Decoding the Heavens: The Antikythera Mechanism by Jo Marchant

hi my name is Joe Marchant I'm a science journalist and tonight I'm going to talk about the Antikythera mechanism which i think is the most exciting object that we have from the ancient world it's the remains of a complex mathematical device that was found after spending 2,000 years under the sea and I'm going to talk about how it was discovered how its mystery was solved and what it means for our thinking about what the ancient Greeks were capable of and for the roots of our own science and technology so good evening and welcome to tonight's Darwin College lecture and as you know our theme this year is enigmas every time I walk down Kings parade here in Cambridge I'm struck by the crowds of people admiring the Corpus Christi clock the chronophage or the time eater which has that monster grasshopper walking along the top of the clock releasing the escape will cog by cog it was John Harrison an 18th century carpenter and clock maker who invented the grasshopper escapement and that meant for over a century his long case clocks were the most accurate in the world however he was most famous for designing clocks that could keep accurate time in ships at sea and so enabled longitude to be precisely determined from astronomical observations up to then longitude being a huge and long-standing problem for navies and sailors in general so while the motion of planets can be tracked with telescopes their motion can also be predicted with clocks and the Greeks and the Romans were deeply interested interested in astronomical motion so the Greek Antikythera mechanism demonstrates that they had been going down the same route that John Harrison and others followed almost two millennia later using gears and wheels it was a complicated instrument apparently designed to predict the heavenly motions and must have required final engineering skills to design and build it so tonight we have dr. Joe Marchand who's going to take us back 2,000 years and explore the mysteries around this complex instrument and the title of her lecture as you can see being the Antikythera mechanism so Joe welcome [Applause] thank you so yeah tonight I want to tell you about what I think is the most exciting object that we have from the entire ancient world and yet it's not a classical statue or bars or an Egyptian mummy or a beautiful piece of gold and jewelry it's a collection of ancient battered bronze pieces called the Antikythera mechanism so this is the the largest piece so the Antikythera mechanism is now held in the National Archaeological Museum in Athens it was found on a shipwreck after 2,000 years under the sea and it's the remains of a complex mathematical machine and it completely mystified scholars when it was first discovered there's nothing else like this in the historical record it's unique nothing anything close to this sophistication occurs before it in the historical record and nothing close to this appears after for well over a thousand years afterwards so tonight I want to tell you about how this objects was discovered the how its mysteries were decoded it's a project that took over a century to work out what this thing is and I want to talk a bit about what the answers that have been gleaned from these fragments mean for our understanding of what the ancient Greeks were capable of and for the roots of our own science and technology so the modern story of this mechanism starts in the year 1900 where the group of sponge divers so the Industrial Revolution was in full swing sponge diving was a thriving industry across the Mediterranean Sea and the sponge divers used these canvas and rubber suits with heavy metal helmets and they breathe compressed air that was fed through a hose from the boat above and that was very dangerous the dangers of the bends really weren't understood at the time and for thousands of divers with dying of the bends at this time but nevertheless lots of crews of sponge divers would would sail out every spring harvest sponges for the summer and sail back again in the autumn and in the spring of 1918 called Demetrius contests and his crew set sail from the island of where's my pointer I can't see it the island of Simmi anyway hopefully you can see it marked on the map they were from Simmi in the Aegean Sea and they sailed west and south down to the cat the coast of North Africa off Libya where they collected sponges for the summer and then in the autumn they sailed back and on one of those journeys we're not sure which of those journeys but on one of them they were blown off-course by a storm and they sheltered by the island of Antikythera so this is Antikythera because it's beautiful but it's barren it's got these treacherous steep rocky cliffs and they sheltered in a little harbour there and once the storm had died down one of the divers went down into the water and the story goes that he very quickly came back up again terrified saying to the others that he had seen a pile of dead naked women and horses on the sea beds the captain put on the suit they had just the one suit between them went down to have a look and he did indeed see figures about 60 meters down but he realized that they weren't corpses they were statues bronze and marble statues so the divers had come across an ancient wreck that was full of treasure so they reported it to the Greek authorities they took a bronze arm with them as proof of their find and they were hired to salvage the wreck under the direction of official archaeologists and that makes this a very important wreck in the history of marine archaeology this was the first time that archaeologists had investigated a shipwreck and they it was very dangerous work they salvaged the wreck for ten months between November nineteen hundred and September 1901 the weather was terrible one of them died of the bends and other one was paralyzed but they brought back what at the time the most incredible haul of objects from the ancient world that had ever been discovered and they were all shipped back to the museum in Athens and this included bronze and marble statues there was bronze armor including helmets and shields there was parts of furniture ornate bedsteads parts of a bronze throne there was gold and jewelry and lots and lots of pottery luxury glassware this is one of the most famous vines from the Antikythera Rex called the Antikythera youth a bronze statue that dates from around the 4th century BC they were also a lot of marble statues brought back and that top picture is the sponge divers in their two little boats and then here you've got some of the marble statues that were brought back to the museum so they tended to be in much worse state they were corroded eaten away by sea creatures some of them have beautifully preserved details though this statue you hear of a crouching boy so it was half buried in the sediments when it was brought up so you can see the other half has been eaten away but that half is beautifully preserved this is one of my favorite finds from the Antikythera wreck it's the the head of a statue and it's thought to be a portrait of a particular philosopher we don't know who he was with the eyes inlaid with stone dating from around the 3rd century