Daniel and Kelly’s Extraordinary Universe - Do black holes have magnetic fields?

Episode Date: July 18, 2024

Daniel and Jorge try to resist the magnetic attraction of the mysteries of black holes, and fail.See omnystudio.com/listener for privacy information.

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continue to be moved and inspired by our guests and their courageously told stories. Listen to Family Secrets Season 12 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hey, Daniel, what do you think makes Black Hole so interesting? You know, I think the mystery, the finality of it, the weirdness of it, for sure. They're like a magnet for fascination. They absolutely are for curiosity, for investigation, for dedication. And it's not just physicists. Everyone seems to have questions about black holes.

Yeah, they seem to be sort of mentally magnetic. So black holes attract matter and also questions. They definitely attract questions. They seem to repel understanding. Or they just repel physicists? Pretty sure they'd be happy to suck me right in. I don't think I want to go down that rabbit hole. UC Irvine, and I desperately want to know what's inside those black holes.

If there's even an inside, right? Do we know that they have an inside? We don't really know anything beyond the event horizon at all. In some sense, the interior of a black hole could be like another universe. Whoa. Like we could be living inside of a black hole right now. Is that possible? I think that gives me a mental black hole even thinking about it. I suckered you right in. But anyways, welcome to our podcast, Daniel and Jorge Explain the Universe, a production of IHeartRadio. In which we try our best not to give you a headache

while we contemplate the deepest secrets of the universe. We want to understand everything that's out there from the tiniest little bits to the hugest swirling black holes and everything in between because we think that it's possible somehow to make sense of it all, to understand it, to predict it, and to explain all of it to you. Yeah, that's right. we try to be the Advil or Tylenol to your understanding of the universe,

not give you a headache about how amazing things are, but rather try to ease the pain of trying to wrap your mind around this amazing cosmos we live in. I think it was that's your prescription for physics. Well, everybody out there is going to need like another kind of health insurance now. Physics health insurance. Do physicists have special health insurance for, you know, headaches and mind bending? We're going to have you cover the cost of understanding the universe because while physics has made lots of progress in understanding the way the universe works, there are still huge gaps in our knowledge. In fact, we're pretty sure there's more that we don't understand than that we do.

And a lot of those mysteries might have answers waiting for us beyond the curtain of the event horizon. Yeah, as we've talked about, we only know about 5% of the whole universe. The rest, the other 95% is a complete mystery. and even within the 5% that we think we know, there are still huge holes in our understanding of how things work and what can happen out there in the universe. The best way to unravel some of the open mysteries is to embrace the unknown,

is to dive into our ignorance and try to reveal something new about the universe. Often this happens at the extreme points of the universe, places where things are super duper hot or super duper dense or super duper crazy because it's at those places that our understanding breaks down. That's one reason why black holes are so attractive to physicists because they are where our current theories have to break.

Yeah, it seems like there's no place in the universe that is more extreme or mysterious than a black hole. We have so many questions about that. Everyone has questions about it. It seems that it attracts not just mass and energy, but also curiosity. It does, absolutely. I don't know if it sucks in curiosity or it's radiating curiosity

or how the whole curiosity field works. and cocking radiation of curiosity. Exactly. Maybe it's consuming anti-curiosity while radiating curiosity. Who knows? Anti-curiosity. Oh, that's an interesting concept. What is that?

I don't know. That's what we're trying to generate on this podcast. We're trying to satisfy everybody's curiosity. Or are we just trying to stoke it? I'm not even sure anymore. Yeah, it sounds like you're trying to annihilate people's curiosity. No, I guess we're trying to generate anti-confusion particles. How about that?

Oh, there you go. rockons get itinos exactly the aha particles that's what we're after yeah I want to be one with the aha field but there are still very basic questions about how black holes work what it means to be near a black hole

what you would experience what you might measure with your devices near a black hole we've talked about the mass of black holes we talked about the charge of black holes we talked about the spin of black holes but there are still even more basic things we can think about when it comes to black holes. So today on the podcast, we'll be tackling the question.

Do black holes have magnetic fields? Like, are they attractive or repulsive? Do they have raised or not? Can you use black holes to find lost wedding rings on the beach? I knew there was a practical application of my research somewhere. Could you use it to detect your wedding ring on the beach? wouldn't it just swallow up the whole beach? Then you'd have a good excuse for why you lost your wedding ring.

Look, I mean, there was a black hole on the beach. Yeah, and you would technically know where it is. It's inside the black hole. You just, you know, you can't get it ever. Yeah, exactly. No number of explainions is going to get you out of that jam. Yeah. But yeah, it's an interesting question.

Do black holes have magnetic field? And I know we've did a whole episode on whether black holes have a chart, right? Mm-hmm. Yeah. And so this is different. This is more about the magnetic field. Yeah, we did one on chard. We did another one on spin.

There's not that much stuff you can actually know about black holes. And we know so little. So I'm always excited to talk more about it. Didn't we do a whole episode on the hairiness of a black hole? That's true. Their lack of hairiness, actually. They're smooth shavenness. Yeah.

