The Fabric of the Cosmos: Space, Time, and the Texture of Reality

Brian Greene's latest (equation-less) book "The Fabric of The Cosmos", addresses why spacetime is not simply a metric but a real "something", and the overarching question, "Just what is reality?" My take is that everyone should read this book!! Part I contains a magnificent overview of the development of Relativity and Quantum Mechanics. This is both fully understandable to the layman and has fascinating new angles - new insights - that are spellbinding to this professional physicist (new views/descriptions of acceleration and gravity, Bell/Aspect vs. EPR, possible conflicts between Relativity and QM on large scales [not just quantum fluctuations at the Plank length], etc.). Part II (what's time?) is absolutely fascinating! Greene's whole discussion of what time might be, its apparent "flow" as experienced by us, and his discussion of statistical mechanics and entropy and their insufficiency to define a classical "arrow of time" ("flowing" from past to future), absent something like the Big Bang, are super -AND CLEAR TO THE GENERAL READERSHIP. I loved his review of the whole business of quantum theory and reality, e.g., the so-called "delayed choice" and "quantum eraser" experiments, the various attempts to come up with some glimmer of understanding of "the measurement problem" (technically, the unpredictable collapse of the wavefunction by another system, e,g., a macroscopic instrument still composed of underlying quantum states) and progress on the proposition of "decoherence". For non-cosmologists, Part III ain't for sissies but does have some wonderful word pictures, mainly towards the beginning and end, which are extremely worthwhile if one doesn't get too bogged down in the middle with unified quantum field theories and elementary particle physics. Towards the beginning of Part III is a terrific discussion of the curvature(s) of space, and towards the end are many fresh insights on repulsive gravity, the inflation field, dark matter and energy, wrinkles in the cosmic-ray background, etc. The real gem is Greene's description of the inflationary (vs. "standard") Big Bang model, with a great summary of our current understanding - and the potential limitation of our further understanding - of how this universe could have started in the first place. (For the serious student, I would note that Greene's enthusiastic description of how inflation impacts the problem of "fine tuning" is perhaps overstated. One important aspect of fine tuning is greatly relaxed, but there are many others that are not affected.) I found Part IV (superstring theory) of Greene's book surprisingly easy going, especially re. the extra space dimensions, M-Theory, and Branes. It provides a far superior view of the "big picture" than is found in his earlier, more detailed and technical book on superstrings, "The Elegant Universe" (1999). I should add a note here for those who have not yet read books like The Elegant Universe. While string/M-theory provides a conceptual framework for reconciling quantum mechanics and general relativity (each being, individually, solidly proven theories but which don't work together), and therefore affords in principle some way to mathematically describe the origin and elemental constituents of spacetime, it is still a long, long way from being subject to experimental verification, due both to current inadequacies of the theory and to the lack of experimental equipment to conduct relevant experiments. Part V, the final chapters, includes a summary of some future experiments that might confirm some of the stranger aspects of the theoretical constructs, some quantum teleportation phenomena (and their unlikelihood of being extended to macroscopic objects), time travel (including Kip Thorne's version of wormholes, which are also unlikely), and a final chapter described next. I particularly enjoyed Greene's introductory discussion of time travel where he explains a resolution of the common apparent paradoxes in a person's traveling backwards in time (e.g. to kill his parents before he was born) using only classical spacetime, i.e., without resorting to any quantum phenomena (pp. 451-455). The final chapter is titled "The Future of an Allusion" and deals with probable future changes to our ideas about spacetime. These concepts are very exotic and pertain to both the macroscopic and microscopic properties of spacetime. An example of the former and, of those presented, Greene's favorite, is one in which our everyday universe is a holographic projection of some surface around us upon which the "real" events are happening. The final pages of the book contain this comment: "...regardless of future discoveries, space and time will continue to frame our individual experience; space and time, as far as everyday life goes, are here to stay. What will continue to change, and likely change drastically, is our understanding of the framework they provide - the arena, that is, of experimental reality. After centuries of thought, we still can only portray space and time as the most familiar of strangers. They unabashedly wend their way through our lives, but adroitly conceal their fundamental makeup from the very perceptions they so fully inform and influence." I would grade the drawings/illustrations in "The Fabric of The Universe" as top-notch aids to understanding. (I once complained that the drawings in a related general readership book by Stephen Hawking, "The Universe in A Nutshell" (2001), appearing after his best-selling "A Brief History of Time" (1998), were the greatest obstacles to understanding the book!) Finally, I would note that an interesting step upwards in generalizing Greene's question, "what is reality?", can be found in the three physics chapters (Chapters 4-6) of another excellent (and easier) book, "The Case for a Creator" by Lee Strobel (2004). There, the interpretation of many of the phenomena described by Greene is extended to metaphysics - metaphysics no longer being a stranger to science (a major paradigm shift sparked by scientific advances in the last two decades). A critical question in theism, "did the universe have a beginning?", is examined vis-à-vis concepts including Hawking's imaginary-time (no-boundary) proposal, Guth's inflation theory, and oscillating universes. Superb examples are given of "fine tuning" (for which hard data have been produced since the 1980s) and its arguments for "Intelligent Design" vs. multiple universes. (As atheist Nobel Laureate in Physics Stephen Weinberg said at one conference, these are the only two choices.) Instead of simply hypothesizing enough alternate universes (essentially infinite) to offset fine tuning, the dependence of a multiverse on superstring theory and inflationary cosmology is examined, including cyclical universes with Brane collisions. Martin Fricke, Ph.D. Del Mar, CA 1/17/2005

