The Antikythera computer captured the ancient Greek passion for mathematics and especially geometry.
By Evaggelos Vallianatos
The second century BC was a time of the golden age of Greek science, and civilization centered in the kingdoms of the empire of Alexander the Great, especially in Alexandria, Egypt.
However, mainland Greece faced the aggressive Roman Republic soon thereafter. In 146 BC, a Roman army wiped out Corinth, Greece, which became a province of Rome. The victorious Romans did what all empire builders do: loot and rule.
Sometime in the first century, a rich Roman citizen or general on Rhodes loaded a giant boat with stolen Greek treasures. The ship headed for Rome, but it sunk in the stormy Ionian and Cretan Sea.
Two thousand years later in the spring of 1900, Greek sponge divers discovered the sunken ship loaded with ancient Greek treasures. The shipwreck had occurred in the waters of Antikythera, a tiny island between Crete and the Peloponnesian Peninsula.
Among statues, ceramic vases, coins, and earnings, there was a metal artifact by which the experts of the National Archaeological Museum in Athens were completely stumped. After they observed triangular teeth and Greek inscriptions on the artifact, they dubbed it ‘The Antikythera Mechanism.’
Greek and foreign scientists all found it immensely challenging to decipher the nature of the Antikythera device. They studied it for more than a century, and, indeed, analysis continues to this day.
The reasons for these extensive studies and great international interest in ancient Greek technology are complex, though clear. Here was a 2,200-year-old astronomical computer that simply had no precedent in history.
Clearly a work of incredible genius, it was made with interlocking bronze gears, that is, scientific technology. Scientists were shocked. After all, such technology was supposedly a product of modern times.
For several decades, no one had a clue as to who had conceived of the idea of an astronomical computer, how, and where it was built—or why the Greeks even needed such a high-tech gadget.
Some experts thought the Antikythera Mechanism was an astrolabe, a useful astronomical instrument but hardly comparable to the predictive power of the scientific technology of this extraordinarily complex computer.
Gears from the Greeks
One of the mid-twentieth century foreign experts who studied the Antikythera Mechanism in the National Archaeological Museum in Athens was Derek de Solla Price, an unusual scientist and scholar.
A British physicist and historian of science, he taught the history of science at Yale University.
He had experience in studying ancient Chinese scientific instruments and clocks. For about sixteen years, he immersed himself in the technological complexity and science embedded in the fragments of the Greek device and, in 1974, he published an article called “Gears from the Greeks.”
Price’s report opened the way to a more accurate evaluation of the Antikythera computer. Price declared that the Antikythera Mechanism was “one of the most important pieces of evidence for the understanding of ancient Greek science and technology.”
According to Price, the reason for this was that the complex gearing of the Antikythera Mechanism shows a more precise picture of the level of Greco-Roman “mechanical proficiency” than that coming out of the surviving textual evidence.
This “singular artifact,” he said of the Antikythera Mechanism, “the oldest existing relic of scientific technology, and the only complicated mechanical device we have from antiquity, quite changes our ideas about the Greeks and makes visible a more continuous historical evolution of one of the most important main lines that lead to our civilization.”
That device, once housed in a wooden case the size of a dictionary or shoe box, after surviving a tortuous path, became part of Western technological culture.
Price described the differential gear of the Antikythera Mechanism as the landmark of its high tech nature. This was the gear that enabled the Antikythera Mechanism to show the movements of the Sun and the Moon in “perfect consistency” with the phases of the Moon.
“It must surely rank,” Price said of the differential gear, “as one of the greatest basic mechanical inventions of all time.” It was this gear from the Greeks, and the clockwork culture that moved it along, that advanced the technology of cotton weaving in the eighteenth century. Eventually, the differential gear ended up in cars in the late nineteenth century.
Price complained that the West judged the Greeks from scraps of building stones, statues, coins, ceramics, and a few selected written sources.
Yet, when it comes to the heart of their lives and culture, how they did their work in agriculture, how they constructed the perfect building of the Parthenon, what kind of mechanical devices they had for doing things in peace and war, how they used metals, and, in general, what they did in several fields of technology, we have practically nothing from Greek history.
“Wheels from carriages and carts survive from deep antiquity,” he said, but there is nothing else from Ancient Greece, he said, which looks “anything like a fine gear wheel or small piece of mechanism. Indeed the evidence for scientific instruments and fine mechanical objects is so scant that it is often thought that the Greeks had none.”
Price died in 1983 and his legitimate question remains largely unanswered. In most cases, classical scholars have largely ignored Hellenic science and technology.
A stunning instrument of the heavens and the Earth
In 2005, a team of international scientists finally got to the bottom of the ancient Greek computer — or so they thought.
Scientists from two high tech companies, X-Tek from England, and Hewlett Packard from the US, joined the researchers and revealed the secrets of the astronomical device.
They concluded that the Antikythera Mechanism was the most sophisticated technology in the Mediterranean for more than a millennium. They published their reports in the November 30, 2006 and July 31, 2008 issues of the science magazine Nature.
According to the 2006 report, the Antikythera Mechanism “stands as a witness to the extraordinary technological potential of ancient Greece, apparently lost within the Roman Empire.”
A calculator and a calendar
The Antikythera computer was a practical machine which must have been widespread in the Greek world for centuries.
It was a calculator that read the stars, as well as being a calendar that connected the Panhellenic games like the Olympics to the phenomena in the natural world and the Cosmos.
