- No known species of reindeer can fly. But there are at least 300 000 species of living organisms yet to be classified, and while most of these are insects and germs, this does not completely rule out flying reindeer which only Santa has ever seen.
- There are 2 billion children (persons under 18) in the world. But since Santa doesn't (appear) to handle the Muslim, Hindu, Jewish and Buddhist children, that reduces the workload to 15% of the total - 378 million according to Population Reference Bureau. At an average (census) rate of 3.5 children per household, that's 108 million homes. One presumes there is at least one good child in each.
- Santa has 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 good children, Santa has 1/1000th of a second to park, hop out of the sleigh, jump down the chimney, fill the stockings, distribute the remaining presents under the tree, eat whatever snacks have been left, get back up the chimney, get back into the sleigh and move on to the next house. Assuming that each of these 108 million stops are evenly distributed around the earth (which, of course we know to be false but for the purpose of our calculation we will accept), we are now talking about 1.2 miles per household, a total trip of 129 million miles, not counting stops to do what most of us must do at least once every 31 hours, plus feeding and so on. This means that Santa's sleigh is moving at about 1200 miles per second, 6 000 times the speed of sound. For purposes of comparison, the fastest man-made vehicle on earth, the Ulysses space probe, moves at a pokey of 27.4 miles per second - a conventional reindeer can run, tops, 15 miles per hour.
- The payload on the sleigh adds another interesting element. Assuming that each child gets nothing more than a medium-sized Lego set (2 pounds), the sleigh is carrying 321 300 tons (assuming not all children are good), not counting Santa, who is invariably described as overweight. On land, conventional reindeer can pull no more than 300 pounds. Even granting that "flying reindeer" could pull ten times the normal amount, we cannot do the job with eight, or even nine. We need 107 100 reindeer. This increases the payload - not even counting the weight of the sleigh - to 329 868 tons. Again, for comparison - this is four times the weight of the Queen Elizabeth.
- 329 868 tons traveling at 1200 miles per second create enormous air resistance - this will heat the reindeer up in the same fashion as space crafts reentering the earth's atmosphere. The lead pair of reindeer will absorb 14.3 quintillion joules of energy. Per second. Each. In short, they will burst into flame almost instantaneously, exposing the reindeer behind them, and create deafening sonic booms in their wake. The entire reindeer team will be vaporized within 4.26 thousandth of a second. Santa, meanwhile, will be subjected to centrifugal forces 17 500 times greater than gravity. A 250 pound Santa (which seems ludicrously slim) would be pinned to the back of his sleigh by 4 315 015 pounds of force.
In conclusion - If Santa ever did deliver presents on Christmas Eve, he's dead now!
