It is the facts that matter, not the proofs. Physics can progress without the proofs, but we can't go on without the facts ... if the facts are right, then the proofs are a matter of playing around with the algebra correctly.

I was terrible in English. I couldn't stand the subject. It seemed to me ridiculous to worry about whether you spelled something wrong or not, because English spelling is just a human convention--it has nothing to do with anything real, anything from nature. Any word can be spelled just as well a different way.

A scientist is never certain. ... We absolutely must leave room for doubt or there is no progress and there is no learning.

The test of all knowledge is experiment. Experiment is the sole judge of scientific truth.

Scientists are explorers. Philosophers are tourists.

You see, I get such fun out of thinking that I don't want to destroy this most pleasant machine that makes life such a big kick.

If all of mathematics disappeared, physics would be set back by exactly one week.