Pod Insights Daniel and Kelly's Extraordinary Universe The Mysteries of Magnetism About this episode Daniel and Kelly dig into the mysteries of magnetism, explaining how magnets work and what they reveal about the Universe.
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Transcript 10,394 words · 23 speakers
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0:47 Speaker 02 Hey, I'm Niall Rogers. This fall, I'll be driving across the country, meeting some of today's coolest and most fascinating artists. We'll explore the stories before the moments that changed everything. Because every musician remembers the moment where it all began. Experience Before the Moment, a Lincoln Original Series on the iHeart Radio app, YouTube, or wherever you get your podcasts.
1:26 Daniel Whiteson? I love that science has made so much progress in explaining the universe, unraveling its inner workings. It's almost incredible what we've accomplished. There's almost nothing left in our everyday lives that remains a true, deep mystery. Sure, the early universe and the black holes and lots of extreme situations still defy explanation, and we dig into those on the podcast all the time. But your everyday experience is mostly explained and understood. The motion of the stars, the sun, the planets, those are understood. We know what an earthquake is and how weather works, even if we can't predict them very well. Makes me wonder what it was like to be a human when there were unexplained mysteries right up in your face every
2:11 Daniel Whiteson? day, when science hadn't fully conquered magic. Today, we're going to try to get the flavor of that by talking about the remaining mysteries of one of the most magical forces in physics: magnetism. Welcome to Daniel and Kelly's extraordinarily magnetic universe.
2:42 Kelly Weinersmith? Hello, I'm Kelly Wiener-Smith. I study parasites and space and magnets, man. How do they work? What a miracle magnets are.
2:50 Daniel Whiteson? Hi, I'm Daniel. I'm a particle physicist, and my job is to unravel how the world works. And yet, I sort of sometimes wish there really was magic.
2:59 Kelly Weinersmith? Yeah, yeah, no, me too. That would be pretty cool. Like, it's been really fun being a parent and seeing the like, sort of magical world that resides in my daughter's head and kind of wishing some of it could be real. But you know what? What exists in the real world is the Insane Clown Posse.
3:16 Daniel Whiteson? And are you saying they're magicians?
3:18 Kelly Weinersmith? Uh, no, I think they're into magic. So they, the Insane ICP is from Detroit, and I grew up in Toledo. And so the Insane Clown Posse often had shows in Toledo, and I got sort of exposed to some of their music and exposed as maybe exposed. Yeah, I feel uncomfortable when I hear the word exposed. And that's how I felt when I listened to ICP. But they had this one song, and anytime I hear about magnets, I think about this one song they had called Miracles, where, and this is a kid's show, so I'm going to replace a word with stinking. They'd be like, stinking magnets, how do they work? And I was like, I think if you talk to someone, we could tell you, there's probably an answer. It doesn't have to be a miracle. But, uh, but they do go on to say they hate scientists.
4:03 Kelly Weinersmith? So that's, uh, I think they're not interested in what we have to say.
4:06 Daniel Whiteson? Thumbs down for that. Well, you know, there's a lot of really interesting stuff there. Like, on one hand, some of the stuff we figured out is as fascinating and amazing as the kind of magic that exists in those novels, you know, like internet communication. I'm talking to you in real time from across the country, you know, like, that's basically magic.
4:28 Daniel Whiteson? But it's explained, it's understood. And there's something about magic, which is that it's not explained and not understood, which makes it sort of special. And the thing about magnets is that, yeah, we know how electromagnetism works and we can even understand it on the quantum level and QED is the most successful theory of all time, dot, dot, dot, dot, dot. And yet, when you play with magnets, they do feel a little magical. They do feel like a little bit beyond physics, don't they?
4:52 Kelly Weinersmith? They absolutely do. And I think if you were to talk about like maglev trains, which I suspect is a slightly different situation, but I can't say I know about it. And you were to explain that to someone from like 100 years ago, that and Zoom would absolutely feel like magic. You know, I like, I feel like the life we live in would feel like magic for people 100 years ago. I agree.
5:14 Daniel Whiteson? Yeah, yeah, like we went to the moon, man. We really did. The moon in the sky. That's right.
5:18 Kelly Weinersmith? Right, right.
5:19 Daniel Whiteson? Yeah. And so on today's show, we're gonna ruin magnets a little bit for all of y'all, right? Magnets are not magic and we're gonna explain the science of them. And I did something a little bit different with this episode. I wanted to really answer people's questions to resolve their magnetic mysteries. So before I even got started writing this episode, I went out and asked people, what are the deepest mysteries of magnets? What do people need explaining? How can we ruin the magic of magnets for all of our listeners?
5:48 Kelly Weinersmith? Our apologies to the juggalos for demystifying the magic of magnets.
5:53 Daniel Whiteson? So here's what our listeners had to say. If you would like to contribute your voice for future episodes, please don't be shy. We'd love to hear from you. Write to us to [email protected] . In the meantime, think about it for a moment. What do you think is the deepest mystery of magnets? Here's what listeners had to say. How migratory birds are able to detect magnetic fields.
6:16 Speaker 04 To me, the most mysterious thing about magnetism is that it's not constantly canceling itself out, that we can have magnets at all and that the atoms aren't just arranging themselves in such a way that the positive and negative are canceling out in any macro scale sort of way.
6:32 Speaker 05 Historically, I wonder if magnetism is one of the earliest to perceive intersections between magic and science.
6:37 Speaker 06 It's a mystery why magnet and steel was Walter Egan's only hit because that's a great song.
6:44 Speaker 07 I can get more magnets by breaking one into pieces.
6:48 Speaker 08 Total mystery. Spin creates it, but spin isn't really spinning, is it? And then moving charges make magnetic fields and magnetic fields make moving charges. It's basically the universe's most passive aggressive friendship. Also, magnetism is just electricity from a different perspective.
7:04 Speaker 09 How magnets can attract and repel without touching. There's no such thing as a monopole. There are always dipoles.
7:11 Speaker 10 Why is it binary? Why isn't there a third attraction? So it all works in a triangle.
7:18 Speaker 11 It's the repellent force between two magnets and the attractor force between a magnet and an object that's attracted to it. I think that force, both of those forces are very mysterious.