BC so that's just to get across to the Antikythera shipwreck even without anything else would still be one of the most important ship breaks that's been discovered from an archaeological point of view and so the staff were trying to deal with all these thousands of objects that were being brought back a lot of them in pieces they're trying to fit everything together any kind of fragments that were and identified or didn't look very interesting we're just left in crates in the museum courtyard and in May 1902 a visitor to the court to the to the museum realized that one of these lumps its lump of bronze had broken open and what he saw inside seemed impossible he saw remains of intricate gear wheels and measuring scales lots and lots of inscriptions so this is the the largest piece this is called fragment a and so you can see that there's this big gear wheel there with four spokes and the shape of a cross you can see the little triangular teeth that are cut all around the edge and then behind that there are a lot more smaller gear wheels with their teeth and you can see other mechanical components there this is two more fragments so on this one you can see what look like perhaps concentric sort of circular dials those inscriptions they're here you've got this double scale sort of precisely mark measuring scale looks like it's a modern protractor that you might use for measuring angles more inscriptions and it's really hard to overemphasize just how incredible this find was so there was no other example of a gear wheel known surviving from the ancient world like not a single one no example surviving of a measuring scale so this was just completely different to anything that had been found before sand nothing sort of close to this kind of complexity appears again in the historical record until the development of mechanical clocks and that was well over a thousand years later so various experts were drafted in to try and work out what this thing was only a few words at this point could be deciphered from the inscriptions but they included some astronomical terms so one idea was that this might be an astrolabe so that's a device where you have one disk that rotates over another to represent the movement of the stars in the sky but they don't have gear wheels another idea was maybe a planetarium but you know nothing like that is known from the ancient world maybe it was just a hoax or a mistake so people were really sort of flummoxed by this and then during the Second World War a lot of the artifacts from the Athens museum including the Antikythera mechanism were taken and hidden under the floors buried in sand to hide them from the invading Nazi army a lot of this work was forgotten after the war everything was got back out a lot of items were put back on display but the Antikythera mechanism never was it was just left forgotten in a storeroom this thing that didn't really look like much and nobody really knew what it was until this man this is Derrick to saw a price rediscovered it so he was born in East London in the 1920s he trained as a physicist originally but then he moved to Yale to become the us's first professor of the history of science and he was fascinated by the history of scientific instruments and especially astronomical instruments and he really felt that tracing this tradition of devices was key to to tracing the progression of human knowledge so he did a variety of projects on different artifacts trying to sort of trace this tradition of technology further and further back one of the things that he looked at was the tower of the winds in the Greek marketplace in Athens so this is the stone tower dating to around the first century BC its octagonal and it's got carvings on each of its sides representing the eight winds it's empty but from markings on the the marble floor price was able to reconstruct a giant clock that once stood there so there was a water clock driven by a local stream and so just by a couple of gear wheels that the water was used to drive a giant bronze disc that with the Stars sort of carved onto it representing the sky that would have turned inline with the heavens but then he discovered something much more impressive than this the Antikythera mechanism so he studied at he worked with a researcher in Greece to try to read more of the inscriptions now that a lot of the fragments had been cleaned and they were able to read more snatches of text so there's this double scale here and on the outer scale and they were able to read the words pack on and panie these a month names so this outer scale looks as if it was a calendar divided into 365 days of the year and separated into the 12 of months so a doll representing the year and on the inside ki and Parthenos so these are signs of the zodiac Libra Virgo so this inner scale would have been divided into the 360 degrees at the sky and the 12 signs of the zodiac and of course the the Sun during the course of a year sort of moves through in a circle around the sky through these background stars so a pointer that moved around this dial would have shown you both the dates in the year and the position of the Sun in the zodiac there were other snatches of text Vega rises in the evening the high D set in the morning so these are telling you different events things that the stars were doing at different times of year and price realized that they were little kind of solo letters at different points around this dial that led to these other bits of text so they were basically giving you more information about what the stars were doing at different times of year other bits of text seem to be kind of looking as if they were perhaps operating instructions so he wasn't able to get much further than this he wasn't at this point he wasn't able to see what was really happening inside the mechanism but already he started to realize its importance so mechanical gearing is a really crucial technology it enabled the development of mechanical clocks so accurate timekeeping it also enabled the automated machinery that drove the Industrial Revolution so price realized that here's this technology that is thought of as having really shaped the modern world and yet here was proof that it actually had its roots in ancient Greece so he wrote that the Antikythera mechanism was as spectacular as if the opening of Tutankhamun's tomb had revealed the decayed recognisable parts of an internal combustion engine so he wasn't given to understatement price and then in the 1970s he had another breakthrough because he worked with another researcher in to x-ray the fragment so this technology was just becoming usable for archaeological artifacts and so for the first time in two thousand years the internal structure of these fragments was revealed and crucially he could start to I don't think identified a lot more gearwheel and he could start to count the teeth on those wheels and therefore start to work out what was being calculated inside the mechanism and so just to quickly that it worked on the same principle as clock so you've got gear wheels driving around other gear wheels and depending on the number of teeth you can do mathematical calculations so if you imagine that you had one game where with 20 teeth and it