I am reading a paper on quantum gravity (written circa 1988 but I don't think it's relevant to give a more precise reference) where I read the following statement: "universe loops will in general induce nonlocality, just as field theory loops induce nonlocality in relativistic-particle path integrals, and string loops induce nonlocality on the world-sheet". And to be honest, it's really unclear, I can't argue about the string theory case as I barely know anything about it, but regarding QFT, if those loops are the quantum corrections (appearing in an $\hbar$ expansion for example) I don't see how it is nonlocal, although it could be Wilson loops, then I'd like to know if the "path integrals" mentioned in the quote/article are the path ordered integral of the Wilson loops or the path integral of the partition function (or any correlation function). I hope that my question is clearer than my mind right now.

Thanks.

This post imported from StackExchange Physics at 2014-05-01 12:19 (UCT), posted by SE-user toot