What is a particle?

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Speaker 1: Hey, Daniel, what exactly is your job title these days? Well? I call myself a particle physicist, all right, so then this question should be pretty easy for you. Can you tell me what exactly a particle is? Oh? Boy, I wish I could. What I mean you wish? Aren't you a particle physicist? How can you not know what it is? Well? I guess it's kind of just a made up job title, I suppose. I mean, you must be smashing something there in your large accelerator. Yeah, maybe that's what we should have called it, the large something collider, the large something something collider. I mean, I voted for something collider face, but nobody else wanted that. It's not too late. I am more handmade cartoonist and the creator of PhD comics. I'm Daniel. I'm a professor of physics at you see ermine, and I'm also a particle physicist whatever that means. Maybe that should be the title should be whatever physicist technically that encompasses the whole universe. Or I could just be a professor of whatever. What are you teaching this year? Whatever? In your house, you're probably a professor of that. I'm sure you hear from your kids a lot whatever. Yeah, I do have two teenagers, so I do get that a lot. You get a lot of something at home. Not a whole lot of interests in physics, but a whole lot interest in whatever, dad, or a lot of non interests. I guess in whatever. Sometimes I can trick them into being interested in physics. Oh yeah, how does that work? You pay them now? They asked me a question about something else they're honestly curious about, and then I turned it into a question about physics. I guess everything at the end is physics sort of, and so basically anything that anything they ask you as a physics question. When can I go to sleep? Well, it depends on the physics of the chemistry and your brain. Let's explore that. Sit down, I'll give you a lecture, and that's a good way to put them to sleep. It all works out. But anyways, welcome to our podcast, Daniel and Jorge Explain the Universe, a production of I Heart Radio in which we turn the whole universe into a physics question and ask what is it, how does it work? And can we figure it out without putting you to sleep. We take your mind on a journey into the craziest things that the universe contains, the craziest things that the universe does, and the craziest, strangest things that the universe might also be made out of. That's right. We take you in a journey to the big whatever because the universe is full of what you know, it's full of stuff, and there's also an ever there because the universe is several billion years old and maybe around for trillions of more years. That's right. There's not many things that we can say with certainty in physics and philosophy, but we can say that there is something out there and we're something, right, also, are don't we something? I'm something? You're something. The listener is something and you're definitely listening to something right now. Well, you're more, you're more of a something else, Dan. I'm gonna take that in the entirely positive way that it was meant. Definitely not nothing. Something. It stands out you mean, like a ZiT sort of rises above the skin. That's that's something else, Daniel. But I'm happy to be the black head in this universe. But it is a pretty wonderful universal of amazing things to discover, and every day we're learning more and more about it. We're looking out there into the stars and looking with our microscopes at the smallest things in existence, and we're giving names. We're not just taking names, we're giving out names to these things. And we're doing more than just trying to see what's out there in the universe. We're trying to make sense of it. We're trying to describe the crazy bonkers universe that we see out there in terms of ideas that makes sense in our It's we have a small mental toolbox of concepts that we are familiar with, and we need to describe the whole crazy universe out there in terms of these simple ideas. Yeah, does that mean we have like little tiny hammers inside of our brains and little tiny screwdrivers sort of? I think that as kids grow up, they experienced the universe and they encounter new ideas and they sort of become familiar with them, and then that things in your brain is like the set of ideas that you are comfortable with. You know, a thing, what can the thing do, what can the thing be? What are the rules of a thing? And then lady, you try to describe other stuff in terms of that kind of thing. Yeah, it's almost like we sort of experienced two different universes in a way, right, Like, as you grow up, the universe seems to be one way. It seems to follow sort of like Newtonian physics. Things bouncing around, things are hard, things are soft, things fly through the air. But then as you learn more and more about the universe, as humanity has learned more and more about the universe, things got more complex. They certainly did. There are so many things out there in the universe that we do not experience in childhood that we do not have intuitive concepts for, because they're not the kind of thing that our brains involved to understand, and not the kind of things that we learned to deal with when we were children. And yet they are out there and they are part of the real world, and so we need to somehow extrapolate from the kinds of concepts that we do understand out there into the fuzzy weirdness that the universe is. And it makes me wonder how other intelligent species think about the universe, if they have different ways of interacting with the universe, or if they're very very small or very very large or very very fast, would they think that our understanding of the universe is strange and alien. The way we might think there's is whoa. You just kind of blew my mind there, right, Like we usually assume aliens are the same size and the same shape as we are. But maybe aliens are you know, a tiny microscopic of almost quantum size and beings. Yeah, or maybe aliens can like taste photons and smell electrons and have weird quantum interactions, and for them, quantum mechanics is totally intuitive and they would find you know, classical mechanics is like, wow, that's fantastic and beautiful. What an interesting simplification of big quantum mechanics. It's really fun. And of course you know, I can turn any question into one about aliens, yes, or maybe the aliens are just going like whatever, that's actually what my kids complain about their Like, dad stopped turning this into something about aliens. I didn't ask about aliens. Well, all teenagers act like aliens sometimes, or at least they feel alienated or they wonder if their parents are aliens. You just need a cone head, I guess. But it does seem like we're sort of maybe stuck it away in our childhood view of the universe sometimes or at least it's hard to you know, kind of think about the real universe because it is sort of complex and not intuitive from a child's perspective. But then our language and our way of thinking is sort of stuck because that's how we grew up. And it's a real question whether or not we can comprehend a true, chaotic, buzzing reality that's out there in terms of the kinds of ideas that we have, or do we need to somehow invent or discover a completely new kind of concept which previously was alien two our thinking, you know, just following the mathematics and then developing inventing some new kind of intuition sort of as an adult intellectual species that we need to grapple with the craziness of reality. I wonder if even our brains are capable, right or equipped or designed to maybe grasp the true nature of the universe. You know, it could be that, you know, like sort of like dogs can't do calculus, maybe we really understand the define mathematics at the core of reality. And