by Decoding the Heavens- Solving the Mystery of the World's First Computer (retail) (epub)
When the day came it was like a carnival, with all of the researchers taken aback by the strength of feeling among the Greek public. Nearly 500 people came to the open session, even though there wasn’t room for them in the hall, so the crowd overflowed down the aisles and out of the doors. After Freeth spoke (his words translated into Greek by his colleague Seiradakis), he got a standing ovation that he thought would never end. Every spare moment during the day was taken up by journalists eager for press interviews, and tearful members of the public rushed up to him and the others to shake them by the hand.
After so many lonely years of battling every possible obstacle, Michael Wright found the recognition instantly afforded to Tony Freeth and his team almost too much to bear. He very nearly didn’t attend the Athens meeting at all, but in the end he couldn’t stay away. Nevertheless his wife Anne stayed at his side to keep him calm. In his talk, later described by one of the other speakers as ‘half an hour of continuously controlled rage’, he reminded the audience that the latest team was not the only one to work on the mechanism. He started with the story of how, after 20 years studying it, Derek de Solla Price had written to an acquaintance about his final paper on the Antikythera mechanism. ‘As far as I am concerned,’ Price had written, ‘[this] wraps the whole thing up.’
‘Price seems to have had enough; and I can sympathise,’ Wright told the audience, struggling to control his emotions. ‘I have studied this artefact for about as long as he did, and whatever pressure he experienced, I can match it. My employer forbade my research, so I have conducted it in my own time and at my own cost, in the face of professional and personal difficulties: intrigue; betrayal; bullying; injury; illness; loss for years of all my data (some still not recovered); the long illness and death of my collaborator; and more.
‘Even so . . .’ He paused. ‘I am still here.’
He outlined his work, explaining carefully how his radiographs had shown nearly every part of the mechanism’s inner workings years before Freeth’s team had seen them. He didn’t say it in his talk, but he knew that if he had only known about Fragment F he would have got the rest of it as well. He brought his model to show the audience, adjusted to reveal the new arrangement of the lower back dial and lunar mechanism, as Freeth had described it. It took just three hours to make the necessary changes, he said pointedly (see diagram).
On a couple of points he insisted that Freeth was wrong. For example, Freeth played down the possibility that the device showed the planets, despite the inscriptions devoted to this subject. He described the device as an ‘eclipse predictor’. But although this emphasised the part of the mechanism that Freeth had discovered, Wright felt it missed the point. It was like finding part of a grandfather clock with a Moon display from which the hour and minute hand had been lost, and announcing that it had been a Moon calculator. Wright remained convinced that the device was primarily a planetarium.
And he stuck to his interpretation that the spiral on the lower back dial had started and finished at the top, not the bottom as Freeth had it. Tony Freeth’s moustache bristled when he heard that. This was meant to be a celebration of his own project, yet Wright seemed intent on claiming every discovery for himself. Freeth couldn’t resist challenging him when the floor was opened to questions.
‘You’ve got the spiral wrong,’ he said. ‘We’ve checked it with the CT, and it starts at the bottom.’
Wright smarted. No matter that the orientation of the spiral was a mere detail. He spoke through clenched teeth, convinced that Freeth was trying to humiliate him.
‘I’ve measured it,’ he said. ‘And it runs this way round.’
Afterwards, Alexander Jones and John Steele, two experts on ancient astronomy who had attended the conference, came up to Wright.
‘Don’t take a hacksaw to your model just yet,’ they advised.
They had noticed something from the slides that Freeth and the others missed: mysterious letters at the bottom of the eclipse glyphs that Freeth hadn’t been able to interpret ran alphabetically around the dial, and they showed that Wright was correct about the orientation of the spiral. They were reference letters like those on the parapegma on the front, probably referring to pieces of text around the dial that gave further detailed descriptions of each predicted eclipse.
