What happens to data after it has travelled beyond a black hole's event horizon? The geometry of wormholes has been suggested as a possible solution to this perplexing problem, but the math has proven difficult to say the least.
An
international group of physicists has discovered a workaround for better
understanding how a collapsing black hole might avoid breaching quantum
physics' fundamental laws in a new publication (more on that in a bit).
Despite
its theoretical nature, the research shows that there are likely things we are
overlooking in our quest to reconcile general relativity with quantum physics.
PhysicistKanato Goto of Cornell University and RIKEN in Japan says, "We uncovered a
new spacetime geometry with a wormhole-like structure that had been disregarded
in standard computations."
"Computing entropy with this new shape yields a completely different answer."
One of the
outstanding difficulties between Einstein's theory of general relativity and
quantum physics is the black hole information dilemma.
The event
horizon of a black hole is a point of no return in general relativity. Beyond
that critical point, everything is inevitably sucked into the black holes
gravitational well, and no speed in the Universe, not even the speed of light
in a vacuum, is sufficient for escape velocity. That's it, it's gone. Kaput.
Irretrievable.
Then, in
the 1970s, Stephen Hawking proposed that, when quantum mechanics is taken into
account, black holes might indeed produce radiation.
According
to theory, this occurs as a result of the black hole's interference with the
wave-like properties of surrounding particles, thus causing it to 'light' at a
temperature that rises as the black hole shrinks.
This glow
should eventually shrink a black hole to nothingness.
"Black
hole evaporation" is named after the fact that the black hole shrinks like
a vaporising water droplet, according to Goto.
Because
the 'light' does not appear to be the same as what went into the black hole in
the first place, it appears that whatever was in the evaporated black hole is
no longer there. However, information cannot just vanish from the Universe,
according to quantum mechanics. Many physicists have looked into the notion
that information is encoded in Hawking radiation in some way.
Goto and
his colleagues planned to investigate this idea analytically by calculating the
entropy of Hawking radiation surrounding a black hole. This is a system's
measure of disorder, and it can be used to detect information loss in Hawking
radiation.
According
to physicist Don Page's 1993 study, the paradox of missing information should
be avoided if disorder reverses and entropy goes to zero when a black hole
evaporates. Unfortunately, quantum mechanics does not allow for this reversal.
Enter a
wormhole, or at least a mathematical representation of one, under extremely
certain Universe models. This is a bridge that connects two sections of a
curved sheet of spacetime, similar to a ravine bridge.
Goto
claims that thinking about it this way in connection with black holes gives us
a new approach of determining the entropy of Hawking radiation.
"Like a bridge, a wormhole connects the interior of the black hole to the radiation outside," he explains.
The
results of the team's computations utilising the wormhole model were identical
to the Page entropy curve. This shows that information sucked beyond a black
hole's event horizon may not be lost forever after all.
However,
there are still some unanswered questions. We won't be able to call the black
hole information paradox solved until these questions are answered.
"We still don't understand the core mechanics of how radiation carries information away," Goto explains. "We need a quantum gravity theory."
References:
- Goto, K., Hartman, T. & Tajdini, A. Replica wormholes for an evaporating 2D black hole. J. High Energ. Phys. 2021, 289 (2021). https://doi.org/10.1007/JHEP04(2021)289
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