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Then Hawking's luck turned. The progress of the disease slowed, and Einsteinian space-time suddenly seemed less formidable. But what really made the difference, he says, "was that I got engaged to Jane," who was studying modern languages at Cambridge. "This gave me something to live for." As he explains, "If we were to get married, I had to get a job. And to get a job, I had to finish my Ph.D. I started working hard for the first time in my life. To my surprise, I found I liked it."
What particularly intrigued Stephen was singularities, strange beasts predicted by general relativity. Einstein's equations indicated that when a star several times larger than the sun exhausts its nuclear fuel and collapses, its matter crushes together at its center with such force that it forms a singularity, an infinitely dense point with no dimensions and irresistible gravity. A voluminous region surrounding the singularity becomes a "black hole," from which -- because of that immense gravity -- nothing, not even light, can escape.
Scientists years ago found compelling evidence that black holes exist, but they were uncomfortable with singularities, because all scientific laws break down at these points. Most physicists believed that in the real universe the object at the heart of a black hole would be small (but not dimensionless) and extremely dense (but not infinitely so). Enter Hawking. While still a graduate student, he and Mathematician Roger Penrose developed new techniques proving mathematically that if general relativity is correct down to the smallest scale, singularities must exist. Hawking went on to demonstrate -- again, if general relativity is correct -- that the entire universe must have sprung from a singularity. As he wrote in his 1966 Ph.D. thesis, "There is a singularity in our past."
Stephen later discerned several new characteristics of black holes and demonstrated that the stupendous forces of the Big Bang would have created mini-black holes, each with a mass about that of a terrestrial mountain, but no larger than the subatomic proton. Then, applying the quantum theory (which accurately describes the random, uncertain subatomic world) instead of general relativity (which, it turns out, falters in that tiny realm), Hawking was startled to find that the mini-black holes must emit particles and radiation. Even more remarkable, the little holes would gradually evaporate and, 10 billion years or so after their creation, explode with the energy of millions of H-bombs.
Other physicists, long wedded to the notion that nothing can escape from a black hole, have generally come to accept that discovery. And the stuff emitted from little black holes (and big ones too, but far more slowly) is now called Hawking radiation. "In general relativity and early cosmology, Hawking is the hero," says Rocky Kolb, a physicist at Fermilab in Illinois. Caltech Physicist Kip Thorne agrees: "I would rank him, besides Einstein, as the best in our field." And what if a mini-black hole explosion is finally observed? "I would get the Nobel Prize," says Stephen, matter-of-factly.