Daniel and Kelly’s Extraordinary Universe - Is the universe left-handed?

Episode Date: January 2, 2020

Why does the universe seem to be left-handed? Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

This is an I-Heart podcast. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, everything changed. There's been a bombing at the TWA terminal. Just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. Listen to the new season of Law and Order Criminal Justice System

On the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Why are TSA rules so confusing? You got a hood of you on take it all! I'm Manny. I'm Noah. This is Devin. And we're best friends and journalists with a new podcast called No Such Thing, where we get to the bottom of questions like that.

Why are you screaming at me? I can't expect what to do. Now, if the rule was the same, Same. Go off on me. I deserve it. You know, lock him up. Listen to No Such Thing on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. No such thing. I'm Dr. Joy Hardin Bradford, host of the Therapy for Black Girls podcast.

I know how overwhelming it can feel if flying makes you anxious. In session 418 of the Therapy for Black Girls podcast, Dr. Angela Nielbornet and I discuss flight anxiety. What is not a norm is to a lot. allow it to prevent you from doing the things that you want to do, the things that you were meant to do. Listen to therapy for black girls on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Hey, Jorge, remember when we talked about particles in?

I'm trying not to remember. You mean the spin that isn't really a spin? Yep, and then we talked about particle color. Uh-huh, uh-huh, the color that isn't actually a color? Mm-hmm, and particle flavors. You mean the flavor that doesn't actually taste like anything? That's the one. Well, I got some news for you.

Uh-oh. Turns out particles can be left-handed or right-handed. Hi, I'm Jorge. I'm a cartoonist and the creator of Ph.D. Comics. Hi, I'm Daniel. I'm a particle physicist and I'm mostly right-handed. And welcome to our podcast, Daniel and Jorge, give weird names to particle properties in the universe, a production of iHeard radio. In which we do our best to connect the weird, the strange, the amazing, the bonkers universe that we find ourselves in to things that actually do make sense to you that are familiar in every day. Yeah, because I think sometimes the universe does feel really familiar, you know, and relatable,

and I feel like I understand it, but sometimes I feel like the universe is this crazy, unknowable, confusing, and totally unintuitive thing that we're all living in. You mean every time you leave your house? Every time I turn on the news. If I just stay in my living room, everything feels so familiar. Why do I have to go outside? Yeah, but I guess I mean, you know, sometimes the universe, you know, particles and stars and black holes behave in ways that really don't make a lot of sense to me. Yeah, and it's fascinating how as humans we try to make sense of them in terms of things that we do understand.

Like we talk about the life cycle of stars, even though, of course, stars are not alive. But, you know, they begin and they burn and then they die spectacularly. like, I hope I will die spectacularly one day, I suppose. I think most people wish for a quiet death, Daniel. Not a spectacular. Who wants to go out with a whimper, man? I want to end with a supernova. I see.

That sounds just like a physics supervillain, Daniel, in a comic book. Look, my budget for my funeral is not like all coffins and flowers and stuff. It's all sticks of dynamite. Oh, great. I'll be sure to turn down that invitation. All right. But the point is that we do our best to understand this weird, cold, lifeless, dramatic world in terms of things that do make sense to us. You know, we think of particles as little balls. We think of photons as like waves in the ocean. We think of things as having a life cycle. What else can we do? We try to map the universe into things that we know. Yeah. And so today we'll be talking about a particular property of the universe, or I guess particles in particular. Is that a good way to say it? I say it. A particular particle property. Oh, my goodness. I feel like I'm talking to my kids and they're giving me a riddle. Peter Piper picked a pack of pickled peppers. Peter Piper picked a pack of pickle particles. Yeah, we'll be talking about a really amazing particle property that we might not even discovered if it didn't turn out that the universe.

preferred one kind rather than the other. Yeah. Sometimes the universe has a preference, you know? It's just the way it is. Is it just the way it is? The kind of thing that makes us wonder. Like, why is the universe this way and not the other way? Every time the universe has to make a choice,

and it chooses one direction over the other, one place over another makes us wonder, why this and not something else. Yeah. So usually as physicists, we like when the universe is balanced, when it's symmetric. And it doesn't make a preference because then we don't have to know why.

