In Our Time - The Antikythera Mechanism

Episode Date: December 12, 2024

Melvyn Bragg and guests discuss the 2000-year-old device which transformed our understanding of astronomy in ancient Greece. In 1900 a group of sponge divers found the wreck of a ship off the coast of the Greek island of Antikythera. Among the items salvaged was a corroded bronze object, the purpose of which was not at first clear. It turned out to be one of the most important discoveries in marine archaeology. Over time, researchers worked out that it was some kind of astronomical analogue computer, the only one to survive from this period as bronze objects were so often melted down for other uses. In recent decades, detailed examination of the Antikythera Mechanism using the latest scientific techniques indicates that it is a particularly intricate tool for showing the positions of planets, the sun and moon, with a complexity and precision not surpassed for over a thousand years.With Mike Edmunds Emeritus Professor of Astrophysics at Cardiff UniversityJo Marchant Science journalist and author of 'Decoding the Heavens' on the Antikythera MechanismAnd Liba Taub Professor Emerita in the Department of History and Philosophy of Science at the University of Cambridge and Visiting Scholar at the Deutsches Museum, MunichProducer: Simon Tillotson In Our Time is a BBC Studios Audio ProductionReading list:Derek de Solla Price, Gears from the Greeks: The Antikythera Mechanism (American Philosophical Society Press, 1974)M. G. Edmunds, ‘The Antikythera mechanism and the mechanical universe’ (Contemp. Phys. 55, 2014) M.G. Edmunds, ’The Mechanical Universe’ (Astronomy & Geophysics, 64, 2023)James Evans and J. Lennart Berggren, Geminos's Introduction to the Phenomena: A Translation and Study of a Hellenistic Survey of Astronomy (Princeton University Press, 2006)T. Freeth et al., ‘Calendars with Olympiad display and eclipse prediction on the Antikythera mechanism’ (Nature 454, 2008)Alexander Jones, A Portable Cosmos: Revealing the Antikythera Mechanism, Scientific Wonder of the Ancient World (Oxford University Press, 2017)Jo Marchant, Decoding the Heavens: Solving the Mystery of the World’s First Computer (Windmill Books, 2009)J.H. Seiradakis and M.G. Edmunds, ‘Our current knowledge of the Antikythera Mechanism’ (Nature Astronomy 2, 2018)Liba Taub, Ancient Greek and Roman Science: A Very Short Introduction (Oxford University Press, 2022)

BBC Sounds, music, radio, podcasts. This is in our time from BBC Radio 4, and this is one of more than a thousand episodes you can find on BBC Sounds and on our website. If you scroll down the page for this edition, you can find a reading list to go with it. I hope you enjoyed the programme. Hello, the Antikythera Mechanism is one of the greatest discoveries

in the history of marine archaeology, even though, when salvaged in 1900-worn, it seemed like just a lump of corroborated. it was bronze. It came from a 2000-year-old wreck discovered by Greek sponge divers and it was only when this dull lump broke up that its secrets began

to be revealed. It turned out to be an analogue computer of a complexity otherwise lost from the ancient world and not appearing again until the Middle Ages and it challenges our ideas of how advanced the peoples of that era really were.

With me to discuss the Antikythera mechanism are Mike Edmonds, Emeritus Professor of Astrophysics at Cardiff University. Lieber Taube, Professor Emerita in Department of History and Philosophy of Science at the University of Cambridge, and visiting scholar at the Deutsche Museum, Munich, and Joe Marchant, science journalist and author of Decoding the Heavens on the Antikythera Mechanism. Joe Marchant, I've called it an analogue computer. Can you describe what this object was in outline and what it would have looked like?

It was one of the most sophisticated and complicated objects that we have that survives from the ancient world. If you imagine a wooden box about the size of a shoe box filled with bronze gear wheels, so looking like clockwork, little bronze gear wheels with teeth all driving each other around, handle on the side to turn it with dials on the front and the back. And it was essentially a model of the universe, a little portable cosmos it's been described as. So you had a dial on the front is showing you. the movements of the sun, moon and planets through the sky, through the year. There was a star calendar on there telling you which star constellations are rising and setting at different times.

And then two more dials on the back. There was a calendar. There was information about which athletics games were happening in a particular year, including the Olympics games. And there was an eclipse prediction dial. So really, it was just a little box. You turn the handle to move forwards and backwards in time, and it shows you everything about the universe for that particular moment.

Can you take us back to 1900 when this was lying on the seabed and tell us how it was found? And how long it had it been lying on the seabed? It had been on the seabed for more than 2,000 years, probably dates from the first century BC. Yes, it was found on a shipwreck by sponge divers who were on their way from their home in Simi, in the eastern Mediterranean to the northern African coast where they were diving for sponges. and either on their way there or on the way home, they were blown off course by a storm, and they took shelter by a little rocky island called Antikythera,

which is just about halfway between the southern tip of mainland Greece and Crete. And once the storm had eased, the story goes that one of the divers put on the diving suit, they were diving in those days in those sort of heavy canvas and rubber suits with a bronze helmet breathing air through a tube that went up to the surface. He went down, came back after a few minutes, terrified, saying that he had seen a heap of dead, naked women and horses on the seabed.

