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.”
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.
Reference:
Tony Freeth, David Higgon, Aris Dacanalis, Lindsay MacDonald, Myrto
Georgakopoulou, Adam Wojcik. A Model of the Cosmos in the ancient Greek
Antikythera Mechanism. Scientific Reports, 2021; 11 (1) DOI:
10.1038/s41598-021-84310-w
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