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Jeffery thread-strings and branes

  1. Jun 28, 2003 #1


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    Jeffery thread--strings and branes

    Last night, in a (loop) quantum geometry thread which I started, Jeffery posted the following about strings, M-theory, and the "hottest topic in cosmology now" which he says is brane cosmology. I thought the posts should really be gathered into one place, in their own thread, as likely to stimulate discussion and requests for supporting links.

    In the LQG thread where originally posted they are not especially helpful or on topic. However as a separate thread his assertions (unfortunately lacking online references to back them up) could be quite interesting

    The following are quotes from Jeffery's posts of last night:

    Did you know that even when you start with minkowski space in string theory, string theory forces GR on you anyway? In this sense string theory predicts spacetime, something which LQG doesn't do. This remarkable fact is just one of many reasons why string theory is so compelling and why we feel like we're discovering physics.

    06-27-2003 01:40 PM

    Did you know that the different backgrounds in string theory - which necessarily include curved spacetime as mentioned above - simply parametrize the moduli space of a single unique theory, called M-theory?

    06-27-2003 01:48 PM

    Did you know that even when you begin with classical commuting spacetime coordinates, string theory forces noncommutative spacetime coordinates on you anyway?

    06-27-2003 01:49 PM

    Did you know that though string theory starts with the same uncertainty principles as any other quantum theory, it forces an even more fundamental uncertainty expressed purely in terms of spacetime intervals not involving any conjugate.

    This together with the above post indicate that whether we like it or not, strings require a direct quantization of spacetime, and the feeling is that it's just a matter of time before she is forced to give up the secret of how to do it.

    06-27-2003 01:53 PM

    What I find senseless is your uninformed and uncategorical rejection of a complicated and deep theory which the best minds in the world have commited themselves to.

    I think my positon is quite sensible in comparison.

    Last edited by jeff on 06-28-2003 at 04:10 AM

    06-27-2003 01:58 PM

    I've seen you mention LQG cosmology. Did you know that the hottest topic in cosmology now has nothing whatsoever to do with LQG. I'm talking about brane cosmology, which comes directly from string theory.

  2. jcsd
  3. Jun 28, 2003 #2


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    contrasting opinion

    For the sake of controversy here is an October 2002 post on Usenet sci.physics.research by Peter Woit a mathematician at Columbia, where string-savant Brian Greene is.
    I will try to learn more about Woit, but would judge him to be a neutral observer---at least, not being a physicist he could not be considered motivated by rivalry. Woit teaches Lie groups and representations (currently a graduate course in this) and may have the longterm good of physics at heart. He is commenting as an observer in an allied field, on changes in the String scene, or ex-scene:

    Here is a sample from Woit's post


    <<From the point of view of physics, my impression is that the only two string-theory related subjects that aren't completely dead in the water are AdS/CFT, which is getting a lot of attention because string theory seems to be finally saying something interesting about physics (not gravity or unification, but 4d strongly coupled gauge theory), and "brane-worlds".
    The second of these subjects isn't even really part of string theory (and ts appeal completely mystifies me). Neither of these subjects seems to have any particularly interesting mathematical component at all.
    Various M-theory related ideas that tried to invoke more sophisticated mathematics, like the K-theory classification of branes or uses of non-commutative geometry all appear to have foundered. They don't have any relation to real physics and they don't lead to really major fruitful new ideas about mathematics.

    Another major trend is that a lot of string theorists appear to have given up working on trying to solve the problems of string theory and are doing "string cosmology", hoping to find something physically observable caused by strings. Here at Columbia my colleague Brian Greene seems to be mostly
    devoting his time to a new "Institute for Strings, Cosmology and
    Astrophysics" rather than anything math-related.

    The bottom line about string theory as a way of going beyond the
    standard model is that it has failed completely. The fact that
    this project used a lot of sophisticated mathematics that
    many people didn't understand made a lot of the physics
    community resentful. The fact that it has failed has
    unfortunately put the whole use of mathematics in particle theory in a bad odor, This is going to continue for a while, a good start on dealing with this would be for the particle theory community to give the corpse a decent burial.>>
    Last edited: Jun 28, 2003
  4. Jun 28, 2003 #3


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    Woit's essay, "String Theory: An Evaluation"

    The most positive material about string theory and "brane cosmology" I could find through a google search was
    the accounts of them at the Jeffery Winkler website,

    this is a valuable online resource of science writings on a wide range of subjects----including M-theory and "brane cosmology"
    To find it, just put the author's name [Jeffery Winkler] into google.

