14 DAY TRIAL // Scientists at the University of Utah have recently announced the development of a new mathematical model, which could lead to the creation of a novel cloaking method. The research is not aimed at producing “invisibility cloaks” that absorb visible light, but rather at creating new means of making stealth planes even stealthier, at rendering submarines invisible to sonar waves, buildings invisible to earthquakes, and coastal buildings invisible to tsunamis. A paper detailing the achievement was published online, in the August 14th issue of the Physical Review Letters.
“We have shown that it is numerically possible to cloak objects of any shape that lie outside the cloaking devices, not just from single-frequency waves, but from actual pulses generated by a multi-frequency source. It's a brand new method of cloaking. It is two-dimensional, but we believe it can be extended easily to three dimensions, meaning real objects could be cloaked. It's called active cloaking, which means it uses devices that actively generate electromagnetic fields rather than being composed of 'metamaterials' [exotic metallic substances] that passively shield objects from passing electromagnetic waves,” UU Distinguished Professor of Mathematics Graeme Milton explains.
The National Science Foundation (NSF)- and the University of Utah-funded research was carried out by Milton, as the senior author, and UU Assistant Professors-Lecturers in Mathematics Fernando Guevara Vasquez and Daniel Onofrei. Details of the find also appear online in the August 16th issue of the respected scientific journal Optics Express. Theoretically, invisibility cloaks could be created for anything from sound waves, sea waves, and seismic waves, to electromagnetic waves such as visible light, microwaves, infrared light, radio and TV waves.
The main advantage that the new technology has over other invisibility cloak methods is the fact that it uses waves to conceal an object, rather than metamaterials. These special materials are constructed from their atomic structure upwards, and are designed to have other physical and chemical traits than they would normally have. “The problem with metamaterials is that their behavior depends strongly on the frequency you are trying to cloak from. So it is difficult to obtain broadband cloaking. Maybe you'd be invisible to red light, but people would see you in blue light,” Milton says.
“Our method may have application to water waves, sound and microwaves [radar]. It would be wonderful if you could cloak buildings against earthquakes. That's on the borderline of what's possible. Even though cloaking from light is probably impossible, it's a fascinating subject, and there is beautiful mathematics behind it. The whole area has exploded. So even if it's not going to result in a 'Harry Potter' cloak, it will have spinoffs in other directions, [such as] for building new types of antennas, being able to see things on a molecular scale. It's sort of a renaissance in classical science, with new ideas popping up all the time,” Milton concludes.