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January 10, 2008

Stealth submarines invisible to sonar with metamaterial design

Duke University engineers will reveal Friday (Jan. 11) details of an acoustic cloak fabricated from metamaterials that they claim can render objects invisible to sonar. If this works then we will have unprecedented control to hide from the effects or to enhance the effects of sound and other waves in all kinds of material. Submarines invisible to sonar would extend the security of nuclear weapons deployed on submarines against future sensing technology. Even if one side had nanotechnology it would take a lot to find invisible to sonar stealth submarines that were carrying nuclear weapons. Extending the deterrent of nuclear weapons makes for a more militarily stable future world.

Although the acoustic cloak has only been mathematically simulated, the engineers claim that devices based on their blueprint can make submarines invisible to sonar. "We have shown that acoustic cloaks theoretically do exist," said Duke University professor Steven Cummer. "Our recipe shows how to make an acoustic material that essentially opens up a hole in space--making whatever is inside that hole 'disappear'."

Further, the engineers claim that the technique proves that waves can be redirected around objects in different media, opening up the possibility of improving the acoustics in concert halls by cloaking structural beams from sound waves in air. It may even be possible to redirect seismic waves around buildings [making them earthquake resistant], or ocean waves around ships.

Besides fabricating an acoustic cloak based on the blueprint, the researchers also claim that the technique will make it possible to use metamaterials to bend and concentrate sound waves in new ways.

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