5 comments about The Physical Principles of the Quantum Theory.

1. This really helping me to understand more about the Quantum Theory, I think this book is need to be read by everyone who study physic or by someone who interested by physical theory. I have been read this book for several times and I stil never feel bored. I think this book is really interesting. Thank's



2. This book is the standard introduction to - well, to the physical principles underlying the mathematical formalism of quantum mechanics. While it is dated in terms of that mathematical formalism, it has never been superseded in its analyses. Every serious student of quantum physics will encounter it, sooner or later, in the original or in paraphrases in newer monographs on quantum theory.



3. Not really for beginners in spite of appearances, this book sketches Heisenberg's path in discovering the canonical commutation rules of quantum mechanics. After trying unsuccessfully for years to quantize the helium atom via the Bohr-Sommerfeld quantization rules (which attempt Einstein had already explained in 1917 to be hopeless, because the classical 3-body problem is nonintegrable), Heisenberg was finally motivated by the example of relativity (where absolute time had to be abandoned) to give up the assumption that the position and momentum of a point particle are simultaneously predictable. To follow Heisenberg's reasoning the reader must first understand action-angle variables in classical mechanics. With Einstein's 1917 paper in hindsight, the three body problem representing the helium atom energy spectrum was finally approximated semi-clasically around 1990 based on a path-integral approximation to a chaotic Hamiltonian system.



4. I was pleasantly surprised by this book. It uses technical language (which can at times can become difficult), to express the physical context surrounding the development of Quantum mechanics, and deal with the matter at hand (pardon the pun). Quantum theory has a reputation as being difficult, confronting and unbelievable. However this book expresses logically and in detail, the physical principles of the Quantum theory, by the great Werner Heisenberg himself.
   A great book if your thought needs provoking...



5. The only thing mysterious here is how this great scientist has managed to muddle up his own theory in this book to the point where its unintelligible. It takes him a chapter to state that the electron does not have a velocity or a path in the classical sense. And why give this book such a blatant appealing title to lure beginners to pay money for this trash. No examples or end-of-chapter problems either. Read Lev Landau instead.

5 comments about Quantum Evolution: How Physics' Weirdest Theory Explains Life's Biggest Mystery (Norton Paperback).

1. If yours is a less-than-layman's knowledge of the biological sciences, biochemistry, systems theory, quantum electrodynamics, and genetics, fear not. Lads and lords alike will find this meta-disciplinary study entertaining, anectdotal, and edifying.
   
   Spliced with the McKenna brothers' "The Invisible Landscape", 21st Century fusions of science and spirituality start to display their edge features. Interesting commentaries on the early evolution of chemical pathways and autocalytic cycles make this an important addition to the complexity theorist's library.
   
   McFadden provides historical narratives to frame this essay, which make its strangely unorthodox probes into quantum observation within the sub-cellular landscape easier to digest. A popsci background in disciplines such as quatum mechanics, systems theory, and biology will make this a four-five day read. The author's argument is both challenging and controversial, but his case is vacuum-sealed.



2. This is one of the most innovative theories I've encountered since Albert Einstein's proposal of General Relativity (I once recommended this book to one of my buddies and he ended up buying it and making his girlfriend read it). It basically explains the origins of life, evolutionary jumps, adaptive mutation rates, and unprecedented complex processes (especially those whose precursors lacked an independent selection value) in terms of the influence of the inverse quantum zeno effect on the decoherence of chimeric protein sequence superpositions in ribonucleic acids.



3. The authors exploration into quantum physics and it's relevance in evolution provides an extremely interesting view on the possibilities of how life began. Quantum physics was not a discipline that I had much knowledge of prior to reading this book, but McFadden makes clear, easy to understand examples of its most important points. I found this material so interesting that I even reread the book to gain a clearer understanding of the big picture of quantum evolution. This book was very well written and I recommend it to anyone interested in science at the molecular and atomic level.



4. McFadden begins with a discussion of what defines life. He concludes that "directed action" is a key notion. This is something analogous to the appearance of "will" in humans or higher animals. Moreover this directed action takes place all the way down to the microscopic level within organisms. Organisms are characterized by order via directed action at scales large and small.
   
   Prior to presenting the core arguments for quantum effects in life, McFadden reviews evolution and DNA replication. He also looks at the different theories for the origin of life. On his way toward providing his own answer, McFadden next takes a closer look at biochemistry, showing that as you drill down into particular biological functions you find they are driven by directed movements of individual protons or electrons via the electromagnetic force. This puts us squarely in the domain of physics, specifically quantum physics.
   
   McFadden presents his own very readable summary of QM, leaning heavily on the two-slit experiment as a heuristic device. His strategy is to show that quantum measurements are happening at the micro-level in living systems. He gives an example of an enzyme action that ultimately depends on a single proton, which we know must be in a superposition of states absent measurement. So, a living system must be measuring itself. His view is that the classical world depends generally on continual measurement for its manifestation. This discussion leads to the next key tool McFadden wants to use: the quantum Zeno effect (and inverse Zeno effect). This, he speculates, is what is responsible for directed action at the micro-level.
   
   With the review of QM in hand, he returns to a discussion of the origin of life and the question of how the first replicator was assembled (given the extreme improbability of it happening by chance). He theorizes that quantum superpositions could allow exploration of a large space of possibilities at the scale of an amino acid peptide chain. But the chances still seem small of making the self-replicator. However, harnessing the (inverse) Zeno effect could increase the probability. And, once you have a self-replicator, can we assume natural selection can do the rest of the job? No, there is still a big challenge here in getting a simple replicator to build the complex machinery of a cell. Moreover, in computer simulations, replicators tend to generate simpler systems, not more complex ones.
   
   McFadden speculates that if a system on the edge of the classical frontier repeatedly fell back into quantum superposition and took advantage of the inverse quantum Zeno effect, this could have added complexity. Still, we haven't been able to do anything like this in the lab.
   
   And yet, the case seems relatively more compelling that non-trivial quantum effects are being exhibited in living cells (even if they are difficult or impossible to directly detect). To give credence to the existence of these effects one can estimate that decoherence times would be lengthy enough for them to occur in the relevant context. Also, important to note is that it is only coherent systems are sensitive enough to be affected by the weak electromagnetic fields which are known to exist in the cellular realm. McFadden concludes the quantum/classical barrier exists at the sub-cellular level of biology, and that organisms are comprised of "quantum cells".
   
   Getting back once again to the definition of life, McFadden says the cell's ability to "capture" low entropy states to maintain order at the microscopic level via (internal) quantum measurements and the quantum Zeno effect is responsible for the distinctive directed action which characterizes life.
   
   In the final chapters, McFadden first reprises the discussion of the role of quantum effects in DNA mutation and adaptive evolution. Then, he closes with his theory of how quantum effects in the brain may be linked to human will and consciousness.
   
   On the one hand, this book consists of speculation stacked on speculation. On the other hand, each step progresses from features of physics or biochemistry that we know to be true. Between the spheres of quantum physics and the human mind lies the world of biology: I continue to look for arguments and evidence that biological systems have features that can bridge these realms. This book was a fine effort along this line.



5. Perfection in scientific writing achieved by Dr McFadden. Shame I did not have a single lecture with him at University of Surrey.

2 comments about The Quantum Ten: A Story of Passion, Tragedy, Ambition, and Science.

1. This interesting book provides a special view of quantum theory.
   It provides an insight into the origins of the theory based on the personal
   lives of its creators.
   
   The book treats scientific activity as any other cultural activity
   making clear that even the most "objective" of our mathematical theories
   (like the theories of mathematical physics) ought to be seen as cultural
   products within the social and political frame of their conception and
   (perhaps more importantly) within the professional and financial strains
   and aspirations of their creators. This is indeed the case from the beginning
   of abstract mathematical thought in ancient Greece to this day.
   
   There is no deep discussion of the mathematics/concepts of the theory and
   an expert in the theory would certainly not become any wiser as to its
   meaning. However, the greatest service provided by the text is a better
   understanding of the shaky foundations of the theory that was conceived
   as an effective model of reality as allowed by the mathematical capabilities
   of that time and not at all as a "fundamental" theory as understood today.
   The theory emerged as a recipe for understanding experiments with no
   intrinsic limits on its applicability or relevance to other situations.
   
   Young people interested in a realistic view of how real science is done
   rather than idealized, fairy-tale treatments would find this text interesting.
   Interesting but not captivating so four stars.



2. OK, the premise is a noble one. The subject matter is an esoteric one that few people would care to know about. I know equations in a book halve (if not completely reduce) the sales. But for a book that professes to introduce the notoriety of the quantum ten should at least list out one equation for each person that they produced and seriously embroiled in this 1927 Solvay controversy. At the very least explain what the wave function is and what its implications really mean for quantum physics. Please please do not be scared to put equations in a book. I thought I'd see E=hv or
   pq - qp = h/2*pi or schrodinger's wave equation. Sad, sad, sad. I hope she does something interesting in her second edition (if it ever gets to that)
   
   This book has facts that can be gotten out of Wikipedia. It does not say anything new about the physics or the people. No new light on wisdom, knowledge or history I'm afraid. It can all be gotten on the net, sorry to say.
   
   My two cents - rent it at your public library but don't waste money buying it

3 comments about Stochastic Processes in Physics and Chemistry, Third Edition (North-Holland Personal Library) (North-Holland Personal Library).

1. Before I knew of this book, I used to refer to Chandrasekhar's paper on stochastic processes. This book is very physical and tries to avoid unnecessary dry mathematical rigour (replacing it with clear physical insights) Also the physical problems considered in the book to elucidate the mathematical framework vary from fundamental physics to applications. The exercises are essential but otherwise also the book is a smooth reader. The sections on master equation, Focker plank equation and fluctuation dissipation are my favourites.
   
