Are Magnets The Most Familiar Mystery On Earth?

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He teams up with an unimaginable ally to defy all odds and save the universe from extinction. See Project Hail Mary in cinemas and IMAX from Thursday, the 19th of March. You can also catch it early on Saturday, the 14th of March, Pi Day and a Sunday, the 15th of March. Welcome to the rest of science. I am Hannah Fry. I'm a mathematician. That's a, if you cut me open, I would bleed equations. But I have been making science programs for about a decade or so. And I'm Michael Stevens. I am a barbecue pit master in my personal life. But you may know me from my YouTube channel, BeSauce, where I make science content, math content, psychology content, whatever I'm interested in. And today I'm interested in magnets. Why do we live on a magnet? Can animals feel magnetism? And I'm going to talk about how I believe that humans can feel magnetism emotionally. But first of all, Hannah, how do magnets work? Oh, I mean, I can give you a sciencey sounding answer about electrons and about spin and about spin canceling each other out and the properties of particular atoms. But if you really want to know how they work, I mean, at some level, it's going to, it's going to involve acceptance, Michael. It does. At some level, we have to just say magnets work because we find ourselves in a universe where they do. It is a fundamental ingredient in our universe, just like gravity. The thing is, people don't question gravity in the same way. Because we experience it so often, it's normal that things fall. It's a little bit like saying, well, how did you end up in the hospital? So, oh, well, because she fell over on some ice. And it's okay, but why? Yeah. Fine men draws this great comparison to asking how magnets work and why they work to, well, what level of explanation do you want? She's in the hospital because she slipped on the ice. Why did she slip on the ice? Well, because ice is slippery. Yeah, but why is ice slippery? Well, because water expands when it freezes. And so, a pressure that compresses it causes it to melt a little bit. So, you're actually standing on a liquid layer on ice. Well, why does water expand when it freezes? Well, the molecular properties of water are quite huge. And this goes on and on. But why does she slip? Well, because she's old. Well, why does that affect it? Well, because you're balanced and your muscle control changes. And psychologically, maybe she was distracted. And suddenly, you realize there is no end, same with magnetism, same with gravity, same with everything. Okay. The insane clown posse asked, just a few months ago, Donald Trump, the president of the United States said, no one knows what a magnet is. And they got ridiculed for statements like that. I don't know who insane clown posse are. Are you not a jugolette? Do I look like a jugolette? Well, no, but I thought for the show you like wash off the makeup. Is this not fego? I really am that boring, Michael. My goodness. All right. Look, so years ago, in a song called Miracles, they wrapped about magnets. Yeah. How do they work? And a lot of people ridiculed them for that statement. Because this is the thing, right? You can answer at a different levels. You can start off and you can say, you take a particular type of metal, something like iron, and you interact it with an existing magnetic field. There is a force of attraction or repulsion that appears. And then you could go a bit deeper and you could say there are field lines that appear around a magnetized object, which you can see with iron filings. And you go a bit deeper still. And you could say down at the level of electrons it's to do with the spin, canceling out or not in some materials. You can kind of keep going and keep going and keep going. But ultimately, even once you're taking quantum effects into account, there is always a level of which you just have to sort of say, because it is. Yes, there's a level where you have to say, look, ultimately, it is an intrinsic property of our universe in the same way that there is gravity. Why? Well, I don't know. If there wasn't, maybe we wouldn't have evolved to ask, but that's a just so story. Even the magnetic field lines you see when you sprinkle iron filings on a magnet, even those aren't showing you the field as it was before you sprinkled it. The iron affects that field. So you're seeing the iron's effect on the magnet. But what did it look like before? It just was. And so, well, I think that yeah, if you want an answer when people start making fun of those who are curious about magnets, you're right. It's ultimately the existence of charge, like the electromagnetic force as a thing in our universe is a property stuff has. And we know that when charges move, they create a magnetic field. They just do. Okay. But here's the thing, electrons are charged and they move in a sense