Then it was time to eat. Wright, Freeth, Roger Hadland, Tom Malzbender, Mike Edmunds, Xenophon Moussas, Yanis Bitsakis and the others all sat down around the same dinner table for one more cry of ‘More gears!’ Friends or not, they were all part of the same wonderful adventure. As they ate, the news of the incredible Antikythera mechanism sped around the globe. The story zipped down telephone wires, flew through the air, bounced off satellites, inked itself onto newspaper pages and appeared on television and computer screens in every continent of the world. At last, Derek de Solla Price’s dream was starting to come true. History was being rewritten, and soon everyone would know that the ancient Greeks had built a clockwork computer.
More than a hundred years after Captain Kontos and his crew raised the Antikythera mechanism from its resting place at the bottom of the sea, the mysterious device had finally been decoded. Whoever turned the handle on the side of its wooden case became master of the cosmos, winding forwards or backwards to see everything about the sky at any chosen moment. Pointers on the front showed the changing positions of the Sun, Moon and planets in the zodiac, the date, as well as the phase of the Moon, while spiral dials on the back showed the month and year according to a combined lunar-solar calendar, and the timing of eclipses. Inscribed text around the front dial revealed which star constellations were rising and setting at each moment, while the writing on the back gave details of the characteristics and location of the predicted eclipses. The mechanism’s owner could zoom in on any nearby day – today, tomorrow, last Tuesday – or he could travel far across distant centuries.
For the first time in history it was possible to revisit the past and to predict the future. It was possible to control time itself.
And yet, this can’t be the end of the story. Who could have made such a device? And why?
10
Old Man of Syracuse
I know that my day’s life is marked for death.
But when I search into the close, revolving spirals of stars,
my feet no longer touch the Earth. Then,
by the side of Zeus himself, I take my share of immortality.
— ATTRIBUTED TO PTOLEMY
THE GREAT OLD circle of Stonehenge on the chalk downs of Wiltshire is one of the world’s most awe-inspiring monuments. Its huge stone slabs were hauled into place in various phases during the third millennium BC to serve as a temple dedicated to the worship of the Sun. When the Sun rises on the summer solstice, the longest day in the year, its first rays shine straight down the avenue that leads to the circle and into the open arms of a horseshoe of stones that stands in the centre.
Around 2500 BC the circle’s 80 bluestones were lugged to Wiltshire from high in the South Wales mountains. We don’t know why the builders undertook such a huge challenge; presumably the stones or their place of origin were of great religious importance. But they weren’t alone in their efforts. As the Britons edged their huge load forwards on rafts and rollers, builders working more than 2,000 miles away for the Egyptian pharaoh Khufu were completing their own mammoth project. They cut two million limestone blocks from a quarry in Giza, and piled them high into the most spectacular pyramid ever built.
The north face of the Great Pyramid is aligned almost perfectly to the celestial north pole – the point around which all the stars in the sky appear to spin – with an error of less than a twentieth of a degree. The shafts inside the pyramid may also have been dug to point precisely to the positions of particular constellations in the sky. This is hard to prove, but we do know that many of the Egyptian gods and goddesses were associated with constellations or celestial bodies. The constellation Orion represented Osiris, god of rebirth and the afterlife, while the
Milky Way symbolised the sky goddess Nut giving birth to the sun god Re.
In fact, as far back in history as it is possible to look, ancient societies everywhere were obsessed with the heavens. This makes sense from a practical point of view because to a large extent the days and seasons ruled people’s lives, but there was a strong spiritual or religious aspect to it too – nearly every culture worshipped gods who lived in the sky. Back then there wasn’t much to do at night but look up, and without the electric glare from modern towns and cities the heavenly lights and bursts and trails would have made compelling viewing. Later, observations became more systematic and the ability to track and predict celestial movements would have been a vital part of the transition of any culture from hunter-gatherers into an organised society capable of farming and navigation.
