One possible way for extraterrestrials to assume control of the earth would be for human beings to leave or evacuate the earth – and then return to pick up where they had left off. While this might sound like a cop out on the premise at first reading, it should be noted as well that we are exploring an issue influenced by evidence available or circumstances differing from an earlier age of exploration thus far.
In the era of exploration five hundred years earlier, explorers headed west from Europe to reach the Indies and China not anticipating numerous native peoples in between them and their final objective. Looking back even farther, history abounds with tribes and peoples wandering across continents and encountering each other leaving for archeologists and historians numerous records of conflict. But in the 21st century, looking toward another age of exploration, we are perhaps anticipating inhabited continents where we have as yet no confirmation of a prospective India or China.
Over many centuries there has been occasional speculation that other worlds provided other sentient life. When 19th century astronomers in Europe and the United States began to debate whether markings observed on Mars were water channels, canals or simply blotches, speculation about extraterrestrials became ever more common. Science fiction writers in the 20th century provided a vast literature on the topic and the scientific community became involved as well with efforts to detect intelligent life or to debate what the likelihood was. During certain periods such as the early days of the Lowell Observatory in Arizona, expectations rose high that intelligent life was just beyond telescopic view. In other periods such as the first Mariner flybys of Mars revealing a particularly desolate swath of cratered terrain, expectations dropped very low. At this writing, detection of extraterrestrial microbial life within the confines of the solar system is considered an important pursuit of solar system exploration, but it is unresolved whether such exists. Further afield, detection of earthlike planets around other stars is anticipated by success in finding larger planets thus far, but it will probably require either longer observing periods with existing instruments or launch of more sensitive telescopes to identify worlds similar to our own from which to expect outer space visitors arriving here to expropriate us.
Going back to the 19th century excitement about possible canals on Mars, early science fiction writers led by H.G. Wells explored the implications of hostile martians colonizing Earth as though we the native life were little more than garden pests. Variations on this theme continued with updated information about technology, planets, biology, psychology, nuclear energy, but still one essential element has remained missing: a genuine example of extra-terrestrial life.
Absence of ETs is no reason to sneer at these creative exercises, some of them ingenious or classic within the limits of their domains ( though movie and TV adaptations tended to become monotonous or worn shticks after decades). But discussion of such comes with a caveat that without a single ET these novels are theoretical exercises for now; contingencies, yes but of uncertain possibility. Perhaps in another era they could become emergency manuals that could be broken out of cases, but the notions of our science fiction literature cannot be considered science if they cannot be tested against anything resembling a true alien.
Saying that we can proceed by describing some earthly ET schools of thought: In the era of Edgar Rice Burroughs martians could be attractive near human (“A Princess of Mars”) or otherwise in the same book as it suited the author, but these martians remained on their home world. Others, such as H.G. Wells and John Cristopher (“The Tripods”) modeled alien creatures much less like ourselves and more like squids with aims of doing the opposite of terra-forming to the Earth. When allowed to speak they seemed like the most ill-tempered malevolent professors on the faculty. Some have noted that the likelihood of martians or aliens resembling us is as likely that they would speak English, but owing to our own efforts to broadcast television into the void, perhaps it is more likely that aliens would speak English and not resemble us. For as time has passed, so has our television broadcasts’ light year radius of coverage. But as a result of our own reflections about life’s development on Earth, there is some consensus between readers and writers that ET would not closely resemble mankind. We are, of course, reminded that certain functional features are repeatedly used by nature such as eyes, ears, arms, heads, legs, internal organs, but so are fins, spines, exo-skeletons, tusks and horns.
For very large extremes in alien countenances I submit two novels by British astronomer Fred Hoyle whose first notion of an alien visitor to Earth (“The Black Cloud”) was a sentient interstellar-traveling so-named entity of astronomical proportions. The Black Cloud could have destroyed the Earth as much as taken it over, but it also used the visit to espouse Hoyle’s steady state cosmology. Fortunately Earth’s leaders did not argue in favor of the Big Bang, a label coined by Hoyle for the cosmological theory that eventually prevailed. Hoyle also suggested that alien life could transmit itself to earth as a radio signal and then be propagated as a result of following blueprints with computers and manufacturing facilities in a novel titled “A for Andromeda”. The movie “Species” borrowed much of its beginning from Hoyle, but turned into the usual alien horror story into the second reel.
…And so the list could go on, but we still have no genuine alien. Yet since humans are demonstrably extant and ET as yet is demonstrably not, then could we perhaps someday become our own alien nightmares or antagonists? At least one sf novel entertained this notion. In the 1970s Celia Holland, a historical novelist who typically wrote about the tumult for people on the frontline of Mongol or Ottoman empires in expansion, transferred her insights to a milieu two millennia hence in which the solar system had been colonized by our own distant descendants. Civilization’s centers had shifted to other planets where the populations had new cultures and even new genetic traits. Over shifting political alliances among more powerful planets or states, forces eventually march or descend on Earth to make war – or at any rate, to take over. Some of the details were fanciful or unlikely, but yet at the same time, there were depictions that seemed to ring true; if for nothing more than their consistency with earlier patterns of history.
Since Cecelia Holland’s work was usually about falling kingdoms or empires, the tone of this work was dark as well; darker than how I wish to conclude. But to a certain degree, the cosmos without any potential extra-terrestrial invader is a more lonely place than one which has barbarians beyond the city walls. Perhaps having extraterrestrial invaders someday who are our own kin would not be the end of the world but evidence of our future’s vibrancy.
