Jack of Harts

One of the more interesting theories I have heard from the days before Contact is that maybe we had not talked to anybody because they were too alien to talk to.  Maybe they had a completely different style of technology than us, or no technology at all.  A genetic organism capable of space flight for instance may have nothing like radio or radar for us to even recognize.  It did not turn out that way, but many still speculate that they could be out there.