The Search for ExtraTerrestrial Intelligence relies on trying to tune into the galactic radio broadcast. Well-established civilized civilizations may be broadcasting intentionally or unintentionally. SETI has yet to identify such a signal. One of the concerns is that civilizations may not tend to survive from things like wars; so, maybe we should look for signs of wars. Within the billions of possible civilizations, the odds are that at least some will have followed technologies familiar to us, like nuclear weaponry. One possibility, therefore, is to watch for the sad signs of nuclear war. It wouldn’t be communication, but we would learn a lot by knowing that there at least was life somewhere else in the universe.
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