WEBVTT - TechStuff Classic: How Magnetic Storage Works 0:00:04.440 --> 0:00:10.440 Welcome to tech Stuff, a production from iHeartRadio. 0:00:11.840 --> 0:00:12.680 Hey there, and. 0:00:12.600 --> 0:00:16.480 Welcome to tech Stuff. I'm your host, Jonathan Strickland. I'm 0:00:16.520 --> 0:00:20.159 an executive producer with iHeartRadio, and how the tech are you? 0:00:20.760 --> 0:00:23.680 It is time for a tech Stuff classic episode. This 0:00:23.720 --> 0:00:27.960 one is called How Magnetic Storage Works. It originally published 0:00:28.280 --> 0:00:34.680 on January twenty fifth, two thousand and seventeen. So how 0:00:34.680 --> 0:00:38.440 do you preserve information so that you can access it 0:00:38.479 --> 0:00:41.320 again later? Cause in the old days, and I'm talking 0:00:41.440 --> 0:00:44.920 like tens of thousands of years ago, verbal communication was 0:00:44.920 --> 0:00:47.760 where it was at. You stored all that information up 0:00:47.760 --> 0:00:50.519 in your head. Someone would tell you something important and 0:00:50.560 --> 0:00:52.879 you had to remember it. Perhaps they would tell you 0:00:52.920 --> 0:00:57.520 within the context of a story. And then eventually, if 0:00:57.560 --> 0:00:59.880 you were trying to preserve information, you would tell that 0:01:00.040 --> 0:01:03.520 same information to someone else and pass it along this way. 0:01:03.720 --> 0:01:09.640 This is essentially folklore. That's how knowledge was maintained for centuries. 0:01:10.400 --> 0:01:11.880 And then way back in the day. 0:01:11.760 --> 0:01:15.039 Someone said, hey, what if we made up some symbols 0:01:15.080 --> 0:01:18.800 to represent these sounds we're making to communicate with each other, 0:01:19.080 --> 0:01:21.000 and then we put those symbols into some sort of 0:01:21.480 --> 0:01:26.560 fixed format, like in a clay tablet, and that way, 0:01:26.800 --> 0:01:30.600 we can preserve the information a lot longer. And if Bob, 0:01:30.840 --> 0:01:34.600 who's really good at making fires, can explain how to 0:01:34.640 --> 0:01:37.920 make fires, and we put it down in this format, 0:01:38.200 --> 0:01:40.560 we'll be able to make fires even if Bob does 0:01:40.600 --> 0:01:43.880 something stupid like walks off the edge of a cliff 0:01:43.959 --> 0:01:48.480 or something. And writing was born. It probably went a 0:01:48.520 --> 0:01:50.520 little differently from the way I explained it, but I 0:01:50.560 --> 0:01:53.400 think I got the gist of it. Not everyone, however, 0:01:53.560 --> 0:01:56.120 was a fan of this development. Believe it or not, 0:01:56.240 --> 0:01:59.640 there were people who were against the whole idea of 0:01:59.720 --> 0:02:04.440 right stuff down. Socrates was actually a critic of writing 0:02:04.440 --> 0:02:07.240 stuff down, or at least that's what we hear, because 0:02:07.400 --> 0:02:12.080 Socrates didn't write anything down, his students did. He said 0:02:12.120 --> 0:02:15.280 that the written word is fixed, and therefore it can't 0:02:15.320 --> 0:02:19.680 defend itself or any arguments it makes, so it's inherently flawed. 0:02:20.240 --> 0:02:23.680 If someone writes down an argument and your access to 0:02:23.720 --> 0:02:27.120 the argument is in that written format, and you have 0:02:27.280 --> 0:02:31.480 questions or you have attacks on that argument, it can't 0:02:31.480 --> 0:02:34.360 defend itself. The person who wrote it could if they 0:02:34.440 --> 0:02:37.440 were there, but if they're not there, then the argument 0:02:37.480 --> 0:02:40.079 has to stand on its own, and therefore it has 0:02:40.160 --> 0:02:46.080 to be less effective, let's say, than an actual human being. 