Oblivion and More on (Im)Plausible Alien Invasions
By Taylor Marvin
[Oblivion spoilers are marked below]
Last weekend I saw Oblivion, a new entry into the venerable Hollywood alien invasion genre. With stunning visuals and occasionally impressive acting, I found the film enjoyable, and despite its plot holes entertaining.
I’ve previously discussed how difficult it is to invent a plausible motive for an alien invasion of Earth. Unfortunately, Oblivion’s script isn’t particularly inventive in this department — the film’s writer is mostly content to recycle old tropes under a gleaming facade of modern CGI and gorgeous cinematography (seriously, Oblivion is beautiful). But since alien invasion stories in general are such an interesting topic of discussion, reflecting on the Oblivion’s plausibility is a fun exercise.
Of course, discussing alien invasions stories is inherently a discussion of aliens themselves, and speculating on any aspect of aliens’ behavior — especially the plausibility of their Hollywood invasions — is inherently dangerous. But as I wrote in a recent discussion of Cowboys and Aliens, aliens broadly similar to us — in economics if not physiology — would face enough universal limitations that informed speculation is possible:
“The only thing we can assume about alien civilizations is that, well, they’re alien. It’s very difficult to make any assumptions about how an alien civilization would be organized, what they would value, and how they would behave. But we are able to identify universal constraints, and extrapolate which of these constraints aliens’ incentives are bound by. No matter how alien, there are certain limitations that we can assume all technological civilizations are bound by…. The galactic scarcity of certain chemical elements is also universal, as is some degree of natural selection within and between species.”
Unfortunately, Oblivion mostly disregards these questions of plausibility. Of course, this doesn’t make it a bad movie per se, or even bad science fiction; the protestations of science fiction fans who use “hard” as a synonym for “good” aside, plausibility is overrated. But it does suggest interesting questions.
First, Oblivion’s opening minutes establish that humanity successfully defeated the invading aliens with nuclear weapons. This is a welcome departure from the frequent nukes-didn’t-work trope, but it is difficult to think of a plausible way that nuclear weapons would be particularly helpful in a contemporary conflict with aliens. While nuclear weapons are often discussed as plausible weapons in space combat (though in the vacuum of space a nuclear device has a much smaller destructive radius than in an atmosphere), in Oblivion’s scenario humans are confined to Earth, and are shown to have used nuclear weapons against alien surface targets. This implies that the aliens landed ground forces, forces vital enough to their war effort that their destruction ensured their defeat.
But why would the aliens land ground forces anyway? It is frequently noted in contemporary strategic studies that airpower cannot take or hold ground, but this limitation would not necessarily apply to the aliens. A civilization capable of routine interstellar flight is also presumably capable of arbitrarily detecting and destroying even hardened ground targets. This means that if humans are unable to threaten alien standoff weapons platforms or otherwise interfere with their bombardment and the aliens have sufficient spacecraft to cover all surface war zones, ground forces are unnecessary.
Anyway, the aliens aren’t seeking to hold ground at all; they are simply trying to kill enough humans to prevent humanity from interfering with the aliens’ plan to steal the Earth’s resources. This genocide can certainly be accomplished from space.
[Begin major Oblivion spoilers]
Halfway through the film the aliens’ motivations become more clear. The film’s leads characters Jack and Vica learn that have been mislead, and they are not the last remaining humans on Earth. Contrary to what they (and the viewer) has believed, the massive spacecraft in orbit is not humanity’s refuge but is instead the alien adversary responsible for Earth’s devastation. Jack and Vica, with their memories wiped, have been working for the alien, fending off attacks from the remaining desperate humans and protecting the alien’s massive machines gathering up the world’s oceans. Interestingly, this is the exact invasion motive of another alien invasion blockbuster, Battle: Los Angeles — in both films the aliens are after the Earth’s water. Water itself isn’t a worthless commodity: it is necessary for many plausible biological processes and can be used as reaction mass in advanced spacecraft engines. But, like in Battle: LA, it is a totally implausible motive for invading Earth. Water is one of the most common resources in the universe. Even if the alien depleted the water resources in its home system, it is unlikely to come prospecting in ours. We know that there are no visible intelligent civilizations around nearby stars — certainly none engaging in massive system-wide resource extraction — meaning that Earth far, far away from any hungry aliens. A civilization that valued water could certainly find it closer to home.
But even if the alien did judge our solar system’s water resources to be worth the energy expenditure necessary to get here, there is no rational reason to gather water from Earth itself. Ice is extremely common in the outer solar system, where it is not deep in a gravity well. Even for the extremely technologically advanced Oblivion alien transporting the mass of Earth’s oceans into space would be extremely costly — there is no plausible reason for harvesting Earth’s water, rather than the wider solar system’s.
However, this suggests an interesting premise. Imagine an expansionistic alien judged harvesting the solar system’s water a rational decision, and began dismantling several icy moons in the outer solar system. How would humanity respond? The alien could perceive the outer solar system as unclaimed territory — after all, no human has never set foot there. In our minds, however, the entire solar system would clearly fall in humanity’s domain, and the otherwise-non-confrontational alien would be seen as infringing on our territory and stealing our future resources. Would this situation lead to war? If so, would humanity be the aggressor — after all, harvesting the outer solar system’s water does no direct harm to humans.