What is a particle?

Daniel and Kelly try to get an solid mental picture of this particularly slippery concept See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Daniel Whiteson?

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• 1:42Daniel Whiteson?

  What is everything made out of? That seems like a simple question, and it also seems like a reasonable question. I'd like to know what I'm made out of, what my food is made out of, what kittens are made out of, what lava is made out of. It's also an ancient question, I think one that people have been asking since people have been asking, you know, any questions. The Greeks, famous for asking questions in their sexy robes, thought that everything was made of earth, air, water, and fire. And modern science, of course, has made a lot of progress here and uncovered some pretty weird and kind of shocking news about what everything is made out of. What seems like smooth and continuous matter is actually made up of tiny little bits that

• 2:24Daniel Whiteson?

  are woven together into some extremely fine mesh. And we are all made of the same basic bits, summed together to make me, or you, or kittens, or lava. The world is made of particles. But our curiosity doesn't just end because we have that answer. We want to know, what are these basic bits? How do we think about them? What mental picture should we have in our mind? Are they tiny dots of stuff, or rippling waves, or some other concept that's too alien to even imagine? And what does it tell us about the universe that these are its basic building blocks? Or are they? So today, on Daniel and Kelly's Extraordinary Universe, we'll be tackling the basic yet

• 3:06Daniel Whiteson?

  confusing, the simple yet deep, the important but impossible question, what is a particle?

• 3:25Kelly Weinersmith?

  Welcome to Daniel and Kelly's Extraordinary Universe. I am Kelly Wiener-Smith. I'm a parasitologist, and I'm particularly excited to be here today. You know, that might have been really cute if I had been able to pull it off, but I didn't.

• 3:40Daniel Whiteson?

  Hi, I'm Daniel. I'm a particle physicist, which means I probably should know what a particle is.

• 3:47Kelly Weinersmith?

  Well, we've got the right expert on the show today. So, Daniel, here's what I'm wondering. So you've told me that you go to CERN in Switzerland to do your research. Why doesn't the United States have the biggest particle collider?

• 4:00Daniel Whiteson?

  Oh, my gosh, wow. You are putting your foot in a sensitive spot right there. You know, for many years, it was a race between the Europeans and the Americans. So before CERN had the most powerful collider, we had one. It was outside of Chicago at Fermilab. It was called the Tevatron. I did my PhD there. I had one child born near that collider, and then my next child born near CERN. You know, I had a kid at each collider, basically.

• 4:25Kelly Weinersmith?

  Wait, one of your kids was born abroad?

• 4:27Daniel Whiteson?

  Yeah, my daughter Hazel was born in Switzerland, very close to CERN.

• 4:31Kelly Weinersmith?

  That's cool. Did you have to not pay because you were in Europe and they just do healthcare better there? Or what was that like?

• 4:37Daniel Whiteson?

  No, actually, they told us that when we showed up for the delivery, we had to bring 50,000 Swiss franc in cash if we didn't have local insurance.

• 4:46Kelly Weinersmith?

  Whoa.

• 4:47Daniel Whiteson?

  So yeah, that was going to be an issue. But then we discovered there's a law in Switzerland that if you're working there, which my wife was, they have to insure you. So even though she had all sorts of crazy pre-existing conditions, we could buy insurance for like 100 franc and then we didn't have to pay for anything. So it was amazing, actually.

• 5:04Kelly Weinersmith?

  Nice. Okay, that's good.

• 5:06Daniel Whiteson?

  And the insurance company even offered to retroactively cover a bunch of appointments where we hadn't yet had insurance. It was a very different experience than American insurance.

• 5:15Kelly Weinersmith?

  Yeah, that's incredible. I'm going to get depressed if we stay on this topic too long. Let's go back to particle colliders. Okay, so you have had each of your children near very large particle colliders. Why isn't the biggest one in the US?

• 5:26Daniel Whiteson?

  Well, they planned to build the biggest one in the US, the Superconducting Super Collider in Waxahachie, Texas. And they started building it and they spent billions of dollars digging a hole. But then the director of CERN at the time came and testified before Congress saying it was a big waste of money because CERN was building one that was going to be bigger and better and they should just cancel it. And Congress, for all sorts of complicated political reasons, listened to him and canceled the American Superconducting Super Collider. And since then, the lead has been in Europe and probably will for a while. And the US particle physics community is mostly focused on things like neutrinos and stuff like that. So these days, if you want to do cutting-edge, high-energy particle physics at colliders, you got to go to Switzerland, which hey, it's not too bad.

• 6:11Daniel Whiteson?

  The chocolate's amazing.

• 6:12Kelly Weinersmith?

  No doubt. You know what? Actually, I'm going to go out on a limb here and say I'm not a huge fan of Swiss chocolate. Yeah, I know.

• 6:18Daniel Whiteson?

  You prefer Belgian?

• 6:19Kelly Weinersmith?

  I do. Yeah, there, I said it. So every once in a while, I'll hear about like astronomy students who want to get time on a telescope, but the telescope's all booked up and it takes forever. Does CERN have enough time for everyone? So like when that guy came to the US and tanked our program, did he know he was going to have enough time for all of our scientists to come over and do their work?

• 6:39Daniel Whiteson?

  Yeah, that's a great question. And people often ask me about that, like, what's it like to set up your experiment at the collider? But the reality is very different. Telescopes and colliders don't work the same way. A telescope, you have to like, point at the thing you want to look at. So you write a proposal to say, let's point our amazing telescope at this one star I want to study. And then it's not pointing at any other stars. But a particle collider is very general. It always just does the same thing. It smashes the particles together, and you take pictures of it. And then afterwards, you analyze it. So everybody who uses the collider uses the same data. They're just looking for different kinds of particles. We don't have to point the collider at certain things. We don't swap out what we're using to take pictures. Every few years, we turn the thing off, revamp it, build a new detector that's better, faster, higher

• 7:23Daniel Whiteson?

  resolution, or whatever. And then we make it as general as possible. So everybody can use it. So you don't have to swap it out every day or every experiment. Everybody uses the same data set, which makes it kind of crazy, because everybody's looking for discoveries in the same data set at the same time. So you could get scooped by any of your thousands of colleagues.

• 7:41Kelly Weinersmith?

  Yikes. So do you actually need to be there in person? Or if it's just data, they can make that available anywhere, right?

• 7:49Daniel Whiteson?

  CERN has long been at the forefront of the internet. We invented the web at CERN, for example. And we have excellent cloud computing. And so we transfer that data all around the world. We've collaborated from Japan to Singapore, to South Africa, to the northern tip of Canada, all over the world, people analyze this data. Absolutely. You don't have to go. I go frequently because I have students there and postdocs are like onsite building stuff and helping keep it run. But technically, you don't have to to look at the data.

• 8:16Kelly Weinersmith?

  Cool. I mean, that's good and bad. I feel like ecologists, like, we want to study exotic animals. But partly it's because we want to go there. And I imagine it's sort of the same with CERN. Like, it'd be nice to go to Switzerland. But I guess the more important thing is answering the question.

• 8:27Daniel Whiteson?

  It is nice to go to Switzerland. But then again, it's also nice to be able to do science without having thousands of dollars to go to Switzerland, which means smaller groups and not such fancy institutions, for example, could also participate. So it makes it a little bit more democratic, you know?

• 8:41Kelly Weinersmith?

  Nice. That's awesome. Okay, so the whole point of having a large particle collider is so that you can figure out what those particles are made of. Is that right?

• 8:50Daniel Whiteson?

  The whole point of having a particle collider is that you can say you're smashing particles together at nearly the speed of light, which sounds pretty awesome at parties.

• 8:57Kelly Weinersmith?

  It does. Yeah. Kind of like jousting for particles.