around a nucleus. But they don't spin. And yet we say they have spin. Okay, we're getting really into the weeds here because there is no quick answer. But if we accept that electrons have a charge and that they move in certain ways, some of which don't involve movement at all, spin. I'm looking at you. They create a magnetic field. And those magnetic fields tend to be not lined up in most things. But in certain materials, they can line up and have a macroscopic manifestation. And that's what a magnet exhibits. In iron, in nickel, I mean, very few things that actually have magnetic properties. That's right. And we just happen to be living on a planet full of the stuff. But how did the earth get magnetized? I remember being a kid doing the magnet thing in like fourth grade and you would take a a paper clip and swipe it over a magnet over and over again. And now the paper clip is a magnet. Did someone do that to earth? Well, the earth is sort of doing it to itself inside. And within within the earth's, if you're going to go down into the center of the earth, you have this solid iron core and then you have this sort of magma, this sort of swirling metallic substance. And because the earth is spinning, but also because it's very, very hot in the core and cooler at the outside, you have these currents. So this magnetized metallic liquid is continually moving around. That's one of the things that supports and continues. The fact that the earth has this magnet within it. So what we don't know is where it started. We know, or at least there's the theory, the geodinomotheri that says that moving conductive liquids can maintain and even grow a magnetic field. Do they produce one by themselves? I don't think so. But if there's another magnetic field around, like say from the early sun, the sun may have been much more magnetic when it was young. And the earth could have been in that stronger magnetic field. It's sloshing around this molten iron. And that magnetic field gets kind of ripped and stretched. And it can persist because of this rolling motion. And it still persists today. Because I think this is it, right? Okay. We started by joking about how no one knows how magnets work. But why is the earth itself a magnet? I mean, this is a very strange thing, if you think about it, that north and south, magnetic north magnetic south, which by the way, it's so slightly different from geographical north and south, that they are there and can be sensed by aligning magnets floating them on water. Like, why is that? Where did the earth magnetic field come from? Yeah. We don't totally know. It's not like the earth has a giant horseshoe shaped wily coyote magnet inside of it. What the earth does have inside of it though is a lot of metal. It's got a solid metallic core because pressure is so high. A little further out, it's got molten metal. Mainly iron. There's some nickel, there's some sulfur, there's other stuff there. But most of it's iron. And iron has a property where its atoms can get lined up. But the iron in the in the in the outer core is too hot to be a magnet. Okay, like a magnet couldn't even survive down there. And yet it's magnetic. So there's this whole theory called geodinemothery, which says somehow a spinning planet that's cooling that has molten ferromagnetic metals in it will have swirls of this fluid because of its own rotation. And a moving electrically conductive fluid can grab onto a magnetic field and hold it so that it persists and can even grow. And so at some point in earth's history, it grabbed onto a magnetic field, maybe from our young son, which may have been more magnetic in the past. And it's just been holding on to that. I mean, it's not like there's a battery down there that's sending current through wires. It's just that deep inside the planet, there's molten metal that's moving. And somehow that motion amplifies or holds on to magnetic fields like like a dynamo that keeps this magnetic field alive. So the solar wind can stretch it and shape it, but the source is within. We're carrying it with us. And that means the entire earth is just this big magnet covered in life. Because the fact that the earth is spinning is key here, right? And the fact that the earth is cooling down is also key because you have this temperature difference between that really, really hot center, the central core. And then it's much cooler the outside as you get towards the earth's crust. That temperature difference, it's sort of like imagine a pot of water as it's boiling. You have this circulation currents that that happen from the very hot bottom to the much cooler top, which moves the water around in the same way that it's moving or the liquid inside the earth around. But then also the spin on the earth is helping as well. You have this Coriolis effect. So you get all of these little eddies, these little currents, these little swells inside of the