““One of the things that I wanted to find out when I started working on the book—that's always fascinated me—I have great admiration for scientists and what they do. It is not just to find out what we know, but *how we know what we know*. I've always found that particularly fascinating. How do we know—how does anybody know—how much the Earth weighs, or what's going on in the middle of the planet, or how many millions of miles away Jupiter is, or any of that kind of thing? How do people figure that out?””
