Few if any end-of-the-world scenarios can claim a longer history; none has more diverse roots. Depending on where you look, you may find prophecies about 2012 linked to everyone from the ancient Maya, Egyptians, and Hopi to the mysterious prognosticators Nostradamus and Edward Cayce, with helpings of the I Ching, reports from cutting-edge geophysicists and geologists, and various New Age self-realization texts thrown in for good measure.