Aliens

I agree strongly with what CRAI is saying.
There is no possible way we are the only life forms out there.
But if we did end up meeting someday, its likely we would not be at all compatible.

Just think about how different people are from continent to continent on earth.
Meeting someone from another planet would likely be pretty confusing as I am sure they wouldn't even talk the same way we do.
And if they did, no chance in hell would it be a language we know about on earth.

It would probably be better if we just stayed and rotted on our own planet.