I believe in the possible. I believe, small though we are, insignificant though we may be, we can reach a full understanding of the universe. You were right when you said you felt small, looking up at all that up there. We are very, very small, but we are profoundly capable of very, very big things.

Thirty years ago I was diagnosed with motor neurone disease, and given two and a half years to live. I have always wondered how they could be so precise about the half.

So next time someone complains that you have made a mistake, tell him that may be a good thing. Because without imperfection, neither you nor I would exist.

To my mathematical brain, the numbers alone make thinking about aliens perfectly rational.

Any physical theory is always provisional, in the sense that it is only a hypothesis: you can never prove it.

The meaning in life is not out there but inbetween our ears. In many ways this makes us the lords of creation.

When I get to heaven I'm gonna find the guy in charge of the weather and kick his rear.