I would like to step up from the pop-sci level of understanding LQG to something more like a real physicist's understanding, but one thing that's hanging me up is the SU(2) stuff, which I don't understand, even at a hand-wavy level. Falling back to the pop-sci level to regroup, I remembered that Lee Smolin had an article on LQG, "Atoms of Space and Time," Scientific American, Jan 2004. Its discussion of spin foams is actually more detailed than in his pop-sci book Three Roads to Quantum Gravity. In the diagrams in the paper, the nodes and lines are labeled with integers representing volumes and areas. How would those integers relate to the SU(2) stuff?(adsbygoogle = window.adsbygoogle || []).push({});

[EDIT] After posting the above, I found this, which seems to help a lot: http://math.ucr.edu/home/baez/foam/

[EDIT] This paper by Smolin is also helping me to understand the Baez talk: http://xxx.lanl.gov/abs/gr-qc/9702030

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# Smolin's Scientific American article on LQG

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