It’s the time of year when our minds are supposed to turn to presents, mince pies, turkey dinner, and eggnog — and occasionally goodwill to all mankind. But for some of us, Christmas is a time of torment and sleepless nights. The thoughts that trouble our minds — pushing out images of dancing sugar plum-fairies — are of the science that allows a single man to deliver presents to every child in the World.

Fortunately, ZME Science is here to help alleviate some of these troubling thoughts, answer some lingering questions, and possibly dismiss silly doubts that Santa Claus may not be… well… real.

Of course, Father Christmas keeps his scientific secrets to himself. Despite the fact these scientific tricks and cheats are clearly closely guarded by Kringle, we at ZME aren’t the first to accept this Christmas quest. Every year physicists gather to tackle the science of Santa, explaining how Papa Noel can perform incredible feats without recourse to magic.

This is the science of Santa.The physics of Father Christmas. The chemistry of Kris Kringle. The quantum of Claus?

OK. That last one is a stretch.

To assess why Santa needs cutting-edge science to perform his annual challenge, the first question we must ask is how just how big is the scale of the operation Santa must undertake?

Just How Many Houses Does Santa Have to Visit? 

To assess this, first, we have to acknowledge that Santa doesn’t visit every kid on Christmas Eve — just those in households and homes that celebrate the holiday. Whilst there is no hard and fast way to do this, we could get a rough estimate by calculating the proportion of the world that identifies as Christian.

About 33% of the world’s population identify as Christians, so let’s assume that applies to Earth’s 2.2 billion children too. That means about 726 million children to gift.

Don’t worry Santa we’re going to trim that down a little bit more. There are approximately 4 children per household globally. So that’s about 182 million separate homes that Santa needs to visit. 

Fortunately, Father Christmas has a little over 24 hours to do this. When taking timezones into account, and factoring in the rotation of the planet, Santa can extend his time limit to 31 hours in picking the right route to take on his gargantuan present delivering operation. 

Let’s go to the blackboard and calculate how many stops Santa must make per second.

That’s quite the task. Santa has almost as little as 1/2000 of a second to park his sleigh, get out, slip down the chimney (or find another access point), leave presents, eat the cookie or mince pie left for him washing it down with milk (or something stronger if he’s lucky), and then get back to the sleigh and move on!

That’s pretty impressive. No wonder he needs the calories from at least 182 million sweet treats! All this leads to another question; just how fast must Santa be traveling to achieve this remarkable task?

At the Speed of Santa

To reach the near 200 million households on Santa’s delivery route in just 31 hours, the jolly fat man’s sleigh must be clocking in at a fair speed. To figure out just what his sleigh’s velocity must be, let’s assume that all the homes Santa visits are equally distributed across the globe.

That means that there is an average of 1.25 km between each house, meaning Santa’s journey would cover a distance of about 228 million kilometers.

Whilst that is an incredible speed which is barely comprehensible, it doesn’t violate the idea that nothing can travel faster than the speed of light, as it is still way below the universal speed limit of around 1.08 x 10⁹ kilometers per hour.

So it’s possible, albeit still way faster than the fastest a vehicle has ever been recorded on the surface of the planet — 4x 10⁴ km/h. This record was, of course, set by you on Christmas Eve last year when you realized at 3:55 pm that you had forgotten to get stuffing…. Or possibly by an X-15 jet belonging to the US Air Force. The speed Santa must travel at also tops the fastest speed we’ve recorded a space vehicle traveling at by a considerable margin.

Traveling at such speeds within an atmosphere brings with it all sorts of associated problems for Santa, of course. The most pressing of these is likely the incredible heat that it would generate.

So how does Santa deliver presents that aren’t charred and burnt whilst also ensuring the incredible speed speeds he flies at don’t roast his reindeer?