Well, this is an interesting question. And so as usual, we were wondering how many people out there had thought about whether black holes have magnetic fields and if they do, what do they look like or feel like? I think it's possible that they do. I think if I'm not too sure exactly how to

rationale it, but somehow I feel like it might be possible for black holes to have magnetic fields. I think they do if only from the spiraling matter that's been consumed by the black hole. Whether or not they are magnetic in their core, whatever their core is, or if you can have a

call in a black hole, I don't know. But by virtue of the hole of the object, that's W-H-O-L-E, yes. I do not believe so, only because I do not believe there are any charged particles within a black hole. However, since we do see jets coming from black holes at times, I could be totally wrong about that. I don't really know, but if I have to guess, I think they would, like, something to do with the Hawking radiation being magnetized somehow or so. The black hole itself beyond the event horizon, I don't think we can know that, but the area around the black hole where the accretion disk is probably can have a magnetic field.

Black holes have mass and they have spin and I believe they have a charge. So if something has a charge, it should also have a magnetic field, probably a little squirrely with the amount of gravitational forces going on, but going with yes. Yes, I'm pretty sure black holes have magnetic fields because whenever a particle that's charged enters it, the electric charge is conserved. So I guess a black hole would need to have that magnetic field that. that the particle had. I have no idea that as a wild guess,

I would say yes. They have probably vacuumed up some magnetic vibes along the way. Black holes do have magnetic fields. I'm pretty sure that the Beatles wrote a song about it. Magnetic fields forever. If a black hole is churning around, does it create a magnetic field? Is there a North Pole to a black hole?

I wonder if magnetism can escape gravity or is immune to it. I think magnetars are neutron stars with a magnetic charge. I'm not sure about a black hole. Maybe if it's spinning and has an electric charge? I think that if a black hole, a bunch of large stuff with a magnetic field, then the black hole would get a magnetic field. I'm going to say yes because there's one out of three things that black hole presents

so that we can measure, but I forget one of them. So there are spin, mass, and electromagnetic force. So I'm going to say yes. All right. interesting answers from a lot of magnetic people. Yeah, you could tell a lot of people had not thought about this question at all. They seem to sort of come up with their answers on the fly. Yeah, it's kind of a polarizing question.

People either retracted or repelled by it. Yeah, well, it seemed to attract definitely a lot of ideas about what's going on in the black hole. And so let's dive right into it, Daniel. Take us through the basics of black holes and how they relate to electrical. So fundamentally, we don't really know what black holes are in our actual universe, like the physical things that are at the center of the galaxy or that have really dense stuff orbiting them really closely. We're not really sure what those things are, but we do have a concept in our theory.

General relativity predicts a kind of black hole, but we know again general relativity can't be right. So this theoretical object can't actually align with what's out there in the universe, but it gives us something to dig into something to play with. And because general relativity tells us that gravity is not a force between objects the way Newton described it, but instead a curvature of space time, there's something weird that can happen when you get enough mass, enough energy density actually together in one place, which is that space can curve so much that the inside is essentially cut off from the outside. There's a place beyond which space is curved so that it only

points towards the center of the black hole, meaning any object that falls past that event horizon will always end up at the center of the black hole. And so this is the basic concept of a black hole, sort of extreme space-time curvature that generates this event horizon past which nothing can escape. Right, right. Because I feel like that's always one of the caveats we have to point out is that the bending of space time, right? It's not just sort of space. It's also sort of like what happens in the future. There are definitely time-related effects also mass bends space and creates this event horizon. It also bends time.

So if you are near a black hole, for example, a distant observer will see your clock go more slowly. And near black hole, space and time are very confusing. And in fact, the whole concept of space time is easier to understand in special relativity when you have flat space. In general relativity, which direction is space and which direction is time becomes very, very confusing. And in some cases, it's not even clear. And so as you said, it's something that physics predicts is happening out there in the universe because we see around us and it seems like, you know, the sun is bending space around it.

The earth is bending space around it. And we're bending space around us. But if you take it to an extreme, it predicts something called a black hole. Yeah. And a lot of people imagine a black hole in a sort of Newtonian way. They think, oh, gravity is so strong that you have to go faster than the speed of light in order to escape it. but it's not a question of forces, it's not a question of velocity, it's not a Newtonian picture at all. It really tells you that the story of how gravity works is very, very different, that you're literally trapped inside this event horizon.

No amount of velocity, no force can ever escape it because the shape of space itself has changed. And so if you imagine space is this like emptiness in which things float, then you need a new idea. General relativity tells us we could describe it as this sort of stuff with curvature to, it that we're moving through that curvature and that curvature is not sitting inside some like deeper larger space that you might be tempted to imagine that's all there is and we are trapped inside of it and there's nothing on the outside of it as far as we know right right and as usual we also have to give the caveat that black holes are technically theoretical right like we've seen things that sort of behave like black holes but we haven't sort of been in front of

one or touched it right that's right and what we're describing is a prediction of general relativity, which we know to be very accurate in most circumstances, except we expect it to break down when things get very, very intense and very, very small. And so, for example, general relativity predicts that at the heart of one of these black holes is a singularity, a point of infinite density. This runaway gravity just goes on forever and you get infinite curvature at the heart of the black hole. But we don't think that that's really happening because we know that that's in conflict with quantum mechanics.

And so real black holes, if they exist out there in the universe, can't align perfectly with this theoretical description of a general relativity black hole. There has to be some quantum fuzziness to it, some other version of a black hole. And we talked recently on the podcast how quantum black holes probably radiate. They're not perfectly black due to hawking radiation. And there must be other changes we need to make from this general relativity picture of a black hole to a realistic quantum gravity black hole that we don't even know how to describe. And you're right that the things we've seen out there in the universe, at the heart of our galaxy, et cetera, we're not even sure if they actually are black holes because we've not technically observed an event horizon. All we've seen is that there are very dense objects, very massive, very small, very compact.

