An electron is no more (and no less) hypothetical than a star. Nowadays we count electrons one by one in a Geiger counter, as we count the stars one by one on a photographic plate.

I don't believe any experiment until it is confirmed by theory. I find this is a witty inversion of "conventional" wisdom.

It is impossible to trap modern physics into predicting anything with perfect determinism because it deals with probabilities from the outset.

It cannot be denied that for a society which has to create scarcity to save its members from starvation, to whom abundance spells disaster, and to whom unlimited energy means unlimited power for war and destruction, there is an ominous cloud in the distance though at present it be no bigger than a man's hand.

Philosophically, the notion of a beginning of the present order of Nature is repugnant to me ... I should like to find a genuine loophole.

Every body continues in its state of rest or uniform motion in a straight line, except insofar as it doesn't.

Science is one thing, wisdom is another. Science is an edged tool, with which men play like children, and cut their own fingers. If you look at the results which science has brought in its train, you will find them to consist almost wholly in elements of mischief. See how much belongs to the word "Explosion" alone, of which the ancients knew nothing.