In Search of the Multiverse

The ongoing pseudo-scientific multiverse mania continues, with the recent publication in the UK of a new book by John Gribbin promoting this to the public: In Search of the Multiverse.

Gribbin expounds at length the usual string theory anthropic landscape/multiverse ideology, carefully avoiding introducing any mention of the fact that there might be quite a few scientists skeptical about it. On the crucial question of testability he invokes Raphael Bousso, who:

hopes, and expects, that there will be ways to extract such broad rules of the behaviour of matter at what are low energies compared to the Big Bang, but high by the standards of everyday life, from string theory.

There’s no indication given about what these broad rules implied by string theory might be, just a hint that whatever they are, we’re not going to be able to test them anytime soon:

even the the technology of the Large Hadron Collider may not be up to the task of testing such predictions.

Like many multiverse fans, Gribbin wants to mix together the many worlds interpretation of QM and the string theory anthropic multiverse in cosmology, attributing this insight to Susskind, and ending the next to last chapter of his book with:

This pulls together everything discussed in this book so far in such a pleasing way that it is tempting to end it here. The Cosmic Landscape of string theory is just the many worlds theory of David Deutsch writ large, and with inflation included within itself.

Unfortunately he doesn’t end the book there, but adds a final chapter promoting his own interpretation of the significance of the multiverse. His idea is that we are the product of a baby universe created by some race of superior beings:

The intelligence required to do the job may be superior to ours, but it is a finite intelligence reasonably similar to our own, not an infinite and incomprehensible God. The most likely reason for such an intelligence to make universes is the same as the reason why people do things like climbing mountains or studying the nature of subatomic particles using accelerators like the LHC – because they can. A civilization that has the technology to make baby universes might find the temptation irresistible, while at the higher levels of universe design, if the superior intelligences are anything at all like us there would be an overwhelming temptation to improve upon the design of their own universes.

This provides the best resolution yet to the puzzle Albert Einstein used to raise, that ‘the most incomprehensible thing about the Universe is that it is comprehensible.’ The Universe is comprehensible to the human mind because it was designed, at least to some extent, by intelligent beings with minds similar to our own. Fred Hoyle put it slightly differently. ‘The Universe,’ he used to say, ‘is a put-up job.’ I believe that he was right. But in order for that ‘put-up job’ to be understood, we need all the elements of this book.

Personally, I think there’s an air-tight argument against this: any race of superior beings that produced a universe in which science descended into this level of nonsense would immediately wipe out their creation and start over. Since we’re still here, there can’t be such a race operating out there.

Gribbin also has a Sci-Fi novel entitled Timeswitch coming out soon.

For two reviews of the book, see here and here.

In other multiverse news, FQXI has a story here promoting Andrei Linde, Renata Kallosh and their work on the string theory multiverse. Linde and a collaborator have a new paper How many universes are in the multiverse? on hep-th (by the way, why are these things not in qr-qc, since they’re “quantum cosmology” if anything is?). They come up with a number of 10 to the 10 to the 375 for the number of universes, and seem to argue that one needs to analyze all these to come up with predictions:

But when we study quantum cosmology, evaluate the total number of universes and eventually apply these results to anthropic considerations, one may need to take [the number of degrees of freedom of the observer] into account. Potentially, it may become very important that when we analyze the probability of existence of a universe of a given type, we should be talking about a consistent pair: the universe and an observer who makes the rest of the universe “alive” and the wave function of the rest of universe time-dependent.

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24 Responses to In Search of the Multiverse

  1. theoreticalminimum says:

    That’s rather sad. John Gribbin is an author whose many books I grew up reading. I don’t think I will grow up with this one.

  2. roland says:

    “The Universe is comprehensible to the human mind because it was designed, at least to some extent, by intelligent beings with minds similar to our own.”

    I guess following the line of universe builders leads to a final source(?). The highest beings there should live in a universe that is uncomprehensible to them. How did their human- like minds develop there? How can they have technology if they can’t comprehend their environment. That whole line of reasoning is just absurd.

