One of the basic tenets of modern physics is that cosmological information (the stuff of the universe) is always conserved and at least hypothetically recoverable -- that is, that one can always reconstruct the past from the residue of information of today. In the late 1960s and early 1970s, however, cosmologist Stephen Hawking and others postulated that in the case of "black holes" -- locations in the universe where "gravitational abysses" swallow matter, energy, and even light -- such information was irretrievable, overturning this basic assumption of modern physics. Since then, many physicists, especially those working with "string theory" -- which hopes to produce a "Theory of Everything" that would explain all the forces of nature -- believed they had discovered evidence that information from black holes was hypothetically recoverable and that Hawking's assumption was false. This week the world famous physicist capitulated and announced at the 17th International Conference of General Relativity and Gravitation in Dublin, Ireland, that he was wrong and then presented a short summary of his new calculation that led him to change his mind.

He accompanied his announcement with the presentation of a baseball encyclopedia to California Institute of Technology's John Preskill -- the stake in a famous bet made in 1997 between Preskill and Hawking and another Cal Tech physicist, Kip Thorne, who agreed at the time with Hawking that what had been "swallowed" by a black hole was eternally irretrievable.

On the basis of a new calculation, Hawking has concluded that this basic assumption of physics is true and that information can escape a black hole. He told those in the audience at the general relativity conference, "I want to report that I think that I have solved a major problem in theoretical physics." Preskill, asked later, said that he had always dreamed of besting Hawking on this point in front of witnesses, but never dreamed it would be before the bulk of their peers.

Although Hawking talked as though he had nearly single handedly solved the problem, many physicists were somewhat reticent. Some agreed that his solution sounded credible, but that it would take time to understand and test his solution. Other remarked that many theorists in physics have proposed solutions to the problem over the last several years, although Hawking would not acknowledge the possible validity of their work before. In fact, Leonard Susskind, a theorist at Stanford, remarked, "Until Stephen's recent reversal, he was about the only person still getting it wrong."

Hawking (62) is a giant among theoretical physicists, not only for his ground-breaking theories, but also for making the wonder of physics and cosmology intriguing to the general public through his popular level books such as his Brief History of Time and also for mastering a challenging career as he suffers from the extremely debilitating disease of amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig's disease), which has confined him to a wheelchair, practically imobilizing him, and forcing him to "speak" by means of a specially modified voice synthesizer connected to a specially modified computer keyboard.

Susskind and his Dutch colleague, Gerar 't Hooft of the University of Utrecht, welcomed Hawking's change of mind, noting of his previous denial that information could be retrieved from black holes, "Stephen correctly understood that if this was true, it would lead to the downfall of much of 20th-century physics."

For the full story: Hawking's Good News for Cosmic Detectives.