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29 Sep 2005 Listen to the In Our Time for 29 Sep 2005 For a trial period In Our Time will offer an edited transcript of each edition. THIS WEEK'S PROGRAMME: MAGNETISM MELVYN BRAGG: Hello. Pliny the Elder in his Historia Naturalis tells a story of a legendary Greek shepherd called Magnes, who, while guiding his flock on Mount Ida, suddenly found it hard to move his feet. The nails of his sandals held fast to the rock beneath them, and the iron tip of his crook was strangely attracted to the boulders all around. Magnes had stumbled across the lodestone, or magnetite, and discovered the phenomenon of magnetism. Plato was baffled by this strange force, as were Aristotle and Galen. Despite being used in navigation - first by the Chinese - supposedly suspended over the body of Mohammed, and deployed in the pursuit of medical cures - apart from some thirteenth century scholastic studies - it wasn't until the late sixteenth century that any serious scientific attempt was made to explain the mystifying powers of the magnet. Who pioneered the study of magnetism, what theories did they construct from its curious abilities, and how was the power of the magnet brought out of the realm of magic and into the service of science? And do we really know what it is even now? With me to discuss magnetism is Stephen Pumfrey, senior lecturer in the history of science at the University of Lancaster; John Halbron, America's professor of history at the University of California, Berkeley; and Lisa Jardine, professor of renaissance studies at Queen Mary, London. Stephen Pumfrey, the fact that there was no satisfactory explanation of one lump of iron attracting another, or a magnet moving its position to point in one direction, didn't stop people using them. Can you tell us when magnets were first used and what for? STEPHEN PUMFREY: Well as you said, the Chinese were the first to discover this property of magnets pointing north, and it was really in Europe around the time of the Crusades that European navigators started to use magnetised needles in their ships. MELVYN BRAGG: Had this come from the Chinese through the Ottomans? STEPHEN PUMFREY: Yeah, yes, I mean through the trade routes, and it was I think when the, well as far as we understand when the Crusaders sailed to the Levant from the port of Amalfi , it was there that they first encountered primitive compasses. And they used them in the mediaeval period really as a sort of rough check on north, especially when it was cloudy, and as we all know compasses do point roughly north. But it was really during the age of exploration, when the Spanish and Portuguese lead Europe in exploration of uncharted territories, that the compass came into its own. And all progress really up until 1600 was made by these seamen rather than philosophical scientists. MELVYN BRAGG: And the main point of the compass and the main help it gave was that you could navigate away from the shoreline. STEPHEN PUMFREY: That's right. With the age of exploration navigation changed from knowing roughly where you were from the shoreline to sailing completely uncharted waters. And the Portuguese first began to discover that the compass didn't actually point at actually north, but deviated slightly. As they sailed to the Orient, they found it sailed east, and that rather screwed up the sort of standard philosophies of the period that it somehow had some magical correspondence with the celestial pole. MELVYN BRAGG: Because there seemed to be two poles - the north pole and the true pole - and also it varied, when you were in different parts of the globe it varied. STEPHEN PUMFREY: Well that's right. And indeed when Columbus led the Spanish to America , as he later discovered, he was astonished to find that the compass pointed west, and at this point people were really very confused as to how the magnetic property operated at all. But there was one saving virtue out of this disaster. MELVYN BRAGG: And...? Are you going to keep us all in suspense? We haven't got much time to cover this whole subject. STEPHEN PUMFREY: Which was that if the compass perhaps pointed east if you sailed eastwards, and west when you sailed westwards, could you perhaps use this difference in magnetic variation to solve the great pressing problems of navigation which was finding your longitude of sea. And up until the sixteenth century, navigators whose lives depended on it were trying to solve this problem. MELVYN BRAGG: There are two things to say about the compass. First of all this is a study in which practicality preceded theory quite emphatically and for a long time. STEPHEN PUMFREY: Well it certainly ran ahead of theories. MELVYN BRAGG: Ran ahead of theories. And secondly the compass was very important commercially, as you indicated, but also politically how you could move around the world and conquer people, and also theologically in the sense, religiously in the sense of how could you get across to these foreign places full of non-Christians and Christianise them. So we're talking about a very important instrument in many senses of the word. It was a man, an Englishman called Gilbert, in 1600, who did the first of the major work on a massive book on magnets 'De Magnete', and that's