For 50 years, theoretical physicists have tried to solve the famous black hole paradox, which predicts that these cosmic monsters are much more complex than general relativity suggests. The fact is that according to Einstein's theory, black holes are surprisingly simple. If you know the mass, charge, and rotation of a black hole, then you know everything you need to know about it. It turns out that black holes are one of the simplest and most understandable characters in the entire Universe. But this apparent simplicity creates a disturbing paradox. In the 1970s, famed astrophysicist Stephen Hawking realized that black holes are not completely black. Instead, they emit light through a subtle quantum mechanical process at their event horizons or the edges of black holes, from where nothing, not even light, can escape. Because black holes are so simple and can only be described with three numbers, all information about the material that gets into black holes is apparently locked away forever. It doesn't matter if you create a black hole from dead stars and interstellar dust or a black hole from cats; as long as these two black holes have the same spin, mass and charge, they will be identical. But what ultimately happens to information?

## Information paradox

The universe is amazing. And it's a pity that modern cities are so polluted with lighting, because the stars in the night sky are practically invisible. Meanwhile, if every night we saw the Milky Way out of the window, and every August we watched the Perseid stream from the comfort of our home, we would probably think about the Universe more often. In the end, the craziest physical theories, for example, about the multiplicity of worlds or that with the help of black holes it is possible to travel to this very Multiverse, may turn out to be reality, who knows.

In the meantime, Andrei Linde and other scientists suggest that our Big Bang was not the only one, the efforts of others are aimed at studying black holes, the existence of which was proved several years ago.

Stephen Hawking, who devoted a lot of scientific work to these space monsters, believed that as the black hole emits radiation, it evaporates, eventually disappearing completely - hence the so-called black hole information paradox. If a bunch of information falls into a black hole and the information cannot be destroyed, then when does the black hole disappear and where does all the information go?

A snapshot of a black hole taken with a network of telescopes spread over eight continents. What we see in the image is larger than our entire solar system. The mass of this black hole exceeds the solar mass by 6.5 billion times.

In a series of groundbreaking works, theoretical physicists have come painfully close to resolving the black hole information paradox that has fascinated and tormented them for nearly 50 years. Information, they now confidently say, is indeed slipping out of the black hole.

If you jump into a black hole, you will not be lost forever. Part by part, the information you need to repair your body will reappear. Most physicists have long assumed that this would be the case; this was the outcome of string theory, the leading candidate for a unified theory of everything. But the new calculations, while inspired by string theory, do not by themselves imply their existence.

The information comes out thanks to the action of gravity itself - just ordinary gravity with one layer of quantum effects, the researchers say. This is a kind of change in the role of gravity.

## Changing the role of gravity

According to Einstein's theory of general relativity, the gravity of a black hole is so strong that nothing can escape it. The more sophisticated understanding of black holes, developed by Stephen Hawking and his colleagues in the 1970s, did not question this principle. Hawking and others tried to describe matter in and around black holes using quantum theory, but they continued to describe gravity using Einstein's classical theory - a hybrid approach physicists call "semiclassical."

Although the approach predicted new effects around the perimeter of the hole, the interior remained strictly isolated. Physicists concluded that Hawking had made the correct semiclassical calculation - any further progress would have to treat gravity as quantum as well.

Such a black hole was seen by the filmmakers "Interstellar"

However, this is precisely what the authors of new studies dispute. According to Wired, they discovered additional semiclassical effects - new gravitational configurations that Einstein's theory allows, but which Hawking did not include.

At first muted, these effects start to dominate when the black hole gets very old. The hole transforms from a kingdom of hermits to a vigorously open system. Not only does information seep out, everything new that gets into it erupts almost immediately. The revised semiclassical theory has yet to explain exactly how information comes out, but over the past two years, the pace of discovery has been such that scientists have hints of a solution to the paradox.

One way or another, there is still a lot of work for theorists - spacetime itself seems to be disintegrating into a black hole, implying that spacetime is not the root level of reality, but an emerging structure from something deeper. And although Einstein understood gravity as the geometry of space-time, his theory also entails the decay of space-time, and this is why information can ultimately escape from its gravitational prison.

## Black holes, quantum computers and nonlocality

In numerous attempts to resolve the information paradox of black holes, researchers have resorted to computer simulations, which are in themselves a physical system; quantum modeling, in particular, is not entirely different from what it models. So physicists imagined that they were collecting all the radiation, injecting it into a massive quantum computer, and running a complete simulation of a black hole.

And this has led to remarkable results. Since the radiation is associated with the black hole from which it came, the quantum computer is also strongly associated with the black hole. As part of the simulation, quantum entanglement is transformed into a geometric relationship between the simulated black hole and the original. Simply put, they are connected by a wormhole.

There is a physical black hole and then simulated in a quantum computer, and there could be an exact copy of a wormhole in between,”said Douglas Stanford, a theoretical physicist at Stanford University and co-author of the new study. This idea is an example of the 2013 suggestion that quantum entanglement can be viewed as a wormhole. The wormhole, in turn, provides a secret tunnel through which information can enter.

Quantum computers for simulating black holes are closer than they seem.

Further discussion, inevitably, concerned how to literally understand all these wormholes. Wormholes are so deeply immersed in equations that their connection to reality seems weak, but they still have tangible consequences.By connecting two distant locations, wormholes allow events in one location to directly affect the distant location, except that a particle, force, or other influence does not cross the intermediate distance. This effect of physics is called nonlocality.

We have always known that there must be some non-local effects involved in gravity, and this is one of them, the researchers note. Things that you thought were independent are not really independent.

At first glance, this is amazing. Einstein built general relativity with the explicit goal of eliminating nonlocality from physics. Gravity does not travel through space instantly. It must propagate from one place to another with a finite speed, like any other interaction in nature.

But over the past decades, it has become clear to physicists that the symmetries on which relativity is based are creating a new generation of nonlocal effects.

So, in February 2020, a team of physicists discovered that the symmetries of the theory of relativity have even broader effects than is usually assumed, which can give space-time the quality of the mirror hall seen when analyzing black holes.

This is how a black hole bends space-time.

All this reinforces the conjecture of many physicists that space-time is not a root level of nature, but arises from some underlying mechanism that is not spatial or temporal. The new calculations say much the same thing, but without reference to duality or string theory. Wormholes arise because they are the only language that the path integral can use to convey that space is collapsing. This is geometry's way of saying that the universe is ultimately non-geometric.

And although physicists will take time to confirm or deny the results of the study, in the end, even the authors of the work did not expect to resolve the information paradox of black holes in this way and without a complete quantum theory of gravity. But if we assume that their calculations are correct, then the theory of black holes no longer contains the logical contradiction that makes it paradoxical. In a word, Viva physics and the human mind.