A German team has turned tales of invisibility cloaks made, famous by Grimm’s fairy tales and Harry Potter, into a potential – albeit a small – reality. About 0.00005 inches in fact. “Researchers at Karlsruhe Institute of Technology in Germany say they have rendered (almost) invisible a bump in a layer of gold measuring 0.00004 inches high by 0.00005 inches across, by ‘cloaking’ it in a new material. The ‘cloak’ is a structure of crystals with air spaces in between, almost like a pile of logs, which is able to bend light. When placed over a small layer of gold, the tiny bump could not be detected at infrared frequencies – very near to the spectrum of light visible to humans. Crucially, this new ‘metamaterial’ – artificially engineered to have properties not found in nature – was able to disguise the bump in three dimensions. Previous ‘cloaks’ have hidden objects when looked at head-on, but did not work if viewed from the side. While in this case the bump was so tiny that a magnifying lens was needed to see it, the lead researcher, Tolga Ergin, told the US journal Science there was no reason why the technology could not be developed to make much larger objects vanish. ‘In principle, the cloak design is completely scalable; there is no limit to it,’ Ergin said. Developing the fabrication technology so that the crystals were smaller could ‘lead to much larger cloaks’.”