The latest end-of-the-world prediction says we're all doomed today, 12/21/12. Some say Nostradamus predicted PSY's K-pop hit "Gangnam Style" would usher in the end of life on earth. Why do we as humans apparently need the periodic cheap thrill of thinking "It's the big one"? If we do go out in a bang, might it be predicted by Nostradamus, science or not at all? Bonus: What's your favorite doomsday theory yet?