Einstein, like Newton, thought light particles followed one path from source to screen, so when the data favored quantum theory, that waves interfere then hit the screen at a random point of their spread, he had two options: either quantum theory was wrong or the physical causes were unknown:
“This is the fundamental problem: either quantum mechanics is incomplete and needs to be completed by a theory of hidden quantities, or it is complete and then the collapse of the wave function must be made physically plausible. This dilemma has not been solved until today, but on the contrary has become more and more critical.” (Audretsch, 2004), p73.
This problem, which Einstein raised and Bohr ignored, still haunts physics today. On the one hand, all attempts to find hidden variables that make quantum randomness physically plausible have failed. On the other hand, all attempts to show that quantum theory is incomplete also failed, so the rules of the quantum world predict perfectly but have no physical explanation.
What then is the solution? The two explanations, that quantum theory is incomplete and that it is physical both led nowhere, so the answer must lie elsewhere. The idea that quantum theory must be either physically true or wrong assumes that material things explain everything. But if materialism is wrong, then quantum theory can be true and also describe what isn’t physical. We know it is true because it always works, and we know it isn’t physical because nothing physical can do what it does. It is then possible that quantum events aren’t explained by physical events because they generate them, just as quantum theory says.
For example, the rules of Minecraft don’t explain how its blocks exist, nor do the rules of chess say how its pieces exist, because that is outside their domain. A created scene can never be fully explained by its local rules, so perhaps physical rules can’t explain photons for the same reason. The player of a game doesn’t have to follow its rules, as I can turn off a game or tip over a chess board. If physical events are also generated, then perhaps physical events can’t explain photons because they originate outside the physical domain. How this could occur is now explored.