Apparently not content with simply building an invisibility cloak, of sorts, those mad scientists at Duke University's Pratt School of Engineering now say that they've found that a three-dimensional "sound cloak" is also possible, in theory. According to Duke's Steven Cummer, the researchers have come up with a "recipe" for an acoustic material that would "essentially open up a hole in space and make something inside that hole disappear from sound waves." Needless to say, they haven't tested that possibility just yet, but they say it could one day be used to hide submarines from detection by sonar or even be used to improve the acoustics of a concert hall by making inconvenient structural beams effectively disappear. What's more, they say that the basic principles at play here could also suggest that cloaks could be created for other wave systems, like seismic waves, or even waves at the surface of the ocean, although the practical applications for those would seem to be a bit more limited.

[Image courtesy of Royal Navy/BAE Systems]