Tony Freeth
Scientists have long struggled to solve the mystery of the lever system at the forefront of the so-called Antikythera mechanism – a fragmentary ancient Greek astronomical calculator, perhaps the earliest example of a device. Now an interdisciplinary team at University College London (UCL) has devised a computational model that reveals a dazzling display of the ancient Greek cosmos, according to a new article published in the journal Scientific Reports. The team is currently building a replica mechanism, which moves gears and all, using modern machinery. You can watch an extended 11-minute video about the project here (inclusion currently disabled).
“We are the first model to match all the physical evidence and match the descriptions in the scientific inscriptions engraved on the mechanism itself,” said lead author Tony Freeth, a mechanical engineer at UCL. ‘The sun, moon and planets are impressively displayed power tower of ancient Greek brilliance. ‘
“We believe our reconstruction matches all the evidence that scientists have obtained so far from the existing remains,” co-author Adam Wojcik, a materials scientist at UCL, told the Guardian.
The hand-operated Antikythera mechanism has a long history. In 1900, a Greek sponge diver named Elias Stadiatis discovered the wreck of an old cargo ship off the coast of Antikythera Island in Greece. He and other divers got all sorts of artifacts from the ship. A year later, an archaeologist named Valerios Stais studied what he thought was just a piece of rock recovered from the shipwreck, but he noticed that there was a gear in it. It turns out to be an old mechanical device. The Antikythera mechanism is now housed in the National Archaeological Museum of Athens.
The 82 remaining fragments of the device were originally housed in a wooden box about the size of a shoebox, with outer buttons on the outside, with a complex assembly of gears. The largest piece is known as Fragment A, with bearings, pillars and a block. Another piece, Fragment D, has a disc, a tooth with 63 teeth and a plate. The existence of the mechanism provides strong evidence that such technology already existed in 150-100 BC, but the knowledge was subsequently lost. Similar machines of equal complexity only reappeared in the 18th century. While found on a Roman cargo ship, historians believe it was Greek, possibly from the island of Rhodes, known for its impressive mechanical engineering.
It took decades to clean the device, and in 1951 a British historian named Derek J. de Solla Price began investigating the theoretical operation of the device. Based on X-rays and gamma-ray images of the fragments, Price and physicist Charalampos Karakalos published a 70-page paper in 1959 in the Transactions of the American Philosophical Society.. Based on the images, Price assumed that the mechanism was used to calculate the motions of stars and planets – making it the first analog computer.
In 2002, Michael Wright, then curator of mechanical engineering at the Science Museum in London, made headlines with new, more detailed X-rays of the device taken via linear tomography – meaning that only features at a particular level come into focus. so that it can be further investigated and the exact location of each gear can be fixed. Wright’s further analysis showed a fixed central gear in the main wheel of the mechanism, to which other moving gears can turn. He concluded that the device was specifically designed to model ‘epicyclic’ motions, consistent with the ancient Greek notion that celestial bodies move in circular patterns called epicycles. (The fixed point around which they move is generally considered the earth, until Copernicus realizes that it is in fact the sun.)