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

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For David Deutsch, a young physicist of unusual originality, quantum theory contains our most fundamental knowledge of the physical world. Taken literally, it implies that there are many universes “parallel” to the one we see around us. This multiplicity of universes, according to Deutsch, turns out to be the key to achieving a new worldview, one which synthesizes the theories of evolution, computation, and knowledge with quantum physics. Considered jointly, these four strands of explanation reveal a unified fabric of reality that is both objective and comprehensible, the subject of this daring, challenging book. The Fabric of Reality explains and connects many topics at the leading edge of current research and thinking, such as quantum computers (which work by effectively collaborating with their counterparts in other universes), the physics of time travel, the comprehensibility of nature and the physical limits of virtual reality, the significance of human life, and the ultimate fate of the universe. Here, for scientist and layperson alike, for philosopher, science-fiction reader, biologist, and computer expert, is a startlingly complete and rational synthesis of disciplines, and a new, optimistic message about existence.

390 pages, Paperback

First published September 26, 1996

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About the author

David Deutsch

41 books799 followers
David Deutsch, FRS is a British physicist at the University of Oxford. He is a non-stipendiary Visiting Professor in the Department of Atomic and Laser Physics at the Centre for Quantum Computation (CQC) in the Clarendon Laboratory of the University of Oxford. He pioneered the field of quantum computation by being the first person to formulate a description for a quantum Turing machine, as well as specifying an algorithm designed to run on a quantum computer. He is also a proponent of the many-worlds interpretation of quantum mechanics.

In his books, he also made philosophical contributions. In epistemology, he stressed the importance of explanation, and proposed 'hard to vary' as a criterion for good explanations. In memetics, he gave an account of how memes work, separating them into 'dynamic' or rational memes and 'static' or anti-rational memes. He also advocates optimism, potentially boundless progress, objective beauty in aesthetics, and reason.

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Profile Image for Manny.
Author 29 books13.6k followers
February 18, 2014
In 1619, Johannes Kepler, a theoretical astronomer who earned the greater part of his income from casting horoscopes, published the Harmonices Mundi, the "Harmony of the World". It contained a statement of the Third Law, relating the period of a planet's rotation around the sun to the radius of its orbit; this was the fruit of years of diligent work, and a first-order scientific breakthrough. The book also contained hundreds of pages of the most ridiculous pseudo-scientific nonsense, where Kepler used the shapes of the regular geometric solids to explain the distances of the various planets from the Sun. He later considered the notes of the musical scale and inferred the heavenly harmonies produced by the celestial choir. The serious-minded Laplace, writing his brief history of astronomy a couple of centuries later, is shocked. How could someone as smart as Kepler do this? What was he thinking?

If things work out well for David Deutsch, it's possible that an as yet unborn historian will write similar things about him in the twenty-third century. Some parts of his modestly-titled The Fabric of Reality are interesting and insightful. In particular, he makes a rather good case for the reality of the quantum multiverse, which already seems to have had a considerable effect: I didn't realize it at the time, but I've seen him quoted more than once. Deutsch's presentation combines themes from two of his heroes, Hugh Everett (the inventor of the Many Worlds Interpretation of quantum mechanics) and Karl Popper. Deutsch starts by asking, with Popper, about the nature of the scientific process. He claims that it is primarily about using evidence-based argument to weigh the merits of rival explanations; the best scientific theory is the one that is currently winning the arguments. He persuasively suggests that, on these reasonable-sounding criteria, Everett's Many Worlds Interpretation is in fact the best way to think about quantum mechanics. In particular, it is by far the most intuitive way to think about quantum computers, a subject where Deutsch has played a pioneering role. If you are at all interested in these matters, I strongly recommend reading his clear, lucid exposition.

And then... oh dear. From its logical, eminently sane beginnings, the book gradually descends into more and more bizarre territory. Deutsch introduces his eccentric personal take on the Church-Turing thesis, and uses it to derive all manner of odd consequences. He tells us that everyone who has ever worked on the philosophy of mathematics has got it wrong: mathematical proof is part of the physical world, and thus essentially bound by the laws of physics. He spends thirty pages discussing time-travel, and concludes that it is perfectly feasible in the quantum multiverse. In the last chapter, he throws aside all his inhibitions and outlines an extended fantasy, based on the work of Frank Tipler, which forecasts the future evolution of the cosmos. Intelligent life, we read, will inevitably learn to control first the Sun, then the galaxy, then the whole universe. As we head for the Big Crunch, the future civilization will take control of the gigantic gravitational energies released to create a godlike cosmic consciousness. This will exponentially slow down time, so that our distant descendents will subjectively never die, living forever in the final moments of the universal collapse. All of this, if I understood correctly, is mandated by the extended Turing Principle: the results, startling as they seem, just follow from the laws of physics. The only thing that's not quite clear is whether the godlike future being will resurrect the dead and put them in a Heaven-like environment. Tipler, a Christian, thinks it will, but Deutsch is inclined to disagree.

It must have been disappointing when dark energy was discovered the year after, implying that there wouldn't be a Big Crunch after all. But Deutsch doesn't come across as the kind of guy who sits around and mopes over his setbacks. My guess is that his new theory is even better, and when he and Kepler are resurrected together some time in the infinite future I'm sure they'll have no end of fun comparing notes.
Profile Image for Infinite Jen.
83 reviews290 followers
December 21, 2022
Friends, I’d like for you to entertain, for a moment, how a multiplicity of universes informs the path finding algorithms of a booze-humping photons throughout the cosmos. Anthropomorphize and embody this atomic lush as the vicious scourge of your diminished dopaminergic vitality has fully adorned itself in the finery of sex dungeons, wheezing through the teeth of a tiny zipper like a reedless gunmetal harmonica, a long note of spittle and eagerness. Threatening to collapse the wave-function of your probabilistic chicken tendies if you do not head for the liquor store, refractive indices be damned.

Let us further imagine that, rather than consign Hugh Everett’s Many Worlds interpretation of quantum mechanics (which posits the literal reality of the universal wave function sans collapsing) to phenomena of scale which appear as radical discontinuities to our terrestrial experience, we take all that it implies fully on board and face the strange realit(ies)y it offers.

In one version of this story, stirred by the motive forces of rabid chemical dependency you head in a straight line for Woody’s (your local dive) in solipsistic fashion, assigning no particular weight to the fictional actions of other agents who could willfully or accidentally visit harm upon your quanta if possessed of actual identity. You don’t even flinch as horns blare and a disgruntled particle shouts, “I traversed your mother’s double-slit last night, asshole!” Being of no consequence that your mother was either discrete or continuous in bed, you reach your destination.

In another version of this story, you travel inefficiently and at such an angle that you pass through the small apartment of a complete buffoon named Jen, who is presently writing a review for a book she just finished. Unceremoniously corralling her thoughts like feral hogs, high in the saddle of her vices; nicotine, whisky, caffeine, and Capri Sun, propelling the beast forward. Steadily escalating threats issue forth from the young lady, a snatch of which goes; “What’s wrong with fruit drink pouches you joyless prig? You think you’re too good for FRUIT PUNCH, STRAWBERRY KIWI, PACIFIC COOLER, LEMONADE, WILD CHERRY, TROPICAL PUNCH, INEFFABLE TAINT, MOUNTAIN COOLER, SPLASH COOLER, CUM BASTARD, STRAWBERRY, GRAPE, TIT SWEAT, COASTAL COOLER, RED BERRY, ORANGE, SURFER COOLER? You have all the warmth and charm of a walleyed pike. You should go into the woods and leave everyone alone! Say one more thing about fructose and we’re FINISHED!” Across her monitor the following observations have been made:

What I liked: One of the best explanations of The Many-Worlds Interpretation I’ve read. A thorough examination of the implications which follow from it, namely that all possible outcomes of a quantum event are realized in alternate worlds or universes, of which there are very many, or perhaps an infinite number. Rather than Schrödinger's sex panther existing in a superposition of life and death and only realizing one of those states through the introduction of an observer, Everett’s theory suggests that the cat is both alive and dead before the box is opened, but these two different states exist in alternate branches of the multiverse which are equally real, but do not interact with one another.