And so we suspect that they are black holes. But they could be something else. These days, there are quantum gravity inspired ideas for other things that could fit the data, fuzz balls or dark stars etc yeah all kinds of fun names i wonder if we should maybe start calling black holes and not black holes then maybe or maybe just black holes with a question mark black holes really dark objects ardeos all right so then a big concept in a black hole is this idea of an event horizon now is the idea of an event horizon also dependent on relativity and quantum mechanics playing nicely with each other or does relativity only break down at the center of a

black hole? Like, is the edge of a black hole safe to talk about? The edge of a black hole is really only something we can talk about in general relativity. We don't know how quantum mechanics will modify that. It might make it so that there are no event horizons. These buzz balls, for example, compact states of strings do not have event horizons at all. So it could be that there are no event horizons. in the universe. So if we want to talk about this, really the only thing we can do is talk about what general relativity predicts, even though we're not exactly sure it's real. So then how do you define the event horizon then? Well, in general relativity, the event horizon is the point past

which no information can escape. And that's something we can calculate in general relativity. And it depends on the mass of the object, also whether it's spinning, whether it has charge, these kinds of things. And it's kind of a very special point in a black hole because that's the point at which not even information can escape right yeah that's right so the sort of limits of things we can know about the black hole yeah you can't know anything that's going on inside the black hole but you can measure some things about the black hole like we know for example obviously you can measure the black hole's mass you can measure its gravitational effects on things nearby if you fly near a black hole you're going to be drawn

towards it because space is curved so the effect of the black hole exists outside the event You can sort of think of it as the event horizon itself having a property. The event horizon is there. It summarizes all the stuff that's inside of it. The mass of the event horizon or the black hole itself affects space outside the event horizon. So you can definitely know that about the black hole and you can know a couple of other details as well. Like the spin and also the charge of a black hole, right? Yeah, that's right.

Those are the three things that general relativity says we can know about the black hole. that a black hole can also be spinning, right? Things that fall into a black hole. If they have angular momentum, they have to keep having angular momentum because in our universe, angular momentum is conserved, we're pretty sure. Same thing with electric charge. The universe strictly preserves electric charge. We've never seen that violated. You can create plus and minus particles together, but the overall charge of the universe has to be the same. And so if you drop an electron into a black hole, then the black hole has to have that charge because it can't just disappear from the universe.

So mass, spin, and charge are the things you can know about a black hole from the outside. You can't know like the arrangement of charges or masses or spins or whatever inside the event horizon, but you don't have to in order to know the total mass or the total charge or the total spin from the outside. Can you tell if a black hole has a headache or something? Do black holes wear mood rings? I wish they did. What does that mean?

Do they wear engagement? rings. Well, you said charge, and I'm wondering, you know, that's the electromagnetic charge, but we also talk about in this podcast about other kinds of charge in the universe from the weak force and the strong force. Can you know those other charges about a black hole? Can you know the color of a black hole? The color charge is a really fun and tricky concept. It's not something we really understand very well because objects that have color don't ever exist in the universe. We only see neutral things, like things that have color like quarks are always bound together into neutral states, something with the opposite color or the other two complementary colors. So they balance out because there's so much energy in the strong force.

So things can't have their own color charge. You might want to imagine like what happens if you have a quark anti-cork pair and they're bound together, but one of them falls into the black hole. And now you're doing quantum gravity because we're talking about bound states of quarks and one of them falls into the black hole. and the other one doesn't. We don't know the answers to those questions because we don't have a theory of quantum gravity. But is it possible that maybe they also conserve those kinds of charges and you would have to add that to the list of things

you can know about a black hole? It is possible. And it's also possible that there are other kinds of charges in the universe we've never even discovered. Like dark matter could have all sorts of other forces. There could be like a dark version of electromagnetism with dark photons and dark charges. And black holes could have those dark charges

as well. Wait, wait, wait, you're saying black holes could have a hidden charge? Like a hidden fee? Exactly. Check your statements, people, when you buy a black hole. Read the small print before you go into a black hole. All right. So then that's, you know, we can tell it has a gravitational field and an electric field. And now let's talk about a magnetic field of a black hole. What exactly is a magnetic field? Magnetic fields are really weird and awesome because they have lots of really interesting symmetries, symmetries that exist and also symmetries that are broken. Like in a lot of ways, the magnetic field is a perfect sister to the electric field. Like light, for example, is a balance between electric fields and magnetic field. It's sloshing

perfectly back and forth between electric fields and magnetic fields and back. It really tells us that the distinction we make between electric fields and magnetic fields is a little bit arbitrary. It's just sort of like a historical thing. We drew a dotted line between these two things that are really part of a larger hole. But there also are important differences between electric fields and magnetic fields. For example, we have electric charges in the universe, but we don't have magnetic charges.

Like an electron has a negative charge, you can just create a charged object by putting an electron on it, right? You can't do that with a magnetic field. There's nothing with a magnetic charge. If it existed, this would be called a magnetic monopole. It'd be like something with just a north or something with just a south.

We've never seen one in the universe. Physicists don't know why. They think maybe they do exist out there or used to exist in the early universe. But you can't make a magnetic field the same way you make an electric field by just adding a magnetic charge to something. Well, maybe take a step back here because, you know, like I'm wondering how do you even define what a magnetic field is? You know, like a gravitational field tells me how much a planet, for example, is pulling on me at any point in space or an electric field tells me how much, you know, an electron is repelling or pushing me or attracting me. at any point in space, what does the magnetic field tell you? Yeah, great question.

