Each time he described his work to Feynman, he was criticized because Smolin's ideas were not sufficiently crazy! So, much of the book contains some crazy ideas, and it is full of philosophical speculation.
The importance of this book comes not from the proposed cosmological theory itself, but from its understanding of relational cosmology and the philosophical ramifications of relativity and that a natural mechanism _is_ possible to explain the complexity of the universe. The passages on relativity & relational cosmology, complex systems, and art and science places this book at the center of my thoughts as of late.
Still, this is a great book because it delves into questions rarely addressed by proper scientists like- why are the parameters of the universe the way they are and not otherwise; is there an absolute truth and does this lie beyond the reaches of the scientific method; the difference between absolute and relative etc. It also uses principles of biology (natural selection, niche, competition etc) to infer hypotheses about the universe, although i disagree with him and feel his case for cosmic Darwinism is very weak and doesn't test that hypothesis directly. Smolin emphasises why this paradigm shift is important if we wish to have a better theory that describes the universe. It also acts as a self referencing system, and can self organise and spontaneously occur (probably), and smolin tries to apply these principle of biology to cosmology, and gives us a new hypothesis for the universe which doesn't need any external truth, and which relies on the history of a self referencing and self forming universe. I'm yet to read a good, proper science book which discusses how science itself requires some level of faith in the scientific method and in evidence and in reality, but this book is the closest I have come so far. I also like the book because it addresses the philosophical origins and implications of Newtonian physics (the absolute), gen rel (the relational), and QM (the observational and probabilistic), rather than merely describing what these theories are. This book discusses these ideas and introduces another one- of cosmic natural selection to answer the question above. It also discusses what gravity, space time, and time would be like at a quantum level, and why there are so many inconsistencies in physics and in reality itself.
The book's thesis is Smolin's own theory of Cosmological Natural Selection. If a parameter can be changed to increase the rate of black hole formation, it would refute the theory. This sounds a little bit like anthropic reasoning: If the constants of nature weren't fine tuned as they are, we wouldn't be here to worry about the problem of fine tuning. Put another way: If any physical constant is changed from its observed value, OBJECT becomes less likely, therefore THEORY which predicts our universe must have OBJECT is upheld. Replace OBJECT with "black holes" or "intelligent life", and THEORY with "Cosmological Natural Selection" or "The Anthropic Principle", respectively. The not-so-fun part is Smolin's constant, painful, digressions into philosophy. Philosophical Digression #2: God Smolin uses the word "god" 74 times in this book. Philosophical Digression #3: Systems Smolin makes a big deal about complex, self-organizing, stable, and non-equilibrium systems. Philosophical Digression #5: Mysticism Like the word "god", this is another red flag; and it appears 25 times... I can empathize, but there is no excuse for resorting to poetry like this in a science book: "Is there any reason we might not conceive of the world as made up as a network of relationships, of which our appearances are true examples, rather than as made up of some imagined absolute existing things, of which our appearances are mere shadows?" Smolin, please tell me you aren't writing this way just to get chicks.
Each child universe inherits the properties of its parent, with some random mutation, and eventually one (or more) universe formed that is stable enough to give rise to us.
It is interesting to see how the battle between Newton and Leibniz's physics develops throughout the book, which eventually Leibniz comes out as the winner!
There are two books that I've read in my 48 years so far on this Earth which have blown my mind and completely changed my whole way of looking at things, and this is one of them. If you're not too physics-minded, you can just read and enjoy the part (in the first half of the book) where Smolin describes his theory that a big bang and a black hole are like reverse mirror images of each other.
Smolin writes in complex sentences, compounded by a generous sprinkling of grammatical errors, all of which conspire to make it a hard, slow, tedious read.
I learned a lot here and there and although I'm not a convert yet, I love the ideas of self-organization and natural selection.