Preventing a Christmas Conflagration

Roasting chestnuts may be a Christmas tradition, but let’s face it, none of us want to be roasting anything in the mangled wreck of Santa’s flaming sleigh. Fortunately, astrophysicist Knut Jørgen Røed Ødegaard, professor of physics Gaute Einevoll, professor of mathematics Nils Lid Hjort and self-described Elf expert Ane Ohrvik, have an idea of how Santa may prevent his sleigh from bursting into flames when traveling at incredible speeds. 

The researchers suggest that to mitigate the generation of excessive heat, Father Christmas could use an ion-shield consisting of charged particles and held together by a magnetic field.

Non-Kringle associated scientists at Rutherford Appleton Laboratory were testing prototype ‘mini-magnetospheres’ that could offer protection against high energy solar particles, as early as 2008. It’s possible these researchers, who proposed their shield could help protect the delicate electronics within spacecraft from solar radiation, could have hit upon a system similar to the one employed by Santa. 

Who knows? Maybe one of the team had been an exceptionally good boy or girl the year before and received it as a gift from the man himself?

Of course, Santa probably also employs the most up to date heat-resistant materials. Possibly, some of these are similar to the substances that NASA uses to protect space-vehicles from the heat associated with entering a planetary atmosphere.

The most heat resistant materials that scientists have currently developed are the ceramic compounds Tantalum carbide (TaC) and hafnium carbide (HfC). In 2016 a team of researchers from Imperial College London used laser-heating techniques to discover that the melting point of HfC is the highest ever recorded, with the compound able to withstand temperatures as great as 4,000 ⁰C. 

These refractory ceramics have already been touted as ideal coatings for heat shielding on the next generation of hypersonic space vehicles. But, who knows? Maybe Santa was on to TaC and HfC way before us?

Of course, air resistance isn’t the only hindrance to Santa getting around. With toys for around 33% of the World’s children aboard the sleigh that they are hauling, Santa’s reindeer need all the scientific tricks they can get their hooves on. 

Maybe, the scientific secret Santa employs to mitigate the weight of this load and find the space to fit it all in just a few sacks could lie in one of physics’ most cutting-edge theories.

Santa and the String Theory Sack 

String theory says that all of the particles that make up the matter and energy content of our universe are the manifestations of one-dimensional vibrating strings that fill spacetime. For string theory to work, the fabric of the Universe would have to be made up of more dimensions than the four we are aware of — three of space and one of time. 

In fact, it would require at least 11 dimensions. Maybe 26. Depends on who you ask.

These ‘hidden dimensions’ exist curled up within the more familiar dimensions that we as a species are aware of. Maybe, they also exist curled up in the sack of one Santa Claus too, giving him near-infinite space to play with.

A string- theory-powered sack could also help reduce the weight load of all those toys. One of the reasons string theory was initially posited is because there is currently no quantum theory of gravity. Thus, whilst quantum physics provides a satisfactory explanation of the other three fundamental forces — electromagnetism, the strong nuclear force, and the weak nuclear force — it can’t as of yet unite with general relativity and explain gravity. 

One of the lingering questions about gravity is why is it so weak over large distances. This has led some physicists to suggest that some of gravity’s associated effects ‘leak’ into the extra dimensions of string theory. That means that a sack that exploits these extra dimensions could possibly hold a tremendous mass whilst still just weighing a marginal amount. 

Who knows, maybe Santa has his whole toy factory folded up in there?

Quanta Claus?

Of course, all these explanations still leave a lot of unanswered questions about Santa and the science he employs each year.

For example; how does he make his reindeer defy gravity? How does he exist in a superposition in every shopping mall in the US at one time without his wavefunction collapsing? And most importantly, why did he bring me a Go-Bot instead of the Transformer I asked for on that best-forgotten Christmas day in 1986? 

Seriously Santa. You dropped the ball here. Big time.

As for how Santa determines naughty and niceness  and how he knows if you are sleeping— well that all hinges on quantum entanglement, but that’s way too complicated to explain in time for his visit this evening.