  3. neo says:

    Absolutely right, Roland. Like every “intelligent design theory”, it seeks to explain by invoking the inexplicable.

  4. Tim vB says:

    You could of course have an infinite hierachy of creators, if each level acts twice as fast as the level below (the higher the more advanced), you could still have our baby universe at the bottom created in finite time, right? No need of some highest entity.
    In that case we should hasten to create our own baby universes, or else we would have to live with the fact that we are the most stupid human like creates of infinite universes.

  5. Chris Oakley says:

    … any race of superior beings that produced a universe in which science descended into this level of nonsense would immediately wipe out their creation and start over.

    This may be about to happen. Hopefully they will replace it with a universe with no Teletubbies.

  6. Stephen says:

    This argument:
    “‘the most incomprehensible thing about the Universe is that it is comprehensible.’ The Universe is comprehensible to the human mind because it was designed, at least to some extent, by intelligent beings with minds similar to our own.”

    is actually exactly the same argument invoked by theologians: The Universe is comprehensible to the human mind because it was designed, at least to some extent, by intelligent beings with minds similar to our own=God. The reason being that he is the creator and he has created us similar to himself, we are his image (or even more: he is our father, according to christian theology).

  7. Stephen says:

    and by the way:

    the reason why people do things like climbing mountains or studying the nature of subatomic particles using accelerators like the LHC – is not just because they can: but because it is beautiful (and, who knows, perhaps useful).

  8. Oxonian says:

    I am an atheist because I am unpersuaded by the arguments and evidence for theism, not because theism “sounds silly”. It is arguments and evidence that I would like to see offered against Gribbins’s hypotheses, however “silly” they may sound. Yet as far as I can see, all we are given in that respect is an invocation of falsifiability, which is besides the point since there are observations that could affect the probability that those hypotheses are true or false. So, Peter, could I kindly ask you to articulate, at least roughly, the reasons why you reject Gribbins’s ideas? This may actually persuade me and others that these ideas are indeed wrong, moving the discussion forward.

  9. Peter Woit says:

    Oxonian,

    The problem with Gribbin’s ideas is that they are pseudo-science, not science. They don’t actually have anything substantive to say about observations. Sure, it may be true that our universe may have been constructed by a higher intelligence, but this is an hypothesis that can be tested in any legitimate scientific way.

  10. Oxonian says:

    Peter,

    Thanks for the response. It is not clear to me why such a hypothesis could not, in principle, be tested in a legitimate scientific way. I agree with Richard Dawkins that the hypothesis that there is a god should be treated like a scientific hypothesis; and I agree with Victor Stenger that this hypothesis is disconfirmed by the available evidence. I don’t see why a hypothesis such as Gribbin’s (sorry for the misspelling above) should not be treated similarly.

    Just out of curiosity, do you think the many worlds interpretation of quantum mechanics is also pseudo-scientific? If so, what do you make of claims by Max Tegmark and others that this interpretation is actually scientifically testable? (If you have written about this in the past, feel free to direct me to the relevant writings.)

  11. Peter Woit says:

    Oxonian,

    There is no trivial reason why you can’t get predictions out of string theory multiverse models, you need to understand what they are and what their problems are. The bottom line though is that, despite a lot of work, proponents of this have come up with nothing. There is nothing in the Gribbin book in terms of predictions except the assurance from Bousso that he expects his work to be successful and to find something.

    I haven’t seen Tegmark’s claim that many-worlds is testable, so don’t know what that refers to. To the extent that many-worlds precisely agrees with other QM interpretations, not postulating completely different physics we mysteriously can’t quite test, I don’t think it’s pseudo-science. But if so, depending on one’s taste, one might not find it very interesting…

  12. Rakavolver says:

    “Personally, I think there’s an air-tight argument against this: any race of superior beings that produced a universe in which science descended into this level of nonsense would immediately wipe out their creation and start over. Since we’re still here, there can’t be such a race operating out there.”

    Superior doesn’t mean “good,” there is no correlation. They may be the types with horns, not halos, or supra-being equivalents of non-serious high school sophmores in Chemistry lab playing with bunsen burners.

