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String crash lessons

  1. Jun 6, 2004 #1


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    There has been a decline in string research. What lessons can we learn from this?

    First of all just to establish the basic fact, look at the numbers of papers posted on arXiv per 12-month period, there has been a substantial decline over the period 2000 to June 2004.

    I'll supply links to the arXiv search engine for anyone who hasnt already seen the stringy research paper counts.

    However there has been an if anything sharper decline in the research quality (as gauged by citations). There were less than half as many recent highly-cited stringy papers in 2003 as there were in 2002.

    I'll supply links to the Stanford/SLAC HEP database that just issued its citations report for 2003, for anyone who hasnt checked it out already.

    The decline in string research has affected both the raw number of papers and the number of highly-cited papers

    What is happening in stringy research that correlates with this sudden falling off? What basic physics issues have emerged in this connection?

    How do statements by string leaders----Leonard Susskind, Tom Banks, David Gross, Mike Douglas, Edward Witten---correlate with the drop off? Are any of their recent remarks relevant: do they explain (to some extent at least) what is going on?

    Fortunately the answer is a partial yes: there are recent comments by Susskind and others that shed a little light on this. Hopefully we can gather some of these words-from-the-wise and post them, or links to them, on this thread.

    What, if anything, can we infer? It may be that stringy research has encountered interesting physical-theoretical obstacles which would be informative to sketch out.
    Last edited: Jun 15, 2004
  2. jcsd
  3. Jun 6, 2004 #2


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  4. Jun 6, 2004 #3


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    This is from the Spires ranking of hep-th papers.

    For definiteness 'recent' means the preprint appeared in the past 4 years so at end 2000 recent papers are those which appeared in years 1997-2000.

    According to Spires, in year 2000 there were 9 recent stringy research papers that garnered 125+ citations, and look at the numbers of citations each received:

    In 2000 the 9 recent highly cited sringy papers got: 498, 446, 397, 347, 316, 268, 191, 164, 131 citations.

    By contrast, in 2003 there were only 4 recent highly cited (125+) stringy papers and they got: 197, 135, 134, 125 citations.

    the above was from Spires list for the single category hep-th.

    Here are some similar results from the combined Spires HEP list,
    the combined list is broader and includes papers in all categories which
    Spires considers part of the HEP database----in line with what is meant by High Energy Physics research at least at the Stanford SLAC, DESY(Germany) and the other institutions participating in Spires.
    The Spires HEP database is broader than the single ArXiv category hep-th.

    The 1999 Spires HEP topcite list had, with only recent papers counted, 24 papers which received 125+ citations.
    Of these, 15 were recent string papers. (over 60 percent, a substantial percentage)

    The number of citations these 15 recent string papers received that year were:
    625, 464, 425, 285, 215, 202, 170 170, 167, 148, 146, 139, 137, 130, 126

    By contrast the Spires HEP 2003 topcites list had, when only recent articles were included, 20 papers which garnered 125+ citations.
    Of these, 4 were stringy type research (a smaller percentage than in 1999, 25 percent instead of 60 percent)

    the numbers of citations for these 4 string papers were:
    197, 135, 134, 125



    Last edited: Jun 9, 2004
  5. Jun 9, 2004 #4


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    There's been a sharp decline in string research and I am still hoping to hear some cogent explanations.
    the decline is an objective thing you can see in the ArXiv and Spires numbers---the data is online and I've provided links.
    What might be interesting is how you interpret it----there can be questions about interpretation.

    Lubos Motl talked about the decline in stringy research last year on SPR and said he hoped it was "sinusoidal", but IIRC no cogent explanation.

    Anyway the annual Spires report just came out and one can use it to quantify the sharp downturn in string research. it has four aspects

    1. decline in raw output of papers
    (according to ArXiv, a steady rise 1991 to about 2001-2002 and a decline since 2002 to present, no sinusoidal or uppy-downy behavior, just one long up and then down). Links will be provided so you can see for yourself.

    2. loss of standing in the annual "Papers that shaped modern high energy physics" review. This is an annual "what's hot in HEP" essay. Since 1997 or so it has been written by Michael Peskin at SLAC. Up thru 2001 it has been dominated by string news. After 2001 string is more of an afterthought at the end. Other HEP areas of research take the limelight and are seen as hot. Links will be provided.

    3. there are fewer recent highly cited stringy papers than there were before 2001 and these represent a declining percentage of recent highly cited HEP papers. Taking 'recent' to mean 'last four years' and highly cited to mean 125+ citations, one sees a decline from 60 percent in 1999 down to 25 percent in 2003. Percentagewise string has become a less important, or dominant, part of HEP research, as shown by the Spires HEP database.

