Like every other destruction of optimism, whether in a whole civilisation or in a single individual, these must have been unspeakable catastrophes for those who had dared to expect progress. But we should feel more than sympathy for those people. We should take it personally. For if any of those earlier experiments in optimism had succeeded, our species would be exploring the stars by now, and you and I would be immortal.

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

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.

Like every other destruction of optimism, whether in a whole civilisation or in a single individual, these must have been unspeakable catastrophes for those who had dared to expect progress. But we should feel more than sympathy for those people. We should take it personally. For if any of those earlier experiments in optimism had succeeded, our species would be exploring the stars by now, and you and I would be immortal.

The most important application of quantum computing in the future is likely to be a computer simulation of quantum systems, because that's an application where we know for sure that quantum systems in general cannot be efficiently simulated on a classical computer.

I myself believe that there will one day be time travel because when we find that something isn't forbidden by the over-arching laws of physics we usually eventually find a technological way of doing it.

The overwhelming majority of theories are rejected because they contain bad explanations, not because they fail experimental tests.