4 comments about It's About Time: Understanding Einstein's Relativity.

1. The basic ideas making up Albert Einstein's special theory of relativity are relatively easy to understand. The only mathematics required to understand the formulas is basic algebra and very little knowledge of physics is needed. The only essential physics background is an understanding of many of the words of physics. Concepts such as linear momentum, electromagnetic radiation, computing with units, velocity and simultaneity must all be clearly understood before you read this book.
   Once into it, you will find some of the best non-technical descriptions of the special theory of relativity that have ever been published. While the author does not pathologically shrink from using equations, he also does not become infatuated with them. There are just enough to demonstrate the concepts and none that I considered superfluous. Many diagrams are used to illustrate the ideas and equations and the text is a superb complement to the formulas and figures.
   The world where the special theory of relativity is valid is a strange one where our intuitive ideas based on everyday phenomena no longer apply. However, it is not impossible to understand and this book is the best place to begin that process.



2. The book is as simple as it can be but not simpler. It is as if Einstein learnt to explain in english. It cleared my way of thinking about time-place events. Now I am just afraid to think how many such simple things can be out there which my mind has not yet ever analysed.



3. One hundred years after Einstein published the theory of relativity, publishers are still promoting popular books that explain reltivity to the lay reader. This is the best such book that I have read. That's because Mermin's approach is to help the reder to develop a thinking style so that it becomes almost second nature to get your brain to hop between moving frames of reference. Mermin's thought experiments examine the outcome of experiments performed on moving trains or by moving rockets. The reader discovers the trick of examining the outcome from two points of view: inside the moving train, and outside watching the train go by. Almost everyone, including professers of physics, will benefit from a careful rreading of this book. It does include many equations and diagrams.



4. Introduction of formulas a priori with only consecutive derivation is preceptionally inadequate. This combined with too a verbose and insufficiently organized progress of the argument makes for an uneasy reading.

No comments about El código maya: La aceleración del tiempo y el despertar de la conciencia mundial.

5 comments about Time and the Art of Living.

1. Robert Grudin's "Time and the Art of Living" is about how we exist in time, and the role time plays in our lives, for better if we make productive use of it, or for worse if we ignore it. Not a self-help book, it is nonetheless a book that I come back to every several years, both for its accessible erudition and for its suggestions for giving shape to your life in time. Highly recommended.



2. This book reminds me of ancient moral philosophy. It's intelligent thinking about life, with a practical emphasis: how to enjoy your life and live well. It's quite thoughtful and original, yet not systematic at all, usually overconfident (kind of forcedly profound), and occasionally even ridiculous. But always relevant and stimulating.
   
   It's more thinking about time, or our experience of time, than you'd think is possible, unless you'd bothered to fight through Heidegger.
   
   The value of the book is its creative thought about life. This book will make you think about your life. If you're thoughtful, you'll disagree with some of the author's opinions, but there's some gold in here. I give it five stars for stimulating valuable thoughts, five stars for content (despite some flaws), and five stars for the genre: we need more intelligent, thoughtful books about living well.



3. I recommend that everyone read this fine collection of meditations on the practical use of time in daily living.
   
   A pleasurable read.



4. A friend gave me a copy of this book more than 10 years ago and I keep "losing" my copy to friends. The book is full of wisdom and is wonderfully written. I probably have read the book a half a dozen times and have read selected passages more than a few dozen times! The "Achievement" section has been particularly valuable for me.



5. I didn't know that thinkers of his class still existed. This is a sterling collection of meditations on life's essentials.

5 comments about Faster: The Acceleration of Just About Everything.

1. This book has a lot of insights about various ways in which the ' pace of life and learning' have since the Scientific Revolution accelerated. In other words it is a book which gives one much to think about.
   The problem is that it also suggests that given the vast increase of information available to us, the vast increase in 'possible alternatives' for our attention, that we will probably have our minds moved away from the insights so rapidly as to not even absorb them.
   The obvious reply to such an intense barrage upon our consciousness, is to withdraw. And when we withdraw and close out all that is accelerating around us, we begin to try and make a pace and story of our own within ourselves.
   The faster we are forced to go, the slower we may need to go.
   I think a companion volume , or perhaps a contradictory volume should be written on all those human activities which might be aided by our ' going slower in them'. And along with this volume should be advice and recommendation of how to keep out of our life these seemingly endless intrusions which disrupt our living by our own rhythm.
   "Run slowly, slowly horses of the night".



2. Gleick would like us to feel that everything, EVERYTHING is going faster. Ultimately, whetever you are doing now, it will happen faster tomorrow.
   
   Sure, life is getting faster, but that's not the ultimate goal. People want to do MORE, they do not want to simply go faster.
   
   To ignore the need for more is to miss the entire point of why we want to do some things faster: so that we have the leisure to do other things more slowly! I would like to finish my work faster so I have more time to cook a gourmet meal. I like to commute via bicycle so I can combine my workout and commute, but I certainly don't rush!
   
