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How did we discover neutrinos? What don’t they make any sense? Why do they have mass, and how do they change their identities? I discuss these questions and more in today’s Ask a Spaceman!

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Music by Jason Grady and Nick Bain. Thanks to Cathy Rinella for editing.

Hosted by Paul M. Sutter, astrophysicist and the one and only Agent to the Stars (http://www.pmsutter.com).

 

EPISODE TRANSCRIPTION (AUTO-GENERATED)

This break is brought to you by Adobe Photoshop. Here's a fun fact. Every day, millions of people around the world use Photoshop to create all kinds of cool stuff. Designs for t-shirts and posters, graphics to promote brands and businesses, images for social and websites. Anyone can do it. And to the guy who put a bulldog's head on a parakeet's body, you, sir, are a genius. Get started for free today. Click or tap the banner to head over to Photoshop dot com. Neutrinos annoy me. They frustrate me. Thinking about neutrinos gives me a headache. They drain me mentally, physically, even spiritually. Trying to understand neutrinos shortens my life. Every time I try to think about neutrinos, I can feel a connection between my neurons snapping. I think neutrinos are making me dumber. But you asked. Some of you want to understand them. Some of you say it's your favorite particle. I don't I don't get it. But I always tell you that if you ask me questions, I'll answer them on the show.

But this is going to be tough folks. Part of the reason is that neutrinos just live complicated lives and are prone to lawlessness. They make the rules, not us. They are indecent. They violate all social norms and common sense. They don't care about you. They don't care about me. They don't care about anything that makes this universe great. The other part of the reason is that we don't understand neutrinos, which is very frustrating. I mean, yes, we don't understand most of the universe. That's physics, and that's science. And that's job security. And that's OK. But we can make neutrinos in our laboratories. We can capture them. We can figuratively hold them in our hands. And yet we still can't fully explain them. That's frustrating. When I can give you a neutrino, I say, Here's a neutrino and you say, Well, what's up with neutrinos? I say, I don't know. But here it's yours now that's a frustrating experience, and we're going on nearly a century of neutrino mystery. So this is becoming a generational thing.

So we're all going to take a deep breath. We're gonna get tough, we're gonna talk about neutrinos, and we're going to get through it the only way I know how to get through tough situations. Jeez, no, but that would be nice. with an abundance of bad metaphors. So let's dig in. The particle nastiness that is the neutrino was first hypothesized when experiments in the 19 twenties went wrong, which shows you just how bad this road is that we're about to go down. It worked 100 years ago, and nobody asked for neutrino. We found them because things weren't making sense. Back when particle physics was first becoming particle physics, we found something called beta decay. And don't worry about the name. That's another show. In beta decay, a neutron could sometimes randomly become a proton and electron, just like whatever changes mind. I'm done being a neutron. Here, have a proton electron. I'm outta here. That's fine. I mean, it was weird at first, but then we figured out nuclear decay in general, and we got used to it.

But measurements of the proton and electron revealed something weird. They didn't have enough energy because all these particle interactions and decays or whatever they have to obey certain rules, and you just can't just do whatever the universe feels like doing the amount of electric charge coming into the interaction. Whatever you start with, has to be the same on the other end. Like like you start with a neutron electrically neutral, and you end with a proton, which is positive, and electron, which is negative. They cancel each other out, and so that's neutral again. So neutral on one side, neutral on the other. Everyone's cool, but you also have to obey things like conservation of energy and conservation of momentum. The energy and momentum you have coming into the reaction or interaction has to be the energy and momentum we have coming out. And it wasn't coming out when we added up the energy and momentum of the electron and the proton in this beta decay reaction, it didn't add up to the original momentum and energy of the neutron.

Hence problem. There had to be something that was stealing some of the momentum and energy from the decay, and it had to be electrically neutral because you can't just, like, decide to have extra charge that's not allowed. It had to be very, very small, possibly even massless, because it was only carrying away a tiny, tiny bit of energy and momentum. And so a name was suggested as a kind of a joke. The joke was Italian for little neutral one or neutrino. The fact that this particle guy's name as a joke is another bad sign of just how monstrous and horrible these particles are. But OK, fine. Whatever. In the 19 thirties, we decided that neutrinos exist. Whatever. There's a new particle. It's weird. Fine. Uh, everything was great. Neutrinos were just another particle hopping around the universe. No big deal. I mean, they were completely and totally unlike any other particle in the universe.