If they were magnetic monopoles, then they would be affected by magnetic fields the same way that electrical charges are affected by electric fields. They would be accelerated in one way or another. But those don't exist, so we can't use that to define magnetic fields. What do you mean? Like, when you talk about monopole, you mean like in a magnet that you have a north and a south, right? In the magnets that we have in our universe, we have a north and the south. Those are dipole magnets that create a dipole magnetic field.

There's a pair of a north and a south. So are you saying like if you had a north in front of me and I'm a south, it would tell me how much I'm attracted to the north or repelled? Yeah, exactly. If you have a huge magnet, it makes a magnetic field. And then if you put a north in that field, it would get pushed or pulled in one direction. And by the strength of that push or pull, you could measure the magnetic field.

So there is some sort of charge? Yeah, exactly. Like what would determine how much of that push and pull I feel? Well, the north and south are like the plus and minus, right? North and south for a magnetic field are plus and minus for electric charges. And I can have like more of it or less. Yeah, exactly. You're going to bigger magnets or smaller magnets.

You go to more norths and more souths. We've never seen a north on its own or a south on its own the way we have for electric charges. But in principle, they could exist. Nothing in physics says that they can't. But we've only ever seen them paired together. Meaning like if something has a north, it also has a south. Yeah, and that's because those magnetic fields are actually made by electric charges. See, there's a very close connection between electricity and magnetism because if you take an electric charge, like an electron, and you whizz it around in a circle, it makes a magnetic field.

Any charge in motion, any charge with velocity is going to make a magnetic field. And so every magnetic field that we ever created is actually made by moving electric charges. So if it's made by electric charges, it's made by the electric field. So why do we even call it its own field? Well, because it's made by electric charges doesn't mean it's an electric field, right? Yeah, we could just call this electromagnetism. You might be saying, hey, the distinction between these two things seems arbitrary. Yes, it's totally arbitrary and historical because we discovered magnets and we discovered lightning.

We called them two separate things. We built two theories and then boom, one day, a brilliant Scottish dude realized there are actually two parts of the same thing. Now we call them electromagnetism. And you might say, let's just call it all electromagnetic fields. Cool, we can do that. But we do notice that there are two different charges that are described by this field, electric charges and magnetic charges. And only one seems to exist in the universe.

All right. So it's deeply connected to electricity. And some things just seem to have it or not, right? Things with charge seem to have it or not. Yeah. So every magnet we've ever seen in the universe is either a tiny little object that has quantum spin, like an electron has quantum spin, and that spin combined with its charge makes it a tiny little magnet. But because it's spinning, it makes two magnets. It makes a north

and a south. So it's a little dipole magnet. Or you can have current like motion of electrons through a wire that makes a dipole magnet. So every magnetic field we've ever seen is made either by tiny little quantum particles having their own little magnetic fields. That's, for example, why your refrigerator magnet has a magnetic field, has all these little particles with quantum spin oriented in the same way, adding up, or like an electromagnet, like an electric motor that comes because of current from electricity. Interesting. And so I guess now the question is, since black holes can have an electric charge and

also spin, can they also have a magnetic field? So let's dig into that. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal glass.

The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and Order Criminal Justice System is back. In Season 2, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious.

Well, wait a minute, Sam, maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor. and they're the same age.

It's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale,

listen to the OK Storytime podcast on the Iheart radio app, Apple Podcasts, or wherever you get your podcast. I don't write songs. God write songs. I take dictation. I didn't even know you've been a pastor for over 10 years. I think culture is in your.

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special came on. And all the great Motown artists, Marvin, Stevie Wonder, Temptations, Diana of all. From Mary Mary to Jennifer Hudson, we get into the soul of the music and the purpose that drives it. Listen to Culture raises us on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Imagine that you're on an airplane and all of a sudden you hear this. Attention passengers. The pilot is having an emergency and we need someone, anyone, to land this plane. Think you could do it? It turns out that nearly 50% of men think that they could land the plane with the help of air traffic control. And they're saying like, okay, pull this, and so this.

Pull that. Turn this. It's just, I can do my icecloth. I'm Manny. I'm Noah. This is Devin. And on our new show, no such thing. We get to the bottom of questions like these. Join us as we talk to the leading expert on overconfidence.

Those who lack expertise lack the expertise they need to recognize that they lack expertise. and then as we try the whole thing out for real wait what oh that's the run right i'm looking at this thing listen to no such thing on the iheart radio app apple podcasts or wherever you get your podcasts all right we're asking the question can a black hole have a magnetic field and what would happen if you put it on your fridge. He would eat everything in your fridge. There you go. You can blame that

also on a black hole. I don't know who finished the pie, honey. Really, I don't. Maybe it was a black hole in the middle of the night. Check the camera. Yeah, me or a child put a black hole on the fridge there. The new black hole diet by Daniel.

Yeah, and I don't think that's how diets work. I might need to workshop that a bit. Yeah, yeah, yeah. It's more like an excuse for a bad diet. But yeah, so black holes, do they have magnetic fields? Like literally, if you have a tiny one, would it stick to your fridge? That's kind of what we're asking here today, right? Right?

