WEBVTT - What Is Quantum Spin? 0:00:00.120 --> 0:00:09.680 Ythaniel. Do you ever get caught using a word that 0:00:09.760 --> 0:00:13.080 you don't really understand? Do you actually always know what 0:00:13.119 --> 0:00:16.440 you're talking about? I don't think I'm willing to devote 0:00:16.480 --> 0:00:18.759 that here on the podcast, and maybe we can have 0:00:18.840 --> 0:00:22.479 that conversation over a beer sometimes. But the thing that 0:00:22.520 --> 0:00:25.240 I love is that there are some topics in physics, 0:00:25.239 --> 0:00:29.120 some idea, some words that I'm pretty sure nobody actually 0:00:29.160 --> 0:00:33.519 really understands. I feel like this is taking us to 0:00:33.800 --> 0:00:38.559 another episode about quantum physics that's right and wrong at 0:00:38.560 --> 0:00:47.640 the same time. No, I mean, yes, exactly what at 0:00:47.640 --> 0:01:07.120 the same time. Hi'm Jorge. I'm a cartoonist and the 0:01:07.200 --> 0:01:11.160 creator of PhD Comics. Hi I'm Daniel, I'm a particle physicist, 0:01:11.560 --> 0:01:14.960 and Welcome to our podcast, Daniel and Jorge Explain the Universe, 0:01:15.160 --> 0:01:17.679 a production of I Heart Radio in which we take 0:01:17.840 --> 0:01:20.959 crazy and fascinating and amazing and hot and wet and 0:01:21.040 --> 0:01:23.880 nasty things about the universe and try to explain them 0:01:23.920 --> 0:01:27.360 to you. Today's episode is dedicated to a Lana, whose 0:01:27.400 --> 0:01:30.120 boyfriend Nick is a local fan of the podcast here 0:01:30.120 --> 0:01:38.600 in Irvine. Happy Birthday, Alana. Today's topic is a really 0:01:38.640 --> 0:01:41.560 fun one, and in preparation for it. Not only did 0:01:41.600 --> 0:01:44.360 I go and do the normal street interviews I usually 0:01:44.360 --> 0:01:46.880 do with random people, but I actually went around the 0:01:46.880 --> 0:01:49.000 halls of my physics department and I asked a bunch 0:01:49.000 --> 0:01:52.000 of grad students if they could explain today's topic for me, 0:01:52.160 --> 0:01:55.200 and they found it pretty tough. Wow, that's a pretty 0:01:55.240 --> 0:02:00.400 interesting spin on the topic in our process. That's right, 0:02:00.640 --> 0:02:02.280 that's right to be on the podcast. We're going to 0:02:02.320 --> 0:02:11.639 be talking about quantum spin exactly. Quantum spin? What is it? 0:02:11.880 --> 0:02:14.720 What does it mean? Are things actually spinning? Why is 0:02:14.760 --> 0:02:18.000 it quantum um? We've got a lot of people sending 0:02:18.000 --> 0:02:20.359 in requests to talk about this topic. And I think 0:02:20.360 --> 0:02:23.040 when people are interested in physics and digging around in 0:02:23.160 --> 0:02:25.519 videos on the internet and listening to podcast you hear 0:02:25.600 --> 0:02:28.519 this come up a lot. It comes up in quantum entanglement, 0:02:28.560 --> 0:02:31.480 It's in science fiction everywhere, and of course people want 0:02:31.520 --> 0:02:34.200 to know what does it mean, what's going on? Why 0:02:34.240 --> 0:02:37.000 is it so important? That's right? What is spin? How 0:02:37.040 --> 0:02:40.680 fast is it spinning? What's the spin on it? Exactly? 0:02:40.880 --> 0:02:43.280 Is it's spinning out of control? That's right? Is it 0:02:43.360 --> 0:02:46.760 different from political spin? Um? It's definitely a thing, right, 0:02:46.800 --> 0:02:50.000 It's something fascinating and more importantly, if you're an expert 0:02:50.000 --> 0:02:52.160 in this field, does that make you a spin doctor 0:02:53.480 --> 0:02:57.280 doctor of spin? Yes, exactly. You know, we have sort 0:02:57.320 --> 0:03:00.359 of a bad track record in physics of naming things 0:03:01.080 --> 0:03:06.520 um naming things using familiar words, like we give corks flavors, right, 0:03:06.919 --> 0:03:08.919 the up cork and the charm cork and the top 0:03:08.960 --> 0:03:12.839 cork a different flavors of corks, colors and colors, right 0:03:12.960 --> 0:03:16.400 when they don't really have color, they don't really have color, 0:03:16.800 --> 0:03:18.840 and they don't really taste different. I mean, I don't know, 0:03:18.880 --> 0:03:21.920 I've never actually tasted a top cork, So there you go. 0:03:21.960 --> 0:03:24.560 I'm speaking on something I don't really understand, but we 0:03:24.600 --> 0:03:26.840 don't mean it in that way. So sometimes we're like 0:03:26.880 --> 0:03:31.919 adopting existing words and just using them totally inappropriately. Other 0:03:32.040 --> 0:03:35.000 times we're trying to use words that are similar to 0:03:35.160 --> 0:03:38.760 some other concepts because specifically because we want to call 0:03:38.880 --> 0:03:42.040 up structures and ideas from those concepts. Like color is 0:03:42.080 --> 0:03:45.200 actually a pretty cool one because while the particles are 0:03:45.240 --> 0:03:49.600 not colored, there's something about quantum color which is similar 0:03:49.640 --> 0:03:52.400 to color, and so we want to express that. You're 0:03:52.400 --> 0:03:55.960 sort of trying to grab onto an intuitive idea, even 0:03:56.040 --> 0:03:58.640 if you're trying to like a reference, you're trying to 0:03:58.680 --> 0:04:03.000 reference an intuitive idea in our everyday experience and and 0:04:03.080 --> 0:04:06.000 kind of latch that onto a physics concept exactly. And 0:04:06.040 --> 0:04:08.000 we do that all the time, right, That's basically what 0:04:08.080 --> 0:04:11.360 physics is is try to explain the unknown in terms 0:04:11.400 --> 0:04:13.960 of the known, right, Like when we try to talk 0:04:14.000 --> 0:04:16.440 about particles, we're doing that all the time. You know, 0:04:16.480 --> 0:04:18.920 we're saying, oh, it's a particle, No, it's a wave. Right, 0:04:19.400 --> 0:04:21.599 It's really neither, and it's both and it's something else 0:04:21.640 --> 0:04:24.279 more complicated, And we're just trying to patch together a 0:04:24.320 --> 0:04:28.440 description of using ideas in your head, right, we weave 0:04:28.520 --> 0:04:31.320 these together into some sort of understanding. Here's such a 0:04:31.360 --> 0:04:33.720 suggestion for you guys. Maybe you should just instead of 0:04:33.720 --> 0:04:37.240 calling being bold and calling it like colors or flavors, 0:04:37.360 --> 0:04:40.159 just at the word, like at the beginning in your 0:04:40.160 --> 0:04:43.960 official definition. So the announcement should be like, like we're 0:04:43.960 --> 0:04:48.480 calling this color, I mean, like let's call flavor. No, 0:04:48.640 --> 0:04:52.720 I just call it like a quantum light color. It's 0:04:52.800 --> 0:04:55.880 light color. It has a color like property or a 0:04:55.920 --> 0:04:58.760 spin like property, or you know, I mean, if you 0:04:58.760 --> 0:05:00.880 want to get mathematically, just with a little Tilda in 0:05:00.920 --> 0:05:04.520 the front right, and then nobody would be confused. Yeah, 0:05:04.560 --> 0:05:09.880 I like that idea a lot good. You like like it? Yeah, 0:05:09.920 --> 0:05:12.000 I totally like it, and I think, um, I hope 0:05:12.040 --> 0:05:14.680 on Twitter it gets a lot of likes. There you go. 0:05:15.360 --> 0:05:18.039 I think I want to something. I think I think 0:05:18.160 --> 0:05:22.960 you should be nominated onto the secret International Physics Naming Committee. 0:05:23.160 --> 0:05:24.640 I don't know where it meets or when it meets, 0:05:24.680 --> 0:05:26.200 or who's in charge of it, but they have been 0:05:26.240 --> 0:05:29.440 making some dubious decisions recently and they need some fresh blood. Well, 0:05:29.440 --> 0:05:31.039 I think if I was in charge, I would just 0:05:31.080 --> 0:05:33.480 put the tilt in front of physics itself. You know, 0:05:34.120 --> 0:05:38.440 what are you study till the physics? Physics? I'm studying 0:05:38.520 --> 0:05:44.240 something like physics, but it's not actually, I mean, isn't 0:05:44.279 --> 0:05:48.520 everything like physics? Pretty next thing, you're gonna be calling 0:05:48.560 --> 0:05:51.880 me like a physicist, not actually a physicist, but something 0:05:52.000 --> 0:05:56.000 like approximating a physicist. You know, you're gonna spread this 0:05:56.680 --> 0:06:00.159 Tilda Daniels sort of like a Daniel into it. Lee, 0:06:00.160 --> 0:06:02.240 You're Daniel. You know I'm actually a Daniel. I am 0:06:02.240 --> 0:06:08.760 the definition of me, right, You're Daniel sub zero exactly. 