You're entitled to say, if you're so smart, why don't you tell me what that dark matter is? And I'll have to confess I don't know.

- Jim Peebles

I think I'd be depressed if everything were nearly all known, but I don't feel any danger of that happening.

- Jim Peebles

It is an embarrassment that the dominant forms of matter in the universe remain hypothetical.

- Jim Peebles