Receiving a signal would be one of the more chilling things the Earth civilization can ever experience.
Good thing if these guys would be on approximately the same stage as we are, but chances are slim. An answer from someone who knows about radio for 1000 years in much more probable than from someone who knows it for 100 years, as we do.
Meeting the technologically more more advanced European expeditions did change the lives of the natives of the Americas, probably to the better, after a few centuries — if we ignore certain details.
We're pretty close to being capable of launching a Bracewell-von Neumann probe if some billionaire had the urge to do so. But so far as we can tell, the galaxy is not already full of self-replicating interstellar probes. Where are they? The uncomfortable implication is that we are the first/only species to get this far.
Good thing if these guys would be on approximately the same stage as we are, but chances are slim. An answer from someone who knows about radio for 1000 years in much more probable than from someone who knows it for 100 years, as we do.
Meeting the technologically more more advanced European expeditions did change the lives of the natives of the Americas, probably to the better, after a few centuries — if we ignore certain details.