In this post, I want to expand upon the idea of those alien devices.
Let’s assume the existence of a great number of technologically advanced races within a few hundred light years of Earth. That’s a very reasonable assumption. Let’s further assume that faster−than−light travel isn’t possible; that’s very probably the case. I think that developing a technologically advanced civilization requires curiosity about the universe and how it works. That implies curiosity about the possibility of intelligent life existing elsewhere, so I think it’s reasonable to assume that those advanced races are as curious about life on other worlds as we are.