He sold millions of books popularizing physics and mathematics. His lecture was even attended by the TV show's Sheldon Cooper, who is doing the same research as him in The Big Bang Theory - string theory. He says we are nothing but the characters acting out a drama that is scripted by mathematics and that our brains search for patterns in the world. God, he says, is an amazing invention of the human brain, who is created by the particles inside our heads. "But that doesn't mean I don't walk out the door after this interview and say: 'Hey, if you're really there, I'm really sorry,'" professor Brian Greene of Columbia University in New York.