Speaker 1: Hey, Daniel, what's it like to discover a new particle
Speaker 1: of nature?
Speaker 2: You know, it's a lot less dramatic than you might expect.
Speaker 1: Oh really, there's no Eureka moment or some grand reveal.
Speaker 2: It's usually a lot more gradual than like dropping a
Speaker 2: velvet curtain or something. It's more like watching water drain
Speaker 2: out of the tub to reveal the toys at the bottom.
Speaker 1: You make it sound so exciting.
Speaker 2: I'm not sure how Steven Spielberg is going to portray
Speaker 2: that in a moment of my life. But you know,
Speaker 2: it gets even worse. Sometimes we don't even agree about
Speaker 2: whether or not we did discover something.
Speaker 1: Sometimes it's like it is that a toy at the
Speaker 1: bottom of the tub or is that something else? But
Speaker 1: what do you mean? Like, sometimes you discover something and
Speaker 1: some people are like, no, I don't think that's the thing.
Speaker 2: Yeah, we can basically disagree about anything in particle.
Speaker 1: Physics, even about whether you disagree or not.
Speaker 2: That's the one thing we can agree on.
Speaker 1: I am more handmade cartoonists and the creator of PhD comics.
Speaker 2: Hi, I'm Daniel. I'm a particle physicist and a professor
Speaker 2: at UC Irvine. And when I got into this field.
Speaker 2: I really did think there were going to be more
Speaker 2: discoveries to be had.
Speaker 1: Well, isn't it kind of up to you to make
Speaker 1: those discoveries? Why are you sound like you're complaining.
Speaker 2: It's partially up to me, but it's also up to nature.
Speaker 2: You know, when you go out and do research, you
Speaker 2: never know what you're going to find, and you never
Speaker 2: know what's out there for you too fine. It's like
Speaker 2: the folks who were hoping to discover life on Mars.
Speaker 2: They worked hard, they did their job, they built their rovers.
Speaker 2: There just wasn't life on Mars for them, too fine.
Speaker 2: And it's sort of the same way in particle physics.
Speaker 2: It's been a little bit dry for us thirsty folks.
Speaker 1: Mmmm. Are you going to ask for your money back
Speaker 1: from nature or your career back?
Speaker 2: I'm hoping the government doesn't ask for their ten billion
Speaker 2: dollars back. We'll have to auction off bits of the LHC.
Speaker 1: Yeah, yeah, there you go, offer it the souvenirs like
Speaker 1: memorial you know, special keepsakes. You get a little bit
Speaker 1: of this super conducting magnet.
Speaker 2: The world's nerdiest Etsy shop bits of the LHC. There
Speaker 2: are actually people who've done salvage on the super Conducting
Speaker 2: super Collider in Texas. A lot of the equipment there
Speaker 2: was just abandoned and people have grabbed some of it
Speaker 2: and saved it as keepsakes.
Speaker 1: A bit of people would buy a piece of the LC, right,
Speaker 1: wouldn't they. It's the thing that discovered the Higgs boson.
Speaker 1: That's kind of a big deal. Like you might actually find,
Speaker 1: you know, the little sensor pad that actually caught the
Speaker 1: first Higgs. Let's let's get in on that. Let's kill
Speaker 1: it on the Daniel and Jorge online shop.
Speaker 2: It can be like pieces of the true Cross. We
Speaker 2: can sell more of them than actually existed.
Speaker 1: Yeah, there you go. Amazingly. It's magical as well. It
Speaker 1: multiplies the LHC. But what do you think you would
Speaker 1: have done if you hadn't been a particle physics someone
Speaker 1: who explores life on Mars.
Speaker 2: Well, I actually did two degrees as an undergraduate physics
Speaker 2: and computer science, and I also applied to grad school
Speaker 2: and computer science. I was going to do artificial intelligence
Speaker 2: and machine learning, so that was sort of my other life.
Speaker 1: Wow, man, I'm sorry to say, but you totally missed
Speaker 1: that boat. He would probably a billionaire, I guess, But
Speaker 1: then we wouldn't have this podcast, or we would have
Speaker 1: a super popular podcast about Ki.
Speaker 2: Yeah, but then I'd be responsible for people's self driving
Speaker 2: cars crashing, and I don't know if I could handle
Speaker 2: that kind of responsibility.
Speaker 1: Well, it's not your fault, it's the car's fault. That's
Speaker 1: why you give them sentience to absolve yourself of any responsibility.
Speaker 2: Right right, Just like we're not responsible for whether our
Speaker 2: kids grew up to be serial killers or not.
Speaker 1: Exactly right, Wait, what what's going on with your kid there?
Speaker 1: Maybe it's your kids are already making a head.
Speaker 2: I do wonder about those serial killers and whether their
Speaker 2: parents feel responsible. Yeah.
Speaker 1: I thought you're gonna say I do wonder about my son.
Speaker 1: I was like, whoa, But anyways, Welcome to our podcast,
Speaker 1: Daniel and Jorge Explain the Universe, a production of iHeartRadio.
Speaker 2: We are not responsible for the incredible, crazy, bonkers, beautiful
Speaker 2: universe out there, but we do feel responsible for helping
Speaker 2: you to understand it. We dig in deep into what's
Speaker 2: going on out there in the universe, and we try
Speaker 2: to process it. We chop it up, and we serve
Speaker 2: it all up to you, hoping to educate and entertain
Speaker 2: you at the same time.
Speaker 1: It's right, welcome to our two hundred and ninetieth course
Speaker 1: meal here on the amazing food for thought that is
Speaker 1: the universe, because it is pretty awesome. And to be honest,
Speaker 1: I do feel a little bit responsible to that.
Speaker 2: You know, you were reaching for a big number there,
Speaker 2: but I think the number of episodes is more like
Speaker 2: four hundred and eighty or something.
Speaker 1: By now, oh my goodness, it's like the banquet that
Speaker 1: never ends. Like maybe it's more like a buffet where
Speaker 1: we take a bring on this food little by little.
Speaker 2: That's right. Every course has to be super tiny for
Speaker 2: you to be able to finish course number five hundred.
Speaker 2: Eventually we'll get to dessert.
Speaker 1: Now, do we reveal each course of this meal or
Speaker 1: do we just let the work and let the food
Speaker 1: say that good.
Speaker 2: Bottom Every episode is letting the water drain and hoping
Speaker 2: that there's some understanding to be revealed.
Speaker 1: That is how we record it. We just sit down,
Speaker 1: you start talking, and we hope that some knowledge comes
Speaker 1: out of it.
Speaker 2: We hope there's gold and not a floating turret in
Speaker 2: that Baptob.
Speaker 1: Oh Man, can you say that on our podcast? I
Speaker 1: guess you just did.
Speaker 2: Let's see if it guests passed the sensors.
Speaker 1: Which are you?
Speaker 2: Yes?
Speaker 1: Crazy? Well, speaking of pushing things out, let's dive into
Speaker 1: the topic of the episode here today. So it is,
Speaker 1: as we said, an amazing and incredible universe full of
Speaker 1: amazing and lots of little things, lots of little things
Speaker 1: out there that keep the universe together.
Speaker 2: And over the last fifty years or so, we have
Speaker 2: pulled apart matter to reveal its basic constituents. We know
Speaker 2: that you are made of molecules, which are made of atoms,
Speaker 2: which are built out of electrons, protons and neutrons. We've
Speaker 2: even pulled the protons and neutrons apart to discover that
Speaker 2: they are made of quarks. We have found the quarks
Speaker 2: out there and other versions of the electron. We have
Speaker 2: this wonderful periodic table of the fundamental particles that we
Speaker 2: describe using the standard model, which paints a very nice
Speaker 2: picture of what's going on microscopically inside of me and
Speaker 2: you and at the hearts of stars.
Speaker 1: That's right. We've come a long way from thinking that
Speaker 1: the universe and everything in it is made out of
Speaker 1: four things like earth, wind and fire and water, to
Speaker 1: basically chop up the entire matter of the universe into
Speaker 1: smaller and smaller bits until we get to basically bits
Speaker 1: that you can't chop up anymore.
