Hawking reverses self on black holes

By DENNIS OVERBYE

July 22, 2004

New York Times News Service

Stephen Hawking threw in the towel Thursday, or at least an encyclopedia.

Hawking, the celebrated Cambridge University cosmologist and best-selling author, declared at a scientific conference in Dublin, Ireland, that he had been wrong in a controversial assertion he made 30 years ago about black holes, the fearsome gravitational abysses that can swallow matter and energy, even light.

As atonement he presented John Preskill, a physicist from the California Institute of Technology, with a baseball encyclopedia.

The encyclopedia was the stake in a famous bet Hawking and another Caltech physicist, Kip Thorne, made with Preskill in 1997. Hawking and Thorne said information about what had been swallowed by a black hole could never be retrieved from it; Preskill and many other physicists said it could. The winner was to get an encyclopedia, from which information could be freely retrieved.

This esoteric sounding debate is of great consequence to science, because if Hawking had been right, it would have violated a basic tenet of modern physics: that it is always possible to reverse time, run the proverbial film backward and reconstruct what happened in, say, the collision of two cars or the collapse of a dead star into a black hole.

Now, on the basis of a new calculation, Hawking has concluded that physics is safe and information can escape from a black hole. "I want to report that I think that I have solved a major problem in theoretical physics," he told his colleagues, according to a transcript of his remarks.

Standing in front of television cameras, as well as an auditorium full of physicists, Preskill said he had always dreamed that there would be witnesses when Hawking conceded, but "this really exceeds my expectations," according to an account by The Associated Press.

Hawking’s new calculation was received by other physicists with reserve. They cautioned that it would take time to understand it. Some of them emphasized that a long line of work by various theorists in recent years suggested that information could escape from black holes.

"Until Stephen’s recent reversal, he was about the only person still getting it wrong," said Leonard Susskind, a theorist at Stanford.