And so the captain puts on the suit, they only had one suit between them, goes down and realises that these are not corpses. They are statues, bronze and marble statues from an ancient shipwreck, which those divers then worked with the Greek government to salvage over 10 months from 1900 to 1901. And it was an incredible find. It was by far the most impressive hall of ancient treasured. that had ever been found at that point.

It was the first ancient shipwreck that was ever salvaged under the direction of archaeologists, so quite historic for the field of marine archaeology. And all kinds of things came up. So the bronze and marble statues, there was furniture, like ornate bronze thrones, bedsteads. There was armour, shields, helmets, gold jewellery, luxury, luxury glassware, amphras.

So all of these things coming up being covered in the newspapers all around the world. But everything was being brought back to the National Archaeological Museum in Athens and it wasn't until many months later that an unassuming corroded lump of bronze broke open and was recognised for being really something rather special that had never been seen before. Mike Edmunds, can you take that further and tell us about the route the ship had been following and why it had been following that route? Well, the actual route of the ship isn't known.

It was travelling along what was a common track. trade route from the eastern Mediterranean towards Italy, really. It would have maybe called in at Pergamon and roads. Those are possibilities on the way and be heading towards the Italian ports. It was a well-known trade route. It was at one time wondered whether this was a load of plunder that was being taken back towards Rome. But more likely it was probably some very well-heeled official or something moving his house.

I mean, how did you move in those days? You couldn't take the train or the road. You had to take the ship. And it's most likely that this was some rich person moving with all their stuff. Why would that stuff include the mechanism we're going to talk about? Well, that's an interesting question. Presumably because it was a high-status object that somebody might like to own. Well, no doubt, have to talk quite a lot about what the thing actually was for,

because nobody's actually entirely clear what it was for. but one good possibility it was a statement about what the Greeks knew at this time about the universe and somebody had no doubt seen a market opportunity and realised that a lot of people in the upper echelons might like to appear at least to be interested in such things

and to have such a thing on their mantelpiece as a talking point and show that they were interested in the universe I mean there was to some extent I believe it's a Pythagorean or Plattecs view that if you actually take an interest in things celestial and so on, you almost become a bit immortal yourself.

So it'd be in a nice object that somebody could have had on their mantelpiece and might have been prepared to pay for too. Who were the first curators to get to grips with it, having been discovered? The bronze has undergone chemical changes, is very fragile and so on. Any wood in it is now virtually

rotted away, obviously. But there's still enough there. And What's amazing about it too, the bronze plates with which is made are coveted inscriptions in Greek as well. So it comes not with a user manual, but at least a user specification, as it were, with it, which has been enormously helpful in beginning to understand what it did. But the story of how it came to be, we talked about how it began to be discovered. I mean, what happened was interesting? There's a guy called Spiriton-Stais, who was the Minister of Education in Greece. and he'd been quite instrumental in getting the underwater archaeology going.

And anyway, he came, by this time, he wasn't Minister of Education anymore, like modern-day ministers, they don't last long. And he was MP, basically, for Kithra. And he was visiting the museum, National Archaeology Museum. And he went down the basement where they got all this stuff. And he said, what's that? Pointing at this bronze thing and saying, well, everybody sort of looked a bit surprised with, it's a bit of bronze, you know.

But it had cracked open. It presumably had dried out. and you could see in it the outline of gear wheels. And that was the real teller. And precision gear wheels, metal gear wheels, aren't known from the classical world. Here's the first example of them. And also the beginnings of these few words of Greek that they could see were related to astronomical things. That's when it really started the study of it.

And over the years, it was gradually sort of split apart a bit more to see what was inside it. And it's only in the 1960s and onwards. Once you get into radiology and so on, that the real complexity and beauty of this device began to be realized. It's extraordinary, isn't it? It is. Leiber, at the time the ship went down, what was the understanding at that time of the moon and the planets and their movements? We're very fortunate that we have a book by someone called Geminis, who was working in the first century before our era, so the same century in which the shipwreck occurred.

The book is called The Introduction to the Phenomena, and it is an introduction to astronomical observation and to astronomy, and it gives us a very good impression of what was being taught in the period. It's very likely that Geminus himself was not a researching astronomer, but was rather an educator and possibly even a popularizer. We know that he wrote another work talking about different kinds of mathematics, and astronomy was in the period considered to be a branch of mathematics. The title of the book was introduction to the phenomena, and phenomena here means what we can see. It means the appearances. So he's focusing on what can be seen in the sky. There are the so-called fixed stars, which are constellations or asterisms, which seem to, to keep their relative positions as they move through the sky. They're also the so-called planets or wanderers, the sun, the moon, and the five that we consider to be planets, Mercury, Venus, Mars, Jupiter, and Saturn.