Yeah, it's a really cool question. And the answer is it depends. Why am I not surprised? It depends on your reference frame. It depends on your velocity. Because we don't have magnetic monopoles. You can't just like throw a monopole into a black hole and have it have a magnetic field like inherently. The only way for it to have a magnetic field is for it to do what electrons do and electric currents do,

which is have a charge and a spin. So take a black hole, spin it and charge it by shooting like a beam of electrons right near the event horizon. So it gets some angular momentum and it gets some charge. In that case, it will get a magnetic field because now it's spinning relative to you. So if you have like a magnetometer or something, you will measure a magnetic field near the event horizon. Sort of in the same way that like an electron on its own can have an electric field because it's a charge,

it has charge and it has spin. Yeah, exactly right. Or like if you take a coil and wire and you spin a bunch of electrons, that is those that charge spinning, which creates a magnetic field. Yeah, exactly. You make a coil of wire and you run a current through it.

That makes a magnetic field through the core. coil, right? Or simply, if you just have a single line of wire, not a coil, and you run electrons through it, then you're going to get a magnetic field around the wire. But that magnetic field is frame dependent. It depends on the electrons moving relative to you through the wire. It only happens because the electrons are moving. It's charges in motion that give us magnetic fields. So if you have your black hole and it's spinning near you, you measure magnetic field. Now you get in your ship and you start orbiting the black hole at exactly the same rate it's spinning

so that when you look out of your ship the black hole is not spinning relative to you then it no longer has a magnetic field. The magnetic field is frame dependent. Well, meaning that the magnetic field disappears or that you don't feel it? It's not there. I mean, we don't even know if fields are real anyway

but you can't measure it and according to the physics it isn't there. Like you do the calculation. there's a prediction of no magnetic field there. And the thing is, the field itself, you like to think of it as something physical that's out there in the universe. But the distinction between electric fields

and magnetic fields, like you were saying earlier, is a little bit arbitrary, and it turns out to depend on your frame of reference. And not just for black holes, also for the simple situation of an electron going down a wire. If you jump in a car and you drive down the wire the same speed as the electrons,

the electrons only have an electric field, but your buddy who's standing, next to the wire, he measures the electrons going through the wire. They have a velocity. He will also see a magnetic field. So magnetic fields are always frame dependent because they depend on velocity. Well, that's a little bit odd to me, I guess. So let's say have like a loop of wire and I run a current through it.

You're saying if I sit in the middle of it on a like an office chair and I spin myself, then I'm not going to feel the magnetic force? Yeah, if you spin at the same rate that those electrons are moving, so the electrons have no velocity relative to you, then you will feel no magnetic field. You will sense no magnetic field. It's a tiny little bit more complicated there because now we're spinning,

so we have acceleration and non-inertial frames. So it's a little bit simpler in the straight line case, but yeah, the same thing applies. Right. I guess that's what I was trying to get at is that you're saying it depends, but it doesn't depend on like an inertial frame, which is sort of like the standard frames of the universe.

It's like you have to make up this weird frame. frame, right? Like I would be feeling other things. I won't feel that electromagnetic field, but I'm going to feel, for example, this interpital force. Yeah, exactly. And that's sort of the missing piece because you might be wondering like, hold on a second. If I'm measuring a magnetic field and my friend is not measuring a magnetic field, how is that possible? It dropped a monopole into that situation. Would it get pushed or would it not get pushed? Right. It has to be like one answer to that question. And the answer is a little bit subtle, but kind of of beautiful. What relativity tells us is that the same laws of physics apply no matter what your

reference frame, but the story they tell about why things happen doesn't have to agree. So in one scenario, your friend will say, oh, there's a magnetic field there and it helps push things around. The other person will say, no, there's no magnetic field there. But they will also see the electric field is a little bit different and that will compensate. So one person will see a combination of electric and magnetic fields doing pushes and pulls on charged particles and magnetic monopoles somebody else will see only electric fields and no magnetic fields but they'll actually predict the same motion for all the particles they'll just have a different reason for why it happened right it's sort of like if you're moving with the

electricity then you won't feel the forces of the electromagnetic field but you'll have to push and spin yourself around the wire which is sort of a quick And I think is what you're saying. Yeah, all the differences actually add up to give the same prediction, which is kind of amazing. And that's one of the beautiful things about relativity is that it shows you that all these pieces work together because really the distinction between electricity and magnetism is a bit arbitrary and it's even frame dependent. You know, people going in different speeds see electric fields or magnetic fields, but all the pieces

work together so that even people in different reference frames, while they tell a different story about why things happen. Like, did you have a magnetic field or not? They will agree in these scenarios about what actually did happen. But I wonder if you can just, can you just say the same thing about everything in the universe? You know, like you could also make gravity disappear if you move with the gravity, right? Or you can make electric charge disappear if you move with the charges. Not everything in the universe is frame-dependent. For example, black holes are not. If there's a black hole, then everybody agrees there's a black hole. You can't, boost yourself into some frame in which there is no black hole.

This is why, for example, you can't make a black hole just by going really, really fast. You might think, oh, black holes actually happen when you have a lot of energy, not just mass. So why can't I make a black hole by taking a particle and zooming it to really high speeds? Because that would make a frame-dependent black hole, which doesn't exist in our universe. So there are some things that are invariant, no matter what frame you're in, inertial or not. But yeah, there are a lot of things in the universe that are framing. independent. I think more than people suspect. Right. I wonder if the analogy is sort of like, you know, if you jump out of an airplane and you're

falling towards Earth, you can't tell that there's a planet there below you, right? Like to you, it's going to feel like you're floating in space as you plummet to your death. Yeah, that's right. In that scenario, you're actually in free fall. You're not doing any accelerating. It's the planet that's accelerating towards you. The surface of the planet is accelerating towards you. If you take out a gravitometer or an accelerometer in that scenario, you'll measure no acceleration. So you need to look out the window to see a planet rushing towards you to discover that your lifespan is going to be very short. Right. So in that way, so the gravity is also