    For a contrasting viewpoint, here is an essay by the mathematician/physicist Peter Woit----"String Theory: An Evaluation"

    I just learned that although Woit is in the Mathematics department at Columbia, his specialty is QFT! So he qualifies as either a mathematician or a mathematical physicist, I guess. Something like this by him was published in the American Scientist journal I believe----will try to get confirmation)

    Anyway here is a sample from Woit's "Evaluation" essay:


    --------start of Woit exerpt--------

    <<... The importance of the Dirac operator is well known to physicists, what is less well known is that it is of similar importance in mathematics where it plays the role of "fundamental class" in K-theory. This is reflected in the central role the Dirac operator plays in the Atiyah-Singer index theorem, one of the great achievements of twentieth century mathematics.

    To the extent that the conceptual structure of string theory is understood, the Dirac operator and gauge fields are not fundamental, but are artifacts of the low energy limit. The Standard Model is dramatically more "elegant" and "beautiful" than string theory in that its crucial concepts are among the deepest and most powerful in modern mathematics. String theorists are asking mathematicians to believe in the existence of some wonderful new mathematics completely unknown to them involving concepts deeper than that of a connection or a Dirac operator. This may be the case, and one must take this argument seriously when it is made by a Fields medalist, but without experimental evidence or a serious proposal for what M-theory is,
    the argument is unconvincing.

    Given the lack of experimental or aesthetic motivation, why do so many particle theorists work on string theory? Sheldon Glashow describes string theory as "the only game in town", but this begs the question. Why is it the only game in town?

    During much of the twentieth century there were times when theoretical particle physics was conducted quite successfully in a somewhat faddish manner; there was often only one game in town. Experimentalists regularly discovered new unexpected phenomena, each time leading to a flurry of theoretical activity and sometimes to Nobel prizes for those quickest to correctly understand the significance of the new data. Since the discovery of the J= in November 1974, there have been no solid experimental results that disagree with the Standard Model (except perhaps recent indications of neutrino masses). It is likely that this situation will continue at least until 2006 when experiments at the LHC at CERN are scheduled to begin. To a large extent particle theory research has continued to be conducted in a faddish manner for the past quarter century, but now with little success.

    Graduate students, post-docs and untenured junior faculty interested in physics beyond the Standard Model are under tremendous pressures in a brutal job market to work on the latest fad in string theory, especially if they are interested in speculative and mathematical research. For them, the idea of starting to work on an untested new idea that may very well fail looks a lot like a quick route to professional suicide.

    Many physics researchers do not believe in string theory but work on it anyway. They are often intimidated intellectually by the fact that some leading string theorists are undeniably geniuses, and professionally by the desire to have a job, get grants, go to conferences and generally have an intellectual community in which to participate.

    What can be done? Even granting that string theory is an idea that deserves to be pursued, how can theorists be encouraged to try and find more promising alternatives? Here are some modest proposals, aimed at encouraging researchers to strike out in new directions:

    1. Until such time as a testable prediction (or even a consistent compelling definition) emerges from string theory, theorists should publicly acknowledge the problems theoretical particle physics is facing, and should cease and desist from activities designed to sell string theory to impressionable youths, popular science reporters and funding agencies.

    2. Senior theorists doing string theory should seriously reevaluate their research programs, consider working on less popular ideas and encourage their graduate students and post-docs to do the same.

    3. Instead of trying to hire post-docs and junior faculty working on the latest string theory fad, theory groups should try and identify young researchers who are working on original ideas and hire them to long enough term positions that they have a chance of making some progress.

    4. Funding agencies should stop supporting theorists who propose to continue working on the same ideas as everyone. They should also question whether it is a good idea to fund a large number of conferences and work-shops on the latest string theory fad. Research funds should be targeted at providing incentives for people to try something new and ambitious, even if it may take many years of work with a sizable risk of ending up with nothing.

    Particle theorists should be exploring a wide range of alternatives to string theory, and looking for inspiration wherever it can potentially be found. The common centrality of gauge fields and the Dirac operator in the Standard Model and in mathematics is perhaps a clue that any fundamental physical model should directly incorporate them. Another powerful and unifying idea shared by physics and mathematics is that of a group representation. Some of the most beautiful mathematics to emerge from string theory involves the study of (projective) representations of the group of conformal transformations and of one-dimensional gauge groups ("loop groups"). This work is essentially identical with the study of two dimensional quantum field theory. The analogous questions in four dimensions are terra incognita, and one of many potentially promising areas particle theorists could look to for inspiration.

    During the 1960's and early 1970's, quantum field theory appeared to be doomed and string theory played a leading role as a theory of the strong interactions. Could it be that just as string theory was wrong then, it is wrong now, and in much the same way: perhaps the correct quantum theory of gravity is some form of asymptotically free gauge theory? As long as the
    best young minds of the field are encouraged to ignore quantum field theory and pursue the so far fruitless search for M-theory, we may never know.>>

    ------end of Woit exerpt------
    Last edited: Jun 29, 2003
  5. Jun 29, 2003 #4


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    Re: Re: Woit's essay, "String Theory: An Evaluation"

    You post, oh I would say roughly a couple of times a week, on Usenet sci.physics.research, as Jeffery. The similarity in manner and interests is hard to ignore and I would imagine several other people at PF who also visit "spr" have noticed your presence here.

