You have to be careful when you use beauty as a guide. There are many theories people didn't think were beautiful at the time but did find beautiful later—and vice versa. I think simplicity is a good guide: The more economical a theory, the better.

When it comes to the world around us, is there any choice but to explore?

Faith just doesn't have anything to do with what I'm doing as a scientist. It's nice if you can believe in God, because then you see more of a purpose in things. Even if you don't, though, it doesn't mean that there's no purpose. It doesn't mean that there's no goodness. I think that there's a virtue in being good in and of itself. I think that one can work with the world we have.

Both religions and musicals work best with energetic and committed believers. Cynicism or detachment would have destroyed the magic - something true of religion, too.

Maybe dark matter is denser than we usually assume, kind of like the Milky Way plane.

Speculation and the exploration of ideas beyond what we know with certainty are what lead to progress.

Sometimes models are surprisingly smart.