But there is still a puzzle of why inflation should have just the right strength to lead to a universe like our own. The "natural" size for a universe is down in the sub-atomic region, on the scale of the Planck length, 10-35 of a metre, the smallest "distance" that can exist. This is where evolution comes in.
The key element that Smolin [Lee Smolin, professor of physics at the Center for Gravitational Physics and Geometry at Pennsylvania State University] has introduced is the idea that every time a black hole collapses into a singularity and a new baby universe is formed with a new space-time, the laws of physics that are born with it are slightly different. The force of gravity, for example, may be a little stronger--or weaker--than in the parent. The process, he argues, resembles the way mutations provide the variability among organic life forms on which natural selection can operate.
Each baby universe, says Smolin, is not a perfect replica of its parent but a slightly mutated form. The original, natural state of a baby universe may indeed be to expand out to a few times the Planck length, before collapsing once again. But if the random changes in the workings of the laws of physics--the mutations--happen to allow a little bit more inflation, a baby universe will grow a little larger. If it becomes big enough, it may separate into two or more different regions that each collapse to make a new singularity and thereby trigger the birth of another generation of universes.
Those new universes will also be slightly different form their parents. Some may lose the ability to grow much larger than the Planck length, and will fade back into the quantum realm. But some may have a little more inflation still than their parents, growing even larger, producing more black holes and giving birth to more baby universes in their turn. The number of new universes that are produced in each generation will be roughly proportional to the volume of the parent universe. "The essential point," says Smolin, "is that the universes that reproduce the most successfully by leaving the largest number of progeny dominate the ensemble after many generations."
The end product should be not one but many universes, all about as big as it is possible to get while still being inside a black hole and in which the parameters of physics are such that the formation of stars and black holes is favoured. Our Universe exactly matches that description.
This explains the otherwise baffling mystery of why the Universe we live in should be "set up" in what seems, at first sight, such an unusual way. Just as you would not expect a random collection of chemicals suddenly to organize themselves into a human being, so you would not expect a random collection of physical laws emerging from a singularity to give rise to a Universe like the one we live in.
Smolin has stopped short of suggesting that the Universe is alive. But heredity is one of the defining attributes of life, and Smolin suggests that universes pass on their characteristics to their offspring with only minor changes, just as people pass on their characteristics to their children with only minor changes. Universes that are successful in evolutionary terms are the ones that leave the most offspring. Provided that the random mutations are indeed small, there will be a genuinely evolutionary process favouring larger and larger universes...
... Before Charles Darwin and Alfred Wallace came up with the idea of evolution, may people believed that the only way to explain the existence of so unlikely an organism as a human being was by supernatural intervention. The apparent unlikelikhood of the Universe has similarly led some people to suggest that the big bang many have resulted from supernatural intervention. Even respectable cosmologists such as Davies [Paul Davies, cosmologist at the University of Adelaide] and Frank Tippler of the University of New Orleans talk of the new cosmology as revealing "the mind of God" at work.
But if Smolin is right, there is no longer any basis for invoking the supernatural. We live in a Universe which is exactly the most likely kind of universe to exist if there are many living universes that have evolved in the same way that living things on Earth have evolved."
I was going along with John Gribbin right up to the last couple of paragraphs. But then he took the standard Western science precaution of emphasizing that all of the above can proceed in a quite mechanical fashion (he exposes his deterministic perspective with the phrase "...a Universe which is exactly the most likely kind of universe to exist.") IMHO, he's speaking the language of emergent complexity, but avoiding the truly wondrous implication of his line of reasoning; if our Universe is but one of a perhaps infinitely large group of evolving universes, then what about the possibility of emergent consciousness, just as has occurred on this small planet with human beings, dolphins, etc. And once one Universe becomes conscious, might it not figure out a way to breach its isolation from within its own black hole, and reach out to its neighboring Universes, and thus perhaps start an emergent co-evolutionary process amongst a community of conscious Universes?