earth. And that is what is perpetuating this magnetism that somehow or other initially arrived on earth that the earth has grabbed onto and kept going for all of these billions of years. You know what's exciting is that just recently we managed to create a geodinamo in a lab. So researchers took a two cubic meter vessel of molten sodium, which is really electrically conductive and they spun it up like in a giant blender so that parts of it were moving at like 15 meters a second. And sure enough, it like took the existing magnetic fields in the room, one of which was from earth and held onto it and magnified it. And even after they stopped spinning it, it maintained that magnetic field. That's probably what earth does. But this is also strange because it's like, okay, well, where did that original magnetic field come from? Because it's not there anymore. I mean, you should get a little bit of magnetism from the Sun, especially when you have solar flares and so on. But it's not enough to have that there must have been some seed somewhere at some point that originally this kind of intergalactic bar magnet. Yeah. That's a floated par star planet that gave it the original magnetism. I know. Like some aliens came by on their bar magnet ship four and a half billion years ago. And they were like, Oh crap, we just made a mess of that planet. They tried to clean it up and they were like, it's not going away. They were just getting out of here and don't tell anyone. But thank goodness our planet is a magnet because that magnetic field interacts with charged particles that fly at us from the Sun and protect us. They redirect those particles so that our atmosphere isn't just obliterated by them. This is why you get the Northern lights, right? Exactly. But it's where the Earth's magnetic field is concentrated sort of exiting from the North and South. And then that is where you see these Northern lights interacting with the Sun's magnetism. Yeah, the charged particles get funneled into the atmosphere there. They create these beautiful lights. But that also protects our atmosphere as a whole from just being peeled away by this powerful radiation. Mars, not a magnet. And guess what? Tell me about its atmosphere. Does it protect the Martian surface from ultraviolet light? Absolutely not. Think again. Serious sunburn on the surface of Mars. Serious. They call it the red planet for a reason. That's right. Well, one other interesting thing about the fact that it is this geodynamite, right? The fact that it's the swirl of the inside of the Earth that is creating this magnet or that is allowing this magnet to exist means that it's nowhere near as stable as you think. And the really nice thing is that you can see in rock, especially when you have volcanoes, for example, as lava ends up solidifying, if there's iron inside of that lava, the iron will line up with the Earth's magnetic field, then cool and then get frozen in place, which means that you can go back really, really ancient lava flows and you can see the direction that the Earth's magnetic field was pointing in. And it's not always that north is north and south, south. This thing has flipped. It's flipped many, many, many, many, many times over the history of the Earth. Do you think it's bad when it flips? Maybe pretty confusing, wouldn't it? If you were out on a sailboat. That would be a hilarious public announcement. Hey, everyone. Compasses still work, but opposite the way they say they do. Exactly. The end that's painted red is now going to point south. For maybe only 12 years, maybe for another few million, we think Earth's magnetic poles flip on average, about every 450,000 years. But we're in a long stretch of stability. Yeah, it's been about 800,000 years since they flipped. So some people say we're due for a flip and it's going to be catastrophic. But it probably takes about a thousand years for the flip to actually have. Oh, it's not like an instant. It's not like you wake up one day and north is south and south is. Oh, bummer. That's not how it works. I think that sometimes these reversals might be just another consequence of something else terrible that happened because we can find that extinction events and pole reversals might line up. It could be that an impact creates a lot of volcanoes and change in Earth's interior that can lead to a switch. But really, the animals all died, not because of the magnetic switch, but because of the ash in the air, because of the impact. Also, Earth's magnetic north pole is actually Earth's south magnetic pole. Oh, really? Is it upside down? Yeah. Oh, it's upside down. Because we made up a rule of how to name the poles of a magnet and we use the right hand rule. Sure. If electrical current flows this way from my palm to my fingertips using my right hand, my thumb points in the north direction. That's up. Yeah. So we make magnets. We had to arbitrarily decide which one's