Naturally Occurring Quasicrystals | Hacker News Reader

Naturally Occurring Quasicrystals

johncarlosbaez.wordpress.com

134 pointslukeplato11 comments

I remade the hero GIF in HD

https://www.shadertoy.com/view/sXsGDl

Thanks! Perfect match as far as I can see, nice one! How did you learn/know how to do this?

The code was really interesting to read and tinker with! I made a version where the symmetry (7 originally) can be other numbers, and that was fascinating to see!

ShaderToy forever!!

Ah silly me, you put the sources in the comment!! Thanks for that I will have a read for sure!

It struck me as looking a bit like a demoscene plasma effect but with a radial/angular aspect! (also reminds me of cymatics diagrams a bit!)

I experimented with non-integer symmetries and it seemed not to introduce discontinuities, and I made it produce an RGB value for fun too:

https://www.shadertoy.com/view/7XsGWs

Wow this is too much fun for simple sum-of-cosines but I shouldn't be surprised (have played with FFT a bit, and I know of Reimann Zeta Function.. sines are amazing!)

I doubled the angle so that it doesn't drift to the side any more.. and put it back to 7-symmetry, but left it with the coloring I added (now adjustable via consts):

https://www.shadertoy.com/view/7Xl3Ws

And a small tweak:

https://www.shadertoy.com/view/73lGDs

If you squint with it on fullscreen on that last one there's a wonderful mixture of things feeling like they are rotating vs flowing inward-and-outward from 'centers' (like it's ambiguous whether it's curl or divergence somehow for my eyes/brain at least!).

Hooray for sines and cosines and shaders and thanks for motivating me to play!

So cool! It reminds me of the kaleidoscope I played with as a kid. Truly mesmerizing.

FYI your second link is not working

Ah thanks for letting me know! I had not set it to public. It's public now though! Glad you enjoyed it!

If you haven't already, read the book "The Second Kind of Impossible" by Paul Steinhardt

https://www.goodreads.com/book/show/35297608-the-second-kind...

It's a riveting account of years of research to discover Quasicrytals from theory, to experiments, to literally hunting in a meteor field in eastern Russia!

Related, if you're interested in byproducts of nuclear explosions:

> researchers have identified a new material within trinitite called a clathrate—a cagelike chemical lattice that traps other atoms inside it.[0]

[0]https://www.scientificamerican.com/article/strange-crystals-...

There are also "natural" paracrystalline viruses that turn isopods blue and then kill them.

https://en.wikipedia.org/wiki/Invertebrate_iridescent_virus_...

There was a mathematician and a chemist arguing these structures had a pattern that had something to do with the distribution of prime numbers. https://www.quantamagazine.org/a-chemist-shines-light-on-a-s...

tl;dr Quasicrystals are aperiodic structures. The author notes that the conditions for creating them are rare, given the need for instantaneous high temperature. They recount that these can happen during space debris impact and when lightning hits sand. They close out by describing some of the chemical 'formulas' for these materials, given that characterizing a prototypical section is difficult without repeating elements.

I don't have anything to say about quasicrystals, other than it seems right up this blog's alley, as the other most recent articles are about math and materials (like feldspars [0]).

[0] https://www.explainxkcd.com/wiki/index.php/2501:_Average_Fam...

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