WEBVTT - What are paraparticles? 0:00:13.039 --> 0:00:15.600 How does the universe work? What are the rules that 0:00:15.680 --> 0:00:19.680 govern its most microscopic nature. For a few hundred years, 0:00:19.720 --> 0:00:22.840 we've been making progress on this question, mostly by taking 0:00:22.840 --> 0:00:25.680 things apart, and when we zoom into the universe at 0:00:25.680 --> 0:00:28.760 the smallest level, it seems so far like there are 0:00:28.800 --> 0:00:33.520 two different categories of particles, matter particles like quarks and electrons, 0:00:33.560 --> 0:00:37.840 and force particles like photons and gluons. For a long time, 0:00:37.840 --> 0:00:40.120 it seems like that has to be all there is. 0:00:40.360 --> 0:00:44.080 What else could there possibly be? But experiments aren't the 0:00:44.120 --> 0:00:47.040 only way to reveal the secrets of the universe. Another 0:00:47.280 --> 0:00:50.640 very fruitful path is to follow the math. When we 0:00:50.720 --> 0:00:53.920 ask what else the math allows, we sometimes get predictions 0:00:53.920 --> 0:00:57.760 for very weird phenomena like antimatter, or black holes or 0:00:57.840 --> 0:01:01.480 Higgs bosons, which turn out to be real in the universe. 0:01:02.120 --> 0:01:04.720 So can the math show us another kind of particle? 0:01:05.200 --> 0:01:10.319 A weird third way beyond matter and forces. Welcome to 0:01:10.480 --> 0:01:13.760 Daniel and Kelly's Extraordinary mathematical Universe. 0:01:27.000 --> 0:01:30.280 Hello, I'm Kelly Wiersmith. I study parasites and space, and 0:01:30.319 --> 0:01:32.320 I think there are four kinds of particles. 0:01:35.360 --> 0:01:36.920 Are parasites the fourth particle? 0:01:37.080 --> 0:01:39.560 I mean if physics were any good, the answer would 0:01:39.600 --> 0:01:43.920 be yes. See what I think is that y'all like symmetry, 0:01:44.080 --> 0:01:46.280 and I think that if you decide there's three kinds 0:01:46.319 --> 0:01:49.040 of particles, that will be an odd number and you'll 0:01:49.040 --> 0:01:52.920 have to decide there's another kind, so that it's even Hi. 0:01:53.040 --> 0:01:53.680 I'm Daniel. 0:01:53.800 --> 0:01:57.400 I'm a particle physicist, not a paraparticle physicist or a 0:01:57.560 --> 0:02:00.000 parasitical particle physicist or any. 0:02:00.080 --> 0:02:01.280 Those other varieties. 0:02:01.520 --> 0:02:03.920 But I do love understanding the nature of the universe 0:02:04.000 --> 0:02:05.720 and finding symmetry in. 0:02:05.720 --> 0:02:09.080 It all amazing. So are you one of those physicists 0:02:09.080 --> 0:02:11.440 who feels like there needs to be symmetry in these 0:02:11.480 --> 0:02:13.800 answers or does it just kind of depend on the topic? 0:02:14.040 --> 0:02:15.680 Wow, what a deep question to drop on me at 0:02:15.680 --> 0:02:18.880 the top of the episode. I think what we've learned 0:02:18.919 --> 0:02:21.400 so far is that there is symmetry in the universe. 0:02:21.840 --> 0:02:25.480 Like all the rules we've discovered about physics seem to 0:02:25.520 --> 0:02:29.840 follow symmetric patterns. There's like reflections and translations, and you 0:02:29.880 --> 0:02:33.760 can generalize this into abstract algebra called group theory. So 0:02:33.800 --> 0:02:37.880 the universe seems to be well described by symmetries in mathematics. 0:02:37.919 --> 0:02:40.440 Does that mean the universe is symmetric or that's just 0:02:40.480 --> 0:02:42.200 the way we like to think about it. I mean, 0:02:42.280 --> 0:02:43.960 that's a deep question in philosophy. We're not going to 0:02:43.960 --> 0:02:46.560 answer it today. But I appreciate symmetry. 0:02:46.800 --> 0:02:49.560 I love it. I love the mathematical beauty of what 0:02:49.600 --> 0:02:50.880 we've learned about the universe. 0:02:51.240 --> 0:02:53.800 Why should the universe be symmetrical instead of like just 0:02:53.840 --> 0:02:56.160 a mess? Like as an evolutionary biologist, like it all 0:02:56.200 --> 0:02:58.920 being held together with like duct tape and zip ties 0:02:59.080 --> 0:03:01.680 makes more sense to me then it being beautifully symmetrical. 