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

If any of Deutsch's four theoretical 'strands' could be called the seed of Deutch's synthesis, it would be Popper's epistemology. For it is this explainatory structure that provides the 'structure for the structure' that Deutch then fits the remaining strands into. Essentially, Popperian epistemology says that knowledge grows only through the process of trial and error, conjecture and refutation, not by some inductive process. And the key to formulating a conjecture that will survive the refutation process is understanding the explainatory structures of our best theories as they relate to the problem's domain. The creation of new knowledge requires the human capacities of innovation and creativity, specifically the mysterious weaving process whereby similarities between seemingly disparate phenomenon are spontaneously seen. This is how Deutch weaves an accurate (though tenative) description of reality. More importantly, this is how Deutch's reality says it must be [self consistency]. If Deustch's theory itself is true, then, it constitutes a growth of knowledge. The theory itself describes how this can happen.

I would guess that Deutch had his first glimpse of the woven threads when he figured out that computation theory, once thought to be purely an abstract construct, had to have a physical basis in reality. After all, computers are physical objects, subject to the laws of physics. Alan Turing's classical computation theory had many incompatibilities with classical physics that kept it in the realm of abstractions, but we now know classical phyics is false. This physical basis for computation turned out to have its roots in our newest, most fundamental (reductively speaking) physical theory, quantum mechanics. Combine this with the role of computation in evolution (genes 'rendering' environments), along with the role of our senses in representing our environment to our brains (virtual reality), and the growth of knowledge (rendering ideas) and you can see how computational processes are fundamental to Deutch's reality.

Deutch's contribtions to science and philosophy probably won't be appreciated until we have working, practical quantum computers. Only then, when his theories are what allow us to build our working technology will he be taken seriously. 'Fabric of Reality' provides us then with a prescient glimpse of what will eventually become our world view, describing the first great unification of our best theories.


quantum computers   July 5, 2005
Palle E T Jorgensen (Iowa City, Iowa United States)
25 out of 29 found this review helpful

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.



One of the best popular science books I ever read   December 13, 1999
15 out of 17 found this review helpful

This book is full of ideas and is written with exceptional clarity and power. Some of the ideas are controversial, and the author makes no secret of that, but they are surely thought-provoking and may well turn out to be right. As a physicist, I can add that clarity in this book is not achieved at the expense of logical shortcuts and gross oversimplifications, as it often happens in popular science. The intellectual and scientific level of the discussion is very high.


Philosophy in physics clothing   September 17, 1997
rubin1@jeflin.tju.edu (Philadelphia)
14 out of 16 found this review helpful

"The Fabric of Reality" presents the mind-bending multiple universe (multiverse) hypothesis that arises from the "wierdness" of quantum phenomena in a style that is as clear as may be possible. The philosophical ramifications of this view are profound, and leads the author towards a fantastic overall discussion of the nature of reality itself. As a cell biologist myself, the lucid exposition of issues such as perception, knowledge, evolution and computing have opened new intellectual vistas. This is not a book for the uninitiated. At a minimum, a cultural background in quantum physics, biology, epistomology and computing are required. Indeed, the flow of logic became obscure to this reader when the discussion went deep within my scientific blind spots. In this regard, I was fortunate to have read John Gibbon's "In Search of Schrodinger's Cat", and Timothy Ferris' recent book "The Whole Shebang" prior to tackling "The Fabric of Reality". David Deutsch clearly is a man of exceptional intellect. He is passionate about his ideas. It is here where he may be faulted in that his ardent advocacy for the multiverse hypothesis tends towards the polemic. I am sure that physicists will have much to say about Deutsch's ideas, and I can imagine that the discussions will be hot. Outside of his own field, Deutsch's ideas approach the fanciful, but are always thought provoking. Although the overall style is lucid, the text can be a bit wordy and repetitive. These reservations notwithstanding, this book may emerge as a classic in the field of the philosophy of science. David Deutsch clearly possesses a remarkable intellect.