Perhaps we are being shielded. Perhaps aliens don't indiscriminately broadcast signals. Perhaps they do but they are too weak to penetrate the noise by the ti

Perhaps we are being shielded. Perhaps aliens don't indiscriminately broadcast signals. Perhaps they do but they are too weak to penetrate the noise by the time they get to us. Perhaps they are encoded to match background radiation to all but those with the right cipher. Perhaps there is some sort of sub-space that messages can be transmitted on that we have yet to discover.