At first I was put off by the simplicity of the narative. Appeared and felt like a book on physics simply dumbed down -- but as I got further into the writing I found the writing style grew on me -- that this is an excellent writing on QM that is accessable to my nieces. L. Susskind is very thorough in his presentation, and after the first 100 pages or so, just paints an exciting picture that is very easy to follow, and, again, what is more impactful -- one simply WANTS to find out the "next step." OK -- Christmas gift for my nieces??

The book discusses a problem. According to Hawking, when an object falls down a black hole (BH), all information is lost. The problem is that this violates a principle of physics that information is never lost. The future cannot lose track of the past, for then the past would cease to exist, as the only meaning to the past is present observations and records. Susskind proposes a solution that took him a decade to resolve, and he discusses this in the book. The solution is the Holographic Principle, which is that all the information inside the 3-dimensional sphere of the BH resides on the 2-dimensional surface. An object falling down a BH never crosses the surface, and so the information is not lost. There is a "dual description" that does not refer to the inside.

Susskind makes heavy use of String Theory to establish the theory. Actually, one can arrive at the same conclusion without the use of String Theory or quantum mechanics, by simply focusing on basic principles of physics and general relativity (GR). According to GR, it takes an object forever to reach the BH, and so it never gets inside. We therefore cannot speak about the inside. Everything falling down a BH is eternally falling, and so the information is not lost. We cannot speak about the inside of the BH. This then is exactly Susskind's Holographic Principle, where all information is outside the BH.

Science, and in particular physics, is a collection of theories. A theory is a mathematical system along with observational and experimental agreement. If it is impossible in principle to perform an observation, the theory cannot speak about that situation. Science also includes guesses, research proposals, and hypotheses, not all of which are theories.

The confusion arises from the formal existence of a solution of GR that from the viewpoint of the falling object, the object crosses the event horizon in finite time. However, since it is impossible in principle to observe an object "entering" the BH, this formal solution does not exist in reality.

If we accept the argument that something that a falling observer (someone who cannot return nor communicate with the rest of the world) can observe is considered as a valid scientific observation, we then lose our ability to criticize people for believing that the dead go to Heaven. The dead person (one who cannot return nor communicate with the rest of the world) observes Heaven. We scientists must be very careful about our scientific reasoning, and not give others the opportunity to twist it to make it sound as if we support religion, as is, unfortunately, often the case.

In summary, the principle of objective observation implies that no object can enter a BH.

Another point is that the formal solution of GR from the viewpoint of the falling observer is not a valid solution of GR. This is due to the proven existence of a singularity at the center. Since the object reaches the singularity in finite time, this solution is not valid. If we insist on accepting this formal solution, we get into paradoxes, as is usually the case when one accepts formal invalid solutions.

According to the Holographic Principle, no future theory can discuss the inside of a BH.

I gave four stars. The book makes excellent reading. It helps clarify some aspects of String Theory. For this, I give it three stars. His points about information residing outside the BH give it another star. I do not give it five stars, as his main point about where the information is can be proven by understanding and applying basic principles of science. We scientists and teachers must never lose sight of basic principles.

Susskind makes the common error of defining a BH as a place where light cannot escape, implying that the idea of an inside of a BH is a meaningful concept, contradicting his own Holographic Principle. A correct definition of a BH is a mass so large that objects falling towards it are time-dilated and red-shifted out of existence.

Another error in the book is mentioning "the 3-dimensional space inside the BH". The geometry is very much non-Euclidean. Approaching a BH is geometrically similar to moving eternally outwards to the "end" of the universe. Speaking about the inside of a BH is geometrically similar to speaking about space outside the universe, i.e., not meaningful.

