# Book of Leonard Sasskind “The Battle of the Black Hole”

It’s great to sometimes read quality books that talk about complex scientific theories in a popular language. Of course, after such books it is impossible to say that you understand these theories, but to get at least a general idea of them is useful. One of these great books is The Battle of the Black Hole by theoretical physicist Leonard Sasskind. The second title of the book is “My battle with Stephen Hawking for a world safe for quantum mechanics.”

The core of the book is a scientific dispute between the author and his supporters with Stephen Hoging (and his supporters) on the question of whether information that has fallen into the black hole without a trace disappears, or whether it can somehow be extracted from there (theoretically). Hawking thought that the information was missing, but that means that in this case one of the basic principles of quantum mechanics should stop working, which worried Sasskind and his friend, Nobel Prize winner Gerard 't Hooft (I wonder what such an apostrophe means at the beginning of a surname? ) Susskind tried to prove that information can be extracted (again, theoretically) by collecting particles that form when a black hole evaporates. The most interesting thing is that this very evaporation of black holes was predicted and justified by the same Hawking back in 1974, and now this radiation bears his name.

Susskind tells how over the years (from 1983 to the two thousandths) various theories appeared that interacted with each other and which as a result helped to answer the question posed, of course, in favor of the author of the book. The most remarkable thing in this whole story is that this debate was purely scientific, did not outgrow the debate and did not affect the relations between the two sides.

But for me, the most interesting thing in this book was a description of the theories that have appeared over the past decades in quantum physics, black hole theory, and some other areas. Susskind begins the book with a description of theories that they study back in school (at least they studied when I was studying there) - Einstein's theory of relativity (special and general), quantum theory, speaks of entropy from the point of view of information theory and thermodynamics, briefly mentions non-Euclidean geometry.

I liked in the book that the author, on the one hand, tries to avoid formulas, explaining all the physics on fingers and analogies (while indicating where the analogy does not work), but at the same time, where some calculations are necessary, it’s true, however completely ignoring the dimensions, which is why during the reading I had to remember, for example, in what the entropy is measured.

The author in this book talks about some theories already accepted in the scientific community, from which the head goes around. From the very first pages, he warns that physicists have already experienced several paradigm shifts (in the words of Thomas Kuhn) that forced them to update the “firmware” of the brain (these are already Susskind’s words), and lately, thanks to the development of theoretical physics, there have been quite a few such reflashes . What, for example, is the fact that, from the point of view of quantum theory, all information in three-dimensional space can be placed on a two-dimensional (closed?) Surface that covers this volume of space, i.e. what we see around ourselves theoretically can be a hologram, information for which is recorded somewhere far away on a two-dimensional surface. If it weren’t written by a physicist (moreover, he writes, Since this theory is accepted and so far no errors have been found in it), I would regard this as a television delirium about aliens and flying saucers. I will quote from the book:

In the last chapters of the book, Susskind talks about string theory, which was described wonderfully by Brown Green in his book The Elegant Universe. These are already very difficult chapters, if before that it was possible to trace the logic of explanation in order to understand the physics of phenomena, then here everything has to be taken on faith, or, more correctly, said, because string theory itself is a terribly mathematical theory , and it is from mathematics that its explanations of physics follow.

As a result, if you are interested in physics, then you should read this book to broaden your horizons. It was written in a very understandable language (only the last chapters were given to me hard), in addition to the description of physics, various stories from the author’s life are given, at least somehow related to the main theme of the book. As a nit-picking one can say that there are a lot of typos in the book (inconsistent endings, etc.), but this does not affect the overall quality of the book.

PS. Link to the habrapost about the book from the publisher .

The core of the book is a scientific dispute between the author and his supporters with Stephen Hoging (and his supporters) on the question of whether information that has fallen into the black hole without a trace disappears, or whether it can somehow be extracted from there (theoretically). Hawking thought that the information was missing, but that means that in this case one of the basic principles of quantum mechanics should stop working, which worried Sasskind and his friend, Nobel Prize winner Gerard 't Hooft (I wonder what such an apostrophe means at the beginning of a surname? ) Susskind tried to prove that information can be extracted (again, theoretically) by collecting particles that form when a black hole evaporates. The most interesting thing is that this very evaporation of black holes was predicted and justified by the same Hawking back in 1974, and now this radiation bears his name.

Susskind tells how over the years (from 1983 to the two thousandths) various theories appeared that interacted with each other and which as a result helped to answer the question posed, of course, in favor of the author of the book. The most remarkable thing in this whole story is that this debate was purely scientific, did not outgrow the debate and did not affect the relations between the two sides.

But for me, the most interesting thing in this book was a description of the theories that have appeared over the past decades in quantum physics, black hole theory, and some other areas. Susskind begins the book with a description of theories that they study back in school (at least they studied when I was studying there) - Einstein's theory of relativity (special and general), quantum theory, speaks of entropy from the point of view of information theory and thermodynamics, briefly mentions non-Euclidean geometry.

I liked in the book that the author, on the one hand, tries to avoid formulas, explaining all the physics on fingers and analogies (while indicating where the analogy does not work), but at the same time, where some calculations are necessary, it’s true, however completely ignoring the dimensions, which is why during the reading I had to remember, for example, in what the entropy is measured.

The author in this book talks about some theories already accepted in the scientific community, from which the head goes around. From the very first pages, he warns that physicists have already experienced several paradigm shifts (in the words of Thomas Kuhn) that forced them to update the “firmware” of the brain (these are already Susskind’s words), and lately, thanks to the development of theoretical physics, there have been quite a few such reflashes . What, for example, is the fact that, from the point of view of quantum theory, all information in three-dimensional space can be placed on a two-dimensional (closed?) Surface that covers this volume of space, i.e. what we see around ourselves theoretically can be a hologram, information for which is recorded somewhere far away on a two-dimensional surface. If it weren’t written by a physicist (moreover, he writes, Since this theory is accepted and so far no errors have been found in it), I would regard this as a television delirium about aliens and flying saucers. I will quote from the book:

Putting it all together, we get a proof of an amazing fact: the maximum number of bits of information that can fit in any area of space under any conditions is equal to the number of Planck pixels that can fit on the area of its border. Implicitly, this means that there is a “boundary description” of everything that happens inside the region of space; the boundary surface is a two-dimensional hologram of a three-dimensional internal region.

In the last chapters of the book, Susskind talks about string theory, which was described wonderfully by Brown Green in his book The Elegant Universe. These are already very difficult chapters, if before that it was possible to trace the logic of explanation in order to understand the physics of phenomena, then here everything has to be taken on faith, or, more correctly, said, because string theory itself is a terribly mathematical theory , and it is from mathematics that its explanations of physics follow.

As a result, if you are interested in physics, then you should read this book to broaden your horizons. It was written in a very understandable language (only the last chapters were given to me hard), in addition to the description of physics, various stories from the author’s life are given, at least somehow related to the main theme of the book. As a nit-picking one can say that there are a lot of typos in the book (inconsistent endings, etc.), but this does not affect the overall quality of the book.

PS. Link to the habrapost about the book from the publisher .