What would be needed to make physicists search for such an explanation? Some kind of pattern in the "randomness"? Say, photons behave more like particles on Monday mornings?
They are at odds with what quantum mechanics predicts (and what we have observed).
On a semi-related note, I might be reading too much into your comment, but I very much dislike when people imply that scientists haven’t thought outside or the box or tried other non-mainstream theories. They try all the time, but fail because those theories often aren’t true. What we’re left with are the best extant theories, even if they’re obvious incomplete.
[0] https://en.wikipedia.org/wiki/Local_hidden-variable_theory?w...
Correct theories are suppressed all the time by oligarchs. See the electric car.
This assumption that the best is chosen is part of the problem of the scientific institution - the assumption that corruption doesn’t play a major role in what is allowed through the gate keepers.
My point is that the notion of "measurement" or "wave function collapse" simply don't seem to explain anything. Instead they are just different words for what we observe. So yes, that is certainly useful but it also seems to be limiting.
A simple question would be: What is "measurement", i.e. what is the fundamental thing that forces a probability distribution to yield a concrete value? And why does it exist separately from said probability distribution?
Edit: to make things even clearer: I am not lamenting that there is no one working on mathematically consistent interpretations of QM. I know people are doing that and I know that this is difficult. Instead I am asking what would be a clearly visible limit of QM. Where would we, as a society, encounter a situation where we say: "We really need to explain the reasons behind QM or we won't get that problem here solved."
All classical theories and interpretations of QM already have indexical uncertainty (the randomness of what person you find yourself born as). MWI avoids adding any new kinds of entities not implied by the Schrodinger equation and effectively explains away quantum randomness by implying that it's the same thing as indexical uncertainty, instead of being a separate kind of randomness.
Also, the MWI idea of branching is no more satisfying or intuitive than the wave function collapse, which at least doesn't require an infinity of universes out of which some are much more probable than others.
Note also that there is only 1 of you in MWI, you just exist with different amplitudes in different states, but when interacting with another object, you become entangled with a single outcome and thus can no longer perceive the other states that other versions of you perceive. This is important, as otherwise physical quantities would not be properly conserved.
I'd say confirmation of a failed prediction by QM is what's needed.
what if randomness is an inherent property of nature?
However, when you measure the state of such a system after however many steps of perfectly deterministic interactions you want, you find the system takes only one of the many possible states predicted by the Schrodinger equation, with a probability that depends on the amplitude of that state.
It is this discrepancy between the deterministic nature of the quantum world and the classical world, but the probabilistic nature of the crossing between them, that people find disconcerting.
MWI even does away with this to solve extent, explaining it as a kind of observation bias: as a particle interacts with a very independent system, it loses its ability to interact with itself (decoherence), and so we get many versions of the system each interacting with a single version of the particle, which stimulates classical physics for each version. From the perspective of any particular version of this system it is random with which particular version of the particle it interacts, even though at the universal level there is no randomness.