The document discusses theories about the Mayan calendar ending in 2012, including the Long Count calendar reaching 13.0.0.0.0 on December 21, 2012 and the Galactic Alignment Theory that the solar system will intersect with the Galactic Equator on this date. It also mentions potential effects like solar flares and references sources on Mayan calendars and theories about December 21, 2012 being a doomsday date.