Year: 2012
Type: article
Abstract: In perturbative QED, the approximation is improved by summing more Feynman graphs, while in non-perturbative QCD, by refining the lattice. Here we observe that in quantum gravity, the two procedures may well be the same. We outline the combinatorial structure of spinfoam quantum gravity, define the continuum limit and show that under general conditions, refining foams is the same as summing over them. The conditions bear on the cylindrical consistency of the spinfoam amplitudes and on the presence of appropriate combinatorial factors, related to the implementation of diffeomorphism invariance. Intuitively, the sites of the lattice are points of space: these are themselves quanta of the gravitational field, and thus a lattice discretization is also a Feynman history of quanta.
Source: Classical and Quantum Gravity
Authors: Carlo Rovelli, Matteo Smerlak
Institution: Centre de Physique Théorique
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2124572913