0:06:09.120 --> 0:06:12.320 I'm not like me I am me, right, you are, 0:06:12.760 --> 0:06:15.719 I think therefore I am Daniel. Well, anyways, before we 0:06:15.760 --> 0:06:19.320 spin out of control here on this um side conversation, um, 0:06:19.360 --> 0:06:21.600 we're talking about quantum spin, and so it's it. It 0:06:21.640 --> 0:06:25.320 plays a big deal in quantum physics and quantum entanglement, right, 0:06:25.400 --> 0:06:28.920 and atomic orbitals. I mean it's it's sort of it's 0:06:28.960 --> 0:06:32.880 important in everybody's atoms, which um which are a kind 0:06:32.880 --> 0:06:36.159 of important to people, that's right. I like my atoms, 0:06:36.200 --> 0:06:39.039 you know, they're not like atoms. I just like them. 0:06:39.040 --> 0:06:41.680 But exactly, spin is everywhere, and you hear come up, 0:06:41.720 --> 0:06:45.280 and especially when you're hearing explanations of quantum entanglement or 0:06:45.360 --> 0:06:49.119 quantum computing or or orbitals and this kind of stuff, 0:06:49.120 --> 0:06:51.679 you hear about it. And when I was a student 0:06:51.720 --> 0:06:54.000 and I was learning about quantum spin, I was like, okay, 0:06:54.000 --> 0:06:57.000 but what is it like? Are these things actually spinning? 0:06:57.040 --> 0:06:59.000 Why do we call it spin? Right? How could a 0:06:59.040 --> 0:07:02.920 particle spin? And so let's dig into all that today. Well, 0:07:02.960 --> 0:07:05.840 as usual, Daniel went out there and asked people in 0:07:05.920 --> 0:07:09.440 the street if they knew what quantum spin was. And 0:07:09.560 --> 0:07:12.240 you actually have kind of an interesting spin twid this time, right, Yeah, 0:07:12.240 --> 0:07:13.760 I went out and I asked people on the U 0:07:13.800 --> 0:07:16.320 C Irvine campus and then a few other folks at 0:07:16.360 --> 0:07:19.440 the at an Irvine mall Um what they thought quantum 0:07:19.480 --> 0:07:21.840 spin was, if they could describe it, and if they 0:07:21.840 --> 0:07:24.680 did understand quantum spin. I also asked them, are these 0:07:24.720 --> 0:07:28.680 particles actually spinning or is that just like spin? Is 0:07:28.680 --> 0:07:31.200 that just like a word we use. Well, here's what 0:07:31.240 --> 0:07:34.960 people had to say, um, so energy, I just think 0:07:34.960 --> 0:07:39.120 of energy. Oh yes, what's the quantum spin? Uh? Like 0:07:39.200 --> 0:07:43.080 quantum spin as an like spin up, spin down with 0:07:43.080 --> 0:07:49.600 within molecular orbitals and electrons um. So are those particles 0:07:49.640 --> 0:07:59.760 like actually spinning gesa Uh No, I haven't quantum spin? No? 0:08:00.520 --> 0:08:04.360 Uh yeah, it's electron spin um that it can be 0:08:04.480 --> 0:08:08.280 positive or negative um. And then how's it different from 0:08:08.320 --> 0:08:11.280 normal spin? Like a tennis ball can spin? Is electron 0:08:11.400 --> 0:08:15.120 spain the same thing? Are they physically spinning? Uh? I'm 0:08:15.160 --> 0:08:20.800 not sure. I know some stuff about Polly's principle that 0:08:20.920 --> 0:08:23.640 the spin should be in a specific way, and they're prepared, 0:08:23.920 --> 0:08:27.560 so I know some way in distunt stuff, but I'm 0:08:27.640 --> 0:08:31.760 not sure about the people. Right. Yeah, isn't because um 0:08:31.880 --> 0:08:34.320 every electron has a different type of spin. It's like 0:08:34.360 --> 0:08:36.160 either a plus one half a minus one half. I 0:08:36.200 --> 0:08:39.320 forgot what it would Yeah, and are they like actually spinning. 0:08:39.400 --> 0:08:41.160 Is it like the same thing as a tennis ball spinning? 0:08:41.240 --> 0:08:44.640 Or is it's um? No, because it's not like because 0:08:45.679 --> 0:08:47.760 you can't treat it like it's a particle, right, because 0:08:48.400 --> 0:08:51.360 it's um like an electron is a mix of a 0:08:51.440 --> 0:08:54.240 particle and a way. I've heard of it, but I'm 0:08:54.240 --> 0:08:57.080 not familiar with the meaning. Okay, No, I don't know 0:08:57.120 --> 0:09:00.360 what that is, all right. Yes, there's up and down spin, right, 0:09:01.040 --> 0:09:03.360 and it's in me. Uh well, I don't know much 0:09:03.400 --> 0:09:06.480 more than that, Okay, all right. It seemed very binary. 