Home > My Fiction, Science > Thinking about other universes (or, the trouble with infinities)

Thinking about other universes (or, the trouble with infinities)

I’ve been mulling over another subject that was suggested by the recent NOVA miniseries “The Fabric of the Cosmos,” hosted by physicist Brian Greene based on his book of the same name.  I felt some of the ideas it put across were too fanciful, putting sensationalism over plausibility or clarity, and one of them was the topic of its concluding episode, “Universe or Multiverse?”

The premise of that episode was that, if the Big Bang happened as the result of localized symmetry-breaking in an ever-inflating realm of spacetime, then our universe could be just one “bubble” in a perpetually expanding cosmic foam, with other universes being separate “bubbles” with their own distinct physics and conditions, forever out of reach because the space (how many dimensions?) between us and them is forever expanding.  Now, that’s okay as far as it goes.  It’s a somewhat plausible, if untestable, notion given what we currently know.  But what Greene chose to focus on was a rather outre ramification of this: the idea that if the multiverse is infinite, if there’s an infinite number of other universes alongside ours, then probability demands that some of them will be exact duplicates of our universe, just happening by random chance to have the exact same combination of particles and thus producing the same galaxies, stars, planets, species, inviduals, etc. — kinda like how the famous infinite number of monkeys banging on an infinite number of typewriters will inevitably produce all great literature by chance.  Thus, so the claim went, there could be other universes out there that are essentially parallels to our own with duplicates of ourselves, except maybe for some minor variations.  (Or maybe universes where duplicate Earths and humans exist in different galaxies, or where a duplicate Milky Way coexists with a different configuration of galaxies, or all of the above.)

Note that this is entirely different from the concept of parallel timelines, the usual way of generating alternate Earths in science fiction.  Parallel timelines aren’t separate universes, despite the erroneous tendency of SF to use the terms interchangeably.  They’re coexisting quantum states of our own universe.  The idea is that just as a single particle can exist in two or more quantum states at the same time, so can the entire universe.  These alternate histories would branch off from a common origin, and thus it’s perfectly reasonable that they’d have their own Earths and human beings and the same individuals, at least if they diverged after those individuals were born.  And there’s at least the remote possibility of communication or travel between them if nonlinear quantum mechanics could exist.  What we’re talking about here is something else altogether, literal other universes that just happen by random chance to duplicate ours because it’s inevitable if there’s an infinite number of universes.  While parallel timelines would be facets of the same physical universe we occupy, and would thus essentially be overlapping each other in the same place, these duplicate universes would be unreachably far away, except maybe by some kind of FTL or wormhole technology if such a thing could ever exist.  And they might predate or postdate our own universe by billions of years.

But I think it was a flawed conceit to dwell on that aspect of the multiverse idea, and I have my problems with the reasoning employed.  For one thing, it’s purely an ad hoc assumption that the multiverse is infinite rather than finite.  If it’s finite, then there’s no guarantee that there would be other universes that exactly duplicate ours.  Certainly there could be ones with compatible physical laws, with their own stars and galaxies and planets and life forms, but odds are they’d be different planets, different species, different individuals.  No duplicate Earth, no duplicate Lincoln or Kennedy or Jet Li.

And if the multiverse is infinite, then sure, you could argue that with an infinite number of tries, it’s inevitable that our universe would be exactly duplicated somewhere.  But the flip side to that argument is that if there’s an infinite number of universes, then the odds that any given universe would duplicate ours would be n divided by infinity, or effectively zero.  In practical terms, if we found a way to visit other universes via wormholes or something, then we could search for an infinite amount of time before finding one that had its own Earth and human race and history duplicating ours except for having more goatees or whatever.  Thus, by any realistic standard, such duplicates would be effectively nonexistent. (This is the problem with infinity as a concept in science — it tends to lead to absurdities and singularities.  Physicists generally try to avoid infinities.)  So while that result (the existence of duplicate universes) might be a logically sound consequence of the premise of an infinite multiverse, it’s also a trivial result, one that has no practical meaning and can’t be proven or falsified.  So it’s not science, just sophistry.  It’s angels dancing on the head of a pin.  And that makes it a waste of time to focus on in a program that’s supposed to be about science.

