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What is a particle? · Daniel and Kelly’s Extraordinary Universe

• 0:06
  Speaker 1: What is everything made out of? That seems like a
• 0:09
  Speaker 1: simple question, and it also seems like a reasonable question.
• 0:13
  Speaker 1: I'd like to know what I'm made out of, what
• 0:15
  Speaker 1: my food is made out of, what kittens are made
• 0:17
  Speaker 1: out of, what lava is made out of. It's also
• 0:19
  Speaker 1: an ancient question, I think, one that people have been
• 0:22
  Speaker 1: asking since people have been asking any questions. The Greeks,
• 0:26
  Speaker 1: famous for asking questions in their sexy robes, thought that
• 0:30
  Speaker 1: everything was made of earth, air, water, and fire. And
• 0:34
  Speaker 1: modern science, of course, has made a lot of progress
• 0:36
  Speaker 1: here and uncovered some pretty weird and kind of shocking
• 0:40
  Speaker 1: news about what everything is made out of. What seems
• 0:43
  Speaker 1: like smooth and continuous matter is actually made up of
• 0:47
  Speaker 1: tiny little bits that are woven together into some extremely
• 0:51
  Speaker 1: fine mesh. And we are all made of the same
• 0:54
  Speaker 1: basic bits, some together to make me or you, or
• 0:57
  Speaker 1: kittens or lava. The world is of particles. But our
• 1:02
  Speaker 1: curiosity doesn't just end because we have that answer. We
• 1:05
  Speaker 1: want to know what are these basic bits? How do
• 1:08
  Speaker 1: we think about them? What mental pictures should we have
• 1:11
  Speaker 1: in our mind? Are they tiny dots of stuff or
• 1:13
  Speaker 1: rippling waves or some other concept that's too alien to
• 1:17
  Speaker 1: even imagine. And what does it tell us about the
• 1:20
  Speaker 1: universe that these are its basic building blocks?
• 1:23
  Speaker 2: Or are they? So?
• 1:25
  Speaker 1: Today, on Daniel and Kelly's Extraordinary Universe, we'll be tackling
• 1:29
  Speaker 1: the basic yet confusing, the simple yet deep, the important
• 1:32
  Speaker 1: but impossible question what is a particle?
• 1:49
  Speaker 3: Welcome to Daniel and Kelly's Extraordinary Universe. I'm Kelly Wiener Smith.
• 1:53
  Speaker 3: I'm a parasitologist and I'm particularly excited to be here today.
• 2:00
  Speaker 3: But it might have been really cute if I had
• 2:01
  Speaker 3: been able to pull it off, but I didn't.
• 2:04
  Speaker 2: Hi, I'm Daniel.
• 2:05
  Speaker 1: I'm a particle physicist, which means I probably should know
• 2:08
  Speaker 1: what a particle is.
• 2:11
  Speaker 3: Well, we've got the right expert on the show today.
• 2:13
  Speaker 3: So Daniel, here's what I'm wondering. So you've told me
• 2:16
  Speaker 3: that you go to CERN in Switzerland to do your research.
• 2:21
  Speaker 3: Why doesn't the United States have the biggest particle collider?
• 2:24
  Speaker 1: Oh my gosh. Why you are putting your foot in
• 2:26
  Speaker 1: a sensitive spot right there. You know, for many years
• 2:30
  Speaker 1: it was a race between the Europeans and the Americans.
• 2:33
  Speaker 1: So before CERN had the most powerful collider.
• 2:36
  Speaker 2: We had one.
• 2:36
  Speaker 1: It was outside of Chicago at Fermi Lab. It's called
• 2:39
  Speaker 1: the Tevatron. I did my PhD there. I had one
• 2:42
  Speaker 1: child born near that collider, and then my next child
• 2:45
  Speaker 1: born near Cerns. You know, not a kid at each collider.
• 2:47
  Speaker 3: Basically, wait, one of your kids was born abroad?
• 2:51
  Speaker 1: Yeah, my daughter Hazel was born in Switzerland, very close
• 2:54
  Speaker 1: to cern That's cool.
• 2:55
  Speaker 3: Did you have to not pay because you were in
• 2:58
  Speaker 3: Europe and they just do healthcare there or what was
• 3:00
  Speaker 3: that like?
• 3:01
  Speaker 2: No?
• 3:01
  Speaker 1: Actually they told us that when we showed up for
• 3:03
  Speaker 1: the delivery, we had to bring fifty thousand Swiss fronc
• 3:06
  Speaker 1: in cash if we didn't have local insurance.
• 3:10
  Speaker 3: WHOA.
• 3:11
  Speaker 2: So yeah, that was going to be an issue.
• 3:13
  Speaker 1: But then we discovered this a law in Switzerland that
• 3:15
  Speaker 1: if you're working there, which my wife was, they have
• 3:17
  Speaker 1: to insure you. So even though she had all sorts
• 3:20
  Speaker 1: of crazy pre existing conditions, we could buy insurance for
• 3:23
  Speaker 1: like one hundred franc and then we didn't have to
• 3:25
  Speaker 1: pay for anything. So it was amazing.
• 3:28
  Speaker 3: Actually nice, Okay, that's good.
• 3:30
  Speaker 1: And the insurance company even offered to retroactively cover a
• 3:33
  Speaker 1: bunch of appointments to where we hadn't yet had insurance.
• 3:36
  Speaker 1: It was very different experience than American insurance.
• 3:39
  Speaker 3: Yeah, that's incredible. I'm going to get depressed if we
• 3:41
  Speaker 3: stay on this topic too long. Let's go back to
• 3:43
  Speaker 3: particle colliders. Okay, so you have had each of your
• 3:46
  Speaker 3: children near very large particle colliders. Why isn't the biggest
• 3:50
  Speaker 3: one in the US.
• 3:50
  Speaker 1: Well, they planned to build the biggest one in the US,
• 3:52
  Speaker 1: the Superconducting super Collider in Waxahachie, Texas, and they started
• 3:56
  Speaker 1: building it, and they spend billions of dollars digging a hole.
• 4:00
  Speaker 2: But then the director of CERN.
• 4:02
  Speaker 1: At the time came and testified before Congress saying it
• 4:04
  Speaker 1: was a big waste of money because CERN was building
• 4:06
  Speaker 1: one that was going to be bigger and better and
• 4:09
  Speaker 1: they should just cancel it. And Congress, for all sorts
• 4:12
  Speaker 1: of complicated political reasons, listen to him and canceled the
• 4:15
  Speaker 1: American Superconnecting super Collider. And since then the lead has
• 4:19
  Speaker 1: been in Europe and probably will for a while. And
• 4:22
  Speaker 1: the US particle physics communities mostly focused on things like
• 4:26
  Speaker 1: neutrinos and stuff like that. So these days, if you
• 4:28
  Speaker 1: want to do cutting edge, high energy particle physics at colliders,
• 4:32
  Speaker 1: you got to go to Switzerland, which, hey, it's not
• 4:34
  Speaker 1: too bad.
• 4:35
  Speaker 2: The chocolate's amazing, no doubt.
• 4:37
  Speaker 3: You know what. Actually, I'm gonna go out on a
• 4:38
  Speaker 3: limb here and say I'm not a huge fantas with chocolate.
• 4:41
  Speaker 2: Yeah, I know you prefer Belgian I do.
• 4:44
  Speaker 3: Yeah, there I said it. So every once in a
• 4:47
  Speaker 3: while I'll hear about like astronomy students who want to
• 4:49
  Speaker 3: get time on a telescope, but the telescope's all booked
• 4:51
  Speaker 3: up and it takes forever. Does cern have enough time
• 4:55
  Speaker 3: for everyone? So like, when that guy came to the
• 4:56
  Speaker 3: US and tanked our program, did he know he was
• 4:59
  Speaker 3: going to have enough time time for all of our
• 5:01
  Speaker 3: scientists to come over and do their work.
• 5:03
  Speaker 1: Yeah, that's a great question, And people often ask me
• 5:05
  Speaker 1: about that, like what's it like to set up your
• 5:07
  Speaker 1: experiment at the collider? But the reality is very different.
• 5:10
  Speaker 1: Telescopes and colliders don't work the same way. A telescope
• 5:12
  Speaker 1: you have to point at the thing you want to
• 5:14
  Speaker 1: look at. So you write a proposal to say, let's
• 5:17
  Speaker 1: point our amazing telescope at this one star I want
• 5:19
  Speaker 1: to study, and then it's not pointing at any other stars.
• 5:22
  Speaker 2: But a particle collider is very general.
• 5:24
  Speaker 1: It always just does the same thing smashes the particles
• 5:26
  Speaker 1: together and you take pictures of it, and then afterwards
• 5:30
  Speaker 1: you analyze it. So everybody who uses the collider uses
• 5:33
  Speaker 1: the same data. They're just looking for different kinds of particles.
• 5:36
  Speaker 1: We don't have to point the collider at certain things.
• 5:38
  Speaker 1: We don't swap out what we're using to take pictures.
• 5:41
  Speaker 1: Every few years we turn the thing off, revamp it,
• 5:44
  Speaker 1: build a new detector that's better, faster, higher resolution or whatever,
• 5:48
  Speaker 1: and then we make it as general as possible so
• 5:50
  Speaker 1: everybody can use it so you don't have to swap
• 5:52
  Speaker 1: it out every day or every experiment. Everybody uses the
• 5:55
  Speaker 1: same data set, which makes it kind of crazy because
• 5:58
  Speaker 1: everybody's looking for discoveries in the set SA data set
• 6:01
  Speaker 1: at the same time, So you could get scooped by
• 6:03
  Speaker 1: any of your thousands of colleagues Yanks.
• 6:06
  Speaker 3: So do you actually need to be there in person
• 6:09
  Speaker 3: or if it's just data, they can make that available
• 6:12
  Speaker 3: anywhere right.
• 6:13
  Speaker 1: CERN has long been at the forefront of the Internet.
• 6:15
  Speaker 1: We invented the web at CERN, for example, and we
• 6:18
  Speaker 1: have excellent cloud computing and so we transfer that data
• 6:20
  Speaker 1: all around the world. We've collaborated from Japan to Singapore
• 6:24
  Speaker 1: to South Africa, to the northern tip of Canada, all
• 6:28
  Speaker 1: over the world. People analyze this data. Absolutely, you don't
• 6:30
  Speaker 1: have to go. I go frequently because I have students
• 6:33
  Speaker 1: there and postdocs are like on site building stuff and
• 6:35
  Speaker 1: helping keep it run. But technically you don't have to
• 6:38
  Speaker 1: to look at the data.
• 6:39
  Speaker 3: Cool. I mean, that's good and bad. I feel like
• 6:41
  Speaker 3: ecologists like we want to study exotic animals, but partly
• 6:44
  Speaker 3: because we want to go there, And I imagine it's
• 6:46
  Speaker 3: sort of the same with cern, like it'd be nice
• 6:48
  Speaker 3: to go to Switzerland. But I guess the more important
• 6:50
  Speaker 3: thing is answering the question.
• 6:51
  Speaker 1: It is nice to go to Switzerland, but then again,
• 6:53
  Speaker 1: it's also nice to be able to do science without
• 6:56
  Speaker 1: having thousands of dollars to go to Switzerland, which means
• 6:58
  Speaker 1: smaller groups and not such institutions, for example, could also participate.
• 7:02
  Speaker 1: So it makes it a little bit more democratic, you know.
• 7:05
  Speaker 3: Nice. That's awesome. Okay, So the whole point of having
• 7:08
  Speaker 3: a large particle collider is so that you can figure
• 7:11
  Speaker 3: out what those particles are made of, Is that right?
• 7:14
  Speaker 1: The whole point of having a particle collider is that
• 7:15
  Speaker 1: you can say you're smashing particles together and nearly the
• 7:18
  Speaker 1: speed of light, which sounds pretty awesome at parties.
• 7:21
  Speaker 3: It does, yeah, kind of like jousting for particles.
• 7:24
  Speaker 2: Yeah.
• 7:25
  Speaker 1: Well, particle colliders, I think, sort of have two different purposes.
