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The Science of Santa Claus: Answers For Inquisitive Kids

The story of Santa Claus — a world-travelling man with flying reindeer — is pretty out there. When kids get wise, keep the magic alive with some (strange but true) science that helps to explain Santa's abilities.

The myth of Santa Claus — a world-traveling fellow with magical flying reindeer — is rather unbelievable, and at a certain age, kids are going to be naturally inquisitive. But if they don’t come out and ask directly (“Santa isn’t real, right?”), they likely want you to keep the myth alive and to play along with their inquiry. So play along, but come prepared with some real (and real weird) science to explain how Jolly Ol’ Saint Nick does it. Here’s a sample script that should cover all your bases — from how muons help him get down the chimney to his space-time-twisting capabilities.

Dad, how does Santa reach every house in the world?

He creates relativity clouds to jump from one home to the next.


Well, Albert Einstein’s theory of relativity describes how time and space weave together to create the fabric of the universe. This fabric can stretch or shrink like spandex. There’s this really smart scientist, Larry Silverberg, who says that Santa has figured out how to stretch time using relativity clouds. Inside a relativity cloud, Santa can spend what feels like months delivering all of the presents. To everyone outside the cloud, it would seem like only a few minutes had passed.


Because if you move faster than the speed of light, time slows down — Einstein proved this — so it’s like time inside the cloud is different than time outside the cloud. He needs that time to deliver all the presents.


Well, if Santa starts in the time zone where the day starts (UTC+14)  and moves west from there he will have 24 hours during which at least some place on Earth is experiencing Christmas Eve. In those 24 hours, he needs to hit 2.2 billion children. If you divide 24 hours by 2.2 billion children, Santa should have an average of 39.27 microseconds to deliver to each child. This means he would have to deliver to 25,641 children per second. Of course, there’s often more than one child per household, so he could probably shave some time off at certain stops.


What are you actually asking?

Um, well, how does he fit down the chimney?

He shrinks. Many physicists have been trying to figure out how to shrink matter. Santa clearly has found a way, probably with a device that triggers all of the electrons in his body to convert into muons, which are a lot like electrons except they are much denser and smaller. The muons remain just long enough for him to get down the chimney, then they convert back into electrons — a process called neutrino oscillation, which has so far only been observed by scientists.


What do you mean why? A chimney is usually two feet or less in diameter and Santa is way bigger, that’s why.

Well, how does he carry all the toys?

He doesn’t. He creates them.


Remember that really smart scientist Larry Silverberg? Well, he says that Santa uses technology beyond the capability of modern scientists to turn chimney soot and other nearby materials into toys. Chimney soot results from burning up, or combusting, wood in a fireplace. When the wood, which is made up mostly of cellulose, is burned at a relatively low temperature it creates water, carbon dioxide, carbon monoxide, and carbon (or soot), along with a few other materials. This is one example of a thermodynamic process that is considered irreversible by most scientists. But through Santa’s advanced research at the North Pole, he has figured out a way to reverse the process. He feeds all of these materials into the machine in his toy sack. It zaps them with electromagnetic radiation, converting them back into wood. Then it slices the wood into toys just in time for delivery.


Because no bag could possibly hold enough toys for every child. Besides, that many toys would weigh down the sleigh.

So, how does he know what I want?

This one’s easy. He uses a really really powerful computer.


Reading millions of letters each year from children around the world would be impossible to do in time — especially because so many of them turn those in at the last second or don’t send them in at all. For these kids, Santa employs sophisticated computer technology to parse information gathered from each child’s home. Remember the lyrics, “he sees you when you’re sleeping and knows when you’re awake”?


From “Santa Claus is Coming to Town.” We were just singing it.

Oh yeah.

Anyway, he sees you using modern technology, not magic. When parents make online purchases, that information is sent to the North Pole. The system keeps track of the shows and movies that children stream. Smart home devices and smartphones contain microphones that listen for keywords and clues. All of this data is sent to Santa’s computers which use an artificial intelligence algorithm to determine the perfect gift for each child.

Why doesn’t Santa visit my friends who celebrate Hannukah?

Um… go ask your mother.