As a pioneer in the field of quantum computation, the author does a good job of explaining how this view of reality means that quantum computers would essentially be performing computations across multiple universes at once, while the various qubits are in a state of quantum decoherence. This is intuitively disturbing and insanely fascinating.

What I was lukewarm about: A large section of the book is dedicated to expounding Deutsch’s brand of epistemology, wherein he aligns himself with Karl Popper and elevates the notion of fallibilism to the central pillar of human understanding. (fallibilism is the philosophical position that all human endeavors — attempts to create knowledge or achieve anything — are subject to error. There can be no foundation upon which to build “reliable”, “probable” or even “justified” knowledge. The logic of this is very simple: any foundation, any “reason to believe” you got things right needs to be itself justified. Therefore, all attempts to ground knowledge in any form of justification leads to an infinite regress.) He then proceeds to take a pick axe to inductivists, instrumentalists and reductionists. This was interesting, but I couldn’t help but feel that some of the stand in arguments for the opposing philosophies were somewhat bloodless, like unto an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed and assembled into the shape of a humanoid, as they say.

Some controversial claims are then made about the nature of mathematics and the viability of time-travel.

What I disliked: The book becomes pure singularity based science fiction involving a universe spanning consciousness that slows down the subjective experience of time near the Big Crunch which confers a kind of immortality on our far-future descendants.

Passing through this den of fruity iniquity you arrive at Woody’s in oblique fashion.

In another version of this story, you loop around the entire globe, which, being a photon, is not as arduous as it sounds.

In another version you pass through a battlefield where idealistic machines wage war over the nature of science, espousing, in glorious carnage, the respective ideals of their commanders (Einstein & Niels Bohr). If only you could inform them that the hegemony of the Copenhagen Interpretation of Quantum Mechanics is not so complete, and that, with all its apparent weirdness, quantum physics could still admit determinism.

In another version.
In another version.
In another version.
In another version.

All equally real?
Profile Image for Richard Derus.
2,890 reviews1,919 followers
December 17, 2022
Rating: four exuberant, excited stars out of five

There is more than enough room in the Multiverse for reality-based understandings of the spiritual world to render gawd obsolete.

Clear, well-turned prose, ample illustrative examples of his points, and a beautifully thought-out explication of the bizarre nature of reality as explained in the far reaches of physics. The fact that Richard Dawkins is cited as an inspiration for Mr. Deutsch's work should forewarn the spiritual seekers in the audience to avoid this book at all costs. It takes a very clear stance against there being a supernatural agency in the workings of the Multiverse.

Instead, Deutsch says that the Multiverse is weird enough to contain answers to all questions couched in numinous terms and to explain all phenomena and experiences the species has filed in the "supernatural" bin. His arguments are presented without condescension or hectoring, which is a common failing in the prose that wishes to "debunk" the spiritual experience. He simply explains how the experiences fit into the framework of the Multiverse. From there, he says, it's up to you the reader.

THIS is an attitude I can endorse and enjoy. I dislike the spiritual imperialism that says, "My way is Right and all others are Wrong," and equally dislike the materialist dogma that "There IS no spiritual and those who imagine there is are deluded and foolish." I want the arguments presented and then leave it up to me to decide what to do with the information presented. Please don't do my thinking for me! And that, laddies and gentlwomens all, is what I feel Mr. Deutsch makes an overall successful stab at NOT doing. He favors the material explanation, and makes no bones about it; but he is very reasonable and reasoned in his advocacy, not shrill or hectoring.

A well-done work of enduring value in the cultural conversation about the nature of reality as we find it.
November 2, 2020
What do we see when we look at things we imagine are real?
How real is reality? And what is it made of?
What would a frog (who seems to have particularly light-sensitive eyes) see when confronted with a light source that is placed far enough that light is getting sent to it in quants (as opposed to steady light rays)?
These and other titillating mysteries are made accessible to people light years from physics by DD.

... coherence, elegance and simplicity, as opposed to arbitrariness and complexity, though none of those things is easy to define either. (c)
Again we were too parochial, and were led to the false conclusion that knowledge-bearing entities can be physically identical to non-knowledge-bearing ones; and this in turn cast doubt on the fundamental status of knowledge. But now we have come almost full circle. We can see that the ancient idea that living matter has special physical properties was almost true: it is not living matter but knowledge-bearing matter that is physically special. Within one universe it looks irregular; across universes it has a regular structure, like a crystal in the multiverse. (c)
Not only is there constant backtracking, but the many subproblems all remain simultaneously active and are addressed opportunistically. (c)
We do not experience time flowing, or passing. What we experience are differences between our present perceptions and our present memories of past perceptions. We interpret those differences, correctly, as evidence that the universe changes with time. We also interpret them, incorrectly, as evidence that our consciousness, or the present, or something, moves through time. (c)
Profile Image for Mehrsa.
2,234 reviews3,657 followers
February 4, 2019
The beginning of this book was really fascinating and got me thinking, but then the last half was really hard to get through because he got bogged down in super scientific details that I just didn't care about. I think the book is probably outdated at this point too because though we aren't closer to a "theory of everything," we have pushed forward on a lot of the theories he discusses in this book.
Profile Image for Bruce.
439 reviews73 followers
June 22, 2010
I've been blowing through books lately, and it may be because I am at present too summer-shallow and absorbed by theater books to give works like this the necessary patience. So thank all the Neil Simon currently burning up space on my night table, and take this review for what it's worth.

I went into this on the strength of recommendations that had me expecting something like Michio Kaku's Physics of the Impossible, but found instead a ponderous mess that left me in full-bore skim mode after only the second chapter. Deutsch came across to me as patronizing and intolerant of those who do not share his views (which, he confesses, are most scientists and writers). He dismisses his colleagues as hopelessly reductionist (wanting to reduce all observable phenomena to the behavior of elementary particles) or positivist (wanting to bother only with theories that can be used to predict observable phenomena), complaining persuasively that such philosophies fail to explain our world in a way that can be rearticulated without access to a blackboard.

So far so good. Like any philosopher worth his publishing salt, he Humpty Dumpties a lot of terminology to suit his own purpose, and so "Theory of Everything" changes from meaning the grand unification of relativity and quantum theory (allowing observable phenomena to be described by a single maths of electromagnetic-gravity or some such) to a one-sentence explanation that ties together quantum theory, parallel universes, epistemology, and evolution.

Deutsch's explanation of interference patterns in light is done without recourse to wave theory (the word does not appear in the index and probably does not exist in the book, not even for purposes of theoretical rejection); his exegesis of quantum theory is all about individual light particles -- photons and their shadow counterparts. The latter exist only to create interference and an infinitude of parallel universes, identical in all respects to ours but for the photon that passes or fails to pass through a given experimental filter. All this is well and good, but Deutsch never bothers to explain why such a worldview -- which, having earlier decried such definitions as pseudoscience unworthy of our consideration, he allows to be unobservable and undocumentable -- is worth bothering with.

