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        riddles >> easy >> Listen! Can you see it?
        
(Message started by: rloginunix on Oct 16^th, 2014, 6:58pm)

Title: Listen! Can you see it?
Post by rloginunix on Oct 16^th, 2014, 6:58pm

Listen! Can you see it?

That is it - how can you make sound visible?

This question (and the intended answer) is based on a real [hide]scientific event[/hide] and has to do both with math and physics, which go hand in hand on this one, in tune so to speak.

P.S.
I have no doubt in the awesome inventive powers of the members of this forum so other scientifically plausible answers are also welcome.

Title: Re: Listen! Can you see it?
Post by diva on Oct 16^th, 2014, 9:37pm

it would be great if i cna understand more about it. @william pen

Title: Re: Listen! Can you see it?
Post by SWF on Oct 16^th, 2014, 10:16pm

[hide]Density difference in air results in different index of refraction, which can be visible: see slow motion video of power explosions, or shadow graphs of high speed projectiles. Can sprlkle sand on a drum head to see vibration patterns. See "sonoluminescence": light emitted from bubbles in an ultrasonically excited liquid.[/hide]

Title: Re: Listen! Can you see it?
Post by dudiobugtron on Oct 16^th, 2014, 11:46pm

Buy one of these?

http://www.tqualizer.com/images/P/tqualizer-raver-p.gif

Title: Re: Listen! Can you see it?
Post by towr on Oct 17^th, 2014, 1:54am

A balloon (or other receptive surface) and a strobe light?

Title: Re: Listen! Can you see it?
Post by alien2 on Oct 17^th, 2014, 4:36am

on 10/16/14 at 18:58:19, rloginunix wrote:

That is it - how can you make sound visible?

Nobody suggested, except for crazy people, that the written word 'sound' is invisible. My imagination has its limits so this is all I can think of.

Title: Re: Listen! Can you see it?
Post by rloginunix on Oct 17^th, 2014, 9:08am

All the ideas are interesting but SWF and towr got closest to the intended answer. Out of the three main items used in the experiment they both mentioned one.

For a clue as to the second item look at the problem statement, there's a hint there.

The third item is so common that most of us see it every morning without giving it a second thought.

The last hint: time travel to [hide]1855[/hide].

[edit]
Sorry. One more thing. Don't forget about the math portion - least common multiple, rational and irrational numbers are involved.
[/edit]

Title: Re: Listen! Can you see it?
Post by alien2 on Oct 17^th, 2014, 2:54pm

New research confirms a theory: high-frequency acoustic waves can be converted to light. (http://www.popsci.com/scitech/article/2009-03/sound-becomes-light)

Title: Re: Listen! Can you see it?
Post by rloginunix on Oct 18^th, 2014, 8:26am

That is an interesting new development. Thank you for the link, alien2. I've bookmarked the page.

May be my clues were too vague, sorry.

So SWF and towr got the beam of light.

The second item is hinted at in the problem statement's "... in tune so to speak". If you play(ed) a guitar, for example, you likely have used this item once in a while.

When you look into the third item in the morning someone very familiar stares back at you.

1855, France.

Wiki has an article about it, another article covers the experiment's math, youtube has a bunch of clips showing the recreation of the experiment.

Title: Re: Listen! Can you see it?
Post by rloginunix on Nov 7^th, 2014, 11:42am

Just me. Tying up the loose ends.

The experiment I was hinting at was performed by the French mathematician [hide]Jules Lissajous[/hide] where he used two [hide]tuning forks[/hide] in orthogonal formation. Each [hide]fork[/hide] had a small [hide]mirror[/hide] attached to it. When a beam of light is shone on the vibrating [hide]mirrors[/hide] it paints a curve on a wall thus making the sound visible.

If each vibration is a simple harmonic motion then the resulting compound curve traced by an (x, y) point is:

x = aSin(http://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/omega.gifhttp://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/sub1.gift + http://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/varphi.gifhttp://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/sub1.gif)
y = bSin(http://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/omega.gifhttp://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/sub2.gift + http://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/varphi.gifhttp://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/sub2.gif)

If the ratio (http://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/omega.gifhttp://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/sub1.gif\http://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/omega.gifhttp://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/sub2.gif) is a rational number then the resulting curve (no matter how intricate) will eventually close and the motion of the above point will be periodic, the least common multiple of the two individual periods being a common period.

If the above ratio is an irrational number then the curve will never close but the point will eventually paint the a by b rectangle.