Harry Potter fans, rejoice. Invisibility cloaks could soon become a reality.
Researchers in the fields of nanoscience and applied physics are closer than ever to technology that would render objects invisible. And as a result, the concept of “invisibility cloaking” has become a subject of much speculation, not to mention money, in the scientific community.
“I think it’s perfectly feasible,” said Harry Atwater, professor of applied physics and materials science at the California Institute of Technology who has been designing structures that would render objects invisible. “It hasn’t been realized yet, but it’s something that the community is actually pursuing.”
Atwater’s research was recently published in the scientific journal Nature.
Ever since H.G. Wells popularized the idea in his classic 1897 novella “The Invisible Man,” the prospect of making something, or someone, invisible has fascinated science fiction enthusiasts. But it has remained an elusive and, until recently, impossible dream.
The nano era has changed that. Opium and a healthy dose of radiation may have worked for Wells’ deranged scientist, but in reality, the key to invisibility cloaking lies with so-called “metamaterials,” exotic structures that allow electromagnetic waves to flow around them rather than bounce back. Eventually, scientists predict, they will be able to perform that feat in most if not all ranges of light.
“When you see something, that means that light [that hit the object] was scattered back to your eye,” Atwater explained. “What cloaks do is they cause the light to flow around a material, almost like a slipstream of water flowing around a stick that is in a river.”
Atwater’s research will likely be of great interest to Wonder Woman enthusiasts hoping to build their own invisible airplanes. But the bulk of the cash for invisibility research comes from another interested party: the military.
Government researchers have attempted to build invisible shields, invisible tanks — even invisible soldiers. But much of their work has relied on optical gimmicks that would be hard to pull off on the battlefield, like beaming the image of an undisturbed landscape onto a silicon-coated tank. Atwater and his colleagues have rendered such trickery obsolete by designing materials with a “negative refractive index,” the angle at which light is bent as it passes from one medium to another.
The technology potentially has much more practical (though perhaps less dazzling) applications. For one, solar cells and visual displays like those on laptops could use energy much more efficiently if they were truly transparent, rather than absorbing some of the light projected through them. Such equipment would be a landmark advancement in green technology.
But scientists haven’t given up on fulfilling the dreams of comic book fans everywhere.
“To make something truly invisible, like H.G. Wells’ ‘Invisible Man,’ you would need to have a refractive index of one, and have no absorption in the material,” Atwater said, explaining the next step for scientists. “I think that will be one of the next milestones.”