* There are approximately two billion children (persons under 18) in the world. However, since Santa does not visit children of Muslim, Hindu, Jewish or Buddhist religions, this reduces the workload for Christmas night to 15% of the total, or 378 million (according to the Population Reference Bureau). At an average (census) rate of 3.5 children per household, that comes to 108 million homes, presuming that there is at least one good child in each.
* Santa has about 31 hours of Christmas to work with, thanks to the different time zones and the rotation of the earth, assuming he travels east to west (which seems logical). This works out to 967.7 visits per second. This is to say that, for each Christian household with a good child, Santa has around 1/1000th of a second to park the sleigh, hop out, jump down the chimney, fill the stockings, distribute the remaining presents under the tree, eat whatever snacks have been left for him, get back up the chimney, hope back into the sleigh, and get to the next house.
* Assuming that each of these 108 million stops is evenly distributed around the earth (which, of course, we know to be false, but will accept for the purposes of our calculations), we are now talking about 0.78 miles per household; a total trip of 75.5 million miles, not counting bathroom stops or breaks. This means Santa's sleigh is moving at 650 miles per second - 3,000 times the speed of sound.
* For purposes of comparison, the fastest man-made vehicle, the Ulysses space probe, moves at a poky 27.4 miles per second, and a conventional reindeer can run (at best) 15 miles per hour.
* The payload of the sleigh adds another interesting element. Assuming that each child gets nothing more that a medium sized Lego set (two pounds), the sleigh is carrying over 500 thousand tons, not counting Santa himself. On land, a conventional reindeer can pull no more than 300 pounds. Even granting that the "flying" reindeer could pull ten times the normal amount, the job can't be done with eight or even nine of them - Santa would need 360,000 of them. This increases the payload -- not counting the weight of Santa, which is reported to be fairly impressive -- to 600,000 tons.
* 600,000 tons traveling at 650 miles per second creates enormous air resistance -- this would heat up the reindeer in the same fashion as a spacecraft re-entering the earth's atmosphere. The lead pair of reindeer would absorb 14.3 quintillion joules of energy per second each. In short, they would burst into flames almost instantaneously, exposing the reindeer behind them and creating deafening sonic booms in their wake. The entire reindeer team would be vaporized within 4.26 thousandths of a second, or right away, and just before the sleigh, presents, and Santa followed.
* Therefore, if Santa did exist, he's dead now.
Of course, it's scientifical magic. It's as plain as the nose on Rudolphs face. The nose on Rudolphs face is a heat absorber. Or a heat dissypater. Or maybe it's a warp drive, justa poppin' here and there in nothing flat.
You can trust me, I'm a fizzysist. I know these thangs.
I guess that would be one explanation for the redness of his nose. Most stories attribute it to his heavy drinking.
I don't know if he got off the ground this year. News reports had him being arrested on Friday in Austin, Texas for writing on sidewalks with sidewalk chalk, and in my state of Wisconsin he was arrested yesterday for running into a police cruiser, in both cases in full Santa Dress.