   I used to work in systems biology and now I have changed my focus to biophysics and the book is useful to me still. I was so desperate to get the book that I had to buy it second hand at the price of first hand. I do not regret about that at all.
   
   Regards
   Purushottam
   JHU Chemical Engineering,
   Grad student



2. This is my favorite textbook. It is highly readable; everything is explained very clearly without being verbose, and it is very logically organized. One of the book's best features is the author's commentary on the inappropriate uses of particular approaches or the care needed in working particular problems correctly. These insightful sections are clearly the result of a true mastery of the subject and make easier the use of the book for self-study, in which access to such commentary (from a lecturer) is typically not available.
   
   Although it doesn't read like it, this book is actually quite dense with information. It is not uncommon for me to come across a difficult problem in my work, only to find it solved in here. There are many exercises, all of which are interesting and add to the presentation in each chapter.
   
   I do not have any complaints about this book, and I can not recommend any other book more highly than this for anyone interested in learning more about stochastic processes. Even as a first book on the subject, for readers with sufficient mathematical sophistication I can not think of a better book.
   
   A final note: the changes to the third edition are apparently mostly in the chapter on quantum mechanics. You might consider trying to find a bargain on the second edition if such changes are not important to you!



3. It is a pity that a great book like this is so poorly bound. I bought it some months ago and the pages are coming off the spine. The publishers should do a better job and bind van Kampen's classic as it deserves, specially considering its (unreasonably high) price.

5 comments about Quantum Theory: A Very Short Introduction (Very Short Introductions).

1. This is a short book, and that is its only advantage, unfortunately.

   Granted, that the author is eminent in this field and was himself a student of the great Paul Dirac. However, this book does not sit easily in a series designed to make a subject approachable to the novice. It has far too much esoteric maths than is good for a book of this genre. An ever stronger criticism is the fact that instead of keeping to basic physics ideas such as the double slit experiment (which this book does well!) and then developing the ideas of atomic structure, and the uncertainty principle, it dwells on things like operators and such like.

   If you want a good introduction to Quantum Theory, look no further than the books by George Gamow's "The New World of Mr Tompkins" or "Mr Tomkins in paperback", or, "Uncle Albert and the Quantum Quest".




2. This book does its best, but in the end suffers from something that I think is inherent in the material itself. I did learn a little more about quantum theory from this book, but not much more than I already knew to begin with. And this book didn't really make many of the main concepts any clearer. I don't think is the author's fault, I think it's almost impossible to try to explain these things. Most of the problem, (and similar statements go for cosmology, cryptography, etc.) is that it's almost impossible to explain concepts whose fundamental expression is mathematical language without using mathematics. What inevitably results is some kind of vague, touchy-feely idea of what's meant, but little understanding. And I say this as a mathematician.

   To give just one example, at one point in the book, the author talks about "probability amplitudes", for several pages. The only problem is, he never says what this term is supposed to mean, but he does mention that complex numbers are involved, and other facts. The result after this happens several times is that the reader starts to read entire paragraphs consisting of terminology that's never been defined clearly. The word "operator" is the best example here. It's fine to talk ABOUT operators in indirect, oblique language, but really you don't have a true understanding of what that word means unless you know its precise mathematical definition, or unless you have a clear understanding of the notion of vector space (axiomatically, not "stuff you can add together"). I didn't have this kind of problem with most of the mathematical terminology, because I know it, but the problem comes with the physics -- the physics concepts are essentially mathematical, and trying to explain them without using mathematics is like trying to understand Shakespeare without being able to read English -- you can always give a vague, hazy account, but not much more.

   The book is well-written (aside from an overly-biased presentation of the philosophical aspects), but I think it tries to have its cake and eat it too. It says it's free of mathematics, but this isn't really the case. The whole text is fully of talk about operators, vectors, vector spaces, equations, probability theory, and so on. It's the _symbolism_, not the math, that's missing (except for the appendix, which thoroughly confused me, mainly because terms were introduced without precise definition, and the notation was the physicist's notation, not mathematician's notation...)

   This book was confusing to me, but the reason was because it had too LITTLE math, not too much.




3. I'm thoroughly unimpressed by Rev. Polkinghorne's account of quantum physics. Even though he is technically competent, Polkinghorne seems to get every major interpretation wrong. For example, he thinks Bohr in error to consider free will and determinism complementary. But Bohr's colleague and Nobel Laureate Max Born did say that Bohr's complementarity applies precisely to this situation.
   
   Right on page 1 Polkinghorne shows his tendency to misunderstand. Speaking of Laplace's conjecture, the physicist-turned-Anglican priest writes "In fact, this rather chilling mechanistic claim always had a strong suspicion of hubris about it. For one thing, human beings do not experience themselves as being clockwork automata...."
   
   This is like accusing someone of arrogrance because he said "If I were the president of the United States I would eliminate poverty..." He did say "If," didn't he? Laplace always said this prediction of the future is only possible in principle, but impossible in practice. In fact, in making his "thought experiment" - not a factual "claim," as Polkinghorne thinks - he made two assumptions which he knew to be UNTRUE. First, that such an ideal intelligence exists. (When Napoleon asked him about the Creator after reading his theory of the solar system, Laplace gave this magnificent reply: "Sire, I have no need for that hypothesis.") And second, that this intelligence can analyse absolutely all data at once.
   
