Speaker 1: What is everything made out of? That seems like a
Speaker 1: simple question, and it also seems like a reasonable question.
Speaker 1: I'd like to know what I'm made out of, what
Speaker 1: my food is made out of, what kittens are made
Speaker 1: out of, what lava is made out of. It's also
Speaker 1: an ancient question, I think, one that people have been
Speaker 1: asking since people have been asking any questions. The Greeks,
Speaker 1: famous for asking questions in their sexy robes, thought that
Speaker 1: everything was made of earth, air, water, and fire. And
Speaker 1: modern science, of course, has made a lot of progress
Speaker 1: here and uncovered some pretty weird and kind of shocking
Speaker 1: news about what everything is made out of. What seems
Speaker 1: like smooth and continuous matter is actually made up of
Speaker 1: tiny little bits that are woven together into some extremely
Speaker 1: fine mesh. And we are all made of the same
Speaker 1: basic bits, some together to make me or you, or
Speaker 1: kittens or lava. The world is of particles. But our
Speaker 1: curiosity doesn't just end because we have that answer. We
Speaker 1: want to know what are these basic bits? How do
Speaker 1: we think about them? What mental pictures should we have
Speaker 1: in our mind? Are they tiny dots of stuff or
Speaker 1: rippling waves or some other concept that's too alien to
Speaker 1: even imagine. And what does it tell us about the
Speaker 1: universe that these are its basic building blocks?
Speaker 2: Or are they? So?
Speaker 1: Today, on Daniel and Kelly's Extraordinary Universe, we'll be tackling
Speaker 1: the basic yet confusing, the simple yet deep, the important
Speaker 1: but impossible question what is a particle?
Speaker 3: Welcome to Daniel and Kelly's Extraordinary Universe. I'm Kelly Wiener Smith.
Speaker 3: I'm a parasitologist and I'm particularly excited to be here today.
Speaker 3: But it might have been really cute if I had
Speaker 3: been able to pull it off, but I didn't.
Speaker 2: Hi, I'm Daniel.
Speaker 1: I'm a particle physicist, which means I probably should know
Speaker 1: what a particle is.
Speaker 3: Well, we've got the right expert on the show today.
Speaker 3: So Daniel, here's what I'm wondering. So you've told me
Speaker 3: that you go to CERN in Switzerland to do your research.
Speaker 3: Why doesn't the United States have the biggest particle collider?
Speaker 1: Oh my gosh. Why you are putting your foot in
Speaker 1: a sensitive spot right there. You know, for many years
Speaker 1: it was a race between the Europeans and the Americans.
Speaker 1: So before CERN had the most powerful collider.
Speaker 2: We had one.
Speaker 1: It was outside of Chicago at Fermi Lab. It's called
Speaker 1: the Tevatron. I did my PhD there. I had one
Speaker 1: child born near that collider, and then my next child
Speaker 1: born near Cerns. You know, not a kid at each collider.
Speaker 3: Basically, wait, one of your kids was born abroad?
Speaker 1: Yeah, my daughter Hazel was born in Switzerland, very close
Speaker 1: to cern That's cool.
Speaker 3: Did you have to not pay because you were in
Speaker 3: Europe and they just do healthcare there or what was
Speaker 3: that like?
Speaker 2: No?
Speaker 1: Actually they told us that when we showed up for
Speaker 1: the delivery, we had to bring fifty thousand Swiss fronc
Speaker 1: in cash if we didn't have local insurance.
Speaker 3: WHOA.
Speaker 2: So yeah, that was going to be an issue.
Speaker 1: But then we discovered this a law in Switzerland that
Speaker 1: if you're working there, which my wife was, they have
Speaker 1: to insure you. So even though she had all sorts
Speaker 1: of crazy pre existing conditions, we could buy insurance for
Speaker 1: like one hundred franc and then we didn't have to
Speaker 1: pay for anything. So it was amazing.
Speaker 3: Actually nice, Okay, that's good.
Speaker 1: And the insurance company even offered to retroactively cover a
Speaker 1: bunch of appointments to where we hadn't yet had insurance.
Speaker 1: It was very different experience than American insurance.
Speaker 3: Yeah, that's incredible. I'm going to get depressed if we
Speaker 3: stay on this topic too long. Let's go back to
Speaker 3: particle colliders. Okay, so you have had each of your
Speaker 3: children near very large particle colliders. Why isn't the biggest
Speaker 3: one in the US.
Speaker 1: Well, they planned to build the biggest one in the US,
Speaker 1: the Superconducting super Collider in Waxahachie, Texas, and they started
Speaker 1: building it, and they spend billions of dollars digging a hole.
Speaker 2: But then the director of CERN.
Speaker 1: At the time came and testified before Congress saying it
Speaker 1: was a big waste of money because CERN was building
Speaker 1: one that was going to be bigger and better and
Speaker 1: they should just cancel it. And Congress, for all sorts
Speaker 1: of complicated political reasons, listen to him and canceled the
Speaker 1: American Superconnecting super Collider. And since then the lead has
Speaker 1: been in Europe and probably will for a while. And
Speaker 1: the US particle physics communities mostly focused on things like
Speaker 1: neutrinos and stuff like that. So these days, if you
Speaker 1: want to do cutting edge, high energy particle physics at colliders,
Speaker 1: you got to go to Switzerland, which, hey, it's not
Speaker 1: too bad.
Speaker 2: The chocolate's amazing, no doubt.
Speaker 3: You know what. Actually, I'm gonna go out on a
Speaker 3: limb here and say I'm not a huge fantas with chocolate.
Speaker 2: Yeah, I know you prefer Belgian I do.
Speaker 3: Yeah, there I said it. So every once in a
Speaker 3: while I'll hear about like astronomy students who want to
Speaker 3: get time on a telescope, but the telescope's all booked
Speaker 3: up and it takes forever. Does cern have enough time
Speaker 3: for everyone? So like, when that guy came to the
Speaker 3: US and tanked our program, did he know he was
Speaker 3: going to have enough time time for all of our
Speaker 3: scientists to come over and do their work.
Speaker 1: Yeah, that's a great question, And people often ask me
Speaker 1: about that, like what's it like to set up your
Speaker 1: experiment at the collider? But the reality is very different.
Speaker 1: Telescopes and colliders don't work the same way. A telescope
Speaker 1: you have to point at the thing you want to
Speaker 1: look at. So you write a proposal to say, let's
Speaker 1: point our amazing telescope at this one star I want
Speaker 1: to study, and then it's not pointing at any other stars.
Speaker 2: But a particle collider is very general.
Speaker 1: It always just does the same thing smashes the particles
Speaker 1: together and you take pictures of it, and then afterwards
Speaker 1: you analyze it. So everybody who uses the collider uses
Speaker 1: the same data. They're just looking for different kinds of particles.
Speaker 1: We don't have to point the collider at certain things.
Speaker 1: We don't swap out what we're using to take pictures.
Speaker 1: Every few years we turn the thing off, revamp it,
Speaker 1: build a new detector that's better, faster, higher resolution or whatever,
Speaker 1: and then we make it as general as possible so
Speaker 1: everybody can use it so you don't have to swap
Speaker 1: it out every day or every experiment. Everybody uses the
Speaker 1: same data set, which makes it kind of crazy because
Speaker 1: everybody's looking for discoveries in the set SA data set
Speaker 1: at the same time, So you could get scooped by
Speaker 1: any of your thousands of colleagues Yanks.
Speaker 3: So do you actually need to be there in person
Speaker 3: or if it's just data, they can make that available
Speaker 3: anywhere right.
Speaker 1: CERN has long been at the forefront of the Internet.
Speaker 1: We invented the web at CERN, for example, and we
Speaker 1: have excellent cloud computing and so we transfer that data
Speaker 1: all around the world. We've collaborated from Japan to Singapore
Speaker 1: to South Africa, to the northern tip of Canada, all
Speaker 1: over the world. People analyze this data. Absolutely, you don't
Speaker 1: have to go. I go frequently because I have students
Speaker 1: there and postdocs are like on site building stuff and
Speaker 1: helping keep it run. But technically you don't have to
Speaker 1: to look at the data.
Speaker 3: Cool. I mean, that's good and bad. I feel like
Speaker 3: ecologists like we want to study exotic animals, but partly
Speaker 3: because we want to go there, And I imagine it's
Speaker 3: sort of the same with cern, like it'd be nice
Speaker 3: to go to Switzerland. But I guess the more important
Speaker 3: thing is answering the question.
Speaker 1: It is nice to go to Switzerland, but then again,
Speaker 1: it's also nice to be able to do science without
Speaker 1: having thousands of dollars to go to Switzerland, which means
Speaker 1: smaller groups and not such institutions, for example, could also participate.
Speaker 1: So it makes it a little bit more democratic, you know.
Speaker 3: Nice. That's awesome. Okay, So the whole point of having
Speaker 3: a large particle collider is so that you can figure
Speaker 3: out what those particles are made of, Is that right?
Speaker 1: The whole point of having a particle collider is that
Speaker 1: you can say you're smashing particles together and nearly the
Speaker 1: speed of light, which sounds pretty awesome at parties.
Speaker 3: It does, yeah, kind of like jousting for particles.
Speaker 2: Yeah.
Speaker 1: Well, particle colliders, I think, sort of have two different purposes.
