Well... hehe. sad to see a great topic been reduced to a list of movies....
Actually, the harder i think of it, the more convined i am that we can never be alone. Why?
One, We are the proof that there is intelligent life forms out there. If u DARE say we are alone, may i post to you about our origin? May i gain the insights from you how does life come to been? The soup of chemicals which is present on early earth may have form the first 'living' material, virus. Which then mutates into the DNA, then a cell, then multiple cells merge to from an organism (bacteria) and then to what we know today.
Two. Conditions for life. Who say life needs sunlight, water and oxygen? Dive with the world best marine biologists and you would know the definations of conditions for life to exist is wrong. The new conditions is an energy source which an organism can harnest from and internalise it for their own use. Deep sea creatures often do not have oxygen as the oxygen dissolved in water concentrates near the surface and sunlight is alien to them. At that depth, the ocean is very dark and cold and the worms and mussels survive by chemosynthesis. They convert hydrogen sulfide from the vents as an energy source (instead of light) for the synthesis of proteins and carbohydrates.
Three, even if we must have sunlight oxygen, carbon, water, etc etc etc. There must be a planet with an environment justs like earth. For one, earth is one such planet within the millions and millions and millions and millions and millions of planets out there. seriously, logical deduction that there are millions of planets out there which is just like earth, once like earth, or going to be like earth.
Then we consider how does life come into being.
Then we consider that life does not ONLY need sunlight.
Then just like in the movie CONTACT. If we are alone, it a gigantic waste of space.
possiblity of us been alone = 8.90e-999999999999999 (guessing, but u get the idea)
Then similarly, these life froms have intelligent, if we have them, why can't they?
As such, could it be possible that we are actually primitives in the eyes of another? like monkeys compared to us? homo sai.... then again, are we truly, capable of true thinking in the view of another?