[ExI] a clean well-lighted challenge
anders at aleph.se
Wed Sep 23 07:14:06 UTC 2015
On 2015-09-23 00:11, spike wrote:
> So now I have a challenge for you. Write a Hemmingway-esque story (or
> a you-esque story if you are better than Papa) which will teach me
> something, anything. The Hemmingway story has memorable qualities,
> but taught me nada. I am looking for a short story that is memorable
> and instructive, on any subject that interests you.
"Ah, yes, customers."
"Cannot live with them, cannot live without them."
"The optics guys."
"Those are the worst."
"I thought that was the security guys."
"Maybe. What's the deal?"
"Antireflective coatings. Dirt repelling."
"That doesn't sound too bad."
"Some of the bots need to have diffraction spread, some should not.
Ideally determined just when hatching."
"Hatching? Self-assembling bots?"
"Yes. Can not do proper square root index matching in those. No global
"Yes. Do not even think about what they want them for."
"I was thinking of insect eyes."
"No. The design is not faceted. The optics people have some other kind
"Have you seen reflections from insect eyes?"
"If you shine a flashlight in the garden at night you can see jumping
spiders looking back at you."
"That's their tapeta, like a cat's. I was talking about reflections from
"I have not looked, to be honest."
"There aren't any glints when light glance from fly eyes. And dirt
"They polish them a lot."
"Sure. Anyway, they have nipples on their eyes."
"Nipple like nanostructures. A whole field of them on the cornea."
"Ah, lotus coatings. Superhydrophobic. But now you get diffraction and
"Not if they are sufficiently randomly distributed."
"It needs to be even density. Some kind of Penrose pattern."
"That needs global coordination. Think Turing pattern instead."
"Some kind of tape?"
"That's Turing machine. This is his last work from '52, computational
"Never heard of it."
"It uses two diffusing signal substances: one that stimulates production
of itself and an inhibitor, and the inhibitor diffuses further."
"So a blob of the first will be self-supporting, but have a moat where
other blobs cannot form."
"Yep. That is the classic case. It all depends on the parameters: spots,
zebra stripes, labyrinths, even moving leopard spots and oscillating modes."
"All generated by local rules."
"You see them all over the place."
"Yes. Some Russians catalogued the patterns on insect eyes. They got the
entire Turing catalogue."
"Changing the parameters slightly presumably changes the pattern?"
"Indeed. You can shift from hexagonal nipples to disordered nipples to
stripes or labyrinths, and even over to dimples."
"Local interaction, parameters easy to change during development or even
after, variable optics effects."
"Stripes or hexagons would do diffraction spread for the bots."
Blagodatski, A., Sergeev, A., Kryuchkov, M., Lopatina, Y., & Katanaev,
V. L. (2015). Diverse set of Turing nanopatterns coat corneae across
insect lineages. /Proceedings of the National Academy of Sciences/,
Future of Humanity Institute
Oxford Martin School
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