"In practice, quantum mechanics merely gives predictions with probabilities attached. This should be considered as a normal and quite acceptable feature of predictions made by science: different possible outcomes with different probabilities. In the world that is familiar to us, we always have such a situation when we make predictions. Thus the question remains: What is the reality described by quantum theories? I claim that we can attribute the fact that our predictions come with probability distributions to the fact that not all relevant data for the predictions are known to us, in particular important features of the initial state."

“If you really want to contribute to our theoretical understanding of physical laws — and it is an exciting experience if you succeed! — there are many things you need to know. First of all, be serious about it!”

“Quantum mechanics as it stands would be perfect if we didn't have the quantum-gravity issue and a few other very deep fundamental problems.”

“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.”

“Deterministic underlying theories for QM are possible. They are still difficult to construct, but simple "toy models" are possible. These models are not good enough to replace today's existing quantum theories.”

“On your way towards becoming a bad theoretician, take your own immature theory, stop checking it for mistakes, don't listen to colleagues who do spot weaknesses, and start admiring your own infallible intelligence.”

“... 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.”