Bell's theorem is for ANY wave, not specifically for quantum mechanics

We have earlier in this blog claimed that Bell's theorem essentially states a very obvious fact that if you make a wave function to "collapse", the collapse destroys precious information, and you cannot reproduce the same interference pattern that you could produce with an "unharmed" wave.

https://en.wikipedia.org/wiki/Bell%27s_theorem

Today we realized that actually this is true for any wave, also for classical waves. Consider the double-slit experiment. We can treat the laser beam as a classical electromagnetic wave, or alternatively, a probability amplitude wave of quantum mechanics (using the Feynman terminology).

If we disturb the wave, the interference pattern on the screen changes. A "collapse" of the wave is a drastic operation on an electromagnetic wave. It is like using a converter to transform an analog (real number) signal to a binary number 0 or 1.

A "hidden variable" hypothesis typically is incompatible with the hypothesis that we are dealing with a simple, undisturbed wave.

Non-locality

Bell's theorem is often interpreted as showing that quantum mechanics is "nonlocal". There is a "spooky action at a distance", to paraphrase Albert Einstein.

In this blog we do not believe in any spooky action at a distance. Rather, we believe that the wave function can only "collapse" inside the head of a single observer. Any measurement result made by any measuring apparatus is transmitted as a probability amplitude wave into the head of the observer, where the final collapse happens. It is like the double-slit experiment where the screen is placed inside the head of the single observer.