WEBVTT - How Magnetic Storage Works 0:00:04.160 --> 0:00:07.200 Get in touch with technology with tech Stuff from how 0:00:07.240 --> 0:00:14.200 stuff works dot com. Hey there, and welcome to tech Stuff. 0:00:14.240 --> 0:00:18.080 I'm your host, Jonathan Strickland, senior writer for how stuff 0:00:18.120 --> 0:00:20.920 Works dot com, and today I thought it might be interesting. 0:00:21.239 --> 0:00:26.080 So perhaps I'm mistaken to talk about data storage, specifically 0:00:26.120 --> 0:00:28.880 magnetic storage. So there are a lot of different ways 0:00:28.920 --> 0:00:31.880 to store data, you know, like there's always writing it down, 0:00:32.440 --> 0:00:34.440 that's the type of data storage all the way up 0:00:34.479 --> 0:00:38.720 to like holographic memory storage. And magnetic storage has played 0:00:38.720 --> 0:00:41.440 a really important role in the history of technology in 0:00:41.479 --> 0:00:44.519 general and computers in particular. So I want to focus 0:00:44.600 --> 0:00:47.839 on how magnetic storage works. Who came up with that 0:00:47.960 --> 0:00:51.800 idea and even dive into the science of magnets. Yes, 0:00:52.400 --> 0:00:56.520 insane clown posse, I'm looking at you. We're gonna discover 0:00:56.560 --> 0:01:00.440 how magnets work. So if you've been wondering since that 0:01:00.560 --> 0:01:03.800 video I got, I got your hook up. So first, 0:01:03.880 --> 0:01:06.840 let's talk about why magnetic storage was a necessity in 0:01:06.880 --> 0:01:11.200 the first place. So how do you preserve information so 0:01:11.240 --> 0:01:14.160 that you can access it again later? Because in the 0:01:14.200 --> 0:01:16.840 old days, and I'm talking like tens of thousands of 0:01:16.920 --> 0:01:19.760 years ago, verbal communication was where it was at you 0:01:19.880 --> 0:01:23.280 stored all that information up in your head. Someone would 0:01:23.280 --> 0:01:25.400 tell you something important and you had to remember it. 0:01:25.920 --> 0:01:28.680 Perhaps they would tell you within the context of a story. 0:01:29.400 --> 0:01:33.119 And then eventually, if you were trying to preserve information, 0:01:33.200 --> 0:01:35.960 you would tell that same information to someone else and 0:01:36.040 --> 0:01:39.760 pass it along. This way, this is essentially folklore. That's 0:01:39.800 --> 0:01:45.280 how knowledge was maintained for centuries. And then way back 0:01:45.280 --> 0:01:48.040 in the day, someone said, hey, what if we made 0:01:48.080 --> 0:01:51.560 up some symbols to represent these sounds we're making to 0:01:51.600 --> 0:01:54.200 communicate with each other, and then we put those symbols 0:01:54.200 --> 0:01:58.920 into some sort of fixed format, like in a clay tablet, 0:01:59.800 --> 0:02:02.840 And that way we can preserve the information a lot longer. 0:02:03.240 --> 0:02:07.600 And if Bob, who's really good at making fires, can 0:02:07.680 --> 0:02:10.800 explain how to make fires, and we we put it 0:02:10.840 --> 0:02:13.480 down in this format, we'll be able to make fires 0:02:13.639 --> 0:02:17.080 even if Bob does something stupid like walks off the 0:02:17.160 --> 0:02:21.000 edge of a cliff or something. And writing was born. 0:02:21.760 --> 0:02:23.760 It probably went a little differently from the way I 0:02:23.800 --> 0:02:25.560 explained it, but I think I got the gist of it. 0:02:26.040 --> 0:02:29.720 Not everyone, however, was a fan of this development. Believe 0:02:29.760 --> 0:02:32.600 it or not. There were people who were against the 0:02:32.680 --> 0:02:37.200 whole idea of writing stuff down. Socrates was actually a 0:02:37.240 --> 0:02:40.200 critic of writing stuff down, or at least that's what 0:02:40.280 --> 0:02:45.600 we hear, because Socrates didn't write anything down, his students did. Uh. 0:02:45.600 --> 0:02:48.600 He said that the written word is fixed, and therefore 0:02:48.639 --> 0:02:52.200 it can't defend itself or any arguments it makes, so 0:02:52.240 --> 0:02:56.760 it's inherently flawed. If someone writes down an argument and 0:02:56.880 --> 0:02:59.960 your access to the argument is in that written format, 0:03:00.360 --> 0:03:04.399 and you have questions or you have attacks on that