Now you see the fish, now you don't. Well, from certain angles, anyway.
Researchers from China's Zhejiang University have devised a way to shield aquatic and terrestrial creatures from view using a specialized "invisibility cloak," or "box of invisibility."
Based on a concept developed by theoretical physicist Sir John Pendry, the cloaking device uses optical glass to bend light around the living animals within an enclosure of prisms.
Dr. Hongsheng Chen, an electromagnetics professor at the university, and his team wrote in a study uploaded to arXiv.org this month that they sought to simplify Pendry's concept in order to allow the cloak design to be made in large scale using commonly available materials.
Baile Zhang, an assistant physics professor at Singapore's Nanyang Technological University, unveiled a similar concept at a TED conference earlier this year. In a video demonstrating Zhang's design, a transparent block of the mineral calcite shields a small object from view.
Though Chen touches on the use of this mineral to achieve invisibility in visible light, he notes in his paper that it had been shown to work primarily on items that measure in the millimeters, whereas Chen's methods were devised with larger objects in mind.
And while artificially engineered components capable of bending light and interacting with electromagnetic waves are the key to invisibility in other methods, such man-made metamaterials are not a requirement of Chen's invisibility cloak. Instead, his team manipulates the cloaking materials to achieve results.
As seen in the videos of their experiments, the cloak is not worn in the traditional sense. It acts more like a shield, providing an "invisibility cloaking for natural light" from multiple angles of observation.
Nature cleverly describes the experiment as a "trick." The journal reports it's "arguably closer to ‘disappearances’ staged in Victorian music hall using arrangements of slanted mirrors than to the modern use of substances called metamaterials to achieve invisibility by guiding light rays in unnatural ways."
Last month, researchers at Duke University announced they had come up with a simple method to 3D print an invisibility cloak. Though the device, which includes a metamaterial layer, is limited to an 8-inch diameter due to the size of typical 3D printers, the lead researcher was confident that larger cloaks could be created by connecting parts printed separately.
Watch Chen and his team use their "invisibility cloak" to obscure a fish (above) and cat (below) from view.