I don't like the way you're talking about my dog there, man, I mean, don't put limits on my dog's village. Dog can do calculus or at least algebra. Come on, you can count treats. I'm pretty sure. There you go. I'm sure he can calculate the radio treats too, So that's sort of like calculus. Yeah, but you're right, we don't know if the human brain is capable of grasping the true nature of reality. Certainly dogs are not, as much as we love them, and so then there's no guarantee that we are infinitely intelligent and capable of understanding. If super intelligent aliens come to Earth and want to explain physics to us, could we even understand it? Could we grocket even if they knew how to speak our language and our mathematics and our physics. Would we fail that class? Yeah? Or maybe they would have to like trick us into understanding or liking or asking the right questions about physics. You know, you think we'd just be like whatever, aliens, we don't want to hear it. Just give me a headache, man, I would sign up for that headache. I would go to that class. What if it was a constant headache, like seven headache? Man? Have you tried quantum mechanics? That's basically seven headache. I feel like that's humanity trying to absorb something which is truly alien, which is far from our experience, something we have never experienced on the early Savannahs. I mean, we didn't need to know to be able to hunt mammoth, and yet we are somehow beginning to grapple with it. We are getting a sort of mathematical fluency with a truly alien concept. We'll just need to require the aliens to bring espirin at least give us a hand. But it is interesting to try to, you know, understand these fundamental concepts about the universe. And there is one concept out there that may seem pretty easy to understand, but actually there is a lot of uncertainty about it. Something very basic about the universe, that's right, And if you ask people whose job it is to understand this stuff, you get lots of very different answers, to my surprise. So to be on the podcast, we will be tackling the question what is a particle? And just to be clear, then in your official title is particle physicists. So you know, first of all, it's shocking that you don't know. And second of all, if we were going to ask somebody we should ask you. You know we have one of the leading experts in the field here. Yeah. Well, I suppose you could say that a particle physicist is someone who tries to understand what particles are, not somebody who already knows the answers, right, because member science is a journey. You ask somebody who's an expert in dinosaurs, they don't know everything about dinosaurs. Maybe they know everything that humans know about dinosaurs, but they don't already have all the answers right. Right. When I hire a plumber, I don't really want someone who knows plumbing. I just want someone who comes in to learn about plumbing. Well, that's why you don't hire a physicist to do your plumbing, because they'll be like, Oh, I have this great R and D project. I'm curious this new theoretical idea for plumbing will work in your toilet. That's right. I wanna build a water collider inside your walls and we'll see what happens. No, I'm just putting a small black hole under your toilet and it's just gonna suck everything away. That would be a pretty green solution. It would conserve water for sure. Whether dark matter can go into a black hole. Oh man, that's next level physics, spread there, or lower level physics. But you know, particle physicists are people who are curious about these questions. What is the universe is made out of at its most fundamental level, And it's something we've made a lot of progress thinking about in the last hundred years or so. But there's a shocking diversity of answers, even among particles physicists. Yeah, something as simple of award as a particle can have many different meanings, and in physics it can mean very different things. So it's usually we were wondering how many people out there have thought about this very basic question what is a particle, and whether or not they have a true answer to it. So thank you very much for everybody who is willing to answer random questions for the podcast. It's some great help to us and we love hearing your voice and having you all out there participated makes us feel a little bit like this is a conversation, So please, if you'd like to participate, don't be shy right to us. Two questions at Daniel I and Jorge dot com. So think about it for a second, what do you think is a particle. Here's what people have to say, Well, Daniel and Jrrey, I think I learned this one from you. At a particle is a certain excitation of a certain field. I'll leave it at that. To me, a particle is the smallest, this great thing that you can poke where we don't yet know how to smash it into smaller bits. My understanding is that a particle is just an excitation in a quantum field, and when it reaches a certain energy level um our many electron golds in that field. That causes a particle to just appear as a consequence of the energy in the field. It's just the basic unit for that has of matter and um and energy. We have different definitions based on how we're talking about what a particle is. Maybe talking about a particle from the perspective of an engineer building a particle collider, you might have a certain definition. If you're talking about it in a theoretical physics sort of minded way, you might have a slightly different definition. I think it's something that we're still grappling with because it's not something that we have an intuitive understanding of. So I think there's a lot of different ideas and a lot of different ways to try and make analogies that we can understand to sort of encompass this concept of particle. A particle is that portion of the standard model divided into quantized pieces which may or may not be fundamental. They may be thought of as the building blocks of the universe, and they may be also thought of as perturbations, wiggles, or vibrations of their concommittant field. I generally use the word particle to describe small bits of stuff, and it doesn't just mean atom. You can even say, like a cork is a particle, and of course are made up of other things. Those two are particles. So I guess the word particle just means a bit of something, the smallest bit of something you could possibly have. All Right, I got a little existential there and a little basic. Some people were, like, a particle, it's just a particle, right, It's like the basically unit of stuff. Yeah, it is a really fascinating question, and you hear in these answers a lot of different ideas. Yeah. Yeah, some people say it's like an excitation in a quantum field, and some people say it's just like the smallest thing you can poke at Nobody said it was Daniel job. Nobody said why are you asking me? If you're asking me, we're in trouble. It's like if your dentist asks you what am I supposed to do next? At least nobody said something or whatever. It's not nothing. Oh, there you go. Maybe it's not nothing. Is that one of the leading theories. That's not an explanation though, that's just like ruling out other explanations. Maybe that is the answer, Daniel. That's like when you ask your teenager who didnt to the car and they say, I don't know, but it wasn't me. That's not an answer. Yeah, so let's dig into this. It's it's almost almost like a philosophical question, right Daniel, like what is a particle? Or maybe more like a semantic question, you know, about the meaning of the word or is this actual? Like physics questions like we don't even have math for it. I think it's all of the above. It's definitely an interesting lesson in history how we came up with this concept of a particle, what it meant to people through time. There's also a philosophical question, you know, if you could