Speaker 2: And it's been a really fascinating ride, not just discovering
Speaker 2: what matter is inside of us, which is mostly the upcork,
Speaker 2: the down cork, and the electron because you can assemble
Speaker 2: the upcork and the down cork into protons and neutrons
Speaker 2: and put the electrons around them to make atoms, but
Speaker 2: also to discover what else the universe can do. The
Speaker 2: things that we are made out of are the stable bits,
Speaker 2: the things that last forever and can get mixed together
Speaker 2: to make more interesting chemistry. But there are also other
Speaker 2: weird things that the universe can do, things that don't
Speaker 2: last for very long, so they take special conditions to
Speaker 2: reveal them.
Speaker 1: Yeah, the universe has its own buffet of things that
Speaker 1: it can make out there, and not just the things
Speaker 1: that we can eat that make up who we are.
Speaker 1: There's lots of other things out there in the universe,
Speaker 1: and little by little we've put together a pretty complete
Speaker 1: picture of what's out there or what can be out
Speaker 1: there in the universe.
Speaker 2: We have a whole fun series of podcast episodes about
Speaker 2: the discoveries of these particles, how the top quark was discovered,
Speaker 2: how the gluon was discovered, how the photon was discovered.
Speaker 2: All these pieces of the Standard Model, and we put
Speaker 2: them together into a picture and ask like, does it work?
Speaker 2: Are there any missing bits? And that's how some of
Speaker 2: those discoveries were made. We like assemble them together and
Speaker 2: we notice patterns. We say, huh, there's a hole here.
Speaker 2: I wonder if there's another particle missing. The way you
Speaker 2: can look at the periodic table and say, where's element
Speaker 2: thirty four? Why is there a thirty three and a
Speaker 2: thirty five? There should be one in the middle. In
Speaker 2: the same way, we filled in a lot of the
Speaker 2: gaps in the Standard model just by looking for patterns
Speaker 2: and hoping for simplicity and mathematical beauty and symmetry. And
Speaker 2: this has been a very useful guiding principle in helping
Speaker 2: us to discover things. That's how, for example, we knew
Speaker 2: to look for the Higgs boson.
Speaker 1: Yeah, we have a periodic table for the fundamental particles
Speaker 1: of nature. It's called the Standard Model, and it does
Speaker 1: kind of look like the periodic table right, it's a
Speaker 1: grid and you got little spas for all the different
Speaker 1: particles like quarks and electrons and neutrinos, and they're sort
Speaker 1: of in order. Also, it sort of looks like a
Speaker 1: periodic table. Yeah, because there are patterns there.
Speaker 2: Like you can take the electron, the muon and the
Speaker 2: tow and you notice that they're increasing in mass. The
Speaker 2: muon is heavier than the electron, the tow is heavier
Speaker 2: than the muon, And the same pattern exists in the upcork,
Speaker 2: the charm cork, and the top cork. The charm in
Speaker 2: the top is just like heavier versions of the upcark.
Speaker 2: So we notice these patterns. We see these things in
Speaker 2: the table, and so we arrange our table in that
Speaker 2: way to bring out those patterns to like inspire us
Speaker 2: to think about what could be explaining them. And so
Speaker 2: there's sort of two directions to think about there. One
Speaker 2: is like, well, what's inside these particles? Is there a
Speaker 2: deeper layer of reality? And so that's definitely something we're exploring.
Speaker 2: But sometimes we look in the other direction and we say, well,
Speaker 2: what are the consequences of these particles? What can these
Speaker 2: particles do? If this is real? If those particles are
Speaker 2: actually out there, what do we expect to see in
Speaker 2: our colliders? What can these things come together to make?
Speaker 2: And that's another very fruitful way to test our understanding
Speaker 2: of what's going on in the particle world.
Speaker 1: Yeah, so we have a grit called the standard model,
Speaker 1: and it's called the standard model because they think it's
Speaker 1: standard and it's a model. But when did they come
Speaker 1: up with this name? I wonder? And how did they
Speaker 1: know it is going to be standard for the entire universe?
Speaker 2: I knew you were going to have concerns about the names.
Speaker 2: The standard model itself comes out of the seventies when
Speaker 2: people realized that there were connections between the weak force
Speaker 2: and electromagnetism and that explained a lot of what we
Speaker 2: were seeing happening with the electron and the muons, and
Speaker 2: so they put this together into a model of leptons,
Speaker 2: which then became a standard model of leptons, and so
Speaker 2: it was sort of adopted around then. And the standard
Speaker 2: that sense, just sort of means like consensus. There are
Speaker 2: lots of different views of what was happening in particles,
Speaker 2: and this just sort of emerged as the most popular model,
Speaker 2: the one that people thought was the most parsimonious and
Speaker 2: explained what we were seeing, and it also predicted the
Speaker 2: Higgs boson, and so when we saw the Higgs boson
Speaker 2: in nature, people were like, Yep, that's it.
Speaker 1: The standard model is the way to go interesting. It's
Speaker 1: it's like the thing that all physicists can agree on, kind.
Speaker 2: Of mostly that can happen. It can happen, although of
Speaker 2: course there are lots of disagreements about what is the
Speaker 2: standard model. Some people, for example, say that the standard
Speaker 2: model requires neutrinos to have no mass, but we know
Speaker 2: neutrinos do have mass, and some people say, no, no,
Speaker 2: we can have massive neutrinos in this standard model. And
Speaker 2: so there's a lot of disagreement about exactly what constitutes
Speaker 2: the standard model. Probably was a bad idea to call
Speaker 2: it standard in the first place.
Speaker 1: Ye should have called it a model. But it's interesting because,
Speaker 1: like what you said, is that it's not just a
Speaker 1: sort of like a listing of all the fundamental particles,
Speaker 1: kind of like the periodic table is. It's also kind
Speaker 1: of about the rules that govern what happens between the
Speaker 1: things in the table, and a lot of it is
Speaker 1: also just the math of how all of these things
Speaker 1: work just like the periodic table. It's not just the
Speaker 1: listing of element. It's also like a model of how
Speaker 1: the electron you know, orbits around the nucleus, and what
Speaker 1: happens when two atoms get close together, how do they
Speaker 1: share electrons and things like that. The Standard model also
Speaker 1: there's a lot more to it than just the listening
Speaker 1: to particles.
Speaker 2: Yeah, exactly. We often focus on the matter particles like
Speaker 2: the upcork, the down cork, and the electron, but also
Speaker 2: in the standard model we have the force particles, the photon,
Speaker 2: the W, the z, the gluon, and as you say,
Speaker 2: these play a very important role in building things. Without
Speaker 2: the forces, you couldn't put the up, the down, the
Speaker 2: electron together to make ice cream or kittens or lava
Speaker 2: or hamsters or anything. Right. Really, the forces are required.
Speaker 2: And I often feel that way when somebody says, oh,
Speaker 2: the atom is mostly empty space, because they imagine the
Speaker 2: tiny little nucleus or the tiny electrons really are apart
Speaker 2: from each other in mostly empty space. But the truth
Speaker 2: is is not really empty. It's filled with fields, force
Speaker 2: fields and virtual particles tying them together. It's a swarm
Speaker 2: of oscillating energy and so you're right, we need to
Speaker 2: think not just about the little bits of matter, but
Speaker 2: also the forces that tie them together and how that
Speaker 2: works and what those can do. And that's something we
Speaker 2: are still exploring, still trying to figure out.
Speaker 1: Yeah, I think that's something that maybe a lot of
Speaker 1: people don't know. And I wonder if that's because, you know,
Speaker 1: when they discovered the Higgs Boson, it was kind of
Speaker 1: a big deal. At least that's what the headline said.
Speaker 1: That it was a big deal because it completed this
Speaker 1: standard model. The Higgs Boson sort of like was the
Speaker 1: cherry on top where it put the last little lego
Speaker 1: piece or jigsaw puzzle piece on the standard model and
Speaker 1: then you guys were done, right, you could all retire
Speaker 1: and become hey experts or something.