• 7:28
  Speaker 1: One is like, hey, let's take stuff and see what's
• 7:31
  Speaker 1: inside it. Let's start with something familiar, you know, like
• 7:34
  Speaker 1: the proton, and smash it open and see what it's
• 7:36
  Speaker 1: made out of. And that's a continuation of like a
• 7:39
  Speaker 1: long glorious tradition of taking the stuff around us a
• 7:41
  Speaker 1: part to understand what it's made out of. You know,
• 7:44
  Speaker 1: I'm made of molecules, which are made of atoms which
• 7:46
  Speaker 1: have a nucleus and electron, and the nucleus is made
• 7:49
  Speaker 1: of protons. Let's go inside the proton. So that's definitely worthwhile.
• 7:53
  Speaker 2: And we do that.
• 7:54
  Speaker 1: But colliders can actually do something else, even more powerful,
• 7:56
  Speaker 1: which kind of sounds like magic, which is that they
• 7:59
  Speaker 1: can convert the mass of those protons into energy and
• 8:02
  Speaker 1: then back into mass, and so what can come out
• 8:06
  Speaker 1: of the collision is not just a rearrangement of what
• 8:09
  Speaker 1: went in. It's not like chemistry where you're like this
• 8:11
  Speaker 1: hydrogen moved from this atom to over there, and now
• 8:14
  Speaker 1: you have a different kind of compound. You can annihilate
• 8:17
  Speaker 1: these things, and then you basically have like a budget
• 8:19
  Speaker 1: to make anything. And the stuff that comes out of
• 8:22
  Speaker 1: the collision doesn't just have to be like a refashioned,
• 8:25
  Speaker 1: rearranged version of what went in. You can have entirely
• 8:28
  Speaker 1: new matter. It really is alchemy. So like protons go in,
• 8:33
  Speaker 1: you have this intermediate state of frothing energy, and then
• 8:36
  Speaker 1: you can make whatever the universe can make, dark matter, muons,
• 8:41
  Speaker 1: all sorts of other stuff. You're not just rearranging the protons.
• 8:44
  Speaker 3: There's got to be some rules right for what you
• 8:46
  Speaker 3: can make.
• 8:49
  Speaker 1: Yes, exactly, that's the whole premise of particle physics. There
• 8:51
  Speaker 1: are rules, there are patterns. Quantum mechanics tells us what's
• 8:55
  Speaker 1: likely to happen in certain collisions. We look at those patterns,
• 8:58
  Speaker 1: we notice, oh, this typically happens, typically shoots out at
• 9:00
  Speaker 1: those angles.
• 9:01
  Speaker 2: What are the rules that control this?
• 9:03
  Speaker 1: Absolutely there are rules, but fundamentally it's random. Right, Like
• 9:07
  Speaker 1: you do the same collision twice, you get two different answers.
• 9:10
  Speaker 1: Because it's quantum mechanical, it's not determined by the initial conditions.
• 9:15
  Speaker 1: So it's really a very powerful way to explore the
• 9:18
  Speaker 1: universe because you don't have to know what's out there
• 9:21
  Speaker 1: in order to discover it. You smash protons together often enough,
• 9:24
  Speaker 1: eventually everything the universe can do, it will do, and
• 9:28
  Speaker 1: you get to take pictures of it.
• 9:29
  Speaker 3: Wow.
• 9:30
  Speaker 1: It's like, imagine if you could build a box and
• 9:33
  Speaker 1: every kind of creature that could exist on Earth would
• 9:36
  Speaker 1: randomly cycle through that box. You could just sit there
• 9:39
  Speaker 1: and watch and be like, oh, wow, I didn't know
• 9:40
  Speaker 1: that existed. Oh look at those things.
• 9:42
  Speaker 2: What are those? You know?
• 9:44
  Speaker 1: That would be pretty powerful. That's basically what we can
• 9:46
  Speaker 1: do with particle physics.
• 9:47
  Speaker 3: Now you have my attention. Although that box, I guess,
• 9:49
  Speaker 3: could mostly be showing me like different species of bacteria,
• 9:52
  Speaker 3: which would be a bomber. You could show me different
• 9:54
  Speaker 3: speceis of bugs, that would be great.
• 9:55
  Speaker 1: Yeah, it'd be mostly beetles. You're like, wow, it's basically
• 9:58
  Speaker 1: a beetle box.
• 9:58
  Speaker 2: Right.
• 10:00
  Speaker 3: So there is that famous saying that like God is
• 10:02
  Speaker 3: inordinately fond of beetles, because there's this thought that beetles
• 10:06
  Speaker 3: are the most common species group on the planet, but
• 10:09
  Speaker 3: actually quite often those beetles are infected by more than
• 10:13
  Speaker 3: one species of hymenopter and wasp, and so we think
• 10:17
  Speaker 3: there might actually be more wasp species on the planet
• 10:20
  Speaker 3: than there are beetles based on that observation.
• 10:23
  Speaker 1: And probably those wasps are infected by viruses, so they're
• 10:26
  Speaker 1: more viruses than wasps. Yes, and those viruses are made
• 10:30
  Speaker 1: of particles, and boom a boom, we're back to the
• 10:33
  Speaker 1: topic of the episode.
• 10:34
  Speaker 3: Well, what makes up a particle, Daniel exactly?
• 10:37
  Speaker 1: So we smash particles together, we look at what's inside them,
• 10:40
  Speaker 1: we annihilate them to make new kinds of particles. We
• 10:43
  Speaker 1: have this idea that particles are what everything is made
• 10:46
  Speaker 1: out of. But I struggle, still after decades in this field,
• 10:49
  Speaker 1: to understand this basic question what is a particle?
• 10:54
  Speaker 2: So I really want to explain to.
• 10:55
  Speaker 1: People what we do know and what we still don't
• 10:57
  Speaker 1: know about this very basic concept that everybody talks about
• 11:00
  Speaker 1: all the time.
• 11:01
  Speaker 3: Well, first, let's hear what our listeners think. And if
• 11:03
  Speaker 3: you would like to be a listener who tells us
• 11:06
  Speaker 3: what you think, send us an email at questions at
• 11:09
  Speaker 3: Daniel and Kelly dot org and we will get you
• 11:12
  Speaker 3: in the loop and send you a question from time
• 11:14
  Speaker 3: to time and you can send us your answers. So
• 11:16
  Speaker 3: let's see hear how folks answer the question what is
• 11:19
  Speaker 3: a particle?
• 11:20
  Speaker 2: A particle is a thing that interacts with other things.
• 11:24
  Speaker 1: A particle is really just an excitation in a field.
• 11:29
  Speaker 2: A particle is a defined portion of something, something that
• 11:35
  Speaker 2: is infinitesanly small to us.
• 11:39
  Speaker 1: It's the smallest unit of energy or mass.
• 11:43
  Speaker 3: I think that particles are the excitement of different friends,
• 11:46
  Speaker 3: spatial spots, and interaction.
• 11:49
  Speaker 2: A particle could be very small vibrating field. A mass
• 11:52
  Speaker 2: or non mess object.
• 11:54
  Speaker 1: Exists within what we would perceive as matter.
• 11:59
  Speaker 4: A particle is a sub microscopic kernel of energy and
• 12:05
  Speaker 4: or matter. A particle is an excitation of a field.
• 12:10
  Speaker 4: I do know that particles aren't just tiny bits of matter.
• 12:14
  Speaker 4: I've heard that there fields, or strings, or some other
• 12:22
  Speaker 4: impossible to understand little bits of the universe.
• 12:27
  Speaker 2: Particle is a ripple and a quantum field. Particle is
• 12:33
  Speaker 2: the name we give to the smallest discrete, quantum little
• 12:37
  Speaker 2: bits that we know of and haven't been able to
• 12:40
  Speaker 2: break up.
• 12:41
  Speaker 3: Further yet, an expression of a field where the chances
• 12:46
  Speaker 3: of that occurrence happening is the greatest. There. The more
• 12:51
  Speaker 3: think about, the bigger this rabbit warren is going.
• 12:54
  Speaker 1: I think these answers perfectly encapsulate this episode. I mean, really,
• 12:58
  Speaker 1: it's an excellent snapshot because a lot of what people
• 13:00
  Speaker 1: have said in here is correct. But also there's a
• 13:03
  Speaker 1: huge list of conflicting answers, right, you know, is it
• 13:06
  Speaker 1: the smallest bit of stuff? Is it just something in
• 13:08
  Speaker 1: space time? Is it actually an excitation of a field?
• 13:11
  Speaker 1: You know, there's so many conflicting concepts for what a particle.
• 13:14
  Speaker 3: Is, and is this one of those topics where at
• 13:16
  Speaker 3: the end the answer is going to be we really
• 13:19
  Speaker 3: have no idea, could be all of these things? Or
• 13:22
  Speaker 3: is this a topic we're at the end. We're going
• 13:24
  Speaker 3: to have a pretty clear answer.
• 13:27
  Speaker 2: At the end.
• 13:28
  Speaker 1: We're going to have a pretty clear answer, but not
• 13:29
  Speaker 1: at the end of this episode, at the end of
• 13:31
  Speaker 1: this journey, which might be in ten or one hundred
• 13:34
  Speaker 1: years unfortunately. Okay, I mean we're going to get somewhere.
• 13:38
  Speaker 1: Today we have a pretty crisp clear view of what
• 13:41
  Speaker 1: a particle is mathematically, but we also know why that's
• 13:44
  Speaker 1: not really satisfactory, and there's lots of big open questions
• 13:47
  Speaker 1: about what that really means. So it's not like all
• 13:50
  Speaker 1: particle physics is a scam because we don't know what
• 13:52
  Speaker 1: a particle is. We have a working definition, but we
• 13:54
  Speaker 1: also know that it's incomplete, just like most of science.
• 13:57
  Speaker 3: Right, Oh yeah, amen, All right, well, so let's start
• 13:59
  Speaker 3: with the historical perspective. Bring me back to the beginning.
• 14:02
  Speaker 3: When did we start thinking about this question?
• 14:04
  Speaker 1: Yeah, I think it's important to trace the origin of
• 14:06
  Speaker 1: this historically because it still shapes how we think about
• 14:10
  Speaker 1: the universe. And you know, whenever you ask a big
• 14:12
  Speaker 1: question about science, you got to think about like what
• 14:14
  Speaker 1: kind of answer you're looking for.
• 14:17
  Speaker 2: And in science, even though.
• 14:18
  Speaker 1: We try to be like mathematical and open minded and
• 14:22
  Speaker 1: let the data tell us what the universe is saying,
• 14:25
  Speaker 1: we still need to understand that data. We still need
• 14:28
  Speaker 1: to interpret it. We still need to cogitate on it
• 14:30
  Speaker 1: in a way that makes sense to us. And we're
• 14:32
  Speaker 1: sort of limited in our mental intuitive language. We can't
• 14:36
  Speaker 1: really grapple with things that we've never experienced, that are
• 14:40
  Speaker 1: completely alien to us. We tend to translate the unfamiliar
• 14:44
  Speaker 1: into the familiar.
• 14:46
  Speaker 4: You know.
• 14:46
  Speaker 1: My favorite example of this is like what happens when
• 14:48
  Speaker 1: you drink a wine or you taste a new fruit
• 14:51
  Speaker 1: and you're like, oh, this fruit tastes kind of like
• 14:52
  Speaker 1: a cherry and kind of like an apricot and whatever,
• 14:54
  Speaker 1: and a little bit like a kiwi. You're explaining something
• 14:57
  Speaker 1: new in terms of something you already know, and that
• 15:00
  Speaker 1: makes a lot of sense also what we do in science,
• 15:02
  Speaker 1: and so it's important like dig into like what are
• 15:04
  Speaker 1: the sort of basic mental building blocks we're using to
• 15:07
  Speaker 1: understand this stuff.
• 15:08
  Speaker 3: I think one of my favorite examples of that is
• 15:10
  Speaker 3: the brain being compared to whatever technology is hot and
• 15:13
  Speaker 3: new at the time. You know, like your brain is
• 15:14
  Speaker 3: like a clock, your brain is like a computer. And
• 15:17
  Speaker 3: some of those analogies work in some ways, but you know,
• 15:20
  Speaker 3: having an analogy like that sometimes limits the way you
• 15:22
  Speaker 3: actually attack a problem.
