The Fabric of Reality: The Science of Parallel Universes - and Its Implications

The book was published in 1997, and a lot has happened since then. Yet the foundations retain their permanence, and David Deutsch's captivating writing is as fresh as ever. Despite the availability of newer books, for the layman/woman, now almost 10 years later, I would still rank this book at the top. There is a lot in the book; and yet, the ideas are presented in a clear and engaging way. The author is a pioneer, a giant in modern physics; he was and is a driving force in new discoveries in the subject. Yet he has his personal way of explaining physical reality. His view is not shared by all scientists, one should admit. However, there is agreement about the scientific conclusions. The first chapter in the book stresses *explanation*, our understanding of the reason for things. There are other views of science, e.g., instrumentalism: predicting the outcome of experiments. The author's view on quantum theory is based his idea about parallel universes. While fascination, the reader should be aware that there are alternative theories for explaining quantum phenomena. An important concept in quantum theory and quantum computation is "decoherence", and it is explained (ch 9) in terms of different (parallel) universes. In ch 9 about quantum computers, it might have been only fair to mention that there are such other current views on decoherence; but this is a minor complaint. Presentation: I love that each chapter concludes with a section on terminology and a summary. As a subject theoretical computer science started with Alan Turing and John von Neumann in the 1940ties: Classical computation follows the model of Turing,-- strings of bits, i.e., 0s and 1s; and a mathematical model which is now called the Turing machine. Instead of bits, why not two-level quantum systems, e.g., models built from electrons or photons? Such an analogues model for computation based on two-level quantum systems, and a quantum version of Turing's machine was suggested in the 1980ties by R.P. Feynman. The form it now has owes much to the author himself, David Deutsch. But it wasn't until Peter Shor's qubit-factoring algorithm in the late 1990ties (not covered in the book) that the subject really took off, and really caught the attention of the mainstream science community, and of the general public: The 'unbreakable' codes might be breakable after all ! That there is a polynomial factoring algorithm, as Shor showed, shook up the encryption community, for obvious reasons, and created headlines in the news. Ideas in the quantum realm, and not part of classical thinking, include superposition of (quantum) states, the EPR paradox (1935), and (quantum) coherence. Although these concepts are at the foundation of quantum theory, they make a drastic change in our whole theoretical framework of computation: Now one passes from the familiar classical notion of bit-registers to that of qubit-registers, and the laws of quantum mechanics take over. Mathematical physicists and computer scientists must revisit the old masters: Bohr, Einstein, Heisenberg, Pauli, and Dirac. In passing from logic gates to quantum gates (unitary matrices), the concept of switching-networks from traditional computer science now changes drastically. The changes introduce brand new scientific challenges, and new truly exciting opportunities. I believe that this book does justice to this, and that it is still a fascinating and thought provoking invitation to some of the most intriguing trends in modern physics.

I love David Deutsch's honesty. I teach physics at a small university, and I know I've been guilty of hesitating and couching my words so as to not seem crazy, or to not upset the sensibility of others. But if we're to make progress, we need to be more honest with what we know, and counter those who don't know but should. If you fail to move forward with an understanding of the multiverse in any form, I doubt we'll see the next big breakthroughs from you. That's okay in the larger sense. Many people with a lesser understanding will still make worthwhile contributions in other needed areas. And most don't need to know that our planet is round to make it home. And we can still refer to the sun setting, even if we know it's not; however, even if you don't know this, I suspect you might still make it through life largely unaffected by that failing. . . And it is a failing. And not just yours. It's my failing too. I don't know the answers. I don't know anyone who does. However, I suspect Deutsch's understanding will be far ahead of mine in most times future to now. Which is why I look forward to anything he writes. If you haven't considered also getting his more recent book, The Beginning of Infinity, do. In The Fabric of Reality you will confront the best of the big picture that humans have been assembling for centuries, but which most still can't accept. What can be expected to be known of biological evolution, even to the level of a layman's appreciation, is grasped by only a minority (if you believe in biological evolution with a guiding hand from a god, then you're in that majority who simply don't understand evolution). But I feel comforted to have my closet friends all accept some form of biological evolution, even if we disagree over the details. Quantum physics, however, has an even smaller minority who are willing to face it on its terms, even if we consider only those who do largely accept evolution. Instead we get silliness like the Copenhagen view of Bohr and Heisenberg, or silliness like the wishy-washy view of those belonging to the "shut up and calculate" school. . . Whatever the reason for this (and an important appreciation of where the answer will come from is found in Deutsch's lastest book), read this book from Deutsch, read his latest book (The Beginning of Infinity), if you want to think about these ideas seriously.

