Constraints from undetected gamma-ray sources

The number of positive gamma-ray source detections by the Compton Gamma-Ray Observatory has been large, and the significance of the results has been substantial, as is described in other reports at this conference. In addition, searches for gamma rays were made that have led to null results, but that nonetheless deserve attention because of their important scientific implications. In the gamma-ray observations there has been as yet no indication of antimatter in the universe other than that produced in cosmic-ray interactions. The upper limit for microsecond bursts has implications for attempts at unified theories of physics. The search for signatures from supersymmetric particles has not revealed any positive evidence. The measurements of the high-energy gamma-ray emission from blazars and its interpretation in terms of the relativistic particles and their origin has been one of the highlights of the EGRET results. However, there are a few flat-spectrum radio quasars that are very strong in the radio reg...