In theory, they should be out there. While we have yet to find a planet that is exactly like ours, there are still many other planets out there, and it's completely possible that life exists without water, without air, etc. It's also completely possible that there is life, but it's unintelligent simple life (like bacteria). If there is only unintelligent simple life out there, that would explain why we haven't been contacted by them yet. If there is complex intelligent life out there, perhaps they (like us) have yet to discover how to travel faster than the speed of light, and (like us) don't want to send humans out into an inhospitable environment for thousands of years without knowing for certain if they will come into contact with intelligent life. If they have discovered a way to travel, and are willing to explore the unknown, perhaps they have yet to reach our tiny corner of the universe, or perhaps they are only observing the life they find, or perhaps they did exist, but have destroyed themselves with their own technology and wars - and perhaps that is where we are headed, as well.

Great question. Many things to think about. :)

Yes i believe that there are Aliens out there in space there is so much proof and evidence that it is amazing and there are pictures and videos and way back when the cavemen where around there where sightings of of UFOs and aliens,i mean how can people say that there is no such thing when even our own president and government knows all about it and they are hiding it from people ,because they wont have the power no more!!!!