The Lycurgus Cup, a 1600-year-old Roman glass goblet in the British Museum in London, is one of the earliest known examples of the use of nanotechnology in human history.
Nanotechnology is actually a compound word made up of the words nano and technology. To make any material, we need to connect atoms together. “Nano” means “one in a billion” and objects that appear on the nanoscale are roughly a billion times smaller than us. Nanotechnology is the general name for the technology created using these nanoscale materials. In other words, nanotechnology is the control of matter at the atomic, molecular and supramolecular level.
The mythological scenes on the cup depict the death of King Lycurgus of Edonia in Thrace at the hands of Dionysus and his followers. The Lycurgus Cup first appeared in print media in 1845. The process is unclear about its earlier history. It is thought to have been owned by the Rothschild family. Until 1950, no detailed study of the cup was carried out. The British Museum acquired the cup from Lord Rothschild in 1958, and since then it has been studied in detail.
Why is the Lycurgus Cup Special?
What makes the cup so special is actually an optical illusion. When the cup is illuminated from the outside with light, it appears opaque green, but when the light shines from the inside, it appears translucent red. This color change has puzzled scientists for years. For a while there was even some debate about whether the cup was really glass, as it seemed impossible to create such an effect with the technical know-how of ancient glasswork.
But finally, in the 1990s, researchers revealed that Roman glassmakers used nanomaterials to create this unique effect. In other words, even though these glassmakers didn’t know the mechanism behind the effect, they manipulated the materials through sheer experimentation, and perhaps developed the first known example of nanotechnology in the 4th century.
Of course, as you may have guessed, the researchers initially thought that these particles were accidentally mixed into the glass. However, later studies revealed that the nanoparticle residues found in the glass were added on purpose, not by accident. Before the gold and silver were added to the glass, they had been ground and shaped into certain forms.
The property of some substances to take on different colors in the direction of observation is called dichroism. In the 6th and 15th centuries, the vibrant stained glass windows in European cathedrals owed their rich colors to nanoparticles of gold chloride and other metal oxides and chlorides. So in fact, long before the term nanotechnology was coined, medieval artisans used gold and silver nanoparticles to color glass panels as early as the 10th century. However, the Lycurgus Cup dates back much earlier than that.
How was the Lycurgus Cup made?
The explanation for this phenomenon was only obtained in 1990 after scientists analyzed the cup using an atomic force microscope. As a result of the investigations, it was found that this color change in the cup was the result of 66.2% silver, 31.2% gold and 2.6% copper nanoparticles present in the glass. These particles are about 50 nanometers in size. In other words, they are about 100 times smaller than the thickness of a human hair. The size and 12-sided shape of these particles cause light to reflect differently.
The electrons of silver and gold nanoparticles vibrate when exposed to different wavelengths of white light. The electrons then re-emit this light at the same color wavelength. The observed red color is the result of light absorption by the gold particles. The green color comes from silver particles. The researchers also think that this glass can change color depending on the type of liquid poured into it. As a result, the Lycurgus cup is considered one of the oldest synthetic nanocomposites.
The reason nanotechnology is the talk of the town today is that we now have the tools and microscopes to directly manipulate structures of this scale, enabling us to create much larger arrays of nanostructures. Yet we see that the creators of this magnificent chalice certainly seemed to know exactly what they were doing. It was only in the 1990s that we were able to understand this technology.