Speaker 1: One is like, hey, let's take stuff and see what's
Speaker 1: inside it. Let's start with something familiar, you know, like
Speaker 1: the proton, and smash it open and see what it's
Speaker 1: made out of. And that's a continuation of like a
Speaker 1: long glorious tradition of taking the stuff around us a
Speaker 1: part to understand what it's made out of. You know,
Speaker 1: I'm made of molecules, which are made of atoms which
Speaker 1: have a nucleus and electron, and the nucleus is made
Speaker 1: of protons. Let's go inside the proton. So that's definitely worthwhile.
Speaker 2: And we do that.
Speaker 1: But colliders can actually do something else, even more powerful,
Speaker 1: which kind of sounds like magic, which is that they
Speaker 1: can convert the mass of those protons into energy and
Speaker 1: then back into mass, and so what can come out
Speaker 1: of the collision is not just a rearrangement of what
Speaker 1: went in. It's not like chemistry where you're like this
Speaker 1: hydrogen moved from this atom to over there, and now
Speaker 1: you have a different kind of compound. You can annihilate
Speaker 1: these things, and then you basically have like a budget
Speaker 1: to make anything. And the stuff that comes out of
Speaker 1: the collision doesn't just have to be like a refashioned,
Speaker 1: rearranged version of what went in. You can have entirely
Speaker 1: new matter. It really is alchemy. So like protons go in,
Speaker 1: you have this intermediate state of frothing energy, and then
Speaker 1: you can make whatever the universe can make, dark matter, muons,
Speaker 1: all sorts of other stuff. You're not just rearranging the protons.
Speaker 3: There's got to be some rules right for what you
Speaker 3: can make.
Speaker 1: Yes, exactly, that's the whole premise of particle physics. There
Speaker 1: are rules, there are patterns. Quantum mechanics tells us what's
Speaker 1: likely to happen in certain collisions. We look at those patterns,
Speaker 1: we notice, oh, this typically happens, typically shoots out at
Speaker 1: those angles.
Speaker 2: What are the rules that control this?
Speaker 1: Absolutely there are rules, but fundamentally it's random. Right, Like
Speaker 1: you do the same collision twice, you get two different answers.
Speaker 1: Because it's quantum mechanical, it's not determined by the initial conditions.
Speaker 1: So it's really a very powerful way to explore the
Speaker 1: universe because you don't have to know what's out there
Speaker 1: in order to discover it. You smash protons together often enough,
Speaker 1: eventually everything the universe can do, it will do, and
Speaker 1: you get to take pictures of it.
Speaker 3: Wow.
Speaker 1: It's like, imagine if you could build a box and
Speaker 1: every kind of creature that could exist on Earth would
Speaker 1: randomly cycle through that box. You could just sit there
Speaker 1: and watch and be like, oh, wow, I didn't know
Speaker 1: that existed. Oh look at those things.
Speaker 2: What are those? You know?
Speaker 1: That would be pretty powerful. That's basically what we can
Speaker 1: do with particle physics.
Speaker 3: Now you have my attention. Although that box, I guess,
Speaker 3: could mostly be showing me like different species of bacteria,
Speaker 3: which would be a bomber. You could show me different
Speaker 3: speceis of bugs, that would be great.
Speaker 1: Yeah, it'd be mostly beetles. You're like, wow, it's basically
Speaker 1: a beetle box.
Speaker 2: Right.
Speaker 3: So there is that famous saying that like God is
Speaker 3: inordinately fond of beetles, because there's this thought that beetles
Speaker 3: are the most common species group on the planet, but
Speaker 3: actually quite often those beetles are infected by more than
Speaker 3: one species of hymenopter and wasp, and so we think
Speaker 3: there might actually be more wasp species on the planet
Speaker 3: than there are beetles based on that observation.
Speaker 1: And probably those wasps are infected by viruses, so they're
Speaker 1: more viruses than wasps. Yes, and those viruses are made
Speaker 1: of particles, and boom a boom, we're back to the
Speaker 1: topic of the episode.
Speaker 3: Well, what makes up a particle, Daniel exactly?
Speaker 1: So we smash particles together, we look at what's inside them,
Speaker 1: we annihilate them to make new kinds of particles. We
Speaker 1: have this idea that particles are what everything is made
Speaker 1: out of. But I struggle, still after decades in this field,
Speaker 1: to understand this basic question what is a particle?
Speaker 2: So I really want to explain to.
Speaker 1: People what we do know and what we still don't
Speaker 1: know about this very basic concept that everybody talks about
Speaker 1: all the time.
Speaker 3: Well, first, let's hear what our listeners think. And if
Speaker 3: you would like to be a listener who tells us
Speaker 3: what you think, send us an email at questions at
Speaker 3: Daniel and Kelly dot org and we will get you
Speaker 3: in the loop and send you a question from time
Speaker 3: to time and you can send us your answers. So
Speaker 3: let's see hear how folks answer the question what is
Speaker 3: a particle?
Speaker 2: A particle is a thing that interacts with other things.
Speaker 1: A particle is really just an excitation in a field.
Speaker 2: A particle is a defined portion of something, something that
Speaker 2: is infinitesanly small to us.
Speaker 1: It's the smallest unit of energy or mass.
Speaker 3: I think that particles are the excitement of different friends,
Speaker 3: spatial spots, and interaction.
Speaker 2: A particle could be very small vibrating field. A mass
Speaker 2: or non mess object.
Speaker 1: Exists within what we would perceive as matter.
Speaker 4: A particle is a sub microscopic kernel of energy and
Speaker 4: or matter. A particle is an excitation of a field.
Speaker 4: I do know that particles aren't just tiny bits of matter.
Speaker 4: I've heard that there fields, or strings, or some other
Speaker 4: impossible to understand little bits of the universe.
Speaker 2: Particle is a ripple and a quantum field. Particle is
Speaker 2: the name we give to the smallest discrete, quantum little
Speaker 2: bits that we know of and haven't been able to
Speaker 2: break up.
Speaker 3: Further yet, an expression of a field where the chances
Speaker 3: of that occurrence happening is the greatest. There. The more
Speaker 3: think about, the bigger this rabbit warren is going.
Speaker 1: I think these answers perfectly encapsulate this episode. I mean, really,
Speaker 1: it's an excellent snapshot because a lot of what people
Speaker 1: have said in here is correct. But also there's a
Speaker 1: huge list of conflicting answers, right, you know, is it
Speaker 1: the smallest bit of stuff? Is it just something in
Speaker 1: space time? Is it actually an excitation of a field?
Speaker 1: You know, there's so many conflicting concepts for what a particle.
Speaker 3: Is, and is this one of those topics where at
Speaker 3: the end the answer is going to be we really
Speaker 3: have no idea, could be all of these things? Or
Speaker 3: is this a topic we're at the end. We're going
Speaker 3: to have a pretty clear answer.
Speaker 2: At the end.
Speaker 1: We're going to have a pretty clear answer, but not
Speaker 1: at the end of this episode, at the end of
Speaker 1: this journey, which might be in ten or one hundred
Speaker 1: years unfortunately. Okay, I mean we're going to get somewhere.
Speaker 1: Today we have a pretty crisp clear view of what
Speaker 1: a particle is mathematically, but we also know why that's
Speaker 1: not really satisfactory, and there's lots of big open questions
Speaker 1: about what that really means. So it's not like all
Speaker 1: particle physics is a scam because we don't know what
Speaker 1: a particle is. We have a working definition, but we
Speaker 1: also know that it's incomplete, just like most of science.
Speaker 3: Right, Oh yeah, amen, All right, well, so let's start
Speaker 3: with the historical perspective. Bring me back to the beginning.
Speaker 3: When did we start thinking about this question?
Speaker 1: Yeah, I think it's important to trace the origin of
Speaker 1: this historically because it still shapes how we think about
Speaker 1: the universe. And you know, whenever you ask a big
Speaker 1: question about science, you got to think about like what
Speaker 1: kind of answer you're looking for.
Speaker 2: And in science, even though.
Speaker 1: We try to be like mathematical and open minded and
Speaker 1: let the data tell us what the universe is saying,
Speaker 1: we still need to understand that data. We still need
Speaker 1: to interpret it. We still need to cogitate on it
Speaker 1: in a way that makes sense to us. And we're
Speaker 1: sort of limited in our mental intuitive language. We can't
Speaker 1: really grapple with things that we've never experienced, that are
Speaker 1: completely alien to us. We tend to translate the unfamiliar
Speaker 1: into the familiar.
Speaker 4: You know.
Speaker 1: My favorite example of this is like what happens when
Speaker 1: you drink a wine or you taste a new fruit
Speaker 1: and you're like, oh, this fruit tastes kind of like
Speaker 1: a cherry and kind of like an apricot and whatever,
Speaker 1: and a little bit like a kiwi. You're explaining something
Speaker 1: new in terms of something you already know, and that
Speaker 1: makes a lot of sense also what we do in science,
Speaker 1: and so it's important like dig into like what are
Speaker 1: the sort of basic mental building blocks we're using to
Speaker 1: understand this stuff.
Speaker 3: I think one of my favorite examples of that is
Speaker 3: the brain being compared to whatever technology is hot and
Speaker 3: new at the time. You know, like your brain is
Speaker 3: like a clock, your brain is like a computer. And
Speaker 3: some of those analogies work in some ways, but you know,
Speaker 3: having an analogy like that sometimes limits the way you
Speaker 3: actually attack a problem.
