Certain theorists anticipate the end of life, as we know it on December 21, 2012. These theorists believe that on December 21, 2012, the Earth will experience unprecedented, cataclysmic disasters ranging from massive earthquakes and tsunamis to nuclear reactor meltdowns.

With the many theories and/or interpretations, the only thing that is certain about the end of the world is that no one can know for sure what will happen. People will continue to speculate endlessly about when it will be over until the day of when/if it arrives.

From Wikipedia:

The 2012 doomsday prediction is a present-day cultural meme proposing 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 Mesoamerican Long Count calendar, which is presented as lasting 5,125 years and as terminating on December 21 or 23, 2012, along with interpretations of assorted legends, scriptures, numerological constructions and prophecies.

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 newer sociopolitical age for the global community.[1] Conversely, some believers in 2012 millenarianism believe that it marks the beginning of an apocalypse. The 2012 doomsday prediction idea has been disseminated in numerous books and TV documentaries, and has spread around the world as an Internet meme through websites and discussion groups.