Stephen Hawking thought up how to save a black hole the information that fell into it

On August 25, the famous physicist and popularizer of science, Stephen Hawking, spoke about his new ideas about the physics of black holes. He did this during a lecture at the Royal Institute of Technology (KTH; Stockholm, Sweden), which was held as part of a weekly conference entirely devoted to developments in the field of black holes. In his opinion, the old paradox about the disappearance of information in a black hole is resolved by the fact that in reality the hole's horizon is a two-dimensional hologram.



According to modern concepts, a non-rotating and uncharged black hole is characterized by only one parameter - the mass. If any body falls into a hole, then all its characteristics and state at that time will not play any role - after its absorption, the hole will only increase its mass. This phenomenon was called the “lack of hair” in the BH - that is, the absence of any differences between the BH of the same mass.

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Moreover, if we consider the BH from the point of view of quantum physics, then it turns out that it has radiation (predicted by the same Hawking), because of which it gradually “evaporates”. The particle-antiparticle pairs originating on the horizon can scatter so that one proceeds inside the BH, and the other from it. Thus, the BH will lose mass and after a rather long time will disappear (more precisely, at least, decrease to Planck values). Any object caught in a BH, as a result, disappears without a trace , turning into radiation in no way connected with it. Even if the information about the object is stored inside the BH, it can in no way affect the BH emission.



Such metamorphoses, firstly, violate the laws of conservation of quantum numbers, and secondly, lead to nonunitary transformations. All this is a paradox and contradicts modern quantum mechanics, therefore such unsportsmanlike behavior of BH causes heated debates and encourages theorists to search for suitable explanations of what is happening .







For example, adherents of string theory, armed with additional compactified measurements, developed the theory of " fluffy tangle " ( fuzzball ). According to them, BH is a tangle of strings vibrating according to special laws. In this theory, there is no singularity, and even the interior of the BH - space-time ends at the event horizon, so the object can not get "inside" the BH. The “fall” of an object leads to a change in the vibrations of the fluffy ball, on which the BH radiation depends - as a result, the information does not disappear without a trace.



Japanese physicists have calculated on the supercomputer another version of the solution of the paradox proposed by the Dutch physicist Gerard 't Hooft. In this version, the BH can be represented as a giant two-dimensional hologram, inside of which information about the curvature of space-time is “recorded”. Due to this, we see not a flat BH, but a kind of three-dimensional sphere of emptiness. And in such a BH a paradox with information does not arise, since in fact the bodies falling in a BH interact with a two-dimensional object, and Hawking radiation directly depends on the processes occurring inside this object.



Hawking in Stockholm proposed his own solution to the paradox. According to him, the BH surface, that is, the event horizon, may itself be a hologram. Therefore, all information about an object fallen in a BH can be encoded in this hologram - being two-dimensional, it can save information about a three-dimensional object (just as a three-dimensional image of an object can be stored in a two-dimensional holography).



Therefore, this information is not lost, and it affects the radiation of the BH originating near its horizon. However, from a practical point of view, it is not possible to extract it from the radiation. The physicist himself brought such a colorful analogy: if you burn an encyclopedia and leave all the ashes, then theoretically the information will not be lost. But practically after that it will be very difficult to see in the encyclopedia the capital of the state of Minnesota.



At another lecture in Stockholm, which he read the day before, Hawking also mentioned another well-known theory that BHs can be portals to other universes . He did not dwell on this issue in detail, he only clarified that such a portal, if it exists, works only in one direction - it will be impossible to return back.