After much research, we present the annual aeronautical engineers report on the theory of Santa: No known species of reindeer can fly. BUT there are 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 & 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 91.8 million homes. One presumes that there's at least one good child in each. Santa has 31 hours of Christmas to work with. This is due to the different time zones and the rotation of the earth, assuming he travels east to west (which seems logical). This works out to 822.6 visits/second. That is to say that for each Christian household with good children, Santa has .001 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 91.8 million stops are evenly distributed around the earth (which, of course, we know to be false but for the purposes of our calculations we will accept), we are now talking about .78 miles/household, a total trip of 75.5 million miles; not counting stops to do what most of us do at lease once every 31 hours, plus eating etc. So Santa's sleigh must be moving at 650 miles/second, 3,000 times the speed of sound. For purposes of comparison, the fastest man-made vehicle on earth, the Ulysses space probe, moves at a pokey 27.4 miles/second. A conventional reindeer can run, tops, 15 miles/hour. If every one of the 91.8 million homes with good children were to put out a single chocolate chip cookie and an 8 ounce glass of 2% milk, the total calories (needless to say other vitamins and minerals) would be approximately 225 calories (100 for the cookie, give or take, and 125 for the milk, give or take). Multiplying the number of calories per house by the number of homes (225 x 91.8 x 1000000), we get the total number of calories Santa consumes that night, which is 20,655,000,000 calories. To break it down further, 1 pound is equal to 3500 calories. Dividing our total number of calories by the number of calories in a pound (20655000000 / 3500) and we get the number of pounds Santa gains, 5901428.6, which is 2950.7 tons. The payload on the sleigh adds another interesting element. Assuming that each child gets nothing more than a medium-sized Lego set (2 lb.), the sleigh is carrying 321,300 tons, not counting Santa, who is invariably described as overweight. On land, conventional reindeer can pull no more than 300lb. Even granting that "flying reindeer" (see #1) can pull 10 TIMES the normal amount, we cannot do the job with 8, or even 9, reindeer. We need 214,200. This increases the payload - not counting the weight of the sleigh - to 353,430 tons. This is four times the weight of the ocean-liner Queen Elizabeth. 353,000 tons traveling at 650 miles/second creates enormous air resistance. This will heat the reindeer up in the same fashion as a spacecraft 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 .00426 of a second. Meanwhile, Santa, will be subjected to centrifugal forces 17,500.06 times greater than gravity. A 250 lb. Santa, being very conservative in terms of guessing Santa's weight, would be pinned to the back of his sleigh by 4,315,015 lb. of force. If Santa ever DID deliver presents on Christmas Eve, he's dead now.