Antikythera Mechanism Mystery: Secrets of the World’s Oldest Analog Computer Revealed Using Gravitational Wave Technology

A new technique has revealed new evidence about the world's oldest analog computer.

Ancient Mechanical Calculator

An ancient device dating back to the 2nd century B.C., was salvaged from divers in 1901 off a remote Greek island in the Aegean. The mysterious device is called the Antikythera mechanism, and that has long fascinated modern scientists and engineers since the discovery of remaining fragments.

Much of the mystery surrounding this device is due to its singular nature: the device being one of its kind as no other similar device from the time-rock period is known to exist. It was discovered in a highly eroded state, having spent about 2,000 years amidst the wreckage of a ship that sank near the Aegean Island of Antikythera.

This device, about the size of a shoe box, has an array of intricate mesh gears, dials, and plates that produced a model of the cosmos that fitted cycles of the sun, the moon, and the planets, as well as constellations. It also predicted eclipses and marked the timing of athletic games, such as the ancient Olympics.

X-ray images of the device's components, one identified to be its calendar rings, came out in 2020 with new features including a series of regularly spaced holes beneath the ring. Given its highly eroded state, the presence of rings could be discerned, although the number remained unclear.

Unveiling the Secrets of Antikythera Mechanism

In a recent study, a team of researchers worked out how many holes were likely contained within one of the mechanism's broken rings. The details of their study were discussed in the paper "An Improved Calendar Ring Hole-Count for the Antikythera Mechanism."

This paper questions fundamental assumptions about the mechanism of Antikythera that could revolutionize our understanding of its form and function. But rather than turning to the accepted tools of archaeology, the team came to their conclusion by drawing information from an unlikely source.

Graham Woan and Joseph Bayley from the University of Glasgow used a technology developed for the study of gravitational waves. They used statistical modeling techniques, which had been originally designed to look for ripples in spacetime.

The researchers fine-tuned the research by couching techniques adapted in analyzing LIGO gravitational wave data to study the calendar ring. This approach includes a Markov Chain Monte Carlo and nested sampling, and the results returned an affirmation of holes with precision of about ⅓ mm.

The researchers had initially suggested that there could have been about 347 to 467 holes along the calendar ring of the Antikythera mechanism. The exact number of holes was confirmed by applying Bayesian analysis and new techniques from gravitational wave research.

Woan and Bayley said the mechanism's calendar ring once held 354 holes. That is an important discovery because those 354 holes would correspond to a Greek lunar calendar, not the 365 holes of the Egyptian calendar. The latest analysis also found 354 holes to be hundreds of times more likely than the count at 360 previously considered by various researchers.

It also portrays the high accuracy of the emplacements of the holes in the gravitational wave technology, given the average radial variation of only 0.028 mm.