7:29 Speaker 12 I think it's the fact that the north and south poles switch and we don't know why or like what causes it.
7:35 Kelly Weinersmith? All right, Daniel, magnets. How do they work?
7:39 Daniel Whiteson? I don't know. It sounds like we should invite Walter Egan to sing us his song.
7:43 Kelly Weinersmith? I have to admit, I haven't heard of Walter Egan. Not that I'm like a great music connoisseur, but have you heard of Walter Egan?
7:51 Kelly Weinersmith? It's no fair if you Google it, Daniel.
7:57 Daniel Whiteson? So Walter Egan's great hit apparently came out in 1978 and I was only three. So I think I was a little too young to enjoy it at the time. So no, I'm not familiar with Walter Egan's only hit, but I'm gonna enjoy it after this recording.
8:10 Kelly Weinersmith? Yeah, me as well. We'll check it out. But then how, how do magnets work, Daniel?
8:15 Daniel Whiteson? Yeah, so magnets are amazing and fascinating, but they're best understood if we start with a related topic, which is electricity. Because electricity and magnetism very closely connected and we can use our intuition for electricity to understand how magnets are similar and also crucially different. So let's step away for a moment and start with electric charge. So we know that you can have positive and negative charges, right? Like the electron, what's its charge? It's negative one, right? The proton, what's its charge? It's positive one. There's no like balancing charge to the electron. You can have a proton and electron together and you can make a neutral object or even like a dipole. Where you have like more negative on one side, more positive on the other. But you can also crucially separate the electron and the positron.
9:00 Daniel Whiteson? You can just have in principle, an empty universe with an electron in it, or an empty universe with just a proton in it. So you can have positive charges, negative charges, and they can be isolated and separate. Right? We call these things monopoles. Mono because they're just one, right? So they're alone. They don't have to come in pairs. And crucially, they are the source of electric fields. Right? Like if you have an electron in space, it makes an electric field. So it could push and pull on other electrons. A proton can also make electric fields. And if you like to draw field lines, these lines start from the electron or the proton. Right? So that's the basics of electric fields and charges.
9:41 Kelly Weinersmith? So to clarify, for monopoles, when they're alone, do you have to have just one electron alone? Or you can have a bunch of electrons as long as they don't let any protons in?
9:51 Daniel Whiteson? Yeah, great question. You can have just one electron alone. You can also have like 10,000 electrons and they're a source of negative charge. So that's 10,000 monopoles, which makes an effective monopole. It's still only a negative charge. It's a net negative charge. It's a source of the electric field.
10:09 Kelly Weinersmith? Okay, so the word monopole refers to one electron alone or a bunch of electrons together? It's, it can be either singular or plural electrons?
10:19 Daniel Whiteson? Yeah.
10:19 Kelly Weinersmith? Okay.
10:20 Daniel Whiteson? Yeah, I see how that's confusing.
10:23 Daniel Whiteson? What we mean by mono is not the number of electrons, but the fact that there is no balancing pole. Because a dipole, in contrast, is a positive and a negative, where the net charge is zero. But a monopole has negative or positive net charge, even if it's one or 75 electrons.
10:38 Kelly Weinersmith? We gotta make sure that we're clear because we gotta bring the juggalos along with this conversation. Wait, can I just check the juggalos? What are ICPs?
10:47 Daniel Whiteson? You're going down that rabbit hole. Here we go.
10:50 Kelly Weinersmith? Not very far. They are juggalos. Okay, they are juggalos. Oh God, a picture popped up.
11:00 Kelly Weinersmith? Brought back to my youth. Okay.
11:01 Daniel Whiteson? All right. So that's electricity. What about magnetism? Well, as we've talked about on the show a few times, this concept of charge extends to other forces. We call it charge, but really the official name is electric charge because we have also magnetic charges and weak force charges and strong force charges. Okay. So magnetic charges, what do we call them? We don't call them plus or minus. We call them north or south. And that's a historical anomaly because we associate it with the earth's magnetic field, which happens to be aligned mostly with the north and south poles. And so we call it magnetic north or magnetic south. But physically and conceptually, abstractly, you should think of these in the same category as electric plus and minus, just for magnetism instead of for electricity.
11:46 Kelly Weinersmith? And so north is plus and south is minus?
11:49 Daniel Whiteson? No, no, not necessarily. It's just two labels like plus and minus are arbitrary, right? We could have called the electron plus and the proton minus. Ben Franklin went the other way. There's no necessary connection between north and south or plus or minus. You're just biased for the northern hemisphere, Kelly.
12:04 Kelly Weinersmith? Well, I like where I live. But I'm sure the southern hemisphere is lovely as well. It was when I visited. So are we going to get to why the earth has a magnetic field too?
12:15 Daniel Whiteson? Yes. And what we don't understand about it and how weird it is, we're definitely going to dig into that.
12:19 Kelly Weinersmith? Magic.
12:20 Daniel Whiteson? All right. So so far magnetism is very similar to electricity. Here's the crucial difference. There are no monopoles. You can never have just a magnetic north, the way you can have a negative electric charge or a positive electric charge by itself. As far as we know, there is nothing which if you put it in an empty universe, would just have a magnetic north or magnetic south. They only come in dipoles, pairs of north and south together.
12:45 Kelly Weinersmith? Why?
12:46 Daniel Whiteson? Yeah. Why is a great question. And we don't have a good answer to that. We think actually there should be, like physics actually wants there to be a monopole. It would be a nice balance. We like symmetry in the universe. We like symmetry in the laws of physics. And if you just looked at the equations, you're like, oh yeah, there should totally be monopoles, but we've never seen one. We've never found anything out there that's the magnetic equivalent of an electron, like an electron carries charge just on its own, just a negative charge, no balance. We've never found anything out there that carries magnetic south or magnetic north. The only way we've ever made magnets is by moving electric charges. There's this connection between electricity and magnetism.
13:28 Daniel Whiteson? Electricity can generate magnetism, magnetism can generate electricity. That's the only way we can make magnetism through charges, not through pure magnetic sources. There are no sources of magnetism that are pure.
