Lycurgus Cup – An Ancient Nanotech Marvel

By Anupum Pant

The concepts of modern nanotechnology must have been first seeded in the year 1959 by the renowned physicist Richard Feynman, but Romans were already doing it back in 300 AD (around 290-325 AD). About 1700 years back, utilizing the principles of Nanotechnology, Roman engineers had crafted a magnificent chalice – Lycurgus Cup (picture). Like the Prince Rupert’s drop, this is another glass marvel you should know about.

Side note: You can listen to the legendary lecture by Dr. Feynman on YouTube – There’s Plenty of Room at the Bottom, where he discusses the “possibility of synthesis via direct manipulation of atoms”, or Nanotechnology.

Lycurgus cup description

The Lycurgus cup was probably the first ever optical artificial [meta]material – Ruby Glass – engineered to have properties that may not be found in nature. Its unusual optical properties are something that makes it stand out.

Normally, the cup appears green, but if it is illuminated from the inside or lit up using a light placed behind it, it glows ruby-red; hence the name, ruby glass. This kind of glass is known as a Dichroic glass. Dichroic  literally means ”two colored” and is derived from the Greek words ”di” for two, and ”chroma” for color; in this case, the colors green and red.

The technology behind this cup baffled scientists for around 40 years (from 1950s to 1990s). It was only in 1990s that they figured out how it really worked. The goblet has been preserved well, and is presently at display in the British Museum.

Dichroic glass

Dichroic glasses do not use paints, dyes, or any coloring agents for the color. They are made using fine coatings on glass. The coatings themselves do not have a color, but rather they bend light to reflect colors like a prism does, to make rainbows.

These colors are visible due to the presence of very minute amounts of finely ground gold and silver particles in it. Romans could have included these powders unknowingly as contaminants or might have added them on purpose to achieve the very effect, we’ll never know.

Inspired by an age-old technology

NASA, in the 1950s, used a similar technology to fabricate a kind of glass that could selectively reflect light wavelengths. They achieved this by depositing a thin-film of metal on the glass.

With innumerable combinations of oxides, glass colors and patterns available, the possibilities to utilize this phenomenon for various useful purposes are endless.
The unusual properties of this cup have also inspired material scientists to create concepts for an invisibility cloak using modern nanofabrication technology. [Source]

I want to study interesting materials like these

If you think the Lycurgus cup, Wolverine’s claws and Aerogels (If you haven’t heard about it, you must definitely check this out!) are awesome. You can make a career in researching materials like these by making a foray into Materials Science and Engineering. Most good universities offer a course in it. It is a budding field, growing at a rapid pace, replete with real-world challenging conundrums waiting to be resolved.