Newly Developed Cloak Hides Underwater Objects From Sonar: "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."