• 15:23
  Speaker 1: Yeah, but it also is what allows you to understand it, right,
• 15:26
  Speaker 1: So in the end, it's sort of how we understand everything. Yeah,
• 15:29
  Speaker 1: And that's why it's useful to go back to like
• 15:32
  Speaker 1: fifth century BC and talk about Democratus and his buddy Lucepis,
• 15:37
  Speaker 1: because these folks were thinking about, hey, what is the
• 15:39
  Speaker 1: universe made out of? And they came up with this concept,
• 15:42
  Speaker 1: or they're credited with this concept of what seems like
• 15:46
  Speaker 1: smooth and continuous matter, you know, water, seems smooth and continuous.
• 15:50
  Speaker 1: Air seems smooth is actually made of tiny little bits
• 15:54
  Speaker 1: of stuff. This is a big idea, right, This is
• 15:57
  Speaker 1: a huge concept. It is like pulling back the veil
• 15:59
  Speaker 1: on the world and saying the world isn't the way
• 16:02
  Speaker 1: that it seems. It's actually quite different. You know, it
• 16:05
  Speaker 1: has like a resolution. These days, we're kind of familiar
• 16:07
  Speaker 1: with this because you're used to things like, Hey, I
• 16:09
  Speaker 1: look at my TV screen. It looks like I'm just
• 16:11
  Speaker 1: looking at a picture, but I know that if I
• 16:13
  Speaker 1: put my eyeball closed to the screen, I'll see pixels.
• 16:17
  Speaker 1: This is basically saying the whole world, all matter is
• 16:19
  Speaker 1: actually pixelated. It's built out of little bits instead of
• 16:23
  Speaker 1: smooth and continuous.
• 16:24
  Speaker 3: Did they have any thoughts about what the little bits
• 16:28
  Speaker 3: were like, like do you get different bits in the
• 16:30
  Speaker 3: sand and different bits in your skin? Or how fine
• 16:34
  Speaker 3: grained was this idea?
• 16:35
  Speaker 2: Oh my god?
• 16:36
  Speaker 1: They had hilarious ideas about what the little bits were.
• 16:39
  Speaker 1: They thought that everything was made up a little bit
• 16:41
  Speaker 1: of stuff, but that stuff had different shapes, and you know,
• 16:44
  Speaker 1: they were right on the spirit of it that they thought,
• 16:47
  Speaker 1: like the properties of the shape determined how we experienced
• 16:50
  Speaker 1: it and its property. But for example, they thought that
• 16:52
  Speaker 1: something's tasted sour because it was made of little sharp
• 16:56
  Speaker 1: needle shaped atoms that like stabbed your tongue when you
• 16:59
  Speaker 1: ate it.
• 17:00
  Speaker 3: This is going to be so condescending, but that's such
• 17:02
  Speaker 3: a cute idea.
• 17:03
  Speaker 2: It is so cute, I know.
• 17:05
  Speaker 1: And they thought that things that were white were white
• 17:08
  Speaker 1: because they were made of very smooth atoms. And they
• 17:12
  Speaker 1: thought that your soul was made of atoms, and that
• 17:14
  Speaker 1: those atoms were particularly fine grained. They were right in
• 17:17
  Speaker 1: the spirit in that the behavior and the structure of
• 17:21
  Speaker 1: the atom really does determine, like hey, what is shiny
• 17:24
  Speaker 1: and what conducts electricity and what's liquid at room temperature.
• 17:27
  Speaker 1: That's all true. They were just wrong on the details.
• 17:30
  Speaker 1: But you know, they couldn't see atoms. They were just imagining.
• 17:33
  Speaker 1: And I'm really impressed by this. I'm impressed by the
• 17:36
  Speaker 1: courage to imagine that the universe is so fundamentally different
• 17:39
  Speaker 1: from the way it seems, because that's really the scientific spirit, right, Yeah, totally.
• 17:44
  Speaker 3: Okay, So we've got Democritus and his buddy what was
• 17:48
  Speaker 3: the buddy's.
• 17:48
  Speaker 1: Name mispronounced as Lacoupiskopis, But I don't know the correct pronunciation.
• 17:53
  Speaker 3: I hadn't heard of that person before. So you got
• 17:55
  Speaker 3: the two of them, and they're proposing that everything is
• 17:58
  Speaker 3: made of small bits of stuff. How long before we
• 18:01
  Speaker 3: get some clarity on the fact that sour isn't just
• 18:04
  Speaker 3: sharp little bits of stuff.
• 18:07
  Speaker 1: Yeah, so they're credited with this idea, probably came up
• 18:11
  Speaker 1: earlier because remember, we give people credit because we have
• 18:13
  Speaker 1: a written.
• 18:14
  Speaker 2: Record of it.
• 18:15
  Speaker 1: We have like a tiny fraction of everything the Greeks wrote,
• 18:18
  Speaker 1: though very excitingly, they're now scanning burnt scrolls from an
• 18:21
  Speaker 1: ancient Greek library. We're going to like double the amount
• 18:24
  Speaker 1: of Greek writing.
• 18:24
  Speaker 2: We have very soon.
• 18:26
  Speaker 1: But also, you know, we just don't have writing from
• 18:28
  Speaker 1: other civilizations. What do the Etruscans think ancient Chinese writing? So,
• 18:32
  Speaker 1: you know, people give the Greeks a lot of credit,
• 18:33
  Speaker 1: but we should remember like other people thought about this
• 18:35
  Speaker 1: stuff too.
• 18:36
  Speaker 3: Ain't that always the way?
• 18:37
  Speaker 2: It's always the way, I know.
• 18:39
  Speaker 1: And they use the word adam because atomos in Greek
• 18:42
  Speaker 1: means indivisible, So that's where that comes from. And this
• 18:45
  Speaker 1: is the origin of this idea that you know, smooth
• 18:47
  Speaker 1: stuff is actually made of little bits and that still
• 18:51
  Speaker 1: guides our mental picture. When I think particle, I still
• 18:54
  Speaker 1: think tiny little dot of stuff, like a little spinning
• 18:57
  Speaker 1: ball or a grain of sand.
• 18:59
  Speaker 2: That's what it means to me.
• 19:01
  Speaker 1: Like it's particular, Like if you say something is particulate, right,
• 19:04
  Speaker 1: you mean it's made of these little bits. And so
• 19:07
  Speaker 1: the words are powerful because they guide our mental images.
• 19:10
  Speaker 1: But it wasn't for a couple of thousand years that
• 19:12
  Speaker 1: we had really more information. I mean it was chemists
• 19:16
  Speaker 1: like Dalton who were doing experiments on chemical reactions and discovering,
• 19:20
  Speaker 1: you know, laws of ratios and proportions and the things
• 19:24
  Speaker 1: were divisible by integers. That really give us a clue that, oh,
• 19:28
  Speaker 1: there were like units of stuff going into these equations
• 19:31
  Speaker 1: that you really needed two to one hydrogen to oxygen
• 19:35
  Speaker 1: to make a certain amount of water. It gives you
• 19:36
  Speaker 1: a clue that it really has just clicked together out
• 19:38
  Speaker 1: of these tiny little bits. So that was a really
• 19:40
  Speaker 1: important clue. But it wasn't until the late eighteen hundreds
• 19:44
  Speaker 1: that we really had the discovery of anything that we
• 19:46
  Speaker 1: would today call a particle.
• 19:49
  Speaker 3: And is that because it's so tiny, it probably depends
• 19:52
  Speaker 3: on having the right technology to be able to address
• 19:54
  Speaker 3: that and so did we just have to wait until
• 19:57
  Speaker 3: the late eighteen hundreds because that's when we finally got
• 20:00
  Speaker 3: the technology where we could start making a dent.
• 20:02
  Speaker 2: Yeah. Absolutely.
• 20:03
  Speaker 1: And in the great tradition of particle physics, we didn't
• 20:06
  Speaker 1: invent the technology that we used to make these discoveries.
• 20:09
  Speaker 2: We borrowed it. In this case, we borrowed it from
• 20:11
  Speaker 2: the circus.
• 20:12
  Speaker 3: From the circus, yes, exactly. All Right, we're going to
• 20:16
  Speaker 3: take a break, and when we come back, you're going
• 20:18
  Speaker 3: to tell me about how the circus allowed us to
• 20:21
  Speaker 3: understand the electron. All right, and we're back, and today
• 20:40
  Speaker 3: we're talking about the freak show that is particles, and
• 20:43
  Speaker 3: Daniel's gonna tell us about how we were able to
• 20:46
  Speaker 3: understand the electron from technology developed for the circus mm HM.
• 20:52
  Speaker 1: Back in the mid eighteen hundreds, there were circuses, and
• 20:54
  Speaker 1: there were these side shows, and you know, you had
• 20:57
  Speaker 1: bearded ladies or conjoined twins or whatever freak show you
• 20:59
  Speaker 1: wanted to see, but also you had people with weird gizmos,
• 21:03
  Speaker 1: and in particular, somebody invented basically the cathode ray tube,
• 21:07
  Speaker 1: but a cathoid ratube back then was actually called a
• 21:09
  Speaker 1: Crooks tube. And basically you have a glass and you
• 21:11
  Speaker 1: put electricity on one side, electricity on the other side,
• 21:15
  Speaker 1: and we now know what happens is that electrons boil
• 21:18
  Speaker 1: off of one and fly through it.
• 21:20
  Speaker 2: And hit the other.
• 21:21
  Speaker 1: But if you left a little bit of gas in
• 21:23
  Speaker 1: that tube, then the electrons would hit that gas and
• 21:26
  Speaker 1: gas would glow. People were making these tubes because they
• 21:28
  Speaker 1: glowed in this eerie way and that was pretty cool.
• 21:32
  Speaker 1: And you know, back in the eighteen hundreds, this was
• 21:34
  Speaker 1: a magical thing to see that somebody could build this
• 21:37
  Speaker 1: thing and it would glow green, it would glow red
• 21:39
  Speaker 1: or whatever. And so these Crooks tubes were very popular
• 21:43
  Speaker 1: on side shows. And then later scientists were like, what's
• 21:47
  Speaker 1: going on here, Let's see if we can understand what's
• 21:49
  Speaker 1: going on. And JJ Thompson in the late eighteen hundreds
• 21:52
  Speaker 1: used it to discover the electron.
• 21:54
  Speaker 3: How do you go from ohnit that tube lights up
• 21:57
  Speaker 3: to and that's because of electrons.
• 22:00
  Speaker 1: Yeah, So JJ Thompson was trying to understand what is
• 22:04
  Speaker 1: lighting up here. And they already called these things cathode
• 22:06
  Speaker 1: rays because they could see paths, like definitely, there's a
• 22:10
  Speaker 1: line of stuff moving through them. And they were like,
• 22:12
  Speaker 1: what are these rays? Is it made of something? A
• 22:14
  Speaker 1: lot of people tried to understand this and failed, But
• 22:16
  Speaker 1: he had like the best vacuum, so the best control
• 22:19
  Speaker 1: of this experiment, and he did it the most systematically.
• 22:22
  Speaker 1: What he did was he put these tubes under electric
• 22:25
  Speaker 1: fields and he was like, hmm, can I bend these rays?
• 22:27
  Speaker 1: And then he tried with magnetic fields, like, oh, can
• 22:29
  Speaker 1: I bend the rays this way and that way? And
• 22:31
  Speaker 1: he tried with combinations of them. And so we had
• 22:34
  Speaker 1: an understanding of electromagnetism back then. We understood that electric
• 22:38
  Speaker 1: fields whole things that have charge, and magnetic fields can
• 22:41
  Speaker 1: bend them. So from this he determined, oh, these cathode
• 22:44
  Speaker 1: rays are little bits of charge. There's charge flowing here
• 22:48
  Speaker 1: because I can bend it with fields, and so that
• 22:51
  Speaker 1: was really fascinating. And then he very carefully bounced the
• 22:54
  Speaker 1: two fields and he was able to measure the mass
• 22:56
  Speaker 1: of the thing, and that right there is the origin
• 22:59
  Speaker 1: of this sort of concept of a particle. He was like, oh,
• 23:02
  Speaker 1: these rays are made of tiny little bits of stuff
• 23:05
  Speaker 1: that have a charge and a mass. And what he's
• 23:08
  Speaker 1: doing conceptually there is very important. He's saying there's a
• 23:11
  Speaker 1: point in space, and I'm going to put two labels
• 23:13
  Speaker 1: on it. I'm gonna say it has a charge and
• 23:15
  Speaker 1: has a mass, and those two things cannot be separated.