0:09:06.760 --> 0:09:09.680 Some people had had no idea, never even heard of it, 0:09:09.720 --> 0:09:12.480 and some people had a lot to say about this topic. Yeah, 0:09:12.520 --> 0:09:14.400 and some people knew some stuff sort of in the 0:09:14.480 --> 0:09:17.360 vicinity of the topic, but not actually like reluing to 0:09:17.400 --> 0:09:21.400 the question the vicinity. Yeah, yeah, exactly. I like when 0:09:21.400 --> 0:09:23.520 when I asked somebody question and I can tell they 0:09:23.520 --> 0:09:26.000 haven't thought about this in a long time, and they 0:09:26.000 --> 0:09:28.000 have sort of like a free association going off in 0:09:28.040 --> 0:09:30.319 their mind that wait, this is connected to that idea, 0:09:30.400 --> 0:09:32.640 to that idea of that idea, and then they go no, Actually, 0:09:32.640 --> 0:09:35.760 I don't know. I don't know the answer. That's really fun, 0:09:35.840 --> 0:09:38.200 but you can see their process. Yeah, because a lot 0:09:38.200 --> 0:09:40.120 of people to be heard about it or read about 0:09:40.120 --> 0:09:42.880 it a long time ago, maybe in high school physics 0:09:42.960 --> 0:09:45.320 or something, and so you sort used to feel like 0:09:45.320 --> 0:09:47.400 it's in there in your brain. You just need some 0:09:47.480 --> 0:09:50.840 time to you know, boot up the hard drives. Yeah, exactly. 0:09:50.960 --> 0:09:53.440 But I think my favorite part of this experience asking 0:09:53.480 --> 0:09:56.720 people these questions was that one gentleman after I asked him, um, 0:09:56.720 --> 0:09:59.000 if you knew about quantum spin, he then asked me, 0:09:59.040 --> 0:10:01.360 he said, is this some thing you need for your dissertation? 0:10:04.760 --> 0:10:08.320 Said yes, yes, sir, Yes, sir, I am a twenty 0:10:08.360 --> 0:10:11.840 five year old graduate student. Absolutely, are you saying that 0:10:12.280 --> 0:10:15.120 you can be a grad student at forty something? There 0:10:15.160 --> 0:10:16.960 are fewer of them. Yes, there are a few or 0:10:16.960 --> 0:10:18.720 forties something year old grad students. But I have to 0:10:18.720 --> 0:10:21.400 say the ones that are forty years old, like folks 0:10:21.480 --> 0:10:23.280 that went out into the real world and worked in 0:10:23.320 --> 0:10:25.680 real estate or law or something and then came back 0:10:25.760 --> 0:10:29.120 to do physics grad school, they're really good students. They 0:10:29.200 --> 0:10:31.360 really want it. Yeah, it takes a it's a lot 0:10:31.400 --> 0:10:34.280 of work to divert from a path in the real 0:10:34.280 --> 0:10:37.080 world back into academia. It's much harder than just like 0:10:37.320 --> 0:10:39.840 going from undergrad to grad school. So I really respect that. 0:10:39.880 --> 0:10:42.720 You know, you gotta really want it cool. So if 0:10:42.760 --> 0:10:45.040 there are any there, any listeners out there who want 0:10:45.080 --> 0:10:47.880 to change careers and get a PhD, they should contact you, 0:10:48.000 --> 0:10:51.400 right and you have a spot for them. I'm not 0:10:51.440 --> 0:10:53.800 sure I just offered anybody funding, but I would encourage you. 0:10:53.840 --> 0:10:55.640 If you have a deep passion for physics and you're 0:10:55.640 --> 0:10:57.880 finding yourself in a dead end job and you wish 0:10:57.920 --> 0:11:00.640 you had gone to physics grad school to unraveled mr 0:11:01.000 --> 0:11:04.559 of the universe, I encourage you, sir and ma'am, if 0:11:04.559 --> 0:11:09.280 you'd like to be in another dead end of of 0:11:09.360 --> 0:11:12.400 awesome knowledge, then be a cartoonist. Is that what you're 0:11:12.400 --> 0:11:19.800 gonna say? Yes? Yes, alright, So Daniel, let's break it 0:11:19.840 --> 0:11:24.280 down for people. What is quantum spin? We don't know? 0:11:25.760 --> 0:11:31.280 Done podcast over, why we had to diversely so much? 0:11:31.440 --> 0:11:33.920 Just do fill fill in the air time? Um, So 0:11:34.040 --> 0:11:36.480 people don't know