Thursday, January 11, 2007

The Antikythera Anachronism?

` The article I am referencing due to lack of additional time to study:
` In search of lost time: The ancient Antikythera Mechanism doesn't just challenge our assumptions about technology transfer over the ages — it gives us fresh insights into history itself - Nature News editor, Jo Marchant.
` I had always wondered about this thing.... Apparently it was discovered over a hundred years ago in 1902, but it has not gotten its deserved attention from historians, scientists and engineers - not to mention, the general public.
` So... what does it look like? Lucky you, there are plenty of pictures to ogle, such as this one:


` Barring that, I really enjoyed Jo Marchant's description for its own sake:

It looks like something from another world — nothing like the classical statues and vases that fill the rest of the echoing hall. Three flat pieces of what looks like green, flaky pastry are supported in perspex cradles. Within each fragment, layers of something that was once metal have been squashed together, and are now covered in calcareous accretions and various corrosions, from the whitish tin oxide to the dark bluish green of copper chloride. This thing spent 2,000 years at the bottom of the sea before making it to the National Archaeological Museum in Athens, and it shows.

But it is the details that take my breath away. Beneath the powdery deposits, tiny cramped writing is visible along with a spiral scale; there are traces of gear-wheels edged with jagged teeth. Next to the fragments an X-ray shows some of the object's internal workings. It looks just like the inside of a wristwatch.

This is the Antikythera Mechanism. These fragments contain at least 30 interlocking gear-wheels, along with copious astronomical inscriptions. Before its sojourn on the sea bed, it computed and displayed the movement of the Sun, the Moon and possibly the planets around Earth, and predicted the dates of future eclipses. It's one of the most stunning artefacts we have from classical antiquity.

` It truly seems out of place, being not only the first geared mechanism known, but also being over a thousand years ahead of Europe's invention of astronomical clocks. Nobody knows who first invented them, nor has anyone found any similar artifacts from that time.
` Why, if someone made such an amazing device, was this knowledge not preserved through the ages? It was truly an amazing advancement for ancient technology, though strangely, it has not been widely recognized as such in the modern world.
` To see just how sophisticated this device really was, a retired former curator at the Science Museum in London by the name of Michael Wright decided to reconstruct what it must have been like before it had spent those two millennia being corroded by salt water.
` Marchant describes his work:

The mechanism is contained in a squarish wooden case a little smaller than a shoebox. On the front are two metal dials (brass, although the original was bronze), one inside the other, showing the zodiac and the days of the year. Metal pointers show the positions of the Sun, the Moon and five planets visible to the naked eye. I turn the wooden knob on the side of the box and time passes before my eyes: the Moon makes a full revolution as the Sun inches just a twelfth of the way around the dial. Through a window near the centre of the dial peeks a ball painted half black and half white, spinning to show the Moon's changing phase.

On the back of the box are two spiral dials, one above the other. A pointer at the centre of each traces its way slowly around the spiral groove like a record stylus. The top dial, Wright explains, shows the Metonic cycle — 235 months fitting quite precisely into 19 years. The lower spiral, according to the research by Edmunds and his colleagues, was divided into 223, reflecting the 223-month period of the Saros cycle, which is used to predict eclipses.

To show me what happens inside, Wright opens the case and starts pulling out the wheels. There are 30 known gear-wheels in the Antikythera Mechanism, the biggest taking up nearly the entire width of the box, the smallest less than a centimetre across. They all have triangular teeth, anything from 15 to 223 of them, and each would have been hand cut from a single sheet of bronze. Turning the side knob engages the big gear-wheel, which goes around once for every year, carrying the date hand. The other gears drive the Moon, Sun and planets and the pointers on the Metonic and Saros spirals.

` If this is not enough for you, there are also photos of the front and rear of the device that you can readily view. Now, looking at these, you might ask; in the first century, who could have made such a wonderous device as this? There are, unfortunately, no inscriptions to tell us who it could have been - however, there are a few clues as to when it was built.
` Clue #1: In the 1970's, Jacques Cousteau found coins at the site of the shipwreck which were made a bit after 85 B.C. And, according to the Edmunds 2000 paper, it could had been used for perhaps 15 to 20 years before that. So, it falls somewhere in the early first century B.C.
` Clue #2: This ship had been carrying statues, silver coins from Pergamon and Rhodes-style vases, traveling the middle of a shipping route from east to west Aegean, probably headed for Rome where Greek art, philosophy and technology were well-appreciated.
` Apparently, Rhodes was like the astronomy capital of the Roman empire, and in the first century B.C., Posidonius had an astronomy school going there.
` Clue #3: The first century Roman lawyer/consul, Cicero, who studied on Rhodes, wrote in De Natura Deorum II that his friend, Posidonius himself, had 'recently' made an instrument "which at each revolution reproduces the same motions of the Sun, the Moon and the five planets that take place in the heavens every day and night".
` However, since the device has been dated to have been built after that was written, it couldn't have been Posidonius'. Even so, there has apparently been another, which I'll get to in a moment.
` Evidently, this Antikyhtera mechanism wasn't completely unique, though there evidently weren't many of them around. So, who built it? According to Edmunds, it was apparently inspired by the work of the great astronomer Hipparchus (he worked in Rhodes from 140 B.C. until his death in 120 B.C.), who was the reason Posidonius had started an astronomy school on Rhodes.
` The logic behind the assessment is this:

