More on the age of the Antikythera Mechanism

Remember when I reported that new analysis of the Antikythera Mechanism suggests the astronomical device is older than archaeologists had assumed?  James Evans, a physicist and science historian at the University of Puget Sound in Tacoma and part of an international group working to crack the puzzle of the device’s origins and purpose, recently added a new twist with an analysis that suggests it dates to 205 BC; as much as a century earlier than previously believed.


Pieces of the Antikythera Mechanism are photographed at the Archaeological
Museum in Athens. The device consisted of a series of intricate, interlocking
 gears designed to predict eclipses and calculate the positions of the sun,
 moon and planets as they swept across the vault of the sky
 [Credit: Louisa Gouliamaki/AFP/Getty Images]


If he’s right, that makes it more likely the Antikythera Mechanism was inspired by the work of the legendary Hellenic mathematician Archimedes. It would also mean the device was built at time when scientific traditions from multiple cultures were coming together to create a new view of the cosmos. According to Evans, pushing the date back is exciting.

“We think it would be highly significant because it could change the picture of the development of Greek astronomy.”

Greek sponge divers stumbled across the wreck of the Roman galley in 1900, after being blown off course and taking shelter in the lee of the tiny island north of Krete. Scientists think the ship was a merchant vessel that foundered around 60 BC. Archaeologists eventually identified more than 80 corroded fragments believed to be part of the Antikythera Mechanism, including the shoebox-sized piece with dials and gears clearly visible on the surface. Studies revealed at least 30 interlocking gears, and researchers believe the device held at least two dozen more. The assembly was housed in a wooden box and operated by a hand crank. Elaborate dials traced the movement of heavenly bodies, while ingenious gearing mimicked the fluctuating speeds at which the moon crosses the night sky, even though the Greeks had no understanding of the elliptical orbit responsible for the effect.

One dial plotted the four-year cycle of Olympic Games. Another predicted the timing of solar and lunar eclipses, apparently down to the hour. That was the dial Evans and Christián Carman, of the University of Quilmes, Argentina, focused on for their new analysis, published in the Archive for History of Exact Science.

Based on the style of Greek lettering on the Antikythera Mechanism, previous estimates of its construction date ranged between 150 to 100 B.C. But Evans and Carman took an astronomical approach, comparing eclipse dates on the mechanism to Babylonian eclipse records and a NASA eclipse catalog. They concluded that the 'start date' for the eclipse predictor was 205 BC. That doesn’t prove the device was built then, but Evans thinks it was.

“For us, it seems most likely that it was built close to the period for which it would have worked best."

Science historian Alexander Jones, who was not involved with the analysis, called it a really remarkable piece of work. Evans and Carman clearly establish the oldest possible age for the device, said Jones, of New York University’s Institute for the Study of the Ancient World. But he’s still not convinced it was actually manufactured that long ago. It’s possible that 205 B.C. was a historic date, chosen by the maker as the starting point for his dial, Jones pointed out. Evans agrees.

“People should be leery of trying to associate it with any one particular person, but you would have to think that whoever built this must at least have made use of what Archimedes had done, or came out of a tradition that started with Archimedes.”

If the date holds up, it would also mean that the device was built before the invention of trigonometry, a branch of mathematics long linked to the golden era of Greek astronomy. According to Evans:

“I think that would make it much more interesting, because it would come from a more formative period of Greek astronomy.”

Future revelations about the device may hinge on the discovery of additional fragments. A new series of underwater excavations started last year and will resume in the spring. I will keep you informed.