WEBVTT - What is weak hypercharge? 0:00:05.880 --> 0:00:10.640 The universe is beautiful and amazing and strange and confusing, 0:00:11.000 --> 0:00:14.360 and we struggle sometimes or a lot of times, to 0:00:14.720 --> 0:00:17.320 make sense of it. One reason is that we have 0:00:17.440 --> 0:00:21.599 a limited vocabulary to explain it to ourselves, not just 0:00:21.680 --> 0:00:25.440 limited to the words that we choose, but the concepts 0:00:25.480 --> 0:00:30.040 that we find familiar, the things we accept as explanations. 0:00:30.400 --> 0:00:34.280 Most of physics is about explaining the weird, bonkers rules 0:00:34.320 --> 0:00:37.800 of our universe in terms that do make sense to us, 0:00:38.200 --> 0:00:41.960 like eating some new, weird fruit nobody's ever tasted before, 0:00:42.400 --> 0:00:46.360 and then describing it in terms of familiar childhood staples. 0:00:46.600 --> 0:00:48.879 It's a little bit like an orange, but with hints 0:00:48.960 --> 0:00:51.559 of cherry and BlackBerry. That's what we try to do. 0:00:51.600 --> 0:00:54.400 For example, with photons, we say, oh, they're kind of 0:00:54.480 --> 0:00:56.680 like waves, they're kind of like particles, even though we 0:00:56.840 --> 0:01:00.520 know that neither of those fully capture the alien of 0:01:00.560 --> 0:01:05.039 the photon. But today's episode isn't about oranges or about photons, 0:01:05.120 --> 0:01:08.160 at least not directly. We're going to dig into another 0:01:08.319 --> 0:01:11.800 basic concept and try to understand what it really is. 0:01:12.400 --> 0:01:16.160 Electric charge. What is it? Where is it? Why do 0:01:16.240 --> 0:01:19.040 some particles have it? Why do some have more than others? 0:01:19.280 --> 0:01:22.440 How is it connected to electric forces? And once we 0:01:22.520 --> 0:01:24.920 have something of a handle on that, we're going to 0:01:25.000 --> 0:01:28.000 see if we can extend it to something less familiar, 0:01:28.240 --> 0:01:31.640 the weak force. How do charges work for those other forces? 0:01:31.680 --> 0:01:34.880 And why, oh why did physicists call the charge for 0:01:34.920 --> 0:01:38.679 the weak force hypercharge? Is it weak or is it hyper? 0:01:39.000 --> 0:01:43.080 Make up your minds, physicists. Welcome to Daniel and Kelly's 0:01:43.200 --> 0:01:45.080 hyper Extraordinary Universe. 0:01:58.840 --> 0:02:03.400 Hello, what smith? I am a parasitologist and weak hypercharge 0:02:03.440 --> 0:02:05.320 is a phrase that makes really no sense to me. 0:02:08.040 --> 0:02:10.640 Huh. I'm Daniel Watson. I'm a particle physicist, and so 0:02:10.720 --> 0:02:13.760 I should understand weak hypercharge, but it still gets scrambled 0:02:13.840 --> 0:02:14.600 up in my head. 0:02:15.040 --> 0:02:16.680 Well that's all right, we're going to clear it all 0:02:16.800 --> 0:02:19.600 up today. And so you and I are very well 0:02:19.680 --> 0:02:22.040 organized people, so we record our episodes a few months 0:02:22.040 --> 0:02:24.200 before they actually come out. So for you and I, 0:02:24.320 --> 0:02:27.520 it actually has recently become the new year, So welcome 0:02:27.560 --> 0:02:31.280 to twenty twenty five. Do you believe in resolutions? 0:02:33.760 --> 0:02:36.160 I believe in self improvement. You know, I think people 0:02:36.200 --> 0:02:39.040 can take positive steps to change their life. I'm not 0:02:39.080 --> 0:02:42.040 one of those naysayers who says people never change, because 0:02:42.280 --> 0:02:45.840 my life has changed significantly in various ways over the years. 0:02:45.840 --> 0:02:48.480 So yeah, I think it's good for people to have introspection, 0:02:48.960 --> 0:02:51.200 think about their life, think about how it could change 0:02:51.240 --> 0:02:53.800 in the new year, especially when you're reaching out to 0:02:54.240 --> 0:02:56.760 folks who are in your community or used to be 0:02:56.800 --> 0:02:59.359 in your community. You know, personal connection is the thing 0:02:59.360 --> 0:03:02.040 that makes life wonderful. So reach out to somebody you 0:03:02.080 --> 0:03:05.000 haven't talked to in a while and make that connection again. 