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

Product Details

• Amazon Sales Rank: #145507 in Books
• Published on: 2008-02-10
• Original language: English
• Number of items: 1
• Binding: Paperback
• 240 pages

Customer Reviews

The road back
Horses are for courses as books are for readers. I happen to be someone for whom this book is ideal. I was a research theoretical physicist in the early seventies when the standard theory was being developed. I then left to do other things before retiring recently.Thus, thankfully in some ways, given Smollin's comments both in this book and in "The Trouble With Physics", I missed the entire string theory period. Now I am trying to get some idea of what happened in physics between 1976 and now. Lee Smolin's book gives more of the detail than most accounts for non-specialists, enough for the non-specialist to get a good and flavoursome taste and enough to inspire someone like me to go off afterwards and dip into the references he provides. For me and others in my position, this book is perhaps part of the road back.

An Introduction to Loop Quantum Gravity
Since the postulation of theory of relativity (theory of cosmos, which describes the structure of space and time), and quantum mechanics (laws of microcosm, which describes atomic structure, nuclear forces, and nature of basic component of matter); physicists until now have struggled to explain gravity (which is a manifestation of spacetime fabric in presence of matter) in terms of quantum mechanics (quantum gravity). In this book the author attempts to explain three different approaches to quantum gravity; Loop Quantum Gravity (LQG), Superstring - M theory (S. -M), and Blackhole Thermodynamics (BT). While each takes a different starting point, they all agree when viewed on Planck scale, and they also view space and time are not continuous, and space is composed of discrete units. LQG gives us a detailed picture of these units in terms of spin networks, where as S.-M theory proposes continuous space in terms of a continuous string (with compactified extra dimensions) made of string bits, which is governed by uncertainty principle. BT theory states that amount information in any given space is finite and is proportional to the area of the boundary of the region in Planck units. The author is a pioneer in the field of LQG and provides the reader with a good introduction of the theory in a non-mathematical form and then compares with S.-M and BT theories. The book is described in three parts; the first part is a general introduction, which describes historical development of three theories, the second part introduces LQG and then compares with S.-M and BT theories, and the final part attempts to unify the three approaches into a single theory using Holographic Principle.

The author gives us several interesting accounts of physicists working in these fields are in a climate of mutual ignorance and complacency with the belief that their theory is correct and others are wrong. There are instances when one group can't solve certain problems, and they seek the help from the other camp. The author also briefly explains other theories such as Twister theory, and Non-Commutative Geometry. This is one of the few books I have read which describes LQG in some detail, although there are several books in literature, which describes S.-M theory. The author is very honest in comparing the three approaches to offer the best explanation for quantum gravity. Anyone who wants to understand LQG must have this book.