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The Economics of Alien Invasion, Updated

By Taylor Marvin

I saw it. At the bottom of the page is what they got wrong.

Here’s the trailer for the upcoming film Battle: Los Angles:

This may or may not be a good movie. But it did get me thinking: if intelligent, advanced alien civilizations exist, what incentives would they have to invade Earth?

Though it’s impossible to reasonably speculate about extraterrestrials’ motivations, there are some universally constant factors that would influence the behavior of any technological civilization, no matter how alien:

  1. Space is extremely big, and the distance between even a relatively nearby alien civilization and us means that travel between the two would take at least decades. Barring a major hole in our understanding of physics faster than light travel is impossible, meaning that for even a very advanced civilization interstellar travel would be extremely costly and time consuming. Given the enormous energy requirements of interstellar flight, even for a energy-rich civilization that had intensively industrialized its solar system these costs would be very significant, and it’s been speculated that interstellar travel could turn out to be so expensive that no economy could reasonably support it. This logic would still apply to alien civilizations with vastly different available resources and economic systems than we’re used to. Even an enormous multi-world alien economy would face the problem of scarcity and costly interstellar travel would have to compete for resources with other projects. If aliens do choose to aggressively develop interstellar travel they must have an extremely powerful incentive to do so, especially give the huge opportunity costs of building an interstellar fleet.
  2. An alien civilization would have to be very close by to know about humanity at all. The Earth’s presence is obvious across great distances, and any alien civilization interested in our planet would probably be able to infer the presence of some form of life on Earth by the high concentration of free oxygen in our atmosphere. However, it would be much harder to detect our technological civilization. The main evidence of our civilization detectable across interstellar distances is our radio emissions, and it seems likely that even a vastly different alien civilization would be able to interpret radio emissions from Earth as a sign of intelligence. However, because humans have only been emitting lots of noise in the electromagnetic spectrum for about the last hundred years radio waves from Earth have only had time to travel roughly 100 light years, expanding in a sphere around the Earth at the speed of light. That implies that only an alien civilization 100 light years from Earth would be able to detect human technology. It’s unlikely that, given the vast size of the galaxy and presumed rarity of habitable planets, an advanced civilization would lie so close to ours. However, it isn’t impossible — within only a 21 light year radius of Earth lie 100 stars, some with planets. Despite this it seems unlikely that an advanced civilization would lie so close to us, because we would probably be able to detect it. It seems unlikely that an alien species experiencing technological development would not have emitted significant electromagnetic radiation during its history, emission that would be detectable by us. This, combined with an assumed 200+ year lag period between the advent of alien radio and interstellar space-flight technologies, strongly implies that there are no technological civilization within at least two hundred light years of Earth and no alien intelligence aware of our presence.
  3. There are few plausible incentives aliens would have to invade the Earth. Science fiction authors and filmmakers typically offer the Earth’s resources as motivation for aliens to mount an invasion of our planet. This doesn’t seem likely. Most of the resources Earth offers are common in the universe; water is ubiquitous, rare metals are a normal component of asteroids, and solar systems with terrestrial planets suitable for mining seem to be common. Given the very high cost of interstellar travel, it’s hard to imagine any physical resource found on the Earth that couldn’t be more cheaply exploited closer to an expanding alien civilization. However, one unique feature of Earth is its climate and atmosphere. If an alien species had a similar physiology to Earth life and planets with oxygen atmospheres and liquid water turn out to be rare in this section of the galaxy it’s possible that our biosphere could motivate an alien invasion. However, this doesn’t hold up to scrutiny. The only reason an alien civilization would send a military force, rather than a colonizing mission, to Earth is if they knew an intelligent species lived here and judged our technological abilities to be a threat. If an alien aggressor was aware that Earth harbored a technological civilization, it would be reasonable to assume the aliens also recognized human’s nuclear weapons capability, a fairly basic technology a sufficiently advanced civilization would likely  be aware of. The threat of a human nuclear defense of the planet would remove the incentive to invade Earth for its atmosphere or biosphere — resources that would be destroyed by nuclear warfare. An irradiated Earth would be of much less utility to even a radiation-tolerant species, making the notion of an invasion driven by a desire for alien living space or biological resources unlikely.