reference dependent, right? I can make it disappear if I jump out of an airplane. Lots of gravitational effects are frame dependent. Yes. There are some things that are frame independent, like the existence of a black hole. But a lot of things are frame dependent, absolutely. And you're right that this story applies very broadly. There's lots of situations in physics where people will disagree about why things happened, even if they apply the same rules, and they might agree about what happened. They'll tell a different story about how that happened or why that happened, even though the outcome is the same. But I guess if you stick to what most people think is normal, which is like an inertial frame or, you know, not spinning around in a crazy speed in an office chair,

then you would say that a black hole does have a magnetic field. Yeah, exactly. And it's not special, right? The black hole has a magnetic field in exactly the same way a coil of wire has a magnetic field. You got charge in there. You got spin. So you're moving charges. So you get a magnetic field. The magnetic field of a black hole is not deficient in any way compared to the magnetic field from an electromagnetic motor, for example. And I guess what that means is that if I take a compass and I hold it up close to a black hole, I'm going to see it point in a specific direction, right? Just like it points to a specific direction here in Earth. Yeah, exactly. A black hole will have a magnetic field the way the Earth does. We think the Earth's magnetic field probably comes from convection and flow of stuff inside the Earth, though we don't totally understand.

And so, yeah, you could use a compass to navigate near a magnetic black hole. Does that mean black holes have a North and South Pole? Yeah, exactly. They have a North and South Pole for their spin as well, right? A black hole that doesn't spin is spherically symmetric. But a spinning black hole has broken that symmetry because there has to be some axis. around which it's spinning. So that gives it a north and south spin black hole. And because that spin is what generates the magnetic field,

it also then has a north and south magnetic pole. Whoa. And so if I have a tiny spinning black hole, then it would be attracted to my fridge door, right? Yes, it would be attracted to your fridge door. Even if its gravity was too weak to hold it there, its magnetic field might be powerful enough. Because remember, magnetic fields are much more powerful than gravity.

so you make a tiny black hole out of a few electrons it might not have very strong gravity but the magnetic field could already be quite powerful yeah it's interesting to think that a black hole has a north and south pole I hear the north pole of a black hole is where all the dark elves hang out are they making dark presents

for dark Christmas yeah now they're just making a bunch of coal presents for everyone it's the opposite it's the opposite I see. Can you measure the magnetic field of a black hole from a distance? In principle, if you were near the black hole, you can do what we describe, which is use the compass.

We can't go near black holes, unfortunately, but we can see the effect of black holes on nearby particles, right? Black holes are almost never on their own. They formed because they're in the middle of some dense blob of matter they've been gobbling. So usually there's a lot of stuff around them. And if you trace the path of the charged particles near the black hole, then you can measure something about its magnetic field. But those particles also will generate a magnetic field. So teasing those two things apart is quite tricky.

Sort of like if you threw a bunch of iron filings, filings, filings at a blockhole, they would form a pattern around the black hole. And that would tell you, oh, that's the magnetic field. That's where the North Pole is pointing. Yeah, it's filings if it's little pieces of shaved iron. It's fillings if they came from people's teeth, which were you to imagine. Both, I guess. I guess both would work.

I guess if you go near a black hole, it might pull out your iron fillings. What do you file some fillings? I'm going to find a complaint with the black hole division if that happens. Now they're full, I think. They filled up already. Yeah. All right. So then could we measure it potentially from Earth?

Like if we, you know, we have these pictures now of what we think are black holes. Could we measure their magnetic field from here? Absolutely. We can. And we have. We have. All right, well, let's talk about that. But first, let's take another quick break.

December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA. terminal. Apparently the explosion actually impelled metal glass. The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and order, criminal justice system is back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder

to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem. but I don't trust her. Now he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate.

Well, according to this person, this is her boyfriend's former professor and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. I don't write songs. God write songs. I take dictation. I didn't even know you've been a pastor for over 10 years.

I think culture is any space that you live in that develops you. On a recent episode of Culture Raises Us podcast, I sat down with Warren Campbell, Grammy-winning producer, pastor, and music executive to talk about the beats, the business, and the legacy behind some of the biggest names in gospel, R&B, and hip-hop. This is like watching Michael Jackson talk about Thurley before it happened. Was there a particular moment where you realize just how instrumental music culture was to shaping all of our global ecosystem? I was eight years old, and the Motown 25 special came on. And all the great Motown artists, Marvin, Stevie Wonder, Temptations, Diana Raw. From Mary Mary to Jennifer Hudson, we get into the soul of the music and the purpose that drives it.

Listen to Culture raises us on the iHeart Radio app, Apple Podcast. or wherever you get your podcasts. Imagine that you're on an airplane and all of a sudden you hear this. Attention passengers. The pilot is having an emergency and we need someone, anyone, to land this plane. Think you could do it?

It turns out that nearly 50% of men think that they could land the plane with the help of air traffic control. And they're saying like, okay, pull this, do this, pull that, turn this. It's just... I can do it my eyes close. I'm Manny.

I'm Noah. This is Devon. And on our news, show No Such Thing, we get to the bottom of questions like these. Join us as we talk to the leading expert on overconfidence. Those who lack expertise lack the expertise they need to recognize that they lack expertise. And then, as we try the whole thing out for real.

