The Sticky Story of the Gluon's Discovery

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Speaker 1: Hey, Daniel, is size as dramatic as they make it out to be in the movies? You mean, like we all wear white lab coats and go ah ha while making discoveries in the shower. I don't want to know if you wear a lab coat in the shower. But isn't that dramatic? No, it's not usually so exciting. I mean, you don't storm into a room with a piece of definitive evidence on a piece of paper and claim some amazing discovery all the time. I'm waiting for the day I have a chance to do that, But so far nothing really that doesn't happen in particle physics, not usually. But there was this one time in which you wore a lap coat in the shower, or in which he had definitive evidence. I'm not going to answer that question. I am poor handy cartoonists and the creator of PhD comments. Hi, I'm Daniel. I'm a particle physicist and I love storming into rooms with definitive evidence. How often do you get to do it, Daniel? Never? Almost never. I'm desperate for an opportunity. How do you know you love it if you've never done it? I dream about it? How was that you stimulated in your head. It's funny when I talked to young students who are interested in particle physics and they read about big discoveries and amazing revelations about the universe, and then I tell them that, you know, we don't make discoveries every day. It's not like that on a day to day basis. Unfortunately, really, you throw cold water into their optimism and enthusiasm. I do. I don't want to mislead them. And then I show them all the fun puzzles that we do get to solve on a day to day basis, which is more like why is my code not working? And less like what is universe made at of? And then they walk out of your office? Or are they hooked by the small puzzle? You get some of both, You get some of both. Welcome to our podcast Daniel and Jorge Explain the Universe, a production of I Heart Radio in which we try to hook you on the puzzles of the universe, the big questions about how the universe was made, how it all fits together, why it works at all, and whether we can understand it. Yeah, because science is a process, it's real people asking questions about the universe and trying to figure out how to answer those questions because it's not always clear. That's right. It's people pushing forward individually with their curiosity on the boundary of knowledge, trying to figure out is this the way things work? Is that the way things work? Does this particle exist? How about that other weird particle? And sometimes there are dramatic days of discovery, though those are few and far between. Usually it's more subdued. You would say, you know more about you know, slow discoveries or slow consensus of discovery, slow discoveries. You know, these days the particles were discovering take more information to find them. You don't have like a single picture of an event where you say, oh, look at this new weird particle that nobody's ever seen before. It's more statistical. But back in the early days of particle physics, you really could. You could like have a cloud chamber and you could see a particle decay in a new way that nobody's ever seen before. So you could have this like single event discovery. But those days are behind us. Do you think those people would also describe it as exciting and dramatic or maybe I wonder if it was still a slock for them, you know, like it was. It was incremental and slow for them. I think there were a lot of boring days in between the dramatic days of discovery, but those individual days must have been pretty exciting. I think about the way archaeologists like dig for human bones, and sometimes you hear about like a twenty five year career that finally they found a jaw bone, and I'm thinking, like, why do they keep digging after twenty two or twenty three years. That takes a lot of determination. They were waiting for so much to throw them a bone to their career, and then it happens and does happen. And that's why I think these stories of discovery are useful because they help inspire the next generation of scientists to remember that we don't make discoveries unless somebody keeps pushing forward. At least it helps get them into your office, at which point you discourage them and tell them the real truth about research. I tell them the real truth to encourage them, because there's lots of different ways to do science. Some people like to do science by writing programs. Some people like to do science by tweaking lasers in the basement. There's lots of different ways to do science, and the most important thing is to find the way that you find fun. Well, it is fun to discover new things. And so today we're gonna be talking about a very specific discovery that was done in particle physics and Daniel, this is a bit of a sticky story. It is a bit of a sticky story, and it's part of a series of episodes we've had on how we understand the standard model. We know that everything is made out of particles, but how do we know that those particles exist? Are they just theoretical ideas? What experiments did we do to really reveal them? And for me this is really fun because minds people that all these concepts about how the universe works came out of individual experiments, things people saw, weird stuff that happened when we smashed stuff together that reveal the nature of the universe. And by standard model, you mean sort of like our collection or our idea, our our survey of all the particles that make up the universe. Right, Yeah, we've been building it for decades now. Our understanding of what is out there, what