The sheer vastness of space is what ultimately makes the prospect of an alien invasion unlikely. Even if an advanced civilization was located relatively close to our solar system, the limited speeds of even extremely advanced space travel would mean that the flight time of an invasion fleet would be measured in centuries, if not millennia. For a civilization motivated to mount an extremely costly invasion whose prospective gains would be realized thousands of years into the future would require a species with the ability to think over the extremely long term without significant discounting future returns to present costs. The necessary long flight times of interstellar travel also have interesting tactical implications — a fleet that arrived at Earth would be armed with at least centuries-old technology from the aliens’ own perspective, with the possibility that human weaponry had advanced significantly during their long journey. The lack of clear gains from successfully occupying Earth, combined with the extremely high costs of developing sufficient interstellar travel capabilities, suggest that mounting an invasion of Earth would not be in the interest of most imaginable alien economies.

However, not all wars are motivated by economic concerns. The medieval Crusades are thought to have been at least partially motivated by the need for an outlet for Europe’s large number of otherwise unoccupied professional soldiers and overpopulation pressures, and it is possible to imagine similar conditions motivating an alien civilization. And of course we have really no real basis to speculate about what incentives an imaginary alien civilization might face. We can state that interstellar travel would probably be very costly for any civilization, but it’s possible that we’re wrong. Similarly, an alien species could put enormous value on Earth for reasons we can’t even comprehend, enough value to justify the extreme costs and long time horizons of an invasion. However, given the inherent expense of interstellar flight, likely large separation between intelligent civilizations, and universal prevalence of resources there seem to be few incentives for an alien invasion, even for an extraterrestrial species. We’re lucky.

Update: I’m a sucker for science fiction, so I saw the movie Friday. Unsurprisingly, the filmmakers chose not to incorporate my theories on the cost-effectiveness of alien invasion. Specifically (spoiler alert!):

  1. The aliens are willing to travel hundreds of light years, a journey that will take at the very least centuries (and that’s assuming extremely advanced propulsion technology like antimatter thrusters) to find water, the most common multi-element molecule in the universe? We know that water itself is extremely common in the universe, and we know that solid planets with surface temperatures to permit liquid water exist, because we’ve already found one. Even if the Battle: Los Angeles aliens somehow couldn’t find a water source closer to home, why would they need to invade Earth for it? The movie attempts to address this- a television reporter claims that Earth is “the only known source of liquid water in the universe.” Even if this turns out to be true, the aliens shouldn’t need to find liquid water — if you can generate enough energy for interplanetary travel, you can melt Pluto into as much liquid water as you want.
  2. The aliens’ invasion force is mostly composed of infantry. This doesn’t make much sense — if you truly want to exterminate Earth’s population, an orbital bombardment is a much cheaper way to do this. What are the aliens planning to do, individually shoot 7 billion people? This is not an efficient use of resources.
  3. Similarly, the aliens choice to use living troops rather than robots is interesting. It’s clear that the aliens don’t have some cultural taboo against constructing robots, as their air force is entirely drones. It’s also possible that, unlike humans, the alien species doesn’t have an aversion to losing soldiers.However, even if the alien society was willing to suffer preventable casualties utilizing live troops would be enormously costly for an invasion force, because living beings require biological inputs during the interstellar voyage to Earth. Even if the aliens put their troops into some kind of hibernation during the centuries to millennia-long voyage, they would still have to provide their troops with an atmosphere, requiring more massive, complex ships. This would significantly increase the cost of constructing an invasion fleet. Considering the resources necessary to transport and individual alien soldier to Earth, they aren’t expendable, and certainly have better things to do than hunt down Aaron Eckhart. Additionally, the aliens fight us on roughly equal terms — their weapons are similar to ours, and they seem to require roughly numerical parity to defeat human soldiers. That implies that the aliens have transported enough soldiers to earth to rival all of the world’s militaries — maybe ten million soldiers. This strains the limits of plausibility. Interstellar flight may be so slow and expensive that no civilizations ever have the resources to pursue it. Transporting ten million beings to invade one planet that isn’t home to any unique resource is certainly not cost effective.

Of course, analyzing the plausibility of a movie with the word “battle” in the title probably isn’t a great use of anyone’s time. Still, it is encouraging that it is difficult to imagine circumstances where even radically alien extraterrestrials would have an incentive to invade Earth. Alien invasion movies are fun, but they aren’t intellectually challenging. Something tells me this isn’t a problem.

