Imagine a multilayered shell where metal and insulator layers alternate like pages in a book. Such a structure can make an object hidden inside invisible to an observer. Light bends around it as water smoothly flows around a smooth stone: no ripple, no splash — no reflection, no shadow. Remarkably, the cloaking does not depend on the shape of the hidden object: whether it's a metal sphere or a plastic star, the shell works equally effectively across the entire visible spectrum: that is, for all wavelengths our eyes can perceive.

The mechanism relies on precise calculation of layer thicknesses. The outer layers of the shell are tuned to cancel scattering, the re-emission of light sideways, arising from the inner layers. This works on the analogy of wave interference: just as opposing water waves can cancel ripples when they overlap in antiphase, scattered light waves from different layers annihilate each other. As a result, scattering drops by a factor of 1000, and the object becomes unnoticeable. Light continues to travel at its usual speed (about 300,000 km/s in vacuum) but smoothly bends around the obstacle as if it weren't there.

Particularly noteworthy is that this cloaking is broadband: it covers all colors of the visible range at once — from violet to red. No hue will give away the hidden object, and the shell remains invisible under any lighting.