Wait, what? Oh, that's the runway. I'm looking at this thing. Listen to No Such Thing on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. All right, we're talking about the polarity of a black hole. They're very polarizing black holes. Some people love them.

Some people really love them. Those are your only two choices. Yeah, you either love it or you don't love it. Fill out this survey or would take your iron fillings. Well, we're talking about how a black hole has a magnetic field, but it's sort of not new. information, right? Like it's the product of its charge and it's been, so it's not like it has a fourth property that you can find out about it. It's sort of a derivative of its charge and spin. Yeah, exactly. Not derivative in the calculus sense, but derivative in the like, oh, you

just copied that sense. It comes out of the other properties. It's not a core basic quantity of a black hole itself unless the black hole had a magnetic monopole in it and then it would be a core property but you're right it sort of emerges from the other properties what would you mean if a black hole ate a monopole if a black hole ate a monopole it'd be something we call a dionic black hole and it would have its own monopole magnetic field just like the monopole that fell into it right how would it ever eat a monopole number one a monopole would have to exist in the universe and we don't know that they do but they might and then it would have to go near a black hole and then gobble gobble.

Could a black hole split a dipole into two monopoles? It eats one and it shoots off the other one? That would be an awesome feature of quantum gravity. Currently in our predictions, no, you can't split a dipole because like where does that come from? It comes from the electron spinning. So you're going to split the electron somehow. So we don't know how to do that.

I don't know. In general, can you tell a black hole what it can or can't do? If black holes are listening to this podcast, I apologize for my presumptuousness. they're going to come after your fridge watch out all right well so what can we see of a black hole

or what have we seen so we've seen the black holes have a huge effect on nearby matter they don't just suck stuff in they also shunt stuff away from themselves their magnetic fields can be so strong that infalling particles

can actually follow those magnetic fields and then escape the black hole you know the same way that like we've seen these aurora because charge particles falling in towards the earth end up spiraling around our magnetic fields and then end up at the North Pole. It's also possible when particles are falling

in towards a black hole. Basically the same thing happens, but they get so much speed that they then escape the grip of the black hole. And they shoot out up and down the North and South Poles. And we've seen these enormous jets from black holes. You see galaxies with super massive black holes at their center

and then these huge jets extending thousands of light ears up and down sort of above and below the plane of the galaxy. Those are jets from the central black hole and they're powered by its magnetic field. Whoa, wait, wait, hold on. It's not stuff coming out of the black hole, is it? Right?

It's not, right? Because nothing can escape a black hole. It's not something escaping a black hole. It's something having a near miss. It's like fell in and then the magnetic field outside the black hole, the same way we have a magnetic field outside the atmosphere of the earth.

The magnetic field that's outside the black hole guides those particles towards the north and then they escape but they never went inside the event horizon I see now I wonder if that means that a black hole looks different to like an electron

than it does to a proton potentially they definitely do look a little bit different I mean a proton and an electron have different charges and so they're affected differently by those magnetic fields but all these particles do see the same event horizon the event horizon is the event horizon is the event horizon

is the event horizon. But wouldn't their paths near a black hole be different, in which case the point at which they would definitely fall in is different? Yeah, the paths near the event horizon are different because they are affected by magnetic fields differently and their masses are different, et cetera, and their charges are different. But the event horizon is still just the event horizon.

That's a feature of the curvature of space. It's not an issue of like the forces on the particles, remember. It's a product of the black hole itself. And that's just from the magnetic field of the black hole itself. You mentioned earlier that the stuff swirling around it can also make magnet fields. Yeah, exactly. There's huge accretion disks surrounding most black holes, especially the ones at the center of galaxies that have been feeding on gas and dust.

And so there's a lot of stuff that has fallen close to the black hole and is still in orbit around it. Remember things, unless they fall directly towards the center of the black hole or towards the event horizon, they're still going to have some angular momentum. You can orbit a black hole the same way the moon orbits the earth. Black holes are not like literally sucking things in. They're just gravity, right? They're just curvature of space.

You could in principle orbit a black hole forever and never fall in. But if you're in this big disk of gas and dust, you're also going to have friction. You're going to bump up against each other and some stuff is going to end up falling in. But before it does, you have this huge disk of gas and tidal forces are heating it up. So it's really hot and energetic and glowing in the x-ray. and because it's a lot of charged particles swirling around, it has its own very strong magnetic field. Like it adds to the black holes is a magnetic field or it cancels it?

Or how does it interact with the black hole? It's magnetic field itself. Yeah, great question. And that's essentially the cutting edge of our research right now. It's like, what do the black hole magnetic fields look like? What are the magnetic fields coming from the disc look like? It depends a lot on how calm or how turbulent that accretion disc is. is. Like if everything is flowing very nicely like Saturn's rings, then all those magnetic

fields will add up very nicely and they'll all contribute in the same direction. But if it's sort of chaotic like a big storm, then the magnetic fields generated by those particles might cancel each other out. We also don't really know how much the magnetic field is coming from the disk and how much is coming from the black hole itself. We can't separate those two things very easily. We can't because it's just too complicated. Yeah, we don't really understand how much magnetic field there is coming from the accretion disk because it's not something we've modeled very well. We have lots of competing theories about what the accretion disk looks like. And so to separate out the black hole's magnetic field, you have to understand the rest of the magnetic field very well.

But we've tried to do that. We've been able to take these images of the event horizon or images of the stuff near the event horizon. And recent pictures of that have used some clever tricks to try to understand what the magnetic fields look like near the black hole. Whoa, how can you do that? Well, first of all, you can't really see the event horizon, right? You only see the shadow of the black hole, which is different. Yeah, that's exactly right. We're just not seeing photons from the event horizon or anywhere near it.