   This book has a lot of anecdotal data, which is all very interesting, but doesn't amount to much. Some of the individual chapters give very detailed analysis of specific people or technologies, but Gleick never pulls it all together.
   
   In short, interesting data, but not enough to support his position. And certainly not nearly enough to appease a skeptic.



3. I obviously did not conducting enough research before buying this book. I am seventeen and this was an easy read, but I was hoping for and expecting a philosophical examination of our speedy lives. Instead I was bombarded by semi-interesting, useless facts about how our world has been struck by "hurry-sickness" and how everything has been accelerated (a fairly obvious fact).
   
   If you are consious enough of our world to buy this book (because of its title) for yourself, it will not raise you conciousness with any deep philosophical questions or with any solutions. The only people who will benefit from this book are the ones who will never buy it for themselves. Therefore I believe this book is basically useless and slightly boring.



4. Jam-packed with information and covering subjects that range from Richard Feynman's observations of theoretical physics to the rise of MTV, this book reads, well, fastly. I got a kick out of it and learned a lot. It has a very large number of chapters which are not always that closely tied together, but maybe an obvious point is that that is the intent of the author, to make the book read like modern Western society, with information flying at you from all directions. If so, that may make the book a little harder to get in to and less conventional in style, but it also makes it more original, and in a sense, more logical because it is consistent with its own theme. Author of Adjust Your Brain: A Practical Theory for Maximizing Mental Health.



5. Having read Chaos, I was surprisingly disappointed with Faster. Gleick seemed to want to write about so many things, but never really had much more than a few short factoids about each. I was rather disappointed to find whole chapters of a topic comprising less than FOUR pages of text. Yes, this book is a fast read. So, for the person who seeks notches on his bookshelf, this is certainly a book for you! Of course Gleick discusses some very intriguing items concerning time, but unfortunately his execution falls a bit short of his other work.

5 comments about Supercontinent: Ten Billion Years in the Life of Our Planet.

1. Based on the subtitle of this book, I was expecting details on the changes in the earth's crust/continents over the last 10 billion years -- a very interesting survey that would be! However, the author begins with a parable on what an alien visitor would see from outer space, suitable for teenage readers, after which the bulk of the book is a survey of the history of plate tectonics. This survey focuses on the individuals involved, jumping back and forth between them, and offers little real information. It is not particularly scientific but would instead be a history of the research, with bios of the scientists/philosophers. I ended up skimming in order to find the kind of info I was looking for. Also, to note, the illustrations don't have captions, so you aren't entirely sure what you are looking at or where/why it applies to the text.



2. "Did the Earth move for you?", asks the voice beside you. Well, yes. Because that's what it does. All the time. The continent you live on used to be someplace else, and far away from where it is now. Your home ground has even been part of a greater landmass known as a "supercontinent" - and will be again. Hence, the title of this book. Ted Nield provides us with a fine account of how we came to learn about these movements. He has brought together the years of research tracking where the rocks have been and where they are likely to go. He likens the movement of continents to a dance of landforms - a "Grand Quadrille". A fine synopsis of the history of geology and its compelling figures - scholars who had to project what was known in their time back into a distant past.
   
   Earth has been a busy place for the past four billion years, and it hasn't stopped to rest. We speak of the "firmness of the Earth", but that phrase is a sham. The key figure in this story is the great supercontinent of Pangaea that began breaking up 250 million years ago. Assembled from previous continents that had once joined and also separated, Pangaea's breakup into places we live on today have been traced in exquisite detail. The matching of rocks in places separated by wide seas provided the clues. In fact, as Nield relates, it was the vast Atlantic that bears the responsibility for Pangaea's fracturing to form the basis for the continents we know today. The author explains how the continents have been engaging in a Grand Quadrille and will continue to do so - for another five billion years, at least.
   
   The progenitor of the idea of "drifting continents" was Alfred Wegener. Using maps to show how western Eurasia and Africa matched the east coasts of the Western Hemisphere, Wegener proposed they had once been joined, but had pulled apart. He couldn't provide a mechanism for the movement, and his idea was rejected - most notably by the geologic "establishment" of the United States. Rejection of the proposal was so strong there that one British geologist described it as "regarding the Declaration of Independence as retroactive to the Palaeozoic". Continents formed separately and remained so through time, it was thought.
   
   However, one US dissident, Reginald Daly of Harvard, had been in South Africa, encountering the work of Alexander du Toit, who noted similarities in rocks of the Great Karoo and South America. That discovery, enhanced by some detailed measurements in Greenland, suggested that movement was occurring. It took a war and the hunt for submarines to reveal what prompted continental movement. An Irish geophysicist, John Joly had already postulated the mechanism, heat from radioactive elements deep in the Earth required escape. That venting pushed the softer areas in the Earth's crust around. Sitting atop that stirring material, the continents track the flow patterns of the heat.
   