0:03:05.280 --> 0:03:09.240 That is a way deeper answer than I was expecting. Like, so, 0:03:09.320 --> 0:03:12.440 my resolutions aren't usually like think about how you could 0:03:12.440 --> 0:03:15.000 improve your personality and do something better, or reach out 0:03:15.000 --> 0:03:16.880 to an old friend. It's like, I want to get 0:03:16.960 --> 0:03:22.280 done this five resolution. I want two little baby ducks. 0:03:22.720 --> 0:03:25.080 That's not a resolution, that's a wish list. 0:03:26.080 --> 0:03:29.680 I resolved to build their habitat and make time in 0:03:29.720 --> 0:03:32.679 my life for you know, a happy, relaxing pens. 0:03:32.880 --> 0:03:35.240 I'm going to improve myself by adding ducks. 0:03:36.480 --> 0:03:39.600 Hell, that will make me happy. That's a happiness improver. 0:03:40.040 --> 0:03:42.440 Getting baby ducks and renovating my kitchen. Those are my 0:03:42.560 --> 0:03:45.680 twenty twenty five I guess they're goals now instead of resolutions. 0:03:45.840 --> 0:03:47.600 Do you have a resolution you want to share, then 0:03:47.840 --> 0:03:48.400 or a goal. 0:03:48.760 --> 0:03:50.280 I do have a resolution for the year, and it's 0:03:50.280 --> 0:03:53.440 about the podcast and its response to an email I 0:03:53.440 --> 0:03:57.680 got on January first at eight am, where somebody wrote 0:03:57.720 --> 0:04:01.240 in and says Happy New Year. Unfortunately, I can't listen 0:04:01.280 --> 0:04:06.680 to the show anymore because of the perpetual giggling, which 0:04:06.680 --> 0:04:10.240 of course just made me giggle. And I thought to myself, man, 0:04:10.280 --> 0:04:13.240 who doesn't like a podcast with giggling in it? And 0:04:13.280 --> 0:04:15.880 so this year, I'm gonna lean into the giggling. 0:04:16.320 --> 0:04:19.000 I resolve to giggle with you a lot over we 0:04:19.279 --> 0:04:23.359 hypercharges and strong forces and all sorts of other things. 0:04:23.360 --> 0:04:24.320 We're gonna have a blest. 0:04:24.400 --> 0:04:26.599 But it made me wonder about giggling, because you know, 0:04:26.640 --> 0:04:28.600 I have a bit of a deeper voice, and I've 0:04:28.600 --> 0:04:31.240 always thought myself as more of a chuckler than a giggler. 0:04:31.279 --> 0:04:33.159 And so I don't know, what are your thoughts, where's 0:04:33.160 --> 0:04:35.040 the distinction between giggling and chuckling. 0:04:35.440 --> 0:04:38.320 After we record an episode, our editor does the editing, 0:04:38.320 --> 0:04:39.800 he sends it to us. We listened to it to 0:04:39.800 --> 0:04:41.840 make sure we didn't get anything wrong, and I was 0:04:41.880 --> 0:04:43.640 listening to my laugh and I was like, I've got 0:04:43.640 --> 0:04:47.920 a really like sort of obnoxious, dude ish kind of laugh, 0:04:48.520 --> 0:04:51.240 But I don't care. It's unique. I'm happy and that's 0:04:51.279 --> 0:04:52.000 all I care about. 0:04:52.200 --> 0:04:55.280 Your laugh is not obnoxious. It's expressive. You know, you 0:04:55.320 --> 0:04:58.720 are really showing us how funny you think something is. 0:04:59.320 --> 0:05:02.400 It's very it's very New Jersey also though it is. 0:05:02.520 --> 0:05:04.000 Yeah, yeah, well I was born in New Jersey and 0:05:04.040 --> 0:05:05.640 am proud of that. Yeah. I don't hold back it. 0:05:05.680 --> 0:05:07.120 So I don't feel like either one of us do 0:05:07.200 --> 0:05:10.200 what I would call giggling. But whatever, we're having fun 0:05:10.320 --> 0:05:12.680 and let's resolve to lean into it absolutely. 0:05:12.680 --> 0:05:16.039 And I think a key to understanding difficult concepts is 0:05:16.080 --> 0:05:18.520 to giggle a little bit, right. You can't just always 0:05:18.600 --> 0:05:20.600 go deep on these concepts. You got to lighten the 0:05:20.640 --> 0:05:23.000 mood a little bit. That's kind of our brand, right, Like, 0:05:23.480 --> 0:05:26.800 make a few mom jokes along the way, throwing a 0:05:26.839 --> 0:05:29.360 few dad ponds, keep it light as we go deep 0:05:29.400 --> 0:05:30.320 on the topics. 