0:03:01.840 --> 0:03:03.720 But why is it symmetrical? 0:03:04.520 --> 0:03:08.520 I think I have a natural preference for explanations that 0:03:08.600 --> 0:03:13.680 are simple, that are harmonious and parsimonious, right, Like we 0:03:13.840 --> 0:03:16.959 think that the universe should be in the end described 0:03:17.040 --> 0:03:21.120 by one simple idea, and so we're constantly looking for that, 0:03:21.160 --> 0:03:24.080 and symmetry helps us restrain that. It helps us reduce 0:03:24.160 --> 0:03:27.560 the number of options, you know, like instead of having 0:03:27.600 --> 0:03:29.480 to come up with ten numbers, what if there's a 0:03:29.520 --> 0:03:32.520 symmetry that tells you that those numbers are all related, 0:03:32.560 --> 0:03:35.080 so there really is just one number that turns into ten. 0:03:35.720 --> 0:03:37.840 But you might also ask the basic question like, well, 0:03:37.880 --> 0:03:41.200 why do we expect the universe to be simple and parsimonious, 0:03:41.840 --> 0:03:43.400 and I don't have an answer for that, you know, 0:03:43.520 --> 0:03:46.080 just so far that seemed to work, you know, looking 0:03:46.080 --> 0:03:49.320 for the simplest explanation so far has found us things 0:03:49.360 --> 0:03:52.240 that work in the universe. They predict experiments, they describe 0:03:52.280 --> 0:03:55.200 things we haven't seen yet. So many times in the 0:03:55.240 --> 0:03:58.360 history of science we followed the symmetry in mathematics to 0:03:58.400 --> 0:04:05.200 make discoveries like particles or like electromagnetism. You know, Maxwell 0:04:05.280 --> 0:04:07.800 looking at these equations and seeing a lack of symmetry 0:04:07.880 --> 0:04:09.880 and penciling in the piece he needs to make the 0:04:09.880 --> 0:04:14.040 equation symmetrical, discovering something real in the universe, or Peter 0:04:14.200 --> 0:04:17.000 Higgs finding a piece that clicks together with all the 0:04:17.040 --> 0:04:21.320 other pieces to answer why symmetry is broken, so it 0:04:21.400 --> 0:04:24.120 seems to work, is the only real answer I can 0:04:24.160 --> 0:04:24.480 give you. 0:04:24.880 --> 0:04:27.040 Interesting, you know, So I was I'm reading this book 0:04:27.080 --> 0:04:30.039 called The Remedy right now, and it is about how 0:04:30.200 --> 0:04:35.400 like Coch and Pasteur determined that microorganisms caused disease. And 0:04:35.480 --> 0:04:38.600 the author was arguing that actually this kind of flew 0:04:38.640 --> 0:04:41.680 in the face of we should look for the simplest answer, 0:04:41.760 --> 0:04:44.640 because the simplest answer at the time was that bad 0:04:44.720 --> 0:04:47.440 air causes all of these maladies, and so having one 0:04:47.720 --> 0:04:50.520 cause that explained all of this stuff seemed much simpler 0:04:50.520 --> 0:04:54.000 than you know, Tuberculosis is caused by this tiny organism, 0:04:54.080 --> 0:04:56.400 and smallpox is caused by that tiny organism that we 0:04:56.440 --> 0:04:59.360 can't even see. And so the fact that bad air 0:04:59.480 --> 0:05:01.960 was simple a sort of made people cling to it 0:05:02.000 --> 0:05:04.200 a little bit longer than this more complicated answer that 0:05:04.240 --> 0:05:05.880 tended to be right. And so I think in almost 0:05:05.880 --> 0:05:07.760 every case it makes a lot more sense to look 0:05:07.800 --> 0:05:11.080 for the simplest explanation first, but you should not let 0:05:11.080 --> 0:05:13.719 it close your eyes to the more complex answers that 0:05:13.800 --> 0:05:15.680 might actually be the reality of the situation. 0:05:15.920 --> 0:05:18.640 Yeah, you should choose the simplest answer that works, that 0:05:18.720 --> 0:05:22.200 actually describes the universe. Yes, not the simplest answer that 0:05:22.200 --> 0:05:25.040 doesn't describe the universe. But you're right, you don't know 0:05:25.080 --> 0:05:26.960 in advance what's going to work and what isn't, And 0:05:27.000 --> 0:05:30.080 so we often start from the simplest thing because why 0:05:30.120 --> 0:05:32.200 not right, And if that doesn't work, then we move 0:05:32.240 --> 0:05:33.400 on to something more complicated. 0:05:33.440 --> 0:05:36.360 And that's how we get chemistry and biology and. 0:05:36.320 --> 0:05:41.200 All sorts of other delicious, beautiful messes of science. Right, 0:05:41.279 --> 0:05:43.159 that have yet to pull themselves together into a single 0:05:43.160 --> 0:05:46.880 parsimonious explanation. And that's also one reason why I am 0:05:46.920 --> 0:05:50.279 a physicist, because physics, I feel like, is closer to 0:05:50.360 --> 0:05:53.440 getting to a single answer than chemistry is. For example, 0:05:53.480 --> 0:05:55.880 I was always frustrated in chemistry, like this rule for 0:05:55.920 --> 0:05:57.680 this thing, and this rule for that thing, and this 0:05:57.800 --> 0:06:00.839 other rule except for this other scenario. Maybe I just 0:06:00.880 --> 0:06:02.400 have a bad memory and it's hard to hold all 0:06:02.440 --> 0:06:04.440 those things in my head. But I just really like 0:06:04.480 --> 0:06:06.880 to look, here's one equation. Start from that you can 0:06:06.920 --> 0:06:09.440 get to anything. That just always appealed to me. 0:06:09.680 --> 0:06:11.839 That's so interesting. I think we live on very different 0:06:11.880 --> 0:06:14.520 sides of this gradient. So like for me, you know, 0:06:14.560 --> 0:06:17.360 you said biologists and chemists have yet to come up 0:06:17.360 --> 0:06:19.760 with a simple theory. I don't feel like that's what 0:06:19.760 --> 0:06:20.839 we're trying for at all. 0:06:20.960 --> 0:06:23.599 Like why maybe that's why you haven't found one. 0:06:24.240 --> 0:06:26.680 Why would you assume that there is one? Like life 0:06:26.720 --> 0:06:29.880 is beautifully complex, you know, the it depends is where 0:06:29.920 --> 0:06:33.080 all the fun lives. I think. You know, you're like, oh, 0:06:33.160 --> 0:06:36.120 that's frustrating, and I'm like, no, that's that's the exciting part. 0:06:36.240 --> 0:06:39.200 Like what it depends on what life is complicated and 0:06:39.279 --> 0:06:41.120 messy and that's what makes it beautiful. 0:06:41.279 --> 0:06:43.160 But isn't it beautiful when you find things that are 0:06:43.160 --> 0:06:46.279 true across all of life? Right Like DNA, for example, 0:06:46.400 --> 0:06:48.520 undergirds a lot of life on Earth, and that's really 0:06:48.560 --> 0:06:51.320 powerful to discover that and to understand it. Right, Yeah, 0:06:51.400 --> 0:06:54.279 it's not as fascinating as like this one kind of 0:06:54.360 --> 0:06:57.680 frog does this one kind of thing on random tuesdays 0:06:58.040 --> 0:06:59.080 in my opinion. 0:06:58.880 --> 0:07:01.760 Well, I will politely disagree with you. I think what 0:07:02.600 --> 0:07:05.520 the frogs are doing on tuesdays I am deeply interested in. 0:07:05.680 --> 0:07:09.360 But yes, you know, I think it's beautiful that you know, 0:07:09.400 --> 0:07:13.440 the blueprint for life is stored in the same material 0:07:13.960 --> 0:07:16.360 no matter what organism you're looking at. But we all 0:07:16.400 --> 0:07:19.320 do very different things with that material. You know, bacteria 0:07:19.520 --> 0:07:22.720 do horizontal gene transfer. They're swapping genes back and forth, 0:07:22.760 --> 0:07:25.080 and you know, we have to have sex to swap 0:07:25.120 --> 0:07:28.400 genetic material, and we've got recombination and I don't know anyway, 0:07:28.400 --> 0:07:30.679 that's where the it depends gets fun again. 0:07:31.280 --> 0:07:33.640 Well, we have made a lot of hay in physics, 0:07:33.680 --> 0:07:37.240 at least in looking for symmetries and then trying to 0:07:37.400 --> 0:07:40.520 understand when there are holes, is there something to fill 0:07:40.560 --> 0:07:43.160 that hole? Right the way we did with antiparticles and 0:07:43.280 --> 0:07:45.720 the way we did with all the quarks, and so 0:07:45.920 --> 0:07:49.280 often mathematical beauty really does lead us to new discoveries. 