WEBVTT - What Is A Superconductor? 0:00:07.440 --> 0:00:10.920 Hey, Daniel, When you think of physics, what images come 0:00:10.960 --> 0:00:13.520 to mind for you? I think of the cosmos, I 0:00:13.560 --> 0:00:17.400 think of planets. I think of the fire inside the sun. 0:00:17.760 --> 0:00:22.599 I think of crazy people with weird hair when you 0:00:22.680 --> 0:00:25.560 look in the mirror. When you think of physics, what's 0:00:25.600 --> 0:00:31.080 the difference? Well, what about a dance party. I wouldn't 0:00:31.080 --> 0:00:33.839 say that's in the top one thousand associations I have. 0:00:34.000 --> 0:00:36.440 Might maybe not even in the top five thousand. Well, 0:00:36.479 --> 0:00:39.839 it turns out that physics and dance actually have a 0:00:39.920 --> 0:00:42.200 lot in common. They have a lot of fun connections. 0:00:42.479 --> 0:00:45.360 Is that right? Yeah, they can help us understand the 0:00:45.400 --> 0:00:48.440 topic of our podcast to day. That's right. Thinking about 0:00:48.440 --> 0:00:50.199 the way people dance and the way they shake their 0:00:50.200 --> 0:00:53.800 booty could actually help you understand the physics, the crazy 0:00:53.880 --> 0:00:59.800 topic of today's podcast. So get out there, shake your 0:01:00.280 --> 0:01:02.800 and get ready to download some physics into your brain. 0:01:03.000 --> 0:01:23.720 Get into the groove. It's time for physics. Hi'm h 0:01:24.120 --> 0:01:27.800 and I'm Daniel. Welcome to our podcast, Dancing with Physicists. 0:01:28.959 --> 0:01:31.880 How far can you get across the universe by just dancing? Now? 0:01:31.880 --> 0:01:34.000 We're just kidding. You were not the victim of clickbait. 0:01:34.080 --> 0:01:37.120 This is the podcast Daniel and Jorge explain the universe, 0:01:37.240 --> 0:01:40.200 in which we take something weird, something fascinating in the 0:01:40.240 --> 0:01:43.920 universe and try to explain it to you, sometimes using 0:01:44.040 --> 0:01:46.319 dance to be on the podcast, we're going to talk 0:01:46.360 --> 0:01:51.920 about a physics phenomenon that is everywhere. It's everywhere, and 0:01:52.000 --> 0:01:56.880 it's helping make some of the greatest scientific experiments in 0:01:56.920 --> 0:02:00.960 the world. That's right. It's really important, it's fascinating, it's weird, 0:02:01.240 --> 0:02:05.040 it's quantum, and yet it's not really very well understood. 0:02:05.280 --> 0:02:09.919 And more most important, it's super that's right. And it conducts. 0:02:10.600 --> 0:02:15.120 Uh what, it's conductive. There you go, that's right. The 0:02:15.160 --> 0:02:24.400 topic of today's podcast is super conductors. What are they? 0:02:24.400 --> 0:02:28.919 Who are they? Who are they? Super? No? Super conductivity 0:02:28.960 --> 0:02:33.040 is fascinating question, something behind a lot of really interesting 0:02:33.040 --> 0:02:36.359 research in the last few decades, and something we thought 0:02:36.480 --> 0:02:39.560 was worth getting into because there's a lot of puzzles there. Yeah. 0:02:40.120 --> 0:02:42.440 I was just thinking, the first time I heard about 0:02:42.440 --> 0:02:45.839 super conductors was in the eighties, right, and let's when 0:02:45.880 --> 0:02:48.720 it sort of became this big buzz about it. That's right. 0:02:48.760 --> 0:02:50.480 They had a lot of big advances in the eighties. 0:02:50.600 --> 0:02:53.200 How old were you in the eighties? Or I was 0:02:54.000 --> 0:02:59.040 old enough apparently to read about science news, but but 0:02:59.160 --> 0:03:01.200 you would always see it tied to the to this 0:03:01.280 --> 0:03:05.440 footage of this little magnet floating on top of something. Yeah, 0:03:05.480 --> 0:03:08.720 that's like a classic application of super conductivity. Yeah. Yeah, so, 0:03:09.000 --> 0:03:11.440 like I think forever, that's what people think of a 0:03:11.480 --> 0:03:13.919 lot of people think of when they think of super conductors, 0:03:13.919 --> 0:03:16.480 like that one image. Yeah, there's that. There's also the 0:03:16.680 --> 0:03:19.399 super conducting super collider that they were going to build 0:03:19.440 --> 0:03:21.799 in Texas in the nineties that was going to cost 0:03:21.840 --> 0:03:25.160 a huge amount of money and that they canceled halfway through. 