New theories, Lego model shed new light on the Antikythera Mechanism
The 2,000-year-old Greek mechanical “computer” known as the Antikythera Mechanism continues to inspire both scientists and science fans. The geeks are suggesting the geared device may have inspired Greek astronomy, instead of the other way around, and one of the fans has created a new model of the mechanism…out of Legos.
Since its discovery in 1902, the Antikythera Mechanism — with its intricate and baffling system of about 30 geared wheels — has been a fascinating enigma. In 2006, a major new research project used some of the most advanced technology of the 21st century A.D. to decipher the most advanced technology of the 1st century B.C. (A slideshow shows how it was done: Decoding the 2,000-year-old Antikythera Mechanism)
The 2006 findings, aided by advanced imaging software and 3-D X-ray computed tomography, confirmed some previous insights by researcher Michael Wright and expanded on them. The mechanism, originally roughly the size of a largish shoebox, is revealed as a sophisticated mechanical calculator that displayed a variety of astronomical events and periods, including the sun and moon moving through the zodiac, accurately predicted solar eclipses, and apparently displayed movements of the known planets.
There have been serious and successful attempts to recreate the original device, virtually and physically. (The remaining pieces of the mechanism are on display National Archaeological Museum of Athens
But the new Lego model, created by Andrew Carol who does this kind of thing as a hobby in his spare time, while more whimisical, is in some ways more revealing. Carol created the model on a dare from the editor of Nature.com. To mark the launch of its Website, Digital Science co-produced with Nature (both are divisions of Macmillan Publishers Ltd.) a video that shows how the Lego model works, and recreates the calculations and movements of the original mechanism.
(The link to the YouTube video is here.)
There’s also a detailed blogpost on how the complex video was created.
With a score that would be fit the next Jason Bourne movie, the video gives a sense of how the gears perform a series of complex calculations to bring the front dials into position to foretell a future event, in this case a solar eclipse on April 8, 2024, for which some are already preparing.
When the 2006 Antikythera research was presented, it was widely thought that the device embodied the most advanced astronomical theories of 1st century B.C. Greece, including the use of epicyclical gearing to explain the observed changes in celestial movements and speeds.
But now further study is changing that picture, as reported in a November 24 online story at Nature.com. The new theory is that, first, the device actually expresses Babylonian astronomical theories and algorithms; and second, it was the struggle to create a mechanical model that showed the observed changes in celestial speed and motion, that caused the Greeks to recast their own astronomical theories, not the reverse.
The new direction has been charted by historian of astronomy James Evans at the University of Puget Sound in Tacoma, Washington. With his colleagues, Evans found a discrepancy between how the 360 divisions on the surviving portion of the zodiac scale were spaced, compared to the 365 divisions of the calendar scale encircling it. To be correct, the zodiac spacings should have been slightly larger: Evans found they were smaller. For the calculations and movements to come our correctly, the rest of the scale must have used wider spacing. If so, then the zodiac scale was divided into “fast” and “slow” sections, to mimic the perceived changes in the speed of the Sun’s movement. The arrangement is shown in this illustration. “This scheme is identical to a theory of the Sun’s movement used by the Babylonians, known as System A,” according to the Nature story.But if so, then the zodiac scale would no longer be accurate for showing the position of planets. Evans suggests that the five planets were shown on individual dials intended to show not position but the timing of such events as the change in direction, first or last appearance in the night sky and so on. This could have been done with simple gear trains, “representing period relations derived by the Babylonians,” instead of the innovative, and more complex epicyclical gearing, which the device uses to mimic the moon’s movements, “In other words, epicycles were not a philosophical innovation but a mechanical one,” according to Nature. “Once Greek astronomers realized how well epicyclic gearing in devices such as the Antikythera mechanism replicated the cyclic variations of celestial bodies, they could have incorporated the concept into their own geometrical models of the cosmos.”
Two thousand years after it was made, and four years after scientists were certain they had now fully explained its mysteries, the Antikythera Mechanism continues to teach us new things.
