If you’re a non-magical being, you might think your chances of becoming invisible are slim to nil. But don’t jump to conclusions just yet: Researchers are now claiming to have developed a portable system that can make small objects, like your keys or pet lizard, disappear from sight.
Top image: Conceptual model of an invisibility cloak in which lightwaves travel around the object, via Wikimedia
The key to real life invisibility lies in clever optical tricks that bend light around an object, shielding it from detection. In principle, such technology has only been demonstrated for very tiny objects, but now, a group of researchers from the Karlsruhe Institute of Technology say they’ve developed a scaled-up system that can be ported around and used for classroom demonstrations.
The problem researchers typically run into when they try to bend light around an object lies in compensating for the extra distance the light must travel. Since they can’t very well increase the speed of light in air, the KIT team has developed a silicon-based organic polymer (PDMS), that, doped with titanium dioxide nanoparticles, scatters light waves to slow them down. Once slowed, the light can be sped up again to make up for the longer path around the veiled object.
In a diffusive light-scattering medium, light moves on random paths. A normal object casts a shadow, an object with an invisibility cloak does not. Image Credit: R. Schittny, KIT
When the KIT researchers want to cloak an object, they place it inside a hollow metal cylinder coated with acrylic paint, which diffusely reflects light. That metal tube is then embedded inside a light-scattering PDMS block. If the time it takes light to travel through the block is just the right proportion of the time it takes light to travel through the cloak, the cloak becomes invisible. Or so the researchers say—the first actual demonstration of this technology will take place on May 13th, according to a press release.
While it’s a far cry from a cloak you can actually don—unless you fancy walking around inside a giant metal tube inside a giant block of silicon—this proof-of-concept could, one day, lead to more sophisticated materials that are wearable. In the meanwhile, a simple device that can make cellphone-sized objects disappear from sight sounds like the start of any number of excellent pranks.
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