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 color depending on the direction of the light falling upon it. The glass chalice had baffled scientists ever since its acquisition 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 nanometers in diameter, less than one-thousandth the size of a grain of table salt.
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—“an amazing feat,” according to archaeologist Ian Freestone of University College London. When hit with light, electrons belonging to the metal flecks vibrate in ways that alter the color depending on the observer’s position.
Now it seems that this technology, once used by the Romans to produce beautiful art, may have many more applications—the super-sensitive technology might help diagnose human disease or pinpoint biohazards at security checkpoints. Gang Logan Liu is an engineer at the University of Illinois at Urbana-Champaign who has long focused on using nanotechnology to diagnose disease. He and his colleagues realized that this effect offered untapped potential.
They conducted a study 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, or salt, the colors changed. The prototype was 100 times more sensitive to altered levels of salt in solution than current commercial sensors using similar techniques. It may one day make its way into handheld devices for detecting pathogens in samples of saliva or urine, or for thwarting terrorists trying to carry dangerous liquids onto airplanes.
This is not the first time that Roman technology has exceeded that of our modern day. Scientists studying the composition of Roman concrete that had been submerged under the Mediterranean Sea for the last 2,000 years discovered that it was superior to 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. Isn’t it ironic that scientists now turn to the works of our so-called “primitive” ancestors for help in developing new technologies?
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