Speaker 2: We've been napping in our offices ever since. Yes, confirmed,
Speaker 2: Oh okay, that's good to know. Then I do want
Speaker 2: my money back, Please wait for the check. Yeah, and
Speaker 2: so it was sort of a big deal because they
Speaker 2: said they'd the standard model. But you're telling me maybe
Speaker 2: that it's not complete. Maybe it's something that people disagree about.
Speaker 1: Still.
Speaker 2: Yeah, well, it's not like the New York Times were
Speaker 2: liars or anything. When they said it completed the standard model.
Speaker 2: That's true from one perspective, from the perspective of like
Speaker 2: looking at the periodic table of fundamental particles and saying,
Speaker 2: do we have all the pieces necessary to make a
Speaker 2: complete theory? You know, are there any obvious holes? And
Speaker 2: so we had found the top core, we had found
Speaker 2: the Towe leapt on, and the last like definitely predicted
Speaker 2: missing fundamental piece, little jigsaw piece, as you say, was
Speaker 2: the Higgs boson. It was definitely missing, and we definitely
Speaker 2: needed to find it if the Standard Model was real,
Speaker 2: if it was a description of nature. And now we
Speaker 2: found it, and it clicks in, and we do have
Speaker 2: what we consider a fairly complete theory. Of course, it
Speaker 2: doesn't describe gravity or dark matter or all sorts of
Speaker 2: other crazy stuff. And we just did an episode about
Speaker 2: like the problems of the Standard Model. But you know,
Speaker 2: from one perspective, it really did complete it. It was
Speaker 2: like an obvious hole that needed to be filled. There
Speaker 2: are no more open holes in that sense, like fundamental
Speaker 2: particle that the Standard Model predicts that we haven't found yet.
Speaker 2: From another perspective, there's lots of things left to study,
Speaker 2: you know, like how these particles dance together to make
Speaker 2: new things. That's not how these particles come together to
Speaker 2: make more interesting, complicated things. That's not something we fully
Speaker 2: yet understand. And there are lots of predictions there that
Speaker 2: have not yet been verified.
Speaker 1: Yeah, I feel like you're pulling off a nice marketing
Speaker 1: trick here, where you're saying, like, what we did was awesome,
Speaker 1: and where's all that money? And we finished it, but
Speaker 1: there are still things less to do to keep giving
Speaker 1: us money.
Speaker 2: That is the summer of every science grant proposal ever, basically,
Speaker 2: not just in particle physics.
Speaker 1: I see, it's just a reflex for you know.
Speaker 2: Well, you know that's the story. It's like, look, we
Speaker 2: did awesome stuff with the money you gave us. We
Speaker 2: will do more awesome stuff with the future money we
Speaker 2: hope you keep giving us. That's the way it works.
Speaker 1: Well, like you said, there's still more to discover, I guess,
Speaker 1: or to check off about all of the things that
Speaker 1: the standard model predicts. And so one of those predictions
Speaker 1: is kind of an interesting sounding object.
Speaker 2: It is a super fun prediction of the standard model,
Speaker 2: and one people have been hunting for for a long
Speaker 2: time and disagree about whether it's possible to find it,
Speaker 2: or whether we already have.
Speaker 1: It's a sticky subject. Well, to the end of the episode,
Speaker 1: we'll be tackling the question what is a glue ball?
Speaker 1: That sounds like something that happens when you're playing with glue.
Speaker 2: It does sound like a very everyday object, but it's
Speaker 2: also a very esoteric prediction by the standard model that's
Speaker 2: been surprisingly difficult to verify.
Speaker 1: Actually, it does kind of sound like something that might
Speaker 1: be useful, like a ball made out of glue that
Speaker 1: then you can use to stick things together.
Speaker 2: It sounds like the thing you could keep next to
Speaker 2: your rubber band ball. Yeah right, let's start selling those.
Speaker 2: You can get those on our online store now, balls.
Speaker 1: Of glue, oh man.
Speaker 2: With little bits of the LEDC stuck inside.
Speaker 1: Yeah, there you go. Or it's sticking together bits of
Speaker 1: the lac.
Speaker 2: Even better, How does the lac work it's held together
Speaker 2: with spit in glue balls.
Speaker 1: Well that might be actually true, right.
Speaker 2: That might be actually trueious.
Speaker 1: I mean, I'm sure a lot of physicists were drilling
Speaker 1: when they were putting it together. That's where all this
Speaker 1: bit comes from. Well, anyways, as usual, we were wondering
Speaker 1: how many people out there had heard of a glue
Speaker 1: ball or have any idea what it can be.
Speaker 2: So thank you very much to everybody who answers these
Speaker 2: random questions. It's super helpful to get a sense for
Speaker 2: what people already know and what they think about these ideas.
Speaker 1: So think about it for a second. What do you
Speaker 1: think a glue ball can be? Here's what people had
Speaker 1: to say.
Speaker 3: There must be some silly ball made by kids to
Speaker 3: play with during lunch of races. Yeah, I'm kidding. So
Speaker 3: glue ball is a very relatively new concept. It is
Speaker 3: basically combination of glue on particles without anyone and squawk.
Speaker 1: A glue ball sounds like something to do with glue ons.
Speaker 1: That's maybe like a ball of glue on, just a
Speaker 1: bunch of them just interacting and stuff, just hanging out.
Speaker 4: A glue ball. Yeah, I have no clue what that
Speaker 4: could possibly be. The only thing that comes to mind
Speaker 4: maybe is it might have something to do with glue ones.
Speaker 4: But other than that, I can't even begin to guess.
Speaker 1: Uh, probably something my cat pukes after she ates some clue.
Speaker 1: I don't know. All right, sounds like we're not the
Speaker 1: only ones who thought it's a kit's toy, or that
Speaker 1: it involves spit somehow from cats.
Speaker 2: I feel sorry for that guy's cat. I mean, who
Speaker 2: lets their cat eat glue? Seriously?
Speaker 1: I don't know. But are you responsible if your cat
Speaker 1: eats glue? Or is that the cat's faut.
Speaker 2: I don't know, But if your cat turns out to
Speaker 2: be a serial killer, maybe you are responsible.
Speaker 1: Well, at least the cat wouldn't get far, very far.
Speaker 1: Just get stick to everything. The sticky glue ball, serial
Speaker 1: killer sticky cat? Did you mean?
Speaker 2: But I think a lot of these folks really got
Speaker 2: the idea from the name, right, a ball of gluons.
Speaker 2: Maybe this is actually a thing in particle physics that
Speaker 2: has gasp an appropriate name.
Speaker 1: Well, I don't know, it's if it is a ball
Speaker 1: or not. I bet it's more like a teohedron or something.
Speaker 2: I see you're gonna withhold judgment, all right, let's dig in.
Speaker 1: Yeah, let's see what happens here. We'll step us through this, Daniel,
Speaker 1: What is glue ball?
Speaker 2: So a glue ball is a predicted particle that would
Speaker 2: be made entirely of gluons, No quarks, no electrons, no
Speaker 2: other matter particles at all, just gluons.
Speaker 1: M Okay, So it's a theoretical or a predicted object
Speaker 1: that can happen out in nature, and you would get
Speaker 1: it by putting together gluons. Now what are gluons?
Speaker 2: Right? So this is a predicted particle of the standard model.
Speaker 2: It says gluons should be able to come together and
Speaker 2: make this weird thing we call a glue ball. So
Speaker 2: to understand that, you have to understand what is a gluon? Right. So,
Speaker 2: as we said, each of the forces that are out there,
Speaker 2: the fundamental forces that we know about, get mediated in
Speaker 2: terms of fields, but you can also think about them
Speaker 2: in terms of particles. Like what happens when two electrons
Speaker 2: talk to each other, But they're doing it as they're
Speaker 2: pushing on each other, and they push on each other
Speaker 2: using their electric fields. But you can also think about
Speaker 2: those fields as like a swarm of virtual photons. So
Speaker 2: one way to think about how two electrons talk to
Speaker 2: each other is that they bounce photons back and forth.