argument, 0:03:04.919 --> 0:03:07.919 it can't defend itself. The person who wrote it could 0:03:08.040 --> 0:03:10.840 if they were there, but if they're not there, then 0:03:10.880 --> 0:03:13.400 the argument has to stand on its own, and therefore 0:03:13.600 --> 0:03:19.120 it has to be less effective. Let's say that an 0:03:19.120 --> 0:03:21.320 actual human being. He also said that if you write 0:03:21.320 --> 0:03:23.920 stuff down, you don't have to remember it yourself, and 0:03:23.960 --> 0:03:27.639 that makes you less intelligent, because if you're not actually 0:03:27.680 --> 0:03:32.639 committing something to memory, you're getting super dumb. Uh. This 0:03:33.520 --> 0:03:35.600 might sound a lot like some of the arguments people 0:03:35.600 --> 0:03:40.040 have made about Google and the Internet, and it's absolutely correct. 0:03:40.160 --> 0:03:43.440 Every single time we have created a new way to 0:03:43.800 --> 0:03:48.000 permanently store data in some form or another, people have 0:03:49.200 --> 0:03:51.880 brought up this idea that it's making us more dumb, 0:03:53.040 --> 0:03:55.280 Like they might say, hey, Back in the day, you'd 0:03:55.280 --> 0:03:57.480 have to remember all your phone numbers, like all the 0:03:57.560 --> 0:03:59.680 numbers of the friends and family that you would be 0:03:59.680 --> 0:04:01.840 calling a regular basis. But now it's all on your phone, 0:04:01.840 --> 0:04:04.200 so you don't remember it. You may not be able 0:04:04.240 --> 0:04:07.120 to rattle off more than two or three phone numbers 0:04:07.160 --> 0:04:10.080 today because of that, therefore you are more dumb. I 0:04:10.120 --> 0:04:12.880 don't subscribe to that particular argument. I think having the 0:04:12.960 --> 0:04:17.200 accessibility of information outweighs the fact that we are no 0:04:17.240 --> 0:04:20.839 longer able to remember it necessarily. Uh. The point I 0:04:20.839 --> 0:04:24.000 would make is that comprehension is always more important than 0:04:25.000 --> 0:04:27.600 being able to recall something. You might be able to 0:04:27.640 --> 0:04:30.280 recall some information, but if you don't truly comprehend it, 0:04:30.279 --> 0:04:33.400 it's no It's of no use to you. So I 0:04:33.440 --> 0:04:36.760 don't think it's necessarily a measure of intelligence. It's certainly, 0:04:37.000 --> 0:04:39.719 perhaps more of a statement about our memories than anything else. 0:04:40.520 --> 0:04:44.120 But I'm getting off on a tangent here. So I 0:04:44.160 --> 0:04:48.000 think the developments we've had have been phenomenal. We wouldn't 0:04:48.000 --> 0:04:50.720 be where we are today if we were still depending 0:04:50.760 --> 0:04:54.400 upon just telling each other the important stuff and hoping 0:04:54.440 --> 0:04:57.520 that they would be able to then tell other people 0:04:57.920 --> 0:05:00.360 the important stuff we just told them and in way 0:05:00.400 --> 0:05:05.039 that was accurate and effective. We clearly wouldn't be where 0:05:05.040 --> 0:05:07.560 we are today if we still depended upon that. And 0:05:07.600 --> 0:05:09.640 I don't have to travel all the way across the 0:05:09.680 --> 0:05:12.240 world to find a specific guru to learn how to 0:05:12.279 --> 0:05:15.680 perform a particular skill. I can just go onto YouTube 0:05:16.080 --> 0:05:18.839 and watch like thirty or forty videos until I find 0:05:18.839 --> 0:05:25.240 one that actually makes sense. So that's progress. Take that, Socrates. Now, 0:05:25.240 --> 0:05:27.560 throughout history, we saw many advances in the way we 0:05:27.600 --> 0:05:31.640 store information, and as we developed more advanced technology, it 0:05:31.720 --> 0:05:34.800 became clear that a compatible method of storing data would 0:05:34.839 --> 0:05:38.480 be really handy. So imagine what computers would be if 0:05:38.520 --> 0:05:41.640 they could not save information, they'd be practically useless. You 0:05:41.720 --> 0:05:44.920 need to have a way of storing data somehow, whether 0:05:44.960 --> 0:05:48.599 it's in magnetic storage, optical, solid state punch cards, whatever. 