    4. the citation quality of recent stringy papers has declined.
    Taking 'recent' to mean last four years here are the numbers for 1999 and for 2003:
    625, 464, 425, 285, 215, 202, 170 170, 167, 148, 146, 139, 137, 130, 126,...

    197, 135, 134, 125,...

    In 2003 there were fewer recent stringy papers which got 125+ citations.
    And their citability quality was inferior compared with their counterparts in 1999. It is not clear what citations measure, but they are an object measure of research quality of some sort as seen by other researchers in the field: influence, importance, valuable new ideas, advances, usefulness to later researchers, starting new lines of investigation, whatever gets your paper cited by those that come after. This quality has declined sharply in the string field, as the above comparison illustrates.

    My feeling is that this sharp downturn should be explainable and that one ought to be able to learn something from it.

    It certainly does not appear to be random fluctuation.
    I just looked at the raw output figures for 1991 to present and could see no 'business cycle' or 'sinewave' (sinusoidal) component. The arxiv count went like this:
    Code (Text):

    1991    102
    1992    461
    1993    544
    1994    610
    1995    810
    1996   1002
    1997   1248
    1998   1299
    1999   1403
    2000   1491
    2001   1546
    2002   1518
    2003   1258
    LTM     970
    By LTM I mean the last twelve months, 9 June 2003 to 9 June 2004.
    counts produced by the arxiv search engine vary some, but the
    general picture of a peak around 2001-2002 shows up consistently.
    I dont believe in taking other people's word on things like this so I will
    provide links to arxiv search so you can check for yourself.
    Last edited: Jun 9, 2004
  6. Jun 9, 2004 #5
    Experimental observation lacking, can be a direct challenge to the conceptual basis of anything, and Peter Woit is challenging that conceptual basis? This is always a safe assumption:)

    These statistics are very interesting from a overall perspective :smile:

    Maybe we should compare it the the mathematical challenges of the poincare conjecture or the issues of Fermat ( a million dollar reward in the offering of the toe?).

    The challenge is very difficult, and requires mnds that will incubate for a long time. These are the careful thinkers in this case that you have sited. Some who might not even care about the money:)

    Does not mean the challenge is going unabated? :smile:
    Last edited: Jun 9, 2004
  7. Jun 9, 2004 #6


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    there is a real grain of wisdom in what you say, Sol2, as there often is.

    It would be good to make some historical comparisons.

    with other intellectual fashions, in the past,

    and also with great outstanding problems.

    It has happened that with great outstanding problems several
    different approaches get tried, and many variations on them get tried,

    and then those approaches get abandoned and some other approach
    comes in (maybe from an unexpected direction) and works.

    as a watcher or onlooker I try not to get locked into one particular set
    of expectations

    or even one view of the problem

    You know I think that the problem been confronted now is not actually the TOE!!!

    Whatever people think they are doing, i think what they are really trying to do is arrive at a background independent version of quantum theory

    Yesterday selfAdjoint was speculating about "spaceons" of quantized space exchanging "gravitons" among themselves
    (as the geometry of space changed dynamically, I guess)
    it was a light-hearted, not a solemn, post, but it started me trying some unfamiliar lines of thought

    anyway this stringy approach may be getting run into the ground
    it is not just the decline in raw numbers of papers
    it is the decline in citability---the papers have less and less significance.

    whatever happens it's bound to be interesting
  8. Jun 9, 2004 #7

    The question JB highlighted in terms of the background issue, are very important, and the thoughts here are really quite fleeting. So to bring one back down to earth and I have to continually refresh my mind on that particular issue.

    You are right, in terms of what must be geometrical expressed. How does this relationship transpired in the subject of background versus non background?

    JB referred back to Smolin for comparsion of the true attempts at this question. Three Roads was a synopsis of the differents methods and approach and raised the question of how we might tackle this problem.

    This is how I saw it. It lead us to the understanding of what mathematics we might use? This then raises intertesting speculations on my part about the philosphical discussion on the issues of math and its origination.


    Also, you pointed out the historical discussion, and for me seeing how dirac and then Feynmen leads from him, in the toy model considerations, he consistently impoved this model for consideration?

    The solvay meetings were to me to incubate the ideas generated from different perspectives and this issue is on going in the dialogue between these two camps of LGQ and Stringtheory.

    But there is a basic question here about the background verus the nonbackground that must be answered?

    Yesterday selfAdjoint was speculating about "spaceons" of quantized space exchanging "gravitons" among themselves
    (as the geometry of space changed dynamically, I guess)
    it was a light-hearted, not a solemn, post, but it started me trying some unfamiliar lines of thought

    The only one missing, was wheeler's geon:) It has not passed others attention how we might describe the fundamental reality of dynamical resolution. Looking backwords, some of this historical insight can be quit revealing as you have stated
    Last edited: Jun 9, 2004
  9. Jun 9, 2004 #8


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    that's a good point. what you capitalized deserves to be
    and bold-faced as well!

    About "two camps" I dont know. People who think "camps"
    could be more interested in convincing other people that
    they are right, rather than finding out about nature.
    There may be Stringtheory propagandists who will yell at you if
    you dont genuflect to their Big Would-be TOE.
    But the people working on quantizing gravity seem a fluid bunch not locked into one particular doctrine.

    About the only thing non-String Quantum Gravity people seem to agree on is what you suggest here----the urgency of a (background independent)
    description of geometry.
    you have to be able to describe it in a convenient way so you can
    say how it changes, as matter moves around.

    geometry = gravitational field

    it isnt satisfactory to base things on a fixed pre-conceived geometry because the world just isnt like that.

    I would like to know other people's thoughts as to why String/Brane research has declined----some people say "flat-lined"----anyway seems at least temporarily stalled. But if I had to guess, I'd imagine it is just this very thing---this dynamic geometry thing.

    Witten called for a background independent version in 1992 (said how important it isl) and people have made great efforts---including recently Vafa----but it seems very hard and complicated to achieve B.I. in context of strings.
    Tom Banks referred to it as a "chimera".
    Motl recently talked about this as a central goal----he called it finding a
    "backround-universal" version---in a soul-searching SPS post.
    I should get some links to these quotes, they are interesting and revealing I think.
  10. Jun 9, 2004 #9


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    Here are links to the ArXiv search engine showing numbers of stringy research papers by year since 1991.

    (Counts papers whose abstract summary has the keywords
    string OR brane OR braneworld OR D-brane OR M-theory OR p-brane.)

    Year 1991:

    Year 1992:

    Year 1993:

    Year 1994:

    Year 1995:

    Year 1996:

    Year 1997:

    Year 1998:

    Year 1999:

    Year 2000:

    Year 2001:

    Year 2002:

    Year 2003:

    Last twelve months (e.g. 9 June 2003 to 9 June 2004):
    Last edited: Aug 5, 2004
  11. Jun 9, 2004 #10


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    we should backup key quotes with links---you may know this Witten quote
    about background independence already but I'll put the references:

    “Finding the right framework for an intrinsic, background independent formulation of string theory is one of the main problems in string theory, and so far has remained out of reach.” ... “This problem is fundamental because it is here that one really has to address the question of what kind of geometrical object the string represents.”

    E Witten: “Quantum background independence in string theory” http://arxiv.org/hep-th/9306122. “On Background independent open-string field theory” http://arxiv.org/hep-th/9208027.
  12. Jun 9, 2004 #11

    What is the move to the graviton, from gravitational wave understanding. If Gr was to remain consistent with QM how would this calculation serve to illustrate it as a smooth transformation?

    The very significance of the graviton must have dimensional significance based on the value of those gravitational waves?

    I hope I did not steer you off course here.
  13. Jun 9, 2004 #12


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    Sol2, indeed you dont steer me off course at all! I am unsteerable in
    a graviton direction. Your ideas and questions I'm glad to see (as usual)
    but I do not know from gravitons!

    Maybe someone else can respond to your question. I do not think a graviton has ever been observed yet and the various
    would-be theories that try to quantize Gen Rel seem to differ as to
    whether and what they are. So for the time being I remain happily ignorant about gravitons---really no opinion!

    Time will tell.

    Do you know how photons were first detected?
    (expect you do :smile:) they were detected before
    their existence was theorized
    Last edited: Jun 10, 2004
  14. Jun 10, 2004 #13
    To get numbers of string-theory related papers as a function of time it would probably be better to use the SPIRES database. The increase in numbers during the 90s is mostly due to the spreading use of the arXiv system, whereas SPIRES has been cataloging pretty much everything in particle physics for a very long time.
  15. Jun 10, 2004 #14


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    Good suggestion! I imagine the effect would be especially important in the
    early 90s when people were just getting started using arXiv.

