The concept of alien life visiting Earth, particularly in ancient times to plant the seeds of knowledge amidst early human minds, has gone through a renaissance over the last few years. Every few decades, trends (including this one) will appear to go through short little bursts of revitalization, almost like mystery signals leaping from the otherwise desolate void of space, and calling to us with promises of things greater and more distant than ourselves or the knowledge we have attained.
While the concept of "ancient aliens" has been entertained by some of the brightest minds, the concept is generally attributed to--of all people--Carl Sagan, who posited as early as 1966 that what he called paleo-contact might account for knowledge brought to Earth by extraterrestrials, in a book he coauthored with astrophysicist I.S. Shklovski called Intelligent Life in the Universe. Earlier roots predating Sagan and Shklovski's writing have been linked to H. P. Lovecraft and his mythos of "Elder Gods" who could fling themselves about the stars, and occasionally land here on Earth to wreak havoc.
More recently, the theme of "ancient aliens" may have arisen again in the realm of science literature, but in a far more literal sense: that having to do with alien civilizations so old that they are, quite literally, ancient.
The recent discovery of a planetary system dubbed Kepler-444 had spurred discussion about what astronomers refer to loosely as a "period of planetary formation." Kepler-444 is around 117 lightyears away, and is only about 3/4 the size of our own Sun. Its planets, though smaller than Earth, are surprisingly bright, becoming visible on a clear night using only slight magnification that a good pair of binoculars might provide.
Following a statement released by Kepler scientists on the discovery, io9 reported:
"Kepler-444 is the oldest known system of terrestrial-size planets," write the authors in the study. "We thus show that Earth-size planets have formed throughout most of the Universe's 13.8-billion-year history, providing scope for the existence of ancient life in the Galaxy."
Estimated to have been in existence for as much as 13.8 billion years--roughly the same length of time the Universe is believed to have been around itself--planets capable of accommodating the conditions of a "planetary oasis" the likes of Earth might have existed a long time ago. Which, of course, is another concept that isn't really new for science fiction fans:
The more literalist interpretation of "ancient aliens" would have such ancient, highly-advanced races visiting Earth to share principles of science, agriculture, architecture, and other concepts with ancient people; some believe that legends prevalent among some modern cultures, including the Dogon of Africa, indicate that these very sorts of interactions did occur. Critics of the idea argue that utilizing myths and cultural traditions to explain actual events on par with today's science fiction is entirely speculative, and unlikely at best.
But while we're mentioning the practice of speculation, let's assume for a moment that an advanced alien civilization did exist in ancient times. Presuming that they were indeed advanced enough, such a civilization might have harnessed the power of the atom, and perhaps even more than just atomic power. If advanced enough, our hypothetical alien race might have even harnessed technology that would bend the nature of time and space to their will, hence overcoming our most far-out ideas like warp speed, and even time travel. In the event that the latter were the case, what if purported alien visitations in the present day were, in fact, time travelers from the ancient past, skipping around to different points in history, and perhaps also to different planets in history, just as well?
It's entirely speculative, of course. But such possibilities, remote though they are, still provide us with minute quantities of intellectual fodder, and maybe somewhat more broadly than popular representations of "ancient astronauts" in various media today.
One big question about life in our ancient universe entails whether the building blocks for life existed there too, rather than merely the possibility of planets capable of housing life. Based on our self knowledge, we know life can exist today, which strangely, might also be a bit theoretical when we consider the remote chance that our own existence might be a fluke, resulting in a singular one-off we call humanity, as suggested last year by physicist Brian Greene (which is novel, considering that Greene has in the past also given consideration to a multiverse; this begs the question whether dimensions parallel to our own might be any more capable of bearing the fruit of life than this one is).
If we're the only ones, perhaps the bigger question we should be asking today is whether we've always been the only ones, or perhaps whether at different times throughout the history of our Universe, different alien civilizations were the sole inhabitants of the cosmos for extended periods themselves, coping with frustration similar to our own so far as attempting to reconcile with whether or not others may exist.
Perhaps the only chance of finding evidence of intelligent life beyond Earth is the hope that, one day, rather than life that coexists with us in the Universe now, we may find evidence of life that once existed. Even if that were all we found, would it really require a living planetary civilization elsewhere to confirm our hopes and expectations about alien life? If anything, it might supply us with all the answers we need, and without the worry espoused by the likes of Stephen Hawking, who has warned of the dangers present in relations we may eventually have with alien civilizations.
In which case, we literally are getting all the best of both worlds... ours, and what remains of theirs.
Update: Readers pointed out an astronomical error--in the literal sense--above: that the star, rather than the planets of Kepler-444, are visible with proper magnification from a telescope or binoculars on clear nights.