   As for what humans "experience," the fact is that not even a frog feels like a clockwork automatum. But what we feel is irrelevant if our belief in free will is due to the unpredictability of our volition, and this unpredictability is due in to deterministic chaos, which leaves no room for free will at all, no matter how irregular we might feel. In fact, no machine can perfectly understand another machine of exactly the same level of complexity, even without chaos added to the difficulty. A machine may be able to understand another of lower level of complexity. The same goes for humans: We may always have difficult understanding ourselves although we may eventually understand simpler organisms. We humans have enough trouble understanding the nervous system of something as simple as a dog. What Polkinghorne should have asked is: What would be the effect of quantum mechanics on this "thought experiment" of Laplace? An honest answer would be: None. Indeed, Laplace did not need chaos or quantum uncertainty to know that his conjecture is no more than just a thought experiment, though a very worthwhile and instructive one.
   
   Polkinghorne puts down other physicists (and auto mechanics in general) by saying "The average quantum mechanic is no more philosophical than the average auto mechanic." Born, however, said that theoretical physics IS actually philosophy. Bohr always said that there are important epistemological lessons to be drawn from the world of physics, especially elementary particle physics. It's as though Polkinghorne has been asleep through all the major developments of the past century. On the few occasions he is awake, he misunderstands and misrepresents. Polkinghorne himself may be no more philosophical than an auto mechanic (maybe even less so), but don't drag people like Schroedinger, Bohr, Born, Pauli, Heisenberg, Wheeler, Bell and Weinberg through the mud with such silly statements.



4. In an introduction to a topic, one expects lots of figures to explain just about every topic. This book, and indeed the entire series, generally has rather few figures. The series also, generally, focuses on the historical development of the topic and not necessarily on the current understanding of the topic. Therefore, the series sacrifices a better explanation of our current understanding to explain who thought what and when. Nonetheless, this book serves adequately in the capacity of a "very short introduction."



5. This pocket-sized, 92-page text--113 pages with appendices and index--professes to be a "very short introduction" to an understanding of quantum theory, to the unseen world that's so many millions of times smaller than even atoms.
   
   It's not at all a bad summary of the field of quantum mechanics, written fairly lucidly, concisely, and with interest, but I'd have to say it's lacking as an introduction to the subject, in that it really does assume its readers are intelligent people with something of a science background. Do not buy this expecting it to be QUANTUM THEORY FOR DUMMIES, because it's still fairly dense and heavy, and not written as clearly or as startlingly as much of Stephen Hawking's stuff. To some readers, this assumption of their intelligence may be refreshing, and it is to a degree, but with a subject as complex and bizarre as quantum mechanics, most non-scientists will need as much help as they can get, help not necessarily to be found in here.
   
   I do have to say, though, that this is a book worth reading, and, then, re-reading. After I read it, I went back through and looked up a few of the more major concepts--quantum entanglement, in which two particles that interact will continue to affect each other no matter how far apart they're separated; Schrödinger's Cat and the idea of a state between life and death, between here and there, between being and non-being; Heisenberg's Uncertainty Principle and how you can't have a knowledge of both position and momentum of a particle; et cetera--and just that brief re-reading was a huge help to me.
   
   The book will teach you a lot about the subject, and will give you a good start toward further educating your knowledge of this awesome and frustrating topic, this topic which has already done so much toward unlocking the secrets of our existence and our universe--and toward confusing everyone.
   
   Its glossary is lacking, its author has a subtle but evident Christian bias, but overall it's a good little book, and I enjoyed it. I recommend it.

5 comments about The Principles of Quantum Mechanics (International Series of Monographs on Physics).

1. As anothers reviewers state don't expect to learn QM from this book -actually I think Cohen-Tannoudji is one of the best for this purpose-, but if you know already some quantum mechanics you'll find a very clear and elegant introduction of the dirac formalism of QM. I like it very much.



2. Quite simply, this is the most important book written on the foundations of physics in the last 100 years. I read this when I was 18 & it persuaded me to pursue a career in theoretical physics. It is still one of the few books in physics that I return to after 40 years.
   Life is too short, so just read the 'Masters' - Dirac is the greatest master of physics in the 20th Century.



3. This wonderful book lays out the thought process by which Dirac's formulation of quantum mechanics, with its much-handwaved-about "bra" and "ket" notation, came to be. Dirac makes minimal assumptions about the reader's prior education (appropriate, since the first edition was published in an age when a thorough scientific education comprised Homer, Virgil, Euclid, and Newton), so there are none of those annoying allusions of the form, "from which, of course, the insights of [famous name X] allow us to conclude that ..." In fact, there are extremely few footnotes of any kind, and they are not needed, as this work is neatly self-contained.
   