0:03:25.639 --> 0:03:27.600 And so a lot of people connect those two phrases 0:03:27.600 --> 0:03:31.320 super conducting and super colliding. Oh yeah, no, I didn't 0:03:31.360 --> 0:03:35.800 hear about that one in the eighties. Um, So it 0:03:35.800 --> 0:03:37.480 sort of seems like it's been out there in the 0:03:37.560 --> 0:03:41.560 popular culture for a while, and but we were wondering 0:03:41.720 --> 0:03:43.600 how much people knew about it, and you know, it's 0:03:43.640 --> 0:03:45.720 part of the popular culture and the people maybe have 0:03:45.800 --> 0:03:48.440 heard about it or whatever. It's strangely, it hasn't really 0:03:48.560 --> 0:03:52.600 entered like, um, you know, um comic books or science 0:03:52.640 --> 0:03:56.040 fiction that much. You don't see like super conducting technology 0:03:56.480 --> 0:03:58.480 all over the place in science fiction. I mean, you 0:03:58.480 --> 0:04:04.160 haven't seen that comic called The super Conductor Adventures of 0:04:04.240 --> 0:04:07.760 Crime Fighting super Conductor. That's right, During the day, he's 0:04:07.760 --> 0:04:11.480 just a mild mannered, regular bus conductor, but at night 0:04:13.800 --> 0:04:16.600 he's a super duper conductor. No, I haven't seen that, 0:04:16.640 --> 0:04:18.120 and you don't see it. Um. You know, playing a 0:04:18.120 --> 0:04:21.640 prominent role in science fiction movies like particle physics is 0:04:21.680 --> 0:04:24.279 everywhere in science fiction movies. The Higgs boson explains everything 0:04:24.279 --> 0:04:27.680 and causes problems, etcetera. But you don't see super conductivity 0:04:27.800 --> 0:04:30.680 used and abused much in popular culture. Do you have 0:04:30.760 --> 0:04:33.279 I missed it? Yeah, I don't know. I guess it's 0:04:33.279 --> 0:04:36.680 not flashy, right, it's not um. It's not a word 0:04:36.680 --> 0:04:43.039 that sounds as cool as quantum or leasers or higgs boson. Yeah, exactly. Yeah. Anyway, 0:04:43.040 --> 0:04:45.839 so I went around campus and I asked people, do 0:04:45.880 --> 0:04:48.520 you know what super conductivity is? Can you explain it? 0:04:48.600 --> 0:04:51.320 Do you understand it? Here's what people had to say. 0:04:51.600 --> 0:04:54.479 What about super conductivity? Have you heard of that? Yes? 0:04:54.880 --> 0:05:01.159 Can you explain that? Best? Guess maybe it has two 0:05:01.279 --> 0:05:07.360 conductors and for some stuff. Okay, uh, yeah, I've also 0:05:07.520 --> 0:05:11.400 heard of it, but I also have no idea either. Okay, Um, 0:05:11.440 --> 0:05:16.160 it's a phenomena that happens at very low temperatures because 0:05:16.720 --> 0:05:21.640 electrons have very low resistance to movement due to the 0:05:21.839 --> 0:05:25.960 very slow vibrations of the matrix of the metal of 0:05:26.040 --> 0:05:28.440 the nucleus of the atom, so the electrons have a 0:05:28.440 --> 0:05:31.920 lot more space to move through. Something along those lines. 0:05:33.080 --> 0:05:35.599 Is that the one with the magnets and they could float. 0:05:36.400 --> 0:05:38.800 That's about all I know about that one where no 0:05:39.320 --> 0:05:43.279 I can guess though, Um, my conductivity with like wires, 0:05:43.320 --> 0:05:46.680 for example, or like metal so super conductive, then it's 0:05:46.680 --> 0:05:50.400 a good conductor, doesn't burn out. I would assume that 0:05:50.440 --> 0:05:56.080 it has something to do with objects that are conductive. Alright, Yeah, 0:05:56.080 --> 0:05:58.040 so I like the person who said that it has 0:05:58.080 --> 0:06:02.800 something to do with conductors and force and stuff. That's right. 0:06:03.080 --> 0:06:05.320 And there's somebody out there who clearly is reading the 0:06:05.360 --> 0:06:08.000 same magazine you were, because they're like, oh, it has 0:06:08.040 --> 0:06:11.240 to do with magnets that can float. Yeah, yeah, do 0:06:11.279 --> 0:06:12.800 you know which clip I'm talking about? I feel like 0:06:12.839 --> 0:06:14.919 they used the same clip for years and years and 0:06:14.960 --> 0:06:16.960 years and years and years. Yeah. I totally know what 0:06:17.000 --> 0:06:19.520 you mean. A little black magnet floating over a very 0:06:19.600 --> 0:06:23.480 cool surface. With like liquid hydrogen sublimating off of it. 0:06:23.480 --> 0:06:25.760 It's pretty cool looking. And then somebody comes and pokes 0:06:25.800 --> 0:06:30.360 the magnet and it just keeps floating there. Yeah, exactly exactly. 