Saturday, May 17, 2014

The Antikythera Mechanism - an Ancient Analog Computer

The Antikythera mechanism
On May 17, 1902, Greek archaeologist Valerios Stais discovers the Antikythera mechanism, an ancient mechanical analog computer, designed to predict astronomical positions and eclipses.

The famous mechanism was discoverey in a shipwreck near the Greek island of Antikythera. In October 1900, a group of sponge divers discovered the wreck and retrieved a great number of artifacts dating back to the end of the second century BC, which included bronze and marble statues, pottery, glassware, jewelry, coins, and of course, the mechanism. All together, they were brought to the National Museum of Archaeology in Athens for research purposes. However, the mechanism itself stayed unnoticed for over two years. The big clot of corroded bronze and wood looked pretty inconspicuous to the museum staff and they decided that other pieces had a higher priority. It took two more years until archaeologist Valerios Stais found out that one of the pieces belonging to the mechanism had some kind of gear wheel embedded in it. The scientist immediately thought of an astronomical clock, but most of the archeologists examining the mechanism from then on believed it to be prochronistic due to its incredible complexity. Unfortunately for Stais, the investigations on the device were dropped. The physicist, historian of science, and information scientist Derek J. de Solla Price increased his interest in the mechanism in 1951. Along with the Greek nuclear physicist Charalampos Karakalos he took X-ray and gamma-ray images and published a very large scientific paper on their findings in the 1970s. It was quickly realized, how important the mechanism was and Cardiff University professor Michael Edmunds, who led a 2006 study of the mechanism, described the device as "more valuable than the Mona Lisa".
Antikythera Machine mechanical model
Image: Mogi Vicentini

Derek Price concluded that the device was an astronomical computer capable of predicting the positions of the sun and moon in the zodiac on any given date. A new analysis, though, suggests that the device was even more complex than the scientist thought and reinforces the evidence for his theory of an ancient Greek tradition of complex mechanical technology. Today, the device is often called the first analog computer. However, it is also assumed that the mechanism may have had predecessors during the Hellenistic Period that remained undiscovered. One of the things that astonished the experts the most was the high level of miniaturisation and overall complexity that was for example seen in 14th century astronomical clocks. Since research on the device progressed only slowly and needed decent funding, the Antikythera Mechanism Research Project was initiated in 2005. It is an international collaboration of academic researchers, which aims to completely reassess the function and significance of the Antikythera Mechanism. Recent findings of the project suggest that the concept for the mechanism originated in the colonies of Corinth, since some of the astronomical calculations seem to indicate observations that can be made only in Corinth area of ancient Greece. Also, a connection to the school of Archimedes is assumed, since Syracuse was a colony of Corinth and the home of the inventor, mathematician and engineer. But this is not the only theory regarding the device's origin. Some historians assume that it may have been built in the ancient Greek city of Pergamon.

It was found out that the mechanism was operated by turning a small hand crank which was linked via a crown gear to the largest gear. This allowed the setting of the date on the front dial and the calculation of the position of the Sun and Moon and other astronomical information was possible. It is known that the device has at least 30 gears, but on this day it is still argued whether the mechanism had indicators for all five of the planets known to the ancient Greeks. It is assumed that the gears were created from a blank bronze round using hand tools and with the help of X-ray images, the precise number of teeth and size of the gears within the located fragments could be determined and thus, the basic operation of the device was revealed. Another point that was highly discussed was the question whether the mechanism was based on the geocentric or even the heliocentric model. It was then found out that since the device's purpose was to position astronomical bodies with respect to the celestial sphere, in reference to the observer's position on the Earth, the device was based on the geocentric model.

In 2012, the Woods Hole Oceanographic Institution in the United States received permission from the Greek Government to conduct new dives around the deep shoals of Antikythera. The researchers hope to find other small pieces of the Antikythera mechanism on the sea floor as well as to locating and surveying the wrecks of other ships that foundered near the island.

At yovisto, you may be interested in a discussion about 'The Technology of the Antikythera Mechanism' at the Getty Museum.



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