Richard P. Feynman Theory Quotations

Because the theory of quantum mechanics could explain all of chemistry and the various properties of substances, it was a tremendous success. But still there was the problem of the interaction of light and matter.

The electron is a theory. But the theory is so good we can almost consider them real.

Progress in science comes when experiments contradict theory.

Another thing I must point out is that you cannot prove a vague theory wrong.