13:41 Kelly Weinersmith? Okay, so when I have a magnet, it's because of stuff electrons and protons are doing in there.
13:47 Daniel Whiteson? Exactly. One of Maxwell's equations, one of the crucial equations for electromagnetism, tells us that charges in motion make magnetic fields. So you take a bunch of electrons, you run them down a wire, what happens? They make a magnetic field around them. So you can make magnetic fields from charges in motion, but you can't make them monopoles, you can only make dipole fields. A charge in motion can make a magnetic field, but it has to make a north and a south at the same time. You can't just generate a north, you can't just generate a south.
14:20 Kelly Weinersmith? And is that, is that the end here? The answer is we don't, we don't know why that's the case? I think that's what you were saying.
14:25 Daniel Whiteson? We understand why you can't generate a monopole from electric charges. We don't understand why there aren't monopoles out there that just make magnetic north or make magnetic south. We don't know, and there might be. It could be that they are somewhere in the universe, but if they are, they are very rare. We've never seen them. We've looked for them and we can dig into that in a minute. But every magnetic field we've ever made or seen or that you've used doesn't come from some inherent source of a magnetic monopole the way electric fields come from electrons or protons. It comes from electric charges in motion.
14:58 Kelly Weinersmith? So why do electric charges in motion result in a north and a south? Have I just asked the same question in a slightly different way? Okay.
15:06 Daniel Whiteson? No, no, no, that's a great question. And there's a very mathematical answer if you look at the structure of Maxwell's equations. But intuitively, the way to think about it is, think about the magnetic field that's generated when electron moves down a wire. It's gotta be in a loop. It's a curl equation, so it makes a magnetic field in a loop around the wire. There's no source there. The magnetic field line starts and ends on itself. It doesn't start or end in a specific location. So there's no endpoints there. Monopoles have endpoints for magnetic fields, but an electron in motion can't make that. It can just make a loop that ends and starts on itself. And that has a north and a south all together. And so it can't generate these sources. So let's talk about the two kinds of magnets that we have experience with.
15:51 Daniel Whiteson? The kitchen magnet, like a permanent magnet, like a ferromagnet. And then we'll talk about electromagnets. So a ferromagnet, you might ask like, I have this thing on my fridge. I'm not running electricity through it. What charges are in motion? And this is exactly the question I just got yesterday as I was prepping this episode. So here's David Naylor asking us this question.
16:12 Speaker 13 Hi, Daniel and Kelly. I'm told that magnetic fields are generated by moving electron charges. So my question for you is what moving electron charge is powering two magnets that I hold in my hand? Thank you both for an awesome show and I can't wait to hear your answer.
16:30 Kelly Weinersmith? Well, David, since we've both asked exactly the same question, I've got to say that this is a truly great and insightful question. What is the answer, Daniel?
16:39 Daniel Whiteson? Are you inviting David to join your insane magnet posse?
16:44 Kelly Weinersmith? Yes, the magalos.
16:49 Daniel Whiteson? Right, so what's moving here to generate this magnet? So zoom in on the magnet. You have molecules of iron. Inside those molecules, you have the nucleus and you also have electrons whizzing around, right? Well, all of these fundamental particles have something we call spin. It's quantum spin. They're not physically spinning, but they have this property, which is very closely related to spin. And one of the reasons we say that this property is related to spin is that it has a lot of the same behavior as classical spin. Like if you take a metallic sphere that's charged and you spun it, it would generate a magnetic field. Why? Because you've got charges in motion. You have charges attached to the surface of the sphere and they're in motion generates a magnetic field. Cool.
17:34 Daniel Whiteson? If you have a fundamental particle like an electron that's charged and you give it quantum spin, it also has a little magnetic field. It has a little north and a little south. Why is that exactly? It's a little bit circular. Like we call it spin because we see that it generates magnetic field. And so we're like, well, whatever this quantum spin thing is, it has angular momentum and it generates magnetic field. So it's a lot like spin, so we'll call it spin. So you can either say, well, something is happening with the electron to generate these mini magnetic fields and it's related to spin, or you can say, we call it spin because it generates magnetic fields. It's sort of two sides of the same coin. But basically, each little electron is its own mini magnet.
18:15 Kelly Weinersmith? Okay, so I'm just trying to make sure I've got my head around this. So you were saying that electrons are like all negative, totally negative, but they can still have a north and a south because north and south is not the same thing as positive and minus, despite the fact that I have locked that into my brain. So what does it really mean then to say that an electron has a north and a south pole?
18:36 Daniel Whiteson? So electrons can spin in two different ways. They can spin up or spin down. If it spins up, then it has a north and a south pole. If it spins down, then it has a south and a north pole, if you like to think about it that way. So the direction of its spin determines which side of it the electron is north and which side is south. And then if you pass them through a magnetic field, spin up electrons will go one way and spin down electrons will go the other way. This is actually the crucial experiment that revealed that electrons could only have two spins, up or down, as they passed them through a magnet. And they didn't see a whole distribution of electron deflections. They saw two deflections, either left or right. They were tightly clustered. So you can use the magnetic field of the electron to measure its spin because it's that closely connected. So to answer David's question directly,
19:19 Daniel Whiteson? like, we don't want to say that electron is in motion because it's a quantum particle and it doesn't have a surface and it's not really spinning, but the quantum spin of the electron is analogous to electric current and together with the electron's charge, that generates a little tiny dipole magnet.
19:36 Kelly Weinersmith? Okay, so I'm thinking about my kitchen magnet, and I've got some electrons spinning up, some electrons spinning down. Is the top of my magnet?
19:43 Daniel Whiteson? Yeah.
19:44 Kelly Weinersmith? Or the bottom, whatever. Is one side of the magnet where my electrons that are spinning up live, and the bottom side is where my electrons that spin down live? And why don't they mix together?
19:56 Daniel Whiteson? Does that seem like a cozy little neighborhood organization?
19:59 Kelly Weinersmith? Well, no, it sounds like they're segregating. I don't like that one bit.