0:05:48.680 --> 0:05:53.479 You need something that can record the information otherwise it's 0:05:53.520 --> 0:05:56.240 only good for a moment. And a lot of folks 0:05:56.240 --> 0:05:58.960 worked on this problem, and as is the case with 0:05:59.080 --> 0:06:02.400 many technological developments, some of that work had nothing to 0:06:02.440 --> 0:06:06.240 do with computers, but more with researching fundamental scientific questions 0:06:06.720 --> 0:06:10.599 and finding answers to questions lead other people being able 0:06:10.640 --> 0:06:13.880 to use that information in practical ways that we didn't anticipate. 0:06:14.520 --> 0:06:17.120 And this is kind of another soapbox I like to 0:06:17.160 --> 0:06:19.680 get up on, uh to argue for the importance of 0:06:19.720 --> 0:06:24.160 exploratory science. Applied science is really interesting. Applied sciences when 0:06:24.200 --> 0:06:27.159 you're trying to find a particular solution that will work 0:06:27.600 --> 0:06:30.320 for some sort of problem. Right your you might be 0:06:30.400 --> 0:06:34.200 researching whether or not a specific material would be great 0:06:34.640 --> 0:06:39.960 to use for a particular purpose, like bulletproof material something 0:06:40.000 --> 0:06:43.839 like that. But exploratory science, when you're not necessarily looking 0:06:43.880 --> 0:06:48.400 for applications, is also important because we expand our knowledge 0:06:48.440 --> 0:06:51.920 about how the universe works, and it can open up 0:06:51.920 --> 0:06:55.000 opportunities to leverage that knowledge in ways we could not 0:06:55.160 --> 0:06:58.440 have anticipated when we first started looking into the issue 0:06:58.440 --> 0:07:02.240 in the first place. It's in and stuff, So I 0:07:02.440 --> 0:07:05.720 argue that exploratory science needs to continue to be supported. 0:07:05.880 --> 0:07:09.360 Let's uh now acknowledge all this, take a deep breath, 0:07:09.400 --> 0:07:14.240 and get ready to jump into the strange world of magnetism. So, first, magnetism, 0:07:14.520 --> 0:07:20.000 or more specifically, electro magnetism, is one of four fundamental 0:07:20.080 --> 0:07:25.320 forces that govern the atomic behavior in our universe. So 0:07:25.360 --> 0:07:28.080 the other three if you're keeping track, are the strong 0:07:28.160 --> 0:07:32.200 nuclear force, the weak nuclear force, and gravity, And if 0:07:32.200 --> 0:07:35.920 you want to rank those from the weakest to the strongest, 0:07:36.320 --> 0:07:41.000 you'd start with gravity. Gravity is negligible at the atomic scale. 0:07:41.040 --> 0:07:44.480 It's there, but it's so faint as to be almost absent. 0:07:45.160 --> 0:07:48.360 And this is largely because gravity is dependent upon mass, 0:07:48.760 --> 0:07:51.680 So at the atomic scale, mass masses are so small 0:07:51.960 --> 0:07:56.360 there's barely any gravitational attraction between particles. But gravity is 0:07:56.400 --> 0:07:59.600 kind of nifty because while it's weak, it is there. 0:08:00.160 --> 0:08:03.240 And in fact, there's a gravitational pull on every bit 0:08:03.280 --> 0:08:07.080 of matter from every other bit of matter in our universe. 0:08:07.840 --> 0:08:10.880 So you, that is you listening to me right now, 0:08:11.280 --> 0:08:14.600 you are are exerting a gravitational pull on the Sun, 0:08:15.440 --> 0:08:20.320 and on Alpha Centauri, and on the Andromeda galaxy. You 0:08:20.360 --> 0:08:23.840 are exerting a gravitational pull on everything else that is 0:08:23.960 --> 0:08:29.280 matter in our universe. It's just that that gravitational pull 0:08:29.400 --> 0:08:32.240 is so weak as to be practically nothing, but it 0:08:32.440 --> 0:08:36.520 is there. So since gravity is something we ourselves can 0:08:36.559 --> 0:08:41.000 and do experience in our daily lives, we categorize it 0:08:41.320 --> 0:08:47.480 as one of the familiar forces. Now, next in the 0:08:47.600 --> 0:08:51.480 rank from weakest to strongest, is the weak force. Now 0:08:51.520 --> 0:08:55.720 that's responsible for nuclear beta decay and some other decay processes. 