Nothing, not even light, can ever escape from a black hole. These drainpipes of the universe contain matter to heavy and no highly concentrated that gravitational attraction overwhelms all other forces. Yet astronomers believe that today's universe exploded out of a gargantuan black hole in a "high bang" billions of years ago, and that it may collapse back into such a black hold again.

English astrophysicist Steven Hawking, who spent the last two weeks at Harvard lecturing and meeting with researchers, has devoted most of his life to studying these gashes in the fabric of space and time. I've always wanted to understand why the world is what it is and how it works," says Hawking, now a successor to Sir Isaac Newton as Lucastan Professor of Mathematics at Cambridge University. Since, according to Hawking, "we already know completely the laws that govern normal matter," his goal is to extend such knowledge to extreme conditions. Nothing is more extreme than a black hole.

Most of a Hawking's research to date has focused on relativity, the theory developed by Albert Einstem to show that the laws of physics are the same everywhere and that apparent differences are caused only by the relative motions of various observers or by the forces acting on them. Hawking's work has so transformed our conceptions of black holes and gravitation that many physicists consider him the most important relatively theorist since Einstein.

I don't know anybody who's contributed more to the study of black holes," said John Archibald Wheeler, inventor of the term "black hold" and a professor of physics at the University of Texas at Austin

For instance, until recently astronomers beleived that black holes were cold and didn't emit radiation This seemed logical since the gravitational of a black hole would be strong enough to keep any radiation from escaping But Steven Hawking, applying the theory of quantum mechanics to black holes, proved that they do give off radiation, in other words, black holes are sort of gray.

Amazingly, Hawking has done his ground-breaking research despite a tremendous handicap. For the last 20 years the physicist has suffered from Lou Gehrig's disease, a terminal degenerative illness of the nerves and muscles. Now, at 40, Hawking remains confined to an electrically controlled wheelchair and has difficulty holding his neck up when he speaks. Even then his voice barely escapes--it comes out sometimes as a guttural moan--and Hawking generally travels with an interpreter.

Despite his illness, Hawking impresses all who meet him with his cheerfulness and almost childlike joy, and is always smiling and making quips. Wheeler, who has known Hawking for many years, said that despite his disease. "He's still in a way the same Steven. He's got the light of life--the hope, the liveliness, the sparkle--in his eyes."

Hawking's prodigious research achievements and unceasing optimism in the face of his debilitating disease have been called a model for handicapped people. Many of his colleagues suggest that, in an odd twist of fate, Hawking's disease may have helped his work by forcing him to focus exclusively on the faraway physical world.

"Steven could have been a great physical if he hadn't been ill, but he might have chosen not to be," says William H. Press, professor of Astronomy and of Physics, and Malcolm J. Perry, a former graduate student of Hawking's at Cambridge who now teaches physics at Princeton, explains, "Most of us are subject to an infinite number of distributions. His illness has protected him from these."

But, as Arthur M. Jaffe, Harvard professor of Mathematical Physics and Hawking's host while he was here, puts it: "He can devote complete attention to his work. But it's a terrible price to pay."

The physicist, however, is certainly not a pure thinking-machine. Married for 17 years, he and his wife Jane have three children--two sons and one daughter. According to Hawking's former student Perry. "Everybody gets to know his family" because he's so open and friendly.

Asked whether he would like his children to pursue science. Hawking replies. "It's very hard for children to follow in their father's footsteps because they're likely to be overshadowed at the start. But my eldest son [Robert, now 12 years old] is very interested in mathematics and physics . . . ."

Hawking's father was a scientist too, a biologist who researched tropical diseases. Although his father encouraged him to pursue biology and medicine. Hawking avoided these fields because he thought they were too impercise. If he had been able to predict the explosion in molecular biology, however, the physicist says he might have chosen that route since it is "one of the most exciting fields in science today."

As a child, Hawking took apart clocks and motors to see if he could understand how they worked Today, using mathematics instead of screwdrivers, he disassembles parts of the faraway universe that he can't even touch and tries to picture their mechanics.

According to the uncertainty principle of quantum mechanics, it's impossible to determine both the location of a small practice and its velocity at the same time. This means that a particle and its anti-particle--its mirror image of opposite--can appear and disappear so long as they don't get too far apart before wiping each other out.