One of the wheels connected to the main drive wheel moves around once every nine years. Fixed on to it is a pair of small wheels, one of which sits almost — but not exactly — on top of the other.
` The bottom wheel has a pin sticking up from it, which engages with a slot in the wheel above. As the bottom wheel turns, this pin pushes the top wheel round. But because the two wheels aren't centred in the same place, the pin moves back and forth within the upper slot.
` As a result, the movement of the upper wheel speeds up and slows down, depending on whether the pin is a little farther in towards the centre or a little farther out towards the tips of the teeth (see illustration on 'Archaeology: High tech from Ancient Greece').

The researchers realized that the ratios of the gear-wheels involved produce a motion that closely mimics the varying motion of the Moon around Earth, as described by Hipparchus. When the Moon is close to us it seems to move faster. And the closest part of the Moon's orbit itself makes a full rotation around the Earth about every nine years.
` Hipparchus was the first to describe this motion mathematically, working on the idea that the Moon's orbit, although circular, was centred on a point offset from the centre of Earth that described a nine-year circle. In the Antikythera Mechanism, this theory is beautifully translated into mechanical form. "It's an unbelievably sophisticated idea," says Tony Freeth, a mathematician who worked out most of the mechanics for Edmunds' team. "I don't know how they thought of it."

"I'm very surprised to find a mechanical representation of this," adds Alexander Jones, a historian of astronomy at the University of Toronto, Canada. He says the Antikythera Mechanism has had little impact on the history of science so far. "But I think that's about to change. This was absolutely state of the art in astronomy at the time."

Wright believes that similar mechanisms modelled the motions of the five known planets, as well as of the Sun, although this part of the device has been lost. As he cranks the gears of his model to demonstrate, and the days, months and years pass, each pointer alternately lags behind and picks up speed to mimic the astronomical wanderings of the appropriate sphere.
Almost everyone who has studied the mechanism agrees it couldn't have been a one-off — it would have taken practice, perhaps over several generations, to achieve such expertise. Indeed, Cicero wrote of a similar mechanism that was said to have been built by Archimedes. That one was purportedly stolen in 212 BC by the Roman general Marcellus when Archimedes was killed in the sacking of the Sicilian city of Syracuse. The device was kept as an heirloom in Marcellus' family: as a friend of the family, Cicero may indeed have seen it.

` Indubitably, this is true: In De Re Publica, Cicero mentioned this device built about 150 years previous by Archimedes, which was demonstrated to him by Gallus: "And when Gallus moved the globe, it was actually true that the moon was always as many turns behind the sun on the bronze contrivance as would agree with the number of days it was behind in the sky. Thus the same eclipse of the sun happened on the globe as would actually happen."
` So, what happened to these devices? Perhaps they were destroyed because they were a) not much appreciated by common folk, and b) made of bronze, the perfect material for making weapons and other things and valued more as such. This would also explain why nine of the Athens museum's paltry ten major bronze sculptures were found in shipwrecks. As Wright puts it; "We only have this because it was out of reach of the scrap-metal man."

` Perhaps such technology had been carried along after all - a Byzantine sundial from the sixth century has four gears left and may have had at least eight for use as a model to keep track of the sun and the moon.
` In the eighth and ninth centuries, the rise of Islam resulted in Greek works to be translated into Arabic - perhaps they had read of such devices? In 1,000 A.D., al-Biruni described a device similar to the Byzantine sundial, which he called a "box of the moon". There is also a seven-geared astrolabe at the Museum of the History of Science in Oxford that models the sun and moon dating from 1221 or 1222, inscribed in Arabic.
` And yet, the Antikythera device is much more complex than those until the rise of clockwork devices in Western Europe, including St Albans clock (made by Richard Wallingford) from 1330, which models the motions of the sun, moon and planets. In addition to that, the clock Giovanni de'Dondi built in Padua, Italy, displays the eclipse cycles. They are so grandiose that the portion that tells time "seems incidental".
` So, were they discovered apart, or was the tradition passed down from the Moslems? Well, since clockwork mysteriously appeared in Europe right as their knowledge had spread out to Europe after the fall of Baghdad, it seems logical to attribute the clockwork to them. On the other hand, skills to build those things are generally left out of such texts, and so anyone relying on them would have to work very hard to make it work right.
` Also, if this tradition had been passed down through the generations, then why did the technology develop further over the years? The Antikythera mechanism was wildly complex while its 'descendents' did not live up to its reputation. Considering that medeival Europe's introduction to clockwork took off, introducing such new devices as clocks, why did this not happen in Greece?
` According to a historian of sciences at Imperial College, London, Serafina Cuomo, says that the Greeks just weren't that interested in making accurate timepieces. They made many devices powered by clockwork, hot air and water, but instead of making clocks or steam engines, they used them as demonstration models of philosophical principles. Philosophy, says David Sedley of the University of Cambridge, was what was really important to their entire culture.
` Such devices also may have indicated social status; amaze your friends and colleagues to earn respect! And, to up the demand, Romans also hungered for such Greek philosophers and their devices.
` Therefore, such mechanisms may not really have been built in order to further science so much as serve as important cultural works, demonstration of their cutting-edge astronomy as well as earning prestige. If you were to improve upon them, you would basically be building a better status symbol rather than seeing if it could do something they had no pressing need for, such as knowing exactly which minute on the hour it was: Their water clocks were good enough.
` And as for steam engines and other devices that could replace human labor, it may not have occurred to many a Greek to invent such things, as they also would have been superfluous: Why build a robot to do your work for you when you already have human slaves?
` Another reason why they did not invent mechanical clocks is probably because they lacked an important idea that the medeival Europeans used to make clocks work unaided - weights. Their astrological clockwork devices were powered by dripping water, which can only drive so many gears: This is why the Antikythera Mechanism apparently had to be cranked by hand.