0:05:29.960 --> 0:05:31.480 A couple jokes about Urinus. 0:05:34.600 --> 0:05:36.480 So hey, if you're here to learn some deep concepts 0:05:36.480 --> 0:05:39.760 about the universe and you are allergic to giggling, you 0:05:39.800 --> 0:05:41.159 might have found the wrong podcast. 0:05:41.800 --> 0:05:44.960 Sorry, there's got to be something else out there for you. 0:05:46.120 --> 0:05:48.400 But we are going to go deep into topics, and 0:05:48.520 --> 0:05:50.240 especially today, we're going to dig into one of my 0:05:50.320 --> 0:05:52.960 favorite concepts in physics, not just because it tells you 0:05:53.000 --> 0:05:55.640 something about how the universe works, but it shows you 0:05:55.680 --> 0:05:59.640 the mechanics of how physics as a field struggles with 0:05:59.760 --> 0:06:03.360 try to grapple with something alien. How we start from 0:06:03.360 --> 0:06:06.880 intuitive concepts and we build this precarious scaffolding to help 0:06:06.960 --> 0:06:09.760 us understand something even weird or and translate it back 0:06:09.760 --> 0:06:11.719 into something we might be able to make sense of. 0:06:12.120 --> 0:06:14.200 And I'm super excited today because you sent me the 0:06:14.240 --> 0:06:16.120 outline for this topic and there's a bunch of things 0:06:16.160 --> 0:06:17.800 when I was reading it through that made me think, 0:06:17.839 --> 0:06:20.760 oh gosh, I thought I knew the difference between like 0:06:20.839 --> 0:06:24.160 charge and force, but maybe I really don't. And I 0:06:24.240 --> 0:06:26.000 think a bunch of that's going to get cleared up today, 0:06:26.000 --> 0:06:27.880 and I'm glad that I'll be giggling along the way. 0:06:28.440 --> 0:06:29.800 And you know what's good for giggles. 0:06:29.839 --> 0:06:31.240 What's good for giggles, Kelly. 0:06:31.160 --> 0:06:33.600 The hilarious answers we get from our audience. I mean, 0:06:33.600 --> 0:06:35.719 we get lots of great, serious answers, but we also 0:06:35.800 --> 0:06:38.000 usually get some pretty funny ones when folks don't know 0:06:38.040 --> 0:06:40.440 what it is. So let's go ahead and giggle at 0:06:40.600 --> 0:06:41.719 lots of amazing answers. 0:06:41.839 --> 0:06:44.800 So today we're talking about electric charge and the weak fours, 0:06:44.880 --> 0:06:48.000 and specifically weak hypercharge. So I went out there to 0:06:48.120 --> 0:06:50.520 our volunteers and I asked them if they knew what 0:06:50.680 --> 0:06:54.080 weak hypercharge was. Think about it for yourself. Do you 0:06:54.240 --> 0:06:57.760 know what a weak hypercharge is? Here's what audience members 0:06:58.040 --> 0:07:00.480 had to say, All right, sort of. 0:07:00.440 --> 0:07:03.000 A permeter of property. It might even be a mathematical 0:07:03.040 --> 0:07:07.280 concept to describe the weak force. The week hypercharge is 0:07:07.320 --> 0:07:09.520 the value assigned to a particle participant. 0:07:10.720 --> 0:07:15.480 It's either some extortionate tax imposed by a cowardly government, 0:07:16.040 --> 0:07:20.400 or it's something associated with the weak field, which mirrors 0:07:20.480 --> 0:07:23.080 the electric charge in the electromagnetic field. 0:07:23.560 --> 0:07:30.320 Hypercharge combinds with isospin to somehow give a charge under 0:07:30.360 --> 0:07:32.080 the electro weak force. 0:07:32.240 --> 0:07:34.200 A charge state of the weak force. 0:07:34.480 --> 0:07:38.760 I have no idea weaknd hyper sounds like my childhood Nope, 0:07:40.000 --> 0:07:40.920 it's related to. 0:07:42.560 --> 0:07:43.560 Quantum physics. 0:07:43.680 --> 0:07:46.280 I have no idea what the hypercharge part would be 0:07:46.320 --> 0:07:48.280 and how I would tie it to the weak force. 0:07:48.400 --> 0:07:51.360 The weak hypercharge is the charge of the weak force. 0:07:51.480 --> 0:07:57.720 Encapsulates a particles in some particular force along with its 0:07:57.960 --> 0:08:01.800 spin and maybe mother information. I don't know what the 0:08:01.800 --> 0:08:03.760 weak Harper charge is, but it sounds like there's a 0:08:03.800 --> 0:08:05.120 stronger version of it somewhere. 