The Anthropic Cosmological Principle (Oxford Paperbacks) [Paperback]

The title, density of equations and sheer size of this book will either intrigue you or scare you to death. It intrigued me - and once read - left me with a great sense of wonder at this universe we live in. If you are not an extremely well read physicist you will have to persevere with some of the dense well argued detail and take most of the equations at face value but you will be well rewarded.

This book is as free from bias as I think a book on this topic can be, and is certainly free from the card-carrying philosophical baggage with which may other works in this area are fraught. Opening with a careful definition of the various forms of the cosmological principles the first few chapters take a broad sweep through the history of philosophical thought. It charts the origins of the various streams of thought concerning what we are all doing here - and why. The rest of the book them systematically links these with current scientific thinking very effectively. This introduction is well worth reading in its own right if the subsequent equations are going to scare you!

Approaching the problem from multiple angles - chemistry, biology, stellar evolution, and dimensionality, to name but a few, the journey begins. Taking a belief in the theory of evolution as a pre-requisite, it explains just how remarkable our existence really is. A central theme of the book is the anthropic significance of the continuing uncertainty as to whether the universe will expand forever or collapse back into itself. From every angle the key characteristics that our universe requires to support intelligent life are examined paying particular attention to the tolerance to certain variables that intelligent life can display, highlighting the implied cosmological consequences. Resisting the temptation to steer the reader to one viewpoint or another the book tirelessly explores how this marvel of intelligent life could occur.

The climax of the book is a discussion of the possibility that other intelligent life exists, or will exist at some time, in our universe - and explores the logical consequences of this for closed and open universes. It is here that the authors appear to have an opinion, but it is still well argued and credible.

To the atheist and believer alike this book will force you to consider the wonder of our universe and wonder at the fact of our existence. Persevere and you will be well rewarded!

If you are interested in the revival of anthropic reasoning and why our Universe appears fine-tuned then this is an essential must read classic. The renowned authors present a refreshingly unbiased approach to a complex and potentially dry labyrinth of subjects and even take an irreverent swipe at some topics with the occasional humorous epigram at the beginning of each section. Be aware though, the quotation preceding the foreword "Ah Mr Gibbon, another damned fat square book..." is a warning of the perseverance required of the reader. The density of text and the almost continuous run of scientific equations in the central chapters demand much fortitude. The work can be used as a reference guide with each chapter dipped into independently, which is just as well. However, the content is grouped into the following major discussions in sequence - a romp through the dramatis personae of philosophy, scientific thought and metaphysics from ancient to modern, the re-emergence of the anthropic principle, the significance of the anthropic principle in the modern scientific context and finally several speculative not to say rather wacky chapters covering space travel and the future of the Universe.

Collectively the monograph is well written and presented, but I found the early chapters repetitive and dragged quite a bit. The scientific demonstrations of the anthropic principle were better and particularly persuasive; the chapter on biochemistry and the premise in the chapter on astrophysics that many gross physical properties can be described in terms of only two dimensionless parameters, the fine structure constant and the electron to proton mass ratio, is remarkable. Despite being an erstwhile scientist I had to take many of the equations on trust but managed to work through a good few and I found that my scepticism began to grow when the authors made simplifying equivalencies or unjustified assumptions which led to questionable values sometimes pulled from a hat e.g. sensationally raising the approximate number n of crucial steps in the evolution of modern man from 10 to 110,000 - come on, no way! Some of the theories discussed as the investigation unfolds and especially in the final chapters are decidedly off the wall but then again so are many other hypotheses in cosmology and quantum mechanics. Scientific knowledge, particularly in quantum theory and cosmology, has progressed significantly even since the first edition was produced in 1986 and this book needs a thorough revision to reflect this.

This is a thought-provoking influential book responsible for introducing significant philosophical and empirical implications and is an essential read for all those interested in the anthropic debate.

I rate this along with Penrose's The Emperor's New Mind: Concerning Computers, Minds and the Laws of Physics (Popular Science) as being on the exact borderline between popular science and the domain of the serious practitioner. If you've got a bit of rusty old undergraduate maths, and you want to engage with some fascinating science that they didn't teach you in school/college, then you should just about be able to hang on for this exhilarating ride.

It's a tour of physics, all of science in fact, but arranged sort of transversely to the usual treatments, in such a way as to illustrate the numerous ways in which anthropic thinking impacts on modern science. So it's as much a philosophy of Physics as a straight physics text.

So starting from the very beginning, we look at all the infinitude of ways the big bang might have worked out: from universes so brief or tiny as to be 'pointless', to those that don't have a sufficient preponderance of matter or anti-matter, and so end up too empty to be interesting. However, we thinking beings find ourselves in a Goldilock's universe that's 'just right', and we examine the exquisitely tuned parameters required for this to be so.

Next we look at how gravity is arranged 'just right' so as to make galaxies, stars and planets, rather than an endlessly dissipating cloud of fog, or at the other extreme, a universe of nothing but black holes.

We then move on to the nuclear forces and find all the ways it might have been whereby there was nothing more interesting than hydrogen, or helium, or nitrogen, or carbon, or where all there is iron, and so on. But again we find ourselves in the Goldilock's universe, where the exquisitely tuned parameters of the nuclear forces allow the stars to ignite and turn simple nuclei into a rich variety of other nuclei, which in turn provide the basis of a chemistry interesting enough for life to develop.

And so on up the chain of being we go. Quantum parameters that allow chemistry interesting enough to make molecules, that are in turn interesting enough to make biological processess possible. The ludicrous unlikelihod of a molecule that can self-replicate (DNA), and not just that, but that can interact with other ludicrously unlikely molecules to reliably build intricately structured proteins, and so on.

We study planets and the rather narrow range of size/masses they must have in order to retain atmospheres and liquid oceans, and allow complex organisms to stand up and move around without falling apart or drifting off into space. We consider why carbon based life forms are the most likely sort, because no other atom has chemistry interesting enough to generate the huge range of macromolecules upon which biology depends.

We look at all the alleys that evolution explored before it got around to trying the big brain strategy, and speculate a bit on how big a brain has to be before it can start reflecting on the structure of the universe it finds itself in, thus finally coming round to framing the anthropic question: how we thinking beings come to find ourselves living at a place and time capable of supporting thinking beings? Along the way we have watched the probabilities against such a universe stack up in a geometric series of infinitesimals.

We then explore the ramifications of the anthropic principle and its various weak to strong flavours. From the position whereby this one and only exquisitely tuned universe implies a Designer God, but also observing that the Designer God is as ludicrously improbable as the Universe its supposed to explain. At the other extreme we have the position that all Universes that can be, are, and its simple logical necessity that we thinking beings find ourselves in one of the tiny subset that can support thinking beings. There is in fact a beautiful little book by the philosopher John Leslie Universes which I found an excellent follow up to this aspect of anthropic thinking. Leslie is a theist, but presents the ramifications of the anthropic principle systematically, and makes clear that there is no final clincher in cosmology to determine the correct position.

The last couple of chapters are more speculative, and include the speculations of Brandon Carter, arguably the father of modern anthropic thinking and Tipler's more infamous conjectures about omega points, immortality, total universal intelligence and so on. The author's make clear that these are speculations, and that they are above all good fun to think about. Unfortunately, more credulous theorisers have latched on to some of these notions in such a way as to give anthropic thinking a bad reputation amongst the more sober science community. A shame, because there are some serious questions to be answered there.