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04/04/2018 | News release | Distributed by Public on 04/04/2018 15:29

The Riddle of the Ancient Greek ‘Computer’

Can you explain what we know about how it worked?

This thing was sort of shoebox-sized with display dials, and there was some kind of a knob or a crank on the side which you would turn, and turning it would represent going forward or backward in time. The back side of the mechanism showed cycles of measuring time, like a calendar, and the cycle of the Olympic games and the other big Greek game competitions. And on the front side there was this kind of planetarium display that simulated the movements of the sun, the moon, and the five planets that people knew before telescopes-which is everything as far out as Saturn-as you see them from the Earth.

How technologically advanced was the mechanism?

In terms of the technology of the gears inside that made this thing do what it did, it was very sophisticated. You really have to go more than a thousand years later to late medieval Europe when these sorts of public astronomical clocks were being put up in cities. So technologically, this is the highest-end ancient Greek machine that survives in any form. We have books that mention things that are comparable, but work differently. There's no record of anything else like this gear-work device.

Do you have an idea of how it was meant to be used?

What we found there is that on the dial there are month names of this particular local calendar, which is probably the place the mechanism was made for. But what it's showing is that it was connecting science with civil and religious life, and showing the games. Why would an astronomical tool show you when the Olympic games are going to be held every four years? Because it's not really a research tool at all-that's my take on it. This is a teaching device that's about showing how the world works, governed by time, and it's the human world as well as the celestial world. And so you could basically teach a whole course on cosmology with something like this.

The mechanism is sometimes referred to as an early calculator. What kind of calculations could it perform?

It could do a certain kind of calculation, like where, more or less, the sun, moon, and planets are or were on a particular date. But it's not super accurate. It's a very expensive way of doing a job that you can do with the equivalent of a pencil and paper. But if you want to show the cosmos to people who are not specialists in astronomy, it would have had huge visual impact. It could speed time up: it takes Jupiter 12 years, and Saturn 30 years, to go once around the zodiac, so you're going to have a long wait if you're going out at night to show your pupils this kind of stuff. But with a machine like this, you can just whiz the thing around, and you'd see these pointers going around the dial, you'd see a little ball that represents the moon with its phases, and at the same time you have all these things on the back showing the calendar cycle, the games cycle, and so on. I could see this as being something that would really, really impress people with the coordination of the universe, which was something that at least some of the schools of ancient philosophy made a big thing about. Stoics, for example, described the universe as a kind of organism, like a living thing with a mind that caused the coordination of everything, including human lives. So for a Stoic philosopher, something like this would be just such a beautiful way of visualizing that conception.