   Dirac is marvelously careful in calling attention to the guesses he makes along the way, so the careful reader can see what Dirac's premises are as well as what can be logically derived from them.



4. This book is the basis of Quantum Mech any physicist that respect him or herself should read Dirac because it resembles the origins and gives the best description of QM there can be in this book you can feel the real possibilities of QM I say possibilities because at the time QM wasn't fully developed, or at least as thought through as it is now.
   Either way this is a basic book for anyone intending to study physics I really recommend it.
   
   One thing you should know is that the image given here is the not the real one, you should look at th one given by me, is one taken from the look inside, that has the real cover. But as it is always said you should never judge a book by its cover, even more so if the one who wrote it was the best physicist in the last century.



5. His insight into the physical interpretation of the formalism of Quantum Mechanics has no precedent. Almost every physicist around the world agrees that HE IS MASTER DIRAC, so an insight into his vision of the theory is invaluable.
   
   This is not a didactic book, in fact, in my opinion, it is not even to be considered a text book. Its value concerns the rigorous development of the formalism of QM, as well as a firm base for the understanding of the very principles of it. I'd say it's better for people who have struggling qith the ideas of QM for a while already, that for who are just starting with them.

4 comments about Quantum Transport: Atom to Transistor.

1. For over thirty years, Green's functions have been used to calculate effects in solid state physics. But usually for pure research, destined to be written up in scientific journals. Here, Datta offers some outreach. There is indeed quite a lot of theory presented. But there is a corresponding emphasis on the latest materials fabrication abilities, including the making of nanotubes and quantum dots.
   
   All these have (presumably) interesting and practical applications. So if you want to design novel devices from a theoretical standpoint, the maths tools developed in the text can be very useful.



2. The book is in great condition and was ok for the price. Ad i couldnt find it in any of my university book stores



3. The author (SD) claims that this is a physics book written for engineers. Maybe that explains why, unlike the authors of most physics books written for physicists, he doesn't seem particularly concerned with elegance, concision, abstract generality or showing how clever he is in this book. Apparently, his main concern is to help you understand stuff. Not only that, but he's chosen some very interesting stuff to tell you about.
   
   The narrative arc of the book is to show you how to get from a particle in a box to Ohm's Law, as instantiated in nanoscale transistors. The path to doing this is already laid out in the first chapter, using a "toy" level of analysis. The next nine chapters lay out building blocks for attacking the problem using Green's function (GF) techniques, which are a bit more modern and versatile than the transmission formalism favored in the past (including by SD in a previous book). The whole picture is put together in Chapters 11 and 12, followed by an appendix that shows (albeit quite tersely in comparison to the rest of the book) how the same problem is dealt with using a second-quantization (2Q) GF formalism. The fact many pieces of this arc are repeated at successively deeper levels of analysis is very helpful. So too are SD's "big picture" introductions at the beginning of each chapter, and at the beginnings of the longer subchapters.
   
   Throughout, SD pauses to describe in words and pictures the physics behind pretty much each term of each equation -- a de-mystification that most authors of physics texts seem to avoid as if it were blasphemy. I was especially impressed when SD used these opportunities to allude to some deeper and more general issues, such as how you get from time-reversible equations to irreversible physics. In fact the whole book serves as an applied introduction to non-equilibrium stat mech, a cutting-edge subject usually reserved for abstract theoretical treatment, or the last few pages of a conventional textbook. SD also foregrounds some basic points that are often buried in or missing from other texts, such as that the Schroedinger equations do not explain why atoms emit light, and why "optical" phonons are called that. (This latter point had really bugged me when I took a course in solid state years ago, so while reading this book I re-checked 7 or 8 solid state texts within reach, including Ziman, and found that only Kittel and Ashcroft & Mermin bothered to explain this point, and so casually (K) or vaguely (A&M) that you'd hardly notice.)
   
   I was especially struck by the book's attention to modeling transistor contacts and how they interact with the channel. In the last few years this has become a big issue in organic electronics, as researchers have found that many aspects of device behavior were far more dependent on the contacts than they'd previously appreciated (kind of a let-down after going to the trouble of synthesizing some exotic channel material). That said, though, note that the book's POV is restricted to inorganic crystalline semiconductors, and I don't claim to be smart enough to see how easy it is to extend the book's methods to organic devices.
   
   A couple of caveats. Although my copy says it was "reprinted with corrections 2006", there are still a lot of typos (none too terrible, though). More significant is that many of the exercises rely on your having access to MATLAB or some other math program. If you're not attached to an academic institution or didn't aquire a copy of such a program while you were so attached, those exercises probably will be inaccessible to you (unless you're willing to spring for ~ $10E2.6-$10E3.3 for a personal copy, depending on the program). Contrary to another review, there isn't anything about fabrication techniques, despite brief references to quantum dots and nanowires. And while the blurb on the back cover says "No prior acquaintance with quantum mechanics is assumed," and although SD does start from a description of the Schroedinger equation in Chapter 2, the QM intensity accelerates rapidly from there. So I wouldn't rely on learning the relevant QM from this book. (However, it might be possible to enjoy this book before you've finished a class in solid state.)
   
