The Lycurgus Cup, as it is known due to its depiction of a scene involving King Lycurgus of Thrace, is a 1,600-year-old jade green Roman chalice that changes colour depending on the direction of the light upon it.
It baffled scientists ever since the glass chalice was acquired by the British Museum in the 1950s. They could not work out why the cup appeared jade green when lit from the front, but blood red when lit from behind.
The mystery was solved in 1990, when researchers in England scrutinized broken fragments under a microscope and discovered that the Roman artisans were nanotechnology pioneers:
They had impregnated the glass with particles of silver and gold, ground down until they were as small as 50 nanometres in diameter, less than one-thousandth the size of a grain of table salt.
The Lycurgus Cup
The work was so precise that there is no way that the resulting effect was an accident. In fact, the exact mixture of the previous metals suggests that the Romans had perfected the use of nanoparticles. When hit with light, electrons belonging to the metal flecks vibrate in ways that alter the colour depending on the observer’s position.
The super-sensitive technology used by the Romans might help diagnose human disease or pinpoint biohazards at security checkpoints. Gang Logan Liu, engineer at the University of Illinois at Urbana-Champaign, and his colleagues, conducted a study last year in which they created a plastic plate filled with gold or silver nanoparticles, essentially creating an array that was equivalent to the Lycurgus Cup.
When they applied different solutions to the plate, such as water, oil, sugar and salt, the colours changed. The prototype was 100 times more sensitive to altered levels of salt in solution than current commercial sensors using similar techniques.
It’s not the first time Roman technology has been studied. Scientists studying the composition of Roman concrete, submerged under the Mediterranean Sea for the last 2,000 years, discovered that it was superior to the modern-day concrete in terms of durability and being less environmentally damaging.
The knowledge gained is now being used to improve the concrete we use today.
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