Worse, having ridiculed as worthless the opinions of those who would describe planetary movement as resulting from angelic exertions (how then to describe the angels' motivations?), he goes on to glibly speculate that in other universes yet unseen other versions of him are writing the same words more elegantly, writing on another subject entirely, or perhaps not writing at all but instead getting a cup of tea. Never once does he explain how the horribly complicated chain of interfering photons and shadow photons across all of these imagined parallel universes might impact our observable world. Or how we could observe it if they did. Or why such a nonexplanation represents an improvement on the angel idea?

The rest of the book is all of a piece with this. I don't mind trying to believe 6 unbelievable things before breakfast, but I do demand along the way that my mysterians demonstrate either internal consistency or a bit of humility. Deutsch offers neither.
Profile Image for axe.
71 reviews16 followers
August 31, 2012
This is a weird book to review. There were pages where I was vociferously arguing with a (imaginary) Mr Deutsch, and pages where I was nodding along like in a class room. So a good book in all, perhaps even a great one.

Deutsch is at his best when explaining Quantum Theory, and surprisingly good when talking Epistemology. In the former he has some of the clearest expositions I have ever seen, and some very appealing explanations for old chestnuts. In the latter, although he does some convolutions I am not particularly found of, but I will be forever grateful to him for resolving my ambiguous feelings on Popper. To wit, I like most of the worldview that Popper espouses, but I disagree vehemently on certain points. Mr Deutsch has had the novel idea, that 'so what ?'. That most founders of revolutionary theories are standing sans foundations, and will of course make mistakes. I can be a Popperian, without agreeing with all that Popper says. Huzzah !

On the other hand, Deutsch's insistence on explanations as a solution for the problem for induction, (and of the role of intuition and self evident truths in mathematics) is problematical. Also inconsistent with some of what Deutsch himself says - namely that he, unlike Penrose, does believe that the human brain is a classical Turing Machine. This despite him pointing out a whole host of such inconsistencies in other viewpoints. Although the author does a fascinating job demolishing inductivists, instrumentalists, and reductionists the argument seems a tad unfair considering that the opposing parties can hardly talk back. This is especially highlighted when he pushes Everett's multiverse worldview. To be fair, he has described several tests to distinguish between the Copenhagen and the MWI interpretations, just not in this book. Then there is the, ahem, pussyfooting, around the Kuhn philosophy on the 'heretic in the scientific orthodoxy'. And of course, Mr Tipler's Omega point, on which I reserve comment.

It may sound as if I am complaining a lot for a book I gave five stars to. But that is not the case. A book is not a conversation. At best it is a discourse - and it should be judged as such. This one does what the best lectures do, they make the audience go back and talk about them. Or in my case, write about it.

Profile Image for Gary  Beauregard Bottomley.
977 reviews580 followers
March 10, 2019
I would suggest that my other self, Gary Beauregard Bottomley, in a parallel universe should not waste his time reading this book. It is deceptively misleading. Explanation is not the foundation for reality as the author tries to show. Explanation does not make the transcendental deduction real.

Samuel Johnson does not refute the Reverend Berkeley by kicking a rock even if the rock kicks back. Hume’s experiences are not a sufficient foundation in themselves. Kant wisely realizes that both (Berkeley and Hume) are wrong since they make truth dependent on an exclusive foundation of either the mind (scientific anti-realist) or experience (empirical) thus Kant merges the two and creates a transcendental deduction, but the explanation for reality is not the reality itself as the author will say; it is only made whole through the transcendental deduction that is within the faculty of understanding.

The measurement problem in physics is real. Feynman said in one of the seven lectures of ‘The Characteristics of Physical Law’ that all the mysteries of physics are contained in the double slit experiment. There is a paradox at the heart of being human. The ‘Laws of Thought’ (see Schopenhauer or Bertrand Russell for further elaboration) break down. The mutually exclusive law doesn’t always work for our best explanation of the world. The author gives a fix to this vexing paradox.

The author makes the ontological foundation for reality derived from these four pillars: quantum physics, epistemology, Dawkins/Darwin Evolution, and Turing universal machines. His fix requires a infinity of other universes that are process driven as opposed to event oriented. (Conversely, Bertrand Russell, who is often quoted in this book, believed that all understanding came from experiences of events and when asked about the White Cliffs of Dover replied they were just a slow acting event!).

The author appeals to Descartes’ cogito. When one does that, one should remember that Descartes first assumes away an objective world and gets subjective certainty only after having done that (so, of course, if you assume the world outside of yourself away, all that remains is what is within you. Furthermore, see Avicenna’s Floating Man for why that might be a foolish starting point). The author needs subjective/objective in formulating his arguments, because he says in multiple ways that ‘there is an objective truth out there’ and he seems to think that explaining a phenomena makes it objectively real as he’ll say is true for mathematics. Einstein needed ‘hidden variables’ in order to explain quantum physics and assumed away ‘spooky action at a distance’ in order to explain and keep his scientific realism, but today we all know there are no hidden variables and entanglement is real. Hypothesizing infinite universes with processes instead of events will be able to explain entanglement, but perhaps there are other unknown possible explanations waiting to be found, or maybe we just live in simulation and can’t break out. (By no means do I reject the MWI, I just think this author’s justification is flawed overall).

Hegel said certainty is within us and truth is outside of us and he will dialectically resolve the paradox allowing for Heidegger to take that by inverting Husserl’s ‘bracketing’ of the world to get his being-in-the-world through present-at-hand, ready-at-hand and being human (Dasein). I mention this because this author doesn’t follow in the method of Hegel or Heidegger; rather he often brackets the world extracting an objective reality within a subjective frame of reference for his conclusions. He’ll also often give false dichotomies such that it’s either the Copenhagen Interpretation or his Hugh Everett III MWI, or it’s either Popper or Kuhn that are our choices. Sometimes the world doesn’t need to be binary for our potential reasonable options (hence my Kant reference in the first paragraph).

The author has a scientific realism with progress underlying his world view. I think it’s possible to say that science sometimes replaces what came before it in such a way that we can justifiably say that we were wrong previously (phlogiston is Kuhn’s example). For example, at one time F=ma was considered tautologically true by Mach and most others, but Einstein changes that completely (acceleration needs a relativistic correction), and the very concept of Force (or mass, or acceleration) is different after Einstein then it was before thus changing almost everything in our understanding of the physical world. Our concept of the Sun changed because we finally had a better new way (not a best way, but definitely a different way) to explain how the Sun could be older than the earth because we could say fusion kept it hot and gravitationally balanced. How we understand the Sun changed with Einstein from how we understood the Sun with Newton. We use the same word ‘Sun’, but everything we understood about it was redefined with different implications and understanding. It was no longer a fiery ball of hot gas, but it was a controlled nuclear fusion helium producing entity with a whole lot of quantum tunneling transpiring.

The author will show that his explanation for the double slit experiment by invoking parallel universes explains free will within humans. That’s actually a non insignificant part of the book and it is a big part of his argument. Augustine gives the Christian West its concept of free will, and he said that it is the power within humans that was analogous to the power that God Himself had which allowed him to freely (but not necessarily since for Augustine God is all powerful and nothing can make an all powerful being do something necessarily) create the universe. My only real way I understand ‘free will’ is by hypothesizing a God who judges by sending some to hell and others to heaven and wonder how that God would make His decision. My gut tells me an all knowing, all good, all wise God would never send someone to hell because He (She, or It) would always know that but for the Grace of God there would go each individual and the free will that we possessed was just an illusion because time, chance and circumstances created the person and his actions through a long series of cause and effect steps. (BTW, Schopenhauer in Volume I and Volume II of his ‘Will and Representation’ ends each volume with saying it is through God’s Grace alone that we thrive because Schopenhauer’s deterministic philosophy doesn’t allow for people to control their own destiny and I actually tend to agree with that with or without a multi-verse to ‘explain’ free will and reality as a whole).

