The science of Christmas: Santa Claus, his sleigh, and presents

Santa Claus delivers presents to all the good children in the world. But how? And why? We take a look at the science of Christmas gifts

How fast does Santa travel?

If we assume that Santa has to travel 510,000,000km on Christmas Eve, and that he has 32 hours to do it (the reasoning behind these numbers is another story), then Santa will be travelling at 10,703,437.5km/hr, or about 1,800 miles per second, all night (assuming he never stops: some sort of sleigh-mounted present-launcher will be required to shoot gifts down chimneys while moving. The guidance system will have to be quite impressive, to avoid accidentally showering Afghan wedding parties with extra presents). It will probably also be advisable to have Santa catheterised to obviate the need for lavatory breaks.

How much will his sleigh weigh?

Last year, we calculated Santa’s sleigh (carrying 700,000,000 Optimus Primes and dragged by three million reindeer) to weigh 1,232,300 metric tonnes. However, this year, thanks to the success of Toy Story 3, he will have to be carrying Buzz Lightyears, which have a boxed weight of 1.2kg compared to Optimus’s comparatively puny 659g. So that’s 840,000 tonnes of toys, which will require 5,600,000 reindeer to pull. Given each reindeer weighs around 272kg (600lb), the whole procession (assuming a weightless sleigh) will have a mass of 2,363,200 tonnes when standing still. Last year, however, we failed to take into account the relativistic increase in mass caused by the speed of the sleigh. Travelling at 10,703,437.5km/hr, or 0.97 per cent of light speed, the whole thing will have an apparent weight to a stationary observer of 2,363,310.33 tonnes.

Why do we give gifts at all?

We’re all evolved, right? Selfish genes and all that. So how come we’re generous? How come we waste valuable resources on other humans when we could be keeping them all for ourselves? Yet altruism, and gift-giving, exists in thousands of animal species.

In most other species, it’s readily explicable by kin selection (being generous to close relatives who will likely carry our genes) or by reciprocity: males give gifts to females to boost their chance of mating; social creatures are generous to each other to gain favours themselves in future. But humans are often generous to total strangers, almost certainly unrelated to them and who they may never meet again. Usually it’s explained by saying that it’s an evolutionary hangover from our days of living in far smaller groups.

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