Hi janop! I also believe that it could be possible for life to exist in ways that we just can´t detect by any of our current means. Maybe there are some forms of "energy" or "matter" that we just can´t detect, like centuries ago when cells and microorganisms were completely unknown to us. Maybe they even populate our solar system and we can´t detect their presence. And maybe even we can´t be detected by some of them. Who knows...