Free will in a human relates to whether a machine can think. The author will say that in order for us to know if a machine is thinking we will have to understand (explain) how it is thinking and we will know that through using his multi-verse paradigm. I would say that even within myself let alone others who may or may not be a machine, the closest I can get at is ‘I want what I desire, but I don’t desire what I desire’ and I’m never able to see into the heart or head of anyone (even myself) and the most I ever get to see is their actions or hear their words and interpolate through a kind of transcendental deductivism.

This author’s speculation on quantum computers from the 1998 perspective is fascinating. Quantum computers are real today, but they were speculative at the time of this book. When the author talked about quantum computers or Turing is when he was at his best. Otherwise, I think most of this book was not worth while today and was heavy handed in its presentation and lacked philosophical rigor. Though, I did not know anything about Frank Tipler and his Omega Point philosophy and I want to learn more.

Contrary to this book, I think Reason (with a capital ‘R’) is a fictional label we use to fabricate explanations for our understanding of reality. The author makes Reason through our explaining reality integral for his ontological system. I know a lot of what I wrote above won’t be understood and I wrote things in short hand such that I’m fairly certain if Gary Beauregard Bottomley (GBB) gets to read this review in a parallel universe he’ll understand fully what the real GBB meant and probably would just skip this book and read Tipler’s book instead.
Profile Image for Gendou.
585 reviews261 followers
December 31, 2019
The nicest thing I can say about this book is that Deutsch offers his own "novel" opinions philosophy of science. Unfortunately he's reached those opinions by collecting logical fallacies like a hoarder collects old newspapers. He's basically a crank, having worked largely in isolation for decades, who thinks he's got a grand new theory that's underappreciated by academics.

Straw Man
His favorite logical fallacy to employ is the Straw Man. He has Plato's Dialogues style arguments with a fictional "Inductivist" who does a piss-poor job at countering his poor philosophy of science.

Special Pleading
His second favorite is special pleading with a side of good old fashioned denial. He simply denies the validity of other interpretations of Quantum Mechanics (QM) besides the Many Worlds Interpretation (MWI). He doesn't give sufficient description of other interpretations or their strengths. For example, he's a particle chauvinist, refusing to acknowledge that quantum fields "real" and thereby dismissing all interpretations that require quantum fields (all of them except MWI) to be fully realist theories. He counts up evidence consistent with QM and calls it proof of MWI, all while failing to mention the obvious fact that these lines of evidence point equally to all other interpretations of QM. He does this, smugly, over and over, like a child sharing fantasy make believe, all excited because he thinks the adults in the room are actually buying it.

Category Error
Another fallacy he falls prey to is the category error. For example, he thinks that we can infer from the Turing Principle that there will be an Omega Point at the end of time. It takes a lot to explain why this is wrong in detail, but suffice it to say he's got the arrow of inference backwards. He mistakenly promoted the Turing Principle from a descriptive idea into a prescriptive law.

His arguments often contradict well-established science, and even one another. For example, he's got this theory of time as an order we impose on separate snapshots. The snapshots are just "out there" and we sort them in an order from which time and the laws of physics emerge. It's a neat idea, if you're high on drugs, but we know this is false because of General Relativity. Later in the same chapter he "predicts" time travel is possible but you go to the future/past, but in a parallel universe. But this contradicts his idea of snapshots wherein causality emerges from the interrelationship of snapshots. Because there's so vanishingly few snapshots that look like someone from the future in another universe popping into existence, it's as good as forbidden by his own rules! And can't be caused to happen by any "casual" means, because it doesn't obey the laws of QM.

He picks a fight with Weinberg over Instrumentalism [see page 129]. Here Weinberg is saying that, given dual interpretations of the same underlying theory, we can be instrumentalist about choosing which interpretation to use. Deutsch argues that explanatory power of theories matter so we shouldn't feel so free to select any dual interpretation. He wants us to pick one with the most explanatory power, not the most instrumental potential. But here he's equivocating between how we know if a theory is true (explanatory power matters more than instrumental potential) and which interpretation of a well-supported theory to use (instrumental potential matters more than explanatory power).

This last one may be subtle, but this is his main trick for shutting down ALL COMPETING INTERPRETATIONS of quantum mechanics! That's the core thesis of his book!

And it's one big logical fallacy.
Profile Image for DJ.
317 reviews232 followers
March 21, 2009
This is David Deutsch's plea to the scientific world to tear down the separation between theory and their own worldviews and truly own the picture of reality that modern physics has painted for us. He begs that we take our theories seriously as fundamental paradigms and not set them aside as interesting little quirks of Nature. In particular, he makes a solid case for embracing the "many-worlds" interpretation of quantum mechanics (given my greenness on this subject, I'm reserving judgment until further notice).

His central idea, however, is a draft of an approach to a theory of everything that melds quantum theory, the theory of evolution, epistemology, and the theory of computation.

As for quantum theory, this was book provides one of the best popular introductions to quantum theory and quantum computation that I've seen. Certain ideas (such as the concept of parallel computation in the multiverse) only clicked for me after hearing them from Deutsch.

As for epistemology, Deutsch commands a knowledge of his contemporary scientific philosophy rivaling that of Galileo, Newton, and Einstein - men who were not afraid to dabble in the "softer" science of epistemology. He drives home the mistakes of induction-based scientific philosophies and presents the case for adopting a Popperian philosophy, emphasizing the relative problem-solving efficiency of a theory as criterion for its success. The reading can be a bit rough though if you've never been introduced to Kuhn, Popper, or other scientific philosophers before. I'd highly recommend reading some of their works before picking up Fabric of Reality (I had read some Kuhn but no Popper and wish I had).

His introductions to evolution and computation are noble efforts but again, this book is much richer if you have a bit of a background in these subjects. I'd particularly recommend Richard Dawkins' The Selfish Gene as a prerequisite for Deutsch's discussions.

I was extremely intrigued by the seeds of a multiverse theory of knowledge that Deutsch planted as well, something I intend to further explore as I gain more background in quantum theory.

Given the radical and rigorous nature of this book's explorations, I found Deutsch's use of chapter summaries and glossaries extremely helpful in structuring my reading. I think this feature is an excellent take-away for any science writer.

All things considered however, the fact that this book is not stand-alone and can be confusing at times without the proper background lead me to grant it only three stars.
Profile Image for Alberony Martínez.
471 reviews34 followers
February 8, 2021
Como sistema de conocimientos que es la ciencia sobre la realidad que nos rodea, hablar de la realidad, y mucho más de la Estructura de la realidad, creo sentirme el menos indicados, cada quien con su conjunto de método procesal para dar una argumentación, hasta para esto hay que tener cuidado, para no encontrarme con unas pléyades de doctores en ciencia, que juzga un libro como bueno o malo, pero gustaría ver el suyo, a ver si es flores que le tiraran, y como vemos a través de este libro, la ciencia es movimiento, lo que hoy se puede afirmar, mañana podría verse esa afirmación como algo no del todo real. Así, para realizar una recomendación respecto este libro, y más en asunto de ciencia, siempre recomiendo ir en pos de la indagación, ir más allá, y no presumir que lo que dice un escritor es falso.