kind of particles can be used to make up the universe not just what particles are used to make up me and you and hamsters and lamas and ice cream, but also what kinds of particles are possible, and that gives us a sense for like how the universe is organized and what the patterns are, and and gives us access to some of those really interesting fundamental and basic questions. But we find these one at a time, bit by bit, sometimes after years of painful work. So you call this list or this I guess it's more like a table or like a like a grid of particles. You call that the standard model. Yeah, the standard model is sort of like our current consensus list of particles we found and what we know about them. And so it's filled with a bunch of particles, about twelve of them right so far. Yeah, there are twelve matter particles, the kind of particles that make up me and you and all sorts of stuff. And then there are other kinds of particles that represent forces, the way the things push against each other and pull themselves together. And so there's a handful of those extra particles as well. Yeah, and so today we'll be talking about one that's I mean, you could literally say it's at the nucleus of all the things that we're made out of. Right, that's right. It holds all of us together. So to be on the program, we'll be asking the question how was the glue on discovered? And the glue on is one of my favorite particles because it has such an awesome name. I wonder what that meeting was like. They're like, um, we got this new particle and it's it's really sticky. I can't get it off my fingers. You know. I did a little informal survey here in my household just a few minutes ago. I asked my kids. I said, if I said the word glue on to you, what do you think that means? And my daughter said, I don't know something particle physics ce maybe, but it sounds kind of sticky, and so I thought that was a pretty good guest. Yeah. I think having a particle physics dad might have influenced their answer. That could have been a clue. Yes. Yeah, So this is one of the fundamental particles and it's it's pretty important, right, It's definitely very important. Without the glue on, we would not be here, nuclear I would not hold together the universe as we know it would look totally different without the glue on, but it took a while for us to find It's a pretty interesting story and so we'll jump into that. But first we were wondering how many people out there know about I guess, first of all the glue on, and second of all how it was discovered. So, as usual, Daniel went out there into the wilds of the internet and asked people to send in their answers without looking it up to what they thought was the process in which the glue was discovered. That's right, and so if you'd like the volunteer to answer hard physics questions with no preparation and no googling, please right to us two questions at Daniel and Jorge dot com. We'd love to put your baseless speculation on the podcast. So think about it for a second. How would you answer the question what is the gluon? And how was it discovered? Here's what people had to say. I don't know how the clue one was to check it, but like the rest of the tenant and wh community of an imagine, it happened at the LHC and it's discovery as an epic tail that changed the fundamental understanding of the universe, maybe by firing lasers at protons and then protons explode and you can measure bluans flying away. It was about time he was hiding for a long time. Probably was a sting operation there. I think gluon is what holds quarks together. So my guess is, when quirks were discovered, um, we wanted to find out, well, what connects these quirks, what's the strong words that holds these things together? And that might be how blue ones were detected. I think that it's likely that some physicists or scientists discovered it by a happy accident. I think particle physics, you take normal matter, you smash normal matter, normal metal goes boom, and all that is left is some viad stuff. Alright, A lot of people, uh want to give you credit. They think it came from the LHC. That's right. Everybody just gives all the credit for particle discoveries to the latest, hottest, biggest, sexiest collider. Yeah. Well, you guys have taken up a lot of headlines, at least in the last ten years. Yeah, well that's true. That's because it takes a while to build a collider, so you don't get like a new one every year or so. So when you build a collider it sort of takes up the popular imagination for a couple of decades. Well, there are a lot of answers here about it holds nuclear together, involves courts and lasers. So a step us through this, Daniel, I guess, first of all, what is the gluon and does it dry really quickly or do you have to wait like twenty four hours. Well, first of all, I have to say I wish that I had more lasers to play with in my job. Mostly it's just tapping on a keyboard. I don't get a fire laser basically anything ever, which is too bad. Well, you probably have a laser in your mouth, right, but you have a little like a laser. That's how your mouth probably reads where it is. Yeah, that's true. There are lasers everywhere. I have a laser in my laser pointer, which I used to use for lecturing when I gave lectures in person, but no more anyway. A gluon is a really fun particle, and it's a really important particle, and it's connected to the strong nuclear force, and I has sort of the same relationship to the strong nuclear force that the photon does to electromagnetism. Electromagnetism, you remember, is the force that gives us like electricity and magnetism. It's you