"I'm a fairly aggressive tweeter. I like to engage with people who disagree with me, and try to educate them."

"The universe is a classroom, and we are all students."

"I'm often asked if I believe in UFOs. I'm open to the possibility, but I need evidence. I need the aliens to land on the White House lawn, or at least in my backyard, and say hello."

"If you are not in awe of the universe, you are not living."

"It's not about what you know, it's about what you can prove."