[Sirius Lee]

The problem is when. Some scientists have posited that the amount of time a civilization with a comparable lifespan to ours has between developing radio and collapse from war/pollution/disease is 100-200 years.

I'll throw in a couple of other factors: If a species becomes technologically proficient as to develop radio as a medium of communication, it may be that the same species either develops some other means (leveraging quantum entanglement?) within 200 years, or perhaps recognizes that it might not be such a good idea to broadcast your existence out to a universe which is fundamentally hostile and/or hungry, and so they employ less leaky modes of communications (direct line of site lasers?)

[The Antiyuppie]

There is a lot of evidence in our own history that civilization “peaks” last only 50-200 years. Egyptians, Greeks, Rome, Persia, Byzantines, etc.