good question....
i think we as humans on one small planet would be naive to believe we are the only being in existence in the universe with it being so vast..
the issue is, in what form would these aliens be in..would it be in a similar form to ours of would they have a different make up..possibly breathing different gases than what we do..
judging by the many many sightings over the past up till now, seeing unidentified craft and such like and also alien beings...whats to say that there isnt something in it..
we all know theres many hoax perpetrators but can they all be hoaxes...??
it would be interesting to get peoples views on this as this has interested me for as long as i can remember.