"If you want to understand the universe, you have to be willing to ask the tough questions."

"I'm not a vegetarian, but I do believe that we should be more mindful of where our food comes from, and how it's produced."

"I'm not saying there are no aliens. I'm just saying the evidence is insufficient for me to conclude it."

"If you're ever feeling small, just remember that you're made of stardust, and you're part of something much bigger than yourself."

"I think the best way to learn is to teach."