Mars once was wet and fertile. It's now bone dry. Something bad happened on Mars. I want to know what happened on Mars so that we may prevent it from happening here on Earth.

Extreme skepticism and extreme gullibility are two equal ways of not having to think at all. And I don't think I'm the first to say that.

When we see animals doing remarkable things, how do we know if we're simply seeing tricks or signs of real intelligence? Are talented animals just obeying commands, or do they have some kind of deeper understanding? One of the biggest challenges for animal researchers is to come up with tests that can distinguish between the two.

Do you realize that if you fall into a black hole, you will see the entire future of the Universe unfold in front of you in a matter of moments and you will emerge into another space-time created by the singularity of the black hole you just fell into?

A supernova is one of the most powerful explosions in the universe. It's so luminous, it can be seen across billions of light years. It releases as much energy in an instant as our sun will produce over its 10-billion-year lifetime.

I don't have specific television ambitions in the sense that I remain fundamentally and academic, and so, my innermost ambitions are what's the next discovery I can make; that's in my direct center.

I don't ever tell people what to do! Even if it seems and feels that way sometimes, I don't think I should tell a person how to spend their money. I try not to tell people what to read.