But every time it does make a choice, that's a clue. It tells us there's something weird in particular about our universe. It could have been different. Right. And so to the end of the podcast, we'll be talking about... Is the universe left-handed? Why didn't we say, is the universe right-handed, Daniel? Yeah, well, because the universe does have a preference,

and it turns out it's not the same as a bi-handed. Oh, interesting. So meaning that the universe is maybe not the perfect symmetrical, unjudgmental thing that we kind of wish it were, right? Or maybe wish it weren't? Well, we're always looking for symmetries in the universe and wondering what those mean. We have lots of really deep symmetries like, we don't think it matters where in the universe you are, the laws of physics should be the same. Or if you're here or if you're there or if you're somewhere else. The same way there's no preferred direction in the universe. There's no up. and down. That sort of makes sense to us, right? We like to think of the universe as like

democratic in that way. Right. But really, it's more of an electoral college kind of thing, which is the source of all of our problems. You know, that's a fascinatingly accurate description because the universe is dominated by mostly empty space. It's the empty space that contributes most of the energy of the universe because that's where all the dark energy is. Oh, man. No, we are trying really hard to stay apolitical on this show. are applying, you know, reason and logic to trying to understand the universe. But, of course, we have to map it sometimes to things that make sense to us. Right.

So it turns out that the universe is not perfectly symmetrical. It does have kind of a preference for one direction or another. And so that's what we'll be talking about here today. We'll be talking about the property of particles called handedness, right? Left and right handiness of particles, which I think don't actually have any hands. Well, I'll give you a hand for that one. particles as we know don't have hands but that doesn't mean we can't talk about handedness right and like we call it handedness because it's a property we first noticed of our hands like if you look

at your hands the two are not the same right your left hand and your right hand are not the same and even if you put them next to each other there's no way to like rotate your left hand to make it look just like your right hand they really are differently the pattern the order of the fingers is just different from one to the other right there's a our hand my hand right hand is not the same as my left hand. It's like a mirror image. That would be weird if both my hands looked exactly the same, though. That's kind of a disturbing if I was all thumbs. You were the one saying you like symmetry. Would you prefer to have two identical hands? Well, that's different than symmetry because I feel like hands are symmetric, but it's like mirror symmetry, right? There's a difference

between mirror symmetry and like exactness. That's right. And that's the property we're interested in here today, things that have a handedness that have a mirror symmetry, like your hand, if you put up your left hand in the mirror, it looks just like your right hand does in real life. The mirror turns left-handedness into right-handedness and the other way around. Right. The way like a sphere, a sphere doesn't have a handedness because it looks the same in the mirror. But your hand, it does have a handedness because it looks like the other one in the mirror. And so we're interested in like, all right, here's a symmetry, here's a property. Does the universe prefer one or the other? And we know, for example, in people, that there are more right-handers than left-handers.

And you have to wonder, like, why is that? What does that mean about biology or evolution or something? And now we can ask that same kind of question about particles. Right. And it turns out that the particles have a handedness and that the universe kind of prefers one over the other. Yeah. It's kind of fascinating.

All right. We'll get into that. But first, we want to give a quick shout out to Chris McKinnon in England. That's right. We got a request from your partner, Georgia, Arnold, who says, thanks for listening to the podcast and for teaching science to others. So Chris apparently is a fan of our podcast in England. So happy holidays, Chris, and happy birthday coming up in January.

Yeah, happy birthday to everyone whose birthday is coming up in the next year, which I guess includes everybody, except for those born on a February 28th, right? I guess that's right. We want to be inclusive, but we also want to be accurate. Right. And happy holidays to everyone out there. And happy non-holidays to all the. atheist as well. Are you saying atheists don't have holidays? I think by definition they don't have

holidays. Oh man, I don't know. This is a topic we should dive into. But yeah, thanks. And if you are interested in writing to us and let us know what you think of the podcast, please follow us on Instagram and Twitter and Facebook. All right, well, let's get back on the topic here of the handedness of the universe. And so we might say to the topic at hand. Let's get back to the do the bad puns guys we trailed off into some holiday cheer we forgot to get dole out the bad puns but as usual we were wondering how many people out there knew that the universe or that particles have a preference or even a this an idea or a property called handedness yeah so i walked around campus at uc irvine and i asked books if they knew what it meant for a particle to be left

or right handed so think about it for a second if you were approached by a physicist on a holiday morning and you were asked if you knew whether particles can be left or right-handed, what would you answer? Here's what people had to say. Do you know what it means to say a particle can be left-handed or right-handed?

No. No, they don't have hands. Well, isn't it talking about the movement of the current? That's where I can remember from physics I took. No. On the micro-level, there's certain orientations and movements happen somehow. and it's either oriented one way or the other way, but I'm not super familiar with that words.

Unfortunately not, no. Do you think particles have hands? Well, well, I would guess that it has something to do. Like, we're like the electrons around it, maybe more to the left or to the right or something. All right. Not a lot of people knew that particles have handedness. No, no, and a little bit of pushback.

