Friday, November 04, 2005

Anthropic Weinberg

Steven Weinberg is an exceptional physicist. He not only gave the name to the Standard Model, but he also discovered it - in the old era when it did not include QCD yet. He has made lots of other discoveries and he is still "in" and he even follows the very technical recent discoveries in string theory. Many of us have read his popular books such as The First Three Minutes and Dreams on a Final Theory and they influenced us tremendously.

One of his controversial but equally successful predictions was the prediction of the rough size of the cosmological constant assuming the galactic principle. If cosmology allows the galaxy formation, the cosmological constant can't be too large because the space would expand and dilute too quickly, before the clumps can be created by the gravitational pull. But it definitely can't be too negative either because the Universe would approach the Big Crunch too early.

There is an allowed window - the anthropic or galactic window - and the measurements in 1998 confirmed that our Universe seems to be somewhere in this window on its preferred, positive side. Although I am sure that Weinberg hates the idea of the anthropic principle deeply in his stomach and mind, he decided to accept it. And because his comment about the cosmological constant is the only at least partially and superficially successful prediction of the anthropic principle among those that can't be explained more accurately, he became a true prophet of the Anthropic Church. In his opening talk
Weinberg presents some novel ideology to support this principle. The biggest revolutions of physics not only answer questions in new ways, but they even change the classification which questions are important and well-defined. And the anthropic principle and the landscape seem to be doing something similar, he argues. Asking for an explanation of the values of the parameters of the Standard Model is equally meaningless as asking how to describe the interior of an electron or how to explain that aether causes no winds, Weinberg suggests.

Many people such as David Gross - or your humble correspondent - often tend to compare the anthropic principle to the religion because they share many important features. The main common feature is that the most important insight is determined a priori and it is a universal answer to many questions: there is either God or googols of Universes. Because this is a dogma, no insight can really falsify it. And this dogma justifies the viewpoint that we don't have to look for more detailed answers to the unanswered questions.

Not surprisingly, Steven Weinberg's opinion differs; the happy marriage between some recent anthropic trends in physics and religion, as supported by the Templeton Foundation and others, it not appreciated universally. Weinberg presents the anthropic principle and Christianity as big enemies. At the end of his talk, he quotes a powerful religious guy who is publicly afraid of Darwin's theory as well as the multiverse. And because Weinberg is probably the most well-known outspoken and radical atheist in the world, together with Richard Dawkins, he argues that the priest's emotions themselves are a good reason to look at the anthropic principle seriously. :-)

Well, I am also an atheist but frankly speaking, neither positive nor negative emotions of a priest seem to be enough to make an idea scientifically attractive for me. Weinberg's picture of the anthropic principle and the religion as two opposing theories seems to be much more superficial than Gross' comparison of the anthropic principle and the religion.

If someone says that there is no "microscopic", "deeper", or "quantitative" explanation for the properties of the species or the values of parameters in our effective field theories, I don't care much whether she explains that it's because these things are designed by an Intelligent God or she argues that the properties were chosen from a vast selection of Universes. The physical consequences are isomorphic: we can't predict and analyze the system at a deeper level. If I could choose among these two similar pictures, I would probably choose God because She at least cares about us, unlike the cold but otherwise equivalent multiverse. ;-)

Weinberg has made a very good guess about the cosmological constant - he has found an indirect argument that can impose both lower and upper bounds on the C.C. But it certainly does not mean that there can't exist a more accurate, quantitative calculation that determines its values - much like it exists in thousands of other contexts - and it certainly does not imply that Weinberg's semi-quantitative argument should become a template according to which new conjectures and insights about Nature should be created.


  1. Dear Lumos,

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    How can you allow this horse manure to be sold via your blog?

    Anyway on a different, subject, Weinberg is referred to on the special relativity subject by Wallace in "Farce of Physics" (

    Sidney Coleman, Shelly Glashow, Steven Weinberg, and other
    senior physicists at Harvard opposed my studies to such a
    point of preventing my drawing a salary from my own grant for
    almost one academic year.
    This prohibition to draw my salary from my grant was
    perpetrated with full awareness of the fact that it would
    have created hardship on my children and on my family. In
    fact, I had communicated to them (in writing) that I had no
    other income, and that I had two children in tender age and
    my wife (then a graduate student in social work) to feed and
    shelter. After almost one academic year of delaying my
    salary authorization, when the case was just about to explode
    in law suits, I finally received authorization to draw my
    salary from my own grant as a member of the Department of
    Mathematics of Harvard University.
    But, Sidney Coleman, Shelly Glashow and Steven Weinberg and
    possibly others had declared to the Department of Mathematics
    that my studies "had no physical value." This created
    predictable problems in the mathematics department which lead
    to the subsequent, apparently intended, impossibility of
    continuing my research at Harvard.
    Even after my leaving Harvard, their claim of "no physical
    value" of my studies persisted, affected a number of other
    scientists, and finally rendered unavoidable the writing of
    * S. Glashow and S. Weinberg obtained the Nobel Prize in
    physics in 1979 on theories, the so-called unified gauge
    theories, that are crucially dependent on Einstein's special
    relativity; subsequently, S. Weinberg left Harvard for The
    University of Texas at Austin, while S. Coleman and S.
    Glashow are still members of Harvard University to this
    writing.[23 p.29]

