We didn't go to the moon to explore or because it was in our DNA or because we're Americans. We went because we were at war and we felt a threat.

The most successful scientists in the history of the world are those who posed the right questions

In whatever you choose to do, do it because it's hard, not because it's easy. Math and physics and astrophysics are hard. For every hard thing you accomplish, fewer other people are out there doing the same thing as you. That's what doing something hard means. And in the limit of this, everyone beats a path to your door because you're the only one around who understands the impossible concept or who solves the unsolvable problem.

Give a kid a book, and you change the world. In a way, even the universe.

Science, and its impact on a person's livelihood is the common denominator.

... there is no shame in not knowing. The problem arises when irrational thought and attendant behavior fill the vacuum left by ignorance.

I want upon death to be buried, just like in the old days, where I decompose by the action of microorganisms, and I am dined upon by any form of creeping animal or root system that sees fit to do so.... I will have recycled back to the universe at least some of the energy that I have taken from it. And in so doing, at the conclusion of my scientific adventures, I will have come closer to the heavens than to Earth.