20:01 Daniel Whiteson? You're right. Exactly. Let's mix, everybody. Well, if you just take a hunk of iron out of the earth, then it's got all these little electrons and they have all their little magnetic fields, but they're all pointing in random directions. And so it doesn't act like a magnet. And actually, if you zoom in, you find that they have organized themselves into little magnetic domains, little clusters where they all point the same direction. And then there's another cluster pointing the opposite direction. But on a macroscopic scale, they all add up to nothing. They cancel each other out. What happens if you bring another magnet nearby is it'll start to flip those guys, right? Those magnets will align with the other magnets. So that's why if you bring like a hunk of iron near a magnet, it gets magnetized. What you're doing is just rearranging all of those electrons. So they're no longer fighting each other.
20:45 Daniel Whiteson? They're now all aligned in the same direction and they add up. Instead of canceling out, they add up to an overall magnetic field.
20:52 Kelly Weinersmith? Okay, so you're not just moving them around so they're in like groups. You're actually flipping them all to the same direction.
20:56 Daniel Whiteson? Yeah.
20:57 Kelly Weinersmith? Okay.
20:57 Daniel Whiteson? And we're talking about electrons here because they're easiest to think about. But it's not just the electrons to have these magnetic fields. Protons have magnetic fields also. The neutron even has its own residual magnetic field because it has quarks inside of it, which are charged. And so you can measure the magnetic moment of the neutron or of the proton or the electron. And so I'm saying electrons, but really I mean like all the particles inside that add up to do this. And so you can make pretty powerful magnets with the right materials that have like the right structure and everything can align nicely. The strongest magnet we've ever measured is about one and a half Tesla, which uses neodymium, iron and boron magnets. And that's pretty powerful.
21:40 Daniel Whiteson? Remember, the earth's magnetic field is almost a million times weaker than that. It's like 30 to 50 micro Tesla. So we can make very powerful magnets that like are much more powerful than the earth's magnetic field.
21:51 Kelly Weinersmith? So I'm thinking of the brave little toaster and the giant magnet that was picking stuff up to throw it away in the landfill. So like 1.4 Tesla, how many, how many cars could you pick up with that? What are we talking about?
22:05 Kelly Weinersmith? The Brave Little Toaster is a classic.
22:07 Daniel Whiteson? I don't know The Brave Little Toaster.
22:09 Kelly Weinersmith? What?
22:10 Daniel Whiteson? I've got a lot of cultural homework to do after this episode.
22:12 Kelly Weinersmith? You were born in the wrong decade, man.
22:14 Daniel Whiteson? Yeah, exactly. Well, you could pick up a lot of cars, but actually, those big guys that pick up cars tend to be electromagnets.
22:21 Kelly Weinersmith? Oh.
22:21 Daniel Whiteson? Because those are magnets you can easily turn off and on.
22:24 Kelly Weinersmith? Hmm.
22:25 Daniel Whiteson? Like, you could demagnify something by trying to re-flip it and rerandomize all the magnetic domains, but that's a lot of work. Instead, the other kind of magnet is very easy to turn off or on or reverse.
22:37 Kelly Weinersmith? All right, magnet I've got on my fridge. It has electrons spinning up on one side, electrons spinning down on another side. Over time, would I expect those to, like, decay? Where some of the ones that are going up start going down? Or they just keep spinning in the direction they're spinning in unless you do something to force them otherwise?
22:57 Daniel Whiteson? Yeah, this is a great question. People often ask this because they imagine, like, why do magnets not lose their energy?
23:03 Kelly Weinersmith? Yeah.
23:03 Daniel Whiteson? But yeah, they just point in the same direction unless something comes along and flips them. And so to demagnetize a magnet, you'd have to, like, flip some of the electrons or some of the particles one way and not the other ones, which would be pretty tricky. And they can just sit there and keep spinning in the same direction without requiring any energy. You know, the same way that, like, a rock can sit on the top of a hill until somebody comes along and pushes it. It takes energy to move the rock. So we can get more into that in a minute. But yeah, they will keep spinning in the same direction unless you come along and scramble them.
23:36 Kelly Weinersmith? All right, well, let's take a break and get more into that.
23:48 Speaker 02 Hey, it's Niall Rogers, host of Before the Moment, a Lincoln original series. I'm driving across the country, meeting some of today's most fascinating artists. We're exploring the stories before the moment that changed everything.
24:04 Speaker 02 This week, I'm joined by my friend, John Legend. So you're helping Will.i.am write hooks. What made "Ordinary People" become the one song from those sound checks you knew you had to make your own?
24:16 Speaker 14 I was just writing for the Black Eyed Peas. I wasn't expecting to write something for myself in that session, but I wrote the hook for "Ordinary People," and I recorded a demo, and I'm like, I would rather keep "Ordinary People" for myself. This station in Chicago, WGCI, they start playing it before we're promoting it. The song spoke for itself. It became the defining song for my first album. I knew it was special, but you never know how special it's going to be and how much impact it's going to have in people's lives. And you never believe that you're going to actually change people's lives with a song.
24:45 Speaker 02 Experience Before the Moment, a Lincoln original series on the iHeart Radio app, YouTube, or wherever you get your podcasts.
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26:34 Kelly Weinersmith? All right, so my brain is stuck on the brave little toaster now and that electromagnet that was picking cars up and flinging them around and throwing them down. How do electromagnets work?
26:42 Daniel Whiteson? So electromagnets are like macroscopic versions, right? A minute ago, we were talking about microscopic electrons. We say they have charge and spin, and therefore they generate a magnetic field. Here, we just take a bunch of electrons. We say, whiz them around in a circle. That's charges in motion, and so that generates a magnetic field. And you know, that just says current. So if you want a straight-up magnetic field, for example, you make a loop of wire. You like wrap wire around a cylinder. And then as the electrons go through that wire, they generate a magnetic field in a loop around the wire. And then inside that cylinder, they all add up in the same direction to make a big magnetic field. So this is what electromagnet is. It requires running a current.
27:27 Daniel Whiteson? You have to run energy through it. So you run out of energy, boom, your magnet turns off. This is, for example, how an electric motor works. Has an oscillating electromagnet. You turn the magnet on in one direction, so it pulls on something. Then you turn it on the other direction, so it pushes. And oscillates very rapidly to spin that rotor. Every electric motor uses electromagnets.
27:49 Kelly Weinersmith? What kind of things in our lives use electric motors?
