Ask Ethan: Could you have two perfectly identical snowflakes? (Synopsis)

"Lives are snowflakes - unique in detail, forming patterns we have seen before, but as like one another as peas in a pod (and have you ever looked at peas in a pod? I mean, really looked at them? There's not a chance you'd mistake one for another, after a minute's close inspection.)" -Neil Gaiman
When you see a snowflake, what you're seeing is a thin crystal of ice, with intricate, hexagonally-symmetric features that reveal themselves under a microscope. Although snowflakes come in a myriad of different shapes and patterns, there's one adage you've heard since you were a kid: that no two snowflakes are alike.
Two nearly identical snow crystals as grown under laboratory conditions at Caltech. Image credit: Kenneth Libbrecht / Caltech / SnowMaster 9000. Two nearly identical snow crystals as grown under laboratory conditions at Caltech. Image credit: Kenneth Libbrecht / Caltech / SnowMaster 9000.

From a scientific perspective, is that true? What gives snowflakes their intricate structures, and what does it truly mean for a snowflake to be unique? Do we require the exact same branching structure? Can we obtain that if we create them artificially? Do we require identical-ness down to a molecular or atomic level? And how much snow would we need for that to happen?

The formation and growth of a snowflake, a particular configuration of ice crystal. Image credit: Vyacheslav Ivanov, from his video at Vimeo: http://vimeo.com/87342468. The formation and growth of a snowflake, a particular configuration of ice crystal. Image credit: Vyacheslav Ivanov, from his video at Vimeo: http://vimeo.com/87342468.

Come find out the real science behind two snowflakes being alike on this week's Ask Ethan!

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