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Joe Lykken's List of Stringy Goods and Bads

  1. Aug 6, 2005 #1


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    Every year Stanford SLAC has a summer institute. This summer Fermilab Joe Lykken is giving a series of talks called "String Theory for physicists". His first 7 slides summarize what he thinks are the stringy goods and bads.

    In case anyone might want to discuss, question them, clarify, I will transcribe the list. The slides are handwritten--so in case the list is interesting to anyone here at PF, it may be useful to have it copied out. The rest of this post is a transcription of Lykken's list: "good/bad news about string theory"


    Good: String theory is a consistent theory of quantum gravity.

    Bad: It's really a generator of an infinite number of mostly disconnected theories of quantum gravity, each around a different ground state. No background independent truely off-shell formulation of string theory is known (yet).


    Good: String theory is unique. i.e. there is only one distinct consistent theory of "fundamental" strings

    Bad: It has an infinite number of continuously connected ground states plus a google of discrete ones. There appears to be no vacuum selection principle, other than the stability of supersymmetric vacua, which gives the wrong answer.


    Good: String theory gives you chiral gauge theories, with big gauge groups, for free + complicated flavor structure at low energies is mapped into the geometry of extra dimensions

    Bad: Doesn't like to give the Standard Model as the low energy theory.
    A "typical" string compactification is either much simpler (with more SUSY and bigger gauge groups) or much more complicated (lots of extra exotic matter extra U(1) gauge groups etc)


    Good: String theory predicts supersymmetry and extra dimensions of space

    Bad: It's happy to hide them both up at the Planck scale


    Good: No length or energy scales are put in by hand; all scales should be determined dynamically

    Bad: Appears to be too many (hundreds!) scalar fields (moduli) with too much SUSY to get determined dynamically; may be forced to appeal to cosmic initial conditions (the Landscape)


    Good: String theory gives a microphysical description of (at least some) black holes, resolves their singularities

    Bad: Doesn't seem to resolve the singularity of the Big Bang
    (good for inflation, though)


    Good: Lots of powerful dualities
    including weak <--> strong coupling dualities
    and short <--> long distance dualities

    Bad: Can't tell what are the "fundamental" degrees of freedom.
    String theory not necessarily a theory of strings


    Good: Unification of all the forces is almost for free, may need
    an (interesting) extra dimensional assist

    Bad: In our most realistic string constructions so far, SU(3)C,
    SU(2)W, and U(1)Y have essentially nothing to do with each other: related to different features of complicated D-brane setups


    Good: AdS/CFT duality shows that 10 dim. String theory in a certain background is equivalent to a 4 dim. gauge theory!!
    Use this e.g. to show that RHIC QCD physics maps onto quantum gravity/black holes.

    Bad: Add more confusion: can't tell an extra dimension apart from technicolor


    Good: We are starting to use string theory to learn tricks for perturbative QCD, understanding the QCD strings, etc.

    Bad: The QCD community was already doing fine, thank you.
    Last edited: Aug 7, 2005
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  3. Aug 6, 2005 #2


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    RR "Railroad" Tucci has created a little song about the current status of String research. This curious message appeared four days ago at Woit's blog. It could be a good balancer for Lykken's list


    Well, ya got trouble, my friend.
    Right here, I say trouble right here in Jersey City
    Why, sure, I’m a stringy player
    Certainly mighty proud to say,
    I’m always mighty proud to say it
    I consider the hours I spend pulling out all my hair are golden
    Help you cultivate horse sense and a cool head and a keen eye

    Now, folks, let me show you what I mean
    You’ve got one, two, infinitely many stringy vaccua
    Vaccua that mark the difference between a gentleman and a bum
    With a capital ‘B’ and that rhymes with ‘Stree’ and that stands for ‘String’

    And all week long, your Jersey City youth’ll be fritterin’ away
    I say, your young men’ll be fritterin’
    Fritterin’ away their noontime, suppertime, choretime, too

    Ya got trouble, folks, right here in Jersey City
    with a capital ‘T’ and that rhymes with ‘Stree’
    and that stands for ‘String’

    May I have your attention, please? Attention, please
    I can deal with this trouble, friends,
    with the wave of my hand, this very hand
    Please observe me, if you will I’m Professor Harold Hill
    and I’m here to organize a quantum computer band

    Oh think, my friends, how can any stringy guess
    ever hope to compete with a gold Q comp
    Rah, rah, rah-da-da-da-da, rah-rah
    Remember, my friends, what a handful of Apple players
    did to the famous, fabled walls of I B M
    Oh, corporation walls come a-tumblin’ down

    Oh, a band’ll do it, my friends, oh yes
    I said a Q C band, do you hear me?
    I say Jersey City’s gotta have a Q C band
    and I mean she needs it today
    Well, Professor Harold Hill’s on hand
    and Jersey City’s gonna have her Q C band
    Just as sure as the Lord made little green apples
    and that band’s gonna be in uniform.

    posted by R.R. Tucci, August 2nd, 2005
    Last edited: Aug 6, 2005
  4. Aug 7, 2005 #3


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    IIRC the Music Man's band was less than met the eye, but perhaps that is the point.
  5. Aug 7, 2005 #4


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    ohwilleke, my problem here is total ignorance, which puts me at a considerable disadvantage. I tremble to confess that I have never heard of the Music Man's band. So are these lines of RR Tucci a parody of some wellknown pop lyrics?

    (that sounds like a naive question)


    [EDIT] So it was a Broadway show! and later a movie.
    I looked in google for "Music Man" and found this

    thanks for the lead.
    so that is who Professor Harold Hill is---the assumed name of a con-artist musical instrument salesman
    Last edited: Aug 7, 2005
  6. Aug 8, 2005 #5
    Hah, what a great list of Goods & Bads.
  7. Aug 9, 2005 #6


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    Always a pleasure to expand your cultural horizons (it is a fun show by the way, a favorite of college summer theater troupes).

    Just to flesh it out a little, the Music Man sold instruments and then told his students that they could learn music using "the Think Method", which involved imaging themselves playing the instruments rather than actually practicing. Thus, the reference is in part a dig at doing theory without having experiments to back them up.
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