Call it Harry Potter's invisible sleeve. New calculations show how to make an electromagnetic "wormhole"—a tube that is invisible from the sides but allows light to shine down the center.
The concept is a twist on a spherical cloak of invisibility proposed last year. Such a device would be made of metamaterial, a thicket of metal rings or other shapes that bends light in funny ways. A hollow shell of metamaterial could in principle channel light around its inner space without slowing the light down, rendering that hidey-hole invisible to the outside world.