0:06:30.400 --> 0:06:32.320 So people had some sense, you know, they knew what 0:06:32.360 --> 0:06:34.800 it was. Nobody was like, I've never heard that word before, 0:06:34.839 --> 0:06:38.080 what are you talking about? Right, But nobody could explain 0:06:38.080 --> 0:06:39.960 it to me. Like some people knew you had to 0:06:40.000 --> 0:06:42.760 be cold to be a superconductor, but nobody could give 0:06:42.800 --> 0:06:44.760 me a solid explanation for what it was and how 0:06:44.800 --> 0:06:47.960 it worked. Right. I guess this one has something understandable, 0:06:47.960 --> 0:06:50.840 which is a conductor, and you know, I guess people 0:06:50.960 --> 0:06:54.440 in high school figure out that or learned that it's 0:06:54.480 --> 0:06:58.320 something that conducts electricity, and so a super conductor must 0:06:58.320 --> 0:07:01.760 just be something that is super ad That's right, it's 0:07:01.800 --> 0:07:05.640 awesome at conducting extracity. Right, that should be the next discovery. 0:07:05.720 --> 0:07:10.480 Awesome conductors. That's right. Superconductors last year, this year, awesome 0:07:10.520 --> 0:07:14.840 conductors next year, uber conductors. Um. But there is really 0:07:14.840 --> 0:07:18.080 something special about superconductors, which is not just that they 0:07:18.120 --> 0:07:20.240 can conduct a lot, but that they conduct with no 0:07:20.400 --> 0:07:23.560 resistance at all, where that you can't have anything better 0:07:23.600 --> 0:07:26.600 than a superconductor. So it is pretty amazing, and they 0:07:26.720 --> 0:07:30.360 are really important for things like particle physics, right, Yeah, 0:07:30.440 --> 0:07:33.720 they have a lot of really cool applications. So it's 0:07:33.720 --> 0:07:39.320 like a physics phenomenon that has really great applications for 0:07:39.640 --> 0:07:43.120 important experiments like the Large Hadron collider. That's right, And 0:07:43.160 --> 0:07:45.480 it's also a really fun physics puzzle. You know. The 0:07:45.520 --> 0:07:47.640 kind of physics that I do personally is like take 0:07:47.680 --> 0:07:51.240 everything apart and understand the smallest bits. That's totally worthwhile 0:07:51.280 --> 0:07:54.080 obviously and leads to deep insights. But there's a whole different, 0:07:54.080 --> 0:07:56.760 other kind of way of doing physics that's like can 0:07:56.800 --> 0:07:59.559 we put things together in a weird way that makes 0:07:59.680 --> 0:08:02.840 weird materials? You know, we have lots of materials around 0:08:02.880 --> 0:08:04.880 us on Earth that we're familiar with, but you can 0:08:04.920 --> 0:08:07.400 think like can we rearrange those bits to make new 0:08:07.520 --> 0:08:10.280 kinds of stuff. So there's a whole group of people 0:08:10.280 --> 0:08:13.000 out there in physics departments because basically all their job 0:08:13.080 --> 0:08:15.440 is is to make new kinds of goo, right, Like, 0:08:15.760 --> 0:08:17.720 let's mix this together and add a little bit of 0:08:17.720 --> 0:08:19.160 that and a little bit of this, and maybe if 0:08:19.200 --> 0:08:21.840 we zap it with a laser will get this weird 0:08:21.880 --> 0:08:25.480 crystal with strange behaviors that like nothing anybody's ever seen before. 0:08:26.280 --> 0:08:29.640 Are you talking about solid state physics? Yeah? These days 0:08:29.680 --> 0:08:32.760 I think they call it condensed matter physics. But essentially, yeah, 0:08:32.840 --> 0:08:35.360 it's like, can we build new kinds of stuff? It's 0:08:35.400 --> 0:08:38.560 like the properties of bulk materials, you know, UM, not 0:08:38.640 --> 0:08:41.319 individual particles, but like what happens when you put all 0:08:41.360 --> 0:08:44.040 these different kinds of particles together in a certain lattice 0:08:44.040 --> 0:08:47.320 and a certain in a certain arrangement. Do they behave 0:08:47.360 --> 0:08:49.760 in strange ways? And what can