If we contact a civilization capable of interstellar travel, that civilization would also likely have the capability of wiping us off of our own planet in a day or less. They probably wouldn't, since there's nothing we have that they would want.. but it's within the realm of possibility.
If they did have interests on our planet, it would likely be from their anthropologists and archaeologists. That portion of their population would probably be larger than our entire planet's population of humans. If that were the case, they wouldn't come visit alien-to-person. They'd send probes.
They likely also have populations of aliens who are interested in very obscure hobbies larger than our own.
Because of that possibility of being wiped out, we ought to keep our radio noise to a minimum-preferably radio silence.
Our signals haven't traveled much further than about 200 light years out. From what we can tell, we're utterly alone. Maybe we really are completely alone in the universe. Or the solution to the Fermi paradox is we're the first one. Or the alien signals haven't reached us yet.
If they're listening, we're already fucked. Can't stop what EM radiation we've already leaked. But we could STFU right now and hope nobody is listening at the right time.
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