The Fabric of Reality: The Science of Parallel Universes and Its Implications (Allen Lane Science) (Hardcover)

I do recommend this book to anyone interested in reading a summary of the pursuit of a "theory of everything" and a defense of the science of parallel universes. Deutsch's theory of everything depends on four theories: quantum (as espoused by Everett), epistemology (Popper), evolution (Dawkins), and computation (Turing). Even if one does not ultimately agree with Deutsch's ideas, his book offers some interesting thought experiments (the chapter on "time travel" is especially fun) and a concise overview of several scientific trends. In addition, his book provides a decent defense of why the theory of the multiverse should be considered a reasonable explanation for the interference results obtained the infamous two-slit experiment.

That said, I do think Deutsch's book contains many shortcomings. First, although the multiverse may be a valid explanation for interference phenomenon, Deutsch fails to convince that it is THE explanation. In one short paragraph, he dismisses David Bohm's theory of wave-particle duality. "Working out what Bohm's invisible wave will do requires the same computations as working out what trillions of shadow photons will do." One could easily reverse this sentence as a criticism of Everett and Deutsch: that the trillions of unseen photons requires the same computations as working out what Bohm's single invisible wave will do. Deutsch does not explain (in this book, anyway) why trillions of photons are simpler than one wave, and he does his readers a disservice by pretending that Bohm's work does not deserve a full refutation.

Second, and similarly, Deutsch dismisses with an even shorter paragraph the charge that his "theory of everything" is anthropocentric. (He pretty much admits it is, but tries--unconvincingly, to this reader--to turn it into an argument in his favor.) Third, his discussion of evolution (one of the four "equal" strands of his theory of everything) is a mere 25 pages and, unlike the rest of the book, is at times incomprehensible and seems completely indebted to Dawkins. (Not that there is anything wrong with Dawkins's work; rather, Deutsch just seems in over his head during this part of the book.) Fourth, he rejects Kuhn's belief in the rigidity of scientific paradigms (for example, the inability of thinkers in Galileo's time to accept the full implications of the Copernican system because they were so used to thinking of the world in Ptolemaic and Judeo-Christian terms), but then he describes a modern scientific establishment that refuses to accept the multiverse implications of quantum theory because they are rooted to the concept of a single universe. (Just because modern scientific discourse is more civil does not mean that Kuhn's argument is incorrect. Deutsch's opponents are still mocking him behind his back, in book reviews, and anonymously on this Web site. Or, even more effectively, they are ignoring him altogether.) And, finally, his discussion of Tipler's omega-point theory is hurried and unfortunately nebulous: at one point, Deutsch seems to be saying that knowledge in the universe will become omniscient and omnipresent--which is practically the same as saying that the universe will become itself.

Nevertheless, regardless of what you think of its implications, Deutsch's views deserve serious consideration and, as necessary, rebuttal--not mockery and scorn. In the same way that we read Lucretius even though we know him to be wrong (or, for that matter, Einstein because we believe he is mostly right), we should read Deutsch's work because he challenges the way we look at our world.

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.