The Science of Santa: An Engineer’s View of Christmas

Ellena Tangi

December 17, 2019

With Christmas only one week away, we begin to wonder just how Santa preps for his one-night of madness. Of course, the Engineer in all of us wonders just how possible it is to carry a ludicrous amount of presents across the world, on a sleigh with flying reindeers. Below is an Engineer’s answer to all of our burning questions. This article was originally featured on IEEE.

Are Rudolph and his friends real?

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.

Santa’s other friends, the Elves would use approx 1.6 million miles of wrapping paper – which could wrap around the world 60 times!

How many children are on his list and how much time does he have per stop?

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 (hopes) there’s 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 822.6 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 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 1.26 km per household, a total trip of 121.5 million km, not counting stops to do what most of us must do at least once every 31 hours, plus feeding and etc.

This means that Santa’s sleigh is moving at 1,000 km per 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 poky 44 km per second – a conventional reindeer can run, tops, 24 km per hour.

How much would his sleigh weigh?

The payload on the sleigh adds another interesting element. Assuming that each child gets nothing more than this year’s most popular toy, the Lego Boost set (1kg approx.), the sleigh is carrying 321,300 tonnes, not counting Santa, who is invariably described as overweight. On land, conventional reindeer can pull no more than 135 kg. Even granting that “flying reindeer” (see point #1) could pull TEN TIMES the normal anoint, we cannot do the job with eight, or even nine.

We need 214,200 reindeer. This increases the payload – not even counting the weight of the sleigh – to 353,430 tonnes. Again, for comparison – this is four times the weight of the MS Queen Elizabeth.

353,000 tons travelling at 1000 km per second 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 110 kg Santa (which seems ludicrously slim) would be pinned to the back of his sleigh by 1.9 million kg of force…not great news!

Although the science and maths prove it’s impossible, we all know that Christmas is a magical time of the year and so could defy the laws of physics, meaning Santa can keep his promises.

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