   In moving, the continents encounter each other, joining, fusing and establishing mighty landmasses that break up again. Nield skilfully describes the mechanisms and the people who have read the rocks to understand how they work. Beyond Pangaea, for example, the author cites the work of Mark McMenamin, who proposes a yet older supercontinent, Rodinia. Rodinia's importance in the history of the Earth is that it was probably the extant landform around which complex life, after over 3 billion years, finally emerged. Nield's skill in presenting all these complex ideas and their significance never wanes throughout the book. He's achieved a fine summary of the history of modern geology, supported by a collection of portraits and some line drawings. The emphasis on Pangaea is slightly overdone, but his pointer to Chris Scotese's web page of geologic ages more than overcomes that small limitation. An excellent overview. [stephen a. haines - Ottawa, Canada]



3. This book tackles the great subject of the geologic history of the Earth from the vantage point of plate tectonics. Along the way, the author writes compellingly of the origins and development of life and the history of our atmosphere. He also gets side-tracked in biographies of some key geologists in the Continental Drift controversy as well as a light-hearted discussion of fictitious 'Lost Continents'. Luckily the book is organized in such a way that these digressions can be skipped if desired. My main objection in this book is the lack of good and relevent illustrations and maps. At the very least, a detailed stratigraphic chart relating geologic periods to continent-building and other events would be helpful. Also, maps detailing the assembly and disassembly of the supercontinents would greatly enhance his narrative of these events.
   
   In many ways this is a wonderful and informative work. Paradoxically, it is not an easy read in the most interesting sections but it is well worth the effort.



4. It's interesting in a sense that if it had been someone other than Neild writing this book, I probably would have given it five stars. As it is however, the presentation of the subject matter is at times vague and at other times condascending. Science is always evolving as new ideas are put forward and old ones become obselete. As such, there's no need to criticize old ideas, even if they've been rendered null and void.
   
   The science is still good though, so I'd recomend picking this book up.



5. In this remarkable book, the author touches upon just about everything regarding long lost continents: how the idea of a supercontinent came about, ancient and not-so-ancient myths (Atlantis, Lemuria, Mu), why continents cannot simply sink, highlights in the lives of some of the individuals involved and, in particular, the fascinating science. After discussing how the existing continents are moving relative to each other (continental drift) and how they will likely collide in the distant future, thus forming another supercontinent, he discuses the supercontinents of the past. In so doing, the reader is treated to a history of the earth and how it works, brimming throughout with scientific facts, principles as well as theories and the evidence that supports them. The scientific processes involved and the dating techniques that are used by scientists are particularly well explained; this is not surprising given the author's credentials. The writing style is clear, elegant, authoritative, often witty and always quite engaging. As a result, this is a book that can be enjoyed by anyone, although science/geology buffs may be the ones that would savor it the most.

5 comments about Time and Eternity: Exploring God's Relationship to Time.

1. Willaim Lane Craig describes and defends his view on God's relationship to time, giving arguments for and against both temporal and timeless existence for God. Craig concludes that there is better reason to think God is temporal. Then Craig defends his the A theory of time against the B theory. Craig deals with many interesting, difficult, and hard to understand theories in this book, but makes it as easy as it can possibly be made for a popular audience. (And, given his lengthy discussion of relativity theory, this was no doubt not easy). Anyone who reads this book will come away with a much better understanding of God's relationship to time, and time itself, then they had before they opened it.
   
   The only drawback is that God's relationship to time is not a huge theological/philosophical topic, and therefore, this might not be a high priority book for many people. I concede that, but then say that for those who wish to learn more about it, I highly recommend it.



2. Dr. Craig does a splendid job of tackling a very complex subject, which is really beyond human capacity. Maybe that is why many of the arguments he presents must be looked at several times to truly understand his meaning. Just glossing over the text will provide many holes in your grasp of these concepts. Some grounding in physics is really essential for understanding. Otherwise it is a good read, but do not expect to read it quickly.



3. Bill Craig does an excellent job comparing the various views proffered by philosophers regarding the question of the nature of time. He explains the A and B theories of time well. As an A theorist, he considers the 'tensed' nature of time as the most 'common sense.'
   
   Briefly, the A-theory is that what is past is gone forever and what is future is yet to have happened. B-theorists believe time is dimensional and exists as an all-encompassing whole. A being outside of time, on B-theory could interact with any point in history as the present.
   
   Bill goes on to expound upon the nature of God's relationship to time. Since God is considered unable to interact with his time-bound creation from a position outside of time, Bill believes that after the moment of creation God himself became time-bound. So on Bill's view, "prior" to creation, God is atemporal and after creation God becomes temporal.
   
   He has been criticized for compromising God's immutability with his position, but he explains why he disagrees with his objectors. I personally believe the premise that God is unable to interact with his creation from a position of atemporality is a flawed premise. Hence I prefer the B-theory.
   
   Nevertheless, even though I disagree, Bill's treatment of the issues is very thorough and well thought out. I'd recommend a potential reader also read Paul Helm's Eternal God: A Study of God without Time to gain two perspective on the issue.



4. This is a well referenced book and gives much information. However, don't expect to find answers. I'm not a philosopher so qualify my comments accordingly. In my opinion the author sometimes uses uses terms loosely and even inappropriately to reach his conclusions. My disagreement with him made it a very stimulating book to read and helped clarify my own thoughts.



5. When you're religion provides you with the "answers" and your audience shares your beliefs, all you have to do is write persuasively; just as long as it kind of "makes sense". In total disinterest of what the truth may be and declining to ask any philosophical questions with substance, Craig makes endless assumptions that echo tradition evangelical Christian theism in order to convince the reader God must exists. This book, Time and Eternity, felt more like a sales pitch for the God Theory then an actual attempt to analyze time. Throughout the book the word "He" is casually capitalized in reference to God, which is a good representation of the bias view this book pumps into its ideology of time. Dodging well understood theories and the opportunity to through something new into the hat, this book focuses on patching holes in the shortcomings of religion in reference to time. If you are genuinely interested in learning about the idea of time, it would probably be best to read a book written by someone that doesn't claim to have all the answers. Einstein didn't have the answers or an agenda, he observed the universe and though he was on to something and wrote a few papers about it. That's science, not this. If you rather not leave the realm of religion go to your church and asking the minister what time is. You'll get the same answer and save yourself a few days of reading.

5 comments about The End of Certainty.

1. If you want a simple, elegant, responsible, well-informed book on the origin of the macroscopic arrow of time and on how time-revesibility at the microscopic level resolves many of the quantum paradoxes, read Physics Prof. Victor Stenger's "Timeless Reality". You will get much more out of it.



2. I did buy this book some time ago and then I was fascinated. I studied the basis of his theory, but unfortunately, Prigogine passed away recently, before I can discuss with he some topics in more detail.

   The greater part of the book is written in a natural style, but some sections are highly mathematical even for the majority of scientists! This mathematical presentation has a curious explaining. There are several version of Prigogine's theory, but the first versions had been "abandoned", and then Prigogine details the new approach: "Star-unitary theory for LPS outside of Hilbert space".

   An earlier reviewer said that the book provides a solution to three of the most important problems in science: (1) Time's arrow. (2) The measurement problem in QM. (3) The existence of freewill. Precisely, I am working in those and other questions, and I do not believe that claim was completely correct (and perhaps Prigogine believed the same, because in his last communication, said me "The questions that you ask are very difficult."). In my opinion, the novel theory is conflictive both in mathematical and physical details, but I consider that, at least, the aim of the School is correct one. Irreversibility and uncertainty are two fundamental features of our universe. I see that orthodox physics (including particle physics and the so-called String-M theory) is incorrect and/or inapplicable. I believe that, whereas other "popular" books (The Quark and The Jaguar, The Elegant Universe, etc.) should be "relics" in 21st century physics, Prigogine's book will be then a basic work.

   The contributions of Prigogine's physics to the understanding in other disciplines, as chemistry, are not clear. In fact, I believe that the impact of recent Prigogine's ideas into fundamental chemistry has been "insignificant", because his revolutionaries ideas in physics are an outcome of their previous chemical investigations (Nobel Prize for Chemistry). For example, in his complex spectral theory, energy is an imaginary quantity, and this is in direct conflict with standard quantum theory postulates. However, in theoretical chemistry, one always defines a transition state by means of an imaginary frequency. As said Prigogine in a recent Solvay conference, "all of Chemistry deals with irreversible processes". I cannot say the same of physics.

   The book is very good one, but I disagree in one point. When one writes a scientific paper for publication in a specialized journal (as Physical Review), one can write about everything. Referees and other scientist can either accept or reject your work in scientific grounds. When one writes a popular book for non-expertises, one must be the most "neutral" possible. If this is not possible, one must to "alert" to the reader. This book is not neutral and, in some restricted sense, shows several theories and ideas as been of broad acceptance or current use in science. Of course, this overemphasizes the scientific status of the so-called Brussels School and minimizes the importance of other interesting points of view. In my opinion, this is not a correct attitude. For example, the "diagrammatic" method developed by Brussels School in the 60's (and illustrated in the book) is broadly not used by scientific community. See, for example, "Nonequilibrium Statistical Mechanics" by Robert Zwanzig for a view in more standard formalisms. In addition, I also must say that some previous Prigogine's ideas in dissipative structures, kinetic potentials, etc. are not standard, and other, as the "universal" criterion of evolution (following production of entropy), was experimentally shown to be false. Of course, other contributions of called Brussels School are simply impressive, for example the extension of scattering theory of particle physics to more general situations of chemical kinetics. Effectively, you have read fine, orthodox S-matrix of "fundamental" physics can be derived as an idealized asymptotic version valid for typical accelerator experiments! I am sorry, but I must said that Chemistry is not applied QED.