Besides, it’s boring.  The show presented us with the prospect that there could be an infinite number of possible forms for universes to take, whole other sets of physical laws, an unlimited range of possibilities… and all they wanted to talk about was duplicates of the world we already know?  What a staggering failure of imagination — or what a staggering triumph of self-absorption.  I would’ve been far more interested in hearing about the endless variety of universes that weren’t just like ours.  Why not dazzle the viewers with some discussion about what physics would be like in a universe with more than three spatial dimensions?  Or one with a higher or lower speed of light?  That would’ve been so much cooler and more enlightening than the silly, dumbed-down examples they gave, like Earth with a ring around it or Brian Greene with four arms.

I suppose the one appeal of the infinite-monkeys premise is metafictional: You can use it to argue that if every remotely possible combination or interaction of particles is inevitable, then every fictional universe really happens somewhere.  So, for instance, I could claim that my various fictional universes — my default/Only Superhuman universe, the Hub universe, the “No Dominion” universe, whatever else I might eventually get published — all coexist in the greater multiverse, and their different physical rules, different principles of FTL and whatever, could be explained by subtle variations in the laws of physics of their distinct universes (and yet somehow don’t prevent the fundamental interactions, dark energy, and so forth from having the exact same values so that stars and planets and life can form the same way).  And it’s handy for fans who want to believe that, say, a crossover between Star Trek and Transformers, or Star Wars and Firefly, or whatever might be possible despite the huge differences in those universes’ histories and physics.  But I’m not sure I find it desirable.  To me, if there’s some planet in some unreachably distant universe that exactly duplicates Earth’s evolution and history, and has a duplicate of myself who’s writing this post at this equivalent point in his Earth’s orbit (which might be billions of years in the past or future relative to my “now,” if such a thing could even be meaningfully measured), I wouldn’t really think of him as me, or his Earth as being my Earth.  So it wouldn’t really feel to me that those other fictional universes connected to my world’s history, and that would make them less meaningful.

Or would it?  I mean, just going in, I know these fictional universes don’t have the same physical laws as our universe, that the specific characters or alien races or whatever that exist in them don’t exist in our world.  So I know going in that they’re already separate realities from my own.  Their versions of Earth and its history may correspond almost exactly to ours, yet they’re still separate entities.  So maybe it’s no worse to think of my various written worlds (blog name drop!) as coexisting realms in an infinite multiverse than it is to think of them simply as independent fictional constructs.

And sure, sometimes I think it would be nice to have some sort of grand unified theory linking my universes together.  I already tend to think of “No Dominion” as being in a parallel quantum timeline of my Default universe, because it has no visible discrepancies in physics or cosmology and has a lot of similar technological and social developments; it’s just that some technologies develop decades too early to be compatible with my published or soon-to-be-published Default-universe fiction.  That won’t work for something like the Hub, though, since it has distinct differences in physical law.  And yeah, I admit I’ve tried to think of a way to fit my universes together into a unified multiverse, at least in passing.  I suppose the “infinite monkeys” idea could give me a means to do that.

But I don’t think I find it appealing, because it just multiplies the variables to such an insane degree.  If these universes are just infinitely separated samples of an infinitely expanding metacosmos, then that doesn’t really unify them in any way, does it?  They’re so far apart, so mutually unreachable, that the “connection” doesn’t really count as a connection at all.  (After all, given the underlying physical premise, there’s no realistic chance of any kind of wormhole link or inter-universe crossover anyway.)  It’s a trivial and useless result fictionally for the same reasons it is physically.  And if they’re specks in an infinite sea of universes, it makes them all feel kind of irrelevant anyway.  So why even bother?  It’s simpler just to treat them as distinct fictional constructs and not bother trying to unify them.  Besides, even if I know intellectually that the humanity and Earth and Milky Way of my fictional universes aren’t the same as my own, it’s more satisfying to pretend they are, to construct a satisfying illusion for the readers that they’re reading about an outgrowth of our own reality, than to pretend that they’re some totally separate duplicates in universes unreachably distant from ours.  No point going out of my way to create a premise that alienates me and my audience from the universes they’re reading about.  Granted, judging from some conversations I’ve had in the past, there are some people out there who wouldn’t have a problem with that.  But it doesn’t really work for me.