As an amateur interested in astronomy and astrophysics I enjoyed listening to Brian Green's the Fabric of the Cosmos very much, learned a lot and thought about fundamental questions about the universe in a different way. The questions below and many others are explored in a very interesting way. The explanations flow smoothly in a logical manner. Questions are raised in a way to get the listener thinking. This audio CD is relevant to both amateurs and professionals on the topic. As an amateur I was not able to understand everything on the CD yet. I am sure that as I listen to the CD several more times I will understand a lot more. These topics are sometimes explained in a boring way in high school physics and college astrophysics courses and therefore can kill interest in the topic. By contrast, this CD introduces them in a very curiosity raising manner. It uses a philosophical and yet at the same time a scientifc approach that is upto date. I have also watched DVDs on similar topics before. So before listening to this CD I was skeptical about whether a CD about the universe lacking the visual elements of a DVD could be interesting or not. My answer now is definitely yes ; the auditory explanations create very interesting mental images in the listener's mind. Examples to some of the questions, among others, explored in the CD are : What is time ? What is space ? How are they related ? What is reality and how do we perceive it ? Does time always have to flow towards the future or can the direction of flow sometimes reverse ? Does time flow at the same rate in different parts of the universe or not ? How was the universe created ? How is it likely to end ? Is the big bang theory of the creation of the universe valid ? What has banged, how and how long ago? Could the universe actually be a giant brain ? How many dimensions are there in the universe ? Can we perceive all the dimensions or not ? What are matter and energy ? How are they related ? What are black holes ? What could be happening inside black holes ? How does Einstein's theory of general relativity explain the universe ? According to that theory, why is the velocity of light always constant ? What is light made of ? What are photons ? How does light travel in space ? What are the limitations in Isaac Newton's explanation of the universe ? Are objects that are billions of light years apart in the universe completely unrelated or can they affect one another despite those awesome distances ? How do we perceive movement ? Movement occurs with respect to what ? What are frames of reference ? Could we perceive movement in space if there were no other objects at all in the universe ? How did atomic theory start ? What are the smallest particles of matter ? What are quarks ? Are electrons matter or energy ? What is quantum theory ? How does it reconcile with the theory of general relativity ? What is the uncertainty principle ? Why can't the velocity and position of an object be simultaneously determined with absolute certainty ? What is gravity ? Are all forces in the universe such as gravity, electromagnetism etc. actually different manifestations of the same force or not ? What is string theory and how does it explain the universe ? Is a unified theory that explains everything possible ? How is the structure of the atom related to the structure of the universe ? What are the historical developments of various theories that attempt to explain the universe ? What are the contributions of Isaac Newton, Albert Einstein, Edwin Hubble and many other scientists and philosophers to the development of our understanding of matter, energy, space, time, the universe and the texture of reality ? As of today how much do we understand the universe ? What questions remain unanswered ? What are the likely developments in these theories in the future ? How do the various theories contradict and / or reconcile with one another ? We may think that the answers to questions such as what is space ? what is gravity ? what is time ? what is reality ? what is movement ? are simple and that we already know the answers from our high school physics courses. So we may reason that there is no need for deep philosophical contemplation about them. However, this CD challenges this type of thinking and makes us aware that what we maybe taking for granted as known facts may not be ultimate answers at all. For example, if you think that space is equivalent to emptiness, to nothingness and if you think that time can flow only in one direction, that is towards what we call the future, think again. This CD challenges these concepts. Thousands of years ago humankind thought that the Earth was carried on the backs of giant elephants or turtles. A few centuries ago humankind was debating whether the Earth was flat or round, if the Earth orbited the sun or the reverse. Humankind's vision of the universe was limited to the solar system and fixed stars. The only elements were air, soil, fire and water. With the contributions of many scientists including Galileo our understanding of the universe significantly developed to date. However, this CD demonstrates that despite these giant steps, and despite the sophistication of our current theories, we still have a long way to go before we can say that we fully understand the universe. This CD demonstrates that we do not yet have certain and final answers, but we have many questions that are being further explored. Fortunately, we have significant knowledge, that accumulates in the right direction towards the discovery of the " truth ". So if these matters arouse your curiosity I strongly recommend that you listen to the CD titled " The Fabric of the the Cosmos " by Brian Green.

