Rocking dreams are your minds way of making sense of your fears and thoughts. You are dreaming about it because you are worried about it.
It's not real.
My Mum is a complete nut for reading all these books and things and even she doesn't truly believe that the world will end bang on 21/12/12.
Nostradamus apparently predicted that the world would end as we know it, in 2012. Due to something named Damas, which as my Mum gleefully points out every time anyone so much as whispers about the apocalypse is an anagram of Sadam.
His predictions were all in riddles, so can be interpreted in anyway the reader wants to interpret them, thus they can be made to fit.
I like reading his "The world will end as we know it and it is Damas' fault" prediction as "Sadam started a big war and lost. Other countries have/are following and over throwing their dictators. The world will change as we know it because there will be world peace"
Bear in mind that he also predicted that "The dead will walk the Earth in the 2012 games", now I don't know about you, but I didn't spot any Zombies competing in the Olympics 
His predictions also carry on throughout the 3000's, so even he didn't believe the world would end in 2012.
To be perfectly honest I try not to listen when she starts babbling about Nostradamus, but I do know that she is not stock piling tinned goods and has made plans for Boxing day, so all is well. My sister claims to be psychic and has her own views on what will happen when the world "changes as we know it" and she doesn't think we all die either, she is the one who believes we all go back to working the land and the change will be gradual rather than an over night apocalypse.