http://www.nytimes.com/2006/11/30/science/30compute.html?_r=1&oref=slogin
Early Astronomical ‘Computer’ Found to Be Technically Complex
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Published: November 30, 2006
A computer in antiquity would seem to be an anachronism, like Athena ordering takeout on her cellphone.
Decoding the Ancient Greek Astronomical Calculator Known as the Antikythera Mechanism (Nature)
But a century ago, pieces of a strange mechanism with bronze gears and dials were recovered from an ancient shipwreck off the coast of Greece. Historians of science concluded that this was an instrument that calculated and illustrated astronomical information, particularly phases of the Moon and planetary motions, in the second century B.C.
The instrument, the Antikythera Mechanism, sometimes called the world’s first computer, has now been examined with the latest in high-resolution imaging systems and three-dimensional X-ray tomography. A team of British, Greek and American researchers deciphered inscriptions and reconstructed the gear functions, revealing “an unexpected degree of technical sophistication for the period,” it said.
The researchers, led by the mathematician and filmmaker Tony Freeth and the astronomer Mike G. Edmunds, both of the University of Cardiff, Wales, are reporting their results today in the journal Nature.
They said their findings showed that the inscriptions related to lunar-solar motions, and the gears were a representation of the irregularities of the Moon’s orbital course, as theorized by the astronomer Hipparchos. They established the date of the mechanism at 150-100 B.C.
The Roman ship carrying the artifacts sank off the island of Antikythera about 65 B.C. Some evidence suggests it had sailed from Rhodes. The researchers said that Hipparchos, who lived on Rhodes, might have had a hand in designing the device.
In another Nature article, a scholar not involved in the research, François Charette of the University of Munich museum, in Germany, said the new interpretation of the mechanism “is highly seductive and convincing in all of its details.” It is not the last word, he said, “but it does provide a new standard, and a wealth of fresh data, for future research.”
Technology historians say the instrument is technically more complex than any known for at least a millennium afterward. Earlier examinations of the instrument, mainly in the 1970s by Derek J. de Solla Price, a Yale historian who died in 1983, led to similar findings, but they were generally disputed or ignored.
The hand-operated mechanism, presumably used in preparing calendars for planting and harvesting and fixing religious festivals, had at least 30, possibly 37, hand-cut bronze gear-wheels, the researchers said. A pin-and-slot device connecting two gear-wheels induced variations in the representation of lunar motions according to the Hipparchos model of the Moon’s elliptical orbit around Earth.
The numbers of teeth in the gears dictated the functions of the mechanism. The 53-tooth count of certain gears, the team said, was “powerful confirmation of our proposed model of Hipparchos’ lunar theory.” The detailed imaging revealed more than twice the inscriptions recognized earlier. Some of these appeared to relate to planetary and lunar motions. Perhaps, the team said, the mechanism also had gearings to predict the positions of known planets.
Dr. Charette noted that more than 1,000 years elapsed before instruments of such complexity are known to have re-emerged. A few artifacts and some Arabic texts suggest that simpler geared calendrical devices had existed, particularly in Baghdad around A.D. 900.
It seems clear, he said, that “much of the mind-boggling technological sophistication available in some parts of the Hellenistic and Greco-Roman world was simply not transmitted further.”
“The gear-wheel, in this case,” he added, “had to be reinvented.”
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source: http://www.nature.com/nature/journal/v444/n7119/abs/nature05357.html
Nature 444, 587-591 (30 November 2006) | doi:10.1038/nature05357; Received 10 August 2006; Accepted 17 October 2006
Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism
T. Freeth1,2, Y. Bitsakis3,5, X. Moussas3, J. H. Seiradakis4, A. Tselikas5, H. Mangou6, M. Zafeiropoulou6, R. Hadland7, D. Bate7, A. Ramsey7, M. Allen7, A. Crawley7, P. Hockley7, T. Malzbender8, D. Gelb8, W. Ambrisco9 and M. G. Edmunds1
Correspondence to: M. G. Edmunds1 Correspondence and requests for materials should be addressed to M.G.E. (Email: mge@astro.cf.ac.uk).
The Antikythera Mechanism is a unique Greek geared device, constructed around the end of the second century bc. It is known1, 2, 3, 4, 5, 6, 7, 8, 9 that it calculated and displayed celestial information, particularly cycles such as the phases of the moon and a luni-solar calendar. Calendars were important to ancient societies10 for timing agricultural activity and fixing religious festivals. Eclipses and planetary motions were often interpreted as omens, while the calm regularity of the astronomical cycles must have been philosophically attractive in an uncertain and violent world. Named after its place of discovery in 1901 in a Roman shipwreck, the Antikythera Mechanism is technically more complex than any known device for at least a millennium afterwards. Its specific functions have remained controversial11, 12, 13, 14 because its gears and the inscriptions upon its faces are only fragmentary. Here we report surface imaging and high-resolution X-ray tomography of the surviving fragments, enabling us to reconstruct the gear function and double the number of deciphered inscriptions. The mechanism predicted lunar and solar eclipses on the basis of Babylonian arithmetic-progression cycles. The inscriptions support suggestions of mechanical display of planetary positions9, 14, 15, now lost. In the second century bc, Hipparchos developed a theory to explain the irregularities of the Moon's motion across the sky caused by its elliptic orbit. We find a mechanical realization of this theory in the gearing of the mechanism, revealing an unexpected degree of technical sophistication for the period.