Speaker 1: Yeah, but it also is what allows you to understand it, right,
Speaker 1: So in the end, it's sort of how we understand everything. Yeah,
Speaker 1: And that's why it's useful to go back to like
Speaker 1: fifth century BC and talk about Democratus and his buddy Lucepis,
Speaker 1: because these folks were thinking about, hey, what is the
Speaker 1: universe made out of? And they came up with this concept,
Speaker 1: or they're credited with this concept of what seems like
Speaker 1: smooth and continuous matter, you know, water, seems smooth and continuous.
Speaker 1: Air seems smooth is actually made of tiny little bits
Speaker 1: of stuff. This is a big idea, right, This is
Speaker 1: a huge concept. It is like pulling back the veil
Speaker 1: on the world and saying the world isn't the way
Speaker 1: that it seems. It's actually quite different. You know, it
Speaker 1: has like a resolution. These days, we're kind of familiar
Speaker 1: with this because you're used to things like, Hey, I
Speaker 1: look at my TV screen. It looks like I'm just
Speaker 1: looking at a picture, but I know that if I
Speaker 1: put my eyeball closed to the screen, I'll see pixels.
Speaker 1: This is basically saying the whole world, all matter is
Speaker 1: actually pixelated. It's built out of little bits instead of
Speaker 1: smooth and continuous.
Speaker 3: Did they have any thoughts about what the little bits
Speaker 3: were like, like do you get different bits in the
Speaker 3: sand and different bits in your skin? Or how fine
Speaker 3: grained was this idea?
Speaker 2: Oh my god?
Speaker 1: They had hilarious ideas about what the little bits were.
Speaker 1: They thought that everything was made up a little bit
Speaker 1: of stuff, but that stuff had different shapes, and you know,
Speaker 1: they were right on the spirit of it that they thought,
Speaker 1: like the properties of the shape determined how we experienced
Speaker 1: it and its property. But for example, they thought that
Speaker 1: something's tasted sour because it was made of little sharp
Speaker 1: needle shaped atoms that like stabbed your tongue when you
Speaker 1: ate it.
Speaker 3: This is going to be so condescending, but that's such
Speaker 3: a cute idea.
Speaker 2: It is so cute, I know.
Speaker 1: And they thought that things that were white were white
Speaker 1: because they were made of very smooth atoms. And they
Speaker 1: thought that your soul was made of atoms, and that
Speaker 1: those atoms were particularly fine grained. They were right in
Speaker 1: the spirit in that the behavior and the structure of
Speaker 1: the atom really does determine, like hey, what is shiny
Speaker 1: and what conducts electricity and what's liquid at room temperature.
Speaker 1: That's all true. They were just wrong on the details.
Speaker 1: But you know, they couldn't see atoms. They were just imagining.
Speaker 1: And I'm really impressed by this. I'm impressed by the
Speaker 1: courage to imagine that the universe is so fundamentally different
Speaker 1: from the way it seems, because that's really the scientific spirit, right, Yeah, totally.
Speaker 3: Okay, So we've got Democritus and his buddy what was
Speaker 3: the buddy's.
Speaker 1: Name mispronounced as Lacoupiskopis, But I don't know the correct pronunciation.
Speaker 3: I hadn't heard of that person before. So you got
Speaker 3: the two of them, and they're proposing that everything is
Speaker 3: made of small bits of stuff. How long before we
Speaker 3: get some clarity on the fact that sour isn't just
Speaker 3: sharp little bits of stuff.
Speaker 1: Yeah, so they're credited with this idea, probably came up
Speaker 1: earlier because remember, we give people credit because we have
Speaker 1: a written.
Speaker 2: Record of it.
Speaker 1: We have like a tiny fraction of everything the Greeks wrote,
Speaker 1: though very excitingly, they're now scanning burnt scrolls from an
Speaker 1: ancient Greek library. We're going to like double the amount
Speaker 1: of Greek writing.
Speaker 2: We have very soon.
Speaker 1: But also, you know, we just don't have writing from
Speaker 1: other civilizations. What do the Etruscans think ancient Chinese writing? So,
Speaker 1: you know, people give the Greeks a lot of credit,
Speaker 1: but we should remember like other people thought about this
Speaker 1: stuff too.
Speaker 3: Ain't that always the way?
Speaker 2: It's always the way, I know.
Speaker 1: And they use the word adam because atomos in Greek
Speaker 1: means indivisible, So that's where that comes from. And this
Speaker 1: is the origin of this idea that you know, smooth
Speaker 1: stuff is actually made of little bits and that still
Speaker 1: guides our mental picture. When I think particle, I still
Speaker 1: think tiny little dot of stuff, like a little spinning
Speaker 1: ball or a grain of sand.
Speaker 2: That's what it means to me.
Speaker 1: Like it's particular, Like if you say something is particulate, right,
Speaker 1: you mean it's made of these little bits. And so
Speaker 1: the words are powerful because they guide our mental images.
Speaker 1: But it wasn't for a couple of thousand years that
Speaker 1: we had really more information. I mean it was chemists
Speaker 1: like Dalton who were doing experiments on chemical reactions and discovering,
Speaker 1: you know, laws of ratios and proportions and the things
Speaker 1: were divisible by integers. That really give us a clue that, oh,
Speaker 1: there were like units of stuff going into these equations
Speaker 1: that you really needed two to one hydrogen to oxygen
Speaker 1: to make a certain amount of water. It gives you
Speaker 1: a clue that it really has just clicked together out
Speaker 1: of these tiny little bits. So that was a really
Speaker 1: important clue. But it wasn't until the late eighteen hundreds
Speaker 1: that we really had the discovery of anything that we
Speaker 1: would today call a particle.
Speaker 3: And is that because it's so tiny, it probably depends
Speaker 3: on having the right technology to be able to address
Speaker 3: that and so did we just have to wait until
Speaker 3: the late eighteen hundreds because that's when we finally got
Speaker 3: the technology where we could start making a dent.
Speaker 2: Yeah. Absolutely.
Speaker 1: And in the great tradition of particle physics, we didn't
Speaker 1: invent the technology that we used to make these discoveries.
Speaker 2: We borrowed it. In this case, we borrowed it from
Speaker 2: the circus.
Speaker 3: From the circus, yes, exactly. All Right, we're going to
Speaker 3: take a break, and when we come back, you're going
Speaker 3: to tell me about how the circus allowed us to
Speaker 3: understand the electron. All right, and we're back, and today
Speaker 3: we're talking about the freak show that is particles, and
Speaker 3: Daniel's gonna tell us about how we were able to
Speaker 3: understand the electron from technology developed for the circus mm HM.
Speaker 1: Back in the mid eighteen hundreds, there were circuses, and
Speaker 1: there were these side shows, and you know, you had
Speaker 1: bearded ladies or conjoined twins or whatever freak show you
Speaker 1: wanted to see, but also you had people with weird gizmos,
Speaker 1: and in particular, somebody invented basically the cathode ray tube,
Speaker 1: but a cathoid ratube back then was actually called a
Speaker 1: Crooks tube. And basically you have a glass and you
Speaker 1: put electricity on one side, electricity on the other side,
Speaker 1: and we now know what happens is that electrons boil
Speaker 1: off of one and fly through it.
Speaker 2: And hit the other.
Speaker 1: But if you left a little bit of gas in
Speaker 1: that tube, then the electrons would hit that gas and
Speaker 1: gas would glow. People were making these tubes because they
Speaker 1: glowed in this eerie way and that was pretty cool.
Speaker 1: And you know, back in the eighteen hundreds, this was
Speaker 1: a magical thing to see that somebody could build this
Speaker 1: thing and it would glow green, it would glow red
Speaker 1: or whatever. And so these Crooks tubes were very popular
Speaker 1: on side shows. And then later scientists were like, what's
Speaker 1: going on here, Let's see if we can understand what's
Speaker 1: going on. And JJ Thompson in the late eighteen hundreds
Speaker 1: used it to discover the electron.
Speaker 3: How do you go from ohnit that tube lights up
Speaker 3: to and that's because of electrons.
Speaker 1: Yeah, So JJ Thompson was trying to understand what is
Speaker 1: lighting up here. And they already called these things cathode
Speaker 1: rays because they could see paths, like definitely, there's a
Speaker 1: line of stuff moving through them. And they were like,
Speaker 1: what are these rays? Is it made of something? A
Speaker 1: lot of people tried to understand this and failed, But
Speaker 1: he had like the best vacuum, so the best control
Speaker 1: of this experiment, and he did it the most systematically.
Speaker 1: What he did was he put these tubes under electric
Speaker 1: fields and he was like, hmm, can I bend these rays?
Speaker 1: And then he tried with magnetic fields, like, oh, can
Speaker 1: I bend the rays this way and that way? And
Speaker 1: he tried with combinations of them. And so we had
Speaker 1: an understanding of electromagnetism back then. We understood that electric
Speaker 1: fields whole things that have charge, and magnetic fields can
Speaker 1: bend them. So from this he determined, oh, these cathode
Speaker 1: rays are little bits of charge. There's charge flowing here
Speaker 1: because I can bend it with fields, and so that
Speaker 1: was really fascinating. And then he very carefully bounced the
Speaker 1: two fields and he was able to measure the mass
Speaker 1: of the thing, and that right there is the origin
Speaker 1: of this sort of concept of a particle. He was like, oh,
Speaker 1: these rays are made of tiny little bits of stuff
Speaker 1: that have a charge and a mass. And what he's
Speaker 1: doing conceptually there is very important. He's saying there's a
Speaker 1: point in space, and I'm going to put two labels
Speaker 1: on it. I'm gonna say it has a charge and
Speaker 1: has a mass, and those two things cannot be separated.
