By building a digital model of the Antikythera mechanism, scientists finally uncovered a key function of the ancient device and revealed it a design that required seriously advanced thinking.
The 2000-year-old Antikythera mechanism was pulled from a shipwreck off the coast of Crete in 1901 and surprised scientists. New research published in Scientific Reports presents a hypothetical model of the astronomical instrument, presented by Tony Freeth, the lead author and a mechanical engineer at the University of London., says is the first to comply with “all the physical evidence and consistent with the descriptions in the scientific inscriptions engraved on the mechanism itself,” he said in a statement.
The handheld device is the oldest known analog-astronomical computer, an early example of complex mechanical engineering. The device stretches from ancient Greece and has formed astronomical phenomena and events such as lunar and solar eclipses and the positions of the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn.
Only a third of the Antikythera Mmechanism has been restored, and there is nothing else to compare it to. The incomplete remnant, with its 30 bronze gears and 82 individual fragments, has forced scientists to speculate what it looks like, what it is used for and how it works.
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In 2016, scientists offered the results of a decades-long investigation into the remains. Using an X-ray scanner, scientists were able to document 3,500 characters of explanatory text – a kind of manual – embedded on the device. Analysis of this text suggests that the Antikythera mechanism is not a real computer because it is not programmable. It was rather a machine designed to transfer our place in the universe and predicts celestial events such as lunar and solar eclipses.
Fragment A, the largest part of the device, consists of bearings, pillars and a block, while Fragment D contains a disc whose purpose is unknown, a gear with 63 teeth and a plate. The aim of the new study was to gain a better understanding of the lever system at the front of the mechanism, which is largely lacking.
The inscriptions mention a cosmic mechanical exhibition in which the planets and moon, represented by marker beads, move around on rings. As the authors write in their study, ‘no previous reconstruction is close’ to creating a model that actually meets this apparent specification. To that end, the team failed to recreate the missing component of the Antikythera mechanism.
“The solution to this intricate 3D puzzle reveals a creation of genius – the combination of cycles from Babylonian astronomy, mathematics of Plato’s Academy and ancient Greek astronomical theories,” write the authors, including Adam Wojcik, also the mechanical engineer, of UCL.
The ancient Babylonians indeed chronicled the movements of the planets, while the ancient Greek philosopher Parmenides developed a mathematical model to explain these movements.
Inscriptions on the device mentioned celestial cycles assigned to Venus, at 462 years, and Saturn, at 442 years. The scientists associated these numbers with synodic cycles, which describe the duration of a celestial object to return to its original position in relation to our perspective on earth. These cycles were important to the ancient Greeks because of their geocentric view of the universe. When we look at the sky, it seems as if the planets sometimes stand still for a short time and swing back and forth as they – and us on earth – orbit the Sun (ie retrograde motion), in which is an optical illusion. (A fantastic example of this can be seen here, in which the moon apparently deteriorates.) As a fun fact, the word ‘planet’ comes from the Greek word for ‘wanderer’.
The Greeks, believed that the planets revolve around Earth, was amazed at these retrograde movements, and they devised some rather complicated theories and mathematical explanations to make it all work, many of them flat-wrong out.
Look at the Antikythera mechanism itself, the researchers realized that components in fragments A and D corresponded to the mechanical motions of Venus, “which precisely modeled the 462-year-old planetary relationship, with the 63-speed gear playing a crucial role,” he said. David Higgon, a PhD student and co-author of the paper, in the UCL statement. The scientists then determined the cycles of the remaining planets, which they did using the ancient Greek formulas, and incorporated these cycles according to the article into ‘highly compact mechanisms, which correspond to the physical evidence’.
What this all means is that the Greeks, with their geocentric view of the cosmos, made it unnecessarily difficult for themselves in the design of the Antikythera mechanism. Instead of showing the planets –represented by beads moving along concentric circles – moving in a single direction around the Sun, they had to point the planets back and forth brilliantly during their cycles as they moved around Earth. Incredibly, it had to be done for each of the five planets, with the relative position that each must be accurate at any given time. Assuming this is the case, at least the machine works.
Equipped with their calculations, the scientists then designed and digitally recreated this monstrous complicated thing. The scientists “created innovative mechanisms for all the planets that would calculate the new advanced astronomical cycles and reduce the number of gears in the entire system so that it would fit in the available spaces,” Freeth said. Indeed, the gear arrangements could not be arbitrarily large, as the assumed components had to fit into the device, including spaces not exceeding 25 millimeters deep.
A 30-minute movie left this research, which shows how this model came together, can be seen on Vimeo.
The simulated machine seems to work, but simulated is the key word. The authors rightly say that an important step has yet to be completed.
“Now we have to prove its feasibility by making it with ancient techniques,” Wojcik said. A special challenge is the system of nested tubes that carry the astronomical outputs. ‘
Nice. It sounds like the team is about to embark on an experimental archeology, in which a real physical model of the Antikythera mechanism will be built. Just the thought of thinking that about 2,000 years later we will struggle to recreate this ‘genius creation’, in a remarkable example of lost technology.