Time Delay of Radiation from Gamma-Ray Burst Sources as a Test for a   Model of the Universe
  The estimation of light velocity dispertion caused by quantum fluctuations influence on electromagnetic wave propogation in four-dimensional space-time is presented. Analytical cosmological solutions for the flat and open Universe for the case of cosmic vacuum model are obtained. The time delay of cosmic gamma-ray burst radiation is calculated. The delay is explained by propogation of dispersive electromagnetic wave in the expanding Universe. It is shown that the delay value depends on a model of the Universe. We conclude that to discern a model of the Universe measurement accuracy of parameter \Delta t / \Delta E_{\gamma} should be better than 10^{-5} s / MeV. 
Yu. S. Grishkan, V. B. Petkov, E. G. Vertogradova (Institute for   Nuclear Research of RAS)