Customer Reviews

Road to Reality

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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!

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'.

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..."

This book looks like a bestseller buy it is not as easy to grasp by the average read as it might seem at first sight. It is extermelly long, the number of topics treated is overhelming and it is full of formulas. The author claims you can skip these formulas and you will still benfit from the insights of its pages. However I am not so sure about this statement. Without the formulas you miss much of the value of the book and it becomes increasingly difficult to understand.

It will require you a special mental predisposition to finish the book and in its desire to cover everything, the author makes what in my opinion are unnecesary incursions into complex mathematics to explaian even simple concepts.

Nevertheles, I like Penrose's sometimes revolutionary proposals and it is refresheing to find sombody who dares to oppose the mainstream ideas from time to time. This reason alone makes the book worthwhile.

Other reviews focus on whether the book is easy to understand or not, or wheter it is too big or not. And it would seem that

the only purpose of the book is to put all togheter the physical laws mankind knows.

But this is a book with a message. A message that takes very long to transmit and Penrose chose to start from the very begining.

A significant part of the physics as it is known today is exposed in a long (900 pages) preamble, but Penrose wants to tell

us that he believes that the road to the Theory of Everything that is standard in today's physics leads nowhere.

If you have read "The Emperor's new mind" you know that Penrose's ideas are not mainstream in today's physics. But if you are

interested in cutting edge physics you'll also know that there is a growing number of physicists that believe that the field is on crisis. Let me sumarize Penrose views:

- The standard interpretations of quantum mechanics are wrong. Even the decoherence approach.

- Infactionary cosmology cannot be right.

- Superstring theory is just a beautiful mathematical construction with no connection to the physical world. His point of view is similar to Smolin's ("The trouble with physics").

I'm not at all an expert on the field, although I studied quantum mechanics in the University, and I'd say that at least Penrose has a very strong point. He is not able to provide but hints of alternative theories but this does not lower the merit of the book.

He also explains standard areas of mathematics and physics such as complex number calculus, Maxwell fields or group theory in a non-conventional but brilliant way. For example, it includes a beautiful demonstration of Pythagoream theorem. The chapter about the standard model of particle physics is particularly helpful; nowhere else can be found a concise and understable explanation of it.

And yes, the book is difficult, but if you don't understand the mathematics, just keep reading.

As it happens, I'm an inhabitant of mathematical Slowland (somewhere between the author's level 1 and level 2 on what is an exponential scale of mathematical knowledge), but this book's preface charmed me into attempting a pilgrimage down "The Road to Reality," even though--or perhaps because--it has lots and lots of math. What is the lure Sir Roger uses in his preface? A profoundly simple explanation of fractions! I've always longed to find a 'Summa Philosophiae Naturalis' that wove together all the physical and mathematical strands of my education. Maybe this will be that 'summa' after its contents finally sink in (it will take multiple readings.) If not, there was still plenty of shock and awe on Sir Roger's Road to Reality.

This author has the special gift of making his readers feel the beauty of scientific ideas through mathematics. Many of the books that have been published recently on the physical mechanisms of our Universe have been a little misty in this respect, probably for fear of losing readers.

Not so Penrose. After a benign preface and opening chapter, his 'Royal Road' plunges his readers head-first into hyperbolic geometry. If it weren't for the Escher woodcut and its subsequent transformations, I might not have plunged in after him. As it was, I almost sank out of sight upon encountering Contour Integration in chapter 7. It was a long, hard 400-page slog to Minkowskian Geometry (chapter 18), after which the heavy physics finally kicked in.

Extended side-trips into James R. Newman's classic "The World of Mathematics" were what saved me and kept me chugging through the first half of 'Reality.' I found I needed a bit of historical perspective on topics such as Riemann spheres, that Sir Roger necessarily had to explain in a formula and a paragraph--unless he wanted his book to bulk up into multiple volumes.

So I highly recommend a supplemental mathematical source such as Newman for the parts in Penrose where you WILL get stuck in the Slough of Despond. Yes, friends, unless you belong to the author's level 4 mathematical elite you will flounder, but throughout your struggle, beautiful fireworks will be going off over your head: a promise of the grandeur to come.

This book is full of glorious explosions, especially when the author is discussing a discrete, rather than real-numbered-base to physics: "Einstein, also, suggested, in his last published words, that a discretely based ('algebraic') theory might be the way forward for the future physics..."

Wait a minute! Does that mean I should flush my 23 semester-hours of calculus down the same toilet that swallowed up phlogiston and Piltdown Man?

Not at all. Penrose includes reams of calculus in this book, for those of you who like to twiddle around with infinitesimals. But do pay attention to the notion of a discrete reality. In the latter, 'physics' section of the book, Sir Roger refers back to discreteness when he discusses his twistor theory of Everything--combining relativity and quantum mechanics without the need for superstring theory.

This book is a thousand-page guide to physics' Grand Unified Theory as expressed by one of the world's most original thinkers. Pick it up and start down a road not usually taken, and I mean that literally as many cosmologists will argue that this author is way off the beaten path.

Despite the previous work of Roger Penrose concerning my favourite topic (neuroscience, mind-brain issues, consciousness, etc.), this is the first book of his that I have read (not quite finished yet, not that fast !). I am quite impressed overall, wanting a well discussed introduction to some of the primary mathematics and physics that have led to our current time. This, Roger Penrose functionally provides, though at times some of his discussion could be clearer. He has made a sensible and successful effort to write at a number of different levels so that those with no mathematical background can read prose for content and ideas, and those with significant previous knowledge and ability can work on proofs of various arguments, etc. This is certainly a weighty set of chapters, and I cannot comment on the appropriateness of some of the latter chapters vis a vis current arguments and the positions held by other scientists, but definitely, this is one of the most significant and important books of its type to arrive on the scene and with some significant effort on the part of the reader, should repay hansomely!

The publication date is supposed to be in 2005, but for some reason this book is already available in Canada.

Penrose is a distinguished mathematical physicist specializing in general relativity. That's where he shines. But his views on certain matters I cannot agree with. His skepticism towards string theory is not shared by the world's top physicists, including Michael Green of Cambridge (Britain) and Steven Weinberg at Texas. He believes Edward Witten is not as great a mathematician as he is a physicist, a view Sir Michael Atiyah would heartily disagree. Penrose completely rejects inflationary theories. But unfortunately for him inflation is grounded in particle physics. Supporters of inflation (at least those who find it convincing) include Leon Ledermann, Steven Weinberg, and the cosmologist the late David Schramm. Penrose doesn't seem to realize that general relativity, great and powerful as it is, can only take you so far in terms of understanding the universe without help from theoretical particle physics. Ironically, Penrose places his faith in quantum mechanics in trying to solve the mystery of the brain, not knowing that physics can only take you so far without help from neurobiology, biochemistry and molecular biology in understanding the consciousness problem (for which physics is certainly required but classical physics plus deterministic chaos will probably be sufficient). When Penrose talks about the brain using quantum theory and relativity, black holes, crystals, and the like, I feel like he is doing precisely what Schroedinger tried to do to the DNA puzzle - ignoring chemistry altogether. That's like a philosopher beating the air with vague ideas. Schroedinger had a good excuse because molecular biology and structural chemistry were still being developed. Penrose seems to be living in a different world, given the spectacular advances in the biological sciences since Schroedinger wrote. On the whole, I have doubts about Penrose's judgment about a lot of other issues as well.

This thick book is not as accessible as it sounds from the front flap. There are quite a few equations with Greek letters, and the diagrams are hand-drawn, black-and-white, and not very clear.