• 9:00Daniel Whiteson?

  Yeah, well, particle colliders, I think, sort of have two different purposes. One is like, hey, let's take stuff and see what's inside it. Let's start with something familiar, you know, like the proton and smash it open and see what it's made out of. And that's a continuation of like a long glorious tradition of taking the stuff around us apart to understand what it's made out of. You know, I'm made of molecules, which are made of atoms, which have a nucleus, an electron. The nucleus is made of protons. Let's go inside the proton. So that's definitely worthwhile and we do that. But colliders can actually do something else even more powerful, which kind of sounds like magic, which is that they can convert the mass of those protons into energy and then back into mass.

• 9:41Daniel Whiteson?

  And so what can come out of the collision is not just a rearrangement of what went in. It's not like chemistry where you're like, this hydrogen moved from this atom to over there. And now you have a different kind of compound. You could annihilate these things and then you basically have like a budget to make anything. And the stuff that comes out of the collision doesn't just have to be like a refashioned rearranged version of what went in. You could have entirely new matter. It really is alchemy. So like protons go in, you have this intermediate state of frothing energy. And then you can make whatever the universe can make. Dark matter, muons, all sorts of other stuff. You're not just rearranging the protons.

• 10:21Kelly Weinersmith?

  There's got to be some rules, right, for what you can make?

• 10:25Daniel Whiteson?

  Yes, exactly. That's the whole premise of particle physics. There are rules, there are patterns. Quantum mechanics tells us what's likely to happen in certain collisions. We look at those patterns, we notice, oh, this typically happens and it typically shoots out at those angles. What are the rules that control this? Absolutely, there are rules, but fundamentally it's random, right? Like you do the same collision twice, you get two different answers because it's quantum mechanical. It's not determined by the initial conditions. So it's really a very powerful way to explore the universe because you don't have to know what's out there in order to discover it. You smash protons together often enough, eventually everything the universe can do, it will do. And you get to take pictures of it.

• 11:05Kelly Weinersmith?

  Wow.

• 11:06Daniel Whiteson?

  It's like, imagine if you could build a box and every kind of creature that could exist on Earth would randomly cycle through that box. You could just sit there and watch, be like, oh, wow, I didn't know that existed. Oh, look at those things. What are those? You know, that would be pretty powerful. That's basically what we can do with particle physics.

• 11:23Kelly Weinersmith?

  Now you have my attention. Although that box, I guess, would mostly be showing me like different species of bacteria, which would be a bummer. If it could show me different species of bugs, that would be great.

• 11:32Daniel Whiteson?

  Yeah, it'd be mostly beetles. You're like, wow, it's basically a beetle box, right?

• 11:36Kelly Weinersmith?

  So there is that famous saying that like, God is inordinately fond of beetles, because there's this thought that beetles are the most common species group on the planet. But actually, quite often, those beetles are infected by more than one species of hymenopter and wasp. And so we think there might actually be more wasp species on the planet than there are beetles, based on that observation.

• 11:59Daniel Whiteson?

  And probably those wasps are infected by viruses. So they're more viruses than wasps.

• 12:04Kelly Weinersmith?

  Yes.

• 12:04Daniel Whiteson?

  And those viruses are made of particles. And boom, a boom, we're back to the topic of the episode.

• 12:10Kelly Weinersmith?

  But what makes up a particle, Daniel?

• 12:13Daniel Whiteson?

  Exactly. So we smash particles together. We look at what's inside them. We annihilate them to make new kinds of particles. We have this idea that particles are what everything is made out of. But I struggle still, after decades in this field, to understand this basic question, what is a particle? So I really want to explain to people what we do know and what we still don't know about this very basic concept that everybody talks about all the time.

• 12:37Kelly Weinersmith?

  Well, first, let's hear what our listeners think. And if you would like to be a listener who tells us what you think, send us an email at [email protected], and we will get you in the loop and send you a question from time to time, and you can send us your answers. So let's see how folks answer the question, what is a particle?

• 12:56Speaker 05

  A particle is a thing that interacts with other things.

• 13:00Speaker 06

  A particle is really just an excitation in a field. A particle is a defined portion of something.

• 13:10Speaker 07

  Something that is infinitesimally small to us. The smallest unit of energy or mass.

• 13:19Kelly Weinersmith?

  I think that particles are the excitement of different spatial spots in interaction. A particle could be a very small vibrating field, a mass or non-mass object. Exists within what we would perceive.

• 13:34Speaker 06

  As matter. A particle is a sub-microscopic kernel of energy and or matter. A particle is an excitation of a field. I do know that particles aren't just tiny bits of matter.

• 13:51Speaker 06

  I've heard that they're fields or strings or some other impossible to understand little bits of the universe. Particle is a ripple on a quantum field. Particle is the name we give to the smallest discreet quantum little bits that we know of and haven't been able to break up further yet. An expression of a field where the chances of that occurrence happening is the greatest there. The more think about it, the bigger this rabbit Warren is going.

• 14:30Daniel Whiteson?

  I think these answers perfectly encapsulate this episode. Really, it's an excellent snapshot because a lot of what people have said in here is correct. But also there's a huge list of conflicting answers. You know, is it the smallest bit of stuff? Is it just something in space time? Is it actually an excitation of a field? You know, there's so many conflicting concepts of what a particle is.

• 14:51Kelly Weinersmith?

  And is this one of those topics where at the end the answer is going to be? We really have no idea could be all of these things? Or is this a topic where at the end we're going to have a pretty clear answer?

• 15:03Daniel Whiteson?

  At the end, we're gonna have a pretty clear answer, but not at the end of this episode. At the end of this journey, which might be in 10 or 100 years, unfortunately.

• 15:12Kelly Weinersmith?

  Okay.

• 15:13Daniel Whiteson?

  I mean, we're gonna get somewhere today. We have a pretty crisp, clear view of what a particle is mathematically. But we also know why that's not really satisfactory. And there's lots of big, open questions about what that really means. So it's not like all particle physics is a scam because we don't know what a particle is. We have a working definition, but we also know that it's incomplete, just like most of science, right?

• 15:33Kelly Weinersmith?

  Oh, yeah. Amen. All right, well, so let's start with the historical perspective. Bring me back to the beginning. When did we start thinking about this question?

• 15:40Daniel Whiteson?

  Yeah, I think it's important to trace the origin of this historically. Because it still shapes how we think about the universe. And you know, whenever you ask a big question about science, you gotta think about like, what kind of answer you're looking for. And in science, even though we try to be like mathematical and open minded, and let the data tell us what the universe is saying, we still need to understand that data. We still need to interpret it. We still need to cogitate on it in a way that makes sense to us. And we're sort of limited in our mental intuitive language. We can't really grapple with things that we've never experienced that are completely alien to us. We tend to translate the unfamiliar into the familiar.

• 16:22Daniel Whiteson?

  You know, my favorite example of this is like, what happens when you drink a wine? Or you taste a new fruit and you're like, oh, this fruit tastes kind of like a cherry and kind of like an apricot and whatever, and then a little bit like a kiwi. You're explaining something new in terms of something you already know. And that makes a lot of sense. It's also what we do in science. And so it's important like dig into like, what are the sort of basic mental building blocks we're using to understand this stuff?

• 16:44Kelly Weinersmith?

  I think one of my favorite examples of that is the brain being compared to whatever technology is hot and new at the time, you know, like your brain is like a clock. Your brain is like a computer. And some of those analogies work in some ways, but you know, having an analogy like that sometimes limits the way you actually attack a problem.

• 16:59Daniel Whiteson?

  Yeah, but it also is what allows you to understand it, right? So in the end, it's sort of how we understand everything.

• 17:05Kelly Weinersmith?

