Loading... ## Cycles of Time: An Extraordinary New View of the Universe (2010)## by Roger Penrose
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Sign up for LibraryThing to find out whether you'll like this book. No current Talk conversations about this book. Too mathy for me (although I appreciated his lack of condescension in presenting the math clearly and cogently for the general public) but I'm interested in all current non-theist, and preferably non-metaphysical attempts to speculate about the origin and destiny of the cosmos. So I can now add conformal cyclic cosmology to my collection: an infinite series of universes whose endings merge into the beginnings of the next through a matching low entropy and absence of structure and mass. (Even though the Second Law of Thermodynamics says entropy always increases, Penrose says that at a spacetime near infinity all matter will have collapsed into black holes, which he says will then evaporate, destroying entropy... I have to say it all sounds a bit wishful thinking-y when you put it like that. And of course we're no closer to knowing the mechanism by which this transition from the almost infinitely large to the infinitesimally small happens. Also some key evidence he thought he had in the cosmic microwave background radiation has been disputed... But anyway, that's just where theoretical physics is at these days - it's not a consensus sort of place. In fact, physicists can't even seem to agree if it's the best of times or the worst of times for cosmology.) ( ) This groundbreaking book presents a new perspective on three of cosmology’s essential questions: What came before the Big Bang? What is the source of order in our universe? And what cosmic future awaits us? Penrose shows how the expected fate of our ever-accelerating and expanding universe—heat death or ultimate entropy—can actually be reinterpreted as the conditions that will begin a new “Big Bang.” He details the basic principles beneath our universe, explaining various standard and non-standard cosmological models, the fundamental role of the cosmic microwave background, the paramount significance of black holes, and other basic building blocks of contemporary physics. Intellectually thrilling and widely accessible, Cycles of Time is a welcome new contribution to our understanding of the universe from one of our greatest mathematicians and thinkers. This is a short book with many chapters, making it a snappy read for those comfortable with abstract concepts. Penrose starts slowly taking the reader through some relevant basics of entropy and then defines his prime concern. Why were the conditions of the big bang so special? His partial answer is that the big bang was specially prepared by the death throes of a previous cosmos. Of course others have imagined the cosmos goes through cycles of crunch and re-explosion. Penrose’s vision is different. He acknowledges our cosmos will expand forever and die a cold death. Yet through conformal mapping he takes this picture into infinite time and into the start of a new rescaled cosmic aeon. Hence, in Cantorian fashion, he fits an infinite succession of infinite times within a greater infinity. His treatment is thought provoking. Furthermore it is both formal and presumptive. Thus the narrative is less physical and less philosophical than one would get from a theoretical physicist of equal eminence. Moreover it still does not actually explain the specialness of the big bang. Indeed at this preliminary stage it is also unsatisfactorily complicated. But who knows? Be prepared for talk of novel conjectures like a devaluation of phase space and all particle rest masses decaying to zero. The book is okay, but it would be a very difficult read of the average reader. You should have some background in physics and preferably quantum mechanics. It definitely has some interesting idea though. I particularly like his discussion of entropy. _Cycles of Time: An Extraordinary New View of the Universe_, by Roger Penrose, Alfred A Knopf, 2011. Far from the "same old same-old" as regards cosmology books, this one presents the distinguished Penrose's own Conformal Cyclic Cosmology (CCC), which takes great care to respect the laws of thermodynamics. To quote from Wikipedia, "In CCC, the universe iterates through infinite cycles, with the future timelike infinity of each previous iteration being identified with the Big Bang singularity of the next." The book's two appendices (~30 pages) are impenetrably mathematical, and Penrose rightly says they are for experts only. But it seemed to me that some of this impenetrability afflicts large parts of the second half of the main text too. I was very disappointed that I failed to fully understand conformal spacetime diagrams. I never grasped the reason why it is not simply contradictory to say that universe iterations possessing neverending time progressions can form a temporal chain.
Doing what most find impossible has long been Penrose's stock in trade in mathematics and physics, even when it comes to publishing. His previous book, The Road to Reality, was a 1,049-page bestseller, although it was mostly a textbook. Penrose doesn't do "popular", as he peppers his books with equation after equation in defiance of the publishing maxim that each one cuts sales in half. By that reckoning Cycles of Time will have about four readers, though it's probably destined to be another bestseller. As Penrose puts forward his truly Extraordinary New View of the Universe, that the big bang is both the end of one aeon and the beginning of another in an Escheresque endless cycling of time, he outlines the prevailing orthodoxy about the origins of the cosmos.
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