I would love to see many-worlds shown superior to all available alternatives, but this book did not make the case. The chapter on epistemology is excellent. He concludes that a successful theory must have explanatory power and must satisfy evidence that refutes all prior theories. He does a good but incomplete job of illustrating the explanatory power of many-worlds, failing to show how many-worlds explains the EPR results. Unfortunately he ignores all competent existing theories. Indeterminism and wavefunction collapse are not required by QM. They are merely interpretations. Wavefunction collapse in particular is not required to explain the double-slit results because the virtual particles (another interpretation) that constitute the wavefunction are not observable and have no relation to the new entity that results from a "measurement" interaction. The EPR experiments assert that "hidden variables" havc been eliminated, but indeterminacy is still not proven. Deutsch rightfully proclaims many-worlds superior to one interpretation of QM, based solely on the double-slit results, but he fails to mention alternatives. The most compelling evidence is the idea that a quantum computer could make computations requiring >10^500 parallel universes. IF such a computation is performed, it may be difficult to explain in any other way, but it has not been done and the obstacles may be fundamental. He asserts that all worlds in the multiverse must follow the same physical laws. There are many more worlds out there that fit in his philosophy. We know our particular laws result from post-Big-Bang broken symmetries and that event itself was not a pristine Perfect Form. What does Deutsch mean by "laws of physics"? Is his interpretation that there are many multiverses? I had great hopes for the chapter on time, but his writing style is sometimes impenetrable and it came across as hand-waving. If Richard Feynman liked many-worlds, it must be right. Deutsch should try again, in collaboration with a scientifically literate writer.

I see this book as the ultimate guide to cake baking. It is the very thing the title suggests ~The FABRIC of Reality~. As a famous saying goes, "To bake a cake from scratch first you create the universe" This book identifies the absolute basic ideas that define our understanding of what our senses tell us. Regardless of what you think of his theory of the multiverse or even his views on quantum physics you must admire the way he challenges us to look at the things we believe in their most basic form. He says if you kick a stone and you feel it hurt your foot then you must assume it is real. All our lifetime beliefs must stem from this simple observation. To me DD has opened up my eyes to see the world and after reading this book my mind was forced to make adjustments in the way I come to accept things as fact. He goes to the very heart of what not only what the fabric of the universe is but during the explaination forced me to see what the fabric of my own surroudings is and how I should decide what to believe in. I must highly recommend this book as required reading to anyone who has ever decided to belive in something just because someone else said it was true (hint - religous writings) without offering the rock kicking experiment to prove it.