  Yeah.

• 17:05Daniel Whiteson?

  And that's why it's useful to go back to like fifth century B.C. And talk about Democritus and his buddy Lusippus. Because these folks were thinking about, hey, what is the universe made out of? And they came up with this concept, or they're credited with this concept of what seems like smooth and continuous matter, you know, water seems smooth and continuous, air seems smooth, is actually made of tiny little bits of stuff. This is a big idea, right? This is a huge concept. This is like pulling back the veil on the world and saying, the world isn't the way that it seems. It's actually quite different. You know, it has like a resolution. These days, we're kind of familiar with this because you're used to things like, hey, I look at my TV screen. It looks like I'm just looking at a picture.

• 17:49Daniel Whiteson?

  But I know that if I put my eyeball close to the screen, I'll see pixels. This is basically saying the Whole world, all matter is actually pixelated. It's built out of little bits instead of smooth and continuous.

• 18:00Kelly Weinersmith?

  Did they have any thoughts about what the little bits were like? Like, do you get different bits in the sand and different bits in your skin? Or how fine grained was this idea?

• 18:11Daniel Whiteson?

  Oh, my God, they had hilarious ideas about what the little bits were. They thought that everything was made of a little bit of stuff, but that stuff had different shapes. And, you know, they were right on the spirit of it, that they thought like the properties of the shape determined how we experienced it and its property. But for example, they thought that some things tasted sour because it was made of little sharp needle shaped atoms that like stabbed your tongue when you ate it.

• 18:36Kelly Weinersmith?

  This is gonna be so condescending, but that's such a cute idea.

• 18:40Daniel Whiteson?

  It is so cute, I know. And they thought the things that were white were white because they were made of very smooth atoms. And they thought that your soul was made of atoms and that those atoms were particularly fine grained. They were right in the spirit in that the behavior and the structure of the atom really does determine like, hey, what is shiny and what conducts the electricity and what's liquid at room temperature? That's all true. They were just wrong on the details, but you know, they couldn't see atoms, they were just imagining. And I'm really impressed by this. I'm impressed by the courage to imagine that the universe is so fundamentally different from the way it seems, because that's really the scientific spirit, right?

• 19:19Kelly Weinersmith?

  Yeah, totally. Okay, so we've got Democritus and his buddy, what was the buddy's name?

• 19:25Daniel Whiteson?

  Mispronounced as Lecoups.

• 19:27Kelly Weinersmith?

  Lecoups.

• 19:27Daniel Whiteson?

  But I don't know the correct pronunciation.

• 19:29Kelly Weinersmith?

  I hadn't heard of that person before. So you got the two of them, and they're proposing that everything is made of small bits of stuff. How long before we get some clarity on the fact that sour isn't just sharp little bits of stuff?

• 19:43Daniel Whiteson?

  Yeah, so they're credited with this idea, probably came up earlier, because remember, we give people credit because we have a written record of it. We have like a tiny fraction of everything the Greeks wrote, though very excitingly, they're now scanning burnt scrolls from an ancient Greek library. We're going to like double the amount of Greek writing we have very soon. But also, you know, we just don't have writing from other civilizations. What did the Etruscans think? Ancient Chinese writing? So, you know, people give the Greeks a lot of credit, but we should remember like other people thought about this stuff, too.

• 20:12Kelly Weinersmith?

  Ain't that always the way?

• 20:13Daniel Whiteson?

  Yeah, it's always the way. I know. And they use the word atom because atomos in Greek means indivisible. So that's where that comes from. And this is the origin of this idea that, you know, smooth stuff is actually made of little bits. And that still guides our mental picture. When I think particle, I still think tiny little dot of stuff, like a little spinning ball or a grain of sand. That's sort of what it means to me. Like it's particular. Like if you say something is particulate, right? You mean it's made of these little bits. And so the words are powerful because they guide our mental images. But it wasn't for a couple of thousand years that we had really more information. I mean, it was chemists like Dalton who were doing experiments on chemical reactions

• 20:56Daniel Whiteson?

  and discovering, you know, laws of ratios and proportions. And the things were divisible by integers. That really gave us a clue that, oh, there were like units of stuff going into these equations. They really needed two to one hydrogen to oxygen to make a certain amount of water. Gives you a clue that it really is just clicked together out of these tiny little bits. So that was a really important clue. But it wasn't until the late 1800s that we really had the discovery of anything that we would today call a particle.

• 21:25Kelly Weinersmith?

  And is that because it's so tiny? It probably depends on having the right technology to be able to address that. And so did we just have to wait until the late 1800s? Because that's when we finally got the technology where we could start making a dent?

• 21:38Daniel Whiteson?

  Yeah, absolutely. And in the great tradition of particle physics, we didn't invent the technology that we use to make these discoveries. We borrowed it. In this case, we borrowed it from the circus.

• 21:48Kelly Weinersmith?

  From the circus?

• 21:52Kelly Weinersmith?

  All right, we're going to take a break. And when we come back, you're going to tell me about how the circus allowed us to understand the electron.

• 22:05Speaker 02

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  All loans and amounts subject to lender approval. Hi, it's Nora McInerney, host of the Head Start Embracing the Journey podcast. We're back with more honest conversations from people living with chronic migraine. People figuring out how to adapt, advocate, and stay connected to the things that bring them joy while managing their condition. People like romance novelist Britt Middleton.

• 22:54Kelly Weinersmith?

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  Listen to the Head Start Embracing the Journey on the iHeart Radio app or wherever you get your podcasts. This show is brought to you in partnership with AbbVie.

• 23:37Speaker 03

  Hey, I'm Niall Rogers, producer, songwriter, guitarist, and co-founder of the group Sheik. A great song has a way of defining a moment, a moment of joy, heartbreak, or anything in between.

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  You know, a song is a story, and the verse is setting the scene. And for me, at least, it's allowing me to be personal and vulnerable with the audience, whether it's about my wife and I'm being vulnerable about her, or it's about, you know, my parents and I'm being vulnerable to them. And it's almost like a cinematic piece in a way where each song tells that beautiful story.

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  It's gonna be one hell of a trip. Experience Before the Moment, a Lincoln Original Series on the iHeart Radio app, YouTube, or wherever you get your podcasts.

• 25:05Kelly Weinersmith?

  All right, and we're back. And today, we're talking about the freak show that is particles. And Daniel's going to tell us about how we were able to understand the electron from technology developed for the circus.

• 25:17Daniel Whiteson?

  Mm hmm. Back in the mid 1800s, there were circuses and there were these sideshows. And you know, you had bearded ladies or conjoined twins or whatever freak show you wanted to see. But also, you had people with weird gizmos. And in particular, somebody invented basically the cathode ray tube. But the cathode ray tube back then was actually called a Crook's tube. And basically, you have a glass and you put electricity on one side, electricity on the other side. And we now know what happens is that electrons boil off of one and fly through it and hit the other. But if you left a little bit of gas in that tube, then the electrons would hit that gas and the gas would glow. People were making these tubes because they glowed in this eerie way. And that was pretty cool. And you know, back

• 25:59Daniel Whiteson?

  in the 1800s, this was a magical thing to see that somebody could build this thing and it would glow green or glow red or whatever. And so these Crook's tubes were very popular on sideshows. And then later, scientists were like, hmm, what's going on here? Let's see if we can understand what's going on. And J.J. Thompson, in the late 1800s, used it to discover the electron.

• 26:21Kelly Weinersmith?

  How do you go from, oh neat, that tube lights up to, and that's because of electrons?

• 26:27Daniel Whiteson?