north, which one's south. And this is the field that you can see if you put an ion filing. Exactly. Which way round is it wrapping from that? That's right. And so, yeah, turn some current on through a coil goes this way. That way's north. Oh, shoot. When you make a compass using this mechanism, the north points to the north, but they should repel since they're the same, which means that actually as a magnet, Earth's north pole is its south pole. Tell you what I don't understand. And I've actually until literally this conversation I have never thought to be curious about it. When it flips, right, on the occasions when it flips, it does, it is that north and south swap. It's not like suddenly north is at the equator. And presumably, that must be because of the spin. That must be because of the core. It can. There's a thing called an excursion where the north pole doesn't just like flip, but it like goes to the equator and back. It wobbles. Yeah, it can wobble quickly. But it's stable along that axis, right? Of like the north. It's most stable that way. Yes. Because of the spin. Because of the Earth's spin. But why doesn't it exactly align with the geographic north? Because geographic north south is, if you put a skewer through the Earth on the axis that it spins around, that would be the geographic north south. And then the magnetic north south is ever so slightly off. Yeah. Why? I don't know. I don't know either. They're different by about 11 degrees. And the magnetic pole keeps moving. It's moving from Canada to Siberia right now. It's actually quite close to the geographic north pole. The actual pole that their spins around. But it used to be much further south down into Canada. It moves at about 40 kilometers a year, about 25 miles a year at tops from what we've observed. I've always wanted to go there and watch a compass needle stop pointing in some direction like on the surface, but just point down. Like that right there. That's it. Yeah. Here you go. Okay. Because you basically have this kind of boiling blob of liquid metal that is wobbling around all over the place. And it just wobbles roughly in the same place as this kind of skewer through the Earth and the way that it spins. I don't know what causes it to drift around and not keep lining up with our rotation axis. But there are a lot of factors that affect Earth's magnetic field. Even the tides and the motion of the ocean changes it because saltwater is electrically conductive. And so it's a mess. If you want to be really precise by using a compass, you're going to notice that it's just not it's all over the place. Also the Earth's spin is not absolutely consistent. No, it isn't. It isn't. But why 11 degrees? But then I think maybe we're just thinking about it as though at this moment in time it's 11 degrees, but we shouldn't think of it as static in time. It's something that's right. You sped it up and watched it over the last four-been years. It's bad. It's all over the shop. Yes. And it and reversals seem very random. They don't seem to correlate with any known other process. Okay. I tell you what else would be different. If it did flip, not only would sailors end up going in the wrong direction. But there is one paper that came out about 10 years ago that talked about dogs pooping. Have you heard about this? I have. Is it true? I don't know. First of all, tell the listeners. All right. So this is a paper. It was called Dogs are sensitive to small variations of the Earth's magnetic field published in 2013. Peer reviews, right? Sure. Yeah. Frontiers in Zoology was the journal. And I mean credible researchers over a two-year period, they followed 70 dogs from 37 different breeds. They recorded the directions of the dogs spines during their defecations and the urination. And they demonstrated statistically that they appeared to align with the magnetic field direction. When they pooped. Yeah. One thing I will say is that there have been replication studies on this. People have tried to repeat the experiment and have not found a statistical problem. I'm not surprised. I believe a dog could maybe sense Earth's magnetic field. However, why they would want to poop facing North. I don't know. I can't think of a helpful evolutionary reason. I agree with you. I agree with you. But that's interesting though that you wouldn't be surprised if they could sense it. Because I mean, you're me sitting here. How's your sensation on the magnetic field of the Earth? I can't feel it. I'm not aware of it. It's happening. It's going through my body. I am in it. And yet I don't feel it. It seems as though other creatures can. And that is what we're going to be talking about once we come back after this break. If you happen to be listening to this podcast while out on a dog walk, just without a compass and take notes of which direction. Maybe we should turn this into a citizen's office. I love that. An experiment. Take photos of your dog pooping. Send them directly to Hannah, right? Yeah. Close-ups, guys. My email address is visors at therestescience.gov. This episode is brought to you by Cancer Research UK. Radio therapy is over a century old, but it is still changing. Cancer Research UK helped lay the foundations of radiotherapy in the early 20th century and has driven progress ever since. Radio therapy remains one of the cornerstones of cancer treatment today. Every year, millions of people worldwide benefit from cancer research UK's work to make it more precise. Scientists are still refining how radiotherapy is delivered. 