Saturday, January 27, 2007

Book Review - The Fabric of The Cosmos

The second book I've completed in the past month is Brian Greene's The Fabric of the Cosmos.

Brian Greene is a physicist whose specialty is "string theory" or "superstring theory". Greene's earlier work The Elegant Universe focuses on these new theories of the basic nature of matter. The Fabric of the Cosmos describes the evolution of scientific thinking about the nature of the universe itself - specifically whether space (or spacetime to be more precise) exists independently of matter and energy, or whether it is a simply a 'human abstraction' for the vacuum in which matter/energy exist.

As Greene recounts, this question - which skirts the boundary between science and philosophy - is not new. It concerned the greatest of scientists going back to Sir Isaac Newton. Of course, we don't have an absolute answer to the question. However, today's physics gives tantalizing clues. Greene's narrative stitches together the underlying accepted physics - quantum theory and general relativity - and superstring theory, a strong candidate for bridging the troubling gap between these.

I found this book excellent. Although it doesn't answer the question, it is an excellent summary of the state of the current science built around attempting to answer it. A good deal of the book discusses cosmology. I took away a better understanding of the cosmological expansion that from other works I've read.

Greene is more up-to-date in his coverage of the scientific thinking attempting to explain how the quantum mechanical wave 'collapses' when measured. An earlier work In Search of Schrodinger's Cat (John Gribbin - 1984) is an enjoyable read on this - but leaves us with the unpallatable choice between a mysteriously collapsing wave function, and the existence of a virtually infinite number of parallel universes. Greene describes a wider set of plausable theories - including decoherence.

The chapter 'Quanta in the Sky with Diamonds' is particularly compelling. In a nutshell:

- the cosmic background radiation emanating from the "Big Bang" (i.e. the beginning of the universe we observe today) is practically uniform - but with small but measurable variations.
- based on quantum theory, quantum fluctuations at the birth of the universe explain these variations almost exactly.

As Greene writes on p. 309:

"I hope you're blown away by this concordance of theory and observation,"

Yes Professor Greene, that I am.

No comments: