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Space and state, spacetime and process

  1. Jun 5, 2004 #1

    john baez

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    Peter May and I are about to run a workshop on n-categories at the Institute for Mathematics and its Applications:


    We'll mainly be trying to compare different definitions of n-categories, but there will be an afternoon about applications of n-categories to mathematical physics, especially topological quantum field theory. Since most of the audience won't be experts on physics, I'm giving an introductory talk which may be of interest to some people here too:


    This includes some of the math I deliberately left out of my paper "Quantum Quandaries: A Category-Theoretic Perspective":


    Check it out! You can also see transparencies of two of my n-category talks.

    John Baez
    Last edited: Jun 5, 2004
  2. jcsd
  3. Jun 5, 2004 #2
    Is there any PDF format for these papers?..I tried the links, but could not get any info, may be a problem with my computer though?
  4. Jun 5, 2004 #3


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    One has the memorable arxiv number of


    but, Olias, I think you have seen that one already. In any case it
    is available from arxiv in PDF


    since you are in UK you will probably be using the UK mirror

    others may be inPDF also, I will let you know if and as I find them
  5. Jun 23, 2004 #4

    john baez

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    You can get a lot of papers and transparencies of talks here now.

    This and my other two talks are available in PDF now, not just Postscript. Thanks for asking, Olias.
  6. Jun 23, 2004 #5
    Wow, great files.
  7. Jun 23, 2004 #6


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    This is the wrong forum for this stuff. Move it to the math forums.
  8. Jun 24, 2004 #7


    I appreciate seeing the difference between strings and LQG in terms of describing quantum gravity. We can see this, in terms of continuity in strings....


    and discreteness in LQG.....


    Is this not the fundamental difference between the two?
    Last edited: Jun 24, 2004
  9. Jun 24, 2004 #8


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    sol you have quoted Yaron Oz in your last post, or an article from march 1999 in CERN courier paraphrasing Oz.
    It makes a striking contrast with the mood nowadays!
    I appreciate seeing the difference----showing the optimism of 5 years ago.
    (I hope I am reading your article correctly)
  10. Jun 24, 2004 #9


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    Thanks also to John Baez for following up on this!
    Actually this discussion of how category theory is applied to quantum gravity----and other physics----got started some here at PF some months back with a post by arivero
    (Lethe, selfAdjoint, myself, others participated)

    or even earlier

    Most recently I think, we were looking at Baez
    quantum gravity paper
    "Quantum Quandaries"
    which shows relevance of so-called "star-categories" to physics.
    and led to some of us wanting to look into the June workshop
    that Baez and somebody else organized

    the workshop is on n-categories and their applications
    one of the most interesting applications being to physics, at least
    in my view

    it strikes me as hard to comprehend but from a quantum gravity
    perspective something one should know something about
    (at least at the quant-ph/0404040 level)

    there is some more discussion of this at the Fotini thread
    Last edited: Jun 24, 2004
  11. Jun 24, 2004 #10
    yes of course.

    One of the pictures was taken from John's Baez' article made avaliable through John's links.


    Using strings wrapped and dividing in the pant style[ topological considerations ](quoted article), in relation to todays conclusions, I wanted to draw attention to the way in which Quantum gravity is looked at with these two models. This hasn't change from 1999, in terms of continuity and discreteness. This is a foundational principal of how quantum gravity is looked at between these two camps.




    Simscience and Quantum Gravity

    This link helps you see the issues

    I am open to corrections here.
    Last edited: Jun 24, 2004
  12. Jun 30, 2004 #11
    So is the quantization scheme mentioned above basic simplicial homology. If not, how does it differ?
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