An Ancient Greek Machine Rewriting the History of Technology
Discovery of the Antikythera Mechanism
In the spring of 1900, a group of sponge divers took refuge from a Mediterranean storm near the small island of Antikythera, located between Crete and mainland Greece. Once the storm subsided, they resumed diving and stumbled upon an ancient shipwreck. This wreck contained a stunning collection of Greek artifacts, including bronze sculptures, glassware, jewelry, amphorae, furniture fittings, and tableware.
The Astonishing Mechanism
Several months after its recovery, the object split apart, revealing intricate gearwheels, some the size of coins. This discovery challenged existing assumptions about ancient Greek technology, as precision gearing of this nature was not thought to exist in that era. Today, only about one-third of the original mechanism survives, divided into 82 fragments, labeled A-G and 1-75.
For more than a century, researchers have attempted to decode the purpose of the device. A multidisciplinary team of scientists from University College London (UCL), known as the UCL Antikythera Research Team, has recently made significant strides in understanding how the mechanism functioned. Their work builds upon the insights of past scholars, using modern imaging and analytical techniques to develop a model that aligns with all available evidence.
An Astronomical Calculating Machine
From its discovery, the mechanism sparked debate regarding its purpose. Early theories proposed that it was either an astrolabe for tracking stars or a navigation device, but these ideas were eventually disproven. The journey to understanding its true function has been a complex and evolving detective story.
- The 19-year Metonic cycle (used to align lunar and solar calendars)
- The 76-year Callippic cycle (a refinement of the Metonic cycle)
- The 223-month Saros cycle (used for predicting eclipses)
Rehm suggested that the device was an astronomical calculator. He also theorized that it used epicyclic gearing—gears mounted on other gears—a concept previously thought to be beyond the reach of ancient Greek engineering. However, his understanding of the internal mechanics was incomplete, and his work remained unpublished.
Scientific Investigations and Advancements
Fifty years later, British physicist Derek de Solla Price embarked on a two-decade-long study of the mechanism. His research, published in the landmark paper Gears from the Greeks (1974), made significant progress in decoding the mechanism’s function.
Price’s discoveries were aided by X-ray imaging conducted by Charalambos and Emily Karakalos, which revealed 30 surviving gears:
- 27 in Fragment A
- 1 each in Fragments B, C, and D
By analyzing the gearing, Price confirmed that the mechanism could calculate the 19-year Metonic cycle. However, while he advanced the understanding of the Sun-Moon system, his insights into planetary calculations remained speculative.
After Price’s death in 1983, the challenge was taken up by Michael Wright, a curator at the London Science Museum. Wright had extensive experience studying mechanical devices and significantly expanded upon Price’s work. He reconstructed the gearing and determined that the mechanism tracked planetary movements.
The Greek Perception of the Cosmos
To understand the mechanism’s purpose, it is important to consider how the ancient Greeks viewed the universe. Their model was geocentric, believing that the Earth was at the center while the Sun, Moon, and planets moved around it. The planets appeared to follow irregular paths against the backdrop of fixed stars, at times reversing direction—a motion known as retrograde motion.
In the 1st millennium BC, Babylonian astronomers discovered period relations—cycles that linked planetary movements to whole numbers of years. For example, Venus completes five synodic cycles in eight years. The Greeks later developed geometrical theories to explain these planetary motions, making them suitable for mechanical replication in a geared device. The Antikythera Mechanism appears to have used these theories to create a mechanical model of the cosmos, allowing predictions of planetary positions with the simple turn of a handle.
Reconstructing the Antikythera Mechanism
The UCL Antikythera Research Team examined Wright’s pioneering work and uncovered further evidence of the mechanism’s complexity. They focused on the Main Drive Wheel, a four-spoked gear in Fragment A, which serves as the system’s central driving force. This wheel, turned by a handle, sets the other gears in motion.
Wright proposed that an epicyclic gearing system was mounted on the Main Drive Wheel. This system, combined with pin-and-slotted follower mechanisms, could accurately replicate the backward loops (retrograde motion) of planets. Inspired by medieval astronomical clocks, Wright reconstructed a planetarium model of the mechanism that displayed:
- The current date
- The positions of the Sun and Moon
- The positions of the five known planets: Mercury, Venus, Mars, Jupiter, and Saturn
His results, published in 2002, marked a significant milestone in Antikythera research, though later studies would refine and challenge some aspects of his model.
Conclusion: A Revolutionary Machine
The Antikythera Mechanism stands as a testament to the technological sophistication of ancient Greece. It not only provided astronomical predictions but also demonstrated an advanced understanding of mathematics, engineering, and cosmology. This intricate device rewrites the history of technology, proving that ancient civilizations possessed knowledge and skills far more advanced than previously believed. Ongoing research continues to unlock its mysteries, ensuring that this remarkable machine remains at the forefront of historical and scientific inquiry.
