Non-locality from quantum loops

Question

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

Comments

If you have an exact reference for the paper, it wouldn't hurt to include it and is likely to help.

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