The phenomena that I've mentioned, the observations that people could see just looking at the night sky, in some ways seem to be regular that, for instance, the rising in the east and the setting in the West. But people noticed that the planets, the wanderers, seem to drift. And the big challenge, or one of the big challenges of Greek astronomy, was to give an account of how the planets seem to move, appear to move in non-regular ways. How widely was this kind of knowledge shared,

and who took an interest in it? It isn't the first thing we think about when we think about the Greeks and so on. Well, I think that the way that Geminis' book is set out, that it is an introduction to the phenomena, to astronomical phenomena, gives us an impression and an indication that you didn't need to be a specialist. You didn't need to be a mathematician, an astronomer, to be interested in these phenomena. The book seems to be educational. It's possibly even a textbook. It doesn't seem at all as if it's being written only for specialists. It didn't come, turn it to you and out, Joe Marchant. In the 1950s, Derek DeSolar Price took an interest in the mechanism. What did he find out? Yeah, Derek Price was a really interesting person. So there were several scholars before the Second World War,

he would take an interest, had some different ideas. Was it an astrolabe or a planetarium? Sort of reading traces of inscriptions, there was an idea that it was something astronomical, although there was also an idea that perhaps this was a hoax because it just seemed so incredible that something so sophisticated would have come. But Derek Price, he was interested in the history of science. So he was a physics professor originally, born in East London,

but went to Yale to become the first professor of the history of science in the US. And he was interested in the history of knowledge, and particularly the history of ancient scientific instruments, especially astronomical instruments. He thought that through the devices and the instruments, they held the sort of secret of the history, the progression of human knowledge. So in the 1950s, he started studying the pieces of the Antikythera mechanism in the Athens Museum, worked with an epigrapher to decipher more of the inscriptions,

came up with this model of the wooden shoebox with the two faces, the dials on the front and the back, realised that the front dial was showing the sun and the moon. And then in the 1970s, he worked with a radiographer. And he was really the first person. They didn't know how it worked, quite what was going on, but he knew it was important. He said it was as spectacular as if the opening of Tutankarmoon's tomb had revealed the remains of an internal combustion engine. Like he was the person who said this matters, this changes everything.

This is the roots of our modern technology right here in ancient Greece. But he didn't really get much further with it until the 1970s when he worked with a radiographer in Athens and was the first to x-ray the pieces. So now you're seeing the gear wheels that were hidden inside. And in particular, he was counting the teeth. teeth on all of those different sized wheels because the gears are driving each other around with the teeth and the differences in speed depend on the number of teeth with the different wheels. So you're carrying out mathematical calculations with these wheels. You're converting one speed into another

speed. In particular, he looked at a train of six gear wheels. So you turn the knob on the side, the first six gear wheels. And he realized that they convert the speed by a ratio of 254 over 19, which might not sound particularly impressive, but he realised that these were numbers that were found in a Greek calendar that harmonises the motion of the sun and the moon. It was essentially converting the speed of the sun into the speed of the moon through the sky.

You wanted to come in. Yeah, well, I mean, just think of yourself. You're a Greek, and you look at this device. You're asking, well, what's the relevance? How are the reeks going to react to this? But there you are. There's the heavens in front of you. There you can see the moon,

its phase. You can see the sun going around the sky. And presumably to the planets as well, though that part of the mechanism is unfortunately lost. We certainly believe that it was there. And so in a way, here's a device that allows you to visualize the heavens in a different way and realize that you don't have to have gods pushing the planets around. It's an interesting philosopher of viewpoint that that's what was doing. But maybe look, here you can do it gear wheels and things. And surely that leads you on to great philosophical speculations about what the universe is really like.

Nobody's going to say it's got big gear wheels that drive everything round. But the point is something is doing it, and it doesn't have to be gods anymore. There's also, the ancients knew that the movement of the planets wasn't regular. How did the discovery made there tackle that? Well, this is interesting. As I say, unfortunately, the actual mechanism that would show the planetary motions is missing from what's left of the mechanism.

But we know from the detailed inscriptions on the device that it probably did display planetary positions. We might worry, how would they have done this? Because it was quite, you know, technically not trivial to show the retrograde motion of the planets and things going forwards and backwards with gear trains. But we know from the way they designed the lunar train, the one that's there, that shows how the moon moves in the sky, that they were clever enough to be able to incorporate non-regular motion in that. It has irregular or regular, irregular motion,

if you like a Rumsfeld type description. In other words, they knew how to devise gear trains. And in fact, they're very sophisticated interlaced gear trains that give you this variation in the lunar speed and its orbit. And that shows that if they'd wanted to, and we believe they did want to, They could have done that for the planets too. Thank you. Leva, who would have had the skill to make something like this?

Do you have any idea? I believe it's very likely that more than one person was involved in creating this object. And as you've already pointed out, there's lots of things that are in this object. It's not one type of information that's being portrayed and depicted. There's also the calculating function, etc. So someone would have had to know about astronomy, someone would have had to know about calendars. The games have already been mentioned, so people would have had to know about the different games that are depicted on there and their calendars.

