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| View Larger Image | Three Roads to Quantum Gravity
by Lee Smolin
| | List Price: | $14.95 | | Price: | $10.17 | | You Save: | $4.78 (32%) |  | | Available: | Usually ships in 24 hours | | | | | Sales Rank: | 195055 | | Studio: | Basic Books | | | Binding: | Paperback | | Number Of Pages: | 240 | | Publication Date: | August 15, 2002 | | Publisher: | Basic Books |
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EDITORIAL REVIEWS |
Product Description
The Holy Grail of modern physics is a theory of the universe that unites two seemingly opposing pillars of modern science: Einstein's theory of general relativity, which deals with large-scale phenomena (planets, solar systems and galaxies), and quantum theory, which deals with the world of the very small (molecules, atoms, electrons). In Three Roads to Quantum Gravity, Lee Smolin provides the first concise and accessible overview of current attempts to reconcile these two theories in a final "theory of everything." This is the closest anyone has ever come to devising a completely new theory of space, time and the universe to replace the Newtonian ideas that were the foundation of all science until the beginning of the twentieth century. Lee Smolin, who has spent his career at the forefront of these new discoveries, presents for the first time the main ideas behind the new developments that have brought a quantum theory of gravity in sight. He explains in simple terms what scientists are talking about when they say the world is made from exotic entities such as loops, strings, and black holes. As he does so, he tells the fascinating stories behind these discoveries: the rivalries, epiphanies, and intrigues he witnessed firsthand.Science Masters Series |
Amazon.com
It's difficult, writes Lee Smolin in this lucid overview of modern physics, to talk meaningfully about the big questions of space and time, given the limitations of our technology and perceptions. It's more difficult still given some of the contradictions and inconsistencies that obtain between quantum theory, which "was invented to explain why atoms are stable and do not instantly fall apart" but has little to say about space and time, and general relatively theory, which has everything to say about the big picture but tends to collapse when describing the behavior of atoms and their even smaller constituents. Whence the hero of Smolin's tale, the as-yet-incomplete quantum theory of gravity, which seeks to unify relativity and quantum theory--and, in the bargain, to move toward a "grand theory of everything." Smolin ably explains concepts that underlie quantum gravity, such as background independence, the superposition principle, and the notion of causal structure, and he traces the development of allied theories that have shaped modern physics and led to this new view of the universe. Although he allows that "it has not been possible to test any of our new theories of quantum gravity experimentally," Smolin predicts that a solid framework will be established by 2015 at the outside. If he's correct, the years in between promise to be an exciting time for students of the physical sciences, and Smolin's book makes an engaging introduction to some of the big questions they'll be asking. --Gregory McNamee |
CUSTOMER REVIEWS (Average Customer Rating: 4.0 based on 48 reviews)
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Poorly Written 
This book addresses some extremely interesting topics, including string theory, quantum loop gravity, and halographic models of the universe. Unfortunately, it does not do so successfully. The author merely glosses over these topics and many deep subtopics as the disorganization of them and muddled writing ruin what otherwise might have been an interesting exercise in the comparison and contrast of approaches to developing a model of quantum gravity. The writing is so poor that I often gave up reading this book in frustration, only to return to it due to the interest in the subject matter, however ill-rendered. I recommend seeking a better treatment or treatments of the subject matter.
July 20, 2008 | |
I wish I had read the less than positive reviews more closely. 
For me, the most useful reviews are those that tell me something about the book, along with some of the reviewers' opinions. I hope that the reader finds this one to be in that category. Some of the reviews of this book were less than completely positive and so is this present one. I wish that I had paid more attention to those reviews. If I had, I might never have invested the time that I did on this book. For the reasons listed below, I am forced to give this book a strongly qualified, only slightly positive, review.
First a little about the book and its good features:
1. Quantum gravity is the merger of general relativity and quantum mechanics. It is being applied to describe nature at the smallest of size scales, the behavior of black holes and the origin of the universe.
2. More than gravity per se, this book is about the quantum nature of space and time. It addresses the question as to whether space and time are continuous and can be divided into infinitely smaller pieces, or whether they are discreet, with minimum possible sizes (the Planck distance and Planck time). The book supports this discreet view of space and time.
3. The quantum of space is discussed in terms of quantum loops and atomic structure is described in terms of the spin networks, developed by Roger Penrose, that are made up of these quantum loops.
4. This book discusses the entropy of black holes and how this relates to quantum gravity.
5. There is a brief explanation of what string theory is about and how it relates to quantum gravity. It is postulated that these strings may themselves be made from spin networks.
6. There is a brief section of supersymmetry and its impact on string theory and quantum gravity.
7. There is a brief chapter discussing theological implications of this work.
8. This book focuses on the questions raised by modern physics. If you read it you will definitely get an idea about these questions and about quantum gravity, string theory and the entropy of black holes. These are all good reasons to read this book, but before you invest the time and effort to do so you should consider the reservations listed below.
Now why the above features were not enough for me to give this book 5 stars:
1) You definitely need some physics background to get much from this book. You need to know about entropy, quantum mechanics, nuclear physics and general relativity. This is not good a book for high school students or those who have no background in the required prerequisites. This would be a good book for people in the field, for interested scientists and for laymen who are well read in the required prerequisites. To be fair, the author does mention the need for some previous knowledge, but this is not stated on the book cover or where it might warn prospective readers. I therefore feel the need to do so here.
