Is Each Snowflake Really Unique?

The holidays are upon us, and they bring up big scientific questions. For example, what is the physical nature of the Holy Trinity? How did Moses split the Red Sea? What is Kwanzaa? These questions and more are hard ones for scientists. Luckily, I’m going to dedicate the next 10 000 words to definitively proving which is the one true religion, and disproving all false ones.

Are you going to hell? Find out after the jump!

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I’ve been informed by my editor that I shouldn’t devote my science blog to proving and disproving various religions. Apparently it could offend a lot of people, and I’m told that we don’t want to alienate potential readers. Fine. Let’s please everyone and not look at any hard-hitting, important issues.

Apparently the spirit of the holidays is censorship

Since I’m not allowed to write about anything that could be at all controversial, let’s go with another mystery of the season: snowflakes. Has anyone ever told you that you’re a unique little snowflake? Rest assured, you are not, but the concept of a snowflake being unique has been common knowledge for a long time. Are they actually unique, though? Is no snowflake in the world exactly like another?

These ones are certainly different. That’s six down

To answer that question, we must first define a snowflake, which is not a 2010’s-era undergraduate, rather “a flake of snow, especially a feathery ice crystal, typically displaying delicate sixfold symmetry”. Of course, snowflakes are more than that. They’re made of water, and water is made of two hydrogen atoms and an oxygen atom.

Thus concludes everything I learned in high-school chemistry

A snowflake has approximately 10¹⁸ water molecules, plus or minus several billion, and about one in every 5000 water molecules differ from the typical H₂0 structure, with a deuterium (a hydrogen isotope) atom replacing one of the hydrogens. Water molecules with deuterium in place of a hydrogen is called “heavy water”, by the way.

Fat-shaming is a serious problem in the water molecule community

Anyways, as I’m sure you’ve worked out in your head, 10¹⁸ water molecules with every 5000 or so being different means that the odds of two snowflakes having the same molecular composition is relatively low. In fact, Kenneth G. Libbrecht, crystallographer at Caltech declares: “Even with 10²⁴ crystals per year, the odds of [two molecularly-identical snowflakes] happening within the lifetime of the Universe is indistinguishable from zero.”

“Libbrecht out”

So, on a molecular level, the odds of two identical snowflakes is astronomical. But what about two visually identical snowflakes? Can two snowflakes look the exact same? That’s what we really care about. After all, we know the identical twins may have slightly different molecular structures, but in reality we know they are both the exact same person.

One is simply a back-up copy of the other

Can two snowflakes look the same, then?
Well, the water molecules in a snowflake actually make up an ice crystal, resulting in a snowflake. Now, one simple, hexagonal ice crystal can look the same as others, but as a natural ice crystal grows, it develops branches, like a fern.

You can thank Kenny G. for that knowledge bomb, as well. Man knows his snowflakes

As snowflakes develop branches in the clouds, they’re blown around into different temperatures and collect dust and other detritus, all of which affect their shape at random. All told, and there is about a 10¹⁵⁸ chance that two snowflakes will develop in the exact same way, 10⁷⁰ times more than the total number of atoms in the universe.

I’ll let Kenneth Libbrecht tell it, because he does it so much better than I can:
“And thus it’s unlikely that any two complex snow crystals, out of all those made over the entire history of the planet, have ever looked completely alike.”

“And I know, because I’ve physically examined every single one by hand”

So there you have it: every snowflake is different; no two are alike. By molecular composition and physical structure, every snowflake is completely unique.

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And following that line of logic, I suppose that means every person is unique as well, including you. Never in the history of the universe will someone like you come around again. So celebrate the fact that, like each snowflake, you have made a completely unique and indelible impact on the world that can never be truly replicated.

For example, I’m unique for shoehorning in a sappy twist ending to this blog

Happy Holidays!

Dan would like to remind you that catching snowflakes on your tongue robs the world of a beautiful crystal that will never ever be recreated. He and the people at Science Everywhere would also like to wish you a safe and happy holiday season.