   Conclusion: The book describes an excellent philosophical view in a "new" physics, and for this reason it may be a central piece on your collection. Nevertheless, I consider that the scientific way proposed is a little conflictive and some mathematics may be modified!




3. Reading this "popular science" book, written by one of the greatest contemporary chemical physicists, was both difficult and satisfying. To avoid a fit of sycophancy, let's just say that I wish I had it when taking my postgrad Statistical Mechanics class. The only negative thing I can cay about this book is that the discussion is somewhat eclectic; it often oscillates between almost trivial philosophy and very high-level, cutting-edge science. It is not clear what the reader is expected to know before starting on this book. That said, if you can work your way through it, you will likely come out with a new understanding of non-equilibrium statistical mechanics and the physics of complex systems.



4. by the late Nobel Laureate on the controversial issue of time's arrow. It's not clear he succeeded but his passion was never missing. He has consistently held in his books that nature is probabilistic even though his explanation of the 2nd law of thermodynamics, that entropy can only hold constant or increase in an isolated system, has evolved. (For instance in acceding to Frank Tipler that gravity breaks invariance.) Much of his motivation seems to have been in sorting out why Boltzman and Gibbs failed to satisfy the science community that their statistical physics explained the 2nd law, due to reversible classical equations and Poincare recurrences. However in order to make his probabilistic argument he may have created a loophole. He points to the Langevin equation as an irreversible equation with noise (friction) and he says Poincare should have connected nonintegrability with irreversibility and most dynamics are nonintegrable. However everyone agrees some (simple) systems are reversible (pendulums etc) so how can all of nature be stochastic? Maybe because the noise terms tend to but never go to zero? However in addressing the arrow of time he suggests gravity which is ignored in thermodynamics as are all interactions; but this explanation is also used by others in deterministic models. So it may never be provable who is right; but if his loophole is real I think there may be a simpler explanation.
   
   Statistical entropy in all of it's variations is an excellent inference tool but it is about an observer's measurements and not underlying properties of the system being measured (frequentist approaches come close but usually have to extrapolate). In this case Poincare recurrence maybe non-physical, a mere statistical fluctuation with no actuality. (Prigogine says it is false because he introduces new microscopic dynamics, I'm just saying it may not arise in reality but only through statistical assumptions which depend on observer uncertainty.) I agree with the explanation at the website secondlaw.com that the thermodynamic explanation of entropy is fundamental as it is a measure of energy diffusion, and not randomness or uncertainty as the tool of statistical entropy would imply. In this way the 2 approaches are not contradictory; the statistical is merely a measurement tool for observers while the thermodynamic is real dynamics requiring no observers (ice melts, water crystalizes etc long before man was around). The current argument in wikipedia that statistical entropy is considered more fundamental because the others can be derived from it is silly; there are many types of subjective entropy measures, the basic frequentist vs Bayesian approaches, there is volume entropy such as for measuring expanding gases, configurational entropy such as for crystals etc; however there is only one thermodynamic entropy, Clausius's dS = <>q/T (for reversible systems; calculations change of course with potential variables of volume, pressure and temperature). If anything this should be viewed as fundamental as it is a direct measurement of the physical movement of heat. One should not confuse information theory and measurement techniques with real underlying dynamics. When some authors say 'entropy is not a property of a system, it is a property of our description of the system' they are referring to statistical entropy measures and not real thermodynamics. As Prigogine says 'irreversability is not just in our minds', that it applies to nonintegral systems identified by Poincare but not the connection. The very same wikipedia current description, possibly by a different author, accedes the point: "The problem with linking thermodynamic entropy to information entropy is that in information entropy the entire body of thermodynamics which deals with the physical nature of entropy is missing...information entropy gives only part of the description of thermodynamic entropy. Some, authors, like Tom Schneider, argue for dropping the word entropy for the H function of information theory and using Shannon's other term 'uncertianty' instead."
   
   
   If Boltzman had accepted that his equation was not fundamental but an inference tool then most of the debates would likely not have arisen, including Prigogine's criticism of an excellent tool that did not deserve to be criticized on that basis. However what he has done is to show mathematically how irreversibility can apply at the microscopic level for nonintegral systems (in agreement with macroscopics) due to non-local persistent interactions but has to be measured statistically at the level of ensembles and not individual trajectories. This is quite a feat even if controversial. Nevertheless the standard entropy calculations apply for equilibrium systems and the arrow of time is still mysterious though possibly linked to gravity as he says. It would have been nice to see some discussion of entropy of non-equilibrium systems for which there is no universal agreement. For instance it is said that 'the rate of change of entropy with time for a nonequilibrium stochastic process is always positive.' [B.C. Bag; the following references are also available on the net with a simple author search.] This might suggest he already solved the problem and gravity is not required? But-
   
   R. Metzler et. al. say 'Prigogine introduced novel microscopic laws which are irreversible with time. One reason for this ongoing discussion is the absence of rigorous mathematical proofs of irreversible properties in the thermodynamic limit...ensemble averages do not give a basic explanation of irreversible properties, since they contain an average over infinitely many trajectories. Ergodic theory does not help either, since it needs time averages over infinitely many trajectories...In this model we introduce a model with deterministic time reversible dynamics which can be analysed in detail...The Poincare return time is known exactly...' However this takes us back to the usual complaints about statistical fluctuations. [Is there a real arrow of time if everything is eventually reversible?]
   
