If the world really does end in 2012, we've had a hell of a ride. People have been predicting the end of human civilization for about as long as we've had human civilization. In this feature, we'll share some of the most absurd, crackpot end of the world theories that have ever been issued, from alien interventions to insane natural disasters. If any of these come true, we'll be amazed. If all of them do, we'll be dead a hundred times over.