was driving another way with ten teeth then for every one turn of the 22 three Oh your tent with wheel is going to turn twice so you've multiplied your speed by two or in fact minus two because it's going the other way and in clocks gear wheels are used to multiply speeds by factors of 60 to turn seconds into minutes and hours but the calculations that were going on inside that Antikythera mechanism were a lot more complicated than this so he was able to decipher in particular one set of of six gear wheels that led directly from the input of the mechanism so essentially he worked out that this was a mechanism that would have been held in a wooden case looking a bit like a modern clock about the size of a shoebox turned by a handle on the side and then that handle he figured was driving a pointer showing the movement of the Sun so one turn of that point it would represent a year and then he saw this train of six gear wheels and when he worked out the calculation that that was doing it was multiplying the input speed by 254 over 19 which might sound like quite a random number but he knew enough ancient astronomy to know that this was a reference to a calendar called the metonic cycle that was used by the ancient Greeks to harmonize the motions of the Sun and the moon so it's quite tricky to have a straight full calendar that tracks both the Sun and the moon because 12 lunar month do not fit exactly into one solar year so each year you're full and New Moon's will fall on different dates but the Greeks knew that after 235 months or 19 years they do come back into sync and again your phases of the Moon will occur on the same dates as they did on the first year so they used to use this 19 year calendar to bring together both the Sun and the moon and that's synodic months tracking the phase of the Moon there's another kind of month called a pseudo real month which measures the time it takes for the moon to go exactly one orbit around the Earth and come back to the same position with respect to the background star so the timing of that is slightly different and in this cycle 19 years it's 235 synodic months is 254 sideral months so essentially for every 19 turns of the Sun through the sky the moon will turn 254 times so essentially what this gear train was doing was taking the speed of the Sun and translating it into the speed of the Moon so as you're turning the handle it's driving a Sun pointer but then through this gear train it can also drive a moon pointer going around once a month so price still had lots of questions about the mechanism you didn't really know what was happening on the back of the mechanism but he knew that there was one dial on the front with a Sun and a moon pointer and so he figured that he has solved what this thing was he saw it as a calender computer tracking the movements of the Sun and the moon through the sky so price died in 1983 but his work was continued by this man this is Michael Wright at the time he was a young curator at the Science Museum in London this is a more recent picture of him and he is a mechanician he loves making models love's ancient gearing misses his little workshop in his home in London and he was really interested in prices work it was really brilliant insights that he had but the more that Michael Wright looked at it the more he realized that there was an awful lot more to this mechanism a lot more to be discovered about it so he traveled to Athens several times in the 1990s and took his own x-ray images and part of the problem with prices images was they were flat two-dimensional all the wheels are kind of on top of each other you can't really tell how they're arranged so Wright built a crude tomography machine where he could as he took the images he could swing the objects the fragments and the film together with respect to the x-ray source and you can do that in such a way so that only one plane is in focus at the same time so you could start to separate out the sort of three dimensions of how the wheels are arranged and then he built what he saw so this is from his model of the Antikythera mechanism so build he just cut the wheels himself and built them out of a sheet of brass one of the things that he did was started to work out what was going on on the back of this mechanism so this is where those concentric circles were except that he was the first person to realize that they're not actually concentric circles at all they were spirals and so there's two dials one above the other made of these spiral slots and the pointers had extent they were extendable arms with a little needle at the end that drops down into the slot just like the stylus on a record player and so they would each start at the middle run through the spiral and then when they got to the end the user would pick them up and put them back to the beginning again and Wright was also able to count the number of divisions on this top spiral and realized that it came to 235 exactly the number of months in the metonic cycle so through looking at the gear train leading to this as well he realized that this was a lunisolar calendar showing the dates of the of the new and full moon across the nineteen years of that metonic cycle there's actually he saw this little dial in the middle there the rights as well and that's divided into four and he initially assumed that this was a longer and more accurate period that was used by the Greeks known as the Olympic cycle which is made up of four metonic cycle Zoar 76 years actually more recently the latest readings of the inscriptions have shown that actually this was a four year dial and it had nothing to do with astronomy it actually tracked the timing of athletics games that were held including the Olympics we'll come back to that a bit later so that was one of the many surprises of this mechanism for a yeah so here you can see Olympia there it's now thought that actually there probably were originally two little dials inside and the other one probably was showing the clipping cycle prior price also may progress with the front big front dial he realized for example that there was originally a little ball that probably painted half black half white that rotated to show the face of the Moon and he also realized that on that big gear wheel we saw before with the the crop the force of spokes in the shape of a cross there were the traces of structures that had once been carried around on that wheel that had since been broken off and to work out what those were what he'd seen something similar in his work at the Science Museum in the astronomical clocks from the relations and in in those clocks there were structures carried around on bigger wheels that were used to model the motions of the planets so the planets because they don't orbit the earth obviously they're going around the Sun at the same time we are so they do cycle through the zodiac but not in a constant way they're speeding up slowing down sometimes they appear to just stop and change direction and in these astronomical clocks that was modeled using little wheels riding around on bigger wheels so at the time the theory for how it's were moving in this erratic way from ancient Greek times up until the 17th century was the theory of epicycles