taken also to be the first scientific treatise perhaps on any subject. Can you tell us briefly what Gilbert did? STEPHEN PUMFREY: What Gilbert did was to talk to the extremely experienced English navigators who, because of the Spanish and Portuguese rule of the southern hemisphere, were forced to sail near the north magnetic pole - their compasses went sort of haywire really. So English navigators knew much more even than Spanish and Portuguese about it, and he learned a lot from them. He's consulted what Shakespeare would have called the rude mechanicals when many natural philosophers would not have thought of having them, having very much the same. And 'De Magnete' is his extraordinary book, it's got an extraordinary thesis, which is that the Earth is a giant magnet. It's got an extraordinary attitude for a Renaissance natural philosopher which is that because he thought that he knew that Aristotle and Plato had known nothing about the Earth as a magnet, he took the very radical view that really the ancients had nothing to say to us and their whole philosophy was to be dismissed. MELVYN BRAGG: Can I turn to John Halbron? Can you explain what Gilbert's theory was? We talked about 1600, he was the court physician to Queen Elizabeth I. JOHN HALBRON: Well Stephen said his notion has to do with the Earth as a magnet. In fact magnetism is the principal quality of the Earth, it distinguishes it from everything else in the universe. There's lunar properties that cause the moon to stick together, and Jovian properties that cause Jupiter to stick together, and our particular form of attraction is magnetism. And in fact the Earth's soul is a magnet, and the Earth's soul is more noble in fact than ours. MELVYN BRAGG: So was that a great discovery on Gilbert's part, that the Earth... JOHN HALBRON: It might be a discovery. Oh that the Earth was a magnet? No, in fact one of these mediaeval persons to whom you alluded, Petros Peregrinus, who seems to have been a teacher of Roger Bacon's, had many of the same ideas as Bacon, and had in fact done some of the experiments for which Bacon would later be - excuse me, for which Gilbert would later become famous, particularly modeling the Earth as a spherical lodestone. MELVYN BRAGG: So how far did Gilbert go with this first massive book? How far did he take us in the study of magnetism? JOHN HALBRON: Well he brought together what had been known, very greatly amplified it, but perhaps the most important thing is that he showed how, by a series of systematic experiments, it would be possible to exclude what was suggested as properties of magnets, which, such as killing its power by rubbing it with garlic, or that it would not perform in the presence of a diamond or any such thing, or that a pocket full of magnets would give you eloquence. I tried that incidentally, but I think you have to swallow them actually! So he got rid of a number of old and new wives' tales and he showed how by systematic exploration of this 'tirella', as he called it, this simulacrum of the Earth, this lodestone made into a sphere, it would be possible to show how the compass worked, and its declination, the variation of which Stephen has spoken, could all be observed on this tiny tirella. MELVYN BRAGG: And as Stephen said and as you indicated, he got a lot of his information from people down in the docks who'd come with their compasses from all over the world. JOHN HALBRON: He did, indeed, and he was something of a hobbyist, that he would rush down to the docks to get the latest rock from here or there and run home and test its magnetism and so forth. MELVYN BRAGG: How were his ideas received by his contemporaries, by Francis Bacon for example? We all know about the great Francis Bacon. How was he thought of? JOHN HALBRON: Well we do. I feel that I am most shy in speaking about Francis Bacon in the presence of Lisa, but... MELVYN BRAGG: Oh go on, get over it! JOHN HALBRON: I'll get over it, I'll get over it and say if - I suppose I can - if it were possible for Bacon to say Gilbert, what he did, not knowing anything about the subject, namely that he was a perfect example of this idol of the cave in which ones raises one's own hobbies or hobby horses to the level of philosophy, building, as he said, a philosophy out of the lodestone. But Bacon had a what... an ability to see, not to see what was the most progressive in the science of his time. MELVYN BRAGG: What did he mean, Lisa Jardine, when he called, Bacon called Gilbert being an example of the idol in the cave? LISA JARDINE: Well, it, it's interesting because Stephen's given us such a good account of Gilbert's sort of idea of a unifying theory of the magnet, that the Earth is a great magnet that you can account for all kinds of phenomena by regarding it as so. MELVYN BRAGG: And John also, John Halbron also said that it had a soul. LISA JARDINE: And that it has a soul, quite. MELVYN BRAGG: Which Gilbert also thought. LISA JARDINE: Francis Bacon was deeply sceptical of grand theories. The idols of the cave are grand theories, and he actually picks Gilbert out as an example of how a man who has very very good practical knowledge, very good practice, can get carried away and elevate what he's doing and what he knows about to the level of a grand