know, the thing that gives us lightning and electricity and all that good stuff. And that force is carried by the photon. Like any time you have an electromagnetic interaction, you have photons flying around carrying that information. Really, so it's sort of like the transmitter particle the photon. Yeah, exactly. We break up particles into two kinds, matter particles, which are like electrons and corks and that kind of stuff, the stuff that makes up matter and stuff, and then the force particles. And that's how the particles talk to each other. And you can think about two electrons coming near each other. How do they bounce off each other? They don't have like physical edges that touch the way that your elbow touches the table. What happens. They shoot photons at each other to talk to each other and bounce off each other, even like a fridge magnet, or like if if I take two magnets and they repel each other, they're actually shooting photons at each other. Yeah, and it can get a little hairy to think about what the actual photons are. Really. What we're talking about our wiggles in the fields between them. So every magnet has a magnetic field, and when it moves, it changes that magnetic field, and infer nation about the changing field is what we call a photon. These aren't always the same kinds of photons that hit your eyes. That can have very low frequency, a very high frequency, or sometimes they're even virtual particles, not particles that like live a very long time. We have a whole fun podcast about what it means to be a virtual particle. It's just sort of the name you give to the wiggles. When two particles talk to each other, yeah, exactly. The way they talk to each other is sort of action at a distance. You know, people wondered for a long time, like how do things push on each other without touching, And the answer is that they have these fields. Right, An electron, for example, as an electric field around it, and that field is what pushes on the other electron. A totally equivalent way to think about that field is to think about it as a bunch of particles. So you can either think about as fields or particles. For now, we think about it as particles, or think about those particles as the wiggles in the fields. It's really all equivalent, right, And so the gluon is the one that transmits to force for the strong nuke your force. So that's one of the one of the fore fund mental forces. Electromagnetism and gravity are two of them. A third one is the strong nuclear force. That's right exactly. And we spent a lot of time understanding electromagnetism. The first theory of quantum fields was by Feynman and quantum electrodynamics with the understanding of how electrons use photons to talk to each other. And then we thought, well, can we also use this for the other fields and the other forces, and so like the strong nuclear force is a very important one. So people were thinking, if electromagnetism has a particle that's used to go back and forth between electrons, what's the particle that goes back and forth between corks when they interact using the strong nuclear force. And so that's the idea of the gluon. That's why we thought maybe there is a gluon in the universe. And I guess maybe just to recap the strong nuclear forces. It's not a force that we feel on an everyday basis, like you don't, so they need to know about it. But it is sort of what's keeping the nuclear of your atoms together, right, Like it's pretty much the sort of the main place where it acts. Yeah, it's a very short range force, and so it likes to hold things together very very tightly. It's very very powerful, and so it's mostly balanced out. Like anything that's imbalanced on the strong nuclear force. Very rapidly that force will realign so that everything gets like smoothed out and balanced out, and that you don't feel the force anymore. And so it operates mostly very short distances, like the size of the proton. It ties those corks together into a proton and hold it together. And what you feel on a normal, everyday basis is mostly electromagnetism, like when you push against the wall. It's the electromagnetic force of the bonds of the electrons to the atom that are keeping the atoms from passing between each other. Right. But it's very short range, and that like if I have a cork here and a court meter away, they're not going to feel the strong nuclear force, right, It's only when you get them really close to each other, but they then snap together. Yeah, actually you can't have a cork by itself because the strong nuclear force is so powerful that it as soon as you create a quirk by itself and give it like any distance at all, the energy stored in the strong nuclear field is so powerful that other quarks will just be created out of the vacuum to surround it. So the situation you just described, having like two quarks a meter apart is essentially impossible in our universe because so much energy would be stored in the strong nuclear force between them that would just create a shower of other matter in between them to surround them with other quarks. Well that's wild, all right. Well, well, so that's the gluon, but it's different than the photon. That's the gluon exactly, And it's different from the photon, like it's the force particle for the strong nuclear force, and the strong nuclear forces also created different from electromagnetism in lots of other ways, Like it's not just that it's a short range force and it holds a nucleus together. It's different because it's more complicated, like electromagnetism has positive and negative charges, and photons only interact with things that have positive