I love science.

[theweaselking]

Jules Mikhael and his colleagues didn’t set out to make a material with a structure that had never been seen before, much less one that combines order and irregularity in a whole new way, one that Archimedes hinted at 2,000 years ago, one bound together by the Fibonacci sequence. They just wanted to understand a quasicrystal.

Even that wasn’t such a modest goal, because quasicrystals are pretty odd critters. Slice one in half, and there is a sort of mosaic with repeating shapes like tiles, much like a crystal. But here’s the bizarre part: Spin the resulting mosaic a fifth of a turn and often its tiles will line up exactly as they were before you spun it.

But that kind of five-fold symmetry is “forbidden,” because mathematicians have shown that no repeating flat pattern has it. That’s why you’ve never seen a bathroom tiled with pentagons—it’d be impossible to cover the whole surface with no gaps.

The secret of a quasicrystal is that its patterns never repeat. The tile shapes within the quasicrystal combine and recombine, with one area perhaps looking similar to another but then skipping off in its own unique formation. This eternal irregularity also gives quasicrystals remarkable, intriguing properties. For example, they tend to be slippery like Teflon, and even when made from metals, they’re good insulators.

Physicists have never really understood why quasicrystals have these properties, though.

Comments

[sivi-volk.livejournal.com]

Science rocks. Hard. I'm looking forward to being a scientician again.

[elffin.livejournal.com]

Specifically, good electrical insulators, and the electrical insulation is because the atoms in each arbitrary spatial domain of the quasicrystal are not arranged in an orderly fashion, but rather "randomly" oriented, as they are when metal is heated. Heated metal is a terrible electrical conductor, because electrons don't pass from atom to atom but bounce around and are converted to photons. So each small domain of a fifth of the quasicrystal is like a frozen snapshot of a heated metal.

In addition, ferrous metals that are (hypothetically) arrayed as a quasicrystal (I don't know if there are any examples of such or if it is possible, I'm merely extrapolating based on the laws of physics) would be non-magnetic due to the non-homogenous orientation of their electron clouds, and probably wouldn't even be weakly diamagnetic.

The same explanation would contribute to understanding why they're slippery - if a given arbitrary quasicrystal spatial domain is unable to exchange electrons with neighboring domains, any charge that ambiently makes its' way onto the domain would be difficult to drain to ground, producing a fluffy "quilted" cloud of electrostatic repulsing domains - the same way Teflon works.

[elffin.livejournal.com]

Well, Teflon works with van der Waals forces rather than electrostatic forces, and these likely do the same.

I wish I knew more about them to be able to say precisely how and which occurs here.

[nancylebov.livejournal.com]

Anyone remember Illuminatus!?

[elffin.livejournal.com]

Never trust anyone with finn2 for a username.

[unknownpoltroon.livejournal.com]

THis is 3.1459 levels above my math skills.

[snarkpuppie.livejournal.com]

There is actually a set of pentagons that will tessellate, though not your standard symmetrical pentagon. This link (http://www.mathpuzzle.com/tilepent.html) lists the 14 different types and when they were first discovered/documented. Tiling your bathroom may still present a challenge though :)

[theweaselking.livejournal.com]

They mean regular pentagons, not "any five-sided figure"

[opaqueplanet.livejournal.com]

does it have to be flat? what if your bathroom is a buckyball configuration? :P

[theweaselking.livejournal.com]

Buckeyballs involve more than just pentagons. They're a soccerball shape - pentagons and octagons!

[opaqueplanet.livejournal.com]

not C^20! And the most common one, C^60 is actually pentagons and hexagons.
http://en.wikipedia.org/wiki/Fullerene

C^20 is a dodecahedron (or d20), so I'm not sure why I didn't just say dodecahedron in the first place. The article just had me thinking all in chemical structures.

[opaqueplanet.livejournal.com]

man, pretend those superscript symbols mean subscript. ugh.