The ancient Greeks were no different and as soon as there are written records we see references to the heavens as a central part of life. In Homer’s Iliad, written down in the eighth century BC, the blacksmith god Hephaistos makes a shield for Achilles and decorates it with images of the constellations. And Homer knew that sailors could navigate by the stars – in the Odyssey his hero kept the Bear on his left in order to sail to the East. The next surviving work of Greek literature is a poem by Hesiod called Works and Days, written around 650 BC. It told farmers what work needed to be done at different times of year, according to which constellations were rising and setting at dawn. These relationships were probably known long before they were written down and would have been remembered as oral poems, perhaps even back to the emergence of agriculture in the region thousands of years before.
Traditionally, the Earth was simply thought of as a flat disc, floating on the ocean like a shield. But by the sixth century BC speculation about the form of the universe was common. Anaximander described a cylindrical Earth suspended in the centre of the cosmos, surrounded by fiery rings. Philolaus, a follower of Pythagoras, suggested that all the celestial bodies including Earth were circling a central fire. The Sun shone with light reflected from this fire, but we didn’t see it directly because a counter-Earth (Antichthon) moved around just inside our orbit, always standing in the way. A little later Aristotle adopted the idea of a spherical Earth surrounded by a heavenly realm, with separate circles or spheres carrying round the Sun, Moon, five planets and the stars, which were fixed in place on their sphere like fairy lights poking through cardboard.
In the third century BC an astronomer called Aristarchus worked out that the Sun was many times bigger and heavier than the Earth, and proposed that the Earth must therefore go around the Sun rather than the other way round (he also suggested that day and night were caused by the Earth spinning on its axis). But most of his peers thought it was a terrible idea. For a start, if we were hurtling through space, we’d all fly off. The developing theory of epicycles could account for the movements of the Sun, the Moon and planets around the Earth fairly well, so replacing this with circular motions of the Earth and planets around the Sun didn’t make astronomers’ models any more accurate (it would take Kepler’s elliptical orbits many centuries later to make sense of the heliocentric view).
By the time that the Antikythera mechanism was built – around the beginning of the first century BC – Aristotle’s model was more or less accepted, with the wandering motions of the planets explained by epicycles. Astronomers were starting to put numbers to these geometric models to describe the periods of the planets, and the variations in the apparent motions of the Moon and the Sun. The Antikythera mechanism therefore comes from a society for which the nature of the heavens was crucially important, and from a period when astronomers were making their first attempts to describe the universe mathematically. From that point of view it makes sense. But to see these equations converted into a bronze machine is still far beyond anything that we would have expected from the supposedly theoretical Greeks. So what genius came up with the idea, and why?
It is rarely possible to attribute any ancient artefact to a specific individual – unless it happens to be signed. We don’t know enough about who was around in the first century BC, and even for those rare characters that we have heard of, we’re generally only aware of a tiny fraction of their achievements. It is quite possible – perhaps even likely – that the Antikythera mechanism was dreamed up by someone whose name is forever lost to history.
Bearing this in mind, we can at least speculate based on the clues we have. We know that the wrecked ship on which the Antikythera mechanism was found probably sailed from Pergamon on the Asia Minor coast between 70 and 60 BC, stopping off possibly at Alexandria and almost certainly at Rhodes, on the way to Rome. Pergamon and Alexandria were key centres for trade, and both would likely have boasted the most sophisticated metalworkers around.
But that may not have been enough. The astronomy embodied in the Antikythera mechanism was state of the art, and would presumably have needed the input of a major astronomer. We don’t know of any astronomers working in Pergamon at the time. By the first century BC the Romans had taken over the city, so the activity of scientists there may have been waning. Scientific activity at Alexandria was also at a low, after the Roman-friendly king Ptolemy VIII expelled the city’s Greek scholars a few decades earlier. Rhodes on the other hand, although its citizens had to be careful not to upset the Romans, was still nominally independent, and one of the few places where Greek academics could work relatively unhindered.