  Yeah. So J.J. Thompson was trying to understand what is lighting up here. And they already called these things cathode rays, because they could see paths. Like, definitely, there's a line of stuff moving through them. They were like, what are these rays? And made of something? A lot of people tried to understand this and failed. But he had like, the best vacuum, so the best control of this experiment. And he did it the most systematically. What he did was he put these tubes under electric fields. And he was like, hmm, can I bend these rays? And then he tried with magnetic fields, like, oh, can I bend the rays this way and that way? And he tried with combinations of them. And so we had an understanding of electromagnetism back then. We understood that electric fields pull things that have charge and magnetic fields can bend them.

• 27:09Daniel Whiteson?

  So from this, he determined, oh, these cathode rays are little bits of charge. There's charge flowing here because I can bend it with fields. And so that was really fascinating. And then he very carefully balanced the two fields and he was able to measure the mass of the thing. And that right there is the origin of this sort of concept of a particle. He was like, oh, these rays are made of tiny little bits of stuff that have a charge and a mass. And what he's doing conceptually there is very important. He's saying, there's a point in space and I'm going to put two labels on it. I'm going to say it has a charge and it has a mass and those two things cannot be separated. He tried to separate the mass and the charge and he couldn't. So he's like, now in his mind, he has these little dots that are moving through space and he's putting these mental labels on them.

• 27:53Daniel Whiteson?

  And that's really the origin of the modern concept of a particle.

• 27:57Kelly Weinersmith?

  Okay, so I'm imagining being in his lab. He's got this ray. He's got a magnet on one side and he does the magic and he's got that line. Is it like a bolt of lightning? Like, does it go from one side to another and you can see all of it? And if so, how does he make the jump from there's a line that lights up and bends towards the magnet to, and that line is made up of lots of little tiny things that come to be called electrons? You know what I mean?

• 28:23Daniel Whiteson?

  Yeah, so what you should be imagining is sort of like what a fluorescent light bulb looks like now. It's like long and thin and filled with glowing gas, right? Except they were like thinner lines. So these are very clearly rays. And you're right that he measured that there's sort of a flow of charge, right? So there was a screen on one end and you could see these glowing dots landing. But he also measured the mass. That's what told him that this was made of little bits because he could measure, actually their charge to mass ratio. He couldn't measure the mass itself, but he measured the charge to mass ratio by seeing how much they were deflected by the magnetic fields. That's the thing that gave him the clue that it was made of little bits, not just some continuous stream. Because he can identify a charge to mass ratio for these bits.

• 29:07Daniel Whiteson?

  And he almost sent the world down a crazy path where my job title would be different. Because he didn't call this thing a particle. He didn't call it an electron. He used the word corpuscle. He thought that was a really cool name for this thing that he had discovered.

• 29:22Kelly Weinersmith?

  Sounds like a kind of acne to me.

• 29:25Daniel Whiteson?

  To me, it sounds like an especially explosive kind of zit.

• 29:27Kelly Weinersmith?

  Yeah.

• 29:29Kelly Weinersmith?

  So you were almost a corpuscalologist?

• 29:35Daniel Whiteson?

  Or a corpuscular physicist. Fortunately, the person who discovers the thing doesn't always get to name it. And later on, people adopted the name electron suggested by Fitzgerald and Lorentz and other folks. And so fortunately, the word corpuscular didn't hang on. But that was really the seminal experiment where people discovered, okay, the world is made into little bits and we can put labels on them. And these days, we have so many labels for particles. We put spin on them. We put charge, of course, we put other kinds of charge. Every particle has a charge for electromagnetism, has a charge for the weak force, a charge for the strong force, it has a mass. This is really part of the concept of a particle is a little dot in space with labels that we put on it.

• 30:20Kelly Weinersmith?

  And it sounds like it gets complicated pretty quick. So let's back up a little bit. So we've got mass and charge. What is our next historical advancement?

• 30:29Daniel Whiteson?

  Well, next came Rutherford, because people were wondering, all right, so these things exist, these corpuscles, or these electrons, as we later call them. But how do you use that to make up the world? It's sort of like the twofold question we were talking about before. One thing you can do is try to answer like, what is everything around us made out of by taking it apart? The other is just to ask, what can the universe do? Like, not necessarily how am I built out of the universe, but what is the universe capable of sort of holistically? And so Thomson discovered, oh, the universe can make electrons. People were wondering, okay, are those electrons part of who we are? And, you know, they were speculating, we think electrons are probably inside the atom, but nobody knew yet what the atom's structure was. We knew that we had chemicals and we had these different atoms and periodic table,

• 31:14Daniel Whiteson?

  the elements was a thing, but nobody understood how the atom itself was built. And we suspected electrons were in there, but we didn't understand like, well, what's balancing that charge? And so Thomson proposed that like, well, we have electrons because I discovered them. And so there must be the building block of everything. And they're embedded in like a jelly, like a positive jelly that balances the charge. That was sort of his idea. But then Rutherford came along and said, well, let's see. And he took a sheet of gold foil and he shot radiation at it. And he wanted to understand like, what is that positive stuff made out of? And if that positive stuff was like, spread out like jelly, then he would expect that his particles would mostly just slop through it.

• 31:56Daniel Whiteson?

  But what he saw was that most of the time, they just shoot right through the foil, but occasionally, they bounce right back. What he concluded from that was that the positive charges weren't spread out evenly. They were clustered into these little hard dots. So, most of the time, the radiation missed it. Sometimes, they bounced right back. That gives us the more modern picture of the atom as a positive nucleus surrounded by electrons.

• 32:18Kelly Weinersmith?

  Okay, so if we are still trying to think of this as a jelly, then we should be picturing like, that strawberry jelly that has seeds in it. And those seeds are like, the nucleus that the electron was bouncing off of. Is that right?

• 32:30Daniel Whiteson?

  Exactly. And so now, we have like, electrons, and we also have the nucleus, which later on, we discover is made out of protons and neutrons. And so, we're starting to build up our catalog of particles to try to understand like, what is the world made out of? What are these particles? And at this point, the concept of a particle is still, it's a dot in space that we could put labels on. And one of those labels is mass. But then, that was all upended when we discovered the next particle, which is the photon.

• 33:00Kelly Weinersmith?

  Why does it always get more complicated?

• 33:01Daniel Whiteson?

  Photons mess everything up, right?

• 33:04Kelly Weinersmith?

  My goodness.

• 33:05Daniel Whiteson?

  So around the turn of the century, Einstein was thinking about what happens when you shine light on metal. Very bright beam of light on metal, what happens is electrons boil off. This is something people had seen, but not really understood, because they were confusing results about what happened when you made the beam brighter. People expected that if you make the beam brighter, which if light is a wave, means that the EM fields are oscillating with larger amplitude, so more energy, then they thought that electrons should get kicked off with more energy. But instead, what they saw was electrons kicked off with the same energy, but more of them. So instead of having faster moving electrons, you have more electrons at all the same speed. And it was Einstein who figured out what that meant.

• 33:48Daniel Whiteson?

  What it means is that the light you're shining at the metal is not a continuous beam, perfectly smooth, the way Maxwell imagined, but made of chunks, made of bits called photons. And what was happening is that each electron can only absorb one. Like the electron absorbs a photon or it doesn't. If it absorbs a photon, it gets kicked off and it always has that photon's energy. You can't eat two photons or 10 photons. And so when you make the beam brighter, you're shooting more photons, more electrons get to eat a photon. But because it's based out of these chunks, it's not smooth and continuous. It's basically a one-on-one interaction.

• 34:25Kelly Weinersmith?

  You said that was Einstein who helped figure that out, right? So that wasn't that long ago.

• 34:28Daniel Whiteson?

  A hundred years.

• 34:29Kelly Weinersmith?

  Yeah, we went from like nothing to amazing detail in the last hundred years.

• 34:33Daniel Whiteson?