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Try Atio for free at ATT I O dot com slash and power. Welcome back. Good to see you. Hannah, we were talking about dogs, we were talking about defecation. Uh-huh. Let's change the subject. Okay. Not totally. I want to keep talking about animals because there's evidence that many animals, many living things on earth can actually sense and feel, earth's magnetic field. Of course there is. I mean, if you take migratory birds, for instance, how on earth, this has been a question that long-standing question, you know, for hundreds, hundreds of years, how do robins, for example, know where they're going? How do they move around to different climbers, fly south for the winter, and there was always this question of how on earth do they know where they're going? And it looks like, and looks like actually as the operative word here, it looks like they are seeing the magnetic field of the earth. It looks like they're seeing it. It looks like they are seeing it. Tell me more. Okay. So back in the 1960s, they had some experiments where they put robins in in special cages, which had sort of like a type of paper on the outside. So if the bird wanted to fly, wings were just hit the paper, leave in, con the paper, and you could tell which direction they were aiming for. Okay. Now these particular cages were also sort of cone shaped to the bird was sort of sitting in the middle and as it would fly up, you could tell. And then what they started doing was they started messing with the magnetic field around this particular cage, measured with the intensity of it, measured with the direction of it, measured with the inclination of it, which direction the field lines are going in. And they demonstrated that the birds would change the direction they wanted to fly in based on what was going on with the magnetic field. So this is like back in the 1960s and people are like, okay, cool, right? So robins are using the magnetic field of the earth or magnets somehow. They have some form of magnetoception. Exactly. Since not just light and sound and touch, but magnetism. I mean, honestly, magnetoception makes it sound like it deserves its own superhero series. Because we use it to describe superheroes. Because it's just unbelievable that you could sense this thing that we did not evolve the sense totally. But here is where it gets even wilder. Because it looks like the sensing is all going on inside the eye of the robin. So there's a very particular protein that appears in a robin's eye. It's called a crypto chrome. And when blue light hits this protein, it forms this pair of electrons who spin becomes quantum entangled. Okay, so essentially what happens to one happens to the other? I mean, that's the most ridiculously oversimplified revelation of quantum ever. But just go with me for a second. Yeah, I'm going. Okay, so here's the thing. The earth's magnetic field, which is incredibly weak when you're talking at this scale. But it's enough to really subtly change the probability that that pair of electrons will either recombine or separate out. So I mean, effectively what's happening is it has this protein which is so sensitive to magnetic fields that where the magnetic field is present or stronger or which direction it's going in, it changes the chemistry in the retina essentially. And that pattern, that chemical pattern is interpreted by the robin's brain. So what we think it's actually seeing is this sort of faint ghostly pattern that aligns with magnetic north. So it's not like it's not like a metal detector. It's not got like a compass inside it. We think that it sees the magnetic field of the earth as a kind of directional glow within its field of vision. Wow. Isn't that amazing? So it's probably a visual phenomenon. Probably a visual phenomenon. Either things are glowing a bit more north or south. It's not like it's head sort of like to a magnet. It's not like the eye is being like pulled a little bit all the time. Don't think so. They're going, oh, once it gets cold, I need to start following that pull. But maybe it's when it gets cold, I need to follow the glow. And I want to say brightness or color because it could be a third thing. Absolutely. That's also visual that we've never seen. Wow. Isn't that