describe the universe in terms of particles versus fields, versus something else, which is the true stuff of the universe. But it's also really a physics question. You know, we are trying to understand the universe, and it's most basic level, what is the fundamental element of the universe. Some things are fundamental, they're inherent properties of the universe, and other things like ice cream cones, are emergent. They arise out of the complex interactions of other stuff. So it's really sort of the heart of particle physics is understanding the very nature of the universe. So I think it really is a physical question as well. It's a it's a party, It's right there in the name particle. Well I never made that connection. My whole job is just a party. You're a party animal, professional party animal, professional party. Yeah, and if you have had a bunch of particle physicists at your party, you know that's true. Yeah, you know it's not really a party. But anyways, let's dig into this kind of deep question, Daniel, I guess how would you even start to tackle this question. I think a good way to begin is to recognize that particles are really at the heart of what we mean by the stuff around us. It's a huge inside already to say that the things that are around us, the ice cream cone, the lava, the kittens, whatever you ate for lunch, all of this stuff is made out of smaller pieces. Right, So the fact that you had a cheese sandwich for lunch is not because that cheese sandwich is made out of like cheese bits and sandwich bits. It's all made out of the same stuff, right. There's no cheese sandwichiness to the universe. There's no lava eatness to the universe. That's all made out of the same fundamental pieces. And so when you take the universe apart, you discover this really deep and fascinating fact that most of the qualities of the things around you are determined by the smaller bits they're made out of. And not like the identity of those bits, but how those bits are arranged. Right. But that that's sort of a modern view of the universe, right, I mean, when we started back in ancient times, you know, we noticed, I think we noticed that we can you can break stuff apart, right like you can break a person apart. You can take a rock and smash it into smaller and smaller bits but it probably our limitation was that if you break a rock into smaller bits, eventually just get tiny little rocks or kind of little pieces of people. But there's sort of no way for us to know, like, oh, this rock stuff is different than this plant stuff. Right, Certainly in ancient times, but there was this concept that maybe there are a few basic elements. You know, they thought it was air, wind, fire, and water initially, but this idea that maybe everything around us was made of basic ingredients mixed together in different ways. That is an ancient idea. Although you know, every time you're giving credit to the Greeks for some ancient idea that sounds very modern and insightful, you gotta remember they had lots of other crazy ancient ideas that we never forget because they're so far off that we ignore them. Right right, I'm well aware of your anti Grecian is m. You're kind of down on the Greeks. Do you think they were just like shooting ideas everywhere and some of them stuck on the wall. I mean, have you read Greek philosophy, And basically that's exactly what they did. They sent around in robes, eating olives and throwing ideas against the wall. It sounds like a great way to do things. It is a great way to do things, and it's wonderful that people were thinking so deeply a long time ago. The problem is they didn't really have ways to test these ideas until very very recently. So for a long time the idea has just sort of floated out there in idea space. But more recently we have actually gained insights about the universe by doing experiments. And it was something like a hundred and fifty years ago that the concept of a particle really came together and it emerged out of experiments that people were doing. Interesting, So was this before or after the idea of the atom, Like, do we have an idea of what an atom was, is the smallest thing you can kind of break stuff apart into, before the idea of a particle? Or did we think about particles before atoms? We thought about atoms first. I mean atoms also come from the Greeks, right, Democratus had the idea of atoms, and then later on in chemistry we noticed that there were these integer quantities in chemical equations. So people had this concept that maybe things were made out of atoms. But we didn't really know how those atoms worked, you know, what was inside the atom, what was the structure of the atom itself, what made this element different from that element, And that didn't come about until the discovery of the electron in the late eighteen hundreds. This is J. J. Thompson who was playing around with cathode rays, these strange glowing rays in these tubes where they had pumped out most of the gas. Mmm. Interesting, So you're saying that, I guess we tried bringing down rocks as small as we could and at some point, which chemistry, you get to the idea of like maybe there's the smallest possible bit of stuff. And so we knew about atoms, but maybe we thought that, you know, there was a carbon atom and that was different than a hydrogen atom, and that was different than an oxygen atom, right, Like that's kind of where we were before we thought about things smaller than an atom exactly. And there's a reductive approach, and so we wonder, like, well, what makes a carbon atom different from an oxygen atom? Is that just it is that like the fundamental element of the universe. It's like the carbon genus and the oxygen genus or is there some quality to carbon that makes it carbon ey and a different quality that makes it oxygen e? Right, And so we wonder like, is that come out of the internal structure? Are there the same bits inside are arranged in different ways? Can we explain them in terms of another deeper layer of reality? And so that's of course the goal of particle physics to keep tearing things apart and understand in the relationship between these things and what explains their nature what makes carbon carbony and what makes oxygen oxygen e? Right? Right? Because I guess it could have been that could have been the answer, right, Like we could have lived in the universe where carbon was one of the fundamental particles and oxygen was one of the fundamental you know, units of the universe, right, Like, it could have been that. But you're saying that once we discovered the electron, then we started to take apart the atoms in theory, Yes, and it could even have been possible at a higher level, you know, you're talking about elements, but it could have been that. You know, cheese for example, it was made out of some fundamental cheese object and couldn't be divided into smaller things cheese is pretty fundamental, at least to my diet. But yeah, it could have been that carbon was just one thing in the universe and oxygen was another thing. But if that were true, some physicists would wonder, like, what's the relationship between carbon and oxygen? Why are there two things? Why can't I express them in terms of just one fundamental thing? So there will always be people pushing at that boundary and wondering if there's a deeper explanation. But you're right, we don't know. And that's sort of where we are today in particle physics. With a few objects we think maybe our fundamental and we wonder about their relationships and if there is a deeper explanation. Right, Because we eventually broke apart the item, we discovered the electrons and the protons, and then the protons can be broken into courts, and the courts can be can be broken into cheese. Right, I hope that we discover some new quantum property and we call it cheese. We've called them flavor and color, right, it would be just as inappropriate. Yeah, but I was just kidding, But really we were down to like the court level. Right, as far as we know, when you try to break stuff down to its smallest level, we're down to corks and electrons and like their cousins in the periodic table of the standard model. Yeah, and all of this is just like a hierarchy of our understanding. It doesn't really define what we're talking about. Like we're talking about an electron, we're talking about quirks we haven't really specified, like what is that thing? You know, it's a word, we're saying, it's part of the and but what do we mean is going on inside the atom? What is the nature of these things? Right? I mean, that's basically the question we're asking today is what is exactly an electron and what exactly is a court? Because we as far as we know, you can't break those down into smaller little bits, right. And the cool thing is that you can make a lot of progress doing particle physics without knowing the answer to that question. You can talk about the relationships between these things. You can build one thing out of other things without even really understanding what it is you're talking about. And that's sort of my job is to try to make progress even though we don't understand like the core fundamentals, the true foundation of the nature of reality right, right, because we've talked about this in the podcast before. How there's this kind of progression, right, like to do engineering at least, like to build a building, you don't really need to know chemistry, and to do chemistry, you don't really need to know understand quantum particles, and to and to put together an atom, you don't really sort of need to know what is exactly a particle in a mathematical sense. But your job is to like go as deep as you can and break that down until like nobody can ever break it down anymore. Yeah, And that's true that you don't need, for example, to understand quantum gravity to predict the path of hurricanes. And I'm grateful that the world works this way and sort of layers of emergent theories, so you don't need to know how the universe begin order to make chicken soup, for example. But we're sort of clueless at another level more than just like the engineers not understanding how the corks work. We're dealing with corks and we still don't really know what they are, and we have these mathematical tools that we can use to predict what they're going to do, but they are so strange and so counter to our intuition that we can't really answer the question, like, what is this thing we're talking about? We have the math that describes it, but we don't have like an intuitive grasp of it. So then that's what you mean by particle. When we're asking what is a particle, we're really asking what is a cork? And what is an electro? Exactly? What is this thing we're talking about? What does it mean? What is its fundamental nature? And more than that, like what makes a cork different from an electron? The way you were talking about, like maybe carbon could just be different from oxygen. It could just be two fundamental elements of the universe. Why is a cork different from an electron? Like what makes them different? One of them has more cheese obviously. All right, let's get into possible ideas for what a particle could be, and as always, we'll talk about what does it all mean? Man, So let's get into that, but first let's take a quick break. All right, we are asking fundamental questions here on the podcast today, Daniel, we're asking what exactly is a particle? I mean, we know that matter can be broken down into atoms, and adams can be broken down into electrons and corks. But what exactly is an electron or a cork. That's a difficult question to answer. It is, and when you'd say particle, most people probably imagine like a tiny little dot of matter, like the smallest bit of stuff. And you heard some of the listeners answering in that way, and that's very convenient, but it's sort of an extrapolation of an intuitive idea you had that like, rocks are made out of small rocks, and those rocks are mad out of even smaller rocks, and when you get down to it, the universe is basically a bunch of super tiny little rocks. It does rock the universe the little cheesy sometimes, but it kind of rocks. It rocks my world for sure. But we know that that's not a completely accurate picture because when you get down to the quantum level, the rules do change. The rules for rocks are the classical rules. You know, the things move through the universe smoothly and continuously, that they follow rules of where you used to If something is here and then later it's there, it went from here to there. We also know that the quantum particles. The super tiniest little rocks in the universe don't follow those rules, so we need like a new concept for what's going on down there. At the very smallest level, we just say they're little, tiny rocks, right, because like one kind of physics is good for keeping track of rocks, that's Newtonian physics. But at the smallest level and things get quantum, things get kind of fuzzy, and then it's they're more accurately represented by waves, right, Yeah, And we have these equations, these wave equations, which seem to control what happened to these little objects, these little particles, and we can solve those wave equations, and they predict with a probability where these particles are likely to go. But already we're presented with a confusion, like, well, are we talking about these things as a wave as a particle? Do? I sometimes talk about them as a particle, sometimes talk about them as a wave. And hear lots of people saying that these objects are waves most of the time, but then when you look at them, they become particles. Right, that's a common picture. But I think that that's not really an accurate way to think about it. I think more accurate is to think that these objects are something new and different. There neither particles nor waves, though they can sometimes be described in analogy by either of those pictures. Interesting because I always thought about it them as you know, they're waves that sort of looked like particles from Afar. If you get down to the smallest level, they look like a wave, but if you used to just kind of pull back, they look more like a little bit of stuff moving around, except that sometimes they look like waves. Even from Afar. You know, you can see interference effects, which are macroscopic effects. A double slit experiment shows you that particles passing through those slits interfere with themselves and create these like macroscopic effects. This interference patterns on the screen. So these wave like effects can also influence you know, real visible stuff. Okay, so then that's one definition of a particle is that it's a collapse wave or like a wave that when you that that when you look at it becomes a particle kind of. There is a common attempt to sort of weave together this idea that maybe a particle is a wave and sometimes it acts like a particle when you look at it. Right. The problem of course, is that we don't really know what it means to say you look at it. We've had a few podcasts on this topic of the quantum mechanics measurement problem, like what does it mean to look at something and collapse its wave function? Why when an electron is flying along through the universe does the universe suddenly decide, Okay, we're going to take on particle like little mini rock like properties and decide now where the electron actually is. Whereas a minute ago we were happy having it being a quantum wave and having uncertainty to it. What makes the universe decide to draw from this random probability distribution and decide where the electron is so that you can look at it with your experiments. It sounds to me kind of like what's in your head is that you're thinking that a particle