2) There is no attempt to define some of the important things being discussed. For instance, conical figures depicting photons in space-time are shown with little or no discussion. World lines are shown in one figure, but not defined. (Under W in the index are Warhol, Andy and Wittgenstein, Ludwig, but no world line.)
3) The features mentioned above are given in only general terms. Without more specificity and more background information the text is rather murky in places. After about 50 pages I was ready to stop and go on to other things, but I decided to read a bit further. Fortunately, I enjoyed some of the subsequent chapters a bit more and finished the book. No math is included, which is probably a very good thing since the math is daunting even for theoretical physicists.
4) There is a lot of personal anecdotal information in this book, which in my opinion only adds to its length, but does not provide any insights into the physics being discussed. According to the author (see item #9 below) this was included to show "science in the making", but I personally do see how this is done by recounting how the author had two flat tires while driving a colleague to the airport, or that he was rear ended by a Maserati. This information may great for those who know the author, but I felt that it just slowed down the flow of the text. I would have preferred replacing this anecdotal information with a better discussion of quantum gravity. Most of the book is about quantum loops and in my opinion there is insufficient discussion of how this relates to gravity, quantum or otherwise.
5) One of my main concerns is that at present there is no way to experimentally determine the validity of any of the theories presented in the book and much of what is being presented will likely be shown to be wrong. Without experimental verification, physics tends to degenerate into metaphysics. While it is a somewhat invidious comparison, at times reading this book reminded me of the medieval preoccupation with trying to count the number of angels that could dance on the head of a pin.
6) To use the author's own analogy, this book is like reading about the work of Galileo and Kepler, without the unifying principles developed by Newton. Perhaps, one should wait until someone makes sense of all of this and then spend the time to read a book that discusses this synthesis. (See #9, below, for Smolin's reason for publishing this book before all the evidence was in.)
7) Quantum gravity is clearly in competition with string theory for graduate students and funding dollars, and Smolin clearly favors QG. He feels that it is more fundamental than String Theory since he views strings as perhaps ultimately being made from spin networks of quantum loops. I would have liked to have seen more of the String Theory side of this debate. Compared to String Theory, QG is a minority view of physics on the smallest size and time scales. I am sure that there are many string theorists who could have contributed some balance to Smolin's views. As it stands, the picture that is presented is very one sided. (I am not a String Theorist or even a physicist, just a retired scientist from another field who has the time to write lengthy reviews.)
8) In the epilogue, Smolin predicts, "We shall have the basic framework of the quantum theory of gravity by 2010, 2015 at the outside.". This view is supported by the postscript to the 2001 paperback edition, in which Smolin cites recent experimental work that may provide the experimental evidence to validate one or more of the theories that he presents. All the more reason, in my opinion, to wait as little as 3 years (8 years at the outside) until some of the theories have been winnowed down by experimental evidence and Smolin can write a new book, or update this one, that gives a more definitive view of quantum gravity.
9) At the very end of the book, Smolin questions the wisdom of presenting science "in the making" to a general audience, but decided that it was best for the public to see how science goes about seeking the truth. I have no trouble with this, so long as this is clearly stated on the book cover and in the literature provided by the publisher. I for one would have preferred to wait until all this was sorted out before I expended the energy required to follow the discussion.
In summary, this book is OK if you want to know about some of the important questions being raised in modern physics and if you want to get a glimpse of science "in the making", but this book (and the science being described) is short on verified answers. (Not that anyone else has them to give.)
November 06, 2007 | |
Quantum Gravity Review 
Lee Smolin has again created an excellent non-mathematical book that has his distinctive style and clearly that explains his view point on how we get to a theory of everything. Lee presents a partial history of the different approaches used by the Physics community to solve solve the problems of creating a theory of everything. His approach is heavly vested in the Quantun Gravity history and development. This is only natural in that his life has been spent primarly in this area of development. However, he does a very adaquite job of explaining the history and issues with string theory. Lee does a excellent job in this book to present a possible direction for the science community to persue. I only hope that our science community will take Lee's approaces seriously.
September 24, 2007 | |
" The Diggidy Dog of Physics Books"
Wow, I'm not going to go into any details or dicussions about this book, or any other matter, but i have to say this. This book is beyond GOOD, it will rock your mind so hard that you will be hooked on Physics for the rest of your life. Lee Smolin is the Man.
June 30, 2007 | |
A theory of quantum gravity by 2015!
Lee Smolin's promise of a full theory of quantum gravity by 2015 concludes this book.
Along the way to that conclusion Smolin takes the reader on a comprehensible and lucid tour the current state of the search for a unified theory of quantum gravity. In this way, Smolin introduces the reader to his "three roads to quantum gravity" being:
1) The road from relativity or those classical principles originally established by Albert Einstein in his general theory of relativity back in 1916;
2) The road from quantum mechanics or that standard model developed within twenty years of Einstein's relativity dealing with the forces that operate at the subatomic level and finally;
3) The road from both and the various ways in which researchers from both areas have tried to the meld the two approaches.
Though admittedly (and particularly at the time this book was written) the theory favored by most theorists is so called string theory, Smolin also discusses other contenders like loop gravity (which Smolin worked with) as well as Oxford's Roger Penrose's twistor theory and others.
Long story short, the three roads are still being travelled. However, Smolin's salutory comments about a solution being in the offing by 2015 are optimistic.
Hopefully, they're also right!
Good book, good background, highly recommended.
June 24, 2007 | |
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