astronomers thought that the planets were moving in little circles at the same time as their big circle around the earth so looping the loop if you like and so that was modeled in these clocks by using little wheels writhing around on bigger wheels and so Wright thought well perhaps this is what was being done in the Antikythera mechanism so he built it so he had these little wheels for each planet so the Greeks knew of five planets Mercury Venus Mars Jupiter Saturn and so you can see there there would be a little wheel riding around on the bigger wheel with a pin sticking up that would go into a slot at this lever that would then be moving around so you get that back-and-forth motion and that would be transferred directly to the planet pointer so in his model he realized that the planets were being shown too and so not just constant motion you're turning the handle but you're actually getting all of these pointers moving around with the erratic motion to model the planets and when he suggested this he was working from these very tiny traces the actual mechanisms that showed the planets haven't survived and a lot of researchers thought that this just could not be correct they did not think that their ancient Greeks could possibly have done this and but more recently with the reading news new readings of the inscriptions it's actually the text talks about the planets and the motions that are shown and includes numbers and ratios that are exactly what would need to have been used for them to show the planets in this way so the accepted view now is that Wright was actually correct and it was showing the planets here as well as the Sun and the moon there were still some things that Wright could not work out and he didn't know what that bottom spiral dial was doing for example most of that part of the mechanism was missing but he had realized that this wasn't just a Sun moon calendar computer it was a plan you know it was showing the planets as well and then around 2004 he heard that another team was starting work the mechanism and this team couldn't really have taken a more different approach so Wright was working on his own and his little workshop with all of his traditional instruments get pouring through hundreds of radiographs making everything by hand this was an international team involving researchers from lots of different disciplines they had state-of-the-art technology costing millions of dollars and the team was put together by this guy so second from the left at the top that's Tony Freeth so he was a film maker in London and he wanted to make a film about the Antikythera mechanism but at the time there wasn't very much new to say about it Michael Wright hadn't published a lot of his work and Freeth was a mathematician by training and so he decided that if he wanted some new results put in his film he was going to have to find them out himself so he put together this team with lots of different academics and representatives of two different companies as well he were developing technologies that could help to image the fragments sort of more accurately than ever before one of those was called X Tech it was a little company based in Tring in Hartford shear and they were involved in imaging components for from industry to check for internal faults and they specialized in a technique called computed tomography or CT and this is using x-rays to image an object but not just from one direction they fire the x-rays of hundreds of different directions and then feed all of those images into the computer to build up a kind of virtual three-dimensional map of the internal structure of the object the only problem was that for the Antikythera mechanism they were going to need something that had very high penetrating power a very powerful beam of x-rays but also incredibly high resolution to seal the tiniest details and at the time no machine of that type existed but Freeth managed to persuade X Tech to develop a completely new machine to do this there it is they called it Blade Runner because they were hoping that one day they'd be able to use it to image aircraft turbine blades which they did eventually do actually and it weighed eight tons in November 2005 they shipped the entire thing to Athens because they can move the mechanism but it was worth it they got incredible images of the fragments down to resolutions of just a fraction of a millimeter and I just wanted to show you an example if I can just get this plane view that's doing something so this is that biggest fragment fragment a with the full spoked wheel and this is just scrolling down through the fragment so just sort of going through the depth of it so you can see there's that big wheel and then we're going through that to see the wheels that are behind it and then even deeper into parts of the mechanism that you just can't see at all from the outside so there's that central plate and then there's more structures behind that and you can just see how much detail they were able to capture and then you can see at the end this bite that's part of the spiral dial on the back of the mechanism and then just one other really quick one so this is the same fragment but this time just being able to rotate it in space to see it from every angle so that's one of the approaches they had for studying the fragments and then the other company that was involved with Sheila Packard in California I think that's about okay hewlett-packard we're imaging scientists called Tom mounts bender was developing a technique for modeling how different materials respond to light and he was doing this initially for developing more lifelike computer graphics and what he developed was this sort of gadget it was like a half dome and then on the dome he mounted 50 different flash bulbs and then he would have a camera and then he would put the dome in front of the object he wanted to image and then each flash bulb would fire in turn at the same time as he took 50 photographs so each photo was lit by a different bulb so lit from a very slightly different direction and so you can feed all of those images into a computer and build a kind of virtual map of that object's response to light and he soon realized that if you tweak that virtual map you can actually start to create lighting conditions that would not be possible in the real world so you could take something that was of dull stone for example and tell the computer to make every part of that surface reflect lights much more than usual and you can make that Dale stone look like glossy shiny metal and that got archaeologists interested because then you can make very sort of subtle tiny scratches in the surface of something really leap out and become much more visible so this is what it did for the Antikythera mechanism you can see that's what this fragment looks like in a photo and then this is what it looked like when you've sort of boosted its reflectivity to light so the inscriptions were really started to leap out and then the CT imaging actually was also unexpectedly really useful for reading the inscriptions because it turned out that there was a lot more lettering hidden just under the surface of the of the fragments because you've got a lot of layers of it all squashed together