Like, nope, particles do not have hands. Yeah, that was very confident. Yeah, that was my thought as well. I'm going to give a hand to this person. here. No, so not a lot of familiarity with this concept. Yeah. Which is, I guess, I know, I knew about this idea just from talking to you, Daniel, another

physicist, because I know that it's related to like the spin of particles, right, and how they look at each other in the mirror. Yeah, and it's related to parody. And we did a whole fun video with Derek Mueller of Veritasium about parity and charge parity and its impact on time with particles. It's a gorgeous video. Folks out there are really interested in this concept of symmetries and particles. Go check it out.

I think it's called Do Particles Tell Time? Yeah, on YouTube. And so just to clear things up, particles don't have hands. We've established that. At least we don't think that we've seen, right? They could have point hands. That's right. We have to qualify what we understand here.

We have not seen particles hands. That doesn't mean they don't have them. that could be super duper tiny. Little cute little tiny particle hands. Yeah, that's how they hold on to each other, Daniel. That's how they make those bonds, right? That's how the universe is connected. Tiny little hands.

That's right. But, you know, you can have handedness, even if you don't have hands. And let's get into it. But I feel like even if particles were a little spherical balls, which I know they're not, it seems weird that they would have like a preference between right and left because what's the right and left of a perfect sphere?

You're exactly right. And if you had a perfect sphere, a perfect sphere is not handed. To have something be handed, you need at least two different directions that you can compare. And so a perfect sphere, however, can spin. And when it spins, the axis along which it's spinning gives you one direction. And then you can compare that spin direction to something else, like the direction it's moving. And you can ask like, do those two directions line up, this kind of stuff? So particles can have handedness because it's built on top of other properties they have.

But you're right, a sphere has no handiness. It looks the same in the mirror. By itself. And as well, I guess, a point as well, right? Like a point would have even less of a hand, unless it has plenty point hands. Right, which is not really the matter at hand. But you're saying that handliness for particles is related to, like you've got to throw in another part. property into the conversation in order to have handedness in a point particle.

Yeah. And here's where we get in a murky territory because handedness, it's a quantum property of particles. It's like an intrinsic property. It's like charge, right? Or it's like spin. It's not physically spinning or there is no place where the charge is. It's just like a label we put on a particle.

And so these particles have this intrinsic leftiness or writingness. Really? And we can make it connected to this other physical thing. But in the end, it really is deeply, fundamentally, just sort of an internal quantum label that we can never really truly understand. Really? Because I've never seen handedness in any of the, you know, posters or graphics for the standard model of physics.

You know, I see spin, I see charge, I see color. But I never see like left or righty, you know? Yeah. Well, it's mostly connected to the weak force because the weak force is what revealed to us that handedness was a thing we had to think about and that it was actually important. So I guess we should call it quantum handedness

because that's the solution. Quantum handedness. That's the solution to any confusion in physics is just add a word that says, you're right, it is confusing, it's okay, don't try to understand it at an intuitive level, it's weird. No, you're right, quantum X, what we mean when we say that in physics

is like, well, this is like some other weird version of X. We're using X because it's similar kind of in some way to the thing you're familiar with. There's an analogy there that's maybe helpful, but it's not really the same thing.

Right. It's kind of like how our podcast is known for quantum humor. That's right. Only particles get it. It's neither here nor there, but just don't try to understand it.

That's right. That's where we're getting a lot of quantum laughs and making a lot of quantum bucks. It's so theoretical, Daniel. No, but in the case of particles, you can sort of define this handedness by saying, let's look at the direction it's moving, and then let's look at the axis around which it's spinning and ask, are those two things pointing in the same direction or not? And so we call it right-handed if they're in the same direction and left-handed if they're in opposite directions. But that's arbitrary. We could have just labeled them anyway.

We could call them alpha and beta or blue and red or left and right or right and left. These are just labels we decide. Oh, I see. It'd be like saying, like, some particles like to be positive and green, and some particles like to be negative and blue, and you might call that handedness or some other property. Yeah, some of the properties. But this particular one that we found, it turns out the universe cares about.

So you could construct all sorts of things and column handedness, but the universe might be like, yeah, that's fine. I don't care about that. It doesn't matter to me. But this one is interesting because the universe does seem to care. It is something that is important. It changes the way the universe treats these particles, and so it really does matter. Okay.

So you're saying that handiness in a particle means that the spin of the particle is sort of aligned to its motion. Yeah. And it's a bit confusing to think about the direction of spin because it's going in every direction, right? It's a spinning thing. It's turning and turning and turning. What if I just turn my head upside down? Wouldn't it flip it on its head? Well, it wouldn't change the direction of spin, right?

