True. We are tied to our few perceptive faculties, understanding, and what we can measure from physical instruments. Science seems to be more open to the idea of parallel realities and universes these days, which is good, even if it isn't very pragmatic now. It is very likely inorganic life is the more ubiquitous manifestation of intelligence simply because of all the energy present, physical mass is the least common form. It is conceivable that inorganic life coexists with organic life without either entity being cognizant of the fact. Humans could even have the capacity to perceive such an entity if there were a survival incentive to do so or if our conscious minds were not so self-involved.

Personally, I think any civilization advanced enough to conduct interstellar travel would be a cooperative life form (organic life that is). Is it a coincidence that the most intelligent forms of life on earth are social and cooperative? Really once you think about it, pretty much all war on earth was rooted in not sharing resources, artificial boundaries, nationalism, religion, and poor resource allocation (i.e. the price system). These are all solvable problems that all to often get blamed on the "human nature," which I think is a convenient excuse fabricated by our minds in a petty attempt to rationalize our ages of suffering. Greed is environmental, not biological. Believe it or not nomads are pretty resourceful and respectful to one another and the environment; "modern" civilization seems to have an incentive to trade accountability for convenience--never really living within our means (crappy economies cut spending on space programs). We live on a small planet, and in even smaller paradigms restricted by all the arbitrary lines we draw on stuff we don't really understand for the sake of calling it our own. Exploring the empty, silent void of space, if not good for anything else, should be a humbling experience to truly discover how petty, yet fascinating our inner space really is.