and there was a ten-year project after this to read and decipher all of those inscriptions that was published in 2016 and they were able to read in the end nearly three and a half thousand characters out of what they think was maybe about 20,000 characters on the device originally one member of the team said it was like having a whole new manuscript so together with all of this data that's really helped to transform again that understanding of the mechanism so they were able to confirm a lot of Michael Wright's ideas but they also added to it and particularly when it came to the back of the mechanism so this is this team's reconstruction and crucially when they did their project a new piece of the mechanism was found in the storeroom of the Athens Museum that no one had realized was part of part of this device and it was part of this bottom spiral dial that had been a mystery up until this point and so they were able to count the number of divisions and found that it came to 223 which I'm sure will instantly tell you what the the researchers knew that the ancient Greek astronomers used a 223 month cycle to track and predict eclipses so the pattern of lunar and solar eclipses roughly repeats every 223 months and the inscriptions backed this up as well because in some of these little month divisions you've got little brief inscriptions they called in glyphs and with different symbols that are basically telling you whether there is a solar or lunar eclipse possible in that month or both it's and it tells you the time of day or night but that eclipse is expected and there's also little index letters that then refer to more text that's around these dials that gives even more information about those eclipses and this includes directions which is thought to be perhaps either in the direction from which the disc is obscured perhaps changes in wind direction during or immediately after an eclipse and colors so black or fiery red for example and this was another complete surprise because the different astronomical models that are used in this device you know some of them are more accurate than others but this was the first thing that was found that has no basis in facts whatsoever there's no scientific way to predict the color of an eclipse for example but these directions and colors they did feature in astrology at the time so not for individual horoscopes but for bigger things like forecasting the weather or the the fate of a king or a whole country so this added a kind of astrological kind of tinge to the whole mechanism for the first time I just want to mention like one more feature inside the gear work which was possibly like the most impressive and that was like oh yeah this here for there's four wheels that we're sort of called the pin and slot components of the mechanism and and in particular if you look at and that's how they looked in the CT if you look at these two in particular you've got two little wheels and they're identical one is above the other same number of teeth same size but they're on slightly different centers that they're turning around and the bottom one is driving the top one so there's a pin sticking up from the bottom one into this little slot in the top one and because they're on rotating around slightly different centers as they turn this pin is moving backwards and forwards in this slot so sometimes it's driving this top way a little bit slower when it's nearer the center of the wheel and then sometimes it's driving it a little bit faster when it's near the outside of the wheel so this little device so the sort of the motion comes in here across to there and then back out here and what all that it's done it's just introduced a wobble into the speed so that it's speeding up and slowing down with a set period and is mathematically pretty much equivalent to a mathematical theory of the moon's motion that was developed by an ancient Greek astronomer called Hipparchus in the second century BC so the moon's orbit around the Earth is not a perfect circle it's an ellipse so it's distance from us is changing and so as you look at the moon in the sky it seems to be speeding up and slowing down dependent just a very tiny amount depending on where the moon is in its orbit and the Greeks didn't know about the elliptical orbit but they did know the timing of the speeding up and slowing down and so this shows that they had actually modeled that in the mechanism right and seen this originally but he was kind of confused about it because it's sat on this other bigger wheel towards the back of the mechanism that also seems to be turning and he couldn't quite work out what it would be doing there but throughthe when he looked at this had the benefit of this extra piece of the mechanism and he was able to work out that this turntable was turning at roughly once every nine years and that told him what this was all about because the the moon's orbit around the earth the ellipse the the sort of the axis of that ellipse is actually shifting through the zodiac once every nine years so not only have they modelled with speeding up and slowing down they put it on this turntable to model that shifting and the axis of the moon's orbit as well which is just so impressive and so that would have been been fed back to the moon pointer on the front and probably the moon phase ball as well and it gets even more impressive than that because this turntable itself has 223 teeth around the edge it's a key part of the gear train that leads to that eclipses prediction dial on the back and what the designer of this mechanism has done is he's put in an extra wheel to convert the motion of this turntable to be just what it needs to be to model the moon and then he's put in another wheel just afterwards to cancel out that change and reinstate the motion that it needs to have to drive the eclipses prediction pointer so to reduce the sort of amount of gear wheels that he needs to have a simpler design he's kind of doubled up on this big turntable so well I'll give you Tony Freeth words for that he says it's an absolutely unbelievably stunning and sophisticated idea I don't know how they thought of it we're just following in the tracks of the ancient Greeks so just to kind of sum all of that up you can see how the identity of kind of what people have thought this device was has still shifted over time for him prices calendar computer to rights planetarium to Freeth Eclipse predictor but they're all right really it did all of these things sometimes I think you could think of it almost like an ancient sort of tablet with all of these different apps in one box so on the back you've got its calendar you've got the Athletics games you've got the Eclipse prediction on the front you've got this dial showing you the movement of the Sun Moon and planets to the sky the phase of the Moon and you've got a little firm ation about what the stars are doing so and actually just on the front even just this dial you could see this as being a multifunctional according to historian called Alexander Jones who has been helping to read the inscriptions it kind of had a double purpose that you could see it as this is showing you the appearance of the sky as seen from Earth so you it's showing you