   For a next edition, I'd look forward to (i) a somewhat less rushed description of transmission formalism in sec. 9.4 (one of the few places in the book where EEs may have a real advantage over others), (ii) a wordier discussion of the 2Q formalism in the appendix, and (iii) a more explicit discussion of Fock space methods, which seem to play an uncredited role in the discussion of multi-electron systems in Chap.3. But even as-is, this is a very stimulating and enjoyable book.



4. All i can say is that either the Amazon service, the delivery time and the item were really excellent, i even got the item few days before the estimated delivery date.
   Thank you

5 comments about The Fabric of Reality: The Science of Parallel Universes and Its Implications.

1. This is a difficult book. Deutsch, a British theoretical physicist, asks scientists to face up to the reality implied by the present fundamental theories of quantum physics and computation. He weaves these strands together with the theory of evolution and a lengthy discussion of epistemology to demonstrate that an improved understanding of the real world is to recognize it as a set of parallel universes. This "multiverse" reality has baffled scientists, who find quantum physics necessary but shy away from the implications for reality. Deutsch probes deeply into how we know anything, how science moves forward, and the reinforcing strands of computer information theory and quantum physics. While the conclusions are certainly counter-intuitive, his evidence is serious. However, the final two chapters will need reworking, as they are based on the assumption in 1997 that our universe would ultimately contract again into a "big crunch." Evidence is now persuasive that continued expansion is our fate, so that his "infinite knowledge" scenario in the final moments of the contracting universe will not occur. Nevertheless, Deutsch's analysis is compatible with those who believe that knowledge (information) is the ultimate reality. On the way, he explores the theoretical possibility of time travel (Possibilities: one way trips into the future, and round trips into the past only back to the time at which time travel technology is first deployed). Personally, I find the parallel universe conclusion hard to envision, but as an explanation of quantum physics it is certainly more straightforward than the unsatisfactory and labored interpretation of the "Copenhagen school."



2. The book attempts to develop a theory of everything based on the synthesis of several diverse approaches in physics, genetics, philosophy and computation theory -- quantum mechanics, natural selection, Popper's epistemology and theory of complexity.
   
   Unfortunately, the central original idea in the book - that of parallel universes - is the least convincing of the four, and probably ultimately unnecessary for any practical purpose. The idea is introduced ( and not expanded beyond a simple example ) using a quantum interference effect: A beam of light if partially obscured by a screen with two slits produces a periodic interference pattern of bright and dark areas. Even if it is known that only one particle of light, a photon, is emitted by the light source, the same interference pattern results. Therefore the photon somehow goes through both slits, even though if measured right at the individual slits in the screen, it is observed only at one at a time. This paradoxical behavior created a lot of discussions in the physical circles in the first part of the century when quantum mechanics was actively developed.
   In the book, the offered interpretation of this experiment is that the universe, because of the photon, splits into two almost-independent copies, apart from being weakly connected by the photon in question.
   It has been earlier suggested that this interpretation, of multiple universes, is consistent with the equations of quantum mechanics. According to the author it provides a better insight into quantum phenomena and thus, bringing a bit of philosophy here, we are to conclude that to the best of our knowledge multiple universes must exist.
   It becomes immediately clear that this approach leads to an astronomical proliferation of universes, which, in my view, should be viewed as a severe drawback of the theory, and which needs to be at least discussed. Most of physical theories are based on symmetries, and the related notion of conservation of energy and other quantities - a sort of embedded frugality in nature. In a computer language, one would rather increase a "count" of the universes instead of making an unnecessary copy, and keep track of the photon probability - precisely what the "old" theory does.
   
   It also seems that this hypothesis of multiple universes is not needed to understand the idea of quantum computing, which is truly very interesting. As an aside, I think it would be interesting to see if a sort of a quantum computer is implemented in biological systems, which seem to operate at the exactly right molecular level where quantum effects are important.



3. David Deutsch's aim in writing The Fabric of Reality is to present a theory that does not relate to one particular subject, but to all subjects: a `Theory of Everything'. To do so, he interrelates quantum mechanics, computation and virtual reality, Popperian scientific method, and Darwinian evolution. One of the unifying themes of the book is his view that science is concerned not with prediction but with explanation.
   
   First, he discusses quantum physics and the existence, inferred from experiment and observation, of shadow photons. So far so good. But having done so, he goes on to deduce the existence of parallel universes - unobservable universes that are similar to but not the same as ours - in some ways connected to ours (how else would we guess their existence?) and yet in others not connected. These unobservable universes he refers to, collectively, as `the multiverse'. He then makes a speculation - unfounded apart from the inferred existence of unobservable shadow photons - that I find difficult to accept:
   
   `While I was writing that, hosts of shadow Davids were writing it too. They too drew a distinction between tangible and shadow photons; but the photons they called `shadow' include the ones I call 'tangible', and the photons they called 'tangible' are among those I call 'shadow' [...] Many of those Davids are at this moment writing these very words. Some are putting it better. Others have gone for a cup of tea.'
   