and negative charges. Like if you're neutral, like a neutron or a neutrino, then you can't interact with the photon. The photon ignores you. You on the interact with things that have positive and negative charges. But the strong nuclear force is really weird. It doesn't just have two charges like positive and negative. So you can't like line them up on a number line and think about like plus one plus two zero minus one minus two. It has three different charges, three different directions, so you need like three axis to think about instead of just two, Like it has a plus and minus and a and an x. Yeah, And so instead of lining them up on the number line, we actually think about them in terms of colors. We think about them and the red axis, the green axis, and the blue axis, and that sort of works mathematically because if you add them all up together, you end up in the middle. We call that white or like color lists, And so we try to make this analogy to how we know colors mixed together to help us think about these color charges. These are not electric charges. Their charges for the strong nuclear force their color charges. And I guess maybe a question is how do we know about these different charges, Like it's such a strange concept, it's really weird. And it was a cool discovery actually in the sixties and seventies because when we first started understanding that particles are made out of quarks. You know that protons have quarks inside them, we found all these other particles that were different mixtures of quarks. We found this really weird one, the delta plus plus particle, and it was made of three up corks, which just like three upquorks combined, gives you this doubly charged delta plus plus particle. But there's a problem with that because we think that quarks are fermions. That means that, like electrons, you can't have two of them in the same state. Like you know how if you have an atom, you put an electron around it, the next one has to go up in the next energy level. You can't like hang out together. For meons don't like to be together in the same quantum state. And so the problem with the delta plus plus is that it has three of these corks, but they should be interchangeable, Like how can you have three fermions all in the same quantum state? Together in a particle seemed to violate this basic principle, and so somebody thought, well, maybe they're not the same. Maybe they all have like a different color charge. One is red, one is green, and one is blue, and that would explain it. And so that was sort of the origin of the idea. And so I guess maybe courts can have any one of these three charges, like an upcork or a down court can be red, green, or blue. Yeah, exactly the way, like an electron and positron are related because they have opposite electric charge, but they are a different particle. A quirk can be a red cork or green cork or blue cork. We don't call a different particle. What the truth is that there are three different kinds of up corks. They really are different particles. Green upcork is different from a red upcork or a blue upcork, the same way an electron is different from a positron. All right, So that's the glue on. The blue on is what transmits the strong the dervors and which therefore holds all the quarks inside of your protons and neutrons together, which is kind of important. Without it, you would just fall apart. You totally would be because I remember that these corks also have electric charges, like a proton has two up corks in it and a down court, and the charges they were totally blow it apart if the glue wasn't there to hold it together. So thank you gluon. Thanks thanks for sticking with us and sticking us together. All right, So it's super important, and people theorized that it might exist, just like the photon existed, But discovery of it was pretty interesting and pretty dramatic. So let's get into that. But first let's take a quick break, all right. So we're talking about the discovery of the gluon, which was not a simple or easy discovery apparently, Daniel. Yeah, and it was a dramatic race actually between two different groups of folks, the Europeans in Americans, both trying to build a collider capable of discovering the gluon and racing again to each other. Wow, that does sound dramatic. So I guess people knew that it probably existed, right because it something must be transmitting the strong nuclear force. But I guess maybe just the question was like nobody had seen it, right, nobody had seen it on like a piece of paper or an experiment. Yeah, so this is like the late seventies, and at that point we had found all the corks, the up, the down, the charm, the strangers to bottom, but not yet the top corp. People were pretty sure the top cork was out there, but it's gonna be another fifteen years or so before it was discovered. And we knew about the photon and electrons and stuff, but all the other force particles that we now know that gluon, the W and di z, those had not yet been discovered, and so we really only had evidence for one force particle, the photon, and so we were pretty sure the glueon existed, but it was kind of a big extrapolation, and so it was gonna be really nice to say, like, wow, it really existed actually out there. It was sort of a big question for particle physics whether this whole like forces as particles moving between other particles thing was real, you know, the same way like we think maybe gravity has a graviton, but nobody's ever found it before. We could be totally wrong. Maybe gravity doesn't work by exchanging particles. So it was really a big open question. It's easy to look back