The Antikythera Mechanism: The 'computer' from Ancient Greece

Replica of the Anitikythera Mechanism on display
Image: imagIN.gr photography / Shutterstock.com

Discovered by accident in 1901, the Antikythera Mechanism is an ancient Greek device that’s befuddled historians and researchers for over a century. Modern technology has now begun to unlock the secrets of this incredible artefact, leading to the belief it could be the world’s earliest known analogue computer.

The small Greek island of Antikythera lies at the edge of the Aegean Sea between the mainland and Crete. In 1900, a Greek sponge diver claimed to have found a shipwreck some 150 feet beneath the waves. Further dives confirmed his discovery, and the wreck was thought to be that of an ancient Roman vessel that sunk sometime during the 1st century BC. Although its exact route is unknown, historians have suggested the ship could have perhaps departed from the busy ancient trading port of Rhodes and headed towards Rome.

Over the following year, divers worked with archaeologists to bring a multitude of artefacts to the surface. The recovery operation was far from simple and led to the death of one diver with two more paralysed from the bends.

Their efforts, however, were not in vain. A treasure trove of marble sculptures, coins, a bronze statue and lyre, glasswork, and pottery were discovered. Amongst the hoard was a lump of corroded bronze and wood. Since the other objects recovered from the wreck were more obviously recognisable as finds of importance, this strange lump was stored away at the National Museum of Archaeology in Athens and all but forgotten about.

The shipwreck was not dived again until the 1970s, when famous French oceanographer Jacques Cousteau worked with archaeologists to recover a further 300 artefacts, including ceramic jars, jewellery, and even human remains.

However, it took over 70 years from the shipwreck’s original discovery for the first publication on the Antikythera Mechanism to be made, although no conclusions were brought about its purpose or how it worked. Only until relatively recently have the secrets of this mystery box begun to be decoded. Modern X-ray machines, including a computed tomography imager, have been used to reveal some fascinating insights into the history and purpose of this device.

Recovered fragments of the mechanism total 82 separate pieces, believed to be around a third of the size of the original structure. The scans revealed previously unseen Greek inscriptions and symbols dotted around the pieces, as well as at least 35 bronze gears, 19 shafts and axles, and seven pointers, hinting at a device of unparalleled complexity for the ancient world.

It was soon apparent the Antikythera Mechanism was some kind of device used to calculate dates and predict astronomical events, making it the oldest known example of an analogue computer.

Whilst many attempts have been made to recreate the device to demonstrate how it may have functioned, all are still entirely speculative. However, the general belief is the device sat within a wooden case the size of a shoebox. Powered by a hand-crank, the intricately linked gears all moved in unison. The gears rotated a series of dials and scales inscribed with Greek zodiac signs and Egyptian calendar days and months.

With astonishing accuracy, the device could predict the position of the sun, moon, and planets (only the five known in the ancient Greek world) in the sky. A small rotating sphere displayed the phases of the moon whilst pointers on the back of the device tracked both solar and lunar eclipses. It could also determine the dates of the ancient Olympic Games held every four years and even be set up to take into account leap years. Astonishingly, it also came with basic instructions with an inscription on the back bronze panel detailing some of the parts of the device.

Believed to have been built sometime around the late 2nd century BC and early 1st century BC, the Antikythera Mechanism pre-dates the invention of mechanical clocks in medieval Europe by over a millennium. The gears found in the mechanism, with their triangular teeth, are said to be the first in the history of mankind to resemble the shape and functionality of modern gears.

A 2021 paper written on the mechanism called A Model of the Cosmos in the ancient Greek Antikythera Mechanism states: ‘It is the first known device that mechanized the predictions of scientific theories and it could have automated many of the calculations needed for its own design - the first steps to the mechanization of mathematics and science. Our work reveals the Antikythera Mechanism as a beautiful conception, translated by superb engineering into a device of genius. It challenges all our preconceptions about the technological capabilities of the ancient Greeks.’

As for who used these ancient devices, no one knows for sure. Various suggestions have been put forward including temples, schools, and the wealthy. It’s also unknown as to what end the device was used, was it for practical purposes or purely educational?

The question of where it was made also remains unanswered. The Greek Island of Rhodes, which was at the time a busy trading port and a centre of astronomy and mechanical engineering, is a favoured location by researchers for the birthplace of the device. Rhodes was also home to Hipparchus, a 2nd century BC astronomer and father of trigonometry, who worked and taught on the island. Many believe he had a hand in the creation of the Antikythera Mechanism.

Whilst the mechanism has been called the world’s oldest analogue computer, the sophistication of the device has led researchers to conclude that it cannot be the first of its kind, but rather the only surviving one of a sequence. Written evidence supports this theory with references to such devices mentioned in Greco-Roman literature, including the works of Roman scholar Cicero.

The shipwreck from which the mechanism was originally discovered remains a hotspot of archaeological activity with new artefacts coming to the surface regularly. Investigations are now being carried out into whether a second ship lies close by. Who knows, a predecessor to the Antikythera Mechanism may well be uncovered.