Antikythera Mechanism Research Project

FragmentA back

Antikythera Mechanism,  fragment A – back

More than 21 centuries ago, a mechanism of fabulous ingenuity was created in Greece, a device capable of indicating exactly how the sky would look for decades to come — the position of the moon and sun, lunar phases and even eclipses. But this incredible invention would be drowned in the sea and its secret forgotten for two thousand years. For more than a century, researchers were trying to understand its functions. Since 2005, a pluridisciplinary research team, the “Antikythera Mechanism Research Project”, is studying the Mechanism with the latest high tech available. The results of this ongoing research has enabled the construction of many models.

In 1901, a group of divers excavating an ancient Roman shipwreck near the island of Antikythera, off the southern coast of Greece, found a mysterious object – a lump of calcified stone that contained within it several gearwheels welded together after years under the sea. The 2,000-year-old object, no bigger than a modern laptop, is now regarded as the world’s oldest computer, devised to predict solar eclipses and, according to recent findings, calculate the timing of the ancient Olympics. Following the efforts of an international team of scientists, the mysteries of the Antikythera Mechanism are uncovered, revealing surprising and awe-inspiring details of the object that continues to mystify.

The Antikythera mechanism (pron.: /ˌæntɨkɨˈθɪərə/ ant-i-ki-theer-ə or /ˌæntɨˈkɪθərə/ ant-i-kith-ə-rə) is an ancient analog computer designed to calculate astronomical positions. It was recovered in 1900–1901 from the Antikythera wreak, but its significance and complexity were not understood until a century later. Jaques Cousteau visited the wreck in 1978 but, although he found new dating evidence, he did not find any additional remains of the Antikythera mechanism. The construction has been dated to the early 1st century BC. Technological artifacts approaching its complexity and workmanship did not appear again until the 14th century AD, when mechanical astronomical clocks began to be built in Western Europe.

Professor Michael Edmunds of Cardiff University, who led a study of the mechanism, said: 

“This device is just extraordinary, the only thing of its kind. The design is beautiful, the astronomy is exactly right. The way the mechanics are designed just makes your jaw drop. Whoever has done this has done it extremely carefully … in terms of historic and scarcity value, I have to regard this mechanism as being more valuable than the Mona Lisa.”

FragmentA

Antikythera Mechanism, fragment A – front

The mechanism would have been housed in a wooden box approximately 340 × 180 × 90 mm in size and comprised of 30 bronze gears (although more could have been lost). The largest gear, clearly visible in fragment A, was approximately 140 mm in diameter and probably had either 223 or 224 teeth. The mechanism’s remains were found as 82 separate fragments of which only seven contain any gears or significant inscriptions. All that remains now of Antikythera mechanism is a col­lec­tion of cor­roded lumps found off the island of Anti­kythera. Edmunds and his team x-rayed the lumps to read the hid­den inscrip­tions without priz­ing apart the device and dam­aging it.

This machine has the oldest known complex gear mechanism and is sometimes called the first known analog computer,although the quality of its manufacture suggests that it may have had a number of undiscovered predecessors during the Hellenistic Period. It appears to be constructed upon theories of astronomy and mathematics developed by Greek astronomers and is estimated to have been made around 100 BC. In 1974, British science historian and Yale University Professor Derek de Solla Price concluded from gear settings and inscriptions on the mechanism’s faces that the mechanism was made about 87 BC and was lost only a few years later.

The mechanism was operated by turning a small hand crank (now lost) which was linked via a crown gear to the largest gear (the 4 spoked gear visible on the front of fragment A (named b1)). This allowed setting of the date on the front dial. The action of turning the hand crank would also cause all interlocked gears within the mechanism to rotate, resulting in the calculation of the position of the Sun andMoon and other astronomical information, such as moon phases, eclipse cycles, and theoretically the locations of planets.