Speaker 1: He tried to separate the mass and the charge and
Speaker 1: he couldn't. So he's like, now in his mind, he
Speaker 1: has these little dots that are moving through space and
Speaker 1: he's putting these mental labels on them. And that's really
Speaker 1: the origin of the modern concept of a particle.
Speaker 3: Okay, So I'm imagining being in his lab He's got
Speaker 3: this ray, he's got a magnet on one side, and
Speaker 3: he does the magic, and he's got that line. Is
Speaker 3: it like a bolt of lightning? Like does it go
Speaker 3: from one side to another and you can see all
Speaker 3: of it? And if so, how does he make the
Speaker 3: jump from there's a line that lights up and bends
Speaker 3: towards the magnet two, And that line is made up
Speaker 3: of lots of little tiny things that come to be
Speaker 3: called electrons, You know what I mean.
Speaker 1: Yes, So what you should be imagining is sort of
Speaker 1: like what a fluorescent life. Well it looks like now,
Speaker 1: it's like long and thin and filled with glowing gas, right,
Speaker 1: except there were like thinner lines. So these were very
Speaker 1: clearly rays. And you're right that he measured that there's
Speaker 1: sort of a flow of charge. Right, So there was
Speaker 1: a screen on one end and you could see these
Speaker 1: glowing dots landing. But he also measured the mass. That's
Speaker 1: what told him that this was made of little bits
Speaker 1: because he could measure actually their charge to mass ratio.
Speaker 1: He couldn't measure the mass itself, but he measured the
Speaker 1: charge to mass ratio by seeing how much they were
Speaker 1: deflected by the magnetic fields.
Speaker 2: That's the thing that.
Speaker 1: Gave him the clue that it was made of little bits,
Speaker 1: not just some continuous stream, because he could identify a
Speaker 1: charge to mass ratio for these bits. And he almost
Speaker 1: sent the world down a crazy path where my job
Speaker 1: title would be different because he didn't call this thing
Speaker 1: a particle, he didn't call it an electron. He used
Speaker 1: the word corpuscule. He thought that was a really cool
Speaker 1: name for this thing that he help. To me, it
Speaker 1: sounds like especially explosive kind of Yeah.
Speaker 3: Yeah, so you were almost a corpuscoologist.
Speaker 1: Or a corpuscular physicist. Fortunately, the person who discovers the
Speaker 1: thing doesn't always get to name it, and later on
Speaker 1: people adopted the name electron suggested by Fitzgerald and Lorentz
Speaker 1: and other folks, and so fortunately the word corpuscular didn't
Speaker 1: hang on. But that was really the seminal experiment where
Speaker 1: people discovered, okay, the world has made the little bits,
Speaker 1: and we can put labels on them. And these days
Speaker 1: we have so many labels for particles. We put spin
Speaker 1: on them, we put charge. Of course, we put other
Speaker 1: kinds of charge. Every particle has a charge for electromagnetism,
Speaker 1: as a charge for the weak force, a charge for
Speaker 1: the strong force. It has a mass. This is really
Speaker 1: part of the concept of a particle is a little
Speaker 1: dot in space with labels that we put on it.
Speaker 3: And it sounds like it gets complicated pretty quick. So
Speaker 3: let's back up a little bit. So we've got mass
Speaker 3: in charge. What is our next historical advancement?
Speaker 1: Well, next came Rutherford because people were wondering, all right,
Speaker 1: so these things exist, these corpus s gules, or these
Speaker 1: electrons as we they to call them. But how do
Speaker 1: you use that to make up the world. It's sort
Speaker 1: of like the twofold question we were talking about before.
Speaker 1: One thing you can do is try to answer, like,
Speaker 1: what is everything around us made out of by taking
Speaker 1: it apart. The other is just to ask what can
Speaker 1: the universe do? Like, not necessarily, how am I built
Speaker 1: out of the universe, but what is the universe capable of?
Speaker 1: Sort of holistically, And so Thompson discovered, oh, the universe
Speaker 1: can make electrons. People were wondering, Okay, are those electrons part.
Speaker 2: Of who we are?
Speaker 1: And you know, they were speculating, we think electrons are
Speaker 1: probably inside the atom. But nobody knew yet what the
Speaker 1: atom structure was. We knew that we had chemicals and
Speaker 1: we had these different atoms and periodic table the elements
Speaker 1: was a thing, but nobody understood how the atom itself
Speaker 1: was built. And we suspected electrons were in there, but
Speaker 1: we didn't understand, like, well, what's balancing that charge? And
Speaker 1: so Thompson proposed that, like, well, we have electrons because
Speaker 1: I discovered them, and so they must be the building
Speaker 1: block of everything, and they're embedded in like a jelly,
Speaker 1: like a positive jelly that balances the charge.
Speaker 2: That was sort of his idea.
Speaker 1: But then Rutherford came along and said, well, let's see,
Speaker 1: and he took a sheet of gold foil and he
Speaker 1: shot radiation at it, and he wanted to understand, like,
Speaker 1: what is that positive stuff made out of And if
Speaker 1: that positive stuff was like spread out like jelly, then
Speaker 1: he would expect that his particle would mostly just slop
Speaker 1: through it. But what he saw was that most of
Speaker 1: the time they just shoot right through the foil, but
Speaker 1: occasionally they bounced right back. What he concluded from that
Speaker 1: was that the positive charges weren't spread out evenly. They
Speaker 1: were clustered into these little hard dots. So most of
Speaker 1: the time the radiation missed it, sometimes they bounced right back.
Speaker 1: That gives us the more modern picture of the atom
Speaker 1: as a positive nucleus surrounded by electrons.
Speaker 3: Okay, so if we are still trying to think of
Speaker 3: this as a jelly, then we should be picturing like
Speaker 3: that strawberry jelly that has seeds in it, and those
Speaker 3: seeds are like the nucleus that the electron was bouncing
Speaker 3: off of. Is that right?
Speaker 2: M hmm exactly.
Speaker 1: And so now we have like electrons, and we also
Speaker 1: have the nucleus, which later on we discover is made
Speaker 1: out of protons and neutrons. And so you were starting
Speaker 1: to build up our catalog of particles to try to
Speaker 1: understand like what is the world made out of? What
Speaker 1: are these particles? And at this point the concept of
Speaker 1: a particle is still it's a dot in space that
Speaker 1: we could put labels on, and one of those labels
Speaker 1: is mass. But then that was all up ended when
Speaker 1: we discovered the next particle, which is the photon.
Speaker 3: Why does it always get more complicated?
Speaker 2: I know?
Speaker 1: Photons mess everything up, right, my goodness. So around the
Speaker 1: turn of the century, Einstein was thinking about what happens
Speaker 1: when you shine light on metal, very bright beam of
Speaker 1: light on metal. What happens is electrons boil off. This
Speaker 1: is something people had seen but not really understood because
Speaker 1: they were confusing results about what happened when you made
Speaker 1: the beam brighter. People expected that if you make the
Speaker 1: beam brighter, which if light is a wave, mean that
Speaker 1: the em fields are oscillating with larger amplitude, so more energy.
Speaker 1: Then they thought that electrons should get kicked off with
Speaker 1: more energy. But instead what they saw was electrons kicked
Speaker 1: off with the.
Speaker 2: Same energy, but more of them.
Speaker 1: So instead of having faster moving electrons, you have more
Speaker 1: electrons at all the same speed. And it was Einstein
Speaker 1: who figured out what that meant. What it means is
Speaker 1: that the light you're shining at the metal is not
Speaker 1: a continuous beam, perfectly smooth the way Maxwell imagined, but
Speaker 1: made of chunks made of bits called photons. And what
Speaker 1: was happening is that each electron can only absorb one
Speaker 1: like the electron absorbs a photon or it doesn't.
Speaker 2: If it absorbs a photon.
Speaker 1: It gets kicked off, and it always has that photon's energy.
Speaker 1: You can't eat two photons or ten photons, and so
Speaker 1: when you make the being brighter, you're shooting more photons.
Speaker 1: More electrons get to eat a photon. But because it's
Speaker 1: based out of these chunks, it's not smooth and continuous.
Speaker 1: It's basically a one on one interaction.
Speaker 3: You said that was Einstein who helps figure outright, So
Speaker 3: that wasn't that long ago one hundred years. Yeah, we
Speaker 3: went from like nothing to amazing detail in the last
Speaker 3: hundred years.
Speaker 4: I know.
Speaker 1: It's really incredible what we've understood. And this is a
Speaker 1: huge advance because now we're like, oh wow, light is
Speaker 1: also made of little mini servings. Right, there's a minimum
Speaker 1: amount of light. Like you take a flashlight and you
Speaker 1: start to turn it down and down and down and down.