0:08:05.280 --> 0:08:07.440 Well, that's pretty easy. That's when you try to do 0:08:07.480 --> 0:08:11.320 a hypercharge CAU and it's so weak it doesn't really. 0:08:11.240 --> 0:08:15.600 Charge a single factor that enumerates both like a particle's 0:08:15.640 --> 0:08:21.880 electric charge. It's weak charge and I don't know it's magnetic. 0:08:22.400 --> 0:08:26.920 All right, So I chuckled at sounds like my childhood 0:08:27.000 --> 0:08:29.280 and the one about attacks put on by a cowardly 0:08:29.320 --> 0:08:33.559 governmental agency. So thank you everyone for the giggles and 0:08:33.640 --> 0:08:34.920 the serious answers as well. 0:08:35.200 --> 0:08:37.480 Yes, and some of these serious answers are right on 0:08:37.679 --> 0:08:39.680 the money, so I was really impressed. 0:08:39.880 --> 0:08:40.880 Well, I'm not surprised. 0:08:40.960 --> 0:08:45.120 We have a brilliant and good looking too. Wow, that's right. 0:08:45.160 --> 0:08:47.040 That's what I think. It's called the halo effect. When 0:08:47.080 --> 0:08:48.559 somebody is good at one thing and then you just 0:08:48.600 --> 0:08:51.240 assume they're good at everything else. They're probably also like 0:08:51.320 --> 0:08:52.880 fits and fast. 0:08:52.559 --> 0:08:53.439 They smell good. 0:08:53.720 --> 0:08:57.920 Yeah, way to go, guys. All right, so let's start 0:08:57.960 --> 0:09:01.000 like super back at the beginning. Let's make sure we're 0:09:01.000 --> 0:09:03.600 all on the same page. With just even what is charge? 0:09:03.679 --> 0:09:08.479 Yeah? Oh wow, I'm supposed to answer that question. Whate'relie physicists? 0:09:08.679 --> 0:09:10.000 Yea, what is charge? 0:09:10.080 --> 0:09:12.559 So yeah, let's begin with charge, and let's just talk 0:09:12.600 --> 0:09:15.800 about charge descriptively first before we get into the philosophy 0:09:15.840 --> 0:09:19.199 of like what is it? Man? We know that electrons 0:09:19.240 --> 0:09:23.640 have negative charge, Protons have positive charge, right, electrons or 0:09:23.640 --> 0:09:27.000 minus one protons or plus one. So already we know 0:09:27.080 --> 0:09:30.319 something about charge, which is that it's associated with the 0:09:30.400 --> 0:09:33.640 number line. Right, it's a number. It can be zero, 0:09:33.720 --> 0:09:36.680 it can be positive, it can be negative, right, It 0:09:36.800 --> 0:09:40.880 also can be fractional. Quarks have two thirds of a 0:09:41.000 --> 0:09:44.040 charge or minus one third of a charge, so it's 0:09:44.040 --> 0:09:46.560 not an integer, right, So it's associated with the real 0:09:46.920 --> 0:09:50.840 number line. We don't know if they're rational or irrational charges. 0:09:51.000 --> 0:09:54.360 We've only ever seen fractional charges. But this tells us 0:09:54.360 --> 0:09:57.199 something that charge lies along this spectrum. It's important to 0:09:57.280 --> 0:09:59.440 keep that in mind because later on, when we get 0:09:59.480 --> 0:10:02.360 to the week four the strong force, that's no longer true. 0:10:02.840 --> 0:10:05.800 But let's stay on the safe ground of electricity. Particles 0:10:05.840 --> 0:10:07.920 have this thing we call charge. It can be positive, 0:10:08.040 --> 0:10:10.480 it can be negative, and there are mirrored versions of 0:10:10.520 --> 0:10:13.400 it like there's the electron that has negative one charge, 0:10:13.679 --> 0:10:17.000 and then there's another particle, the anti particle of the electron, 0:10:17.360 --> 0:10:19.960 which is a version of it with positive charge. We 0:10:20.040 --> 0:10:24.240 call that the positron. And every particle we've observed that 0:10:24.400 --> 0:10:27.439 has a charge, there's also a partner particle that has 0:10:27.480 --> 0:10:31.400 the opposite charge. The anti matter version of it has 0:10:31.440 --> 0:10:34.640 the opposite charge. So a cork might have one third charge, 0:10:34.679 --> 0:10:37.440 but the anti cork would have minus one third. 