Daniel and Kelly’s Extraordinary Universe - What is the axion?

Episode Date: June 30, 2020

Why do scientists think there might be a wispy mysterious particle? And why did they give it such a silly name? Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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Welcome to Season 2 of The Good Stuff. Listen to the Good Stuff podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Hey, Daniel, if you ever discovered a particle, what would you name it? Uh-oh. I feel a little bit put on the spot here. No pressure. I mean, you wouldn't just name it the White Sun or the Whitesonino. The Danielino? Well, you know, over the course of these podcasts, I've come to get a feeling of, I don't know, judgment from you

by the quality of particle names. So I guess I feel some responsibility to like do it right and meet your high standards. Oh, well, I'm glad I'm doing my bit to make physics better. You know, I just hope you don't give it a silly name, you know, like a random name. Like a squiglion or something? Yeah, no squiglions. That would be a silly name.

Well, I promise to do my best. I won't like name it after a random laundry deterrent. All right, if you do that, this podcast is over. Hi, I'm Jorge. I'm a cartoonist and the creator of PhD comics. Hi, I'm Daniel. I'm a particle physicist who has never discovered a particle. At least one that nobody else is discovered. That's right. I found particles this morning when I had breakfast, and I plan to find some more for lunch,

but they're all your everyday run-of-the-mill, quarks and electrons. Yeah, I find particles all the time in my belly button. That's probably not a picture. We want to paint this early in the episode. That's probably what dark matter is, Jorge. It's just your belly button. Oh, yeah, my bellybun is full of dark matter and dark energy. And physicists also can't explain it.

But welcome to our podcast, Daniel and Jorge, Explain the Universe, a production of I. Hard Radio. In which we try to tackle the biggest questions in the universe, what is dark matter, what is everything made out of what is that weird thing in Jorge's belly button? And we try to do it in a way that educates you and entertains you along the way. Yeah, and we like to talk about not just the science and what we know about the universe and what we don't know, but we also kind of like to talk sometimes about the process of science, like how were things discovered or what are scientists thinking about or what are they looking for?

That's right, because the forefront of science, the edge of here, human curiosity, it belongs to everybody. And we want you to know what are scientists thinking about. What are they wondering about? What do they not know? And what are they doing to figure it out? How do we go from clueless to slightly clued in? Slightly less clueless. Diminishing clueless. That'll be the title of my autobiography. Yeah, we like to kind of stand at the precipice of ignorance, I like to call it. Like we're right at the edge of what scientists know and don't know and what they're discovering right now at the moment. Do you think we're in danger of falling into that precipice or we're pushing it back?

I think it's possible to go a little bit too deep into the rapid hole here of what we don't know in physics. Just following up on your metaphor there, does that make the rabbit is ignorance or rabbits are ignorant? Well, I don't want to insult any rabbits. We're definitely pro-rabbit on this podcast. We are. We like rabbits here. But one question is that, you know, there are all these particles out there in the universe and there's a whole bunch of of particles we've discovered in the universe and so the kind of the question is like how do people find new particles how do you physicists discover them yeah there's sort of two big ways to do it

one is to look at the list of particles we have now and say it doesn't seem complete we need another one and this is the case when we talked about the top core for example we had a nice little pattern of particles with a missing square in it there was one particle that didn't have a partner and everything else was paired off so we thought there must be one there And sometimes more abstractly, we say there's just a larger pattern that would make sense if we added one more particle. I see. That's how the Higgs boson was discovered, for example. So you're saying particle physics, it's kind of like Pokemon collecting or baseball card collecting.

Yeah, except we can't trade. You know, if the aliens come, maybe we could trade our discoveries for theirs, right? Oh my goodness. Your nerve brain just exploded. I'll give you a Higgs boson for the dark matter. Please, do you have dark matter? We want dark matter. Boy, that does sound kind of like fun.

You know, you get together in the neighborhood and you exchange what you know about the universe. Yeah, I'm looking forward to that party. But there's a whole other way to discover particles, which is just to sort of stumble across them, to like find them in nature and see them and go, what's that? And then figure out sort of how does it fit into the larger puzzle? Where does this go? How do we connect it? And we haven't done too much of that recently. Mostly we've been predicting particles and then finding it.

Oh, I see. So how would you stumble upon a particle? Like you're running the collider or any kind of collider and then suddenly you see something you weren't expecting? Yeah, precisely. This is how muons were discovered, for example. They had big blocks of photographic materials up on the tops of mountains and they saw these streaks of particles going through them

and the particles weren't consistent with electrons or anything else. And so they said, well, this must be some new particle we haven't seen before. And colliders are actually the best place to discover a new, unexpected particle because you smash the protons together and you get this little blob of energy which can turn into anything, anything the universe is capable of making. And so it could just pop out some crazy new particle

you've never seen before without you knowing that it's exist. You don't have to know it's there in order to find it. That's the amazing thing about exploring the universe with colliders. You'd be like, who ordered that? Exactly. Where'd that go from? That's exactly literally what they said when they heard about the muon. They said, what?

