Some of the Most Plausible Scenarios for Alien Civilizations

We have yet to make contact with an extraterrestrial intelligence, making it exceedingly difficult for us to imagine what an alien civilization might be like. But that doesn’t mean we can’t make some educated guesses. Here’s what we know — and don’t know — about aliens. » 11/04/13 11:00am 11/04/13 11:00am