New study sheds light on how information escapes from an evaporating black hole

(ORDO NEWS) — An international team of physicists from RIKEN, Cornell University and UC Santa Barbara have used a new wormhole space-time geometry to show that information is not necessarily irretrievably lost from evaporating black holes.

Einstein’s general theory of relativity predicted that if an object falls into a black hole’s event horizon, it will end up at the center of the black hole, called a singularity, where it will completely collapse.

In the 1970s, Stephen Hawking calculated that when quantum mechanics is taken into account, black holes should emit radiation.

“It’s called black hole evaporation because the black hole shrinks like an evaporating water drop,” says Dr. Kanato Goto, a researcher at the RIKEN Interdisciplinary Center for Theoretical and Mathematical Sciences and the Department of Physics at Cornell University.

However, this has led to a paradox. In the end, the black hole will completely evaporate – and all information about its swallowed contents, too. But this contradicts the fundamental postulate of quantum physics: information cannot disappear from the universe.

“This suggests that general relativity and quantum mechanics in their current form do not agree with each other. We must find a common basis for quantum gravity,” says Dr. Goto.

“Many physicists suspect that the information that escapes is somehow encoded in the radiation.”

“For the study, they calculate the entropy of radiation, which measures how much information is lost from the point of view of a person outside the black hole.”

“In 1993, physicist Don Page calculated that if information is not lost, then entropy will initially increase, but as the black hole disappears, it will drop to zero.”

“When physicists simply combine quantum mechanics with the standard description of a black hole in general relativity, it turns out that Page is wrong – entropy is constantly increasing as the black hole shrinks, indicating a loss of information.”

But recently, physicists have been investigating how black holes mimic wormholes – providing a pathway for information to leak.

“This is not a wormhole in the real world, but a way to mathematically calculate the entropy of radiation,” Dr. Goto said. “A wormhole connects the inside of a black hole and the radiation outside, like a bridge.”

When Dr. Goto and his colleagues performed a detailed analysis, combining the standard description and picture of a wormhole, their result matched Page’s prediction, which suggests that physicists are right in suspecting that information persists even after the death of a black hole.

“We have discovered a new space-time geometry with a wormhole-like structure that has been overlooked in conventional calculations,” said Dr. Goto. “The entropy calculated using this new geometry gives a completely different result.”

“But this raises new questions. We still don’t know the underlying mechanism of how information is carried away by radiation. We need a theory of quantum gravity.”


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