In 1897. H.G. Wells created a fictional scientist who became invisible by changing his refractive index to that of air, so that his body could not absorb or reflect light. More recently, Harry Potter disappeared from sight after wrapping himself in a cloak spun from the pelts of magical herbivores. Countless other fictional characters in books and films throughout history have discovered or devised ways to become invisible, a theme that long has been a staple of science fiction and a source of endless fascination for humans. Who among us has never imagined the possibilities? But of course, it's not for real. Or is it?
While no one yet has the power to put on a garment and disappear, Elena Semouchkina, an associate professor of electrical and computer engineering at Michigan Technological University, has found ways to use magnetic resonance to capture rays of visible light and route them around objects, rendering those objects invisible to the human eye. Her work is based on the transformation optics approaches, developed and applied to the solution of invisibility problems by British scientists John B. Pendry and Ulf Leonhardt in 2006.
At its simplest, the beams of light flow around the object and then meet again on the other side so that someone looking directly at the object would not be able to see it—but only what's on the other side.
"You would see the light source directly through the object," said Semouchkina. "This effect could be achieved if we surround the object by a shell with a specific distribution of such material parameters as permittivity and permeability."
She and her collaborators at the Pennsylvania State University, where she is also an adjunct professor, designed a nonmetallic "invisibility cloak" that uses concentric arrays of identical glass resonators made of chalcogenide glass, a type of dielectric material—that is, one that does not conduct electricity.
Multi-resonator structures comprising Semouchkina's invisibility cloak belong to "metamaterials"—artificial materials with properties that do not exist in nature—since they can refract light by unusual ways. In particular, the "spokes" of tiny glass resonators accelerate light waves around the object making it invisible.
In computer simulations, the cloak made objects hit by infrared waves—approximately one micron, or one-millionth of a meter long—disappear from view.
The potential practical applications of the work could be dramatic, for example in the military, such as "making objects invisible to radar," she said, as well as in intelligence operations "to conceal people or objects."
"We want to move experiments to higher frequencies and smaller wavelengths," she said, adding: "The most exciting applications will be at the frequencies of visible light.”
Give the summary of the text using the words below:to use magnetic resonance to capture rays of visible light and route them around objects; to render objects invisible; to be based on the transformation optics approaches; to flow around the object; to use concentric arrays of identical glass resonators.
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