The Roman Cup, made 1,600 years ago, could be an example of nanotechnology, experts say. The mysterious Lycurgus Cup, made of dichroic glass, is able to change color from green to red, depending on the lighting.
To create the bowl, which is on display at the British Museum in London, the technology used what is now called nanotechnology - the controlled manipulation of materials at the atomic and molecular levels. These technologies, according to scientists, can be used in various fields - from diagnosing diseases to detecting bombs at airports.
Scientists managed to unravel the secret of changing the color of the bowl only in 1990, after years of fruitless attempts. After examining the shards of glass under a microscope, scientists found that the Romans impregnated it with particles of silver and gold, which they crushed into extremely tiny particles - about 50 nanometers in diameter - a thousand times smaller than a crystal of salt.
The precise metal ratios and such meticulous grinding led experts to conclude that the Romans were the pioneers of nanotechnology because they really knew what they were doing.
Archaeologist Ian Freestone of University College London, who has researched the bowl and its unusual optical properties, calls the creation of the goblet an "amazing feat." The cup changes color depending on which side the observer is looking at.
The bowl appears to have been used in exceptional cases for drinking, and experts say its color changed depending on the beverage with which it was filled.
Liu Gang Logan, an engineer and nanotechnology expert at the University of Illinois at Urbana-Champaign, said: "The Romans knew how to make and use nanoparticles to create works of art."
Of course, scientists couldn't examine a one-of-a-kind goblet and fill it with various liquids. Therefore, they were forced to recreate the Lycurgus Cup by applying microscopic particles of gold and silver to the glass. The researchers then experimented with different liquids to find out how its color would change. A new goblet filled with water, scientists have found, glows blue, and when filled with oil - bright red.
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While the experiment could help archaeologists understand how the bowl works, it could also help scientists develop devices to detect pathogens in saliva or urine, or to identify liquids that terrorists might try to transport on airplanes.