La lectura de La estructura de la realidad de David Deutsch es un explicación penetrante a la nueva física, y por esto, a la llamada a la física cuántica, donde su teoría se apoya en la realidad que depende de la percepción, desdibujando los bordes entre el fenómeno físico y los aspectos invisibles y abstractos del Universo durante siglos. Este libro es un viaje por el tiempo, una interpretación sobre las computadoras cuánticas y el multiuniverso, como hace referencia en la película ‟Avengers: Endgame”. Para el escritor, la teoría cuántica contiene nuestro conocimiento más fundamental del mundo físico. La multiplicidad de universos resulta ser la clave para lograr una nueva visión del mundo, una que sintetice las teorías de la evolución, la computación y el conocimiento con la física cuántica.

Es un excelente libro, del cual debemos ir con toda la disposición de que lo que nos dará es ciencia, no es un libro de ficción, una novela, es ciencia, es un texto que nos conecta con muchos temas en la vanguardia de la investigación y el pensamiento actual, como las computadoras cuánticas, la física de los viajes en el tiempo, la comprensibilidad de la naturaleza y los limites físicos de la realidad virtual, el significado de la vida humana y el destino final del universo.
Profile Image for Phil Scovis.
65 reviews1 follower
November 21, 2012
Most popular books on Quantum Mechanics suffer from an apparent need to overawe the reader with the weirdness of it all, stressing the old saw that if you think you understood it then you didn't. It should come as no surprise, then, that the Q-word has become associated with whatever woo-woo philosophy anyone cares to attach to it.

I can only think of two books on the subject that treat the reader with the respect due someone who can understand the basic concepts even if the mathematical details are reserved for the elite. The first is "QED" by Richard Feynman, in which does an astounding job of introducing the fundamentals of Quantum Mechanics without ever mentioning "particle-wave duality". The other is "The Fabric of Reality", which addresses the philosophical implications of our most advanced theories.

Author David Deutsch's main villain is "instrumentalism": the philosophy that the purpose of science is to make predictions while remaining firmly agnostic about the nature or existence of objective reality. Instrumentalism, he believes, has infected QM right from the start, a circumstance which has greatly hampered our understanding, both at the popular and egghead levels. The alternative is to regard our scientific theories as reliable descriptions of reality. Right from the preface, Deutsch laments that it is even necessary to suggest that we consider our scientific theories might be true.

Deutsch champions the so-called "many-worlds interpretation" of QM, in which the universe is part of a vast multiverse of slightly-interacting other universes. This seems to me to be a radical explosion of the extent of reality, compared with the almost unnoticeable phenomena that required the development of QM theory. To Deutsch, the only alternative is the one which most physicists have taken: that QM is nothing more than a method of calculating and predicting phenomena whose causes are beyond our understanding. The many-worlds interpretation, on the other hand gives us a true picture of reality (and predictive power as a bonus).

Deutsch also explores virtual reality, universal computation, and evolution as fundamental to our understanding of reality, calling these and QM the "four threads" of our current understanding. Along the way, he takes apart widely believed orthodoxy, and puts forth some heretical theses: Space-time, as popularly imagined, is self-contradictory and false. Mathematics is not justified by logic, but is on a level with physical theories. Science is not based on induction. Fundamental theories need not be reductionistic. Time-travel is not paradoxical. Humans (or more generally, intelligent life) really are the most important thing in universe. And so on.

Perhaps surprisingly, Deutsch gives thoughtful consideration to the eschatological theories of Frank Tipler, widely considered to be something of a crank. While Deutsch strongly criticizes some of Tipler's conclusions, he finds the general idea of an unbounded future not only plausible but inevitable. If I may attempt a paraphrase, this is because our theories of reality would be more profound if Tipler's Omega Point actually existed. At this point I balked, realizing that I hadn't quite swallowed Deutsch's main thesis, and I was suddenly aware that I was at heart one of his ridiculous "crypto-inductivists".

Deutsch has been criticized by other reviewers as being "arrogant" in his presentation. I know that brilliance often looks like arrogance, and I am not versed enough in the subject matter to judge the author in this case. I will say this: he says what he believes to be true as if it were true, using no weasel words, and admitting no exceptions.
Profile Image for Murilo Queiroz.
144 reviews15 followers
January 7, 2020
What an amazing, life-changing book! I could recommend it by its very convincing defense of the Everett's Many-worlds interpretation of quantum mechanics alone, or Karl Popper's Epistemology, but it's the synthesis of the four strands mentioned in the book (the other two are Darwin-Dawkins Evolution and Turing's Universal Computation) that makes this a must-read work about Philosophy of Science.

A curious anecdote: during a very interesting discussion about the books I read in 2019, in the BBQ after an alumni meetup / research workshop in my alma mater, I mentioned that this year I loved Neal Stephenson's Anathem and Fall, or Dodge in Hell. And I also said that Robert Sapolsky's Behave: The Biology of Humans at Our Best and Worst is one of my favorite books, because of its posture with relation to explanations, and I asked if someone could point me to books about metamodernism.

Then someone I just met told me to read The Fabric of Reality: The Science of Parallel Universes--and Its Implications and I confess at the beginning I didn't understand why... But after finishing the book I must agree that it has a lot to do with themes of all these books, which was an amazing surprise.
Profile Image for Jason Pettus.
Author 18 books1,279 followers
June 10, 2019
DID NOT FINISH. I picked this up because Neal Stephenson mentioned in a recent interview that it was the main nonfiction book to inform the details of his newest novel, the virtual-reality morality thriller Fall: Or, Dodge in Hell, and I thought it might be interesting thing to make my way through while waiting for my chance to secure a copy of Stephenson's book. And it's interesting no doubt, an attempt by this admired theoretical physicist to explain to a non-science crowd how it is that we use the theories behind quantum mechanics, computation, evolution and epistemology (i.e. the "scientific method") in order to create the most thorough and complex understanding of reality that we as humans can possibly make, which at our present rate is rapidly leading us to the much-ballyhooed "universal theory of everything" that will supposedly in the future let us explain each and every detail of the universe through one simple, interconnected concept. But whoo boy, this stuff just threatened with every sentence to go straight over my head; and when, after a week straight of reading for several hours every day, I found myself still barely 20 percent done with the manuscript, and just barely understanding what the hell Deutsch was talking about in the first place, I finally decided to throw in the towel, especially since my copy of Fall is now here. By all means, take on this fascinating but headscratching book if you can think you can handle it; if you manage to finish it, rest assured knowing that you are officially a better person than I.
Profile Image for Carlos Scheidegger.
70 reviews18 followers
January 31, 2012
Thought-provoking, but confusing at parts, and over-reaches a bit. The arguments about the importance of explanations are very good, but his attempt to tie together "the four strands" (epistemology, evolution, quantum theory and computation) falls fairly short.

- Computational complexity issues were simply brushed aside during his arguments about virtual reality - that is a real shame, since efficient simulability could be said to be *the* central issue of computational complexity, and clearly has impact in Deutsch's arguments about the universe's ability to create perfect representations of itself.

- His argument about virtual reality, physically possible universes vs logically possible universes, and in particular his "diagonalization proof" that not all logically possible universes are physically possible, was sloppy. Diagonalization proofs are pretty delicate, and Deutsch simply failed to argue successfully that it applied in his case.

- His understanding of proof theory and the critique of constructivism was bizarre. From the writing, it seems Deutsch misunderstands the role of proof theory withing mathematics. Perhaps a bit ironically, the best description of metamathematics I know of comes from Andrej Bauer, a constructivist himself. From memory, the idea is that Proof theory is simply the branch of mathematics which turns the effectiveness of formal thinking into the process of mathematics itself. Specifically, proof theory does not set out to reduce all mathematics to formal manipulation; that is a strawman interpretation of the process.

