The best weapon of a dictatorship is secrecy; the best weapon of a democracy is openness.

Had we not pursued the hydrogen bomb, there is a very real threat that we would now all be speaking Russian. I have no regrets.

In our educational institutions applied science may almost be described as a "no-man's land."

In the history of physics, there have been three great revolutions in thought that first seemed absurd yet proved to be true. The first proposed that the earth, instead of being stationary, was moving around at a great and variable speed in a universe that is much bigger than it appears to our immediate perception. That proposal, I believe, was first made by Aristarchos two millenia ago ... Remarkably enough, the name Aristarchos in Greek means best beginning.

No endeavor that is worthwhile is simple in prospect; if it is right, it will be simple in retrospect.

Really exotic methods of propulsion . . . will have to be devised to get there. How it will be done, I do not know. Whether it will be done, I am not quite certain. But I would bet it can be done.

The extinction of the human race will come from its inability to EMOTIONALLY comprehend the exponential function.