0:08:55.760 --> 0:08:58.440 And this one's pretty difficult to explain. And since I'm 0:08:58.480 --> 0:09:01.160 are you going to have to explain magnetism, I'm gonna 0:09:01.400 --> 0:09:04.320 call for a pass on this one. Let's mulligan it. 0:09:05.120 --> 0:09:08.319 But this is a force that we do not experience 0:09:08.360 --> 0:09:10.960 firsthand in our daily lives, So this one actually falls 0:09:11.000 --> 0:09:16.000 into the category of unfamiliar forces. Now next in strength, 0:09:16.280 --> 0:09:21.680 so second strongest if you prefer, is the electromagnetic force, 0:09:21.760 --> 0:09:24.839 the one will be focusing on today. Now, this is 0:09:24.880 --> 0:09:27.640 a force that exists between all particles that have an 0:09:27.679 --> 0:09:31.360 electric charge. So electrons, for example, will bind to a 0:09:31.480 --> 0:09:35.680 nucleus because electrons have a negative charge, and a nucleus, 0:09:35.720 --> 0:09:40.280 which only contains positively charged protons and neutral neutrons, is 0:09:40.360 --> 0:09:45.360 net positive. And you know that opposites attract, so we 0:09:45.520 --> 0:09:50.480 have the negative electrons attracted to the positive nucleus. We 0:09:50.679 --> 0:09:54.480 can and do experience electromagnetic forces on a daily basis, 0:09:54.480 --> 0:09:58.200 so this one is one of the familiar forces. And 0:09:58.440 --> 0:10:00.680 then we have the strongest of them all, all the 0:10:00.840 --> 0:10:04.640 strong nuclear force. This is the force that holds a 0:10:04.760 --> 0:10:09.280 nucleus together it's a dominant force in various chemical reactions, 0:10:09.280 --> 0:10:12.439 and it has to be strong because it's doing something 0:10:12.480 --> 0:10:18.199 that's really difficult to do. It's holding together similarly charged particles. Remember, 0:10:18.240 --> 0:10:21.800 a nucleus is a bunch of protons and neutrons. The 0:10:21.840 --> 0:10:25.160 protons all have a positive charge. They don't want to 0:10:25.240 --> 0:10:28.560 be and when I say want, I don't actually mean 0:10:28.640 --> 0:10:32.160 they have motivations, but they don't want to be next 0:10:32.160 --> 0:10:36.280 to each other. Those parts, those similar charges are repelling 0:10:36.320 --> 0:10:39.400 one another. So the strong nuclear force has to be 0:10:39.480 --> 0:10:43.079 stronger than the electromagnetic force in order to hold protons 0:10:43.160 --> 0:10:48.760 together in a nucleus with a bunch of neutral charge particles. Ah, 0:10:48.920 --> 0:10:52.959 it does have a very short range, however, so while 0:10:53.000 --> 0:10:56.280 it's stronger than the electromagnetic force, it does, the range 0:10:56.320 --> 0:10:59.640 does not reach very far outside of a nucleus, so 0:10:59.720 --> 0:11:02.480 we do directly observe it in our daily lives, and 0:11:02.559 --> 0:11:06.120 therefore it is an unfamiliar force. So gravity and electro 0:11:06.160 --> 0:11:10.040 magnetism are familiar forces. The strong and weak nuclear forces 0:11:10.080 --> 0:11:16.240 are unfamiliar forces. Uh So what makes electro magnetism tick 0:11:16.400 --> 0:11:19.040 and how did we even figure out how to make 0:11:19.080 --> 0:11:22.599 good use of it? Well, let's start by imagining a 0:11:22.720 --> 0:11:24.679 bar magnet. A lot of this is going to go 0:11:24.720 --> 0:11:27.840 back to stuff that you probably learned in elementary school, 0:11:27.840 --> 0:11:30.880 middle school, high school, those physics courses, that kind of stuff, 0:11:30.920 --> 0:11:34.720 basic science. So you've got your bar magnet. Uh, let's 0:11:34.760 --> 0:11:37.480 just say it's a rectang. It's rectangular in shape. So 0:11:37.720 --> 0:11:40.960 you know you've you've got uh, your north pole and 0:11:41.000 --> 0:11:45.000 your south pole on the magnet. Um this these represent 0:11:45.400 --> 0:11:50.360 the various charges, magnetic charges of the magnet, opposites tracked. 0:11:50.960 --> 0:11:54.000 So if we were to bring this bar magnet close 0:11:54.040 --> 0:11:57.320 to another bar magnet, the north end of our bar 0:11:57.440 --> 0:12:00.600 magnet would start to exert a poll on the south 0:12:00.720 --> 0:12:03.920 end of the other bar magnet. Or if we were 0:12:03.960 --> 0:12:06.760 to try and bring the north pole of our magnet 0:12:06.800 --> 0:12:09.199 close to the north pole of the second magnet, it 0:12:09.240 --> 0:12:12.600 would push against each other, just like I was mentioning 0:12:12.600 --> 0:12:15.920 a second ago. Now, magnets produce a field around them 0:12:16.040 --> 0:12:20.560 that we can represent as lines of force, and those 0:12:20.600 --> 0:12:24.640 lines exit from the north pole, loop around the magnet 0:12:24.960 --> 0:12:28.440 and enter the south pole. A permanent magnet is always 0:12:28.480 --> 0:12:32.720 producing the sort of magnetic field. It's it's consistent, it 0:12:32.800 --> 0:12:37.559 doesn't waiver. Um. You may hear about things like electromagnetism. 