Most Helpful Customer Reviews
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22 of 22 people found the following review helpful:
5.0 out of 5 stars
A wonderful book, October 4, 2004
This is a terrific book. It can take a bright reader who has no more than an undergraduate college degree in a technical field and bring that person to a point where they can read and understand technical papers about fundamental physics and cosmology. It discusses these topics in a way not open to many books for the layman, since it has brought the reader up to speed on the necessary mathematics. Some of the math can be skipped, of course, but it is there to bring the material to life.
Of course, that means starting the book with over 350 pages of math, taught in impressive style by the author, including Euclidean and hyperbolic geometry, number theory, complex numbers, logarithms, complex powers, real and complex calculus, Riemann surfaces, Fourier series, Vector fields, Quaternions, Manifolds, Symmetry groups, and Fibre bundles! That allows him to proceed to discuss quantum mechanics and the rest of fundamental physics.
It is true that Penrose does mention his views about inflation and string theory. But the fact that he has views about these theories does not in any way stop him from being a great teacher. He covers the field of fundamental physics very well indeed.
Penrose does impart a very important viewpoint that I think is valuable for us all. Most scientists are basically positivists: that is, they search for theories that will correspond to measurements (pass experimental tests and provide accurate predictions). It is secondary to them what reality happens to be. But there is something to be said for asking what the reality behind the physics actually is.
If you are a very bright high school graduate about to go to some top notch university to try to become a theoretical physicist, read this book now!
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12 of 12 people found the following review helpful:
5.0 out of 5 stars
Encyclopedic survey of modern physics, October 27, 2004
A complete and encyclopedic view of modern physics. Not for casual reading as it is full of mathematical equations; but as the author says in the preface the maths can be safetly ignored while still making the book understandable with some efforts. Covers everything from Relativity, Quantum Physics to String Theory. Penrose also explains the maths required to understand the various concepts. In all a great book from the master who gave us 'The Emperors New Mind' and 'Shadows of the Mind'.
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7 of 7 people found the following review helpful:
5.0 out of 5 stars
Brilliant, June 28, 2005
While this book is essentially an elaboration of Penrose's earlier books and theories, it appears it was worth the effort (both his and the readers). I agree with reviewer Lee Carlson's comment that "The chapter on the Big Bang and its 'thermodynamic legacy' is the best in the book", though experts in other fields may enjoy (or be challenged) by other chapters.
In his chapter 27 on thermodynamics, Penrose seems to finally 'bury' dissenters who believe there is nothing unique or improbable about the universe. For instance in Vic Stenger's attack in his book Timeless Reality he says:
"The initial entropy of the universe was also as large as it could have been, since it was also the entropy of a black hole. Thus, the universe has maximum entropy at the two extremes on the time axis. In each case, the universe is in equilibrium. At each time, the univserse is in a static state of total chaos. This is a point that has been missed by almost everyone, including Penrose." [Referring to his earlier book The Emperor's New Mind.]
In his recent book Penrose counters:
"Now let us return to the extraordinary 'specialness' of the Big Bang. The fact that it must have had as absurdly low entropy is already evident from the mere existence of the Second Law of thermodynamics. But low entropy can take many different forms. We want to understand the particular way in which our universe was initially special...
It seems to me that this apparent thermal equilibrium in the early universe has grossly misled some cosmologists into thinking that the Big Bang was somehow high entropy 'random' (i.e. thermal) state, despite the fact that, because of the second law, it must have actually been a very organized (i.e. low entropy) state. A prevalent view seems to have been that the resolution of this paradox must lie in the fact that, soon after the Big Bang, the universe was 'small' so that comparatively few degrees of freedom were available to it, giving a low 'ceiling' to possible entropies. This point of view is fallacious, however, as was pointed out [earlier]. The correct resolution of the apparent paradox lies in the fact that the gravitational degrees of freedom have not been thermalized along with all of those matter and electromagnetic degrees of freedom...In fact, these gravitational degrees of freedom -providing a huge reservoir of entropy -are frequently not take into account at all...Rather than sharing in the thermalization that, in the early universe, applies to all other fields, gravity remains aloof, its degrees of freedom lying in wait, so that the second law would come into play as these degrees of freedom begin to become taken up. Not only does this give us a Second Law, but it gives us one in the particular form that we observe in nature. Gravity just seems to have been different!...physicists have tried to come to terms with this puzzle and related ones, concerning the origin of the universe. In my opinion, none of these attempts comes at all close to dealing with the puzzle..."
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