An ancient artifact found more than 100 years ago in a Roman ship that sunk in the Mediterranean sea in the second century BC holds new clues to a view of the universe that has influenced scholars and thinkers for more than two millennia.
The notion of a clockwork universe is often associated with Newton, but the ancientGreek view of the universes asgeometric in nature suggests the idea is rooted in a much deeper past. Sponge divers who sought shelter from a storm on the tiny island of Antikythera off the Greek coast in 1900 discovered the wreck, which seemed to be filled with the spoils of war. Amidst the trove of jewelry, statues, coins and weapons, was an elaborate bronze device about the size of a shoe box that contained more than 30 bronze gear wheels and was covered with thousands of Greek inscriptions. But a corroded mass his hid its intricate inner mystery, soit not carefully examined for decades.
A story by Jo Marchant in the Nov. 25 issue of Nature describes the discovery-now called the Antikythera Mechanism -as a technologically sophisticated clockwork device that displayed the sun, moon, and the five planets known at the time. The name of the Greek craftsman who built the device is lost to antiquity, and some historians think the device is so sophisticated it must have been the product of generations of achievement. A handle turns to indicate the path of celestial bodies, and the appearance and disappearance of major stars at different times of the year are charted. A complex interplay of gear wheels riding on other gear wheels allows for elliptical movements, and sun and moon movements that varied from fast to slow in different parts of their trajectories. It also represented the four year cycles of the Olympic games and predicted eclipses.
Scholars exploring its capabilities were astonished. The British historian Derek De Solla Price who studied Antikythera Mechanism in the 1950s, likened its discovery to opening King Tut’s tomb for the first time and finding a fully functional internal combustion engine inside.Marchant, who became so fascinated with the device that she wrote her book Decoding the Heavens about it, says it was utterly unlike any else historians had seen from the first or second centuries BC. In fact, its technological complexity was unmatched until the eighteenth century. Before it was authenticated, some thought it must be a hoax or something that had been dropped accidentally into the sunken ship. Others suspected it had been produced by aliens.
Radiographic studies of the internal gear wheels and work by scholars at the Antikythera Mechanism Research Project helped reconstruct a large circular dial with two concentric scales, one marked with months of the year, and one marked with 12 signs of the zodiac. Researchers also identified two spiral dials, one showing a repeating 235 month calendar, and one showing a 223 month calendar. Marchant explains that after 235 months, or 19 years, the distribution of new moons in the solar year is the same. The 223 month calendar represents an eclipse cycle. Both cycles were identified initially by Babylonian astronomers. Astronomy scholar James Evans and others believe the design of the mechanism is Babylonian rather than Greek, a signifncant addition to historical analysis.
So where did the Greek concept of a geometric cosmos come from? Marchant says scholarship on the Antikythera Mechanism suggests the Greek or Greeks who developed it were inspired by Babylonian mathematics and astronomy. Marchant quotes Evans in her article: "Maybe we need to rethink the connection between mechanics and astronomy. People think of it as purely one way, but maybe there was more of an interplay.” In other words, she writes, when that Greek mechanic shaped the Antikythera Mechanism’s complex gear trains, he didn’t just create one device, he helped shape a view of the universe that would last 2,000 years. Listen to Marchant and Evans discuss this amazing device, which they compare in sophistication to an ancient celestial IPod.