"What makes human beings unique? Some say it's language or tools. Others say it's logical reasoning. They obviously haven't met many humans."

"The ultimate goal of science is to provide a single theory that describes the whole universe."

"I think the universe is a lot stranger than we can imagine."

"It is a matter of common sense to take a method and try it. If it fails, admit it frankly and try another. But above all, try something."

"I am an optimist, but I am a realist who understands that science is a slow process."