   Reading those words, I was reminded of Hume's assertion that while it is legitimate to infer a cause from an effect, it is not legitimate then to return and infer new effects from that same cause.
   
   Deutsch's assumption is vulnerable to reductio ad absurdam. By his own argument for the existence of counterfactual or `might-have-been' worlds, a parallel universe could exist - and, if we are to believe the metaphysics of the philosopher David Lewis, really does exist - in which David Deutsch is garbage operative and Mao Tse Tung is an evangelical Christian.
   
   Having brought into being the multiverse, Deutsch continues throughout the book to refer to it as if its existence were an indisputable fact. Much later in the book, he claims, with little foundation as far as I can see, that the multiverse did not come into being until some time `after' the big bang - ignoring his earlier (and to my mind, well justified) agreement with presentism - that the past, the present and the future are all one, and terms like `before' and `after' are meaningless.
   
   Having discussed problem-solving and criteria for reality, Deutsch goes on to discuss virtual reality with particular reference to the Turing Principle and logically possible experience. Here again, I feel that Deutsch makes an assumption that stretches the bounds of conceptual possibility to breaking point:
   
   `Since we cannot hope to render all logically possible environments, let us consider a weaker (but ultimately more interesting) sort of universality. Let us define a universal virtual reality generator as one whose repertoire contains that of every other physically possible virtual reality generator. Can such a machine exist? It can. Thinking about futuristic devices based on computer-controlled nerve stimulation makes this obvious - in fact, almost too obvious. Such a machine could be programmed to have the characteristics of any rival machine. It could calculate how that machine would respond, under any given program, to any behaviour by the user and so could render those responses with perfect accuracy (from the point of view of any given user) [...] given the appropriate program and enough time and storage media, it could calculate the output of any computation performed by any other computer, including the one in the rival virtual reality generator. Thus the feasibility of a universal virtual reality generator depends on the existence of a universal computer - a single machine that can calculate anything that can be calculated.'
   
   His reference to `perfect accuracy (from the point of view of any given user' I found particularly hard to swallow. Necessarily, accuracy cannot be perfect if it is from a point of view. That sort of accuracy is a relative. Besides, how can a given user testify to accuracy, even if they have experienced the environment? Perhaps Deutsch should read Wittgenstein's private language argument, in which the suggestion that it is possible to compare a pain I have today with a pain I had yesterday is reduced to absurdity.
   
   Hume's scepticism with regard to reason is relevant: he points out that if we wish to make a judgment about the reliability of any proposition, we should first assess the reliability of that kind of proposition in general as well as the reliability of the author of the proposition. But we can't stop there. We must also apply the same rule to ourselves and assess our own ability to make assessments as to the reliability of propositions, and that of the authors of those propositions. Then there emerge further questions concerning our ability to assess our own ability to assess prior probabilities and so on ad infinitum so that `all the rules of logic require a continual diminution and, at last, a total extinction of belief and evidence.' (Basic Flying Instruction, p.105)
   
   Deutsch is not only a physicist. He is a physicalist and a functionalist. Towards the end of the book he seems to get carried away by his functionalism, suggesting that human beings or their evolved descendants have the potential to control not only themselves, not only the planet, but the universe. I had the uncomfortable feeling, from time to time, that he was too ready to `pick and mix' worldviews to compile his explanation of reality. The universe is one, and then it is many. The multiverse is one, but it also could be many. Things are separate, but they could be joined. Time flows, then it doesn't.
   
   Deutsch refers to photons travelling through a vacuum, presumably an absolute vacuum. This assumption sounds very much to me like Newton's supposition of `action at a distance', which was so brilliantly deflated by Faraday's metaphysical speculations, discarded by Einstein as a stepping stone to STR and GTR, and is denied by quantum field theory. Even in string theory, there has to be a length of string between the blobs. As Parmenides warned 2500 years ago, when we speak of `what is not' we get into serious trouble.
   
   Deutsch relies heavily on the Cantor-Turing conjecture, which, following Roger Penrose, he states as the Turing principle:
   
   `For abstract computers simulating physical objects, there exists an abstract universal computer whose repertoire includes any computation that any physically possible object can perform.'
   
   From that principle, he concludes that it is possible to build a virtual reality generator whose repertoire includes every physically possible environment. In referring to `every physically possible environment' he assumes that that there are more than one physically possible environments, and that such environments are entirely separate. On page 291 he claims: `a virtual reality generator could [...] give one the experience of living in the age of the dinosaurs, or in the trenches of the First World War, and it could make the constellations, dates, newspapers or whatever appear correctly for those times.' My problem with this is that I believe that giving a `perfectly accurate' experience of the trenches in the First World War (or indeed any environment) is impossible, as every environment is joined to every other: there is only one environment.
   
