Quantum fluctuations of the gravitational field and propagation of light: a heuristic approach

Quantum gravity is quite elusive at the experimental level; thus a lot of i nterest has been raised by recent searches for quantum gravity effects in t he propagation of light from distant sources, such as gamma ray bursters an d active galactic nuclei, and also in Earth-based interferometers, such as those used for gravitational wave detection. Here we propose a simple heuri stic picture of the quantum fluctuations of the gravitational held and use it to setup a mathematical framework to estimate quantum gravity effects in interferometers. We also discuss some other developments suggested by thes e heuristics.