The elevator doors opened into a cavernous room in an underground tunnel outside Geneva. Out came the eminent British astrophysicist Stephen Hawking, in a wheelchair as always. He was there to behold a wondrous sight. Before him loomed a giant device called a particle detector, a component of an incredible machine whose job is to accelerate tiny fragments of matter to nearly the speed of light, then smash them together with a fury far greater than any natural collision on earth.
Paralyzed by a degenerative nerve disease, Hawking is one of the world's most accomplished physicists, renowned for his breakthroughs in...