[SunkenCiv]

"But I am not really willing to accept your premise, because it may well be that the means of communications they have are of a kind that we do not know how to receive, and that they would not have the means of communicating with sufficiently powerful radio or optical signals. That is something which, technologically, is too difficult for them but they would have some other means we would not recognize." -- Thomas J. Gold, 'Communication with Extraterrestial Intelligence' (Sagan, ed)

[justa-hairyape]

There is yet another possibility. They don't want us to see them. We are quarantined. Surrounded by a filter. Entire solar system. Possible for a civilization 1 million years advanced.