Someone would have had to have the skill to do the metal work and the gearing. And it may well have been, that person doing the gearing may very well have been a different person from the person who did the inscribing, the engraving, the engraving on the object. So I think it probably makes sense to think of the object as a product of collaboration, possibly even what we might think of as a workshop. So they're making an image of a universe mechanically? That's part of what's going on here, yes. What's the other part? Well, for instance, the part with the game style, for instance, which is very interesting because it has nothing to do with astronomy here. So it's not only an astronomical object.

I think what's interesting actually is that it shows us that for the Greeks, they didn't make that same separation between Earth and sky that we do. So we would think, oh, well, it's showing astronomy. So why are the Olympic Games in there? But they would have had a much more holistic view where what was going on in the heavens was really sort of mirroring, driving, guiding and forming what was going on Earth. And they also wouldn't have had the same distinction that we have between astronomy, the scientific observations and astrology.

So we see all of these things mixed together and I think that that makes sense as this device really being a holistic model of the workings of the universe as they understood it at the time. Another reason why there might be the Olympic, or this game style there is because calendars varied all around the classical world. Almost every city had its own calendar. And so if you're using this device,

you might wonder whether you've got the set the year right for your particular calendar. But everybody would know whether the Olympic Games were having that year or a couple of years' time. So it may have just been a way of orienting as to where you were when you were playing with the device. It's possible.

Joe, back to you. Were there any particular philosopher at the time? There were plenty of them. Were there any one or two who underpinned what was going on? Well, one philosopher whose name often comes up relating to the Antichythera mechanism is Posidonius, who was working in the first century BC

on the island of Rhodes. He was a stoic philosopher who would have seen the universe as guided by this sort of holistic divine force, not so much different gods in the heavens as you might have seen previously with the Babylonians, for example. And the reason that his name comes up is because Cicero, who had written accounts of descriptions of this kind of machine, at one point says, our friend Positonius made this bronze machine that models the motions of the sun, moon and planets in the sky. And Cicero visited roads in the first century BC when Posidonius was working there, at just about the same time as the Antikythera ship

would have stopped there. So all of these strands are kind of coming together. And the name Archimedes comes up. Is he relevant to what you were talking about? Yes, Archimedes always comes up with any ancient invention. But yes, because Cicero wrote another description of a very similar sounding device. And in this case, he says that it was built by Archimedes. Now, Archimedes was working a couple of. of centuries earlier, third century BC, all the way west in Syracuse in Sicily. So he was working too early to have made this particular device and in the wrong place for where we know that the ship would have sailed. But it is possible that he could have invented this tradition of

devices, this idea of modelling the motions of the heavens in bronze. And perhaps he would have made a much simpler version, perhaps just the different speeds of the sun, moon and planets without all of the speeding up and slowing down and changing direction that we know the antikythera mechanism did. And you can imagine that over the generations, these models would have become more sophisticated, folding in the latest astronomical advances as they occurred. And then the third name that I wanted to very quickly mention is Hipparchus, an astronomer who was working on roads in the second century BC, just a few decades before Posidonius, because he was working on these epicyclic theories

that have been mentioned. He modelled, he had a sort of a mathematical theory for the change in speed of the moon that we see in the Antichythera mechanism. So it could have been his astronomical theories then feeding into those mechanical designs and perhaps Posidonius and his workshop were then building on that in the first century BC.

Thank you very much. Mike, what is feeding off what in this? Are the makers of this instrument or instruments, let's use the one that we're talking about, influence by what they see, or is it the other way around? But of both, I suspect. It feeds probably both ways. I mean, I agree with what was saying, most likely thing is some sort of small workshop could have produced these,

and maybe there are workshops elsewhere. You mentioned Archimedes. He wrote a book, apparently, about such devices, probably, called Desferi. But it's been lost. You don't have a copy, do you, I'm afraid. But if only we could find the copy of that book, we'd know how far advanced they were at Archimedes' time. but it's been lost.

Perhaps it'll turn up in Panam Cest or something one day. But I'm sure that there must have been a two-way trade between building these devices and developing the theories that went with them. I mean, circles, rolling on circles, classic Greek mathematics, how many circles you can fit together and so on. And I suspect, and some of the philosophers nowadays do think so,

that there was a two-way process. You look at these devices, they've built these devices, it gives you new ideas about the planetary theory. So I suspect those things coexisted for a while in developing planetary theory. Leiber, who might have commissioned this particular object? Well, I tend to agree with Mike that this is probably someone, well, certainly someone who had the money to commission it, to pay for it. And someone probably who also wanted to show off his interest in astronomy,

that he was an educated person, that this was the sort of thing that he knew about. I think the person was probably Greek. I think it was probably a man. And if he wasn't Greek, he may have been a Roman who was wishing to show off Greek knowledge. It certainly was a very impressive object, and as it's already come up, it does all sorts of different things. And I think that's one of the most interesting questions is what was it for? And I think that what it was for may have been to show off knowledge, to show off sophistication, possibly to even show off money. And Mike suggested that someone wanted to put it as a status symbol on a mantelpiece.

