The human brain has 100 billion neurons, each neuron connected to 10 thousand other neurons. Sitting on your shoulders is the most complicated object in the known universe.

In fact, all of us have a piece of Chernobyl in our bodies going back to 1986.

Sooner or later, we will face a catastrophic threat from space. Of all the possible threats, only a gigantic asteroid hit can destroy the entire planet. If we prepare now, we better our odds of survival. The dinosaurs never knew what hit them.

I hope we find evidence of dark matter in the lab and in outer space. This would go a long way to proving the correctness of string theory, which is what I do for a living. That is my day job. So string theory is a potentially experimentally verifiable theory.

For relaxation, I like to figure skate. Being on the ice and spinning and jumping, I feel very close to nature. In particular, I feel very close to Newton's laws of motion. On the ice, you can experience Newton's laws of motion in their purest, most elegant form.

I think a colony in space will take much longer than sci fiction writers think. It costs $10,000 to put a pound of anything into near earth orbit. That is your weight in gold. It costs about $100,000 a pound to put you on the moon. And it costs $1,000,000 a pound to put you on Mars.

Hover boards, unfortunately, currently violate the laws of physics. Supermagnets exist, but they have to be cooled to near absolute zero, and they are extremely expensive. So Michael J. Fox's hover boards are not possible until we invent room temperature super conductors.