T book is easily worth the read, but gets 1 point deduction from the issues above, and 1 point from being a bit meandering at parts.
18 reviews1 follower
January 1, 2020
Holy shit. 🤯 Mind is fucking blown. 🤯 World view is completely changed. 🤯 I’m gonna go read a couple of novels to clear my head, and then I’m gonna read this again.
Profile Image for Parker.
122 reviews
December 4, 2021
Four Strands of Reality:
While complexity of our knowledge grows, so does the depth of our knowledge. These four fundamental strands of reality are increasingly intertwined:
1. quantum physics (Everette)
2. epistemology (Popper)
3. universal computation (Turing)
4. evolutionary life (Darwin-Dawkins)
These explanations, while each seems narrowly focused at first, when taken together are the most straight forward unified explanation of our reality that we have at this point. While each still has holes in their theory that causes them to be individually ignored and often challenged, the parallels between them are amazingly summed in the idea of a virtual reality program looping the same 5 minutes over and over, ie time travel.

Each strand can be act as someone's world view (ie we're living in a simulation) or be critiqued on its own as naive (ie Hawking's critique of life being the most important strand by saying we're just a remote patch of organic scum ). But to defend them the strands must be viewed together: combined evolutionary life with computation and physics and we have the ability to change the sun (if we want survive the solar system).

Complexity vs simplicity... As we learn more and more facts it can seem like there is a never ending increase of complexity. Facts are not knowledge and real knowledge is increased not through induction (studying data and learning what predictions we could have made/identifying laws), but by deduction and explanation. Science grows knowledge by dreaming up better explanations that solve more problems (as long as it meets the Popperian criterion that is IS falsifiable). So as we develop better explanations our knowledge becomes both broader and deeper. Simply broadening our facts means specialists are needed to understand any single field of study fully. But problems aren't organized in fields. The depth of our knowledge increases as we develop better problems solving explaination. Depth is winning vs complexity and we are approaching a theory that underlies everything. This means we ultimately will be able to understand all of reality. How can this be so?
There are 4 pillars of our reality that are required to understand the nature of the world and grow knowledge:
1. quantum physics (Everette)
2. epistemology (Popper)
3. computation (Turing)
4. evolution (Dawkins)

Outside Reality: there is a large class of theories (all a variant of solipsism) identified by the way they arbitrarily draw a lines at the limit of what they define as Reality. Drawing the limit of reality around your own brain=solipsism; around the Earth=Inquisition; at 4,000BC=creationism; at the material world/heaven=Christianity and Islam; outside the brain=behaviorists; outside of our direct and self evident intuition=mathematics (specifically intuitionists). All these theories say it's just a game outside their definition of reality, and while they solve a specific problem of their author, if you take them seriously they provide no explanation. So is everything real? No, many things are false.

A Criteria for Reality: anything that kicks back. An explanation that says this isn't correct requires additional complexity where the more simple assumption (realism) provides better explanation. Galileo's discoveries showed that scientific observations were reliable and helped solve problems, despite being open to later refutation or clarification. Evidence is everywhere and a fabric of our reality, if you kick something it kicks back, this leads to knowledge.
"Thus science and other forms of knowledge are made possible by a special self similarity property of the physical world. Yet it was not physicists who first recognised and studied this property: it was mathematics and computer theorists, and they called it the universality of computation (the 3rd strand)."
Universal computation is possible, which means reality is structured in such a way that a knower can comprehend the laws of physics. The laws of physics existing mandates that reality is comprehensible.

Inductivism: justifying truth through logical deduction is not the same thing as making an argument for a better explanation. With an argument you don't rely on a justification or an appeal to logical proofs/senses/authority, you only need to show that it better solves a problem by its given explanation.

Life/evolution: The advance of science seems to knock life off the registration if important phenomenons of nature. But we now know that genes do not experience our environment because they have no senses, but they do embody knowledge about their niche by manufacturing a kind of virtual reality where they can replicate. But not only replicate, it's the ability to create an embodiment of the physical reality that lets them replicate. Life is the physical embodiment of knowledge. Knowledge bearing matter (like genes, but not only living matter) has the ability to maintain it's structure throughout the multi-verse. The only way to identify junk genes in a genome is to figure out which could be modified in other cloned/parallel universe but the organism would remain the same. The Turing principal shows us that life and virtual reality use the same universal computation to embody reality.

Time: the flow of time is an illusion, and the classical view of the universe where there's both a series of discrete moments and a changing cause-effect flow happening. But spacetime (block universe) physics wouldn't allow any change. Time is a quantum concept. the quantum concept of time is that all moments are just special cases of other universes and are only related to the current moment by the laws of physics. We discover those moments (past and future) rather than other moments in the multi-verse because the laws of physics link them to us (quantum interference). But that is a solopist error because those other multiverse moments are just as objectively happening, we just don't have access to them.

Free Will: The fact that some moments exist now means that future snap shots all branch from this one. Just like true knowledge can be represented by the fact that the same truth exists in many versions of the multiverse, we can see that certain choices we make are repeated much widely in the multi verse.
Profile Image for Wendelle.
1,519 reviews25 followers
March 19, 2022
David Deutsch is the Oxford physicist who devised the extension of the Turing principle into the virtual Turing principle: "It is possible to build a virtual-reality generator whose repertoire includes every physically possible environment."
This book is like a layout of one well-respected scientist and pioneer of quantum computation's self-consistent theory of the universe. Speculative and mindblowing and who knows how its correctness will play out
8 reviews
September 1, 2022
Deutsch propose que la réalité est composée de, ou plutôt, expliquée au meilleur de notre connaissance actuelle par, l'union des 4 théories suivantes: l'épistémologie poppérienne, la théorie quantique, la théorie de l'évolution et la théorie du calcul.
Points forts : Il aborde la théorie quantique comme explication du monde physique et non seulement comme un outil de prédiction. C'est de loin la meilleure présentation de cette théorie et de son interprétation multiverse pour le grand public. L'auteur explique aussi le principe de Turing dans toute sa splendeur, en décortiquant ce que veut vraiment dire «réalité virtuelle». Une élégante présentation des idées de la théorie de l'information et de l'importance des conséquences qui découlent du principe de Turing et de l'universalité, lorsque ces concepts sont pris au sérieux.
101 reviews1 follower
August 29, 2016
The level of semantic complexity is not uniform throughout the 14 chapters of the book, and neither is the balance between the proficiency in Quantum Physics and Computation Theory that is expected of the reader in order to internalize the contents.

Having read the book as a Computer Scientist with knowledge of Artificial Intelligence and Machine Learning, my understanding of Deutsch's work is that it is aimed at communicating a multiverse worldview (where "worldview" is understood here as a semantic and metaphorical framework for describing our experience of physical reality), in which questions regarding the infinite parallelism inherent in quantum computing can be explained and linguistically reasoned about more comfortably.

The first chapters on virtual reality and rendering processes can be thought of as laying an axiomatic foundation which is less semiotically constrained than the empiricist conception of science. Furthermore, an integral part of this foundation is formed by attaching a value system for the phenomenon of explanation which is compatible with evolutionary theory. I was in fact surprised that Deutsch's theory of explanation does not make more references to Kolmogorov complexity.

