Some things that satisfy the rules of algebra can be interesting to mathematicians even though they don't always represent a real situation.

There's plenty of room at the bottom.

Scientific knowledge is a body of statements of varying degrees of certainty -- some most unsure, some nearly sure, none absolutely certain.

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

It's because somebody knows something about it that we can't talk about physics. It's the things that nobody knows anything about we can discuss.

[B]eyond poverty, beyond the point that the material needs are reasonably satisfied, only from within is peace.

Progress in science comes when experiments contradict theory.