where the planets were where the Sun in the moon was as seen from Earth but you could also see this from the outside as a kind of a model of the Greek cosmos as seen from outside from a God's eye view if you like because he thinks that each of these from the inscriptions he's pretty sure each of these pointers had a little ball on it representing the celestial body and there were different colors gold for the Sun fiery red to Mars and he thinks that they were positioned at different lengths along these pointers depending on the distance that the Greeks thought that planet was from Earth so if seen from outside you've kind of got the earth in the middle you've got the Sun Moon and planets all going around in their sort of respective orbits and then you've got the stars in the background represented by the zodiac scale we kind of have half the mystery solved there if you like we know what the mechanism was we know we know what it did we know how it works but there's a lot more to this like what's the story of the mechanism itself like where did it come from who made it why so I just want to talk a little bit about that and for these questions you can get quite a lot of information from studies of the shipwreck itself so this was a big trading vessel perhaps 30 or 40 meters long it was packed to the brim with this luxury cargo it would have been running very low in the water and this is an artist's impression of what it might have looked like in that storm at Antikythera and researchers have been since that the brick was discovered has been studying the the items found from the wreck to try and work out when did it think where was it coming from where was it going and that the statues weren't a great deal of help because a lot of those are antiques they were already centuries old when the ship went down but there were other items so pottery jars that held food and wine hundreds of them that came from Pergamon and a thesis on the Asia Minor coast as well of the islands as well as the islands of cars and roads there was glassware from Egypt that was perhaps loaded at the trading stop of roads so it was very clear early on that this ship came from the east and was heading west when it sank our best idea about the date of the wreck comes from the diving public pioneer Jacques Cousteau so he took a team of divers to Antikythera in the 1970s to make a film about it which you can still get on Amazon I think it's very interesting and they died down to see if the sponge divers had left anything behind they excavated a small area of the site and their techniques included having a massive suction hose that basically hoovered up the seabed and sent everything up to the ship and then it all kind of tipped out onto the deck of the boat above which I don't think you'd be allowed to do now but anyway they they found hundreds of small items there's this lovely bronze statuette on a rotating base there's golden earrings they found human bones but for dating the important thing was they found bronze and silver coins and these came from the cities of Pergamon and a thesis on the Asia Minor coast and they dated the rector between 70 and 60 BC so the first half of the first century BC so it seems that the ship probably started started at Pergamon and then sailed down the Asia Minor coast probably stopped off roads for supplies and then with heading west when it sank Antikythera and initially it was assumed to be a Roman ship so in the first century BC the Romans were still taking over the whole Mediterranean area and they carted like shiploads of Greek treasures back home to Rome but more recently another team of archaeologists has been excavating the wreck site and they they dated lead components from the ship itself I sorry not dated analyzed lead components from the ship itself so parts of the hull sheath being anchors sounding weights and they found that these components didn't come from Italy they came from either northern Greece or the Cyclopes so here and here so it seems that the ship was actually most likely made in Greece so perhaps it was a Greek training ship heading back actually to northern Greece rather than on to Rome we can also get clues from written sources from the time there are quite a few intriguing mentions of devices that sound a bit like the Antikythera mechanism and the oldest and sort of most trustworthy source on this is a Cicero a Roman statesman and writer who lived in the first century BC and he was on roads exactly the time when the Antikythera ship is thought to have docked there and so he said in one source he talked about an instrument recently constructed by our friends Posidonia s' which at each revolution reproduces the same motions of the Sun the moon and the five planets that take place in the heaven each day and night and then another source he talked about an astronomical model invented by Archimedes that he said represent he said that Archimedes had thought out a way to represent accurately by a single device for turning the globe those various and divergent movements with their different rates of speed and for a long time historians didn't really know what to make of these kinds of stories because Cicero didn't have any technical training he didn't explain how these devices worked some of them appear in fictional dialogue so we could have just made the whole thing up but this new reconstruction of the Antikythera mechanism as sort of exactly this implies that actually perhaps he was basing these tales on on reality so let's just look at this first account a little bit more so Cicero's friends Posidonia s-- he was a philosopher working on roads in fact Cicero was visiting Posidonia on roads exactly when the Antikythera ship is thought to have been there and pasta donees did a lot of work in astronomy he would have had access to state-of-the-art technical workshops and there are actually some other clues that tie this device to roads one of them is Hipparchus oh I mentioned earlier so he was one of the greatest astronomers from ancient Greece and it was his mathematical theory of the variation in speed of the moon so he his theory involved two but the moon's orbit being slightly displaced from the center of the earth so to sort of circles with the space centers that's very close to what is we actually see modeled in that little pin slot component in the mechanism so maybe that device Wars that are made later on roads and directly influenced by Hippocrates work also coming back to that games dial these are the games that are named on the dial and the top four were really big events there would have been known across the Greek world but the bottom two were much smaller of only local interest and this one Hilaire took place on roads so Alexander Jones who has been reading a lot of the inscriptions thinks that this is a bit like a made inroads label if you like he thinks that the device was indeed made on roads and perhaps in pasta Dennis's workshop but that's not the whole story because na was held in Northwest Greece so Jones thinks oh and also the month names on the spiral the calendar the top spiral on the back of the device there are also local names and they come from a calendar that was used in Northwest Greece so Jones thinks the