The middle chapters draw parallels between computation theory and the phenomenon of life. However, in contrast with the Darwinian single-[discrete]world interpretation of evolution, Deutsch describes life through the theory of replicators embedded in a (the?) multiverse. I thought that a particular innovation in thinking was his proposed thought-experiment criterion for differentiating between life and non-life.

The final chapters explain the [non]existence of time from a multiverse conception of reality, and posit the laws of physics as the source for the deterministic topology in which the snapshots of the universe simultaneously coexist (thus making possible the perception of time and causality).

In the end, Deutsch affirms his belief in the ultimate (but incremental) plausibility of unifying theories of reality (especially in the light of Physics as the unifying force), and the continual creation of knowledge as its main driving process - in simplistic and poetic terms, he believes that the universe is the computational effort of physics to understand itself, to build a fixed point of itself if you will.

This process is understood and speculated to continue asymptotically towards the end of the universe, though subjected to physical laws we have no mean of imagining.

I believe that no matter what your background is, this book will help scratch a few nihilistic (and perhaps spiritual) itches in your psyche. It most certainly reaffirmed some of my continuously-evolving beliefs regarding the nature of life and existence.
33 reviews
July 25, 2017
Оказывается существует бесконечно много вселенных. По английски одна вселенная называется universe. А все вселенные вместе называются multiverse. Вы можете спросить, а почему мы тогда не ощущаем этого расщепления себя на множество параллельных вселенных?! Ну то, что Земля вращается вы тоже не ощущаете, однако это так.

Наша Вселенная - это такой монолит из всевозможных комбинаций. Времени не существует. Есть только снимки состояний мира. А законы физики являются клеем склеивающим эти снимки. Время НЕ течет подобно головки граммофона по пластинке.

В книге затрагивается вопрос путешествия во времени и убедительно доказывается почему это невозможно. Если вы возвращаетесь на прошлый снимок, то вы возвращаетесь на другой снимок, который допускает ваше возвращение. Вы не можете вернуться на целевой снимок потому что это уже будет другой снимок. Есть определенная комбинация и вы не можете в неё вторгнуться не изменив её. А изменяя её она становится по определению другой комбинацией.

В книге делается попытка связать воедино квантовую физику, теорию вычислений, эволюцию и эпистемологию. Много рассказывается про виртуальную реальность, что сейчас актуально. Согласно принципу Тьюринга универсальный компьютер может воссоздать любую физически возможную среду, а т.к. человек это физический объект, то возможно создать виртуального человека, т.е. искусственный интеллект. А нас в университете преподаватель информатики убеждала, что создание ИИ невозможно в принципе.

В процессе чтения книги у меня появилась такая мысль, что между устройством нашего сознания и устройством Вселенной есть что-то общее, что позволяет нам познавать окружающий нас мир.

На вопрос куда всё движется, автор отвечает, что всё движется по пути знаний. Мне это напомнило кажется философию Кадербхая из романа Шантарам. Всё идёт по пути усложнения. И в конце этого пути стоит Бог. Возможно достигнув Бога он станет по-настоящему живым и воздаст всем за всё. Так что вполне возможно, что смерть это ещё не конец и однажды нас оживят.

С другой стороны так как существует бесконечно много вселенных, то не исключено, что в одной из них существует сила, которую можно назвать Богом.

В книге также затрагивается вопрос свободной воли. Нам только кажется, что мы самостоятельно принимаем решения. На самом деле всё предрешено.

Короче говоря, боюсь, что наш мир устроено куда более сложно, чем мы способны сейчас себе это представить.
Profile Image for Eugene.
17 reviews5 followers
September 6, 2011

Когда я был маленьким, я не хотел быть ковбоем или космонавтом. Из "приключенческих" профессий мне больше нравилась археология или геология, но больше всего мне хотелось стать ученым. Но без специализации, а вот просто Ученым - который занимается всем подряд, именно тем, что ему интересно в данный момент. Я вырос, мечта слегка увяла, особенно после того, как узнал, кого называют современными учеными и что есть современная наука. Но где-то там, глубоко внутри, детская мечта немного жива. И она приводит к таким книгам, как "Структура реальности" Дэвида Дойча.
У автора была похожая мечта в детстве, и судя по всему - у него она реализовалась более успешно. Или, по крайней мере - он на правильном пути. Дэвид Дойч - физик-теоретик в университете Оксфорда и яркий евангелист квантовых вычислений и теории мультиверса (множества параллельных вселенных).
Книга относится к жанру научно-популярных и написана "для широкого круга читателей". Хотел бы я познакомиться с этим "широким кругом"... Каких-то специфических деталей там нет, но мозгодробилка из нее все же вышла неплохая.
Наука "обо всем", с помощью которой можно будет объяснить все, происходящее вокруг, по мнению Дэвида, включает в себя четыре основных направления:
- квантовую механику (с использованием понятия мультиверса)
- эпистемологию (теорию знаний)
- теорию вычислений
- эволюционную теорию
Одна из важных особенностей "теории всего" - не пытаться объединить все в рамках одной науки (как пытаются сделать с физикой элементарных частиц), а сделать правильный симбиоз, когда одна теория красиво дополняет и помогает другим. Это и есть та Наука, которая грезилась мне маленькому.
Также имеет смысл почитать книгу, если интересно узнать о квантовых компьютерах, виртуальной реальности, машинах времени, конце света, бессмертии и многих других не менее загадочных вещах. И все это с точки зрения научных теорий и взглядов. Очень надеюсь, что заинтриговать получилось. :)

Оригинал рецензии: Структура реальности
Profile Image for Vheissu.
207 reviews57 followers
November 25, 2010
I must reluctantly conclude that this book simply is not worth the time and effort to read it.

I picked it up because of the high regard that Charles Yu afforded it in his wonderful novel, How to Live Safely in a Science Fictional Universe. I highly recommend Yu instead of Deutsch.

I admit up front to being a "positivist" in the Karl Popper sense, but not to the "straw man positivist" of whom Prof. Deutsch is clearly peeved. I'm sorry that mainstream theoretical physicists have not embraced his "explanation" for quantum strangeness (infinite parallel universes), but whining and name-calling and misrepresentation surely aren't persuasive tactics.

I'm sufficiently open minded to give his "explanation" a chance to prove itself, which can only be accomplished by empirical confirmation through reproducible experiments. Had Prof. Deutsch confined himself to such experiments, he might find many more besides myself who are willing to indulge his assertions.
Profile Image for Richard.
Author 6 books89 followers
April 28, 2012
Ambitious even by the standards of BIG picture pop sci (Hawking, Greene), Deutsch's "four strands" view of reality encompasses everything from how evolution might affect the universe as a whole to time travel, the very nature of a "theory," and quantum computing's effects on us. And you have to love a book that begins by describing an experiment that uses a flashlight and three pieces of cardboard to demonstrate that there must be far, far more universes than there are atoms in this one.