is something that has like a definite location and boundary and velocity and like you know where it is. It's like a little rock that's just sitting on your desk. But a quantum wave is different than that. Like, a quantum wave is not like a little rock, right, Like it's it's that boundary between uncertainty and certainty that maybe you think the definition of a particle is that's a the way to put it, and the reason is that we can't see uncertainty in that way. We can't measure the quantum wave function directly. We can't see a photon as in two states at the same time. We don't observe that. Ever, our experiments, they count particles. That's why particles are such a compelling concept. It's because it's what we see in our experiments. We can do single photon experiments when we see a one photon fly across the room and hit a screen. We never see a photon like in two possible states at once. That's only like what the universe does when it's calculating what might happen in your experiment. It's nothing we actually observe. That's why we use the word particle when we talk about things we actually observe, because that's all we can observe. We can't see those waves directly. Oh, I see what you're saying. You're saying that maybe one possible definition of the word particle is it's what happens when you sample a quantum wavefunction, right, it starts after the particle is seen or interact with something else before that it's not a particle. That's a common idea and it's compelling, but it's deeply, deeply flawed, right, because you don't have a clear definition for what it means to look at it or to sample it. You know, like we talked about before, if you're gonna poke this electron with your finger, then you know it has a wave function. Maybe it's here and gets poked by your finger, or maybe it's over there and it doesn't get poked. But when you touch it with your finger, the universe has to decide. But how does that happen? Because in the end, your finger is also made out of quantum particles, right, It's just made out of other electrons and quirks. So why can't it just interact in an uncertain way with that electron and leave things uncertain? At what point does your finger become a classical object that forces the universe to collapse the wave function? And what point can it stay uncollapsed? That's not defined, it's not specified, and that's what makes that picture totally unsatisfactory. And it also kind of leads you to the problem of like, what is it before before it collapsed or what is it before you measured it? Right, it's like a pre particle almost, which that doesn't help you. Yeah, what is that thing that's going through the universe? Like? Is the wave functioning a real physical thing? Is it just a calculation that's in our minds that we used to predict these things? Is the universe doing that calculation somewhere in its internal computer? Like? What's going on? What's going on? Man? All right? So that's kind of one idea. What you're saying. It's kind of flawed because they kind of doesn't help you. But then maybe what if I just think of a particle as that wave? Right? Like, what if I think of the particle as just an excitation of a quantum field. So the way the history went was that Schereninger develops his wave equation as a way to describe what's going on with these particles, and it worked amazingly. I loved you know, he just wrote this thing down and he had no real justification for it, you know, like it might have worked, and then it just kind of did, like wow, and predicted experiments. That's cool, But it turned out to be very hard to use because it really just describes one particle flying through the universe, and you know, the universe is filled with particles, and so as soon as you have like multiple particles, three or four, ten seven particles, it's basically hopeless. You know, you can't use the short in your equation to solve any realistic problem. So then the mathematical and physical geniuses in the first part of the last century developed this new idea of a field. Right, they have this idea of a field from classical physics. You know, electromagnetic field already existed, and they say, well, what if there are these quantum fields, and instead of describing one electron over here is one short in or wave, and that electron over there is another shorting of wave, we unify it into a big picture of an electron field, and both electrons are just wiggles in that field. And then we could just like you know, think about the motion of that field rather than the motion of individual electrons. I see, like before we thought of maybe electrons as like separate magnets, like there's one magnet over here, there's another magnet over there. But another way to think about them together, it's like they're all part of the same magnet, right, or they're all part of the same magnetic field of the universe. Yeah, and it's a really powerful idea, not just because it's helpful, like it lets you do calculations you otherwise couldn't do. The Shorting equation, for example, describes how a particle moves to the universe. It's very difficult to describe the creation or the annihilation of particles, but we know that happens all the time when you use fields. However, it's no big deal, Like you can create a particle, just excite the field another step. It's just like take the string and strum it harder. Or you can describe the destruction of particles when the field relaxes and releases that energy into like another field. So things that were hard now become natural. Right, And so in this view, the universe is filled with a field, and a particle is really just like a little like excitation in that field, like a little like a blip in it almost, And so we're all just made out of blips. Yeah, and don't underestimate the physical implications of that. It means that particles are not the fundamental element of the universe we're talking before about like fundamental versus emergent. Right, like ice cream cones are not fundamental property of the universe. You could expect there to be a universe where there are no ice cream cones, and maybe there won't be in the future, sorry to say. In that same sense, this means that particle holes in this view are not fundamental to the universe. They just like sort of are a description of how fields wiggle. The fields are the real fundamental building blocks of the universe. That what the universe is is space filled with quantum fields, and those fields wiggle in certain ways that we call particles. Yeah, like you, it's almost like we were looking at the tale of an elephant and we didn't know that. Really what's important is that there's a whole elephant and from us. Yeah, and it's really beautiful. As you get into the mathematics of quantum fields, you see so many symmetries and patterns emerge that just strike you as like, wow, I'm reading the truth about the universe. We talked in a recent podcast episode about a really subtle concept, gauge symmetry, which talks about like how these fields are related to each other. You can like rotate these fields so that one turns into another one, and you see these symmetries exist in our universe, and there are the reasons for things like why is electric charge conserved because there's a symmetry in the photons field it were wires photons to exist and acquires electromagnetism. So it really like feels like you're reading the deep truth of the universe when you get immersed in quantum field theory. But I guess the basic idea is to define a particle is just a little blip in the field, right, and it's really the field that kind of puts together the things in the universe. Yeah, you can have fields that exist without having any particles in them. And then a particle, as you say, is like you start with a vacuum and you put energy into it and it excites, And that's what a particle is. And it's not just