He's great, and it a fun book to read. But too often he's so close to the material he gives you know sense at all of what it means. For instance, another universe, a 3-brane, just a millimeter from ours! Great -- why a millimeter, why not a foot? What does that kind of closeness mean? Suppose it was farther? And what does a parallel universe mean anyway? Another universe the same size, or shape, or with similar laws, or what? And how could it be that close w/o its matter somehow interacting with ours? This is just one example of him introducing something really fascinating, and talking *around* it in depth w/o every telling you what it means or how to think about it, or what it means to our conception of the universe/existence. He also has a disturbing habit of talking about the most arcane subjects an then zooming out to use a horrifically simplistic analogy which he never returns to, something like talking extensively about the most confounding aspects of gravity and gravity waves/particles and then suddenly summing it all up with "it's as if this universe was a stretched piece of 3-dimensional fabric that stretches with gravity." Okay, but does that metaphor have any other implications? What does it mean that it's a fabric? In a sense, I wish Hawking had written this, because he really seems invested in explaining how these breakthroughs influence how we understand the human condition being situated in this particular reality. That having been said, he packs a lot in, and I'm buying his other book because he's one of the better writers on this stuff out there. Beware, but enjoy!

Excellent book, makes hard stuff easy to understand

I certainly recommend this book to any layperson that enjoys reading accounts of both the history of physics and the state of progress in modern physics. Greene is an excellent writer and he discusses and teaches often difficult concepts in an accessible way. On reflection, my only criticism of the book is really an issue with the subject of string theory, rather than with Greene's descriptions. For me, the book breaks down into two parts. The first 2/3 is an account of historical developments in physics using an excellent organizing scheme. Greene sets out two key questions. First, are space and time fundamental or do they simply arise as descriptions of relations among other fundamental entities? Second, how do we account for the unidirectional flow of time ("the arrow of time") which we experience? With these questions in mind, Greene reviews classical physics, Einstein's relativity, quantum mechanics, and recent cosmological theories. The best part of this first section of the book for me was the review of the inflationary hypothesis. After describing the second law of thermodynamics (the only part of traditional science which has an explicit arrow of time), Greene examines theories of the history of our universe for a possible explanation of both the flow of time we experience as well as the geometry of observed space. I understood the attraction of the inflationary scenario much better after reading the book. The second part of the book is a discussion of progress in string theory/M theory and the attempt to reconcile relativity and quantum mechanics in a unified framework. String theory's major exciting starting point was its promise to explain all of the fundamental particles and forces (including gravity) in a framework of one-dimensional units called strings. To laypeople, it is usually put forth that different vibrations in the strings describe all of the fundamental entities. However, the working out of string theory was accompanied by difficulties. First, there were several versions, not just one. More importantly (in terms of the nature of space and time), in its initial formulations string theory required an absolute backdrop of space-time, thus in a way reverting to a pre-relativity stance. Also, to work, there had to exist many more dimensions of space - a total of ten space-time dimensions. (I should note that, to his credit, Greene does a good job throughout presenting criticisms and possible shortcomings of string theory.) In recent years, Greene tells us, it was discovered that several different versions of string theory really were one theory after all. This overarching theory (which now featured an eleventh space-time dimension) also introduced new structures beyond one-dimensional strings. These 2, 3 and higher dimensional entities became known