But so you use your right hand, and if your fingers are curling the direction, the particle is spinning, your thumb tells you where we sort of define the direction of the spin vector. And it's along the axis of spin. It's kind of like a top. If you're spinning a top, I guess you can spin the top both ways. But it's kind of like a screwdriver, I guess, or like a screw. It's like clockwise versus counterclockwise, right? You have to define one direction or the other. and we say that the direction that the fingers curl on your right hand is a certain way

and that helps us define a certain direction. And so if the particle is moving in the same direction that this spin is pointing, where again the spin comes from your thumb, if your fingers curl the way the sphere is spinning, we call that a right-handed particle. Really? Yeah. So parts of particles don't have the option of moving either way, like they always either move in the direction of spin or not in the direction,

direction of spin? Oh, that's a fascinating question. Remember, spin is quantized, right? And so you measure spin along any axis. And because it's quantized, it's either along that axis or in the other direction. Spin is not a infinitely valued quantity. It has to be either positive or negative. It's quantum spin. Like, let's say that spinning and the spinning direction is up. You're saying that particles can't move up and down. They have to move up or down? You can't say the particle is spinning and its spinning direction is up. That's quantum mechanically impossible to know the complete spin direction.

Right? Because there's three different axes and you can't know spin along three axes simultaneously because the Heisenberg insert and equal principle. Oh boy. Instead you have to go the other direction. You say, all right, which direction is my particle moving? All right, that defines some direction. Now I can ask, is it spinning along that

direction or in the opposite direction? I see. And that, what I get, if I ask it, is it spinning in the direction? direction of moving or not, is something that particles, some particles will always give you the one answer and other particles will always give you the other answers? Or is it random, like a particle can be moving either aligned or not aligned with its spin? That's what we call handedness. If a particle is right handed, then it's moving with its spin. And if it's left handed, it's moving away from its spin. Now, some particles like neutrinos, you only ever

see left-handed neutrinos. The right-handed neutrinos do not exist. Other particles, you can have both a right-handed version or a left-handed version. Oh, I see. Huh. All right. So some particles are ambidextrous. They can right with a right or left-hand. But some particles in nature are definitely lefties or right-ies.

Yeah, and it's a little bit more subtle than that. It's like, do you think of the electron and the positron as different particles or sort of two sides of the same coin? In the same way, do we think of like the left-handed electron and the right-handed electron is two different particles? Or just sort of like two different versions of the electron. Because it turns out nature sees them as different. Wait, so the electron can be right or left-handed. Or you could say it that there are right-handed electrons and left-handed electrons. Oh, I see.

But is it like 50-50 or what is it? The universe prefers left-handed electrons. You mean there are more of them? There are more left-handed electrons, yes. Whoa. Huh. So it's kind of the opposite of people. No, that's right.

And also for our DNA. You know, our DNA has a handedness to it also. And it's also right-handed. All of our organic molecules in our body are right-handed molecules. Oh, interesting. All right. So that's kind of what handedness is. Is do particles like to move in the direction in which they spin?

Or do they like to move in the direction in which they not spin? So that's a handedness in particles. And so let's get into what that means for the universe's prospects in Major League Baseball. Whether they are going to be drafted early or not, and why it matters maybe to you and me. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys.

Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal glass. The injured were being loaded into ambulances. Just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and order, criminal justice system is

Back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly and now I'm seriously suspicious. Well, wait a minute, Sam, maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school. a week on the okay story time podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want her gone. Now hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor and they're the same age. It's even more likely that they're cheating. He insists there's nothing between them.

I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the Iheart Radio app, Apple Podcasts, or wherever you get your podcast. I'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. when you think about emotion regulation, like you're not going to choose an adapted strategy which is more effortful to use unless you think there's a good outcome as a result of it if it's going to be beneficial to you. Because it's easy to say like go you, go blank yourself, right? It's easy. 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 iHeartRadio app, Apple Podcasts, or wherever you get your podcasts. All right, Dennis, so you're saying that some particles in nature, like the electron, can be right or left-handed, meaning they can move. you see them moving in the direction that they're spinning and some of them you see them moving not in the direction they're spinning but some particles like the neutrino do have a preference that's exactly right neutrinos are only left-handed and anti-nutrinos are only right-handed

and this is a really fascinating thing that we discovered only about 50 years ago that this concept of particle handedness is a real thing in the universe and you know we've been like over the history of science adding labels to particles as we discover them Well, like, we'll see something happen and we're like, oh, well, we can't explain that with the labels we currently have. So maybe particles are a little bit more complicated.

Like we have to add spin to them or we have to add flavor or color or whatever to sort of have our theory have enough wrinkles in it to describe all the weird effects that we observe. And so hantiness is like one of the latest ones. In the late 50s, people saw these really strange experiments where it looked like the universe didn't work the same in the mirror. as it does not in the mirror. And to explain them, they had to add this new property to particles call handedness. Oh, I see.