Speaker 1: You can't have it be arbitrarily dim like this one
Speaker 1: setting where it's dark, completely dark, but then there's a
Speaker 1: minimum brightness. You can't shoot half a photon out of
Speaker 1: a flashlight or one and a half photons. It's quantized,
Speaker 1: you know, it's not continuous and smooth. But this is
Speaker 1: confusing because they were going to call a photon a
Speaker 1: particle a minute ago. We set a particle something that
Speaker 1: has like mass in charge. Photons don't have mass, So
Speaker 1: already your mental conception of like, oh, a particle is
Speaker 1: a little bit of stuff, Well, this boton doesn't have
Speaker 1: any stuff to it. You know, you can't catch up
Speaker 1: to a photon and look at it, you can't hold
Speaker 1: it in your hand, and yet we think of it.
Speaker 2: As a particle. So already one hundred years.
Speaker 1: Ago, we have to like back up and broaden our understanding,
Speaker 1: like what is a particle if it's not a little
Speaker 1: bit of stuff the way Democratis was imagining.
Speaker 3: And doesn't it get even more confusing yet, because then
Speaker 3: we decide that photons aren't necessarily particles. Sometimes maybe they're waves.
Speaker 3: And at this point you're like, I'm majoring in biology.
Speaker 1: It gets more confusing before it gets more interesting and
Speaker 1: more clear. But yes, there's definitely a period of confusion there,
Speaker 1: and I do think that's kind of a filter. Some
Speaker 1: people hear that and they're like, I need to understand
Speaker 1: this and learn more. I'm going to become a physicist.
Speaker 1: And some people are like, I'm going to go study eels,
Speaker 1: and that's cool because eels can make waves too, you know,
Speaker 1: they're pretty.
Speaker 3: Wiggly and electric fields and yeah.
Speaker 2: Yeah, yeah.
Speaker 1: And something you said I want to get back to,
Speaker 1: which is like, sometimes they're particles. I mean, a photon
Speaker 1: is always a photon. What is a photon? Is it
Speaker 1: a particle? Is it a wave?
Speaker 2: Like really, it's neither.
Speaker 1: The way that that new fruit is not a cherry
Speaker 1: or an apricot, it's not sometimes because it has hints
Speaker 1: of it in your mouth. It's something new and weird.
Speaker 1: And a photon has behaviors that we sometimes describe in
Speaker 1: a particle way, and behaviors we sometimes describe in.
Speaker 2: A wave like way.
Speaker 1: But it's not choosing now I'm a wave, now I'm
Speaker 1: a particle. It's always a photon. It's just that none
Speaker 1: of these descriptions perfectly capture what it is the way
Speaker 1: that like I can't perfectly describe you. I mean, you're
Speaker 1: a mother, you're a partner, you're a podcaster. None of
Speaker 1: those things define who you are. You're Kelly, right, and
Speaker 1: you're sometimes well described by one of those labels.
Speaker 3: Right, yes, right, So this is another one of those problems,
Speaker 3: like brains are like a computer, yes, but not entirely.
Speaker 3: And by putting these labels on it, sometimes it helps
Speaker 3: you think about it, but also sometimes it makes things
Speaker 3: more confusing.
Speaker 1: So let's dig into what it means though, because the
Speaker 1: thing people were trying to confront, the thing people were
Speaker 1: struggling with is like, yeah, Einstein tells us light is
Speaker 1: made out of these little packets, so we should think
Speaker 1: of them as like individuals. But also we had all
Speaker 1: these experiments showing that lighthead wave like behavior, you know,
Speaker 1: it like interferes with itself, diffraction. There's all sorts of
Speaker 1: stuff that we only usually attribute to waves, and so
Speaker 1: people have this idea in their mind, and they hear
Speaker 1: a lot about the particle wave duality that sometimes you
Speaker 1: use wave to describe light and sometimes you use particles
Speaker 1: to describe light. And later on it got more confusing
Speaker 1: because we saw that electrons do this too, like electrons
Speaker 1: have wave like behavior. You could take beams of electrons
Speaker 1: and they will interfere with themselves as if they are waves.
Speaker 1: But you know, electron is like the original og particle.
Speaker 1: So what's going on here? And there is definitely a
Speaker 1: way to.
Speaker 2: Think about this that's not Sometimes it's a.
Speaker 1: Wave and then it switches suddenly to a particle. It's
Speaker 1: the more quantum mechanical way to think about it, which
Speaker 1: is rarely like a way to think more clearly about stuff,
Speaker 1: but you know, it is the way that we think
Speaker 1: about it. And the quantum mechanical way to think about
Speaker 1: this without getting heavy into the math, is to say
Speaker 1: that what controls where a particle goes is a mathematical
Speaker 1: equation that looks like a wave equation.
Speaker 2: We call it the Schrodinger.
Speaker 1: Equation, and it tells us what's likely to happen to
Speaker 1: a particle. So an electron enters an experiment, the shorting
Speaker 1: equation tells us, oh, is it likely to go left?
Speaker 1: Or is it likely to go right? A photon goes
Speaker 1: through a slit, the shortening equation tells us is it
Speaker 1: likely to go here?
Speaker 2: Is it likely to go there? It's going to land
Speaker 2: on a screen.
Speaker 1: The shortening equation tells us what's the probability of something happening,
Speaker 1: So it's wave like in that an equation that looks
Speaker 1: a lot like other wave equations, the equations we use
Speaker 1: to describe oceans and sound and all sorts of wave
Speaker 1: like behavior, which is amazingly everywhere in the universe. And
Speaker 1: we can have a whole conversation about, like, why does
Speaker 1: the universe all seem like waves? There's a wavy equation
Speaker 1: that describes where this stuff is likely to go. But
Speaker 1: then there's something weird that happens, which is the universe
Speaker 1: has to go from here. All the things the photon
Speaker 1: could do, and here's the various probabilities of it going
Speaker 1: here or there. Then we do the experiment. We want
Speaker 1: to know the answer. The universe does this thing where
Speaker 1: it picks one. It's like, all, right, of all the possibilities,
Speaker 1: I'm going to decide this photon goes over there, and
Speaker 1: this other photon is going to go over here, and
Speaker 1: this third photon is going to go there. And it's
Speaker 1: sort of amazing and it's a process. We fundamentally do
Speaker 1: not understand how the universe goes from Here's the list
Speaker 1: of probabilities to I'm going to pick one. But this
Speaker 1: is what people imagine when they think wave like to
Speaker 1: particle like. Wavelike is like when the universe is still
Speaker 1: maintaining all the possibilities. Particle like is like I've looked
Speaker 1: at it, I've measured it, I see a dot on
Speaker 1: the screen. So I'm thinking of it as acting like
Speaker 1: a particle because it's here, has the location, and we
Speaker 1: think of particles as like it is somewhere. It's a
Speaker 1: tiny dot in space with labels. So when we force
Speaker 1: the universe to tell us where did that photon go,
Speaker 1: we call it being particle like because we put a
Speaker 1: location on it.
Speaker 3: Okay, And is this the right way to think about
Speaker 3: all particles or do some particles follow this wave function
Speaker 3: thing and other particles don't.
Speaker 1: This is the nineteen thirties way to think about all particles.
Speaker 1: You can use this to describe photons, you can use
Speaker 1: it to describe electrons. You can do use to describe
Speaker 1: any particle. This is the Shortener equation, and it works
Speaker 1: really really well for individual particles, and these deep fundamental
Speaker 1: problems with it still like we don't understand when the
Speaker 1: universe goes from here are all your possibilities to actually,
Speaker 1: we're going to do this one. People call this the
Speaker 1: wave function collapse or quantum collapse, and philosophically it makes
Speaker 1: no sense because it doesn't happen when a photon is
Speaker 1: measured by a quantum particle. Like a photon can interact
Speaker 1: with an electron and maintain all of its possibilities. But
Speaker 1: if a photon hits an eyeball you see it here
Speaker 1: or you don't see it there, it collapses. And so
Speaker 1: really this wave versus particle thing is about maintaining quantum
Speaker 1: possibilities or collapsing to one. That's really the core of it,
Speaker 1: and that is not something we understand why that happens,
Speaker 1: When that happens, If that happens, huge open question in
Speaker 1: physics and in philosophy, and what is a particle sort
Speaker 1: of sits right at the nexus of that. So we've
Speaker 1: mapped this question of like what is a particle to hey,
Speaker 1: when do quantum wave functions collapse?
Speaker 2: And do they?
Speaker 1: But that's not a question we have an answer to.
Speaker 1: So I'm not sure how helpful it is. But the
Speaker 1: modern view of what is a particle is actually a
Speaker 1: little bit different from this sort of nineteen thirties concept
Speaker 1: of a wave function and the Schrodinger equation.
Speaker 3: Well, let's take a break and then we'll get modern.
Speaker 3: So we are up to the nineteen thirties, and now
Speaker 3: you are going to tell us about our more modern
Speaker 3: understanding of particles.
Speaker 1: Yes, so this idea that particles are these weird quantum
Speaker 1: objects and where they go is controlled by a wavy equation.
Speaker 1: But sometimes we can make their measurements and force the
Speaker 1: universe to tell us where they are in an instant
Speaker 1: and they have these properties masked sometimes charge, sometimes spin. Sometimes.
