The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory

The book has the merit of being one of the first books to explore and to try to explain superstring theory to the layman. In this regard it is a fair try. Otherwise, 1/3 of the book is wasted trying to explain what special relativity, general relativity and quantum mechanics are all about, and here the author is only mediocre in his enterprise. Anyone who has already read popular level books on these subjects, like the classics by Gamow or Feynman or Joseph Silk or Weinberg, will feel uncomfortable. The analogies the author uses are also terrible, almost nonsense, like when he compares the input of parameters in the Standard Model with the input of the value of an initial investment in the stock market. Geeez... Finaly, I do not like Greene's writing style: the reading simply does not flow. Compared to, e.g., Alan Guth on the equally aethereal subject of inflationary universe, Greene's writing style sucks. Weeeeell..., at least Guth is talking about something that bears a possible connection with reality!

This is a very good book for learning about superstring theory. I was motivated to read this book after seeing the associated NOVA documentary (a documentary which I actually thought was extremely repetitive and somewhat cheesy, though the presented ideas and interviews with various physicists were quite interesting). Greene is obviously a very talented science writer and manages to present a highly technical subject in a way that is intelligible to the non-physicist. In addition to string theory, this book provides some very clear introductions to special relativity, general relativity and quantum mechanics.

While the theories presented in this book are exciting from the standpoint of their potential to unify quantum mechanics and general relativity, it would be nice if the superstring theorists could eventually find an empirical backing for the results stemming from their "elegant" equations. It is not that the elegant-math argument is without merit but it would be more convincing if the theory could make some predictions that were actually falsifiable. Arguments stating that the extra dimensions are extremely tiny since we would have otherwise noticed them or that superpartners are extremely massive since we would have otherwise noticed them, etc., are not entirely convincing for me in the absence of empirical evidence. (As an aside, string theory is, apparently, not without its critics in the physics community judging from some of the new books being published such as Woit's Not Even Wrong: The Failure of String Theory And the Search for Unity in Physical Law and Smolin's The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next.)

Greene does concede the need for falsifiable predictions and he seems forthright in pointing out issues that string theorists still need to address. Perhaps Greene is right in stating that this lack of falsifiable predictions is simply a consequence of the theoretical physicists outpacing the experimental physicists; perhaps superstring theory will eventually obtain the empirical evidence necessary to appease the skeptics. Whatever the ultimate fate of string theory/M-theory, I found this book to be both enjoyable and informative and I would definitely recommend it for those who are interested in superstring theory.

I started reading this book this week and had a hard time accepting Einstein's Theory of General Relativity. It almost sounds as if he accepts as truth the optical and mechanical illusions of motion, either by a shortening of matter along its axis of motion or a delay in clock time by a pull of gravity on its mechanics. It almost seems that space and time, under the theory of general relativity, can be mathematically manipulated to save his theory that light travels at a constant velocity. Of course, light does not travel at a constant velocity. This was proven in experiments documented in Petr Beckmann's book "Einstein Plus Two" which held that in order for light to travel in waves, it must have a medium upon which to oscillate. That medium can either speed up or slow down the velocity of light depending upon its local gravitation field. For example, light traveling from Washington D.C. to Los Angeles travels faster than light traveling from Los Angeles to Washington D.C. This demonstrates that what actually happens in the experiment observed may be different than the optical illusion being observed. Einstein simply didn't have the necessary tools to overcome the limits of observation relative to his day.

I had seen this book before in a bookstore years ago, but I did not buy it. Big mistake. Greene explains the workings of the universe in down to earth terms (no small feat). Expand your brain a Large notch, if you are not scientifically inclined, as to the modern ideas circulating over the all important Superstring theory - without being a mathematician or physicist!

I think that this book should be reviewed on two levels: how good is the book and how relevant is the subject matter. Let me first address the book on its own merits, irrespective of ones view of string theory.

This book is very well written. It is about physics on the Planck scale (10^-43 seconds and 10^-35 meters), where quantum mechanics and general relativity conflict with one another. String theory was developed to overcome this conflict and in my opinion this book does a very good job of describing what string theory is and why it is needed. It is very clearly written (as clear as possible given a horribly complex subject). Absolutely no mathematics is used; there is nary an x, y, z, c or h in the text. Thus, even the most math-phobic should be able to read this book. Very complex ideas are conveyed through simple analogies, although in a very simplified and superficial manner. The background sections on quantum mechanics and relativity are, however, very superficial and are only included to the extent that some background is required for the more extensive discussion of string theory. This is therefore not the book for someone that wants a review of quantum mechanics or relativity theory, but it is if you want a review of string theory. I particularly liked the first 60% of the book, which was devoted to the quantum mechanics, relativity and the basics of string theory. The last 40%, which is more focused on the author's work on string theory was much harder to follow and caused me to reduce what was until then point a 5 star book to four stars. The more the discussion shifted to Calabi-Yau shapes the more difficult it was to follow and the more it raised questions in my mind about the relevance of string theory. Is it physics or just an exercise in advanced topology? I sometimes got the feeling that I was reading a treatment of how advanced topology can be used to calculate the number of angels that can dance on the head of a pin.

This is a very good book if you want to learn more about string theory, even perhaps more that you care to know. The question is why should you care to know anything about this subject? Most physicists have grave reservations regarding the relevance of string theory and allied subjects such as quantum gravity. As the author freely admits, string theory has made no experimentally verified predictions of new phenomena, nor has even the smallest part of it been experimentally verified. To make matters worse, there are an infinite number of possible string shapes and vibrations, many of which seem to predict our universe, but there is no way to know which if any is the correct one. Many others predict new particles, which have never been observed, but may exist beyond our experimental capabilities to observe them. Unfortunately, this experimental limitation is not one that is likely to be overcome, since it may require a particle accelerator the size of the whole universe. Nor is the mathematics of string theory very tractable, as some calculations would require the fastest computers over 100 years to run. Advances in computing power may solve these problems, but the only time that enough energy was present to test many of the aspects of string theory was at the instant of the creation of the universe. Nonetheless, Greene makes a strong case for why he and many of the world's best physicists are devoting their careers to string theory. My opinion is that the subject was sufficiently interesting and important to warrant the time that I spent on this book, but it may ultimately be a field that will end up in the dustbin of history. Only time will tell. Perhaps we will know more in a decade or so and then one will be able to read a book about a more definitive approach to physics on the Planck scale. For now, if you want to know about string theory as of 1999, this is about as good a book as there is.