Science News

Mechanical cosmos recreated inside world's first analogue computer

By Brooks Hays   |   March 12, 2021 at 2:02 PM
Researchers have recreated the cosmos display at the front of the Antikythera Mechanism, an ancient Greek analog computer used to predict the position of planets and eclipses. Photo by Tilemahos Efthimiadis/Wikimedia

March 12 (UPI) -- Scientists have reconstructed a cosmological model to fit the complex arithmetic of the Antikythera Mechanism, the world's first analogue computer.

One of the most sophisticated engineering feats to have survived from the ancient world, the 2,000-year-old Antikythera Mechanism was used by Greek astronomers to calculate the positions of the sun, moon and planets, as well as predict lunar and solar eclipses.


The ancient astronomical calculator was first recovered from a Roman-era merchant ship, wrecked off the coast of the Greek island of Antikythera, by sponge divers in 1901.

In the decades since, scientists have struggled to figure out exactly how its 30 bronze gears worked to calculate astronomical positions.

Researchers at the University College London were able to decipher the computer's mechanics using a combination of X-ray images and ancient Greek mathematical analysis.

They detailed their feat in a new paper, published Friday in the journal Scientific Reports.

"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," lead study author Tony Freeth said in a press release.

"The sun, moon and planets are displayed in an impressive tour de force of ancient Greek brilliance," said Freeth, a professor of engineering at UCL.

Scientists have previously attempted to reconstruct the device, but only about a third of the system's gears remain intact, complicating those efforts.

The authors of the latest study built off the progress made by earlier modeling efforts.

To complete the cosmological model, researchers utilized inscriptions on the bronze device, as well as mathematical methods developed by the ancient Greek philosopher Parmenides.

According to the new analysis, two numbers inscribed on the front of the bronze device, 462 and 442, represent the cycles of Venus and Saturn.

To understand how the ancient computer was able to calculate those figures, scientists had to operate under the Greek assumption that the sun and planets revolved around Earth.

The methods of Parmenides helped scientists produce a new model to explain how two of the device's fragments, including an essential 63-tooth gear, worked to predict the 462-year planetary period relation of Venus.

"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," Freeth said.

The breakthrough allowed scientists to solve one of the Antikythera Mechanism's last remaining puzzles.

"Now, we must prove its feasibility by making it with ancient techniques," said co-author Adam Wojcik, a materials scientist at UCL. "A particular challenge will be the system of nested tubes that carried the astronomical outputs."