From Wikipedia

Mayan Doomsday Prophecy

The 2012 phenomenon is a range of beliefs and proposals positing that cataclysmic or transformative events will occur in the year 2012. The forecast is based primarily on what is claimed to be the end-date of the Mayan Long Count calendar, which is presented as lasting 5,125 years and as terminating on December 21 or 23, 2012. Arguments supporting this dating are drawn from a mixture of amateur archaeoastronomy, alternative interpretations of mythology, numerological constructions, and alleged prophecies from extraterrestrial beings.

A New Age interpretation of this transition posits that, during this time, the planet and its inhabitants may undergo a positive physical or spiritual transformation, and that 2012 may mark the beginning of a new era. Conversely, some believe that the 2012 date marks the beginning of an apocalypse. Both ideas have been disseminated in numerous books and TV documentaries, and have spread around the world through websites and discussion groups.

Mayanist scholars argue that the idea that the Long Count calendar "ends" in 2012 misrepresents Maya history. To the modern Maya, 2012 is largely irrelevant, and classic Maya sources on the subject are scarce and contradictory, suggesting that there was little if any universal agreement among them about what, if anything, the date might mean.

The claims put forward by those predicting the end of the world in 2012 (alignment with a black hole, collision with a rogue planet, polar shifts) have been rejected as pseudoscience by the scientific community. Many of these claims violate the laws of physics, or are contradicted by simple observations.

A film called 2012, directed by Roland Emmerich, has employed a viral marketing campaign drawing on fears of an apocalypse in that year. This campaign, which masquerades as a public awareness video from the fictitious "Institute for Human Continuity", has been roundly criticised by scientists and sceptics for contributing to popular anxiety on the topic.