• 23:18
  Speaker 1: He tried to separate the mass and the charge and
• 23:20
  Speaker 1: he couldn't. So he's like, now in his mind, he
• 23:22
  Speaker 1: has these little dots that are moving through space and
• 23:24
  Speaker 1: he's putting these mental labels on them. And that's really
• 23:27
  Speaker 1: the origin of the modern concept of a particle.
• 23:30
  Speaker 3: Okay, So I'm imagining being in his lab He's got
• 23:33
  Speaker 3: this ray, he's got a magnet on one side, and
• 23:36
  Speaker 3: he does the magic, and he's got that line. Is
• 23:39
  Speaker 3: it like a bolt of lightning? Like does it go
• 23:42
  Speaker 3: from one side to another and you can see all
• 23:44
  Speaker 3: of it? And if so, how does he make the
• 23:45
  Speaker 3: jump from there's a line that lights up and bends
• 23:48
  Speaker 3: towards the magnet two, And that line is made up
• 23:51
  Speaker 3: of lots of little tiny things that come to be
• 23:54
  Speaker 3: called electrons, You know what I mean.
• 23:56
  Speaker 1: Yes, So what you should be imagining is sort of
• 23:58
  Speaker 1: like what a fluorescent life. Well it looks like now,
• 24:01
  Speaker 1: it's like long and thin and filled with glowing gas, right,
• 24:04
  Speaker 1: except there were like thinner lines. So these were very
• 24:06
  Speaker 1: clearly rays. And you're right that he measured that there's
• 24:10
  Speaker 1: sort of a flow of charge. Right, So there was
• 24:12
  Speaker 1: a screen on one end and you could see these
• 24:14
  Speaker 1: glowing dots landing. But he also measured the mass. That's
• 24:18
  Speaker 1: what told him that this was made of little bits
• 24:21
  Speaker 1: because he could measure actually their charge to mass ratio.
• 24:24
  Speaker 1: He couldn't measure the mass itself, but he measured the
• 24:26
  Speaker 1: charge to mass ratio by seeing how much they were
• 24:29
  Speaker 1: deflected by the magnetic fields.
• 24:31
  Speaker 2: That's the thing that.
• 24:31
  Speaker 1: Gave him the clue that it was made of little bits,
• 24:34
  Speaker 1: not just some continuous stream, because he could identify a
• 24:37
  Speaker 1: charge to mass ratio for these bits. And he almost
• 24:40
  Speaker 1: sent the world down a crazy path where my job
• 24:43
  Speaker 1: title would be different because he didn't call this thing
• 24:46
  Speaker 1: a particle, he didn't call it an electron. He used
• 24:49
  Speaker 1: the word corpuscule. He thought that was a really cool
• 24:52
  Speaker 1: name for this thing that he help. To me, it
• 24:58
  Speaker 1: sounds like especially explosive kind of Yeah.
• 25:00
  Speaker 3: Yeah, so you were almost a corpuscoologist.
• 25:08
  Speaker 1: Or a corpuscular physicist. Fortunately, the person who discovers the
• 25:12
  Speaker 1: thing doesn't always get to name it, and later on
• 25:15
  Speaker 1: people adopted the name electron suggested by Fitzgerald and Lorentz
• 25:20
  Speaker 1: and other folks, and so fortunately the word corpuscular didn't
• 25:25
  Speaker 1: hang on. But that was really the seminal experiment where
• 25:28
  Speaker 1: people discovered, okay, the world has made the little bits,
• 25:30
  Speaker 1: and we can put labels on them. And these days
• 25:33
  Speaker 1: we have so many labels for particles. We put spin
• 25:36
  Speaker 1: on them, we put charge. Of course, we put other
• 25:38
  Speaker 1: kinds of charge. Every particle has a charge for electromagnetism,
• 25:42
  Speaker 1: as a charge for the weak force, a charge for
• 25:44
  Speaker 1: the strong force. It has a mass. This is really
• 25:47
  Speaker 1: part of the concept of a particle is a little
• 25:49
  Speaker 1: dot in space with labels that we put on it.
• 25:52
  Speaker 3: And it sounds like it gets complicated pretty quick. So
• 25:55
  Speaker 3: let's back up a little bit. So we've got mass
• 25:57
  Speaker 3: in charge. What is our next historical advancement?
• 26:02
  Speaker 1: Well, next came Rutherford because people were wondering, all right,
• 26:05
  Speaker 1: so these things exist, these corpus s gules, or these
• 26:08
  Speaker 1: electrons as we they to call them. But how do
• 26:10
  Speaker 1: you use that to make up the world. It's sort
• 26:13
  Speaker 1: of like the twofold question we were talking about before.
• 26:15
  Speaker 1: One thing you can do is try to answer, like,
• 26:17
  Speaker 1: what is everything around us made out of by taking
• 26:19
  Speaker 1: it apart. The other is just to ask what can
• 26:22
  Speaker 1: the universe do? Like, not necessarily, how am I built
• 26:25
  Speaker 1: out of the universe, but what is the universe capable of?
• 26:28
  Speaker 1: Sort of holistically, And so Thompson discovered, oh, the universe
• 26:31
  Speaker 1: can make electrons. People were wondering, Okay, are those electrons part.
• 26:35
  Speaker 2: Of who we are?
• 26:37
  Speaker 1: And you know, they were speculating, we think electrons are
• 26:39
  Speaker 1: probably inside the atom. But nobody knew yet what the
• 26:42
  Speaker 1: atom structure was. We knew that we had chemicals and
• 26:45
  Speaker 1: we had these different atoms and periodic table the elements
• 26:48
  Speaker 1: was a thing, but nobody understood how the atom itself
• 26:51
  Speaker 1: was built. And we suspected electrons were in there, but
• 26:53
  Speaker 1: we didn't understand, like, well, what's balancing that charge? And
• 26:56
  Speaker 1: so Thompson proposed that, like, well, we have electrons because
• 27:00
  Speaker 1: I discovered them, and so they must be the building
• 27:01
  Speaker 1: block of everything, and they're embedded in like a jelly,
• 27:05
  Speaker 1: like a positive jelly that balances the charge.
• 27:08
  Speaker 2: That was sort of his idea.
• 27:09
  Speaker 1: But then Rutherford came along and said, well, let's see,
• 27:13
  Speaker 1: and he took a sheet of gold foil and he
• 27:14
  Speaker 1: shot radiation at it, and he wanted to understand, like,
• 27:18
  Speaker 1: what is that positive stuff made out of And if
• 27:21
  Speaker 1: that positive stuff was like spread out like jelly, then
• 27:25
  Speaker 1: he would expect that his particle would mostly just slop
• 27:28
  Speaker 1: through it. But what he saw was that most of
• 27:30
  Speaker 1: the time they just shoot right through the foil, but
• 27:32
  Speaker 1: occasionally they bounced right back. What he concluded from that
• 27:36
  Speaker 1: was that the positive charges weren't spread out evenly. They
• 27:38
  Speaker 1: were clustered into these little hard dots. So most of
• 27:41
  Speaker 1: the time the radiation missed it, sometimes they bounced right back.
• 27:46
  Speaker 1: That gives us the more modern picture of the atom
• 27:48
  Speaker 1: as a positive nucleus surrounded by electrons.
• 27:51
  Speaker 3: Okay, so if we are still trying to think of
• 27:53
  Speaker 3: this as a jelly, then we should be picturing like
• 27:55
  Speaker 3: that strawberry jelly that has seeds in it, and those
• 27:59
  Speaker 3: seeds are like the nucleus that the electron was bouncing
• 28:02
  Speaker 3: off of. Is that right?
• 28:03
  Speaker 2: M hmm exactly.
• 28:04
  Speaker 1: And so now we have like electrons, and we also
• 28:07
  Speaker 1: have the nucleus, which later on we discover is made
• 28:09
  Speaker 1: out of protons and neutrons. And so you were starting
• 28:13
  Speaker 1: to build up our catalog of particles to try to
• 28:16
  Speaker 1: understand like what is the world made out of? What
• 28:18
  Speaker 1: are these particles? And at this point the concept of
• 28:20
  Speaker 1: a particle is still it's a dot in space that
• 28:23
  Speaker 1: we could put labels on, and one of those labels
• 28:26
  Speaker 1: is mass. But then that was all up ended when
• 28:29
  Speaker 1: we discovered the next particle, which is the photon.
• 28:32
  Speaker 3: Why does it always get more complicated?
• 28:34
  Speaker 2: I know?
• 28:35
  Speaker 1: Photons mess everything up, right, my goodness. So around the
• 28:38
  Speaker 1: turn of the century, Einstein was thinking about what happens
• 28:41
  Speaker 1: when you shine light on metal, very bright beam of
• 28:45
  Speaker 1: light on metal. What happens is electrons boil off. This
• 28:48
  Speaker 1: is something people had seen but not really understood because
• 28:52
  Speaker 1: they were confusing results about what happened when you made
• 28:54
  Speaker 1: the beam brighter. People expected that if you make the
• 28:56
  Speaker 1: beam brighter, which if light is a wave, mean that
• 29:00
  Speaker 1: the em fields are oscillating with larger amplitude, so more energy.
• 29:05
  Speaker 1: Then they thought that electrons should get kicked off with
• 29:07
  Speaker 1: more energy. But instead what they saw was electrons kicked
• 29:11
  Speaker 1: off with the.
• 29:11
  Speaker 2: Same energy, but more of them.
• 29:13
  Speaker 1: So instead of having faster moving electrons, you have more
• 29:16
  Speaker 1: electrons at all the same speed. And it was Einstein
• 29:19
  Speaker 1: who figured out what that meant. What it means is
• 29:23
  Speaker 1: that the light you're shining at the metal is not
• 29:25
  Speaker 1: a continuous beam, perfectly smooth the way Maxwell imagined, but
• 29:30
  Speaker 1: made of chunks made of bits called photons. And what
• 29:33
  Speaker 1: was happening is that each electron can only absorb one
• 29:37
  Speaker 1: like the electron absorbs a photon or it doesn't.
• 29:39
  Speaker 2: If it absorbs a photon.
• 29:40
  Speaker 1: It gets kicked off, and it always has that photon's energy.
• 29:43
  Speaker 1: You can't eat two photons or ten photons, and so
• 29:46
  Speaker 1: when you make the being brighter, you're shooting more photons.
• 29:49
  Speaker 1: More electrons get to eat a photon. But because it's
• 29:53
  Speaker 1: based out of these chunks, it's not smooth and continuous.
• 29:56
  Speaker 1: It's basically a one on one interaction.
• 29:58
  Speaker 3: You said that was Einstein who helps figure outright, So
• 30:00
  Speaker 3: that wasn't that long ago one hundred years. Yeah, we
• 30:02
  Speaker 3: went from like nothing to amazing detail in the last
• 30:06
  Speaker 3: hundred years.
• 30:06
  Speaker 4: I know.
• 30:07
  Speaker 1: It's really incredible what we've understood. And this is a
• 30:09
  Speaker 1: huge advance because now we're like, oh wow, light is
• 30:12
  Speaker 1: also made of little mini servings. Right, there's a minimum
• 30:15
  Speaker 1: amount of light. Like you take a flashlight and you
• 30:18
  Speaker 1: start to turn it down and down and down and down.
• 30:20
  Speaker 1: You can't have it be arbitrarily dim like this one
• 30:24
  Speaker 1: setting where it's dark, completely dark, but then there's a
• 30:27
  Speaker 1: minimum brightness. You can't shoot half a photon out of
• 30:30
  Speaker 1: a flashlight or one and a half photons. It's quantized,
• 30:34
  Speaker 1: you know, it's not continuous and smooth. But this is
• 30:37
  Speaker 1: confusing because they were going to call a photon a
• 30:39
  Speaker 1: particle a minute ago. We set a particle something that
• 30:42
  Speaker 1: has like mass in charge. Photons don't have mass, So
• 30:46
  Speaker 1: already your mental conception of like, oh, a particle is
• 30:49
  Speaker 1: a little bit of stuff, Well, this boton doesn't have
• 30:52
  Speaker 1: any stuff to it. You know, you can't catch up
• 30:56
  Speaker 1: to a photon and look at it, you can't hold
• 30:57
  Speaker 1: it in your hand, and yet we think of it.