on these things and say, oh, yeah, well that was obvious. But at the time there was a lot of uncertainty about whether this whole picture of particles talking into each other by passing other particles back and forth was really valid. We didn't know the idea would stick together. So I guess maybe you know it's interesting because a photon you can sort of see right, Like you can literally see a photon it it'll hit your eyeball in the back and you'll see it. But concluance do that too, Like can you see an individual gluon? Like can it float out into space and hit your eyeball? Well, a gluon, like a cork, can't be by itself, and that's because it's colored, not in the sense of it like is red, green, or blue, but in the sense of the strong nuclear charge. And anything that has a strong nuclear charge has so much energy bound up in that fours that immediately creates a spray of particles. So if you had a gluon flying through the air somehow, what would happen is that would create other quirks around it to balance out that color charge. So what you get is a stream of particles. Wait, a gluon has charged, but like a photon doesn't have charge. A photon is neutral, right, Like light doesn't have positive or negative charge, but gluons do have charge. Yeah, and that's one thing that makes a strong force very different from electromagtism. You totally put your finger on it. Photons don't talk to each other. Like photons passed right through each other. They don't have electric charges. Photons can only talk to things that do have electric charges, but they don't talk to each other. So like two rays of light don't bounce off each other. But gluons, you're totally right. They have color and they actually carry two colors each of them. And because of that, they can interact with each other. And so two gluons like shooting at each other with totally like form a little particle. In fact, we're searching for that. We're gonna talk about that later. It's called a glue ball when you combine two gluons and do a particle and glue ball. Nice, all right, So there was a race to detect the glue. So we said, have had an idea of it and maybe a theory about it, but nobody had actually seen it until people were smashing things together hoping that one one would pop out, or that you know, evidence of one would pomp out. Yeah, the idea was that you needed enough energy to make them. What we had done already was smash particles together and see pairs of quarks. So you can smash, for example, an electron and a positron together, and those will annihily and turn into a little ball of energy like a photon. And sometimes that photon will turn into two quarks, like an up quirk and an anti up cork. Whence you get there, there's two quarks flying out. But because of what we talked about earlier, how corks can't be by themselves, each one turns into like a stream of particles. We call this a jet of particles. What do you mean a stream like? Wouldn't that mean that they're like one in front of the other, or wouldn't they stick together? Well, you have two quirks coming out a really high energy back to back, so like one with a lot of energy in one direction and other going in the other direction with a lot of energy, and so they don't stick together because they have too much energy. They're flying apart. So it happens that they create new particles out of that energy and turn that energy into mass. And so instead of one cork flying one way and antiquork flying the other way, you get like ten quirks in the deck, quirks in one direction and ten flying the opposite direction, like one in front of the other. They come together because quarks don't like to be by themselves, and so they form other particles. So you never actually see a cork. What you see are particles made from corks. You see protons and chons and pyons and masons and all sorts of crazy stuff. So when you create a quirk and an antiquork, you create these two jets of particles. Each one has particles inside of it that are made of quirks. Okay, but I guess you don't actually see the individual gluons. Then you just see kind of like the gluon after it's created friends for itself. Yeah. So people had already done that. They had seen pairs of quirks, and the idea was what would happen if you put more energy into the collision. You pour more energy into this electron positron pair, and there might be enough energy for a gluon to be created. So not just create the cork and antiquark, but also in addition, create this glue on, because just like an electron can give off a photon if it has a lot of energy, a cork can give off a glue on. It can radiate a glue on if it has enough energy. Because it's just so much energy flying around that you might occasionally randomly create one and send it off in a new direction. In that case, you would see three of these jets, not just two back to back, but three, and sort of like a Mercedes pattern, each flying off in a different direction. But we hadn't yet done that. We hadn't built a collider with enough energy to create these gluons. So the idea was build a bigger collider, smash particles together, higher energy. Maybe instead of just seeing two quirk jets back to back, you'd see two cork jets with a glue on jet coming out the side right, But you wouldn't see the glue on. The clue jet would just be again more quirk, yeah, exactly. You wouldn't ever see the glue on directly. So it's frustrating some times in particle physics because these detections are never like perfect little pictures. It's not like we went hunting for a unicorn and we have a picture of the unicorn and it's indisputable. They're always sort