27:52 Daniel Whiteson? EVs.
27:53 Kelly Weinersmith? Oh. What about my hybrid? Does my hybrid use an electric motor?
27:57 Daniel Whiteson? Your hybrid definitely has an electric motor. And like every robot you've ever seen, and anything that goes like, brrrr, vrrrr, all that stuff, you know, uses little electric motors. Electric motors are everywhere, and they're wonderful. And you can combine these two things. You can take an electric motor, and instead of just having like a plastic cylinder or whatever, you can use a ferromagnetic cylinder. So now your electromagnetic motor is aligning the spinning electrons of the ferromagnet, so it all adds up and you get like a really powerful magnet. So people have been doing experiments to try to like, make the most powerful electromagnet possible to see like, how much magnetism can we have in a little bit of space?
28:38 Kelly Weinersmith? So why would having a permanent magnet and then running electricity through that make it more intense? Like, you know, you've already got the electrons doing their thing, and running current, why does that supercharge the magnetism? Magnet, or magic?
28:54 Daniel Whiteson? There's no magic here. It's just that if you have the electromagnet, it generates a magnetic field through its core. That's one magnet. If you add a chunk of iron, then your electromagnet will align, will magnetize your iron for you. So now you have a permanent magnet adding to your electromagnet. So it just adds up. So you use the electromagnet to magnetize your chunk of iron to give you a permanent magnet. And now your permanent magnet just sits there adding to your electromagnet, if that's what you want, right? If you want an oscillating magnetic field, then that's not what you want, because you can't turn off the permanent magnet or oscillate it very quickly. But if your goal is to like, be a magnet nerd and make the most powerful magnet ever made on earth, then that's what you want. And that's what people are doing.
29:37 Kelly Weinersmith? And why would you want to make the most powerful magnet ever made on earth? Is there like a thing you can do once you have that? Or is it just awesome?
29:45 Daniel Whiteson? You get to be the magnet king or queen. I mean, come on, Kelly.
29:48 Kelly Weinersmith? Queen of the Megalos!
29:51 Daniel Whiteson? I just think it's cool, you know? Probably there will be some application someday, and I hope it's not weapons. But you know, a lot of us who got into physics just do things because like, let's see if we can and what happens. And maybe our theory breaks down. And you know, these things are fascinating.
30:07 Kelly Weinersmith? Yeah, I'm fascinated. So what is the biggest magnet? Who is the current monarch of the Megalos?
30:14 Daniel Whiteson? Yeah, so one of the first guys to get into this was an American physicist named Francis Bitter.
30:20 Kelly Weinersmith? Does he wear a lot of makeup?
30:21 Daniel Whiteson? If you look into...
30:26 Daniel Whiteson? No, and he's not a very bitter guy, though the magnets that he inspired and he designed are called the bitter magnets. But you know, they don't taste bitter. Nobody's grumpy about them. They're just named after Francis Bitter.
30:37 Kelly Weinersmith? Okay.
30:38 Daniel Whiteson? So he and his design of magnets set a record of 41.4 Tesla, which is a huge amount of magnetism, right? Remember, the strongest permanent magnet ever was like one and a half Tesla. So already blowing out of the water, all permanent magnets.
30:54 Kelly Weinersmith? Wow.
30:54 Daniel Whiteson? The limit there is that there's so much energy in this magnet that basically it'll overheat. There's not a physical limit, like it's not that you can't have more magnetism or density or something we think, it's just that it melts the whole apparatus because there's so much energy in it. And that's because, you know, you can't have current without loss and the resistance of your wire is going to heat up everything and you're just going to melt your whole apparatus. So people said, well, let's try to use superconductors, right? Superconductors are famous for having low resistance. So higher currents, so bigger magnet, yay. And that's very cool. And we use superconducting magnets in, for example, the Large Hadron Collider. Say you wanted really powerful magnets because you wanted
31:37 Daniel Whiteson? to bend the path of super high energy particles so you could collide them together and reveal the secrets of the universe. See, there you go. There's an application for very powerful magnets.
31:46 Kelly Weinersmith? Yay. That's why didn't you come up with that sooner, Daniel? This is, this is what you do, man.
31:52 Daniel Whiteson? I wanted to lead into it a little bit more.
31:54 Kelly Weinersmith? Oh, suspense. You're good at this.
31:55 Daniel Whiteson? Yes, yes. And that sounds awesome. But the problem is that superconductivity is not something we understand super well. And at some point, having a lot of magnetic field interferes with the superconductivity. The superconductivity comes from like electrons behaving weird. They pair up with each other and flow differently, et cetera, et cetera. It's not something we super understand, but we do know that magnetism interferes with it. And so there's a limit there. And they've only gotten to like 32 Tesla at the National Magnetic Field Lab in the US.
32:26 Kelly Weinersmith? So that's what 10 Tesla less than what Bitter was doing? Is that right?
32:30 Daniel Whiteson? Yeah, exactly.
32:31 Kelly Weinersmith? Okay.
32:31 Daniel Whiteson? Yeah. So then somebody said, well, let's combine all the best ideas out there, right?
32:35 Kelly Weinersmith? Oh.
32:36 Daniel Whiteson? Yeah, let's have a bitter magnet with superconductors. And they were able to get up to 45 Tesla. This is the Florida State Magnet Lab. And so that's the current record for a magnet that lasts more than a few microseconds on magnets like stable and you could use it to do something, for example. But there are other folks out there, they're like, so what if your magnet melts? Or so what if the whole apparatus blows up? You still got a powerful magnet. So there are folks working on something called explosive magnets that says like, let's just try to get the most powerful magnetic field ever. We don't care if the whole building collapses. Afterwards, we still get the record.
33:13 Kelly Weinersmith? I mean, I can get behind that attitude, but can I take one quick step back? So I thought that the, okay, so when we talked about using a superconducting wire, I thought you were taking the bitter magnet plan, but using a superconducting wire instead. So what does it mean to say you're doing a hybrid of the bitter and the superconducting idea?
