on 16 November 1999
There are currently several books dealing with new theories in physics, they are fascinating but I found the "End of Time" a bit disappointing after all the hype (see reviews above). What I want in a book of this type are three things, firstly to be educated on the general theoretical background, entertainingly presented the history of the subject up to the present day, secondly the author must, as succinctly as possible, explain their theory; show where it supports and where it overturns conventional ideas. Finally the books must present conclusions, sketch out the likely impact of the new concept. The "End of Time" devotes many pages to arguments in favour of the author's thesis, in a way that will bore the general reader but is unlikely to convince the physicists. Near the end of the book my feeling was ok ok you win, just tell me the implications, but that's the problem, the author refuses to speculate, possibly on the spurious grounds that predictions are impossible in a world without time. In summary a long, confusing and eventually a frustrating read. If you want to see how a book of this type should be handled read the unbelievably good "The Inflationary Universe" by Alan H. Guth.
on 15 May 2012
Julian Barbour, a well-known maverick at conferences, has managed to present his unorthodox views in a balanced and accessible way in this popular treatment. His singular vision ties together the various themes in a startling manner. The theory therein is exciting, disturbing, and invigorating.
Somehow a rather complex set of ideas incorporating the canonical approach to quantum gravity, the many worlds interpretation of quantum mechanics, and Barbour's novel approach regarding configuration space are presented at a level anyone bothered to put the time in (ho ho) can understand. Generally, Barbour is good at laying out ideas in a simple manner, although he does occasionally transition from carefully explaining everything to quickly reeling off some technical sentence or other, albeit only in a minority of cases. He writes equations out in words, with some loss of technical generality, on the other hand. My main minor criticism of the book is his description of the wavefunction as three coloured 'mists'. Despite my training in QM, I got lost sometimes when trying to remember whether blue represented probability or position and so on.
I think the main reason the book works is because Barbour's theories are themselves usually only describable in qualitative terms anyway, since quite preliminary. I've often thought cutting edge ideas are often easier to explain than well-established ones, since often they only exist in qualitative form. And Barbour has a vision, a breathtaking vision, one that incorporates many themes that are now (2012) even 'hotter' then they were back in 1999, which I think is the original publication date. Barbour's approach to QG is fascinating, even if it should prove false.
One further minor quibble, however, is that the book is called the end of TIME, and Barbour's theory is presented as a theory of time (i.e. there isn't any 'flow,' etc.), yet in reality it is an anti-realist position with regard to MOTION and/or real 'becoming,' NOT 'time' as such. The further independent argument required - that time is reducible to change, motion, etc. - even if plausible, is nowhere satisfactorily provided. The nearest Babrour comes to providing such, in my view, is when he mentions a critique of Ashtekar's views. (It may be objected that Barbour's positive arguments for a 'Machian' approach incorporate a certain denial of absolute and/or real time, but this requires an argument. Since distinctions such as denying A-series, B-series, or C-series time are not addressed, for example).
Incidentally, where Barbour contrasts his MWI with other historical Everettian's, including Everett, an update would be interesting, since the field has moved on so much since 1999, perhaps partly inspired by Barbour's book.
All in all, this is an accessible and brilliant book, containing one of the most interesting unified views on nature, physics and time ever. If you enjoyed Deutsch's Fabric of Reality from the late 90s, you'll probably enjoy this book too. Barbour is careful, perhaps more so than Deutsch, to point out his ideas are unorthodox, in terms of the 'sociology' of physics. However, much as in the case of Deutsch, a sizeable and growing minority of physicists are developing ideas that resemble many of those contained in this book.
I should note that I find Barbour's conception of 'Nows' or 'instants' physically incoherent, but that it took me a long time to work around his many brilliant and subtle arguments contained herein.
on 5 November 2010
Written both for the popular-science market and for scientists and philosophers, only the latter shall fully enjoy this remarkable book. Because they have developed their mind's eye, enabling them to see four-dimensional space-time or Riemannian spaces just as clearly as everyone can see a thing extended in two directions.
The author argues that the apparent passage of time is an illusion. If we could stand outside the universe and 'see it 'as it is'', it would appear to be static. This radical conclusion is reached by considering the most basic structure of Einstein''s general theory of relativity and quantum mechanics, the two fundamental theories of physics.
In particular, time is treated in completely different ways in the two theories. This presents a severe problem, since all serious workers in the field are convinced that the two theories must eventually be subsumed in a single over-arching theory. This will be the quantum theory of the universe (also called quantum gravity). The finding of this theory presents many great difficulties, of which the 'problem of time' is perhaps the most severe. It seems that a choice has to be made between two irreconcilable notions of time. The author argues that the only satisfactory solution is to abolish time altogether and outlines a timeless quantum theory of the universe.
Is included a proposed solution to one of the most intractable problems of physics : what is the origin of the so-called arrow of time? Why is it that all phenomena distinguish a common direction of time (i.e., why does entropy increase?), but the equations of physics are symmetric with respect to the direction of time? The equations of physics allow not only the shattering of a cup that is dropped on the floor but also the re-assembly of the pieces. However, that is never observed. A theory of the universe should explain why entropy increases.
'The End of Time' suggests that a fundamental asymmetry in the space of all the possible structures of the universe could provide a basis for the arrow of time.
Not highly readable, nor accessible to the layman; but profound, original and creative, this book deserves five stars.