The fabric of reality

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!

This being said, I actually found the book very interesting as a social and historical document. According to Deutsch's web site, he is a full professor at Oxford, and has been awarded "The Dirac Prize". Dirac was a shy, unpretentious man who made VAST contributions to modern physics. Deutsch has not contributed a whole lot to physics, and I don't expect anyone has ever accused him of humility. This is why "A Fabric Of Reality" is such a fascinating document. It illustrates the abysmally poor quality of British physicists in our time. I mean, to go from a Dirac to a Deutsch... As a sequel to this book, I would love to read a book that recounted the history of British science up to our time, with a nice chapter explaining why British physics has declined so precipitously.

Some of the outlandish claims that Deutsch makes in this book are the following: the mind-body problem is solved; P=NP is solved (it's false); the Church-Turing Thesis is a fact; everything that Deutsch dislikes is a form of solipsism. Of course, no details are given to the solutions, as these are just trivial facts, I guess, according to Deutsch.

But after reading the book, probably the one claim that I abhorred the most was never explicitly stated, but a simple corrollary are statements that he makes again and again: every human endeavour is just quantum physics. The reason for this is because human beings are (at the base level) just quantum-mechanical things, everything we do is a result of physics, and therefore while mathematicians (I happen to be a PhD student in mathematics, set-theory in particular) may think that they are dealing with abstract concepts, they are actually dealing with nothing more that quantum effects in their brains (which Deutsch equates with minds). A simple extension of this principle tells us that philosophy is just a quantum-mechanical process, ditto with art, politics, friendships, love, etc.

Of course, something that is hidden in the above idea is a reductionist claim --- that everything can be reduced to quantum effects. Not surprisingly, it turns out that Deutsch thinks that reductionism is wrong. There are several places in the text where Deutsch ends up contradicting himself, or appeals to claims that he thinks are incorrect. (He grants that criticism of scientific theories does not rest on experimental evidence alone, but while claiming that in fact experimental evidence is very low on the scale, for the most part the only criticisms he ends up making are through experimental evidence.)

My advice for anyone interested in the metaphysical or epistemological issues raised in this book --- read the works of a meta-physicist, not a quantum-physicist.

I actually slogged my way all the way through this EXCEPTIONALLY BADLY written book, because of my large interest in the subject matter. David Deutsch should have used a ghost writer for this, as he obviously was not up to the task. He is in love with page long paragraphs, as this book is filled with them. This, of course, reduces readability and comprehension. He couldn't write a clearly written sentence, if his life depended on it.

He also (out of 3,000+ books I have read) is the most arrogant writer I have ever read. He dismisses, cavalierly, and without much explanation, ANYONE who doesn't agree with him, and, though not saying this directly, certainly hinting strongly that he thinks that anyone disagreeing with him is an idiot. I found this attitude repulsive.

I expected to see a lot of experimental research to be quoted in this book, but it is almost totally lacking in any. He wanders around in this book, in bizarre philosophical mumbo-jumbo, that I don't think that he really understands properly, acting as if this proves some cosmic points.

The few facts that he actually provides in this book, are better described in any number of other books. If I had not read previously on related topics, his writing is so bad, that this book would have been incomprehensible to me.

To sum up in a much clearer way, than Deutsch could ever manage, the main point of his book, he basically says that a finite (but very large), number of parallel universes exist, that cover everything that every could, or might have happened; and that this in essence, happened at the moment of the big bang, or within 10 to the -43 seconds after. Time is discrete, not continuous (like a string of pearls looks continuous, but if you break the thread, it is actually shown to be discrete).

Time doesn't "flow", but our conciousnesses are only aware of one discrete moment of time, at a time. (Think, motion picture here. There are 30 static, non-moving picture frames per second, but your mind "fuses" them, into an apparent continuous whole, of an illusion of motion. This is how Deutsch views the universe. ALL the "movies" (universes), that can, could, or might, ever exist; and all possible events of "time", were created simultaneously at the moment of the big bang. Our conciousness, though, is only aware of one, discrete, "movie frame" (discrete bit of time), at a time, within only one "movie" (universe). So, continuous time DOESN'T really exist. It just appears that way because of limitations in our conciousness. Another way to think of it, is that the multiverse is like a video tape store. Each video tape, represents a different universe. Each static frame on the video tape, represents a discrete moment of time. Though all video tapes (universes), and all static frames (discrete moments of time), exist simultaneously, your consciousness can only derive meaning from it, from experiencing the frames sequencially, NOT simultaneously. So, only discret time exists, not continuous time.)

There, now you don't have to bother buying this book. Since he gives almost NO experimental evidence for this point of view, anyway, you don't need to worry about the fact that I didn't offer "proof", either!

For those people whose reviews I read, that seem to think that this book was a stunning revelation; I can only conclude that you haven't read much about this topic, before. Stuff along these lines, existed in science fiction probably since the thirties, and in hard science, for decades.

Whether or not some of what Deutsch believes, is ultimately proven to be correct or not, I don't know. For people in the field pushing parallel universes, though, it might have been better if this book had never been written, as it was such a HUGE turn-off for me.

My 2 cents worth.

Karl

The funny thing is the brilliant intuition of parallel worlds, however that is to be taken. For we see in historical evolution a mysterious parallel effect, in the so-called 'Axial Age', as historical evolution branches into a synchronous phase. So maybe all this is onto something.
The big puzzle: why are all the world's best physicists confused about Darwinism?