because I don't know what quantum spin is. 0:11:36.600 --> 0:11:38.400 We don't really know what it is. Now we know 0:11:38.480 --> 0:11:41.559 it's a thing, right, So there's this thing, this property 0:11:41.600 --> 0:11:43.920 of particles. We don't really understand what it is, what 0:11:44.000 --> 0:11:46.920 it's doing. But there's this thing we've observed and we 0:11:47.040 --> 0:11:49.679 call it quantum spin. So let's do that. Let's talk 0:11:49.679 --> 0:11:51.920 about what this thing is that we can observe, and 0:11:51.960 --> 0:11:54.360 then we'll talk about why we call it quantum spin. 0:11:54.440 --> 0:11:56.680 And you know whether it's actually spinning and stuff. Right, Well, 0:11:56.800 --> 0:11:59.080 what's the origin of this? How did this come to 0:11:59.120 --> 0:12:00.920 be a thing? And it came to be a thing 0:12:01.120 --> 0:12:06.320 basically because of magnets, right, and you remember that charged particles. 0:12:06.360 --> 0:12:07.920 So a little particle with the charge on it, like 0:12:07.960 --> 0:12:10.800 an electron, if you move it in a circle, right, 0:12:10.880 --> 0:12:14.160 like through a wire loop or something, then it makes 0:12:14.160 --> 0:12:16.520 a magnetic field. Right, you can turn it on and 0:12:16.559 --> 0:12:19.319 off like electro magnets. This is how they work, right, 0:12:19.360 --> 0:12:22.720 like motors everyday electric motors, motors in your car and 0:12:22.880 --> 0:12:26.800 in your electric car, and you're um even your phone, right, 0:12:26.800 --> 0:12:29.760 there's probably a little motor of solenoid doing the vibrations 0:12:30.280 --> 0:12:32.600 when you put it on vibrate mode. That that's the principle. 0:12:32.760 --> 0:12:36.600 Like they just pump electrons through a coil a little loop, 0:12:36.640 --> 0:12:39.800 and then that creates a magnetic magnetic field which moves something. 0:12:40.000 --> 0:12:41.680 That's right. And the cute cool thing there is you 0:12:41.679 --> 0:12:44.840 have a magnet you can control electronically or digitally. So 0:12:44.880 --> 0:12:47.440 that's pretty awesome. But the important concept there is that 0:12:47.559 --> 0:12:50.080 things moving in a circle. Charges moving in a circle 0:12:50.360 --> 0:12:52.880 give you a magnetic field. Right, So that's something we 0:12:52.960 --> 0:12:56.199 know about, right, something we understand. And so then people 0:12:56.200 --> 0:13:01.040 were asking the question, um, well, do electrons themselves like 0:13:01.200 --> 0:13:04.480 individual particles? Do they have little magnets on them, like 0:13:04.600 --> 0:13:06.640 not just moving in a circle, but is there a 0:13:06.679 --> 0:13:09.040 magnetic field just due to the particle? And this is 0:13:09.040 --> 0:13:11.360 the kind of thing physicists do. They're like, well, we 0:13:11.400 --> 0:13:14.000 don't expect this to be this way, but let's just check, right, 0:13:14.040 --> 0:13:17.280 let's see if this happens. Because back then maybe they 0:13:17.280 --> 0:13:20.960 thought particles were like little little balls, right maybe yeah, 0:13:21.040 --> 0:13:23.360 well they didn't know. Right, this is in the nineteen twenties, 0:13:23.440 --> 0:13:26.040 this is almost a hundred years ago. The whole idea 0:13:26.080 --> 0:13:29.439 of a particle was still pretty new. People discovered electrons 0:13:29.440 --> 0:13:32.200 and neutrons and you know, it was a crazy era 0:13:32.240 --> 0:13:35.319 of discovery. They were maybe asking, like, is one electron 0:13:35.679 --> 0:13:38.960 maybe like a magnet itself? Yes, exactly right, And that's 0:13:38.960 --> 0:13:40.840 what they were wondering about. And so if it's a magnet, 0:13:40.880 --> 0:13:43.800 it would have a direction, right, like a field exactly 0:13:43.840 --> 0:13:45.880 what it have its own little magnetic field. So that 0:13:45.920 --> 0:13:47.600 was the question they were trying to answer, like does 0:13:47.640 --> 0:13:50.319 an electron or a silver atom or whatever, a little 0:13:50.320 --> 0:13:53.800 particle have its own magnetic field. So what they did 0:13:53.880 --> 0:13:57.120 is they built this device that would um