Alien Invasion

Alien invasion refers to a move by extraterrestrial civilization to conquer Earth. A staple of science fiction since HG Wells, it is also a possible doomsday scenario.

Depictions in Science Fiction

• War of the Worlds
• Independence Day
• V

Real Threat

Considering the sheer scale of our galaxy, let alone the universe, it is quite likely that, like on Earth, life started on extrasolar planets, and some of that life might evolve cognative capabilities rivaling our own. A civilization from an intelligent species older than ours could conceivably develop a method of interstellar travel (such as putting the crew of a ship into suspended animation and having it fly through at a decent fraction of the speed of light), allowing them to spread themselves across the universe. If they come this way, they could easily destroy our civilization via orbital bombardment and set up their civilization over the remains of ours or subjugate ours with the threat of orbital annihilation, gradually displacing our own. In most conceivable scenarios, humanity would be unable to resist an assault by an alien conquest fleet.