    Even Albert Einstein was not immune from pressure from the
    established politicians in the physics community with regard to
    the sacred nature of the original special relativity theory,
    especially with respect to the postulate of the constant speed of
    light. For example the following quote is from a letter by Dr.
    E. J. Post in a continuation of the relativity debate:

    At the end of section 2 of his article on the foundations
    of the general theory, Einstein writes: "The principle of
    the constancy of the vacuum speed of light requires a
    modification."[26] At the time, Max Abraham took Einstein to
    task (in a rather unfriendly manner) about this deviation
    from his earlier stance.[27]

    With regard to the scientist's image of himself, Dr. Spencer
    Weart writes:

    A number of young scientists and science journalists,
    mostly on the political left, declared that the proper way to
    reshape society was to give a greater role to scientifically
    trained peopleÄÄthat is, people like themselves.[17 p.31]

  2. Nigel:
    Lubos's blog here is owned and operated by Google. Google can put whatever ads they like here without Lubos's consent. So he is not responsible for that.
    I noticed a certain X must have been reading Peak Oil related web sites, which may have meantioned the Hydrino. My attitude is I will start to believe it when I can purchase a commercial product made of Hydrino.

    The UK government is now seriously studying the consequence of Peak Oil. And it's quickly becoming something the main stream media is talking about more and more frequently laterly.


  3. I don't understand the opposition against multiverse ideas on the grounds that it prevents you from gaining deeper insight in the universe.

    The opposite is true. If you have only a single universe described by some laws of physics, superstring theory or whatever, then that's the end. You can't ask why the universe doesn't operate according to other laws of physics. That question doesn't make sense in this setting. And anthropic arguments become tautological in this case.

    A reasonable assumption was formulated by Tegmark some time ago: All mathematical models define their own universes. Physical existence may be nothing more than mathematical existence. So, our universe exists because there is a mathematical model that describes it. Indeed, our universe IS this model.

    One problem with this idea is that there must exist a non trivial measure over the set of all possible universes that favors simpler universes (a uniform measure would predict that you should find yourself in an infinitely complex universe. This measure has to fall off faster than 2^(-n) where n is the number of bits needed to specify the model). But note that most physicists have an intuitive notion of such a measure when they appeal to Occam's Razor.

    Because here you don't postulate physical existence apart from mathematical existence, this is more conservative from postulating even a single physical universe, let alone some large number of physical universes.

  4. Dear Lubo Motle, This may be a hopeless comment, but as an educated atheist you might show at least some historical awareness that the word "God" with a capital G is a proper noun, not a generic stand-in for the idea of “intelligent” design, whatever that means. Granted, this Hebraic conception of a deity or god (in the generic sense) has no scientific content, which is hardly surprising given its antiquity. Yet from this conception was derived the notion of the unity of nature, which in turn (see Rodney Stark on this) led to the discovery of the existence of universal laws of nature. If the pioneers of science didn’t think they might find such laws they would never have looked for them in the first place. Polytheism does not tend in that direction.

    Another point: you may find it laughable and certainly unempirical to believe that the universe “cares” about human beings. Granted, it may be a fairy tale. But even so, from the Hebraic anthropomorphism of this idea – namely, that there is a God who is just and who impartially judges every human being according to a universal standard of justice -- we get our modern ideals of freedom, justice and human equality, which constitute the moral foundations of liberal democracy. The vast majority of our citizens have an evident need to believe in this Hebraic conception of God, not only because it comforts them emotionally, but because it under girds their sense of moral responsibility towards other people. And as Lincoln once observed, any universal feeling, however well- or ill-founded, cannot safely be disregarded.

    I guess what I’m trying to say is that you are not only a scientist but also a citizen. For this reason it probably behooves you, along with the rest of the scientific establishment to which you belong, to show a little more appreciation and respect for this proper noun, if only for the sake of the future funding of science.

    Luke Lea

  5. Sorry if I missed something, but I don't see any reference to Lee Smolin's notion of Comological Natural Selection as a nonteleological alternative to Intelligent Design when accounting for anthropic coincidences. Basically, he taps Darwinian logic to come up with a model of the evolution of universes in which physical constants that skew universes toward black hole production give those universes an adaptive advantage in the ensemble of universes. More at