Where we have good, testable explanations, they then have to be tested, and we drop the ones that fail the tests.

Our best theories are not only truer than common sense, they make more sense than common sense...

The quantum theory of parallel universes is not the problem, it is the solution. It is not some troublesome, optional interpretation emerging from arcane theoretical considerations. It is the explanation - the only one that is tenable - of a remarkable and counter-intuitive reality.

It is possible to build a virtual-reality generator whose repertoire includes every possible environment.

To me quantum computation is a new and deeper and better way to understand the laws of physics, and hence understanding physical reality as a whole.

The brain is the only kind of object capable of understanding that the cosmos is even there, or why there are infinitely many prime numbers, or that apples fall because of the curvature of space-time, or that obeying its own inborn instincts can be morally wrong, or that it itself exists.

The whole [scientific] process resembles biological evolution. A problem is like an ecological niche, and a theory is like a gene or a species which is being tested for viability in that niche.