Sooner or later we would meet an alien civilization. The question would be: What if that meeting was an invasion. It is not impossible, also not very likely. So how many ways could this happen?
Bad Reasons to Invade
So let us take a look at this from the worst to the least bad first.
They Want Our Women
So unless you are looking at old pulp sci-fi this is not going to be a concern. Unless for some reason our broadcast signals have created a new interstellar kink.
They Want Our Resources
Even for us most of the resources we want for expansion in space we are going to get from space. It is far better to get get it there than have to drag it up from a planet’s gravity well. Also unless they have figured out faster than light (FTL) travel trying to move those resources from our system is going to be cost prohibitive. Even with FTL the amount of energy needed wouldn’t warrant it. Even if we allow for the sake of argument that possibility there are always going to be closer systems to harvest unless our invaders are from Alpha Centauri. At this point our technology probably would have detected that.
We or Some Life on Earth is a Delicacy
The classic short story To Serve Man aside. It is highly unlikely that life on a different planet would be tasty or even biocompatible. If by some strange reason we were some delicacy, the technology of an advanced civilization makes cloning or some type of GMO human delicacy possible. At this point taking biopsies and sequencing the genes will give them all they need to grow what they want no major conflict needed.
They Want Our Land
Here at K2 Musings Central we feel that planets are a very bad colonization choice. Again the technology to build space habitats, such as an O’Neil Cylinder, gives you access to more land than a hundred planets in a system. Also it becomes easier to move resources back and forth rather than to move them up an down from a gravity well. Although advanced civilizations could build space elevators and orbital rings, but again you don’t need to.
We Are Located in a Good Strategic Location
The rules of real estate: location, location, location. As we have learned from all science fiction, Earth is always important, especially the United States or Great Britain. At this point it is hard to believe there would be a reason for that. Again for the sake of argument even if are space based assets are more likely better than a planet.
Good Reasons to Invade
And by invade here it is more likely to mean good reasons to destroy Earth. Since both the planet and us are not terribly useful to an alien species.
We Are Against Their Religion
Earlier we spoke about a Kardashev II civilization as pretty much a place we religion goes to die. However, it is not completely impossible that some religion formed that only their own people and system are special and all other species are infidels and must be destroyed.
They Have Created Artificial Intelligence That Wants to Wipe Out All Life
This is part of the plot of Dennis E. Taylor’s book The Singularity Trap. The galaxy is pretty much at war between artificials and uploaded biologicals.
This is the concern that we invent Artificial Intelligence and that is the last invention we create. The A.I. decides all life is a threat to its existence wipes us out then stands ready to wipe out any other other life it discovers.
A.I., keep it simple keep it dumb or end up under SkyNet’s thumb.
Isaac Arthur
We Represent and Existential Threat
This is perhaps the best argument for alien invasion. A K2 civilization has existed as a society for thousands of years, and it has time horizons running in centuries or millennia. A civilization discovering us would know a couple things. We are a technological civilization and we came to be where we are through evolution. We fought our way to the top of the food chain. The alien civilization most likely also pushed its way to the top of the food chain in a same way.
That means they can view us as a threat in terms of competition for resources. It may be a couple thousand years before we could pose a threat, but it is easy to eliminate that threat now before we become a space faring or multi planet civilization.
So What Does an Interstellar War Look Like
It pretty much looks like the entire NATO Alliance versus a second grader with a pointed stick. And the pointed stick might be giving us too much credit.
The simplest way to wipe us out is a Relativistic Kill Missile. This is basically just taking a large mass accelerated to some fraction of light speed. We would have almost no defense against this. It would have been accelerated up to its speed a good distance from Earth. So you have a dense, small, and fast object that is very difficult to detect and thanks to its speed very little warning.
So the war looks like a sudden burst of mushroom clouds around the planet suddenly out of nowhere. So a realistic alien invasion film look much more like Bambi Meets Godzilla.
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