The Sun would be mov­ing slowly against the back­ground stars, so over the course of a year it would pass through all the signs of the zodiac. The Moon how­ever is more com­plex. The Moon also moves in front of the back­ground stars, but it only takes about 27 days to do this. It’s called the sider­eal period. So you need a couple of gears to drive those two motions. But you wouldn’t really think of the sider­eal period as a month. For most people the syn­odic period, the time between one New Moon and the next or the time between one Full Moon and the next, is a month. This is around 29½ days. Throw in extra gears for driv­ing other dis­plays show­ing eclipse cycles and it’s clearly a com­plex device. The ori­ginal stud­ies found evid­ence of epi­cycles, gears moun­ted on other gears. Add other fea­tures like dis­plays for eclipse and lunar cycles on the back and it’s obvi­ous you have a com­plic­ated device. The 2006 research showed that in fact it was all a bit more com­plic­ated than that.

Computer grenerated graphic

Computer generated graphic for the front of the Antikythera Mechanism

The Moon’s move­ment isn’t con­stant. It speeds up and slows down. This is because its orbit isn’t exactly cir­cu­lar. Instead it’s slightly egg-shaped. The point fur­thest from the earth is the apo­gee and the point closest to the Earth is the peri­gee. When it’s near the apo­gee it travels slowly, but when it moves closer to the Earth it picks up speed until it passes peri­gee and then it slows down again. This is called the first lunar anom­aly. The dif­fer­ence is notice­able by the naked eye, if you’re will­ing to make sys­tem­atic obser­va­tions. This is all simply explained by Kepler’s Laws of Plan­et­ary Motion. There’s small prob­lem. Kepler used ellipses.

You can’t use ellipt­ical gears. The point of gears is that they must have inter­mesh­ing teeth. An ellipt­ical gear would lose con­tact with the driv­ing gear as its axis changed. Instead it seems that the mech­an­ism used two gears, one slightly off-axis from the other. The rota­tion was con­nec­ted by a pin-and-slot arrange­ment, so that the one gear wouldn’t turn at quite the same rate as the other gear. The on-axis gear can then be turned reli­ably by the drive gears, while the motion of the moon can driven by the off-axis gear. So you have a device that can track the sider­eal, syn­odic and anom­al­istic months, all while the Earth is spin­ning round the Sun. If that’s caus­ing your head to spin you might want to skip the next paragraph.

There’s another prob­lem. The lunar anom­aly describes the Moon’s travel from one apo­gee to the next. This apo­gee is also rotat­ing around the earth. If the apo­gee is in Aries then two and a bit years later it will be in Can­cer, and another two and a bit years to move into Libra until it too has trav­elled through the zodiac over about nine years. So now we have a device which tracks the Moon around the Earth, and its phases and it’s vari­able speed and vari­ations in that vari­ab­il­ity, while also keep­ing track of the Sun’s pos­i­tion, poten­tial lunar and solar eclipses and inter­cal­a­tion cycles so you know when to stick an extra month in to keep the lunar months in step with the solar year round gears, some moun­ted slightly off axis to cre­ate a pseudo-sinusoidal vari­ation using cir­cu­lar gears to replace ellipses. If you have funny feel­ing near the back of your head right now, that’s prob­ably your brain try­ing to crawl out of your ears. The Anti­kythera Mech­an­ism is insanely com­plex. Still just because it’s insanely com­plex, that doesn’t make it sci­entific.

In fact you can argue about whether or not Sci­ence exis­ted in the ancient world. Cer­tainly a lot of ele­ments like test­ing ideas with exper­i­ments didn’t really become pop­u­lar till after Galileo. On the other hand some nat­ural philo­sophy of the time was based on obser­va­tion. There was cer­tainly tech­no­logy which was the res­ult of applied know­ledge. With those kind of pro­visos a lot of ancient his­tor­i­ans would be happy with the idea of ancient sci­ence, albeit a sci­ence dif­fer­ent to post-Renaissance sci­ence. In this case, the sheer intense obser­va­tion and cal­cu­la­tion involved in mak­ing the Anti­kythera Mech­an­ism marks it out as a work of ancient sci­ence. There’s also another factor which might make it more sci­entific than artistic.