There is a lot of physics contained in this excellent book - modern, cutting-edge theoretical physics, that is. In 24 chapters and almost 450 pages, the author guides the reader through a maze of seemingly contradictory scientific arguments in order to resolve an important issue in the physics of black holes: whether information is forever lost to the universe after it has passed through a black hole's horizon. In essence, this involves a type of reconciliation between General Relativity and Quantum Mechanics. Although this involves very abstract and difficult-to-grasp concepts, the author, one of the main adversaries in this so-called black hole war, gently guides the reader through the various issues, starting from first principles right up to the cutting-edge subject at hand. The book is amply illustrated with many diagrams, drawings, figures and pictures in order to help further clarify the already-lucid descriptions that are given in the text. But, in addition to all the technical issues, the author has included much of the human element in this war. Interpersonal matters, many personal anecdotes, people's backgrounds and even the odd joke all contribute towards illustrating that the main theme of this book is a truly human endeavor: to understand a bit more about our universe. The writing style is clear, authoritative, friendly, even chatty and very engaging; the 450 pages fly by amazingly quickly. Although science buffs are likely to be those who will enjoy this book the most, the writing style is such that its contents are easily accessible to a much broader readership.

On the whole good, but lacks clarity in parts. It tends to go from A to C without explaining what happened to B.

This insider's account of the theoretical battles between Stephen Hawking, the author and Gerald t'Hooft over the true nature of black holes, THE BLACK HOLE WAR, is a rare, fascinating examination of how scientists interact, how theories are created and challenged, and how the reputations of three of the world's greatest scientists - as well as the nature of physics itself - were affected by black hole research. THE BLACK HOLE WAR details the battle as much as the science, making it a 'must' for not only science collections strong in physics and history, but for the general public library.

Diane C. Donovan
California Bookwatch

If you are a fan of Black Hole theory, you have to read this book. There is enough intrigue here to keep you turning the pages, and the physics primer on Black Holes, Quantum Mechanics and Relativity is very approachable.

This is not an in-depth book on the physics of Black Holes - on the contrary, this is an enjoyable read for those who appreciate the topic and respect the brilliance of Leonard Susskind. This book tells the story that few of us have heard (from any side) - and shows us the human side of theoretical physics.

I have had the pleasure of attending lectures at Stanford with Prof. Susskind for the past 4 yrs. now. While his wit and colorful commentary do come out in the book, you will only get a glimpse of why he has such a following amongst "quantum groupies" and academics alike.

I highly recommend this book.

This book demands some concentration by the layman, some acceptance of presumably factual statements without further discussion, and concerns a topic not at the height of curent concerns. On the other hand, it does allow sifnificant insight into the various modes of thinking about major issues in cosmology and, in particular, the role of gravity-normally a very weak force-in keeping us all together.

WELL WRITEN CHRONICLE OF A FAIRLY ARCANE SUBJECT. INTENDED FOR READERS WITH AN INEREST IN QUANTUM MECHAMICS, COSMOLOGY AND PHYICS IN GENERAL.

This book tells the story of the "battle" between the author and Stephen Hawking regarding the latter claim that information is irretrievably lost in black holes.
This story is the extraordinary account of the paradigm shift that has occurred in physics in the last 25 years. Moreover, the book reads like a novel thanks to the various analogies and the anecdotes concerning the lives and personalities of the physicists involved. In summary, a very recommendable book for someone who wants to keep abreast of the advances in quantum gravity and cosmology, although the author discusses also the basic concepts of quantum mechanics and relativity.
Very strange things seem to happen in the vicinity of black holes and, as Susskind says, this needs rewiring of our brains, as we had to do before for relativity and quantum mechanics. When someone approaches and finally crosses a black hole horizon we have a similar situation as the famous Schrödinger's cat paradox. For the astronaut crossing the horizon, nothing happens (if the black hole is big enough so that he does not still notice the effect of the tidal forces). For the observer outside he deducts that the astronaut is fried to death. Believe it or not, this is not a contradiction in physics because the two of them will never be able to compare notes. Susskind calls this paradox black hole complementarity. The holographic principle and Maldacena's duality (well explained in an article in Scientific American not too long ago) are also part of the resolution of the battle for which Hawking finally conceded defeat in 2007.
Chapter 23 hints to a new duality that could indirectly provide experimental evidence for String Theory. Strings and hadrons behave in similar ways and the Relativistic Heavy Ion Collider in Brookhaven is investigating the properties of the quark-gluon plasma which mirror, 20 orders of magnitude higher, the properties of fundamental strings. Quantum gravity in Anti de Sitter space would be similar to quantum chromodynamics. However, our universe is not an Anti de Sitter spacetime. In any case some light between the shadows is finally shining in quantum gravity.