most likely explanation is that this was made on roads with that ice maiden roads label but was customized for a customer was being made to order for a customer in Northwest Greece so they've added in the right month names of him they've added on now and was being shipped to that customer when the ship went down so this is the area here where now was held where the month memes come from and that fits really nicely with this newer idea about this as a Greek trading ship but the Antikythera mechanism itself it can't have been the only one of its kind or the first of its kind it's just too sophisticated too small too complex it seems that there must have been other simpler devices of this type before that perhaps that have been sort of developed over generations becoming more complex over time and that brings us to Cicero's other story about Archimedes because Archimedes lived a couple of centuries earlier Sicily anyway in Syracuse and he is actually a quite good candidate for somebody you might actually invented this lot this whole line of models of the cosmos in the first place so obviously he was a legendary mathematics and engineering genius but his father was an astronomer so he may well have been interested in astronomy in astronomy and we know that one of his Lost works was called on sphere making and aspheres or the Latin words Ferrer this was used as a generic term for this type of models of the cosmos so it's and researchers argue about whether the device made by Archimedes that Cicero was talking about would that have involved pointers on flat dials like with the Antikythera mechanism or could it actually have been a sphere these devices later became known as kind of spheres of Archimedes and this was the model that Michael Wright made sort of using details and Cicero's accounts he made this a few years ago to try and prove that he could have done it actually as a sphere so if you imagine that the earth is sort of in the middle in the center of this globe and then this is a globe with representing the Stars the fixed stars and then you turn it here and then these pointers are showing the movement of the planets through the sky and then this represents the horizon here so these are the stars above the horizon so he could have done it that way but either way perhaps Archimedes was the first to come up with the idea of using mechanical gearing system model the motions of the heavens and then that got developed over time perhaps incorporating there's a latest astronomical theories like epicycles or the park assist model for the moon as they became available and that's perhaps as close as we can get so they're possible people that were behind this device but what was it for and here most specialists who have studied it they say it's hard to think of any practical purpose for this device so that it wouldn't really give you any information information for navigation that you couldn't get much more easily in other ways perhaps you could use that front dial with the positions of the planets forecasting horoscopes in astrology but again you could do that just as easily with astronomical tables and doesn't really explain other functions of the device one possible clue is that the inscriptions on the mechanism they seem to be designed for a non specialist they've been described as not so much operating instructions but more like an extended caption sort of explaining what you can see on the dials so the sort of thing that you might find in a text book for example or you know accompanying a museum exhibit so it seems that this was rather than a research instrument or a practical tool it was more sort of a teaching device for explaining and demonstrating to an educated but lay audience the workings of the heavens and it was thanks I sort of described it earlier it may be a sort of tablet with all these different apps but it was more than that of course it was a model of the universe of everything that sort of the Greeks understood and thought to be important about the cosmos at the time and so that wasn't just scientific it was also social it was astrological it was what was going on in the sky what was going on on earth all sort of entwined together and that's a vision that was expressed really beautifully I think by a Roman author called cassiodorus he wrote a letter in around five or six AD to the philosopher berteus and he was describing an Archimedes spear and he said it was a little machine pregnant with the cosmos a portable sky a compendium of all that is a mirror of nature what a thing it is for human beings and make this thing which can be a marvel even to understand so I think that's really nice and it's actually one of the last ever descriptions that used to be see in the historical record of this kind of device after that just disappears so what happened and it's a first sight it seems that perhaps this amazing technological tradition like so many other technologies just didn't survive the collapse of the Roman Empire but if you look more closely you do start to see some hints that at least some parts of this technology did survive and the first one is this this is a unique object it's actually what first got Michael Wright interested in the Antikythera mechanism and it's a sundial from the Byzantine Empire dating from the sixth century AD that was brought to the Science Museum in 1983 by eleven E's man an anonymous Lebanese man he had it in pieces in his pocket it was we wanted to sell it to the Science Museum and Michael Wright was one of those who studied it and he reconstructed it from the pieces and this is the model that Wright built of it and these are the portable sundials are well known they looked like this on the front you've got a bar that crossed a shadow you can tell the time but this one was different because it had gear wheels inside and he worked out that those gear wheels were just eighth gear wheels were driving a simple calendar on the back that was showing the positions of the Sun and the moon in the zodiac the phase of the Moon the day of the month and it was driven by this ratchet on the front so these represent the days of the week and the user would just click it around once each day so this is not that long after that letter that I just quoted and it's much simpler than the Antikythera mechanism much less accurate but it's proof that that the essence of that idea of using gears to model the heavens survived into the Byzantine Empire the next time we see anything remotely similar is in this manuscript which surface for sale in London in 2005 before it was snapped up by an anonymous dealer and it's a 12th century copy of a 10th century manuscript attributed to an astronomer called nasty list he was working in Baghdad and among other things that describes what NASA was called a box for the moon and it had eight gear wheels losing my spot there and they drove a display so this was attached to an astrolabe not a sundial but it drove a display on the back of the astrolabe showing the position of the Sun in the moon in the zodiac phase of the Moon day of the month it's exactly the same and this is hundreds several centuries later and this is now Arabic not Greek the Islamic world so it's showing that that technology has made