WARNING: THE FOLLOWING IS NOT TO BE SHOWN TO LITTLE JOHNNY, WHO IS WAITING FOR PRESENTS TO BE DELIVERED BY SANTA!!
The Annual Scientific Inquiry into Santa Claus:

1. No know 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 seen.

2. 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 91.8 million homes. One presumes there’s at least one good child in each.

3. 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. That 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 onto 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 1.255 km per household, not counting stops to do what most of us must do at least once in 31 hours … plus feeding himself and the reindeer etc. This means that Santa’s sleigh is moving at 1302 km/sec or 3000 times the speed of sound. For purposes of comparison, the fastest man-made vehicle on earth, the Ulysses space probe, moves at a poky 44.09 km/sec – a conventional reindeer can run, tops, 24 km/hr.

4. The payload on the sleigh adds another interesting element. Assuming that each child gets nothing more than a medium sized Lego Set (0.9 kg), the sleigh is carrying 321,300 tons, not counting Santa that is who is invariably described as overweight. On land, conventional reindeer can pull no more than 136 kg. Even granting that ‘flying reindeer’ (see Point 1) could pull 10 times the normal amount, we cannot do the job with eight – or even nine – reindeer. We need 214,200 reindeer. This increases the payload, not even counting the weight of the sleigh, to 353,430 tons. Again – for comparison – this is four times the weight of the QE2.

5. 353,000 tons traveling at 1032 km/sec creates enormous air resistance – this will heat the reindeer up in the same fashion as spacecraft re-entering 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 thousandths of a second. Santa, meanwhile, will be subjected to centrifugal forces 17,500.06 times greater than gravity. A 113 kg Santa (which seems ludicrously slim) would be pinned to the back of his sleigh by 1,957,290.8 kgs of force. In conclusion, if Santa ever DID deliver presents on Christmas Eve, he’s dead now.