we learn about you know, 0:08:50.040 --> 0:08:53.079 what solids can and cannot do, right, because they do 0:08:53.160 --> 0:08:56.000 different things right, Like, you can make things behave in 0:08:56.040 --> 0:08:58.880 a totally different, a new way just by the way 0:08:58.920 --> 0:09:01.160 you arrange them. Yeah, and you know, the periodic table 0:09:01.280 --> 0:09:03.640 is the first lesson of that. Everything in the periodic 0:09:03.679 --> 0:09:06.079 table is made out of the same bits, right, protons 0:09:06.080 --> 0:09:09.720 and neutrons and electrons, but they're pretty different, right. Uranium 0:09:09.800 --> 0:09:13.000 is pretty different stuff than lithium, for example, And so 0:09:13.080 --> 0:09:16.360 you can get an incredible variety of behaviors just by 0:09:16.400 --> 0:09:19.360 rearranging the same stuff. And so solid state physics, that 0:09:19.360 --> 0:09:22.079 whole field UM is just taking that to in extremes 0:09:22.120 --> 0:09:24.280 like how can we combine these elements and zap them 0:09:24.280 --> 0:09:26.120 and chill them and heat them and do all sorts 0:09:26.120 --> 0:09:29.400 of crazy stuff. It's basically like cooking, right, what kind 0:09:29.400 --> 0:09:31.800 of cakes can you make with the same ingredients right 0:09:32.120 --> 0:09:36.120 that that taste totally different exactly and can float above 0:09:36.160 --> 0:09:40.280 your countertop? Right? Super connecting cakes, that's the next breakthrough. 0:09:40.440 --> 0:09:44.679 This is just renaate that department stuff physics, physics, stuff, 0:09:45.040 --> 0:09:48.320 physics of stuff. Yeah, exactly, the physics of stuff. Hey, 0:09:48.320 --> 0:09:52.480 stuff is pretty interesting. Rights, the whole podcast called stuff. 0:09:52.520 --> 0:09:56.120 You should know how stuff works? Then we should join 0:09:56.200 --> 0:10:07.000 that podcast network. I think there's stuffed pretty full cool. 0:10:07.000 --> 0:10:09.000 So let's get into it all right, um, and let's 0:10:09.000 --> 0:10:12.200 break it down. So let's what's a superconductor. Let's start 0:10:12.200 --> 0:10:15.320 with just the conductor part. Dig in a little bit 0:10:15.320 --> 0:10:17.960 into what it means to be a conductor, right, So, 0:10:18.000 --> 0:10:22.280 a conductor is something where electricity can move through it, right, 0:10:22.880 --> 0:10:25.080 And you have to understand the electricity moving through it 0:10:25.120 --> 0:10:28.360 is not necessarily the same as like electrons flowing through it. 0:10:28.679 --> 0:10:31.360 You put the electricity on one side of a of 0:10:31.360 --> 0:10:33.800 a wire and you get electricity on the other side 0:10:33.840 --> 0:10:35.920 of the wire. It's tempting to think about it like 0:10:35.960 --> 0:10:38.160 a hose, like you put water on one side and 0:10:38.200 --> 0:10:40.640 water comes out the other side. Like a tube. Yeah, 0:10:40.720 --> 0:10:43.200 like a tube. And you know what happens is you 0:10:43.200 --> 0:10:46.040 put electrons in on one side and the electrons all 0:10:46.040 --> 0:10:48.600 sort of shift over like it's it's like a tube 0:10:48.679 --> 0:10:50.960 full of water. You put a little bit of water 0:10:51.000 --> 0:10:52.960 in the front, and a little bit of a different 0:10:52.960 --> 0:10:54.959 piece of water that was already in there pushes out 0:10:54.960 --> 0:10:57.760 the side. It's kind of like um, if you have 0:10:57.800 --> 0:10:59.480 a two and you blow in it. The air that 0:10:59.480 --> 0:11:01.520 comes out the the end is not necessarily the air 0:11:01.600 --> 0:11:04.920 they came out of your mouth. It's like it causes 0:11:04.960 --> 0:11:07.800 some sort of it pushes all the air through and 0:11:07.840 --> 0:11:09.480 the ones that come out are the ones that we're 0:11:09.520 --> 0:11:12.920 waiting closest to the end exactly. And that's only possible 0:11:12.960 --> 0:11:15.480 if the electrons can move. Right. And so a conductor 0:11:15.880 --> 0:11:18.480 is just any material where you have electrons that can 0:11:18.600 --> 0:11:21.520 jump from atom to atom. Right. Think about a material 0:11:21.640 --> 0:11:24.720 and a microscopic scale, it's really a bunch of atoms, right, 0:11:25.080 --> 0:11:27.280 And if it's simple or regular, then it's like a 0:11:27.360 --> 0:11:30.560 lattice like a grid, and it's like regularly distributed atoms, 0:11:30.880 --> 0:11:32.800 and the electrons can jump from one to the other. 