• 31:00
  Speaker 2: As a particle. So already one hundred years.
• 31:03
  Speaker 1: Ago, we have to like back up and broaden our understanding,
• 31:06
  Speaker 1: like what is a particle if it's not a little
• 31:08
  Speaker 1: bit of stuff the way Democratis was imagining.
• 31:10
  Speaker 3: And doesn't it get even more confusing yet, because then
• 31:13
  Speaker 3: we decide that photons aren't necessarily particles. Sometimes maybe they're waves.
• 31:17
  Speaker 3: And at this point you're like, I'm majoring in biology.
• 31:22
  Speaker 1: It gets more confusing before it gets more interesting and
• 31:26
  Speaker 1: more clear. But yes, there's definitely a period of confusion there,
• 31:29
  Speaker 1: and I do think that's kind of a filter. Some
• 31:30
  Speaker 1: people hear that and they're like, I need to understand
• 31:32
  Speaker 1: this and learn more. I'm going to become a physicist.
• 31:34
  Speaker 1: And some people are like, I'm going to go study eels,
• 31:37
  Speaker 1: and that's cool because eels can make waves too, you know,
• 31:40
  Speaker 1: they're pretty.
• 31:41
  Speaker 3: Wiggly and electric fields and yeah.
• 31:43
  Speaker 2: Yeah, yeah.
• 31:44
  Speaker 1: And something you said I want to get back to,
• 31:46
  Speaker 1: which is like, sometimes they're particles. I mean, a photon
• 31:50
  Speaker 1: is always a photon. What is a photon? Is it
• 31:52
  Speaker 1: a particle? Is it a wave?
• 31:54
  Speaker 2: Like really, it's neither.
• 31:56
  Speaker 1: The way that that new fruit is not a cherry
• 31:58
  Speaker 1: or an apricot, it's not sometimes because it has hints
• 32:01
  Speaker 1: of it in your mouth. It's something new and weird.
• 32:03
  Speaker 1: And a photon has behaviors that we sometimes describe in
• 32:07
  Speaker 1: a particle way, and behaviors we sometimes describe in.
• 32:09
  Speaker 2: A wave like way.
• 32:10
  Speaker 1: But it's not choosing now I'm a wave, now I'm
• 32:13
  Speaker 1: a particle. It's always a photon. It's just that none
• 32:16
  Speaker 1: of these descriptions perfectly capture what it is the way
• 32:19
  Speaker 1: that like I can't perfectly describe you. I mean, you're
• 32:22
  Speaker 1: a mother, you're a partner, you're a podcaster. None of
• 32:25
  Speaker 1: those things define who you are. You're Kelly, right, and
• 32:28
  Speaker 1: you're sometimes well described by one of those labels.
• 32:31
  Speaker 3: Right, yes, right, So this is another one of those problems,
• 32:34
  Speaker 3: like brains are like a computer, yes, but not entirely.
• 32:37
  Speaker 3: And by putting these labels on it, sometimes it helps
• 32:40
  Speaker 3: you think about it, but also sometimes it makes things
• 32:41
  Speaker 3: more confusing.
• 32:42
  Speaker 1: So let's dig into what it means though, because the
• 32:44
  Speaker 1: thing people were trying to confront, the thing people were
• 32:46
  Speaker 1: struggling with is like, yeah, Einstein tells us light is
• 32:50
  Speaker 1: made out of these little packets, so we should think
• 32:52
  Speaker 1: of them as like individuals. But also we had all
• 32:54
  Speaker 1: these experiments showing that lighthead wave like behavior, you know,
• 32:58
  Speaker 1: it like interferes with itself, diffraction. There's all sorts of
• 33:01
  Speaker 1: stuff that we only usually attribute to waves, and so
• 33:05
  Speaker 1: people have this idea in their mind, and they hear
• 33:07
  Speaker 1: a lot about the particle wave duality that sometimes you
• 33:10
  Speaker 1: use wave to describe light and sometimes you use particles
• 33:12
  Speaker 1: to describe light. And later on it got more confusing
• 33:15
  Speaker 1: because we saw that electrons do this too, like electrons
• 33:18
  Speaker 1: have wave like behavior. You could take beams of electrons
• 33:21
  Speaker 1: and they will interfere with themselves as if they are waves.
• 33:24
  Speaker 1: But you know, electron is like the original og particle.
• 33:27
  Speaker 1: So what's going on here? And there is definitely a
• 33:30
  Speaker 1: way to.
• 33:31
  Speaker 2: Think about this that's not Sometimes it's a.
• 33:33
  Speaker 1: Wave and then it switches suddenly to a particle. It's
• 33:36
  Speaker 1: the more quantum mechanical way to think about it, which
• 33:38
  Speaker 1: is rarely like a way to think more clearly about stuff,
• 33:41
  Speaker 1: but you know, it is the way that we think
• 33:43
  Speaker 1: about it. And the quantum mechanical way to think about
• 33:46
  Speaker 1: this without getting heavy into the math, is to say
• 33:49
  Speaker 1: that what controls where a particle goes is a mathematical
• 33:52
  Speaker 1: equation that looks like a wave equation.
• 33:55
  Speaker 2: We call it the Schrodinger.
• 33:56
  Speaker 1: Equation, and it tells us what's likely to happen to
• 33:59
  Speaker 1: a particle. So an electron enters an experiment, the shorting
• 34:03
  Speaker 1: equation tells us, oh, is it likely to go left?
• 34:05
  Speaker 1: Or is it likely to go right? A photon goes
• 34:08
  Speaker 1: through a slit, the shortening equation tells us is it
• 34:10
  Speaker 1: likely to go here?
• 34:11
  Speaker 2: Is it likely to go there? It's going to land
• 34:13
  Speaker 2: on a screen.
• 34:14
  Speaker 1: The shortening equation tells us what's the probability of something happening,
• 34:18
  Speaker 1: So it's wave like in that an equation that looks
• 34:21
  Speaker 1: a lot like other wave equations, the equations we use
• 34:23
  Speaker 1: to describe oceans and sound and all sorts of wave
• 34:27
  Speaker 1: like behavior, which is amazingly everywhere in the universe. And
• 34:30
  Speaker 1: we can have a whole conversation about, like, why does
• 34:32
  Speaker 1: the universe all seem like waves? There's a wavy equation
• 34:35
  Speaker 1: that describes where this stuff is likely to go. But
• 34:39
  Speaker 1: then there's something weird that happens, which is the universe
• 34:42
  Speaker 1: has to go from here. All the things the photon
• 34:44
  Speaker 1: could do, and here's the various probabilities of it going
• 34:46
  Speaker 1: here or there. Then we do the experiment. We want
• 34:49
  Speaker 1: to know the answer. The universe does this thing where
• 34:51
  Speaker 1: it picks one. It's like, all, right, of all the possibilities,
• 34:54
  Speaker 1: I'm going to decide this photon goes over there, and
• 34:57
  Speaker 1: this other photon is going to go over here, and
• 34:59
  Speaker 1: this third photon is going to go there. And it's
• 35:01
  Speaker 1: sort of amazing and it's a process. We fundamentally do
• 35:03
  Speaker 1: not understand how the universe goes from Here's the list
• 35:06
  Speaker 1: of probabilities to I'm going to pick one. But this
• 35:09
  Speaker 1: is what people imagine when they think wave like to
• 35:11
  Speaker 1: particle like. Wavelike is like when the universe is still
• 35:13
  Speaker 1: maintaining all the possibilities. Particle like is like I've looked
• 35:17
  Speaker 1: at it, I've measured it, I see a dot on
• 35:19
  Speaker 1: the screen. So I'm thinking of it as acting like
• 35:21
  Speaker 1: a particle because it's here, has the location, and we
• 35:24
  Speaker 1: think of particles as like it is somewhere. It's a
• 35:27
  Speaker 1: tiny dot in space with labels. So when we force
• 35:30
  Speaker 1: the universe to tell us where did that photon go,
• 35:32
  Speaker 1: we call it being particle like because we put a
• 35:36
  Speaker 1: location on it.
• 35:37
  Speaker 3: Okay, And is this the right way to think about
• 35:40
  Speaker 3: all particles or do some particles follow this wave function
• 35:46
  Speaker 3: thing and other particles don't.
• 35:48
  Speaker 1: This is the nineteen thirties way to think about all particles.
• 35:51
  Speaker 1: You can use this to describe photons, you can use
• 35:54
  Speaker 1: it to describe electrons. You can do use to describe
• 35:56
  Speaker 1: any particle. This is the Shortener equation, and it works
• 35:59
  Speaker 1: really really well for individual particles, and these deep fundamental
• 36:02
  Speaker 1: problems with it still like we don't understand when the
• 36:05
  Speaker 1: universe goes from here are all your possibilities to actually,
• 36:08
  Speaker 1: we're going to do this one. People call this the
• 36:10
  Speaker 1: wave function collapse or quantum collapse, and philosophically it makes
• 36:14
  Speaker 1: no sense because it doesn't happen when a photon is
• 36:18
  Speaker 1: measured by a quantum particle. Like a photon can interact
• 36:21
  Speaker 1: with an electron and maintain all of its possibilities. But
• 36:24
  Speaker 1: if a photon hits an eyeball you see it here
• 36:27
  Speaker 1: or you don't see it there, it collapses. And so
• 36:30
  Speaker 1: really this wave versus particle thing is about maintaining quantum
• 36:34
  Speaker 1: possibilities or collapsing to one. That's really the core of it,
• 36:37
  Speaker 1: and that is not something we understand why that happens,
• 36:39
  Speaker 1: When that happens, If that happens, huge open question in
• 36:43
  Speaker 1: physics and in philosophy, and what is a particle sort
• 36:47
  Speaker 1: of sits right at the nexus of that. So we've
• 36:49
  Speaker 1: mapped this question of like what is a particle to hey,
• 36:53
  Speaker 1: when do quantum wave functions collapse?
• 36:54
  Speaker 2: And do they?
• 36:55
  Speaker 1: But that's not a question we have an answer to.
• 36:58
  Speaker 1: So I'm not sure how helpful it is. But the
• 37:00
  Speaker 1: modern view of what is a particle is actually a
• 37:03
  Speaker 1: little bit different from this sort of nineteen thirties concept
• 37:06
  Speaker 1: of a wave function and the Schrodinger equation.
• 37:09
  Speaker 3: Well, let's take a break and then we'll get modern.
• 37:27
  Speaker 3: So we are up to the nineteen thirties, and now
• 37:31
  Speaker 3: you are going to tell us about our more modern
• 37:34
  Speaker 3: understanding of particles.
• 37:36
  Speaker 1: Yes, so this idea that particles are these weird quantum
• 37:39
  Speaker 1: objects and where they go is controlled by a wavy equation.
• 37:44
  Speaker 1: But sometimes we can make their measurements and force the
• 37:46
  Speaker 1: universe to tell us where they are in an instant
• 37:49
  Speaker 1: and they have these properties masked sometimes charge, sometimes spin. Sometimes.
• 37:55
  Speaker 1: That's sort of an old fashioned view. When we started
• 37:58
  Speaker 1: dealing with lots and lots of particles discovered, Oh, this
• 38:01
  Speaker 1: math is kind of clunky. Like if you have ten
• 38:03
  Speaker 1: particles or one hundred particles, it becomes really awkward to
• 38:06
  Speaker 1: have a Shorteninger equation for each individual one and try
• 38:09
  Speaker 1: to bring it together. The math just becomes impossible. And
• 38:12
  Speaker 1: so people instead of thinking about like one wave function
• 38:15
  Speaker 1: for each particle, they're like, let's just think about all
• 38:18
  Speaker 1: the particles as if they're wiggling the same field. So
• 38:22
  Speaker 1: instead of imagining like an individual person waving their hand,
• 38:25
  Speaker 1: now imagine like a crowd at a football stadium and
• 38:27
  Speaker 1: they're doing the wave. So add this thing to your brain,
• 38:31
  Speaker 1: which is a field. Right, A field in space is
• 38:35
  Speaker 1: just like a set of numbers. I say, over here
• 38:37
  Speaker 1: to my left, the field has a value of seven,
• 38:39
  Speaker 1: and over here to my right field is a value
• 38:41
  Speaker 1: of three or two or whatever. And there are wavy
• 38:45
  Speaker 1: equations that determine what is the value of the field.
• 38:48
  Speaker 1: And so you can have waves in that field. You
• 38:50
  Speaker 1: can like ripples in that field where like a large
• 38:53
  Speaker 1: value of the field moves through space from here to there.
• 38:57
  Speaker 1: And then we think about particles as those ripples in
• 39:00
  Speaker 1: the field. So we take like individual wave functions, we
• 39:03
  Speaker 1: try to sort of stitch them together into a single
• 39:05
  Speaker 1: field and think about all the particles as wiggles in
• 39:08
  Speaker 1: the same field.
• 39:09
  Speaker 3: So what assumptions do you have to make to make
• 39:12
  Speaker 3: that transition? Do you have to assume that they don't
• 39:16
  Speaker 3: interact with each other in a way that changes the
• 39:19
  Speaker 3: behavior of the group?
• 39:20
  Speaker 2: Ah, great question.
• 39:22
  Speaker 1: You don't have to assume that, because you can have
• 39:24
  Speaker 1: lots of different kinds of fields. You can have some
• 39:25
  Speaker 1: fields where the particles don't interact with each other. For example, photons,
• 39:29
  Speaker 1: photons don't interact with each other. Photons only interact with
• 39:33
  Speaker 1: particles that have electric charge, like they will be eaten
• 39:36
  Speaker 1: by an electron or proton can give off a photon.
• 39:39
  Speaker 1: But photons ignore each other, like they wiggle right past
• 39:43
  Speaker 1: each other. Two beams of light cross without touching or
• 39:46
  Speaker 1: bouncing off each other. Other particles do interact with each other,
• 39:49
  Speaker 1: like gluons. For example, gluons bounce off of other gluons
• 39:53
  Speaker 1: amid other gluons eat other gluons. It gets very complicated
• 39:55
  Speaker 1: and messy because gluons talk to each other all the time.
• 39:59
  Speaker 1: So you don't have to assume that we build that
• 40:01
  Speaker 1: into each field. So we have a new mathematical framework
• 40:04
  Speaker 1: that allows us to make different kinds of fields. Some
• 40:07
  Speaker 1: fields are very simple, they're just numbers, like the Higgs field.
• 40:10
  Speaker 1: It's just a number in space. Other fields, like the
• 40:13
  Speaker 1: electromagnetic field. At every point in space, you have an arrow,
• 40:17
  Speaker 1: you have a direction, you have three numbers.
• 40:19
  Speaker 2: Basically.
• 40:20
  Speaker 1: So now imagine like a bunch of arrows filling space,
• 40:23
  Speaker 1: and when a photon is moving through that field, what's
• 40:26
  Speaker 1: happening is those arrows are growing and shrinking, They're changing direction.
• 40:30
  Speaker 1: It's oscillations. In these fields that we think about as particles.
• 40:34
  Speaker 1: But we do have to make one important assumption which
• 40:36
  Speaker 1: has a lot of consequences, which is that every electron
• 40:39
  Speaker 1: is basically the same and every photon is basically the
• 40:42
  Speaker 1: same because they're all part of the same field. It
• 40:45
  Speaker 1: was a question for a long time, like why does
• 40:47
  Speaker 1: every electron have exactly the same mass and exactly the
• 40:51
  Speaker 1: same charge? Why is every photon zero mass? Why are
• 40:54
  Speaker 1: they all identical?
• 40:55
  Speaker 2: Right?
• 40:56
  Speaker 1: And the answer is kind of beautiful as well. They're
• 40:58
  Speaker 1: all wiggles in the same field.
• 41:00
  Speaker 2: It's not like the.
• 41:01
  Speaker 1: Universe made a bunch of electrons and it was really
• 41:03
  Speaker 1: good at it, so it was super precise, and the
• 41:05
  Speaker 1: electron factories like high precision engineering, so they're really you know,
• 41:09
  Speaker 1: balls on perfect it's because they literally are the same
• 41:13
  Speaker 1: thing that are just ripples in the same field.
• 41:16
  Speaker 3: Well, that's convenient because it's easier to think of it
• 41:19
  Speaker 3: as a field, right than as a particle.
• 41:21
  Speaker 1: Mathematically, it's much easier because if you want to think
• 41:24
  Speaker 1: about like particles being created, oh, that's just energy going
• 41:27
  Speaker 1: into the field, whereas in the shirting equation it's like
• 41:29
  Speaker 1: pretty hard to create a particle and add its wave
• 41:32
  Speaker 1: function to your calculations, and the same thing with destroying particles.
• 41:35
  Speaker 1: It's really awkward if you're thinking about it one particle
• 41:38
  Speaker 1: at a time, and very natural if you're thinking about
• 41:40
  Speaker 1: it as a group of particles.
• 41:41
  Speaker 3: The universe threw us a softball. Thanks universe. Okay, So
• 41:46
  Speaker 3: when I was in high school, I learned about electrons
• 41:50
  Speaker 3: and protons and neutrons. I don't remember hearing about quarks.
• 41:54
  Speaker 3: But you know, since high school, I've learned that protons
• 41:57
  Speaker 3: are made up of quarks. But I think particles as
• 42:00
  Speaker 3: being the smallest things that make up everything. And so
• 42:04
  Speaker 3: if quirks make up protons, does that mean protons aren't
• 42:08
  Speaker 3: particles or are they both particles but maybe different categories
• 42:13
  Speaker 3: of particles? What's going on here?
• 42:15
  Speaker 1: Oh, that's a great question. So we mostly use these
• 42:19
  Speaker 1: fields to describe fundamental particles, things that we think are
• 42:24
  Speaker 1: not made of anything else. So the photon and the electron,
• 42:27
  Speaker 1: et cetera. Those particles are wiggles and fields that are
• 42:30
  Speaker 1: just a basic element of space itself.
• 42:33
  Speaker 2: But you can totally use.
• 42:35
  Speaker 1: The same math to describe wiggles in other stuff, like
• 42:38
  Speaker 1: water in the ocean or sound waves in the air.
• 42:41
  Speaker 1: These are just wave equations, and the universe is kind
• 42:44
  Speaker 1: of wavy, and you can also identify particles of those
• 42:48
  Speaker 1: fields quanta of those fields. A phonon, for example, is
• 42:52
  Speaker 1: a packet of sound, the way a photon is a
• 42:54
  Speaker 1: packet of light. The math is the same, it's just
• 42:57
  Speaker 1: what's wiggling is not fundamentally universe stuff whatever that is,
• 43:01
  Speaker 1: but something else water or air or plasma or whatever.
• 43:05
  Speaker 2: So we distinguish these.
• 43:07
  Speaker 1: Things from particles by calling them quasi particles. But the
• 43:11
  Speaker 1: point is that the math still works, all right. So
• 43:14
  Speaker 1: to your question about the proton, we know the proton
• 43:17
  Speaker 1: is not a fundamental particle. It's made of quarks, so
• 43:21
  Speaker 1: there's no proton field, right. Well, actually, if you zoom
• 43:25
  Speaker 1: out far enough so you can't see the inside of
• 43:27
  Speaker 1: the proton, it kind of acts like a particle that
• 43:30
  Speaker 1: moves around the universe the way a particle does. And
• 43:33
  Speaker 1: you can pretend that there is a proton field. You
• 43:36
  Speaker 1: can write it down mathematically and use it to describe
• 43:39
  Speaker 1: the motion of the proton as a particle. And the
• 43:42
  Speaker 1: proton field is like an approximate description of the quark
• 43:46
  Speaker 1: fields dancing together. The way they interact together makes it
• 43:49
  Speaker 1: seem like there is a proton field, and until you
• 43:52
  Speaker 1: get enough energy that breaks that proton apart, it all
• 43:55
  Speaker 1: works just fine. And the same, of course, might be
• 43:57
  Speaker 1: true of the electron. We think that there is an
• 44:00
  Speaker 1: electron field, a fundamental part of space. But if the
• 44:03
  Speaker 1: electron is just made of other little particles, which are
• 44:06
  Speaker 1: the true fundamental particles, then the electron field is just
• 44:09
  Speaker 1: an approximate description of those fields dancing together.
• 44:12
  Speaker 3: All right, So where do you go from there?
• 44:15
  Speaker 1: So in this picture, particles are not little bits of stuff, right,
• 44:18
  Speaker 1: you have to give up that whole idea, that whole
• 44:20
  Speaker 1: mental picture we've had since Democritus that said the universe
• 44:25
  Speaker 1: is made of particles and particles are little bits of stuff.
• 44:27
  Speaker 1: Now we say, well, particles are not little bits of stuff.
• 44:30
  Speaker 1: They're wiggles in these fields. And that means something really deep.
• 44:34
  Speaker 1: It means that the universe is not made of particles.
• 44:37
  Speaker 1: It's made of fields. Particles are just something that happens
• 44:41
  Speaker 1: to fields. There's just something fields can do.
• 44:45
  Speaker 2: You know. It's like discovering.
• 44:46
  Speaker 1: Okay, ice cream exists in the world, but actually it's
• 44:49
  Speaker 1: not fundamental. Universe is not made of ice cream. There's
• 44:52
  Speaker 1: times when you don't have ice cream. There's whole periods
• 44:54
  Speaker 1: in the universe when there was no ice cream. It's
• 44:58
  Speaker 1: hard to imagine there was a moment when somebody invented
• 45:02
  Speaker 1: ice cream for the first time, right, and the universe
• 45:04
  Speaker 1: was filled with light. Yes, what it means is that
• 45:06
  Speaker 1: we've gone one level deeper though, right.
• 45:08
  Speaker 2: This is the whole goal. It's like, what really is.
• 45:11
  Speaker 1: At the foundation? What is everything made out of? And
• 45:14
  Speaker 1: this takes quite a left turn. It says, yeah, the
• 45:17
  Speaker 1: universe is not built of little bits. Those bits are
• 45:20
  Speaker 1: actually just ripples in these fields that fill the universe.
• 45:23
  Speaker 1: And I want people to really have an accurate visual
• 45:25
  Speaker 1: image of what these fields are because people think about, Okay,
• 45:28
  Speaker 1: a particle is a ripple in the field, or it's
• 45:30
  Speaker 1: an excitation in the field, And you should understand that
• 45:33
  Speaker 1: a field really is a wavy kind of thing. It
• 45:35
  Speaker 1: can do the same wavy kind of things that other
• 45:37
  Speaker 1: fields can do. You know, like imagine a guitar string.
• 45:41
  Speaker 1: What does a guitar string do when you pluck it,
• 45:43
  Speaker 1: you pull it back and so now it's like you're
• 45:45
  Speaker 1: stretching the string, right, we say in physics, now it
• 45:48
  Speaker 1: has a lot of potential energy because a lot of
• 45:51
  Speaker 1: tangent in there really wants to go back to its
• 45:53
  Speaker 1: relaxed position.
• 45:54
  Speaker 2: What happens when you relax it?
• 45:56
  Speaker 1: What happens when you let it go, Well, it flies
• 45:58
  Speaker 1: back to that relaxed position. But now it's moving really fast,
• 46:01
  Speaker 1: so now has a lot of speed, rights a lot
• 46:04
  Speaker 1: of kinetic energy. So it doesn't actually stop there when
• 46:06
  Speaker 1: it gets back to the relaxed position. It keeps going
• 46:09
  Speaker 1: and it bends the other way, and it oscillates back
• 46:11
  Speaker 1: and forth and back and forth and back and forth.
• 46:13
  Speaker 1: It slashes back and forth between potential energy and kinetic energy.
• 46:17
  Speaker 1: That's what a wave equation, and that's a wave like phenomenal.