In a way that lines up really, really well with predictions of general relativity. And so that's an indirect piece of evidence for black holes, another frustratingly indirect piece of evidence. But we can see this stuff, the accretion disk nearby it. That's why these photos look sort of like a big crispy cream donut, right? You have the hot gas glowing. near the accretion disk. And those photons that come from the gas that are emitted from these high-speed charged particles, they can give us some clues about the magnetic field that they're in. Because the magnetic fields will polarize these photons. It changes how the photons wiggle.

Are they wiggling this way? Are they wiggling that way? And if the magnetic fields are all nicely organized, then the polarization of those photons will be nicely organized. And if the magnetic fields are all a big hot mess, then the polarizations will all be scrambled. So they recently reanalyze the image of the black hole at the heart of the M87 galaxy to try to measure the polarization of these photons. Not just like where is it bright and where is it dim, but in which direction of those photons wiggling. And that gave them some clues about what might be happening in the accretion disk.

Which would then sort of tell you what's going on, right? Yeah, exactly. And it's really fun. They had two models of black hole accretion disc magnetic fields. One of them was called sane, stable and normal evolution. S-A-N-E and the other one is called MAD, Magnetically Arrested Disc. So it was a big competition between the Sane and the MAD groups. They're like, no, I'm sane, no, you're mad.

I mean, you've heard of crazy astronomical acronyms before, but this is like dueling crazy acronyms. I'm impressed by their coordination. Yeah, so each one of these was invented by a different group. Yeah, exactly. These are like competing theories for how the accretion disk will come together. And basically the difference between them is how turbulent is it and how coherent is it? You know, is it basically all scrambled and you don't get a strong magnetic field or is it kind of coherent and well-ordered in which case you do get a stronger build-up of the magnetic fields from the accretion disk.

Right, right. Or are they all just crazy physicists? Yeah, and so for a long time, people thought that the sane scenario was more natural, sort of weaker fields because everything would be sort of more scrambled. But what they measured is more consistent with the mad scenario that things are like nicely organized so they all add up to give more powerful magnetic fields than people suspected. Meaning that the black hole is not as chaotic as we thought it was? Yeah, it turns out to be a little bit tidy. Wait, the mad scenario is more sane than the same scenario. The mad scenario is more like our universe. It's the one where things are better organized.

Yeah. Sounds like physicists are just trying to drive with math. All right. Well, I think that sort of answers the question. Black holes do have magnetic fields. I mean, they have spin in charge, which means they have magnetic fields. You can take a black hole, stick it on your fridge. You can use it to mess up your friend's compass.

But measuring it might be a little bit tricky because it's so far away. And there's also these weird physics and dynamics going on around outside of it. That's right. We can't know what's going on inside of it. black hole, but magnetic fields give us a pretty good clue as to what's going on near a black hole, which one day might help us gain some clues about what's going on past the event horizon. Whoa. Do you think we can use magnets to see what's inside of a black hole?

Is that kind of what you're saying? Well, in general relativity, we definitely cannot. But in a quantum version with quantum gravity, there could be some correlation between the information on the surface of the event horizon itself and what's going on inside. there could be some feature, some hair to the black hole. And that could affect, for example, the radiation and the magnetic fields. And so eventually, if we get detailed enough information and better theories of quantum gravity, we might be able to see what's inside them.

That would be insane. I wouldn't be mad about it. Well, you know what they say? Wearing magnets can really help you out. Do they see that? That sounds like pseudoscience. Well, honestly, all of this black hole stuff also sounds a little. little bit like pseudoscience.

It's definitely not the final word on how any of this stuff works. It's just science in progress. I see. It's not pseudoscience. It's pre-science. All science is pretty. Everything's pre-science. Nothing's the final.

That sounds better. Protoscience. Science in action. How about that? That's right. You don't want to be a pre-scientist. All right. Well, another reminder about the incredible mysteries out there in the universe and how they're

staring us right in our television. You can see them, you can point telescopes, you can measure things about them, but all you see is pure unknowns and their magnetic personalities. That's right, there is. Well, we hope you enjoyed that. Thanks for joining us. See you next time. For more science and curiosity, come find us on social media where we answer questions and post videos. We're on Twitter, Discord, Insta, and now TikTok Thanks for listening, and remember that Daniel and Jorge Explain the Universe is a production of IHeartRadio. For more podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. December 29th, 1975, LaGuardia Airport.

The holiday rush, parents hauling luggage, kids gripping their new. Christmas toys. Then everything changed. There's been a bombing at the TWA terminal. Just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged. Terrorism. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Why are TSA rules so confusing? You got a hood of you. I'll take it off. I'm Mani. I'm Noah.

This is Devin. And we're best friends and journalists with a new podcast called No Such Thing, where we get to the bottom of questions like that. Why are you screaming? I can't expect what to do. Now, if the rule was the same, go off on me. I deserve it. You know, lock him up.

Listen to No Such Thing on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. No Such Thing. I'm Dr. Joy Hardin Bradford, host of the Therapy for Black Girls podcast. I know how old. overwhelming it can feel if flying makes you anxious. In session 418 of the Therapy for Black Girls podcast, Dr. Angela Neil Barnett and I discuss flight anxiety.

What is not a norm is to allow it to prevent you from doing the things that you want to do, the things that you were meant to do. Listen to Therapy for Black Girls on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. This is an IHeart podcast.