0:11:32.840 --> 0:11:35.200 So if you blow on one side, you like pushing 0:11:35.240 --> 0:11:38.080 about some electrons on one side, then all the electrons 0:11:38.080 --> 0:11:40.240 sort of hop over one slot and you get some 0:11:40.360 --> 0:11:43.480 out the other side. It's kind of like, um, like 0:11:43.480 --> 0:11:47.440 playing hot potato. Yeah exactly. And the difference between something 0:11:47.480 --> 0:11:50.360 that can conduct electricity a conductor, and something that can't, 0:11:50.400 --> 0:11:54.360 an insulator, is that conductors have enough electrons that can 0:11:54.600 --> 0:11:58.600 jump between atoms, whereas insulators have all their electrons held 0:11:58.679 --> 0:12:00.720 really tight by each of those atoms in the grid, 0:12:01.040 --> 0:12:03.480 so that there's no way for the electrons to jump 0:12:03.480 --> 0:12:06.920 from one to the other. Conductors have these free electrons 0:12:06.920 --> 0:12:09.880 that are sort of just like floating around happily. Okay, 0:12:09.960 --> 0:12:13.320 So it's something that is not a conductor doesn't have 0:12:13.559 --> 0:12:18.280 kind of a spare electrons, or they don't they don't 0:12:18.360 --> 0:12:22.719 let electrons fly around freely. Yeah exactly. And so and 0:12:22.840 --> 0:12:24.720 you just you know, you put electrons on one side 0:12:24.760 --> 0:12:26.640 and they just go nowhere, right, So you can't get 0:12:26.640 --> 0:12:29.040 electrons through the material. Okay, so wait, wait, why not? 0:12:29.120 --> 0:12:32.520 So I introduce an electron in an insulator and something 0:12:32.559 --> 0:12:34.880 that doesn't conduct what's going to happen to the electron? 0:12:35.000 --> 0:12:36.960 It won't go through, yeah, it just it won't cause 0:12:36.960 --> 0:12:39.480 a current. Right, you can't get a current through there. 0:12:39.520 --> 0:12:42.040 You can't get all the electrons to jump over one 0:12:42.080 --> 0:12:45.520 atom for example. Okay, so it's kind of like, Um, 0:12:45.559 --> 0:12:48.839 a conductor has a bunch of atoms, and everyone kind 0:12:48.840 --> 0:12:52.200 of has everyone's pretty loose with their electrons. That's right. Okay, 0:12:52.240 --> 0:12:54.000 here's one. Oh, I'll take one. R I'll give you 0:12:54.040 --> 0:12:57.520 another one. Oh. Um, electrons can just kind of flow 0:12:57.720 --> 0:13:00.440 through from atom to atom. Yeah, And it's best to 0:13:00.440 --> 0:13:02.360 think of them really as a lattice, because these atoms 0:13:02.400 --> 0:13:04.600 individually act a little different than they do when they're 0:13:04.600 --> 0:13:06.920 together in a material. And when they're together in a material, 0:13:07.200 --> 0:13:10.840 the electrons slash easily back and forth between them. Um, 0:13:10.920 --> 0:13:13.560 for a conductor, for an insulator, that doesn't happen. And 0:13:13.559 --> 0:13:16.160 then of course there's lots of different kinds of conductors 0:13:16.160 --> 0:13:18.079 that things that are good conductors and things that are 0:13:18.080 --> 0:13:21.640 bad conductors. And by a lattice, you mean like a 0:13:21.920 --> 0:13:24.560 like a grid or like a like a rack, Like 0:13:24.640 --> 0:13:28.040 the electrons are arranged kind of like um in rows 0:13:28.080 --> 0:13:30.640 and in columns, right, Yeah, exactly. If you zoom in 0:13:30.679 --> 0:13:32.600 on a crystal, for example, or a piece of metal, 0:13:32.640 --> 0:13:35.800 anything that has a regular arrangement of the atoms, you'll 0:13:35.800 --> 0:13:38.440 see that they're organized in this in this pattern right there, 0:13:38.480 --> 0:13:41.560 built out of these basic units, and that they're pretty regular. 