Watching the new Avengers trailer has set my mind to thinking about how unrealistic most alien invasion movies are: all huge explosions and mass destruction. Putting aside the sheer physics and energy expenditure of moving an alien invasion fleet across several light years, most scenarios of alien conquest just aren’t efficient. A few that I think would be more effective:
- If you’re a Type III civilization and just want to wipe out the human species: find a star above 1.38 solar masses that is a candidate for going nova and spur this process along by using a circular array of orbiting artificial bodies to either add mass to it (causing runaway nuclear fusion) or collapse the core, while ensuring that one pole of the star points at the earth. When the supernova is produced, magnetic field lines will direct the resulting gamma ray burst towards the earth, frying all life. (Betelgeuse would be an obvious candidate, except for the fact that its poles are oriented roughly parallel to the Sun’s, and the giant star is a little too far away from the Earth.)
- Seed von Neumann machines in the Oort cloud and start pushing a few gigatonne comets to intersect Earth’s orbit, causing mass extinction.
If you’re an alien species inimical to humanity and want to wipe it out, but wish to preserve Earth’s other life forms and resources, two other possible stratagems:
- Take the approach of Lord Jeffrey Amherst with the North American Indians, and give the equivalent of smallpox-infected blankets to the human species. Arrive as benevolent aliens with magical free tech (or simply send it in craft that arrive close to the Earth) that, a decade after everyone is using it, turns them all into grey goo.
- Perhaps most effectively: adopt the strategy of the jewel wasp, which stings cockroaches in very precise spots in its ganglia; after injection, the roach is effectively mind-controlled, and walks itself back to the wasp’s lair, where it becomes both host and, as they hatch, a food source for the wasp’s offspring. Properly modified, humans wouldn’t even be “aware” of their own actions after infection by an advanced virus, even if that behavior were destructive; if the parasite preserved higher cognitive functions, human hosts would most likely rationalize every action they took. To a lesser degree, this phenomenon actually occurs right now, but not from aliens… instead, the enemy is cats, or more correctly, the parasitic disease toxoplasmosis, for which felines are carriers. Humans infected with the parasite often undergo changes in behavior, including depression, anxiety, and schizophrenia. Toxoplasmosis also endangers fetal development, which is the reason pregnant women are advised to avoid being near cat litter.
Of course, few of these strategies make for exciting movie plotlines, with the exception of The Body Snatchers.