Stephen Hawking talks physics

Q: Your presentation is about "The History of the Universe Backward." Why tell it backward?

A: Because the universe doesn't have a fixed initial state. Instead the initial state is determined by the final state.

Q: Why do you believe we must colonize the moon and other planets to ensure the survival of the human race? And wouldn't we just screw up the next place, too? There's a pretty good argument for the case that humans are a virus.

A: We might well screw up on other planets, but provided we don't screw up on every planet at the same time the human race will survive. Survival of species or a virus is a matter of fact not a reward for moral behavior. Viruses have no morals.

Q: What do you — searching for a unified theory of the cosmos — make of what seems to be growing dismissal of science, from global warming to stem-cell research to evolution? As you may know, Seattle is home to the Discovery Institute, which promotes "Intelligent Design."

A: The swing against science occurred during the Bush years mainly in America rather than in the rest of the world. But now there's a reaction in the last year. Climate change has become a global concern. Stem-cell research was never out of favor in Europe and the law in the U.S. is likely to change when Bush goes. And the debate on evolution is being won.

Q: How does your work affect your spiritual beliefs, and do you believe in an afterlife?

A: I have learnt not to look too far ahead, but to concentrate on the present. I'm not afraid of death, but I'm in no hurry to die. I have so much more I want to do. My next goal is to go into space. Maybe Richard Branson will help me?

Q: You turned 65 this month, and your astonishing longevity with ALS naturally makes me think of ... wait for it: One of Mad magazine's "Snappy Answers to Stupid Questions." Q: To what do you owe your long life? A: To the fact that I haven't died yet. And so I ask you: To what do you owe your long life?

A: I don't know. Maybe I don't have the most common kind of motor neurone disease, which usually kills in two or three years. It has certainly helped that I have had a job, and that I have been looked after so well by my family, and a team of carers.

Q: Do you think Einstein would have done "The Simpsons"?

A: I think Einstein had a sense of fun.