One theory is that the universe came from nothing. i.e. perhaps bubble-universes collided, as in a bubble bath, and gave birth to the universe. Or perhaps the big bang was created by a bubble-universe which split into two universes. The universe does seem to be compatible with nothing.

I had two passions when I was a child. First was to learn about Einstein's theory and help to complete his dream of a unified theory of everything. That's my day job. I work in something called string theory. I'm one of the founders of the subject. We hope to complete Einstein's dream of a theory of everything.

When I get bored, or get stuck on an equation, I like to go ice skating, but it makes you forget your problem. Then you can tackle the problem with a fresh new insight. Einstein liked to play the violin to relax. Every physicist likes to have a past time. Mine is ice skating.

Our grandkids will lead the lives of the gods of mythology. Zeus could think and move objects around. We'll have that power. Venus had a perfect, timeless body. We'll have that, too. Pegasus was a flying horse. We'll be able to modify life in the future.

I agree, along with Carl Sagan, that we should eventually become a two planet species. Life is too precious to place on a single planet.

Science fiction without the science just becomes, you know, sword and sorcery, basically stories about heroism and not much more.

A hydrogen bomb, for me, was puny compared to the Big Bang - the creation of the universe. That's what I really wanted to work on - the nature of the universe itself, and that's what I do for a living.