as branes, and the theory as M-theory ("M" possibly standing for membrane, but maybe several other things as well). Given that the mathematics in which the theory is described is so far beyond the typical reader, Greene describes the theory effectively and defends it against the common criticism that its details are not provable - he outlines experiments which could make key features testable in the not-too-distant future. Greene finishes by trying to recover the concepts of space and time (as we know them) by postulating that they emerge from a more complex foundational reality described by M-theory. I should also note that in the book he discusses a number of interesting topics that are somewhat off the track of his core narrative, such as time-travel and wormholes, and the holographic principle. As always, the descriptions are interesting and reader-friendly. Despite the fact that I doubt string theory can be described any better than Greene does it, the second part of the book is less compelling than the first. Part of the reason is simply the benefit of hindsight which enables the author to organize and present an effective narrative of the physics of the past, in contrast to describing the messier developments of a work-in-progress. However, in reflecting on Greene's account, I think there's more to it than that. I'm struck by the fact that many of the historical examples of progress in physics featured brilliant conceptual advances which built a framework for the resulting theory, while this is less clearly the case for M-theory. The paradigm case is general relativity, where Einstein had the insight that gravitation is equivalent to acceleration, and then he found a pre-existing mathematical framework in which to formulate the specifics of the theory. In contrast, my impression is that the small army of mathematically gifted M-theory modelers steer a course somewhat un-tethered to guiding concepts, and then attempt later to go back and fix things up. For example, Greene describes current attempts to draw connections to cosmological theories like inflation and to address conceptual shortcomings like space-time background-dependency. It may be that a new key conceptual insight will be needed to guide the advance of modern physics.

Great book, Good price, Quick delivery!

I am not a physicist, though I can honestly say that physics is perhaps one of the most intriguing and exciting aspects of the human quest for knowledge. I have been an ardent amateur student of astrophysics and theoretical physics since high school and there is no better author on the subject than Brian Greene. He is one of those rare brilliant scientists that is also a natural born teacher and gifted writer. I have seen Brian Greene give presentations, lead specials on Nova and other science programs, and have read his spectacular book on string theory, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory . I believe that "The Fabric of the Cosmos" is currently the pinnacle of his work in enlightening the general public on the true nature of the universe. In this book, Greene takes us on a fascinating journey through the history of physics from Sir Isaac Newton to the very present. He confidently highlights the major breakthroughs in physics over the past several centuries, which lead up to our current understanding of how the universe works. That being said, Greene also shows that there are many unresolved issues and that while string theory looks extremely promising, it is as of yet an incomplete theory. Greene's explanations on the physics of time are both fascinating and startling and will challenge your conceptions of what the human experience truly is. Greene does an excellent job of using real world examples and clear metaphors to explain the tough mathematics in more simple terms. For those interested in the actual formulas, Greene provides ample notes and detailed explanations in the back quarter of the book. The pages are also peppered with graphics and diagrams that ease in visualizing the physics at work. Trust me when I say this book is accessible to anyone interested in the topic. "The Fabric of the Cosmos" has challenged my perceptions of the universe and has inspired me to look at my life and my experiences in a new and unique way. It has also reaffirmed my belief that humanity has the intellectual capabilities to achieve its greatest dreams. I recommend this as a physics book of the highest order.

