We live in the kind of society where, in almost all cases, hard work is rewarded.

For me, one of the most fertile consequences of the space program is the extent to which it stimulates people to innovate because they want to create a different tomorrow than what they're living in today. And it's that culture of innovation that spawns entirely new economies.

If you get asteroids about a kilometer in size, those are large enough and carry enough energy into our system to disrupt transportation, communication, the food chains, and that can be a really bad day on Earth.

Physics is the only profession in which prophecy is not only accurate but routine.

Anyone who has wrestled knows that it's the hardest thing in the world to do. Anyone who says something else is the hardest thing has never wrestled. That's what I have found. ... You don't wrestle because it's easy, you wrestle because it's hard. I don't do astrophysics because it's easy, I do it because it's hard. And I juxtapose the two in my mind, body, and soul all the time.

After all, what nobler thought can one cherish than that the universe lives within us all?

Some air you inhale was exhaled by Cleopatra.