0:07:49.280 --> 0:07:51.880 And that's what we're talking about today on the podcast. 0:07:51.960 --> 0:07:56.000 Whether there is another bucket, another kind of thing out 0:07:56.000 --> 0:07:58.440 there in the universe that we can use to describe 0:07:58.520 --> 0:08:01.920 how everything works, maybe explains why those toads do that thing. 0:08:01.960 --> 0:08:03.600 On Tuesday, at. 0:08:03.200 --> 0:08:04.960 The end of all of our banters, I'm like, how 0:08:05.000 --> 0:08:06.440 are we going to get back on track? And you 0:08:06.600 --> 0:08:07.640 always get us there. 0:08:07.840 --> 0:08:15.080 Okay, it's sometimes a bigger step than I expect. 0:08:11.720 --> 0:08:11.800 But. 0:08:14.200 --> 0:08:17.760 You're good at jumping that chasm. So all right. So 0:08:17.800 --> 0:08:21.280 today we're talking about paraparticles and I had never heard 0:08:21.320 --> 0:08:24.720 of para particles before, and so let's see if our 0:08:24.880 --> 0:08:28.280 audience is on the same page as Kelly. So we asked, 0:08:29.000 --> 0:08:32.000 what are para particles? And here are the answers we got. 0:08:32.480 --> 0:08:35.280 I wonder if it's something to do with larger things 0:08:35.360 --> 0:08:40.760 showing particle light behavior in certain circumstances. I'm so glad 0:08:40.840 --> 0:08:43.800 there isn't. TONI exam at the end of the podcast. 0:08:43.920 --> 0:08:47.559 Piece of a particle, like a very small part of 0:08:47.600 --> 0:08:51.880 the particle, some sort of entity that exists alongside the 0:08:51.880 --> 0:08:53.640 traditional particles. 0:08:53.559 --> 0:08:57.480 Somewhere between a real particle and a ghost particle, like 0:08:57.679 --> 0:09:01.679 a virtual particle, and then it's enabling interactions with others. 0:09:02.360 --> 0:09:05.760 I think it's like a super superposition. And it's one 0:09:05.760 --> 0:09:08.720 of those weird things about quantum mechanics that if you 0:09:08.760 --> 0:09:11.319 look at it, it just disappears off. 0:09:11.880 --> 0:09:15.160 I might be particles that we believe exist but haven't 0:09:15.160 --> 0:09:16.400 I prayed for yet. 0:09:16.600 --> 0:09:19.120 Kind of like a particle but not quite. 0:09:19.480 --> 0:09:23.560 Something that acts like a particle when certain conditions are. 0:09:23.480 --> 0:09:27.960 Met at something that's almost a particle. Paraparticles rely on 0:09:27.960 --> 0:09:31.880 their neighboring particle for existence. I'm completely stunned by this one. 0:09:32.360 --> 0:09:37.760 The virtual particle pairs that spring to existence in a vacuum. 0:09:37.920 --> 0:09:41.160 Is a paraparticle something that lives off of or takes 0:09:41.200 --> 0:09:42.760 advantage of another particle? 0:09:43.520 --> 0:09:45.000 Is it a paralyzed particle? 0:09:45.600 --> 0:09:49.880 So lots of playing with what para means in other contexts. 0:09:49.960 --> 0:09:51.920 I like it got you all are very clever. 0:09:52.040 --> 0:09:55.160 But they missed the obvious. Nobody went for the connection 0:09:55.240 --> 0:09:56.400 to parasites. 0:09:56.559 --> 0:10:03.679 Guys, Guys, I work so oft hard so hard. Oh wait, no, no, no, 0:10:03.720 --> 0:10:06.959 that's not true. Somebody said, relying on their neighbors for existence, 0:10:07.120 --> 0:10:13.480 that's their parasitical particles. That's right way to go, that 0:10:13.559 --> 0:10:17.400 particular audience member. Thank you for paying attention all this time. 0:10:17.720 --> 0:10:19.920 I was just glad that nobody went for the sort 0:10:19.920 --> 0:10:23.360 of anti academic grifter line, the like academics are just 0:10:23.440 --> 0:10:27.640 parasites on society and they're sucking money and scams and 0:10:27.679 --> 0:10:29.800 don't really believe anything they're doing, all that bad faith 0:10:29.880 --> 0:10:32.880 nonsense you sometimes see in various corners of the internet. 0:10:32.960 --> 0:10:35.280 Oh wow, are you I feel like there's a bit 0:10:35.320 --> 0:10:39.200 of insecurity today. 