Thought of the Week - Christmas edition: Santa Claus is everywhere

As has become tradition, I will finish the year with a little bit of entertainment and a not-so-serious post about Christmas. I will take my usual end-of-year break and be back with new posts on Tuesday, 2 January 2023.

Joachim Thought Of The Week

Before then, I must address the many grinches of Christmas who constantly point out that Santa Claus isn’t real and that he cannot be the one who brings children their presents because he would have to visit some 1 billion houses in one night. This assumes that there are about 2 billion Christians on Earth. By now, Christians are pretty much everywhere around the globe, so they cover more or less all of the 150 million square kilometres of land. That means there is a Christian for every 0.075 km2 of land or a Christian for every 273m. If Santa Claus has to visit these people in one night and he is smart about time zones etc. that gives him about 12 hours. This means Santa has to travel at 45.5 million km/h (28.3 million mph) and can spend no more than 0.02 milliseconds with each person. The good news is that on average there are some three persons in each household, so he can take a 0.04-millisecond break between each trip to have a cookie and some milk before moving on.

Clearly, these numbers are ridiculous, which is why these people say that Santa Claus cannot exist. But nothing is as dangerous as a little bit of knowledge. So, I had to dust off my physics and maths knowledge to explain to these people that they are wrong. To all my physicist and mathematician readers, please apologies, if I make any mistakes. It has been 24 years since I left the world of physics behind, so I am a bit rusty.

But the thing I want to point out to these grinches who claim that Santa cannot exist is that they clearly aren’t aware of quantum mechanics. Their argument is based on classical Newtonian mechanics which is only a rough approximation to the laws of nature governing motion. True physics is described by quantum mechanics and there we have to deal with wave functions that describe quantum superposition.

In short, quantum mechanics shows that an object has a probability of being in one place and a probability of being in another place. As long as nobody is observing the object (in our case Santa Clause), the object is in all states (in our case all Christian houses) simultaneously. You may have heard of the famous Schrodinger’s Cat paradox where a cat is simultaneously dead and alive until somebody opens the box to check on the cat.

And that is the case for Santa Claus. He is using quantum superposition to visit all houses at the same time, which gives him plenty of time to visit all the children in the world, bring them presents, have cookies and milk and then go home again.

But how does he get into the house, you ask? After all, most of us don’t live in Charles Dickens’ England anymore, so we don’t have fireplaces and chimneys and Santa can’t get into our homes. Well, it really is quite simple.

Capture (4)

This is the time-independent Schrodinger equation for Santa Claus on the left.

Where Ψ is the wave function of Santa Claus, x is the distance he has to travel to get through the wall into a house, m is Santa’s mass (which we will keep to ourselves to not embarrass him), h is the reduced Planck’s constant, V is Santa’s potential energy as he descends from the sky into the house and E is his kinetic energy in the direction of the wall.

Capture 2 (1)

At this point, my professors at university liked to say: “A few moments’ thought will show that…” which was code for “you will take days to figure this out”. The probability of Santa Claus quantum tunnelling through the wall of each house is given by this formula.


It’s easy, really, once you think about it.

Anyway, the main lesson we can take away from this is that Santa Claus can easily visit all the children at Christmas and give them presents without even breaking a sweat. He simply is everywhere all the time.

However, as we know from the Schrodinger Cat paradox, the wave function breaks down, once we observe the state of the cat. In other words, if anyone would ever see Santa Claus, the entire wave function would collapse and he would be only at that one place where he was seen. The price to pay would be that Santa can no longer be at any other place and while you might see Santa, all the other children around the globe would not get a visit from Santa, would not get a present and would be extremely sad and probably lose faith in Santa’s existence and Christmas altogether.

So please stop looking for Santa Claus. You are playing a very risky game that could lead to billions of children losing faith in Christmas.

Instead, simply enjoy the fact that Santa Claus is coming to visit all of you to bring presents. Leave out some cookies or mince pies or whatever food you want together with some milk.

Merry Christmas and happy holidays everyone, whether you celebrate Christmas or not, whether you are religious or not. Enjoy the last days of 2022 and I wish you all a happy, healthy and successful 2023.

PS: If you want to understand how all that quantum mechanics stuff works and don’t want to study physics, watch this 5-minute video:

Thought of the Day features investment-related and economics-related musings that don’t necessarily have anything to do with current markets. They are designed to take a step back and think about the world a little bit differently. Feel free to share these thoughts with your colleagues whenever you find them interesting. If you have colleagues who would like to receive this publication please ask them to send an email to This publication is free for everyone.

New York


Ropemaker Place, Level 12 25 Ropemaker Street London EC2Y 9LY

New York

20th Floor 575 Fifth Avenue New York NY 10017