great? And here's the other thing about it. I mean, well, okay, there's many, many great things about this for starters. That idea of kind of quantum chemistry, wizardry. Like normally it doesn't really work when you interact. It was sort of squishy bits of flesh, you know? Biology and quantum is it's very, very difficult to get these effects to work. And this is something that's happening at you know, bird's eye temperature, you know, within a biological being, which is really extraordinary, a being that literally has a bird brain. Literally, literally has a bird brain. I bring the whole new meaning to birds. I view too, doesn't it? Because it's not suddenly birds. I have this bird particular bird's eye. It's got a quite interesting view. We also now know because of the experiments that they've done that it's not the intensity of the magnetic field that it is, that it's sort of seeing or being drawn to. But the thing that makes it know where it is, north or south is almost certainly the inclination of the magnetic field. Let me explain the episode. So if you imagine the earth as though it's like a barg magnet with iron filings around it, those iron filings would go in this sort of a direction. So they kind of come out, they spur out from the top where the north pole is from from from now on, I'm going to use inverted question. Sure fine. They spurred out from the north and then they go around the earth and then re-enter. In like, who? Like ears on the earth. Exactly. And so if you think about it at the equator, those lines are effectively going parallel to the line of the earth itself. Whereas when you're up at the pole, they're coming straight out, they're going sort of, they're coming perpendicularly out of the ground. And so you will be able to tell how far north or south you are by looking at the angle that those field lines make with the ground that you see beneath you. So what we think that they are doing is that is what is they are sensing the inclination of those field lines. And the reason why we know this is because once again, you can put this, put the Robin very safely and ethically in this particular cone shaped cage with the paper on the outside. And you can rotate the inclination angle using something called a Helmholtz coil, essentially a big electromagnetic device. Let's say the bird wants to be in South London. Okay. This particular time of year, that's where it wants to be. If you change the angle of inclination of the magnetic field so that suddenly it believes that it is in Scotland, for instance, then the bird, the Robin will demonstrate something called Zuckertmholtz, which is German for migration anxiety. Nice. It's just like, okay, get me the hell out of here. I do not want to be here. So you can trick the bird into believing that it is at the wrong spot on the earth, which is something that is seeing with its eyes, sees with its eyes. Isn't that amazing? We've got to teach birds to paint. And get them to go, oh yeah, you know, here's what an apple looks like, but then they draw all of these like lines on it and we're like, what's that? And they're like, well, that's the magnetic inclination. You do not see that. Come on, you dumbass. Yeah, right. How do we do that? Okay. Isn't that good? That's really cool. It's not just Robin's that have this, by the way. There's a number of different creatures that have this same protein. But there are other animals that do these long migration patterns that appear to be using magnetic field of the earth to navigate, but there aren't necessarily doing it in exactly the same way. So whales, for example, if you look at blue whales and humpback whales, their paths along the ocean, they follow these magnetic contour lines, essentially lines of constant magnetic strength of the field strength. It's almost like they're sort of reading this invisible map on the sea floor. So they don't choose the shortest path. They don't, you know, kind of they're not just going perpendicular to the motion of the sun. No, it's correlating with the magnetic field line. Exactly. Exactly. And so the theory is about whales is that there's sort of this this this hierarchy of things that they're following. So number one is the magnetic field of the earth. Then they're also using things like the ocean soundscape, things like the smell of water chemistry. But the coastline, the sea bed depth, that kind of thing. But then something that can muck it all up is the sun and the stars. And if the sun has a bit of a hissie fit by which I mean, chucks out some unexpected magnetic nonsense, it can mess whales up. So like when there's a lot of sunspots, because sunspots are aberrations in the earth's surface, where areas become cooler, because of like a bunch of magnetic flux right there that's stopping convection from happening. And by the way, sunspots are not dark. They look in a photograph like a big black spot, but they're