If you ever wonder what possessed the medieval world to defend and embrace the Ptolemaic view of the cosmos against all comers until the time of Copernicus and for some time thereafter, then this book should provide many people with that same level of discomfort that the defenders of Ptolemy must have felt when faced with the idea of a heliocentric cosmos. It is relatively easy to be wise after the event and scorn the ignorance and stubborness of Ptolemy's guard; even Einstein found the idea of an expanding universe (which is what his original equations told him was happening) to be unacceptable; at least until Hubble provided him with the proof. In a similar vein, Brian Greene's The Hidden Reality takes one on a mind-expanding journey through contemporary versions of Parallel Universes held within the community of astrophysicists and mathematicians who spend their time delving into such matters. At first blush, one might be foregiven for thinking that such concepts are to be taken no more seriously than the world of Alice in Wonderland; at least in terms of their representing our 'Hidden Reality.' However, Greene leads us through each proposal in a clear and concise manner to reveal such concepts as:
The Quilted Multiverse
The Inflationary Multiverse
The Brane Multiverse
The Cyclic Multiverse
The Landscape Multiverse
The Quantum Multiverse
The Holographic Multiverse
The Simulated Multiverse
The Ultimate Multiverse
Along the way, ideas from quantum mechanics and string theory are addressed, along with consideration in the final chapter to the question of the Limits to scientific enquiry about these concepts; most of which might prove impossible to ever actually 'test' in a scientific manner.
This book is not an easy read, although given the nature of the concepts under discussion this is hardly surprising. However, Greene manages to provide a relatively clear explanation of the concepts, without resorting to the need to drown the reader in complex equations and mathematics. At the same time, anyone with a reasonable grasp of scientific methodology and some background in physics and mathematics will probably find this a fascintating read. To really get to grips with the subject matter would involve a more careful rereading and study of the contents, but for an overview of the ideas an initial diligent read will suffice.
Certainly, I should recommend this book to anyone interested in finding out about current thinking and ideas around this subject. I totally disagree that this book could have been reduced to 20 pages and that the remaining 95% is waffle as suggested by one other reviewer. This is not light reading, but nor is it waffle. Indeed, it is impressive precisely because it keeps focused throughout and ties the varoius ideas together in a coherent and meaningful manner. Above all, even if you regularly read books about philosopy of mind, metaphysics, epistemology, science fiction relating to parallel universes, newtonian and quantum mechanics the ideas in this book will certainly provide some stimulating and entertaining food for thought.