I think it's possible that someone wanted to bring it to their dinner table to the sort of dinner party and drinking party that we call the symposium. and we know that at symposia men would get together and have learned conversations. They might have some bawdy conversations as well. And there'd be all sorts of entertainment, including intellectual entertainment. We also know from writers like Vitruvius, writing in the first century before our era, the same period in which the object went down into the sea. We know that there were objects that were devised, purely for amusement. He describes some of these in some detail. One of the people that he mentions,

an earlier person, Cotzebius, who had made some of objects that were purely for amusement, some of them also had gears. So we have all kinds of examples of fancy objects, for instance, depicting birds singing, that used water pressure to operate. We also have trick drinking cups that are not mechanical particularly, but amusing. We also have later authors like Hero of Alexandria describing some things. And I think it's entirely possible that this was a very elaborate, very fancy object. We don't know, as Mike has said, some of the bits are missing. It may have had some decorative bits as well.

So I think that one of its functions was to impress people, but also it could have been literally a conversation piece at a dinner party. So I agree that it was part of what it was about was wealth, the status, wonder, entertainment. But I do think that there was a much deeper philosophical purpose here, that it was absolutely about understanding and exploring the nature of cosmos, reality, our relationship with that universe. One of Cicero's writings, he said if somebody looked, if somebody in a barbaric land like Britain, saw one of these things,

they would know it was made by a rational creator. So it was really an expression of this rational design, order, purpose in the universe. But at the same time, it's an expression of the idea. It's moving from this previous idea of the universe as this sort of chaotic, quite magical place with the celestial bodies as gods kind of warring in the heavens to a single mathematical system where everything is connected, everything has order, where everything works according to mechanical physical rules, not bronze cogs, but rules that we can investigate, understand, predict.

And so the technology of the Antichythera mechanism is really important. But that idea is also so important because that, That, for me, is really the birth of that scientific world view of seeing reality as a mechanism that we can study and understand. Galen, you may know as the medic, the famous medic, who's a couple of hundred years later, really, at the time. But he knew about such devices. We've evidenced from the literature that they certainly lasted until about 500 AD. They were still around by 500 AD. And Galen says, look, I'm not sure that our bodies working quite the same way as your planetary mechanisms do. And it's discussed as to whether, you know, how mechanical the bodies are and so on. I think it's also possible that this was a demonstration device showing different astronomical

explanations and motions as well. So when I say entertainment, they're meant to be impressive, I think it may have had a somewhat intellectual and educational in a broad sense function as well. And we can even in some ways imagine a copy of Geminist's. his book being available and this object being alongside it. And maybe if you're hosting a symposium, you might want to give a little demonstration lecture about astronomy. Joe, after Derek Price, what were the main leaps in the understanding of the mechanism after

him? Well, in the 1980s, there was a young curator at the Science Museum, young at the time, Michael Wright, who became interested in the Antichythera mechanism. and he worked with a historian of computing who was based in Australia called Alan Bromley. They went to Athens and re-xrayed the pieces. This time, Wright, built a kind of cradle, a tomography cradle, for swinging the x-ray film and the object relative to the source, the x-ray source.

And it allows you to just bring out into focus different planes of the picture, rather in a normal x-ray. It's just everything is sort of smushed into one level. So by doing tomography, they could really pick out the three. arrangement of the gears. And Michael Wright then studied those and he makes things. He makes mechanisms. So he built what he saw.

And he was the first person to suggest that this mechanism was modelling the planets. He saw traces of what he thought were something carried around on that big wheels. So little wheels being carried around on the big wheel suggesting epicyclic gearing that this is how it was modeling that looping motion of the planets. He realised that the dials on the back,

Everybody thought they were concentric circles, but he realised they were actually spiral dials, spiral grooves, with a little extendable pointer with a needle tracking that spiral groove, just like a record player, which is one of my favourite details about the mechanism. And then around 2004, there was an international collaboration led by Mike as the academic lead and also Tony Freeth, the mathematician and filmmaker from London. And they brought together expertise, academics from different countries, and state-of-the-art technology.

There was very high-resolution, powerful, CT scanning, so producing these three-dimensional X-ray images of the inside of the fragments to very, very fine resolution, and also using some technology from Hewlett-Packard that was originally developed for computer graphics to image the inscriptions, and that really led to increasing detail and realizing the final piece of the mechanism, which was the, one of the back dials, was actually predicting eclipses, which hadn't been realized until that point. Mike, can I come back to you? Does this fit in with an idea of three, movements of thought going on.

One was, is it a Christian movement had developed, obviously, one god. And before that, there were many gods. And now there was mechanical. Yeah, all mixed in there. All mixed in. I think you get the many gods first. This is coming at the time of many gods.

But then towards the end of the period, I was saying about 500 AD, when these things seem to die out. That's when the Christian era is really coming in. And you do wonder whether that may be something to do with why you don't see them anymore. There may have been a progression through that.

