Stephen Hawking has been an iconic figure in physics for the last half a century, making many groundbreaking discoveries on the nature of the universe. Yet while his mind roams to the farthest corners of reality, his body has become increasingly trapped by the advance of Lou Gehrig's disease, which has bound him to a wheelchair, without speech or movement except for a few facial muscles. Told in his youth that he would not live past his 20s, Hawking will turn 70 in 2012, and today he continues to inspire millions, drawing rock-concert-sized crowds wherever he lectures.