Scientists Decode Ancient Astral Computer

By Ian Sample in London

A MYSTERIOUS device salvaged from an ancient Roman shipwreck has astounded scientists who have finally unlocked its secrets. After a century of study, the 2100-year-old device, known as the Antikythera Mechanism, has been shown to be a complex and uncannily accurate astronomical computer. Recovered in 82 highly corroded fragments, it could predict the positions of the sun and planets, show the location of the moon and even forecast eclipses.
Experts believe it to be the earliest-known device to use gear wheels and by far the most sophisticated object to be found from the ancient and medieval periods. "This device is extraordinary, the only thing of its kind," said Mike Edmunds, a physicist at Cardiff University, in Wales. "The astronomy is exactly right … In terms of historic and scarcity value, I have to regard this mechanism as being more valuable than the Mona Lisa." It was lost among cargo in 65BC, when the ship carrying it sank in 42 metres of water off the Greek island of Antikythera.
In 1900 a sponge diver discovered the wreck. The device came to light when an archaeologist working on recovered objects noticed a lump of rock had a gear wheel embedded in it. Closer inspection of material brought up from the ship revealed gear wheels, dials, clock-like hands and a wooden and bronze casing bearing ancient Greek inscriptions.
Since its discovery, scientists have been trying to reconstruct the device. Using computer X-ray tomography, which makes images of selected layers, and high-resolution surface scanning, a team led by Professor Edmunds and Tony Freeth peered inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered its outer casing. Detailed imaging of the mechanism suggests it dates to between 150 and 100BC and had 37 gear wheels enabling it to follow the movements of the moon and the sun through the zodiac, predict eclipses and even re-create the irregular orbit of the moon.
The motion, known as the first lunar anomaly, was developed by the astronomer Hipparcus of Rhodes in the 2nd century BC, and he may have been consulted in the machine's construction, the scientists speculate. Remarkably, scans showed the device uses a differential gear, which was previously believed to have been invented in the 16th century. The level of miniaturisation and complexity of its parts is comparable to that of 18th-century clocks.
Some researchers believe the machine might have been among treasure looted from Rhodes that was en route to Rome for a celebration staged by Julius Caesar. One of the remaining mysteries is why the Greek technology invented for the machine seemed to disappear. No other civilisation is believed to have created anything as complex for another 1000 years.
Bronze was often recycled in the period the device was made, so many artefacts from that time were melted down and erased from the archaeological record. The fateful sinking of the ship carrying the Antikythera Mechanism may have inadvertently preserved it.