But there are other aspects of this, which I rather like. I'll just mention, for example, I think there are things within the mechanism that show a much deeper continuity of thought. Now, these are people, you know, I make myself very unpopular with my colleagues saying these things. But for example, there's a big wheel in this thing. It's the classic thing.

You look at the pictures and there's this big chariot wheel, it looks like, in the mechanism. And that's the main wheel that Turland's once. a year when you're playing with the mechanism that represents one year turn. Now chariots and chariot wheels are associated with the sun

and in mythology and in artwork and so on. And indeed that wheel has get right, 233 teeth, the seros cycle of months basically. So of lunar months between

eclipses. There are bits in this mechanism that are emblem of the way you talk about astronomy, the way you talk about the heavens, and I've always done so. Going back maybe thousands of years, it's not just a sudden mechanical device. It comes very much in a tradition of thinking about the sky.

Are these decisions disputed between those holding them? I think the point is it shows that it was a great time for intellectual discussion. For example, I mean, this device is geocentric. It's based on Earth and what you see from Earth and whatever. But we know that they discussed in Greek times whether it was a heliocentric universe or not, you know, everything going around the sun rather than around the earth. Everyone thought that was a crazy idea. Well, not everybody.

Not everybody. But, you know, what gets suppressed, what doesn't get dispersed, all these ideas are in a melting pot. And of course, it's a time of great political change as well. So it's the sort of atmosphere in which you would get the sort of discussions about what is the nature of the universe. on. Leba, who would have been writing about this at the time? Well, as I mentioned, Geminis himself talks about astronomical instruments, and this includes teaching devices. He mentions a sighting instrument known as the dioptera. He describes armillary

spheres, which are composed of rings and which would normally show, for instance, the ecliptic, the path of the sun, and the zodiac. He also describes celestial solid globes. I've mentioned Vitruvius as well, and he described different sorts of instruments and objects, including some with teeth. He mentions Cotzebius, who he says wrote about such objects, but we don't have his writings, sadly. we do have later writings. And as Mike and Joe have both mentioned, we have different writers, including Cicero, who's not particularly a scientific author, talking about different models of the heavens. So, and Galen also, as Mike mentioned, and Ptolemy, much, you know, later, this was a contemporary with Galen. But in the period that we're speaking about the first century before our era, I think that Vitru, Pruvius is particularly interesting and Geminus as well. And they clearly had some knowledge of objects that were in some ways related, possibly simpler versions of the mechanism,

but no one describes anything, even Cicero, I don't think, that truly fits the description of the mechanism with all of its different capabilities and, of course, with its gear work. Indeed, I think that's what we wish we had more literature on some drawings from this era. We don't. We have to rely on what we've got. And I think it's true if we didn't have the antichythera mechanism, we'd never have perhaps imagined that it could have been as complicated as we find it. And what would it mean the consequence of that? That we lost something in our admiration for the Greeks, I guess.

I mean, it's true that if you look at the jewelry of the time, that there's no difficulty in imagining the Greeks could make the The actual metal work can be done. They're really good at doing jewelry and so on. They can do the metal work of this. But what I don't think we had any idea of until you've got the anti-cythra mechanism is your hand is realizing that they can do sophisticated engineering design. Okay, they've done some of these things Leibu was talking about,

particularly in theatres, birds, opening doors that open automatically and so on. But the idea of a precision, gearing and thinking, that out is something we would have no idea about. And I think it's interesting in the 1960s and 70s when DeSolar Price was writing, to some excite, people just ignored the solar price because they thought, this can't be right. The Greeks couldn't have been that clever. And it was just a sort of being a bit, I don't know, a bit arrogant, I suppose, for our scientific era. If you go back to 1800 and look at encyclopedias that were written in, there's an Edinburgh in Scytlopieda was written in 1800, talks about the possibility of various planetary mechanisms

and aurories and so on. And there talks about that the Greeks had them. And that comes from the literature references, not because they had the Antichythera mechanism, because they didn't have it then. They had descriptions in the Greek literature implying such a mechanism. And they had no trouble at all with that. Because it was the era of the great classical education, no doubt. And they were used to the Greeks and Romans being as clever as we are. But I think we forgot that during the 1960s and 70s to some extent. And this is in a way brought us back to realize that, you know, they're just as intelligent as us and a fascinating civilization.

Well, if we didn't have the antichythera mechanism, I think we wouldn't realize that some of the technology that has absolutely shaped the modern world. So mechanical gearing has been so important in the development of clocks and timekeeping, which was very important then economically as well. but also the automated machinery that drove the Industrial Revolution is all reliant on these sophisticated gearing techniques, wheels, riding around on other wheels. And this is showing us that those technologies, which have often been credited to the Europeans, we tend to credit everything to ourselves, the beginnings of that technology actually go all the way back to ancient Greece.

