"I'm not an atheist. I'm an agnostic. I don't know what's out there, and neither do you."

"Earth is a small planet, and we are not alone. We are not alone in the universe, and we are not alone on this planet."

"The most important thing is to never stop asking questions."

"The best thing about being a scientist is that you get to ask 'why?' all the time."

"I'm just trying to get people to think about the universe in a different way."