of indirect and here with cork and gluons, you never catch them by themselves. You just sort of see the evidence for what they made. You just see the hoofprints and those parkles. Yeah, it's more like you look for a celebrity and instead you see like the paparazzi around them. Because these corks and gluons create these whole streams of particles which you can see. You can't actually see those anyway. So there was this race between the Americans and they were building a collider at Slack, and then the Germans were building one at this collider at Daisy, which is a lab outside of Hamburg. See, so it's Americans versus Germans. Slack is the one at Stanford, right, Stanford Linear Accelerator, the Complex Center Club collider, that's right. And so it was the late seventies and everybody was trying to build their collider to get there first, and the juror Wins turned to sort of an unusual source to build the materials and the facilities for their collider. They had a revolutionary idea to hire manufacturers that used to build refrigerators what to build their collider. Yeah, and so they subcontracted out to this refrigerator company, and that company would like able to ramp up really quickly and deliver the parts and needed for this accelerator. It's called Petra p E t R A. And it may be the first collider ever in the history of particle physics to turn on ahead of schedule and under budget. What it was also the first one to have an ice dispenser. Conveniently, somehow they stunked it in. So well, why French manufacturers just because the equipment was similar, or they're they're just good German engineers. Yeah. Both. You know, we use a lot of refrigeration in particle physics, but mostly we're building you know, high precision machined objects. You need these vacuum tubes, you need the struts. And they were in a race and they said, hey, look, this company says they can do it. Let's get at them to try. And so they gambled a little bit and one so they were able to build their collider and come in ahead of the Americans. Which so this one and Slack we're being built at the same time. We're being built at the same time. Yeah, and then unfortunately the Americans went with the toaster manufacturer, which had a lot of delays. Is that what happened. They spent all their money on avocados also an anticipation of the toast, and then they went bad. These Californians too far out, all right, So the Germans build it first, and so did they find it first or what happened when they trend it on? So they found it first, and they cranked this thing up. And you know these days are colliders are very very high energy. You know, the LHC, for example, works at fourteen terra electron volts, which is fourteen thousand billion electron volts. Back the end in the day, in the late seventies, it was a big deal to have like thirteen billion electron volts. And so this collider turned on first at thirteen giga electron volts and then i ainked its way up to like twenties seven giga electron bolts in the spring of nineteen seventy nine. And the cool thing about particle physics discoveries is that once you have enough energy, it can come pretty quickly. Like the barrier to creating these particles, it really is just having enough energy in your collisions. And so once you turn it on and you have enough energy, you really only need a little bit of data to actually find something, because I guess things are quantum, right, So like you need to hit a certain threshold of energy before certain particles will be created, because you can't like make half of a gluon, right, that's right, you can't make half of the glue on. What you can do is make a low energy glue on. And so what you need to do is put enough energy into this collision that the gluon can grab enough the energy that it can fly off by itself and make that third jet. So people have seen events with two cork jets in them, but nobody ever seen a gluon come off and make that third jet. So as you crank up the energy, you expect to get more and more energy into the gluon, and then the glue one should have enough energy sort of like fly off and be on its own so you can actually see its own third separate jet. Alright, So then how much further ahead were the Germans like were the years or months ahead of the Americans. It was just months ahead. And there was a conference in the middle of the summer in nineteen seventy nine that everybody was aiming for, and the Germans were hoping to turn their machine on and to see this and to deliver decisive results at that June conference. They're hoping to have some pretty cool results to freeze out the Americans with their fridge collider. They were going to stick it to him. All right, well, let's get into the actual discovery of it, because um, apparently it was pretty significant and interesting to finally get to that big drama moment. But first let's take a quick break. All right, Daniel, we are in the late seventies right now, nineteen seventy nine, and the Americans are competing with the Germans to discover the glue on and so finally the Germans build it first. They're collider and discovered it. Was it that simple or was it? Was? It kind of a hard discovery to make. It was a little bit tricky, and that's because this is the first era of colliders where we really have a lot of data coming in, Like you're doing collisions many times per second, and then you need some sort of computer assistance to sift through all these collisions and find the most exciting ones. These days, everything we do is on the computer. Like at the large hage On collider, you know, there's millions of collisions per second, and the computers sift through them before we ever look at them. In the early days of particle physics, you had stuff like, well, you had a collision, you took a picture, you looked at it, and you looked at the next one. This is the first time we really had filtered the events and the collisions by the computer. But you know, it's the nineteen seventies, and so the computers back then or like much much slower and less powerful than the computer that's literally in your refrigerator today. Yeah, they had They took up whole rooms, and you needed punch cards, right, Yeah, they had punch cards, And so they had to be really careful and clever about how they're going to use these computers. And not a lot of memory in them, you can't just you know, write whatever computer program you want to be sloppy about it. So there were a bunch of folks who wrote some really clever computer algorithms to try to isolate these events where you had three different sprays of particles, and they wrote this code to like figure out on what was the best angle to look for these three prongs and to isolate the events that were most likely to look like this. And so not only did they build this accelerator ahead of schedule, but they had this cool new snazzy computer software to help them sift through all the collisions to find the one they were looking for. They're like, see this little paper cardboard card, that's my awesome new algorithm. It's pretty funny. Actually, I remember my dad writing his master's thesis in and nearing and using punch cards and you know, feeding them into the computer and then it doesn't work, and he's gonna go to the back of the line and the way to turn again to feed them in. It's pretty crazy. I guess you need a computer because how are you getting all this data? Like you're getting this data through detectors or like are they recording these events by hand? These are definitely from detectors. And so just like at the led C, the collision point, the point where the electron and the protons smashed into each other is surrounded by layers and layers of detectors that image particles that come out. So the electron apolittron collide together in the heart of the detector, and then you know, whatever happens happens and things fly out, and we have these layers of detectors that say a particle passed me, or a particle passed over here, and then we use that to sort of try to get an image of what happened, so you can think of it's sort of like a three D camera that makes a picture of everything that's flying out from the detector. Where it went. All right, So then they ran it and they found the glue on. Did they find one event of the gluon or whole like millions of events? What did the data look like. Did they have to you know, sort of like sift through sand or was it like one big like boom there is They did actually have to sit through a lot because luans are not that common at those energies. Most likely you're just gonna have two corks back to back and it's two jets. So they had to say through a lot of events to find one. But then they did and they turned it on and this is like in June of nineteen seventy nine, they're like, you know, a week before the conference and they find one. Their computer says, ding, ding, ding, we found one that's interesting. Take a look. They print this thing out there, like you know, lay it flat on a piece of papers that they can see what it looks like. And it's very clear. There's like three of these sprays of particles, not too like you expect to see from two corks, but there's three. There's definitely this whole third jet that's flying out the side. And they looked at it and they just knew. They were like, this is it. And they went and they brought like that transparency to this conference in Bergen and like slapped it up there during the presentation and showed it and that was it. Like everybody was like, Okay, that's it. You have found the gluon were convinced just one event, like they didn't wait to get to After that, they collected a lot more data, and you know, one event was enough to convince people this is coming. They didn't actually write the science paper until they had a few more events to support it, and other detectors at the same accelerator had seen it, etcetera, etcetera. But that one event really broke people's skepticism. That one event told them, yeah, this is real. The backup data is coming, but now we know it's here. So that was sort of a famous event. You know, people were at that conference or in the field know that one event. They know what that picture looks like. Have you talked to anyone who was in the room when they did? They did they actually slapped the transparency down on the overhead. They stormed in white lab coat flaring behind them. You know here it is boom. But this is sort of what I imagine, like this is the moment of discovery. This is sort of the thing that we all hope for that you're trying to crack a problem in the universe in particle physics, trying to understand how things work, and then it's just revealed to you. You like, see it, there's the answer. Gluons are real. This kind of event, this three jet event, just couldn't exist without glually, it couldn't be like noise in the system or some kind of fluke or some kind of um, I don't know, some weird other thing that could have happened with the equipment. Yeah, you know, there's a possibility of that. It's very unlikely for it to just be some weird, noisy fluke, but it's a possibility. And so of course they cross checked their results and other people saw similar things, and so eventually the data was just indisputable. But that first event will always