theory, in which, as it turns out, he was profoundly wrong. MELVYN BRAGG: Gilbert was living in revolutionary times - I'm going to let that pass! - because you had the Copernican revolution going on. How did that affect the way Gilbert came to his conclusions? LISA JARDINE: I think - again we're all deferring to each other - I think that the Copernican moment if you like, in the middle of the sixteenth century, is a moment when the power of the mind, the power of the human mind to bring together observation and experiment, and to take the great ideas fly really - the movement of the planets, the attraction of the Earth, gravity as a possibility before, well before Newton - that it is the moment, let's say 1543 for Copernicus and then 1600, between 1543 and 1600, when these thinkers, who are practical men, interested in the commercial world, interested in experiment, how things work, get the courage and the mathematical knowledge to build that into great theory. MELVYN BRAGG: Because Copernicus has observed of course that the Earth did go round the sun, and Gilbert was saying well that's because of magnetism - magnetism explains it. LISA JARDINE: Well because of an attractive force, yes. Gilbert makes it magnetism. Bacon says you couldn't be more wrong, and the Copernican theory shows that there is some constant force that is pulling the planets towards the sun. MELVYN BRAGG: There's also for me the intriguing notion at that time of what was called 'action at a distance'. Because magnetism was invisible, and yet it had a force - it came off, it pulled the nails out of your shoes and so on - it was like, as they then thought, infection, which they didn't know about ............. and love. There were two examples they brought along. How widespread was this notion of action at a distance, and how did it affect the thought even of Gilbert himself? LISA JARDINE: Action at a distance we still are interested in. They were hugely interested in how sap is sucked up in plants, how people get the same idea, how people fall in love, and how bodies like. MELVYN BRAGG: Why is it called 'action at a distance' Lisa? One or two listeners might want that really spelled out. LISA JARDINE: Fine. Because whereas when I push this pen on the table, you can see the force acting on the pen, and you understand that the pen moves because I push it, if a planet moves around in the sky you cannot see the force impinging on the material body, and you therefore are inclined to think, in rather mystical and spiritual terms, about what's happening. The magnet in French is called an aimant, which is related to a lover, and there was a very strong sense that the kinds of emotional pressures that you can't see the force originating from but which affect other people, like my making eye contact with you, that those are mysterious, that they are related to magnetism, related indeed to gravity, related to electricity. MELVYN BRAGG: We're in a time of scientific - let's use that word - revolution at that time, but we're also in a form of great religious absolutism, where everything had to be filtered through religion, every idea. How did Gilbert in a Protestant country, a newly, fairly newly Protestant country in 1600, how did that filter through in religious thought, Stephen? STEPHEN PUMFREY: Well, although Bacon didn't like Gilbert's big idea that it was a magnetic force that drove the Earth around the sun, there were plenty of astronomers and philosophers who did. Keppler in fact made it the basis of his elliptical astronomy. And it was when Galileo also started using Gilbert's ideas to buttress his idea of Copernican(?), that the Catholic Church in particular became very interested. MELVYN BRAGG: Interested in the sense of let's ..................? STEPHEN PUMFREY: Well interested in the sense I think that... I mean the Catholic Church had this kind of body of highly trained theological and philosophical professionals - The Society of Jesus, the Jesuits - whose job it was to kind of take o potentially dangerous new ideas and neutralise them. And around the time when Galileo was making waves you could almost I think hear the kind of call coming out from their headquarters at the Roman college saying we need urgently a new Catholic, safe, Aristotelian theory of magnetism that above all proves that the Earth doesn't move, and within... for fifty years after 1628 it's Jesuits more than anybody else who publish it, and they do, to their own satisfaction at least, prove that magnetism is a property of the Earth but it holds it still at the centre and Galileo and Gilbert are completely wrong. So it's highly theologically charged. MELVYN BRAGG: John Halbron, what does Descartes add to the argument about magnetism? JOHN HALBRON: Well he changes the entire basis of the discussion. These souls, or let us call them rather special qualities, they're things that don't have, that are not further reducible - you cannot express them in terms of atoms or some sort of more primitive matter. So the world in full, in the Aristotelian case, with different sorts of things, irreducible things. Then comes Descartes, and he says that's nonsense, I'm going to get rid of all those various things that are supposed to be in the world and reduce the world to matter in