This is an interesting and insightful book by the scientist David Deutsch. The book is well written and the points are explained in an understandable manner, although sometimes through boringly detailed examples. My rating, however, does not reflect my agreement with the content. This book gives an unorthodox view of scientific knowledge, one that is intriguing, but not necessarily true. I shall explain my view in the following paragraphs, for anyone who wants a quick overview of the book. The writer believes that science should be viewed from a different angle, that each of the four "strands of reality" he mentions makes a fundamental piece of reality that cannot be reduced to the other ( though they can be understood through each other). This view is contrary to hierarchal reductionism that is common in science and evident from many fields such as biology, chemistry, and physics. The writer also argues that our understanding of reality is getting more profound, and is driving us away from the meaningless practices of instrumentalists. I agree with this point although it is not argued for very well. As for his case for the four strands, firstly, the writer believes that the many worlds interpretation of quantum mechanics is an avoidable fact. He describes the conclusion in a way different from how Everett first proposed it. And I think it is less convincing, despite the fact that the interpretation is more valid than the classical Copenhagen one (this is evident by how it does not limit the mathematics of QM), it should not be argued for because it is what it "seems"! Our brains did not evolve to necessarily understand the quantum world, so relying on that is in my opinion a poor argument. Second, the writer explains why the theory of computation describes a fundamental aspect of reality. Deutsch is a leading figure in this field as a physicist, and he shows us his unique view of the universality of nature. He argues that virtual reality reflects the possibilities of actual reality and he draws countless conclusions from that, including a strong form of the Turing principle, which the writer supports without doubt. My take on these proposition is that they do say something about reality, after all we do virtually simulate our surroundings in our brains. Therefore, there is some truth in this, at least that virtual reality illuminates logical possibility if not necessarily physical possibility (this is in my opinion more acceptable and consistent with the brain being a virtual reality generator). As for the strand that defines life as a fundamental aspect of reality, the writer gives it less attention than the rest. He argues from Dawkins' theory of replicators that life patterns are similar across parallel universes, thus a fundamental aspect of reality. This did not convince me, if not because certain patterns of DNA will vary depending on the environment the organism evolved in (so different in different universes just like junk DNA is), but also because it relied on another strand to be proven. And even Dawkins himself (in the Selfish Gene) used a hierarchal argument to lead his readers through the survival of the stable to the survival of the replicator, thus deriving the theory of survival of replicators from "physical laws" and not assuming it is fundamental. Perhaps Deutsch disagrees, he states other conclusions regarding the mind and free will which modern biologists and neuroscientists may not agree on. The strand that deals with knowledge is very well argued for. I think the writer gives a deep and confident statement for Popper's theory of the growth of scientific knowledge. The arguments are very consistent and give a very strong candidate for solving the problems of the philosophy of science. Does it really dictate how knowledge overall is obtained? Deutsch believes so, he uses it to make various assumptions, I am not sure it is applicable outside of science and problem solving in general. The writer also addresses other topics, most notably mathematics and time. In these two he excels at giving consistent views, one that I almost totally agree with when it comes to mathematics, and another which I think is the most plausible if the many worlds interpretation is proven. Another topic that is addressed in the latest chapter is the end of the universe. I believe it is the book's weakest claim, if not only for being disproved by current cosmological observations, but also because the line of though assumes something about physical reality (the end of the universe being an omega point) from a principle which talks of logical possibility and is bound by physical laws and the actual state of the universe. This is a long review, and the book deserves it. All in all, it's a good book for any science enthusiast. Deutsch's world-view is interesting, comprehensive, unorthodox, and occasionally unconvincing, but is certainly inspiring.

After reading many other writers of popular science and philosophy, such as Daniel Dennett, Richard Dawkins, Sam Harris and Steven Pinker, I absolutely fell in love with David Deutsch and his style of thinking. This is philosophy that actually gets you somewhere, completely avoiding the piddling controversies that riddles philosophy of science, instead spending time on presenting useful metaphors and constructing a comprehensive structure for thinking about reality. David Deutsch has the gumption not only to call the goal of a great "theory of everything" unambitious for only wanting to explain physical phenomena, and he even goes further than claiming we should seek a theory able to explain emergent phenomena such as morals and psychology. According to Deutsch, we already have such a comprehensive theory, and he goes on to present it convincingly.

Overall 5 stars, extremely interesting and good read. I also find the main thesis fairly convincing but that doesn't figure into the rating much in this case, for me. There are a few points that I feel were not material to the main point of the book and which were also poorly argued, and if I were editing the book I'd simply remove them-- Deutsch's seeming insistence on some kind of libertarian free will (I think he even says explicitly "you could have done otherwise") as a consequence of Many Worlds, a somewhat frantic argument at the end of the book where he attacks a strawman of evolutionary psychology trying to make a genealogical case against moral realism, and the chapter on time travel.

Very detailed on philosophy. Some new twists