To get scientific, we would have to use a series of numbers. Here we go!!! There are about 3 million children that are under 18 (that through religion [and other stuff] can have Christmas) in the world. They receive gifts from "Santa." Look at this though, there are houses all around the world each holding a different amount of children. If Santa has to travel around the world in 12 hours... he's moving at an average rate of 2 seconds per house. Maybe even less!
Then, look at Santa's sleigh. With Santa eating all those cookies (from all the children around the whole earth!!!) ... he would weigh about 5 tons. Not counting the toys, and the reindeer; If reindeer were real, which could be possible through animals and genetics. All that weight is going 2 seconds around the world in 12 hours!
So... as you can see. Unless there is a 5 ton, fat, white bearded man living in the North Pole (below freezing) there is no way there could ever be a Santa Claus. Of course there are possibilities, like magic, but with being in 2012 and going into 2013, there is a serious doubt about it! Just the only problem now, is... who brings the presents!?!?!?!?!?!?!?!?!?