Speaker 2: They're using photons to send messages to each other. So
Speaker 2: every force that's out there you can think about in
Speaker 2: terms of a field or the particle for that field.
Speaker 2: So for electromagnetism, we have the photon, which is the
Speaker 2: particle which carries the electromagnetic force. And then for the
Speaker 2: strong force, we also have fields, and those fields are
Speaker 2: gluon fields, and so the gluon is the particle that
Speaker 2: carries the strong force. So, for example, how do you
Speaker 2: make a proton. We make it out of upquarks and
Speaker 2: down quarks. How do you tie the up quarks and
Speaker 2: down quarks to gather into a proton? You use gluons.
Speaker 2: So inside the proton is not just upquarks and down quarks.
Speaker 2: There's a whole mess of gluons in they're holding it together.
Speaker 1: Yeah, we talked a little bit about this in our
Speaker 1: last podcast, about how photon are the particles that kind
Speaker 1: of mediate, like you said, the electromagnetic force, like every
Speaker 1: time an electron is repelled by another electron, or an
Speaker 1: electron is attracted to another particle like a proton, there's
Speaker 1: an exchange of photons. But we also kind of talked
Speaker 1: about how these are not like real, real particles, like
Speaker 1: they don't actually exchange these particles. It's more sort of
Speaker 1: like in the sense of like quantum virtual particles.
Speaker 2: Right, Yeah, that's exactly right. I find it more intuitive
Speaker 2: to think about these things in terms of fields, like
Speaker 2: the electron has a field and it's using that field
Speaker 2: to push on another electron. But if you don't like
Speaker 2: the idea of fields, you can also think about these
Speaker 2: things in terms of virtual particles, and you just replace
Speaker 2: the field with an infinite number of virtual particles that
Speaker 2: are filling space. Mathematically, it's really the same thing. And
Speaker 2: those are the virtual particles, which you're not like real particles.
Speaker 2: But these fields are also capable of having real particles,
Speaker 2: Like what is a real photon? A photon that leaves
Speaker 2: the Sun and hits your eyeball. That's a ripple in
Speaker 2: the electromagnetic field. And in the same way, a gluon,
Speaker 2: like a real gluon, is a ripple in the gluon field.
Speaker 2: So there can be virtual gluons exchanged between particles inside
Speaker 2: a proton, for example, and they're also real gluons that
Speaker 2: can like fly through space.
Speaker 1: Okay, so there are real gluons and virtual gluons, and
Speaker 1: so like you're saying, these are the particles that mediate
Speaker 1: or that transmit the strong force, which is what keeps
Speaker 1: quarts together to make protons and neutrons, And those are
Speaker 1: the nuclei and all of the atoms in your body.
Speaker 1: But maybe let's paint the picture of how these gluons
Speaker 1: actually keep things together, and then let's talk about what
Speaker 1: happens when you try to glue two gluons together. So
Speaker 1: let's get into that, but first let's take a quick break.
Speaker 1: All Right, we're talking about glue balls, which is not
Speaker 1: a toy, but it is a pretty good name for
Speaker 1: a toy.
Speaker 2: Yeah, that's right. Gluons sound ridiculous, but they are a
Speaker 2: real thing in particle physics, and we use them in
Speaker 2: our calculations and exist in nature sticking your quarks together
Speaker 2: to make you okay.
Speaker 1: So we talked about how gluons are the particles that
Speaker 1: transmit the strong force, and so you said they sort
Speaker 1: of come up when, for example, a quark is attracted
Speaker 1: to another quark. So maybe paint is a picture. I'm
Speaker 1: a quark and I have another quark here next to me,
Speaker 1: and I feel the strong force between us. What does
Speaker 1: that mean? Does that mean I'm like throwing gluons at
Speaker 1: each other, or does it mean that there are virtual
Speaker 1: gluons popping up in the space between us, or what
Speaker 1: does that mean?
Speaker 2: Yeah, the way you should think about it is that
Speaker 2: quarks have a field. That field is just like an
Speaker 2: electric field from an electron. But electrons have a electric charges,
Speaker 2: which is what makes the electric field, and quarks have
Speaker 2: a different kind of charge. They have a charge for
Speaker 2: the strong force, which is a different force from electromagnetism,
Speaker 2: and that kind of charge we call a color charge
Speaker 2: because it has three different varieties red, green, and blue.
Speaker 2: So electromagnetism has like plus and minus charges, the color
Speaker 2: charge is much different and very weird as three versions
Speaker 2: of it. Quark can be like blue or green or red,
Speaker 2: and so it can have a field, a color field,
Speaker 2: and that color field pulls or pushes on other things
Speaker 2: that have color charges to them. So, for example, that
Speaker 2: quark inside your proton has a color field, and that
Speaker 2: color field is applying a force to the other quarks
Speaker 2: inside the proton. And now you can always think about
Speaker 2: these fields in terms of virtual particles, and so the
Speaker 2: virtual particle for this field is a glue on. So
Speaker 2: one way to think about it is these quarks are
Speaker 2: bound together because of their color field that's putting forces
Speaker 2: on the other quarks, or that they're exchanging virtual gluons
Speaker 2: constantly to tie themselves together into a proton.
Speaker 1: And you sort of need this idea of particles that
Speaker 1: transmit the force because these forces are not, as far
Speaker 1: as we can see, instantaneous, like from a quark here
Speaker 1: and you're a quark over there. I don't exert a
Speaker 1: force and you kind of immediately or magically right like
Speaker 1: there's something that has to somehow go from here to there.
Speaker 2: No information can move instantaneously in the universe, and that's why.
Speaker 2: For example, if you take an electron, it has a
Speaker 2: static electric field, but then if you wiggle that electron,
Speaker 2: the whole field doesn't move all at once. If that
Speaker 2: field extends from here to your neighbor's house. But if
Speaker 2: you wiggle the electron, your neighbor can't tell that you
Speaker 2: wiggled it instantly. They have to wait for that wiggle
Speaker 2: to move through the field to get to him. And
Speaker 2: that's what we think of as a ripple in that field,
Speaker 2: which you can interpret as a particle. In fact, that's
Speaker 2: how you make photons. You take electrons and you wiggle them.
Speaker 2: That's an he is and so you can interpret these
Speaker 2: ripples in the field sometimes in terms of real particles
Speaker 2: if they have certain properties special ripples or if there
Speaker 2: are other kinds of ripples in the field, then we
Speaker 2: just call them virtual particles.
Speaker 1: Okay, so now let's paint the picture. I have a
Speaker 1: quark right here in front of you, and it's a
Speaker 1: red cork, and you right next to me have a
Speaker 1: green cork, and so, which means that two quarks are
Speaker 1: sort of attracting each other, right, I'm pulling on each
Speaker 1: other to smush them together through the strong force. But
Speaker 1: they're not moving yet. What's happening? Are there like virtual
Speaker 1: gluons popping up in between the two? Is my quark
Speaker 1: sending gluons to your quark? How would you describe it?
Speaker 1: Or nothing's happening until one of them moves.
Speaker 2: Remember that these are quantum particles, so you can't really
Speaker 2: think of them as having like a specific location and velocity.
Speaker 2: The same way you can't really think about the electron
Speaker 2: as having a specific location and velocity as it moves
Speaker 2: around the nucleus. Instead, you can think of it as
Speaker 2: having like a probability distribution of various possible locations around
Speaker 2: the nuclear Because it's trapped in a little well, the
Speaker 2: nucleus creates an electromagnetic potential, which traps the electron inside
Speaker 2: of it, and the electron is somewhere in that well,
Speaker 2: but we don't know exactly where. So in the same way,
Speaker 2: these quarks all create color potential, a strong force potential
Speaker 2: which traps the other quarks with them inside this potential.
Speaker 2: So where is any individual quark well, it's not determined
Speaker 2: just as a probability distribution, but it's all balanced and solved,
Speaker 2: and all the quarks have a happy wave function to
Speaker 2: be on top of each other inside this little potential
Speaker 2: well that they all create. So it's like a little
Speaker 2: bound state of these quantum functions.
