Deterministic underlying theories for QM are possible. They are still difficult to construct, but simple "toy models" are possible. These models are … - Gerard 't Hooft

... trying to solve a paradox will lead to new kinds of understanding. And I think that the problem of subjecting black holes to quantum mechanics is a fundamental paradox of the same nature, and the same depth, and the same importance as the paradox that Max Planck was studying at the beginning of the twentieth century.

When investigating theories at the tiniest conceivable scales in nature, almost all researchers today revert to the quantum language, accepting the verdict from the Copenhagen doctrine that the only way to describe what is going on will always involve states in HIlbert space, controlled by operator equations.

The usual no-go theorems telling us that hidden variables are irreconcilable with locality, appear to start with fairly conventional pictures of particle systems, detectors, space and time. Usually, it is taken for granted that events at one place in the universe can be described independently from what happens elsewhere. Perhaps one has to search for descriptions where the situation is more complex. Maybe, it needs not be half as complex as superstring theory itself. The conventional Copenhagen interpretation of quantum mechanics suffices to answer all practical questions concerning conventional experiments with quantum mechanics, and the outcome of experiments such as that of Aspect et al can be precisely predicted by conventional quantum mechanics. This is used by some to state that no additional interpretation prescriptions for quantum mechanics are necessary. Yet we insist that the axioms for any "complete" quantum theory for the entire cosmos would present us with as yet unresolved paradoxes.