  1. WordRacket
    December 8, 2011 at 2:00 pm

    So was Sliders a series about parallel timelines or parallel universes in the multiverse? Granted I never watched the full run, but what I saw seemed to be (for the most part) parallel timelines.

    • December 8, 2011 at 2:13 pm

      Like most SF about “alternate universes,” Sliders was nominally about parallel quantum timelines. Although a lot of sci-fi gets the concepts somewhat confused, and there were some Sliders episodes that posited alternate physical laws on parallel Earths. The first season stuck exclusively to alternate histories, but in subsequent seasons there was a lot of conceptual drift and silliness.

  2. December 9, 2011 at 4:02 am

    Your reservations are well-founded, Christopher.

    Multiverse speculations, however philosophically seductive, have no place in the realm of science and it is sad to see the likes of Greene, Kaku and Davies promulgating these notions as such for public consumption.

    There is not a skerrick of evidence for more dimensions than the the three of space and one of time that we observe, nor for an infinity of universes each of which has different laws of physics.

    It is easy to be fooled by the indications of internal mathematical consistency of some of these models. We must aways bear in mind that fictions can be written in the language of mathematics, just as in the natural languages.

    Experimental verification is required for admission into scientific domain. So far there is none, and the reality is that the prospect for unambiguous testing or falsification of these speculations is very poor.

    The multiverse idea seems to stem from what is essentially knee-jerk reaction to the increasingly apparent “fine tuning” of our universe. An effect seen, not only in the physical constants, but, to an even greater extent, in fields such as geology, biology and chemistry.

    Persistent and pervasive patterns which give the overall life process its strong directionality.

    However, contrary to popular belief, this does NOT support the notion of “intelligent design” or of any kind of
    Nor does it require the extreme departure from the principle of parsimony in proposing an infinite number of universes with different physical parameters.

    It is accounted for in the much more down-to-earth evolutionary model presented (very informally) in “The Goldilocks Effect: What Has Serendipity Ever Done For Us?”, which you can download as an e-book from the “Unusual Perspectives” website.

    • December 9, 2011 at 9:45 am

      I should clarify, I’m not rejecting the concept of the multiverse itself. Naturally it should remain just a hypothesis until it can be experimentally or observationally tested, but it is an intriguing hypothesis and one that could potentially be testable in the future. Observations of the cosmic background radiation could reveal patterns suggesting the influence of external universes, and sufficiently high-energy collisions in the LHC might provide evidence of higher dimensions. At the very least, as an SF writer I recognize a lot of potential in the multiverse idea.

      What I have a problem with is the facet of that notion that Greene and his writers chose to focus on in episode 4 of the NOVA miniseries, the hypothetical that in an infinite multiverse, there would be exact copies of Earth and humanity and every one of us as individuals. While that might be a technically true consequence of the premise that the multiverse is infinite rather than finite (itself an ad hoc assumption), it’s a trivial and practically useless consequence, since the flipside is that the probability of any given universe duplicating ours would be infinitesimal, so even if we could observe or travel to other universes, we’d have essentially zero chance of finding such a duplicate. And they misrepresented the concept of the multiverse by dwelling on that extreme unlikelihood of exact duplication instead of on the wealth of universes that would be radically different from ours, which isn’t only misleading, it’s boring.