Speaker 1: That's sort of an old fashioned view. When we started
Speaker 1: dealing with lots and lots of particles discovered, Oh, this
Speaker 1: math is kind of clunky. Like if you have ten
Speaker 1: particles or one hundred particles, it becomes really awkward to
Speaker 1: have a Shorteninger equation for each individual one and try
Speaker 1: to bring it together. The math just becomes impossible. And
Speaker 1: so people instead of thinking about like one wave function
Speaker 1: for each particle, they're like, let's just think about all
Speaker 1: the particles as if they're wiggling the same field. So
Speaker 1: instead of imagining like an individual person waving their hand,
Speaker 1: now imagine like a crowd at a football stadium and
Speaker 1: they're doing the wave. So add this thing to your brain,
Speaker 1: which is a field. Right, A field in space is
Speaker 1: just like a set of numbers. I say, over here
Speaker 1: to my left, the field has a value of seven,
Speaker 1: and over here to my right field is a value
Speaker 1: of three or two or whatever. And there are wavy
Speaker 1: equations that determine what is the value of the field.
Speaker 1: And so you can have waves in that field. You
Speaker 1: can like ripples in that field where like a large
Speaker 1: value of the field moves through space from here to there.
Speaker 1: And then we think about particles as those ripples in
Speaker 1: the field. So we take like individual wave functions, we
Speaker 1: try to sort of stitch them together into a single
Speaker 1: field and think about all the particles as wiggles in
Speaker 1: the same field.
Speaker 3: So what assumptions do you have to make to make
Speaker 3: that transition? Do you have to assume that they don't
Speaker 3: interact with each other in a way that changes the
Speaker 3: behavior of the group?
Speaker 2: Ah, great question.
Speaker 1: You don't have to assume that, because you can have
Speaker 1: lots of different kinds of fields. You can have some
Speaker 1: fields where the particles don't interact with each other. For example, photons,
Speaker 1: photons don't interact with each other. Photons only interact with
Speaker 1: particles that have electric charge, like they will be eaten
Speaker 1: by an electron or proton can give off a photon.
Speaker 1: But photons ignore each other, like they wiggle right past
Speaker 1: each other. Two beams of light cross without touching or
Speaker 1: bouncing off each other. Other particles do interact with each other,
Speaker 1: like gluons. For example, gluons bounce off of other gluons
Speaker 1: amid other gluons eat other gluons. It gets very complicated
Speaker 1: and messy because gluons talk to each other all the time.
Speaker 1: So you don't have to assume that we build that
Speaker 1: into each field. So we have a new mathematical framework
Speaker 1: that allows us to make different kinds of fields. Some
Speaker 1: fields are very simple, they're just numbers, like the Higgs field.
Speaker 1: It's just a number in space. Other fields, like the
Speaker 1: electromagnetic field. At every point in space, you have an arrow,
Speaker 1: you have a direction, you have three numbers.
Speaker 2: Basically.
Speaker 1: So now imagine like a bunch of arrows filling space,
Speaker 1: and when a photon is moving through that field, what's
Speaker 1: happening is those arrows are growing and shrinking, They're changing direction.
Speaker 1: It's oscillations. In these fields that we think about as particles.
Speaker 1: But we do have to make one important assumption which
Speaker 1: has a lot of consequences, which is that every electron
Speaker 1: is basically the same and every photon is basically the
Speaker 1: same because they're all part of the same field. It
Speaker 1: was a question for a long time, like why does
Speaker 1: every electron have exactly the same mass and exactly the
Speaker 1: same charge? Why is every photon zero mass? Why are
Speaker 1: they all identical?
Speaker 2: Right?
Speaker 1: And the answer is kind of beautiful as well. They're
Speaker 1: all wiggles in the same field.
Speaker 2: It's not like the.
Speaker 1: Universe made a bunch of electrons and it was really
Speaker 1: good at it, so it was super precise, and the
Speaker 1: electron factories like high precision engineering, so they're really you know,
Speaker 1: balls on perfect it's because they literally are the same
Speaker 1: thing that are just ripples in the same field.
Speaker 3: Well, that's convenient because it's easier to think of it
Speaker 3: as a field, right than as a particle.
Speaker 1: Mathematically, it's much easier because if you want to think
Speaker 1: about like particles being created, oh, that's just energy going
Speaker 1: into the field, whereas in the shirting equation it's like
Speaker 1: pretty hard to create a particle and add its wave
Speaker 1: function to your calculations, and the same thing with destroying particles.
Speaker 1: It's really awkward if you're thinking about it one particle
Speaker 1: at a time, and very natural if you're thinking about
Speaker 1: it as a group of particles.
Speaker 3: The universe threw us a softball. Thanks universe. Okay, So
Speaker 3: when I was in high school, I learned about electrons
Speaker 3: and protons and neutrons. I don't remember hearing about quarks.
Speaker 3: But you know, since high school, I've learned that protons
Speaker 3: are made up of quarks. But I think particles as
Speaker 3: being the smallest things that make up everything. And so
Speaker 3: if quirks make up protons, does that mean protons aren't
Speaker 3: particles or are they both particles but maybe different categories
Speaker 3: of particles? What's going on here?
Speaker 1: Oh, that's a great question. So we mostly use these
Speaker 1: fields to describe fundamental particles, things that we think are
Speaker 1: not made of anything else. So the photon and the electron,
Speaker 1: et cetera. Those particles are wiggles and fields that are
Speaker 1: just a basic element of space itself.
Speaker 2: But you can totally use.
Speaker 1: The same math to describe wiggles in other stuff, like
Speaker 1: water in the ocean or sound waves in the air.
Speaker 1: These are just wave equations, and the universe is kind
Speaker 1: of wavy, and you can also identify particles of those
Speaker 1: fields quanta of those fields. A phonon, for example, is
Speaker 1: a packet of sound, the way a photon is a
Speaker 1: packet of light. The math is the same, it's just
Speaker 1: what's wiggling is not fundamentally universe stuff whatever that is,
Speaker 1: but something else water or air or plasma or whatever.
Speaker 2: So we distinguish these.
Speaker 1: Things from particles by calling them quasi particles. But the
Speaker 1: point is that the math still works, all right. So
Speaker 1: to your question about the proton, we know the proton
Speaker 1: is not a fundamental particle. It's made of quarks, so
Speaker 1: there's no proton field, right. Well, actually, if you zoom
Speaker 1: out far enough so you can't see the inside of
Speaker 1: the proton, it kind of acts like a particle that
Speaker 1: moves around the universe the way a particle does. And
Speaker 1: you can pretend that there is a proton field. You
Speaker 1: can write it down mathematically and use it to describe
Speaker 1: the motion of the proton as a particle. And the
Speaker 1: proton field is like an approximate description of the quark
Speaker 1: fields dancing together. The way they interact together makes it
Speaker 1: seem like there is a proton field, and until you
Speaker 1: get enough energy that breaks that proton apart, it all
Speaker 1: works just fine. And the same, of course, might be
Speaker 1: true of the electron. We think that there is an
Speaker 1: electron field, a fundamental part of space. But if the
Speaker 1: electron is just made of other little particles, which are
Speaker 1: the true fundamental particles, then the electron field is just
Speaker 1: an approximate description of those fields dancing together.
Speaker 3: All right, So where do you go from there?
Speaker 1: So in this picture, particles are not little bits of stuff, right,
Speaker 1: you have to give up that whole idea, that whole
Speaker 1: mental picture we've had since Democritus that said the universe
Speaker 1: is made of particles and particles are little bits of stuff.
Speaker 1: Now we say, well, particles are not little bits of stuff.
Speaker 1: They're wiggles in these fields. And that means something really deep.
Speaker 1: It means that the universe is not made of particles.
Speaker 1: It's made of fields. Particles are just something that happens
Speaker 1: to fields. There's just something fields can do.
Speaker 2: You know. It's like discovering.
Speaker 1: Okay, ice cream exists in the world, but actually it's
Speaker 1: not fundamental. Universe is not made of ice cream. There's
Speaker 1: times when you don't have ice cream. There's whole periods
Speaker 1: in the universe when there was no ice cream. It's
Speaker 1: hard to imagine there was a moment when somebody invented
Speaker 1: ice cream for the first time, right, and the universe
Speaker 1: was filled with light. Yes, what it means is that
Speaker 1: we've gone one level deeper though, right.
Speaker 2: This is the whole goal. It's like, what really is.
Speaker 1: At the foundation? What is everything made out of? And
Speaker 1: this takes quite a left turn. It says, yeah, the
Speaker 1: universe is not built of little bits. Those bits are
Speaker 1: actually just ripples in these fields that fill the universe.
Speaker 1: And I want people to really have an accurate visual
Speaker 1: image of what these fields are because people think about, Okay,
Speaker 1: a particle is a ripple in the field, or it's
Speaker 1: an excitation in the field, And you should understand that
Speaker 1: a field really is a wavy kind of thing. It
Speaker 1: can do the same wavy kind of things that other
Speaker 1: fields can do. You know, like imagine a guitar string.
Speaker 1: What does a guitar string do when you pluck it,
Speaker 1: you pull it back and so now it's like you're
Speaker 1: stretching the string, right, we say in physics, now it
Speaker 1: has a lot of potential energy because a lot of
Speaker 1: tangent in there really wants to go back to its
Speaker 1: relaxed position.
Speaker 2: What happens when you relax it?
Speaker 1: What happens when you let it go, Well, it flies
Speaker 1: back to that relaxed position. But now it's moving really fast,
Speaker 1: so now has a lot of speed, rights a lot
Speaker 1: of kinetic energy. So it doesn't actually stop there when
Speaker 1: it gets back to the relaxed position. It keeps going
Speaker 1: and it bends the other way, and it oscillates back
Speaker 1: and forth and back and forth and back and forth.