Speaker 1: I guess it's sort of like you know, like you're saying,
Speaker 1: the quark that I have here in my red QRK
Speaker 1: isn't really like a billiard ball. It's more like a
Speaker 1: fuzzy cloud here that I'm holding. And then your quark
Speaker 1: is also not a billiard ball. It's another fuzzy cloud.
Speaker 1: And so when I sort of bring them together, the
Speaker 1: two clouds cand of merge or smoosh together into one,
Speaker 1: sort of like a system made out of two particles.
Speaker 1: That's kind of what you're saying, right, It's like it's
Speaker 1: more like the two quantum functions or wave functions merge
Speaker 1: together to make one that maybe has some sort of
Speaker 1: potential to stay together.
Speaker 2: Remember that quantum mechanics tells us that the universe is random,
Speaker 2: but it's not totally random. It's still deterministic in some way.
Speaker 2: Like old Newtonian classical physics told us that everything was
Speaker 2: like a billiard ball, and if you bounce things the
Speaker 2: same way twice, the same thing would happen. Everything was deterministic.
Speaker 2: Quantum mechanics says, well, we're deterministic, but only about the probabilities.
Speaker 2: Quantum mechanics says, I will predict exactly what the probability
Speaker 2: of various outcomes is. I won't to tell you which
Speaker 2: outcome is going to happen, but i'll tell you the
Speaker 2: various probabilities. So here quantum mechanics applies to these little particles,
Speaker 2: and it says, well, your red cork has a higher
Speaker 2: chance of being over here and the smaller chance of
Speaker 2: being over there, and they have to satisfy all the
Speaker 2: mathematics of the equations. And so you can solve these
Speaker 2: equations and figure out where the red cork is likely
Speaker 2: to be, given that there's a blue cork nearby and
Speaker 2: a green cork nearby side the proton. The really cool
Speaker 2: thing about the strong force is these weird charges. Like
Speaker 2: the atom is neutral because you have a positively charged
Speaker 2: nucleus and a negatively charged electron. Plus one and minus
Speaker 2: one makes zero. Right, Well, the proton has no color
Speaker 2: charge because inside of it it has one of each
Speaker 2: of the charges. It has a red, a green, and
Speaker 2: a blue, and together those add up to make no
Speaker 2: color or white as we call it, in the same
Speaker 2: way that like having one of each of the electromagnetic
Speaker 2: charges plus and minus add up to zero electromagnetic charge.
Speaker 1: And so that's how the quarks add up. But then
Speaker 1: where do the gluons come in?
Speaker 2: So the gluons are super duper weird and much more
Speaker 2: complicated than in electromagnetism. Electromagnetism you have two charges and
Speaker 2: you just have the single photon which transmits it. The
Speaker 2: photon itself is not charged, right, The photon is a
Speaker 2: neutral object, which is going to be important because photons,
Speaker 2: they don't like, bounce off of each other. They pass
Speaker 2: right through each other for the most part. Check out
Speaker 2: our whole podcast episode about lightsabers and photons bouncing off
Speaker 2: each other. But gluons are different. Gluons are charged in color.
Speaker 2: In fact, gluons have two colors. So for example, like
Speaker 2: a quark has one color like red or blue or green,
Speaker 2: a gluon has two colors simultaneously. It can be like
Speaker 2: red and anti blue or blue and anti green.
Speaker 1: Does that depend on sort of like what the two
Speaker 1: quarks are that are interacting? Like if I have a
Speaker 1: red cork and you have a green cork, is it
Speaker 1: that they can only exchange red green or red anti
Speaker 1: green bluons?
Speaker 2: Yeah, it's just like that. If you have, for example,
Speaker 2: a blue cork and a green cork, a blue cork
Speaker 2: can emit a blue anti green gluon and then it
Speaker 2: becomes green. Its blueness has gone into the gluon and
Speaker 2: it becomes green because they also gave that gluon anti green.
Speaker 2: Then the green cork absorbs the blue anti green gluon
Speaker 2: and it becomes a blue cork. So like a blue
Speaker 2: cork and a green cork, or can swap colors by
Speaker 2: exchanging a gluon.
Speaker 1: And so this swapping happens when they move relative to
Speaker 1: each other. Is it always happening at all times? Like
Speaker 1: with these virtual particles? What exactly is going on?
Speaker 2: Well, like everything else quanta mechanical, nothing is definitive. So
Speaker 2: you have your quarks inside the proton, and none of
Speaker 2: them are like actually red, or actually green or actually blue.
Speaker 2: They all have a probability to have one of those
Speaker 2: colors simultaneously, And if you really needed to know, you
Speaker 2: would like send a really high energy particle inside the
Speaker 2: proton to break it up to figure out what the
Speaker 2: color was, and then the universe would roll the die
Speaker 2: and say, Okay, this one happened to be green at
Speaker 2: that moment, or this one happened to be red at
Speaker 2: that moment. But just right now, inside your proton, as
Speaker 2: everything is jiggling, each of your quarks has a simultaneous
Speaker 2: probability for each of these colors. But the fact that
Speaker 2: the gluon has to have these colors itself makes it
Speaker 2: really complicated. So two gluons can also interact with each
Speaker 2: other the way two photons really cannot. Two gluons can
Speaker 2: talk to each other directly.
Speaker 1: Okay, and you're talking about the real gluons or the
Speaker 1: virtual gluons.
Speaker 2: Both all kinds of gluons. These fields all bounce off
Speaker 2: each other and interact with each other and make more gluons.
Speaker 2: Two gluons can come together to make two more gluons.
Speaker 2: It gets really complicated really fast, because everybody's talking to
Speaker 2: everybody else.
Speaker 1: All right. So then gluons are particles, just like an
Speaker 1: electron is or a photon is that they have their
Speaker 1: own field in the universe. I'm trying to put the
Speaker 1: picture here together. And what they do is they sort
Speaker 1: of fly or exist between different quarks that have the
Speaker 1: color charge, and that's sort of how the strong force
Speaker 1: comes about. And they have different flavors, different colors. And
Speaker 1: sometimes these gluons can interact with each other, and I
Speaker 1: imagine they can also stick to each other, which is
Speaker 1: maybe where a glue ball comes in exactly.
Speaker 2: Because they can talk to each other, and they have
Speaker 2: charges relative to each other, they feel forces relative to
Speaker 2: each other. They can also get bound together. They can
Speaker 2: form complicated stuff.
Speaker 1: But wait, if two gluons can interact and push on
Speaker 1: each other, what causes to push it? Is there a
Speaker 1: force another force particle just for transmitting the strong force
Speaker 1: or the glue force between gluons.
Speaker 2: No, they can push on each other directly, the way
Speaker 2: like a photon can push on an electron directly. That's
Speaker 2: an immediate interaction. Those two fields couple and energy can
Speaker 2: flow from one to the other. Gluons can talk to
Speaker 2: each other directly without any other intermediate particle. Like quarks
Speaker 2: can't talk to each other directly. They have to use
Speaker 2: photons or gluons, whatever, But those photons can talk to
Speaker 2: quarks or two electrons. Gluons can talk to each other directly,
Speaker 2: like in the language of finement diagrams. You can have
Speaker 2: a vertex that's just like gluon, gluon, gluon or four
Speaker 2: gluons in fact, can make a vertex, so you don't
Speaker 2: need an intermediate field. This is the field and it
Speaker 2: can talk to itself.
Speaker 1: And that's kind of weird, right because for example, the
Speaker 1: photon is another particle that transmits forces, but it can
Speaker 1: interact with itself.