And when you know what clues to look for, you can actually see hints of it in the Byzantine Empire and in the Islamic world. We know of a sundial from the 6th century Byzantine Empire, so inscriptions in Greek, but it's got a little geared calendar, eight gear wheels, showing the movements of the sun and the moon. And then from the Islamic world, there's a manuscript in Arabic, a 12th century copy of a 10th century manuscript, which has exactly the same, a drawing of the sundial with the eight-gear calendar, and then an actual astrolabe from 13th century from Isfahan, Iran, again with this. eight gear wheel calendar. So when you know what to look for, this is much simpler than the anti-cithro mechanism, but you can see that that tradition of modelling the heavens with gear wheels

survived through the Byzantine Empire, the Islamic world, and then came back to Europe, possibly through Spain in the 12th and 13th century, and then helped to trigger the invention of modern clocks, because the beginning of clocks is very strange, because all of a sudden, they don't start simple and slow and get more complicated, all of a sudden, at the very end the 13th century, beginning of the 14th, you see an explosion of sophisticated, complicated, astronomical clocks all over Europe, and they are showing the sun, moon, planets, they're predicting eclipses. So it seems as if that technology was sort of waiting in the wings for somebody to invent the escapement, that's a sort of ticking bit that regulates the weights into an even

progression. And then that got added to these geared mechanisms and suddenly you've got these complicated astronomical clocks almost coming as if out of nowhere. And I don't think we would have necessarily realized that progression without knowing that the antichythera mechanism stands at the beginning of all of it. The problem is, and I think it still remains a big intellectual problem, as to whether that's a continuous process. In other words, the knowledge to have how to really do it survived into the beginning of the era of the clocks, or whether it is independently rediscovered the possibilities of gearing at that time,

What is interesting, though, is that certainly later astronomers, for example, Kepler, knew that the Greeks had made these sort of model mechanisms. In his letters, he talks about doing his own mechanism to show planets and things and refers to the fact that the Greeks had done it before. But as you say, tremendously important in later times and would prompt, I'm sure, you to think, well, what if the Romans had developed this in more detail? Why didn't they? Why didn't they develop this gear technology? They were wonderful at building aqueducts, civil engineering and so on. Why didn't they seize on this? Think of the things they could have built with it.

I suppose they saw it as a philosophical device more than a sort of practical working thing. I mean, I'm just speculating. But I think maybe it sort of shows us the sort of the category of device that it was perhaps in that the Romans didn't develop. An obvious ones you might try and say, well, let's make a simple calculator. You know, to do tens and, you know, add up the number. of wheat sheaves in the field or whatever or do the land calculations. But they had slaves to do that and use abacuses and things and they didn't need it. So maybe it was only later that the need for such technology to be developed, developed.

Leva, I'm going to the end now. What are the unanswered questions about this? Well, Melvin, I think that many of the questions that you've already posed to us are questions that we still need answers for, that we still are looking for answers. And I think one of the things that's very interesting is that we do to modern technology and things that have happened over the last 50 years, we know quite a bit about the object itself, how it worked, the different parts of it, et cetera. But we don't really know that much about the human side of it. So we can speculate, as we've done today, about who made it. We can speculate about who commissioned it and why, but we don't really have those answers.

And as I think we've all said, we're missing things that existed in the past. There are certain writings, there's certain objects that we have descriptions of, but we don't have the actual things anymore. We don't have these books. We don't have the objects. So I think that probably the three of us are hoping that some more things are going to be discovered and that more work will be able to be done to give us more information about who made it, who commissioned. it and why? At which Mike Edmonds put two thumbs in the air. What I hope for is maybe something like Herculaneum, Pompeii,

perhaps they'll find a rich merchant's house and excavate and find one. And that would be very exciting. Well, thank you very much. Thanks to Lieber Tobe, Joe Marchant, and Mike Edmonds. Next week, the 20th century Italian author of Invisible Cities and If and a Winter's Night a Traveller, that's Italo Calvino, Thank you for listening. And the In Our Time podcast gets some extra time now

with a few minutes of bonus material from Melvin and his guests. What would you like to have said that you didn't have time to say, Leiber? Well, one of the things that I would have liked to have said, jumped in when the point was made about technology. And I think one of, and it was Mike who said that when Derek Price did his work, people really weren't that focused on it. And Gears from the Greek was the title. And it just seemed, people didn't.

really know what to make of it. And I think part of it is that there's been a long-running idea that the Greeks weren't very interested in practical things, that they did some very high-faluting mathematics, they did some very high-folluting astronomy. But it was the Romans who were interested, for instance, in engineering, and that's a word that Mike used. And I think one of the things that is very interesting about the mechanism is it does show that some very, very sophisticated engineering was being done by Greeks. So it really gives us a different view of the culture and it would be wonderful to have more examples of this. Mike, what would you like to have said that there wasn't time to say? Only I still enjoy the fact that this is, there are clues in this

mechanism to an older tradition in astronomy in my view. I mentioned this chariot wheel on the front, which is associated with the sort of sun moving across the sky. Greeks had that view of a chariot carrying the sun across the sky, but it's much older. It goes back. There are sun chariots from Scandinavia at least a thousand years before. It may even go back to Mycena, Greece, the car sign of linear B, which may well be a pictorial for a sun, is the same shape as the main wheel in the Antikythera mechanism. And I think it just shows that this isn't, it's not, I don't know if you'd call you know, sort of a religious thing.

