It seems almost inevitable that life exists beyond our solar system, or possibly even within the confounds of such; siting evidence such as the recent discovery of liquid water containing organic molecules within the interior of Enceladus, and the ever growing rate of newly discovered exo-planets by the kepler space telescope. The emergence of life itself, and the complex genetic code that defines our very being (RNA and DNA), are to complex to be an accident, the way we are comprised of thousands of layers of symbiotic relationships is also to complex to be chance, it would almost seem as the universe imprinted itself with the self replication ability to create life, and we must treat it as such if we are to adapt and learn about life in the universe. I think as humans we have been to biased with our perception of what life is. On earth there are 3 general Kingdoms that all life forms living here fit into. Eukaryotas, Prokaryotes and Viruses. Eukaryotes include all multi-celled individuals on the planet which particularly included Animals and Plants, Eukaryotes include Bacteria and Archea, single celled organisms, and then there's viruses. Lets focus on viruses, in the widely accepted way of looking at a live biological system a Virus technically isn't alive, It cant self reproduce without a host, it doesn't have a complex, multi functioning collection of cells or organelles, basically its a strand of information that is cocooned inside some type of delivery system, however, these things are alive. The can Hijack and manipulate a particular protein and use it as its own appendage. How could it control the appendages without some form of understanding of the use of the protein. Even though it may not necessarily be a living breathing animal from our perspectives, life is much to complex for us to be biased in saying the 5 divisions of life discussed just prior are the only possible ways for life to manifest itself. Recently scientist from the university of Tucson have made incredible discoveries in micro-tubule vibratory frequencies in our brain, according to them, the individual neurons in our brains contain micro-tubules that have quantum vibration effects at a level beyond that of the atom. If these quantum effects are true and defining of the living experience then technically anything that is able to contain a quantum vibration and regulate it can be alive and conscious, bacteria, viruses and archea could have Quantum brains! What we really need to do is envision the prior and apply it to other principals, like energy and quantum effects. Maybe there is a self replicating, intelligent chuck of energy in the universe that uses this principal, if we discovered it, we'd have a very difficult time proving its validity, as it currently is with viruses. The universe is too vast and too powerful for us to limit its limitless possibilities with a limited perspective, a human perspective. For these reason I plead my case, the universe is probably comprised of many different bizarre and unimaginable life forms, who knows, maybe some photosynthetic floating critter is existent in the voluminous atmospheres of gas giants, or float through space, converting radiation to usable energy. Earth may be full of life but in my perspective, there's a possibility of 1.00.00.00,000 different styles of life forms using different mechanics for there specific existential states.
Aliens may exist, but no one has had a scientifically proven sighting and even if it is there was what are the chances of them living? They may be extinct for all we know. How would we find them or vice versa? Space is expanding even as we type ( See what I did there?). They will most likely die out before they're found.