Response of interferometers to the vacuum of quantum gravity

TL;DR

This paper analyzes the minimal effective quantum field theory of gravitons and concludes it predicts an unobservable tiny length variation, implying any detectable large quantum gravity effects would challenge current low-energy theories.

Contribution

It provides a clear theoretical prediction that standard low-energy quantum gravity effects are too small to be observed with current interferometers.

Findings

Predicted length variation is on the order of 10^{-35} meters.

No divergences or breakdowns occur in the low-energy effective theory.

Detection of larger effects would indicate new physics beyond current models.

Abstract

It has recently been suggested that exotic quantum gravity effects could lead to large vacuum fluctuations, potentially observable with realistic detectors. Experiments are currently being built to search for these signals. Here we analyze the minimal model of quantum gravity at low energies -- the usual effective quantum field theory of gravitons -- and show that it unambiguously predicts an unobservably small variation in the measured interferometer length $\Delta L \sim \ell_{\rm pl} \sim 10^{-35}~{\rm m}$. In particular, there are no divergences signaling a breakdown of this calculation in the low energy regime. Thus, detection of a large, gravitationally-induced length variation would signal a severe breakdown of effective quantum field theory in low energy quantum gravity.