It's not a religious thing at all. It's just how you design something, what you're comfortable with, what the tradition is when you're building an instrument or talking about astronomy or something. I think there are clues in the mechanism for that. I just find that very comforting and rather nice rather than just all the abstract mathematics as well.

It's a human thing that you're telling the story of the universe, but the clues you've been using before and the ideas you've used before are there as well. I would like to have a go at explaining one of my favourite features inside the mechanism just to give a sense of the sophistication and how it was actually working inside the box and this is the part of the mechanism that models the very slight variation in speed of the moon in the sky. So the moon's orbit is elliptical, not circular. So as we look at it, it's speeding up and slowing down.

The Greeks didn't know about the elliptical orbit, but they knew about the variation in speed. And what happens inside the mechanism is you've got to be a little bit. got four little wheels, two pairs, two above the other, and one of the bottom ones has a little pin sticking up and it drives the one above it. The pin goes into a little slot and because the centres of the wheels are very slightly offset, the pin moves backwards and forwards in the slot and that introduced this little wobble in the speed of the one above and that's where the wobble comes from, but it's not just that. Those four wheels are in turn mounted on another bigger wheel that is going around once every nine years. Because that wobble in the

the moon's motion in the sky is actually moving around the sky once every nine years. So that whole mechanism is sitting on this bigger wheel once every nine years to model that very subtle motion and not even just that because that wheel that is riding around on is actually the wheel that's driving the eclipse dial that has to move at a different speed. So there's a couple of extra wheels that slow it down so it's just right for the moon pointer and then speed it up again later so that you can then drive the eclipse dial. So they're being very economical. They're reusing wheels inside the mechanism.

So I just think that that's absolutely breathtakingly clever and sophisticated and just to give an idea of how all of this was working inside. And this is what we're saying about design ability, engineering design ability. That's what they had no idea that the Greeks could do that. That's the surprising thing. And it shows us that this can't have been the only one because you couldn't make this as your first mechanism. It was too sophisticated, too confident, too small.

it had to have been the product of generations of work, of building on this idea to get to something like the antichythera mechanism. And my guess would be that these go date from probably, I don't know, certainly 200 BC, maybe a bit earlier, right up to 500 AD. It can be traced back. Oh, some design elements. I'll just call them design elements. For example, I say this chariot wheel is something that I think as an image of the sun. And if you're doing something concerned with the sun, it's the sort of trace. if you like, of the sun that you would use.

And I think that's what's in the mechanism myself. But there are other things. The form of these calendrical dials of spirals makes me wonder, and I wish maybe we just don't know enough about this, I suspect a spiral was a way, typical way of representing a calendar. Maybe it's a bit fanciful, but the New Grange site, which is a sort of megalithic site in Ireland, solstitially aligned.

And that has spirals on. It's a very common device on megalithic or megalithic type observatory or pseudo-observatory constructions. And I just wonder if the idea for a spiral was such that that's what you might. If you were doing a design of a calendar, you would put it on as a spiral just because that's what you thought was the right sort of shape for it to be. And I wonder if there are other things in the device, if we look carefully, that they do just fall in this idea that there's a continuity there that we're perhaps missing. because unfortunately it would be nice if this thing had beautiful design on it and lovely gemstones and everything. It doesn't.

But there are design elements there that I think do date from before this time. Well, one thing we should really have mentioned is the influence of the Babylonians. So the Greek astronomy generally was very influenced by Babylonian astronomy. And Hipparchus, who we think may well have played a role in leading up to the Antikythera mechanism, He was very interested in Babylonian astronomy. It's been suggested that he travelled to Babylon and was getting information from the astronomers' tablets there because the Babylonians over centuries

were making very careful observations of the sky because they believed that they could see omens in the sky that were important for foretelling the future. And they were very accurate and they came up with very sophisticated arithmetic algorithms for predicting motions in the sky. The Greeks, by contrast, had this very geometric sort of three-dictory.

dimensional view, Hipparchus was really the one who brought those two traditions together, who said we can't just talk about all these circles in the sky. We need to know the numbers. We need to be measuring. We need to be observing what's actually happening. And we do see Babylonian influences in the Antichythera mechanism, in the eclipse prediction dial, for example, the timings that cycles use for the eclipses. So it's important to think about this, not just as a purely Greek thing, but you can absolutely see those influences coming from other cultures as well. Yeah, but the cycles are Babylonian, basically, take. and over into the Greek world.

Thank you very much indeed. Thank you. I think a lot of people are going to enjoy that enormously. So thank you very much. Thank you. Hold on. Simon's coming in with his news. News.

Do you want a cup of tea? I have a cup of tea. Two cheese, Melvin? I'd have a cup of tea. Thank you. Three teas. Thank you very much. In our time with Melvin Bragg is produced by Simon Tillotson and it's a BBC Studios audio production.

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