> It sure seems to be an epistemology problem which puts it > squarely in the realm of philosophy, not physics. It's absolutely a physical issue, not a purel

> It sure seems to be an epistemology problem which puts it > squarely in the realm of philosophy, not physics. It's absolutely a physical issue, not a purely philosophical one. Under the Copenhagen interpretation, the probability densities which drop out of Quantum Mechanics reflect some sort of objective physical reality, as in Schroedinger's Cat. The alternative to this is the so-called "hidden variables" theories [1], which posit that those densities reflect variability in some kind of hidden extra state in quantum-mechanical systems of which we are currently ignorant. The very real Bell's inequality experiments [2] are an example of the physical quality of this dichotomy. [1] https://en.wikipedia.org/wiki/Hidden_variable_theory https://en.wikipedia.org/wiki/Hidden_variable_theory [2] https://en.wikipedia.org/wiki/Bell_test_experiments https://en.wikipedia.org/wiki/Bell_test_experiments