0:12:37.640 --> 0:12:39.240 I'll talk a little bit more about in a in 0:12:39.240 --> 0:12:42.680 a bit, where you have to move a coil through 0:12:42.679 --> 0:12:46.000 a varying magnetic field, will a permanent magnet creates a 0:12:46.040 --> 0:12:50.640 consistent magnetic field unless you start doing things like moving 0:12:50.640 --> 0:12:52.920 it around, in which case you're really just moving where 0:12:52.920 --> 0:12:57.840 the magnetic field is. You're not actually fluctuating the field itself. Now, 0:12:58.520 --> 0:13:04.360 inside a magnet a permanent magnet are microscopic regions called 0:13:04.559 --> 0:13:09.800 magnetic domains, and each of these domains is essentially a 0:13:09.840 --> 0:13:13.880 tiny magnet with its own north and south pole. Only 0:13:13.920 --> 0:13:18.000 by aligning the poles of all of these uh magnetic 0:13:18.040 --> 0:13:21.640 domains in a similar direction, like north south, will you 0:13:21.640 --> 0:13:25.640 get a permanent magnet. So if you could just zoom 0:13:25.720 --> 0:13:28.040 in on a permanent magnet, you would see all these 0:13:28.080 --> 0:13:32.160 tiny regions that are essentially magnets that are all aligned 0:13:32.360 --> 0:13:36.920 the same way north south. If you didn't do that, 0:13:37.480 --> 0:13:40.400 if the alignment was mixed up so that you had, 0:13:40.760 --> 0:13:44.120 you know, an equal mixture of north south and south north, 0:13:44.720 --> 0:13:46.880 they would cancel each other out and you wouldn't have 0:13:46.920 --> 0:13:52.320 a magnet. It would just be inert magnetically speaking. So, uh, 0:13:52.360 --> 0:13:55.080 that is something that's interesting because you can actually do 0:13:55.200 --> 0:13:58.040 that to magnets in a couple of different ways. I'll 0:13:58.040 --> 0:14:02.400 talk about that in a second. So all of that 0:14:02.679 --> 0:14:08.680 is changeable. Bomb bom bomb. I wrote that in my notes. 0:14:08.840 --> 0:14:11.760 Actually I had to say it. I could show Dylan, 0:14:11.800 --> 0:14:14.559 but he's working on something else. By the way, when 0:14:14.600 --> 0:14:18.320 all those magnetic domains are aligned north south, what happens 0:14:18.320 --> 0:14:20.360 if you were to cut the magnet in half right 0:14:20.400 --> 0:14:23.320 between the north and south pole. So imagine you've got 0:14:23.320 --> 0:14:26.040 this rectangular bar magnet. You've got you've labeled one in 0:14:26.120 --> 0:14:28.320 the north pole, the other in the south pole. You 0:14:28.400 --> 0:14:33.160 cut the magnet in half horizontally across, well, you would 0:14:33.240 --> 0:14:37.240 end up with two magnets. The middle of that magnet 0:14:37.280 --> 0:14:40.040 would become the south pole for the north end and 0:14:40.080 --> 0:14:42.520 the north pole for the south end. That's because those 0:14:42.560 --> 0:14:46.320 magnetic domains I was talking about, those tiny regions inside 0:14:46.320 --> 0:14:50.080 the magnet themselves itself, those are all aligned north south. 0:14:50.200 --> 0:14:52.560 So if you cut the magnet across, you still have 0:14:52.640 --> 0:14:56.880 those magnetic domains lined up north south, so the overall 0:14:57.000 --> 0:14:59.960 magnetism is preserved. You get two magnets for the price 0:15:00.040 --> 0:15:03.840 of one, but don't cut into magnets magnets, they tend 0:15:03.920 --> 0:15:06.200 to be at least the ones that we typically use 0:15:06.400 --> 0:15:08.920 for things like our fridges and stuff are ceramic magnets, 0:15:08.920 --> 0:15:10.600 and they don't cut so well unless you have like 0:15:10.640 --> 0:15:14.880 a a diamond saw, which some of you probably do. 0:15:15.720 --> 0:15:19.280 And and if you cut magnets normally, then disregard my warning. 