Speaker 2: That's right. It can't interact with itself, so you can't
Speaker 2: have like a light ball. There is ball lightning out there,
Speaker 2: I think people think, but it's not like photons bound
Speaker 2: together in the same way. But gluons, because they can
Speaker 2: do this, they can talk to each other, they can
Speaker 2: feel forces relative to each other. They can create a
Speaker 2: little potential well and trap each other inside, and they
Speaker 2: can make. We think this particle called a glue ball,
Speaker 2: which is a particle made just out of gluons, which
Speaker 2: is really weird because it would have no matter particles inside,
Speaker 2: no fermions at all, no electrons, no quarks, nothing that
Speaker 2: we think of as making up matter. It would be
Speaker 2: pure force.
Speaker 1: Now do gluons only attract each other or do they
Speaker 1: also repel each other? Or does it depend on what
Speaker 1: color combination they are.
Speaker 2: It depends on the color combination. It also depends on
Speaker 2: the distance. The strong force is super duper weird, and
Speaker 2: it's very attractive at some distances and repulsive at other distances.
Speaker 2: And the strong force in general is very difficult to
Speaker 2: understand and also to do calculations with one because it's
Speaker 2: so strong. Like a lot of times when we're doing calculations,
Speaker 2: the actual calculation we want to do is impossible. Say,
Speaker 2: for example, I want to know how an electron is
Speaker 2: going to move through the universe. To really know that,
Speaker 2: I have to account for like all the electrons that
Speaker 2: are out there, the electrons in other galaxies. Technically those
Speaker 2: affect my electron, but because they're so far away, I
Speaker 2: can ignore it. I'll mostly get the right answer that's
Speaker 2: not true for the strong force. The strong force is
Speaker 2: so strong, so powerful that a lot of these effects,
Speaker 2: other quirks in other places and gluons that are created
Speaker 2: by other gluons become very very difficult to calculate and
Speaker 2: are not small effects. And so the approximations that help
Speaker 2: us succeed in doing otherwise impossible calculations for other forces,
Speaker 2: those tricks don't work for the strong force. So a
Speaker 2: lot of basic stuff about the strong force we just
Speaker 2: don't know how to calculate because gluons can do this
Speaker 2: thing where they create other gluons, and because the force
Speaker 2: itself is so so powerful.
Speaker 1: Mmmm. Well, going back to my question, I guess is like,
Speaker 1: what makes two gluons attract each other? Is it like
Speaker 1: all the red ones attract anything with red or repel
Speaker 1: anything that has read in it? You know, like you
Speaker 1: have a red blue glue on, what does it get
Speaker 1: attracted to a green blue?
Speaker 2: Well, you can't have a red blue gluon. You can
Speaker 2: have like a red anti blue or a blue anti red,
Speaker 2: or like a red anti red gluon. But whether they're
Speaker 2: attracted to each other or repel to each other depends
Speaker 2: on a lot of complicated calculations. I mean, the attraction
Speaker 2: comes from like having a potential. Now, are all forces
Speaker 2: in the universe really come from potential differences? Forces are
Speaker 2: due to changes in the potential. Things like to roll
Speaker 2: down hill as a gravitational force because the gravitational potential
Speaker 2: energy is lower at the bottom of the hill, or
Speaker 2: electrons are pushed towards the nucleus because that's where the
Speaker 2: bottom of the electromagnetic potential is. So to think about
Speaker 2: things in terms of forces pulling or pushing, you have
Speaker 2: to understand where the potential is at a minimum, and
Speaker 2: that's really complicated. For the strong force, it's not always
Speaker 2: that simple. Remember we even try to talk about it
Speaker 2: once for the weak force, and it's not always obvious whether,
Speaker 2: for examples, W bosons and Z bosons push or pull
Speaker 2: on each other. They can do both or sometimes it
Speaker 2: depends on the context. And that's even more complicated here
Speaker 2: for the strong force. So in some arrangements, these gluons
Speaker 2: can tug on each other, create a potential minimum and
Speaker 2: get trapped in this well and become a bound state.
Speaker 1: Okay, so I'm getting the sense that it's complicated. It's complicated,
Speaker 1: but it can seem to happen throughout If you sort
Speaker 1: of pierce through all of the mass, there are situations
Speaker 1: where you can get a couple of two or maybe
Speaker 1: more gluons kind of wanting to hang out with each other,
Speaker 1: really close together. That's kind of the idea I'm getting.
Speaker 2: Yeah, from the calculations, which are not perfect and are approximate,
Speaker 2: and nobody is one hundred percent confident in them, we
Speaker 2: see this prediction emerge that gluons should be able to
Speaker 2: get bound to each other and create this persistent state
Speaker 2: that lives for a while, not forever. It's not stable.
Speaker 2: It's not like you can make a glue ball and
Speaker 2: then come back a billion years later and still have
Speaker 2: a glue ball. But very briefly, they'll hang out in
Speaker 2: this little state, do their thing, and then explode into
Speaker 2: a shower of other particles.
Speaker 1: That's the prediction, and so when they come together, that's
Speaker 1: what you would call a glue ball, Etceterronically, the gluons
Speaker 1: don't stick around very long.
Speaker 2: They're not as sticky as we'd like them to be.
Speaker 1: Gluons are not sticky. You mean, glue balls don't stick together.
Speaker 1: And you were saying this is a good name.
Speaker 2: Maybe in super symmetry, we'll have super gluons and those
Speaker 2: will make super glue balls that will really stick together.
Speaker 1: There you go, all right, so then so gluons can't
Speaker 1: stick to each other, and then you think this happens. Now,
Speaker 1: does this happen with real gluons or virtual gluons, or
Speaker 1: it can happen to both.
Speaker 2: This happens from real gluons. So if you create enough
Speaker 2: real gluons, they can come together to make a glue
Speaker 2: ball in the same way that for example, if you
Speaker 2: make quarks, you make a spray of quarks. Quarks do
Speaker 2: not like to be a part Two quarks are very
Speaker 2: far apart from each other. There's a huge potential energy there,
Speaker 2: and that potential energy gets turned into other particles, and
Speaker 2: those particles quickly find partners and form masons and baryons.
Speaker 2: Those are combinations of pairs or triplets of quarks. So
Speaker 2: for example, you have protons or pions or k masons
Speaker 2: or all sorts of other stuff. You know, at the
Speaker 2: Large Hadron Collider, when we smash two protons together, we
Speaker 2: expose the quarks inside them. Briefly, we got these sprays
Speaker 2: of quarks and gluons but they really don't like to
Speaker 2: be by themselves, and so they very quickly create these
Speaker 2: streams of other particles with them, and then they form
Speaker 2: these states. And so what we actually see in our
Speaker 2: detector are streams of like protons and chons and neutrons
Speaker 2: and all sorts of other stuff. So quarks do this,
Speaker 2: they find partners and form other states. And so we
Speaker 2: think that maybe gluons can do this too, that like
Speaker 2: two or three gluons can come together and make something
Speaker 2: we call a glue.
Speaker 1: Ball, because the math is telling you that they are
Speaker 1: sort of compatible, that there is sort of a way
Speaker 1: where you can put together two or three gluont where
Speaker 1: they'll want to stick together exactly.
Speaker 2: And they will be color neutral. They will be white.
Speaker 2: You can match all their colors together to make a
Speaker 2: color neutral object, which in principles should last for a
Speaker 2: little while.
Speaker 1: All right, Well, let's stick a little bit deeper into
Speaker 1: what a glue ball is like and whether or not
Speaker 1: we found it, and if we have, what does it
Speaker 1: mean about our understanding of the universe. But first, let's
Speaker 1: stick another quick break. All right, we're talking about a
Speaker 1: very sticky subject glue balls, which is what happens when
Speaker 1: you potentially get a couple of gluons together, they'll maybe
Speaker 1: stick to each other and form basically a ball.
Speaker 2: Of glue, a literal ball of fundamental glue.
Speaker 1: It sounds like you're saying that if you take a
Speaker 1: couple of gluons and they do stick together, then they
Speaker 1: wouldn't be stick anymore because it would all sort of
Speaker 1: cancel each other out in terms of their charge. Right,
Speaker 1: So glue ball be sticky at all, It wouldn't right,
Speaker 1: it would just be lethal.
Speaker 2: That's a great point. They'd be sticky on the inside, right,
Speaker 2: but all the stickiness would be reserved for the other gluons.