0:02:46.200 --> 0:02:48.040 He also said that if you write stuff down, you 0:02:48.080 --> 0:02:50.440 don't have to remember it yourself, and that makes you 0:02:50.520 --> 0:02:55.000 less intelligent, because if you're not actually committing something to memory, 0:02:55.560 --> 0:03:00.560 you're getting super dumb. This might sound a lot like 0:03:00.639 --> 0:03:02.880 some of the arguments people have made about Google and 0:03:02.960 --> 0:03:07.160 the Internet, and it's absolutely correct. Every single time we 0:03:07.280 --> 0:03:11.840 have created a new way to permanently store data in 0:03:11.880 --> 0:03:16.520 some form or another, people have brought up this idea 0:03:16.560 --> 0:03:20.399 that it's making us more dumb. Like they might say, hey, 0:03:20.440 --> 0:03:22.400 back in the day, you'd have to remember all your 0:03:22.440 --> 0:03:24.880 phone numbers, like all the numbers of the friends and 0:03:24.919 --> 0:03:26.960 family that you'd be calling on a regular basis. But 0:03:27.000 --> 0:03:28.720 now it's all on your phone, so you don't remember it. 0:03:29.360 --> 0:03:31.880 You may not be able to rattle off more than 0:03:31.919 --> 0:03:34.720 two or three phone numbers today because of that, therefore 0:03:34.760 --> 0:03:38.040 you are more dumb. I don't subscribe to that particular argument. 0:03:38.120 --> 0:03:42.720 I think having the accessibility of information outweighs the fact 0:03:42.760 --> 0:03:45.160 that we are no longer able to remember it necessarily. 0:03:46.160 --> 0:03:49.040 The point I would make is that comprehension is always 0:03:49.080 --> 0:03:53.320 more important than being able to recall something You might 0:03:53.360 --> 0:03:55.280 be able to recall some information, but if you don't 0:03:55.280 --> 0:03:58.640 truly comprehend it, it's of no use to you. So 0:03:59.320 --> 0:04:02.320 I don't think it's necessarily a measure of intelligence. It's 0:04:02.320 --> 0:04:05.160 certainly perhaps more of a statement about our memories than 0:04:05.160 --> 0:04:08.440 anything else. But I'm getting off on a tangent here, 0:04:09.320 --> 0:04:13.480 So I think the developments we've had have been phenomenal. 0:04:13.560 --> 0:04:14.560 We wouldn't be where. 0:04:14.360 --> 0:04:17.400 We are today if we were still depending upon just 0:04:17.520 --> 0:04:20.760 telling each other the important stuff and hoping that they 0:04:20.760 --> 0:04:24.440 would be able to then tell other people the important 0:04:24.440 --> 0:04:26.560 stuff we just told them and in a way that 0:04:26.720 --> 0:04:31.160 was accurate and effective. We clearly wouldn't be where we 0:04:31.200 --> 0:04:33.719 are today if we still depended upon that. And I 0:04:33.760 --> 0:04:35.920 don't have to travel all the way across the world 0:04:36.000 --> 0:04:38.599 to find a specific guru to learn how to perform 0:04:38.680 --> 0:04:42.200 a particular skill. I can just go onto YouTube and 0:04:42.640 --> 0:04:45.040 watch like thirty or forty videos until I find one 0:04:45.040 --> 0:04:51.280 that actually makes sense. So AD's progress take that, Socrates. Now, 0:04:51.279 --> 0:04:53.600 throughout history, we saw many advances in the way we 0:04:53.640 --> 0:04:57.680 store information, and as we developed more advanced technology, it 0:04:57.760 --> 0:05:00.560 became clear that a compatible method of star scoring data 0:05:00.640 --> 0:05:04.359 would be really handy. So imagine what computers would be 0:05:04.400 --> 0:05:07.560 if they could not save information. They'd be practically useless. 0:05:07.600 --> 0:05:10.679 You need to have a way of storing data somehow, 0:05:10.720 --> 0:05:14.680 whether it's in magnetic storage, optical, solid state punch cards, whatever. 0:05:14.720 --> 0:05:19.520 You need something that can record that information, otherwise it's 0:05:19.600 --> 0:05:22.239 only good for a moment. And a lot of folks 0:05:22.279 --> 0:05:25.000 worked on this problem, and as is the case with 0:05:25.120 --> 0:05:28.440 many technological developments, some of that work had nothing to 0:05:28.480 --> 0:05:32.279 do with computers, but more with researching fundamental scientific questions 0:05:32.760 --> 0:05:36.640 and finding answers to questions led other people being able 0:05:36.720 --> 0:05:39.919 to use that information in practical ways that we didn't anticipate. 0:05:40.560 --> 0:05:43.160 And this is kind of another soapbox I like to 0:05:43.200 --> 0:05:46.839 get up on to argue for the importance of exploratory science. 