  I know it's really incredible what we've understood. And this is a huge advance because now we're like, oh, wow. Light is also made of little mini servings, right? There's a minimum amount of light. Like you take a flashlight and you start to turn it down and down and down and down. You can't have it be arbitrarily dim. Like there's one setting where it's dark, completely dark. But then there's a minimum brightness. You can't shoot half a photon out of a flashlight or one and a half photons. It's quantized, you know? It's not continuous and smooth. But this is confusing because they were going to call a photon a particle. A minute ago, we said a particle is something that has like mass and charge. Photons don't have mass. So already your mental conception of like, oh, a particle is a little bit of stuff.

• 35:18Daniel Whiteson?

  Well, this photon doesn't have any stuff to it. You know, you can't catch up to a photon and look at it. You can't hold it in your hand. And yet we think of it as a particle. So already a hundred years ago, we had to like back up and broaden our understanding of like, what is a particle if it's not a little bit of stuff, the way Democritus was imagining?

• 35:37Kelly Weinersmith?

  And doesn't it get even more confusing yet? Because then we decide that photons aren't necessarily particles. Sometimes maybe they're waves. And at this point, you're like, I'm majoring in biology.

• 35:49Daniel Whiteson?

  It gets more confusing before it gets more interesting and more clear. But yes, there's definitely a period of confusion there. And I do think that's kind of a filter. Some people hear that and they're like, I need to understand this and learn more. I'm going to become a physicist. And some people were like, I'm going to go study eels. And that's cool because eels can make waves too. You know, they're pretty wiggly.

• 36:08Kelly Weinersmith?

  And electric fields and yeah, yeah.

• 36:11Daniel Whiteson?

  Yeah. And something you said I want to get back to, which is like, Sometimes they're particles. I mean, a photon is always a photon. What is a photon? Is it a particle? Is it a wave? Like, really, it's neither. The way that that new fruit is not a cherry or an apricot. It's not sometimes a kiwi because it has hints of it in your mouth. It's something new and weird. And a photon has behaviors that we sometimes describe in a particle way and behaviors we sometimes describe in a wave-like way. But it's not choosing, now I'm a wave, now I'm a particle. It's always a photon. It's just that none of these descriptions perfectly capture what it is. The way that like, I can't perfectly describe you. I mean, you're a mother, you're a partner, you're a podcaster. None of those things define who you are. You're Kelly, right?

• 36:55Daniel Whiteson?

  And you're sometimes well-described by one of those labels.

• 36:58Kelly Weinersmith?

  Right, yes, right. So this is another one of those problems, like, uh, brains are like a computer, yes, but not entirely. And by putting these labels on it, sometimes it helps you think about it, but also sometimes it makes things more confusing.

• 37:09Daniel Whiteson?

  So let's dig into what it means, though, because the thing people were trying to confront, the thing people were struggling with is like, yeah, Einstein tells us light is made out of these little packets, so we should think of them as like individuals. But also, we had all these experiments showing that light had wave-like behavior. You know, it like interferes with itself. There's diffraction. There's all sorts of stuff that we only usually attribute to waves. And so people have this idea in their mind and they hear a lot about the particle-wave duality, that sometimes you use wave to describe light and sometimes you use particles to describe light. And later on, it got more confusing because we saw that electrons do this too. Like electrons have wave-like behavior. You could take beams of electrons and they will interfere with themselves as if they are waves. But, you know, electron is like the original OG particle.

• 37:54Daniel Whiteson?

  So what's going on here? And there is definitely a way to think about this that's not, sometimes it's a wave and then it switches suddenly to a particle. It's a more quantum mechanical way to think about it, which is rarely like a way to think more clearly about stuff. But, you know, it is the way that we think about it. And the quantum mechanical way to think about this, without getting heavy into the math, is to say that what controls where a particle goes is a mathematical equation that looks like a wave equation. We call it the Schrodinger equation. And it tells us what's likely to happen to a particle. So an electron enters an experiment. The Schrodinger equation tells us, oh, is it likely to go left? Or is it likely to go right? A photon goes through a slit. The Schrodinger equation tells us, is it likely to go here?

• 38:38Daniel Whiteson?

  Is it likely to go there? It's going to land on a screen. The Schrodinger equation tells us what's the probability of something happening. So it's wave like in that an equation that looks a lot like other wave equations, the equations we use to describe oceans and sound and all sorts of wave like behavior, which is amazingly everywhere in the universe. And we can have a whole conversation about like, why does the universe all seem like waves? There's a wavy equation that describes where this stuff is likely to go. But then there's something weird that happens, which is the universe has to go from here. All the things the photon could do. And here's the various probabilities of it going here or there. Then we do the experiment. We want to know the answer. The universe does this thing where it picks one.

• 39:19Daniel Whiteson?

  It's like, all right, of all the possibilities, I'm going to decide this photon goes over there. And this other photon is going to go over here. And this third photon is going to go there. And it's sort of amazing. And it's a process. We fundamentally do not understand how the universe goes from here's a list of probabilities to I'm going to pick one. But this is what people imagine when they think wave like the particle like wave like is like when the universe is still maintaining all the possibilities. Particle like is like, I've looked at it. I've measured it. I see a dot on the screen. So I'm thinking of it as acting like a particle because it's here, has a location. And we think of particles as like it is somewhere. It's a tiny dot in space with labels. So when we force the universe to tell us, where did that photon go? We call it being particle like because we put a location on it.

• 40:04Kelly Weinersmith?

  Okay. And is this the right way to think about all particles? Or do some particles follow this wave function thing and other particles don't?

• 40:15Daniel Whiteson?

  This is the 1930s way to think about all particles. You can use this to describe photons. You can do use it to describe electrons. You can use to describe any particle. This is the Schrodinger equation, and it works really, really well for individual particles. And there's deep fundamental problems with it still. Like, we don't understand when the universe goes from here, all your. Possibilities to actually, we're going to do this one. People call this the wave function collapse or quantum collapse. And philosophically, it makes no sense because it doesn't happen when a photon is measured by a quantum particle. Like a photon can interact with an electron and maintain all of its possibilities. But if a photon hits an eyeball, you see it here or you don't see it there, it collapses.

• 40:56Daniel Whiteson?

  And so really this wave versus particle thing is about maintaining quantum possibilities or collapsing to one. That's really the core of it. And that is not something we understand why that happens, when that happens, if that happens. Huge open question in physics and in philosophy. And what is a particle sort of sits right at the nexus of that. So we've mapped this question of like, what is a particle to, hey, when do quantum wave functions collapse? And do they? But that's not a question we have an answer to. So I'm not sure how helpful it is. But the modern view of what is a particle is actually a little bit different from this sort of 1930s concept of a wave function and the Schrodinger equation.

• 41:36Kelly Weinersmith?

  Well, let's take a break and then we'll get modern.

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• 42:14Speaker 01

  Hi, it's Nora McInerney, host of the Head Start Embracing the Journey podcast. We're back with more honest conversations from people living with chronic migraine, people figuring out how to adapt, advocate, and stay connected to the things that bring them joy while managing their condition. People like romance novelist Britt Middleton.

• 42:33Speaker 06

  It's not often that people can look at you and see that you are living with this. And it felt very important for me to show how people can have these incredibly successful, high pressure, highly visible jobs. But I also wanted to show, because it is a romance, that having the right partner and her love interests actually takes care of her during a migraine attack that happens in the book. And that is also based on my life as somebody.

• 43:01Kelly Weinersmith?

  Who's had an incredible partner to me for the last 14 years.

• 43:05Speaker 01

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• 44:22Speaker 03

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• 44:43Kelly Weinersmith?

  So we are up to the 1930s and now you are going to tell us about our more modern understanding of particles.