Speaker 1: It slashes back and forth between potential energy and kinetic energy.
Speaker 1: That's what a wave equation, and that's a wave like phenomenal.
Speaker 1: I mean that slashes back and forth. That's what fields
Speaker 1: are doing. Fields you can think of them as these
Speaker 1: numbers in space, but those numbers are slashing back and forth.
Speaker 1: The field itself has potential energy and kinetic energy. The
Speaker 1: changing of those numbers has a speed to it. And
Speaker 1: when we solve the wave equations for fields, what is
Speaker 1: fundamentally quantum field theory the bedrock of modern particle physics.
Speaker 1: That's what the solutions look like like. The Higgs field
Speaker 1: is oscillating when we say a photon is an oscillation
Speaker 1: in the electromagnetic field, We mean the values of the field.
Speaker 1: Those numbers in space, Those arrows, they're moving, they're wiggling,
Speaker 1: they're slashing around.
Speaker 3: So when I was in high school, we got the
Speaker 3: like plum pudding model. So yes, I do think now
Speaker 3: about particles as like a raisin embedded in something, and
Speaker 3: not as like a wave function. If I were in
Speaker 3: high school right now, would I be taught something more
Speaker 3: like what you just said? How long have we known
Speaker 3: about this stuff? Why does this feel new? Is what
Speaker 3: I'm asking? Is it new? Or did I forget?
Speaker 1: It's a great time to ask me this question because
Speaker 1: my daughter, who's taking high school chemistry right now, is
Speaker 1: learning about this stuff and asking me questions about it.
Speaker 1: So I'm getting like a front row seat too. How
Speaker 1: are people taught about the nature of matter in high school? Yeah,
Speaker 1: and yeah, they're taught about the plum putting model. Though,
Speaker 1: just for the record, the plum putting model is not
Speaker 1: a modern conception. It was like disproved by Rutherford, right.
Speaker 1: People thought, well, maybe the universe is filled with this
Speaker 1: jelly of positive stuff. Sounds tasty, but it's not the
Speaker 1: way that we understand it. It's in contrast to having
Speaker 1: like a hard dense nucleus at the core. So the
Speaker 1: plum putting model, they teach it to them and then
Speaker 1: they throw it out, but they don't really go very
Speaker 1: deep into like the quantum mechanics of it. Even in
Speaker 1: AP chemistry, I discovered they don't really talk about this stuff,
Speaker 1: and they certainly don't talk about particle physics in AP physics.
Speaker 1: So in high school you don't really get a whole
Speaker 1: lot of this modern stuff. I teach modern physics at
Speaker 1: the college level, and that's the first time we really
Speaker 1: give people an understanding of the nineteen thirties concept of
Speaker 1: what is a particle and how does quantum mechanics work.
Speaker 1: And then we don't show them quantum fields until like
Speaker 1: graduate school. So I didn't learn about quanum field until
Speaker 1: I was in like eighteenth grade.
Speaker 2: So you know, this is not the kind of.
Speaker 1: Stuff that percolates mostly into high school. Maybe fortunately, maybe unfortunately,
Speaker 1: I would love to have some of these ideas introduced earlier.
Speaker 3: So you think if you talked to just about any
Speaker 3: recent graduate of high school, they're probably still thinking of
Speaker 3: electrons as particles that stay in one spot.
Speaker 1: Tiny little dots orbiting the nucleus. Do you know Electrons
Speaker 1: don't orbit, They don't have specific locations. They can't be
Speaker 1: in one spot and have a specific velocity. You can
Speaker 1: measure them here, you can measure them there, but they're
Speaker 1: weird quantum objects. They don't go from here to there.
Speaker 1: They don't obey all the intuitive rules that you expect
Speaker 1: things that have specific locations to do.
Speaker 3: So we can all feel good about our advanced physics knowledge.
Speaker 1: Now, yes, exactly, you have pushed well beyond high school
Speaker 1: and even college physics. And you know, I have to
Speaker 1: underscore how powerful this quantum field theory approach is. To
Speaker 1: say that all particles are just ripples and fields, and
Speaker 1: the universe fundamentally is made of these fields. All space
Speaker 1: is filled with many kinds of fields. You have one
Speaker 1: for the electron, one for the muon, one for the upcork,
Speaker 1: one for the down cork.
Speaker 2: We have more than a.
Speaker 1: Dozen fields that fill space. This is a really powerful
Speaker 1: way to think about the universe. We see patterns in
Speaker 1: these fields, how energy flows from one to the other,
Speaker 1: their symmetries that they observe. It's allowed us to make
Speaker 1: really powerful, very accurate calculations of all sorts of stuff
Speaker 1: that we see happening in particle experiments, and so it's
Speaker 1: really beautiful and really crisp and really clear. And I
Speaker 1: think that most particle physicists this is what they think about,
Speaker 1: or most theoretical physicists, imagine the universe as filled with
Speaker 1: fields and particles as just ripples in them. But of
Speaker 1: course it's a field filled with controversy, and so not
Speaker 1: everybody agrees with that view. There are lots of people
Speaker 1: who have a very different concept of what a particle
Speaker 1: is and fundamentally how it all works at the bottom level.
Speaker 3: So to back up real quick, the field's theory has
Speaker 3: produced loads of testable hypotheses that have been tested and
Speaker 3: panned out. But there are still some people who think
Speaker 3: maybe something else is going on that explains these resultss
Speaker 3: and what are they proposing is happening.
Speaker 1: Then they suggest the fields are a fiction, that the
Speaker 1: fields don't really exist, that the fields are basically just
Speaker 1: a calculational tool we use in our minds to explain
Speaker 1: what we see, because in the end, you can't observe
Speaker 1: a field. You can't directly see a field. It's always
Speaker 1: an intermedia thing like what you can see are particles.
Speaker 1: You see those little dots on your screen, or you
Speaker 1: see the electron deflected in your cathode ray. It's always particle,
Speaker 1: like I'm doing air quotes when we see it, And
Speaker 1: particles are what we observe, They're what.
Speaker 2: We interact with.
Speaker 1: Yes, we can use fields to explain them, and yes
Speaker 1: we can think about fields as being out there, but
Speaker 1: it's hard to argue philosophically that we know fields are
Speaker 1: real in some way other than we can use them
Speaker 1: to calculate these experiments. You can't like really directly see them.
Speaker 1: And lots of famous physicists like Nima or Kanye Ahmed,
Speaker 1: one of the maybe most brilliant modern particle physicists, calls
Speaker 1: them a convenient fiction.
Speaker 3: Huh, So would someone like Nima then argue it's all
Speaker 3: just particles, Like the field thing is throwing us off track.
Speaker 3: We were on track with the particles, and we just
Speaker 3: got to stick with thinking about particles and figure out
Speaker 3: a way to measure yes at that level instead.
Speaker 1: Yeah, and here I want to take the opportunity to
Speaker 1: disentangle something you hear about a lot in popular science.
Speaker 1: People probably hear oh, particles or ripples in a field.
Speaker 1: But they also hear this other story, like what happens
Speaker 1: when two electrons repel each other, Oh, they exchange a photon.
Speaker 1: They're passing a photon back and forth.
Speaker 2: Right.
Speaker 1: What you're doing there is rejecting the field picture. The
Speaker 1: field picture of what happens when electrons push on each
Speaker 1: other is an electron makes a field around it, the
Speaker 1: electromagnetic field, right, and that field pushes on the other electron.
Speaker 1: That's the field picture. People who don't believe in fields,
Speaker 1: they're like, just explain it all in terms of particles.
Speaker 1: You don't need the field. What happens when an electron
Speaker 1: pushes on another electron is it throws a photon at
Speaker 1: the other one. And so you can either explain everything
Speaker 1: in terms of particles that are pushed by fields, or
Speaker 1: you can explain it just in terms of particles and
Speaker 1: say you don't need fields. Just go particles all the
Speaker 1: way down. There are particles we observe, and they push
Speaker 1: on each other by passing other particles between themselves. So
Speaker 1: you can basically replace the fields with an infinite number
Speaker 1: of particles doing all the pushing and pulling and all
Speaker 1: that other stuff that some people say fields are doing
Speaker 1: and the frustrating, slash confusing, slash amazing thing is that
Speaker 1: you do the calculation since you get the same answer.
Speaker 1: So is it particles is it fields? We can't tell
Speaker 1: the difference because the two theories mathematically are equivalent. It's like,
Speaker 1: either you can imagine these fields which fill space, which
Speaker 1: are beautiful and elegant but kind of weird, like what
Speaker 1: are they? Or you can say, I'm going to replace
Speaker 1: those fields by a bunch of particles flying around doing
Speaker 1: that same work.
Speaker 3: And are you a field guy?
Speaker 1: I was a fields guy until I read this book
Speaker 1: about whether science can be done without math. You know,
Speaker 1: people wonder like is math invented? Or is it something
Speaker 1: in our minds? And there's a guy who developed an
Speaker 1: alternative theory of gravity that doesn't use any math, no
Speaker 1: numbers at all. It's called science without numbers, and it's
Speaker 1: really weird. It's very alien. You read it and you're like,
Speaker 1: what was this guy smoking? And where can I get some?
