A new analysis of the Antikythera Mechanism challenges a century-old assumption

The inspiration for the titular device in last year’s blockbuster, Indiana Jones and the Dial of Destiny, was an actual archaeological artifact: the Antikythera Mechanism, a 2,200-year-old bronze mechanical computer. He has no mystical time travel powers, but a device has it has been the subject of fierce scientific scrutiny for many decades and is believed to have been used to predict eclipses and calculate planetary positions.

A new paper published in The Horological Journal found evidence that the mechanism’s calendar ring was designed to track the lunar calendar based on statistical techniques drawn from physics, particularly the study of gravitational waves. This contradicts the century-old assumption among mechanism scientists that the calendar ring had 365 holes, so it is tracked by the solar calendar, but is consistent with the conclusions of the 2020 analysis.

“It’s a neat symmetry that we’ve adapted to the techniques we use to study the universe today to understand more about the mechanism that helped people observe the heavens nearly two millennia ago,” said co-author Graham Woan, an astrophysicist at the university. of Glasgow “We hope that our discovery of the Antikythera mechanism, although less supernaturally impressive than that made by Indiana Jones, will help to deepen our understanding of how this remarkable device was made and used by the Greeks.”

As previously reported, a Greek mushroom picker named Elias Stadiatis discovered the wreck of an ancient cargo ship off the coast of the island of Antikythera in Greece in 1900. He and other divers recovered all kinds of artifacts from the ship. A year later, an archaeologist named Valerios Stais was studying what he thought was a piece of rock pulled from a shipwreck when he noticed a gear embedded in it. It turned out to be an ancient mechanical device. The Antikythera Mechanism is now housed in the National Archaeological Museum of Athens.

In 1951, a British historian of science named Derek J. de Solla Price began investigating the theoretical workings of the device. Based on X-ray and gamma-ray images of the fragments, Price and physicist Charalambos Karakalos published a 70-page paper in the Transactions of the American Philosophical Society in 1959.. Based on these images, they hypothesized that the mechanism was used to calculate the motions of the stars and planets, making it the first known analog computer.

Michael Wright, then curator of mechanical engineering at the Science Museum in London, made headlines in 2002 with new, more detailed linear tomography X-ray images of the device. Wright’s closer analysis revealed a fixed central gear in the main wheel of the mechanism, around which other movable gears could turn. He concluded that the device was specifically designed to model “epicyclic” motion, in keeping with the ancient Greek notion that celestial bodies moved in circular patterns called epicycles. (This was before Copernicus, so the fixed point around which they moved was considered to be the Earth.)

In 2021, an interdisciplinary team at University College London (UCL) led by mechanical engineer Tony Freeth, Honorary Professor at University College London, presented a new computational model that reveals a dazzling display of the ancient Greek cosmos. The team’s efforts built on Wright’s work as part of the ongoing Antikythera Mechanism Research Project, which performed more advanced 3D X-ray imaging with help from X-Tek Systems in the UK and Hewlett-Packard, among others. These images revealed much more of the original Greek transcription and confirmed that it was an astronomical computer used to predict the positions of celestial bodies in the sky. It is likely that the Antikythera mechanism once had 37 gears, of which 30 survive, and had a scale on its front showing the solar cycle and the zodiac, along with pointers indicating the position of the Sun and Moon.