33:34 Daniel Whiteson? The answer is a little bit technical. The way a bitter magnet works is requires these circular plates with insulating spacers in them, and it's not very conducive to the superconducting setup. So people started from a different approach using superconductors. And then later they're like, made some efforts to try to bring these two designs together. So sort of a compromised design, but it has to do with the detailed geometry of bitter magnets.
33:58 Kelly Weinersmith? Awesome. Okay, thanks. Now let's blow some stuff up.
34:00 Daniel Whiteson? Yeah. So not only are these folks willing to let their magnet get blown up, but they're going to literally use explosives to generate the high magnetic field. They use explosives to compress the whole apparatus so you get a higher density magnet as the explosion is happening. And the record here is 2,800 Tesla.
34:19 Kelly Weinersmith? Wow.
34:20 Daniel Whiteson? So we're almost 100 times what the bitter superconductor magnet at the FSU magnet lab can do, but only for a few microseconds, still pretty awesome.
34:29 Kelly Weinersmith? Yeah, I can't imagine you're going to get a government to fund an LHC that runs on explosive magnets, you know?
34:35 Daniel Whiteson? Oh, that would be cool, though.
34:37 Kelly Weinersmith? Yeah. Every decade you get one really big batch of data and then you got to start over again.
34:41 Daniel Whiteson? But before you feel too proud of humanity's achievements, let's put it in like astronomical context, right? 2,800 Tesla is a lot bigger than the Earth's magnetic field, which is like 30 to 60 micro Tesla, but a neutron star is already at a million Tesla.
34:57 Kelly Weinersmith? Oh, wow.
34:58 Daniel Whiteson? So we're talking 1,000 times our explosive magnets. And a magnetar, a super magnetized version of a neutron star that's a pulsar and spinning and crazy, has tend to be 11 Tesla. So like blowing us out of the water by a factor of 10 to the eight. So yeah, nature can do what humanity can't still.
35:18 Kelly Weinersmith? All right. Well, so I've decided instead of the magalos, we're going to be the magnetars because that sounds way cooler. I'm sorry to the juggalos out there, but the magnetars are going to take over the world.
35:31 Daniel Whiteson? All right. And so that's the basics of how magnets work. We got permanent magnets. We look at electromagnets. We got magnetism generated by charges in motion. One of the other questions that the listeners asked was, why are there no monopoles? Why do we only generate magnetic fields from dipoles? And we talked about this a little bit, but I want to dig a little bit deeper into it because I want to explain why physics wants monopoles to exist.
35:58 Kelly Weinersmith? All right, let's see how many different ways there are to say, we don't know.
36:07 Daniel Whiteson? I mean, if you just looked at the equations, if you write down Maxwell's equations, you see they describe how electric fields are generated from sources, you know, positive and negative charges, how magnetic fields are generated from those sources in motion, how you can even get current from magnets, all sorts of back and forth. It's beautiful, the symmetry is gorgeous, but there's this one flaw in it. There's one glaring omission, this lack of symmetry, which is that there are no sources of magnetic fields. And so in the equations, we just say zero, right? The total sources of magnetic fields are zero. It would be so much nicer if we could replace that zero with something that paralleled what happens in electricity where you have monopoles, you have sources of fields.
36:51 Daniel Whiteson? And so that awkwardness makes physicists want to be like, well, what if there are monopoles out there, we just haven't found them yet? Because that would make the equations more beautiful. And let me remind you that beauty and symmetry in physics has led us to real discoveries before. Like even in this particular aspect, when Maxwell was putting his equations together, he noticed there was a term that was asymmetric. He was like, hmm, it would be more beautiful if this other term existed. And then he went out there and actually found the effect. He's like, oh, this is a real thing in the universe, just nobody had isolated it and looked for it before. So symmetry does lead to discoveries, like mathematical insight really does reveal physical nature of the universe, which is like, cool and philosophical and tells you like, wow, maybe the universe really is mathematical.
37:36 Daniel Whiteson? And so it inspires us. It says, hmm, wouldn't it be cool if there was a full symmetry? If these equations really were exactly the same for electricity and magnetism? Because remember, electricity and magnetism are not separate things. They're two sides of the same coin. It's not even always possible to draw a dotted line and say, this is magnetism and this is electricity. Like, let's say, for example, I'm holding an electron. I see an electric field, right? I don't see any magnetic field because I'm just holding it. It's not moving. But what if Kelly drives by, you know, at 50 miles an hour? She looks at my electron. She's like, no, that electron is moving. Because according to you, it's moving at 50 miles an hour. So do you see a magnetic field? Answer is yes. So you see a magnetic field and I don't.
38:21 Daniel Whiteson? Because really, it's just electromagnetism, right? This dotted line we draw between them is an artifact of humans being like, oh, electricity is lightning. Magnets are weird rocks. These are separate things. And later, we realized they're actually just two sides of the same coin. So it would be beautiful if we could fully unify these things, if we saw monopoles.
38:43 Kelly Weinersmith? Every time I talk about beauty and symmetry and physics, I find myself really wanting a framework for when we should be able to say, oh, it would be beautiful if there were this other thing to complete the symmetry. And then whenever we don't see a symmetry, is that because we're missing something? Or is it just like, well, they're just, it just isn't symmetrical? Like, when should you see symmetry and when should you not?
39:05 Daniel Whiteson? We don't know, and it sounds arbitrary and biased. And the only real explanation, if you want to be honest, is so far, this works. Like, looking for symmetry and trusting our gut about like, what is beautiful and elegant, has led us to discoveries. That doesn't mean it always will. The universe could be a mess, you know, it could be ugly, deep down. And this is something you and I have talked about, like, why do we find vistas beautiful? Why are flowers pretty? They're not designed for us. This whole sense of aesthetics, it feels weird and subjective and not scientific. And yeah, that's true, but there's a lot of subjectivity in thinking about what to explore. In the end, the data's got to tell you what's real. But when you're like hunting for ideas, trusting your gut and looking for beauty is useful.
39:51 Daniel Whiteson? And there's another reason why we think magnetic monopoles might exist, which is if they did, it would instantly solve another deep question about the universe, which is, why is electric charge quantized? Like, why do we have electrons that have plus one charge? But there's no particles with like 1.0042 charge or 75.9 charges. They come in these increments. And quarks have one third and two third charge, but they're still quantized. Nobody knows the answer to this, but if there was a magnetic monopole, even just one that existed in the universe, it would answer this question.
