Q&A: Bell’s Inequality
Bell’s Inequality
Question
Hello Rabbi,
Recently I became acquainted with Bell’s inequality and with various experiments that refute it. For example, I saw a video of light passing through a polarizer in a certain direction, and then through another polarizer oriented perpendicular to the first, so that no light passes through both of them. But when a third polarizer is inserted between the first two at a 45-degree angle relative to both of them, suddenly light passes through all three polarizers.
I saw it written on Wikipedia that the only way to explain the refutations of Bell’s inequality is by rejecting one of the following assumptions:
- Every object has definite properties, whose existence, or whose values, do not depend on measurements.
- It cannot be the case that a certain property of an object both exists and does not exist.
- Any action carried out at some location can affect only objects located in that same place. The speed at which the effect can travel is bounded by the speed of light.
From a philosophical standpoint, all of these assumptions seem extremely correct to me. I would be happy to hear your opinion regarding the reason Bell’s theorem is not valid. Which of the assumptions would you reject, and why?
Answer
I’m not really qualified. There is a nice discussion of this in the book Does the World Exist?, which will be the subject of the next column.
Discussion on Answer
I’m not well-versed in the details. If you want, you can look in the above-mentioned book for a description of the experiment and its implications.
What about the issue of the polarizers (see the image in the link here):
https://drive.google.com/file/d/1aNhu92zrBzsaJJu976LoBWiyI2ex8UcJ/view?usp=sharing
You can see in the image that the area between polarizers 1 and 3 is darker than the area between polarizers 1, 2, and 3.
How does that make sense?