0:10:37.520 --> 0:10:39.960 For example, I'm thinking of like a number line, and 0:10:40.000 --> 0:10:43.040 we've got electrons with negative one and we've got protons 0:10:43.080 --> 0:10:46.160 with one. Are the magnitude of those charges the same 0:10:46.200 --> 0:10:49.120 in the different directions? Even though electrons are smaller and 0:10:49.240 --> 0:10:53.120 protons are bigger, they still have opposite charges. 0:10:53.559 --> 0:10:55.200 Yes, And when to put your finger on one of 0:10:55.200 --> 0:10:59.000 the deepest mysteries in physics right there. Because electrons and 0:10:59.000 --> 0:11:03.400 protons have opposite sign charges and exactly the same magnitude. 0:11:03.760 --> 0:11:06.120 It's like electrons are minus one point zeros or zeros 0:11:06.160 --> 0:11:09.200 z z is their infinite zeros and protons are plus 0:11:09.240 --> 0:11:13.040 one point zero zero. And how do we know they 0:11:13.080 --> 0:11:16.400 match exactly? Well, if they didn't match, you couldn't have 0:11:16.760 --> 0:11:19.840 neutral atoms. Right. You use a proton and an electron 0:11:19.920 --> 0:11:23.160 to make hydrogen, and then it's neutral, and it's crucial 0:11:23.240 --> 0:11:27.320 that hydrogen is neutral, right, Like hydrogen gas clouds are 0:11:27.440 --> 0:11:30.000 what forms most of the universe and the dynamics of 0:11:30.000 --> 0:11:32.480 that and the reason they gravity can pull them together 0:11:32.520 --> 0:11:35.840 to form stars is because it's neutral. Electricity, which is 0:11:35.960 --> 0:11:40.240 much more powerful than gravity, has been literally neutralized because 0:11:40.240 --> 0:11:42.839 these things cancel each other out. But as you say, 0:11:42.880 --> 0:11:46.160 the electron is much smaller than the proton. The electron is, 0:11:46.280 --> 0:11:50.000 we think fundamental, made of nothing but electron. The proton 0:11:50.160 --> 0:11:52.880 is made of three quarks. Two of them have two 0:11:52.920 --> 0:11:55.720 thirds charge, one of them has minus one third charge, 0:11:56.000 --> 0:12:00.080 which add up to plus one. Why is that? Why 0:12:00.080 --> 0:12:03.679 does the electron exactly balance this combination of quarks. Why 0:12:03.679 --> 0:12:06.320 isn't it like off by a little bit, Because in 0:12:06.360 --> 0:12:10.600 our theory those are just two different numbers, like there 0:12:10.600 --> 0:12:13.320 are parameters in our theories, knobs that you could change, 0:12:13.320 --> 0:12:16.200 and we think still have a valid universe, but a 0:12:16.280 --> 0:12:19.600 very different universe. We don't know why these two knobs 0:12:19.640 --> 0:12:22.720 happen to be set in exactly the way, so that 0:12:23.040 --> 0:12:25.440 the charge of the proton and the charge of the 0:12:25.440 --> 0:12:28.680 electron balance. It's like if I asked you to pick 0:12:28.960 --> 0:12:32.640 two random numbers between zero and a zillion and you 0:12:32.800 --> 0:12:36.480 picked the same number twice, or the number and its opposite, Like, 0:12:36.559 --> 0:12:39.560 what are the chances of that? So it's a screaming 0:12:39.640 --> 0:12:42.640 clue that there's a deep connection between the quarks and 0:12:42.679 --> 0:12:44.920 the electrons, but we don't know what it is. 0:12:45.320 --> 0:12:50.160 Okay, So a positron is an electron with a positive charge, 0:12:50.880 --> 0:12:54.719 and that positive charge is that positive charge now plus one, 0:12:54.840 --> 0:12:57.319 like the same quantity of charges a proton. Yes, you're 0:12:57.320 --> 0:13:01.360 shaking your head exactly, but it's not done with that's right, right. 0:13:01.640 --> 0:13:04.320 Yeah, So an electron doesn't switch its charge to become 0:13:04.520 --> 0:13:08.120 a positron. The universe can do two things. The universe 0:13:08.120 --> 0:13:12.280 can make electrons. The universe can also make positrons. And remember, 0:13:12.320 --> 0:13:15.280 electrons are ripples in a field, right the way like 0:13:15.320 --> 0:13:19.760 photons are ripple in the electromagnetic field. Electrons are also 0:13:19.840 --> 0:13:22.880 ripples in a field. They're ripples in the electron field. 