Why, you might wonder, did British physicist Stephen Hawking, who died this morning at age 76, never win a Nobel Prize? The answer is simple. Nobel Prizes are not awarded for speculations. Einstein did not win the Nobel for relativity. Hawking chose to work in the most speculative field imaginable—abstract cosmology. Did time have a beginning? And if it did, did it have another form? Say, imaginary time? He is perhaps best known for his theory of “Hawking radiation”—radiation that emanates from black holes and has a temperature inversely proportional to the mass of the black hole. This accounts for why all the black holes we know about, such as the one at the center of our galaxy, are still there while we have no proton-sized black holes.
Hawking studied whether black holes might have singularities at their center at which all quantities become infinite. This is the kind of work that fascinates specialists, and indeed the general public, when it is explained as brilliantly as he did in his immensely popular book A Brief History of Time (1988). But it is not the kind of work that will win you a Nobel Prize. In 1989, I saw Hawking close at hand when, for a couple of weeks, he occupied an office next to mine at the Physics Center in Aspen, Colorado. He still was able to work his voice synthesizer. I would like to have asked him how he came up with “Hawking radiation,” but he seemed so preoccupied that I lacked the courage to interrupt—a missed opportunity that I will always regret. Hawking was a unique phenomenon in science and one we may never see again.