Three Roads to Quantum Gravity

Not that easy but worth the effort. His other books are also good. Don't worry if you don't understand it all, no one else does either! Not that this is anything bad about him, there are two kinds of Gravity, General Relativity and Quantum Gravity. When we understand how they fit together we will know a lot more about the nature of the universe!

Smolin's presentation of the three theories was so thought provoking for me that I realized that I wanted to learn more. I had majored in Physics 35 years ago so I had QM and SR under my belt but nothing more modern. One thing that I particualry liked about Smolin's presentation of the three theories currently being worked on - superstring theory, quantum loop theory and blackhole thermodynamics - was the balanced way he kept saying how all three undoubtedly would contribute to the ongoing progress rather than trying to say one has to be right to the exclusion of the other two - it's simply too early to tell. I've spent 2 years (with a tutor) studying QFT in order, hopefully, to be able to at least approach the mathematics behind these theories. I've just ordered a "First Course in String Theory" and realized that I had never written a review of Smolen's book to so-to-speak thank him so I now fill that gap.

Reviewers more familiar with Quantum Gravity may find the book 'idiosyncratic' or 'subjective'. But I'm thankful for its articulation of concepts so profound as to elude conventional language. And this is Smolin's intent: not to be thorough (the book is 1 inch thick) but to give the layperson with little or no vocabulary, a chance to resonate with ideas whose very contemplation--let alone solution--has challenged thinkers from Aristotle to Witten (ok, Zeno). He's expert in this deep-under-deep subject. Equally important in a book aimed at the general audience, he posesses Wigner's "unreasonable effectiveness" in using English to explicate the interface between new mathematics and new physics. And does it gracefully within the multitasked, competitive environment which scientists now inhabit.The concepts discussed stretch beyond Feynman's use of 'weird' . Though many are now aware of the ubiquity of Black Holes, it still comes as a surprise to learn that---in the few years since Hawking's seminal contributions---theorists have significantly extended Hawking. Black Holes now can be addressed with quantum theory to yield a principle called the Beckenstein bound. And that allows them to formulate a quantum physics of information (or an informational underpinning to physics---Wheeler's "It to Bit"), thus closing in on a complete theory which reconciles relativity and quantum theory Smolin has the gift of making the reader feel he's understanding these ideas. [Does the reader 'understand' in any meaningful sense? That's a subject for philosophers to debate]. He succinctly describes his own loop theory in comparison to 'conventional' string theories and their successor M-theory (as Brian Greene did more extensively in his book The Elegant Universe). He feels these contenders for the Ultimate are looking at the same elephant; and presents the competition's ideas with (well, almost) the conviction he has for his own. In so doing, he bridges both an explanatory and sociologic gap . And he does so with welcome doses of speculation and humility. This original thinker deserves better reviews than those preceding mine; I'd suggest these folks levy their criticism in a speciality journal.

Three Roads To Quantum Gravity by Lee Smolin isn't the easiest highway to travel in the universe, but will be rewarding to anyone taking the journey. Smolin, currently a professor at Penn State [my alma mater :)], writes simply, but smartly about the biggest piece of unfinished physics business leftover from the 20th Century, the resolution of the conflicts between our theory of the large, general relativity, and our theory of the small, quantum mechanics. Smolin assumes an interested and educated reader and simplifies our trip by not doing long introductions to relativity and quantum mechanics. After introducing the idea of a theory of quantum gravity, Smolin spends the rest of the book laying out the 'three roads' of the title, spending slightly more time on loop quantum gravity, the 'road' he's spent the most time on. Although not as elegantly written or as detailed as Brian Greene's The Elegant Universe, Three Roads To Quantum Gravity compliments that earlier book by coming at 'theory of everything' territory from a different direction. Since there is no AAA for physics, layfolks like myself should be glad that we have guides like Lee Smolin to direct us through the hidden regions of our universe.

I am very impressed with this book. This is going to be one of the seminal science book for lay persons, right up there with Stephen Hawking's "A Brief History of Time".Lee Smolin is an active researcher in Loop Quantum Gravity. He laid out in a clear manner the research progress of Quantum Gravity. Quantum Gravity, once completed, should able to reveal the basic fabric of our universe, and say a lot about what is the stuff that space and time are made of. There are no mind boggling math in the book, but there are lots of mind boggling ideas that once Smolin explains them, I am left with a sense indeed this must be how our universe works.Smolin thinks understanding how Black Hole works is key to progress in Quantum Gravity. He gives a modern update of what we know about Black Holes, siting a few fresh research results. This is very valuable, because the typical Black Hole books for the lay person are very dated indeed. A modern treatment is exactly what we need.This book is a must for the fans following the going-ons in the newsgroup sci.physics.research.