Leonard Susskind has been added to my list of general science authors that I really enjoy. Because of this book, I'm actively seeking his other general science books. He joins my list, which include Michio Kaku and Lee Smolin.

Dr Susskind writing is clear and honest. His examples, especially when describing the simplified concepts of string theory are easy to understand due to his gifted narrative ability and clear examples. The chapters where he explains the scientific concepts make this book worth every bit of the book price. His narrative style is also honest enough to explain where he is coming from even if he disagrees with the idea or belief, unlike some other books like Stuart Kaufmann's Reinventing the Sacred, which appear a little less honest and much less straightforward.

The humor he displays is very special. His story about how many ways to wear a jogging t-shirt is one I have now used repeatedly with friends, coworkers and family to the amusement of all (geek/nerd humor at its best).

The story of his and others' disagreement with Stephen Hawkings concept of information loss in a black hole is intriguing in the sense it is interesting to view the politics and dynamics of an academic world where few mere mortals can understand some of the elaborate concepts and theories, no matter what re-wiring is done. The author admits even some of the advanced "masters" of the subject fail to understand the full implications of the paradigms.

The most important paragraph in this book is on page 422:

"Sceptics will point out that everything I have told you about the quantum properties of black holes -- from entropy, temperature, and Hawking radiation to Black Hole Complementarity and the Holographic Principle -- is pure theory, with not an ounces of experimental data to confirm it. Unfortunately they may be right for a very long time."

Susskind obviously believes that he, with help from others, has discovered important radical new physics in Black Hole Complementarity and the Holographic Principle. They are certainly radical new ideas, but of course they do not qualify as physics in the absence of experimental verification. Stephen Hawking's ultimate agreement with Susskind is no substitute for experiments.

The tale of this theoretical dispute is fascinating and a good read until the topic turns to string theory. From that point on I found it too vague and speculative to hold my interest. The book is worth reading to get one perspective on how theoretical physics is done today and I would say what is wrong with it. Without experimental guidance you cannot create new science.

Some arguments can be presented to the general public and some only to the specialist. In this books, in my opinion, there is confusion about the two issues. Hawking was capable of breaking down complex arguments and present them even to children, but Susskind, a great scientist, do not possess such gift. He talks about very trivial matters for a few pages and then he plunges into complex particle physic.
The war about which he speaks in the title, apparently was just a diffent view on a single (important) detail.

Some arguments can be presented to the general public and some only to the specialist. In this books, in my opinion, there is confusion about the two issues. Hawking was capable of breaking down complex arguments and present them even to children, but Susskind, a great scientist, do not possess such gift. He talks about very trivial matters for a few pages and then he plunges into complex particle physic.
The war about which he speaks in the title, apparently was just a diffent view on a single (important) detail.

Quantum theory seems to work mathematically, but verbal descriptions have left most of us scratching our heads at the paradoxes. Suskind has excellent analogies and descriptions that minimize (though can't elemeninate) some of these problems. His knack for using one- and two-dimensional worlds to describe the "real" world are especially enlightening and understandable.

Susskind's book is a lot of fun. It's short on physics (which is a good thing for the layman) but long on personalities. It does include a lot of name dropping and some ingratiating attempts to include Susskind with the recent big boys of physics -- Feynmann, 't Hooft and Hawking -- but he does belong there as an original maverick (who was generally right). His amusing, laconic style, with irreverent detours, is engaging and pretty good for a physicist.

But the best part of the book is its description of the personalities involved and, untittingly, most revealing of Susskind's himself. The last chapter, entitled "Humility," is a gentle and wry criticism of the great Stephen Hawking, who was behind the curve and tried to claim it was he who figured out the conservation paradox of his own black hole writings. When, of course, it wasn't.

The most surprising thing about all of these reviews is that I haven't seen the one by Harriet Klausner yet. Where is she when you really need her?

This is a good book and the author does a great job of explaining the black hole information paradox. He also does a v.g. job of describing the personalities of those involved. The discussion of thought experiments in theoretical physics is also outstanding. What mars the book is the fact that the author is guilty of so many of the quirks that he often points out in his adversaries. It is amusing to see a lesser light take digs at such brilliant men as Hawking, Dyson and Penrose - clearly the author has more than a normal dose of chutzpah.
In light of all the recent attacks on string theory I think he must find it redeeming to be on the offensive....
Still, he does present some very salient arguments and even if you disagree with any of his conclusions it is a thought-provoking read - and I do want to believe that this was his chief motive in writing the book.

If you want a clear explanation of the basics of quantum mechanics and string theory, read this book. In addition to learning more than you ever thought possible about the physics of black holes, author Leonard Susskind provides clear definitions of the seemingly craziest new developments in theoretical physics, such as The Holographic Principle, Black Hole Complimentarity, and anti-de Sitter Space.

If you're interested in theoretical physics, you can't go wrong with this book.

Susskind mainly does well here. He takes the time to give a pretty good qualitative grounding in a number of important concepts. His extended discussion of entropy is particularly well done and does provide a good foundation for understanding the black hole information destruction question. However, he cannot resist making the political statement here and there and, while his physics may be sophisticated, those statements quickly indicate that his politics isn't.

His statements around global warming in particular reflect a willingness to accept assertions without any scientific rigor behind them. This reflects something that is a paradox with a lot of these popular physics books, particularly when they are written by members of the academy: it is often difficult to distinguish between the real scholarship, on the one hand, and the prevailing academic herd orthodoxy, on the other, in which many assertions are simply accepted without the requirement of evidence, much less proof.

This is a phenomenon that Lee Smolin discusses perceptively in his very good "The Problem with Physics."

Other issues include the writing, which is at best pedestrian (don't expect the literary gifts of a Brian Greene) and the insistent name dropping, apparently intended to remind the reader of his membership in the pantheon with Feynman and Hawking. Susskind's dismissive attitude towards religious scholarship (including a particularly insulting (and utterly gratuitous) passage regarding Talmudic scholars) is also troubling.


However, these is relatively minor annoyances if you're there for the physics. This book is still reasonably useful and is worth the time to read.

Susskind describes the decades-long battle between the quantum mechanics community and the general relativists as to whether information is lost when objects pass through the event horizon of a black hole and the hole eventually evaporates. According to Prof. Hawking and the GR community, as nothing can ever reappear from inside an event horizon, the information is indeed totally lost.

Susskind and Gerard 't Hooft begged to differ. Loss of information would violate the basic time-reversibility of QM: Hawking's ideas would lead to universe-destroying phenomena (p. 23). Somehow, the information locked the wrong side of the event horizon must leak out via Hawking radiation. But how?

The resolution of this dilemma took many years of conjectures and refutations. Susskind takes us on a tour of entropy, holographic principles and physics at the Planck scale. And the adversarial plot keeps the reader turning the pages.

I am normally very dubious about popularisations. They proceed by raking up endless analogies which never quite fit together, so that by the end of the book, your mind is like that jig-saw puzzle you bought and could never fit together.

This book was never going to be the exception - the mathematics of quantum field theory, general relativity and string theory are just too arcane for popular culture concepts to cohere around. However, there are wonderful insights all the way through this book and we do end up learning something about the large scale map of the territory. Apparently even the experts find it hard to get the whole thing into one focus.

