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How can we look for magnetic monopoles? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Daniel, does being a scientists require a lot of travel?
• 0:12
  Speaker 2: Yeah, you know, conferences and meetings and all that kind
• 0:15
  Speaker 2: of stuff.
• 0:16
  Speaker 1: But that's just talking about science. What about actually doing science?
• 0:20
  Speaker 1: And you need to go somewhere into the lab or
• 0:22
  Speaker 1: out into the field.
• 0:23
  Speaker 2: Yeah, you got to do that. Also, I'm pretty lucky
• 0:26
  Speaker 2: that the collider I work out is in a pretty
• 0:28
  Speaker 2: beautiful spot in Switzerland.
• 0:30
  Speaker 1: But do you actually have to go there, like you
• 0:32
  Speaker 1: have to press buttons or fix the machine?
• 0:35
  Speaker 2: Who else is going to hit that big red button
• 0:37
  Speaker 2: in the control room if not me? Man?
• 0:38
  Speaker 1: Or did you just go? Are of talk?
• 0:40
  Speaker 2: There's definitely a lot of talking and coffee drinking, But yeah,
• 0:43
  Speaker 2: somebody has to actually build a thing and make it run.
• 0:46
  Speaker 2: So people got to be there in person.
• 0:47
  Speaker 1: And I guess you got to talk to them, right,
• 0:50
  Speaker 1: I'm just wondering, an why do you actually have to
• 0:53
  Speaker 1: go to Switzerland?
• 0:53
  Speaker 2: Yeah, some of us have to actually go to build
• 0:55
  Speaker 2: a thing. We built part of the detector and the
• 0:57
  Speaker 2: readout systems that gather the data. We're responsible for making
• 1:01
  Speaker 2: it work, and you got to be there when it breaks.
• 1:03
  Speaker 1: M Now, is that the best physics location to get
• 1:07
  Speaker 1: stationed at?
• 1:08
  Speaker 2: I think it's one of the top ones. It's definitely
• 1:10
  Speaker 2: better than the suburbs of Chicago, where we worked more recently.
• 1:13
  Speaker 1: Hey, what's wrong with Chicago?
• 1:16
  Speaker 2: Chicago's awesome. The suburbs a little bit less exciting. But
• 1:19
  Speaker 2: there's an experiment on the Mediterranean. So those people basically
• 1:23
  Speaker 2: work on the French Riviera.
• 1:25
  Speaker 1: Nice. Do they work in speedos and swimsuits or not?
• 1:29
  Speaker 1: Since it's the French Priviera.
• 1:31
  Speaker 2: I don't think you want to visualize physicists and speedos.
• 1:33
  Speaker 1: Yeah, let's not do that.
• 1:35
  Speaker 2: On the other extreme, our experiments at the South Pole.
• 1:38
  Speaker 1: Ooh, that sounds super cool.
• 1:41
  Speaker 2: It's a little too cool for my tastes.
• 1:43
  Speaker 1: That sounds awesome, somewhere I want to go at least
• 1:45
  Speaker 1: once in my life. Hi am Jeha May, cartoonist and
• 2:02
  Speaker 1: the author of Oliver's Great Big Universe.
• 2:05
  Speaker 3: Hi.
• 2:05
  Speaker 2: I'm Daniel. I'm a particle physicist and a professor at
• 2:08
  Speaker 2: uc Ervine, and I'd be happy to die without ever
• 2:11
  Speaker 2: going to the South Pole.
• 2:12
  Speaker 1: Well, I guess you don't want to go to the
• 2:13
  Speaker 1: South Pool to die or have those two coin side.
• 2:17
  Speaker 1: But if you had the opportunity, when did you want
• 2:20
  Speaker 1: to go?
• 2:20
  Speaker 2: I actually have had the opportunity, but I said no
• 2:23
  Speaker 2: thank you.
• 2:24
  Speaker 1: You said no thank you.
• 2:26
  Speaker 2: I've said no thank you. Why the South Pole seems
• 2:28
  Speaker 2: kind of cold and uncomfortable. I'm not that into unpleasant travel,
• 2:32
  Speaker 2: same reason I don't really want to go to space.
• 2:35
  Speaker 1: Yeah, well I think space is a little bit colder
• 2:37
  Speaker 1: than the South Pole. Yeah, don't you want to go
• 2:39
  Speaker 1: for the adventure? See some penguins, some live penguins, not
• 2:43
  Speaker 1: in a zoo.
• 2:43
  Speaker 2: I think when I was younger, I was more into
• 2:45
  Speaker 2: adventure travel than I am now.
• 2:47
  Speaker 1: Now you're more into couch adventures.
• 2:51
  Speaker 2: I'm less into discomfort now than I used to be.
• 2:54
  Speaker 1: But anyways, welcome to our podcast, Daniel and Jorge Explain
• 2:56
  Speaker 1: the Universe, a production of our Heart Radio.
• 2:59
  Speaker 2: A mentally adventure, a way to travel the entire universe
• 3:03
  Speaker 2: and think about everything that's happening out there, how things
• 3:06
  Speaker 2: work at the tiny particle level, how things work at
• 3:09
  Speaker 2: the galactic scale, and everything in between. Physics is our
• 3:13
  Speaker 2: way of exploring this vast universe and trying to make
• 3:16
  Speaker 2: sense of it, and our job on the podcast is
• 3:18
  Speaker 2: to help you make sense of it as well.
• 3:20
  Speaker 1: That's right. We live in an amazing cosmos and we
• 3:23
  Speaker 1: are just tourists making our way through it, observing all
• 3:26
  Speaker 1: the sites and learning all of the languages that it has,
• 3:29
  Speaker 1: and eating all the foods it has to offer.
• 3:31
  Speaker 2: We're not tourists to this cosmos. We live here, man,
• 3:34
  Speaker 2: We are home here. We're just trying to understand our
• 3:37
  Speaker 2: own context. It's not like we came here from some
• 3:39
  Speaker 2: other part of the multiverse to poke in prad and
• 3:41
  Speaker 2: take pictures.
• 3:42
  Speaker 1: Well, we're tourists in the sense that we're early here
• 3:44
  Speaker 1: for a very short amount of time.
• 3:46
  Speaker 2: And we hope that in that time we can help
• 3:47
  Speaker 2: unravel some of the deep questions of the nature of
• 3:50
  Speaker 2: the universe.
• 3:51
  Speaker 1: Yes, because there are a lot of amazing things out
• 3:53
  Speaker 1: there for us to ask questions about and to explore
• 3:56
  Speaker 1: and to wonder why they exist.
• 3:58
  Speaker 2: Unfortunately, we can't mostly go out there to explore the universe.
• 4:01
  Speaker 2: We have to just see what comes to us here
• 4:04
  Speaker 2: on Earth. In this tiny little corner of the universe.
• 4:07
  Speaker 2: We can actually gather an incredible amount of information based
• 4:10
  Speaker 2: on all the particles that do arrive here on Earth,
• 4:13
  Speaker 2: the photons, the neutrinos, and sometimes the odd ball particles.
• 4:17
  Speaker 1: Wait, we can't just put physicists in a spaceship and
• 4:20
  Speaker 1: send them out to other planets.
• 4:21
  Speaker 2: If you want to fund that, I bet you'll have
• 4:22
  Speaker 2: lots of volunteer physicists. Just not me.
• 4:27
  Speaker 1: What if they have nice chocolates like they do in Switzerland.
• 4:29
  Speaker 2: I don't think chocolate is enough to counterbalance the discomfort, because,
• 4:33
  Speaker 2: after all, you can still get pretty nice chocolates without
• 4:35
  Speaker 2: getting in the spaceship.
• 4:36
  Speaker 1: How do you know, maybe they taste better in space.
• 4:38
  Speaker 2: We'll let someone else do that experiment and report back.
• 4:41
  Speaker 1: It would be chocolates that are out as this world.
• 4:43
  Speaker 2: Cosmic chocolates. Well, we can do lots of cool experiments
• 4:47
  Speaker 2: just here on Earth, and not just building telescopes to
• 4:51
  Speaker 2: capture photons or neutrinos. Sometimes we can actually use the
• 4:55
  Speaker 2: Earth itself to see these particles.
• 4:58
  Speaker 1: Yeah, the Earth is a big place and it catches
• 5:00
  Speaker 1: a lot of stuff from space, from other parts of
• 5:03
  Speaker 1: the galaxy, from other parts of the universe, and we
• 5:05
  Speaker 1: can use it to try to catch things that maybe
• 5:07
  Speaker 1: we haven't seen before.
• 5:09
  Speaker 2: Some of the telescopes that we build actually rely on
• 5:12
  Speaker 2: the Earth being there to induce the particles to interact
• 5:15
  Speaker 2: to reveal themselves without the Earth. Some of these particle
• 5:19
  Speaker 2: telescopes wouldn't even work.
• 5:21
  Speaker 1: So today on the podcast, we'll be asking the question
• 5:28
  Speaker 1: how can we look for magnetic monopoles?
• 5:32
  Speaker 2: Now?
• 5:32
  Speaker 1: Is this related to monopoly the game or the capitalism concept?
• 5:38
  Speaker 2: I think it's somewhat related to capitalism. Yeah, having just
• 5:41
  Speaker 2: like one source of chocolate, somebody has a monopoly on chocolate.
• 5:44
  Speaker 2: Monopoles are also like a source of charge.
• 5:48
  Speaker 1: Okay, it's a bit of a stretch. What are physicists
• 5:53
  Speaker 1: in this stretched analogy? Here are you the boot? Are
• 5:56
  Speaker 1: you the little car? Are you the top hat?
• 5:58
  Speaker 2: We are buying it up. We are trying to purchase
• 6:01
  Speaker 2: knowledge about the universe.
• 6:03
  Speaker 1: Hopefully you don't land and go to jail, do not
• 6:06
  Speaker 1: pass go.
• 6:06
  Speaker 2: I will happily go to physics jail if that's what's
• 6:08
  Speaker 2: required to unravel the mysteries of the universe.
