All the Best Bits: Discovering a 2,000 Year Old Computer

Every scuba diver, myself included, dreams of finding that priceless artifact. Will it be the next guided wreck dive in the Caribbean? Unlikely. I clearly need to be diving in Mediterranean, or Agean, or Latin American waters for any kind of chance at all. Truth be told, I'm not sure what I would have done had I fished this hunk of corroded metal-encrusted rock out of the ocean on a snorkeling trip.

Elias Stadiatos, a Greek sponge diver, wasn't really sure what he had found either when he discovered an ancient cargo ship wreck off Antikythera island just before Easter in 1900. Fortunately, he found it amidst a series of more traditional artifacts, and so it has circulated through museums ever since, and now resides in the Athens Archeology museum. Here is an image from LiveScience that shows all the parts that were eventually associated with this odd widget.

Earlier efforts at reconstruction were mainly focussed on the visible inscriptions and lettering on the outer plate surfaces, and highlighted a very interesting application of classical image processing with programs like Photoshop to archaeological discovery.

... "Chrysoun Sfairion": the little "Golden Sphere"!

These resulted in a number of reconstructions of the outer casings to show dials related to the motion of the Sun and the Moon and the zodiac.

In the 1930s and 50s, several groups used progressively improved X-Ray images in an attempt to divine the internal mechanism with decent success,

to ultimately result in some very nice reconstructions of the internal mechanisms, which turned out to model the motion of several planets as well.

All of this is simply wondrous in terms of early mechanical realization of solar system models proposed by
ancient Greeks, in effect a mechanical computer that would simulate the solar system.

More recently however, a company named X-Tek used their latest 3D X-Ray Tomography machine (an X-Ray cousin to the latest MRI machines) to make much more detailed 3-D images of the components hidden within the block of sediment. The images are amazing:

An old film radiograph of the largest fragment of the Antikythera Mechanism, taken in 1980.

A single 2D CT slice of the largest fragment of the Antikythera Mechanism from X-Tek's new 3D CT data

Using these new images, researchers at the Universitys of Cardiff and Athens published a paper in the November 30, 2006 issue of Science detailing that the internal componentry of this mechanical computer surpassed anything to emerge over the succeeding 1000 years. From the article:

Named after its place of discovery in 1901 in a Roman shipwreck, the Antikythera Mechanism is technically more complex than any known device for at least a millennium afterwards. Its specific functions have remained controversial because its gears and the inscriptions upon its faces are only fragmentary. Here we report surface imaging and high-resolution X-ray tomography of the surviving fragments, enabling us to reconstruct the gear function and double the number of deciphered inscriptions. The mechanism predicted lunar and solar eclipses on the basis of Babylonian arithmetic-progression cycles. The inscriptions support suggestions of mechanical display of planetary positions, now lost. In the second century bc, Hipparchos developed a theory to explain the irregularities of the Moon's motion across the sky caused by its elliptic orbit. We find a mechanical realization of this theory in the gearing of the mechanism, revealing an unexpected degree of technical sophistication for the period.
An X-ray scanner revealed a complicated arrangement of 30 precision, hand-cut bronze gears. The team has inferred that there were at least seven more gears. "It is only when you get medieval astronomical clocks that you go beyond this in complexity," said Prof Edmunds. Speculation about how this marvel was used continues and the team is now building a virtual version in a computer.

Prof Edmunds said: "It makes you wonder what they would have achieved if the Romans hadn't taken over and put a stop to things. Would they have had a man on the Moon by AD300?
"It sounds ridiculous, but if they were able to construct something as technically brilliant as this, it's not complete fantasy."