Active Cloaking Could Counter Radar, Earthquakes, and Tsunamis
Electromagnetic fields can cloak objects from passing waves Today's stealth fighters, such as the F-22 Raptor, may do pretty well in concealing their radar signature, but mathematicians say that a new active cloaking technique could someday generate electromagnetic fields to hide submarines from sonar, or even protect buildings from earthquakes. Active cloaking differs from cloaking technologies that rely on special materials to bend light or other electromagnetic waves around an object. Scientists have focused on next-generation metamaterials that can only shield very small objects from visible light "The problem with metamaterials is that their behavior depends strongly on the frequency you are trying to cloak from," said Graeme Milton, a mathematician at the University of Utah. "So it is difficult to obtain broadband cloaking. Maybe you'd be invisible to red light, but people would see you in blue light." By contrast, active cloaking...