Hawking's answer is that the black holes hold their contents for eons but themselves eventually deteriorate and die. As the black hole disintegrates, they send their transformed contents back out into the infinite universal horizons from which they came.

Previously, Hawking, 62, had held out the possibility that disappearing matter travels into a new parallel universe within the black hole the very stuff of most visionary science fiction.

''There is no baby universe branching off, as I once thought. The information remains firmly in our universe,'' Hawking said in a speech to about 800 physicists and other scientists from 50 countries.

''I'm sorry to disappoint science fiction fans, but if information is preserved, there is no possibility of using black holes to travel to other universes,'' he said.

''If you jump into a black hole, your mass energy will be returned to our universe, but in a mangled form, which contains the information about what you were like, but in an unrecognizable state,'' he said with a smile, sparking laughter from the audience.

Hawking added, ''It is great to solve a problem that has been troubling me for nearly 30 years, even though the answer is less exciting than the alternative I suggested.''

In a humorous aside, Hawking settled a 7-year-old bet made with Caltech astrophysicist John Preskill, who insisted in 1997 that matter consumed by black holes couldn't be destroyed. He presented Preskill a favored reference work ''Total Baseball, The Ultimate Baseball Encyclopedia'' after having it specially flown over from the United States.

''I had great difficulty in finding one over here, so I offered him an encyclopedia of cricket as an alternative,'' Hawking said, ''but John wouldn't be persuaded of the superiority of cricket.''

Later, Preskill said he was very pleased to have won the bet, but added: ''I'll be honest, I didn't understand the talk.'' Like other scientists there, he said he looked forward to reading the detailed paper that Hawking is expected to publish next month.

Hawking pioneered the understanding of black holes the matter-consuming vortexes created when stars collapse in the mid-1970s. He has previously insisted that the holes emit radiation but never cough up any trace of matter consumed, a view that conflicts with subatomic theory and its view that matter can never be completely destroyed.

Hawking, a mathematics professor at Cambridge University, shot to international fame with his best-selling book ''A Brief History of Time,'' which sought to explain to a general audience the most complex aspects of how the universe works.

Despite being virtually paralyzed and forced to rely on a wheelchair with amyotrophic lateral sclerosis since his mid-20s, Hawking travels the world on speaking engagements. He communicates by using a hand-held device to select words on his wheelchair's computer screen, then sending them to a speech synthesizer.

The slow process of constructing answers meant that, in the press conference that followed his paper, Hawking was able to answer only two questions in a half-hour. The final questioner asked him what problem he intended to tackle next, now that he had solved the paradox of the black hole.

''I don't know,'' Hawking quickly replied, bringing the house down with laughter.

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