The Antikythera mechanism, recovered from a shipwreck off the Greek island of Antikythera in 1901, remains one of the most astonishing artifacts from the ancient world. The device dates to approximately 100-150 BC and is a hand-powered orrery capable of predicting astronomical positions, eclipses, and the timing of the ancient Olympic games.

The mechanism contains at least thirty gears arranged with remarkable precision. The Metonic cycle (235 lunar months roughly equal to 19 solar years) is encoded in a 235-tooth gear. The Saros cycle for eclipse prediction is also encoded. A differential gear — long thought to be a medieval European invention — appears in the mechanism's design.

What makes it epistemologically interesting is what it implies about lost technology. This cannot have been a unique object — the knowledge required to design and build it must have had a tradition behind it. Cicero mentions a similar device made by Archimedes. We have essentially no other physical evidence of this tradition of precision mechanical engineering.

The UCL team's X-ray tomography has revealed previously unreadable inscriptions, including what appears to be a planetary display on the front. The full picture of its capabilities is still being reconstructed from fragments.