` This whole thing makes me wonder; what if all our records from today were lost? What would people from thousands of years in the future make of our artifacts? The cars would all have rusted, our computers would have disintegrated... would anyone actually know that we successfully went to the moon in the 20th century?
` Without records, history is very hard to decipher. When the library of Alexandria was burned down, what insights and documents on the way of life were destroyed? Thank goodness we have plenty of records today... though most of them are electronic and therefore susceptible to power outages and gigantic magnets. If a giant magnet were to land on earth and erase all hard drives on earth, we would lose a gigantic percentage of information (mostly junk, but still...).
` Hmmm. Well, I'm rambling again. Yeah, I'm sleep deprived. Got a long drive ahead of me. G'night.

3 comments:

Galtron said...

That's interesting! Those ancients could of made mechanical clocks, they just didn't think they needed them!
Now we can't imagine life without them!
It probably started when people discovered that having an accurate clock really helps to navigate the ocean, so people struggled to invent a good watch. Needless to say it has been helpful!
We know now that human slaves are inferior to machines, as well! Our economy used to rely on slaves, but now we cannot do without machines at factories because they can do so much more work than people can!

That's a funny thing -- it takes revolutions and malcontent to start something big! (for better or worse.) The problem doesn't generally seem to be "do you have the means?" but "do you have the need?" Ergo, progress!

S E E Quine said...

` Darn IE to heck for crashing every several minutes! ARRGH! ...Attempt #3 from memory:

` That's really interesting, Galtron! I don't know why I didn't point that out myself!
` Indeed, just this week I attended an extra-credit lecture hosted by my teacher where she talked about the characteristics of people's attitudes (or temperaments or personalities or something).
` The color red indicates a characteristic whereby the person likes to have control of situations, pursuing goals, and getting more than what they have.
` White is like the opposite kind of thing, they don't like to rock the boat and avoid conflict and challenge.
` When she asked the class why white is a trait not often seen in college, the class answered: "Because people who are predominantly white are happy with what they have."
` Indeed, it is a virtue to be happy, both if you haven't got much or if you've got it all! (Though if you think you require something stupid like TV to be happy, it's a sign of brainwashing.)
` Reds tend to strive to get better at things, and create new ways of doing things that will improve life - for themselves and/or others. They are our leaders and revolutionaries.

*licking a naked man break*

` As I was saying, there are people who will say "We've got it perfectly good now. Why build something we don't need?"
` When a need arises, however, those who don't resist change will want to fit that need. (Usually, this is a good thing.) For example, the printing press, the sewing machine and their modern descendents have improved life considerably.
` The drive to make gold has resulted in modern types of chemistry equipment, along with (eventually) the knowledge of exactly why you can't combine chemicals to make gold!
` In fact, these small technological and social improvements have gotten us on the moon! (Which reminds me of an upcoming post I'm really proud of....)
` Do we need to improve our lives or not? Well, I'm sure we do not need something like a Blackberry to live well-rounded lives, however it may accidentally lead us to other technological breakthroughs.
` For example, the technology of SETI - while it is somewhat questionable unless we actually do find extraterrestrial life - has led to bettering other types of technology (including breast cancer scanners).
` Computers are decidedly very useful at doing tasks and helping scientists figure things out, and can actually do things that we alone cannot!
` And yet, though I don't remember the history of computer development very well, I know that a lot of computer development had to do with war technology that was absolutely needed, including WWII code-cracking machines!

` Basically, my loosely-constructed point is; you cannot improve anything unless you do something and make some kind of progress!

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