If one were to stumble upon the thought of ancient technology, it would be hard to think of anything as advanced as the Antikythera mechanism. This tiny device which has, several times, been claimed to be the world’s first analog computer ever built has vexed science experts since its recovery by divers off the Greek island of Antikythera in 1901. Picture essentially a shoebox contraption with gears and dials in a position to predict eclipses and positions of planets to unnerving levels of accuracy. While it’s an ancient mystery, now some of the techniques that were developed for studying gravitational waves have allowed a group of astronomers and physicists at Glasgow University to shed new light.
Anyone interested in ancient technology and in the latest scientific efforts will find this story a do-not-miss look at both. One ring—the calendar ring—of the Antikythera mechanism contains minute holes, very accurately placed, to meter the lunar calendar. Just how many of these holes remained a question: The artifact was incomplete, and is mysterious.
It wasn’t until 2020 that new X-ray images revealed a series of regularly spaced holes hidden beneath the broken calendar ring. Preliminary estimates were that the ring would have had between 347 and 367 holes. At this point, this would have been little more than an educated guess; the evidence was incomplete. Enter gravitational wave researchers, who saw an opportunity to bring their refined statistical methods to bear on cracking this ancient puzzle.
The challenge caught the attention of Professor Graham Woan, from the School of Physics & Astronomy at the University of Glasgow. “Towards the end of last year, a colleague pointed to me to data acquired by YouTuber Chris Budiselic, who was looking to make a replica of The Calendar Ring and was investigating ways to determine just how many holes it contained”, said Professor Woan in an announcement. “It struck me as an interesting problem and one that I thought I might be able to solve in a different way during the Christmas holidays, so I set about using some statistical techniques to answer the question.”
Woan used a technique called Bayesian analysis, which puts one’s uncertainty into a quantitative framework with incomplete data. He came up with a best estimate of 354 or 355 holes that would most likely have fitted into the calendar ring, in view of the position of the other surviving holes and the scattering of the remaining fragments from the ring. If the count is correct, it will exactly match with the lunar calendar, giving new evidence that the mechanism was used to track the years as indicated by the moon.
Meanwhile, Dr. Joseph Bayley of the same university used methods honed for the analysis of signals from what’s called LIGO—Laser Interferometer Gravitational-Wave Observatory gravitational wave detectors. These measure tiny spacetime ripples caused by massive astronomical events. Bayley looked very closely at the calendar ring using such methods as Markov Chain Monte Carlo and nested sampling. His results matched Woan’s, strongly indicating that the ring most likely had 354 or 355 holes with extraordinary accuracy.
“Previous work had indicated that the calendar ring was probably used to monitor the lunar calendar, but the dual techniques applied here have greatly increased the likelihood of that being the case”, said Bayley. “It gives me new respect for the Antikythera mechanism and all of the work and care that Greek craftspeople put into its manufacture. To gain this order of accuracy, the positioning of the holes would have required highly accurate measuring techniques, along with an incredibly steady hand to punch them.”
This was, on average, a radial variation with each hole of only 0.028mm—what one imagines is a fantastically impressive incidence of ancient Greek craftsmanship. Professor Woan said: “It’s a neat symmetry that we’ve adapted techniques we use to study the universe today to understand more about a mechanism that helped people keep track of the heavens nearly two millennia ago.”
Both researchers hope that their findings will enhance the understanding of how the Antikythera mechanism was made and used. “We hope our findings about the Antikythera mechanism less supernaturally spectacular than those made by Indiana Jones help to deepen our understanding of how this remarkable device was made and used by the Greeks,” said Woan.
It is in this exciting confluence of ancient history and modern science that more than the resolution of one anachronism happens—it epitomizes the extraordinary precision and skill lying behind ancient Greek craftsmanship. Next time you gaze up toward the sky or read some newly detected gravitational wave, remember that with the same scientific curiosity and methodologies, ancient riddles are solved, just as much as modern mysteries are.