0:10:40.120 --> 0:10:42.000 I just want to address the reality, you know, that 0:10:42.080 --> 0:10:44.839 kind of stuff is out there in the universe. Anyway, 0:10:44.880 --> 0:10:46.880 I was very happy to hear all these positive and 0:10:46.920 --> 0:10:50.120 constructive answers. Thanks everybody. If you'd like to contribute your 0:10:50.160 --> 0:10:52.679 ideas for future episodes, don't be shy right to us 0:10:52.720 --> 0:10:55.439 two questions at Daniel and Kelly dot org. You can 0:10:55.480 --> 0:10:57.239 hear your voice on the podcast. 0:10:57.520 --> 0:11:00.200 Amazing. All right, So let's dig in. So what are 0:11:00.200 --> 0:11:02.280 a particle? So you said in the introduction that there 0:11:02.320 --> 0:11:06.680 are maybe three kinds of particles. Can we start by 0:11:06.840 --> 0:11:09.800 reviewing the first two kinds, because I'm sure that you've 0:11:09.800 --> 0:11:12.439 mentioned in the past that particles come in matter and 0:11:12.640 --> 0:11:15.360 force flavors. But every once in a while, at the 0:11:15.440 --> 0:11:17.800 end of an episode, I'll discover my brain has reached 0:11:17.840 --> 0:11:20.960 capacity and maybe some stuff overflowed out the top, and 0:11:21.040 --> 0:11:24.600 so remind me what are meta particles? What are force particles? 0:11:24.600 --> 0:11:26.000 And then we'll get into this third kind. 0:11:26.280 --> 0:11:29.320 Yeah, sure, no problem. I'd be careful with the word flavor. 0:11:29.320 --> 0:11:32.280 Though flavor has a particular meaning in particle physics, it 0:11:32.320 --> 0:11:35.320 means something else, and it's not like you know, cookie 0:11:35.400 --> 0:11:38.600 dough and mint chocolate chip. It's like the difference between 0:11:38.600 --> 0:11:42.120 electrons and muons and towels or different flavors of leptons. 0:11:42.240 --> 0:11:45.920 Like that's an actual like physics jargon term is flavors. 0:11:46.160 --> 0:11:49.360 Oh absolutely, And there's amazing the whole subfield of particle 0:11:49.360 --> 0:11:52.480 physics called flavor physics. And then the people who work 0:11:52.520 --> 0:11:54.520 on the flavor of particles that have a lot of mass, 0:11:54.559 --> 0:11:57.720 that's called heavy flavor physics, which sounds like it should 0:11:57.760 --> 0:11:59.600 be a hip hop group, but it really is a 0:11:59.600 --> 0:12:00.440 bunch of nerds. 0:12:00.640 --> 0:12:03.000 Well, you know, nerds can have hip hop groups. You 0:12:03.040 --> 0:12:05.360 don't have to be so judgy. 0:12:05.679 --> 0:12:07.640 Yeah, heavy flavor flakes, let's hear it. 0:12:08.160 --> 0:12:08.760 I love it. 0:12:10.240 --> 0:12:10.600 All right. 0:12:10.679 --> 0:12:14.359 So today we're talking about one way to distinguish particles, 0:12:14.720 --> 0:12:17.520 and that's by their spin. So there are particles that 0:12:17.559 --> 0:12:20.520 make up matter, me and you, and everything that's out 0:12:20.559 --> 0:12:22.880 there and everything you've ever eaten are made out of 0:12:22.960 --> 0:12:26.760 quarks and lectons. So the upcork and the down cork 0:12:26.880 --> 0:12:30.240 make up protons and neutrons. You add electrons, which are 0:12:30.360 --> 0:12:32.920 kind of lefton, and you can make any atom. Right 0:12:33.040 --> 0:12:35.360 from that, you can make any molecule. And anything anybody 0:12:35.360 --> 0:12:37.840 has ever seen or thrown at their sister is made 0:12:37.840 --> 0:12:40.120 out of this kind of stuff, right, Okay, So this 0:12:40.200 --> 0:12:43.600 is what we call matter particles. And all these particles 0:12:43.600 --> 0:12:46.160 have something in common, which is their quantum spin has 0:12:46.240 --> 0:12:48.200 units of one half, which means they can have spin 0:12:48.400 --> 0:12:51.760 up one half or spin down one half. So all 0:12:51.800 --> 0:12:55.719 these particles, which we call fermions after Enrico Fermi, these 0:12:55.760 --> 0:12:58.960 are matter particles. They're particles with one half spin. 0:12:59.280 --> 0:13:02.120 Can you help me like visualize that, like, are they 0:13:02.200 --> 0:13:03.280 actually spinning? 