motion - undifferentiated matter in motion. Well that's nicely said, but how do you do it with respect to something like magnetism, which has puzzled people for a good long time, and for which various explanations or forms of words have been used to remove this quality from the universe? And he has to do it by matter in motion. So what he imagines is that there are specially shaped little particles which... and that magnets and iron have very specially shaped little pores in them, and that the little particles go through the pores, and finding themselves unable to penetrate further into the atmosphere because of their shapes they come round back to the bottom of the magnet, and in the course of their motions accomplish magnetic attraction and repulsion. Now I should say that Descartes' little particles that do these things are a product of the Cartesian big bang, s they come from the very formation of the universe, so magnetism is radically important as being a consequence, a relic if you will, of the Cartesian big bang. But you see he's got rid of the quality - that's the essential thing. He has reduced the world to a very uninteresting place without these special qualities. LISA JARDINE: And of course that turns out to be a vain hope, because of all the... Magnetism, I think the reason people are so intrigued by magnetism is it never loses that sense that there are occult qualities associated with the draw of the magnet, which will never be encompassed simply by matter in motion. MELVYN BRAGG: How did Descartes' ideas fall down? I mean, and they've been very clearly explained by John. Why did they not have greater acceptance? STEPHEN PUMFREY: Well look, I mean actually they did. I mean Descartes' ideas of a sort of mechanised universe which gets rid of the magic which lies behind magnetism, did have a wide currency, and they did change the face of scientific thinking. The unfortunate thing is that there are some things that really don't work very well explained this way, as John said. And it's Newton as it were who shows that really you can't have a fluid system, fluid explanation of magnetism. I'm reminded of a... there was some vain Italian philosopher who wrote to the Royal Society and said that he had a theory of everything, and the Secretary of the Royal Society wrote back and said, 'That's very good, what we'd like to know first please is your explanation of gravity, the spring of the air and magnetism'. These were the things that mechanical philosophers just simply couldn't deal with. And Newton 's success is coming up with a different way, which in a sense brings back the magic. MELVYN BRAGG: Hold on, I want to get to Newton in a minute. I'm going to go through Halley. Do you want to say something? LISA JARDINE: I just wanted to say that you know we talked about the practicalities, the fact that this was, magnetism was a phenomenon that was discovered in practice and by seamen and by navigators. One of the reasons that Descartes' theory collapses is, it doesn't work, it's no use to you on a ship. You know the precision of the mechanical universe is a grand idea, but it doesn't work. And there has to be this interplay between the grand theory and the practice on the ground. JOHN HALBRON: Yes but you have in these little particles and their trajectories, you have a perfect image of the iron filings that are scattered round magnets and which we all saw when we were children, and so it became a challenge to calculate just how those iron fillings, or if you prefer the course of these little particles, worked out. So even though Newton came along, there were a lot of Cartesians for many years who kept speculating about how this trick could be played. MELVYN BRAGG: We're running the practical and the theoretical together, and enter a man called Halley, who was an extraordinary man - wealthy, Newton's patron, got Newton... financed the publication of Principia(?) and so on, an astronomer himself, but he, one way and another, went round the world with the Royal Navy to try to make a magnetic map of the world. Could you tell us about that please? LISA JARDINE: Halley is a magnificent example... MELVYN BRAGG: It's he of the comet isn't it? LISA JARDINE: Halley of the comet. Halley, probably the most hands on, successfully hands on of the early Royals, members of the Royal Society. He was born in 1656, he was born in the middle of the English revolution. He came back, sorry he grew up in the returned monarchy, which was desperate for money, and therefore commerce and science go hand in hand in that period. Even as a young man, under twenty, he decided he would go to St Helena in the middle of the, in the middle of nowhere as far as contemporary Europe thought, but the southernmost point that England owned, in order to map the stars, in order to help navigation, to navigate south of the equator. Magnetism took his interest on that first voyage. He subsequently became a very proficient sea captain himself, and then went off to try and explore, in the 1680s and 90s, the way in which the magnet refuses to behave, as Stephen explained so beautifully, the magnet refuses to behave as you move around the oceans. So that this variation, the way that the compass needle points way from geographical north towards