that it's much more mathematically handy to do these calculation it also sort of solves a really deep problem which you alluded to earlier. Somebody asked Freemandeyson, the famous physicist, once what he thought was the greatest accomplishment in physics and the last fifty years, and he said that it was quantum field theory being able to explain why all electrons are the same. And you were saying earlier, like you can think of electrons is like just different magnets. But if you think about that, why I are all electrons the same? If electrons are just different particles, why do they all have the same mass? And quantum field theory it answers that because it says, well, there aren't a bunch of different electrons. There's just really one electron. It's just all the same excitation in the same field. There's only just one electron field in the universe. But how does that ans really question? Like why is this blip in this field the same as the blip in the field over there? Because the field only knows how to blip in a certain way. It's a quantum field, right, it can blip once or twice or three times. It can't blimp like one point to five times, right, that's just what the field knows how to do. The field itself has a mass. It gets that mass from the Higgs boson, and it gets the same mass over here as it gets over there, and it gets an alpha centauri. And so the single field that fills the universe, that controls all of the electrons. So then I guess what's wrong with this picture of a particle? Is there anything wrong with this of looking at particles? It's just excitations in the field. So if you ask particle physicists what's more fundamental a field or a particle, A lot of them say the fields are that this is sort of prevailing view. But there's sort of a stubborn minority that say no, no no, no, no. Fields are just the thing we used to calculate. Mima or Kannie Hahmed, who is a famous physicist at the Institute for Advanced Study in Princeton and widely considered like one of the smartest dues around, he said, the fields are just a convenient fiction. And the thing is that we don't see fields directly. Right. Particles are the things that we see. They are the things that we observe in our experiments and the things we smashed together in our colliders. Fields are what we used to do calculations. But like, are they real? The particles themselves are the things that we see that we can count, that we can interact with, right, Like, like, is it a thing or is it? Just? Like? I guess the consequence of how the universe works, like the math of the universe. Just because we have a mathematical description of how things work doesn't mean that it's real, right, what's real is what we see in our experiments, and those are particles, and we see how particles bounce off each other, and we see how particles interact with each other. And you can view the whole system of the universe mathematically without using fields, like you can say there are no fields, There are just particles and particles when they interact with each other, they don't use fields. They use virtual particles. So like when electrons push against each other, what's happening is they're exchanging photons. So you can replace fields, which just like sums over infinite virtual particles, and it's mathematically totally equivalent. You can do like all the same calculations using virtual particles. So like our fields just a way to express zillions of virtual particles all flying around or are particles just like vibrations in these fields. They're fundamentally mathematically equivalent. And it's a bit of a philosophical question, which is the right picture of the universe. I see you're saying, like maybe thinking of a particle or defining a particles and excitation in the field may not be accurate because maybe fields don't exist. So and so maybe it doesn't make sense for something to be of an expectation of something that doesn't exist, and that maybe particles are just their own thing and fields are just like this mathematical convenience that ties all the particles together. Yeah, we have this expectation that if we come up with a mathematical description of the universe that works, it must somehow be true. But it's not necessarily the case, and it's possible potentially to have multiple distinct mathematical descriptions of the universe that all work. And so you can't claim that, oh, like, I need fields to do my calculations, so therefore field must be out there and reel in the universe. They could just be a way that we do the calculations, all right. So you're saying kind of maybe um math is wrong or the math doesn't exist. We're saying maybe fields don't exist. Right. Math definitely exists, but we don't know necessarily if it's fundamental to the universe or just part of the way that we think. All right, So then that's another view of what a particle is. What's another way we can look at particles. Another way we can look at particles is maybe they are not fundamental. Maybe they're just like zoomed out, wiggling other things. You know, take like the field perspective to the extreme and say, like, well, what makes an electron different from a cork If you say that the electron is a vibration the electron field, and the cork is a vibration the cork field, why do we have these two fields, the cork field and the electron field. Are they somehow related? Is there a deeper relationship? And so string theory, for example, is a view that those two different fields, the electron field in the cork field are actually just one. Is some deeper field that like can vibrate in these other dimensions, and it looks like an electron field if it's vibrating one way, and it looks like a cork field if it's vibrating in another way. And so this of course is string theory, the idea that the whole universe is built on these super tiny vibrating strings. Interesting, like, there's only one field in the universe and it can vibrate in different ways. Yeah, one basic universe stuff, And that would be really satisfying because it would be a very simple answer, like what's fundamental universe? While you got this one thing and you can vibrate this way and it looks like a cork field, and to con vibrate the other way and it looks like an electron field. Like you were saying earlier, when you zoom out, they look different. When you zoom in, you can tell, Oh, it's the same old thing, just acting differently. All right, let's get into this with a little bit more detail, and let's drink people along on what strength theory is. And let's take another quick break. All right, we're talking about deep questions today. We are questioning what does it mean to be a particle? What is the definition of that, and what does it mean in terms of how it matches up with reality and how things really are. And so we talked about different ideas for what a particle could be, and the late one we talked about was about string theory, like maybe particles are just little vibrations in some kind of universal field that's just out there in the universe. Yeah, and you can take this as like an extrapolation of our current ideas of particles as excitations in a bunch of different quantum fields. Maybe we can unify all those fields together into the one universe field, and then electrons are a different kind of wiggle than quirks, and different kind of wiggle than neutrinos, And that would answer a whole bunch of really fascinating questions. You know, why are electrons different from neutrinos. It turns out it's just because they're wiggling and these other dimensions differently than neutrinos are. It would be super cool. So in strength theory, that that is what's kind of being assumed that is happening is that there's one field, you know, and is there a name for this field? The field? Not really, I guess if there's just one field, you don't have to give it names, right, the