      In short, the multiverse is a hypothesis that’s definitely worth exploring and talking about (although of course it should be acknowledged that it’s not yet experimentally verifiable, and the episode did indeed acknowledge that), but my problem is with the way they chose to talk about it, their preoccupation on the silliest, most solipsistic, least intriguing possible consequence of the hypothesis.

  3. December 9, 2011 at 6:07 pm

    I have no problem with multiverse notions, per se, Christopher. But they should not be purveyed as part of science. which they are most certainly not. Like yourself, Greene et al. are science fiction writers. The only difference being that they use the simple language of mathematics rather than the great abstractions of the natural languages.

    There is nothing wrong with writing SF in either language and, on occasions, concepts and insights emerge which substantially help the advancement of science and technology.

    I happen to have a preferred multiverse speculation of my own, much more prosaic than that of the sting theorists inasmuch as the laws of physics are similar, at least in sibling entities. Like all the others it is pure speculation. No evidence! I happen to prefer it because it does tie in rather nicely with the far more factually based broad evolutionary model outlined in my writings.

    Here are some comments on string from real scientists which you might find worthy of consideration:

    Philip W. Anderson observes:

    “String theory is the first science in hundreds of years to be pursued in pre-Baconian fashion, without any adequate experimental guidance. It proposes that Nature is the way we would like it to be rather than the way we see it to be; and it is improbable that Nature thinks the same way we do.”

    Richard Feynman, for whose thinking I have enormous respect, put it this way:

    “I don’t like that they’re not calculating anything. I don’t like that they don’t check their ideas. I don’t like that for anything that disagrees with an experiment, they cook up an explanation-a fix-up to say, “Well, it might be true.” For example, the theory requires ten dimensions. Well, maybe there’s a way of wrapping up six of the dimensions. Yes, that’s all possible mathematically, but why not seven? . . . So the fact that it might disagree with experience is very tenuous, it doesn’t produce anything; it has to be excused most of the time. It doesn’t look right.”

    Here’s Sheldon Glashow:

    “Superstring physicists have not yet shown that theory really works. They cannot demonstrate that the standard theory is a logical outcome of string theory. They cannot even be sure that their formalism includes a description of such things as protons and electrons. And they have not yet made even one teeny-tiny experimental prediction. Worst of all, superstring theory does not follow as a logical consequence of some appealing set of hypotheses about nature.”

    Well, at last, by more mathematical smoke and mirrors, by further unwarranted assumptions, string theorists have come up with an experimental straw to clutch at.

    Kris Sigurdson, an assistant Professor at University of British Columbia, picked up the idea previously mooted several years previously by other researchers at UBC as a test for a multiverse and, it would seem, grafted this into the string framework. Which can, in keeping with tradition, and with no requirement to conform to physical reality, always be jiggled to fit. Sigurdson proposed that, providing the wake of any collision of multiverse components during inflation was sufficiently great, a characteristic double peak of single state photon polarization might be observable. A prediction which is, in principle, testable within the context of CMB missions to be carried out using the Plack observatory.

    That even this is, to use Glashow’s expression, “teeny-tiny” is underlined by Charles Bennett, who is the principal investigator on NASA’s Wilkinson Microwave Anisotropy Probe. He expresses the opinion that “the detection of a cosmic wake would nonetheless be “extremely unlikely”. The amplitude of a wake would have to be just right: too small and we wouldn’t see it; too big and it would probably have had severe consequences for our universe’s structure. The number of collisions would also have to be “fine-tuned”

    Incidentally, the notion of a multiverse did not spring from string theory, It has been around for a very long time in various forms before having been being taken aboard and tailored to fit within the string/brane scenario.

