Severe Limits on Variations of the Speed of Light with Frequency

Explosive astrophysical events at high redshift can be used to place severe limits on the fractional variation in the speed of light with frequency ( $\ensuremath{\Delta}c/c$), the photon mass ( ${m}_{\ensuremath{\gamma}}$), and the energy scale of quantum gravity ( ${E}_{\mathrm{QG}}$). I find $\en... View More