   Deutsch frequently refers to physical reality, and I am left wondering whether he distinguishes between reality and physical reality. Personally, I side with Spinoza's view that there is only one reality, that it is infinite in infinite ways, or aspects, or attributes, and that we human beings, being limited creatures, have access to reality - can conceive of it - in only two ways: through physics, and through logic or mathematics. (Descartes'`thought and extension'.)
   
   Spinoza's view of energy as matter-in-motion and of Nature as one self-causing infinite reality conceived under infinite attributes, was influential on Einstein's development of space-time physics and his abandonment of the supposition of absolute simultaneity. Amazingly (to me, at any rate!), Spinoza's view seems to sit very well with David Deutsch's supposition of parallel universes, which seem to me to be nothing other than Spinoza's infinite aspects or attributes of reality, to which we have access only to thought and matter - maths and the physical sciences.
   
   In spite of the above criticisms, this is a brilliant, exciting and stimulating book. I am not a professor of anything, only a miserable graduate in philosophy from the University of Durham. But as the mathematician Dodgson said, a cat may look at a king.
   
   Basic Flying Instruction: A Comprehensive Introduction to Western Philosophy



4. Life is far to short to waste on this excrutiatingly pompous, self-congratulatory and tedious (supposed) account of the theory of everything. If you ever decide self-flagellation is absolutely unavoidable this is just the thing for you! I ran screaming, pretty damn quickly, back to the sanctuary of Michio Kaku!



5. I was hoping for something that related the discussed the implications of quantum mechanics on our on view of reality. IMO, the book was lacking.
   
   I found the writing style painful to read. As other reviewers have said, the author should have used a ghost writer.
   
   The author spends too much time pumping 'virtual reality' and too little time on quantum mechanics.
   
   The chapter on epistemology was interesting.. so perhaps the one positive take away is a new interest in the work of Karl Popper.

2 comments about Dr. Quantum Presents Do-It-Yourself Time Travel (Sounds True Audio Learning Course).

1. Since Fred Alan Wolf's book The Yoga of Time Travel: How the Mind Can Defeat Time is one of my all-time favorite books on the subject of time travel, I was understandably thrilled to discover that Wolf has recently created a new audio learning course on the subject of time travel. My next happy surprise is that DR. QUANTUM PRESENTS DO-IT-YOURSELF TIME TRAVEL feels very much like sitting down with Wolf and hearing him explain the physics and metaphysics of time travel in simple terms that any layperson can understand. Wolf has a delightful way of describing a seemingly complex subject in such simple terms that not only does time travel begin to make sense on an intuitive level, it also starts sounding quite doable even to those coming from a much more rational, down-to-Earth point of view. This audio course flows beautifully over six compact discs in such smooth fashion that the listener is drawn into contemplating the notion of how tachynauts might one day explore time in much the same way that astronauts explore space, after first having considered the nature of parallel universes and the interconnectivity between various possible and probable worlds... and some of the ancient yogic requirements considered necessary for traveling through time utilizing meditative yogic techniques. This audio workshop is so riveting that I found myself zipping through all six CDs in rapid succession, delighted to start each new segment in order to try the next exercise, hear more time travel stories, contemplate the next big ideas... and see where... and when... I might find myself next. Highly recommended!



2. Dr. Quantum Presents DO-It-Yourself Time Travel, Is very cool. The information was very complex, Yet easy to understand and grasp, Thanks to Dr. Quantum. A must have for anyone who has ever thought about time travel or who wants to experience a truely different mind expanding experience. 5 Stars over and over again. Very well done.

5 comments about Concepts of Modern Physics.

1. It points out most of the important concepts clearly. It is an interesting book if you have proper foundation of Maths. However, I prefer the layout and format of its first edition. It achieved good balance between maths and physics.



2. I did not think that this book offered too good of explanations. After taking the course with this book accompanying it, I did not feel that I went away with anything except for more confusion toward physics. If you are thinking about purchasing this book, you will probably want to try a different text.



3. ...While understanding can come from this book, the numerous typos distract, confuse, and degrade the quality of it. Examples of this include the following: on page 7, the definitions for t_0 and t should be switched (although it's all relative); on pages 39, 40, and 41, there are occasions where a prime ' is either lacking or misplaced; on page 43, a variable dz' should be replaced by dx'. Page 137, example 4.5 (b) gives contradictory exponents. The correct exponents are ^2 throughout. The answer is also wrong! (should be 2.47x10^15 Hz)
   These are just a few occasions that I have noticed and have spent hours struggling with.



4. The book is not very good with the equations in it. It needs to be more consistant with variable letter names. Some equations in the proofs cannot be used to answer end of chapter questions. This gets confusing.



5. After already reading and doing tons of math problems in Griffith's, McMahon's, Schaums and others,I read this book and it put many questions into proper context. Although I have the 4th edition, he brings into focus the mainstream thoughts that should be applied using quantum physics. He sets the tone of almost explaining it to you like he is talking to you! When I got into Chapter 5, I had already done most of the math, so it was just fun to read it and listen to his perspective. I got the feeling that the math was on the back burner and the concepts were on the front burners and although they weren't difficult concepts; they were good explanations!