    Regarding the requirement for evidence as a prerequisite for admission to the domain of science:

    Dan Friedan has this to say:

    “The fact that certain beautiful mathematical forms were used in the period 1905-1974 to make the presently successful theory of physics does not imply that any particular standard of mathematical beauty is fundamental to nature. The evidence is for certain specific mathematical forms, of group theory, differential geometry and operator theory. The evidence comes from a limited range of spacetime distances. That range of distances grew so large by historical standards, and the successes of certain specific mathematical forms were so impressive, that there has been an understandable
    psychological impulse in physicists responsible for the triumph, and in their successors, to believe in a certain standard of mathematical
    beauty. But history suggests that it is unwise to extrapolate to fundamental principles of nature from the mathematical forms used by
    theoretical physics in any particular epoch of its history, no matter how impressive their success. Mathematical beauty in physics cannot be separated from usefulness in the real world. The historical exemplars of mathematical beauty in physics, the theory of general relativity and the Dirac equation, obtained their credibility first by explaining prior knowledge. . . General relativity explained Newtonian gravity and special relativity. The Dirac equation explained the non-relativistic, quantum mechanical spinning electron. Both theories then made definite predictions that could be checked. Mathematical beauty in physics cannot be appreciated until after it has proved useful.
    Past programs in theoretical physics that have attempted to follow a particular standard of mathematical beauty, detached from the requirement of correspondence with existing knowledge, have failed.The evidence for beautiful mathematical forms in nature requires only that a candidate theory of physics explain those specific mathematical forms that have actually been found, within the range of distances where they have been seen, to an approximation consistent with the accuracy of their observation.”

    Personally I will stick to the understanding that phenomena for which there is no evidence have no place withing the realm of science.

    I also subscribe to the principle (Carl Sagan, I believe) that “Extraordinary claims require extraordinary evidence.”

    And also that:

    “Physics starts from experience and ends in it.” Albert Einstein

    [Unusual Perspectives & The Goldilocks Effect: What has Serendipity Ever Done For Us are free downloads from the Unusual Perspectives website]

    • December 9, 2011 at 6:46 pm

      “Personally I will stick to the understanding that phenomena for which there is no evidence have no place withing the realm of science.”

      That doesn’t make much sense. The whole point of scientific theory is to make predictions beyond the existing evidence. Science is not about closing your mind to new possibilities, it’s about actively seeking out new truths beyond what we already know, and questioning our existing assumptions. Yes, predictions need to be testable and falsifiable, but science still does need to make predictions or it isn’t science at all, just another closed-minded dogma. Skepticism is healthy, but skepticism means remaining agnostic about predictions that haven’t been tested yet, not dismissing them out of hand.

      The multiverse model is not just something somebody made up. It’s a consequence of Guth’s inflationary model, a model which was formulated to explain the existing evidence and which has been supported by subsequent evidence. So no, it’s not science fiction. It’s merely an as-yet-untested ramification of a scientific model which on the whole has been supported by observational evidence. (And I don’t know why you’d feel the need to point out that it didn’t originate with string theory, because I never claimed that it did and neither did Brian Greene.)

  4. December 10, 2011 at 4:37 am

    I think you need to go back and read my previous post, and particularly the quotes therein, more carefully, Chris.

    Your remarks are all countered there. Particularly well so in the eloquent and very rational comment of Dan Friedan. If you can’t see the errors in your reasoning there, I doubt if you ever will.

    Good luck with it.


    • December 10, 2011 at 9:49 am

      There is nothing in Freidan’s comments that directly refutes anything I’ve said, since all I’ve said is that one should keep an open mind. I’m not assuming the multiverse is real, I’m just saying we don’t know yet and shouldn’t jump to any kneejerk conclusions just because of our personal biases. In science, the only real error is assuming you have all the answers.

      It sounds to me like you’ve been debating this with other people for a long time and have certain conditioned habits of debate. I think you’re mistaking my position here for the positions of certain others you’ve gotten into the habit of arguing with, people who are aggressively advocating the idea of the multiverse, and so aren’t really seeing what I’m actually talking about. My position is not about “taking sides,” because that’s a silly thing to do when talking about science. I’m just contemplating the possibilities. So I think we’re talking past each other here, and I don’t think it would be constructive to continue.

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