There’s no better guarantee of failure than convincing yourself that success is impossible, and therefore never even trying.

So with each advance in understanding come new questions. So we need to be very humble. We shouldn’t have hubris and think that we can understand everything. But history tells us that there is good reason to believe that we will continue making fantastic progress in the years ahead.

In 2056, I think you'll be able to buy T-shirts on which are printed equations describing the unified laws of our universe.

The core of a scientific lifestyle is to change your mind when faced with information that disagrees with your views, avoiding intellectual inertia, yet many of us praise leaders who stubbornly stick to their views as "strong."

For me, [John Wheeler] was the last Titan, the only physics superhero still standing.

Our external physical reality is a mathematical structure.

This brief century of ours is arguably the most significant one in the history of our universe. We'll have the technology either to self-destruct, or [to] seed our cosmos with life. The situation is so unstable that I doubt we can dwell at this fork in the road for more than another hundred years. But if we end up going the life route instead of the death route, then in a distant future our cosmos will be teaming with life, all of which can be traced back to what we do-here and now. I don't know how we'll be thought of, but I'm sure that we won't be remembered as insignificant.