0:13:03.720 --> 0:13:06.760 M You know the answer to that question, Kelly is 0:13:06.880 --> 0:13:11.800 nobody knows. Quantum spin is a super fascinating topic because 0:13:11.840 --> 0:13:14.839 on one hand, it's very different from a real spin, 0:13:14.920 --> 0:13:17.320 like normal spin, like you take a ball and you 0:13:17.400 --> 0:13:19.679 spin it. We can talk about the angular momentum, we 0:13:19.720 --> 0:13:22.040 can talk about the velocity on the surface. A classical 0:13:22.040 --> 0:13:25.720 object has spin and it has angular momentum, right, And 0:13:25.760 --> 0:13:27.800 we know that that angler momentum is important to the 0:13:27.880 --> 0:13:31.240 universe because it's preserved. Like if you spin a ball 0:13:31.320 --> 0:13:34.280 in space, it keeps spinning. And the reason that like 0:13:34.360 --> 0:13:37.760 our galaxy is spinning is because of conservation of angular momentum. 0:13:37.840 --> 0:13:40.319 The reason the solar system has the shape that it does, 0:13:40.600 --> 0:13:43.120 it's like sort of flat. The way the galaxy is 0:13:43.120 --> 0:13:45.599 a disc is because of angle momentum. Anglementum is a 0:13:45.600 --> 0:13:48.480 really big important thing in the universe. Things really do spin. 0:13:49.280 --> 0:13:53.119 Quantum particles don't spin in the same way because electrons 0:13:53.120 --> 0:13:56.559 are not tiny little balls. And like one hundred years ago, 0:13:56.600 --> 0:13:58.120 when they were thinking about this, they were like, well, 0:13:58.160 --> 0:13:59.920 what if they spin, how fast would they be spin? 0:14:00.480 --> 0:14:03.360 They try to calculate, like how fast the surface of 0:14:03.400 --> 0:14:05.480 an electron is spinning, and you get an answer that's 0:14:05.480 --> 0:14:08.920 like higher than the speed of light. So it's obviously nonsense. 0:14:09.400 --> 0:14:11.040 Whenever you do physics and you get an answer that 0:14:11.040 --> 0:14:13.480 doesn't make sense, like something has gone wrong along the 0:14:13.520 --> 0:14:14.160 way right. 0:14:14.200 --> 0:14:15.400 Or you've created a new field. 0:14:17.600 --> 0:14:20.240 In this case, the answer is that these are quantum particles. 0:14:20.240 --> 0:14:22.280 They're not classical, so you can think of them as 0:14:22.360 --> 0:14:25.840 existing physically the same way, where every part of them 0:14:25.960 --> 0:14:29.440 has a location every moment in time, so they don't 0:14:29.480 --> 0:14:32.840 physically spin. You shouldn't think about these quantum particles as 0:14:32.880 --> 0:14:35.880 like little balls that are spinning, and so you might ask, well, 0:14:35.920 --> 0:14:37.800 if it's not spinning, why do you call it spin. 0:14:38.160 --> 0:14:40.120 We call it spin because it has a lot of 0:14:40.160 --> 0:14:44.640 the same properties as classical objects spin. For example, it's 0:14:44.680 --> 0:14:49.240 conserved right, and it's conserved together with other kinds of 0:14:49.240 --> 0:14:52.560 angular momentum, meaning that what the universe cares about is 0:14:52.600 --> 0:14:56.280 the total angler momentum, including spin. So you can convert 0:14:56.280 --> 0:14:59.400 like normal angler momentum like the Earth is spinning, into 0:14:59.560 --> 0:15:03.280 quantum angle momentum spin, and back and forth. The universe 0:15:03.320 --> 0:15:05.600 requires you to conserve the sum of those two, which 0:15:05.640 --> 0:15:08.880 tells you they're like the same kind of thing the 0:15:08.880 --> 0:15:11.560 same way that like energy is often conserved, but it's 0:15:11.600 --> 0:15:14.840 the sum of kinetic and potential energies. Which tells you like, Okay, 0:15:14.880 --> 0:15:17.160 these are two kinds of the same thing, because what 0:15:17.200 --> 0:15:19.520 the universe cares about is the sum of them, not 0:15:19.600 --> 0:15:23.560 the individual ones. So we know that quantum spin is 0:15:23.600 --> 0:15:27.800 similar to real spin classical spin because the