that. Basically, 0:13:57.160 --> 0:13:59.520 they put particles in this device and the device has 0:13:59.559 --> 0:14:01.880 a magnet nick field on it, and they move the 0:14:01.920 --> 0:14:04.040 particles through the device, not in a circle, just in 0:14:04.040 --> 0:14:06.760 a straight line. And the idea is that the device 0:14:06.800 --> 0:14:10.000 has magnets in it. So if the particles have their 0:14:10.000 --> 0:14:12.400 own magnetic field, then they'll get pushed to one side 0:14:12.440 --> 0:14:14.840 because the magnets on the particle would interact with the 0:14:14.880 --> 0:14:18.400 magnets um from this device and would push the particles 0:14:18.400 --> 0:14:20.000 to one side or the other, kind of like like 0:14:20.080 --> 0:14:22.400 if you not through an electron, but if you through 0:14:22.480 --> 0:14:25.680 like an actual magnet, like a fridge magnet, if you 0:14:25.880 --> 0:14:29.360 threw it at some other magnets, it would get deflected, right, yeah, exactly, 0:14:29.640 --> 0:14:32.320 it would get deflected. Now, most magnets are balanced, right, 0:14:32.320 --> 0:14:34.520 Most magnets have a north and a south. So say 0:14:34.560 --> 0:14:37.280 you set up like a really strong pair of magnets 0:14:37.640 --> 0:14:39.840 and then you threw a fridge magnet through it, probably 0:14:39.880 --> 0:14:42.960 wouldn't get deflected because it has a north and a south, 0:14:43.000 --> 0:14:45.160 and so the polls would get balanced. So what they 0:14:45.200 --> 0:14:48.320 did was they set up one really big magnet and 0:14:48.320 --> 0:14:50.280 then a weaker magnet on the other side, so there's 0:14:50.400 --> 0:14:53.920 like an uneven magnetic field through it, so that if 0:14:53.920 --> 0:14:56.880 your fridge magnet goes through it, depending on the angle 0:14:57.000 --> 0:14:58.840 of the magnet, depending on the angle of the north 0:14:58.880 --> 0:15:00.880 and the south, they'll get pulled the one direction or 0:15:00.920 --> 0:15:04.880 the other. So they build the particle version of this, Right, 0:15:04.920 --> 0:15:07.680 They an uneven magnetic field, and they shot some particles 0:15:07.680 --> 0:15:11.800 through it, and what they found was really surprising, Right, 0:15:12.080 --> 0:15:14.560 it was really shocking what they discovered. They found that 0:15:14.640 --> 0:15:17.440 particles do have magnetic fields. Yeah. Well, first of all, 0:15:17.520 --> 0:15:20.320 they found two things that were surprising. One, particles do 0:15:20.400 --> 0:15:23.120 have their own little magnetic fields. I mean, first they 0:15:23.160 --> 0:15:25.000 did it with silver atoms, which is sort of the 0:15:25.040 --> 0:15:27.320 easiest thing they could do to to make a beam. 0:15:27.440 --> 0:15:29.120 Then this is a long time ago before you could 0:15:29.160 --> 0:15:31.400 easily make like a beam of particles. They just put 0:15:31.400 --> 0:15:33.480 a bunch of silver in an oven and like some 0:15:33.520 --> 0:15:35.920 of it boiled off and they collimated it and got 0:15:35.960 --> 0:15:37.720 a beam of silver atoms. And then later they did 0:15:37.800 --> 0:15:40.320 the same thing with electrons, and they found that these 0:15:40.360 --> 0:15:43.040 things have their own little magnets. Like an electron is 0:15:43.120 --> 0:15:45.840 a magnet, which is kind of perplexing, like what does 0:15:45.880 --> 0:15:48.200 that mean? Like where does this magnet come from? Right? 0:15:48.840 --> 0:15:50.520 But what does it mean that it's a magnet? Like 0:15:50.560 --> 0:15:52.920 if I just look at an electron, it has like 0:15:52.960 --> 0:15:56.040 a north and south poll to it. Yes, exactly. Electrons 0:15:56.080 --> 0:15:58.480 have their own little magnetic fields, even when they're not 0:15:58.600 --> 0:16:01.480 moving in a circle, even if they're not moving at all, 0:16:01.720 --> 0:16:03.640 Like if you suspended a like current, can you can 0:16:03.680 --> 0:16:06.040 you do it? Yeah? Yeah, exactly. If you have an 0:16:06.080 --> 0:16:08.880 electron just floating motionless in mid air, it will have 0:16:08.920 --> 0:16:14.160 its own little magnet. And that's really weird to