I don't think we will ever know or meet an alien. But it should be no question if they are out there if you just think about it there are billions of stars and planet out there maybe even more i once herd something about there being more stars and planets out there than we have grains of sand on the planet earth. that is alot of chances for life to start an alien could be some fish in a puddle on another planet or just one single cell. but we will never know space is just to large and earth don't have that much time. so the chance of them existing is 100%.