Computer model of how the Antikythera mechanism may have worked. Photograph: UCL
Scientists may have solved ancient mystery of
'first computer'
Researchers claim breakthrough in study of
2,000-year-old Antikythera mechanism, an astronomical calculator found in sea
Ian Sample
Science editor
@iansample
Fri 12 Mar
2021 10.00 GMT
From the
moment it was discovered more than a century ago, scholars have puzzled over
the Antikythera mechanism, a remarkable and baffling astronomical calculator
that survives from the ancient world.
The
hand-powered, 2,000-year-old device displayed the motion of the universe,
predicting the movement of the five known planets, the phases of the moon and
the solar and lunar eclipses. But quite how it achieved such impressive feats
has proved fiendishly hard to untangle.
Now
researchers at UCL believe they have solved the mystery – at least in part –
and have set about reconstructing the device, gearwheels and all, to test
whether their proposal works. If they can build a replica with modern
machinery, they aim to do the same with techniques from antiquity.
“We believe
that our reconstruction fits all the evidence that scientists have gleaned from
the extant remains to date,” said Adam Wojcik, a materials scientist at UCL.
While other scholars have made reconstructions in the past, the fact that
two-thirds of the mechanism are missing has made it hard to know for sure how
it worked.
The
mechanism, often described as the world’s first analogue computer, was found by
sponge divers in 1901 amid a haul of treasures salvaged from a merchant ship
that met with disaster off the Greek island of Antikythera. The ship is
believed to have foundered in a storm in the first century BC as it passed
between Crete and the Peloponnese en route to Rome from Asia Minor.
The
Antikythera mechanism
The
Antikythera mechanism is estimated to date back to around 80 BC. Photograph:
X-Tek Group/AFP
The
battered fragments of corroded brass were barely noticed at first, but decades
of scholarly work have revealed the object to be a masterpiece of mechanical
engineering. Originally encased in a wooden box one foot tall, the mechanism
was covered in inscriptions – a built-in user’s manual – and contained more than
30 bronze gearwheels connected to dials and pointers. Turn the handle and the
heavens, as known to the Greeks, swung into motion.
Michael
Wright, a former curator of mechanical engineering at the Science Museum in
London, pieced together much of how the mechanism operated and built a working
replica, but researchers have never had a complete understanding of how the
device functioned. Their efforts have not been helped by the remnants surviving
in 82 separate fragments, making the task of rebuilding it equivalent to
solving a battered 3D puzzle that has most of its pieces missing.
Writing in
the journal Scientific Reports, the UCL team describe how they drew on the work
of Wright and others, and used inscriptions on the mechanism and a mathematical
method described by the ancient Greek philosopher Parmenides, to work out new
gear arrangements that would move the planets and other bodies in the correct
way. The solution allows nearly all of the mechanism’s gearwheels to fit within
a space only 25mm deep.
According
to the team, the mechanism may have displayed the movement of the sun, moon and
the planets Mercury, Venus, Mars, Jupiter and Saturn on concentric rings.
Because the device assumed that the sun and planets revolved around Earth,
their paths were far more difficult to reproduce with gearwheels than if the
sun was placed at the centre. Another change the scientists propose is a
double-ended pointer they call a “Dragon Hand” that indicates when eclipses are
due to happen.
Computer
model of the mechanism’s gears. Photograph: UCL
The
researchers believe the work brings them closer to a true understanding of how
the Antikythera device displayed the heavens, but it is not clear whether the
design is correct or could have been built with ancient manufacturing
techniques. The concentric rings that make up the display would need to rotate
on a set of nested, hollow axles, but without a lathe to shape the metal, it is
unclear how the ancient Greeks would have manufactured such components.
“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.”
Whether or
not the model works, more mysteries remain. It is unclear whether the
Antikythera mechanism was a toy, a teaching tool or had some other purpose. And
if the ancient Greeks were capable of such mechanical devices, what else did
they do with the knowledge?
“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?”