it through and there's actually a physical exam of this this is a national aid from the 13th century from Iran that's now held in Oxford and on the front it looks just like all the other Ash Labor's that we have but on the back here again you've got the Sun in the moon this time on the same dial some of the moon in the zodiac phase of the moon day of the month and it's got the same 8th gear wheels inside so it's got that far and historians are pretty sure that this technology did then make it back from the Islamic world to Europe where it helped to trigger the invention of mechanical clocks so the the key sort of creative leap and the invention of mechanical clocks was the escapement that we heard about earlier so it's this back and forth mechanism that regulates a falling weight into even chunks so you can use a falling weight to sort of derive a mechanism at constant speed but there's a bit of a puzzle because usually when you have a new invention it starts simple and gets more complicated but the very first mechanical clocks that we see appearing in monasteries and churches around 12th century Europe were not simple they didn't just tell the time they were huge astronomical display pieces really complicated with layers of epicyclic gearing and they showed the Sun the Moon the planets they showed eclipses telling the time was really just an afterthought it was only much later that clocks kind of shrank and simplified and streamlined and become became more like sort of the time pieces that we're more familiar with today and it seems that the most likely explanation is that this technology for making sort of more geared models of the heavens had survived and was kind of waiting in the wings and then when the escapement was invented that enabled these things to be won automatically it all kind of came together and you have this explosion of these astronomical clocks I just oh yes what I was going to say about that is that this kind of shows that this isn't actually a lost technology at all but it did survive and that there is a direct link from those ancient sort of 2,000 year old that looks so familiar to us and we see them in the x-rays through to the watches that were wearing on our wrists today I wanted to finish just with this animation which is which shows that's not the right right so this was this is showing us with the internal workings of the mechanism and it was developed by an italian astronomer called Moki vision teeny that's why it's got a lot of Italian subtitles on it and it's made according to a reconstruction of Michael writes I should just say that at the time right thought that the Box had a kind of stepped shape but actually now he and others agree it probably was more like a shoe box with inscriptions above and below the dials and I wanted to show it to you just to get across the breathtaking complexity of the wheel so that you could see all of it together and also because I think it's really beautiful and while that's going I'll just say that you know so most of the big questions we have about the mechanism have now been answered so the still research going on researchers are still arguing about sort of smaller points to do with the working so the exact Eclipse prediction scheme used for example or how was the varying motion of the Sun models but we have most of the big answers but there is one sort of more plus one more puzzle about it that really intrigues me and that is which came first was it the the mathematical theories of how the heavens work or was it these practical models because it's always been assumed that the kind of the theories came first and then the Greeks tried to work out how they could represent those in bronze using gear wheels but it was suggested a few years ago that it might actually be the other way around that in some cases at least it was the machines that inspired the theories so if you take the idea of epicycles for example you can imagine that maybe you know a mechanic was in his workshop with it trying to use gear wheels playing around with them seeing if he could find a way to use them some model the back-and-forth motion of the planets in the sky and he realized that he could do it by mounting little wheels on top of big ones and then maybe that is what inspired the theory of epicycles and probably the two things the theoretical ideas and the practical models what kind of worked them together sort of bouncing off each other over time but I loved the idea that perhaps it was these kinds of devices that were helping to kind of inspire and drive those theories about how the universe works and this isn't just about any sort of specific theory or mathematical model or particular celestial motion this is probably true in a much bigger sense as well because the more we learn about the Antikythera mechanism the more it seems like devices like this we're actually helping to subscribe and inspire that overarching idea of the cosmos as a machine you know the universe as a physical mechanism that has an underlying order to it that doesn't just work through the whim of four gods but it's actually working according to rules that rules that we can measure and understand and predict and for me that is why I'm just gonna that is why this object is so exciting because within these sort of ancient gear wheels there is an idea that changed humanity this metaphor of the universes and machine that it's a metaphor that became an entire philosophy you know Eltham utley this is what triggered science and our modern world view so I'm just going to finish on a slide for more information if you're interested and thank you very much [Applause] [Music] [Applause] [Music] [Applause] Joe thank you very much indeed that was just fantastic it's a the complexity of that is just amazing and then realizing that you know they had Archimedes they had Cicero talking about this they had metal gears I think because they had steam power with hero of Alexandria so you kind of wonder maybe they're on the verge of you know an industrial revolution if they could have powered this but clearly they didn't but all as he only the mechanism has gone through there must have been very close to that perhaps and it's bringing us to today it makes you think well you know what are we missing that we could put this in this together and do something completely novel that we haven't imagined anyway we could we can imagine for ages next week we remain with mathematics and technology but we're moving forward in time when dr. James grime will lecture on Alan Turing and the Enigma machine so again more of sort of hidden things happening in boxes so we hope to see you then but again finally Joe Marshall and thank you very very much indeed for coming to talk to us this evening [Applause] you

Channel: Darwin College Lecture Series

Views: 196,575

Rating: 4.869638 out of 5

Keywords: Darwin College, Darwin College Lectures, Darwin College lecture series, Enigma, Decoding the Heavens, Jo Marchant, Science correspondent, world’s first computer, Cure: A journey into the science of mind over body, New scientist, nature, University of Cambridge, Antikythera Mechanism, decoding the heavens

Id: Iv-zWbxm2lY

Length: 64min 39sec (3879 seconds)

Published: Wed Feb 05 2020