Here is the conspiracy theory.
Thanks to Stephen Hawking we now know that a black hole exists in the centre of our galaxy, the Milky Way. On December 13th 2012 the Earth will come in to perfect alignment between the sun and the centre of the galaxy, this much is true. This alignment will cause the earth to be affected by additional gravity, this is also true. So the theory goes that the additional gravity created by the alignment will knock the earth out of it's orbit, and possibly into the path of a comet BOOM!! There you have your end of days theory.
However, there is one teeny weenie point that seems to have been overlooked by the people who propound this theory, well, er, two points actually".
1: The additional gravity created by the alignment is teeny weenie. It's minuscule on the cosmic scale and would barely register.
2: This alignment that's supposed to send us spinning out of control, happens EVERY December 21st. It happened last year in 2008, it also happened a couple of months after the battle of Hastings in 1066, and again in 1067. It will happen again this year on December 21st 2009, 2010, 2011 and 2012, 13, 14, 15 and so on.
So!! - on December 21st 2012 you can sleep easy, you WILL SEE December 22nd and go on to have a nice Xmas.
I'm sorry to be a kill joy to the masses who love this theory. In fact I'm so sorry that I'm prepared to make amends. If you REALLY AND TRULY want something to worry about, keep in mind April 13th 2036 this is when Comet Apophys REALLY COULD slam in to the Earth.
We'll also have SEVEN years to contemplate our impending doom. The Comet will pass us in 2029, so close that it will dip below our orbiting communication satellites. From that passing in 2009, astrophysicist's will be able to calculate if it's going to hit us in 2036.
Take a look at this clip by Astrophysicist Neil DeGrasse Tyson - all is explained enjoy!!