When my great grandma was born, we didn't have flight, radar, lasers, radio, etc... Why would we think that a civilization capable of building massive space structures would be communicating in such a slow and imprecise way. The idea that we've discovered all there is to know about communication over vast distances is hubris.
We can't see anything because we have not yet discovered what we're looking for.
We can't see anything because we have not yet discovered what we're looking for.