Besides, the accurate calendar helped the Greeks to worship the gods at the same time each year.
The scientists who studied it were right that this “artifact of ancient gearwork” was more than a device of pure astronomy: “exhibiting longitudes of heavenly bodies on the front dial, eclipse predictions on the lower back display, and a calendrical cycle (on the upper back display).”
The mechanical universe of the Antikythera Mechanism
The first inscription on the back of the Antikythera Mechanism reads: “the spiral (ΕΛΙΚΙ) divided into 235 sections.”
This meant that one of the back dials was a spiral representing the 19-year Metonic Moon and Sun calendar of 235 months. The other back dial, known as Saros, predicted the eclipses of the Sun and the Moon.
Two circles enclosed the Cosmos on the front view. The outside circle represented the 365-day year. The inside circle was the Zodiac, an imaginary cosmic circle of 12 constellations around the Earth.
The front view also depicted the movement and position of the Sun, Moon, the phases of the Moon, planets, and prominent stars and constellations. The front inscriptions explained which constellations rose and set at any specific time.
Archimedes and Hipparchos
The ideas of Archimedes and Hipparchos gave substance to the brilliant
astronomical computer made by the Greeks.
In 1907, the German philologist Albert Rehm suggested the Antikythera geared device resembled the Sphere of Archimedes that the Roman politician and man of letters of the first century BC, Cicero, once saw in Rome.
This was part of the looted Greek treasures the victorious Roman general Marcellus had brought to Rome after his troops captured and looted Syracuse.
Agents of Marcellus assassinated Archimedes in 212 BC. Archimedes, a mathematical and engineering genius of the third century BC, was the father of mathematical physics and mechanics which made the Antikythera computer possible.
Cicero said the planetarium of Archimedes reproduced accurately the movements of the Sun and the Moon, including those of the planets (Venus, Mercury, Mars, Saturn, and Jupiter).
It also depicted the eclipses of the Sun and the Moon. Archimedes, like Aristotle, was crucial in the creation of the golden age of Greek science. He measured curved surfaces and applied mathematics to the study and understanding of nature.
He was also an astronomer who studied and measured the eclipses of the Sun and the Moon. Those measurements were important to the designers of the Antikythera Machine.
Archimedes, like the Antikythera Mechanism, deciphered the book of the Cosmos. He became the model for Galileo Galilei and Isaac Newton.
Like Archimedes, Hipparchos, the greatest Greek astronomer, made the Antikythera computer possible. From about 140 to 120 BCE he had his laboratory in Rhodes.
More than other Greek astronomers, he made use of the data collected by Babylonian astronomers. But like the rest of the Greek astronomers, he employed geometry in the study and understanding of astronomical phenomena.
He invented plane trigonometry and made astronomy the predictive mathematical science it is today.
The connection of Hipparchos to the Antikythera Mechanism is in the front bronze plate of the device, where pointers displayed the positions and movement of the Sun and the Moon in the Zodiac.
Hipparchos knew the moon moved around the Earth at different speeds. When the moon is close to the Earth, it moves faster than when it is farther from the Earth, when it slows down.
This is because the Moon’s orbit is elliptical, not the perfect circular movement the Greeks associated with the stars. Hipparchos resolved this difficulty with his epicyclic lunar theory, which superimposed one circular motion of the Moon onto another, the second movement having a different center.
The Antikythera Mechanism modeled the ideas of Hipparchos with one gearwheel sitting on top of another but located on a different axis. A pin-and-slot mechanism then reproduces the non-circular or elliptical orbit of the Moon.
A pin originating from the bottom wheel enters the slot of the wheel above it. When the bottom wheel turns, it also drives the top gearwheel.
However, the wheels have different centers and, therefore, the pin slides back and forth in the slot, which enables the speed of the top wheel to vary while that of the bottom wheel remains constant.
The Antikythera mechanism: a computer of heavens and civilization
Archimedes and Hipparchos provided the architecture of science and technology of this incredibly ingenious astronomical machine.
However, they, too, stood on the shoulders of giants like Aristotle who invented biology and tutored Alexander the Great, the general Ptolemy, and others who contributed to science and technology. Alexander conquered Persia and spread Hellenic culture all over the world.
Alexander made possible the great city of Alexandria, Egypt, which, under the leadership of his general Ptolemy, became the preeminent Greek polis of science and civilization in the ancient world.
Its museum/university and great library were the equivalent in books, knowledge, and brain power of the Library of Congress, MIT, Harvard, Yale, Oxford, and Cambridge universities today.
The Antikythera computer captured the Greek passion for mathematics, and, especially, geometry. This enabled them to simulate astronomical phenomena, thus creating an accurate universe with gears.
Francois Charette, professor of the history of natural sciences at Ludwig-Maximilian University in Munich, Germany, studied the Antikythera computer and concluded that “mind-boggling technological sophistication” must have been available to those who made it. He is right.
Ptolemy and his successors lavished gold and political support on the best and the brightest in the Greek world. They developed the culture and mind-boggling science and technology behind the astronomical computer.
The Antikythera computer was more than a mirror of scientific technology, however. It was the culmination of a golden age that enabled the Greeks to give birth to a remarkable civilization that eventually became the pillar of our own civilization.
Evaggelos Vallianatos, Ph.D., is a historian and environmental theorist. He is author of hundreds of articles and seven books, including The Antikythera Mechanism: The Story Behind the Genius of the Greek Computer (Universal Publishers, 2021).