Like Mytch said, we don't know....yet. But indeed, the sheer size of the universe makes it rather unlikely that we're alone. Although I wonder if more people would believe in space creatures if 2000 years ago some crooks had written a book about them.

We know that there is not life outside Earth.

do google on "xenology" and i think it will bring you some interesting readings. it's always two sides of the coins, believers against non believers. i'll step aside to the believers' side right after first time-machine is invented. but i will have turned into skulls and bones or even mere ashes at the time.

i think so. the myth of universe the power of nature, are the endless pursuit. we human being just one part of it.

Considering what we know about the vastness of the universe, by sheer math it is unreasonable to think that there is no life outside Earth. The more important question would be: Have we had any contact with them? I don't think we have, but that's just me.