SETI has spent many years searching for alien signals coming from the central area of our galaxy (in and near the constellation of Sagittarius) where there are more stars. However, complex life could not evolve in such places because of more frequent powerful gamma ray bursts of deadly radiation from the merging of black holes and neutron stars.

They have recently realized they should have been looking at the outer areas of the Milky Way, where stars are far apart and collisions between black holes and neutron stars are rare events. We at 27,000 light years from the center of our galaxy are much less likely hit by powerful gamma radiation, it usually becomes too weak to be damaging by the time it reaches us although we do detect it.

It is possible that "the great dying" (Permian-Triassic extinction event) 250,000,000 million years ago was caused by a powerful gamma ray burst.

Complex life may be possible in only 10% of all galaxies