To some extent the Anti­kythera Mech­an­ism Research Pro­ject have been inter­ested in hanging a name on the device. It was thought to have ori­gin­ated in Rhodes and sunk on its way to Rome, which would have con­nec­ted it to the home city of Hip­par­chus, one of the great astro­nomers of antiquity. The 2008 paper has examined the parapegma on the mech­an­ism and dis­covered it may be con­nec­ted to Syra­cuse, home of Archimedes.

A parapegma is a cal­en­dar, usu­ally with holes for stick­ing a peg into for mark­ing the days. In the case of ancient Greece they’re inter­est­ing when they tell you what day of the month it is, because each Greek city had its own set of months. The months were usu­ally named after reli­gious fest­ivals, and this was tied into local polit­ics. That meant hav­ing your own cal­en­dar was a good way of show­ing your inde­pend­ence. The best match for the months men­tioned on the mech­an­ism is Taur­omenion, mod­ern Taorm­ina, in Sicily. This is likely to have shared some months with Syra­cuse as it was re-settled from there in the fourth-century BC, so Syra­cuse is a strong pos­sib­il­ity for the home of this device. Archimedes is said to have inven­ted a plan­et­arium accord­ing to Cicero and is thought to have writ­ten a lost book on astro­nom­ical devices. How­ever he could not have made this device. Archimedes died in 212 BC. The Anti­kythera Mech­an­ism is cur­rently thought to date to the second half of the second cen­tury BC, but that might change. But it was very likely to have been made after Archimedes death and that’s what makes it scientific.

Antikythera_mechanism.svg

Schematic of the artefact’s known mechanism

Art can be col­lab­or­at­ive, or it can be per­sonal. Sci­ence in con­trast is built on cumu­lat­ive know­ledge. The per­son who inven­ted the gear­ing did not have to be the per­son who made the astro­nom­ical obser­va­tions. He didn’t even need to live in the same cen­tury as the astro­nomer. In fact the maker of this device might not have done either. He could have fol­lowed a kit and added his own per­sonal touches on the cas­ing. There’s a core to this device which, once expressed, is inde­pend­ent of per­sonal vis­ion. Archimedes didn’t have his own per­sonal Moon which moved in a dif­fer­ent way to every­one else’s, while an artist can have a per­sonal inter­pret­a­tion of the Moon.

A reason people might think the Anti­kythera Mech­an­ism is a work of art is that it’s clearly the res­ult of a lot of ima­gin­a­tion. Great art requires ima­gin­a­tion, but so too does great sci­ence. It requires the kind of ima­gin­a­tion that can look at a tool­box full of circles and see ellipses. The kind of ima­gin­a­tion that can watch wheels turn within wheels as bod­ies waltz to the music of the celes­tial spheres. Another com­mon factor between art and sci­ence is that great art can show a new way of look­ing at the world, and great sci­ence does this too. That’s why I dis­agree with Candy Minx when she says “Sci­ence is always play­ing catch up with the poets.” Sci­ence can reveal beauty too, as a visit to the Anti­kythera Mech­an­ism Research Group’s homepage would show.

The Antikythera mechanism is displayed at the National Archaeological Museum of Athens, accompanied by a reconstruction made and donated to the museum. Other reconstructions are on display at the American Computer Museum in Bozeman, Montana, the Children’s Museum of Manhattan in New York, in Kassel, Germany, and at the Musée des Arts et Métiers in Paris.

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About Art Selectronic

Art Selectronic is an artist-led initiative, that supports grass-roots contemporary art that remains unswayed by fashion, trends or the whims of government funding. The project involves ongoing research into the placing of contemporary art, it’s audiences and it’s relationship to the everyday. We place great emphasis on context. Our mission is to support new works of contemporary art and foster an audience from a wide range of backgrounds.
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2 Responses to Antikythera Mechanism Research Project

  1. BRIAN GREIG says:

    I make the largest number of orreries under the Sun. have 4 orreries at Sydney Observatory
    one of which is a Martian orrery using two elliptical gears to the show how Mars with its elliptical orbit comes and goes around the earth.
    it appears that the object is one of many, most of my more complicated models have drill holes as I try to match complicated gear wheel counts in just two axis.am not aware of any one finding old holes in.the object

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