Originally published in Aurealis.
You haven’t seen your parents since the beginning of COVID, so you’re driving to their house for Christmas. Your one-year-old daughter is secure in the child’s seat in the back. This will be the first time she meets her grandparents. She has been crying for the first hour of the two-hour trip from Alabama to Georgia, but now she’s sleeping comfortably, her head lolling to the side. That’s a good thing, as the traffic is bumper to bumper with holiday travel, and you’re hardly moving.
Something soft and white floats onto your windshield. The first snow of winter! You wonder if you should wake your daughter and look up at the sky to see how cloudy it is. You gasp, the sharp intake of air piercing your chest and making your heart race. What you see emerging from the grey clouds can’t be real. A wide, circular disc has descended from space and hovers over the twisting highways choked with thousands of motorists. You look into the cars next to you. Everyone wears the same stupefied expression on their face. You gaze up again to see the belly of the disc slowly open to reveal a glowing exterior. A blue beam surges forth from the ship. You hear a booming rumble as light fills your vision, and you know no more.
The alien invasion narrative is a popular genre that began sometime in the late 1800s with H. G. Wells’ The War of the Words (1897) and continues today with movies like Roland Emmerich’s Independence Day (1996) and Chris McKay’s The Tomorrow War (2021). The storyline works because the stakes are easily identified—the destruction of the human race; and the goal is simple: to save the human race.
This binary choice is appealing to generation after generation of readers and moviegoers, but over the years, the concept of an alien invasion has come under greater scrutiny because of advances in human science. We are given motivations for an alien attack on Earth, but there are increased reasons to wonder if the explanations are rational, or even practical. Are there any circumstances under which an alien invasion would make enough sense for the invaders to undertake the expedition?
Alien invasion literature was first written by westerners as a metaphor for European imperialism. One of the first is The War of the Worlds, which depicts Martians invading Earth for our resources. H. G. Wells is drawing parallels with the British colonisation and harsh treatment of indigenous populations throughout the British empire during the 16th to 19th centuries. The Martians in The War of the Worlds engage in the ruthless killing of the human population for what is heavily hinted to be human blood, a source of nourishment for the invaders.
Of the reasonings behind an alien invasion, The War of the Worlds is the one of the most practical, not because the Martians were hunting for platelets, but because of the distance between Mars and Earth. Wells would have chosen the Red Planet because, in the late 1800s, scientists believed that life existed on Mars. Giovanni Schiaparelli, an Italian astronomer, thought he observed seas and continents on the Martian surface through his telescope in 1877. The War of the Worlds was released 20 years later.
Today, we know that if complex life existed on the fourth planet from the sun, it would have been hundreds of millions of years ago, if at all. However, the proximity of Earth to Mars makes a potential alien invasion more reasonable, in theory. With current manmade technologies, it takes seven months to travel from Mars to Earth. Assuming that an alien civilisation on Mars is slightly more advanced than Earth’s, and assuming they have ships that can travel from their planet to ours in half the time, then an invasion would become more rational, though still impractical because of the resources necessary to get ships from one planet to the other.
Sending automated rovers like Curiosity and Perseverance to Mars from Earth takes humans half a year, but it is expected that sending actual humans to Mars would be a year long journey with current technologies, rockets, and fuel. Most governments and private agencies currently seeking to send humans to Mars are considering only three to six individuals for initial missions. An alien invasion, as usually depicted in movies and books such as The War of the Worlds, transports hundreds, if not thousands, of enemy combatants to Earth. The effort such an undertaking would require would have to be significantly less than the bounty they hope to gain from such an invasion.
In movies like Joseph Kosinski’s Oblivion (2013), the problem of a biological-based attack, and all the resources it would take to support living entities composing the alien’s armed forces, are nulled. In this scenario, the Tet is an artificial intelligence that invades Earth and wipes out most of the human race so that it can convert our water into fusion. It clones its army from two humans, and even though it still must sustain the clones over an extended period, it would still, theoretically, require less energy than moving an entire invading force from one far point in space to another.
Somewhat like the idea of The Matrix (1999) using humans for their body heat to create a form of fusion, the Tet has chosen water instead, but faces the same logical problem as The Matrix. There would be easier and more efficient ways to create renewable sources of energy, and artificial intelligences would quickly realise this and work to figure out what they are. The Tet wants Earth’s water, but hydrogen and oxygen exist in abundance in other regions of our galaxy let alone in the Helix Nebula. The Orion Nebula is so vast that it creates enough water every day to fill Earth’s oceans 60 times over (NASA). Why would the Tet pass up this readily available source of hydrogen and oxygen to wipe out the native species of a planet instead?
Even today, humans, with our current technologies, have come to the conclusion that the greatest source of power will probably be our sun, a star. Invading Earth as the Tet does, capturing two humans to clone and unleash against the remaining population just to acquire common elements that are likely not the best source for energy, makes little sense for an advanced artificial intelligence already possessing the capability to travel throughout space.