be the one that like really heralded the age of the gluons and also opened up this whole era where we think about forces as transmitting particles. This really showed us that this picture of sending particles back and forth as the way forces work was not just limited to electromagnetism. It also worked for the strong force, and it led to other discoveries. A few years later. All right, well, then what have we learned about glue on since then? Like what makes them express special or weird? Well, gluons are weird because, as you say, they can talk to each other, Like each gluon carries colors with it, and that means that they can talk to other gluons and potentially they can even like hang out together. There's this idea that if you get two gluons and the right configuration, they can even form a particle just made out of gluons. This would be like a thing that's pure glue, right, because they like if you get three of them with different charges, when they just naturally stick together. Yeah, and there's also complicated math of ways you can combine gluons that make a color neutral object. You can also just do with two gluons. They can have the opposite colors of each other. Now, nobody's ever seen this before. We call this a glue ball. And their experiments out there, one of them is called glue X that's looking for exactly this kind of thing. So we don't know if it's real, sort of in the realm of things people have predicted calculations we've done. We don't know if we will see it. If it does exist, it's not going to be that heavy. It's just like about the mass of a proton or so. But it's pretty tricky to spot because if it does exist, it's gonna look a lot like other stuff. And it sounds more like a playground game Globall. Okay, let's play goloball. Yeah, exactly. So we're looking for these particles made out of just force particles, you know, is there any president for that? Like, you can't make a particle out of photons. Right now, the strong force is the only one where the force carrier actually feels the force. You can't make a particle out of two photons. And a few years later we found other force particles. There's the W and the Z bosons. These are the ones that correspond to the weak nuclear force, and they also they don't feel the weak nuclear force, right, so you can't make a particle just out of ws and zs. So the strong nuclear force is definitely weird. It's weird and lots of ways. It's weird because there's three charges. It's weird because the force carrying particles feel their own force. And in fact, just like there are three kinds of quirks because of the colors, there are actually eight different kinds of gluon. Eight What do you mean eight? I thought there were only there was only one with three colors to it. Well, the corks have one color, but the gluons each carry two colors. What I guess is they have to match to the two quirks or what exactly right? And so for example, a gluon can be like red anti blue, or it can be green anti red or whatever. There's lots of different combinations, and so it turns out there eight individual different kinds of gluons. We have one photon for electromagnetism, but there are eight different gluons because of all the colors. And it makes you realize like there's a lot going on inside these particles that we can't see or even really imagined that most of the particles out there are actually colored particles, because we think of them as like one cork and one gluon, but really there's eight gluons and three of each. Kind of quirk. They sound strange enough to be their own like matter particle, but they're not a matter part they're not matter particles. But if you could make a glue ball that would be sort of like a kind of matter just made out of forces. That would be really strange. We've never seen that before, totally fascinating. If we could create it and study it, well, it sounds like maybe you guys did pick a pretty good name, because you know, gluants are so sticky they even stick to themselves exactly. They're like that clinger up that's not supposed to stick to yourself, but it does, all right. So and that's so that's a discovery. Nine. That's when we discovered gluont and that's how we knew how the nucleus of your atoms stayed together. Yeah, and that really powered the generation of discoveries that came next. Like in the eighties, we discovered the W and the z bosons and with a lot of confidence that they existed because we understood that a lot of these forces really were mediated by these force particles. And so it was a pretty exciting moment for the field. And it gives everyone who has a rich company hope that they can maybe build the next great particle collider. You should always put your bid in because you never know when the government will come back and say, yes, actually we want you to do this. All right, Well, that was pretty interesting, pretty dramatic, and very fundamental. You know, without this particle, we none of us would be here. I mean, the universe could go on, but we, like as beings held together, wouldn't be here to talk about it. Yeah, me and you, we have lots of luans inside us. It's sort of weird to be searching for a particle that we know is an inherent part of who we are and how we operate. But sometimes it takes a while to reveal its shy nature. But yeah, you and me and stars and everything around us has gluons inside of it. All right. Well, we hope you enjoyed that. Thanks for joining us, See you next time. Thanks for listening, and remember that Daniel and Jorge explained. The Universe is a production of I Heart Radio. 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