Purdue University researchers have taken a practical step toward creating an “optical cloaking” device that could render objects invisible by guiding light around anything placed inside this “cloak,” an array of tiny needles radiating outward from a central spoke.

Calculations indicate the device would make an object invisible at a wavelength of 632.8 nanometers, which corresponds to the color red. The same design, however, could theoretically be used to create a cloak for any other single wavelength in the visible spectrum.