   Castagnino and Lombardi have developed an interesting approach to the question of the arrow of time. [Clearly Prigogine failed by his own admission and his gravity conjecture!] 'In fact time reversal invariant equations can have irreversible solutions. [e.g. the pendulum is time-reversal invariant...however the trajectories...are irreversible...]...The traditional local approach owes its origin to the attempts to reduce thermodynamics to statistical mechanics...[however] only by means of global considerations can all decaying processes be coordinated. This means that the global arrow of time plays the role of the background scenario where we can meaningfully speak of the temporal direction of irreversible processes, and this scenario cannot be built up by means of local theories that only describe phenomena confined in small regions of spacetime...the geometrical approach to the problem of the arrow of time has conceptual priority over the entropic approach, since the geometrical properties of the universe are more basic than its thermodynamic properties.'
   
   Obviously the debate continues. While Prigogine may not have solved the arrow of time, his work on correlations is important as these are assumed away in classical physics but they are critical to life!



5. This is one of the best books which I have ever read in my life.

5 comments about Sundials: Their Theory and Construction.

1. I have read and viewed the major English language texts on Sundials. These being 1.Waugh, 2. Mayall & Mayall, and 3. Rohr.

   The Waugh text has good, mostly clear, intructions and gives both graphical and equation based methods of constructions. Mayall and Mayall perhaps has better graphical constuctions but Waugh excells in the variety of tables in the appendix. Waugh also has the clearest explanation of determining the declination of a wall. This is very important as many buildings are aligned along magnetic north (& south & east &west) rather than true north ( south etc...).

   A shortcoming of the almost every book including Waugh, is the lack of clear instruction on how to draw other types of hours. Most importantly of these interesting alternatives types of hours are babylonian and Italian hours. These hours are still useful today. So far I've only found the Rohr text to have any attempt of explaining how to draw these lines. However the Rohr text simply doesn't match the clarity and breadth of Waugh and Mayall and Wayall.

   Waugh (and Mayall and Mayall) both could do with an update on trigonometry. With the easy availability of scientific calculators, the need for log versions of equations and the use of things like "cot" functions is not needed and simply makes the calculations clumsy to perform on a key pad.

   The book by Cousins is an excellent higly detailed text if you can get it, but it seems to be out of print. It is useful if you really want to get into the maths of spherical geometry and it wouldn't be the best book you'd want to read first. It makes you appreciate the wonderful elegance of the graphical solutions but it may convince you that it is all too hard when it actually isn't in a practical sense. Just about anyone can make a simple sundial.

   The text by Rohr also has a good section on how to do hour lines on just about any shaped surface (bowl, sphere, plane etc..) if you have a rod for a gnomen. This is about the only strength of this text over the others.

   So to conclude Waugh would be the best first text, very closely followed by Mayall and Mayall, then Rohr. The text by Cousins is excellent but at a much higher level that isn't needed for the construction for the standard types of dials.




2. No other book, as far as I know, gives such clear detail about making your own sundials. That word seems so narrow; Waugh covers much more of solar time-telling than just dials. One thing that amazes me is his passion. He writes with clear pride about his own sundials, good to within (he says) ten seconds!

   This book covers graphical or analytic techniques for laying out sundials on just about any surface that doesn't move, horizontal, vertical (facing any direction), slanted, or even the ceiling. He also discusses the movable kind, like a "shepherd's dial". It has nothing inherently to do with sheep, but can be used anywhere, even without knowing true north.

   The historian may be disappointed. This is not a catalogue of sundials through the ages, although bits of history are scattered throughout. In one sense, though, this is a view into the time of its writing (1973). A modern reader, with access to modern calculators and computers, will be amused if not puzzled by some of tricks used to make hand computation more feasible. I don't know anyone any more who multiplies by adding logs, and the circumlocutions around negative logarithms look positively quaint. The only real flaw in this book is its systematic omission of half the world: the southern hemispehere. It wouldn't have been so hard to add just a paragraph or two about sundials that work "backwards".

   Although this book celebrates the craft and art that can go into a sundial, its real value is technical. This book gives the essential methods for the functional side of a solar time-piece; bring your own artistry.




3. I learnt a lot from this book and the one by Mayall. I strongly recommend you to purchase this if you are looking for technical details on sundial construction. My eagle eye picked up some spelling errors but none that were too serious.