somewhere else - that's called, the angle between them is called the angle of magnetic variation - Halley decided that it must be possible to map that, and indeed he took numerous - though we're not quite sure how many - measurements as he sailed on a very long voyage across the Atlantic Ocean, and he called in measurements from anybody else who was taking measurements. MELVYN BRAGG: And he produced something called an isogenous. Isogenous? STEPHEN PUMFREY: Isogenous I think. MELVYN BRAGG: Is it? Isogenous is it? Missed the hard 'g' there Stephen. Map. Now then can you tell us about that and how good his isogenous map was. STEPHEN PUMFREY: Well he did produce this very wonderful map joining up points of similar variation, and driving it all was this still pressing problem of the longitude. I mean Halley was certainly hoping that if he could map this accurately enough he would be able to use magnetic variation to solve the longitude problem. LISA JARDINE: That is to tell the navigator where he was on the great circles of the globe. You knew how far you were north and south, but you could not map precisely - that's the longitude problem - where you are as between east and west. STEPHEN PUMFREY: East and west. And maybe if you could just look at your compass needle and say oh look it's four and a half degrees, my map tells me that off the coast of Newfoundland twenty miles away it's one half degree, that's where I am. And that would have been fant... I mean governments were prepared to pay millions of pounds in today's money for someone who'd come up with that solution. And unfortunately it doesn't work. I mean it doesn't work because variation actually changes over time. Halley knew that. He had an elaborate theory of four poles of the Earth in which he hoped to predict the change, but that doesn't work. And indeed scientists today who rejoice in the name of geomagneto hydrodynamicists, have a few good model of the interior workings of the Earth, but in terms of being able to use that model to predict actual compass bearings on the surface, we still can't do it. So the only way that would have succeeded would have been if Halley or someone like Halley had gone out every five years to re-map it empirically, and no government was prepared to pay for that. JOHN HALBRON: Which is also the awkwardness, I believe, that the lines in question don't change much, the variation doesn't change much as you go east west in the latitudes of interest, so it wouldn't have helped at all ............ STEPHEN PUMFREY: Especially given the problems of using a compass at sea. JOHN HALBRON: Yes. MELVYN BRAGG: John Halbron, Newton 's name is entered unnecessarily into any discussion of science around this time more than once. What did he.. . Did he concern himself - I know he did but you answer the question - did he concern himself with magnetism, and what did he find out? JOHN HALBRON: He did concern himself with magnetism, as with all other things, but yes his approach was quite interesting, perhaps just because it differed so much from his approach to gravity. He was interested in it as a form of attraction, as he was interested in electricity, but in the case of magnetism he did not do what he did in the case of gravity, which was to add up all the little forces between all the little particles of gravitating matter in the apple and the Earth, or the apple... the Earth and the moon, and so forth, but rather just took on the two magnetics, or magnetic and a lodestone, and ask what the force between them was. And he got an answer, which of course was very peculiar and dependent upon his experiment, because the force between what? The nearest, the poles and, or between the nearest surfaces, or whatever? And so he gave an expression for this force between them, which was not... which people then were unable to reproduce. Now he did not take this approach of gravity, which is to go between little particles of magnetic fluid - that would have been the analogy - but rather a gross approximation using the bodies in question. And I'm sorry I did not say that very clearly, but the point here is that the essence for the mathematician, and the exact experiment of Newton 's gravitational theory was just to be able to define a clear, distinct force, and that was not possible for magnetism for a long time. MELVYN BRAGG: Why was it not possible? I mean gravity seems, is still one of... people are still mulling over, ruminating over, all acknowledging the greatness of Newton's contribution there - why did magnetism seem so... He lost interest in it really, but why did it seem so much.....................? LISA JARDINE: Well the magnet is - a magnet, we're talking about magnets you know that we are quite sure what they are - a magnet is such an interesting object, and very different from remote planets, which you can reduce to point matters and calculate the mathematics of how they move. Every time you break a magnet it turns into two little magnets, with a north and a south pole and all the properties intact. You keep on breaking the magnet, it keeps on reproducing itself with the poles closer and closer together. MELVYN BRAGG: So these ............... are not coming from one thing but from two things ................? LISA JARDINE: From two