When looking for big names on Rhodes, you don’t get much bigger than Hipparchus, one of the most important astronomers of the ancient world. He was born around 190 BC in Nicaea, on the shores of Lake Iznik in what is now Turkey. He moved to Rhodes for the later part of his career, where he made observations in the island’s northern hills between 147 and 127 BC.
Hipparchus’s work was meticulous and systematic. If he had a purpose in life it seems to have been to persuade other Greek astronomers that their models and theories were useless if they didn’t match accurately with observations, and he was not afraid to criticise others if he thought they were wrong. Nearly all of Hipparchus’ writings are lost – once the Alexandrian astronomer Ptolemy wrote his epic Almagest in the second century AD it superseded all the astronomy that went before (for better or worse), and nothing much else was copied. But we do have one minor work that gives us a glimpse into Hipparchus’ character. It is a commentary on one of the most popular poems of antiquity, the Phenomena by Aratus. Like Works and Days it listed the rising and setting of constellations through the year, this time along with expected weather patterns. It was much loved for its literary style, but the charm was apparently lost on Hipparchus. He slated it for its lack of accuracy.
Ptolemy based much of his work on that of his Rhodian predecessor, who he described as a ‘lover of truth’, and we know from the Almagest that Hipparchus was one of the first – if not the first – to put numbers to the Greeks’ geometrical models of the cosmos. Among other things he compiled the first star catalogue, developed trigonometry, discovered the precession of the constellations through the sky, and may have invented the astrolabe. Of particular interest to us, he was the first to describe mathematically the varying motions of the Moon and Sun, and the pioneering equation he used for the Moon is almost exactly reproduced by the undulating pin-and-slot in the Antikythera mechanism. We don’t know of any other astronomer of the time who could have thought of it.
In much of his work Hipparchus was influenced by the precise methods of astronomers from Babylon. They saw any irregularities in the natural world as conveying messages about impending events – usually bad ones. This included the births of deformed animals or people, animals behaving oddly or strangely formed plants. But the most important sources of such messages were the heavenly bodies, and Babylon’s astronomer-priests kept them under close surveillance. It was like watching a soap opera set in the sky – the Milky Way was known as the ‘river of heaven’ and the erratic planets were seen as gods riding about the celestial countryside as living men tra
vel on Earth.
Similar beliefs were held across ancient Mesopotamia – a broad area between the Tigris and Euphrates rivers, roughly corresponding to modern-day Iraq, and parts of Turkey, Syria and Iran. The Babylonian empire was in the south of this region, while Assyria was in the north. Much of what we know about these omens comes from a series of Babylonian clay tablets called Enuma Anu Enlil, which contained lists of astronomical events and the omens derived from them. The tablets were discovered in the library of the Assyrian King Ashurbanipal in Nineveh on the river Tigris (near the modern city of Mosul in Iraq). Ashurbanipal reigned in the seventh century BC, but he collected old cuneiform texts from all over Mesopotamia and especially Babylon, and the omens themselves are thought to date back to the second millennium BC. The timings of the Moon’s phases, risings and settings of the planets and especially eclipses all bore messages about the well-being or otherwise of the king and his country. Some predicted floods or war or the quality of the coming harvest; others were more specific about the personal fate of the king. A typical example reads: ‘When in the month Ajaru, during the evening watch, the moon eclipses, the king will die. The sons of the king will vie for the throne of their father, but will not sit on it.’
The court astronomers concerned with monitoring these omens made daily observations of the state of the sky, so that they could keep their king informed of his impending fortune. This was crucial, because once a sign was spotted it was possible to avert the worst by carrying out the appropriate rituals. Often this involved performing lamentations or making offerings to the gods, but sometimes more drastic action was called for. One ritual involved taking a beggar from the street and sitting him on the throne for the duration of a lunar eclipse, so that the divined ill-fortune would befall him and not the temporarily abdicated king.