really still extremely bright. They're just so much less bright than everything that's hot around them. They look dark. Right. Exactly. Or solar flares, anything like that, anything that's really sort of magnetically noisy, magnetically noisy. And there was a very famous pilot whale, a mass stranding of pilot whales in the Canary Islands, this is in 2002. And everyone was like, how on earth did this happen? These poor whales that have shown up, you know, they shouldn't be here in the first place. And then a team of scientists later worked out that there had been a large solar storm that had hit the earth's magnetosphere, again, sounds like a superhero character, frankly, but had hit the earth's magnetosphere exactly the same moment that the whales went off course. And again and again and again, when whales end up being stranded, people can usually tie it back to some kind of disruption in the earth's magnetic field by a solar event or even a further distant celestial event that's going on. Wow. One of my favorite stories about animals getting lost because the sun's having a hissing fear is in 1997, there was this big race because it's still like pigeon fanciers in the UK, right? Sure. People who race pigeons. Yeah. I'm sure. I'm one of them. Do you know what? I absolutely believe you. I do too. I'm sure there's some who are listening. In fact, I would love to hear from a pigeon fancier, a real one. I could talk your year off all day about pigeon fancing, pigeon racing. Pigeons in general, I'm just I'm quite into pigeons. Anyway, 1997, there was this big race that was being held in the UK. And in that one day, 60,000 pigeons went missing. And it was because there was this intense solar activity that no one is planning. I think in the pigeon fancing community, of course, you'll know this already. It's got a particular name this event, right? When the birds get all messed up by a solar event. Yeah. Yeah. Yeah. We call it going bird zirke. You've given yourself away now. You were telling the truth all along. Oh, I just, well, that's what we call it in my bird circle. Yeah. It's called the great pigeon race disaster of 1997. Ah, yes. I'm part of the pigeon fancier's reform chapter. And we call it the day the pigeons went bird zirke. But go on. I just love the idea, though, that we are existing in exactly the same world as these pigeons as the robins, as the whales. And yet we have no idea. It makes me feel really sad for them. On a day of heavy solar activity, I'm just like, this is kind of a boring astronomical event for me. But the whales are all dying. Yeah. Freaking out the sun's louder than usual. Whatever it is that they see is different. Like reality has changed suddenly. And I'm just like, oh, yeah, I don't know. I got stuff to do. The thing is, is I think there is some evidence that humans do feel this. Go on. We have these cells in our body. They've got tiny little iron crystals in them. It's called magnetite. And I mean, these are like responsive to magnetic fields. You know, the same way a compass would be. So, so in theory, we do have something in our bodies that does, that is capable of changing, according to whatever the magnetic field around us. There was also, there was one experiment where they put people, they wanted to see whether anything would change about us if you put us in these really strong magnetic fields. So they got a bunch of people. They put these caps on the head, the EEG caps, little electrodes that monitor brain activity essentially. And then they changed the direction of the magnetic field inside the chamber. These strengths are similar to that of the earth without letting the participants know that that was what they were doing. They did find something kind of interesting, which is that there was a drop in the alpha brain wave. So these are, it usually means that the brain is processing some kind of, that brain might even process it, but it just doesn't tell our awareness. Just doesn't tell us. Because I mean, as far as we know, we're just, we're kind of wondering around unaware of this. We don't really, we don't really, it wasn't relevant to our survival, like it was for birds, for whales. But we might still have like an evolutionary vestige of the ability to sense it. But we have since stopped listening. Perhaps, yeah. Yeah. Here's the thing though, we don't feel magnetism consciously, but we're very aware of it. We feel it not because of an organ, but because of, well, an organ, the brain. It's curious. We notice things. And we go, why is this compass needle doing this? Why is this, this magnetite, this load stone? Why is it attracted to the other one? Now, animals notice this too, but they don't care. We looked and we cared and we like put it to practical use and we studied it. And we learned about the spin of electrons. We learned about charges. We learned about the fundamental forces of the universe. And so, to