Like if every particle in nature was 50-50, right and left-handed, we wouldn't even have a name for it. It'd just be like, you know, it wouldn't matter. But you're saying it sort of does matter in the universe.

Yeah, we wouldn't know if it was real. Like you and I could right now invent a new particle label, I call it strippiness. And all right, the electrons we're going to say are blue stripe and with red, and those electrons are green-stripped with white or whatever.

I'm going to go with banana-ness. Bananinus. But if the universe treats particles the same, whether or not Jorge has labeled them to be banana equals one or banana equals zero, then it doesn't matter. It's not a physical thing, right? It's just like an idea in your mind. It's like literally not a thing.

Like you would say, that's not a thing, dude. Nobody cares. Say somebody doesn't experiment one day and they realize, you know what? Particles that Jorge has labeled having banana equals one, the universe treats differently. Then we'd be like, oh, the universe is not symmetric to banananess. And then it would be a real physical thing. That's exactly what happened in physics.

People had this idea of handedness, but they thought, that's ridiculous. How could the universe prefer one to the other? Clearly, it's symmetric. There's two options there. It's just a thing in your head. And then they didn't experiment that proved them wrong. It was like in Clueless, where one of them said to do the other, stop trying to make it a thing. It's not a thing.

But it turns out it is a thing. It turns out it is a thing. And there's a lot of really interesting deep philosophical questions there. Like, how many other things are there of particles that are really exists? But we just haven't figured out either the way the universe prefers one to the other or an even deeper question is, what if there are particle things that the universe is just totally symmetric to so we will never discover them? Like it is a thing, but we can't tell us a thing. Yeah, in which case, is it really a thing?

I think that's what's happening with the problem. banana-ness of particles. You guys just can't see it, but I know it's there. Maybe we just need a really big accelerator. Once you raise $50 billion and we'll discover banana-ness. It wouldn't go in a circle, we're just going to half-circle. We need a sort of elliptical accelerator, you know, with a banana curve to it. Yeah, and forget those cryogenic magnets.

We would just use banana peels to lubricate the particles. It's not a particle accelerator, it's a particle slipper. Yeah, there you go. Comedy would be plentiful in this accelerator. Yeah, okay, so particles have a had in this. So what does that mean? What does that mean that the universe has a preference in some cases or not? You're saying it's related to the weak force?

Yeah, well, we have all these fundamental forces of physics. You know, the weak force, the strong force, electromagnetism, and gravity. and they all are different forces. We're trying to understand, of course, how they're related, but they have different effects. And most of them don't care one whit about whether a particle is left-handed or right-handed. But the weak force is weird.

Like the electromagnetic force doesn't care if an electron is right-handed or left-handed. It's democratic. It treats those two the same. And the strong force treats left-handed corks and right-handed corks the same way. It's like, I see you both the same. I am handedness blind.

I'm going to attract you or force you to do something, and I don't care. That's right. If you did an experiment with the strong force and you had it set up next to a mirror and you watch the experiment unfolding in the mirror, you could use this exact same laws of physics that we have in our universe to describe what you see in the mirror. Because in the mirror universe, all the handednesses are flipped, but the strong force doesn't care.

It's like, oh, left-handed corks, now or now right-handed corks, I treat them the same. Oh, I see. the equations kind of work out the same. The equations are perfectly symmetric and the effects are perfectly symmetric. So flipping them does nothing. Like what you see in the mirror could may as well not be in the mirror. Yes.

Or you can't do an experiment to tell are you in the mirror world or not. Oh, boy, that's the results of the same. Interesting. But that's not true of the weak force. Okay. So the weak force is different. It does affect particles differently depending on this idea of handedness. That's right.

And it was in the 50s that people realized, huh, nobody's ever checked to see if the weak force breaks his rule or not. People just sort of assumed it. It's such a deeply ingrained assumption. Like, of course, the universe doesn't prefer one or the other. And then some theorists went through and said, well, has anybody ever checked? And people had checked for electromagnetism and for the strong force and all that stuff. But nobody had checked for the weak force.

So then a physicist did it. Well, I feel like there are two ways in which handedness can. matter. Like one is which of the right or lefties do we see more of? And that's kind of interesting. Like the fact that we see more left-hand-hand-the-nutrinos and right-hand the neutrinoes is sort of one way that the universe is a preference. But then you're, I feel like there's also another way in which the universe has a preference, which is in through the forces. Like the loss of physics actually apply differently to lefties or righties. Yeah, but those are the same concepts, right? We interact with things using forces.

