Lecture on the topic: “Astronomy. Space. Dreams

On April 12, at 19:00, in the “Bukvoed” shop (St. Petersburg, Ligovsky Prospect, 10), within the framework of the “Science is not a flour” project, a lecture on the topic “Astronomy. Space. Dreams. The lecture will be read by Alexey Pasechnik - astronomer, translator, scientific editor of the books L. Susskind. As part of the lecture, we turn to the four books of Susskind, the legendary American theoretical physicist, one of the creators of string theory - “The Battle of a Black Hole”, “Cosmic Landscape”, “The Theoretical Minimum. Everything you need to know about modern physics ”,“ Quantum mechanics. The theoretical minimum.

Below we present an excerpt from the book by L. Susskind “The Battle of a Black Hole. My battle with Stephen Hawking for peace, safe for quantum mechanics " -" Hawking Lecture "

This is what I remembered from Hawking. Stephen sat uncomfortably lounging in his wheeled chair, his head was too heavy to hold it straight, all the others fell silent in suspense. He was on the right side of the stage, from where he could see a large projection screen, and he could follow the audience. By this time, Stephen had lost the opportunity to speak in his own voice. His electronic voice was broadcasting a pre-recorded text, and the assistant manipulated the slide projector, standing behind him. The projector was synchronized with the recorded message, and it is not clear what the assistant did there at all.

Despite the mechanical timbre, his voice was full of personal sound. And Stephen's smile showed complete confidence and conviction. There is a mystery in his speeches: how does the presence of a fixed fragile body breathe so much life into events that otherwise would seem boring? Steven's subtle mimicry carries such magnetism and charisma as few people see.
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The report itself was not particularly memorable, at least in terms of its content. Stephen talked about what he was going to and didn’t want to talk about - CGHS theory and how CGHS developed it (he generously mentioned RST for the error found). His main message was that if you correctly do all the calculations in the CGHS, the results confirm his own theory that the information can not be displayed from a black hole. For Stephen, the CGHS lesson was that the mathematics of this theory simply proved his point of view. For me, the lesson was that not only the speculative picture is defective, but the mathematical foundations of quantum gravity, at least in the form in which they became part of the CGHS, are internally contradictory.

The most unexpected in the report of Stephen was the subsequent question and answer period. One of the conference organizers went up to the stage and asked the audience to ask questions. Usually questions are technical, and sometimes they are quite long, because the questioner wants to show that he understands the essence of the matter. But then there is a dead silence in the audience. A hundred admirers turn into silent monks in a strangely hushed cathedral. Stephen composes the answer. The method by which he communicates with the outside world is amazing. He cannot speak or raise his hand to sign. His muscles are so atrophied that they can hardly make any effort. He has neither the strength nor the coordination to type on the keyboard. If he doesn’t change my memory, at that time he gave signals, lightly pressing on the joystick.

On a small computer screen mounted on the arm of his chair, word sequences run more or less continuously and the letters flash. Stephen pulls them out one by one and saves them in a computer, forming a sentence or a pair. This can take up to ten minutes. While the oracle is the answer, there is silence in the room, as in a crypt. Against the backdrop of growing expectations and anxiety, all conversations are interrupted. Finally, the answer appears: it may be nothing more than “yes” or “no”, perhaps a phrase or a couple of phrases.

I saw this happen in a room with a hundred physicists, as well as in a small stadium with five thousand spectators, including the South American President, the Secretary of Defense and several senior generals. My reaction to this incredible silence ranged from surprise to severe irritation (why is my time being wasted on this farce?). I always wanted to make some noise, maybe just talk to my neighbor, but I never did.

