Saturday, September 24, 2022

Wormholes help shed light on the black hole information paradox

A mathematical analysis helps illuminate the puzzle over how information escapes from a black hole.

According to Einstein’s theory of general relativity, anything that falls into the black hole can not escape its clutches. In the 1970s, Stephen Hawking found that an isolated black hole would emit radiation but only when considered quantum mechanics.

This is known as black hole evaporation because the black hole shrinks. However, this led to the black hole information paradox. If the black hole evaporates entirely, physical information would permanently disappear in a black hole. However, this violates a core precept of quantum physics: the information cannot vanish from the Universe.

It means the general relativity and quantum mechanics as they currently stand are inconsistent with each other. Hence, scientists need to find a unified framework for quantum gravity.

Recently, RIKEN physicists have found that wormholes could help shed light on the mystery of what happens to information about matter consumed by black holes.

They explored how black holes mimic wormholes—providing an escape route for information.

Kanato Goto of the RIKEN Interdisciplinary Theoretical and Mathematical Sciences said, “This is not a wormhole in the real world, but a way of mathematically computing the entropy of the radiation. A wormhole connects the interior of the black hole and the radiation outside, like a bridge.”

In 1993, physicist Don Page calculated that if no information is lost, the entropy will initially grow but drop to zero as the black hole disappears.

But this concept proves wrong when physicists combine quantum mechanics with the standard description of a black hole in general relativity. The result shows- the entropy continually grows as the black hole shrinks, indicating information is lost.

Physicists, in this study, combined both the standard description of a black hole in general relativity and a wormhole picture. After performing a detailed analysis, they found that their result matched Page’s prediction.

This suggests that physicists are right to suspect that information is preserved even after the black hole disappears.

Goto said“We discovered a new spacetime geometry with a wormhole-like structure that had been overlooked in conventional computations. Entropy computed using this new geometry gives a completely different result.”

Journal Reference:

  1. Kanato Goto et al, Replica wormholes for an evaporating 2D black hole, Journal of High Energy Physics (2021). DOI: 10.1007/JHEP04(2021)289
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