0:15:19.280 --> 0:15:21.480 I'm talking about people who don't typically do that sort 0:15:21.520 --> 0:15:23.160 of thing. If you are going to do it, where 0:15:23.160 --> 0:15:28.960 eye protection because that stuff can shatter anyway. Uh, if 0:15:29.000 --> 0:15:32.680 you do that with the magnet. Essentially, each magnet has 0:15:32.760 --> 0:15:36.520 approximately half the magnetic domains of the old magnets, so 0:15:37.120 --> 0:15:39.840 they're not particularly you know, the the individual magnets aren't 0:15:39.880 --> 0:15:42.240 as strong as they were when they were a single magnet. 0:15:42.640 --> 0:15:47.080 Because you're you're magnets, You're overall magnet strength is dependent 0:15:47.160 --> 0:15:51.000 upon the accumulative effect of the magnetic domains within it, 0:15:51.520 --> 0:15:56.520 all right, So each of those magnet domains are tiny magnets. 0:15:57.680 --> 0:15:59.840 There are three ways to get them to line up 0:16:00.240 --> 0:16:03.960 so that the overall material becomes a magnet itself. Like 0:16:04.000 --> 0:16:06.240 how you get them all to line up like north south? 0:16:06.720 --> 0:16:09.480 So way number one is to whack on it with 0:16:09.520 --> 0:16:12.560 something heavy, which isn't a joke. If you hold the 0:16:12.560 --> 0:16:14.960 material in the north south direction and strike it with 0:16:15.000 --> 0:16:19.040 a hammer, you physically realign the magnetic domains and you 0:16:19.120 --> 0:16:23.960 can knock the material into a weak magnet. There's a 0:16:23.960 --> 0:16:26.080 bit more to it than that, but that's the basic idea, 0:16:26.160 --> 0:16:27.920 and that that does mean that you're not going to 0:16:27.960 --> 0:16:30.120 get a very strong magnet as a result, but you 0:16:30.200 --> 0:16:35.400 can physically force those magnetic domains to be in the 0:16:35.480 --> 0:16:39.920 same direction and create a magnet that way. Way number 0:16:39.920 --> 0:16:43.240 two is that you can place the material inside a 0:16:43.280 --> 0:16:46.000 strong magnetic field and make sure the material is in 0:16:46.080 --> 0:16:49.040 the north south alignment and you just leave it there 0:16:49.720 --> 0:16:52.520 and if it's a strong magnetic field, it will start 0:16:52.560 --> 0:16:57.640 to realign the magnetic domains within your target material so 0:16:57.680 --> 0:17:02.000 that they gradually line up with the magnetic fields direction. 0:17:02.640 --> 0:17:04.120 So you just have to have a strong enough one 0:17:04.160 --> 0:17:06.840 to affect the magnetic domains in your target material and 0:17:06.840 --> 0:17:10.080 then eventually you end up with a magnet. So that's 0:17:10.160 --> 0:17:13.000 kind of cool. And way number three is yes, zap 0:17:13.080 --> 0:17:17.560 it with electric current. So one hypothesis is that this 0:17:17.640 --> 0:17:21.280 is how loadstone, which is a naturally magnetic material you 0:17:21.280 --> 0:17:24.960 can find here on Earth, was originally formed the ideas 0:17:25.000 --> 0:17:29.840 that loadstone, which is made up of this stuff called magnetite. Uh, 0:17:29.880 --> 0:17:33.000 some of it was struck by lightning over the the 0:17:33.000 --> 0:17:37.320 the millennia that Earth was forming. So you have magnetite 0:17:37.440 --> 0:17:40.399 on the surface of the planet. Occasionally lightning strikes and 0:17:40.480 --> 0:17:44.280 hits some of this magnetite and then magnetizes it. That 0:17:44.400 --> 0:17:48.480 was That's one hypothesis. But there's another one which suggests 0:17:48.560 --> 0:17:51.520 that magnetite gained its magnetic properties during the time when 0:17:51.560 --> 0:17:53.720 Earth was forming, and it was through more of a 0:17:53.840 --> 0:17:57.879 just a physical uh, the physical process of cooling where 0:17:57.920 --> 0:18:01.720 these magnetic domains aligned in the proper way. Here's the thing, 0:18:01.960 --> 0:18:05.439 we don't really know how it all got started. We 0:18:05.480 --> 0:18:07.840 don't have that information. No one was around back then 0:18:07.920 --> 0:18:10.800 to write it down or put it in magnetic storage. 