Using Special Crystals, Researchers Make a Paper Clip Invisible• popsci.com
Metamaterials have long been thought the key to creating the working, visible spectrum “invisibility cloak” promised us by sci-fi, but it might be time for metamaterials to move over. Two independent labs—one at the University of Birmingham in the UK, the other at MIT—have used naturally forming calcite crystals to render visible objects (as in large enough to see with the naked eye) invisible, something metamaterials haven’t come close to doing.
Metamaterials have achieved a measure of invisibility, but not in any practical sense; they can bend certain wavelengths of light to conceal an object at the microscopic level, but so far they have not been able to work well at the macro scale or in the visible spectrum. It turns out researchers may not have needed such an exotic medium.