answer to distinguish things, it's the capital F field. Yeah. But you have string that are like one dimensional vibrations. You have brains which are like two dimensional surfaces brains B R, A, n E as in membrane, not as in brains like the thing in inside your skull. Right, But these are just that's like a mathematical concept. It's not really something that vibrates. It's just kind of like the dimensions of it, right, or the space of it. Well, you can have one dimensional objects, which are the strings, and you can also have two dimensional objects, which would be the brains, and these strings can sometimes vibrate between the brains. You can have all sorts of complicated things, but the fundamental elements of the universe, the particles that we're familiar with, would be made out of these one dimensional vibrating strings that vibrate differently. And again, you know, this is all speculative. We have no evidence for string theory. We don't even know if string theory is the right theory to do this. But as an example of how you could go deeper and you could get at some of these really interesting questions about like, you know, what makes quarks and electrons different the same we we were wondering, like what makes carbon different from oxygen? Right? It is that made be Electrons and corks are not actually particles, They're just like things put together from a smaller particle, right Yeah, Or maybe they are fields that vibrate in different ways and that's why they look different. So instead of thinking about the electron is made up of smaller things. Think of it like as a version of one larger thing, like the way we think about like the electron and the positron has two sides of the same coin, rather than two separate particles. We can think about the electron and the corks and the neutrinos and all these different particles as different kinds of wiggles that this one field can do. And so the electron field wouldn't exist really, even though we currently have a mathematical description for it. It would actually just be like a sub field of the the field. In the same way that like, does ice cream really exist? It's useful to talk about ice cream when you're doing physics at one level, it's not really useful to talk about like the fields it's made out of. Ice cream does exist, even if it's actually just a bunch of vibrating fields. So in that same sense, like, yes, the electron feel is a useful thing to talk about if you're like doing experiments with electrons, even if deep down it's just like a particular flavor of this universal string field. Well, I think the ice cream is definitely real. In my waistline. It tastes really good, that's right. Yeah, as real flavor. But that's kind of one idea for a particle. But then you don't you run into the same problem you did before, which is like, is a particle of vibration and excitation of this field or is the field itself? The field really the fundamental thing about the universe? Yeah, it doesn't answer that philosophical questions, just sort of like goes deeper down. The fields are fundamental route to try to unify all the fields into one field. It doesn't answer the fundamental question of our the fields actually real or is this just a mathematical picture? And that's something we might not ever be able to probe because in the end of fields are not something we see in the same way that early on in quantum mechanics, we had this idea of a wave function. But you can't see the wave function directly. You just see the particles and you do calculations about how the wave function influences the particles, but you never see the wave function. You can't see things in a quantum superposition, for example, And so it doesn't answer that philosophical question. All right, So another alternative, but maybe not a great definition of a particle. What is maybe another definition of a particle. Well, there are some folks that take a completely different view and trying to build a completely different idea for what a particle is. And I love these kinds of approaches because they like overthrow everything we've been working on for our hundred years and start from scratch. These are the folks that look at the universe as built out of little bits of space, you know, instead of looking at spaces like smooth and continuous. They say, well, what if space is made out of pixels and all those pixels are woven together using quantum entanglement. So you have this new view of the universe as like a bunch of little quantum pixels that are woven together into a fabric that we call space. Right there is the thedea of like we space is kind of like a foam almost right, Like it's not a thing, and it's not like a big emptyiness. It's actually like basically like a giant um, like a giant massive of bubbles right sort of adjacent to each other. So you start with that idea, and then you take it one step further and you make analogies to ideas we've discovered in quantum computers. Quantum computers are this different way to do calculations. By using quantum mechanical objects instead of classical objects like transistors or switches, you can do all sorts of weird different calculations. And if you aren't familiar with quantum computers, with the whole podcast episode on what that is. But some of the ideas from quantum computers people think might be applicable to this sort of like quantum space time. And so you can think of sort of like this quantum spacetime, this quantum foam. It's sort of like a huge array of cubits, these like fundamental elements of a quantum computer. You're started talking about maybe like reducing the physical universe down to just like information ation, Right, that's kind of one view of the universe is that it's not like real, it's not something tangible or spacious. It's actually just all kind of information ones and zeros. Yes, it's all about information, and quantum computing is about how you manipulate information. In fact, all computing is about manipulating information to try to get the answer to a question that you have, and quantum computers manipulate information in a different way than classical computers, and one of the issues they have when they're dealing with information and quantum computers is how to do things like error correction because quantum computers are a bit fuzzy, are a bit messy, and so they're trying to recover information sometimes when it's been fuzzed up and lost from quantum computers. And people have found that this actually is very similar to questions of like trying to get information out of a black hole. Another topic we've talked about in the podcast a lot is like what happens to information when it goes into a black hole? Particles fall into black hole, they contain information. If that black hole eventually evaporates due to Hawking creation, where is that information gone? And is this potential solution to this quantum information black hole problem that says maybe there's like quantum entanglements between the inside and the outside of the black hole. And people have restruction this now in terms of quantum computing and seeing connections between solutions to quantum computing error correction problems and black hole information problems and all that just to say like maybe it makes sense to look at the whole universe is like one massive quantum computer whoa. I mean, like maybe it makes sense, like you found connections between the physical world and this information world, and so maybe the whole universe is just information. Maybe the whole universe is just information. And then the connection back to the question of the episode what is a particle? Is that in some of these space times that arise from looking at the whole universe as a bunch of quantum bits that are all entangled, there are these entanglement patterns that sort of emerge, and they correspond to like localized bits of