0:18:11.040 --> 0:18:13.600 So it's still a bit of a mystery. But we 0:18:13.680 --> 0:18:16.399 do know that those are two possible ways that this 0:18:16.440 --> 0:18:20.479 could have come about. And uh, you can also render 0:18:20.600 --> 0:18:25.119 magnets inert by changing the alignment of the magnetic domains 0:18:25.160 --> 0:18:28.080 within it. If you heat a magnet up beyond its 0:18:28.160 --> 0:18:32.560 cury point, which is different for different magnetic materials, it 0:18:32.680 --> 0:18:36.400 loses its magnetism. The heat warps the material and makes 0:18:36.440 --> 0:18:40.120 the magnetic domains fall out of alignment. So what used 0:18:40.119 --> 0:18:42.960 to be magnetic will no longer be. So something that 0:18:42.960 --> 0:18:45.639 would stick to your fridge no problem, will just slide 0:18:45.680 --> 0:18:48.959 off and hit the floor, and everyone will be sad, 0:18:49.560 --> 0:18:51.879 unless you just did it as a scientific experiment, in 0:18:51.880 --> 0:18:53.359 which case you might be happy that you've got the 0:18:53.400 --> 0:18:59.320 result you expected. Now we can experience magnetism because of electrons. 0:18:59.520 --> 0:19:03.280 This time, negatively charged sub atomic particles hold the key 0:19:03.440 --> 0:19:06.760 to whether a material is affected by magnets or isn't. 0:19:07.440 --> 0:19:09.960 You know, might wonder like, why are some things magnetic 0:19:10.040 --> 0:19:12.359 and some things aren't? Why do magnets stick to some 0:19:12.440 --> 0:19:15.879 materials but slide right off of other materials? And ultimately 0:19:16.320 --> 0:19:23.360 the answer falls with electrons. Now, electrons orbit the nucleus 0:19:24.160 --> 0:19:27.520 right in the atoms. You remember your basic description of 0:19:27.520 --> 0:19:29.480 an atom, where you have a nucleus at the center 0:19:29.560 --> 0:19:34.679 and electrons orbiting at different orbital shells around the electrons. Typically, 0:19:35.280 --> 0:19:39.080 electrons will pair up with other electrons. You'll get pairs 0:19:39.160 --> 0:19:43.280 of electrons. They have a state that's called spin, and 0:19:43.400 --> 0:19:46.080 each electron in a pair has the opposite spin of 0:19:46.119 --> 0:19:49.480 its partner. So we can describe spin as up or down. 0:19:49.640 --> 0:19:52.880 For example, if one electron is spinning up, the other 0:19:52.920 --> 0:19:56.679 one by necessity has to be spinning down. You cannot 0:19:56.720 --> 0:19:59.639 get both electrons in a pair to spin in the 0:19:59.720 --> 0:20:03.160 same direction in the same orbital That just that ain't cricket. 0:20:03.680 --> 0:20:06.199 It's part of the quantum mechanical principle we call the 0:20:06.320 --> 0:20:10.119 poly exclusion principle. And until I did a research for 0:20:10.160 --> 0:20:12.040 this show, I could have sworn that referred to the 0:20:12.040 --> 0:20:15.480 practice of non inviting Polly shortier parties. So I guess 0:20:15.520 --> 0:20:18.200 you've learned something new every day. That got a smirk 0:20:18.640 --> 0:20:22.639 from Dylan. It's maybe he'll laugh when he listens to 0:20:22.680 --> 0:20:26.320 it the second time. Uh. Some elements have an unpaired 0:20:26.359 --> 0:20:29.040 electron in an orbital just because that's just how it 0:20:29.080 --> 0:20:34.320 works out. So those unpaired spinning electrons generate a very 0:20:34.359 --> 0:20:39.080 tiny magnetic field, and we call it an orbital magnetic moment, 0:20:39.160 --> 0:20:41.800 which sounds like something you'd expect in a romantic science 0:20:41.800 --> 0:20:47.720 fiction film. Iron, for example, has four unpaired electrons that 0:20:47.880 --> 0:20:52.119 all have the same spin. Those four unpaired electrons have 0:20:52.200 --> 0:20:56.560 an orbital magnetic moment. So magnetic moment has a magnitude 0:20:56.720 --> 0:21:00.280 and the direction, which means it is a vector. The 0:21:00.280 --> 0:21:03.040 bottom line is this vector refers to the strength of 0:21:03.080 --> 0:21:06.760 the magnetic field and the torque it can exert. So 0:21:06.840 --> 0:21:10.199 a permanent magnets magnetic moments are composed of all the 0:21:10.240 --> 0:21:14.040 moments of its atoms. In other words, you've got all 0:21:14.080 --> 0:21:18.199 these atoms that represent an orbital magnetic moment because