4. The book is very good and easy for everybody to learn about sundials, I indicate the book as a great product.



5. This is the book that finally helped me make a simple, horizontal sundial with paper, pencil, a protractor, a little tape, and a pair of scissors. A great deal of the mystery of making a dial was revealed to this non-math type thanks to this book.
   
   The excellent description of the many different ways one can create the same dial is part of what makes this book superb. There are different techniques for laying out the hour lines, and I sometimes find one method easier than the other. I can try more than one method too. This author understands and respects each of these methods and his treatment of each is certain to make one or more of the methods understandable even to me. The construction of the gnomon was also easily explained.
   
   Of considerable value to me are the tables in the appendix. These made drawing out the simple horizontal dial for a latitude of about 38 degrees very simple. I took my little dial outside, leveled the simple instrument and I was very pleased with the results of my first attempt. I must give most of the credit to Albert Waugh.
   
   I'm looking forward to making my own polar dial and noon marks thanks to the information in this book. Indeed, I will put some other texts to use as well, but this is the one book that helps make these things approachable, and even helps one to better understand the content of more modern texts that are now available, especially in Cyberspace.
   
   I do agree with another reviewer that little mention was made of navigation in this work, thus the importance (even today) of the solar compass is understated. This book was also published in a day when more photographs would have been too expensive, although the illustrations and photos in this volume are still considerable for the time (1973), and well chosen. I have myself seen the dial at the still functioning and historically important Brunton Parish Church in Williamsburg, VA.

4 comments about Aztec Calendar Handbook.

1. Grammatical aside, there is no other treatise on pre-Columbian America and the Aztec Calendar as complete, concise and thought provoking as this one. I didn't notice the grammatical error until the fellow from Tejas spotted it. I was too amazed at having my perception of Native America shattered. After reading many books on the Aztecs, I bought this book and was favorably impressed by the depth, continuity and treatment of the entire subject matter. There is so much information in this book its astounishing. The bibliography contains over 200 sources. Direct eyewitnesses from the 16th century are quoted. The Time-Line is great. I will be referring to this book for years to come.



2. This book is clear, non-technical, and easy to read and understand. People interested in the subject will find it useful.



3. Tlazo'camati, my book came nicely packed & secured and in no time I had it in my hands. Great service. Thank You.



4. This book is the first of its kind. all in one book. before you would have to purchase several books. thanks to the writers research you only need this one book. i recommend if you are studying the calendar. you will not be disappointed...!!!!!

5 comments about About Time: Einstein's Unfinished Revolution.

1. About Time discusses twentieth century developments in theoretical physics and their impact on our notion of time. Davies is a well known and prolific Australian science writer. I offer the following thoughts for potential readers.
   
   Aimed at the general reader the book does not require a detailed knowledge of physics or mathematics. In light of the counter intuitive nature of modern theoretical physics, however, the uninitiated reader may require a little effort to get the gist of this intriguing but esoteric topic. Given the broad scope of material addressed in the text the time spent on each issue is relatively limited.
   
   I concur with previous reviewers that the book is generally quite readable - Davies' technique of using a hypothetical skeptic as a means to highlight certain issues may strike some as awkward (that was my impression). From an overall stylistic perspective, however, Davies has improved significantly from his earlier efforts and become a solid writer.
   
   The author does a nice job of discussing relativity and some of its implications. For instance, his handling of the twins paradox is among the best I have come across. I agree with Davies that there is solid empirical evidence to support time dilation - his transition from this to a tenseless view of time, however, seems premature - or at least insufficiently argued. Indeed, many of Davies assumptions regarding the nature of time, though interesting, will likely not be convincing to those who do not hold his narrow verificationist view of knowledge.
   
   I found the latter part of the book that discusses highly speculative issues such as time travel to be of limited value. At this point much of the thought in this area, though wonderful to ponder, is largely unstructured and untestable - more science fiction than science. Probably the two biggest challenges facing About Time, however, is it dating (a lot has happened in the interim) and the increased competition in this genre of writing.
   
   Overall, it is not a bad book. There are, however, better options available to readers interested in this subject matter - Greene, Singh and Ferris are authors worth looking at.



2. After eight years in the waiting the CERN Hadron collider is set to resume testing in 2007. In so doing it will -- according to noted physicist Ed Witten -- have an opportunity to test some of the more gross predictions of cosmic string theory and in so doing perhaps re write notions of space and time itself.
   
   That being said, Professor Davies book is up to his usually high standards of scholarship and communication in discussing that most pivtol of topics: time.
   
   From recounting speculations of ancient philosophers such as Augustine to telling the modern story of how we are better understanding time to his own speculations, Davies does a wonderful job of briefly recounting the material and making it accessible to the layman.
   
   Well worth reading, but definately keep your eyes peeled for events at CERN.



