The Lycurgus Cup, A Roman Wonder That Changes Color and Baffles Scientists
Ancient Nanotechnology
How a 4th-century glass cup shows the secrets of nanotechnology in roman times
Have you ever seen a glass cup that changes colour depending on the light source? If you think this is a modern invention, think again. The Lycurgus Cup, a 4th-century Roman glass cup, does exactly that. It appears jade green when lit from the front, but blood red when lit from behind. This stunning effect is not a trick of the eye, but a result of nanotechnology.
The Lycurgus Cup is made of a special type of glass, called dichroic glass, which contains tiny particles of gold and silver, less than one-thousandth the size of a grain of salt. These particles act as tiny antennas that interact with light in different ways, depending on the angle and wavelength. When light hits the cup from the front, the particles reflect the green part of the spectrum, while letting the red part pass through. When light hits the cup from behind, the opposite happens, and the cup appears red.
