If intelligent life were very likely, then it would arise early in the lifespan of a planet. You can estimate how many difficult steps one has to go through in order for evolution to bring ourselves about. The answer seems to be about four really difficult steps which makes this pretty unlikely. (The possibility of intelligent life evolving on another planet may be tiny, but if you multiply it by all those stars out there don't you have millions of possible civilizations?) This kind of math I'm doing gives you an upper limit, and that upper limit is high enough that it is possible that there could be a few other civilizations but they're going to be few and far between and thereby hard to detect. (Maybe the model for intelligent life is completely different than us?) Yes, but there are going to be some things that should be similar. Silicon life can't happen, the only life we can find is carbon-based life and it has to be something reasonably similar to its biochemisty to us. (Couldn't it have gotten a jump on us?) Maybe it's true, but I suspect if that's true these beings would be so different from us that we wouldn't have much to say to them anyway. (Does this change your outlook on life?) Yes, I would say at the end of this research I did look back on our beings and we have a kind of cosmic significance because we are the only example of intelligent life.