3. This over-simplistic physics account which holds that universal time and entropy are reversible and that Poincare's recurrence theorem disproves the 2nd law of entropy increase in isolated systems (and Boltzman's statistical mechanics) ignores the fact that physics equations are idealizations and that mathematical equations are tautoligies that do not define direction or cause. These arguments generally ignore real world effects such as friction, noise, chaos (e.g. the 'many body' problem for gravity) and non-linear effects and correlations etc.
   
   For instance the wikipedia description of Poincare's recurrence theorem points out that environmental noise and chaos alone can break the idealization. In addition chaos can cause entropy increase in both time directions (e.g. P. Cipriani). Various authors (with articles on the net) have pointed out that for non-adiabatic processes, 'the natural evolution of entropy is towards larger values because the natural state of matter is at a positive temperature' (M. Campisi), and only in adiabatic classical mechanics are energy and entropy both conserved and time reversible (e.g. Silverberg and Widom). In addition 'One of the basic postulates of the classical statistical physics is an assumption that the particle's interaction range is considered to be small compared with the system size. If this condition does not hold the internal and free energies, entropy etc are no more additive physical quantities... the Boltzman relationship between the entropy and the statistical weight is not any longer valid. The non-extensive systems are common in physics- gravitational forces, Coulomb forces in globally charged systems, wave-particle interactions, magnets with dipolar interactions etc.' (Apostolov et al, April, 2007).
   
   Essentially all of Davies' book is concerned with the idealizations and so most of the paradoxes he describes are not real and he has not updated the debate since Boltzman from the early 20th century. His analysis of the 'twin paradox' from Einstein's early relativity of the same era is also dated (even though his book is a century later!). This paradox about the twins each measuring each other's clocks with telescopes appearing slower to the other when one takes a fast spaceship into space and yet one returning younger is readily dismissed by Davies as the effect of the traveller's acceleration, is in fact not fully accepted. For instance S. Kak's recent article succinctly describes the actual situation:
   
   "There exist many different 'resolutions' to the paradox [which] are not in consonance with each other. The slowing down of all clocks and processes - including atomic vibrations - on the travelling twin cannot be laid on the periods of accleration and turning around during the journey, since they can, in principle, be made as small as one desires... Einstein's own 'resolution' in 1918 (13 years after Davies says he reolved it!) which was an attempt to counter the criticism related to the paradox until that time, used the gravitational time dilation of the theory of general relativity to explain the asymmetrical time dilation of the travelling twin. This explanation is generally considered wrong and is different from the other 'resolutions...In this article we present a new principle for the identification of inertial frames in a matter-filled universe [assumed away in the other idealizations!] that allows us to easily resolve the twins paradox. The principle implies that the identification of a frame as being inertial depends on whether the universe has spatial isotropy with respect to it. This is equivalent to determining the motion of objects against the background of distant stars."
   
   One might describe this solution as 'Machian', whose central principle was that a particle's mass was determined by all of the other particles in the universe. There has been some evolution of this (Mach's general) theory which has gained some popularity and some authors have shown how it can be adapted to conform to any gravitational theory including Einstein's relativity. There are also some good books on this subject for sale on Amazon.
   
   So once again when one does away with the idealizations and enters some reality into the models one can resolve many of the so-called paradoxes.



4. This, as the title states, is a book about time; all the possible aspects of time, from that of the Greek philosophers, through Newton's idea of time, to Einstein's relativistic view of time and beyond. The book is a blend of philosophy, physics and physiology, but heaviest on the physics aspects of time. Everyone thinks that they know what time is, but on closer examination it is not so clear what time actually is. Is it an illusion or just the interval between events? Does it flow, or is it only perceived to do so? Does time always run forward, or can it run backwards? What is imaginary time, or quantum time? Did time start at the instant of the big bang? What does time look like in a black hole? How does the brain perceive time?
   
   To the ancient Greeks time was a mystery, to Newton time was absolute and to Einstein it is relative to the observer. All these are subjects (and much more) that are discussed in the book; discussed in a very literate and highly entertaining manner. This is not, however, a physics text, although much of it is concerned with the physics of time. There are no equations and only the results of relativity theory, quantum mechanics and cosmology are discussed, not the details. Nonetheless, it brings time to life (to use the sort of analogy that is discussed in the book) in a way that the details of a physics text cannot. I highly recommend this book to students and to anyone who wants their perception of the most basic aspect of consciousness challenged. Read this book and you will never perceive time in quite the same way again.



5. I liked this book. When I read the first pages, I thought that I had chosen the wrong book, but afterwards everything changed. Here you can find a light and clear review of many aspects of time.
   
   It is not perfect, and some times it is not clear what the author means with "time reversal", etc, even if he tries to explain it several times. The theory about the proximity of Doomsday is also quite weak.
   
   In spite of this, you find a clear view of time as it is currently known by science. I have not found many new ideas, but in general they are well structured and consolidates what you have read separately in many other books. Apart from that, it has good rhythm, and it is easy to read and understand.