Quantum Gravity is quite elusive at the experimental level; thus a lot of interest has been raised by recent searches for quantum gravity effects in the propagation of light from distant sources, like gamma ray bursters and active galactic nuclei, and also in earth-based interferometers, like those used for gravitational wave detection. Here we describe a simple heuristic picture of the quantum fluctuations of the gravitational field that we have proposed recently, and show how to use it to estimate quantum gravity effects in interferometers.
