By Mark Frauenfelder at 8:34 am Thu, Mar 21, 2013
Twisted Sifter has a great gallery of snowflake and ice crystal electron microscope photos. At this level of magnification, the ice looks like metal that has been machined by space aliens.
25 Microscopic Images of Snow Crystals
Next, could we please see angels dancing on the head of a pin?
Stupid question, but I’ve never been able to figure out how snowflakes get their symmetry. How does a water molecule that may or may not acdrete on one spot “know” where molecules are accreteing on other arms of the flake?
What I love about these pictures is that they suggest that the prevailing hypothesis on this is complete nonsense.
The hypothesis we are all told in school when we ask this question is that snowflakes are formed from “seed crystals” – these are tiny enough that they are a single crystal, and perfectly symmetrical. Why the crystal itself is symmetrical is left to the imagination; as is how it managed to store and convey the information for the specifics of the symmetrical branching to the growing flake.
But essentially, it it claimed that assuming that the various sides of the snowflake remain at the same humidity and temperature, they necessarily must grow at the same speed, and in the same ways, since all six sides of the seed crystal are identical. Magically identical by magic. But differently identical than other snowflakes. Magically differently identical.
Looking at these pictures, you can see the fine structure of the ice crystals around the gaps. It’s basically complete freaking chaos. There is ZERO symmetry in the fine structure. So that simply cannot be the reason for the coarse symmetry.
Fucking snowflakes, how do they form?
Seems like a non sequitur to me, it could certainly be that the humidity/temperature/seed crystal are enough to ensure broad symmetry but not symmetry of fine details. Your argument is a bit like saying “when we look at the fingerprints of identical twins they are completely different at the level of fine structure, so shared DNA and a shared intrauterine environment simply cannot be the reason for their closely similar appearance at the course level.”
I mean I could understand if temp and humidity conditions meant that the snowflakes toggled between two or three different structures, kind of like carbon or metal alloys. But snowflakes have a bewildering array of different shapes, and they still manage to be mostly symmetrical.
I looked around, it turns out they actually have simulated snowflake growth on a computer (using purely local rules where the behavior of each “pixel” depends only on its immediate neighbors), and they do get a wide variety of different shapes as seen in the video here. This page has links to various papers on the simulation. I liked this paper, which has a section starting on p. 11 titled “The Puzzle of Symmetric Complexity” which explains that part of the reason for the diversity of shapes is that outside conditions like temperature and humidity are continually fluctuating as the snowflake falls, and that each part of a given snowflake sees the same fluctuations (but different snowflakes, with different paths downward through the atmosphere, see different fluctuations).
To show up in an electron image, the subject must be coated with a heavy metal (in this case platinum). So this really is metal machined by aliens (where the aliens are us).
Yes, and there may be a deeper layer of detail to the structure that we can’t see in these images because the sputter coating process may gloss it over.
Or gilt by aliens, more accurately.
I wonder how much of the detail is due to the sputter coating and other debris?
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