The Black Hole War

It's difficult do decide how I feel about Leonard Susskind's The Black Hole War. On the one hand, Susskind should be commended -- it's a pop cosmology book that does not read like a textbook (as someone who has read his share of physics textbooks, I certainly would know), and contains many cogent explanations of physics (mostly quantum mechanical) principles and problems for the layman. On the other hand, it's boring as hell.

This isn't to say that the subject Susskind covers is uninteresting -- far from it. It seems that since Carl Sagan popularized it, cosmology has exploded in popularity, and has kept up the pace even as interesting and original voices (such as Sagan's) pass into history. The particular subject of this work is black holes and information loss, which certainly doesn't sound bland. Unfortunately, much of the book is devoted to unfolding the problem and related issues in the slowest manner possible, along with repetition of the mantra "I knew Stephen [Hawking] had to be wrong, but I couldn't quite place my finger on why." Additionally, there's a lot about Susskind's personal life and experiences, which are exactly as scintillating as one would expect from a prominent theoretical physicist. (Ok, that's a bit of a cheap shot, but shouldn't digressions be either interesting or related to a semi-relevant topic? Susskind makes interacting with Richard Feynman and Stephen Hawking, two titans of physics, and interesting characters in their own right, seem like pulling teeth.)

One major redeeming factor of this work is the lack of emphasis on string theory. While Susskind does trot it out towards the end of the work, as a possible theory of everything, he doesn't dwell on it throughout as "the truth". (As an aside, he does offer at least one experiment to test string theory, which is refreshing; unfortunately, said experiment would involve a particle accelerator the size of the galaxy. Not quite as feasible as I would like) This isn't to completely dismiss string theory, as parts of it are falsifiable, but it's instructive to remember that models are typically wrong, but some are still useful. To that end, it's tedious to be lectured on the nuts-and-bolts of a difficult to falsify model, which Susskind manages to (mostly) avoid doing, until the later chapters.

Another major feature of the work that I can't decide is a positive or a negative is the amount of time Susskind will spend to illustrate a point. Descriptions of gravity, Schwarzschild radius, special relativity, quantum mechanics, and other physics concepts receive myriad examples and much explanation. I vacillate between thinking that this is a positive thing for those readers who are unfamiliar with such concepts, and that it's tedious for those of us who are familiar with them. While these are complex concepts that do require in depth explanation (I'm certainly not going to claim to understand quantum mechanics. Susskind does quote Feynman here: "I think I can safely say that nobody understands quantum mechanics."), it can be frustrating to have examples taken to an extreme, as Susskind does in initially explaining gravity.

The meat of the book is devoted to a debate between Susskind (among others) and Stephen Hawking (among others) -- what happens to the information in a black hole if the black hole evaporates? Is it lost forever, or does it return to the universe in the Hawking radiation? If it returns to the universe, how does it return from beyond the event horizon? Why is information loss important? (Because if the information is lost, that would violate the Second Law of Thermodynamics by reducing the overall entropy in the universe. This is a Very Bad Thing (tm). Additionally, quantum mechanics and relativity predict very different things happen as objects approach and pass a black hole's horizon. Invalidating either one would deal a major blow to the state of physics. These are all very interesting questions, and while Susskind does a (relatively) good job answering them, what prevents this book being better than it is is that he has to explain so many concepts to get to the heart of the conflict, and this, combined with much digression, is enough to make the book meander.

A final point The Black Hole War's favor is that it's very thorough -- at no point in the book did I feel that a concept was underexplained. It's not a dense book -- it's light on math, and although the concepts can be difficult, especially for the uninitiated (Schrodinger's cat is thankfully not mentioned. As an aside, here is the front and back cover of the textbook I used for Quantum Mechanics), Susskind does provide many (perhaps too many) examples. Overall, probably one to avoid, unless one is very passionate about information theory, cosmology, or a huge fan of Leonard Susskind.