We don't need that. That doesn't make it. any sense. Go take that somewhere else. Well, we've had several episodes where we talk about the discovery and the search for different particles. We had one about the top cork and the electron and all these other particles. And so today we'll tell the story of another particle, one that was proposed almost 40 years ago and that we are still looking for. That's right. This is a particle which may or may not exist.

And if it does exist, it may simultaneously solve two of the biggest problems. in particle physics. Wow. And weirdly, it's a particle almost nobody outside the field has even heard of. Wow. Well, I guess we don't know

if it exists. And so if it doesn't exist, we have to erase this podcast episode, Daniel? Or? No, we get paid either way. It doesn't really matter. Okay. Yeah, forget about that.

Well, apparently has one of the silliest names in the history of particles. Yes, I'm looking forward to hearing your reaction to how this particle was named. It ends up with a really pretty cool name, but the reason for that name is really pretty ludicrous and whimsical. Oh, man. I am not looking forward to that. But anyway, so today on the podcast, we'll be asking the question, what is the most important particle you've never heard of? Is this like a trendy

band that everyone should listen to, but nobody knows about? Yeah, this is the particle your teenager knows about, but you are clueless about. It's super hot on TikTok. You're like, what, what is TikTok? That's precisely it. You don't even know the name of the social media app on which this particle is cool. That's how uncool you are. No, but it is a really cool name. I like, I like the sound of the name of this particle.

This particle is called the axion. That does sound pretty cool. It does sound pretty cool. What does it evoke in your mind, Jorge? Like a robot or, you know, like axes maybe? Unfortunately, the word for armpit in Spanish is kind of close to it. So it is making me think a little bit of armpits, but we won't go there. The armpit on, wow.

That is an unfortunate name, yes. It makes me think of sort of like double-edged axes being thrown in space along three different axes. You got like your X and Yax and your Yax and your Z X. Or you're throwing an X and X around? I don't know. I don't know. But it is a cool name. It's fun to say.

It's got that XM sound in there. I think as long as it sounds like a transformer, it sounds, I think, cool in physics. You know, synchrotron, graviton, megatron. The synchrotron is not a particle, though. The awesome tron. There you go. That will be the name of a particle. Some of you may have heard about the new interesting axon result from the Xenon experiment.

Now, today we'll be talking about the Axion more generally. But we're going to dig into the Xenon solar axion question in a dedicated episode coming very soon. But as usual, I was curious, what did people know about the Axion? Is this something people actually have heard of? Or is this something that only the cool kids on physics TikTok know about? And so as Daniel went out there into the wilds of the internet to ask people what they know about the Axion particle. So thank you to everybody who volunteered to answer random internet questions and sending in your responses. If you'd like to participate in random person on this street

internet questions, then please write to us at questions at danielanhorpe.com. So before you hear these answers, think about it for a second. If someone asked you, if you knew what the axion particle was, what would you say? Here's what people had to say. I think this is

a way to classify particles. They like they can be axioms and bosons and it has to do with them, for example, having mass or not. I don't know. I guess axiom, axis, would it perhaps be some sort of particle that other particles turn around? I have no idea. But since it sounds like the word axel, I'm going to guess

it has something to do with joining other particles together. I have no idea. I don't know. I think that's to do with what dark matter is made of. I believe there are two options are axioms or wimps. Honestly, I have no idea because it has the word ion in it. Maybe it's some kind of ion. I've got no idea. I never heard about something called axiom. Yeah, of course. That's an elementary particle of an action figure.

The caveman scientists in your book discussing what the most fundamental particle of a stone axe would be. I assume it's not a standard particle. Maybe it's more like strange matter. All right. Not a lot of positive recognition there. I like the one that said it's an action figure or it's related to an action figure. Yeah, the fundamental element of an action figure. That makes a lot of sense. Well, if it does exist and it is part of nature, it could be part of all action figures. It could be. And the other great idea was that maybe it's related to axles. So maybe like joins particles together. This is some really creative responses here. I'm impressed.

Or maybe they were thinking like Axel Rose and like, oh, I'm a Gonson Roses fan. In which case, the Axion's career has to also be in the dust. Yeah. They better get on that physics TikTok right away, do some silly dances. But it did seem like none of these folks had heard of this particle or really had any clue about its incredibly important role in particle physics. Oh, man. Well, I would count myself among those numbers.

I had no idea what this and have no idea what this particle is before you sent me the outline for today's episode. But let's get into it, Daniel. What is the Axion? It sounds kind of important. but maybe not yet discovered. Yeah, the axon particle is totally theoretical. So we do not know if it's part of our universe at all. It may just be an idea in people's minds.

And remember, there have been a lot more ideas than actual particles. And sometimes these ideas are beautiful. They make perfect sense. And when the physicist has them, they go, wow, everything is connected. And this is the way the universe works. But then you go and you ask the universe like, is it real? And the universe says, nice idea. but no.

Isn't that kind of strange? I feel like that's almost like trying to discover new animals by thinking of them before you actually find it. It's like, oh, what if there's an animal with a duck bill, but then a dinosaur neck, and then butterfly wings? And then you go out looking for them. Wouldn't that be kind of not productive? Yeah, well, but to stretch the mixed metaphor of our rabbit holes here,

it's more like that you see evidence for this animal. He's like, what's eating all the deer? And, you know, I see all these strange footprints. and maybe that would be explained if there was this new predator out there I'd never seen before. And so you're trying to tie up loose ends and complete the picture by suggesting an explanation. And that's exactly what the axiom and a lot of other theoretically motivated particles do is they sort of try to tie together what we see in a smaller, more compact explanation. You've just been a pretty horrible picture of this animal, Daniel.

It goes around eating deer. Oh, my goodness. It's like a wolf, man. sharp edges. You were trying to go for a cool animal. Yes, exactly. Wolf with a duckbill and butterfly wings. That does sound pretty cool.

That does sound pretty cool. I want to see that animal if it exists. And you can name it. We'll call it the axon. We already use that name for something else. That would be so confusing. But what if you find the animal first, right? Like, what if you find the animal and call it the axiom before you discover this particle?

I think we've already used up the name, though. That's sort of like, you know, how the Space Force television show on Netflix has trademarked trademark the term space force before the actual U.S. Space Force got around doing it. Oh, that's a problem. That's a problem. Yeah, exactly. Anyway, back to particle physics. The axon, if it exists, is a lot like a photon, but it doesn't have zero mass.

It has a super tiny little wispy mass. Really? A massive photon. Yeah, but it's not very massive. Like the mass, if it has some, is like 200 billionth of the mass of the electricity. which is already one of the lightest particles. So it's like a light, light particle. It's like light, light, exactly.

It's very light, like light. But not quite light. Not quite light. It's not Coke Zero. It's like Coke light. Yeah, exactly. It's a Coke with a tiny little bit of real sugar in it. Right.

And why did somebody come up with this? Well, they came up with it to sort of answer the biggest problem in physics that nobody ever heard of, which is we're looking at the way that interactions happen in physics. And we noticed something weird, something that we cannot explain. And so it was sort of thought up to explain this other mystery. The same way you might hypothesize wolves if you see your deer missing. This is sort of like hypothesizing the axion to explain this other problem, which is called the strong CP problem.

Interesting. And now is its official title, the biggest problem Nodi has ever heard of? Like, do you guys talk about it that way? Yeah, it's sort of a famous problem that nobody really has any answer to except the axiom. And so that's why people think the axiom might really be real. And then we'll talk later in the program about how it could also simultaneously solve another huge problem, which makes the axiom sort of a sexy particle right now. But it was originally dreamt up to solve this other problem called the strong CP problem.

Okay. So what's the strong CP problem? So this problem has to do with basically why does the strong force not break some symmetries? In particle physics, we have all these symmetries like charge symmetry and paint. parity symmetry and time symmetry. These symmetries tell us whether something works the same when you flip it the other way. Like if we say something could happen to an electron, we ask, well, can the same thing happen to a positron, which is the opposite charge version of it?

Because we like symmetries in particle physics. We like the smallest set of rules. So we don't want a different set of rules for electrons and for positrons, for example. So it's kind of like, you know, like if two negative electrons propel each other, you can ask, like do two positive electrons propel each other too? And if they do, then that means it's like symmetric. That's right. It's symmetric in charge.

If you flip the charge and you get the same thing, then it's symmetric in charge. And so we call that C for charge symmetry. And we ask that question about everything. And electromagnetism is charged symmetric. Everything that happens in electromagnetism would happen the same way if you flipped all of the charges, not just one, but all of the charges. Right. Okay.

And then the second one is called P for parent. violation. And that says, would the same thing happen if you did it in the mirror? So if you set up some particle experiment or particle decays to two other ones or two particles collide into each other or whatever. And then you put that experiment in front of a mirror. The thing that happens in the mirror is not exactly the same as the thing that's happening in real life. It's flipped in one dimension. Yeah. A mirror will flip like the Z axis, for example, the axis perpendicular to the mirror, but not the other two. So for example, if you hold a your left hand in front of a mirror, then it looks like your right hand. It doesn't look like

your left hand. And so your hand has parity. It's not parity symmetric, right? Because it doesn't look the same in the mirror. It doesn't look the same. But like a like a ball does sort of look like a perfectly round ball with no drawings or features on it, does is parity symmetric because it looks the same in the mirror. Exactly. So for a long time, physicists thought that all of particle physics was charged symmetric and parity symmetric because it just sort of made sense, right? And physicists like to do that. They say, the universe is beautiful and natural and so it should follow this rule. Right. Like it'd be weird if the electron looked like my right hand in front of the mirror, kind of. Or if you had electrons for hands, that would

also be weird, but for different reasons. And for a long time, everybody assumed that everything followed all these rules. And then in the 50s, people realized, oh, nobody'd ever actually checked this for the weak force. We had a whole episode we dug into how the weak force actually violates parity. Interesting. Yeah, if you have a reaction in the mirror, it looks different than the reaction you're having like in your actual laboratory. And when we're talking about these, these are particles, right?

So they don't have features like hands, but they'll do things like they'll turn a certain way in a magnetic field or they'll react a certain way when they hit something else, right? Yeah, the experiment that discovered the violation of parity did just that. It like takes a bunch of nuclei, aligns them in a magnetic field, and then watches the direction that they emit electrons. like in the same direction as the magnetic field or backwards. And so that's a fascinating experiment that if you're interested in, you should dig into that whole podcast episode.

But for a while, people thought, okay, parity is violated by the weak force. What about the combination of charge and parity? So put it in the mirror and flip the charge. So that says, will an electron look the same if you put it in the mirror and turn it into a positron? I see. And then we discovered that the weak force actually violates this, Also, so we call this CP. If an interaction or a particle physics thing that happens violates CP, it means that it doesn't

look the same when you flip the charge and put it in the mirror. So the weak force violates parity and it also violates charge and parity. That's right. Now, it violates parity big time. It's like a really big violation. And that was a Nobel Prize. And then people thought, well, it must then preserve CP. It must be that parity is violated, but the comment.

of these two things is still preserved. Then they discovered that it violates CP, and that was another Nobel Prize. Oh, man. So that's the weak force. The weak force violates CP. And that was sort of surprising, but then people realized, well, why not? I mean, why shouldn't these things violate CP?

They looked at the way that we write down these interactions and the way we understand these theories, and we say, well, it's actually totally natural for them to violate CP. So, like, the theorist went from, that's impossible, it's absurd, to actually make perfect sense. All right. Well, it sounds like there's a lot going on with the weak force here. It violates all kinds of symmetries. And so let's talk about some of the other forces and how that could maybe lead people to come up with a brand new particle called the Axion. But first, let's take a quick break. I'm Dr. Scott Barry Kaufman, host of the psychology podcast. Here's a clip from an upcoming conversation about exploring human potential. I was going to schools to try to teach kids these skills and I get eye rolling from teachers or I get students who would be like it's easier to punch someone in the face.

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All right, Dinah, we're talking about a potentially existing particle with a cool name called the Axion. And you're telling me that it's definitely related to this idea of the CP problem. which is like a problem in theoretical physics about the symmetry of particles and whether or not they act the same way in all kinds of situations.

And so we talked about how the weak force doesn't follow parity or charge parity symmetry. And that's now become the normal. Before we gave people a Nobel Prize, we're figuring that out. But now it's like, okay, that's the way it is. That's right. We realize that it's actually not outrageous

for the weak force to violate CP. And then we looked at the other forces, we said, you know, the same thing that allows the weak force to violate CP, why doesn't it also allow the strong force to do it? Like the strong force could also violate CP, no big deal. It has the sort of same freedom inside it. It also interacts with corks, which is what the weak force does when it violates parity. And so people thought, oh, well, the strong force, maybe that also violates CP. But it doesn't?

But it doesn't. And we've made really, really precise. measurements of this, like crazy precise measurements. And so the strong force observes CP sort of for no good reason. Interesting. So like if you try the strong force, it seems to be symmetric. It follows the rules. It's like it follows the rules. It's the good citizen of physics. Yeah, it's like if you were watching people drive down the highway and every single one of them was driving exactly at the speed limit. No higher, no lower to like one billionth of a mile per hour. You'd be like, That's weird.

That would be suspicious. Precisely. And you'd wonder like, oh, maybe there's a speed trap out there or something like that. Or their engines are fixed or something. You'd look for a reason, right? Or they're all using cruise control. Yeah, precisely. And it's automated by the government or something.

And so that's what makes us wonder. We see this parameter in the strong force that would very naturally allow for the strong force to violate CP. But it doesn't. It's like this angle that would allow it is set to exactly zero. And that seems weird. It seems like it needs an explanation. And that's the strong CP problem is why doesn't the strong force violate CP? It's called, I just got it, Daniel.

It's called the strong CP problem because it applies to the strong force. That's right. Not because it's a strong problem. Yeah. Well, you know how some problems are called like the, you know, like in a, I don't know. The hard problem of consciousness, et cetera. Yeah, or in computer science. And they're like a, you know, strong.

There's the strong anthropic principle in the weak and things. orthropic principle. Yeah, there you go. Yeah, I'm not crazy. Those exist, but that doesn't mean you're not crazy. Okay, right. It's not an exclusionary. All right.

So it's a strong CP, but it's not actually a problem. It's more like it's like a strong, why does it follow the rules? Yeah. Question. It's not really a problem, right? Like, it's not causing any problem. It's just something that it's hard to understand why it doesn't break the rules. Yeah, it's not going to like fundamentally rip the universe apart or something.

It's not going to bring the apocalypse upon us or anything. don't have to call Bruce Willis. It's not that kind of problem. It's the, why does this work that way when it doesn't have to? You know, it's, it's strange. And anytime you see something unexplained and weird, a pattern you don't understand in physics, you've got to ask why. And you've got to think, is there a simpler explanation? Is there something that's making this happen? And so some people, I guess, had to think of this question, right? Because before you thought that was totally normal, it was following the rules. But now it's weird, suddenly became weird that it was following the Yeah, exactly. Once we realized the rules could be broken, we thought, hey, how come everybody

has been breaking the rules, right? Why is the strong force over there being so nice? You can drive as fast as you want in the highway? Why is everyone driving under the speed limit? Yeah, the weak force is like driving the wrong way. It's driving any speed. It's driving the middle of the night. It's like going off road. And the strong force is like driving Miss Daisy right down in the right, in the correct lane. Oh, man. All right. So that's weird. And so people started asking this question in the 70s? Yeah, it was in the 70s that people came up with maybe the first

answer to this question. People started asking this question basically after CP violation was discovered, which is just a few years earlier. And then people came up with this explanation and it's from Roberto Petchie and Helen Quinn. It was in 1977. And of course, their answer is

let's think up a new quantum field that fills the whole universe. Like, that's the go-to answer. Of course. Let's just add more things to the zoo. I know. And it feels complicated, right? It feels counterintuitive.

Like we're trying to simplify things. And to simplify things, we have to add a new complicated bit. Like, yeah, that's all right. That seems counterintuitive. But it's like, say you're trying to describe how an engine worked and you were missing the pistons. You'd be like, well, this doesn't really make sense. I'm going to add one more piece. Oh, look, it all clicks together.

Now it makes sense. And so sometimes you have to add one missing piece. in order to make the whole machine work or your understanding of the machine work at least. Right. Well, I imagine it's weird because, you know, really, you guys, I sort of just looking at some equations on a page, right?

But it's like, oh, if I could add just one number here, it would work. But really, you're like, you're adding a whole new field to the entire universe just by putting that number. Some of us, experimentalists, do more than just look at pencils and paper. You know, we actually go out and smash particles and try to make this stuff. Oh, sorry.

Yeah, you also look at computer screen. That's right. That is fundamentally different, okay? My wife used to always tease me that my research was just, quote, on the computer and therefore it wasn't real research. I see, you don't mix chemicals or you don't have to wear a lab code. I'm not wearing a lab coat, so how could it be science, right? I mean, you can, but it's just strictly cosmetic. That's right.

And so they thought of this field and they said, well, what if there's this new field that fills up all of space? and it's connected to the same field that controls the strong force this field of quantum chromodynamics the field of the gluons these particles that mediate the strong force and what if it talks to those it interacts with those

and it basically keeps it in line and so there's this new field created in the very early universe with everything else and it sort of pushes the strong force in the direction of having no CP violation I see but not the other forces

like it only somehow affects the strong force. That's right. It only affects the strong force. And it was created just with everything else. And then in the first sort of few moments of the universe, it pushed the strong force towards having a zero value for this angle that controls the CP violation. So not instantaneously. Like there may have been like a bill a second there in the very early universe where the strong force could violate CP. But then it was sort of like pushed in line by this other field. Really? But I guess my question is, why do you need this special field? Couldn't you just say that the strong force, that's the way it is? Like, it was born with this angle? Why do you need to bring in like a field that acts on it and then somehow disappears? Yeah, you could go with the non-answer, right? To say, you know, physics doesn't have explanation. So stop asking questions. You know, like, the numbers just are what they are. It's not really satisfying. You wonder, like, why is it this and not that? Especially when the numbers are a simple value. I mean, if the number is like 0.14,000.

217, you wonder what it is, but when the number is like zero or one, it hints at something else happening. It hints at something else controlling it. Just like seeing those people drive down the street at all the same speed. You wonder what's doing it. But I guess, you know, like how does adding a whole new field help? Because if you add a whole new field, then you have to ask, why does that field exist? Yeah, exactly. Just like you have to ask, why do the pistons exist in the engine? But if you think them up, it does simplify all the parts working together in the way that you observe. And so they thought up this field and they try to make it as simple as possible and it

very naturally connected to the strong force. And in that connection between the strong force and this new field forced the strong force sort of automatically to have zero CP violation. It's sort of like transforming one question into another. You're saying, you know, why is this angle zero gets transformed into why does this field exist? Sure. Okay. And I guess that's a more comfortable question for you guys because.

Because we like fields, man. Because then would I let you be out of a job? Well, also the field is something we could discover. Right? And so if this field exists, we can go out and find it. And then you can ask, okay, why does that field exist? Why do we need all these fields? Is it part of some larger strategy?

I don't know. But it is something that we can test. You can find, right? As opposed to like just some weird property of the strong force. Yeah, you can measure this property of the strong force all day long and say it's zero. that doesn't help you understand why it happens. If it can transform into its force to happen because this field exists and we can prove that field exists,

then we can start to think about the larger puzzle. And like, well, why this field? And does this mean other fields have to exist? And what does this tell us about the pattern of all the fields, which is sort of the larger mission of particle physics, is to understand how all the fields fit together into one? Right. And I guess it's not totally crazy because that's how they discovered the Higgs boson, right?

Like you thought of a field to patch something in your theories. and then you found the particle that belonged to that field. So it's all sort of been buttoned up. Yeah, exactly. The question there was like, why does the photon have no mass? And these other particles do have mass? Can you explain that?

And some people were like, hey, just accept it and move on, man. But Higgs was like, no, I'm going to create a new field that explains it. And he was right. And so now we can, of course, ask the question like, why is there a Higgs field? Dot, dot, dot, dot. We get to get on to the next question.

And so just like that, this new field creates a new part of it. And that new particle is something we could discover. All right. And so there's a fun story. And by fun, I mean crazy story about how it was name, how they named Axion came about. So tell us the story. So it's sort of funny for two reasons. First of all, Petchi and Quinn, who thought up this field, forgot to name the particle.

Wow. Like they came up with this field. And of course, naturally, if the field exists, then it's possible for the field to get like an excited bundle of energy, which we call a particle. But they didn't name the particle. And then so another physicist came along, Frank Wilczek, who's famous and won a Nobel Prize for understanding how quarks interact with each other with the strong force, he decided to name it. He's like, well, let's think about this field and how we might see it. And of course, he thought about the particle, and then he had to give it a name. No, he got to name it, but the particle already had parents.

How can you just go in and name somebody else's kids? Say you met a family, and they didn't give their kid a name. You would probably come up with a nickname for it, right? You wouldn't want to say that kid's name. No, I would tell the parents to give him a name. I would ask the parents, what do they call? What do they say when they want the kid to come over? Well, then you are more modest than Frank Wilczek, which is true for almost all of humanity anyway.

Oh, my goodness. So wait, but did they name, did Pesci and Helen Quinn name the field at least, or did they just say like a field? Yeah, a field. They just gave it a mathematical symbol, right? They didn't give a name to the particle that comes from it. And so, you know, if Frank Wilczek had been less modest, he would have called it the Petchy Quinn particle or something. Or the field. Or what did Frank Wilczek call the field? Yeah, well, now it's called the Axion Field, actually.

Oh, man, he totally took it over. He totally took it over. And on top of that, he gave it a totally ridiculous name. Like, Axion is a cool name, but he got the idea when he was grocery shopping. Oh, no. What happened? He was in the aisle for laundry detergent, and he saw this laundry detergent called Axion detergent, booster and he thought axion that's kind of a cool name oh no well he was what was you thinking like this particle that I'm usurping and stealing from this other other physicists would clean everything up

pretty well so hey laundry detergent makes perfect sense it's a physics booster so we need a detergent booster yeah so somebody in some marketing department created the name for this laundry detergent which ended up naming a theoretical particle no but didn't they copyrighted write it? Can you do that? That's a great question. Can you name a particle after like copyright? Can you name a particle like the Nintendo Switch particle? Yeah. Or like the Netflix particle. Can you do that? You know, that's a question for our legal department. For the physics lawyers. You stumped me on that one. That's right. The physics lawyers of whom I am not won. And, you know, there was competition. There were other famous Nobel Prize

winning physicists like Stephen Weinberg. He wanted to call it the Higgs Lit because he thought, Oh, this is, it reminds me a little bit of the Higgs boson. So he wanted to call it the Higgs lid. I thought you were going to say he wanted to name it Chlorox or Kleenex or the Tidino particle. No, and Axion sort of stuck. And, you know, these things are not fair and they're not always done the right way. Like we talked about how quarks are named quarks because a famous physicist came up with the name, even though a young physicist came up with the name Aces before that.

And it was sort of buried in obscurity. Oh, boy. These things are not always done correctly. They're not always given to the people who, to the parents, you mean. That's right. Yeah. It's not always fair. It's just sort of like what people end up calling something. All right. Well, let's get into why this action is super duper cool and why we think it could be real. But first, let's take a quick break. I'm Dr. Scott Barry Kaufman, host of the psychology podcast. Here's a clip from an uprook.

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It's easy to just drink the extra beer. It's easy to ignore, to suppress, seeing a colleague who's bothering you and just, like, walk the other way. Avoidance is easier. Ignoring is easier. Denials is easier. Drinking is easier. Yelling, screaming is easy. Complex problem solving. Meditating. You know, takes effort. Listen to the psychology podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Have you ever wished for a change but weren't sure how to make it? Maybe you felt stuck in a job. a place or even a relationship. I'm Emily Tish Sussman, and on she pivots,

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Listen on the iHeart radio app, Apple Podcasts, or wherever you get your podcasts. All right, Daniel, we're talking about the Axion, and it got its name from a laundry detergent, which is, I guess not too surprising in physics, because, you know, I'm I'm not impressed by the general imagination in naming things. But it is a cool sounding name, at least. You know, it satisfies your transformer principle. Well, why didn't he steal Megatron's name, you know? Optimus Prime.

Yeah, maybe they had better lawyers, right? The detergent company's lawyers are not as good as the Transformers. As the Hasbro. Yeah, that is a little bit scarier. All right, so you were telling me that this particle is cool because it would answer the question of why the strong force does not violate some of these symmetry conditions in the universe and that but it could also be cool because it explained another big problem yeah there's another big problem in particle physics which is where is all the

stuff right we know that most of the stuff in the universe is not made of quarks and electrons or any other kind of familiar matter it's made of this new thing that we call dark matter even though we don't really know what it is and just like with the other sort of physics mysteries we see evidence for it and how galaxies spin and how light bends through space, but we don't know what it is and what it's made out of. So it's one of the biggest pressing questions in particle physics or I think in modern sciences. What is 80% of the matter of the universe? What is dark matter? Right. And so it could be axiots. It could be laundry detergent. It could be exactly. The dark matter could be scrubbing the universe. Oh, no. It seems ironic that dark matter would be something that's

supposed to get the stains out. Yeah, precisely. Well, it satisfies a lot of the requirements you need for dark matter. It doesn't interact with normal matter, so we wouldn't have seen it. That's what makes it dark. It has some mass to it, although it's very, very light. So if it were dark matter, you would need, like, a ridiculous number of these things. You need, like, $200 billion just to make the mass of one electron.

And we need enough to make five times as much mass as everything in the universe. And so, like, if axioms are the dark matter and they are real, then we are swimming and swimming in a bigillions of axions all the time. Meaning that if these particles exist and they explain this strong force problem, they could also be there, but we wouldn't see them. Like, they don't interact with the electromagnetism force. That's right. They don't interact with electromagnetism. And they do connect to the strong force, but only in this way that they make the strong force. not violate CP.

The field also has some other super duper heavy particles in it that do interact with a strong force, but they're so heavy that they essentially don't exist. And so we don't have to worry about them. And so effectively, axions are totally inert except for the fact that they have a small mass. And so if they have this mass, then they contribute to gravity.

And that's what dark matter is. It's something mysterious out there that's adding gravity to the universe. And so it could be the axioms. All right. Would that be sort of a coincidence that we have this particle and it just so happens to fill in the blank for dark matter? It would be amazing. Like, who wouldn't want to solve two big problems in physics at once, right?

You think of this particle to solve one problem and boom, it turns out to solve the other problem at the same time. You can collect two Nobel Prizes in one trip. Wow. I mean, that sounds pretty good. Do you get two? Like, do you get two in the same ceremony, I wonder? I think you have to come back the next year. I'm not sure.

But that's attractive, but it also makes you a little suspicious. We thought this particle up to explain the strong CP problem, and then we have this other problem. We're going to try to squeeze this particle into solving the dark matter problem. It actually sort of reflects something else about the dark matter problem, which is that we're getting a teensy bit desperate. Like, we thought we would have figured out dark matter by now. We had better ideas for what dark matter could be,

these weakly interacting massive particles, stuff like that. And none of that has really panned out. And so now we're sort of like dragging along the bottom of the bigger. looking for other ideas that might explain dark matter. And so that sort of led to a resurgence and interest in the axions. People think, wait a second, what about axions? Maybe those could be the dark matter. You're like so desperate you're reaching for the non-brand laundry detergent.

That's right, exactly. Is what you're saying. That's exactly where we are. And it could also maybe solve another big problem, right? It could. It could solve another big problem. There was a really fascinating paper out there last year that talked about those first few moments in the universe when this field was created and it forced the strong field to not violate CP.

And it turns out when it did that, it had sort of two directions it could go. Sort of like imagine a marble in an upside down hat and it's rolling towards the bottom. And that's how it forces the strong force to not violate CP. But if instead of just rolling straight down, what if it had like a little bit of a kick. So it sort of went around in a circle and then relaxed to the center. Then it could have done it clockwise or counterclockwise. Oh, boy. It's like another symmetry.

It's another symmetry. And it turns out if it goes clockwise, then the universe is filled with matter. And if it goes counterclockwise, the universe is filled with antimatter. Oh, what? It's like flipping a coin. We could have all been made out of antimatter. Yes. And that's a big question in physics.

It's like, why is the universe made out of matter or not antimatter? And we don't know. And it feels like a coin was flipped. And it could be that this was the coin. Oh. It was a laundry detergent coin. that determined the entire universe. Yeah, and so the axion could solve this other problem also.

So it really could be key to a lot of these big, big mysteries in particle physics. And I guess you're, because I imagine you were saying, this is not the only idea. Like, this is not the only field or particle that people have dreamed of, but this one is somehow more attractive because it sort of makes more sense? Well, because the other ones have been sort of ruled out. You know, you have your first idea. you go look for it. The experiment says, nope, sorry. Then you go for your second idea. You know, you just keep looking through ideas until you find one that the universe says yes to. And so that's sort of led to a resurgence. And, you know, also theoretical physics, there are trends. There are fads.

People get excited about an idea and they work on it furiously and then they get bored with it. Somebody else comes up with a new idea. And so the idea sort of have cycles, you know, people get bored of an idea, put it aside. And then 20 years later, some new young woman says, hey, I have found a new way to use this old idea. And then everybody gets excited about it again. It's a human endeavor, remember. All right. So then the action is trending, is what you're saying.

Like, it's having a surge in popularity. And so I guess the question is, is it real? Like, does it actually exist? And can I find it in places not my laundry detergent aisle at my grocery store? Well, we don't know, but there are experiments out there to look for it. Sort of two different categories of experiments, but both use magnetic feel. The idea is that the axiom is sort of like a photon, and it doesn't interact with photons normally, but it turns out that if you put the axiom into a super duper strong magnetic field, then sometimes it will turn into photons. What?

Yeah. Wait, a magnetic field can cause particles to change? Yes, the magnetic field will change the way the particles interact, right? It has energy in it, and if those particles can feel photons in any sort of way, then... and they can get enhanced and they can change the way they decay. And so the axion, if it's in a chamber that sort of resonates with it, and that chamber is filled with magnetic field. And this magnetic field is like 150,000 times the strength of the Earth's magnetic field.

Wow. Then it could sometimes turn into like little microwave photons. So they have this cavity up in University of Washington where they have it very cold and they have a very powerful magnetic field. and they're just listening for a little microwave blip. Wow. So we can't see them, but they might turn into things we can see them.

Precisely. Into these weird conditions? In very strange, very strong conditions, they might turn into photons. Really? You can predict that with the equations? The equations say it should happen. If you get the magnetic field at the right frequency

and you get it down to cold enough conditions, and they've been running it for a while and they haven't seen them, but they're sort of like tuning the magnetic field, like are they over here, Are they over there? And so far, they haven't seen anything. But it's sort of getting more and more powerful the device. Pretty cool.

So that's one way. What's the other way that we might see them? The other way is sort of the opposite is to try to turn light into axions. Like instead of having axions turn it into photons, turn that around, take a beam of light and try to turn it into axions by putting the light. Yeah. Like make light disappear. Yes. And so this experiment is called light shining through walls because you basically have a wall.

and a really strong magnetic field and then a beam of light and the idea is maybe the light will turn into axions which can then pass through the wall with no problem which will then turn back into light and so you can sort of like

have your light pass through the wall phased through the wall by becoming an axon as it's going through the wall I feel like you're getting to the point where you're like we need ideas

oh what's this is this a comic book what? There's a superhero that can go through walls oh that sounds like a great idea Yeah, well, it's pretty cool because if we figured out, then we could actually build beams of light that go through walls, right? So it's also sort of a cool experiment because you just need like a light beam and a wall, and then you just look for light making it through the wall, right? So it's pretty dramatic if you see something. It's like magical x-rays.

Yeah, yeah, turning light and x-rays, making them penetrate just like x-ray to do. And it's pretty fun, you know, to see these experiments. These are clever ideas. these are wacky ideas. And personally, I never expect these experiments to actually discover the axiom. What? No. Aren't you?

Isn't this your field? This is my field, yes. But the axion has always seemed sort of, I don't know, out there to me, like too crazy an idea. It just feels like a little bit out there in left field. You're like, it's too sudsy. Yeah, it's a little too sudsy. Like I read this interview with Helen Quinn, one of the two people who came up with the original idea. And even she's a little amused that this.

idea still lasts. Really? She's like, I don't know what all the fuzz is about. Yeah. The direct quote from her is, Roberto and I spent a few months cooking up this theory, and now the experimentalist has spent 40 years looking for it. She's laughing at you, Daniel. It's like she's, she's amused by you. The whole thing was a joke to begin with. What are you guys doing, wasting your time? You're like, that's why we didn't give it a name. It was all a big practical joke. Yeah, the whole thing. And then we planted the detergent for Frank Wilchick to find it. Yeah, using their time travel device, right? Their magical x-ray light.

But it's fun. And, you know, sometimes an idea can begin from a silly place. Right. Just exploring, just futzing around with the math and then turn into something real. I mean, if the axon is real and it solves these big open questions in physics, then that would have been a productive few months cooking up that crazy theory. A productive 40 years. Because, you know, like it's almost like the Higgs boson, right?

You predicted it and like 40 years later, they found it. Yeah, it took almost 50 years. to find the Higgs. So sometimes you come up with a theory for a particle that's really, really hard to find. It's not always easy to go and just look for this thing. Even if you know what it's supposed to do and how it's supposed to look, creating those conditions to find it is not always easy, especially if it's elusive.

I mean, if it's the dark matter, then it's been hiding for a long time. And the stakes are pretty high. Like, if you find it, it would explain so many things, including dark matter and antimatter and strong CP problem. Yeah, it would really close off a lot of big open questions. questions in physics. So from that point of view, I sort of hope it is real because it would be a fascinating insight into the universe. And then, like as always with physics, we get to ask the next question. Like, all right, well, why is there an axion? What does that mean? Is there

another axon? You know, there's a whole spectrum of axon particles. And so the questions never really end. Right. I wonder if there are lawyers at the Axion Corporation, they're like just waiting for you guys to discover it to give them that marketing boost in popular culture. Or that's when they're going to suit, right? Yeah, there you go. They're waiting. Like, we own this. You can't make x-rays light special laser beams without us.

That's right. We demand you pack up all your axions and boxes and send them to us immediately. All right. Well, I think, as usual, this just points to the things we don't know and how, you know, science is actively still trying to explain the universe. That's right. And in a hundred years, we could look back and think, what was it like before physics knew about the axion particle? or the chlorox particle or whatever it is we're going to discover in 20 years. But before we know it, it's just an idea.

It feels very different to be on the ignorance side of a discovery than on the knowledge side of it. Because you never know what could turn out to be true. That's right, because the universe is no strangers to weirdness. All right. Well, we hope you enjoyed that. And the next time you're going down the grocery store, laundry detergent aisle, look around. You might discover a new particle that explains the universe. So keep your eyes open.

Or at least discover a cool name for somebody else's good idea. There you go. Thanks for joining us. See you next time. Thanks for listening. And remember that Daniel and Jorge Explain the Universe is a production of IHeartRadio. For more podcasts from IHeart Radio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. Why are TSA rules so confusing?

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