Last year, Graham Woan knew how he wanted to spend his Christmas break: trying to solve the 2,200-year-old mystery of the world’s oldest known “computer.”
Known as the Antikythera mechanism, the bronze device is a mechanical computer with interlocking gears. In the second century BCE, a user would have used its rings and equal holes to depict upcoming celestial events, such as eclipses.
But how many of those equal holes existed has been a mystery and holds the key to determining exactly how the computer worked.
YouTuber Chris Budiselic has long been fascinated by the mechanism and started creating his own version seven years ago, but wasn’t sure how many holes to include.
Based on some of Budisic’s published research, University of Glasgow astronomers, including Woan, turned to statistical modeling techniques to find the answer.
“It struck me as an interesting problem that I thought I could solve in a different way over the Christmas holidays, so I decided to use some statistical techniques to answer the question,” Woan said in a university press release. .
Based on the number of holes, the researchers found, the device follows a lunar calendar rather than an Egyptian one, as some previous research had suggested.
A shipwreck full of ancient treasures
The Antikythera Mechanism is broken and corroded, making it difficult to know exactly how it worked. Associated Press/Petros Giannakouris
The Antikythera Mechanism is just one intriguing discovery from a 2,000-year-old shipwreck that divers first discovered in 1900. Divers waiting out a storm found the remains near the Greek island of Antikythera.
According to the Woods Hole Oceanographic Institution, excavations have uncovered three life-size marble horse statues, coins, jewelry and other treasures. But the Antikythera Mechanism is perhaps the most unique discovery of all.
It’s about the size of a shoebox, broken into six pieces and weathered from its time underwater. The mechanism is so sophisticated that some thought it must have been a modern device that got mixed up with the ancient artifacts, according to Derek John de Solla Price. He helped discover the device’s function in the 1970s.
X-ray images from 2005 gave researchers new details about the device. And in 2020, Budiselic and his colleagues used the images to measure the positions of the holes and proposed that the mechanism had between 347 and 367 holes. If it had closer to 350 holes, it would have followed the lunar calendar. If there were 365, it would be modeled after the Egyptian calendar.
But it was difficult to find an exact number due to the reduced state of the device.
After learning about Budiselic’s research, Woan first used Bayesian analysis, calculating different probabilities of the total number of holes based on the position and number of holes in the remaining bronze pieces. He learned that it was hundreds of times more likely that the device would have 354 holes than 360 holes.
Woan’s colleague Joseph Bayley followed up on the research by modifying techniques used to study gravitational waves, which are ripples in space-time. His results agreed with Woan’s; there were likely 354 or 355 holes in the ring.
In other words, there is a much higher probability that the mechanism was tracking the Greek lunar year rather than the Egyptian one. He was able to calculate the positions of the planets with remarkable accuracy for his time.
The find reinforces the impressive craftsmanship and knowledge required to create the device. “The accuracy of hole positioning would require very precise measuring techniques and an incredibly steady hand to hit them,” Bayley said in the press release.
Both have published their research in the Horological Journal.