
The Visual Patterns of Audio Frequencies Seen through Vibrating Sand - vilda
http://www.thisiscolossal.com/2013/06/the-visual-patterns-of-audio-frequencies-seen-through-vibrating-sand/
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Jabbles
It is interesting, but it's a standard way of demonstrating normal modes, or
the applications of eigenvectors. I would think most physics and engineering
undergraduates have studied this.

That's not to say you shouldn't watch it, but just to put it in perspective -
this is a topic studied in the 1st/2nd year of university, not a poorly-
understood topic for research.

[https://en.wikipedia.org/wiki/Normal_mode](https://en.wikipedia.org/wiki/Normal_mode)

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throwaway1979
I'm a cs person and never encountered this in school. Is this taught in
engineering? Typical course names?

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btilly
As a math person, I look at this and think "Fourier series".

I encountered the ideas in both Classical Mechanics 1 (third year physics
course where I took it) and Differential Equations (third year math course
where I took it).

It is still a nice visualization.

~~~
diydsp
It's very close to Fourier series, but since the "solutions" (the equilibria)
are not integer multiples of a fundamental, but solutions to a 3-dimensional
wave equation, it's more like "wave equation."

~~~
btilly
From a mathematician's point of view it is a Fourier series. You have the
property that any starting state can be divided into the sum of orthogonal
components. No matter how complex the components are, that's still a Fourier
series.

A physicist would disagree, I am sure. But to a mathematician, an orthonormal
wavelet basis is also a Fourier series.

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sambeau
"The study of the patterns produced by vibrating bodies has a venerable
history. One of the earliest to record that an oscillating body displayed
regular patterns was Galileo Galilei. In Dialogue Concerning the Two Chief
World Systems (1632), he wrote:

As I was scraping a brass plate with a sharp iron chisel in order to remove
some spots from it and was running the chisel rather rapidly over it, I once
or twice, during many strokes, heard the plate emit a rather strong and clear
whistling sound: on looking at the plate more carefully, I noticed a long row
of fine streaks parallel and equidistant from one another. Scraping with the
chisel over and over again, I noticed that it was only when the plate emitted
this hissing noise that any marks were left upon it; when the scraping was not
accompanied by this sibilant note there was not the least trace of such marks.
"

[http://en.wikipedia.org/wiki/Cymatics](http://en.wikipedia.org/wiki/Cymatics)

These patterns are also drawn on tiles in the Rosslyn Chapel and are thought
to be displaying music:

[http://en.wikinews.org/wiki/Rosslyn_Chapel_music_score_'deco...](http://en.wikinews.org/wiki/Rosslyn_Chapel_music_score_'decoded')

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ja27
Why is it sometimes asymmetrical vertically? Is it just a slight variation
where the plate isn't perfectly square or the bolt not in the exact center?

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gliese1337
It appears to be simply a lack of sufficient sand to show all of the lines-
some of them become symmetrical when more sand is sprinkled on.

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iknowno_one
Here's a Science Friday video of the same thing but without the music on top,
so you can actually hear the frequencies.

[http://www.npr.org/player/v2/mediaPlayer.html?action=1&t=1&i...](http://www.npr.org/player/v2/mediaPlayer.html?action=1&t=1&islist=false&id=103210918&m=103221404)

~~~
DanBC2
Here's a not very good example using hair and a car stereo
([http://youtu.be/4s_lpBkdoNc](http://youtu.be/4s_lpBkdoNc))

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ck2
I wonder if that could be done at scale with a massive art installation and
marbles.

Now that would be mind blowing to watch.

~~~
DanBC2
I'd love to see an enormous version of this harmonic motion demonstration.

([http://sciencedemonstrations.fas.harvard.edu/icb/icb.do?keyw...](http://sciencedemonstrations.fas.harvard.edu/icb/icb.do?keyword=k16940&pageid=icb.page80863&pageContentId=icb.pagecontent341734&state=maximize&view=view.do&viewParam_name=indepth.html#a_icb_pagecontent341734))

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jtheory
Interesting, but for a similar experiment that's rather higher on the "cool"
spectrum, check some of the videos with "oobleck" (non-newtonian fluid, like
cornstarch and water) on an amp.

~~~
jtheory
Here's the first one I saw, a couple of years ago:

[http://www.youtube.com/watch?v=Yp1wUodQgqQ](http://www.youtube.com/watch?v=Yp1wUodQgqQ)

Linking it here because I just went searching for new examples, and none of
what I found was quite as good at fooling my brain that living creatures were
crawling out of the muck...

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swamp40
I wonder what would happen if you designed a helmet that vibrated your brain
like that?

Maybe some frequency could tweak pleasure centers, etc?

~~~
leephillips
I don't think small deformations of the brain do much, because they don't
change the connectivity or electrical activity of the neurons. However, there
are devices that induce currents inside the brain by applying magnetic fields,
and this has profound effects.

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ccallebs
Has this been attempted in a zero-gravity environment (or even water)? Would
that completely obliterate the results of the test, as the sand wouldn't be on
a solid surface? I'm curious what the results would be.

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ktf
There's a really fun exhibit at the Exploratorium in SF that demonstrates
this. Not _quite_ so fancy, but if you can shove some kids out of the way it's
still pretty cool to play with!

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joeblau
They have this at the Exploratorium! Definitely cool to play with.

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masnick
Bold title for WWDC day.

~~~
leephillips
Because some shiny new gadget will impress you more than a beautiful
visualization of the mathematical structure of nature?

~~~
masnick
That was tongue-in-cheek (mostly...you never know with WWDC).

This video reminds me a bit of A New Kind of Science
([http://en.wikipedia.org/wiki/A_New_Kind_of_Science](http://en.wikipedia.org/wiki/A_New_Kind_of_Science)):
some of the phenomena Wolfram discusses gave me the same "holy! how does this
happen in nature" kind of reaction.

~~~
leephillips
Sorry for coming on so strong. And for being that guy who misses the tone.

~~~
masnick
No worries, we're all that guy sometimes.

+1 for emoji support in HN comments. (Also ironic...mostly.)

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n3rdy
Couldn't you use something like this on a small scale to implement a better
random number generator for computers?

Looks like all it would take is a tiny speaker, a thin metal plate, and
something that reads that metal plate like a QR code. The tone could then be
randomized by a psuedo-random number generator, and even though the shapes
generated are similar, they are never quite identical.

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jpenny_im
if you want to see many other examples, search for "chladni plate"

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jlengrand
Actually, this is salt.

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TheRubyist
No.

