Science is the process that takes us from confusion to understanding.

One of the wonders of science is that it is completely universal. It crosses national boundaries with total ease.

So many galaxies, so many planets out there in the universe circling so many stars... it just feels like there's a very good chance that there is another Earth-like planet out there that is able to support some kind of life similar to what we're familiar with.

General relativity is in the old Newtonian framework where you predict what will happen, not the probability of what will happen. And putting together the probabilities of quantum mechanics with the certainty of general relativity, that's been the big challenge and that's why we have been excited about string theory, as it's one of the only approaches that can put it together.

We do not know whether there are extra dimensions or multiverse. Let's go forward with the possible ideas that come out of the mathematics. It's hard for us to imagine a universe that would have no time at all.

Black holes, we all know, are these regions where if an object falls in, it can't get out, but the puzzle that many struggled with over the decades is, what happens to the information that an object contains when it falls into a black hole. Is it simply lost?

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