  Gamma ray bursts (GRBs) are the most luminous physical phenomena in the
universe. The relativistic effect on the blast wave associated with the GRB
introduces the gamma factor. Here we put an upper limit on the gamma factor via
constraints on maximal power allowed by general relativity and hence set upper
limits on other observable quantities such as deceleration distance. Also upper
limits are set on the high energy particle radiation due to constraints set by
cosmic microwave background radiation.
