Reproduction of 2,100-year-old calculator deepens mystery

A new working model of the mysterious 2,000-year-old astronomical calculator, dubbed the Antikythera Device, has been unveiled, incorporating the most recent discoveries announced two years ago by an international team of researchers.

The new model was demonstrated by its creator, former museum curator Michael Wright, who had created an earlier model based on decades of study. He demonstrates how the more complete device works in a video originally created on the New Scientist Website. (It's part of an update story by Jo Marchant, author of Decoding the Heavens, an account not only of the device itself but also the century-old scientific quest to recover its meaning.)

The added details and precision of the new model are based on the breakthrough research by The Antikythera Mechanism Research Project, a joint effort by researchers from Greece and the United Kingdom. They were able to plumb the depths of the device, comprised of 81 separate pieces (including several fused together over time), and decipher many more of the inscriptions by using high-tech hardware and software from HP Laboratories and X-Tek Systems, a U.K.-based manufacturer of high-resolution X-ray inspection equipment. The 2006 slideshow on the device, and the technology used by the researcher to decipher it, is online. 

Though often dubbed the "first computer," the device doesn't meet the fundamental requirement of computing. One of the project members, Michael Edmunds, a professor in the School of Physics and Astronomy at Cardiff University in Wales, prefers the term "calculator." "It multiplies, divides and subtracts, but you can't program it," he says.

But it's a highly advanced calculator: the complexity of its gearing was not seen again until the rise of European clock-making in the Middle Ages, 1,000 years later.

About the size of a shoebox, the Antikythera Device is crammed with an astoundingly complex and precise arrangement of 27 fine-toothed bronze gears and dials, turned by a hand-operated knob on one side. On the front and back, dials and pointers show the relative positions of the sun and moon in the sky over periods of time (and possibly of the five then-known planets), a black-and-white ball showed the moon's changing phases, and inscriptions showed the times of rising and setting of stars.

On the back, two spiral dials tracked the relative positions of the sun and moon, and the dates of solar and lunar eclipses, and showed the dates of the Olympic games.

The ancient Greeks believed that celestial orbits were circular, instead of the elliptical ones we know them to be today. To account for the discrepancies in the moon's movements, the Greek astronomer Hipparchus developed a mathematical model superimposing the motions of overlapping circles, each with a different center. The Antikythera Device uses a "pin and slot" arrangement to exactly reproduce this anomalous motion, so it accurately represents the observed celestial motions and times.
Reflecting this complexity, the 2006 research team included astrophysicists, radio astronomers, mathematicians and philologists (philology is the study of ancient texts and original documents).