us now, right, 0:16:14.240 --> 0:16:17.600 because we know that part of electrons and particles, they're 0:16:17.640 --> 0:16:20.920 not like little balls or just points. Yes, exactly, and 0:16:21.000 --> 0:16:23.800 so the question of where does that magnet come from? 0:16:23.840 --> 0:16:26.280 That's where this whole idea of spin came from. But 0:16:26.520 --> 0:16:29.400 the other really weird thing they found was that the 0:16:29.440 --> 0:16:32.680 magnets didn't point in every direction, Like if you just 0:16:32.720 --> 0:16:35.840 throw a bunch of magnets through this device, if they're 0:16:35.880 --> 0:16:39.240 all pointed in different directions. Right is just randomly oriented, 0:16:39.400 --> 0:16:42.280 you'd expect them to get deflected in random directions. This 0:16:42.320 --> 0:16:44.120 one goes left, this one goes right, this one goes 0:16:44.160 --> 0:16:45.920 a little bit up, this one goes a little bit down. 0:16:46.240 --> 0:16:48.320 But you know, if they're randomly organized, they should go 0:16:48.360 --> 0:16:51.640 in all sorts of directions, right, But what they found 0:16:52.120 --> 0:16:54.640 was that they either went left or they went right. 0:16:55.120 --> 0:16:57.680 There was not nothing in between, Like it's either left 0:16:57.760 --> 0:17:00.880 or right and nothing else, like, those are your two options, really, 0:17:01.200 --> 0:17:04.320 and no variations and how much right or how much left? Yeah, 0:17:04.400 --> 0:17:07.000 they all went exactly the same amount left or this 0:17:07.160 --> 0:17:11.360 exactly the amount right? What, Yeah, exactly. And that's why 0:17:11.400 --> 0:17:14.119 we call it quantum. Right, they have this little quantum 0:17:14.160 --> 0:17:17.159 magnetic field. The amazing thing is that, say, then you 0:17:17.280 --> 0:17:20.120 rotate the device, you're like, okay, rotated ninety degrees. Maybe 0:17:20.119 --> 0:17:22.360 you were measuring it on the X axis. Now you're 0:17:22.359 --> 0:17:25.560 measuring on the y axis, right, so you're imagining, okay, well, 0:17:25.600 --> 0:17:29.080 maybe these particles just you know, we're somehow weirdly oriented 0:17:29.119 --> 0:17:31.400 along the x axis, so they either go left or right. 0:17:31.600 --> 0:17:35.280 So then rotate your device ninety degrees. Then all the 0:17:35.400 --> 0:17:39.320 particles either move up or down right. No matter how 0:17:39.359 --> 0:17:42.600 you orient the device, the particles either go along the 0:17:42.640 --> 0:17:45.159 magnet or against it. Right. So it's not like a 0:17:45.720 --> 0:17:49.600 it's not like a real magnetic field, right, it's something weirder. 0:17:51.280 --> 0:17:53.960 It's not like a real magnetic field. Exactly like a 0:17:54.040 --> 0:17:58.120 magnetic it's like a magnetic field. And that's that's exactly 0:17:58.119 --> 0:18:00.520 where we what they struggled with. They're like, Okay, this 0:18:00.560 --> 0:18:04.359 has some property. It's something is generating this magnet, and 0:18:04.400 --> 0:18:07.679 it's definitely quantum mechanical in some weird way because we 0:18:07.720 --> 0:18:10.639 have all these weird properties. Like another weird thing about 0:18:10.640 --> 0:18:13.520 this magnetic devices. So you send a bunch of electrons 0:18:13.560 --> 0:18:16.520 through and you split them um left and right. Okay, 0:18:16.840 --> 0:18:19.480 then you take the left beam, only the left beam, 0:18:19.520 --> 0:18:21.880 and you split them through a device that's rotated ninety 0:18:21.920 --> 0:18:24.720 degrees that goes up and down. Then they split up 0:18:24.760 --> 0:18:28.119 and down right, even though beforehand they would only split 0:18:28.200 --> 0:18:30.320 left and right. Wait, what if you take the left beam, 0:18:30.400 --> 0:18:32.480 the one that the ones that went left? What if 0:18:32.480 --> 0:18:36.320 you try to split them up again? Horizontally. Do they 0:18:36.359 --> 0:18:39.639 all go left again, Yes, they do. But if you 0:18:39.680 --> 0:18:42.080 split them left right, and you take the left beam, 0:18:42.160 --> 0:18:44.960 then you split them up down, you take the upbeam, 0:18:45.040 --> 0:18:46.800 and then you try to split it left and right again, 0:18:46.960 --> 0:18:49.879 then they mix they go both left and right. And 0:18:49.960 --> 0:18:54.159 that's why it's quantum mechanical, yeah, because you can't you 0:18:54.240 --> 0:18:57.840 can't measure this weird little quantum magnet that the electron has. 0:18:57.880 --> 0:18:59.919 You can't measure it both in X and in y 0:19:00.080 --> 0:19:03.639 at the same time. It's the old Heisenberg uncertainty principle. 