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A little applet that does 6j and 3j

  1. Jul 6, 2003 #1


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    I just happened onto an online calculator that does 6j symbols


    If you try it, you may find trouble reading the square root
    sign. It looked like a vertical bar to my browser.
    But you can tell it is the sq.rt. because of what the numbers are.

    I like the commonality of things that are online
    You dont have to have Mathematica on your computer
    for this, anyone in the world can calculate a 6j symbol.

    Baez and friends have been calculating spinfoam amplitudes
    getting from one geometry to another just as
    one calculates feynman diagram amplitudes of some
    process. The calculations are reminiscent and depend on
    some computer whiz discovering an efficient algorithm
    to calculate "10j" symbols. Aiiieeee!

    A recent paper based on calculating foams using 10j symbols
    Baez et al "Spin foam models of Riemannian Quantum Gravity"

    have to go
  2. jcsd
  3. Jul 7, 2003 #2


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    Daniele Oriti's paper

    Daniele Oriti has written an informative introduction to spin foams


    6j symbols come in at page 20, in case you were wondering :wink:

    Oriti is a grad student at Cambridge. I think he writes well. Here's the title and abstract:

    Spacetime geometry from algebra: spin foam models for non-perturbative quantum gravity
    Daniele Oriti
    Department of Applied Mathematics and Theoretical Physics,
    Centre for Mathematical Sciences, University of Cambridge,
    October 15, 2001

    This is an introduction to spin foam models for non-perturbative quantum gravity, an approach that lies at the point of convergence of many different research areas, including loop quantum gravity, topological quantum field theories, path integral quantum gravity, lattice gauge theory, matrix models, category theory, statistical mechanics.

    We describe the general formalism and ideas of spin foam models, the picture of quantum geometry emerging from them, and give a review of the results obtained so far, in both the Euclidean and Lorentzian case. We focus in particular on the Barrett-Crane model for 4-dimensional quantum gravity.
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