The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos
If you like your science explained rather than asserted, if you like your science writers articulate and intelligible, if you like popular science to make sense, even as it probes the heart of difficult theory, you are going to love The Hidden Reality and its author, Brian Greene.
This book takes us on a tour of nine popular theories of parallel universes. Yes, nine.
As Dr. Greene says, one of the most surprising things about recent developments in theoretical physics, of all flavors, is that the possibility of parallel or multiple universes emerges naturally. From the plain old “quilted” multiverse that general relativity permits, to the 500-dimensional landscape of universes that emerges from string theory, from the foaming bubble universes that inflationary cosmology suggests, to the mathematical Wonderland of the Ultimate Multiverse, Dr. Greene guides us with a firm hand and a sure step.
Most of the ideas in the book are mind-boggling and, inevitably, difficult. So, as we go through, Dr. Greene introduces all the other ideas we will need to grasp in order to understand them. We get a lesson on quantum mechanics and Schrödinger’s equation just in time to understand the “many worlds” hypothesis. We get an excellent side-tour of string theory and M-theory, just before we plunge into the “braneworld” multiverse. And it is all good stuff.
Dr. Greene has done a superb job of anticipating all those “But what about . . . ?” questions that form in the reader’s mind during such an excursion. Almost as soon as the questions occur, he dives off into a description of the anthropic principle, or a discussion of the nature of infinity, or a quick review of the arguments about whether string theory is actually scientific or not. And all the while he remains humble and honest in the face of the many controversies and uncertainties in the various theories he describes. (Why does string theory require 10 dimensions? Because it makes the math work. He shrugs, and moves on.)
It is rare to encounter a book of such scope and depth that avoids mathematics almost completely (except in a few endnotes, where the “mathematically inclined reader” is thrown a few crumbs) and yet makes so much sense. It is in Dr. Greene’s clever use of analogies and similes that the strength of his text rests. It is also where so many other popular science writers fall down.
Yet even Dr. Greene is not infallible. When he explains why probabilistic reasoning in a “many worlds” context is problematic, he makes use of a “cloning” analogy which is itself contentious and inappropriate. We get what he’s saying, despite this, but it is a shame to see even this little flaw in such an excellent book.
Some readers may balk at the fact that the text has copious endnotes as well as occasional footnotes. It would have been better if Dr. Greene had made the effort to integrate the information in these notes into the body of the text, or to have used footnotes exclusively. Almost all of the material in the notes is useful and interesting and definitely belongs in the book somewhere, but reading with two bookmarks is a nuisance, and it is going to make any ebook edition even less manageable.
In the end, though, such minor quibbles are irrelevant. The Hidden Reality is a first-class piece of popular science writing. It is clearly written, thoughtful and discursive, and covers material that in itself should be of great interest to any thinking person these days. Dr. Greene is always aware of how bizarre most of the ideas he describes will sound, and takes all reasonable pains to ensure that the historical context and scientific arguments are presented to ensure the reader understands just how these ideas arose and what problems in physics they address.
It is a book that deserves huge success.