• 6:11
  Speaker 1: I guess researches are a little bit like drawing chance cards.
• 6:14
  Speaker 2: Oh, it definitely is. I've had so many conversations with
• 6:16
  Speaker 2: students where they've been like, I've been working for sixty
• 6:18
  Speaker 2: hours a week for a year and haven't gotten anywhere.
• 6:21
  Speaker 2: I'm like, number one, don't work sixty hours a week.
• 6:24
  Speaker 2: Number two, there's no guarantee that time spent means progress made.
• 6:28
  Speaker 2: There's so much randomness in research.
• 6:30
  Speaker 1: And number three, you should be working eighty hours a week.
• 6:33
  Speaker 2: No, you should definitely not be working eighty hours a week.
• 6:37
  Speaker 2: You got to take care of your people's mental health. Man.
• 6:39
  Speaker 1: But yeah, I guess it's not maybe related to the
• 6:41
  Speaker 1: board game. I'm guessing it's maybe related to magnetism and
• 6:44
  Speaker 1: magnetic polls exactly.
• 6:45
  Speaker 2: It has to do with deep questions about where charge
• 6:48
  Speaker 2: comes from in electricity, where magnetism comes from in magnetism,
• 6:53
  Speaker 2: how the two are connected, why we have quantized amounts
• 6:57
  Speaker 2: of electric charge in this universe, and why we have
• 6:59
  Speaker 2: quantized amounts of electric charge in this universe. It's sort
• 7:03
  Speaker 2: of like a big open question in particle physics.
• 7:06
  Speaker 1: Yeah, we're gonna jump into what a magnetic monopole is,
• 7:10
  Speaker 1: but first we were wondering how many people out there
• 7:12
  Speaker 1: had heard of this concept and thought about the idea
• 7:15
  Speaker 1: of how to look for them.
• 7:16
  Speaker 2: So thanks very much to everybody who answers these questions.
• 7:19
  Speaker 2: If you would like to hear your voice on the
• 7:21
  Speaker 2: podcast answering the Question of the Day, please write to
• 7:24
  Speaker 2: me two questions at Danielandjorge dot com.
• 7:27
  Speaker 1: We think about it for a second. How do you
• 7:29
  Speaker 1: think we can look for magnetic monopoles? What people had
• 7:33
  Speaker 1: to say, I have no idea what that means. But
• 7:36
  Speaker 1: maybe yeah, if it was a monopole, it messed with
• 7:39
  Speaker 1: other magnetic fields, and so we could look for disturbances
• 7:42
  Speaker 1: and die poles.
• 7:44
  Speaker 3: First of all, I would ask who it really exists.
• 7:47
  Speaker 2: I know you have a podcast on that, but I
• 7:48
  Speaker 2: haven't listened to it yet. I actually don't know.
• 7:53
  Speaker 3: I really don't know. Looking forward to hear from it
• 7:55
  Speaker 3: from you, I.
• 7:56
  Speaker 1: Would say by closing one eye.
• 7:58
  Speaker 4: But I think they may not this because the needs
• 8:01
  Speaker 4: to rebalance the nature, and this just seems unbalanced.
• 8:04
  Speaker 5: Where are monocles?
• 8:07
  Speaker 4: I don't know what a monopole is, so I don't know.
• 8:12
  Speaker 4: Maybe something related to like the magnetic field of Earth,
• 8:15
  Speaker 4: just for the universe, Like maybe the universe has a
• 8:17
  Speaker 4: joint magnetic field. I don't know. I can't wait to
• 8:20
  Speaker 4: search it up.
• 8:21
  Speaker 5: I'm not sure how we could look for magnetic monopoles.
• 8:24
  Speaker 5: If they're large, then maybe we could look at how
• 8:29
  Speaker 5: things act around them out in space. But if they're
• 8:33
  Speaker 5: really small, I have no idea.
• 8:36
  Speaker 3: I wouldn't even know where to look, never mind how
• 8:39
  Speaker 3: to look. I believe classical electromagnetism doesn't allow for magnetic monopoles,
• 8:45
  Speaker 3: but maybe there is some kind of quantum weirdness that
• 8:51
  Speaker 3: at least theoretically predicts them. But I don't have a
• 8:56
  Speaker 3: clue about how to find.
• 8:59
  Speaker 1: All right, we got to tell comedians here in the batch.
• 9:02
  Speaker 1: Somebody say, maybe we can look for monopoles by wearing monocles.
• 9:06
  Speaker 2: The guy in Monopoly wears a monocole, after all, doesn't he?
• 9:09
  Speaker 1: Oh, yes, it's all there. It was a hidden sign.
• 9:12
  Speaker 2: You don't have a monopoly on jokes and physics.
• 9:14
  Speaker 1: Apparently apparently not, because two people have brought up this joke.
• 9:19
  Speaker 1: Somebody said you can also look for them by closing
• 9:21
  Speaker 1: one eye. But which I I guess that's the question.
• 9:25
  Speaker 1: Maybe you have to roll the die.
• 9:26
  Speaker 2: Depends if it's a left or right handed monopole.
• 9:28
  Speaker 1: I suppose monopoles are handed. There's handedness and magnetism.
• 9:32
  Speaker 2: If it has spin, then it's going to have handedness absolutely.
• 9:35
  Speaker 1: M All right, well let's dig into this concept. Maybe
• 9:38
  Speaker 1: a lot of people haven't heard what a monopole is.
• 9:40
  Speaker 1: A magnetic monopole is, so Daniel explained to us what
• 9:43
  Speaker 1: is a magnetic monopole.
• 9:44
  Speaker 2: A magnetic monopole is easiest to understand if you first
• 9:47
  Speaker 2: get your mind around what an electric monopole is. If
• 9:50
  Speaker 2: you could understand what a monopole is in electricity, then
• 9:53
  Speaker 2: we can understand what it is in magnetism. And in electricity.
• 9:57
  Speaker 2: A monopole is pretty simple. It's just something that has
• 9:59
  Speaker 2: an o overall charge, like an electron. Electron has negative charge.
• 10:03
  Speaker 2: It's a source of charge, and the proton has a
• 10:07
  Speaker 2: positive charge. It's a source of charge. You add up
• 10:10
  Speaker 2: all the charge on the object. It's either positive or
• 10:12
  Speaker 2: it's negative. It's not zero, and that creates a particular
• 10:16
  Speaker 2: kind of field. Gases law for electricity tells you, for example,
• 10:19
  Speaker 2: that the electric field through a surface depends on the
• 10:22
  Speaker 2: total amount of charge in the volume. So a monopole
• 10:25
  Speaker 2: and electricity is just something that has an overall charge
• 10:29
  Speaker 2: to it.
• 10:30
  Speaker 1: So, as you said, like an electron is maybe the
• 10:32
  Speaker 1: ultimate negative electric monopole, right, Like it's just the point particle.
• 10:37
  Speaker 1: It's just a little point in space that has a
• 10:39
  Speaker 1: negative charge to it, and it looks negative from all
• 10:42
  Speaker 1: directions exactly.
• 10:44
  Speaker 2: And the atom is the combination of the proton and
• 10:46
  Speaker 2: the electron. It's overall neutral. It has no overall charge,
• 10:50
  Speaker 2: so it's not a monopole, but it is a dipole
• 10:53
  Speaker 2: because the positive charge and the negative charge are not
• 10:56
  Speaker 2: exactly on top of each other. They don't totally cancel out,
• 10:59
  Speaker 2: so if you're closer to one than the other, you'll
• 11:01
  Speaker 2: still feel an electric field. But that's a dipole field.
• 11:04
  Speaker 2: It's a field that comes from something that has a
• 11:06
  Speaker 2: positive and a negative charge. Right, Dipole means two, so
• 11:10
  Speaker 2: it comes from something where the charge is overall zero,
• 11:13
  Speaker 2: but it has a distribution. So monopolsm that has an
• 11:16
  Speaker 2: overall charge, like the electron of the proton. A dipole
• 11:19
  Speaker 2: has no overall charge, but the distribution of charge inside
• 11:23
  Speaker 2: that neutral object still gives you an electric field, a
• 11:26
  Speaker 2: dipole field.
• 11:27
  Speaker 1: I think what you mean is like the nucleus of
• 11:29
  Speaker 1: an atom is neutral because there are or at least
• 11:31
  Speaker 1: it's positive, right, because it has protons and neutrons in it,
• 11:35
  Speaker 1: And then the outer part of the atom has the electron,
• 11:38
  Speaker 1: which is negative, and the electron is going around the nucleus,
• 11:42
  Speaker 1: so at any given time there's one side of the
• 11:45
  Speaker 1: atom that's more negative than the other side, right, But
• 11:48
  Speaker 1: it's sort of like it's electron is flying around, right,
• 11:51
  Speaker 1: So it's changing for an atom all the time, exactly.
• 11:53
  Speaker 2: And if you're really far away from the atom, then
• 11:55
  Speaker 2: the distance between the electron and the proton doesn't really matter.
• 11:58
  Speaker 2: You can think of them as on top of each other,
• 12:00
  Speaker 2: and the dipole field goes to zero very quickly. But
• 12:03
  Speaker 2: as you get close to it, then that does matter,
• 12:05
  Speaker 2: and so there is an electric field that doesn't cancel out. Right,
• 12:08
  Speaker 2: The electric field of the electron and the proton don't
• 12:11
  Speaker 2: cancel out, so you feel a dipole field.
• 12:13
  Speaker 1: Meaning like if you're really close to the atom, super
• 12:16
  Speaker 1: duper close to the and you're like an electron, for example,
• 12:18
  Speaker 1: you might be pushed in one direction more than the other.
• 12:21
  Speaker 2: Yeah, exactly. You can imagine a field from the electron
• 12:24
  Speaker 2: and a field from the proton. If you're really far away,
• 12:26
  Speaker 2: then they're basically canceling each other out. But if you're
• 12:29
  Speaker 2: really close to the two of them, you're going to
• 12:31
  Speaker 2: be closer to one than the other by a big
• 12:33
  Speaker 2: fraction and they're not going to cancel out. So that's
• 12:35
  Speaker 2: a dipole field.
• 12:36
  Speaker 1: So monopoles do exist, like an electron is a monopole,
• 12:39
  Speaker 1: isn't it.
• 12:39
  Speaker 2: Yes, an electric monopole does exist. You can have a
• 12:42
  Speaker 2: piece of matter with an overall charge to it that
• 12:44
  Speaker 2: creates this monopole field, right, just a very simple field.
• 12:48
  Speaker 2: And dipole fields exist in electricity, in quadrupole fields and
• 12:52
  Speaker 2: octopole fields. Actually, it's part of this multipole expansion. If
• 12:56
  Speaker 2: you like to think about vector spaces and linear algebra,
• 12:58
  Speaker 2: you can break any yield and the expansion of these
• 13:01
  Speaker 2: different poles. The first term is the monopole, then the dipole,
• 13:04
  Speaker 2: then the quadrupole, et cetera, et cetera. But conceptually you
• 13:06
  Speaker 2: can think about the monopole is coming from something that
• 13:09
  Speaker 2: has an overall charge.
• 13:11
  Speaker 1: All right, so that's an electric monopole. I'm guessing maybe
• 13:14
  Speaker 1: a magnetic monopole is different.
• 13:16
  Speaker 2: A magnetic monopole is the exact analog, except use magnetic
• 13:19
  Speaker 2: charge instead of electric charge.
• 13:21
  Speaker 1: Wait wait, wait, wait wait, what's the difference between magnetic
• 13:24
  Speaker 1: charge and electric charge?
• 13:25
  Speaker 3: All right?
• 13:25
  Speaker 1: I thought that was the same thing.
• 13:26
  Speaker 2: Well, they're very tightly connected because we've unified electricity and
• 13:29
  Speaker 2: magnetism into one overall force called electromagnetism. Right, But there
• 13:34
  Speaker 2: are two different parts of it. There's electricity and there's magnetism.
• 13:37
  Speaker 2: There are different components of electromagnetism.
• 13:39
  Speaker 1: Like what's the difference, Like, if two electrons are repelled
• 13:42
  Speaker 1: from each other, aren't they pushing away from each other
• 13:45
  Speaker 1: using the electromagnetic force?
• 13:48
  Speaker 2: Yes, absolutely they are, and there's components to that which
• 13:51
  Speaker 2: are electric, like this the Colombic repulsion just from the
• 13:54
  Speaker 2: electric charges. But if they're in motion, then one of
• 13:57
  Speaker 2: them can be generating a magnetic field, and that magnetic
• 13:59
  Speaker 2: field and also turn the other electron for example, So
• 14:03
  Speaker 2: there's both electric and magnetic components to how two electrons interact.
• 14:07
  Speaker 1: Hmmm, So I guess you would maybe have to dig
• 14:09
  Speaker 1: into the equations, But is there a way to sort
• 14:11
  Speaker 1: of explain the difference between magnetism and electricity, Like.
• 14:14
  Speaker 2: Magnetism has a different set of charges. We call them
• 14:16
  Speaker 2: north and south, right, So you can have a magnet
• 14:19
  Speaker 2: that has a north and a south and you know
• 14:20
  Speaker 2: that if you bring the north end close to another
• 14:23
  Speaker 2: north end, it repels two north's repel and two south repels.
• 14:26
  Speaker 2: So these are the magnetic charges, the north and the
• 14:28
  Speaker 2: south charges.
• 14:30
  Speaker 1: But aren't those like emergent properties, Like aren't the all
• 14:33
  Speaker 1: just made out of electrons, which are monopoles.
• 14:36
  Speaker 2: Yes, exactly, All the magnetic fields in the universe are dipoles.
• 14:39
  Speaker 2: All of magnetism is generated by electric monopoles, either moving
• 14:45
  Speaker 2: charges or quantum spin. So all the magnetic fields we
• 14:48
  Speaker 2: have in the universe are generated by electric monopoles. If
• 14:52
  Speaker 2: there are magnetic monopoles, then those would also generate pure
• 14:56
  Speaker 2: magnetic fields, like a pure north field or pure south field,
• 15:00
  Speaker 2: not a dipole field where you have like a north
• 15:02
  Speaker 2: on one end and a south on the other. If
• 15:04
  Speaker 2: you have a bar magnet, for example, it has a
• 15:06
  Speaker 2: north on one side and a south on the other.
• 15:08
  Speaker 2: You try to crack it in half, You're not going
• 15:10
  Speaker 2: to get a pure north on one side and a
• 15:11
  Speaker 2: pure south on the other. You're going to end up
• 15:13
  Speaker 2: with two bar magnets, each of which is a dipole
• 15:15
  Speaker 2: with a north and a south. As far as we know,
• 15:18
  Speaker 2: there are no pure magnetic charges out there, no like
• 15:22
  Speaker 2: particles that just have a north or particles that just
• 15:24
  Speaker 2: have a south. That would be a magnetic monopole, the
• 15:27
  Speaker 2: equivalent of like an electron, which is an electric monopole.
• 15:31
  Speaker 1: Okay, so I guess I'm still trying to wrap my
• 15:33
  Speaker 1: head around this difference, because I always thought it was
• 15:35
  Speaker 1: maybe the same thing. So you're saying, like, if I
• 15:38
  Speaker 1: have an electron and I spin it, it's going to
• 15:40
  Speaker 1: create a dipole.
• 15:42
  Speaker 2: It's going to create a magnetic dipole. Right, It's going
• 15:44
  Speaker 2: to have a north and a south. So electrons have
• 15:47
  Speaker 2: quantum spin. They don't literally spin in the way that
• 15:50
  Speaker 2: like a top spins, but their quantum spin does generate
• 15:53
  Speaker 2: a little magnetic field. But that magnetic field has a
• 15:56
  Speaker 2: north and a south. It's not just a north or
• 15:58
  Speaker 2: not just a south.
• 15:59
  Speaker 1: Right. But I guess the question is, like, what is
• 16:01
  Speaker 1: a magnetic field.
• 16:02
  Speaker 2: A magnetic field is something that's generated either by a
• 16:04
  Speaker 2: magnetic monopole or induced by an electric current, right, And
• 16:08
  Speaker 2: electric currents can only induce magnetic dipoles. They can't induce
• 16:12
  Speaker 2: magnetic monopoles.
• 16:13
  Speaker 1: I guess what I mean is like to the labors,
• 16:15
  Speaker 1: and how would you define a magnetic.
• 16:16
  Speaker 2: Field in the same way that you think about electric fields.
• 16:19
  Speaker 2: These are sort of theoretical concepts that explain how two
• 16:22
  Speaker 2: particles push on each other. So how does an electron
• 16:26
  Speaker 2: push on another electron? We say it's using the electric field.
• 16:29
  Speaker 2: Really that's just our way of saying, this is what
• 16:32
  Speaker 2: two electrons do to each other. Magnetic fields are similar,
• 16:35
  Speaker 2: the two are very closely paired. Electric fields and magnetic
• 16:38
  Speaker 2: fields very tightly coupled. But a magnetic field is different
• 16:40
  Speaker 2: from an electric field, right, It does different things. It's
• 16:43
  Speaker 2: generated in different ways. It applies different forces to charges,
• 16:47
  Speaker 2: or a magnetic field does different things to magnetic charges
• 16:50
  Speaker 2: than it does to electric charges. All these things are
• 16:52
  Speaker 2: described by Maxwell's equations, but in the end it's just descriptive, right,
• 16:56
  Speaker 2: Like we see these things happening to electrons and to
• 16:58
  Speaker 2: bar magnets and to other particles in the universe, we
• 17:01
  Speaker 2: try to boil them down into as compact the description
• 17:04
  Speaker 2: as possible, and then we come up with this story
• 17:06
  Speaker 2: that we tell ourselves about what's happening, and that story
• 17:09
  Speaker 2: includes fields. Are those fields real and physical things that
• 17:12
  Speaker 2: are out there in the universe. We can't like see
• 17:14
  Speaker 2: them directly, We only see their impact on other particles.
• 17:18
  Speaker 2: So when you ask me, like, well, what is a field, Well,
• 17:20
  Speaker 2: it's sort of a theoretical philosophical construct that explains the
• 17:24
  Speaker 2: motions of the particles that we see. They seem to
• 17:26
  Speaker 2: follow certain rules and those are best explained by these
• 17:29
  Speaker 2: fields that we've built up in our minds.
• 17:31
  Speaker 1: I guess maybe I think what you're saying is that
• 17:32
  Speaker 1: a field is sort of like an idea that tells you, like,
• 17:36
  Speaker 1: if I put an electron in here relative to this
• 17:39
  Speaker 1: other electron, it's going to field a repulsive electric force
• 17:43
  Speaker 1: in that direction. Or if I put it over here
• 17:45
  Speaker 1: and this other location is going to feel the force
• 17:48
  Speaker 1: in a different direction by a different amount. And so
• 17:50
  Speaker 1: maybe a magnetic field is sort of the same, Like
• 17:53
  Speaker 1: if I have a magnetic field and I throw an
• 17:56
  Speaker 1: electron add it, it's going to do different things depending
• 17:59
  Speaker 1: on whether it's you know, flying close to the north
• 18:02
  Speaker 1: side of this magnetic field, or it's the south side.
• 18:05
  Speaker 2: Right, Yeah, that's right. These fields were invented as a
• 18:08
  Speaker 2: concept to explain action at a distance, like how did
• 18:11
  Speaker 2: two electrons push on each other if they're not actually touching,
• 18:14
  Speaker 2: And so you create this field concept. Say an electron
• 18:17
  Speaker 2: creates a field through space, and that field can push
• 18:19
  Speaker 2: on the other electronic transfers momentum to the other electron. So, yeah,
• 18:24
  Speaker 2: magnetic fields have different rules, and these are all described
• 18:26
  Speaker 2: by Maxwell's equations. You throw an electron through a magnetic field,
• 18:30
  Speaker 2: it's going to curve. You throw an electron through an
• 18:32
  Speaker 2: electric field, it will get accelerated in some direction to
• 18:35
  Speaker 2: the rules are a little.
• 18:36
  Speaker 1: Bit different, So I guess the way the universe works,
• 18:39
  Speaker 1: it's just kind of weird thing. Like if you take
• 18:41
  Speaker 1: an electron and you spin it, it creates a field
• 18:44
  Speaker 1: around it, or like it hasn't affect on the things
• 18:47
  Speaker 1: around it, so that if you throw another electron near
• 18:50
  Speaker 1: that spinning electron, then it's going to curve a certain way,
• 18:52
  Speaker 1: depending on whether you're going like in the direction or
• 18:55
  Speaker 1: near its north and south poles. That's just the weird
• 18:58
  Speaker 1: thing that happens, right.
• 18:59
  Speaker 2: Yeah, I guess you could say allophysics is explaining the
• 19:02
  Speaker 2: weird things that happen. And if you're not really comfortable
• 19:05
  Speaker 2: with the idea of like quantum spin, you can also
• 19:07
  Speaker 2: just take electrons and run them in a circle. You
• 19:09
  Speaker 2: take a wire and you coil it and you pass
• 19:12
  Speaker 2: a current through it. That's electrons moving in a circle.
• 19:14
  Speaker 2: That will generate a magnetic field, which will bend the
• 19:17
  Speaker 2: path of other electrically charged particles. But the key thing
• 19:21
  Speaker 2: is that all of the magnetic fields we've seen in
• 19:23
  Speaker 2: the universe are generated by the motion of electric charges
• 19:27
  Speaker 2: or the spinning of those electric charges, and those generate dipoles,
• 19:30
  Speaker 2: a combination of a north and a south. In principle,
• 19:34
  Speaker 2: by symmetry, you might imagine, why aren't there particles that
• 19:37
  Speaker 2: can generate a pure north or pure south the way
• 19:40
  Speaker 2: an electron can generate a pure positive or negatively charged
• 19:43
  Speaker 2: electric field.
• 19:44
  Speaker 1: Well, it kind of seems like maybe there isn't such
• 19:47
  Speaker 1: a thing as a magnetic charge. Is there such a
• 19:50
  Speaker 1: thing as a magnetic charge? Isn't it more like? I
• 19:52
  Speaker 1: don't know, but maybe does it maybe have more to
• 19:54
  Speaker 1: do with the direction that these electrons are spinning, Like
• 19:59
  Speaker 1: is there such a thing as a magnetic charge? Or
• 20:01
  Speaker 1: is it just a direction that electrons are spinning.
• 20:04
  Speaker 2: There's such a thing as the polarity of a magnetic field, right,
• 20:06
  Speaker 2: Magnetic fields have a north and a south. When you
• 20:08
  Speaker 2: take two bar magnets, you try to push them together,
• 20:11
  Speaker 2: you flip one over, they'll repel instead of a tract. Right,
• 20:13
  Speaker 2: So there's definitely a direction to these magnetic fields. They
• 20:17
  Speaker 2: have a charge to them in that sense the same way, like,
• 20:19
  Speaker 2: what's the difference between a positive and negative charge? It
• 20:22
  Speaker 2: really is just defined by the effect of a field
• 20:24
  Speaker 2: on it. What's the difference between an electron and an
• 20:27
  Speaker 2: anti electron. They have a different charge, which means you
• 20:29
  Speaker 2: put them in an electric field that go in different directions.
• 20:32
  Speaker 2: That's sort of what charge means. And so in the
• 20:34
  Speaker 2: same way, there's two different kinds of magnetic fields. This's
• 20:38
  Speaker 2: the north and the south kind. We've only ever seen
• 20:40
  Speaker 2: them paired together. The way, for example, you can make
• 20:42
  Speaker 2: a dipole out of a positive and negative charge, putting
• 20:45
  Speaker 2: them together to have something an overall neutral but still
• 20:48
  Speaker 2: has an effect on stuff nearby because it has a
• 20:50
  Speaker 2: dipole field. We've only ever seen a magnetic dipole field.
• 20:54
  Speaker 2: So you're asking like, is there really a magnetic charge, Well,
• 20:57
  Speaker 2: there's a directionality to the magnetic field. We've never I've
• 21:00
  Speaker 2: seen a particle that has a pure magnetic charge by itself.
• 21:04
  Speaker 2: So in that sense, everything is generated from the electric charge.
• 21:07
  Speaker 2: But that doesn't mean that they don't exist. And actually
• 21:10
  Speaker 2: it would be theoretically beautiful and kind of symmetric if
• 21:13
  Speaker 2: they did exist. It would complete these equations in this
• 21:16
  Speaker 2: sort of very nice way.
• 21:18
  Speaker 1: I guess maybe what I'm trying to say is that
• 21:19
  Speaker 1: like an electron, right has electric charge and it has
• 21:23
  Speaker 1: a spin direction, but it doesn't really have like a
• 21:26
  Speaker 1: magnetic label or value or quantum quantity.
• 21:30
  Speaker 2: To it, right, it does not, You're correct.
• 21:32
  Speaker 1: The magnetic field and it's magnetic field direction comes from
• 21:36
  Speaker 1: the charge and the spin and in the same way
• 21:38
  Speaker 1: like for your fridge magnet. It's not like it's a
• 21:41
  Speaker 1: property of the things in it. It's just that the
• 21:43
  Speaker 1: electrons inside of that magnet are all spinning in a
• 21:46
  Speaker 1: certain way.
• 21:46
  Speaker 3: Right.
• 21:46
  Speaker 2: Yes, all magnetism we know of in the whole universe
• 21:49
  Speaker 2: are just dipoles or combinations of north and south, which
• 21:52
  Speaker 2: are generated from the electric charges. Fundamentally, but that doesn't
• 21:56
  Speaker 2: mean the only thing that can happen. It might be
• 21:59
  Speaker 2: that there are parts of out there that have a
• 22:02
  Speaker 2: magnetic charge the way the electron has an electric charge.
• 22:05
  Speaker 2: That would be a magnetic monopole. That's the question.
• 22:08
  Speaker 1: All right, Well, let's dig into that question a little
• 22:10
  Speaker 1: bit more, and also how physinessists are trying to look
• 22:14
  Speaker 1: for these monopolies in nature. But first let's take a
• 22:17
  Speaker 1: quick break. All Right, we're talking about a very magnetic
• 22:31
  Speaker 1: subject here today, magnetic monopoles and whether they exist or
• 22:35
  Speaker 1: can exist in how we're actually looking for them now, Daniel,
• 22:39
  Speaker 1: I guess I'm kind of confused here. It seems like
• 22:41
  Speaker 1: magnetic fields are just kind of what happens when you
• 22:43
  Speaker 1: take an electric charge and you spin it right, either
• 22:46
  Speaker 1: quantum spin or you actually like physically make an electron
• 22:49
  Speaker 1: go around in a circle. You create a magnetic field.
• 22:51
  Speaker 1: And a magnetic field is sort of defined by that
• 22:53
  Speaker 1: right by its direction, Like if you spin it, Let's
• 22:56
  Speaker 1: say I spin an electron clockwise, it's going to generate.
• 23:00
  Speaker 1: Can I feel in like going up or going down right?
• 23:03
  Speaker 1: And so I feel like going up or down automatically
• 23:07
  Speaker 1: gives you a diepole because you need an up and
• 23:09
  Speaker 1: a down to the fine a direction, And so I
• 23:12
  Speaker 1: don't even know what a monopole would look like, Like
• 23:15
  Speaker 1: how can something have the same direction from all sides.
• 23:17
  Speaker 2: Same way an electric field does? You have an electron
• 23:19
  Speaker 2: in empty space that has an electric field which you
• 23:22
  Speaker 2: know either points towards the electron or away from the
• 23:25
  Speaker 2: electron in every direction simultaneously. Right, there's a total overall
• 23:29
  Speaker 2: charge there. It's like a source of electric charge.
• 23:33
  Speaker 1: So then how would it act on something else? Like
• 23:35
  Speaker 1: let's say that a mono magnetic monopole did exist. Let's
• 23:38
  Speaker 1: say I have one in my hand, and now I
• 23:41
  Speaker 1: have a magnet on my other hand with a north
• 23:44
  Speaker 1: and a south pole. What would this thing do? It
• 23:46
  Speaker 1: would only attract the north part of my magnet or
• 23:49
  Speaker 1: something like that.
• 23:49
  Speaker 2: If you're holding a north charge and then you have
• 23:52
  Speaker 2: another north charge, they would repel. If you have a
• 23:55
  Speaker 2: south charge, they would attract. You can apply all of
• 23:57
  Speaker 2: your intuition from electricity because we think the things are
• 24:00
  Speaker 2: perfectly symmetric. The equations should be the same. So if
• 24:03
  Speaker 2: you think, like, well, what happens to a neutral atom
• 24:06
  Speaker 2: if I have an electron nearby, Well, the electron repels
• 24:09
  Speaker 2: the other electron and attracts the proton. So if you
• 24:12
  Speaker 2: have a north charge in your hand and then you
• 24:13
  Speaker 2: have a dipole nearby, then it will attract the south
• 24:16
  Speaker 2: part of the dipole and repel the north part of
• 24:18
  Speaker 2: the dipole. That dipole will align itself in that magnetic field.
• 24:22
  Speaker 1: I see, repel the north part. But what will attract
• 24:25
  Speaker 1: the south part of my magnet?
• 24:27
  Speaker 2: Exactly? Yeah?
• 24:28
  Speaker 1: What if I have like a spinning electron.
• 24:31
  Speaker 2: A spinning electron will create a dipole field, right, so
• 24:34
  Speaker 2: then you'll have two dipoles.
• 24:35
  Speaker 1: Oh, I think I see the difference. Like, if I
• 24:37
  Speaker 1: have a monopole in my left hand and a dipole
• 24:40
  Speaker 1: in my right hand, the forces it exerts on my
• 24:43
  Speaker 1: right dipole magnet are always going to be sort of
• 24:46
  Speaker 1: pointing away from the north monopole. Right, That's kind of
• 24:50
  Speaker 1: what it means to have a monopole. Whereas if I
• 24:51
  Speaker 1: had a dipole in each hand, how they affect each
• 24:55
  Speaker 1: other sort of depends on how I twist my hands
• 24:57
  Speaker 1: or in what direction or where I put them relative
• 24:59
  Speaker 1: to each other. But a monopole magnetic monopole would sort
• 25:02
  Speaker 1: of act like a point particles that I think is
• 25:05
  Speaker 1: what you're saying. It would like exert forces the same
• 25:08
  Speaker 1: in all directions.
• 25:09
  Speaker 2: And theoretically this comes from exactly the kind of questions
• 25:12
  Speaker 2: you're asking. You're basically saying, it seems like magnetism is
• 25:16
  Speaker 2: like just a part of electricity, right, because electricity is
• 25:19
  Speaker 2: really the source of everything. But the theory says, well,
• 25:21
  Speaker 2: if electric sources can generate magnetic fields, why can't we
• 25:25
  Speaker 2: have like magnetic sources that generate electric fields, right? Why
• 25:29
  Speaker 2: can't we do that? Also? Why isn't there a symmetry there?
• 25:32
  Speaker 2: Why can't we have things that are just sources of
• 25:34
  Speaker 2: magnetic fields and then when they spin they make electric dipoles.
• 25:38
  Speaker 2: Or if you have a current of magnetic sources that
• 25:41
  Speaker 2: would generate an electric field the same way a current
• 25:43
  Speaker 2: of electric charges would generate a magnetic field. Wouldn't it
• 25:46
  Speaker 2: be awesome if there was symmetry to them? And if
• 25:49
  Speaker 2: you look at the equations Maxwell's equations for electromagnetism, there
• 25:53
  Speaker 2: is this weird asymmetry. The universe seems to prefer electricity.
• 25:56
  Speaker 2: It seems to be more primary, and that's because we
• 25:59
  Speaker 2: have electric charges. And if you say, well, actually, what
• 26:02
  Speaker 2: if there are monopoles in the universe and you change
• 26:05
  Speaker 2: Maxwell's equations to allow for monopoles, then they become perfectly symmetric.
• 26:10
  Speaker 2: All the equations are just like mirror images of each other.
• 26:12
  Speaker 2: Electricity and magnetism is just two sides of exactly the
• 26:15
  Speaker 2: same coin. So if there were monopoles, it would be
• 26:18
  Speaker 2: this like beautiful theoretical clicking together of these two pieces.
• 26:23
  Speaker 1: Hmmm, interesting, I guess maybe I wonder if the big
• 26:26
  Speaker 1: question is really sort of related to the idea that,
• 26:30
  Speaker 1: like we don't really know why spinning charges create magnetic fields.
• 26:33
  Speaker 1: Do we know that?
• 26:34
  Speaker 2: I guess it depends on what kind of answer you're
• 26:36
  Speaker 2: looking for for why. I mean, we know that it happens.
• 26:40
  Speaker 2: We have a mathematical description of it. We've invented this
• 26:44
  Speaker 2: concept of a field to explain like the forces on
• 26:47
  Speaker 2: particles in the vicinity of moving charges. What kind of
• 26:50
  Speaker 2: why are you looking for?
• 26:52
  Speaker 1: Like if I have a spinning electron on my right
• 26:54
  Speaker 1: hand and a spinning electron on my left hand, why
• 26:57
  Speaker 1: does the spinning electron in my right hand one make
• 27:00
  Speaker 1: this other spinning electron spin in the same direction?
• 27:03
  Speaker 2: I think actually they want to make each other spin
• 27:05
  Speaker 2: any opposite directions.
• 27:06
  Speaker 1: Right, opposite directions?
• 27:07
  Speaker 2: Yeah, oh yeah, that's a good question. You know in
• 27:08
  Speaker 2: our universe, that's what happens, right, we see, that's what happens.
• 27:11
  Speaker 2: And if you try to make an explanation for it
• 27:13
  Speaker 2: without magnetic fields, it doesn't work. If you add this
• 27:17
  Speaker 2: thing called the magnetic field, then it does work. Right,
• 27:20
  Speaker 2: So far, just descriptive. You know, you're basically asking, like,
• 27:23
  Speaker 2: why do you have magnetic fields? Could you have a
• 27:25
  Speaker 2: universe without magnetic fields? You certainly could, But our universe
• 27:28
  Speaker 2: seems to have them. You're asking, could you have a
• 27:30
  Speaker 2: universe without magnetic fields? I think that would be more complicated.
• 27:34
  Speaker 2: It would be a very different universe. You wouldn't have light,
• 27:36
  Speaker 2: for example. So I'm not sure you could have a
• 27:39
  Speaker 2: universe without magnetic fields. I think maybe that's the question
• 27:41
  Speaker 2: you're asking, like why are they here?
• 27:43
  Speaker 1: No, I think I'm more asking, like, you know, how
• 27:45
  Speaker 1: like in space, if you have a whole bunch of
• 27:47
  Speaker 1: rocks twirling around an object like the Sun for example,
• 27:52
  Speaker 1: their orbits are going to collapse down into a disc
• 27:54
  Speaker 1: because like the forces balance out in the direction that
• 27:57
  Speaker 1: they're not spinning around the Sun, but they don't align.
• 28:01
  Speaker 1: You know, there's like a mechanical explanation for why orbits
• 28:05
  Speaker 1: tend to be discs.
• 28:06
  Speaker 2: Yeah, that comes from conservation of angular momentum, right.
• 28:09
  Speaker 1: Right, right. So Now, like if I have a spinning
• 28:11
  Speaker 1: electron on my right hand, I wonder I'm just wondering
• 28:14
  Speaker 1: if maybe it wants to make the other electron spin
• 28:17
  Speaker 1: in the opposite way, because if it's spinning, you know
• 28:20
  Speaker 1: what I mean, Like the motion plus the electric forces
• 28:23
  Speaker 1: somehow make it so that if they're spinning in opposite directions.
• 28:27
  Speaker 1: That's the most balanced way that they can be.
• 28:29
  Speaker 2: I don't think there's a simple mechanical explanation for it
• 28:32
  Speaker 2: in that sense. It's just that the kind of thing
• 28:34
  Speaker 2: we see happen in our universe, and I think that
• 28:37
  Speaker 2: theoretically it'd be pretty hard to build the universe without
• 28:40
  Speaker 2: magnetic fields. To me, that's the best answer for why
• 28:42
  Speaker 2: they're here. You know, it's something we see that happens,
• 28:46
  Speaker 2: and we don't know how to build a universe without it.
• 28:48
  Speaker 1: All right, maybe that's the answer. It's just the way
• 28:50
  Speaker 1: it is.
• 28:51
  Speaker 2: It is just the way it is. But in terms
• 28:53
  Speaker 2: of balance, it's like fascinating that the universe has all
• 28:56
  Speaker 2: these electric charges in it. We see them all over
• 28:58
  Speaker 2: the place, but we've never seen a magnetic charge, and
• 29:01
  Speaker 2: it would be so beautiful and symmetric if it did not,
• 29:05
  Speaker 2: only because it would like balance the equations of maxwell
• 29:08
  Speaker 2: in this way that like, let us have electric charges
• 29:11
  Speaker 2: generating magnetic field and magnetic charges generating electric fields and
• 29:14
  Speaker 2: all sorts of stuff. But it would also answer other
• 29:17
  Speaker 2: deep theoretical questions we have, like why is electric charge
• 29:21
  Speaker 2: quantized at all? Like why is electric charge always this
• 29:24
  Speaker 2: weird number of rational number one, third two third minus
• 29:28
  Speaker 2: one plus two. Why is it never like zero point
• 29:31
  Speaker 2: seventy one four?
• 29:33
  Speaker 1: All right, So it sounds like breaking this problem or
• 29:36
  Speaker 1: figuring it out would tell us about why things are
• 29:38
  Speaker 1: the way they are, which is my question in the
• 29:40
  Speaker 1: first place.
• 29:42
  Speaker 2: Yeah, it's really interesting, and it actually does have to
• 29:44
  Speaker 2: do with angular momentum, as you were talking about a
• 29:46
  Speaker 2: minute ago. In our universe, angular momentum is quantized, right,
• 29:50
  Speaker 2: how fast things spin around. Other things can't just have
• 29:54
  Speaker 2: any arbitrary value. They have to be quantized, like linear momentum,
• 29:58
  Speaker 2: how fast you're moving through space, how much momentum you have,
• 30:01
  Speaker 2: your mass times your velocity doesn't have to be quantized,
• 30:03
  Speaker 2: it can be any number, but your angular momentum. Right,
• 30:07
  Speaker 2: How the momentum of spinning does have to be quantized
• 30:10
  Speaker 2: in our universe. That's a really fascinating fact. But if
• 30:13
  Speaker 2: you have magnetic monopoles in the universe, you have electric
• 30:16
  Speaker 2: charge particle and a magnetically charged particle, then their angular
• 30:19
  Speaker 2: momentum is related to the product of their two charges,
• 30:23
  Speaker 2: like the amount of magnetic charge and the amount of
• 30:25
  Speaker 2: electric charge. And because the product has to be quantized,
• 30:28
  Speaker 2: that means they both have to be quantized. So if
• 30:31
  Speaker 2: there's a single magnetic monopole anywhere in the universe that
• 30:35
  Speaker 2: dates angular momentum has to be quantized, which means its
• 30:38
  Speaker 2: charge has to be quantized, and so does electric charge.
• 30:41
  Speaker 2: So if magnetic monopoles exist, then electric and magnetic charges
• 30:45
  Speaker 2: both have to be quantized.
• 30:47
  Speaker 1: I think you're saying that you know, are electric charges
• 30:49
  Speaker 1: are quantized? Like can you have just any amount of
• 30:52
  Speaker 1: electric charge right now? As far as we.
• 30:55
  Speaker 2: Know they are quantized. You cannot just have like an
• 30:57
  Speaker 2: arbitrary charge. You can't. We're not like seeing particles like
• 31:00
  Speaker 2: one point series or is there one to two electric charges?
• 31:03
  Speaker 2: And point nine nine nine seven electric charges? They seem
• 31:06
  Speaker 2: to be quantized in these discrete units.
• 31:09
  Speaker 1: But then magnetic charge it sort of depends on that
• 31:12
  Speaker 1: electric charge and how fast it's spinning.
• 31:14
  Speaker 2: Well, magnetic dipoles do, right, If there are magnetic monopoles,
• 31:17
  Speaker 2: there are north charges and south charges out there, then
• 31:21
  Speaker 2: you can also ask the question are those quantized? And
• 31:23
  Speaker 2: if so, then why The question is really like why
• 31:26
  Speaker 2: is electric charge? Why is any charge at all quantized?
• 31:29
  Speaker 2: Why isn't it just some arbitrary value. Why don't we
• 31:32
  Speaker 2: see like electrons out there with at big spectrum of
• 31:34
  Speaker 2: different charges. Why do they all have the same one?
• 31:37
  Speaker 1: Well, isn't it the case that electric charges quantized because
• 31:40
  Speaker 1: it's small at the unit that we know, and the
• 31:42
  Speaker 1: electron is a.
• 31:44
  Speaker 2: Particle, right, it is a particle.
• 31:45
  Speaker 1: Yeah, you're asking like, why can't electron have half of
• 31:48
  Speaker 1: them an electron charge?
• 31:49
  Speaker 2: Yeah? Or a real number right? Or an irrational charge?
• 31:52
  Speaker 2: Why is it always this integer or irrational ratio of
• 31:56
  Speaker 2: the integers? You know, we seem like one third or
• 31:59
  Speaker 2: minus two thirds or one seems to be quantized. Yes,
• 32:02
  Speaker 2: you're right, all electric charges are built out of electrons.
• 32:04
  Speaker 2: But the question is like why do particles themselves have
• 32:07
  Speaker 2: quantized electric charges? And the existence of a single magnetic
• 32:11
  Speaker 2: monopole in the universe would force all electric charges to
• 32:15
  Speaker 2: be quantized because their angular momentum depends on their charge.
• 32:19
  Speaker 2: An angular momentum we know has to be quantized. I
• 32:22
  Speaker 2: think the deep question is like why are things quantized?
• 32:25
  Speaker 2: To me? That's really fascinating, Like we could have had
• 32:27
  Speaker 2: a universe where particles have any random charge. Instead, we
• 32:32
  Speaker 2: seem to have a universe where particles have these fixed charges.
• 32:35
  Speaker 2: It's like a ladder of charges instead, of a spectrum,
• 32:38
  Speaker 2: and the question is why, and nobody really has an
• 32:40
  Speaker 2: answer to that except for this one explanation. If there's
• 32:44
  Speaker 2: a monopole out there in the universe, then particles have
• 32:46
  Speaker 2: to have quantized electric charges because it relates to their
• 32:49
  Speaker 2: angular momentum, which we already know has to be quantized.
• 32:53
  Speaker 2: We also think that magnetic monopoles were probably made in
• 32:55
  Speaker 2: the early universe, like when the Big Bang happened, it
• 32:58
  Speaker 2: made a bunch of particles of all, and if monopoles
• 33:01
  Speaker 2: are a thing, then a lot of them should have
• 33:03
  Speaker 2: also been made in the Big Bang and they should
• 33:06
  Speaker 2: still be flying around the universe.
• 33:08
  Speaker 1: But wait, I guess maybe the question is what would
• 33:10
  Speaker 1: this monopole be embodied in. Would it be a particle
• 33:13
  Speaker 1: with a monopole? Would it just be like a random
• 33:16
  Speaker 1: monopole that exists out there, like a random like magnet
• 33:19
  Speaker 1: floating out in space that has this Is it made
• 33:21
  Speaker 1: out of something or is it would it just exist?
• 33:24
  Speaker 2: It would be a new kind of particle, right, a
• 33:26
  Speaker 2: particle with some kind of mass and other properties you know, spin,
• 33:29
  Speaker 2: and it would have some kind of overall magnetic charge
• 33:33
  Speaker 2: the way electric charge doesn't just like float around unembodied
• 33:36
  Speaker 2: in the universe. It's attached to particles the same way
• 33:39
  Speaker 2: a magnetic charge would be attached to this new particle,
• 33:42
  Speaker 2: which we call a magnetic monopole. That would be the particle.
• 33:45
  Speaker 2: It's like the magnetic version of an electron, call it
• 33:48
  Speaker 2: the magnetron or whatever.
• 33:51
  Speaker 1: Okay, now see now you're talking about a whole new
• 33:53
  Speaker 1: kind of particle.
• 33:54
  Speaker 2: Yes, a whole new kind of particle exactly.
• 33:57
  Speaker 1: And so this new particle that we've had I haven't
• 34:00
  Speaker 1: seen yet so far would have mass maybe, and it
• 34:03
  Speaker 1: would also have electric charge or would not have electric charge.
• 34:07
  Speaker 2: It probably wouldn't have electric charge the way like an
• 34:09
  Speaker 2: electron doesn't have magnetic charge.
• 34:11
  Speaker 1: Okay, and so it we just have this magnetic charge
• 34:15
  Speaker 1: to a no spin either. Don't all particles need to
• 34:18
  Speaker 1: have spin.
• 34:19
  Speaker 2: Not all particles have spinned like the Higgs boson has
• 34:21
  Speaker 2: no spin, but every other particle does. And so this
• 34:24
  Speaker 2: particle probably would have spin. There's a bunch of different
• 34:27
  Speaker 2: theories of magnetic monopoles, but in most cases they have spin,
• 34:31
  Speaker 2: and a magnetic monopole spinning would create an electric dipole
• 34:35
  Speaker 2: the same way that an electron spinning has a little
• 34:38
  Speaker 2: magnetic field. A magnetic monopole spinning would have a little
• 34:41
  Speaker 2: electric field, all.
• 34:42
  Speaker 1: Right, And so then this new particle would somehow exist
• 34:45
  Speaker 1: in ems. But we haven't seen it before.
• 34:47
  Speaker 2: We've never seen one. Nobody has ever spotted a magnetic monopole.
• 34:51
  Speaker 1: Wouldn't we have noticed by now, you know, like there
• 34:54
  Speaker 1: are a bunch of north pole particles out there floating.
• 34:57
  Speaker 1: Wouldn't they have been attracted to our south pole we
• 35:00
  Speaker 1: have known? Is that they you know, our soft poles
• 35:03
  Speaker 1: are getting heavier.
• 35:03
  Speaker 3: M hm.
• 35:04
  Speaker 2: Exactly. If magnetic monopoles were as common as electrons, then
• 35:08
  Speaker 2: absolutely yes, we would have noticed them, and they would
• 35:11
  Speaker 2: have played a big role in life, and experience of
• 35:13
  Speaker 2: living in this universe would be very different, and magnetism
• 35:16
  Speaker 2: would be very different, and it would have then bubbled
• 35:19
  Speaker 2: up through our primary experience. And when Maxwell wrote his laws,
• 35:22
  Speaker 2: instead of making them asymmetric and basing everything on electric charges,
• 35:25
  Speaker 2: it would have written magnetic monopoles into his equations. But
• 35:29
  Speaker 2: magnetic monopoles, if they do exist, are very very rare.
• 35:32
  Speaker 2: They're either none in the universe or very very few
• 35:35
  Speaker 2: because we've never seen any.
• 35:36
  Speaker 1: Well, I guess that begs the question, how can we
• 35:38
  Speaker 1: look for them, and have we found any. So let's
• 35:41
  Speaker 1: dig into our search for this possibly imaginary maybe the
• 35:45
  Speaker 1: sense of making particle and what we're doing about it.
• 35:49
  Speaker 1: But first let's take another quick break. All right, you
• 36:05
  Speaker 1: have the monopoly today here on magnetic confusion for cartoonists,
• 36:10
  Speaker 1: and it sounds like there is a concept out there
• 36:13
  Speaker 1: called a monopole, which is maybe this theoretical or maybe
• 36:17
  Speaker 1: potential particle that might exist that has magnetic charge to it.
• 36:21
  Speaker 1: It attracts north and south or repels north and south
• 36:25
  Speaker 1: magnetic holes, but it doesn't really have a direction to it.
• 36:28
  Speaker 1: It only has either north or south to it as
• 36:31
  Speaker 1: an inherent property of its particleness.
• 36:34
  Speaker 2: Exactly, and nobody ever seen one in that sense, it's theoretical,
• 36:38
  Speaker 2: but it's also very theoretically motivated. Like the universe is
• 36:41
  Speaker 2: sort of weird and out of whack, it would make
• 36:43
  Speaker 2: a lot of sense to see monopoles the same way
• 36:45
  Speaker 2: the universe seems weird and out of whack without anti matter. Right,
• 36:49
  Speaker 2: the equations work for matter, and they should also work
• 36:51
  Speaker 2: for antimatter, and so Direc said, like, hmm, let's go
• 36:54
  Speaker 2: look for antimatter, and then we found it. It's not
• 36:56
  Speaker 2: very much of it. It's pretty rare, but it shows
• 36:58
  Speaker 2: us that the universe has this symmetry. It was also
• 37:01
  Speaker 2: direct who said maybe we should go look for monopoles
• 37:04
  Speaker 2: as this sort of symmetric version of electrically charged particles.
• 37:07
  Speaker 2: So it would make a lot of sense if it
• 37:09
  Speaker 2: existed in the universe, but so far we've never seen one.
• 37:12
  Speaker 1: Okay, which begs the questions are we looking for them?
• 37:14
  Speaker 1: Are physicists trying to find these or just sitting back
• 37:17
  Speaker 1: on their couch wondering if they exists.
• 37:21
  Speaker 2: Some physicists are trekking out to the South Pole building
• 37:24
  Speaker 2: crazy amazing telescopes out of the ice in the South
• 37:27
  Speaker 2: Pole to look for neutrinos but also to look for
• 37:31
  Speaker 2: magnetic monopoles.
• 37:32
  Speaker 1: Nice. So this is a famous experiment, or a big experiment.
• 37:35
  Speaker 2: It's a famous and big experiment. There's a big group
• 37:36
  Speaker 2: here at you see Irvine that works on it. It's
• 37:38
  Speaker 2: called the Ice Cube Neutrino Observatory, and it literally is
• 37:43
  Speaker 2: an ice cube. They take a cubic kilometer of ice
• 37:47
  Speaker 2: on the South Pole, they drill holes in it, and
• 37:50
  Speaker 2: they bury cameras on these long strings within the ice.
• 37:54
  Speaker 2: So they basically have instrumented a cubic kilometer of ice
• 37:58
  Speaker 2: looking for flashes of light of particles traveling through that ice.
• 38:02
  Speaker 1: Wait, what, so they just take like an ice shelf
• 38:04
  Speaker 1: down in Antarctica and they drill down like a kilometer
• 38:07
  Speaker 1: or two, and they rope down cameras instruments. But then
• 38:12
  Speaker 1: they're pretty far apart from each other, aren't they.
• 38:15
  Speaker 2: Yeah, they have like ninety of these strings. Each one
• 38:18
  Speaker 2: is like one to two kilometers long. And as you say,
• 38:21
  Speaker 2: they drill these crazy deep holes in the ice and
• 38:25
  Speaker 2: then they have these strings. So every string has like
• 38:27
  Speaker 2: a lot of cameras on it, a lot of these
• 38:29
  Speaker 2: light sensors. They lower those down into these holes and
• 38:33
  Speaker 2: then they pour water in so the whole thing freezes
• 38:35
  Speaker 2: up again. So then you have this cubic kilometer of
• 38:38
  Speaker 2: ice with about five thousand sensors distributed through it. You're right,
• 38:41
  Speaker 2: they're not like equally distributed. They'd love to have more strings,
• 38:45
  Speaker 2: but this is sort of the best they can do.
• 38:47
  Speaker 1: So then how are they looking for monopoles?
• 38:49
  Speaker 2: So what you can do with this ice is you
• 38:51
  Speaker 2: can look for Cherenkov light. That's light that particles emit
• 38:54
  Speaker 2: when they fly through material. Faster than photons can fly
• 38:58
  Speaker 2: through that material, where you can't move faster than light
• 39:01
  Speaker 2: in a vacuum. But when light moves through ice, it
• 39:04
  Speaker 2: moves that's slower than the speed of light in a vacuum,
• 39:06
  Speaker 2: and particles don't always have to follow that same limit.
• 39:09
  Speaker 2: So if a muon, for example, is moving through the
• 39:12
  Speaker 2: ice faster than a photon could, it creates this sort
• 39:15
  Speaker 2: of superluminal wake. The way, for example, if you're on
• 39:18
  Speaker 2: a jet ski in a lake, you're creating a wake
• 39:21
  Speaker 2: behind you because the boat that's making the ripples is
• 39:24
  Speaker 2: moving faster than the ripples, so the ripples sort of
• 39:27
  Speaker 2: like add up to make this wake, this cone of
• 39:30
  Speaker 2: ripples behind you. The same way, particles moving through this
• 39:33
  Speaker 2: material emit this special light, this cherankof light in a
• 39:37
  Speaker 2: cone as they move, so you can use this to
• 39:39
  Speaker 2: spot particles moving really really fast through the ice. And
• 39:43
  Speaker 2: they build this thing not to look for monopoles, but
• 39:45
  Speaker 2: to look for neutrinos that move up through the Earth.
• 39:48
  Speaker 2: So they come from the Sun or somewhere out in
• 39:50
  Speaker 2: deep space, they move up through the Earth, interact somewhere
• 39:54
  Speaker 2: in the Earth, and they create like a muon which
• 39:56
  Speaker 2: flies through the ice, and that tells them that a
• 39:58
  Speaker 2: neutrino was there. That's why they built this experiment as
• 40:02
  Speaker 2: a neutrino observatory.
• 40:03
  Speaker 1: Wait, so they built it to technittrinos, but you can
• 40:05
  Speaker 1: also use it to potentially a monopole particle exactly.
• 40:10
  Speaker 2: This is one of the clever like reapplications of these things.
• 40:13
  Speaker 2: They build it for one thing, but then they realize, actually,
• 40:15
  Speaker 2: we could also use this to look for something else,
• 40:18
  Speaker 2: because a muon and a monopole going through the ice
• 40:20
  Speaker 2: would look very very different. Magnetic monopoles, if they exist,
• 40:24
  Speaker 2: would make a spectacular signature in the ice. Because of
• 40:27
  Speaker 2: this relationship between the magnetic and electric charges. We know
• 40:31
  Speaker 2: that the minimum magnetic charge of a monopole, if it exists,
• 40:35
  Speaker 2: is basically the equivalent of like sixty eight electric charges.
• 40:38
  Speaker 2: So a magnetic monopole, if it exists, it's like very
• 40:41
  Speaker 2: very magnetically charged. So when it flies through the ice,
• 40:44
  Speaker 2: it would create like a series of brilliant flashes of
• 40:47
  Speaker 2: this drank off light.
• 40:48
  Speaker 1: Wait, I guess there's so many questions there. Why do
• 40:51
  Speaker 1: you think a monocle would be so magnetically charged? Firs,
• 40:54
  Speaker 1: Whill where does that guess?
• 40:56
  Speaker 2: Come from. So it comes from this argument that electric
• 40:59
  Speaker 2: and magnetic charging are connected by angular momentum. Parames to
• 41:02
  Speaker 2: the two has to be quantized because that's related to
• 41:04
  Speaker 2: angular momentum. So that let's you actually calculate what the
• 41:07
  Speaker 2: minimum magnetic charge has to be. If that argument holds,
• 41:12
  Speaker 2: it's sort of like the fine structure constant over two,
• 41:15
  Speaker 2: So that's like one thirty seven over two. So the
• 41:17
  Speaker 2: minimum magnetic charge has to be like sixty eight and
• 41:20
  Speaker 2: a half times the electric charge. So basically, if there
• 41:23
  Speaker 2: are magnetic monopoles out there, they are very very magnetic.
• 41:27
  Speaker 2: They're not just like a little bit magnetic.
• 41:29
  Speaker 1: And so as it goes through the ice, this particle
• 41:32
  Speaker 1: wouldn't interact with the water molecules.
• 41:34
  Speaker 2: It would interact with the water molecules. That's what generates
• 41:37
  Speaker 2: the trenk Off radiation is the interaction of this particle
• 41:40
  Speaker 2: with the electromagnetic fields of the water. That's what generates
• 41:43
  Speaker 2: this radiation because it's interacting with the material it's moving through,
• 41:47
  Speaker 2: and that interaction would generate all of this radiation. It
• 41:50
  Speaker 2: wouldn't interact in the same way an electron interacts, right,
• 41:53
  Speaker 2: because electron has a different charge than a magnetic monopole
• 41:56
  Speaker 2: would and because this thing is basically more charge urged
• 42:00
  Speaker 2: than an electron is even though it also has a
• 42:02
  Speaker 2: different kind of charge, its magnitude is also greater. It
• 42:05
  Speaker 2: emits more radiation, like eight thousand times as much radiation.
• 42:10
  Speaker 1: I guess you know we talked last time about neutrinos
• 42:12
  Speaker 1: that they can go through things because they don't feel
• 42:15
  Speaker 1: the electromagnetic force, only the weak force. Right, But here
• 42:19
  Speaker 1: is something that is totally super magnetic. You're saying it's
• 42:22
  Speaker 1: very magnetic. Why wouldn't it sort of bounce around when
• 42:25
  Speaker 1: it hits or flies close to all of these water molecules?
• 42:28
  Speaker 1: Why would it keep going?
• 42:29
  Speaker 2: Yeah, that's a good question. If you shoot an electron
• 42:32
  Speaker 2: and a big blob of ice, it doesn't go all
• 42:34
  Speaker 2: the way through, right, it gets absorbed. But if you
• 42:35
  Speaker 2: shoot a muon through it. Muon, remember is an electron,
• 42:38
  Speaker 2: but with more mass it can penetrate through because it
• 42:41
  Speaker 2: has more mass, so it like has more momentum to
• 42:43
  Speaker 2: keep going. In a monopole, we think also would be
• 42:46
  Speaker 2: massive and so it would survive making it through the ice.
• 42:49
  Speaker 2: It's more like a muon than an electron, but also
• 42:53
  Speaker 2: has this crazy magnetic charge that makes it radiate a
• 42:56
  Speaker 2: lot as it flies through.
• 42:57
  Speaker 1: Wait, so you think it would also be massive. Why
• 42:59
  Speaker 1: do you think it would be massive?
• 43:00
  Speaker 2: There are lots of different theories for magnetic monopoles. Some
• 43:03
  Speaker 2: of them predicted it would be massive, some of them
• 43:05
  Speaker 2: predicted wouldn't be. Basically, this experiment can only see the
• 43:08
  Speaker 2: ones that are massive. If there's a magnetic monopole out
• 43:11
  Speaker 2: there that has very very low mass, then it wouldn't
• 43:13
  Speaker 2: make it through the ice, and so you wouldn't see
• 43:15
  Speaker 2: this signature.
• 43:15
  Speaker 1: So now I feel like this is just getting more
• 43:19
  Speaker 1: theoretical by the minute. So now you're assuming it exists,
• 43:22
  Speaker 1: and also that it's massive, and also that it has
• 43:24
  Speaker 1: a huge magnetic charge to it, and also.