So we only see left-handed neutrinos because we interact with them. It's possible there are our right-handed neutrinos out there that we can't interact with because our forces don't touch them. We only see what it's visible and what we can interact with as a whole. We don't recently discover that there's huge parts of the universe. We barely have hints that actually exist. And so there could be other particles out there that are right-handed neutrinos that we haven't seen because we can't interact with them.

Oh, I see. It's the same thing. It's the same thing. There could be the same plot thickens or passes through us like neutrinos. I'm not quite sure how people are getting this. But you're saying that there isn't more of the left-handed neutrinos in the universe, which is the only kind we see. Well, we don't know if they're a right-handed neutrinos because we can't interact with them,

therefore we can't prove whether or not they exist. Oh, because what we used to interact with them has a preference. It's like a filter. That's right. Now, the other particles, electrons and quarks, we can interact with them in other ways that are democratic, right? Because the strong force and electromagnetism doesn't prefer one or the other. But the neutrinos, we can only interact with them via the weak force. Oh, I see.

It's the only way we can see them, and it certainly does prefer it. So there could be as many right-handed neutrinos as left-handed neutrinos. We just can't see them because the weak force only lets us interact with the left-handed ones. that's right and you know in the same way that like the space could be filled with invisible imperceptible bananas we can't see them so are they really there well we have to use the banana force which i've yet to discover but i'm sure it's on the horizon there yeah and it's fascinating because this effect has to do also with charge right because the particle that mediates this thing for the weak force is the w particle which carries a lexion

charge. So you have W minuses, you can decay to left-handed electrons, and W-pluses decay to right-handed positrons. Okay, so what does that mean? It's relevant because the way we sort of patched up this symmetry is by adding charge to it. You can tell whether or not you're in the mirror world by doing this experiment to see whether things are reversed, right? Whether the weak force is giving you left-handed stuff or right-handed stuff. But if you, in the mirror, you also feel. flip the charge of everything, then the experiment looks exactly the same. Okay. Well, maybe step us through a little bit.

Like, what does it mean that the weak force prefers left-handed to right-handed? Like, it'll only interact with left-handed things as far as we know, or, like, it only works with left-handed things? Yeah, the W bosons in particular will only interact with left-handed matter particles or right-handed anti-matter particles. So left-handed electrons, left-handed quarks, left-handed neutrinos, or right-handed positrons, right-handed antinitrinos, right-handed antichorks. The Z, the Z boson, which is another particle that communicates the weak force, is even weirder.

It will interact with both, but it prefers the left-hand. It interacts with the lefties more than the right-eyes. Oh, you're, okay, I guess now you're taking me through the particles that mediate, that, like, helps us communicate these forces, right? That's exactly right, because the weak force has three of them. Oh, okay. You're saying that the particles that communicate the weak force, those are the ones that have the preference.

It's not like the concept of the weak force has a preference, but the particles that communicate it have a preference. Yeah, well, the particles, they are the manifestations of the force, right? We think about these particles as doing the duty of the force. The Jedi. Does the Jedi order exist without the Jedi, you know? they're carrying out the marching orders of the Jedi hierarchy

so yeah well I mean it's like saying like it's not that the police force has a preference for left or right hand and the people it's more like you know it's like parking officers

have a preference but you know detectives have a different preference you know what I mean like it's different than saying that the whole thing has a preference yeah and you're right and there are three particles

there that mediate the weak force the W plus the W minus and the Z those are sort of like the analogies of the photon, but for the weak force. And the W plus and the W minus, they only interact with left-handed particles or right-handed antiparticles.

I see. It's like that's how that preference manifests itself. It's like the messengers for this force have a preference. That's why we can't communicate with right-handed neutrinos because the messengers are kind of blinded to the other kind. Yeah, and that's how they discovered it. They took a bunch of atoms and they lined up their spins in a certain direction. And then they saw which direction do the particles shoot out?

Do they shoot out in the same direction of the spin, in which case they'd be right-handed? Do they shoot out against the direction of the spin, in which case they'd be left-handed? And they sort of expected it to be balanced so that you couldn't tell. Like, they expected to get the same number of right and left-handed particles so that you couldn't tell if you were in the mirror world. But what they saw was a total shocker. Not only was it not balanced, but it was totally unbalanced. Like zero right-handed particles, 100% left-handed particles. 100% left-handed particles were shot out.

And so the weak force doesn't just prefer left-handed particles. It, like, maximally prefers it. As far as we know, I mean, could it be producing right-handed ones that we just can't see or interact with? There could be right-handed particles that we don't interact with, but they don't interact with the weak force. They have to be some other new force for us to interact with them. If they interacted via the weak-force, we would see it.

Well, but, I mean, I guess one question is, how do we know it's the weak-forces fault or those particles is fault. Like, what if it's our fault, you know? Like, what if we? We're parents, it's always our fault, right? Yeah. What do you mean our fault?

