A lot of people are lead to believe there is just one theory that leads to December 21, 2012 being predicted as the end of the world. It is common belief that 2012 theory is based on the end date of the Mayan calendar. This is where the date December 21 originates from but the longer that the 2012 phenomena is studied, the more knowledge comes to light. At present, there are three main theories involved.






http://www.2012officialcountdown.com/2012/theory.html