things, and... STEPHEN PUMFREY: Well with two magnets, four things - that must have been very confusing. LISA JARDINE: And it's just extremely confusing on that scale. MELVYN BRAGG: It doesn't only attract, it repels and attracts, unlike ......... LISA JARDINE: Well so the like poles repel and the unlike poles attract, and it's really sad in a way that our own children can't do those experiments because magnets are so dangerous around computers. My home as a child was full of magnets, and all these properties with iron filings and producing patterns of iron filings around the poles of a magnet. We all can actually see them in our mind's eye - nowadays they're not even done in school. However Newton, in a way it shows that Newton is an absolutely brilliant mathematician, that is he wants the large theory, the mathematic, as the equation that will capture simplified systems in a way that will produce results which are helpful in everyday life, which is actually what the theory of gravity does. But magnetism just didn't work like that. And he lost interest because he was a - I don't like Newton , but he was a very characteristic... MELVYN BRAGG: You don't like Newton .................. he's a genius. He was an unpleasant man but a genius, and we can live with that. LISA JARDINE: But he was a tiresome man and when he couldn't solve it he discarded it, so he couldn't work this one out properly. MELVYN BRAGG: Well he's more sensible, he'd got other things to do. I think that's a very sensible thing to do, on the theory that you can't do everything for goodness sake Lisa! Maybe you can, but Newton couldn't! STEPHEN PUMFREY: Despite the fact that he couldn't measure it, John, did he not sort of declare as it were that he was sure it was an inverse cube? I thought that was something he just wanted to kind of differentiate. LISA JARDINE: Inverse cube? STEPHEN PUMFREY: Yeah. JOHN HALBRON: Inverse cube. Well he says from some rough experiments that I have done I think it's something like the inverse cube, and then as you say he sort of moved away from the problem. And magnets are even worse than Lisa has described, because, for example, they will lose their magnetism. And you put them in a fire, they lose their magnetism, you put them on the shelf too long, they lose their magnetism. And worse yet, you can change the poles of the things. So gravity is a piece of cake, in conclusion! MELVYN BRAGG: Well we're going to do a programme on gravity now, I'm not looking forward to that quite as much as you seem to. But let's move on to the 1780s where there's a French physicist, Charles Coulomb, devised an experiment that moved even further into magnetism. John Halbron, can you tell us about that? JOHN HALBRON: Well here is the Newtonian experiment at last with respect to magnetism. By the time Coulomb, who was an engineer, came on the scene, it was possible to make very long, narrow, thin magnets. Think of essentially a magnetised steel wire. And that well localised poles, so now you get back into the point story, which.. and a geometry that looks like the, a geometry of the gravitational system. And what he did was to put up two of these magnets, facing one another, and allow one to be mobile and the other fixed, and to drive the mobile needle around, and by measuring the deflection was able to calculate that indeed a magnetic fluid analogous to ponderable matter could give rise to, or did give rise to forces which depended upon the inverse of a square. And that he took to be confirmation of the Newtonian picture, that it would be possible eventually to discuss all phenomena in terms of attractions and repulsion, because you see he got the law, he got something that was quite analogous to the gravitational theory, which Newton had not been able to do. MELVYN BRAGG: As a mere observer now, it's quite interesting that as an engineer suddenly - we've been talking from the beginning, since the Chinese, about the practicalities of this matter, and Gilbert went and talked to ............... and so and so, it's an engineer who brings the two together. JOHN HALBRON: Yes, and through a special balance that he invented, which was essentially a thread or a wire that bears the body on which you're going to do your experiments and which can be twisted, and the twist of the thread produces a force which Coulomb measured very carefully, and it was that twist, that force of tortion that he balanced against his force of magnetism. MELVYN BRAGG: How successful, Stephen Pumfrey, was Coulomb? How successful in spreading his ideas? Did people take that on and think it's been solved? STEPHEN PUMFREY: Well I think very much so. I mean Coulomb had done what Newton was unable to do with his engineering skill, show the inverse square law of magnetism. Coulomb's perhaps most famous today I think for showing that there was an inverse square of the electric point charge as well. We talk about Coulombs as a unit of electricity. So by the end of the eighteenth century French scientists in particular looked like they've got to the end of the Newtonian programme, you know they're arriving at the grand unified theory. Everything in the universe - gravity, magnetism, electricity, the lot, can be explained in terms of the simple mathematics of inverse square