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

von David Deutsch

ISBN: 014027541X

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Important book, though flawed
This is an important book, though flawed. Deutsch describes four "strands" in modern science: the many-worlds interpretation of quantum mechanics, evolution as advanced by Dawkins (who wrote The Selfish Gene), the new scientific method as expounded by a guy named Karl Popper, and the "Turing Principle", related to computation.

The two strands that are at all interesting are MWI and evolution. The others are garbage, as far as I'm concerned. I found it extremely frustrating that he kept bringing them in as the established theories of major branches of science.

For example, when introducing the Popperian theory of how knowledge is acquired, he first erects an elaborate straw-man concept of inductivism, and then smashes it down. In his straw-man, there are obvious flaws.

His "Turing principle" is equally ridiculous. He continually focuses on the idea of virtual reality in his book, but I'm not sure why. It's not as if virtual reality can actually tell us anything about real reality, but he wants us to think that it can.

Nevertheless, there were, as I said, important things in this book. The first is the best defense I've read so far of MWI.

In the preface (p. ix), he writes

Our best theories are not only truer than common sense, they make far more sense than common sense does.

In Chapter 1, The Theory of Everything, he begins to harp on the great Errors that he continually mentions throughout the book, including instrumentalism, positivism and reductionism.

Deutsch loves to complain about reductionists, although I simply cannot see what it is that he's trying to say. I agree much more with Steven Weinberg on this point (see Dreams of a Final Theory).

In chapter 3 he spends a huge amount of text tearing down the philosophy of solipsism, which he defines as "the theory that only one mind exists and that what appears to be external reality is only a dream taking place in that mind". When introducing his scientific method according to Popper, which he elevates to epistemology, he says

In science the object of the exercise is not to find a theory that will, or is likely to, be deemed true forever; it is to find the best theory available now.

Baloney! I'm sure that the average theoretician would love to come up with a theory that would be deemed true, and would continue to be deemed true forever.

Also in chapter 3 he does draw an important parallel between the evolution of scientific theories and biological evolution.

From chapter 5 (or 6):

The laws of physics, by conforming to the Turing principle, make it physically possible for those same laws to become known to physical objects.

This is a good conclusion, and profound. This reminds me of that quote "the stars have made eyes with which to admire themselves". It echos the fundamental requirement that consciousness be somewhat self-referential.

In Chapter 8, he talks about his "fourth strand", evolution. He makes the point that life is a fundamental property of nature.

He describes a concept of replicators, which are things that cause copies of themselves to be made when they interact with a specific environment. Genes are replicators, but organisms are not. Organisms aren't, because the copies that are made are not exact duplicates.

In chapter 9 he talks about quantum computers, and its pretty interesting. This is his field, after all.

In chapter 10 he tries to make the point that our knowledge about mathematics is only as sound as our knowledge of physics - that they are on the same level.

The only propositions that logic can prove without recourse to assumptions are tautologies - statements such as "all planets are planets", which assert nothing.

Well, no one, to my knowledge, ever claims that mathematics can prove things without recourse to assumptions. Indeed, all of mathematics can be derived from sets of axioms, which really make the entire structure the same as a tautology. In other words, if our axioms are given by the statements A, B, and C, then every statement in mathematics is a sort of tautology of the form:

If A, B, and C, then D.

In chapter 11, he talks about time. He does a good job correcting the error of most people's conception that "time flows", that there is some "external time" with respect to which you can see our time flowing. This error shows up in science fiction stories and movies that feature time travel. Often there is some time limit on the travelers, even though they are bouncing back and forth between different world times. "Time Cops" and "Bill and Ted's Excellent Adventure" come to mind.

But he's wrong that time doesn't flow. It flows at a rate of exactly one second per second. And he even makes the same mistake in the following quote:

To exist at a particular moment means to exist there forever.

"Forever" means "for all time", doesn't it?

This I like, and I need to explore further: he says (p. 278):

Other times are just special cases of other universes

In chapter 12 he talks about time travel. He says that it is logically consistent with MWI, and I agree.

