"It is not enough to know how to build a bomb. One must also know how to control it."

"I would rather be ignorant and learn, than be learned and not know."

"Where is everybody? Humans could theoretically colonize the galaxy in a million years or so, and if they could, astronauts from older civilizations could do the same. So why haven't They come to Earth…"

"We must always strive to use our knowledge for the betterment of humanity, and not for its destruction."

"The fundamental problem is to find out if we can make a chain reaction go. If we can, then we have a new source of power. If we can't, then we don't."