Greenstein explores the improbable fitness of the universe to life. Coincidences ranging from the dimensionality, emptiness and uniformity of space to the ridiculously unlikely sub-atomic nature of matter are covered. The thesis is that Darwinism is a door that swings both ways – not only is life maximized in fitness to the environment, but the environment too is made fit for (and possibly by) life.
The heart of this argument is the Anthropic Principle, which simply states that the environment is fit for life. The weak form of this principle applies to a given niche where life is flourishing. That life enjoys, and may even be aware of, the fortunate circumstances it finds itself in. But, since there are almost infinite places in time and space, it is not surprising that one or two prove hospitable to life, and that although that life may be happy about its good fortune, it might not even be aware that its niche was exceedingly rare. The strong Anthropic Principle, however, applies to all places in time and space. It states that the entire universe is extremely fit for life. This is demonstrated by several examples such as stellar fusion and the properties of water. In this case, something created the universe to be fit for life. Rejecting theism, Greenstein puts forth the possibility that there is a symbiosis at work here – between the universe and the observer who creates it (argued using quantum physics). A mind-bending proposal to say the least.
To his credit, Greenstein ends with the admission that should it prove that this universe is but one instance of infinite disconnected realities, the strong Anthropic Principle would vanish, because this entire universe could then be considered as only one niche hospitable to life.
A good read, presented as a proper theory with evidence to support it and possible observations predicted by it.