How is it? Well, I mean, like, maybe there's a new kind of boson, we'll call it the ex-boson, which does interact with the right 10 particles through the weak force, but we just don't interact with the ex-bosar. Totally possible, yeah. There could be a whole complicated sectors of particles out there that interact with each other, than not with us. And we just haven't seen them or haven't yet discover them. Nobody's invited us to the party.

That's the whole hypothesis for dark matter, right? We know that there's a lot of dark matter out there. We don't know what kind of particle is it. We don't know if it feels forces among those particles. We don't know if there's like 10 different dark matter particles. They're always changing into each other. So there could be a whole complicated sectors and oceans of physics there that we are not privy to because we don't have like a portal into them. No way to interact with anything that's happening there. Right. If only we had that banana particle accelerator. It would open new doors to the universe for us. It would peel away the layers hidden from us. It would slip us into a new era of physics. All right. Well,

that makes it a bit clear for me and how the universe has this preference. And so let's get into why it matters to the universe and maybe to us. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually emboldened.

Held metal, glass. The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and Order Criminal Justice System is back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice.

system on the iHeart radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Well, wait a minute, Sam, maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want her gone. Now hold up, isn't that against school policy?

That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor and they're the same age. It's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast.

I'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. When you think about emotion regulation, like you're not going to choose an adapted strategy which is more effortful to use unless you think there's a good outcome as a result of it, if it's going to be beneficial to you. Because it's easy to say, like, go you, go blank yourself, right?

It's easy. 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. Denial is easier. Drinking is easier.

Yelling, screaming is easy. Complex problem solving, meditating, you know, takes effort. Listen to the psychology podcast on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts. All right, Daniel, so the universe apparently prefers lefties. You know, I think left-handed people always have felt pretty special, is my understanding. And now they know why. And now they know why.

The universe likes you better. Yeah, well, the weakest part of the universe at least likes them better. Oh, no, that's not true. Your gravity is the weakest force. The weak force just sort of has that name. But it's fascinating, you know, not only that the universe is asymmetric that seems to notice that there's a handedness, but that it prefers this one. You can wonder like, why don't we live in a universe that's asymmetric the other way that prefers right-handed particles, where the weak force interacts only with the right-handed particles. It's this kind of arbitrary seeming choice that makes us wonder about like the multiverse.

Right. Well, meaning like maybe it's weird that it has a preference, so there must be a twin out there who is right-handed. Well, that's the symmetry in your brain screaming out for an explanation, right? I think there must be balanced, but there doesn't have to be. You know, imagine you're at the control panel of the universe in the first moments of the big bang when the laws of physics are being set in stone, and you have to choose left-handed or right-handed universe. You know, how is that choice made? Are there a billion universes out there and it's randomly assigned for each one? or is there some deep underlying principle of physics that demands that the weak force be left-handed? There could be no other way. Or could they just flip a coin?

It could be. We don't know. According to our current understanding, you could write consistent laws of physics where the weak force prefers them equally, or the weak force prefers only right-handed particles, or where it prefers one by a little bit. We don't understand why it is this way. Does it have to be this way? we have no reason to believe it has to be this way, and yet it is.

So that seems to me like a clue. Right. Do we know in people why some people are left-handed or right-handed, and does it depend on genes, or is it just some random process? Well, based on my deep expertise in biology from being married to a biologist. Is she right-handed or left-handed? She's right-handed. But we have some lefties in her family.

This is actually two layers of answer there. One is people like what they prefer to write with, and we're most. mostly right-handed. We don't know why. And it's, again, a great question. Like, was that just an arbitrary choice that the brain decided to specialize and this side of the brain is better at this and the other side of the brain is better at that? And maybe there were equal populations at some point and then it just sort of randomly drifted in one direction. We just don't know. And then there's this deeper question about the chirality of molecules in life. All the molecules in life, including DNA, have a chirality that's right-handed, which means they have the

same sort of orientation when you rotate the object. Right. Like, each molecules have a mirror image version of themselves, too. Precisely. Every single organic molecule is right-handed. And if you were fed, like, food made out of left-handed molecules, you couldn't eat it. Like, they didn't die.

Yeah. You cannot process it. And so that's another just, like, seems like an arbitrary choice could have been something else. We don't understand any of these things. And I don't know if the mystery of particle physics handedness is connected to those at all because it's definitely the other direction or if this is just sort of a mathematical connection where you can identify handedness and sort of see a similarity in the sort of question.

