Arcadia Discussion Zone

On BBC 4 this evening Thu 10 May 2012 21:00
The Two-Thousand-Year-Old Computer

"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."

http://www.bbc.co.uk/programmes/b01hlkcq

Paddy

Anticythère, the stronghold of the Cilician pirates until they got a good whomping by Pompey the Great.

and....the island hosts the largest breeding colony of Eleonora's Falcon (Falco eleonorae) in the world.

which reminded me of ...."Il monte à bord. Une carte de visite – « Mr et Mme Labouisse » - épinglée sur la porte prouve qu’on ne s’est pas trompé de bateau. Charlot toque. Silence. Au plafond est peinte une rose des vents dont le nord est signalé par un ange à peau noire et aux ailes déployées. Il s’agit évidemment d’un rébus sur Eléonore = ailé au nord, funèbre hommage du capitaine Labouisse à sa créole disparue. Silence encore. Charlot griffonne son adresse et le but de sa visite sur un bout de papier et regagne la chaloupe".

the ship in which this device/mechanism was found, was either bound from Rhodes to Rome or roaming from Rome to Rhodes, bearing in mind that Rhodes was a maritime state which had a reputation for scientific research... btw, i nearly wrote Rodez there by mistake

Poseidonios of Rhodes was the man....some fragments of his writings on astronomy survive through the treatise by Cleomedes, On the Circular Motions of the Celestial Bodies, the first chapter of the second book appearing to have been mostly copied from Poseidonius.
Poseidonius constructed an orrery, which is a mechanical device that illustrates the relative positions and motions of the planets and moons in the Solar System in a heliocentric model. (could this be the Antikythera mechanism ?). Posidonius's orrery, according to Cicero, exhibited the diurnal motions of the sun, moon, and the five known planets.
He appears to have moved with ease among the upper echelons of Roman society as an ambassador from Rhodes and he associated with some of the leading figures of late republican Rome, including Cicero and Pompey, both of whom visited him in Rhodes. Posidonius met Pompey when he was Rhodes's ambassador in Rome and Pompey visited him in Rhodes twice, once in 66 BCE during his campaign against the pirates and again in 62 BCE during his eastern campaigns, and asked Posidonius to write his biography.

A little 3D reconstruction I did some five years ago now.

The whole mechanism was turned by means of a handle on the side.

Upon the front dial was engraved the Egyptian calendar, but in Greek. The two balls on the front are the sun and moon. The moon revolves as it turns to show its phases through the year. Probably all the known planets were represented behind the front dial but they are missing. There is room for them though. A set of movable pins allowed the front dial to turn to represent the years within a four year cycle, ie it was compensated for leap years.

The back shows evidence of being a later addition and the box that housed the mechanism was adapted for it. The back shows a Lunar/Solar calendar and Eclipse prediction.:










A cross section of the cogs I worked from. Originally printed in Nature.

Very little is known about ancient celestial navigation, besides indisputable proof that it did, in fact, occur. It is worth noting, however, that the man who invented trigonometry and first scientifically catalogued the stars' positions was Hipparchus of Rhodes and that, in more than one ancient system of latitude and longitude, the meridians crossed at Rhodes..... The Rhodian navy displayed in a long and distinguished operational history an almost uncanny ability to function and maintain unit cohesion at night.

Agreed. Hipparchus and Rhodes is the likely origin of this device. The Antikythera shows signs of adaptation and repurposing of cogs used in it, so it was the result of an evolutionary process. There are other accounts of similar devices that are now lost but were seen by contemporaries.

There was no similar metal cog-wheeled device for 1,000 years until the advent of the first mechanical clock mechanisms that used metal cogs. The cogs in the Antikythera are fairly crudely cut though - the teeth are straight cut rather than curved to relieve the side pressure. An awesome and astonishing achievement all the same.

Travel and communication between the UK and Greece, Egypt and elsewhere was widespread in Bronze Age times, I think Robert Graves proved that beyond much doubt. Celestial navigation in the clearer skies of those days would have formed a big part of that ability.

I just watched the BBC programme. They seemed to come to the conclusion the Antikythera was the work of Archimedes of Syracuse in Sicily, not Hipparchus of Rhodes. I am sure those experts know more than I.

Having built this Antikythera machine in a computer, with the correct number of cogs, teeth and axles, in positions where the mechanism could actually have worked, I found it a sobering experience and one that gives me the feeling of utmost respect for the originators of this device. It is not trivial by any means. You try drawing it.

That modern engineers can also devise the missing pieces featuring the known planets of the day too is equally sobering. I wish I had the data to add to my model.

As for the repeated BBC voiceover that this was the world's earliest known computer, I personally refute that entirely. The stone circles, not only of Britain but across Europe and Asia and north Africa too bear witness to a precision and knowledge of astronomy that causes us to wonder how they could build such structures.

It is currently fashionable to dispute astronomical claims at megalithic sites, largely due to the recent poo-pooing by Aubrey Burl and the uncertainty of some claims once made by Professor Alexander Thom. Those investigating sites today where lunar standstills and other solar and lunar phenomena are recorded in stone feel certain that here are far more ancient claims to examples of computational equipment, ie computers, than the Antikythera.

Now on BBC iPlayer
http://www.bbc.co.uk/iplayer/episode/b01hlkcq/The_TwoThousandYearOld_Computer/

Paddy

The gears are different between the antikythera mechanism and the Archimedes gears. The antikythera mechanism with triangular clogs would have hardening or sticking points in the rotation whereas the Archimedes gears would not as they are identical in curvature to modern day cogs.

I like that. Hence the word sabotage, putting a clog in the works. (sabot being a clog in French)