KaylasMum, where are you getting all this stuff?
I read broadsheet newspapers with highly educated science editors, and none of them are talking about this. They talk about climate change, but not this. Why would that be?
The governments of the developed world have highly paid top scientists advising on all sorts of things - all over the world, huge building projects are going on, hospitals are pouring resources into curing people of diseases, why would they be doing all that if the world was going to end?
Your bank - if the world was going to end, they would lend you millions and not worry about getting it back if ther was no future. test that in your bank tomorrow 
The top international physicists - some of the brainiest folk in the world - at CERN in Switzerland have come close to discovering what could be the beginning of the world, and seem to have no discoveries at all concerning the end of the world on Dec 21st!
Obviously the real issue is your anxiety, and that you have focussed it on this. But you must be seeking out this stuff, because as I say i have come across none of it. Stop looking for myths perpetrated by nutters who love messing with people's heads.
Lots of things to worry about that you can actually solve - in my case it would be a pile of laundry, what on earth is happening with the electric on my car, and after-school childcare next Thursday. You too must have a list like that - worry about it, do something about it, feel better!