The First Alien Civilization We Encounter Will Be Extremely Loud

When we gaze up at the night sky, we assume that what we’re seeing is a representative population of similar stars at similar distances. But it’s not. The stars we see are a mixture of massive and small, distant and near. In fact, we can’t even see our closest neighbour, Proxima Centauri. We see these stars because they have large observational signals, and that illustrates one of the problems in astronomy.