0:13:41.679 --> 0:13:44.480 You know, there's like lines of atoms. Um, it's not 0:13:44.520 --> 0:13:48.520 just like a big heaping mess. Right. Um, These these solids, 0:13:48.559 --> 0:13:52.280 these metals, these things that are conductors are pretty well organized, 0:13:52.640 --> 0:13:55.280 and so you'll see them in rows and and uh. 0:13:55.320 --> 0:13:56.760 And that's what we mean by the lattice. You have 0:13:56.880 --> 0:13:59.600 just like a grid of atoms. And so you're saying 0:13:59.760 --> 0:14:03.760 like us can flow through or jump freely between atoms, 0:14:03.840 --> 0:14:06.559 but not perfectly right, that's right. And here's where the 0:14:06.600 --> 0:14:10.960 temperature comes in. So, Um, the colder the material is. 0:14:11.280 --> 0:14:13.960 Think about what temperature really is. What is temperature? It's 0:14:14.080 --> 0:14:17.480 how much the atoms inside something are wiggling. The atoms 0:14:17.480 --> 0:14:21.280 inside liquid are wiggling more than the atoms inside of solid, right, 0:14:21.280 --> 0:14:23.280 which is why it's liquid, and the atoms inside of 0:14:23.320 --> 0:14:26.520 gas are totally free and bouncing around everywhere. But even 0:14:26.520 --> 0:14:29.440 inside of solid, even if it's solid, you have different temperatures. Right, 0:14:29.560 --> 0:14:31.280 You can have a piece of metal that's hot or 0:14:31.280 --> 0:14:34.000 piece of metal that's cold. What's happening there is that 0:14:34.080 --> 0:14:37.320 the atoms are moving less, right, They're wiggling less, and 0:14:37.360 --> 0:14:39.680 as it gets colder and colder, they wiggle less and 0:14:39.720 --> 0:14:42.080 less and less. And this is important for the electron 0:14:42.120 --> 0:14:44.480 because remember, it's trying to jump from atom to atom. 0:14:44.800 --> 0:14:47.760 That's easier when the atoms are not wiggling around, when 0:14:47.800 --> 0:14:52.280 they're like regularly spaced rows, like when they're frozen in place. Yes, exactly. 0:14:52.520 --> 0:14:55.320 Here's where the dance analogy comes in. Right. Imagine trying 0:14:55.360 --> 0:14:57.760 to walk through a crowd and everybody's like jumping. It's 0:14:57.800 --> 0:14:59.720 like a mosh pit, right, and they're going crazy into 0:14:59.720 --> 0:15:02.480 punk consider or something. It's really hard to get across 0:15:02.480 --> 0:15:05.000 the crowded room if everybody's jostling and bouncing and moving 0:15:05.040 --> 0:15:08.120 around a lot, Right, It's much easier if they're calm, 0:15:08.200 --> 0:15:11.720 if they're like, you know, slow dancing or something. It's 0:15:11.800 --> 0:15:14.080 kind of like, yeah, you would. If it's a marsh 0:15:14.080 --> 0:15:18.040 pit and everyone's moving and dancing, you would just kind 0:15:18.040 --> 0:15:20.320 of lose a lot of energy just kind of bumping 0:15:20.480 --> 0:15:24.200 against people and just trying to make it through. Exactly. 0:15:24.280 --> 0:15:26.320 You would lose a lot of energy. That's exactly right. 0:15:26.520 --> 0:15:30.600 It's the resistance, right. So electrical resistance is electrons losing 0:15:30.760 --> 0:15:33.480 energy as they bump into the atoms that are wriggling 0:15:33.520 --> 0:15:37.040 around because they're moving like. It's related to the kinetic 0:15:37.200 --> 0:15:39.680 motion of the atoms. Yeah, absolutely, it's related to the 0:15:39.720 --> 0:15:42.080 kinetic motion of the atoms. It makes it harder for 0:15:42.120 --> 0:15:44.040 the electrons to get through and as they get through, 0:15:44.080 --> 0:15:48.240 they lose some energy. Right. Okay, so that's resistance, right, 0:15:48.280 --> 0:15:54.000 that's um vehicles. The resistance of a wire or a conductor, 0:15:54.080 --> 0:15:56.960 that's what it is. It's it's like electrons going through 0:15:57.040 --> 0:16:00.080 but sort of bumping too much into the atoms. That's it. 0:16:00.120 --> 0:16:03.000 And so things that are conductors have low resistance, and 0:16:03.160 --> 0:16:05.200 you want to use things that have low resistance so 0:16:05.240 --> 0:16:07.360 that most of the energy you're sending along a wire, 0:16:07.400 --> 0:16:10.160 for example, gets there. And if you use something with 0:16:10.200 --> 0:16:12.640 low resistance like copper or gold, then most of the 0:16:12.760 --> 0:16:14.280 energy you put into a wire will get to the 0:16:14.320 --> 0:16:16.880 other side. If you use something with really bad resistance, 0:16:16.880 --> 0:16:19.320 with a lot of resistance, then it will heat up 0:16:19.360 --> 0:16:22.480 