I see. Huh. Like everything that might be possible would have a handedness preference or something. Like biology, particles, you know, like just a fundamental, you know, property of existing. Yeah. But it makes our universe interesting. And for example, the reason why the weak force is so weird and so left-handed is one of the reasons why the Higgs boson is so fascinating. What do you mean?

Well, the Higgs boson, what it does is it connects the left and right-handed particles together to give them mass. It interacts with the left and the right. It touches, it talks to both of them. And talking to them together is how it gives those particles mass. And neutrinos, we don't know. We think they have mass, but we don't quite really know how much mass they have and how they get the mass and do they get it from the Higgs boson or not. It's a whole big complicated question.

But the Higgs, it treats the left and the right totally equally and sort of combines them into one combined particle that has a specific mass. Right. But I guess the main point is that the universe has a preference for left or right hand in this, it seems, but we don't know why it has that preference, right? It's a big mystery, right? And it's weird. Yep, it is weird.

And if it wasn't for this little effect in the weak force, which took a long time to discover, we wouldn't even know. So it could have been that, you know, what if the weak force was totally symmetric for some weird reason? Particles have handedness, but we didn't even know, like, that they have this property. Well, we wouldn't care, I guess, right? I care. I care. I care deep. I want to know the truth, man, not just what's relevant for some experience.

Oh, I see. You want to see all the features, even if you can't see the features. Of course. I want to know. What does it mean to be a particle? What are the number of labels you need to define a particle? Mass, spin, charge, color, flavor. Why all those things? What do they mean? Why this and why not that? Why not banananess? To me, these are really deep, fascinating questions about, like, the very nature of the universe. So, yeah, I want to know. Like, if you found out half of all particles had an asterisk, a pin to them, but it didn't matter at all for anything else. Like, nobody would care, but you would care. Me and all the other particle physicists in the world and anybody who cared about understanding the nature of reality, but yeah, you're right, nobody else. You're like, why does that have an asterisk? I see. All right. Well, I want to know why the universe has an asterisk.

All right, well, I think this is all just a big lesson on ways in which we explore the universe. You know, we look for interesting phenomenon and interesting preferences that the universe has, and that tells us something about how it's all put together. put together. Yeah, and we don't understand the importance and the ramifications sometimes of these things. People thought about particle handedness as sort of an abstract idea a hundred years ago when particles were first being understood. They thought, no, whatever, it's just a mathematical curiosity. It's not relevant. And then later it turned out to be relevant. And it might even turn out to be more relevant. Maybe we'll discover a new force that's very powerful and does prefer left to right or right to left or something like that. So it's worth just sort of

sort of like exploring and trying to understand because you never know where the next big discovery is going to be. Yeah, it would be pretty cool. Would you like Daniel to have a hand in that discovery? No, but only if it's the left hand. I'd like to discover it and then I'd like you to give me a hand when I do. You'd like to get both your hands on this discovery. I just want to get my hands dirty, okay? And with that, we've exhausted all the bad puns, Daniel. So maybe we should wrap it up. That's right. We've done all the left-handed puns and the right-handed puns. Well, thank you all for listening. To me, this is a fascinating question about the sort of deep nature of the universe and the stuff that makes it up and how we understand it in terms of

our sort of macroscopic ways of thinking. Flavor, color, spin, and now left-handedness and right-handedness. Yeah, so we hope you enjoyed that. Thanks for joining us. On the other hand, we're not done yet. Now we're going to do the mirror image of this podcast episode. The whole thing backwards. We'll do it backwards, and we'll say the universe has a preference for right-handed particles. We've got to do it backwards and positively charged. And where the jokes are good, this time. That's right, where I make the jokes and you laugh at them.

All right, thanks everyone for tuning in. I hope that podcast reached a parody of our other ones and is not a parody of itself. See you next time. If you still have a question after listening to all these explanations, please drop us a line. We'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge, that's one word, or email us at Feedback at Danielandhorpe.com. Thanks for listening, and remember that Daniel and Jorge Explain the Universe

is a production of IHeart Radio. For more podcasts from My Heart Radio. Heart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. There's been a bombing at the TWA terminal, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged. Terrorism. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts.

Why are TSA rules so confusing? You got a hood of you, I'll take it all! I'm Manny. I'm Noah. This is Devin. And we're best friends and journalists with a new... podcast called No Such Thing, where we get to the bottom of questions like that. Why are you screaming?

I can't expect what to do. Now, if the rule was the same, go off on me, I deserve it. You know, lock him up. Listen to No Such Thing on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. No Such Thing. I'm Dr. Joy Hardin Bradford, host of the Therapy for Black Girls podcast. I know how overwhelming it can feel if flying makes you anxious. In session 418 of the Therapy for Black Girls podcast, Dr. Angela Neal-Barnett and I discuss flight anxiety.

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