In the long run, the only solution I see to the problem of diversity is the expansion of mankind into the universe by means of green technology... Green technology means we do not live in cans but adapt our plants and our animals and ourselves to live wild in the universe as we find it... When life invades a new habitat, she never moves with a single species. She comes with a variety of species, and as soon as she is established, her species spread and diversify further. Our spread through the galaxy will follow her ancient pattern.

Computer models of the climate....[are] a very dubious business if you don't have good inputs.

Everything in my life was luck.

I am acutely aware of the fact that the marriage between mathematics and physics, which was so enormously fruitful in past centuries, has recently ended in divorce.

If we want to go to space with humans, that's for fun not for science. Human adventures in space are just sporting events.

A good cause can become bad if we fight for it with means that are indiscriminately murderous. A bad cause can become good if enough people fight for it in a spirit of comradeship and self-sacrifice. In the end it is how you fight, as much as why you fight, that makes your cause good or bad.

The average student emerges at the end of the Ph.D. program, already middle-aged, overspecialized, poorly prepared for the world outside, and almost unemployable except in a narrow area of specialization. Large numbers of students for whom the program is inappropriate are trapped in it, because the Ph.D. has become a union card required for entry into the scientific job market.