0:13:22.960 --> 0:13:25.000 So we have two different fields that sound very similar. 0:13:25.200 --> 0:13:29.920 Bad naming becausists the electron field and the electromagnetic field. 0:13:30.080 --> 0:13:33.080 Ripples in the electron field are called electrons. Or it 0:13:33.120 --> 0:13:35.680 turns out that same field, not a different field. The 0:13:35.679 --> 0:13:39.160 same field can ripple in another way, and that way 0:13:39.440 --> 0:13:42.240 is a positron. So the electron field can ripple to 0:13:42.280 --> 0:13:46.560 make electrons, or can ripple slightly differently to make positrons. 0:13:47.040 --> 0:13:49.440 And this is something to Rack noticed years and years 0:13:49.440 --> 0:13:51.120 and years ago when he was looking at the math 0:13:51.480 --> 0:13:54.320 for electrons in field theory. He was like, hmm, if 0:13:54.320 --> 0:13:57.040 the universe can do this, why can't it also do that? 0:13:57.120 --> 0:13:59.240 In fact, I predict that it does. Then a couple 0:13:59.280 --> 0:14:02.760 of years later, boom, we found positrons. So you're right, 0:14:02.800 --> 0:14:06.360 positrons have the same electric charge as protons, but they're 0:14:06.440 --> 0:14:10.760 fundamentally very different. Positrons, we think, are fundamental particles ripples 0:14:10.800 --> 0:14:13.360 in the electron field that are different from the way 0:14:13.559 --> 0:14:17.720 electrons make that field ripple, and protons are a combination 0:14:17.840 --> 0:14:20.200 of three quarks, each of which is a ripple in 0:14:20.240 --> 0:14:21.040 its own field. 0:14:21.360 --> 0:14:23.440 Okay, all right, so this is. 0:14:23.360 --> 0:14:25.760 All descriptive, right, we're talking about what we've seen in 0:14:25.760 --> 0:14:28.360 the universe. We've seen this charge, we've seen that charge, 0:14:28.680 --> 0:14:31.480 and explaining in terms of fields makes us wonder like, well, 0:14:31.720 --> 0:14:35.160 what is this thing anyway? Like, why is it that 0:14:35.240 --> 0:14:38.440 some fields have charge, Like the electron field when it ripples, 0:14:38.480 --> 0:14:42.360 it has a charged particle, but when the photon field ripples, 0:14:42.400 --> 0:14:45.480 it doesn't have a charge, Like photons aren't neutral, right, 0:14:45.560 --> 0:14:50.080 So makes us wonder like what is charge anyway? Fundamentally? 0:14:50.320 --> 0:14:51.960 Yeah, go on, what's the answer? 0:14:52.720 --> 0:14:55.720 I was curious because I was like, is that just me? 0:14:56.000 --> 0:14:59.640 Like interested in philosophy and physics? Is a biologist like, well, 0:14:59.680 --> 0:15:01.160 we just grind it and we've given it a name. 0:15:01.200 --> 0:15:01.960 So let's move on. 0:15:03.360 --> 0:15:05.560 No, no, I following you. Let's go down the rabbit hole. 0:15:05.640 --> 0:15:07.040 Let's go one more level of why. 0:15:07.600 --> 0:15:10.680 And so we don't fundamentally know what charge is, but 0:15:10.720 --> 0:15:13.400 we have a bunch of interesting clues. And when I 0:15:13.480 --> 0:15:15.520 was growing up thinking and learning about charge, I used 0:15:15.520 --> 0:15:19.280 to think about charge as a property of a particle 0:15:19.760 --> 0:15:22.160 that could be like removed from it, you know, or 0:15:22.200 --> 0:15:25.040 it's like a description of how the particle is. You know, 0:15:25.160 --> 0:15:27.440 Like if you paint something red, Okay, now it's red, 0:15:27.480 --> 0:15:29.560 but you could also paint it blue and it's still 0:15:29.560 --> 0:15:31.360 the same thing. Right, Like you take an apple and 0:15:31.400 --> 0:15:33.720 it's red, you paint a blue. It's blue now, but 0:15:33.760 --> 0:15:37.000 it's still an apple, right? Or is it a fundamental 0:15:37.120 --> 0:15:39.680 part of the thing that helps define what it is. 0:15:39.680 --> 0:15:41.440 Is it something that you can take off of it, 0:15:41.480 --> 0:15:43.680 like you can