laws of forces, and whether or not Pierre Simon le Plas, who was the great, well the great collaborator of Coulomb, actually said this or not. And the idea is that you can sort of get the magic, you can get God out of the universe. We can calculate and predict exactly how the universe goes. So Coulomb's work was very important. He didn't actually I think push it that far. He became a kind of great technocrat of the kind who ruled France ever since the eighteenth.. the French Revolution - didn't I think play much further part, but his ideas go into this gradually fine thing, which is actually a bit of hubris because they were about to find that they didn't understand these things as well as they thought. MELVYN BRAGG: What about the culture of magnetism in the eighteenth century? What was going on in the sort of funfairs and drawing rooms? LISA JARDINE: Well the lure of the occult version of magnetism never went away, and so what you get, at the very moment when you're getting these grand theories, of the unified theories of how gravity and magnetism are subject to the same law of, inverse square law of attraction, and you get the funfairs producing more and more elaborate versions of men with, usually men, with bundles of magnets making young ladies faint at the funfair with erotic ideas that are generated from the bag of magnets. And of course Mesmer is the past master of exploiting these ideas of magnetism. You have to remember that all these scientific ideas get exploited one way or another, but again the magnet is so deliciously handleable and its properties are so wonderfully curious that drawing in the idea of emotional attraction or curing someone almost in a Freudian... as Freud did by interaction of magnets rather than the talking cure - that is literally how magnets are being used in the eighteenth century. STEPHEN PUMFREY: But it's also a kind of religious experience in a way isn't it, because after all if you take Newton seriously, magnetism, gravity, electricity, are all signs of the divine power hidden in matter. So when you conjure up the magical powers of magnetism you're experiencing the design as well - that's a big ..................... MELVYN BRAGG: So ............... idea of the soul and magnets having a soul, and then Gilbert's idea of having a soul, persists still. But it ended into worldwide superstitions as well didn't it? What about the superstition that if you put magnets under the marital bed you discover whether or not your wife was being unfaithful? LISA JARDINE: Well, exactly. I mean... MELVYN BRAGG: There's a connection with sex going through this isn't there? LISA JARDINE: Had to get sex in somewhere! MELVYN BRAGG: No I didn't, I don't do that sort of thing, but there just is. STEPHEN PUMFREY: Well Lisa mentioned that the French word for magnetism is aimant, and Gilbert was so sort of obsessed in a sense with this kind of sexual angle that he wanted to abolish the word 'attraction', he thought that was vile, it was like kind of rape The word he used was 'coition' - magnets are two lovers coming together. Sex does run through this. LISA JARDINE: And remember, you know we just have to think for a second - attractive, 'she's a very attractive woman', 'I am attracted to him' - those words, and I looked up the etymologies last night, the etymologies all run together. They come from magnets, into the sphere of the discussion of sex and emotion. MELVYN BRAGG: John Halbron, would you care to be engaged in this rather lowering of the tone? JOHN HALBRON: No I've been fascinated by it, and I of course think of Mesmer, whose little games often had an erotic character to them. The passing of one's hands over the magnetiser's hands, over the body of the ill to effect... LISA JARDINE: Usually female. JOHN HALBRON: Usually female - to effect a magnetic cure, to restore the balance of the animal magnetism and so on. Mesmer incidentally, who was a rather engaging character from time to time and a great lover of music, was a sponsor of Mozart, who then repaid the debt by making a magnet a principal character in Cosi Fan Tutte, right, where this quack - well I can't remember the story exactly but this quack made passes of a magnet over the bodies of the suitors who were supposed to have taken poison, who then immediately quake and shake in the approved manner of the mesmeric crisis. MELVYN BRAGG: But in this sort of cultural, subcultural stratum it's competing with electricity, with people like Galvani who puts a charge through a frog's leg and the dead frog twitches, and then we lead to Frankenstein, our life is just a series of pulses which can be put in from outside. So it's an interesting game. It's coming from magic but it's verging on science as well isn't it Stephen? STEPHEN PUMFREY: Well not I mean that's right. I mean it's easy to dismiss Mesmer as a charlatan or a dreamer, and many at the time, as now, did, but just at the time when Mesmer's reputation looked it was going down the pan - you know the Academy of Sciences set up a commission with Franklin and La Roissier to find out whether there was animal magnetism, mesmeric fluid - just at the time that that's looking dodgy, Galvani comes up, as you say, in Italy and sort of puts electricity through a frog and electricity looks