The whole argument started when Stephen Hawking attempted to describe what happens to matter during its lifetime in a black hole. He suggested that, from the perspective of quantum mechanics, the information about the quantum state of a particle that enters a black hole goes with it. This isn’t a problem until the black hole starts to boil away through what’s now called Hawking radiation, which creates a separate particle outside the event horizon while destroying one inside. This process ensures that the matter that escapes the black hole has no connection to the quantum state of the material that had gotten sucked in. As a result, information is destroyed. And that causes a problem, as the panel described.
As far as quantum mechanics is concerned, information about states is never destroyed. This isn’t just an observation; according to panelist Leonard Susskind, destroying information creates paradoxes that, although apparently minor, will gradually propagate and eventually cause inconsistencies in just about everything we think we understand. As panelist Leonard Susskind put it, “all we know about physics would fall apart if information is lost.”
Unfortunately, that’s precisely what Hawking suggested was happening. “Hawking used quantum theory to derive a result that was at odds with quantum theory,” as Nobel Laureate Gerard ‘t Hooft described the situation. Still, that wasn’t all bad; it created a paradox and “Paradoxes make physicists happy.”
“It was very hard to see what was wrong with what he was saying,” Susskind said, “and even harder to get Hawking to see what was wrong.”
The arguments apparently got very heated. Herman Verlinde, another physicist on the panel, described how there would often be silences when it was clear that Hawking had some thoughts on whatever was under discussion; these often ended when Hawking said “rubbish.” “When Hawking says ‘rubbish,’” he said, “you’ve lost the argument.”
Monday, August 1, 2011
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Posted by siobhan at 7:18 PM