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Three Roads to Quantum Gravity

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  • Anonymous

    Posted February 15, 2006

    The worst thing about this book is the title!

    I have two major qualms with this book. First off, for a popular physics book, the author does a terrible job explaining anything, although this was refreshing after sitting through Brian Greene or Michio Kaku. For somebody who is not versed in mathematics or physics beyound the 18th century (i.e. beyond calculus or classical mechanics) much of the prose might go over their head. For somebody fluent in Riemannian geometry, topology, the theory of relativity, quantum mechanics, particle field theory, and other such studies, the book is not technical enough. Here is my main problem however. The book is called 'Three Roads to Quantum Gravity'. First, it should be noted that there are certainly more than 3 approaches to quantum gravity and the theory of everything, some are a bit out there, so I assume he meant the 3 main paths. Funny, I thought that the three major approaches are M-Theory (and other stringy hypotheses) [particle physics approach], loop quantum gravity, and canonical quantum gravity [general relativity approach]. According to Smolin, whose list is similar, the paths are: 1. Quantum Mechanics approach: String theories such as M-Theory, Bosonic String Theory, 11-D Super Symmetry. 2. General Relativity approach: Loop Quantum Gravity 3. Post-quantum, post-relativity approach taken by some philosophers. I guess we both agree that LQG is a GR approach (top down) as opposed to string theories (QM approach, bottom up). But is canonical QG a GR approach. I thought it was, but Smolin would probably call it an obscure example of the third path. Anyways, as anybody familiar with Lee Smolin's work knows, Smolin favors the loop quantum gravity approach to grand unification. As such, I expected the author to have a bias favoring LQG. Problem was, he did not make mention of the three roads outside the introduction (though the book's title suggests otherwise). LQG was the ONLY thing he mentioned, except for the occasional forray into string theory. Lee's coverage certainly was not fair and balanced (even less so than FOX News). The book was written as a series of philosophical chapters purporting to answer questions, but instead parroting old assumptions and pre-conceived notions about reality from older theories even though quantum gravity might give different answers. Unlike a more loyal LQG theorist (such as Carlo Rovelli), Smolin accepts that LQG and string theories need not be incompatible and said that the two should merge. Unfortunately, Smolin did not extend his acceptance to other approaches to quantum gravity. Therefore, a more apt title should be 'Two Intertwined Roads to Quantum Gravity Which May in Fact be the Same Path' or 'Loop Quantum Gravity is da Best, but Stringy Theories are Cool Too' or even 'I am the Wise Lee Smolin! Trust in my Ability to Forsee the Future of Physics and Answer all Questions Ye Mortals'.

    2 out of 2 people found this review helpful.

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