Acoustic Stealth Technology Finally Created

smitty777 writes "An idea for acoustic stealth technology proposed in 2008 was finally put into practice. The abstract describes taking advantage of the 'transformation acoustics and linear coordinate transformations that result in shells which are homogeneous, broadband, and compact. The required material parameters are highly anisotropic; however, we show that they are easily achievable in practice in metamaterials made of perforated plastic plates.' It is thought this technology might be useful for shielding ships from sonar or creating soundproof rooms."

Re:Okay, but....

[Creepy]

Actually, aerodynamics technology can make a supersonic airplane signature (aka "boom") almost silent - the military and NASA has been investing in that for years.

For instance, from NASA's website [nasa.gov]:

Ltpinter: Hi Ed. I hope NASA is keeping you busy on really cool stuff. I would like to know if sonic booms can be reduced to a low rumble?

Ed.: Yes, we can make sonic booms that are very quiet, and can't be heard over normal conversation. It sometimes sounds like distant thunder. And referring to my last comment sometimes you can make the boom totally quiet if the aircraft is slow enough or high enough in altitude.

I know Eurocopter is working on a quiet helicopter, but I couldn't find the one I know about (nor can I talk about it, because they are a customer I'm working with). It may be the same technology as I was able to find, [eurocopter.com] but I'm not sure.

This technology has a different application - it bends sound around the object it surrounds, so sonically it appears to not be there. Being able to bend waves of different kinds around objects has fundamental uses - for instance, if you can bend radiation around a spaceship, you eliminate one of the problems with the theoretical Alcubierre drive (though I would say the theory existed before he wrote about it, as people in my physics class discussed it amongst other "further than light" ideas before 1994 - the two that we couldn't debunk were time bubbles and one that is difficult to describe, but I'd call it uncertainty tunneling).