    Here goes:






    Code (Text):

    1992   734
    1993   656
    1994   771
    1995   869
    1996   857
    this is by putting
    fin k string model and date 1992
    into spires
    Last edited: Jun 10, 2004
  16. Jun 10, 2004 #15


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    Code (Text):

    String, brane, M-theory papers by year of publication
    1986    89
    1987   136
    1988   324
    1989   725
    1990  1092
    1991   936
    1992   853
    1993   761
    1994   864
    1995   976
    1996  1069
    1997  1427
    1998  1383
    1999  1498
    2000  1642
    2001  1559
    2002  1677
    2003   xxx

    I struck the Spires 2003 count from the list because jgraber's
    post later in this thread puts it in doubt----they may still be
    cataloging papers from last year. follow the link given for 2003
    below if you want to get the current Spires count.

    The search used terms of the form
    fin k string model or matrix model or membrane model and date 1992
    in the Spires HEP database



















    my first pass was with just the one spires keyword "string model"
    to refine this I included other keywords
    and went all the way to 2003

    in any case at least we have something objective to check ideas against
    Looking at the spires (key=string, membrane, matrix) numbers i see a swoop between 1990 and 1996.
    Maybe someone who watches string research more attentively would like to explain this: what happened between 1990 and 1996?
    or was it just unexplained random fluctuation?
    Last edited: Jun 16, 2004
  17. Jun 10, 2004 #16


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    I would suggest you add brane (rather than membrane) and adS/CFT (in just that format).
  18. Jun 10, 2004 #17


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    Have you looked at the list of permissible Spires keywords?

    I tried brane but got no results (zilch!)
    then I looked at the list and found that what they wanted was
    "membrane model".

    With a new search engine it's not always easy to figure out how to
    use it. I would be glad if you or some of the others would try.
    Maybe you can get it to accept "brane" as a key word.
  19. Jun 10, 2004 #18


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    These are just a few terms under which you'll find stringy papers. I really do think you need to be expert on string theory to properly collect this sort of data and analyze what it actually means.

    del guidice-di vecchia-fubini
    dimensional reduction
    fischler-susskind mechanism
    flat direction
    fundamental string
    gepner model
    green-schwarz mechanism
    matrix model
    matrix theory
    w string
    world sheet
    inheritance principle
    noncommutative geometry
    type I
    type IA
    type IB
    type II
    type IIA
    type IIB
    Dn-brane, n=0,1,...,8
    tachyon condensation
    vertex operator
    Last edited: Jun 10, 2004
  20. Jun 11, 2004 #19


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    It looks like no one here can improve on the Spires search I just posted.
    I would be delighted if someone could come up with a better keyword formulation that would get Spires to produce more papers. But unfortunately no useful suggestions have been offered so far.

    If anyone would like to try improving, see if you can get more than 1677 papers in 2002, which is what I got with
    fin k string model or matrix model or membrane model and date 2002

    (it's a challenge :smile:)

    What that means is "find keyword string model or matrix model or membrane model and publication year 2002"

    The controlled list of 2000 admissible keywords is maintained by German librarians at DESY and they do not want you to say brane, you are supposed to say "membrane model".

    It is a superior kick-ass system, the best in the world for HEP, but you have to be willing to say "matrix model" and NOT to say M-theory.

    Anyway, you say that
    fin k string model......
    thing that I told you and it translates to this:


    and you get 1677 stringy papers for 2002

    i would be real suprised if Spires HEP database had more stringies to give you than those. But please try!!!

    "These are just a few terms under which you'll find stringy papers. I really do think you need to be expert on string theory to properly collect this sort of data and analyze what it actually means."

    Not at Spires you wont. I guess we need a tutorial on the Spires HEP database.

    In the preceding post's list of over 90 words and phrases all but one of which would be useless as keyword inputs to Spires,
    and that one useful term was one I was already including: matrix model.

    Spires has a great "Help" section with lots of examples.
    Spires is easy to use and I believe all working physicists doing research in HEP must already be familiar with it.

    None of this is news to any bona fide research people who might look in at PF.

    Spires was obviously designed for the ordinary physicist and physics student to use----it's easier than the catalog at our local public library BY FAR :biggrin:

    Spires is a joint project of Stanford/SLAC and Fermilab and DESY (Germany) and some other national HEP centers. Here is the list of some 2000 keywords that is maintained by the DESY librarians.


    note the abbreviation of "schlagwort" for keyword.

    If you want to do a Spires keyword search, you choose from that list.
  21. Jun 11, 2004 #20


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    As I said...

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