universe conserves 0:15:27.840 --> 0:15:30.880 the sum of those things, and quantum spin has other 0:15:30.960 --> 0:15:34.360 similar properties, like things that have quantum spin and electric 0:15:34.440 --> 0:15:38.360 charge have little magnetic fields because charges in motion give 0:15:38.400 --> 0:15:41.280 magnetic fields. So like an electron which is spinning, has 0:15:41.320 --> 0:15:43.880 a little magnetic field, and that's why it's like bent 0:15:43.960 --> 0:15:47.440 by magnetic fields, et cetera, et cetera. So we don't 0:15:47.480 --> 0:15:49.400 really know what it is, but we know that it 0:15:49.440 --> 0:15:52.280 acts a lot like spin, so we call it quantum spin, 0:15:53.120 --> 0:15:54.920 which I think is a pretty good name, even though 0:15:54.960 --> 0:15:55.680 it's not spinning. 0:15:57.800 --> 0:16:00.200 Okay, all right, So I usually to hear things like 0:16:00.240 --> 0:16:02.120 four times before they stick in my brain. I think 0:16:02.120 --> 0:16:05.040 we're at like two, so be prepared to repeat that. 0:16:05.600 --> 0:16:09.480 But so to try to help me, all right, So, fermions, 0:16:08.720 --> 0:16:12.920 these are the mass or the matter particles. Yes, and 0:16:12.960 --> 0:16:16.160 so I'm gonna think of fermions as like it's firm matter. 0:16:16.240 --> 0:16:19.080 It makes us be although you know now you're gonna 0:16:19.080 --> 0:16:22.040 misspell fermions from here on out because it's not spelled 0:16:22.120 --> 0:16:24.800 like firm. But anyway, all right, that's how I'm remembering it. 0:16:24.840 --> 0:16:27.200 And so now let's talk about force. And so I 0:16:27.240 --> 0:16:30.960 always thought force was like a field, and I didn't 0:16:30.960 --> 0:16:34.440 think of it as a particle anyway. So let's go on. 0:16:34.560 --> 0:16:38.360 So the bosons are force particles. 0:16:38.160 --> 0:16:40.240 Yes, And let me also liabrate on the comment you 0:16:40.320 --> 0:16:43.360 made about field versus particles. There are two ways of 0:16:43.480 --> 0:16:46.720 thinking about what stuff is and how it's pushed. One 0:16:46.880 --> 0:16:49.440 is the field picture, which is really natural to a 0:16:49.480 --> 0:16:53.000 lot of particle physicists. There's an electron field, and the 0:16:53.000 --> 0:16:55.720 electron is actually just a ripple in that field, and 0:16:55.840 --> 0:16:59.160 there's an electromagnetic field, and photons are ripples in that field. 0:16:59.640 --> 0:17:02.000 And in that view, the fields are the fundamental thing, 0:17:02.240 --> 0:17:04.679 and particles are just ripples in those things. They are 0:17:04.680 --> 0:17:07.560 like emerging phenomena from the fields, and the fields can interact. 0:17:07.840 --> 0:17:10.119 And we talk about that picture a lot on the podcast. 0:17:10.840 --> 0:17:13.280 There's another way to think about things and say, you know, 0:17:13.440 --> 0:17:15.720 fields are just like a construct in our minds. We 0:17:15.760 --> 0:17:18.960 never see them directly. We only see them acting on particles, 0:17:19.000 --> 0:17:21.239 and the particles are the things we can see. We 0:17:21.280 --> 0:17:25.240 see dots on the screen, we see electrons moving through wires, etc. 0:17:25.840 --> 0:17:28.800 So particles are the real things. And so from that 0:17:28.840 --> 0:17:31.840 point of view, we have electrons and they're little particles, 0:17:31.880 --> 0:17:34.159 and we have quarks and their little particles, and then 0:17:34.200 --> 0:17:36.800 the forces we can talk about other particles. So we 0:17:36.880 --> 0:17:39.920 have like the photon. What happens when two electrons repel 0:17:39.920 --> 0:17:43.600 each other, they exchange photons. So this is the particle 0:17:43.640 --> 0:17:46.440 picture of the universe. Everything is made out of little particles, 0:17:46.840 --> 0:17:49.840 and it can explain matter. It's a little bit more awkward, 0:17:49.840 --> 0:17:52.440 but it can also explain forces right in that picture, 0:17:52.440 --> 0:17:55.520 like electrons exchange photons. That's the way they attract or 0:17:55.560 --> 0:17:58.200 repel each other. And it's a little bit awkward because 0:17:58.240 --> 0:18:01.400 like how exactly they do electrons and positrons attract each 0:18:01.400 --> 0:18:02.800 other by exchanging photons. 