40:27 Kelly Weinersmith? Whoa. All right. This is Schrodinger's equation, right? So would that mean that if, if we found one, would that mean his equations were wrong? Or would that complete his equations?
40:37 Daniel Whiteson? This has to do actually with quantization of angular momentum.
40:40 Kelly Weinersmith? Oh.
40:41 Daniel Whiteson? Right? We know that angular momentum is quantized. And we know this whole relationship between electricity and magnetism. And so it's very easy to derive this quantization from the existence of monopoles. It's a few steps in the equations. And so famous physicists like Joe Polchinski says, quote, "Magnetic monopoles are one of the safest bets that one can make about physics not yet seen." Like, if you had to guess about future discoveries, a lot of physicists are confident that eventually we will see a magnetic monopole.
41:10 Kelly Weinersmith? Oh, wow.
41:11 Daniel Whiteson? And it's not like we haven't looked. We've been looking for them. It's actually quite easy to see a magnetic monopole.
41:17 Kelly Weinersmith? All right. I'm dying to know how we've been looking for them. So let's take a break, ruminate on beauty and what it means for our universe. And when we come back, we'll find out how you find monopoles.
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41:57 Speaker 19 To this day, Ordinary would not have done anything, and I would have not been able to put it out if Book Talk didn't back it up and if my wife and her friend didn't back it up.
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42:09 Speaker 19 I mean, you, I bet you, we could point to nine different things in our careers where it's just one thing all of a sudden. If that one thing didn't happen, then I wouldn't be here.
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42:18 Speaker 02 is what I've been talking about since the beginning of my career. There's these things outside of you
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42:31 Speaker 19 Yeah.
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44:25 Kelly Weinersmith? All right. You were about to tell us how we go about looking for monopoles. So what have we done so far?
44:30 Daniel Whiteson? There's two categories of ways to discover monopoles. One is try to find them already existing in the universe. And the other is try to make some. So how do you find a monopole? Well, let's think about early experiments with magnets, right? Faraday did these experiments where he had a coil of wire and he passed a magnet through it. And he saw that it generated a current, right? And the crucial thing is all the magnets he had had a north and a south. So he would pass the north part through the wire and it would generate a current one way. And the south part would then follow and it would generate a current the other way. So if you have a dipole that goes through a loop of wire, you get current one way and then current the other way, it all adds up to zero because the dipole has no net magnetic charge. But if you have a monopole that passes through, it just generates current in one direction. That's it. So what do you do?
45:16 Daniel Whiteson? You build a huge loop of current to capture any monopole that happened to fly through and you wait and you just see, maybe we'll find one. And some guy built a really big wire and he ran it for a while. And there was this event on Valentine's Day, 1982, where he saw a huge spike of current only in one direction. Boom, it looks exactly like a monopole, but it's never been replicated. Nobody's ever seen another one. So either monopoles are super duper rare in the universe and he happened to capture one. Nobody has been able to do it since, which means they must be super rare. Or it was a glitch or some weird error and not a real signal. Nobody knows to this day, like, did he really see a monopole?
46:01 Daniel Whiteson? You can't really conclude yes, based on just one observation.
46:04 Kelly Weinersmith? So is like essentially this experiment running continuously, looking for? So we're, it's still running, still looking and it's only been seen once in? Forty years?
46:15 Daniel Whiteson? Yeah, exactly.
46:16 Kelly Weinersmith? Okay, wow.
46:16 Daniel Whiteson? And so if he's right, it means that monopoles are like very rare. Like there's less than one monopole per 10 to the 30 atoms, which, you know, that's not, not actually that rare because there's a lot of 10 to the 30 atoms in the earth, for example. But, you know, if monopoles are out there, they're super duper rare. So the other thing we try to do is let's make them. One thing we can do with colliders is create new kinds of matter that we don't have ways to build otherwise. You know, we smash protons together. It turns into some intermediate state and then through alchemy, basically, we can create new kinds of matter. We create electrons or muons or quarks or whatever. And so people have tried to make magnetic monopoles at the collider. It's nothing you do in particular.
46:58 Daniel Whiteson? You just look to see, hey, if we smash protons together often enough, do any of these guys come out? And so far, we haven't seen any. They would act weird in the magnetic fields that our detectors are immersed in. And so there would be a very obvious signal, but we've never seen one so far.
47:14 Kelly Weinersmith? How long have we been using this method to look for monopoles?
47:16 Daniel Whiteson? Basically, every time we run a collider, we look through the data for monopoles. And we've been doing collisions for 50 years or so, basically, at this level. We've looked for them at the Large Hadron Collider. We looked for them at the Tevatron. We looked for them at the Large Electron Proton Collider. We've never seen anything that looks like a monopole. So that's disappointing and it's confusing because, boy, it sure would be beautiful if monopoles existed and it would be an amazing discovery, but we've never seen one. And so maybe the universe just is asymmetric in this way.
47:45 Kelly Weinersmith? So say you do see a monopole, but it really is so rare that you see it, you know, one time every 45 years. Is, is that still as amazing if it's just this rare blip that sometimes happens in the universe?
47:58 Daniel Whiteson? It's still as amazing because their very existence would be satisfactory. It would open up new questions like, well, why are electric monopoles everywhere and magnetic monopoles super duper rare? That would need an answer. The same way that like matter is everywhere and antimatter is super duper rare. That would be another asymmetry we'd have to explain. But if they did exist, it would be a very different universe than one in which they were prohibited and which they just cannot exist for some reason we don't yet know.
48:25 Kelly Weinersmith? Well, my favorite dipole is earth.
48:30 Kelly Weinersmith? I'm a big fan.
48:30 Daniel Whiteson? Biased.
48:31 Kelly Weinersmith? Yeah, well, so I am. That's fine. You can check out my whole book for why I think the Earth is so great. So why, why is Earth such, what makes Earth such a great dipole, Daniel?
48:43 Daniel Whiteson? Is that why you don't want to go to Mars? Because there's no magnetic field there? And you're just pro Earth's magnetic field? Yeah.
