Multiple Universes

A couple of my co-bloggers here thought I should say something about John Horgan’s comments on Richard Dawkins vs. Francis Collins in Time, berating Dawkins on his endorsement of multiple universes as a solution to fine-tuning issues.

My first inclination was to say something snide. After all, here are Dawkins and Collins, two non-physicists, arguing cosmology, and Horgan, a science journalist, pontificating on who is right and wrong. A perfect occasion for misunderstandings all around. Since I don’t believe in staying confined to one discipline myself, I’m not going to take too many cheap shots, but there’s clearly a lot that needs setting straight here, particularly since few seem to understand the physical reasons many physicists these days feel compelled to talk about the possibility of a multiverse.

The greatest misunderstanding is the notion that physicists invoke multiple universes just in order to sweep fine-tuning under the carpet. I see a good number of theologians suggesting this, plus scientists like Collins who go digging around for signs of intelligent design in the universe. This is bloody nonsense. Physicists take multiple universes seriously, but not because we necessarily like the idea (I, for one, would be happier avoiding it) or because it would get the intelligent design people off our back. We take it seriously as a possibility, mainly because it’s damn difficult to avoid if you play around with any kind of quantum cosmology. Starting with inflationary cosmologies, we have been playing around with scenarios involving either a vast number of universe-bubbles or huge numbers of at least metastable vacua for some time now. As I said, they’re difficult to avoid—that is, without invoking arbitrary principles for the sole purpose of sweeping multiple universes under the carpet.

Now, if we already have to consider multiple universes as a genuine possibility, it makes good sense to ask what relevance this might have to fine-tuning questions. It is bound to be significant, particularly since our universe is then not necessarily a respresentative sample of the population of universes. Our very presence means our sample is biased (on top of the usual problems with a sample of one).

One reason to worry about multiple universes is the question of how we test such an idea. Theologically-minded people usually suggest that multiple universes are untestable, ad-hoc inventions in comparison which an unobservable God is a positively restrained idea. Not quite. First of all, if multiple universes appear in the context of an overall well-supported theory we can certainly speak of indirectly testing the idea. This is not at all odd in ordinary scientific practice. And even now, when we are far from having cosmological theories that physicists would bet their right arm on, physicists do talk about testing certain multiple-universe theories by observation. Note that I am not saying every multiple universe idea makes contact with experiment in this way. For example, Leonard Susskind defends the string-theoretical “landscape” notion in his The Cosmic Landscape: String Theory and the Illusion of Intelligent Design. It’s a fascinating book, well worth reading, but (as he partially acknowledges) his version of anthropic argument has trouble suggesting more than a tenuous connection with experimental tests. Moreover, if you’re like me, and you’re inclined toward a degree of skepticism concerning string theory, you’ll be extra cautious because the whole discussion takes place in the context of a theory that has not been able to make contact with too many reality tests. (Unlike, say, basic cosmic inflation.)

If you want to find out more, check out my chapters on physics and cosmology in The Ghost in the Universe and Science and Nonbelief. Vic Stenger’s Timeless Reality has a nice, accessible discussion as well.

Now, back to Collins and Dawkins. As I mentioned before, Collins is way out of his depth when talking physics and cosmology. He doesn’t understand what physical cosmologists are doing, and what he says rarely goes beyond philosophical posturing. Dawkins, on the other hand, can be criticized for taking Susskind’s version of anthropic reasoning on board somewhat over-enthusiastically. Still, in reading The God Delusion, my impression was that Dawkins was fully aware that this was outside his area of expertise, and that he wasn’t leaning too heavily on it.

About Taner Edis

Professor of physics at Truman State University

  • “Q” the Enchanter

    I know there are independent physical rationales for the multiverse idea, but I’m inclined to think that even without them the philosophical argument alone would be rationally compelling. I.e., we have a puzzle (how to explain fine tuning) and we can either appeal to the idea of an intelligent creator (for which we have absolutely no analogue in any domain of science) or we can appeal to the idea of a number of other universes (which at least can be cashed out in terms of simple physical models). Why shouldn’t the rational preference be for the latter sort of explanation, even if it were ad hoc?