• 44:51Daniel Whiteson?

  Yeah, so this idea that particles are these weird quantum objects and where they go is controlled by a wavy equation. But sometimes we can make their measurements and force the universe to tell us where they are in an instant. And they have these properties, mass, sometimes, charge, sometimes, spin, sometimes. That's sort of an old fashioned view. When we started dealing with lots and lots of particles, we discovered, oh, this math is kind of clunky. Like if you have 10 particles or 100 particles, it becomes really awkward to have a Schrodinger equation for each individual one and try to bring it together. The math just becomes impossible. And so people, instead of thinking about like one wave function for each particle, they're like, let's just think about all the particles

• 45:34Daniel Whiteson?

  as if they're wiggling the same field. So instead of imagining like an individual person waving their hand, now imagine like a crowd at a football stadium and they're doing the wave. So add this thing to your brain, which is a field, right? A field in space is just like a set of numbers. I say, over here to my left, the field has a value of seven and over here to my right, field has a value of three or two or whatever. And there are wavy equations that determine what is the value of the field. And so you can have waves in that field, you can have like ripples in that field where like a large value of the field moves through space from here to there. And then we think about particles as those ripples in the field.

• 46:16Daniel Whiteson?

  So we take like individual wave functions, we try to sort of stitch them together into a single field and think about all the particles as wiggles in the same field.

• 46:25Kelly Weinersmith?

  So what assumptions do you have to make to make that transition? Do you have to assume that they don't interact with each other in a way that changes the behavior of the group?

• 46:36Daniel Whiteson?

  Oh, great question. You don't have to assume that because you can have lots of different kinds of fields. You can have some fields where the particles don't interact with each other. For example, photons, photons don't interact with each other. Photons only interact with particles that have electric charge. Like they will be eaten by an electron or a proton can give off a photon, but photons ignore each other. Like they wiggle right past each other, two beams of light cross without touching. Bouncing off each other. Other particles do interact with each other like gluons, for example, gluons bounce off of other gluons, emit other gluons, eat other gluons. It gets very complicated and messy because gluons talk to each other all the time. So you don't have to assume that, but you build that into each field. We have a new mathematical framework that allows us to make

• 47:21Daniel Whiteson?

  different kinds of fields. Some fields are very simple. They're just numbers like the Higgs field. It's just a number in space. Other fields like the electromagnetic field, at every point in space, you have an arrow, you have a direction, you have three numbers, basically. So now imagine like a bunch of arrows filling space. And when a photon is moving through that field, what's happening is those arrows are growing and shrinking, they're changing direction. It's oscillations in these fields that we think about as particles. But we do have to make one important assumption, which has a lot of consequences, which is that every electron is basically the same and every photon is basically the same because they're all part of the same field. It was a question for a long time, like, why does every electron have exactly the same

• 48:05Daniel Whiteson?

  mass and exactly the same charge? Why is every photon zero mass? Why are they all identical, right? And the answer is kind of beautiful. Well, they're all wiggles in the same field. It's not like the universe made a bunch of electrons and it was really good at it. So it was super precise and the electron factory is like high precision engineering. So they're really, you know, balls on perfect. It's because they literally are the same thing. They are just ripples in the same field.

• 48:32Kelly Weinersmith?

  Well, that's convenient because it's easier to think of it as a field, right, than as a particle.

• 48:37Daniel Whiteson?

  Mathematically, it's much easier because if you want to think about like particles being created, oh, that's just energy going into the field. Whereas in the Schrodinger equation, it's like pretty hard to create a particle and add its wave function to your calculations. And the same thing with destroying particles. It's really awkward if you're thinking about it one particle at a time and very natural if you think about it as a group of particles.

• 48:57Kelly Weinersmith?

  The universe threw us a softball. Thanks, universe. Okay, so when I was in high school, I learned about electrons and protons and neutrons. I don't remember hearing about quarks, but you know, since high school, I've learned that protons are made up of quarks. But I think of particles as being the smallest things that make up everything. And so if quarks make up protons, does that mean protons aren't particles? Or are they both particles, but maybe different categories of particles? What's going on here?

• 49:30Daniel Whiteson?

  Oh, that's a great question. So we mostly use these fields to describe fundamental particles, things that we think are not made of anything else. So the photon and the electron, etc. Those particles are wiggles and fields that are just a basic element of space itself. But you can totally use the same math to describe wiggles in other stuff like water in the ocean or sound waves in the air. These are just wave equations and the universe is kind of wavy. And you can also identify particles of those fields, quanta of those fields. A photon, for example, is a packet of sound, the way a photon is a packet of light. The math is the same.

• 50:12Daniel Whiteson?

  It's just what's wiggling is not fundamental universe stuff, whatever that is, but something else, water or air or plasma or whatever. So we distinguish these things from particles by calling them quasi-particles. But the point is that the math still works. All right, so to your question about the proton, we know the proton is not a fundamental particle. It's made of quarks. So there's no proton field, right? Well, actually, if you zoom out far enough so you can't see the inside of the proton, it kind of acts like a particle that moves around the universe the way a particle does. And you can pretend that there is a proton field. You can write it down mathematically and use it to describe the motion of the proton as a particle.

• 50:57Daniel Whiteson?

  And the proton field is like an approximate description of the quark fields dancing together. The way they interact together makes it seem like there is a proton field. And until you get enough energy that breaks that Proton apart, it all works just fine. And the same, of course, might be true of the electron. We think that there is an electron field, a fundamental part of space. But if the electron is just made of other little particles, which are the true fundamental particles, then the electron field is just an approximate description of those fields dancing together.

• 51:28Kelly Weinersmith?

  All right. So where do you go from there?

• 51:30Daniel Whiteson?

  So in this picture, particles are not little bits of stuff, right? You have to give up that whole idea, that whole mental picture we've had since Democritus that said, the universe is made of particles and particles are little bits of stuff. Now we say, well, particles are not little bits of stuff. They're wiggles in these fields. And that means something really deep. It means that the universe is not made of particles. It's made of fields. Particles are just something that happens to fields. There's just something fields can do. You know, it's like discovering, okay, ice cream exists in the world, but actually it's not fundamental. The universe is not made of ice cream. There's times when you don't have ice cream. There's whole periods in the universe when there was no ice cream.

• 52:12Kelly Weinersmith?

  No.

• 52:14Daniel Whiteson?

  It's hard to imagine. There was a moment when somebody invented ice cream for the first time, right? And the universe was filled with light.

• 52:21Kelly Weinersmith?

  Yes.

• 52:21Daniel Whiteson?

  What it means that we've gone one level deeper, though, right? This is the whole goal is like, what really is at the foundation? What is everything made out of? And this takes quite a left turn. It says, yeah, the universe is not built of little bits. Those bits are actually just ripples in these fields that fill the universe. And I want people to really have an accurate visual image of what these fields are, because people think about, okay, a particle is a ripple in the field or it's an excitation in the field. And you should understand that a field really is a wavy kind of thing. You can do the same wavy kind of things that other fields can do. You know, like imagine a guitar string. What does a guitar string do when you pluck it? You pull it back. And so now it's like you're stretching the string, right? And we say in physics now has a lot of potential energy

• 53:06Daniel Whiteson?

  because a lot of tension in there really wants to go back to its relaxed position. What happens when you relax it? What happens when you let it go? Well, it flies back to that relaxed position, but now it's moving really fast. So now it has a lot of speed, right? A lot of kinetic energy, so it doesn't actually stop there when it gets back to the relaxed position. It keeps going and it bends the other way and oscillates back and forth and back and forth and back and forth. It sloshes back and forth between potential energy and kinetic energy. That's what a wave equation, that's a wave-like phenomenon, something that sloshes back and forth. That's what fields are doing. Fields, you can think of them as these numbers in space, but those numbers are sloshing back and forth. The field itself has potential

• 53:47Daniel Whiteson?

  energy and kinetic energy. The changing of those numbers has a speed to it. And when we solve the wave equations for fields, what is fundamentally quantum field theory, the bedrock of modern particle physics, that's what the solutions look like. Like the Higgs field is oscillating. When we say a photon is an oscillation in the electromagnetic field, we mean the values of the field, those numbers in space, those arrows, they're moving, they're wiggling, they're sloshing around.

• 54:14Kelly Weinersmith?

  So when I was in high school, we got the like plum pudding model. So yes, I do think now about particles as like a raisin embedded in something and not as like a wave function. If I were in high school right now, would I be taught something more like what you just said? How long have we known about this stuff? Why does this feel new? Is what I'm asking? Is it new or did I forget?

• 54:37Daniel Whiteson?

  It's a great time to ask me this question because my daughter, who's taking high school chemistry right now, is learning about this stuff and asking me questions about it. So I'm getting like a front row seat to how are people taught about the nature of matter in high school? And yeah, they're taught about the plum pudding model. Though just for the record, the plum pudding model is not a modern conception. It was like disproved by Rutherford, right? People thought, maybe the universe is filled with this jelly of positive stuff. It sounds tasty, but it's not the way that we understand it. It's in contrast to having like a hard dense nucleus at the core. So the plum pudding model, they teach it to them and then they throw it out. But they don't really go very deep into like the quantum mechanics of it. Even in AP chemistry, I discovered, they don't really talk about

• 55:22Daniel Whiteson?

  this stuff. And they certainly don't talk about particle physics in AP physics. So in high school, you don't really get a whole lot of this modern stuff. I teach. Modern physics at the college level, and that's the first time we really give people an understanding of the 1930s concept of what is a particle and how does quantum mechanics work. And then we don't show them quantum fields until like graduate school. So I didn't learn about quantum fields until I was in like 18th grade. So you know, this is not the kind of stuff that percolates mostly into high school. Maybe fortunately, maybe unfortunately, I would love to have some of these ideas introduced earlier.

• 55:56Kelly Weinersmith?

  So you think if you talked to just about any recent graduate of high school, they're probably still thinking of electrons as particles that stay in one spot?

• 56:04Daniel Whiteson?

  Tiny little dots orbiting the nucleus. You know, electrons don't orbit. They don't have specific locations. They can't be in one spot and have a specific velocity. You can measure them here. You can measure them there, but they're weird quantum objects. They don't go from here to there. They don't obey all the intuitive rules that you expect things to have specific locations to do.

• 56:26Kelly Weinersmith?

  So we can all feel good about our advanced physics knowledge now?

• 56:29Daniel Whiteson?

  Yes, exactly. You've pushed well beyond high school and even college physics. And you know, I have to underscore how powerful this quantum field theory approach is to say that all particles are just ripples and fields and the universe fundamentally is made of these fields. All of space is filled with many kinds of fields. You have one for the electron, one for the muon, one for the up quark, one for the down quark. We have more than a dozen fields that fill space. This is a really powerful way to think about the universe. We see patterns in these fields, how energy flows from one to the other, their symmetries that they observe. It's allowed us to make really powerful, very accurate calculations of all sorts of stuff that we see happening in particle experiments. And so it's really beautiful and really crisp

• 57:13Daniel Whiteson?

  and really clear. And I think that most particle physicists, this is what they think about, or most theoretical physicists imagine the universe as filled with fields and particles as just ripples in them. But of course, it's a field filled with controversy. And so not everybody agrees with that view. There are lots of people who have a very different concept of what a particle is and fundamentally how it all works at the bottom level.

• 57:35Kelly Weinersmith?

  So to back up real quick, this fields theory has produced loads of testable hypotheses that have been tested and panned out. But there are still some people who think maybe something else is going on that explains these results. And what?

• 57:52Kelly Weinersmith?

  Are they proposing this happening then?

• 57:53Daniel Whiteson?

  They suggest the fields are a fiction, that the fields don't really exist, that the fields are basically just a calculational tool we use in our minds to explain what we see. Because in the end, you can't observe a field. You can't directly see a field. It's always an intermediate thing. Like what you can see are particles. You see those little dots on your screen, or you see the electron deflected in your cathode ray. It's always "particle-like," I'm doing air quotes, when we see it. And particles are what we observe. They're what we interact with. Yes, we can use fields to explain them, and yes, we can think about fields as being out there. But it's hard to argue philosophically that we know fields are real in some way other than we can use them to calculate these experiments.

• 58:38Daniel Whiteson?

  You can't like really directly see them. And lots of famous physicists like Nima Arkani-Hamed, one of the maybe most brilliant modern particle physicists, calls them a convenient fiction.

• 58:49Kelly Weinersmith?

  Huh. So would someone like Nima then argue it's all just particles? Like the field thing is throwing us off track. We were on track with the particles and we just gotta stick with thinking about particles and figure out a way to measure at that level instead?

• 59:04Daniel Whiteson?

  Yeah. And here I want to take the opportunity to disentangle something you hear about a lot in popular science. People probably hear, oh, particles are ripples in a field. But they also hear this other story, like what happens when two electrons repel each other? Oh, they exchange a photon. They're passing a photon back and forth, right? What you're doing there is rejecting the field picture. The field picture of what happens when electrons push on each other is an electron makes a field around it, the electromagnetic field, right? And that field pushes on the other electron. That's the field picture. People who don't believe in fields, they're like, just explain it all in terms of particles. You don't need the field. What happens when an electron pushes on another electron is it throws a photon at the other one.

• 59:46Daniel Whiteson?

  And so you can either explain everything in terms of particles that are pushed by fields, or you can explain it just in terms of particles and say, you don't need fields. Just go particles all the way down. There are particles we observe and they push on each other by passing other particles between themselves. So you can basically replace the fields with an infinite number of particles doing all the pushing and pulling and all the other stuff that some people say fields are doing. And the frustrating slash confusing slash amazing thing is that you do the calculations, you get the same answer. So is it particles? Is it fields? We can't tell the difference because the two theories mathematically are equivalent. It's like either you can imagine these fields which fill space, which are beautiful and elegant, but kind of weird, like what are they?

• 1:00:30Daniel Whiteson?

  Or you can say, I'm going to replace those fields by a bunch of particles flying around doing that same work.

• 1:00:36Kelly Weinersmith?

  And are you a fields guy?

• 1:00:40Daniel Whiteson?

  I was a fields guy until I read this book about whether science can be done without math. You know, people wonder like, is math invented? Or is it something in our minds? And there's a guy who developed an alternative theory of gravity that doesn't use any math, no numbers at all. It's called science without numbers. And it's really weird. It's very alien. You read it and you're like, what was this guy smoking? And where can I get some? But he philosophically pulls it off. He shows that you don't need to have fields essentially. And the crucial insight in that book is to get rid of fields because fields are like numbers in space. So he divorces physics from mathematics by ditching fields. My favorite part of this story, the guy's last name, Fields.

• 1:01:23Daniel Whiteson?

  So Professor Fields gets rid of fields. The field fieldless theory of physics. There's lots of jokes you could make there, but it made me wonder, you know, like are fields just something we think about or are they actually out there? When aliens come and talk to us about their theory of physics, will they have fields in it? Or will they have schmields or something totally different?

• 1:01:43Kelly Weinersmith?

  So have you dodged my question? Or are you saying that you're a particle person?

• 1:01:49Daniel Whiteson?

  I'm saying, I don't know. I used to be a fields person, but now I teach the controversy.

• 1:01:54Kelly Weinersmith?