energy floating in our three D world. And so what you see in these quantum computers are like these packets of information that like to stick together and float through that quantum world. And is this what a particle is? You know? Do we have particles in our actual universe? Because underneath we have this quantum phone that likes to entangle in certain ways, so that information propagates and these like discrete blobs through the spacetime. It's very tentative and it's very speculative, but it's a fun, sort of brand new idea for what like a particle might be. Well, yeah, I think I need to smoke some more bid and wrap my head around this, But it sounds like you're saying like maybe the nature of the universe isn't the way we experience it. It's maybe just all abstract information, like you know, my the fact that I'm here. I'm not really here next to you or next to this my desk. I'm really just like one quantum bit clump of information in a represent in some universal computer. And this desk is also a clump of information. And some of we're all sort of related by quantum entanglement, and that we interpret that entanglement as like me being next to it. Yeah, and there are these rules these quantum bits like to follow, and that these behaviors that emerge from the way they interact, and some of those behaviors are what we would describe as particles. And so we're part of this system and we look around, we observe it, we describe these things. Doesn't mean that what we see is fundamental. What we see is emergent. It's more like ice creams and hurricanes than the actual units of the universe. And you can refashion these particles in terms of you know, some sort of like weird quantum bits as part of the universal computer. You know, again, this is like a speculative idea that is like ten years from being even a tentative idea, but it's already got a cool name. They call it it from cubit meaning like the whole universe comes from quantum computers. WHOA, Like, it's like something in the universe Earth is actually just a bit of information kind of right, yeah, like for something to be defined as something, it's all just information. Yeah. Yeah. The deeper idea is, if you assemble information in this sort of self organizing way, self perpetuating way, does that create a reality? Can reality just be like a projection of this informational arrangement? And so like you need several more layers of an appeals to really understand the meaning of that. But it's kind of like how you know if I play a video game on my PlayStation that there's this whole world, but it's really just writing on top of a bunch of you know, transistors, and it's all writing and as information as ones and zeros zipping about. You're saying like maybe an electron is not really a thing. It's just like a bit of information sort of writing on top of this quantum foam computer that is actually the universe. Yeah, or maybe that's what a thing is. That's what it means to be a thing is to be part of this quantum information in the universe computer those all the things we've her experience are just that, and that's what a thing is. And so it's a super fun idea because it gives you this like glimpse into an alternative view of the workings of the universe at like the deepest level. But you know, it could also just be bunk or clue, or it could all just be in an aliens PlayStation quantum PlayStation PlayStation qute. Why don't they just press the cheek codes already so I can get to the next level? Yeah, when am I going to upgrade? That's what I'm waiting for. But I guess, you know, maybe I wonder if it could be all all be Like all of these ideas about particles, I wonder if they could all be true. You know, like maybe an electron is a bit of information on a quantum computer, and it's also a vibration in a one unifying field, and it's also collapse wavefunction, you know, do you know what I mean? Like, maybe these all these ideas are just different ways of looking at what's actually true, just like sort of Raschumn style, we might all have different stories to describe the same series of events. There might be multiple ways to describe reality that are self consistent and predict experiments and yet fundamentally at their hearts, like conceptionally very different. And that's a little scary because it means that maybe there isn't a single truth about the universe. Maybe there are multiple truths, or maybe there is no truth. There are just those stories, those mathematical stories we tell ourselves about the way the universe out there works. And so to you know, bring it back to aliens again. I think it would be really exciting to talk to alien physicists and discover, like, do they have a completely different way of thinking about the universe? Is a particle even a concept for them? Or have they discovered the same structures as we have and what does that mean about their universality? Right? Or like we talked about earlier, maybe there is a truth like there is such a thing as a particle, but our brains and our way of doing or you know, limitations and math and thinking only allow us to look at it in these different ways. But really, there is a truth that which but we just don't get it or can't get it, or we get it as much as our dogs understand hurricanes or maybe your dogs of view of the universe is the correct one, right, May we're just overthinking things, Daniel's what I'm saying. Maybe the universe is really just all about treats and not treats. Yeah, and naps. Really that's the fundamental element of the universe, the knaps. Certainly, your dog seems happier than most particle physicists. True, I think my dog is having a better life than I am. That we should all be dogs. We should. I'll be my dog. But I guess again, just another interesting, you know, exploration into what it means for things to be real in this universe and what's at the heart of reality. You know, it seems like we we still don't know and may never know. We still don't know, and we may never know. But we're gonna have fun along the way and make a lot of friends. And you know, even if you answer this question, you know, what is a particle? And you decided when you did some experiment or some philosophical argument to persuade yourself that fields where the fundamental element of the universe. You could still ask, all right, but why why does space have fields in it? Where these deals come from? Right? Do you have to have fields? Could you have space without fields? So even if you answered all these questions, you would still have plenty of stuff to dig into. Or you can say the alternative, which is um, whatever, time to take a nap. Yeah, I'd like to eat a treat, take a nap. That is something actually that professors and dogs have in common, is taking afternoon naps. You're a little rougher. Well, my bark's not as bad as my bite. All right, Well, we hope you enjoyed that trip into asking questions about reality and what does it all mean to be something in the universe? And this is a question for me of particular interest. We'd like to send you off today with a song sent in by a listener, Ben Kelly. This song captures the spirit of wonder we feel when we think about the amazing strangeness of reality. So this is Ben Kelly and his band The Amber Bugs. We took a used at nature and saw there's nothing No bad rocks build from a floor on the feet that pture of the house I'm plants around the sun that ain't put it of th stuff juice way. Everything is made up like this, Everything is just made up. Everything is made up. You're gonna have to base office. It's not just made up. Thanks for joining us, See you next time. Thanks for listening, and remember that. Daniel and Jorge Explain the Universe is a production of I Heart Radio. For more podcast from My Heart Radio, visit the I Aren't Radio app, Apple Podcasts, or wherever you listen to your favorite shows.