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Cross fertilization between string and non string approaches.

  1. Oct 14, 2010 #1


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    Do you know people who work in both string and non string QGs, or who changed from string to non string or vice versa?
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  3. Oct 14, 2010 #2


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    Well sure, many people doing LQG-related stuff have done string. There is cross-over.

    But there is another dimension to the question you are asking. What about actual crossfertilization at the level of ideas?

    George Ellis (co-author with Hawking of The Large Scale Structure of Space Time) is a worldclass figure in cosmology and gen rel. Highly respected elder statesman. For his 70 birthday in 2009 he wanted to bring string and non-string QG people together in a conference and get them talking and sharing ideas. Cambridge Press has made a book out of the talks given at the conference. It is called Foundations of Space and Time.

    I would say that is a start, just a beginning to the kind of cross-fert that has to happen. There were people from several communities participating: LQG, string, CDT, classic GR, various stripes of QFT, sugra, I think also asymptotic safety. We have a discussion thread about it. Book scheduled to appear March 2011.

    The list of actual people who have crossed over is large and would be too much work to try to compile other than by casual mention.

    I will mention a few LQG and other nonstring folks who, if you go back you see they published some string research papers

    Leonardo Modesto (earlier string now mainly LQG)
    Sergey Alexandrov (likewise)
    Lee Smolin (earlier some dozen or so string papers)
    Aurelien Barrau (LQC phenomenology, earlier string phenom.)
    Alejandro Perez (mainly LQG, but has done string-related stuff)
    Matilde Marcoli (mainly NCG but has done LQG-spinfoam and string-related stuff)
    Jan Ambjorn (mainly CDT now, but still does occasional string)
    Renate Loll (mainly CDT but will do some string/matrix theory now and then)
    Stephon Alexander (has done a bit of border-crossing, not easy to describe)

    These are just the names that came to mind. Probably there are 20 others at least as obvious but I just didn't think of them. People at this level tend to be smart and alert to interesting problems in neighbor fields. There is nothing to stop them, if they see a problem they want to work on.
    For instance Laurent Freidel, a prominent LQG researcher, in 2008 presented a proof of AdS/CFT correspondence in the 3D/2D case with an explicit method to reconstruct bulk from boundary information. Maybe AdS/CFT is not exactly "string", but it goes to show how these people roam about---you can't always predict what they are going to work on or come out with.
    Last edited: Oct 14, 2010
  4. Oct 14, 2010 #3


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    AdS/CFT and LQG (spin networks) mentioned in the same breath on the last page of

    AdS/CFT and emergent gravity mentioned on the last page here:

    Wen's attempt at emergent gravity http://arxiv.org/abs/0907.1203 , may have some relation to Horava's attempt http://arxiv.org/abs/1003.0009 .

    And Markopoulou's work is informed by Wen's http://arxiv.org/abs/0911.5075

    So old fashioned LQG <-> Markopoulou <-> Wen <-> tensor networks <-> Vidal <-> AdS/CFT?
    Last edited by a moderator: Apr 25, 2017
  5. Oct 14, 2010 #4


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  6. Oct 15, 2010 #5


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    Thanks, I knew only of Smolin being ex-string theorist.
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