    But on Usenet you are quite forthcoming and after signing Jeffery you give a link to your website, with its many articles on such things as String, Brane Cosmology, M-theory, literary compositions, curriculum vita, fantasy artwork and so on.

    It troubles me that you are not as forthcoming at this board.
    What is wrong with PF? Why can't you be equally frank here?
    Even at sciforum (that "other" board) you gave your website address.

    I told you, when you were using the alias "steinitz" that I much preferred the multifaceted and talented Jeffery Winkler to the guarded persona. Soon after that, you switched to "jeff", but so far you have not posted your website.

    Anyone who wants can just google with "Jeffery Winkler"

    or for that matter with "brane cosmology Jeffery" and your site comes up number one! Congratulations on a very interesting web entity BTW!

    As it stands, I find I cannot give credence to anything you might say about Peter Woit or the recent plight of String because of the fundamental dishonesty of your claim to be a "high energy theorist" in the professional reasearch community. Again, I like the real Jeffery, without the pretensions, much better.

    And am, I must say, much more inclined to trust the real Jeffery's statements.

    So for now at least the answer is no, there is nothing you could "explain" on your own pretended authority about Peter Woit's views. He is a mathematician at Columbia whose views on the Attiyah-Singer index theorem carry some weight with me. He is hardly making a case for LQG!!! He seems concerned with the overall good of theoretical physics. Much of what he says has the ring of truth, not to mention depth and historical perspective. I can respect where he is coming from in a way that I cannot respect a phony persona.
  6. Jun 29, 2003 #5


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    BTW Jeffery, anonymity is fine----keep on being plain "jeff" if you choose. I won't find your pretenses credible but no doubt some others will.

    Here's the first half of that Peter Woit essay. The "fiery polemic" of a mathematician angry at the waste of time and talent going on in theoretical physics. Glad someone had the gumption.

    -----exerpt starts here------

    String Theory: An Evaluation
    Peter Woit

    Department of Mathematics, Columbia University

    December 12, 2001

    For nearly seventeen years now most speculative and mathematical work in particle theory has centered around the idea of replacing quantum field theory with something that used to be known as "Superstring Theory", but now goes under the name "M-Theory". We've been told that "string theory is a part of twenty-first-century physics that fell by chance into the twentieth century", so this year the time has perhaps finally come to begin to evaluate the success or failure of this new way of thinking about particle physics. This article will attempt to do so from the perspective of a quantum field theorist now working in the mathematical community.

    The theory has been spectacularly successful on one front, that of public relations. Best-selling books and web sites are devoted to explaining the subject to the widest possible audience. The NSF is funding a series of NOVA programs on string theory, and the ITP at Santa Barbara is organizing a conference to train high school teachers in string theory so that they can teach it to their students. The newspaper of record informs us that "Physicists Finally Find a Way to Test Superstring Theory" (NYT 4/4/00).

    The strongest scientific argument in favor of string theory is that it appears to contain a theory of gravity embedded within it. It is not oftenmentioned that this is not yet a consistent quantum theory of gravity. All that exists at the moment is a divergent series that is conjectured to be an asymptotic perturbation series for some as yet undefined non-perturbative string theory (the terms in the series are conjectured to be finite, unlike the situation in the standard quantization of general relativity). String theorists actually consider the divergence of this series to be a virtue, since otherwise they would have an infinity (one for each compactification of six dimensions) of consistent theories of gravity on their hands, with no principle for choosing amongst them.

    String theory has lead to many striking new mathematical results. The concept of "mirror symmetry" has been very fruitful in algebraic geometry, and conformal field theory has opened up a new, fascinating and very deep area of mathematics. Unfortunately the mathematically interesting parts of string theory have been pretty much orthogonal to those parts that attempt to connect with the real world.

    The experimental situation is best described with Pauli's phrase "it's not even wrong". No one has managed to extract any sort of experimental prediction out of the theory other than that the cosmological constant should probably be at least 55 orders of magnitude larger than experimental bounds. String theory not only makes no predictions about physical phenomena at
    experimentally accessible energies, it makes no predictions whatsoever.

    Even if someone were to figure out tomorrow how to build an accelerator capable of reaching Planck-scale energies, string theorists would be able to do no better than give qualitative guesses about what such a machine might see. This situation leads one to question whether string theory really is a scientific
    theory at all. At the moment it's a theory that cannot be falsified by any conceivable experimental result. It's not even clear that there is any possible theoretical development that would falsify the theory.