0:18:03.040 --> 0:18:04.000 It's hard to imagine you. 0:18:04.000 --> 0:18:07.280 Could like attract Zach by throwing a ball at him, right, 0:18:07.320 --> 0:18:09.720 it feels like it would only push him away. But 0:18:09.840 --> 0:18:11.760 you know, this is the quantum world, and you can 0:18:11.800 --> 0:18:14.199 do weird things like you can throw a photon with 0:18:14.320 --> 0:18:18.000 negative momentum, so when Zach catches it, he's pulled towards you. 0:18:18.040 --> 0:18:20.480 It's like a tractor beam photon. 0:18:20.600 --> 0:18:24.399 And biology is too complicated, doesn't make sense. What are 0:18:24.440 --> 0:18:25.040 you guys thinking? 0:18:26.920 --> 0:18:28.720 Yeah, yeah, And this is one reason why I think 0:18:28.720 --> 0:18:30.640 the field picture is a little bit more natural. 0:18:31.119 --> 0:18:31.920 But anyway, we can. 0:18:31.840 --> 0:18:35.320 Talk about these forces as mediated by particles. And these 0:18:35.359 --> 0:18:38.000 particles have a property which is that they don't have 0:18:38.200 --> 0:18:40.840 half integer spin like one half or negative one half. 0:18:40.880 --> 0:18:43.520 They have integer spin. So a photon, for example, can 0:18:43.560 --> 0:18:46.960 have spin one, spin zero or spin negative one. And 0:18:47.080 --> 0:18:49.679 the W boson and the Z boson, and the Higgs 0:18:49.680 --> 0:18:52.800 boson and the gluons, all the particles that correspond to 0:18:52.880 --> 0:18:56.000 the forces and how matter particles exchange momentum, they all 0:18:56.040 --> 0:18:59.440 have the same property that their spin is integer values, 0:18:59.520 --> 0:19:02.840 you know, half it's like plus two minus one, this 0:19:02.960 --> 0:19:06.000 kind of stuff. So those are particles we call bosons. 0:19:06.359 --> 0:19:09.280 So the fermions and the matter particles, the bosons are 0:19:09.359 --> 0:19:11.439 the force particles in this picture. 0:19:11.720 --> 0:19:14.720 All right, So now we've got through the two kinds 0:19:14.720 --> 0:19:16.720 of particles, and let's bring a little bit of pep 0:19:16.760 --> 0:19:19.800 into this conversation after the break, So we'll talk about 0:19:19.800 --> 0:19:42.479 the Paul exclusion principle when we get back all right, 0:19:42.760 --> 0:19:46.680 So we've established that we have two kinds of particles. 0:19:46.680 --> 0:19:49.840 We've got the fermions, which are the matter particles, and 0:19:49.880 --> 0:19:53.240 the bosons, which are the force particles. Why does it 0:19:53.280 --> 0:19:55.880 matter that we divide them in this way? Why can't 0:19:55.880 --> 0:19:57.040 they all just be particles. 0:19:58.920 --> 0:20:02.800 They are all just partticles or fields equivalently, but they 0:20:02.840 --> 0:20:07.000 have very different behaviors, and that behavior is really important. Specifically, 0:20:07.080 --> 0:20:10.440 bosons can do something fermions will never ever ever do, 0:20:11.000 --> 0:20:13.720 which is, bosons can be in the same quantum state 0:20:14.000 --> 0:20:17.840 and fermions never will. So you made this joke about PEP. 0:20:18.119 --> 0:20:23.080 The poly exclusion principle, named after Wolfgunning Poll says that 0:20:23.200 --> 0:20:26.320 no two fermions can ever be in the same quantum state. 0:20:26.440 --> 0:20:29.480 So if you have two identical particles like two electrons, 0:20:29.800 --> 0:20:33.200 they can't have all the same quantum description, which would 0:20:33.200 --> 0:20:37.719 be like their location, their momentum, their spin, their energy, 0:20:37.800 --> 0:20:40.360 all this kind of stuff. They can't be identical. They 0:20:40.440 --> 0:20:43.240 have to be unique. Every fermion has to have a 0:20:43.280 --> 0:20:44.399 different quantum state. 0:20:44.680 --> 0:20:46.239