0:19:03.920 --> 0:19:07.159 You can't know too much information about the universe. So 0:19:07.200 --> 0:19:09.639 when you measure it in up, down, it mixes it 0:19:09.720 --> 0:19:13.280 up again and left right. Whoa. It's like, oh, I see, 0:19:13.320 --> 0:19:15.120 you can't measure the up and down and the left 0:19:15.119 --> 0:19:17.240 and right at the same time. It's like them that 0:19:17.320 --> 0:19:19.360 you can't know a particle where it is and where 0:19:19.359 --> 0:19:21.840 it's going at the same time. The same thing applies 0:19:21.920 --> 0:19:24.439 to the magnet exactly. And that's how we knew it 0:19:24.440 --> 0:19:27.919 was a quantum mechanical property. Right, So we discovered this 0:19:28.000 --> 0:19:30.960 weird thing about particles that they have their own little magnets, 0:19:31.240 --> 0:19:33.800 and somehow this magnet is quantum mechanical, and so they 0:19:33.840 --> 0:19:37.600 were like, what could this be? All right, let's get 0:19:37.640 --> 0:19:39.440 into what it could be and some of the weird 0:19:39.480 --> 0:19:55.000 things about that. But first let's take a quick break, okay, Daniel. 0:19:55.080 --> 0:19:59.600 So people were measuring electrons and they found that they 0:19:59.640 --> 0:20:02.280 have sort of like an inherent and inherent magnet inside 0:20:02.280 --> 0:20:05.240 of electrons, and that it's quantum mechanical, meaning that it's 0:20:05.280 --> 0:20:08.080 like really weird and you can't measure up and down 0:20:08.080 --> 0:20:11.080 and left and right. That's right um, and so people 0:20:11.080 --> 0:20:14.640 that's why people decide to call quantum spin. Yeah, even 0:20:14.640 --> 0:20:17.560 though it's not really spinning, they just went for that name. 0:20:17.600 --> 0:20:19.320 That's right. They call it quantum spin. And so let's 0:20:19.320 --> 0:20:21.400 try to figure out what do they mean by quantum spin? 0:20:21.480 --> 0:20:24.199 What why did they call it quantum spin? Alright, Well, 0:20:24.240 --> 0:20:27.120 quantum is pretty straightforward. It's definitely it's a property of particles, 0:20:27.480 --> 0:20:30.440 and it behaves like other quantum things that you can't 0:20:30.640 --> 0:20:33.200 know too much about it at the same time or 0:20:33.280 --> 0:20:36.200 you can't measure the x and the y um direction 0:20:36.240 --> 0:20:38.480 of at the same time. And also it's either up 0:20:38.520 --> 0:20:41.240 or down, right, there's no in between, So it's quantized. 0:20:41.600 --> 0:20:43.639 So the quantum stuff all right, I buy it. Right, 0:20:43.680 --> 0:20:46.040 you should definitely call this quantum something. If you're gonna 0:20:46.040 --> 0:20:48.880 call it quantum spin or quantum banana, you know, that's 0:20:48.880 --> 0:20:52.760 another question. But it should definitely have the quantum label. Okay, Well, 0:20:52.800 --> 0:20:55.080 I feel like maybe they should have called it quantum 0:20:55.240 --> 0:20:57.879 pole or something, you know, like something that references that, 0:20:58.720 --> 0:21:00.919 because really you're trying to you're trying to capture this 0:21:01.160 --> 0:21:05.240 kind of the magnetic the direction of the magnetic field 0:21:05.240 --> 0:21:08.240 of the electron, right, which is kind of like the pole. Yeah, well, 0:21:08.320 --> 0:21:10.360 what they what they did is they thought about what 0:21:10.520 --> 0:21:14.080 generates magnetic polls, right, what generates magnetic fields. And we 0:21:14.160 --> 0:21:16.439 know that a particle moving in a circle, right, like 0:21:16.600 --> 0:21:19.520 orbiting for example, will generate a magnetic field. So then 0:21:19.560 --> 0:21:23.320