Speaker 2: On the other hand, you know, that's also truer protons. Technically,
Speaker 2: protons have no color charge, and yet if you bring
Speaker 2: a bunch of protons together, they can get stuck together
Speaker 2: from the residual color charge. If you're on one side
Speaker 2: of the proton, you might be closer to one of
Speaker 2: the quarks than the others, so the charges don't exactly balance,
Speaker 2: and that's how the nucleus is together. So in principle,
Speaker 2: it might be possible to like have a bunch of
Speaker 2: glue balls and have them all stick together. But yeah,
Speaker 2: they're stickiest on the inside, for sure.
Speaker 1: You mean they might be sticky on the outside, but
Speaker 1: from afar, a glue ball would not be very glue.
Speaker 2: Yeah, a glue ball technically has no color charge and
Speaker 2: no electric charge either.
Speaker 1: All right, well, what else can you tell us about
Speaker 1: these theoretical glue balls.
Speaker 2: So it's predicted that if these gluons exist, that they
Speaker 2: would not be very very heavy. You know, they would
Speaker 2: only be like one to five giga electron volt in mass,
Speaker 2: which is not that heavy. You know, a proton is
Speaker 2: about one gigle electron bolts. So we're talking about something
Speaker 2: that's like one to five times as massive as the proton,
Speaker 2: and that sounds like something we should be able to
Speaker 2: discover because our collider has found things that are much
Speaker 2: much heavier. We're usually limited by the energy. You want
Speaker 2: to make something really massive, you have to pour enough
Speaker 2: energy into the collision to make that thing, because remember
Speaker 2: energy and mass are sort of interchangeable. You want to
Speaker 2: make a heavy Higgs boson, you have to have enough
Speaker 2: energy of one hundred and twenty five protons in your collision.
Speaker 2: But our collider is super powerful. It's thirteen thousand GeV
Speaker 2: in the collision, so there's plenty of energy to make
Speaker 2: heavy stuff. Glue balls are really pretty light in comparison,
Speaker 2: They're not really very massive. There are only a few
Speaker 2: proton masses worth.
Speaker 1: Well, it's interesting that they have mass, right the gluons, Like,
Speaker 1: does an individual gluon have mass by itself? It's a
Speaker 1: force force transmitting particle, Does it have mass on its own?
Speaker 2: It doesn't. Gluons themselves do not have mass, like photons
Speaker 2: do not have mass, but a globe all would have mass,
Speaker 2: the same way that, like a proton has mass, Most
Speaker 2: of the mass of a proton doesn't come from the
Speaker 2: quarks that make it up, Like a proton is one GeV,
Speaker 2: but the quarks inside of it are like one percent
Speaker 2: of that mass. Most of the mass of the proton
Speaker 2: actually comes from the gluons inside the proton. Because remember
Speaker 2: that mass is this weird thing. It's not just like
Speaker 2: how much stuff is inside something. It's all of the
Speaker 2: internal stored energy. So if you have a bunch of
Speaker 2: energy stored in the bonds between your quarks, that counts
Speaker 2: towards your mass. And that's true for other kinds of things,
Speaker 2: like if you could get a bunch of photons and
Speaker 2: store them inside something. Even if they're massless, they would
Speaker 2: add to the mass of that object. In fact, you
Speaker 2: take a rock and it absorbs a photon, that rock
Speaker 2: gets more massive because it's now absorbed that photon's energy.
Speaker 2: So mass is a weird thing. You can make it
Speaker 2: out of massless stuff.
Speaker 1: Well, we talked about before, and I know we talked
Speaker 1: about this in our book. Frequently asked questions about the
Speaker 1: universe that the mass doesn't really exist, Like mass is
Speaker 1: just energy, and what you think of as gravity or
Speaker 1: inertia is really just what happens when you kind of
Speaker 1: concentrate energy in one little spot. And so that's kind
Speaker 1: of what's happening here. Is like an individual gluon doesn't
Speaker 1: have mass, but when you put it together with another gluon,
Speaker 1: you're sort of trapping energy in one spot and then
Speaker 1: suddenly you've got a little spot of energy, and so
Speaker 1: that feels gravity and it feels inertia.
Speaker 2: Yeah, that's what we call mass, right, that's inertial. Mass
Speaker 2: is localized. Internally stored energy has this property that if
Speaker 2: you push on it, it takes a force to accelerate it.
Speaker 2: That's what we call inertial mass, and that's kind of
Speaker 2: a weird and deep mystery of the universe. But yeah,
Speaker 2: you can make it out of massless stuff, as you say,
Speaker 2: as long as you concentrate some energy in there. And
Speaker 2: glue balls definitely have energy inside them. These gluons have
Speaker 2: energy even though they are massless.
Speaker 1: All right, Well, it sounds like a glue ball is
Speaker 1: not really sticky, and like you were saying, it's also unstable,
Speaker 1: like it's not only not sticky, but it doesn't want
Speaker 1: to stick to its over.
Speaker 2: Yeah, like many of these particles, it's unstable. You know,
Speaker 2: the proton is a very unusual particle because it is stable,
Speaker 2: but every other combination of quarks, for example, is unstable.
Speaker 2: Even the neutron will fall apart in about eleven minutes.
Speaker 2: And these other particles, pions and chons, they're created, they
Speaker 2: live sometimes very briefly before they spray out into other
Speaker 2: lighter particles. And the glue ball is no different. It's
Speaker 2: a combination of these strong color charged particles. But it
Speaker 2: also decays into other stuff. And so for example, glue
Speaker 2: ball can turn into two photons, or can turn into
Speaker 2: like four quarks or a shower of gluons or all
Speaker 2: sorts of other stuff.
Speaker 1: You can get showered with blue bits.
Speaker 2: Yeah, they can basically explode into little bits of glue.
Speaker 1: Wow, doesn't sound very glue like at all. I'm slowly
Speaker 1: ungluing your use of the name glue here. Oh man, Well,
Speaker 1: I get The big question now is have we found
Speaker 1: glue balls? Theoretical, we think they can exist and maybe
Speaker 1: exist out there using our math, but have we found one?
Speaker 1: Have you ever seen a googball?
Speaker 2: The weird thing is that we're not sure. Sometimes it's
Speaker 2: very obvious when you've discovered a particle because there's only
Speaker 2: one thing that it can do and nothing else can
Speaker 2: do that. So, for example, when we discovered the Higgs boson,
Speaker 2: we didn't see the Higgs directly, but we saw pairs
Speaker 2: of photons that it decayed into that were flying apart
Speaker 2: from each other with a very specific characteristic energy. We
Speaker 2: found lots and lots of examples of photons with those
Speaker 2: kinds of energies, and we said, this can only really
Speaker 2: come from the Higgs boson, and therefore we're pretty sure
Speaker 2: we found the Higgs boson. And the key there is
Speaker 2: that it was doing something unusual, something that made it
Speaker 2: like stick out from the background. Now, glue balls are
Speaker 2: much more complicated because number one, we're not exactly sure
Speaker 2: what they can do, Like, we're not sure exactly how
Speaker 2: much masks they have. Maybe they have one GV, maybe
Speaker 2: they have five GV. Maybe we're wrong and they have
Speaker 2: like fifty gvre. Because the calculations we talked about are
Speaker 2: very complicated and make a lot of approximations that nobody
Speaker 2: really believes are right, and we hope didn't mess up
Speaker 2: the calculations. And also there's lots of other particles down there,
Speaker 2: like the Higgs boson we found it where there are
Speaker 2: very very few particles of that kind of mass, very
Speaker 2: heavy particles, but there's lots and lots of very light particles.
Speaker 2: If you look at like the list of particles, there's
Speaker 2: like hundreds of particles around one GeV, all sorts of
Speaker 2: crazy combinations of quarks. So it's hard to pick out
Speaker 2: a new one and say, oh, this one is a
Speaker 2: glue ball, especially because we're not exactly sure what a
Speaker 2: glue ball would look like.
