Do not imagine that you have to know everything before you can do anything. My own best work was done when I was most ignorant.

The thing that makes me most optimistic is China and India - both of them doing well.

As a working hypothesis to explain the riddle of our existence, I propose that our universe is the most interesting of all possible universes, and our fate as human beings is to make it so

The technologies that raise the fewest ethical problems are those that work on a human scale, brightening the lives of individual people.

In the history of science it has often happened that the majority was wrong and refused to listen to a minority that later turned out to be right.

The ground of science was littered with the corpses of dead unified theories.

If the tools are bad, nature's voice is muffled. If the tools are good, nature will give us a clear answer to a clear question.