I tell my students to try early in life to find an unattainable objective.

I can conceive of no nightmare so terrifying as establishing communication with a so-called superior (or, if you wish, advanced) technology in outer space.

Every creature alive on the earth today represents an unbroken line of life that stretches back to the first primitive organism to appear on this planet; and that is about three billion years.

There is nothing worth having that can he obtained by nuclear war - nothing material or ideological - no tradition that it can defend. It is utterly self-defeating.

I think I know what is bothering the students. I think that what we are up against is a generation that is by no means sure that it has a future.

A scientist should be the happiest of men. Not that science isn't serious; but as everyone knows, being serious is one way of being happy, just as being gay is one way of being unhappy.

The great questions are those an intelligent child asks and, getting no answers, stops asking.