I don't believe it's aliens because I am strongly persuaded by the grabby aliens theory. We're either truly alone, effectively alone (any other civilizations a

I don't believe it's aliens because I am strongly persuaded by the grabby aliens theory. We're either truly alone, effectively alone (any other civilizations are so far away signs of their activity haven't reached us yet), or by a stroke of luck we are the very first highly intelligent species in the universe. There is a fourth option that also requires a stroke of luck, which is that there are in fact grabby aliens, that haven't reached our neighborhood yet. They may be traveling out in every direction at near c, and won't be detected until very shortly before arrival. There are other options I think are possible but those are more speculative and exotic.