Despite decades spent scanning the stars for evidence of extraterrestrial life, intelligent or not, we have yet to find evidence of aliens elsewhere in the universe - or at least according to public record (but let’s agree set that skepticism aside for now). Our technological capabilities and modes of space travel still limit our search to a relatively small area of space for now, but there's also the depressing and slightly terrifying possibility that the fruitlessness of our searching could be for other reasons.
For all we know, our definition of “life” might be too narrow and rely too heavily on what we have observed of the various forms life takes here on Earth. Aliens could be right under our noses and we might just be unable to perceive or detect them due to our sensory and/or technological limitations. Still, many SETI scientists are confident we’ll find those elusive aliens within just a few years as our methods continue improve. According to a new theory presented at the annual conference of the American Astronomical Society, however, that confidence might be unfounded.
The theory was presented by Dr. Alan Stern, a planetary scientist who has extensive experience working with NASA and private space firms. After examining many of the recent breakthroughs in planetary sciences, Stern proposes that the reason we haven’t discovered alien life yet is due to the overwhelming abundance of frozen ocean worlds in the universe. Stern says that while these interior water ocean worlds, or WOWs as he calls them, may be a perfect breeding ground for life, their rather isolated nature could prevent anyone from detecting life both within them and without:
These environments are protected from numerous kinds of external risks to life, such as impacts, radiation, surface climate and obliquity cycles, poisonous atmospheres, and nearby deleterious astrophysical events such as novae and supernovae, hazards stellar flares, and even phenomena like the Faint Early Sun. Interior WOWs are naturally cut off from communication by their interior nature below a thick roof of ice or rock and ice, therefore do not easily reveal themselves.
NASA has been focusing their attention more on these types of planets lately since they commonly possess the geochemical conditions necessary for life and are believed to be found all throughout the universe. While many hopeful alien seekers might think this to be good news in the search for life, Stern points out that actually the opposite might be true. Just as we are likely blinded by thinking life elsewhere in the universe might follow the same rules that it does here on Earth, aliens on these interior ocean worlds might believe other alien races also live inside frozen planets, limiting their ability or rationales to search for signs of life in the cosmos. Worst of all, perhaps these hypothetical alien races might not even know the stars exist in the first place.
Could the universe be filled with alien races passing right in front of one another’s eyes (or other sensory organs) without ever realizing it? Could the biases of our human physiology and perspective limit our ability to detect and recognize alien life? It's possible, of course. It's also completely possible that we're all alone out here. But we've gotta know for sure.