peel an apple and then you still 0:15:43.720 --> 0:15:46.040 have an apple, right even though it's peeled. Can you 0:15:46.080 --> 0:15:49.400 take an electron and remove the charge from it and 0:15:49.440 --> 0:15:54.080 have like an peeled electron an uncharged electron, you know? 0:15:54.200 --> 0:15:57.560 Or is the charge fundamentally part of the electron? This 0:15:57.600 --> 0:15:59.440 is something I was always wondering about as I was 0:15:59.480 --> 0:16:02.920 learning about particle physics as a kid, and it's not 0:16:03.000 --> 0:16:05.920 something we have a solid answer for, but thinking about 0:16:05.920 --> 0:16:08.800 it in terms of fields helps. And so let's go 0:16:08.920 --> 0:16:11.840 back to thinking about particles in terms of ripples of fields, 0:16:12.000 --> 0:16:13.800 and I'll show you the role the charge plays in 0:16:13.800 --> 0:16:16.160 the field picture and it gives you a very different 0:16:16.240 --> 0:16:18.760 feel for what charge is fundamentally. 0:16:19.040 --> 0:16:20.960 My first thought was, Okay, is charge going to be 0:16:21.160 --> 0:16:23.960 just like an arbitrary thing that humans use in our 0:16:24.000 --> 0:16:27.560 definition for an electron, like charge in mass or is 0:16:27.560 --> 0:16:29.920 it going to be like do you use the example 0:16:29.920 --> 0:16:32.320 of painting it red or blue? And that doesn't change 0:16:32.320 --> 0:16:34.520 anything fundamental about it. But I think the fact that 0:16:34.560 --> 0:16:37.880 when you change the charge and you get like a positron, 0:16:37.880 --> 0:16:41.000 but they annihilate each other. They're behaving totally different, and 0:16:41.040 --> 0:16:43.360 so that feels different than just painting it red or blue. 0:16:44.000 --> 0:16:46.280 But okay, now let's talk about fields and see if 0:16:46.280 --> 0:16:47.080 we can dig into that. 0:16:47.040 --> 0:16:50.080 Deeper, because the field's picture of physics is going to 0:16:50.120 --> 0:16:52.640 tell us that charge is not a property of particles. 0:16:52.960 --> 0:16:56.080 It's actually a relationship between fields. 0:16:56.360 --> 0:16:59.480 I should have seen that coming. The field's always throw 0:16:59.520 --> 0:16:59.800 me off. 0:17:00.640 --> 0:17:02.720 So remember in the field picture, we still have particles. 0:17:02.760 --> 0:17:05.200 There are things we call particles. We have a different 0:17:05.240 --> 0:17:07.320 mental image for what they are. They're not little bits 0:17:07.320 --> 0:17:09.840 of stuff. There are ripples in these fields, and these 0:17:09.880 --> 0:17:13.480 fields fill the universe, and sometimes these fields can interact 0:17:13.560 --> 0:17:16.639 with each other. So now let's talk about forces. What 0:17:16.760 --> 0:17:19.600 happens to an electron when it's flying through space and 0:17:19.640 --> 0:17:23.600 it encounters an electric field, Well, it accelerates, either it 0:17:23.640 --> 0:17:25.080 slows it down or it speeds it up, but it 0:17:25.160 --> 0:17:28.400 changes its velocity. That's what an electric field is. That's 0:17:28.400 --> 0:17:31.600 what electric field does, right, And that means that there's 0:17:31.600 --> 0:17:33.720 a force on it. You accelerate something, you have to 0:17:33.720 --> 0:17:35.600 put a force on it. That's f equals ma A. 0:17:36.200 --> 0:17:38.920 But a neutral particle like a neutrino flying through the 0:17:38.920 --> 0:17:42.520 same electric field totally ignores it. Right, it will fly 0:17:42.640 --> 0:17:45.600 right through. It has no charge, and it ignores the 0:17:45.640 --> 0:17:48.280 electric field. Yeah, it's there, but it doesn't interact with 0:17:48.320 --> 0:17:51.080 it. It doesn't matter to It does not accelerate the neutrino. 0:17:51.640 --> 0:17:54.160 So you shoot an electron to an electric field, it accelerates. 0:17:54.520 --> 0:17:57.960 You shoot a neutral particle through electric field, nothing happens. 0:17:58.160 --> 0:18:02.560 So electric fields exert force on electrons, but electric fields 0:18:02.560 --> 0:18:05.159 don't exert force on neutrons exactly. 