  Since the discovery of the cosmological origin of GRBs there has been growing
interest in using these transient events to probe the quantum gravity energy
scale in the range 10^16--10^19 GeV, up to the Planck mass scale. This energy
scale can manifest itself through a measurable modification in the
electromagnetic radiation dispersion relation for high energy photons
originating from cosmological distances. We have used data from the gamma-ray
burst (GRB) of 6 December 2002 (GRB021206) to place an upper bound on the
energy dispersion of the speed of light. The limit on the first-order quantum
gravity effects derived from this single GRB indicate that the energy scale is
in excess of 1.8x10^17 GeV. We discuss a program to further constrain the
energy scale by systematically studying such GRBs.
