MICHIO KAKU: When I was a child, I, too, read Isaac Asimov's Foundation series, and it forced you to confront the question: Where will we be 50,000 years from now?

Now, remember, science fiction, when I was a kid, was just shoot 'em up cowboy movies in outer space. That's all it was. However, Isaac Asimov forced you to come to grips with the fact that we're going to be exhausting the known laws of physics pretty soon. We have a very good grasp of the electromagnetic, the strong, the weak forces, gravity, but beyond that lies the unified field theory; the theory that eluded Einstein for the last 30 years of his life, the theory that I work on professionally -- that's my day job; I work on something called string theory, which we think is the theory of everything, and this theory could dominate our destiny in the coming millennia. Now, this means, of course, starships. Already, NASA has something called the 100 Year Starship program, very ambitious, however, a lot of it's still theoretical. We don't know for sure what it would take to go to the stars. Stephen Hawking, my colleague, the late Stephen Hawking, talked about shooting computer chips, tiny computer chips boosted by laser beams to 20% the speed of light, capable of reaching Alpha Centauri in 20 years time. But then, of course, we want to go beyond that. One day, we're going to have fusion rockets, anti-matter rockets, rockets that can take us to the nearby stars, not just computer chips, but people. And then beyond that, who knows? Maybe our destiny really does lie in outer space.

Remember that on the earth, 99.9% of all species eventually go extinct. Extinction is the norm. We think of Mother Nature as being warm and cuddly, and for the most part, she is. But sometimes, the savagery of Mother Nature is revealed. And if you don't believe me, dig underneath your feet. Right under your feet, right now, are the bones, the bones of all the different organisms, of fossils, the 99.9% that were doomed by the laws of nature. And the laws of physics also doom the entire planet Earth. And that's why I say, given the fact that Mother Nature and the laws of physics have a death warrant for humanity, that ultimately our destiny will be in outer space.