"Sometimes I think that the surest sign that intelligent life exists somewhere is the fact that none of it had tried contact us."
Calvin & Hobbes
I ran across this quote in an X-Files fanfic. Personally, I think it’s just as likely that somebody did bop in for a quick check, took one good look around and got the hell out of Dodge as fast as their little afterburners could take them. They took one quick run around the outer limits of the solar system planting beacons as they went. All the beacons have the same message. “Enter at your own risk. Beware of that beautiful little blue marble third out from the local star. Their weapons may be primitive but they have a lot of them and they aren’t shy about using them. If you do insist on dropping in for a visit, please register you vital information and ship registration so we can notify your next of kin. Message repeats.”