Speaker 1: But he philosophically pulls it off. He shows that you
Speaker 1: don't need to have fields essentially, and the crucial insight
Speaker 1: in that book is to get rid of fields, because
Speaker 1: fields are like numbers in space. So he divorces physics
Speaker 1: from mathematics by ditching fields. My favorite part of the
Speaker 1: story the guy's last name Fields. So Professor Fields gets
Speaker 1: rid of fields, the field fieldless theory of physics. There's
Speaker 1: lots of jokes you could make there, but it made
Speaker 1: me wonder, you know, like our field's just something we
Speaker 1: think about or they actually out there. When aliens come
Speaker 1: and talk to us about their theory of physics, will
Speaker 1: they have fields in it? Or will they have Schmields
Speaker 1: or something totally different?
Speaker 3: So have you dodged my question or are you saying
Speaker 3: that you're a particle person.
Speaker 2: I'm saying I don't know.
Speaker 1: I used to be a fields person, but now I
Speaker 1: teach the controversy, got it?
Speaker 3: Okay? So when you first said that there were people
Speaker 3: who reject fields, I thought that was going to get
Speaker 3: us into string theory. Are we going to get to
Speaker 3: string theory too? There's three options. So there's particles, fields,
Speaker 3: and strings. Is that right?
Speaker 2: There's more than three options? Unfortunately?
Speaker 1: Okay, So there's lots of directions to go here. People
Speaker 1: also wonder, like, well, what are these fields? Are fields
Speaker 1: that bend ra the truth of the universe at the
Speaker 1: firmament is that the thing that has to exist. And
Speaker 1: it's sort of unsatisfactory because, well, why are there all
Speaker 1: these different fields? Why do we have the electron and
Speaker 1: the muon, which is like a weird heavy version of
Speaker 1: the electron. Why are there these obvious patterns among the
Speaker 1: fields that we can't explain. And one explanation for that
Speaker 1: are strings, to say, well, none of these things are
Speaker 1: what's at the bedrock underneath it all is something else,
Speaker 1: and strings are this idea that the universe is not
Speaker 1: made out of field to instead these one dimensional bits
Speaker 1: of matter that can do wavy like stuff. They can wiggle,
Speaker 1: and they can dance, and they can wiggle in various ways.
Speaker 1: And if you're zoom down far enough so you can't
Speaker 1: see the actual string bits themselves, when they wiggle one way,
Speaker 1: it looks like an electron field, and when they wiggle
Speaker 1: another way, it looks like a muon field, and when
Speaker 1: wiggle a third way, it looks like a photon. And
Speaker 1: so all these fields are actually just different wiggles in
Speaker 1: these strings. This is another beautiful bit of mathematics. Nobody's
Speaker 1: proven to be true or not, but might represent what's
Speaker 1: going on underneath all of this, right, So maybe particles
Speaker 1: are ripples and fields which are just wiggles in strings.
Speaker 3: So string theory is still a popular contender. I thought
Speaker 3: maybe string theory was waning, but I'm you know, not
Speaker 3: in this field. What's the current state of the string theory.
Speaker 1: String theory was very popular in the nineties. It seemed
Speaker 1: very exciting. People discovered this math and could do all
Speaker 1: sorts of fun stuff with it. And they've done a
Speaker 1: lot of fun stuff, but they haven't been able to
Speaker 1: prove that it's true because they talk about the mathematics
Speaker 1: of the strings, but nobody can see these strings.
Speaker 2: The strings are too small.
Speaker 1: In order to see the strings themselves, you'd need like
Speaker 1: a collideer to the size of the solar system, and
Speaker 1: we don't have the funds for that. And so until
Speaker 1: they make a prediction that we can actually test it,
Speaker 1: say like, oh, string theory, if it's true, we should
Speaker 1: be able to see this thing, then we don't know
Speaker 1: if it's just mathematics or if it's actually a description
Speaker 1: of the universe. And so there's been a lot of
Speaker 1: people who are negative about string theory for that reason.
Speaker 1: I still think it's exciting, but there are other ideas
Speaker 1: out there about you know, what the universe could be
Speaker 1: made out of?
Speaker 3: What else?
Speaker 1: As you were saying earlier, we tend to think about
Speaker 1: the brain as made out of whatever is the latest
Speaker 1: technology in the same way we try to think about
Speaker 1: the universe that way. Like the advent of quantum computing
Speaker 1: makes us think about cubits and information And there's a
Speaker 1: whole line of argument that I think we should talk about,
Speaker 1: probably on another episode, about whether the whole universe is
Speaker 1: just a quantum computer and particles are like patterns and
Speaker 1: the flow of information in this quantum computer. There are
Speaker 1: folks who do these experiments that discover that if you
Speaker 1: build a space time from entangled cubits, that these patterns
Speaker 1: naturally arise, which have properties that align well with.
Speaker 2: The particles that we see.
Speaker 1: This is all really very speculative stuff, but it's sort
Speaker 1: of the forefront of current research. People wondering, like, what's
Speaker 1: underneath all this stuff? Maybe it really is even different
Speaker 1: than democratists imagined, or Schrotinger or even Fineman.
Speaker 3: What is a cubit.
Speaker 1: A cubit is a quantum analogy to a classical bit,
Speaker 1: like in your computer. A bit is something that can
Speaker 1: be zero or one. It's like the minimum piece of
Speaker 1: information you can have. It's boiled down to just two options,
Speaker 1: like a switch you can flip. And a normal bit
Speaker 1: is in one state, but a quantum bit has a
Speaker 1: probability to be in one state or in the other.
Speaker 1: It's not necessarily in one or the other. So it's
Speaker 1: a cubit is a quantum bit. And people wonder if
Speaker 1: fundamentally the universe is made out of cubits that are
Speaker 1: somehow woven together to make space and time and our reality.
Speaker 1: But we'll dig into that in a whole other episode.
Speaker 3: Awesome, all right, So if we tomorrow were to find
Speaker 3: out which one of these explanations was correct, what would
Speaker 3: that change? So that would be satisfying, But where could
Speaker 3: we go from there? That would be even cooler, Like
Speaker 3: what doors would that open up? For us?
Speaker 2: Yeah?
Speaker 1: Wow, awesome question. You're basically asking, like, why do we
Speaker 1: care about any of this? So what does it mean
Speaker 1: for us? For me, it's like really deeply important and
Speaker 1: to understand what is the nature of the universe we're in,
Speaker 1: You know, what is it made out of? If you
Speaker 1: told me the universe starts from these conditions, and everything
Speaker 1: else follows from that, Like to have a universe, you
Speaker 1: have to have space and time and this little bit
Speaker 1: of stuff, and then everything else, all the complexity, the blueberries,
Speaker 1: the kittens, the lava, the podcast, all that comes from
Speaker 1: how that stuff is arranged and interacts.
Speaker 2: And that's cool.
Speaker 1: I want to know what is the most fundamental thing,
Speaker 1: because that tells me something deep about the nature of
Speaker 1: the universe. If it's this, then the universe is that
Speaker 1: way in some deep wave. It's that the universe is
Speaker 1: another way, in some deep way, and I just fundamentally
Speaker 1: want to know. It doesn't change how you drink your coffee,
Speaker 1: it doesn't change how you treat people. It doesn't change
Speaker 1: what investments you should make. But it changes what it
Speaker 1: means to be alive in this universe in a really
Speaker 1: important way.
Speaker 2: To me. It's very uncomfortable that we don't know the.
Speaker 1: Answer to the basic question of like, what is the
Speaker 1: fundamental building block of the universe we live in. It's
Speaker 1: like being born into a jail and not knowing who
Speaker 1: built it or what's in the outside. It's like, I
Speaker 1: want to break out of this ignorance.
Speaker 3: I found myself personally wanting the answer to be that
Speaker 3: everything is a field and it's sort of connected in
Speaker 3: a way that feels like, I don't know, maybe sort
Speaker 3: of like kum bay us sit around a fire sort
Speaker 3: of feeling. But I like that stuff, so anyway, I
Speaker 3: guess my gut wants that to be the answer. But yes,
Speaker 3: I think it would be good for us to know
Speaker 3: the answer to this very fundamental question.
Speaker 1: And I suspect the answer is none of these and
Speaker 1: something even weirder. That's going to be so difficult for
Speaker 1: us to understand. It's going to be a stretch to
Speaker 1: even explain in terms of our intuitive language of concepts.
Speaker 1: You know, we're going to have to use kiwis and
Speaker 1: fields and particles and strings and all sorts of other
Speaker 1: stuff to try to wrap our minds around the way
Speaker 1: that we universe actually works, which has no guarantee that
Speaker 1: it's even understandable to us.
Speaker 3: So people are going to be like Democratus thought it
Speaker 3: was sour because it was like little knives, and then
Speaker 3: Daniel and Kelly thought it was like strings and fields.
Speaker 3: What idiots? So you know, who knows what they'll think
Speaker 3: in a hundred or so years.
Speaker 2: I hope they're laughing at us. In one hundred years,
Speaker 2: that would be awesome.
Speaker 3: Yeah, progress is good.
Speaker 1: All right, Well, thanks everybody for taking this journey with
Speaker 1: us from the ancient misunderstanding of what matter was to
Speaker 1: our modern misunderstanding of what matter is. And we hope
Speaker 1: to continue this journey and to slowly chisel away towards
Speaker 1: some actual, solid understanding.
Speaker 3: Have a good week everyone. Daniel and Kelly's Extraordinary Universe
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Speaker 3: We really would.
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