    String theorists often attempt to make an aesthetic argument, a claim that the theory is strikingly "elegant" or "beautiful". Since there is no well-defined theory, it's hard to know what to make of these claims, and one is reminded of another quote from Pauli. Annoyed by Heisenberg's claims that modulo some details he had a wonderful unified theory (he didn't), Pauli sent his friends a postcard containing a blank rectangle and the text "This is to
    show the world I can paint like Titian. Only technical details are missing." Since no one knows what "M-theory" is, its beauty is that of Pauli's painting. Even if a consistent M-theory can be found, it may very well be a theory of great complexity and ugliness.

    From a mathematician's point of view, the idea that M-theory will replace the Standard Model with something aesthetically more impressive is rather suspicious. Two of the most important concepts of the Standard Model are that of a gauge field and that of the Dirac operator. Gauge fields are identical with connections, perhaps the most important objects in the modern formulation of geometry. Thinking seriously about the infinite dimensional space of all connections has been a very fruitful idea that mathematicians have picked up from physicists. The importance of the Dirac operator is well known to physicists, what is less well known is that it is of similar importance in mathematics where it plays the role of "fundamental class" in K-theory. This is reflected in the central role the Dirac operator plays in the Atiyah-Singer index theorem, one of the great achievements of twentieth century mathematics....

    --------end of quote-----

    [this is about where the other exerpt began---the one I posted earlier]
    Last edited: Jun 29, 2003
  7. Jun 30, 2003 #6


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    internal discontent in string-land

    You may have noticed that I am not quoting criticism of Stringery by LQG people. I have seen very little to quote, they are busy with other concerns I would imagine. Woit is a field theorist, with no obvious connection with LQG----a mathematician disgusted by string's hype. In any case, another interesting thing to listen to is criticism from within string-land itself, like Tom Banks'.

    Banks is a central string figure----a member of a group of theorizers at Rutgers, now on leave----a developer of "Matrix" theory----I can only repeat what I hear about him. In any case an important stringpersonage, who gave one of the talks at the bigtime 2002 Oxford String conference.

    Now it appears he is disillusioned. These thoughts of his were posted just this month. Peter Woit was arguing about it on Usenet with Jeff just the other day and Jeff was saying how he hoped the Enemy would not make use of Banks' words to harm String Theory.


    ----------exerpts from Tom Banks' paper--------
    June 9, 2003

    A Critique of Pure String Theory: Heterodox Opinions of Diverse Dimensions
    T. Banks
    Department of Physics and Institute for Particle Physics
    University of California, Santa Cruz, CA 95064
    Department of Physics and Astronomy, NHETC
    Rutgers University, Piscataway, NJ 08540
    E-mail: banks@scipp.ucsc.edu

    I present a point of view about what M Theory is and how it is related to the real world that departs in certain crucial respects from conventional wisdom. I argue against the possibility of a background independent formulation of the theory,....

    1. Introduction: The Conventional Wisdom

    String theory, although it is a theory of gravity, is a creation of particle physicists. Traditional string phenomenology shows its pedigree by asking for an exact solution of a purported theory of everything, which exhibits exact Poincare symmetry (a symmetry which is clearly only approximate in the real world). This theory is supposed to describe the scattering of particles in the real world, which is thus postulated to be insensitive to the cosmological nature of the universe.

    The basis for this assumption is locality, a property that is evidently only approximately true of string theory at low energy. Super Planckian scattering is dominated by black hole production, and the spectrum and properties of black holes of sufficiently high energy are definitely affected by the global structure of the universe. By continuity, there are effects on low energy physics as well. The only question is how large they are.

    At any rate, a principal defect of this approach is that it already postulates two mathematically consistent solutions of the theory of everything, namely the real, cosmological, world, and the exact Poincare invariant solution. In fact, as is well known, the situation is much worse than that. There are many disconnected continuous families of Poincare invariant solutions of string theory. They have various dimensions, low energy fields, and topologies, but they all share the property of exact SUSY. The program of string phenomenology is to find a SUSY violating, Poincare invariant solution of the theory, which describes low energy scattering in the real world. In [2] I expressed the opinion that no such solution exists.

    ...The theory of the real world has a finite number of states and can be neither Poincare invariant, nor supersymmetric. Since the number of states in the real world is exp(10120), it would not be surprising to find that some of the properties of the real world are well approximated...

    ....[later in the same section, on page 6]...
    The above discussion, and [12] make it clear (to me at least) that the old dream of background independence in string theory is a chimera....

    ----------end of quotes from Tom Banks------

    It sounds to me as if he would be attracted to the background independence of LQG, and also to its aspect of finiteness or discreteness. It also sounds as if he is tired of flat old Minkowski space---the Poincare group is just the group of special relativity that stringtheoretics is built on. He may feel the flat space of special relativity doesnt match the real world ("the cosmological nature of the universe") well enough to suit him.
    Last edited: Jun 30, 2003
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