Speaker 1: Hmmm, I see, the theory doesn't predict what it would look.
Speaker 2: Like, so the theory is impossible to do perfectly. There's
Speaker 2: lots of approximations people have made, and they make different predictions.
Speaker 2: Some predict like one point four GeV, some predict five GeV,
Speaker 2: and they also give different predictions for how these things
Speaker 2: might appear. You know, these glue balls have different properties
Speaker 2: from the other particles, like they're weird internal spin and
Speaker 2: other quantum states. Those might make like characteristic signatures, you know,
Speaker 2: like how they turn into other particles, and how those
Speaker 2: particles look. There were angles between each other and the
Speaker 2: relative spin states and this kind of stuff. But again,
Speaker 2: different theoretical calculations make different predictions here, and it's also
Speaker 2: sometimes hard to disentangle from what we're seeing out there. So,
Speaker 2: for example, there is a particle that people have found
Speaker 2: that has about one and a half GeV. It's called
Speaker 2: the F zero, and there's a raging debate in the
Speaker 2: literature about whether or not it is a glue ball.
Speaker 2: Some people say this is totally consistent with the glue ball,
Speaker 2: and other people say, no, Look, it can do this
Speaker 2: and that, and gloe balls shouldn't be able to do that,
Speaker 2: so we don't think it's a glue ball. Nobody can
Speaker 2: really agree about whether the F zero is a glue
Speaker 2: ball or not.
Speaker 1: Whoa wait, wait, wait a minute. You've discovered a particle
Speaker 1: out there. You gave it the name F zero, but
Speaker 1: you don't know what it is. What do you mean
Speaker 1: you don't know what it is? What do you mean
Speaker 1: you've found something that you don't know what it is?
Speaker 1: Wouldn't that be a big deal.
Speaker 2: So we found this particle, we've seen it decay into
Speaker 2: like two pions into four pions, right, and so we
Speaker 2: know that it exists. We can see that it's there.
Speaker 2: Like you find the pions, you add up their energies,
Speaker 2: they're consistent with a particle of mass one and a
Speaker 2: half GeV. That doesn't mean that we know what's inside
Speaker 2: the F zero, Like, is the F zero made out
Speaker 2: of two quarks? Can you explain what the F zero
Speaker 2: is doing just using quarks or do you need this
Speaker 2: special gluon state to explain it? People disagree about whether
Speaker 2: what the F zero is doing can be explained using
Speaker 2: only quarks or requires gluons to explain it.
Speaker 1: I see, so you're not quite sure if you found
Speaker 1: a particle, you found something that could be a particle.
Speaker 2: We found something. The F zero is definitely something. It exists,
Speaker 2: We're just not sure what's inside of it? Like, is
Speaker 2: the F zero made out of quarks or is it
Speaker 2: made out of gluons? Nobody's one hundred percent sure because
Speaker 2: it's a mess down there, and it's hard to make
Speaker 2: very precise measurements of what the F zero is doing.
Speaker 2: We're sure it's there. Nobody's doubting that the F zero
Speaker 2: is real. They just don't really know exactly what it's
Speaker 2: doing and what it's made out of.
Speaker 1: Well, are people looking for glon or is this something
Speaker 1: you're just looking at from the debris of other experiments?
Speaker 1: Is there like a glue ball experiment other and are
Speaker 1: the scientists called glue ballers.
Speaker 2: This is a really exciting frontier in particle physics, but
Speaker 2: also very very difficult. You know, it's a place where
Speaker 2: we don't have crisp predictions and it's really hard to
Speaker 2: see what's happening because everything is a big, messy spray
Speaker 2: of particles. It's not like very crisp and clear one
Speaker 2: photon one electron bouncing off of each other like in
Speaker 2: the early days. You got like a big mess of
Speaker 2: stuff you have to sift through. But there are dedicated
Speaker 2: experiments just to understanding the strong force and specifically to
Speaker 2: understanding gluons. So at Jefferson Lab in the East Coast
Speaker 2: the United States, it is an experiment called glue x.
Speaker 2: I don't know if they pronounced it gluks or glue
Speaker 2: x or glueeks. I'm not exactly sure, but it's an
Speaker 2: experiment that's running right now to study specifically gluons. What
Speaker 2: can they do? Can we find glue balls? Can we
Speaker 2: see it doing other stuff maybe that we didn't expect?
Speaker 1: Have they found it?
Speaker 2: They have not yet found confirmation of glue balls. They're
Speaker 2: trying to study this f zero, but they don't have
Speaker 2: enough data yet to confirm whether or not that's real
Speaker 2: and understand it's decay products. So far, they've been putting
Speaker 2: out preliminary studies and understanding all sorts of other things.
Speaker 2: This is a sort of general powerful detector that can
Speaker 2: study lots of different things about the strong force, because
Speaker 2: whether glue balls exists is one question, but there's so
Speaker 2: many other questions about what's going on with the strong force,
Speaker 2: and this is exploring a lot of them.
Speaker 1: Would you say then that they're kind of stuck at
Speaker 1: the moment.
Speaker 2: I would say it's a sticky question.
Speaker 1: Yeah, for sure, well, let's see if they do find
Speaker 1: glue balls. And it's kind of an interesting idea because
Speaker 1: I think, as you're saying, it's not just about finding
Speaker 1: the glue ball themselves. It's about understanding how the strong
Speaker 1: force works, right, Like, it's one of the fundamental forces
Speaker 1: of nature. It's what keeps our nucleus in our atoms together.
Speaker 1: But it sounds like we don't really sort of like
Speaker 1: know everything about it or know exactly how it works,
Speaker 1: and so finding or not finding a glue ball would
Speaker 1: sort of tell you a little bit of about what's
Speaker 1: going on at that level.
Speaker 2: Yeah, that's exactly right. The same way that understanding the
Speaker 2: structure of the atom has taught us a lot about electromagnetism.
Speaker 2: You know, why electrons fill these shells, the hyper fine
Speaker 2: splitting of electron energy levels has led to a really
Speaker 2: deep understanding of magnetism and spin and electricity and all
Speaker 2: this kind of stuff. You know, seeing these forces in action,
Speaker 2: what kind of complex things they can do or reveals
Speaker 2: their fundamental nature. So we're trying to do the same
Speaker 2: thing for the strong force, like see the strong force
Speaker 2: in action, see what it's capable of, what it can't do,
Speaker 2: and that'll tell us if we understand what it's doing
Speaker 2: or not. But in the end, it's much harder than
Speaker 2: it is for electromagnetism because it's more complex. Instead of
Speaker 2: one photon, we have eight gluons of all sorts of
Speaker 2: different colors, sloshing around and banging into each other and
Speaker 2: confusing each other. It's like having a conversation with eight
Speaker 2: Toddlers at the same time.
Speaker 1: Every PhUSE is a stream, but it sounds like it
Speaker 1: is a prediction of the current standard model, like our
Speaker 1: current model of the universe does predicted glue balls should exist,
Speaker 1: and so if you find them, it would be another confirmation,
Speaker 1: maybe the final confirmation about the standard model. But if
Speaker 1: you don't find them, and you can conclusively say that
Speaker 1: they do not exist, then maybe we need to rethink
Speaker 1: our whole model of the universe.
Speaker 2: Yeah, that's exactly right. It would be almost as big
Speaker 2: a deal as discovering the Higgs boson if we did
Speaker 2: find confirmation of a glue.
Speaker 1: Ball or not a confirmation about blueball.
Speaker 2: Yeah, if you could prove that glue balls don't exist,
Speaker 2: that would also be fascinating.
Speaker 1: I can just see the headline scientists fine glue balls
Speaker 1: do not exist.
Speaker 2: Scientists fail to find glue balls.
Speaker 1: Again, Scientists get stuck with blue balls. All right, Well,
Speaker 1: we hope you enjoyed that. Thanks for joining us, see
Speaker 1: you next time.
Speaker 2: Thanks for listening, and remember that Daniel and Jorge Explain
Speaker 2: the Universe is a production of iHeartRadio. For more podcasts
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