I'm a little dismayed by the ratio of 1-star to 5-star reviews on this title. Seems our popular physics reading community has lowered its standards in recent (...) years.
Fact is, this is a work of genius, but it takes some knowledge of basic physics to be appreciated. In other words, it is not for beginners. That Dr. Barbour tries to reach out to the uneducated is perhaps his only flaw with this presentation. For that, consider this actually to be a 4-1/2 star review.
I think the neophyte's basic problem with the notion of a timeless universe stems from his inability to conveive that a static configuration space can yield the illusion of temporal flow and causality. To this I say that Dr. Barbour is a PHYSICIST, not a religious mystic nor a neuropsychologist! That's not the man's job! He's just telling what his physics is saying, and it is that the universe exists Then, Now, and all Nows-we-have-yet-to-perceive. Everything that exists exists simulatenously. Only in our heads do we experience past, present, and future. Temporality is an act of consciousness (or unconsciousness). Don't expect the man, a mere physicist, to offer pearls of wisdom concerning human experience of time.
I can see some other reasons why newcomers may have problems with the book. First there is the notion of configuration space, the greatest of which Barbour calls "Platonia", his nickname for the "universal relative configuration space" (4 syllables instead of 13, a nice simplification). It should go without saying that compressing our 3 dimensions of space into a single axis on a space-time graph requires a profound imaginative effort beyond most neophyte readers of physics. You just have to keep at reading and thinking about it for a long long time before you can "get it".
Second there is Mach's principle, the idea that all the matter in the far-off universe affects the inertial behaviour of matter in our laboratories right here on Earth. My only possible criticism of Barbour's presentation is that, like configuration space, he does not spend quite enough space (pages) explaining this basic concept to physics-ignoramuses. This is a pity, since it also is a central theme of his argument for the timeless universe.
Let me just mention three other books that may help with understanding Mach's principle. 1) "The Fabric of the Universe" by Brian Greene pages 33-38, 72-74, and 417. this for the basics and their significances. 2) "Was Einstein Right" by Clifford Will pages 149-152. Includes a nice diagram of "Newton's Bucket" and 3) "Dreams of a Final Theory" by Steven Weinberg pages 143-144. These two sentences most particularly -- "The circulation of the matter of the universe around the zenith seem by observers on the merry-go-round produces a field somewhat like the magnetic field produced by the circulation of electricity in the coils of an electromagnet. It is this 'gravitomagnetic' field that in the merry-go-round frame of reference produces the effects that in more conventional frames of reference are attributed to the centrifugal force."
Barbour says very the same thing when he says that the spinning far-off stars create a gravitational field that affects the water in Newton's bucket right here on Earth. And this is one (only one) of the places where the neophyte reader's lack of basic physics frustrates his ability to appreciate Barbour's work. Because any physics undergrad will tell you that when you accelerate (read:rotate) a charged object, you cause it to emit radiation. Well, the "charge" associated with the gravitational field is mass. Yes -- shake your fist and your are emitting (very very weak) gravitational radiation. And so it is with the spinning stars. And since all motion is relative (thanks, Einstein!) it matters not whether you are turning circles or it is the far-off stars! Without a basic foundation in physics knowledge, this basic fact will go right over the head of the neophyte reader of Barbour.
Perhaps one other thing that might bother the reader weak in physics is Dr. Barbour's use of metaphors to describe some of his concepts. Most prominent is his use of the "Blue Mist" to represent the Schrodinger wave function, and "Triangle Land". Well, the use of these sorts of metaphors are historical fixtures in popular physics exposition. Most famously we have Schrodinger's cat. Most telling I think is Feynman's "QED", in which he uses little spinning clocks within photons to delineate the phase relationships between them. The object with the metaphors is to boil down complex ideas into readily graspable mental objects that intuitively represent them. This is something that the reader new to popular physics will just have to get used to. Don't just say "I don't understand this Blue Mist rubbish...this guy is an eggheaded jerk". Well buddy, fact is he's got it and you don't. You'll just have to work harder if you do want to get it.
Let me say just one thing about this charge of Dr. Barbour's "arrogance". He's working on the cutting edge of spacetime physics, and he's invested his entire life in this work. This book you're holding is the result of decades of dedicated effort (let's remember it takes 10 years of hard work "just to get a PhD"). And physicists in general think they're above the rest of us mere mortals...remember Szilard was so "prima-donna" that he wouldn't flush his own toilet for himself! That said, he wouldn't have attempted a popular science book if he didn't care about the understanding of us "little people"; he would have just stuck to the professional journals. I think Dr. Barbour gets this rap mainly because of the book's sub-title "The Next Revolution in Physics" right on the cover. For some, I suppose that could be a turnoff. But think, if his ideas are right, it certainly would be true. And at least I belive if he's not right, he's on to something with this book.
These topics of space and time are so complex that any sophisticated thinker must necessarily sling these basics of physics around left-and-right to get anything done. But we see that it's just too much for the uneducated physics reader to keep up with. So we must mute our criticism where the complexities get beyond our depth.
And yet, Barbour does try in this book to reach out to the unsophisticated reader. He patiently spends many pages explaining the basics of relativity and quantum (wave) mechanics. In my opinion this is the book's only possibly flaw -- admirable yet ultimately lost on this new [...] generation. He should have spent more time explaining the core ideas -- Platonia, configuration spaces, and Mach's principle. With his Kingfisher metaphor he even tries to explain the paradox of instants-and-flow, yet even this noble attempt is commendable-but-misplaced. It only confuses the simple people -- see the one-star reviews here.
Even more noble, I think, is Barbour's career path. He earned his doctorate in physics, then chose to stay outside the university setting and work independently while supporting his family commercially. This is something very very rare while working on the most profound foundational issues. Furthermore, he has published his work professionally (as a working non-professional) in the British science publication "Nature". Be assured this is the very-most high-end of the physics community; to get in Nature your paper must pass peer-review. This is top-flight stuff -- so be assured his ideas are very much worthy of merit, no matter how weird they may seem to you.
Speaking of weird (beyond perception), let's remember that we live on a spinning Earth, and it goes at some 30,000 meters per second around the sun. Which itself revolves around the Milky Way within the Orion Arm even faster. And the Milky Way itself revolves around the Virgo Supercluster yet even faster.
The surface of the Earth looks flat. On a small scale, but I hope we know better by now...
You get the idea. You don't feel these motions or sense these distortions. But science says and we know they are real. And Barbour delivers evidence that the temporal universe we perceive is an illusion -- there is only the relative configuration of objects with their distances in Platonia. How this illusion arises Barbour -- no one -- can yet say, but that is what his physics is saying. Get the book, think, get the other books, and rethink. Maybe this kind of thing bothers the simple people, but books I don't quite understand are the books I like best -- they are ideas you can gnaw on endlessly. "The End of Time" is certainly one of those books.
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