Phys. Rev. Lett. 109, 141103 (2012)

At the Planck scale, general relativity meets quantum mechanics. But what exactly takes place at this infinitesimal length scale (10−35 m) remains largely speculative. Vahagn Gharibyan, however, suggests that there might be a way to test Planck-scale effects using high-energy particle-accelerator experiments.

Theories of quantum gravity predict that — at the Planck scale — space-time has a crystal-like structure and refractive properties. Light from gamma-ray bursts and other astrophysical objects may display signatures of these quantum gravitational effects, but observations are limited by the uncertainty about the properties of these remote cosmological sources.

Gharibyan instead explores the possibility of glimpsing the effects of quantum-gravity-induced vacuum refractivity in Earth-based experiments: collisions between laser-generated photons and relativistic electrons from current GeV and planned TeV particle accelerators. He estimates that, from a length scale of 10−31 m down to the Planck scale itself, subtle changes should manifest in measurable effects in high-energy Compton scattering.