Language and emotions are too easily misread. For example, laughing can mean many things: laughing with you or at you. Does that laugh reflect joy, anger, or that s/he's about to fire you? Too many jobs require complex feelings, pattern recognition, common sense, and the human touch.

In some sense, gravity does not exist; what moves the planets and the stars is the distortion of space and time.

As Heinz Pagels has said, The challenge to our civilization which has come from our knowledge of the cosmic energies that fuels the stars, the movement of light and electrons through matter, the intricate molecular order which is the biological basis of life, must be met by the creation of a moral and political order which will accommodate these forces or we shall be destroyed. It will try our deepest resources of reason and compassion.

You can mass-produce hardware; you cannot mass-produce software - you cannot mass-produce the human mind.

So often, science fiction helps to get young people interested in science. That's why I don't mind talking about science fiction. It has a real role to play: to seize the imagination.

I had two passions when I was a child. First was to learn about Einstein's theory and help to complete his dream of a unified theory of everything. That's my day job. I work in something called string theory. I'm one of the founders of the subject. We hope to complete Einstein's dream of a theory of everything.

No one knows when a robot will approach human intelligence, but I suspect it will be late in the 21st century. Will they be dangerous? Possibly. So I suggest we put a chip in their brain to shut them off if they have murderous thoughts.