But, you know, that's what you get when you didn't even theoretically predict a particle, you only found it because you were looking for something else. Neutrinos are weird. So neutrinos, uh, were long thought to be massless. Don't worry. We're gonna get into that can of worms soon enough. But for a long time, we thought they were massless, so OK, so they're like photons light, but not really 00, and they can't take part in nuclear reactions. Uh, they they don't participate in the strong nuclear force, so they're kind of like the electron which doesn't participate in the strong nuclear force, but not really not electron at all. They don't have electric charge so they don't interact with anything through the electromagnetic force. So they're like a neutral particle, like a neutron. But you know, not really at all. And they do experience gravity because everybody experiences gravity. But because of their mass lessness or near massless, this is not. That's not really anything to write home about, Really. The only thing they do is talk to normal matter through the weak nuclear force and the weak nuclear force is, you know, kind of weak and really short range.

And so neutrinos are just there. They're a byproduct of all the nuclear reactions going on in the universe. So when we see nuclear reactions happening, neutrinos are usually involved because the weak nuclear force is used to mediate nuclear decay and interactions and fusion and fission and all that. But then neutrinos just pop out of that interaction, and then that's it. They don't really do much anything of note except steal a little bit of momentum here and there, like there are. There are trillions of neutrinos passing through your body right now because our sun makes a lot of neutrinos. Radioactive decay in the earth makes neutrinos of existing supernovae pumping out neutrinos that are swimming across the universe. They're flying through you right now, but they don't interact with normal matter. Hardly ever. Rarely they do. But it's so rare that even though trillions of neutrinos are passing through your body, every single second literally trillions, you will live your whole life without any one of those interacting actually interacting with your body.

You're just awash in this sea of invisible particles. Some people call them ghosts. Some people call them ninjas, which are pretty cool. But no matter what, they they were curiosity. It's like, Look at this little freak particle. It's kind of weird. We call it The neutrino doesn't really do much, You know, the the the electrons and Fons and Z bosons are doing all the cool stuff in the universe and the neutrinos. Who cares? And, yeah, there were different kinds of neutrinos. We eventually discovered that which didn't really surprise anyone. Once we discovered that there were multiple flavors of every particle, so right flavor. This is one of the most annoying terms in particle physics, and trust me, there are a lot of contenders, but we can't talk about neutrinos without talking about flavors. Another word for flavor is species. There are different species of particles, which in my mind makes a billion times more sense. When I'm not in charge of any of this, I would rather say there are different species of particles rather than there are different flavors of particles to dig into this, uh, the trouble started when we discovered the muon.

The muon is another fundamental particle that's just like the electron has the exact same electric charge. Same span, same properties. But it's heavier. It's more massive. It's like the older sibling of the electron. It's the exact same thing, just like bigger. Whatever right we We call the electron one flavor or species, and the muon is another flavor or species. It's just like the electron, but a little bit different. But as soon as we discovered the muon, we knew that there would be another flavor of neutrino. That's because whatever arcane particle reaction you've got going in your laboratory, certain rules have to be applied in the way the weak nuclear force works. Different flavors can't participate in the same reaction. So if you got one flavor going on in your reaction, doing its thing. You're only ever gonna get that same kind of flavor on the outside. So, for example, if your reaction deals with electrons, if electrons are participating like in beta decay, you're gonna get the same flavor of neutrino.

You're gonna get the corresponding species of neutrino, a kind of neutrino that matches up with electrons. Uh, something we now call the electron neutrino. I know it's not a very evocative name, but it gets the job done, I suppose. And if you're doing a different kind of nuclear reaction and you're dealing with muons and muons are playing around, then you're going to get muon neutrinos. It's a different flavor. It's a different species of neutrino that only talks to muons only works with muons only hangs out with muons, only goes out to dinner with muons. You'll never see an electron neutrino hanging out with a muon. You'll never see a muon neutrino hanging out with an electron. By the way, the original name for muon neutrinos was new Reto, which is horrible, and I'm glad we moved past that. So OK, there are two flavors of electrons or two species of the electrons we call one of them the electron because, of course we do, and we call the other one the muon, and they're the exact same, except one's heavier.

And then there are two flavors or species of neutrinos, the electron neutrino and the muon neutrino. Now I bet you're asking, or you're wondering if the muon neutrino is heavier than the electron neutrino and hold that thought. Because at the time when we were figuring this out, they're all massless. They were just the only way to distinguish a muon neutrino from an electron neutrino was the kind of reaction that it took part in. That was it. But then we discovered the tau particle, which is like the electron in the muon, but even heavier. It's like the older, older sibling in the electron family. It's a new flavor or a new species of electron. And guess what? There's a corresponding sibling in the neutrino family, no points awarded for guessing what it's called. It's called the town neutrino. It's like the members of each family. Those three siblings, the neutrino family and the electron family will only talk to members of the other family of the same age or size. So an electron talks to an electron neutrino. A muon talks to a muon neutrino and a tow talks to a tau neutrino.

And that's it. OK, so we've got three species of electrons, three species of neutrinos. This is getting a little bit ridiculous, but we can handle it. And then we discovered Antiparticles. You know, antimatter is the exact same as normal matter. But opposite charge, like the electron, has an antiparticle called the positron. So it's cool. Like if you take an electron as like your base particle and you, the only thing you do is change its mass. You get a new flavor in this case, the muon. If the only thing you change is its charge, you get the antiparticle corresponding to the electron, which is the positron. There's an antimatter version of the muon and the Tau. Neutrinos don't have electric charge, but they can still have antiparticles. Because why not? So we have anti electron neutrinos. We have anti muon neutrinos and anti tau neutrinos, and I hope you can start to see why this is getting a little annoying. It's just so cumbersome to have all these families and charges and flavors and species and whatever you want to classify them running around the universe, it just makes things complicated and not very fun.

On the other hand, it is a little bit messy because now we've got our three species of electrons three species of neutrinos. Everyone has an antimatter partner. But there is a certain kind of symmetry here. And I wanna mention you remember quarks, right? You know, there are six quarks up down, top bottom, strange in charm. Well, those are the six flavors of quarks. There are six species of corks and we have cool names for them. And OK, so there are six species or six flavors of these so-called leptons the electrons beyond towels. And then the three neutrinos six and six. Everyone's paired up. Why all these flavors? Why six flavors of each? Nobody knows. It's just the way the universe works, but at least neutrinos filled out all the gaps. So everyone has a partner and all the particles can doy dough. I told you the metaphors would would be bad here, so OK. For the first couple of decades, it was getting messy, but so was all of particle physics here. To be honest, and we just had a lot of neutrinos happening.

We had our three flavors. They each had an antimatter partner. They were essentially invisible and still just hanging out around the universe, and no one cared. And then in the 19 sixties, we looked at the sun, and that was a very bad idea. We want to look at the sun because we're trying to understand neutrinos and neutrinos pop out of nuclear actions. If you have a nuclear reaction, neutrinos are somehow gonna be involved. It's basically the only thing they do in the universe, and the sun is a giant ball of using plasma. And so it's popping out neutrinos all the time. So if we stare at the sun with a neutrino detector, where we're gonna see a lot of neutrinos, so that's exactly what we did. And the first one to do this in a big way was the Homestake experiment, which is when in in an abandoned gold mine in South Dakota. And this is not the beginning of a ghost story unless, you know the the neutrinos are the ghosts. But never mind. The problem that we had with this experiment is when we loaded up our neutrino detector and let it soak in all those neutrinos coming from the sun.

We only got about a third to a half of the neutrinos that we were expecting. We were able to calculate how many neutrinos the sun could spit out because it's just based on its nuclear fusion rate. But it wasn't matching up with what we were seeing. So either we didn't understand nuclear reactions in the sun or we didn't understand something about neutrinos, and, uh, and there was considerable debate. But as the decades wore on, we became super confident about our knowledge of the sun, and we became super confident about our knowledge of neutrinos, something you had to give. Where were the missing neutrinos? The answer, folks, is that neutrinos are annoying. I'll give you the short version now, and we'll dig in a little bit more later because, as usually with episodes on particle physics, it just becomes a tangled morass of confusing and pointless jargon. And we'll all need to anchor on something tangible. And if there's one thing and one thing only I want you to take away from this episode, it's that you need to go to patreon dot com slash PM Sutter to keep supporting the show.

I really, truly do appreciate it. But if there's a second thing to take away from this episode, it's that neutrinos can change flavors as they travel. Yeah, this is Oh, gosh, I can make it an an electron neutrino gun that's really, really good at shooting electron neutrinos, This flavor, this species of neutrino, and I'll point it at you and blast you with electron neutrinos. But on their way to you, they can change into muon neutrino or town neutrinos, or not change at all. It depends on how energetic my electron neutrino gun is. It depends on the distance between us. It depends on what's filling the space between us. So I can shoot you with electron neutrinos coming out of my gun and then what you actually receive in your body? I can't tell you. Without a lot of complicated math, I can tell you it's not gonna be 100% electron neutrinos. I told you it was complicated, folks, but But how can neutrinos do this? How can they change their flavor?

Why can neutrinos do this? Who asked for this Why Why do we have to deal with this? But nobody does this. I shoot you with electrons. You get hit by electrons. I shoot you with protons. You get hit by protons. Very simple and straightforward universe here, but not neutrinos. Neutrinos are not the only particle that can change flavor as it moves. Uh, there's something called the canon that can also do it. But this isn't a kaon episode, but feel free to ask. That's one heck of a rabbit hole, but that's like a special case, like cans are super weird. You can only make them in a laboratory in extreme environments. So you expect weird stuff to happen in laboratories and extreme environments, not day to day stuff. This phenomenon, though, is called oscillation in the physics jargon, because why not? And the big deal here, besides the raw fact that neutrinos can oscillate, is that the only way we can get neutrinos to oscillate is if they have mass.

I'll explain how in a little bit, but just hold on with me here First, I need to address the question of why is this a big deal? Who cares if neutrinos have mass or not all of physicists care. All of them, every single one of them care if neutrinos have mass or not, and every single one of them paid attention when we first figured this out in the sixties and seventies. The reason is because the standard model of particle physics, which is our theory of the universe, is like our theory of how physics works at a fundamental level. Predicted that neutrinos should have no mass, the standard model of particle physics. Our most successful, well tested theory of nature ever said very clearly. Hey, neutrinos don't have mass move on with your life. But here they are changing flavors, and the only way to get them to change flavor is if they have mass and I. I swear I'm gonna explain that. But if they have masks that would violate all laws of physics and also human decency, why did the standard model predict that neutrinos don't have mass?

I honestly debated whether or not to try to explain this in the episode, but I figured we're already in this stew. We might as well just keep on cooking folks. The reason that the standard model predicted that neutrinos don't have mass has to do with something called He Electricity. I warned you, but imagine a bullet. I shoot you with a bull. I know there's a lot of violence in this episode, and I apologize. Imagine I shoot you with a bullet and the bullet is spinning. It's It's traveling and it's spinning. The spin can be in either direction. It can spin this way. Or it can spin that way as it's traveling, either the spin, the direction of the spin, the axis of the spin can be aligned pointing in the same direction of its movement. We call that a right-handed holic, or the spin can be in the opposite direction. If you're like watching the bullet from behind and it's spinning clockwise as it's traveling away from you, that would be right handed. He And if it's spinning counterclockwise, it's called Left-handed.

He I don't know why we don't use clockwise and counter just moving on. So that's the thing. Just fact particles can do this. Check this out. Usually, particles have both left and right handed versions like, you know, if I shoot you with my electron gun, some of the electrons are gonna come at you with right handed. He and some are gonna come at you with left-handed. Holly. You know, no biggie. Who cares? But neutrinos? Oh, no. Oh, no, no, no, no. They just have to go and be weird. All neutrinos. And I mean, all neutrinos are left handed and only left handed. And all anti neutrinos are right-handed and only right-handed. Seriously, every single neutrino that we have ever measured and observed or interacted with have left handed. He electricity, All of them. Why? Well, well, no one knows. It just is. I shoot you with electrons, you'll get both right and left handed ones. I shoot with neutrinos. You'll only get left-handed ones only 100% of the time. Who cares about all this handedness?

The standard model of particle physics does because it turns out that all particles in the standard model are predicted to be massless I. I see. You see why I didn't want to go into this. I've done episodes before on the Higgs boson, the Higgs field, the Higgs mechanism very, very quickly. Here. The Higgs field is a thing that permeates all of space time, and it like talks to people It's very friendly talks to the electrons and the quarks and the bosons, and it's just very, very chatty. And this interaction between the Higgs and these fundamental particles is what gives them mass. So particles by themselves don't have any intrinsic mass the same way they have, like intrinsic electric charge, they only acquire Mass through their interaction with the Higgs field. Like another way to say it is the mass of a particle is its interaction with the Higgs field. And the only way to make that interaction work is if there are both left and right handed varieties just the way the symmetries have to work out in the mathematics.

The Higgs field is very, very chatty Field that likes to interact with lots of particles likes to party, uh, only likes to talk with. If you have both right handed and left-handed versions, that's the only way the math comes out. But neutrinos only have one variety. They're only left-handed neutrinos. And yes, the anti neutrinos are right-handed. But that doesn't count. Neutrinos are only left handed. They don't get to talk to the Higgs, and if they don't talk to the Higgs, they don't get Mass. It's just that simple. In the standard model, like the Higgs is walking around the party. He's like, Hey, electron, how's it going? Top core. How are the kids? What's up? You know, uh, but then sees the neutrino and just just walks on by because there aren't both left-handed and right-handed versions of neutrinos. So the standard model of particle physics very cleanly very clearly says neutrinos do not have mass, but But they do. They do have masks. They do have mass because we observe them oscillating flavors. We see them changing flavors. If you give neutrinos mass, it can explain the oscillation because, wow, we're gonna get into that for now.

Let's just say they're not supposed to according to the standard model, but observation experimentally, they do have mass. Hence nobody understands neutrinos, and I'm getting a headache. Speaking of headaches, this whole oscillation thing is a nightmare and a half for one. It makes experiments really, really complicated because you can't just build a thing that generates and detects electron neutrinos or muon neutrinos or town neutrinos. No, because they're all gonna mix with each other, as we found with home steak. When we thought the sun was producing a lot of electron neutrinos, and it is. It is producing all the electron neutrinos that we thought it would produce. Our models of solar physics were not wrong at all. Once we built the right kind of detectors to find the other flavors, we were able to get everything added, added up. But that's like a lot of experiments, so that's like complicated. Second, it makes no sense. How does this mixing of flavors of species actually work? It's like ice cream.

Yes, this is the best thing I could come up with. Let's say there's a brand of ice cream that you really love. It's called electro cream because, of course it is. It's amazing. It's creamy. It's indulgent. It's awesome. For a long time, electro cream only came in one flavor and one size chocolate small like pint small thing of chocolate. That was what was sold. That was what you bought. Simple, delicious life was good, Like, man, I'm really hungry for some electro cream. What are you gonna get? You're gonna get a small container of chocolate. That's it. But then one day, the folks behind electro cream came out with another flavor vanilla, and they only sold this one in its own size medium, so you can get small chocolate or medium vanilla, but not satisfied. You demanded a third flavor and you got it. Strawberry, this time large. So here are your three choices of electro cream chocolate, vanilla and strawberry. Those are your three flavors in each. One of these flavors corresponds to only one size. If you want chocolate, it's a small If you want vanilla, it's a medium. If you want strawberry, it's a large.

If you want a medium, it's a vanilla. If you want a small, it's a chocolate. If you want. A large is a strawberry. This makes sense. This is easy. But then a competitor came along. There wasn't just electro cream. There was new cream. New cream was different. New cream was radical. New cream was a disruptor. New cream was extreme. New cream comes in three sizes. Small, medium and large. But what flavor is it? Chocolate. Is it vanilla? Is it strawberry? No, it's Neapolitan. It's a mix of all three flavors. Chocolate, vanilla and strawberry, all in the same box. But guess what? That's not radical enough instead, It's not just any Neapolitan folks. It's funky Neapolitan. What does that mean? It means you never know what you're going to get. The truth is, all of this was a marketing gimmick by the makers of new cream used to disguise the fact that they have no idea what they're doing. They have machines that are supposed to make chocolate, vanilla and strawberry, and they'll put those labels on the boxes just like their competitors.

Electro cream. But sometimes the chocolate machine makes vanilla. Sometimes it makes strawberry and sometimes even chocolate, and sometimes they'll put chocolate in and close the lid, and then when you open it, it's strawberry or vice versa. What you see on the label doesn't always match the contents. Unlike electro cream, there is no relationship between the size of the container and the flavor. You don't know there's no connection with electro cream. The size and the flavor come hand in hand, like hey, pass me a small electro cream. You know you're gonna get chocolate. You're like, Hey, hit me up with that large new cream. You don't know what you're gonna get. There's no connection between flavor and size and the label isn't helpful like you're, it's a top and it says this is large new cream and you you don't know what's in it, and the makers don't know what's in it. They have no idea what their machines are doing. It's just weird. You have no idea what you're going to get. These are the neutrinos, obviously almost every single particle in the universe. And certainly the ones you encounter on a daily basis are like electro cream.

The mass matches the flavor. They're basically the same thing. I give you a muon. You know what you're dealing with. Mass flavor linked up the species and the mass are one and the same. The electron participates in certain nuclear reactions, and the electron has a certain mass period under story. The tow particle participates in its own set of reactions that the electron doesn't get to participate in. This is a tow flavored party only, but the tow is just gonna have the mass of the tow, and that's it. Different flavors or different species participate in different kinds of reactions that are exclusive to them, but it doesn't matter, really, like the Muan participates in reactions that allow for the muon. And then you got the muon mass. But neutrinos? Nope, Nope, nope, nope, nope. No, no, that's too boring for neutrinos. Instead, each and every flavor of neutrino is actually a mixture of three different masses of neutrinos.

And now you see why I had to wait till the end to talk about this in the lamest language possible physicists call the three masses of the neutrinos M one, M two and M three. And because particles of different mass travel through space with different speeds. When I make a neutrino, say an electron neutrino and it travels to you, that electron neutrino is actually made up of three different masses of neutrinos M one, M two and M three. They all combined together in order to form this electron neutrino. But as they travel through space because they have different masses, they go at different speeds. And these three masses interplay with each other in a very complicated way, phasing in and out in a very difficult to predict way. And then by the time it hits you, depending on the ratio of the masses, a different flavor of neutrino will appear. So, for example, This is just for example, let's say I make a tau neutrino, and a town neutrino is a certain combination of the three masses of neutrinos M one and M two and M three.

But this a town neutrino is when it's mostly M one and a little bit of M two and barely any M. Three. That's my tow. I shoot it at you. But then M one M two M three. These three. Like underlying neutrinos, they travel at different speeds. They phase in and out. Uh, sometimes M two is on top sometimes M three. Sometimes M one is back on top. And then whatever is the ratio. When it hits you boom, it hits you. Maybe at the moment it hits you. M two is the most prominent component and then followed by M one and M three. And then that presents as an electron neutrino confused. Good. This is why neutrinos give me a headache. And it was a mistake for you to ask. We have three flavors of neutrinos the electron type, the muon type and the tau type. We also have three masses of neutrinos the M one, the M two, and M three. These two sets don't match up. An electron neutrino is really a mixture of M one, M two and M three and a muon neutrino is a different mixture of M one, M two and M three and a tau neutrino is an even different er mixture of M one, M two and M three.

The mass of the neutrino is not directly connected to its flavor, which doesn't make any sense. It's easy to identify an electron or a proton or a quark or a Z boson. It has one set of numbers that completely and totally describes it. It's mass. It's electric charge. It's flavor. It's spin. It's just like I want to find an electron boom. Here's a list of properties that is what makes the electron the electron. The electron participates in certain kinds of reactions, as determined by its flavor or species, and it does so in those reactions with a certain amount of mass. Very reliable. But the neutrino identity is really this giant mixture of flavors and masses. There's no such thing as one neutrino identity.

It's a combination of three flavors and three masses. It just so happens that our experiments that we use to detect the neutrinos depend on the flavor, because the flavor is what tells you how you get to participate in these nuclear reactions and which nuclear reactions you get to participate in, like the flavor is the key. There are three different doors in our universe. Three different sets of nuclear reactions and your flavor is the key you're holding, and it only opens up one door. So if you're holding onto the electron flavor key, then boom. You get to open up the electron reaction door, and you get to participate in that set of nuclear reactions. If you're holding the tau key, you get to open up the Tao Door and participate in tau style Tiel flavored nuclear reactions. But the flavor of the neutrino, the key it's holding, isn't tied to its mass.

Instead, every neutrino that we see the electron neutrino, the town neutrino, the muon neutrino is really a mixture of three different masses of neutrinos, and it works in reverse. Like if we had experiments that could detect the mass of the neutrinos directly, like the only way this experiment works is if it has a certain kind of neutrino Mass. We would find that each massive neutrino say, Hey, here's an M one. Here you go. Hold on to this M one. The M one is really a mixture of electron, muon and tao flavors species. It works in both ways. This makes no sense, folks. This is hard to think about. It's hard to conceive of a universe where electron flavor is tied to electron mass. They're basically the same thing. But neutrino flavor is not that Every neutrino that we detect according to its flavor is really a mixture of three different masses of neutrinos, three different identities mixing together and competing with each other to add the problem.

We don't know the masses of the neutrinos. What is M one, M two and M three. We don't know. We don't know what their masses are. We have some limits on, like the total combined mass. But that's it. The limits. Though These things are tiny, they're 6 million times lighter than an electron, and the electrons are already pretty tiny. So when I'm saying neutrinos are nearly massless, they they really are. We don't know what the masses are. We don't know why the universe is arranged this way. Why is it that all the quarks their flavors match up with their mass? All the electrons and towels and muons their flavor matches up with the mask. Why is it different for neutrinos? We don't know and we don't know how they get their mass. Remember, that was a big question. Like just the fact that neutrinos have mass. We know now that they must have mass because we see them oscillating. We see their flavors changing the only way for their flavors to change. If each flavor of neutrino is really a mixture of three different masses of neutrinos. But how do they get their mass?

One possibility. Give them a hand. Proud of. I'm pretty proud of that joke. Like all the neutrinos that we've observed in the universe are left handed. So maybe we could just say maybe right-handed neutrinos really do exist. Maybe they're out there. But why don't we see them made? Because something who knows what made those right-handed neutrinos have ridiculously large masses. If they have really, really large masses, then we can't form them in our particle colliders because we don't have enough energy. And if they were to pop into existence because they're incredibly massive. They would just decay right away. In this scenario, the neutrinos would be able to get their mass by talking to the Higgs boson, just like every other particle. And we happened to not see the opposite handed neutrinos because something caused them to be incredibly massive and basically disappear from the cosmic scene. What would that interaction be? We don't know. We suspected that these extra massive, opposite handed neutrinos wouldn't even participate in the weak nuclear force.

They'd effectively be silent in all particle interactions, so we call them sterile neutrinos. But because they exist or at least can exist, they would both be both left-handed and right-handed versions of neutrinos. And so they get to participate in the Higgs mechanism. However, these sterile neutrinos there could just be one. You know, there you only need one in order to get give mass to all the different flavors of neutrinos because complicated math or there could be three. Or there could be like 50 sterile neutrinos. We have no idea. We like the idea of sterile nutrients because it's a way to give neutrinos mass. But there could be sterile neutrinos just floating around on their own for their own business. They have nothing to do with handedness. They have nothing to do with the Higgs mechanism, who knows? And then there's this thing that maybe neutrinos might be their own antiparticles. Remember when I said Neutrinos are always left-handed and anti neutrinos are always right handed? Maybe maybe when we're looking at an anti neutrino, we're really just looking at a neutrino. And then when we're looking at neutrino, we're looking at an anti neutrino like no other particle is its own antiparticle like this.

But, you know, neutrinos can be different. We've already demonstrated that fact. So maybe when we look at neutrinos and anti neutrons, we're like Wait. Neutrinos are always left handed. Anti neutrinos are always right handed. Maybe they're the same particle. Maybe there is no distinction between neutrinos and anti neutrinos, and we're just looking at the Left-handed and Right-handed versions. Yay! This might be nice, because one there would be the Higgs, the possibility of a mass through the Higgs interaction because you have both left-handed and right-handed varieties and Higgs will talk to you, and also particles that have their that are their own antiparticles can end up having mass even without needing to talk to the Higgs. Very complicated. Here we call it the Mya Mass and particles that are their own antiparticles. We call them Mya particles, but you might be asking, Don't particles and antiparticles blow each other up? Well, yeah, but neutrinos don't ever really touch each other. They don't really touch anything at all. So we don't know if this even happens.

I need a break, folks. Thank you. Slash not thank you to manosh be via email Chuck H on email at Jay Hammond on Twitter and Jeffrey H on email for asking the questions that led to today's episode. Please go to patreon dot com slash PM Sutter to keep this show going big thanks to my top patreon contributors this month, I'm talking about Matthew K, Justin Z, Justin G, Kevin Duncan, M Corey D, Barbara K, Neuter Dude Robert M, Nate H, Andrew F, Chris Cameron, NAIA Aaron S, Tom B, Scott M and Rob H. Their contributions and everyone else's that keep the show going. Keep sending questions. Could we take a break from neutrinos, please? I'm you know, I'm sure you regret it now Be careful what you wish for. Send questions. The hashtag Ask us spaceman. Ask us spaceman gmail dot com website. Ask us spaceman dot com, and I'll see you next time for more complete knowledge of time and space.