the wire. That energy from the electrons will create resistance, 0:16:22.480 --> 0:16:26.720 which turns into heat and that's not good. But sometimes 0:16:26.800 --> 0:16:29.680 you sort of want resistance, right, Like in circuits, some 0:16:29.840 --> 0:16:32.720 resistors are sometimes good. Yeah, sometimes you want resistance so 0:16:32.760 --> 0:16:34.800 you can put it in on purpose. For example, a 0:16:34.880 --> 0:16:37.320 light bulb, that's a resistor, right. What it does is 0:16:37.320 --> 0:16:39.800 it steals the energy from the electrons and it heats 0:16:39.800 --> 0:16:41.960 of the material, which then glows and gives you light. 0:16:42.240 --> 0:16:44.680 Awesome if that's what you wanted, right, But you don't 0:16:44.680 --> 0:16:49.040 really want them wires in your house glowing. You want 0:16:49.080 --> 0:16:52.000 them to transmit that energy to your iPhone or whatever 0:16:52.000 --> 0:16:54.880 it is you're sending. And those power lines along the road, right, 0:16:54.880 --> 0:16:57.520 we don't want those heating up and melting. Want those 0:16:57.520 --> 0:17:00.240 to transmit the energy from the power station to your 0:17:00.240 --> 0:17:03.560 house without losing much energy. Unless you your house is 0:17:03.560 --> 0:17:08.160 a dance floor, that would be pretty cool, Like, well, 0:17:08.160 --> 0:17:11.840 how are you going to power those speakers without the electrons? Well, 0:17:11.840 --> 0:17:17.080 the speakers will glow too. Sounds like an awesome party, 0:17:17.119 --> 0:17:19.480 Send me an invite. And I think that brings us 0:17:19.520 --> 0:17:21.760 to the cool point, which is that the resistance of 0:17:21.760 --> 0:17:25.200 a conductor depends on the temperature. Yeah, exactly, So as 0:17:25.200 --> 0:17:28.400 it gets colder, the lattice, this grid of atoms gets 0:17:28.400 --> 0:17:30.720 more regular, and it gets easier for the electrons to 0:17:30.760 --> 0:17:33.920 get through, and so the resistance goes down with temperature. 0:17:34.560 --> 0:17:38.080 So hot wire is harder to get electrons through it 0:17:38.760 --> 0:17:41.159 because all the apps are are moving more. But a 0:17:41.160 --> 0:17:45.320 cold wire lets the electrons flow easy, more easy. That's right, 0:17:45.520 --> 0:17:48.360 all right, cool, that's that's a conductor, not somebody who 0:17:48.440 --> 0:17:51.480 drives a bus or directs an orchestra. That person is 0:17:51.520 --> 0:17:55.000 also a conductor. Yeah, but is he a superconductor? Is 0:17:55.040 --> 0:18:02.320 he resistant? Does he glow? Does he steal energy from 0:18:02.320 --> 0:18:05.080 innocent electrons? All right, that's a conductor, And now let's 0:18:05.080 --> 0:18:08.760 get into superconductors. But first let's take a quick break, 0:18:21.640 --> 0:18:24.359 all right, Daniel, So it fills in what is a 0:18:24.480 --> 0:18:28.320 super conductor and what is so super about them? Superconductors 0:18:28.359 --> 0:18:31.040 are really pretty super. The thing that makes them super 0:18:31.200 --> 0:18:35.280 is that they have zero resistance, not just like very small, 0:18:35.520 --> 0:18:39.680 not like Ebsalon resistance, but zero, like zero point zero 0:18:39.760 --> 0:18:42.199 zero zero zero. Keep going with the zeros there, man, 0:18:42.200 --> 0:18:46.520 because it's zero all the way. Okay, Yeah, it's pretty crazy. 0:18:46.560 --> 0:18:48.280 It means that, for example, if you had a loop 0:18:48.560 --> 0:18:50.960 of super connecting wire, you could put a current into 0:18:51.000 --> 0:18:53.359 it and it would just zoom around it forever. It 0:18:53.400 --> 0:18:56.600 would like never get used up. It's a pretty hard 0:18:56.680 --> 0:18:59.080 concept to imagine. It's like, it's like living in a 0:18:59.119 --> 0:19:01.639 world without friction. And you know, it's like imagine you 0:19:01.720 --> 0:19:05.040 had a sheet of ice, you pushed a block on it, right, 0:19:05.440 --> 0:19:06.959 you expect it to go for a while and then 0:19:07.000 --> 0:19:11.040 eventually slow down because every surface has some friction. But 0:19:11.119 --> 0:19:13.720 what if you had a perfectly smooth surface with no 0:19:13.880 --> 0:19:16.760 resistance and you pushed it, it would just go forever. 