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

Our freedom to doubt was born out of a struggle against authority in the early days of science. It was a very deep and strong struggle: permit us to question - to doubt - to not be sure. I think that it is important that we do not forget this struggle and thus perhaps lose what we have gained.

Experiment is the sole judge of the validity of any idea.

I'm going to play with physics, whenever I want to, without worrying about any importance whatsoever.

Poets say science takes away from the beauty of stars-mere globs of gas atoms. Nothing is "mere". I too see the stars on a desert night, and feel them. But do I see less or more? ...What is the pattern, or the meaning, or the why? It does not do harm to the mystery to know a little more about it. For far more marvelous is the truth than any artists of the past imagined it.

Physics is like sex: sure, it may give some practical results, but that's not why we do it.

It does not matter who you are, or how smart you are, or what title you have, or how many of you there are, and certainly not how many papers your side has published, if your prediction is wrong then your hypothesis is wrong. Period.