48:48 Kelly Weinersmith? I mean, I don't think the magnetars and I would feel really comfortable on Mars. You know, we need a strong dipole.
48:55 Daniel Whiteson? Well, the Earth has a big magnetic field. We all know that because we use compasses to navigate for thousands of years. It's not a permanent magnet, right? It's not just like there's a hunk of iron down there that has a magnet to it because it's changing, right? The Earth's magnetic field is not constant. We don't fully understand where the Earth's magnetic field comes from. Roughly, we know that the Earth has a fluid layer. There's rock down there that's under a lot of pressure and there's convection. So this stuff is bubbling and rising and then sinking. So you get these like loops of stuff moving and the Earth is spinning. And so roughly, probably the explanation is that molten liquid currents of this stuff that, and it's charged, these are metals, a lot of them, give a magnetic
49:36 Daniel Whiteson? field. And once you have a magnetic field, that magnetic field can drive currents and those currents can make more field and those fields make more currents. You get this dynamo effect that enhances itself. But what we know is that this is not something that's just fixed. It's not like the Earth has had the same magnetic fields for four billion years. It changes and it changes in weird ways.
49:57 Kelly Weinersmith? And is it changing because convection can be sort of like random and it's not always happening exactly the same way?
50:04 Daniel Whiteson? We don't know. Like, we see these reversals through history and the reversals are not periodic. Like, sometimes it's every 50 million years. Sometimes it's every 100,000 years. The most recent reversal that we've seen is about 800,000 years ago. The poles were the opposite. So like, if you took a compass from today and went back in time a million years, the compass would point north towards the South Pole.
50:30 Kelly Weinersmith? What, would we be totally screwed if that happened? Like, and how fast does it happen? Is it like, you know, Monday morning, it's one way and Monday afternoon, it's the other?
50:38 Daniel Whiteson? No, it doesn't happen that fast, but it might be happening right now. Like, right now, the Earth's North Pole is drifting. It's moving away from the location around which the Earth is spinning, the sort of geometric North Pole, and towards Siberia at 40 kilometers per year.
50:54 Kelly Weinersmith? Oh.
50:54 Daniel Whiteson? And every year, that gets faster.
50:56 Kelly Weinersmith? Oh.
50:56 Daniel Whiteson? Yeah.
50:57 Kelly Weinersmith? So, wow. Are we sure it's gonna go all the way? Or could this just be like a?
51:01 Daniel Whiteson? We don't know.
51:02 Kelly Weinersmith? Jiggling.
51:03 Daniel Whiteson? It could just be a juggalo, you know?
51:04 Kelly Weinersmith? That's right.
51:05 Daniel Whiteson? For all we know. But the cool thing is that we can measure the Earth's magnetic field through history. This is one of those amazing moments when people have come up with this incredible detective strategy to unearth some data from history. We can use magnetized lava that's frozen on the seafloor.
51:22 Kelly Weinersmith? What?
51:23 Daniel Whiteson? So there's these parts of the sea where like you're making a lot of new rock all the time. So you're making new crust at these like mid-ocean ridges that come out and then spreads outwards. And these are susceptible to magnetism. And so they get magnetized by the Earth's magnetic field. All the little particles align in one direction. And then they freeze, right? And so you get these stripes. As the Earth's magnetic field flips, this paleomagnetic record is formed. It's like a tape recorder of the Earth's magnetic field. You can go down and measure the magnetic field of this lava. And you're like, oh, it flipped. Oh, it's back. And if you know when it was made, you can reconstruct the whole history of the Earth's magnetic field. Isn't that amazing? Aren't scientists so clever?
52:03 Kelly Weinersmith? That is so cool. And you know, the folks in the geology section on our Discord are rejoicing because we've we've done something in their wheelhouse now. So yeah, that is incredible.
52:13 Daniel Whiteson? Yeah, so we know that it's happening. We know that it's irregular. We don't know why. And in contrast, for example, the Sun has a magnetic field that flips every 11 years super regularly, like every 11 years for like a long, long time. Why does the Earth have a magnetic field that flips irregularly? We don't know. Why does the Sun reverse this field every 11 years? We don't know. We think the Sun's magnetic field comes from convection of plasma inside it. We don't fully understand it. Huge question. You know, Mars, we think, has no magnetic field because it's essentially frozen. There might be some motion inside Mars, but there's no dynamo inside Mars. Venus has no field. Jupiter has a huge field. Some moons have magnetic fields. We think they have internal motion.
52:58 Daniel Whiteson? So there's some understanding of it, but a lot of big questions left about planetary and lunar magnetic fields.
53:04 Kelly Weinersmith? So a little bit of magic left to demystify.
53:08 Daniel Whiteson? All right, Kelly. So are magnetic fields still magic to you?
53:12 Kelly Weinersmith? You know, I still feel like science holds a lot of magic in a good way. Like, it's amazing that we've been able to figure this all out. And maybe I'm stretching the definition of magic. But I still feel, I still feel inspired and uplifted. And I get that sort of like magical tingly feeling when I learn about some of this stuff and the fact that we figured it all out.
53:33 Daniel Whiteson? Yeah, and I think it's satisfying to replace the mystery with understanding. It's not magic in the same way, but it scratches a deep itch for me.
53:40 Kelly Weinersmith? Me too. I think if I said this to my daughter, she'd be like, come on, Mom. But I still feel that in my bones, so let's go with it.
53:50 Daniel Whiteson? All right. Well, thanks to everyone for writing in with your questions about magnetism. And stay tuned for new episodes.
53:56 Kelly Weinersmith? Thanks, Magalos.
54:04 Kelly Weinersmith? Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you.
54:09 Daniel Whiteson? We really would. We want to know what questions you have about this extraordinary universe.
54:15 Kelly Weinersmith? We want to know your thoughts on recent shows, suggestions for future shows. If you contact us, we will get back to you.
54:22 Daniel Whiteson? We really mean it. We answer every message. Email us at [email protected] .
54:28 Kelly Weinersmith? Or you can find us on social media. We have accounts on X, Instagram, Blue Sky. And on all of those platforms, you can find us at D and K Universe.
54:38 Daniel Whiteson? Don't be shy. Write to us.
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