  13. TomInCalif says:

    It’s “Turtles all the way down…”

  14. Arrow says:

    Oxonian: “I am an atheist because I am unpersuaded by the arguments and evidence for theism, not because theism “sounds silly”. It is arguments and evidence that I would like to see offered against Gribbins’s hypotheses, however “silly” they may sound.”

    Ockham’s razor.

  15. Aristarchus says:

    I always thought that God was a grad student from another universe who made ours for his thesis project. We’re now sitting on some immense beaker on some dusty shelf in another reality, as our Creator goes in search of a postdoc and a future wife.

    I have no proof of this, but these days who needs to?

  16. Charles Hardin says:

    I’m always amazed at the number of people willing to make sweeping statements about a book without actually reading it! I have read it, and it makes a lot of sense. Gribbin isn’t so stupid that he hasn’t thought of all these points, and discussed them! And as he says, if there is only one Universe, where do quantum computers do their calculations?

  17. Rakavolver says:

    Quantum computers, being quantum computers in our universe, make their computations in our Universe. Was that so hard?

    I believe you are referring to Shor’s Algorithm, which is rock-hard Mathematics, and Deutsch’s interpretation of same, which is speculation.

    Would you care to elaborate? Because all of this refers to possible FUTURE Quantum computers far more sophisticated than the ones we have now, and can theoretically can achieve, but have not. Hello, Quantum decoherence?

    Gribbin not stupid by any means, but he has the right and the privilege to be wrong, just like everyone else, including you and me.

  18. Rakavolver says:

    “The Cosmic Landscape of string theory is just the many worlds theory of David Deutsch writ large, and with inflation included within itself.”

    Oh, good Lord. In one sentence, three controversial subjects are combined (NOT “unified”, because to call them so would be a insult to TRUE UNIFIERS such as Dirac who unified (without quotes) Special Relativity and Quantum Mechanics), thanks but no thanks, via semantics. Let’s break them out. This is (sadly) fun:

    - The Anthropic Landscape Mis-Theory of California String Theory
    - The Many-Worlds Mis-Theory of Hugh Everett II
    - The Inflation Damn-Near-Theory but often Mis-Theory of Alan Guth

    Why am I NOT surprised, since this is written for the “middle-brow” “intelligent laymen” target audience that is the English, that this book will NOT sell? In England, anyway.

    So sad.

  19. neo says:

    I would describe Everett’s many worlds as an “interpretation”of a rock solid theory, QFT. I don’t quite know what the anthropic landscape should be called. An interpretation of a speculative theory?

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  21. Charles Hardin says:

    Peter Woit says, “many-worlds precisely agrees with other QM interpretations” in other words, other QM interpretations precisely agree with many-worlds. So it passes all the tests other interpretations pass. AND it solves the puzzle of what makes the wave function of the Universe collapse. You can’t just dismiss it because you don’t like it.

    Rakavolver describes inflation as a mis-theory — yet it has passed several experimental/observational tests.

    And the President of the Royal Society takes anthropic ideas seriously.

    Let’s use reason in this debate, not emotion.

  22. Tim vB says:

    @Charles Hardin
    Hope the following is not too controversial:
    QM is a mathematical model, if you describe your experiment, I can employ that model and calculate the possible outcomes. If there is an error on my or your part we will disagree, find the error, fix it and finally agree, within a relatively short timespan.
    An interpretation of QM is an explanation of why the model works. You and I can believe in different interpretations, that does not affect the your experiment or my calculations. I think this is meant by “many-worlds precisely agrees with other QM interpretations”.
    You cannot rule out an interpretation by experiment.
    While the many-world interpretation has many interesting aspects, I am puzzled why I have the impression to live in only one of the many-worlds. Any interesting comments on that? (I knwo some proponents of many-worlds, but they all dismiss this question as metaphysical).

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  24. Deutsch’s contention is that a quantum computer would literally be “larger” than any one classical universe:

    http://www.edge.org/documents/archive/edge78.html

    Interesting interview, regardless of whether you agree with him.

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