Photo by L. Brian Stauffer
Posted on 01/05/2011 8:49:16 PM PST by decimon
CHAMPAIGN, Ill. — In one University of Illinois lab, invisibility is a matter of now you hear it, now you don’t.
Led by mechanical science and engineering professor Nicholas Fang, Illinois researchers have demonstrated an acoustic cloak, a technology that renders underwater objects invisible to sonar and other ultrasound waves.
“We are not talking about science fiction. We are talking about controlling sound waves by bending and twisting them in a designer space,” said Fang, who also is affiliated with the Beckman Institute for Advanced Science and Technology. “This is certainly not some trick Harry Potter is playing with.”
While materials that can wrap sound around an object rather than reflecting or absorbing it have been theoretically possible for a few years, realization of the concept has been a challenge. In a paper accepted for publication in the journal Physical Review Letters, Fang’s team describe their working prototype, capable of hiding an object from a broad range of sound waves.
The cloak is made of metamaterial, a class of artificial materials that have enhanced properties as a result of their carefully engineered structure. Fang’s team designed a two-dimensional cylindrical cloak made of 16 concentric rings of acoustic circuits structured to guide sound waves. Each ring has a different index of refraction, meaning that sound waves vary their speed from the outer rings to the inner ones.
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The cloaking technology also may affect nonlinear acoustic phenomena. One problem plaguing fast-moving underwater objects is cavitation, or the formation and implosion of bubbles. Fang and his group believe that they could harness their cloak’s abilities to balance energy in cavitation-causing areas, such as the vortex around a propeller.
(Excerpt) Read more at news.illinois.edu ...
wonder if this will stop the nudie pictures from being flashed in front of the minimum wage employee at the airport?
if so, BRING IT ON!
Ping
Romulan technology?
Are they underwater on their mortgages?
This isn’t good news - if our enemies get their hands on it, it could make us very much less safe from nuclear attack than we have ever been. (From an ex-sonarman in the navy)
bflr
Fang and a cloaking device sounds like a Plot for a old Sean Connery 007 movie.
Aren't our nuke subs noisier than the opposition's conventional subs? Might this not be of more benefit to us than to them?
The science behind basic “cloaking” of an object from waves of some form, light, sound, what have you, shouldn’t be all that complex. Calculate trajectory and speed of an incoming wave and project it out the other side. The sheer number of calculations, inputs and outputs would be a problem, though.
As far as “invisibility,” envision a head-to-toe suit with millions of embedded CCD/LED nodules registering inputs and emitting outputs, with the computing power to handle it all. You’d only see the faintest hint of something even close up, due to the projection of color and light from behind, on all sides and at every angle. It’d be a slightly pixelated, everchanging chameleon suit, the perfect camo.
There are devices that destroy sound by emitting the opposite frequency, and have been for years, to the point of inclusion in automobile mufflers. This is a one-sided application of the same idea. It’s much harder to continue a wave on, with an illusion as if unimpeded, than it is to just neutralize it.
>> Fang and a cloaking device sounds like a Plot for a old Sean Connery 007 movie.
LOL
Hmmm - some potential problems that weren’t addressed in the article:
1. How does our sub receive the signal back when they ping for other subs? Wouldn’t the cloak absorb that, too?
2. How do whales get out of the way of an oncoming sub doing 40 knots, when whales rely on their own type of sonar for navigation? That kind of accident would do a lot of damage to the sub and the Captain’s career, not to mention the whale.
3. Doesn’t underwater sub navigation depend on reliable sonar?
4. This should make for some interesting ‘tag’ games with the Russians and the Chinese, LOL.
Lots of potential problems here - hope these are being addressed.
by enclosing them in a massive earplug
It’s been my understanding, that subs don’t ping much anymore. The very act itself will give away your location. Instead, they listen for prop noise, plant noise and any number of other things.
I’m sure a bubble head will be along to comment with a bit more authority.
In use of active sonar (which is very verboten for our guys) you receive a return, or “ping” from the impedence mismatch of the air in the sub not the metal sub itself, that comes from the difference in the speed of sound in air/water/solid objects. Nothing classified here, just basic physics.
So you construct a device that causes the sound to “slide” around an object, instead of giving a ping off the air inside the object. If this is actual, and not theory it would work better than the sound dreddening tiles we use now!
oh man..felt like I was back teaching STS “A” school for a second there!
After searching in vain, I checked the press release again. I linked the article’s PDF at the end of the press release!
Sorry, we'll have to dock your pay.
Didn't know if you'd want to be pinged for this for the science angle but there is also the medical angle. This thing would be good for hiding your liver, I guess.
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