There are 2 billion children in the world. But since Santa doesn't handle the Muslim, Hindu, Jewish and Buddhist children, that reduces the workload to 15 percent or 378 million. At an average rate of 3.5 children per household, that's 91.8 million homes.

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 822.6 visits per second: 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 and move on. Assuming for the purposes of calculation that each of these 91.8 million stops are evenly distributed around the earth, we are talking about 78 miles per household, a total trip of 75.5 million miles.This means that Santa's sleigh is moving at 650 miles per second, 3,000 times the speed of sound. The fastest man-made vehicle on earth, the Ulysses space probe, moves at 27.4 miles per second - a conventional reindeer can run, tops, 15 miles per hour.

Assuming that each child gets nothing more than a medium-sized Lego set (2 pounds), the sleigh is carrying 321,300 tons, not counting Santa, invariably described as overweight. On land, conventional reindeer can pull no more than 300 pounds. Even granting that "flying reindeer" could pull 10 times the normal amount, we cannot do the job with eight, or even nine: we need 214,200. This increases the payload to 353,430 tons - four times the weight of the Queen Elizabeth; 353,000 tons travelling at 650 miles per second creates enormous air resistance - this will heat the reindeer up like spacecraft re-entering the earth's atmosphere. The lead pair of reindeer will absorb 14.3 quintillion joules of energy. Per second. Each. They will burst into flame almost instantaneously, and create deafening sonic booms in their wake. The entire team will be vaporised within 4.26 thousanths of a second. Santa will be subjected to centrifugal forces 17,500.06 times greater than gravity. A 250-pound Santa (ludicrously slim) would be pinned to the back of his sleigh by 4,315,015 pounds of force.

Santa, the final frontier: posted at http://www.tandrin.de/sch_hohoho.html; calculations by Tarig Monawar of Columbia University's Civil Engineering Dept, courtesy sudanese@msu.edu