what extent do we feel it? Not as a sensation, but as a result of an emotion, curiosity that we have. Curiosity is an emotion. It moves us to do or not do things. And when humans see evidence of magnetism, we get curious. We investigate it. We ask questions, how do they work? And in that way, we're moved to learn and study. In the sense that maybe we can't see it with the same birds, I view that the Robin can. But actually, we can see it because we built technology in order to trace its path, in order to follow it, in order to use it for navigation, in exactly the same way as the birds did. Exactly. Birds use it to navigate and we don't. We do. It's called a compass. But we had to use cognition driven by curiosity to do it. It's like curiosity is this sixth sense that encompasses all the things that we weren't built or no longer can feel, but we want to feel that we don't have the biology for, but we do have the brain power. Right. Do you know about the history of the compass? I really love this. It's exactly as you're saying. So it's like dates back to like second century BC in China. And like there's low stones, these sort of naturally magnetized iron ore, this rock that you can find lying around in certain parts of the earth. And people notice that if you put it on water, it will orient itself, float in a particular direction. And this, you know, when they first appeared, I think people weren't using the for navigation. That happened a lot later. I think they were using it for Feng Shui for divination, that kind of thing. But you're right that it's the curiosity of like, what is this weird rock? And what, why is it changing direction when I float it on water? These for divination. Yeah. That would be clever. I could be like, all right, look, honey, I'm going to put this rock on this floating pad and some water. And I don't know if it points that way. You have to wash the dishes. Oh, what do you know? Yeah. Actually, when they first arrived in Europe, so I think China started using them for navigation, knowing which way is not, of course, if they already knew that there was an object that was pointed in the same direction. He started using the navigation about the 11th century AD. Okay. And when they started arriving in Europe, people were like, okay, there is something deeply not okay. Go. Sure. Yeah. This is witchcraft. This is like wizardry. There's like devil going on here. And they didn't want to use them at all. And I think that is hilarious because the actual answer of what's really going on, you know, that no, it's not witchcraft or wizardry. It's instead, there's a planet scale ledger magnetic field that's generated by this, you know, rotating most nine core hundreds of almost hard to believe. So much, much, much, much way to. And yes, I mean, we associate magnets with magic. Like how did that magician do the trick? It was smoke. It was mirrors is probably magnets, right? And yet we associate superheroes with magnetic abilities because we feel, I think, kind of divorced from it in a way we don't feel separated from gravity. I feel quite close to the weak and strong nuclear forces, but most people don't. But we just don't encounter them. We encounter gravity and magnetism. And we want to know more about why. They seem weird. They seem magic. I mean, that's it, right? It is weirder than magic. It is more extraordinary than that. And yet over the centuries, collectively, we've dug into it, maybe not to the point where we can, we can fully, fully, fully explain it. That comes up where you have to just accept it. But nonetheless, we have uncovered this thing that is weirder than magic. So at the end of the day, like we don't feel magnetism. We don't feel Earth's magnetic field, but we do feel curious about it. And I really mean feeling in the sense of an emotion that causes motion moves us to behave in certain ways. It causes us to build compasses and navigate and study animals and put them in boxes and point magnets at them and see what they do. And so we have come to navigate using Earth's magnetic field, not because it's an instinct, but because we're curious. Well, if you're a curious person, you've come to exactly the right place because that's what me and Mike got to hear for. We are magnets for the curious. Hey, we'll tagline that. As ever, we really want to hear from you. And the things that you're curious about too. So you can email us at the rest of science at GoHanger.com or sign up for our newsletter at therestis.com slash science. See you next time. Next time. See you then. Bye. Bye. Bye. Emers yourself in herbal essences new Moroccan organ oil elixir infused with pure organ oil, just one drop delivers up to 100 hours of hair nourishment with the indulgent scent of a Moroccan garden. Herbal essences new Moroccan organ oil elixir spark quality hair repair without the price tag. 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