Too much openness and you accept every notion, idea, and hypothesis-which is tantamount to knowing nothing. Too much skepticism-especially rejection of new ideas before they are adequately tested-and you're not only unpleasantly grumpy, but also closed to the advance of science. A judicious mix is what we need.

You can get into a habit of thought in which you enjoy making fun of all those other people who don't see things as clearly as you do. We have to guard carefully against it.

The universe forces those who live in it to understand it.

[One's] inability to invalidate your hypothesis is not at all the same thing as proving it true.

Ask courageous questions. Do not be satisfied with superficial answers.

Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works.

Atoms are mainly empty space. Matter is composed chiefly of nothing.