This is absolutely the greatest example of what popular science book about theoretical physics/cosmology should be !! Writing is so brilliant, witty, straightforward, direct and succinct, that regardless of education level, anybody can enjoy interesting content (history of science as well as author's personal story) of "The Black Hole War". Author uses analogies in the best possible way, comparable only to Brian Greene and Michio Kaku. Drawings are frequent, well selected, informative and easy to understand. He writes: "The real tools for understanding the quantum universe are abstract mathematics: infinite dimensional Hilbert spaces, projection operators, unitary matrices and a lot of other advanced principles that take a few years to learn. But let's see how we do in just a few pages". AND HE DELIVERES !! While this book could be a starter for anybody, I recommend it to all who know Kip Thorne's famous work. For reason unknown to me, important black hole "war" is not mentioned in "Black Holes & Time Warps" at all. Professor Susskind created a true masterpiece where he even accepts coexistence of science and faith by writing: "The British intellectual world seems to be big enough for both Dawkins and Polkinghorne". Nothing but big applaud for the author and his effort !!

This is absolutely the greatest example of what popular science book should be !! Writing is so brilliant, witty, straightforward, direct and succinct, that regardless of education, anybody can enjoy interesting content of "The Black Hole War". Author uses analogies in the best possible way, comparable only to Brian Greene and Michio Kaku. He writes: "The real tools for understanding the quantum universe are abstract mathematics: infinite dimensional Hilbert spaces, projection operators, unitary matrices and a lot of other advanced principles that take a few years to learn. But let's see how we do in just a few pages". AND HE DELIVERES !! This book should be read by all who know Kip Thorne's famous work. For reason unknown to me, important black hole "war" is not mentioned in "Black Holes & Time Warps" at all. Professor Susskind created a true pearl where he even accepts coexistence of science and faith by writing: "The British intellectual world seems to be big enough for both Dawkins and Polkinghorne". Nothing but big apploud for the author and his effort !!

Leonard Susskind is not only a co-father of string theory, the holographic principle, and many other key concepts of physics but also one of the most original physicists of our era.

He's been fighting against some superficially plausible but fundamentally wrong ideas for decades. During this ferocious fight, he had to discover many fascinating things about quantum gravity.

The battle was about the preservation of the information by black holes. Using revolutionary but approximate results, Stephen Hawking has argued since the 1970s that the information is lost after a black hole evaporates. Leonard Susskind claimed that it was preserved: this preservation, also called unitarity, is one of the postulates of quantum mechanics and these postulates are and have to be completely universal.

Susskind was right. We know many reasons why it is so, including recent results in string theory, and many of them are explained in the book. We also know loopholes that show that Hawking's old qualitative arguments are not quite correct even though his numerical results are numerically almost accurate.

It took many years for Hawking to understand and admit that the information was preserved in the full theory and that physics makes sense. During those years, Susskind was a new "Ahab" waiting for Hawking's elusive concession. However, the book offers a lot of personal stories and emotions, too. Susskind talks about several well-known names of science such as Stephen Hawking, Gerard 't Hooft, Roger Penrose, and Richard Feynman. All of them, and others, have been players in this fascinating story.

Although Susskind is arguably the least known to the general public among these fives names, every real physicist would tell you that he is indisputably the most qualified person to explain how black holes actually work in this quantum world.

Because as an outspoken son of a plumber, he is also close to the middle and working class and an articulate peer of Brian Greene and other great and charismatic science communicators, everyone who is interested in black holes, gravity, and quantum mechanics should read this book.

The physics book market was recently flooded by a lot of trash written by crackpots similar to Peter Woit and Lee Smolin and it is time for the most intelligent readers to pull their heads out of the sand and see one of the great things that cutting-edge theoretical physics has actually achieved by 2008.

highly recommended. very interesting read, even for those not familiar with the underlying physics. suskind is a talent writer, able to make esoteric concepts accessible to the lay-reader. he is also one of the vanguards of later 20th century physics. there is an on-going, vigorous debate swirling around the dark corners of our universe. for anyone with an interest in that debate, this is a must read.