National Post Staff 3/12/2021
For more than 100 years, scientists have deliberated the mystery behind the ancient Antikythera mechanism, a 2,000 year old Greek astronomical calculator with the ability to exhibit the movement of the universe, including five known planets and predict the phases of the moon and the solar and lunar eclipses.
Currently only a third of the device — often defined as the world’s first analogue computer — remains in a collection of 82 battered fragments, including 30 corroded bronze gearwheels, further baffling scholars.
Researchers also don’t know why the Antikythera mechanism was built. It could have been a toy, or a teaching tool, they posited.
“Although metal is precious, and so would have been recycled, it is odd that nothing remotely similar has been found or dug up,” Wojcik said. “If they had the tech to make the Antikythera mechanism, why did they not extend this tech to devising other machines, such as clocks?”
However researchers at the University College of London believe they may have finally cracked the code and hope to prove it by building a replica using modern machinery to test their theory. “We believe that our reconstruction fits all the evidence that scientists have gleaned from the extant remains to date,” Adam Wojcik, a materials scientist at UCL, told The Guardian .
If their theory is correct, then they hope to rebuild the mechanism using a technique from antiquity, they wrote in a paper published by science journal Nature .
The calculator first came to light in 1901 after it was recovered by sponge divers looking for treasures within an archaic ship sunken off the coast of Antikythera, a Greek island. Scholars believe the ship sank during a storm in the first century BC while passing between Crete and the Peloponnese while en route to Rome from Asia Minor.
The device is heavily corroded, but scholars examining it noticed several inscriptions on the mechanism, which provide a kind of user’s manual to operating the calculator. It also included more than 30 bronze gearwheels connected to dials and pointers.
The team believe that the device may have displayed the movement of the sun, moon and the planets Mercury, Venus, Mars, Jupiter and Saturn on concentric rings. However, as the calculator assumes that the sun and planets revolve around the Earth, the planets’ paths are much more difficult to recreate than if the Sun was at the centre.
They also propose adding a hypothetical feature, called the ‘Dragon Hand’ that indicates when eclipses would happen, to replace a similar hand once used by the clock. “The way that the Saros Dial on the Back Plate predicts eclipses essentially involves the lunar nodes , but they are not described in the extant inscriptions,” the paper reads. Lunar nodes are where the Moon’s orbit intersects that of the Earth.
The UCL team wrote that it drew on the works of previous scholars and engineers to reconstruct the mechanism, particularly that of Michael Wright.
Wright, a former mechanical engineer at the Science Museum of London, was instrumental in figuring out how most of the mechanism work, enough to build a working replica. Drawing on his work, researchers used inscriptions on the mechanism and a mathematical method described by Parmenides, an ancient Greek philosopher, to design gear arrangements to move planets and other bodies correctly.
Their solution allows nearly all of the mechanism’s gearwheels to fit within a space only 25 mm deep.
Though hopeful, it isn’t clear whether the new model could accurate replicate the workings of the calculator. For one, the concentric rings that constitute the calculator’s display would have to rotate on a set of nested, hollow axles, and researchers aren’t sure how ancient Greeks would have made the mechanism possible without a modern-day lathe (a machining tool used to shape or rotate metal and wood).
“The concentric tubes at the core of the planetarium are where my faith in Greek tech falters, and where the model might also falter,” said Wojcik. “Lathes would be the way today, but we can’t assume they had those for metal.”
Experts recreate a mechanical Cosmos for the world's first computer
Researchers at UCL have solved a major piece of the puzzle that makes up the ancient Greek astronomical calculator known as the Antikythera Mechanism, a hand-powered mechanical device that was used to predict astronomical events.
Known to many as the world's first analogue computer, the Antikythera Mechanism is the most complex piece of engineering to have survived from the ancient world. The 2,000-year-old device was used to predict the positions of the Sun, Moon and the planets as well as lunar and solar eclipses.
Published in Scientific Reports, the paper from the multidisciplinary UCL Antikythera Research Team reveals a new display of the ancient Greek order of the Universe (Cosmos), within a complex gearing system at the front of the Mechanism.
Lead author Professor Tony Freeth (UCL Mechanical Engineering) explained: "Ours is the first model that conforms to all the physical evidence and matches the descriptions in the scientific inscriptions engraved on the Mechanism itself.
"The Sun, Moon and planets are displayed in an impressive tour de force of ancient Greek brilliance."
The Antikythera Mechanism has generated both fascination and intense controversy since its discovery in a Roman-era shipwreck in 1901 by Greek sponge divers near the small Mediterranean island of Antikythera.
The astronomical calculator is a bronze device that consists of a complex combination of 30 surviving bronze gears used to predict astronomical events, including eclipses, phases of the moon, positions of the planets and even dates of the Olympics.
Whilst great progress has been made over the last century to understand how it worked, studies in 2005 using 3D X-rays and surface imaging enabled researchers to show how the Mechanism predicted eclipses and calculated the variable motion of the Moon.
However, until now, a full understanding of the gearing system at the front of the device has eluded the best efforts of researchers. Only about a third of the Mechanism has survived, and is split into 82 fragments - creating a daunting challenge for the UCL team.
The biggest surviving fragment, known as Fragment A, displays features of bearings, pillars and a block. Another, known as Fragment D, features an unexplained disk, 63-tooth gear and plate.
Previous research had used X-ray data from 2005 to reveal thousands of text characters hidden inside the fragments, unread for nearly 2,000 years. Inscriptions on the back cover include a description of the cosmos display, with the planets moving on rings and indicated by marker beads. It was this display that the team worked to reconstruct.
Two critical numbers in the X-rays of the front cover, of 462 years and 442 years, accurately represent cycles of Venus and Saturn respectively. When observed from Earth, the planets' cycles sometimes reverse their motions against the stars. Experts must track these variable cycles over long time-periods in order to predict their positions.
"The classic astronomy of the first millennium BC originated in Babylon, but nothing in this astronomy suggested how the ancient Greeks found the highly accurate 462-year cycle for Venus and 442-year cycle for Saturn," explained PhD candidate and UCL Antikythera Research Team member Aris Dacanalis.
Using an ancient Greek mathematical method described by the philosopher Parmenides, the UCL team not only explained how the cycles for Venus and Saturn were derived but also managed to recover the cycles of all the other planets, where the evidence was missing.
PhD candidate and team member David Higgon explained: "After considerable struggle, we managed to match the evidence in Fragments A and D to a mechanism for Venus, which exactly models its 462-year planetary period relation, with the 63-tooth gear playing a crucial role."
Professor Freeth added: "The team then created innovative mechanisms for all of the planets that would calculate the new advanced astronomical cycles and minimize the number of gears in the whole system, so that they would fit into the tight spaces available."
"This is a key theoretical advance on how the Cosmos was constructed in the Mechanism," added co-author, Dr Adam Wojcik (UCL Mechanical Engineering). "Now we must prove its feasibility by making it with ancient techniques. A particular challenge will be the system of nested tubes that carried the astronomical outputs."
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The discovery brings the research team a step closer to understanding the full capabilities of the Antikythera Mechanism and how accurately it was able to predict astronomical events. The device is kept at the National Archaeological Museum in Athens.
The UCL Antikythera Research Team is supported by the A.G. Leventis Foundation, Charles Frodsham & Co. and the Worshipful Company of Clockmakers.
The team is led by Dr Adam Wojcik and made up of Professor Tony Freeth, Professor Lindsay MacDonald (UCL CEGE), Dr Myrto Georgakopoulou (UCL Qatar) and PhD candidates David Higgon and Aris Dacanalis (both UCL Mechanical Engineering).
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