In chapter 14 he talks a bit about Tipler's The Physics of Immortality. He makes the same error as Tipler when discussing the possibility that the Omega Point will resurrect us. If that is so, then why aren't we "transported" to that existence "right now"? I mean, presumably the Omega Point could reproduce our state at every moment in our lives, including this one. The fact is, that we are "inside the Omega Point" right now, and we're not!

A uniquely original and exciting book
The driving force behind this book is the conviction that the natural world is intelligible, but only if we take seriously the explanatory content of our most successful theories. What we must not do, if we hope to make sense of the world, is to rely on our pre-eminent theories only for practical purposes, while looking to other, incompatible theories for our conceptual models. But that is precisely what the scientific establishment has been doing, according to the author.

He develops this thesis by examining four fundamental theories, and arguing that, taken together as genuine descriptions of reality, they constitute the first cut of the Theory of Everything, i.e. the beginning of a conceptual framework that will progressively unify all human knowledge.

The style is always lucid, and although the material is sometimes challenging, Deutsch handles it admirably. Several chapters - such as Chapter 2, which is utterly convincing about the existence of parallel worlds - stand out as beacons of science writing.

Only in the last chapter do the author's remarkable powers of analysis slip somewhat, when he gives undue credence to Frank Tipler's musings about the likelihood of God-like beings inhabiting the ends of time. But if you treat that chapter as a speculative appendix, and treat the penultimate chapter as the intellectual culmination of the book, you are in for an exhilarating and profoundly instructive read.

A must read for thinking people
When I ordered The Fabric of Reality, I was hoping I would receive a book something like Quantum Computing for Dummies. While this book does not explain the nuts-and-bolts of programming quantum computers, it is nevertheless an eminently practical guide for problem solving in general, and is curiously comforting in the process in that it rationally confirms our deepest intuitions held from childhood. It also reveals much about the 'sociological' aspects of doing science, from the egalitarian mode of the symposia, to the political elitism of much of the rest of it. This book (while yet coy) does not ultimately shy away from the dirty-little-secrets of scientific methodology. I heartily endorse The Fabric of Reality as 'a must read' for anyone embarking on a career of thinking.

Having read this book, I feel I am now prepared to ace my Philosophical Implications of Science class exams (but alas, I am fifteen years too late). Deutsch takes us from realms of pedestrian problem solving up the heights of the Eiffel tower where we survey the breadth of the terrain of scientific problem solving and we learn that the two modes are the same. All of the principal players that were there in my philosophical science class are here again in the Fabric of Reality, Karl Popper, Richard Feynman, Kurt Gödel, Thomas Kuhn, Niels Bohr, to name just a few. Deutsch explores every domain of explanation I can imagine, quantum mechanics, final cosmology, morality, esthetics, reasoning, all interwoven into one continuous tapestry. Yet this is not a new orthodoxy. Indeed, this is finally a scathing reputation of all orthodoxies (including by implication, postmodernism) unless progressivism be labeled orthodoxy.

Deutsch's style is professorial (i.e. often overbearing and repetitive--although he is self-effacing when relating his own contributions). There are plenty of rhetorical questions that probe the reader's understanding and reveal wider and deeper implications. Every chapter (except the last) ends with a glossary and a summary, which reinforces the entire tapestry and affirms Deutsch's commitment to the reader, that they be given every opportunity to understand the overarching argument.

The Fabric of Reality waxes passionately about embracing always the best available explanations in science. This made the book read like a preamble to the final chapter The Ends of the Universe which is a discussion of Frank J. Tipler's Omega Point Theory. Apparently the Omega Point Theory is still off limits to 'serious' science. While it lacks the mathematical precision physics has come to expect from new theories, the omega point theory is nevertheless a bona fide theory with testable predictions the first of which has been verified, the mass of the top quark, the measurement of which was eminent, hence the necessity of Tipler publishing when he did. While dutifully introducing many caveats to Tipler's assertions (many of which caveats are dubious or wrong-such as, mass and energy are limiting on the omega point trajectory), Deutsch declares that the Omega Point Theory is the best available explanation of the end of the universe and that escalating imperatives, controversies, and delights should continue to engage people (subjectively) forever.
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