In an exciting link up between high-tech industry and international universities, including Cardiff, Athens and Thessaloniki, the secrets of a two-thousand-year-old astronomical calculating device, the Antikythera Mechanism, are exposed for the first time with a unique 400kV microfocus Computed Tomography System.
Antikythera Mechanism Research Project
Nikon Metrology’s 400kV microfocus CT equipment has been used to probe the secrets of the ancient artefact, estimated to date from around 80 BC. Discovered in 1900 AD in a shipwreck in the Greek islands, the Antikythera Mechanism contains over 30 gear wheels and dials and the remains are covered in astronomical inscriptions. It may be a device to demonstrate the motion of the Sun, Moon and planets, or to calculate calendars or astrological events.
Although the Mechanism is no bigger than a shoe box, it is too priceless and unique to leave the National Archaeological Museum in Athens, so a major expedition in late 2005 brought an X-ray tomography machine, weighing over 7.5 tonnes, to examine the artefact in Greece.
Nikon Metrology’s imaging equipment has been instrumental in advancing our current understanding of the Mechanism. It was originally thought that the CT results would be vital in providing good images of the gear train, allowing researchers to obtain good teeth counts for the Mechanism's gears, and finally resolving any arguments regarding the relationships between the gears. The CT results have achieved this, and much more. The results have revealed many more details of the mechanism, including the so called 'pointer-follower' in Fragment B which allows the back dial to be interpreted as spiral dials, not circular dials as previously thought. The 3D CT images have also revealed the pin and slot mechanism that has allowed researchers to discover that the Mechanism models the first anomaly of the Moon's motion.
However the great surprise has been the ability of the CT results to show hidden inscriptions in many of the Fragments. In the case of Fragment G this is exemplary: Price (1974) notes that its inscription is “almost illegible’, reading only 180 characters. The CT images, viewed at various angles, enabled the research project to read 932 characters. Looking at the data with Nikon Metrology, academic principal investigator Professor Mike Edmunds commented, "The outstanding results obtained from Nikon Metrology’s 3-D x-rays are allowing us to make a definitive investigation of the Mechanism. I do not believe it will ever be possible to do better."
The latest results have been published in Nature which coincided with the Antikythera Mechanism Research Project's first major international conference in Athens:
Decoding the ancient Greek astronomical calculator known as the Antikythera mechanism
T. Freeth (1,2), Y. Bitsakis (3,5), X. Moussas (3), J. H. Seiradakis (4), A.Tselikas (5), E. Mankou (6), M. Zafeiropoulou (6), R. Hadland (7), D. Bate (7), A. Ramsey (7), M. Allen (7), A. Crawley (7), P. Hockley (7), T. Malzbender (8), D. Gelb (8), W.Ambrisco (9) & M. G. Edmunds (1)
School of Physics and Astronomy, Cardiff University, UK.
Images First Ltd, UK.
Department of Astrophysics, Astronomy and Mechanics, National & Kapodistrian University of Athens, Greece.
Department of Physics, Aristotle University of Thessaloniki, Greece.
Centre for History and Palaeography, National Bank of Greece Cultural Foundation, Greece.
National Archaeological Museum of Athens, Greece.
Nikon Metrology (X-Tek Systems Ltd, UK.)
Hewlett-Packard Laboratories, USA.
Foxhollow Technologies Inc., USA.
Letters, Nature, Vol 444, 30 November 2006.
BBC News Item
Ancient Moon 'Computer' revisited - The delicate workings at the heart of a 2,000-year-old analogue computer have been revealed by scientists.
New Scientist opinions editor, Jo Marchant describes in a new book the fascinating story of the Antikythera Mechanism, from its manufacture, to its loss at sea, its rediscovery 2000 years later, and the 100 year quest since then to decipher its mysteries.