Light behaves in rather tame and predictable ways when interacting with everyday objects—it travels in straight lines, rebounds when it hits shiny surfaces, and gets bent by lenses. But weird and wonderful things start to happen when light interacts with very small objects. Nanoparticles, for example, which are collections of atoms as small as a virus, can act as mini-antennas, and small disks of silicon can set off strange ‘modes’ of light that render the disks invisible.