While the use of spin networks has greatly improved our understanding of the kinematical aspects of quantum gravity, the dynamical aspects remain obscure. To address this problem, we define the concept of a ‘spin foam’ going from one spin network to another. Just as a spin network is a graph with edges labeled by representations and vertices labeled by… (More)

@inproceedings{Baez1998arXI,
title={ar X iv : g r - qc / 9 70 90 52 v 2 1 7 D ec 1 99 7 Spin Foam Models},
author={John C. Baez},
year={1998}
}