There are many hypotheses in science which are wrong. That’s perfectly all right: it’s the aperture to finding out what’s right. Science is a self-correcting process.

In more than one respect, the exploring of the Solar System and homesteading other worlds constitutes the beginning, much more than the end, of history.

You're an interesting species, an interesting mix. You're capable of such beautiful dreams and such horrible nightmares. You feel so lost, so cut off, so alone, only you're not. See, in all our searching, the only thing we've found that makes the emptiness bearable is each other.

Virtually every major technological advance in the history of the human species - back to the invention of stone tools and the domestication of fire - has been ethically ambiguous.

I find science so much more fascinating than science fiction. It also has the advantage of being true.

Science is a way of thinking much more than it is a body of knowledge. Its goal is to find out how the world works, to seek what regularities there may be, to penetrate to the connections of things-from subatomic particles, which may be the constituents of all matter, to living organisms, the human social community, and thence to the cosmos as a whole.

Any civilization that doesn't develop space travel dies.