Oftentimes, if you're talking to a seasoned interviewer who asks you a question, they may do a follow-up if they didn't quite get it. It's rare that they'll do a third or fourth or fifth or sixth follow-up, because there's an implicit, agreed-upon decorum that they move on. Kids don't necessarily move on if they don't get it.

The central idea of string theory is quite straightforward. If you examine any piece of matter ever more finely, at first you'll find molecules, atoms, sub-atomic particles. Probe the smaller particles, you'll find something else, a tiny vibrating filament of energy, a little tiny vibrating string.

We are living through a remarkably privileged era when certain deep truths about the cosmos are still within reach of the human spirit of exploration.

There may be many Big Bangs that happened at various and far-flung locations, each creating its own swelling, spatial expanse, each creating a universe - our universe being the result of only one of those Big Bangs.

...things are the way they are in our universe because if they weren't, we wouldn't be here to notice.

Sometimes attaining the deepest familiarity with a question is our best substitute for actually having the answer.

The bottom line is that time travel is allowed by the laws of physics.