Y did Mayan's dissapear and what will happen in 2012?

Ok this is my theory the Mayans they were a awsome civilization they did many things but what happend to them and y? I think that we were visited by aliens you may call me crazy but look how did cavemen just randomly find out science and math you may believe we jsut evovled but there is no way we went from hitting eachother in the heads with rocks to computers jets rockets airplanes so i think that maybe just maybe the Mayans went away to another planet or something they were pretty advanced for their time and thier is proof of alien drawings in their hyroglyphics. Now for the calender i think its when the mayans will return, Judment day were Jesus comes down and see's what we have used and how we used the things he has given us Or simply the Mayans were tooken by aliens and never finished Or the guy writting the calender simply was like I QUIT!!! If you have any other ideas on this subject or believe what is say jsut repost under this topic thank you all.