Incognita: The Antikythera Mechanism

The over 2000 year old gear machine from Antikythera is considered one of the greatest puzzles of antiquity and is often described as the “first computer” of mankind. The Antikythera Mechanism was discovered by chance in April of 1900, in a shipwreck near the small Greek island of Antikythera. At the time no one knew how special this perplexing device of remarkable engineering was. Only in the past decades has it undergone serious study.

The Antikythera mechanism is one of the world’s oldest known geared devices. It has puzzled and intrigued historians of science and technology since its discovery. The device seemed to have a range of interlocking gears made of bronze and a hand crank to give a turning movement to the geared mechanism, plus a display that showed information about the moon, sun and planets against a background of stars.

The device is incomplete and therefore no longer functional. The 82 fragments preserved are now in the National Archaeological Museum in Athens. The discovery of the Antikythera Mechanism was surprising in that a technically advanced device like this and the technique and method of manufacture contained in it were extremely sophisticated. The mechanism was built circa 200 BC, and, with over thirty gears hidden behind its dials, it is easily the most advanced technological artifact of the pre-Christian period. The surprising fact is that before the discovery of this device the existence of a complex gear apparatus was not only not known, but from a time long assumed to be before the beginning of technical development. The device uses a differential gear, previously believed to have been invented in the middle ages. The remarkable level of miniaturization and complexity of its parts is comparable to that of 18th century clocks.

Recent research on the mystery of the Antikythera Mechanism has recently been presented in the premises of the Aikaterini Laskaridi Foundation. The members of the research team, the physicists Yannis Bitsakis and Xenofon Moussas, have confirmed that according to the new data the mechanism of Antikythera is the oldest computer in the world.

By using different sized gears, this ancient machine was able to represent the motion of the planets with great precision. To use the instrument, one would simply enter a date using a crank. After the mechanical computations were made by the device, a wealth of information would appear: the positions of the Sun, Moon, planets, and stars, the lunar phase, the dates of upcoming solar eclipses, the speed of the Moon through the sky, and even the dates of the Olympic games. Perhaps most impressively, the mechanism’s calendar dial could compensate for the extra quarter-day in the astronomical year by turning the scale back one day every four years.

The mechanism is now considered to have been an analog computer designed to allow the operator to “mechanically” predict the future or past positions of the sun, moon, and probably some of the known planets. The makers of the Antikythera Mechanism seem to have accepted that the Sun was at the centre of an orbital system, – anticipating Copernicus and Galileo by some fifteen hundred years.

The Greek sciences are often thought of as only purely philosophical in nature with no practical utility. However in the Hellenistic age, at the end of which the Antikythera Mechanism originated, was marked by considerable technical creativity, although inventors such as Archimedes or Heron of Alexandria probably never actually constructed many of their inventions.

It is not the use which makes the mechanism of Antikythera unique, but its existence as a device made of gears, which could accurately model the already well-known relative movements between sun, moon and earth. Toothed gears, especially so many small ones, did not seem to exist in the Hellenistic age. What is astonishing is how many astronomical findings have been common knowledge, so that they could have a craftsman incorporate it into a product such as the Antikythera Mechanism and a user of this product could retrieve it with ease.

While the Antikythera Mechanism is the only known artifact of its kind, its precise engineering and the fact that similar instruments were described in contemporary writing lend strong support to the notion that it was not unique. Although its builder’s identity and what it was doing aboard a ship remain mysterious, scientists have worked for a century to piece together the mechanism’s history.