Smolin spends most of the book using simple-to-understand language and clear examples that are easy for the layperson to follow. The pace here can be at times too slow, and the repetition a little grating. Near the end of the book he introduces the reader to some more challenging concepts such as quantum graphity, which by comparison seem to be dealt with far too briefly for the reader to fully understand. On reflection this material is adequately paced, but by the time it is reached the reader has been lulled into a slower pace and so must ratchet up his attention accordingly. The material would be better served by having the pace build more gradually rather than the somewhat abrupt transition from a metaphorical walk to a jog.
For myself it was refreshing to hear some of my own cosmological thinking expressed in the views of a physicist such as Smolin rather than yet another load of verbal diarrhea on multiple universes and simulation universes gobble-de-gook that seems to have permeated the shelves of popular science "non-fiction". Among Smolin's proposals is the idea that the laws of physics are not eternal, they do not act outside of time and reach into the material world, but they instead evolve along with the initial conditions and are subject to time just as everything else is. This is not a new idea, but it is certainly not a very well publicized one, as Smolin was surprised to discover his ideas echoed those of philosopher Charles Sanders Pierce over a century ago. I myself was surprised to find this view shared by Smolin since it aligned with my own thinking for some time yet seemed to be quite absent from the prevailing thought in physics and cosmology. It may turn out that the greatest benefit I will gain from this book is an introduction to Peirce, who's philosophy seems to have been startlingly ahead of its time.
Smolin makes a good but overly verbose argument against the application of general relativity and quantum theory to the universe as a whole on the basis that they are approximate theories suited to parts of the universe but unsuited to the universe as a whole due to their absence of more fundamental elements. That this is the case seems blindingly obvious to me, but I suspect Smolin feels the need to belabour the point due to the stuffy pigheaded conservatism present in the establishment physics community. However, that these theories are incomplete descriptions of the whole universe is widely known and attempts have been made for decades to discover a more fundamental theory. Smolin's main argument then is that these attempts have been failures precisely because they insist on treating time as an emergent phenomenon rather than fundamental, and that they will continue to be failures so long as they do so. Here I felt that Smolin's argument could use more heft. On reflection when one equates time with causality it is indeed impossible to see how causality would emerge from causelessness. But it is not put quite so pointedly in the book.
Throughout the book Smolin takes the reader on a sort of history lesson of science, from Erastokanes through Aristotle, Gallileo, Newton, and Einstein. One can sense that he has simplified the picture so as to suit his own narrative, and while it is informative, one doesn't escape the feeling of being manipulated rather than educated.
Smolin takes the idea of time as fundamental and goes far further with it than I ever had with my feeble mental exercises, attempting to grapple with what it really means to have physical laws that are subject to the ravages of time. This effort isn't just admirable, it's stimulating and perhaps as Smolin argues, necessary for physics to get beyond its current crises. He explores how a view of time as real can be in agreement with general relativity, which counter-intuitively dismisses time, but has demonstrated remarkable predictive power. Smolin highlights his own theory of cosmological natural selection as a possible explanation for the questions of "why these laws?" and "why these initial conditions?" It's a neat theory but I felt Smolin dwells on it too much given its many shortcomings and the fact that it is still philosophically unsatisfying - there is still a multiverse, except now they are causally connected, so it is at least a scientific theory as compared to many multiverse "theories". However, I felt that Smolin himself, perhaps so entrenched in establishment cosmology dogma, did not go far enough in his pursuit of the idea of time as real, with all things subject to time. The most intriguing idea to emerge from the book is that of Smolin's "principle of precedence", which suggests that the elementary particles behave as they do because that's how they have behaved in the past. It's the kind of idea that begs for more to be devoted to it but Smolin leaves it hanging as a sort of tease for the types of ideas that can emerge from "thinking in time".
I don't think Smolin articulates his case well enough to change the minds of those addicted to the dogma of timelessness. And if that is his primary aim then he may well have failed. But Time Reborn represents an important work because it sows the seeds for much different thinking in cosmology, and the more smart thinkers are focused on these difficult questions and the less embroiled in the fantasies of bubble universes, the better.
Smolin devotes the very end of his book to the idea of applying thinking in time to more than just cosmology, but to economics, ecology, and social policy. This is the weakest portion of the book because Smolin fails to make a compelling case for how the conception of timelessness has led to many failed solutions to difficult problems. Smolin highlights the competing views of conservation and exploitation that butt heads over climate change and suggests an active role in managing our climate as a solution. I agree with this thinking, and more optimistic thinking of new uses of technology to better our world is needed to motivate generations of young people to focus on the right problems. But I disagree with Smolin that the conservation vs. exploitation conception is principally rooted in a worldview of timelessness and that it is solved by thinking inside time. I could perhaps be convinced of this, but the arguments to make this so are not to be found in the pages of Smolin's book. If anything, this section in my view seemed to undermine Smolin's earlier arguments, as he seemed to be arguing for the value of the "in-time" worldview based on its positive consequences rather than the truth of the view itself. For me this hints too closely at the sort of dangerous "thinking" espoused by the fanatically religious who are motivated to discredit scientific facts such as evolution because of the world views they believe these facts engender.
References
Smolin, Lee. (April 2013) Time Reborn: From the Crisis in Physics to the Future of the Universe. Boston, Mass.: Houghton-Mifflin Harcourt.
