 If civilization A sends out colonists to become civilization B, and they send out others to C and D and E, what's the lifetime? It's the sum of all the lifetimes of the other ones. But they don't want to admit that there's colonization or migration going on, because if that's going on, then they could be coming here. And we can't have that, because that would mean that we should learn sign language instead of listening with radio telescopes. So it's a whole web of...