• 46:20
  Speaker 1: I mean that slashes back and forth. That's what fields
• 46:23
  Speaker 1: are doing. Fields you can think of them as these
• 46:26
  Speaker 1: numbers in space, but those numbers are slashing back and forth.
• 46:29
  Speaker 1: The field itself has potential energy and kinetic energy. The
• 46:33
  Speaker 1: changing of those numbers has a speed to it. And
• 46:36
  Speaker 1: when we solve the wave equations for fields, what is
• 46:39
  Speaker 1: fundamentally quantum field theory the bedrock of modern particle physics.
• 46:44
  Speaker 1: That's what the solutions look like like. The Higgs field
• 46:46
  Speaker 1: is oscillating when we say a photon is an oscillation
• 46:50
  Speaker 1: in the electromagnetic field, We mean the values of the field.
• 46:53
  Speaker 1: Those numbers in space, Those arrows, they're moving, they're wiggling,
• 46:56
  Speaker 1: they're slashing around.
• 46:58
  Speaker 3: So when I was in high school, we got the
• 47:00
  Speaker 3: like plum pudding model. So yes, I do think now
• 47:03
  Speaker 3: about particles as like a raisin embedded in something, and
• 47:07
  Speaker 3: not as like a wave function. If I were in
• 47:12
  Speaker 3: high school right now, would I be taught something more
• 47:15
  Speaker 3: like what you just said? How long have we known
• 47:17
  Speaker 3: about this stuff? Why does this feel new? Is what
• 47:19
  Speaker 3: I'm asking? Is it new? Or did I forget?
• 47:22
  Speaker 1: It's a great time to ask me this question because
• 47:25
  Speaker 1: my daughter, who's taking high school chemistry right now, is
• 47:28
  Speaker 1: learning about this stuff and asking me questions about it.
• 47:31
  Speaker 1: So I'm getting like a front row seat too. How
• 47:33
  Speaker 1: are people taught about the nature of matter in high school? Yeah,
• 47:37
  Speaker 1: and yeah, they're taught about the plum putting model. Though,
• 47:39
  Speaker 1: just for the record, the plum putting model is not
• 47:42
  Speaker 1: a modern conception. It was like disproved by Rutherford, right.
• 47:45
  Speaker 1: People thought, well, maybe the universe is filled with this
• 47:47
  Speaker 1: jelly of positive stuff. Sounds tasty, but it's not the
• 47:50
  Speaker 1: way that we understand it. It's in contrast to having
• 47:53
  Speaker 1: like a hard dense nucleus at the core. So the
• 47:56
  Speaker 1: plum putting model, they teach it to them and then
• 47:58
  Speaker 1: they throw it out, but they don't really go very
• 48:00
  Speaker 1: deep into like the quantum mechanics of it. Even in
• 48:04
  Speaker 1: AP chemistry, I discovered they don't really talk about this stuff,
• 48:07
  Speaker 1: and they certainly don't talk about particle physics in AP physics.
• 48:10
  Speaker 1: So in high school you don't really get a whole
• 48:11
  Speaker 1: lot of this modern stuff. I teach modern physics at
• 48:15
  Speaker 1: the college level, and that's the first time we really
• 48:17
  Speaker 1: give people an understanding of the nineteen thirties concept of
• 48:21
  Speaker 1: what is a particle and how does quantum mechanics work.
• 48:23
  Speaker 1: And then we don't show them quantum fields until like
• 48:26
  Speaker 1: graduate school. So I didn't learn about quanum field until
• 48:29
  Speaker 1: I was in like eighteenth grade.
• 48:30
  Speaker 2: So you know, this is not the kind of.
• 48:32
  Speaker 1: Stuff that percolates mostly into high school. Maybe fortunately, maybe unfortunately,
• 48:36
  Speaker 1: I would love to have some of these ideas introduced earlier.
• 48:40
  Speaker 3: So you think if you talked to just about any
• 48:43
  Speaker 3: recent graduate of high school, they're probably still thinking of
• 48:45
  Speaker 3: electrons as particles that stay in one spot.
• 48:49
  Speaker 1: Tiny little dots orbiting the nucleus. Do you know Electrons
• 48:53
  Speaker 1: don't orbit, They don't have specific locations. They can't be
• 48:56
  Speaker 1: in one spot and have a specific velocity. You can
• 48:58
  Speaker 1: measure them here, you can measure them there, but they're
• 49:01
  Speaker 1: weird quantum objects. They don't go from here to there.
• 49:04
  Speaker 1: They don't obey all the intuitive rules that you expect
• 49:08
  Speaker 1: things that have specific locations to do.
• 49:10
  Speaker 3: So we can all feel good about our advanced physics knowledge.
• 49:12
  Speaker 1: Now, yes, exactly, you have pushed well beyond high school
• 49:17
  Speaker 1: and even college physics. And you know, I have to
• 49:19
  Speaker 1: underscore how powerful this quantum field theory approach is. To
• 49:23
  Speaker 1: say that all particles are just ripples and fields, and
• 49:25
  Speaker 1: the universe fundamentally is made of these fields. All space
• 49:28
  Speaker 1: is filled with many kinds of fields. You have one
• 49:31
  Speaker 1: for the electron, one for the muon, one for the upcork,
• 49:34
  Speaker 1: one for the down cork.
• 49:35
  Speaker 2: We have more than a.
• 49:36
  Speaker 1: Dozen fields that fill space. This is a really powerful
• 49:40
  Speaker 1: way to think about the universe. We see patterns in
• 49:43
  Speaker 1: these fields, how energy flows from one to the other,
• 49:46
  Speaker 1: their symmetries that they observe. It's allowed us to make
• 49:50
  Speaker 1: really powerful, very accurate calculations of all sorts of stuff
• 49:53
  Speaker 1: that we see happening in particle experiments, and so it's
• 49:56
  Speaker 1: really beautiful and really crisp and really clear. And I
• 49:58
  Speaker 1: think that most particle physicists this is what they think about,
• 50:01
  Speaker 1: or most theoretical physicists, imagine the universe as filled with
• 50:04
  Speaker 1: fields and particles as just ripples in them. But of
• 50:08
  Speaker 1: course it's a field filled with controversy, and so not
• 50:11
  Speaker 1: everybody agrees with that view. There are lots of people
• 50:14
  Speaker 1: who have a very different concept of what a particle
• 50:17
  Speaker 1: is and fundamentally how it all works at the bottom level.
• 50:20
  Speaker 3: So to back up real quick, the field's theory has
• 50:23
  Speaker 3: produced loads of testable hypotheses that have been tested and
• 50:27
  Speaker 3: panned out. But there are still some people who think
• 50:31
  Speaker 3: maybe something else is going on that explains these resultss
• 50:34
  Speaker 3: and what are they proposing is happening.
• 50:37
  Speaker 1: Then they suggest the fields are a fiction, that the
• 50:41
  Speaker 1: fields don't really exist, that the fields are basically just
• 50:44
  Speaker 1: a calculational tool we use in our minds to explain
• 50:47
  Speaker 1: what we see, because in the end, you can't observe
• 50:50
  Speaker 1: a field. You can't directly see a field. It's always
• 50:54
  Speaker 1: an intermedia thing like what you can see are particles.
• 50:57
  Speaker 1: You see those little dots on your screen, or you
• 50:59
  Speaker 1: see the electron deflected in your cathode ray. It's always particle,
• 51:04
  Speaker 1: like I'm doing air quotes when we see it, And
• 51:07
  Speaker 1: particles are what we observe, They're what.
• 51:09
  Speaker 2: We interact with.
• 51:09
  Speaker 1: Yes, we can use fields to explain them, and yes
• 51:12
  Speaker 1: we can think about fields as being out there, but
• 51:15
  Speaker 1: it's hard to argue philosophically that we know fields are
• 51:19
  Speaker 1: real in some way other than we can use them
• 51:21
  Speaker 1: to calculate these experiments. You can't like really directly see them.
• 51:25
  Speaker 1: And lots of famous physicists like Nima or Kanye Ahmed,
• 51:28
  Speaker 1: one of the maybe most brilliant modern particle physicists, calls
• 51:31
  Speaker 1: them a convenient fiction.
• 51:34
  Speaker 3: Huh, So would someone like Nima then argue it's all
• 51:38
  Speaker 3: just particles, Like the field thing is throwing us off track.
• 51:42
  Speaker 3: We were on track with the particles, and we just
• 51:44
  Speaker 3: got to stick with thinking about particles and figure out
• 51:46
  Speaker 3: a way to measure yes at that level instead.
• 51:49
  Speaker 1: Yeah, and here I want to take the opportunity to
• 51:50
  Speaker 1: disentangle something you hear about a lot in popular science.
• 51:54
  Speaker 1: People probably hear oh, particles or ripples in a field.
• 51:57
  Speaker 1: But they also hear this other story, like what happens
• 52:00
  Speaker 1: when two electrons repel each other, Oh, they exchange a photon.
• 52:03
  Speaker 1: They're passing a photon back and forth.
• 52:06
  Speaker 2: Right.
• 52:07
  Speaker 1: What you're doing there is rejecting the field picture. The
• 52:09
  Speaker 1: field picture of what happens when electrons push on each
• 52:12
  Speaker 1: other is an electron makes a field around it, the
• 52:15
  Speaker 1: electromagnetic field, right, and that field pushes on the other electron.
• 52:19
  Speaker 1: That's the field picture. People who don't believe in fields,
• 52:22
  Speaker 1: they're like, just explain it all in terms of particles.
• 52:25
  Speaker 1: You don't need the field. What happens when an electron
• 52:27
  Speaker 1: pushes on another electron is it throws a photon at
• 52:29
  Speaker 1: the other one. And so you can either explain everything
• 52:32
  Speaker 1: in terms of particles that are pushed by fields, or
• 52:36
  Speaker 1: you can explain it just in terms of particles and
• 52:38
  Speaker 1: say you don't need fields. Just go particles all the
• 52:40
  Speaker 1: way down. There are particles we observe, and they push
• 52:43
  Speaker 1: on each other by passing other particles between themselves. So
• 52:46
  Speaker 1: you can basically replace the fields with an infinite number
• 52:49
  Speaker 1: of particles doing all the pushing and pulling and all
• 52:52
  Speaker 1: that other stuff that some people say fields are doing
• 52:55
  Speaker 1: and the frustrating, slash confusing, slash amazing thing is that
• 52:59
  Speaker 1: you do the calculation since you get the same answer.
• 53:01
  Speaker 1: So is it particles is it fields? We can't tell
• 53:04
  Speaker 1: the difference because the two theories mathematically are equivalent. It's like,
• 53:09
  Speaker 1: either you can imagine these fields which fill space, which
• 53:11
  Speaker 1: are beautiful and elegant but kind of weird, like what
• 53:14
  Speaker 1: are they? Or you can say, I'm going to replace
• 53:16
  Speaker 1: those fields by a bunch of particles flying around doing
• 53:20
  Speaker 1: that same work.
• 53:21
  Speaker 3: And are you a field guy?
• 53:24
  Speaker 1: I was a fields guy until I read this book
• 53:27
  Speaker 1: about whether science can be done without math. You know,
• 53:31
  Speaker 1: people wonder like is math invented? Or is it something
• 53:33
  Speaker 1: in our minds? And there's a guy who developed an
• 53:36
  Speaker 1: alternative theory of gravity that doesn't use any math, no
• 53:41
  Speaker 1: numbers at all. It's called science without numbers, and it's
• 53:45
  Speaker 1: really weird. It's very alien. You read it and you're like,
• 53:48
  Speaker 1: what was this guy smoking? And where can I get some?
• 53:51
  Speaker 1: But he philosophically pulls it off. He shows that you
• 53:53
  Speaker 1: don't need to have fields essentially, and the crucial insight
• 53:56
  Speaker 1: in that book is to get rid of fields, because
• 53:57
  Speaker 1: fields are like numbers in space. So he divorces physics
• 54:01
  Speaker 1: from mathematics by ditching fields. My favorite part of the
• 54:04
  Speaker 1: story the guy's last name Fields. So Professor Fields gets
• 54:10
  Speaker 1: rid of fields, the field fieldless theory of physics. There's
• 54:13
  Speaker 1: lots of jokes you could make there, but it made
• 54:15
  Speaker 1: me wonder, you know, like our field's just something we
• 54:18
  Speaker 1: think about or they actually out there. When aliens come
• 54:21
  Speaker 1: and talk to us about their theory of physics, will
• 54:24
  Speaker 1: they have fields in it? Or will they have Schmields
• 54:26
  Speaker 1: or something totally different?