0:18:05.560 --> 0:18:09.160 Electric fields exert force on any particles with charge. 0:18:09.359 --> 0:18:09.679 Okay. 0:18:09.800 --> 0:18:11.679 And you might think, okay, well that's a useful way 0:18:11.760 --> 0:18:14.720 to describe what an electric field does. It's actually a 0:18:14.720 --> 0:18:18.760 description of what charge is. Charge is a label we 0:18:18.840 --> 0:18:21.800 put on particles that are accelerated by electric fields. 0:18:23.119 --> 0:18:25.280 Okay, So charge is the ability to be sped up 0:18:25.400 --> 0:18:27.399 or slowed down. Can you get slowed down by an 0:18:27.440 --> 0:18:28.200 electric field too? 0:18:28.280 --> 0:18:30.280 Yeah? Absolutely, you can get slowed down. Yeah, if you 0:18:30.280 --> 0:18:33.040 flip the direction of it. So charge is a label 0:18:33.080 --> 0:18:35.119 we put on it. Like let's say I give you 0:18:35.160 --> 0:18:37.120 an electric field and they give you a bunch of particles. 0:18:37.160 --> 0:18:39.399 I don't tell you anything about them. You throw them 0:18:39.440 --> 0:18:42.080 all into an electric field. Some of them slow down, 0:18:42.160 --> 0:18:44.920 some of them don't. The ones that slow down, you say, oh, 0:18:45.200 --> 0:18:47.960 this notices the electric field. I'm gonna put a label 0:18:48.000 --> 0:18:50.280 on that one. This notices the electric field in the 0:18:50.320 --> 0:18:53.280 opposite direction. I'm gonna put the negative label on that one. 0:18:53.400 --> 0:18:55.440 This one, it ignores the electric field. I'm putting a 0:18:55.560 --> 0:18:59.159 zero on that one. All right, So charge is a 0:18:59.200 --> 0:19:02.200 label we put on on particles that sense electric fields. 0:19:02.560 --> 0:19:04.360 So now let's go back to the fields. Picture what's 0:19:04.400 --> 0:19:07.480 happening there. The electron is flying through space. It's a 0:19:07.560 --> 0:19:10.679 ripple in the electron field. Now, an encounter is an 0:19:10.720 --> 0:19:14.119 electric field, which is energy in the electromagnetic field. What 0:19:14.240 --> 0:19:16.920 happens is those two fields are coupling with each other. 0:19:17.080 --> 0:19:22.120 Energy is going from the electromagnetic field to the electron field. Right, 0:19:22.160 --> 0:19:26.480 it's accelerating the electron or it's decelerating whichever, but energy 0:19:26.520 --> 0:19:29.720 is passing. These two fields are coupling together. So instead 0:19:29.720 --> 0:19:32.600 of just having like one field slashing through space doing 0:19:32.680 --> 0:19:35.240 its own thing and another field slashing through space doing 0:19:35.280 --> 0:19:38.199 its own thing, think of them as like tied together. Right, 0:19:38.240 --> 0:19:42.080 there's a connection between them. It's like having two guitar strings. 0:19:42.240 --> 0:19:44.720 But now you have like a rubber band connecting them. 0:19:44.880 --> 0:19:47.320 So when one oscillates, the other one's gonna oscillate. Also, 0:19:48.000 --> 0:19:52.119 that's what charge is. Charge is a coupling between two 0:19:52.359 --> 0:19:57.000 fields for two different fundamental particles. So when the electron 0:19:57.080 --> 0:19:59.960 moves through space, it makes ripples in the electromagnetic field, 0:20:00.800 --> 0:20:03.240 and if there's a field there, it pushes on the electron. 0:20:03.280 --> 0:20:07.840 It slashes back and forth between electrons and the electromagnetic field, 0:20:07.960 --> 0:20:10.879 and charge tells us how that works. If you have 0:20:10.920 --> 0:20:13.520 a zero, then there's no coupling. If you have a one, 0:20:14.000 --> 0:20:15.879 then they are coupled. If you have a mindus one, 0:20:16.000 --> 0:20:17.600 you couple the opposite direction. 0:20:18.240 --> 0:20:22.000 Okay, all right, so first we're talking about strings, but 0:20:22.040 --> 0:20:23.359 it has nothing to do with string theory. 0:20:23.480 --> 0:20:26.919 Now we talk about strings because strings follow the wave equation, 0:20:27.040 --> 0:20:29.359