It is surprising that people do not believe that there is imagination in science. It is a very interesting kind of imagination, unlike that of the artist. The great difficulty is in trying to imagine something that you have never seen, that is consistent in every detail with what has already been seen, and that is different from what has been thought of; furthermore, it must be definite and not a vague proposition. That is indeed difficult.

The electron is a theory we use; it is so useful in understanding the way nature works that we can almost call it real.

All mass is interaction.

Although it is uncertain, it is necessary to make science useful. Science is only useful if it tells you about some experiment that has not been done; it is not good if it only tells you what just went on.

When you get as old as I am, you start to realize that you've told most of the good stuff you know to other people anyway.

The Quantum Universe has a quotation from me in every chapter - but it's a damn good book anyway.

... it is impossible to explain honestly the beauties of the laws of nature in a way that people can feel, without their having some deep understanding of mathematics. I am sorry, but this seems to be the case.