just a thought, i believe that it is absolutely impossible that life does not exist on other planets throughout the universe, however we don't know how advanced they are. there is always the possibility that we might somehow mess up their evolutionary process if we interupted them, not only that, but there is always the possibility that they are barely more advanced then us, if they communicated with us tomorrow then they could be asking us for help, or even permission to colonize our planet, just think how this would affect exceptionally religous people, they might react the same way all humans have when we came into contact whith new ideas and new people. not only that, but what if they messed up our evolutionary process, what would become of us then? if anyone is interested, there is this really good series sci-fi books by Octavia E. Butler, called Lillith's Brood, or in the single books, the first one is called Dawn. check it out, i love them.