If you lined up all the cars in the world end to end, someone would try to pass them.

I don't have much positive to say about motor neuron disease, but it taught me not to pity myself because others were worse off, and to get on with what I still could do. I'm happier now than before I developed the condition.

If the total energy of the universe must always remain zero, and it costs energy to create a body, how can a whole universe be created from nothing?

The real challenge is to work out what aliens might actually be like.

One cannot really argue with a mathematical theorem.

The idea of 10 dimensions might sound exciting, but they would cause real problems if you forget where you parked your car.

Some people would claim that things like love, joy and beauty belong to a different category from science and can't be described in scientific terms, but I think they can now be explained by the theory of evolution.