I did not set out to explain the extinction of the dinosaurs. I'm a particle physicist, and I was actually thinking about dark matter along with some collaborators.

One of the nice things about math and science is it’s obvious, you get the answer or you don’t get the answer.

If such external influences are intrinsic to religion, then logic and scientific thought dictate that there must be a mechanism by which this influence is transmitted. A religious or spiritual belief that involves an invisible undetectable force that nonetheless influences human actions and behavior or that of the world itself produces a situation in which a believer has no choice but to have faith and abandon logic--or simply not care.

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

The universe has its secrets. Extra dimensions of space might be one of them. If so, the universe has been hiding those dimensions, protecting them, keeping them coyly under wraps. From a casual glance, you would never suspect a thing.

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

There are many aspects of time we just do not understand. That’s the thing about writing a popular book: You realize the things you understand because for those you can give a really simple explanation. But some things about time I just don’t know how to give simple explanations for, even though I can tell you mathematically what’s going on.