Very educational, entertaining and informative, but wastes a lot of effort trying to explain "the arrow of time" using entropy. This is a circular argument at best. An observed effect of the passage of time does not explain the cause of the passage of time. Here is a more common-sense (or Razed by Occam) explanation of time. Question: Why do we experience a "now" and not directly experience the past or future? Simple Possible Answer: Because "now" is all that exists. Time is one of those small, tightly-curled dimensions that String theorists love so much. There is no past, and there is no future. There is a tiny little loop, and all quantum jiggling quickly arrives back at "now". Question: Why does time only flow forward? Simple Possible Answer: It doesn't, because time is not an expansive dimension, like space, where one can visit any far-flung location within it. There is one, small location, and that's where we are. It's called "now". Question: Why do things change from one moment to the next? Simple Possible Answer: Just as space allows movement despite Zeno's Paradox, by having a lower limit to movement, and allowing quantum leaps from one location to another, time also allows for the same discrete quanta of movement. The difference is that time always arrives back at "now". Such an obvious explanation also eliminates the "time travel paradox". We cannot affect the past because it doesn't exist. If there is also only a "now", then the future also does not exist, meaning it is not pre-determined, so we don't have to wrestle with questions of free will. There is only one location in time (quantum jiggling notwithstanding). It is called "now". And no, this does not violate Einstein's general relativity. We are all moving through time at C (again, it's a tightly-curled dimension, so we can move all we want but still loop back to "now"). If something moves more quickly through space, it move more slowly through time. Such a fast-moving thing still arrives back at "now", despite travelling more slowly through time, because it's a tightly-looped dimension. To explain quantum entanglement and probability waves in this context, imagine the "many worlds" theory, then modify it slightly so that instead of all possibilities splitting off separately (which is exorbitant), exactly one possibility (across all of space) congeals from the quantum jiggling to become the next "now."

I'm only halfway, but it's one of the best books you can read to truly get a better understanding on how everything around us works and came to be. Very good analogies and recommended even for people with few or no formation on physics, astronomy, etc. Brian Greene explain very hard concepts in a very understandable manner. Very recommended.

Brian Greene has the ability to write books about physics that non-physicists can understand. He takes you into the world of quantum physics, looking at the structure of the universe, without going over your head. I enjoyed reading this book and would recommend it to students or general readers with an interest in science.

What a wonderfully insightful book about time and the Universe. I couldn't put it down. It was very informative. I like that the author uses a lot of easy to understand examples to make sure the reader tries to visualize difficult concepts. It definitely helped me to grasp some of the toughest subjects. I learned a lot, I highly recommend it to whoever is into physics.

A great masterpiece of elaborate description of physics for those with interest in, but without full understanding of modern physics. The book covers from Newton to the up-to-date string theory. All equations are hidden in the volume-end notes and details for accuracy are kept in the footnotes. Hence the body text is very understandable even for beginners. When a reader may have a question while reading, the answer will be usually written in the next paragraph. Somtimes a little redundant, but in most cases just right for easy understanding. At the end, the book will make you a modern physicist.

Like a powerful refresher course on special and general relativity, and all their implications for cosmology. Un excellent livre, accessible pratiquement à tous, mais également une source de réflexion pour ceux qui manient avec dextérité les équations fondamentales -- relativité, mécanique quantique, etc