Lots (and LOTS) to ponder - but Deutsch has a poorer feel than, say, Brian Greene, for what needs explaining more and what needs explaining less. (Examples - The part on why time doesn't flow needed to be clearer and much longer. The part on why inductivism in science is rubbish needed to be clearer and much shorter. The crucial issue of why "space-time" physics is not what Deutsch advocated gets totally lost in the shuffle.) As a result some chapters feel like a harangue, and you end them unsure whether to feel either guilty for having not quite followed the thread or annoyed for having not been given quite enough thread to follow.
Profile Image for Anna Bahrii.
14 reviews1 follower
March 21, 2021
Прочитала эту книгу, найдя на неё отсылку в книге "Программируя Вселенную", вдохновившись идеей, что Вселенная - это квантовый компьютер. Было интересно почерпнуть для себя новые идеи строения Мультиверса, читать про логику и объективную правильность математики, ставя её под знак вопроса. Но автор, преподнося свои идеи, слишком фанатично говорит об их непоколебимой истинности, отрицая и принижая другие научные теории касательно Вселенной. Излишняя самоуверенность автора оттолкнула, но книга всё равно оказалась полезной и интересной.
Profile Image for Aleksei Uljassov.
149 reviews
June 29, 2020
Закончил читать посленднию книгу, из списка из 4 книг, по рекомендации Анатолия Вассермана. Книга крайне интересная и увликательная, автор хорошо объясняет различные темы, но под конец было тяжело читать. А так книга достойна внимания!
9 reviews
April 17, 2020
Отличный научпоп
Теория вычислений
Квантовая теория
Общая теория относительности
Теория эволюции
Profile Image for Andrei Khrapavitski.
93 reviews23 followers
November 18, 2017
Last year when I compiled my all-time favorite reading list, I included David Deutsch’s The Beginning of Infinity: Explanations that Transform the World. This is a really transformative text I wish more people would find time to read. Deutsch, best known for pioneering the field of quantum computation, is one of those scientists who go beyond the constraints of their own field and search for overarching explanations of foundational questions. For instance, Stephen Hawking was famously looking for a theory of everything. So it happens this is what David Deutsch was after, too, in his 1997 book, The Fabric of Reality. Next is a short review thereof.

Standing on the shoulders of giants, namely Karl Popper, Hugh Everett, Alan Turing and Richard Dawkins, Deutsch advocates a particular unified world-view, or a theory of everything, based on the four strands:

the quantum physics of the multiverse. Deutsch claims that Hugh Everett's many-worlds interpretation of quantum physics was the most plausible description of reality. This idea, once stigmatized by the physics establishment, has grown more and more weight and has become popular among prominent physicists (not only Sheldon Cooper). In short, this view implies that there are many, maybe infinitely many, universes “parallel” to the one we see around us. Everything that could possibly have happened in our past, but did not, has occurred in the past of some other universe or universes. Just as we see with particles in quantum physics, these universes can only weakly interact with one another. But who knows, if this view turns out to be true, it gives a whole new potential for things like time travel. In fact, Deutsch dedicated a whole chapter to the topic.

According to the author, future-directed time travel is by far the less problematic proposition. Even in everyday life, for example when we sleep and wake up, our subjectively experienced time can be shorter than the external elapsed time. People who recover from comas lasting several years could be said to have travelled that many years into the future, were it not for the fact that their bodies have aged according to external time rather than the time they experienced subjectively.

An astronaut who went on a round-trip involving acceleration to speeds close to that of light would experience much less time than an observer who remained on Earth. This effect is known as time dilation. By accelerating enough, one can make the duration of the flight from the astronaut’s point of view as short as one likes, and the duration as measured on Earth as long as one likes. Thus one could travel as far into the future as one likes in a given, subjectively short time. But such a trip to the future is irreversible.

Much more interesting is the topic of past-directed time travel. Most physicists believe that it is impossible. Not David Deutsch. He is kind of an agnostic, maybe more than that. He believes it might be possible to travel back in time but not prior to the time when a time machine was constructed.

Strand no 2 is Popperian epistemology. He develops this topic further in The Beginning of Infinity, but this is a truly interesting, IMHO, much less controversial proposition. Here he goes against inductivism and positivism. And for good reason.

Strand 3 is the Darwin’s theory of evolution. According to Deutsch, it was Dawkins who really put all the parts in place in his books The Selfish Gene and The Blind Watchmaker, in particular ideas of replicator and meme, which integrated nicely with Popperian problem-solving.

Finally, Deutsch offers his own contribution: a strengthened version of Turing’s theory of universal computation. You will read about virtual-reality generators and the limits of computation, quantum computers and the nature of mathematics.

As diverse as these propositions may seem, Deutsch is quite convincing that, if put together, they possess an awesome explanatory potential of the world. I wouldn’t go as far as Deutsch to claim that his unified view is conservative. Anyhow his theory of everything is quite plausible. The many-worlds interpretation is, frankly, the part I struggled the most. But at least we can test this idea on quantum level and maybe one day we will learn more about particle interactions on a grander scale. In fact, it is much harder to test some other hypotheses about cosmological multiverse, i.e. Level I and Level II multiverses (see Max Tegmark’s book Our Mathematical Universe for a detailed discussion of different multiverse ideas), even though they intuitively feel more believable than the strange quantum one.

The presumption that the universe will end with a Big Crunch, found in this book, used to be mainstream but now seems less credible. Still the discussion of the omega-point theory and life at the end of the universe was very compelling.

According to the author, for life to exist until the end of the universe, it would require the continual creation of new knowledge, which, Popperian epistemology tells us, requires the presence of rational criticism and thus of intelligent entities.

David Deutsch writes:

“The stabilization procedures, and the accompanying knowledge-creation processes, will all have to be increasingly rapid until, in the final frenzy, an infinite amount of both occur in a finite time. We know of no reason why the physical resources should not be available to do this, but one might wonder why the inhabitants should bother to go to so much trouble. Why should they continue so carefully to steer the gravitational oscillations during, say, the last second of the universe? If you have only one second left to live, why not just sit back and take it easy at last? But of course, that is a misrepresentation of the situation. It could hardly be a bigger misrepresentation. For these people’s minds will be running as computer programs in computers whose physical speed is increasing without limit. Their thoughts will, like ours, be virtual-reality renderings performed by these computers. It is true that at the end of that final second the whole sophisticated mechanism will be destroyed. But we know that the subjective duration of a virtual-reality experience is determined not by the elapsed time, but by the computations that are performed in that time. In an infinite number of computational steps there is time for an infinite number of thoughts — plenty of time for the thinkers to place themselves into any virtual-reality environment they like, and to experience it for however long they like. If they tire of it, they can switch to any other environment, or to any number of other environments they care to design. Subjectively, they will not be at the final stages of their lives but at the very beginning. They will be in no hurry, for subjectively they will live for ever. With one second, or one microsecond, to go, they will still have ‘all the time in the world’ to do more, experience more, create more — infinitely more — than anyone in the multiverse will ever have done before then.”

On this optimistic thought, let me end this review. Happy reading!
Profile Image for Erdem Yılmaz.
11 reviews4 followers
June 9, 2018
Kuşkusuz iyi bir fikirle ortaya çıkan fakat modern bilim felsefesi kavramlarını tali yollarda bırakarak zeminini kurguya evirmiş bir eser olarak görüyorum. Bilimsel/felsefi bir ambalajla sunulduğu ve asıl vaadi kurgusal olmadığından bu eleştiriyi ortaya atarken de cesur davranabileceğimi düşünüyorum. Haklı olmama hakkımın da olduğunu düşünüyorum ve bunda haklıyım.

Eser merkezinde paralel evren metaforuyla eş heyecan yaratacak solipsizm kavrayışı üzerinden bir anlatım oluşturması sıklıkla “ne diyorsun, ne dediğin anlaşılmıyor” sorusuyla insanın içini dolup taşırıyor. Genelinde tutarl bir çerçevesi olduğunu düşünmekle birlikte bu tip detaylarıyla ve ambalajında yarattığı beklentiyle serinlemek için uzanılan ama ağzımıza götürdüğümüzde uzun süre güneş altında beklediği anlaşılan bir şişe suyy içiyormuş hissi yaratıyor. Serinletiyor ama kekremsi tadını da hediye ediyor.
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