Writers pen these plot lines because, as a narrative device, an alien species invading Earth for our resources is easy stakes for audiences to grasp. The problem is that this is also the least practical motivation for aliens to actually cross the vast distances of the cosmos in order to invade another planet.
However, there are several reasons that aliens might invade Earth. One may be a concept that is so alien that we cannot conceive it. Therein lies the paradox, as ultimately, no matter what a writer is writing about, whether it is aliens or dragons or rabbits, we are always only writing about ourselves: humans. We cannot truly write from a perspective of a completely nonhuman entity.
To circumvent this conundrum, writers are forced to write an alien invasion where the aliens invade for a reason that is never discovered or understood by humans. From a narrative standpoint, this will probably be unsatisfying to an audience. Knowing why the aliens are trying to kill humans helps suspend disbelief in order to more fully engage in the story. Simply having aliens attack, kill, and destroy in a seemingly mindless fashion is a harder narrative tale to make work for a wide audience. In movies, such as Matt Reeves’ Cloverfield (2008), where the origins-unknown monster seems to only have the goal to destroy, the question of the practicality of the “alien” invasion becomes moot since the monster is not planning an attack, but simply mindlessly destroying.
Jeff VanderMeer’s novel, Annihilation (2014) is an example of an alien that has come to Earth for unknowable reasons and has potential wide-ranging effects upon the entire human population. Whether or not the alien, the Crawler, constitutes an alien invasion is as debatable as whether the monolith in Stanley Kubrick’s 2001: A Space Odyssey (1968) is an alien invasion. The parameters of the alien invasion genre are often extermination or subjugation of the planet’s inhabitants, something one cannot say about those two narratives, though the widespread change both wreak upon the existing populations leads to extermination through radical transformation of the existing natives.
Another likely reason teased in the alien invasion genre explaining why an extraterrestrial species would invade Earth, despite the numerous obstacles the aliens would face, is that they hold a belief that drives them beyond concerns of mere survival. David Twohy’s The Chronicles of Riddick (2004) has Necromongers that are the equivalent to religious fanatics. Their technology allows them to travel through space with ease, so they are not after planetary resources. Instead, they are driven by a need to convert all sentient species they meet to their own religion.
An alien species that drifts through space and has a singular objective to achieve some abstract goal, the pursuit of which could be fatal to its continued existence, makes sense from a human perspective. People may object to the idea that we engage in irrational, counterintuitive and self-defeating acts that are extremely expensive and could lead to the downfalls of entire civilisations, but history is replete with such instances. Russia’s invasion of Ukraine is a current example of an aggressor engaging in military conflict for motivations difficult to ascertain despite the potentially fatal harm to the future of its nation. An invading alien force may not get very far or last for very long in its desire for extra-planetary conquest, but the technologically inferior species the aliens meet along the way may end up being destroyed until the invading species finally dies out as a result of its self-destructive crusade.
Finally, we are left with the invasive species storyline of alien invasion narratives, which you find in movies like John Krasinski’s A Quiet Place (2018), or more recently, The Tomorrow War (2021). In both movies, the human population is nearly wiped out by what seems to be mindless extraterrestrial species. In The Tomorrow War, the Whitespikes enter Earth’s atmosphere as eggs that are carried by an alien ship. This ship crash-landed on Earth hundreds of years ago and is buried within a glacier. With the climate warming, the ice melts around the ship and the eggs hatch, unleashing a plague of Whitespikes upon the planet similar to an invasive species of ants or locusts eating up everything in their path.
The question of practicality does not so much apply in this scenario since it is more of a catastrophic act of cosmic nature, an unfortunate happenstance for human civilisation. Just as a virus can suddenly jump from bats to humans and wreak havoc upon civilization for years, a rock can drop from the stars carrying an invasive species that brings humans to the brink of extinction. A large enough meteor, without the invasive aliens, would have a similar impact on human society for the same reason: terrible cosmic luck leading to disastrous results.
Ultimately, an intelligent alien species that can muster the forces to engage in extraplanetary warfare probably would not need any resources on Earth to justify the cost of an invasion. The extermination of the human race weighed against the cost of the extermination would also seem impractical. If humans could be destroyed by the aliens at ease, then what would be the rationale of going through with the elimination? Space is too vast to be worried about a race at the level of inferior technological advancement as humans. And if, and when, humans ever become technologically capable of being a threat to faraway species, the aliens would already be all the further ahead of us so that containment would probably be the most practical, cost-efficient solution. A simple hack of our computer systems would probably do more than all-out war to keep humans away from their civilizations.
But an alien species that has a completely incomprehensible goal for invading Earth, or an alien species that is driven by a belief that puts itself at existential risk, or a mindless invasive species that lands upon planet Earth by pure astronomical chance…these are probably the most likely circumstances for an alien invasion.