• 54:28
  Speaker 3: So have you dodged my question or are you saying
• 54:32
  Speaker 3: that you're a particle person.
• 54:33
  Speaker 2: I'm saying I don't know.
• 54:34
  Speaker 1: I used to be a fields person, but now I
• 54:37
  Speaker 1: teach the controversy, got it?
• 54:38
  Speaker 3: Okay? So when you first said that there were people
• 54:40
  Speaker 3: who reject fields, I thought that was going to get
• 54:43
  Speaker 3: us into string theory. Are we going to get to
• 54:45
  Speaker 3: string theory too? There's three options. So there's particles, fields,
• 54:49
  Speaker 3: and strings. Is that right?
• 54:51
  Speaker 2: There's more than three options? Unfortunately?
• 54:54
  Speaker 1: Okay, So there's lots of directions to go here. People
• 54:56
  Speaker 1: also wonder, like, well, what are these fields? Are fields
• 54:59
  Speaker 1: that bend ra the truth of the universe at the
• 55:02
  Speaker 1: firmament is that the thing that has to exist. And
• 55:06
  Speaker 1: it's sort of unsatisfactory because, well, why are there all
• 55:08
  Speaker 1: these different fields? Why do we have the electron and
• 55:10
  Speaker 1: the muon, which is like a weird heavy version of
• 55:12
  Speaker 1: the electron. Why are there these obvious patterns among the
• 55:16
  Speaker 1: fields that we can't explain. And one explanation for that
• 55:19
  Speaker 1: are strings, to say, well, none of these things are
• 55:23
  Speaker 1: what's at the bedrock underneath it all is something else,
• 55:27
  Speaker 1: and strings are this idea that the universe is not
• 55:30
  Speaker 1: made out of field to instead these one dimensional bits
• 55:33
  Speaker 1: of matter that can do wavy like stuff. They can wiggle,
• 55:37
  Speaker 1: and they can dance, and they can wiggle in various ways.
• 55:39
  Speaker 1: And if you're zoom down far enough so you can't
• 55:42
  Speaker 1: see the actual string bits themselves, when they wiggle one way,
• 55:45
  Speaker 1: it looks like an electron field, and when they wiggle
• 55:47
  Speaker 1: another way, it looks like a muon field, and when
• 55:49
  Speaker 1: wiggle a third way, it looks like a photon. And
• 55:52
  Speaker 1: so all these fields are actually just different wiggles in
• 55:56
  Speaker 1: these strings. This is another beautiful bit of mathematics. Nobody's
• 56:00
  Speaker 1: proven to be true or not, but might represent what's
• 56:03
  Speaker 1: going on underneath all of this, right, So maybe particles
• 56:07
  Speaker 1: are ripples and fields which are just wiggles in strings.
• 56:12
  Speaker 3: So string theory is still a popular contender. I thought
• 56:15
  Speaker 3: maybe string theory was waning, but I'm you know, not
• 56:19
  Speaker 3: in this field. What's the current state of the string theory.
• 56:22
  Speaker 1: String theory was very popular in the nineties. It seemed
• 56:24
  Speaker 1: very exciting. People discovered this math and could do all
• 56:26
  Speaker 1: sorts of fun stuff with it. And they've done a
• 56:28
  Speaker 1: lot of fun stuff, but they haven't been able to
• 56:30
  Speaker 1: prove that it's true because they talk about the mathematics
• 56:34
  Speaker 1: of the strings, but nobody can see these strings.
• 56:36
  Speaker 2: The strings are too small.
• 56:37
  Speaker 1: In order to see the strings themselves, you'd need like
• 56:39
  Speaker 1: a collideer to the size of the solar system, and
• 56:41
  Speaker 1: we don't have the funds for that. And so until
• 56:45
  Speaker 1: they make a prediction that we can actually test it,
• 56:47
  Speaker 1: say like, oh, string theory, if it's true, we should
• 56:49
  Speaker 1: be able to see this thing, then we don't know
• 56:52
  Speaker 1: if it's just mathematics or if it's actually a description
• 56:54
  Speaker 1: of the universe. And so there's been a lot of
• 56:56
  Speaker 1: people who are negative about string theory for that reason.
• 56:59
  Speaker 1: I still think it's exciting, but there are other ideas
• 57:02
  Speaker 1: out there about you know, what the universe could be
• 57:04
  Speaker 1: made out of?
• 57:05
  Speaker 3: What else?
• 57:05
  Speaker 1: As you were saying earlier, we tend to think about
• 57:08
  Speaker 1: the brain as made out of whatever is the latest
• 57:11
  Speaker 1: technology in the same way we try to think about
• 57:13
  Speaker 1: the universe that way. Like the advent of quantum computing
• 57:16
  Speaker 1: makes us think about cubits and information And there's a
• 57:20
  Speaker 1: whole line of argument that I think we should talk about,
• 57:22
  Speaker 1: probably on another episode, about whether the whole universe is
• 57:27
  Speaker 1: just a quantum computer and particles are like patterns and
• 57:30
  Speaker 1: the flow of information in this quantum computer. There are
• 57:34
  Speaker 1: folks who do these experiments that discover that if you
• 57:37
  Speaker 1: build a space time from entangled cubits, that these patterns
• 57:41
  Speaker 1: naturally arise, which have properties that align well with.
• 57:44
  Speaker 2: The particles that we see.
• 57:46
  Speaker 1: This is all really very speculative stuff, but it's sort
• 57:49
  Speaker 1: of the forefront of current research. People wondering, like, what's
• 57:52
  Speaker 1: underneath all this stuff? Maybe it really is even different
• 57:55
  Speaker 1: than democratists imagined, or Schrotinger or even Fineman.
• 57:59
  Speaker 3: What is a cubit.
• 58:00
  Speaker 1: A cubit is a quantum analogy to a classical bit,
• 58:03
  Speaker 1: like in your computer. A bit is something that can
• 58:05
  Speaker 1: be zero or one. It's like the minimum piece of
• 58:08
  Speaker 1: information you can have. It's boiled down to just two options,
• 58:11
  Speaker 1: like a switch you can flip. And a normal bit
• 58:14
  Speaker 1: is in one state, but a quantum bit has a
• 58:17
  Speaker 1: probability to be in one state or in the other.
• 58:19
  Speaker 1: It's not necessarily in one or the other. So it's
• 58:22
  Speaker 1: a cubit is a quantum bit. And people wonder if
• 58:26
  Speaker 1: fundamentally the universe is made out of cubits that are
• 58:29
  Speaker 1: somehow woven together to make space and time and our reality.
• 58:33
  Speaker 1: But we'll dig into that in a whole other episode.
• 58:35
  Speaker 3: Awesome, all right, So if we tomorrow were to find
• 58:38
  Speaker 3: out which one of these explanations was correct, what would
• 58:43
  Speaker 3: that change? So that would be satisfying, But where could
• 58:47
  Speaker 3: we go from there? That would be even cooler, Like
• 58:49
  Speaker 3: what doors would that open up? For us?
• 58:51
  Speaker 2: Yeah?
• 58:51
  Speaker 1: Wow, awesome question. You're basically asking, like, why do we
• 58:55
  Speaker 1: care about any of this? So what does it mean
• 58:56
  Speaker 1: for us? For me, it's like really deeply important and
• 59:00
  Speaker 1: to understand what is the nature of the universe we're in,
• 59:03
  Speaker 1: You know, what is it made out of? If you
• 59:06
  Speaker 1: told me the universe starts from these conditions, and everything
• 59:09
  Speaker 1: else follows from that, Like to have a universe, you
• 59:12
  Speaker 1: have to have space and time and this little bit
• 59:14
  Speaker 1: of stuff, and then everything else, all the complexity, the blueberries,
• 59:17
  Speaker 1: the kittens, the lava, the podcast, all that comes from
• 59:21
  Speaker 1: how that stuff is arranged and interacts.
• 59:23
  Speaker 2: And that's cool.
• 59:24
  Speaker 1: I want to know what is the most fundamental thing,
• 59:26
  Speaker 1: because that tells me something deep about the nature of
• 59:29
  Speaker 1: the universe. If it's this, then the universe is that
• 59:32
  Speaker 1: way in some deep wave. It's that the universe is
• 59:34
  Speaker 1: another way, in some deep way, and I just fundamentally
• 59:37
  Speaker 1: want to know. It doesn't change how you drink your coffee,
• 59:40
  Speaker 1: it doesn't change how you treat people. It doesn't change
• 59:43
  Speaker 1: what investments you should make. But it changes what it
• 59:45
  Speaker 1: means to be alive in this universe in a really
• 59:47
  Speaker 1: important way.
• 59:48
  Speaker 2: To me. It's very uncomfortable that we don't know the.
• 59:51
  Speaker 1: Answer to the basic question of like, what is the
• 59:55
  Speaker 1: fundamental building block of the universe we live in. It's
• 59:58
  Speaker 1: like being born into a jail and not knowing who
• 1:00:02
  Speaker 1: built it or what's in the outside. It's like, I
• 1:00:04
  Speaker 1: want to break out of this ignorance.
• 1:00:06
  Speaker 3: I found myself personally wanting the answer to be that
• 1:00:09
  Speaker 3: everything is a field and it's sort of connected in
• 1:00:12
  Speaker 3: a way that feels like, I don't know, maybe sort
• 1:00:14
  Speaker 3: of like kum bay us sit around a fire sort
• 1:00:16
  Speaker 3: of feeling. But I like that stuff, so anyway, I
• 1:00:19
  Speaker 3: guess my gut wants that to be the answer. But yes,
• 1:00:21
  Speaker 3: I think it would be good for us to know
• 1:00:23
  Speaker 3: the answer to this very fundamental question.
• 1:00:25
  Speaker 1: And I suspect the answer is none of these and
• 1:00:27
  Speaker 1: something even weirder. That's going to be so difficult for
• 1:00:31
  Speaker 1: us to understand. It's going to be a stretch to
• 1:00:33
  Speaker 1: even explain in terms of our intuitive language of concepts.
• 1:00:37
  Speaker 1: You know, we're going to have to use kiwis and
• 1:00:39
  Speaker 1: fields and particles and strings and all sorts of other
• 1:00:41
  Speaker 1: stuff to try to wrap our minds around the way
• 1:00:44
  Speaker 1: that we universe actually works, which has no guarantee that
• 1:00:46
  Speaker 1: it's even understandable to us.
• 1:00:48
  Speaker 3: So people are going to be like Democratus thought it
• 1:00:50
  Speaker 3: was sour because it was like little knives, and then
• 1:00:52
  Speaker 3: Daniel and Kelly thought it was like strings and fields.
• 1:00:56
  Speaker 3: What idiots? So you know, who knows what they'll think
• 1:00:58
  Speaker 3: in a hundred or so years.
• 1:01:00
  Speaker 2: I hope they're laughing at us. In one hundred years,
• 1:01:02
  Speaker 2: that would be awesome.
• 1:01:03
  Speaker 3: Yeah, progress is good.
• 1:01:05
  Speaker 1: All right, Well, thanks everybody for taking this journey with
• 1:01:07
  Speaker 1: us from the ancient misunderstanding of what matter was to
• 1:01:10
  Speaker 1: our modern misunderstanding of what matter is. And we hope
• 1:01:13
  Speaker 1: to continue this journey and to slowly chisel away towards
• 1:01:17
  Speaker 1: some actual, solid understanding.
• 1:01:19
  Speaker 3: Have a good week everyone. Daniel and Kelly's Extraordinary Universe
• 1:01:30
  Speaker 3: is produced by iHeartRadio. We would love to hear from you,
• 1:01:33
  Speaker 3: We really would.
• 1:01:34
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• 1:01:37
  Speaker 1: Extraordinary Universe.
• 1:01:39
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• 1:01:42
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• 1:01:45
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• 1:01:45
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