The beautiful complexity of a Snowflake


27 januari 2020
Auteur(s): Philip Lepoutre
There is no such thing as a unique snowflake… Or is there? In this article, the common misconception about the uniqueness of a snowflake will be debunked, along with other interesting topics.

by Philip Lepoutre

Science Editor

The universe is big, really big. So big that scientists approximate the number of atoms in the observable universe to be between 1078 to 1082 atoms. In layman’s terms, that works out to between ten quadrillion vigintillion and one-hundred thousand quadrillion vigintillion atoms. As the universe is so big and full of atoms, it must be that two snowflakes are alike, right?

The idea that no two snowflakes are alike most likely started in 1885 in the United States, when a 20-year-old named Wilson Bentley was sitting outside his farm-house, holding a black sheet of black fabric, waiting for a snowflake to fall in exactly the right place. When it did, he held his breath and took a picture with his big old camera. Wiltson Bentley had taken the first photo ever of a snowflake:

Wiltson seriously loved snowflakes. In fact, he loved them so much that he never got married, never moved out of his mom’s house and essentially spent 50 years taking pictures of snowflakes. He called them “masterpieces of design”, and even though there is no design at all, the pure randomness of nature makes them stunning. 

The life of a snowflake starts as a simple speck of dust or pollen floating in the air, waiting to catch water molecules out of the air, and then forms the simplest shapes a snowflake can have: Diamond Hexagons.

Its life continues with it flying through the air and bumping into other water molecules. The well-known branches of a snowflake arise at each of the corners of the hexagon, because the probability that a water molecule touches a corner is higher than touching one of the flat sides. There is a simple reason for this: the corners just stick farther out. 

As the initial water molecules form branches, more water molecules stick to the branches themselves, forming what we call arms, which form all the beautiful patterns and intricacies we see in snowflakes. Depending on the temperature and humidity, and on a lot of factors scientists don’t even understand, those simple hexagons can give shape to seemingly infinite shapes! Each snowflake will travel through different air currents and bump into different water molecules.

BUT, in 1988, a researcher under the name of Nancy Knight claimed to have found two identical snowflakes, and they do look much alike. It is even possible that two snowflakes look exactly the same in every measurement of size and mass, but they will never be identical, and physics tells us why.

We know that water molecules are made up of two hydrogen atoms and an oxygen atom, but not every hydrogen atom is created equal. If we go back to the Big Bang,13.8 billion years ago, we can notice that out of every million hydrogen atoms created, a couple hundred of them, instead of consisting of only an electron and proton, also contain a neutron. This is the isotope of hydrogen, called deuterium. In Earth’s water, and even in you, about 1 in 3000 molecules will contain deuterium instead of hydrogen. So out of the millions of molecules that make up a snowflake, a lot of them will have deuterium too. 

Even identical looking snowflakes are not the same. In the illustration below, it is shown how no two snowflakes are identical, since the chances that each deuterium and hydrogen atoms have exactly the same positions are very, very small.

“Snowflakes are symmetrical, but they’re not perfect. They’re ordered, but they’re created in disorder, every random branch re-tells their history, that singular journey that they took to get here, and most of all they’re fleeting and temporary. Even if sometimes they don’t look so unique on the outside, if we look within, we can see that they are truly unique after all.”

Dr Joe Hanson - science writer, biologist, creator and host of It’s Okay To Be Smart

Ever since that first photo of a snowflake by Wiltson people haven't stopped taking photos of these amazing structures. Their wonderful complexity can be clearly seen in these photos taken by Alexey Kljatov: