When Stefan Klein, an acclaimed journalist, sits down to talk with 18 of the world's leading scientists, he finds they're driven by, above all, curiosity. When they talk about their work, they turn to what's next, to what they still hope to discover. And they see inspiration everywhere: From the sports car that physicist Steven Weinberg says helped him on his quest for "the theory of everything" to the jazz musicians who gave psychologist Alison...