like it's a kind of fluid, so why should there not be a magnetic fluid of life as well? And this does have serious sort of implications, because are we getting to the point now, as you say, with the Frankenstein's Monster, is - have scientists tamed, or are they in danger of thinking that they can tame the life principle, the animate principle down to a series of physical fluids? JOHN HALBRON: Let's go another way from Galvani too, and remember that Volte comes out of this story. From Volte comes the electric battery, and from the electric battery comes various things to which you I'm sure will lead us in good time. MELVYN BRAGG: Well there isn't much time, but we're going to get to Faraday ............... Let's get to Faraday now.. What did Faraday contribute? Do you want to kick off John? JOHN HALBRON: Well I think we ought to back up one step if you will before we get to Faraday, which is to introduce Hans Christian Oersted, who succeeded in a project in which many people had been interested from the eighteenth century on, which was to show some connection between electricity and magnetism. There were many indications that there was a connection, one of the most curious of which was that iron fire tongs struck by lightning were often magnetised. So Oersted and many others, imbued with the notion of the interconnection of all things, sought to show that there was some way in which electricity could produce magnetism and vice versa, and he succeeded in 1820 by showing that the current carrying wire could produce a magnetic force, which set up of course a quest for the opposite effect - how magnetism somehow could create an electric current. Faraday was one of the first to take up the Oersted effect, and then interrupted his researchers for various other things, returned to them in 1831 and then found that a combination of magnetism and motion and electric, rather a current - excuse me, a circuit, a wire - could produce electricity, which enabled one to say that these powers were inter-convertible. MELVYN BRAGG: Amazing to think - we're in a quite small studio here - it's amazing to think that in a room not much bigger than this, just round the corner isn't it? So what did induction or electromagnetism do, Stephen, in the story of magnetism? Where did it take the story? STEPHEN PUMFREY: Well I mean the fact that you can use the word 'electromagnetism' shows that you know we have entered a new era, which we're still in, of electricity and magnetism as different parts of the same field of force. Faraday introduces the idea of a field of force which is new as well. And in a sense, I mean I'm not a great sort of believer in cyclical theories of history but I think it has come full circle. Magnetism started off in the ancient world, along with the electron amber as two very unusual, strange magical properties, which were the properties of a strange mineral called lodestone, or a strange substance called amber, and they're linked together in a kind of panoply of magical cures. And then with Gilbert, Gilbert tries very hard to separate them and they remain separated but yet after all at the end of the story they've come back to be two sides of the same coin, with the big difference that they're now no longer unique magical properties of strange minerals but they're the fundamental forces of the entire universe. MELVYN BRAGG: I mean is there in which magnetism is still mysterious, is still not fully understood? STEPHEN PUMFREY: Yes, every since. Well almost every since. LISA JARDINE: People still want to... Science still has not cracked magnetism, and people still want magnetism somehow to have a soul. MELVYN BRAGG: What do you mean ..................? JOHN HALBREN: Well I, there are many ways in which one can look at this question. For example after the discovery of Oested, the French busy themselves getting rid of magnetism altogether, the ideal is to be replaced by electricity in motion. Faraday, having shown the complete interconvertability of the two, then busied himself getting rid of both electricity and magnetism and putting the stresses and strains of the forces involved in some sort of medium between the bodies that were interacting. MELVYN BRAGG: Stephen? STEPHEN PUMFREY: Well I mean not obviously a kind of modern science. My understanding is that the holy grail for modern scientists and scientists is to find the single magnetic pole, the magnetic mono pole - this would be the kind of fundamental unit of magnetism that would give them the explanation. And they just haven't got it yet. MELVYN BRAGG: It's like a lot of areas in this isn't it - we're finishing now - that finding the single thing is the final problem. I wonder whether it's the beginning of the next lot of problems. JOHN HALBRON: It may not exists. MELVYN BRAGG: And that came in very well. Well I enjoyed that a lot. Lisa Jardine, John Halbron and Stephen Pumfrey, thank you very much. Next week we'll be talking about two young kings, great princes in the tine of Renaissance Europe - Henry VIII and Francis I, and how they met in imitation of war on the field of the Cloth of Gold. Thank you for listening. Back to the In Our Time homepage The BBC is not responsible for external websites |
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