• 43:26
  Speaker 2: That it's going super duper fast. We can only see
• 43:29
  Speaker 2: these things if they're moving like relativistically, right. Cherenkov light
• 43:32
  Speaker 2: is only emitted if the thing is moving faster than
• 43:35
  Speaker 2: photons through that material. If you have a slow massive monopole,
• 43:38
  Speaker 2: it wouldn't emit this light. We wouldn't see it. But
• 43:41
  Speaker 2: this telescope is capable of seeing massive monopoles with a
• 43:44
  Speaker 2: lot of magnetic charge if they're also moving faster than
• 43:48
  Speaker 2: three quarters of the speed of light. So you're right,
• 43:50
  Speaker 2: it can't look for every kind of monopole, but it's
• 43:52
  Speaker 2: definitely worth looking because if they are there, they would
• 43:55
  Speaker 2: be spectacular signature, would be like very obvious, very easy
• 43:58
  Speaker 2: to see it, and very hard to spoof.
• 44:00
  Speaker 1: But I guess, hasn't this observatory been out there for
• 44:03
  Speaker 1: a while. Wouldn't this have boundaries by now? Or no,
• 44:07
  Speaker 1: it is these weird streaks.
• 44:08
  Speaker 2: Yeah, you're right, it seems like it would be kind
• 44:10
  Speaker 2: of obvious in their data. Why wouldn't they have noticed it?
• 44:12
  Speaker 2: But you know, it's not like people are always looking
• 44:14
  Speaker 2: through the data by eye. When you do an analysis
• 44:17
  Speaker 2: of your data in a particle physics experiment, you're looking
• 44:19
  Speaker 2: for a particular kind of thing usually, and so this
• 44:21
  Speaker 2: might have been missed if nobody was looking for it.
• 44:24
  Speaker 2: So people went and did a dedicated search, like, let's
• 44:26
  Speaker 2: look through the data to see if there's any kind
• 44:28
  Speaker 2: of these weird things. So they've been running your life
• 44:31
  Speaker 2: for like almost a decade, and so they look through
• 44:33
  Speaker 2: all of their data trying to see if there are
• 44:34
  Speaker 2: any big, spectacular signatures of bright monopoles passing through this
• 44:38
  Speaker 2: cube of ice. And they didn't see any want.
• 44:41
  Speaker 1: Want wam, so all this setup was for nothing.
• 44:47
  Speaker 2: All this setup tells us that if there are monopoles
• 44:49
  Speaker 2: out there, they're either not moving fast, or they don't
• 44:52
  Speaker 2: have enough mass, or there's something very different from what
• 44:54
  Speaker 2: we expected. But it's pretty awesome to take this cube
• 44:58
  Speaker 2: of ice in the South Pole and to look for
• 45:00
  Speaker 2: these things. I love how dramatic the signature is. I
• 45:03
  Speaker 2: love how exciting it is. Because also they're going to
• 45:05
  Speaker 2: keep running it. It might be that monopoles are just
• 45:07
  Speaker 2: pretty rare, Maybe there aren't very many left over, Maybe
• 45:10
  Speaker 2: there weren't very many made in the Big Bang. Maybe
• 45:13
  Speaker 2: they're all clustered together the center of the galaxy. We
• 45:16
  Speaker 2: just don't know, so it's worthwhile to keep looking. So
• 45:18
  Speaker 2: they're going to keep running this experiment, and they're going
• 45:20
  Speaker 2: to keep looking for monopoles, and you know, it only
• 45:22
  Speaker 2: really takes one because it's such a dramatic and spectacular signature.
• 45:27
  Speaker 1: And it sounds I give you fine one. It would
• 45:29
  Speaker 1: be pretty significant, right, like you're just trying to prove
• 45:31
  Speaker 1: its existence exactly.
• 45:33
  Speaker 2: Just knowing that it's possible for them to exist would
• 45:35
  Speaker 2: be amazing game changing, right the same way that like
• 45:38
  Speaker 2: discovering one single particle of antimatter proved that antimatter is
• 45:42
  Speaker 2: a thing, and this symmetry exists in the universe, like
• 45:46
  Speaker 2: the guy got the Nobel Prize for literally a picture
• 45:48
  Speaker 2: of one particle that he found in nineteen twenty nine.
• 45:53
  Speaker 2: And so the discovery of a single monopole would tell
• 45:55
  Speaker 2: us something really deep about the nature of electricity and
• 45:58
  Speaker 2: magnetism in our universe. I would answer your question, like,
• 46:01
  Speaker 2: why is magnetism a thing, well, because magnetic monopoles are
• 46:04
  Speaker 2: part of our universe for the same reason the charges
• 46:07
  Speaker 2: are a thing, and so to me that would be
• 46:09
  Speaker 2: really fascinating and these things are totally worth looking. Every
• 46:12
  Speaker 2: time I hear about magnetic monopoles, I'm like, ooh, I
• 46:14
  Speaker 2: hope they found it.
• 46:16
  Speaker 1: I guess maybe a question you can ask is what
• 46:18
  Speaker 1: if they don't exist, what does that mean about the universe.
• 46:20
  Speaker 2: It means the universe is imbalanced in this weird, uncomfortable way.
• 46:24
  Speaker 2: We like symmetry in our equations, we like balance, We
• 46:27
  Speaker 2: like things to not prefer one direction or another. So
• 46:30
  Speaker 2: it's pretty weird if electricity and magnetism have this deep relationship,
• 46:34
  Speaker 2: but the universe prefers electricity for some reason. It's the
• 46:37
  Speaker 2: same as being uncomfortable about like why matter is matter
• 46:40
  Speaker 2: and antimatter is pretty rare. We'd like an explanation for that,
• 46:44
  Speaker 2: And so if there's a symmetry, then we don't need
• 46:46
  Speaker 2: an explanation. If there isn't a symmetry, then we need
• 46:49
  Speaker 2: to know why.
• 46:50
  Speaker 1: Well, it sort of sounds like, you know, generally you
• 46:52
  Speaker 1: can explain magnetism. We just electric charge and spin or
• 46:57
  Speaker 1: spin direction. I wonder you even need magnetism.
• 47:00
  Speaker 2: Yeah, well that's why we combined electricity magnetism too one theory.
• 47:04
  Speaker 2: So in that sense, is magnetism even really a thing? Well,
• 47:07
  Speaker 2: electromagnetism is a thing, and so magnetism on its own
• 47:11
  Speaker 2: doesn't really make sense. It's sort of like saying, you know,
• 47:13
  Speaker 2: do you need elephant tails? Well, they're part of elephants
• 47:16
  Speaker 2: that don't exist by themselves, but they're also an important
• 47:19
  Speaker 2: part of the elephant, right, elephants don't want you chopping
• 47:22
  Speaker 2: their tails off.
• 47:23
  Speaker 1: I don't know, I haven't asked any elephants, and they
• 47:28
  Speaker 1: need to be fine with their tails. I guess what
• 47:30
  Speaker 1: I mean is maybe like a you know, like maybe
• 47:33
  Speaker 1: our wonder if we're trying to look for an effect
• 47:35
  Speaker 1: that we can already explain. Do you know what I mean?
• 47:37
  Speaker 1: Like we have like a charge, we have spin. That
• 47:40
  Speaker 1: kind of explains maganism, doesn't it.
• 47:42
  Speaker 2: Yeah. Absolutely, we can explain all the phenomena we see
• 47:45
  Speaker 2: in the universe without magnetic charges. But the explanation we
• 47:50
  Speaker 2: build has this hole in it, which makes us wonder
• 47:52
  Speaker 2: if we're missing something, the same way that when we
• 47:54
  Speaker 2: put the periodic table together, we notice there's some holes
• 47:57
  Speaker 2: in it. There's some gaps in there. I wonder if
• 47:59
  Speaker 2: that kind of thing exist. Let's go out and try
• 48:01
  Speaker 2: to make technetium. Oh, look, it does exist. That feels satisfactory. Right,
• 48:05
  Speaker 2: It's like an OCD person filling in that last square.
• 48:08
  Speaker 2: So the structure of the theory of electromagnetism seems so
• 48:11
  Speaker 2: tantalizing and tempting it suggests that they might exist. So
• 48:15
  Speaker 2: you're right, we don't need them to explain anything we've
• 48:18
  Speaker 2: seen in the universe. In fact, we have to go
• 48:19
  Speaker 2: out and make special experiments, just a hunt for effects.
• 48:22
  Speaker 2: They can't be explained with electric charges. But we'd love
• 48:26
  Speaker 2: if they did exist because it would just make the
• 48:27
  Speaker 2: theory more beautiful and balanced.
• 48:29
  Speaker 1: And that's what physics. It's all about beauty and balance.
• 48:32
  Speaker 2: It's about finding simple explanations for the complex phenomena.
• 48:36
  Speaker 1: Yeah, all right, well, good luck to the ice cubed
• 48:38
  Speaker 1: nutrino experiment. I hope they find a monopole or a
• 48:42
  Speaker 1: fast moving heavy monopole, right, but those are the requirements,
• 48:45
  Speaker 1: a highly magnetic, fast massive monopole.
• 48:48
  Speaker 2: And if they do, I hope they invite you down
• 48:50
  Speaker 2: there to help them celebrate.
• 48:51
  Speaker 1: Oh man, for sure, in fact, invite me now, I'll
• 48:54
  Speaker 1: totally go. I'll help you dig one of the one
• 48:58
  Speaker 1: of the holes.
• 48:58
  Speaker 2: All right, put that on your tour.
• 49:00
  Speaker 1: Sounds good. Well, we hope you enjoyed that. Thanks for
• 49:03
  Speaker 1: joining us, see you next time.
• 49:12
  Speaker 2: Thanks for listening, and remember that Daniel and Jorge Explain
• 49:15
  Speaker 2: the Universe is a production of iHeartRadio. For more podcasts
• 49:19
  Speaker 2: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
• 49:24
  Speaker 2: you listen to your favorite shows.