This afternoon there will be a colloquium at my university on the topic of GRBs causing mass extinctions. It sounds like a pretty interesting topic and so I want to know what you guys think about it. Here is the offical email that was sent to my FSU account: There are two main theories about the sources GRBs. One, which I favor is the hypernovae hypothesis. The other, which this guy probably believes in, is the collision of neutron stars with other neutron stars, or neutron stars with black holes.