  • Anonymous

    It is an unavoidable fact that the anthropic coincidences are observed to be uniquely related to the structure of the universe in a way that defies what our projected models expect. If you disallow unproven and speculative physics theory, then an evidentially supported implication does necessarily exist that carbon-based life is somehow relevant to the structure mechanism of the universe, and weak, multiverse interpretations do not supercede this fact, unless a multiverse is proven to be more than cutting-edge theoretical speculation.

    That’s the “undeniable fact” that makes Richard Dawkins and Leonard Susskind say that the universe “appears designed” for life, because what is unexpectedly observed without the admission of speculation is most-apparently geared toward the production of carbon-base life, and even intelligent life. Their confidence comes from the fact that they both “beleive-in” unproven multiverse theories, but their interpretation is only valid against equally non-evidenced “causes”, like supernatural forces and intelligent design.

    These arguments do not erase the fact that the prevailing evidence still most apparentely does indicate that we are somehow relevantly linked to the structure mechanism, until they prove it isn’t so, so we must remain open to evidence in support of this, or we are not honest scientists, and we are no better than those who would intentionally abuse the science. We certainly do not automatically dismiss the “appearance” by first looking for rationale around the most apparent implication of evidence.

    That’s like pretending that your number one suspect doesn’t even exist! There can be nothing other than self-dishonesty and pre-conceived prejudicial anticipation of the meaning that motivates this approach, and often *automatically* elicites false, ill-considered, and, therefore, necessarily flawed assumptions, that are most often accompanied by falsely conceived accusations about “geocentrism” and “creationism”.

    There can’t be any argument about the fact that the implication *most apparently* exists, unless you can prove that your multiverse exists, or if you can otherwise prove that the stability mechansim is not inherently geared toward the production of carbon based life for some very practical physical reason, over a “golden region” of the observed universe.

    That’s what makes Leonard Susskind say that “we will be hard-pressed to answer the IDists”… if the landscape fails, although Lenny doesn’t seem to be aware that *natural bias* is the default if we’re not here by accident, so ID doesn’t even enter the picture and can’t be inferred without direct proof.

    There is no valid basis for invoking multiverse interpretations to wipe-away the otherwise indicated significance, unless you’re just arguing with an extremist creationist. A scientist is obligated to accept the fact that she or he is being directed toward a bunch of balance points in nature that are intricately related to both the structure of the universe and the existence of carbon based life, and this is expected to somehow account for the otherwise completely unexpected structuring of the universe.

    You can know that you’re dealing with a self-dishonest scientist if they do not recognize that the above statements are factual and correct.

  • Joe Otten

    Am I missing something, but aren’t we talking about 2 different kinds of multiverse here?

    The multiple universes interpretation of Quantum Physics is about universes splitting off to solve the measurement problem, right? And these universes have the same dimensionless constants.

    And the multiple universes of fine tuning are different one from the next in their dimensionless constants.

    These multiplicities seem to be orthogonal to each other. Not that I like either much, FWIW.

  • Anonymous

    Nah, the “Landscape” of Lenny’s quantum gravity theory has at least 10^500 differing sets of constants.

    Quoting Lenny:
    The mathematics are rickety, but that’s what inflation implies.

    Out of the minimum number of possible universes is supposed to be a “patch” of habitable universes.

    I’m not even sure that’s possible, because I don’t I believe that Leonard Susskind has even begun to consider the effect on ALL of the relevant coincidences that are absolutely necessary to life, if you permanently alter any of them,

    This is a huge cop-out on the science.

    Our near-flat universe is the most natural configuration that a big bang will produce via the least action principle, because… [ uncertainty, multiverse, infinities... do not most-naturally go here! ].

    The lack of any plausible physics for a natural stability mechanism is the reason why string theorists are leaning more and more toward using anthropic selection to choose the correct vacuum from “the landscape” of possible solutions, because they have no more-viable mechanism, since they cannot explain why ours is the most natural configuration that the big bang should produce.

    But surely … the universe is configured to maximize the amount of time that energy can do work.

    The least action principle requires that the universe be most-economically restricted to the observed minimal-entropy configuration so that energy will be most-uniformly dissipated, because energy cannot be conserved if work is not efficeintly maximized.

