Editing Path integral formulation (section)

== Quantum gravity ==
Whereas in quantum mechanics the path integral formulation is fully equivalent to other formulations, it may be that it can be extended to quantum gravity, which would make it different from the [[Hilbert space]] model. Feynman had some success in this direction, and his work has been extended by [[Stephen Hawking|Hawking]] and others.<ref>{{harvnb|Gell-Mann|1993}}</ref> Approaches that use this method include [[causal dynamical triangulation]]s and [[spinfoam]] models.