If information cannot be destroyed, what happens when a black hole that has swallowed a mega belly full of information disappears?
A seemingly unsolvable black hole paradox first proposed by physicist Stephen Hawking may finally be resolved, by wormholes through space time.
The “black hole information paradox” refers to the fact that information cannot be destroyed in the universe, and yet when a black hole eventually evaporates, any information sucked up by this cosmic vacuum cleaner should be long gone. . The new study proposes that the paradox could be resolved by means of nature. latest cheat code: wormholes or passages in space-time.
“A wormhole connects the inside of the black hole and the outside radiation, like a bridge,” said Kanato Goto, a theoretical physicist at RIKEN’s Interdisciplinary Program for Theoretical and Mathematical Sciences in Japan. he said in a press release.
According to Goto’s theory, a second surface appears within a black hole’s event horizon, the boundary beyond which nothing can escape. Threads from a wormhole connect this surface to the outside world, entangling information between the interior of the black hole and the radiation that seeps through its edges.
Black hole information paradox
In the 1970s, Hawking discovered that black holes aren’t exactly black, but at first he didn’t realize what a big problem he had created. Before his discovery, physicists had assumed that black holes were extremely simple. Sure, all sorts of complicated stuff fell into it, but the black holes locked away all that information, never to be seen again.
But Hawking discovered that black holes do release radiation and it can eventually evaporate completely, in a process now known as Hawking radiation, but this radiation itself did not carry information. In fact, he couldn’t; by definition, the event horizon of a black hole prevents information from getting out. So when a black hole evaporates and eventually disappears from the universe, where did all its locked up information go?
This is the black hole information paradox. One possibility is that the information could be destroyed, which seems to violate everything we know about physics. (For example, if information can be lost, the past cannot be reconstructed from present events or future events cannot be predicted.) Instead, most physicists try to resolve the paradox by finding a way, any way, for the information inside the black hole to escape. through Hawking radiation. Thus, when the black hole disappears, the information is still present in the universe.
Either way, describing this process requires new physics.
“This suggests that general relativity and quantum mechanics as they currently stand are incompatible with each other,” said Goto. “We need to find a unified framework for quantum gravity technology.”
A tale of two entropies
In 1992, physicist Don Page, a former Hawking graduate student, saw the problem of the information paradox differently. He started by looking at quantum entanglement, that is, when distant particles have their fates linked. This entanglement acts as the quantum mechanical connection between the Hawking radiation and the black hole itself. Page measured the amount of entanglement by calculating “entanglement entropy,” which is a measure of the amount of information contained in the entangled Hawking radiation.
In Hawking’s original calculation, no information is leaked and the entanglement entropy always increases until the black hole finally disappears. But Page found that if black holes release information, the entropy of entanglement initially increases; then, halfway through the black hole’s lifetime, it decreases before finally reaching zero, when the black hole evaporates (i.e., all the information inside the black hole eventually escaped).
If Page’s calculations are correct, it suggests that if black holes allow information to leak out, then something special must be happening halfway through their lives. Although Page’s work hasn’t solved the information paradox, it has given physicists something juicy to work on. If they could give black holes a mid-life crisis, then this solution could resolve the paradox.
More recently, various teams of theorists have applied mathematical techniques borrowed from string theory – an approach to unifying Einstein’s relativity with quantum mechanics – to examine this problem. They were examining how spacetime near an event horizon might be more complex than scientists initially thought. How complex? As intricate as possible, allowing for all kinds of bends and curves on a microscopic scale.
His work led to two surprising features. One was the appearance of an “extreme quantum surface” just below the event horizon. This inner surface moderates the amount of information that comes out of the black hole. At first glance, it is not very useful. But when the black hole is in the middle of its life, it begins to dominate entanglement, reducing the amount of information released, so that the entropy of entanglement follows Page’s predictions.
Second, the calculations revealed the presence of wormholes, lots of them. These wormholes seemed to connect the extreme quantum surface to the outside of the black hole, allowing information to bypass the event horizon and be released as Hawking radiation.
But this earlier work only applied to highly simplified “toy” models (such as one-dimensional versions of black holes). With Goto’s work, this same result has now been applied to more realistic scenarios, a major advance that brings this work closer to explaining reality.
However, there are many questions. For one thing, it is not yet clear whether the wormholes that appear in the math are the same wormholes that we think of as shortcuts in time and space.
They are so deeply buried in mathematics that it is difficult to determine their physical meaning. On the one hand, it could literally mean wormholes going in and out of an evaporating black hole. Or it could simply be a sign that spacetime near a black hole is not local, which is a feature of entanglement: two entangled particles don’t need to be in causal contact to influence each other.
Originally published on Live Science.