"I have always been very optimistic about the future of the human race."

"I think that the human race has a future, but it's going to be a challenging one."

"Look up at the stars and not down at your feet. Try to make sense of what you see, and wonder about what makes the universe exist. Be curious."

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

"We are all driven by a desire to understand the universe."