    Without breaking this continuity a prediction falls that something other than heat-death must occur in order for energy to be “truly” conserved in an inherently imbalanced universe, otherwise “some” energy will be wasted.

    The above logically derived solution is an example of the kind of physics that one would normally expect for an answer to the riddle of the near-flat universe. This is the causality-accountable physics that is missing from science… and it represents one of the major-league cop-outs on first principles by a growing majority of scientists who have generally thrown up their hands at any hope of finding a realistically plausible stability mechanism.

  • Fletcher

    Scientism relies on the facts, the data, and the tests. Why, then, are “scientists” proposing multiple universes when multiverses, by their very nature, are epistimologically inapprehensible? If there were other universes, they would utterly unattainable and any attempt to grasp them is at best theoretical conjecture.

    Is that science?

    I agree that the multiverse theory is fancied by those who are willing to go anywhere BUT considering that there is a supernatural creator. It’s a convenient “out” for anthropic coincidences with no footing in reality.

  • Anonymous

    I agree that the multiverse theory is fancied by those who are willing to go anywhere BUT considering that there is a supernatural creator. It’s a convenient “out” for anthropic coincidences with no footing in reality.

    This unfounded leap of faith beyond nature is enabled by neodarwinians and physicists who deny interpretations for purpose in nature because they believe exactly what creationists want them to believe… that evidence that we’re not here by accident is evidence for god.

    Einstein, Dirac, Dicke, Carter, Wheeler and Davies would like to ask both sides just exactly where they get their clueless ideas from?… because there can be no inference of this sort without direct proof.

    This false assumption is killing science.

  • Zetetic

    I agree that the multiverse theory is fancied by those who are willing to go anywhere BUT considering that there is a supernatural creator. It’s a convenient “out” for anthropic coincidences with no footing in reality.

    It has a perfectly valid footing, it merely posits the existence of multiple iterations of that which has already been observed. God doesn’t share this distinction.

  • Fletcher

    What I mean is, the multiverse idea is not at all testable because we cannot apprehend it by its’ very nature. It is outside of our universe because it is unobservable.

    God, in my opinion, has revealed himself completely by the very fact that there is anything at all (generally), and through Christ in space and time (specifically).

    We all see the same evidence, it’s a matter of how we interpret it and through which lens we choose to look.

  • Sastra

    I’m curious. What happens to the Fine Tuning Argument if you begin with the premise “there is nothing objectively special or important about carbon-based life?”

  • Fletcher

    On what objective basis would a person start with such a presupposition?

  • Sastra

    Well, if we’re going to leave human opinions out of it (which we really should, seeing as we’re biased and the premises ought to be objective), then on what basis do we start with a premise that there IS something objectively special and important about carbon-based life?

    Surely we shouldn’t try to see if carbon-based life has been specially selected by starting from the premise that it’s objectively special, should we? That would almost seem to be a kind of cheating.

  • Fletcher

    I agree with you about not coming into any discussion with presuppositions, but I suppose we’re all guilty of that at one time or another – or even, oftentimes.

    Regarding the premise that there IS something special about organic life… the accumulation of anthropic coincidences themselves are the source of this premise – they are what show me that *inntelligent* organic life is in fact, special, unique, and amazing.. and vastly improbable as to have occured by accident.

    As I’ve said before, we all see the same signs, it just depends upon which lense we see these signs (or non-signs in the view of some) through. That lense tells the rest of the story. All of us, regardless of worldview, run into at least *some* significant problems at some point in supporting our view as a metanarrative.

    For myself, as a Christian, the problem of evil has always bothered me. If you ask me why God doesn’t stop the suffering of a 4 year old boy being tortured by leukemia, I can’t say that I have an answer any better than this: 1) God knows more than we do about the entirity of the universe and the spiritual dimensions of our existence, and 2) we live in a fallen world. Admittedly, these two attempts fall short, so I arrive at the point of humility where I say that there are some things that are simply inscrutable.

    I cannot, however, deny Christ Himself, and that is where I am “all in” at the end of the day (to steal a term from poker).