of 0:21:18.240 --> 0:21:21.439 the spin of the electrons of the unpaired electrons. If 0:21:21.440 --> 0:21:23.800 you've got enough of them and they're aligned the right way, 0:21:23.880 --> 0:21:29.000 that determines the permanent magnets magnetic moments. So iron and 0:21:29.040 --> 0:21:33.280 several other magnetic elements have a crystalline structure, right, so 0:21:33.560 --> 0:21:37.120 think of it like scaffolding. It makes this very ordered 0:21:37.200 --> 0:21:40.680 kind of structure as opposed to something that looks much 0:21:40.680 --> 0:21:44.639 more chaotic. So as iron cools from a molten state, 0:21:45.040 --> 0:21:49.159 atoms line up into this crystalline arrangement, and groups of 0:21:49.200 --> 0:21:52.280 atoms that have a parallel orbital spin will line up 0:21:52.320 --> 0:21:55.840 within the crystal and those form those magnetic domains I 0:21:55.880 --> 0:21:59.480 mentioned earlier. The qualities that make good magnets are also 0:21:59.560 --> 0:22:03.000 the same ones as the qualities that make materials attracted 0:22:03.119 --> 0:22:06.159 to magnets. So a strong magnet will attract iron and 0:22:06.240 --> 0:22:10.560 other elements that have these orbital magnetic moments in alignment. Now, 0:22:10.600 --> 0:22:14.600 not all permanent magnets are equal. The ceramic magnets you 0:22:14.640 --> 0:22:16.800 may have on your fringe door a pretty weak all 0:22:16.840 --> 0:22:20.199 things considered. They're made of a mixture of iron oxide 0:22:20.240 --> 0:22:24.439 and a ceramic composite. These are ferric magnets, that's what 0:22:24.480 --> 0:22:26.760 we call them, ferric for the iron that's in them. 0:22:27.040 --> 0:22:30.879 But on the other end of the scale are neodymium magnets, 0:22:30.880 --> 0:22:34.720 a rare earth element magnet there is much much stronger 0:22:34.760 --> 0:22:37.600 than the ferric magnets we tend to use, and they 0:22:37.640 --> 0:22:42.800 typically contain a mixture of neodymium, iron and boron. They 0:22:42.840 --> 0:22:47.040 could be really strong too, uh, I have played with somewhere. 0:22:47.440 --> 0:22:49.960 If they get into contact with something like a metal table, 0:22:50.600 --> 0:22:54.000 it can be really hard to remove them. We had 0:22:54.040 --> 0:22:59.560 some here at how Stuff Works that were potentially causing injuries. Uh. 0:22:59.720 --> 0:23:02.200 One person slipped one in their pocket and then found 0:23:02.240 --> 0:23:05.320 themselves stuck to a filing cabinet for a little bit. Uh. 0:23:05.359 --> 0:23:08.280 This was way back in the day, but it was 0:23:08.320 --> 0:23:09.720 one of those things where a lot of us didn't 0:23:09.720 --> 0:23:11.280 have a whole lot of experience with it because at 0:23:11.320 --> 0:23:14.760 the time they were fairly uncommon. Today you can order 0:23:15.000 --> 0:23:19.679 neodymium and other rare earth magnets online without much trouble. 0:23:20.160 --> 0:23:23.400 But when I started um, first of all, how stuff 0:23:23.440 --> 0:23:26.000 works was easy because there are only three things, so 0:23:26.480 --> 0:23:28.439 it was easy to explain how stuff works. Once you 0:23:28.440 --> 0:23:31.160 wrote the three articles, you were done. But over time 0:23:31.160 --> 0:23:34.680 more stuff was made and we had more work to do, 0:23:35.080 --> 0:23:39.040 and at that point it was more. It was more 0:23:39.160 --> 0:23:43.320 uh uh, well, it was easier to get ahold of 0:23:43.359 --> 0:23:47.400 neodymium magnets at that point. Now, some materials are called 0:23:47.440 --> 0:23:50.960 temporary or soft magnets, and those will produce a magnetic 0:23:51.000 --> 0:23:53.840 field in the presence of another magnetic field and retain 0:23:53.960 --> 0:23:57.400 some of that magnetism for a while after they leave 0:23:57.480 --> 0:24:00.800 the field itself, so they're very easy to LUNs. So 0:24:00.920 --> 0:24:03.879 imagine that you've got something like a paper clip and 0:24:03.920 --> 0:24:06.600 you put it within the range of a magnetic field 0:24:06.600 --> 0:24:11.480 for a while, and it starts to have its magnetic 0:24:12.320 --> 0:24:15.919 domains aligned according to this magnetic field. You remove it 0:24:16.119 --> 0:24:18.040