First of all, how could we possibly be certain that ALL life breathes oxygen, needs water, requires food....we cannot IMO. so if it should not be the case, the possibilities are limiteless...
2nd, We look for physical life, either microbial or humanoid or reptilian.....what if this "life" is energy and not physical? Yes I do mean just like ghosts/spirits....looking for physical proof would be pointless as there would not be any.
So I think that life is out there for sure but we are probably too materialistic & violent for them to show themselves to us....one day we will get our answer.
Again this is just MY own opinion/idea on the subject and in no way do I have proof of this...just my little hamster spinning his wheel up there!


