Could the randomness of quantum mechanics be the result of unseen factors? [duplicate]

Question

The possibility of randomness in physics doesnt particularly bother me, but contemplating the possibility that quarks might be made up of something even smaller, just in general, leads me to think there are likely (or perhaps certainly?) thousands of particles and forces, perhaps layers and sub layers of forces, at play that we do not know about. So this got me thinking about quantum mechanics.

I'm no physicist, but I do find it interesting to learn and explore the fundamentals of physics, so I'm wondering: Could the randomness found in radioactive decay as described in quantum mechanics be the result of forces and / or particles too weak / small for us to know about yet resulting in the false appearance of randomness?

Or rather, can that be ruled out?

Answer 1

As noted in the comments this is a much studied question. Einstein, Podolsky and Rosen wrote a paper on it, "Can Quantum-Mechanical Description of Reality Be Considered Complete?", published in Physical Review in 1935, and universally known today as the EPR paper.

They considered a particular situation, and their paper raised the question of "hidden variables", perhaps similar to the microstates which undergird thermodynamics. Several "hidden variable" theories have been proposed, including one by David Bohm which resurrected de Broglie's "Pilot Wave" model. These are attempts to create a quantum theory which gets rid of the random numbers at the foundations of quantum mechanics.

In 1964 Bell analyzed the specific type of situation which appears in the EPR paper, assuming that it met the conditions Einstein et al had stipulated for "physical reality". Using this analysis he then showed some specific measurements that are in agreement with any such hidden-variable, classical theory would satisfy a set of inequalities; these are today known as the Bell inequalities. They are classical results.

He then showed that for ordinary quantum mechanics that the Bell inequalities are violated for certain settings of the apparatus. This means that no hidden variable theory can replace quantum mechanics if it also meets Einstein's conditions for "physical reality".

The EPR abstract reads: "In a complete theory there is an element corresponding to each element of reality. A sufficient condition for the reality of a physical quantity is the possibility of predicting it with certainty, without disturbing the system. In quantum mechanics in the case of two physical quantities described by non-commuting operators, the knowledge of one precludes the knowledge of the other. Then either (1) the description of reality given by the wave function in quantum mechanics is not complete or (2) these two quantities cannot have simultaneous reality. Consideration of the problem of making predictions concerning a system on the basis of measurements made on another system that had previously interacted with it leads to the result that if (1) is false then (2) is also false. One is thus led to conclude that the description of reality as given by a wave function is not complete."

In fact, one can run quantum mechanical experiments that routinely violate Bell's inequalities; I'm currently involved in setting one up which will be validated by violating Bell's inequalities. People have been doing this for over 40 years. The main argument against closing this chapter are the various "loopholes" in the experiments. Recently it has been claimed that a single experiment has simultaneously closed all of the loopholes. If that is true, then there are no classical hidden variable theories which can replace regular quantum mechanics unless they are grossly non-local. Einstein certainly would not think that these were an improvement!

Answer 2

The answer to your question, despite what commenters are saying, is yes, our observations in physics could be caused by factors that play a part on such an unreachable-small scale we can't detect them yet.

This even has precedent: before Einstein we couldn't tell what was causing the seemingly erratic movement of microscopic objects. See animation (source):

His description of what we now call Brownian Motion correctly described the motion of the blue ball as a result from constant bombardment of the much smaller red balls. While this doesn't seem helpful at first, the laws of thermodynamics and rules of probability help use derive useful macroscopic quantities of motion at the cellular level, such as how far the blue ball will be from it's starting center after a certain amount of time.

Perhaps, yes, little tiny Planck-length scale balls are bombarding the inside of all nuclei causing the emissions we now describe with the weak force. However, what you are suggesting is not doing physics. In this field, if you can't observe your prediction, you cannot expect others to take it as a de facto model of nature.

While you might be right about the cause of QM phenomena being these tiny, difficult to measure interactions, without any sort of proof you are just doing math (and without the math, you're just doing science fiction). This has been one of the leading criticisms we hear again and again about string theory.