The Hermit Poet

December 20, 2006

Older Than Babbage’s Machine – The Antikythera Mechanism

Filed under: General — Neil Aitken @ 10:07 am
While Charles M. Babbage’s invention of the Analytical Engine still marks the foundation of modern computer science, evidently there have been ancient computing devices (not quite programmable like Babbage’s machine) such as this one found on the Antikythera shipwreck, the remains of an ancient Roman vessel bearing Greek loot.  The mechanism evidently had 30 gears and 3 dials, could accurately represent what the sky looked like (configuration of the moon, sun, earth, other 5 planets) at any point in the past or future given a date.

A recent Washington Post article features the following details:

“We have gear trains from the 9th century in Baghdad used for simpler displays of the solar and lunar motions relative to one another — they use eight gears,” said Fran?ois Charette, a historian of science in Germany who wrote an editorial accompanying a new study of the mechanism two weeks ago in the journal Nature. “In this case, we have more than 30 gears. To see it on a computer animation makes it mind-boggling. There is no doubt it was a technological masterpiece.”

The device was probably built between 100 and 140 BC, and the understanding of astronomy it displays seems to have been based on knowledge developed by the Babylonians around 300-700 BC, said Mike Edmunds, a professor of astrophysics at Cardiff University in Britain. He led a research team that reconstructed what the gear mechanism would have looked like by using advanced three-dimensional-imaging technology. The group also decoded a number of the inscriptions.

The mechanism explores the relationship between lunar months — the time it takes for the moon to cycle through its phases, say, full moon to full moon — and calendar years. The gears had to be cut precisely to reflect this complex relationship; 19 calendar years equal 235 lunar months.

By turning the gear mechanism, which included what Edmunds called a beautiful system of epicyclic gears that factored in the elliptical orbit of the moon, a person could check what the sky would have looked like on a date in the past, or how it would appear in the future.

The mechanism was encased in a box with doors in front and back covered with inscriptions — a sort of instruction manual. Inside the front door were pointers indicating the date and the position of the sun, moon and zodiac, while opening the back door revealed the relationship between calendar years and lunar months, and a mechanism to predict eclipses.

Research continues on the device at the Antikythera Mechanism Research Project and has lead to at least one international conference (more scheduled no doubt).
You can also read more on the mechanism here.

Fascinating, eh?  Somewhat akin to the Voynich manuscript.

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