0:19:17.160 --> 0:19:21.600 It's like a perpetual motion machine. Yeah, sort of like that. 0:19:22.560 --> 0:19:24.200 Or is it kind of like if you if you're 0:19:24.200 --> 0:19:28.120 out in space and you start spinning something a top, 0:19:28.800 --> 0:19:31.160 It's just going to keep spinning for a long time 0:19:31.200 --> 0:19:34.760 because there's nothing there's no air, no resistance, no nothing 0:19:34.800 --> 0:19:38.320 to stop it from spinning. That's right, yeah, exactly. And 0:19:38.400 --> 0:19:41.480 so a superconductor is something that has zero resistance and 0:19:41.560 --> 0:19:43.880 so the electrons can just flow right through it. It's 0:19:43.880 --> 0:19:46.359 pretty amazing, all right. So let's get into how that works. 0:19:46.400 --> 0:19:50.160 And I think what's cool I heard is that physicists 0:19:50.200 --> 0:19:53.240 don't really know what's going on. Yeah, well, there's some 0:19:53.920 --> 0:19:56.199 there are different kinds of superconductors, and some of them 0:19:56.200 --> 0:19:59.440 are pretty well understood, the old fashioned ones, the classic ones. 0:19:59.520 --> 0:20:02.440 But rees they've made a bunch of really strange superconductors 0:20:02.920 --> 0:20:05.679 um that nobody really understands in great detail. I mean, 0:20:05.720 --> 0:20:08.679 we have some simulations we can describe it, but a 0:20:08.720 --> 0:20:11.040 lot of it's just too complicated or like write down 0:20:11.040 --> 0:20:14.880 equations on paper that we can understand. Okay, So there's 0:20:14.880 --> 0:20:18.480 different flavors of superconductors. Yeah, the first thing they all 0:20:18.520 --> 0:20:20.560 have in common is that you've got to get it cold. 0:20:20.640 --> 0:20:22.520 Like we were saying earlier, you want to lower the 0:20:22.600 --> 0:20:25.720 resistance first, get it cold, and so chill that thing down. 0:20:26.119 --> 0:20:28.879 And people built refrigerators to get things down to like 0:20:29.200 --> 0:20:33.440 really really really cold temperatures like ten or twenty degrees kelvin. 0:20:33.840 --> 0:20:36.919 You know, that's like just above absolute zero. And and 0:20:36.960 --> 0:20:41.280 the point is that one gets colder that cold, the 0:20:42.200 --> 0:20:46.719 grid in the material stops moving, it stops vibrating, right, 0:20:46.920 --> 0:20:49.920 that's right. And you can't get anything down to actually 0:20:49.960 --> 0:20:52.520 absolute zero, but you can get it down really really cold, 0:20:52.880 --> 0:20:54.959 and the grid stops vibrating, as you say, and then 0:20:55.000 --> 0:20:57.200 it gets easier and easier for electrons to go through, 0:20:57.560 --> 0:20:59.920 and so that will bring you down to low resistant, 0:21:00.080 --> 0:21:03.720 even very low. Some might even say super low, but 0:21:03.760 --> 0:21:06.760 it won't get you all the way down to zero resistance. Oh, 0:21:07.080 --> 0:21:09.239 I see, if you just had a regular like if 0:21:09.240 --> 0:21:11.439 I took a copper wire and I froze it to 0:21:11.960 --> 0:21:15.480 almost zero kelvin, it would give me pretty low resistance, 0:21:15.520 --> 0:21:18.719 but not necessarily zero resistance. I don't actually know if 0:21:18.760 --> 0:21:21.800 copper can become a superconductor, but I just mean that 0:21:21.920 --> 0:21:25.280 chilling it down is not the all the explanation. To 0:21:25.400 --> 0:21:28.520 explain how something loses its resistance. You need more than 0:21:28.600 --> 0:21:31.800 just understanding that it gets colder and therefore it's easier 0:21:31.800 --> 0:21:34.280 for the electrons to go through. You need there's another 0:21:34.359 --> 0:21:37.760 piece of the explanation. There's some extra magic going on there, 0:21:38.160 --> 0:21:41.000 some extra dance magic. Yeah, exactly, because physics, if you 0:21:41.080 --> 0:21:44.200 just think about the temperature physics as you shouldn't have superconductors, 0:21:44.680 --> 0:21:46.800 but we do have them. It was in the early 0:21:46.840 --> 0:21:49.600 part of the twentieth century that people made superconductors and 0:21:49.640 --> 0:21:52.520 observed it, and people thought, what, how is this even possible? 0:21:53.160 --> 0:21:56.280