21 Comments Post a comment
  1. Daniel #

    No real insightful commentary on why they’d go through the trouble of invading us, but I can comment a bit on their military choices:

    Orbital bombardment – As I mentioned before when talking about air power, it’s difficult to ever bomb someone into submission. The Germans flatted Stalingrad and the Russians flattened Grozny, both with little effect. England, Germany, and Japan both survived sustained aerial bombardment for months.

    The point of a war is not to exterminate the other side typically. If the aliens goal was to secure resources, it would make sense for them to take beachheads near vital resources (water-fuel in this case) and expand outward from there only as far as they need to. They could accomplish their goals and begin harvesting water much sooner than bombing endlessly from space for months, after which some time we might eventually remember we possess nuclear weapons.

    Regarding the use of drones vs living beings: In the complicated terrain of land, drones are unlikely to ever satisfactorily match automatons. Way too much crap in urban terrain to react quickly from behind a console.

    Also the odds of them actually having to fight 10million beings at the same time is unlikely, even with them fighting on so many fronts at the same time. As far as parity goes, if they’re able to advance on an entrenched position and emerge victorious with 1-1 ratio of troops, they’re doing pretty well. In most of the fights they seemed to actually be doing fairly well, though it was hard to tell with the terrible camera work.

    March 14, 2011
  2. admin #

    I was thinking that would be a cool idea for a movie- humans pushed to the centers of continents, and an uneasy stalemate with the aliens colonizing the coasts. Then we could have Battle: Kansas City.

    March 14, 2011
  3. stockmarkettoday #

    Great post Taylor,

    I am not a fan of the movie either but it certainly got me wondering. You really have a nice outlines of the movie’s inconsistencies here.haha I agree that economic reasons are not the only reason wars are started. Apart from religion most wars are caused by political or ethnic clashes.

    May 31, 2011
  4. tom #

    I agree with the initial comments why we human see alien invasion as impractical. That beings with technical finesse would find the prospect redundant; however, lets speculate on some assumptions? You generally don’t come for resources that take more effort than return. 200 years ago it was more costly to work aluminum into artifacts than the value of an equal weight of gold; now aluminum is as about as cheap to mass produce as paper. High energy physics may have a similar fate; however, harnessing unlimited energy would negate the need to ‘conquer the galaxy for energy’. I think building space cities and terra forming planets would have a more resonable return? Mining comets and asteroids would also be more advantages than ‘stormtrooping’ alien worlds? Robots running amok busting planets and laboring to produce a ‘colony’ ready solar system for its makers to become landlords isn’t far fetched( If Mars or Venus was reshaped for an alien immigration, would we care?) Or what if it was a surviving faction of a great fleet of starships fleeing from the Nova of the Homeworld? They may have had millenia to prepare and are simply resettling… maybe thousands of Stars were to handle the relocation and Sol was on their list? I also enjoyed the “Predator” franchise.. High-tech culture, but embraced “the Hunt” of their ancestors?

    June 6, 2011
  5. Tori #

    I had recently rented this movie and it got me thinking. I am very happy that I have found this post as I share Taylor’s views on the impracticality of interstellar travel and have formulated a few theories of my own. The first thing about this film that caught my attention is the fact that the ET’s seem to only be a century or so ahead of our current level of technology. This is relatively unique to the Alien Invasion genre, where usually the ET’s technical prowess so far outclasses our own that the war is hopelessly one sided, “This is no more a war than that of Men vs. Maggots.” For example; Independence Day (Horrible movie) and War of the Worlds (A film and book that bothered me greatly due to the incredible amount of inconsistency and the apparent pointlessness of their invasion, planned and prepped far before industrialized civilization on earth which paints the ET’s as nothing more than genocidal sadists.) I also enjoyed the observable parallels in development that BoLA’s ET’s share with our own present day earth. With my overactive imagination and my brains inherent need to rationalize and find plausibility in just about anything and everything I have come to some fairly radical theories that would justify an invasion from BoLA’s vision of an ET civilization and their need for our world. I will explain this in detail later. I have also tried my best to find visual representations online of the points I will try to address.

    First I would respectfully disagree with Taylor on his negative opinions on the composition of the ET’s invasion force.

    “The aliens’ invasion force is mostly composed of infantry. This doesn’t make much sense – if you truly want to exterminate Earth’s population, an orbital bombardment is a much cheaper way to do this. What are the aliens planning to do, individually shoot 7 billion people? This is not an efficient use of resources.”

