Using e-mail, I can communicate with scientists all over the world.

While there's life, there is hope.

I don't think the human race will survive the next thousand years, unless we spread into space.

It's the gravity that shapes the large scale structure of the universe, even though it is the weakest of four categories of forces

A million million million million (1 with twenty-four zeros after it) miles, the size of the observable universe.

I like physics, but I love cartoons.

Our population and our use of the finite resources of planet Earth are growing exponentially, along with our technical ability to change the environment for good or ill.