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Biran Greene @ The Edge: The Multiverse Hazard

  1. Jan 4, 2006 #1

    Brian Greene writes, "If true, the idea of a multiverse would be a Copernican revolution realized on a cosmic scale. It would be a rich and astounding upheaval, but one with potentially hazardous consequences. Beyond the inherent difficulty in assessing its validity, when should we allow the multiverse framework to be invoked in lieu of a more traditional scientific explanation? Had this idea surfaced a hundred years ago, might researchers have chalked up various mysteries to how things just happen to be in our corner of the multiverse, and not pressed on to discover all the wondrous science of the last century?"



    In the above quote, Brian Greene says that the Multiverse could have hazardous consequences.

    Is there a mathematical equation for the Multiverse?

    How is the Multiverse different from the Anthropic Principle, which is little more than an entertaining tautology?

    I know Briane Greene is a famous Mathematician, but I couldn't find the Greene equation. Is there one?

    What is his definitive contribution to mathematics taht makes him a great mathematicain? What are the conjectures, postulates, equations, or principles that he has left in his majestic mind's wake?


    And finally, what is the danger of the Multiverse?
  2. jcsd
  3. Jan 4, 2006 #2
    As I understand it. There are two ways at looking at the "Multiverse". One is that there is a quantum superposition of every possible out come. However, it takes a superposition of EVERY possible outcome to make just ONE reality. So each possibility cannot exist on its own. The second is that the universe is very much larger than just what we can observe within our Cosmological Event Horizon. And there may be corners of the universe far beyond our CEH that have different physical parameters. I think that this leads to an inconsistency. For then it would be possible for two overlapping regions to have two values for the physical constants.
  4. Jan 4, 2006 #3


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    No. Multiverse is an interpretation of either quantum measurement or the string landscape.

    I think Greene's multiverse is an interpretation of the landscape. Then the Anthropic principle would be a way of selecting our universe out of the huge number (possibly infinite) of vacua in the landscape.

    1. Greene is a physicist, not a mathematician.
    2. It's just ignorant to suppose a leading mathematician must have an equation named after him or her. It is slightly more accurate to suppose there would be a theorem named after a leading mathematician. But even that doesn't always happen. Sometimes greatness is expressed in other ways.

    As I said, not a mathematician. Were you thinking of someone else?

    I think Greene uses dangerous in the sense of David Dennet, who wrote a book calling evolution "Darwin's Dangerous Idea". Meaning that it undermined many common social notions, and the multiverse, says Greene, would do the same.
  5. Jan 4, 2006 #4
    Hi Mike2
    I think you may be right about the inconsistancy in the idea that there may be corners of the universe that have different physical parameters. Actually, I have never liked the idea of different physical parameters in the different parts of the multiverse. In my experience it seems to stem from a book by Martin Rees, which IIRC was called "Just Six Numbers".

    Rees picked out six cosmic parameters and played with the likely outcome of making small adjustments, and discovered that the existance of our universe is dependent on the parameters being nearly exactly as we find them. This delicate balance was then dubbed "fine tuning," which resulted in speculations about who or what is turning the knobs.

    The universe is not a radio and does not have knobs, but it was an interesting idea. It sparked a firestorm of controversy. But really, the controversy pursues the flaws in a metaphore and does not address the actual question. "Why are the parameters so finely balanced", not "Who tuned the radio"?
    It seems to me that the parameters are what they are probably because of geometric necessities. It is as senseless to ask who set the cosmic constant as it is to ask who set the value of Pi. Or, more simply, who decided that 2+1=3? Nobody decided that. It is a necessary outcome of the notion of numbers.
    So the real task before us is to discover the geometry of nature that results in the balance, just as ancient geometers worked on understanding the proper interpretation of known geometric ratios like Pi and Phi. It wasn't useful to them to invoke divine intervention, altho some of them did, and it isn't useful to us now to do so either.

    I agree with Greene that the multiverse idea is dangerous, but not because of the intelligent design - anthropic principle problem, which seems to me to be trivial, as I tried to show in the last paragraph.
    The danger of the multiverse idea seems to me to be that it threatens causality. Humans are often restrained from unfortunate behaviors by the idea of morality and divine justice, which are based on causality. The multiverse seems to remove this restraint. For example, if I rob a bank, there is a chance that I might get caught and go to jail. If I murder my brother for his riches, there is a chance I might go to hell. Where is the restraint if I now believe I will get caught in one multiverse version, but go free in another?
    Humans generally are not prepared to see the logic of sum over histories, and so cannot correctly evaluate the probabilites so as to act in a way that results in the most favorable outcome in the largest number of future universes. Many might sense the lifting of causal restraints on moral behavior and so take it in mind to commit dreadful acts. Well. That is not so different from what we see today anyway, but it is a caution. I would not like to see the multiverse invoked as a justification for unfortunate behavior on the basis that good and evil result equally from any action.

    In fact that would be a false conclusion, but many might make it anyway.

    I see that selfAdjoint has posted while I was museing. I agree with his short answer. I hope he agrees with my long explication.

    Richard Harbaugh
    Last edited: Jan 4, 2006
  6. Jan 4, 2006 #5
    There is still the interesting question about whether the multiverse idea implies that there are universes with other parameters. I am suggesting that this line of speculation, while it may serve a pedantic purpose in helping us understand the meaning of the parameters, is a dead end.

    Instead, I suggest that the parameters are necessary outcomes of the underlying geometry of nature. We are tasked with the work of discovering that geometric landscape. String theory and M theory have proposed several possible mathematical solutions which could generate some of the parameters. It remains to be seen if we can find a mathematical solution which generates all of them.

    The infinite vacuua criticism of string and M theory seems to me now to be based on the idea that other versions of the multiverse may contain other parameters, which I believe came from Martin Rees' pedantic playing with the knobs. Mike2 has pointed out, correctly in my estimation, that the idea that other versions of the multiverse contain other values for the parameters is self-contradictory. Overlapping regions would then have to have two or more values of parameters, which is clearly nonsensical.

    One conclusion would be that the idea of the multiverse is wrong. The other idea, which IMHO bears consideration, is that the values of the parameters are a necessary result of an underlying geometry, and that they do not and cannot vary in any rational version of the multiverse. Hence the infinite vacua criticism does not negate string and M, but merely shows that there is a correct geometry which is not merely universal, but must also be multiversal. String and M have made real progress in showing us what that geometry could be.

    String, M, and multiverse theories have the challenge of finding falsifiable predictions. Where might we look for such predictions?

    I have stated in another thread the assertion that


    There are many quantum effects which are accessible to current experimentation at low energies. Can they be explained using the classical 3-space 1-time model? Can we show that there is no way to explain them using the classical spacetime model?

    Example: electrons escape from quantum wells. Can this low energy behavior be explained using classical methods? By Occam, if it cannot be explained using classical methods, we must look for additional variables which are hidden from classical view.

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