    In my honest opinion the makeup of BoLA’s ET’s invasion force is rather well done. It follows my personal favorite military doctrine which if executed properly is superior to nearly all others. That of a ground force which favors infantry with close air support, though heavily dependant on maintaining air superiority. If you look at the invasion points in the film the ET’s targeted coastal areas which are densely populated and heavily urban. As history and common sense would dictate a predominantly mechanized ground force would have an extreme disadvantage here as any mechanized force requires open terrain for maneuverability to maximize effectiveness. Infantry are able to traverse a wider range of terrain and present a more difficult target, allowing them to get in close and hit with anti-vehicle small arms and better coordination of air power where needed. This would allow BoLA’s ET’s an efficient way of establishing beachheads. Also, the native population would be a secondary target as the primary points of interest would be infrastructure and supply, rendering a modern army, especially a mechanized one, nearly unable to function. This culminated with the fact that claiming that a sustained orbital bombardment is the correct course of action for the ET’s is totally contradictory to Taylor’s previous points. Given the surface area of the planet and the incredible cost and size needed for a weapons platform capable of orbital bombardment this would be an incredibly inefficient use of resources. Also, due to the dependency of water as a fuel source for BoLA’s ET’s a direct and coordinated ground assault would be the best course of action to utilize the desired resources as soon as possible. As for a nuclear response from humanity the nature of the ET’s invasion would deter this weapons use. A government would never authorize a nuclear strike on a major city or on their sovereign territory as this would risk catastrophic collateral damage and the potential damage from fallout would limit this type of weapon as a last resort only.

    Now, as for the ET’s air power in the film, I believe this was incredibly well thought out as well. As it is portrayed, that is the direction that aeronautics is currently moving toward. Air forces around the globe are rapidly adopting the idea of drone aircraft and for one major reason. Pilots are the least expendable personnel in any military. The time and cost associated with training a pilot makes loosing them incredibly detrimental to any operation and should a craft be shot down and the pilot be forced to ditch behind enemy lines, the further risk to personnel and expenditure of resources to reclaim the pilot makes the idea of manned aircraft obsolete. Therefore the ability to control and coordinate aircraft from a secure location without risking the loss of the pilot makes this an ideal alternative to manned aircraft. I also enjoy the design for the ET’s aircraft in the film, the idea of a multi role craft as in it being a gunship/ air superiority fighter/ bomber and that it is vertical lift makes it incredibly versatile…. Though I found it to be aesthetically… deficient lol… These aircraft actually reminded me of one of the LockheedMartin’s most incredible fighter, the F-35.

    So with the overall tactical viability of the invasion addressed, I now come to some of my more radical theories. Such as where the ET’s could have come from and how they could have gotten here. The base topic of this thread has already established that an interstellar invasion would probably not be attempted, due to it not being cost effective no matter how alien the civilization attempting such an undertaking is. Trying to figure this out plagued me… then of course trying to give plausibility to everything I began to think about the physiology of the BoLA ET’s. They seemed incredibly aquatic, not only due to the fact that their technology seemed to be powered by and interconnected with water, proved when Aaron Ekhart’s character downed the drone and water poured from it’s exposed components, but by what appeared to be environment suits/ armor worn by their infantry and that they were “surgically altered.” Then it dawned on me and I damn near slapped myself for not having thought of it sooner. Jupiter’s moons Callisto and Europa thought to contain liquid water oceans under the ice due to a phenomenon caused by Jupiter’s gravitational pull which can best be explained by this video. Though complex life seems unlikely let alone intelligent life in Europa’s oceans there is still so little that is known that one can slip in the ever enjoyable “what if?”

    And if there is intelligent life there we would not be able to detect it, radio transmissions would never penetrate the ice, however they would most likely be aware of us. Like our space program they would have probably made it to the very edge of Europa’s ice and scrutinized our planet as we have their’s.

    July 4, 2011
  6. Tori #

    Ah and I have forgotten to address the issue with millions of living soldiers. Though using intelligent machines would be an option it would have it’s draw backs. Some more speculation here but a species capable of mounting a full scale invasion of an alien world would most likely have mastered cloning, or one could look at aquatic life here on earth. Most aquatic species reproduce in mass quantity such as squids or nearly all species of fish aside from sharks and a few others.

    July 4, 2011
  7. Whew! all this for the Battle of Los Angeles?

    At first when I read your responses I was happy to realize that it doesn’t make sense for an alien civilization to invade Earth.

