Interesting topic to me. First off, I'd like to qualify my comments by saying that I don't believe anyone knows anything for sure. In my profession, I often hear some of the college kids quoting Lord Kelvin (as in Kelvin measure of temperature). His quote if often parroted, "To measure is to know". I've often accepted that statement to be true, until recently, when it was repeated by someone who didn't even know what Kelvin temperature measure was. I thought about it again, and went back to him and said "Maybe to measure is to form an opinion, but I think that humans are incapable of knowing anything for certain". So I will say this - I suppose that it may be true that we know very little, if anything, and nearly everything we call knowledge was transmitted to our brains by one or more of our senses, or by other unknown means." Since we are an animal and we possess limited intelligence, then what is transferred to our brain may not be understood correctly either, and a lot of things may remain unexplained indefinitely. Try teaching Algebra to a cricket.
Now, to qualify my opinion..
I can only comment by opinion, which is simply a thought based on my senses or other unknown source transmitting information to my brain, and myself processing this information with my given intelligence (average).
I have studied this 2012 issue. I believe that we are on the brink of a serious change in the world. I don't think the December 21'st, 2012 date is a fixed date. This number is based on the expiration date of the Mayan calendar, as I understand it. The Mayans were advanced astronomers and mathematicians and any of their records not etched in stone were supposedly destroyed by the Europeans. I would suggest reading some of the research done by Maurice Cotterrell
His writings delve deeply into the Mayan calendar and their calculations, with the "Birth of Venus" being the beginning of the current era we live in. His interpretation of the Mayan stone records describe how the Sun's reversal of its magnetic poles routinely cause the Earth to ' recycle' itself every now and then. The beginning of the current Mayan calendar notes the 'Birth of Venus', when the Sun's pole shift flipped Venus upside down, explaining why it spins in an opposite direction from most other planets. He explains in his writing that our history of civilization is not the first one, and the Mayans were aware of it, as are most world cultures. He also explains how the recycling date, or pole reversal date is December 21'st, 2012, but the date is mathematically incorrect by several years. The pole reversal and recycling of the Earth is supposed to happen in 2008, this year. Scientist have recently been noting pole shifts, and it seems like it is happening. The results of reversing the Sun's, and subsequently, the Earth's magnetic poles will have an unprecedented effect on the world. There are other indicators that this is taking place, but for now, check out Marice Cotterell's writings. He's one of the philosophical-type physicists/mathematician, like Descartes was. Again, nobody knows anything for sure, but Maurice's scenario is a frightening proposition. Let's hope it doesn't happen. At the bare minimum, it makes for some interesting conversation.