What causes such admiring attention in Steven that a saint could reveal to him, revealing the deepest secrets of God and the Universe? Hawking is an arrogant man, narcissistic and ultimately self-centered. However, this is true for half of the people I know, including myself. I think that the answer to this question is partly related to the magic and mystery of disembodied intelligence that moves around the universe in a wheelchair. But partly, the fact is that theoretical physics is a small world consisting of people who have known each other for many years. For most of us, this is a continuation of the family, and Stephen is a beloved and deeply respected member of this family, even though he sometimes causes frustration and irritation. We are all very worried that he cannot communicate in any other way than in the boring and long way that he uses. Since we value his point of view, we sit and wait quietly. I also think that Steven’s degree of concentration in the process of drafting the answer is probably so high that he doesn’t even notice the strange
silence around.

As I said, the report was not memorable. Stephen made his usual statements: the information goes into a black hole and never returns. By the time the black hole evaporates, it completely disappears.

Immediately after Hawking, Gerard 't Hooft spoke. He is also a very charismatic person, causing universal admiration for the physical community. The speeches of Gerard produce a tremendous effect and earned him great respect. Although it is not always easy to understand, such a “mystery of the oracle” as with Hawking is not connected with it. He is quite a straightforward and quite tangible Dane.

Gerard’s presentations are always fun. He likes to use his body, illustrating different moments, and is able to prepare impressive graphics. After many years, I remember a video that he prepared to illustrate the horizon of a black hole. The sphere was randomly filled with black and white pixels. In the course of the video, the pixels began to flash, moving from black to white and back. The picture looked like white noise on a faulty TV. It was quite obvious that the ideas of 't Hooft are similar to my own in regard to the existence of an active layer of rapidly changing atoms of the horizon, generating the entropy of a black hole. (I was already afraid that he would intercept my applause by proposing his own version of the complementarity of black holes, but if he thought about it, he did not say.)

't Hooft - an extremely deep and original thinker. But, like so many originals, he often remains misunderstood. After his report on black holes, it became clear that he had lost contact with the audience. It’s not that the listeners get bored — not at all — but they didn’t understand its logic. Let me remind you: the horizon of a black hole was considered empty space, and not a defective television screen.

In general, I doubt that at least one person has changed his mind about the fate of information in a black hole. Nobody interviewed the audience, but I would appreciate that by this time the score was about 2: 1 in favor of Hawking.

What seemed surprising to me throughout the rest of the conference was the stubborn refusal to consider the right solution to the paradox. Most speakers mentioned three
possible solutions.

1. Information leaves with Hawking radiation.
2. Information disappears.
3. Information is ultimately held in a special tiny remnant of a black hole that persists after evaporation. (Usually the residue was not larger than the Planck size and not heavier than the Planck mass.)

One by one, the speakers repeated these three possibilities and immediately discarded the first one. There was a consensus among the speakers: information is either lost, as Hawking insisted, or is hidden in some tiny remnant that can absorb an unlimited amount of information. There may have been some defenders of the theory of daughter universes, but I do not remember that. Almost no one, with the exception of 't Hooft and a couple more people, expressed confidence in the ordinary laws of information and entropy.

Don Page came closest to expressing such confidence. Paige is a friendly Alaskan bear man with a huge appetite. Very mobile, noisy, fan of any extreme sports, Don is a walking contradiction, at least for my taste. He is an outstanding physicist and deep thinker. He has a very impressive level of understanding of quantum field theory, probability theory, information, black holes and the general foundations of the scientific method of knowledge. He is also an evangelical Christian. One day, he spent more than an hour explaining to me, using mathematical calculations, why the likelihood that Jesus is the son of God exceeds 96 percent. But his physics and mathematics are not ideological and brilliant. His work had a profound impact not only on my ideas about black holes, but also on this whole area of ​​knowledge.

In his speech, Don repeated the mantra about the three possibilities, but he seemed less inclined to discard the first option. It seemed to me that he really believed that black holes should respect the ordinary laws of nature, which require information to flow away when it evaporates. But he also did not see how to reconcile this with the principle of equivalence. It is simply amazing how physicists were then immune to the possibility of information leaks with Hawking radiation, like how it escapes with water boiling away from the kettle.