssst you already have proven my point with your example 1)! Suddenly, the assumptions you made about this not being a meaningful test completely falls apart because YOUR predictions will be flat wrong.

This appears to say that Bell Theorem experiments have a match rate well

__below__50%So, question 1.

Are we mistaken in our understanding of the match rates from these two sources? If so, could we please be corrected in a way that someone at a Basic level can grasp?

Question 2.

Where can we find source material that gives the discovered match rates for various Bell tests?

(This Wiki page cites a list of Notable Experiments. https://en.wikipedia.org/wiki/Bell_test )

Should we start there and investigate each citation sequentially or is there a 'condensed' source which summarises what we'd like to find out?

Thanks in advance for any help given and apologies in advance for any rookie-level blunders made in this posting.

We would gladly accept gentle correction and instruction, if its needed.

Thank you.

Cerenkov.

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