Aren't we all 'alien' to each other? If you meant "extraterrestrials", then it could be possible that there is something out there. But, this galaxy alone is so huge, and we're only finding a small number of worlds (mostly super gas giants). Some rocky worlds, and one or two that may possibly support life, until we can do up close analysis of these worlds....we'll never know for sure. Also, if we do make contact-I sincerely hope Hollywood isn't right, and they're not friendly.