    Then I started thinking about it abd realized that we don’t need to have alien invaders to have a calamity – we do all that pretty well ourselves.

    The more I think about it, I kind of hope they will come and save us!

    But then that doesn’t make much economic sense either.

    July 14, 2011
  8. Boris #

    Well thought article… the arguments against an invasion on economic grounds seems pretty good for me, and about the use of infantry to invade the earth is nonsense neither; the orbital bombardment does´t need to be with C beam or something fancy from far far away… the alien could take an asteroid of couple million tonnes from the belt among mars and jupiter, split it into smaller parts, putting a motor and send it to as much cities, geographical accidents and infraestructure they which… the damage they could make could be easily controled; big with a couple the size of the one that destroyed the dinosaurs and invading few years after the powder settle down and the civilization was struggling to survive, or taken smaller ones over the 1000 bigger cities on earth and invading next day. That seems very logical for the cheap of the solution (1000 engines moving asteroid must be cheaper that the infantry and all the display). That way, without spoil the whole planet, they can fight a starving civilization spending the minmun.
    But after all, i enjoyed the movie… and the drones were great!

    October 23, 2011
  9. Some reviewers have characterized the show as “far fetched” and “hugely speculative”

    December 13, 2011
  10. With major advancements in space technology and finding of planets that are like the earth soon we may have planets of civilizations rather than countries.

    January 27, 2012
  11. One of things that are you missing in your economic analysis of the invasion is the intangible benefit of one civilization upon another. For leaders the invasion of say Mexico, Iraq, etcetera takes the heat off of difficult problems at home. Right now there has been drumbeats for war over the Falkland Islands; Argentina’s economy is down the tubes. Also, the British economy is in a tailspin. Therefore, a little war helps deceive and distract the populace from the fundamental economic disaster festering in plain view….

    speed of light or e=mc2

    February 4, 2012
  12. atlanta_thinker #

    Various groups posit the existence of humanoid aliens, reptilians and others that first “uplifted” us (a la David Brin)from ..something to primitive man to homo sapiens to free the earlier ‘titans’/elohim/etc etc from slave labor as they spent thousands of years digging for gold to fix the atmospheric shield of either Tiamat or Nibiru / Marduk. i.e., that we were created as a ‘slave race’ long ago during one of the 5 ages of Man chronicled by the Maya, Native American mythology and countless others.

    So getting past all that.. I also wonder about the economics of invading us now in the present era. The distance is not a factor as all the melted slabs and portals around the world illustrate that stargate technology was present back in the day, as was antigrav / gravity shielding tech (e.g, the ruins of Puma Punku, those 3 stones in the Middle East, the Trilithon, etc).

    So here we are, we know of the immense dodecahedral fake moon / satellite (Iapetus) around Saturn, the hanky panky with Europa and of course the ruins on the Moon and Mars. Old news to the informed and the elites who run our world.

    Say the aliens are here and our earth is “owned” and run by elites. What stops the aliens from invading / destroying us? That’s what I can’t figure out. Do they still need Gold? Is gold that rare and precious only to earth? (lets assume the secret stargate technology for getting it off-planet). Is it another mineral? Are we kept in existence so long as we don’t run out of material X?

    Or.. as a young slave race who has lost the memories, knowledge of technology of its masters and makers are we watched from afar and merely confined to earth and its solar system? What happens when we figure out our own stargate? Would its test send a telltale emission across dimensions? Would we then be blown out of orbit?

    So IF the aliens return to check up on the slave race, enslaving us is pointless as our machines can do more than any 100 people. So what would we have to offer in return for not being colonized or vaporized? Finally, what technologies besides robotics and nanotech could we field against alien invaders? Our governments know and are working on technology of “rebellion” let us call it. I wonder what they could be, force field technology for sure, scalar vector weapons?

    Anyway, thoughts on the economics of why NOT to destroy that 3rd planet from the sun populated by those stinky short-lived mammals who can’t figure out their own DNA.. are appreciated. No flames or unkind remarks please. I have a wife for that.

    tanquam ex ungue leonem

    March 25, 2012
  13. “we may have planets of civilizations rather than countries.”

    As long as there is colonial mentality then there is no way that this statement become a reality.

    April 15, 2012
  14. fransisco #

    there is no such thing like alien, i really dont believe in them

    April 26, 2012

Trackbacks & Pingbacks

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