  Got it. Okay. So when you first said that there were people who reject fields. I thought that was going to get us into string theory. Are we going to get to string theory too? There's three options. So there's particles, fields and strings. Is that right?

• 1:02:07Daniel Whiteson?

  There's more than three options, unfortunately.

• 1:02:09Kelly Weinersmith?

  Okay.

• 1:02:10Daniel Whiteson?

  So there's lots of directions to go here. People also wonder like, well, what are these fields? Are fields the bedrock, the truth of the universe at the firmament? Is that the thing that has to exist? And it's sort of unsatisfactory because like, well, why are there all these different fields? Why do we have the electron and the muon, which is like a weird, heavy version of the electron? Why are there these obvious patterns among the fields that we can't explain? And one explanation for that are strings to say, well, none of these things are what's at the bedrock. Underneath it all is something else. And strings are this idea that the universe is not made out of fields. Instead, these one dimensional bits of matter that can do wavy like stuff. They can wiggle and they can dance and they can wiggle in various ways.

• 1:02:55Daniel Whiteson?

  And if you're zoomed out far enough, so you can't see the actual string bits themselves. When they wiggle one way, it looks like an electron field. And when they wiggle another way, it looks like a muon field. And when it wiggle a third way, it looks like a photon. And so all these fields are actually just different wiggles in these strings. This is another beautiful bit of mathematics that nobody's proven to be true or not, but might represent what's going on underneath all of this. Right? So maybe particles are ripples in fields, which are just wiggles in strings.

• 1:03:27Kelly Weinersmith?

  So string theory is still a popular contender. I thought maybe string theory was waning, but I'm, you know, not in this field. What's the current state of string theory?

• 1:03:37Daniel Whiteson?

  String theory was very popular in the 90s. It seemed very exciting. People discovered this math and could do all sorts of fun stuff with it. And they've done a lot of fun stuff, but they haven't been able to prove that it's true because they talk about the mathematics of the strings, but nobody can see these strings. The strings are too small. In order to see the strings themselves, you'd need like a collider the size of the solar system. And we don't have the funds for that. And so until they make a prediction that we can actually test, it's like, oh, string theory, if it's true, we should be able to see this thing. Then we Don't know if it's just mathematics or if it's actually a description of the universe. And so there's been a lot of people who are negative about string theory for that reason. I still think it's exciting, but there are other ideas out there about, you know, what the universe could be made out of.

• 1:04:20Kelly Weinersmith?

  What else?

• 1:04:21Daniel Whiteson?

  As you were saying earlier, we tend to think about the brain as made out of whatever is the latest technology. In the same way, we try to think about the universe that way, like the advent of quantum computing makes us think about qubits and information. And there's a whole line of argument that I think we should talk about probably on another episode, about whether the whole universe is just a quantum computer. And particles are like patterns in the flow of information in this quantum computer. There are folks who do these experiments that discover that if you build a spacetime from entangled qubits, that these patterns naturally arise, which have properties that align well with the particles that we see. This is all really very speculative stuff, but it's sort of the forefront of current research.

• 1:05:06Daniel Whiteson?

  People wondering like what's underneath all this stuff. Maybe it really is even different than Democritus imagined, or Schrodinger, or even Feynman.

• 1:05:14Kelly Weinersmith?

  What is a qubit?

• 1:05:15Daniel Whiteson?

  A qubit is a quantum analogy to a classical bit, like in your computer. A bit is something that can be zero or one. It's like the minimum piece of information you can have. It's boiled down to just two options, like a switch you can flip. And a normal bit is in one state, but a quantum bit has a probability to be in one state or in the other. It's not necessarily in one or the other. So it's a qubit is a quantum bit. And people wonder if fundamentally the universe is made out of qubits that are somehow woven together to make space and time and our reality. But we'll dig into that in a whole other episode.

• 1:05:50Kelly Weinersmith?

  Awesome. All right. So if we tomorrow were to find out which one of these explanations was correct.

• 1:05:59Kelly Weinersmith?

  What would that change? So that would be satisfying. But where could we go from there that would be even cooler? Like, what doors would that open up for us?

• 1:06:07Daniel Whiteson?

  Yeah, wow. Awesome question. You're basically asking like, why do we care about any of this? What does it mean for us? For me, it's like really deeply important to understand what is the nature of the universe we're in? You know, what is it made out of? If you told me the universe starts from these conditions and everything else falls from that, like to have a universe, you have to have space and time and this little bit of stuff. And then everything else, all the complexity, the blueberries, the kittens, the lava, the podcast, all of that comes from how that stuff is arranged and interacts. And that's cool. I want to know what is the most fundamental thing? Because that tells me something deep about the nature of the universe. If it's this, then the universe is that way in some deep way. If it's that, the universe is another way in some deep way.

• 1:06:52Daniel Whiteson?

  I just fundamentally want to know. It doesn't change how you drink your coffee. It doesn't change how you treat people. It doesn't change what investments you should make, but it changes what it means to be alive in this universe in a really important way. To me, it's very uncomfortable that we don't know the answer to the basic question of like, what is the fundamental building block of the universe we live in? It's like being born into a jail and not knowing who built it or what's on the outside. It's like, I want to break out of this ignorance.

• 1:07:21Kelly Weinersmith?

  I found myself personally wanting the answer to be that everything is a field and is sort of connected in a way that feels like, I don't know, maybe sort of like kumbaya, sit around a fire sort of feeling, but I like that stuff. So anyway, I guess my gut wants that to be the answer. But yes, I think it would be good for us to know the answer to this very fundamental question.

• 1:07:40Daniel Whiteson?

  And I suspect the answer is none of these. And something even weirder, that's going to be so difficult for us to understand, it's going to be a stretch to even explain in terms of our intuitive language of concepts. You know, we're going to have to use kiwis and fields and particles and strings and all sorts of other stuff to try to wrap our minds around the way the universe actually works, which has no guarantee that it's even understandable to us.

• 1:08:04Kelly Weinersmith?

  So people are going to be like, Democratists thought it was sour because it was like little knives. And then Daniel and Kelly thought it was like strings and fields. What idiots. So, you know, who knows what they'll think in 100 or so years?

• 1:08:16Daniel Whiteson?

  I hope they're laughing at us in 100 years. That would be awesome.

• 1:08:19Kelly Weinersmith?

  Yeah, progress is good.

• 1:08:20Daniel Whiteson?

  All right. Well, thanks, everybody, for taking this journey with us from the ancient misunderstanding of what matter was to our modern misunderstanding of what matter is. And we hope to continue this journey and to slowly chisel away towards some actual solid understanding.

• 1:08:35Kelly Weinersmith?

  Have a good week, everyone.

• 1:08:43Kelly Weinersmith?

  Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you.

• 1:08:48Daniel Whiteson?

  We really would. We want to know what questions you have about this extraordinary universe.

• 1:08:54Kelly Weinersmith?

  We want to know your thoughts on recent shows, suggestions for future shows. If you contact us, we will get back to you.

• 1:09:01Daniel Whiteson?

  We really mean it. We answer every message. Email us at [email protected].

• 1:09:08Kelly Weinersmith?

  Or you can find us on social media. We have accounts on X, Instagram, Blue Sky, and on all of those platforms, you can find us at D and K Universe.

• 1:09:17Daniel Whiteson?

  Don't be shy. Write to us.

• 1:09:21Speaker 06

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• 1:09:52Speaker 03

  Hey, I'm Niall Rogers. This fall, I'll be driving across the country, meeting some of today's coolest and most fascinating artists. We'll explore the stories before the moments that changed everything. Because every musician remembers the moment where it all began. Experience Before the Moment, a Lincoln original series on the iHeartRadio app, YouTube, or wherever you get your podcasts.

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