Quantum gravity without vacuum dispersion

Understand

A generic prediction of quantum gravity is the vacuum dispersion of light, and hence that a photon's speed depends on its energy.

• We present further numerical evidence for a scale dependent speed of light in the causal dynamical triangulation (CDT) approach to quantum gravity.
• We show that the observed scale dependent speed of light in CDT can be accounted for by a scale dependent transformation of geodesic distance, whose specific functional form implies a discrete equidistant area spectrum.
• We make two non-trivial tests of the proposed scale transformation: a comparison with the leading order quantum correction to the gravitational potential and a comparison with the generalised uncertainty principle.