Product Description

From one of the World's most distinguished scientsits, an elegant and concise presentation of the controversial ideas behind quantum gravity.

The Holy Grail of modern physics is the search for a theory of "quantum gravity." It is a search for a view 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, cosmologist and science writer Lee Smolin provides the first concise and accessible overview of current attempts to reconcile these two theories in a final "theory of everything." Other books and articles have painted an incomplete picture by exposing only one of the different approaches, including string theory and loop quantum gravity. Here 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.

Amazon.com Review

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