0:05:47.760 --> 0:05:50.360 Applied science is really interesting. Applied science is when you're 0:05:50.360 --> 0:05:53.719 trying to find a particular solution that will work for 0:05:53.839 --> 0:05:57.559 some sort of problem. Right you might be researching whether 0:05:57.640 --> 0:06:00.800 or not a specific material would be great rate to 0:06:01.040 --> 0:06:06.400 use for a particular purpose, like bulletproof material something like that. 0:06:06.800 --> 0:06:11.200 But exploratory science, when you're not necessarily looking for applications, 0:06:11.320 --> 0:06:15.039 is also important because we expand our knowledge about how 0:06:15.080 --> 0:06:18.919 the universe works. And it can open up opportunities to 0:06:19.040 --> 0:06:22.200 leverage that knowledge in ways we could not have anticipated 0:06:22.240 --> 0:06:24.680 when we first started looking into the issue in the 0:06:24.680 --> 0:06:29.599 first place. It's important stuff, so I argue that exploratory 0:06:29.600 --> 0:06:34.600 science needs to continue to be supported. Now acknowledge all this, 0:06:34.720 --> 0:06:36.320 take a deep breath, and get ready to jump into 0:06:36.360 --> 0:06:42.120 the strange world of magnetism. So first, magnetism, or more specifically, 0:06:42.240 --> 0:06:47.240 electro magnetism, is one of four fundamental forces that govern 0:06:47.839 --> 0:06:52.000 the atomic behavior in our universe. So the other three, 0:06:52.040 --> 0:06:55.480 if you're keeping track, are the strong nuclear force, the 0:06:55.520 --> 0:06:58.640 weak nuclear force, and gravity. And if you want to 0:06:58.720 --> 0:07:02.919 rank those from the weakest to the strongest, you'd start 0:07:02.960 --> 0:07:07.719 with gravity. Gravity is negligible at the atomic scale. It's there, 0:07:07.760 --> 0:07:11.360 but it's so faint as to be almost absent. And 0:07:11.440 --> 0:07:14.920 this is largely because gravity is dependent upon mass. So 0:07:15.000 --> 0:07:18.600 at the atomic scale, masses are so small there's barely 0:07:18.640 --> 0:07:22.640 any gravitational attraction between particles. But gravity is kind of 0:07:22.720 --> 0:07:26.760 nifty because while it's weak, it is there, and in fact, 0:07:27.000 --> 0:07:30.160 there's a gravitational pull on every bit of matter from 0:07:30.360 --> 0:07:34.240 every other bit of matter in our universe. So you 0:07:35.000 --> 0:07:37.720 that is you listening to me, right Now you are 0:07:38.320 --> 0:07:42.720 exerting a gravitational pull on the Sun, and on Alpha Centauri, 0:07:43.480 --> 0:07:47.640 and on the Andromeda galaxy. You are exerting a gravitational 0:07:47.640 --> 0:07:52.120 pull on everything else that is matter in our universe. 0:07:53.040 --> 0:07:56.400 It's just that that gravitational pull is so weak as 0:07:56.440 --> 0:08:00.520 to be practically nothing, but it is there. So since 0:08:00.520 --> 0:08:03.880 gravity is something we ourselves can and do experience in 0:08:03.920 --> 0:08:08.240 our daily lives, we categorize it as one of the 0:08:08.400 --> 0:08:14.840 familiar forces. Now, next in the rank from weakest to 0:08:14.960 --> 0:08:19.080 strongest is the weak force. Now that's responsible for nuclear 0:08:19.120 --> 0:08:22.480 beta decay and some other decay processes. And this one's 0:08:22.480 --> 0:08:25.000 pretty difficult to explain, and since I'm already going to 0:08:25.080 --> 0:08:28.720 have to explain magnetism, I'm gonna call for a pass 0:08:28.760 --> 0:08:29.320 on this one. 0:08:29.520 --> 0:08:30.400 Let's mulligan it. 0:08:31.160 --> 0:08:34.360 But this is a force that we do not experience 0:08:34.400 --> 0:08:37.000 firsthand in our daily lives, So this one actually falls 0:08:37.040 --> 0:08:42.040 into the category of unfamiliar forces. Now, next in strength, 0:08:42.320 --> 0:08:47.760 so second strongest, if you prefer, is the electromagnetic force, 0:08:47.800 --> 0:08:50.880 the one we'll be focusing on today. Now, this is 0:08:50.920 --> 0:08:53.679 a force that exists between all particles that have an 0:08:53.720 --> 0:08:57.440 electric charge, so electrons, for example, we'll bind to a 0:08:57.520 --> 0:09:01.679 nucleus because electrons have a nextative charge, and a nucleus 0:09:01.760 --> 0:09:06.320 which only contains positively charged protons and neutral neutrons is 0:09:06.400 --> 0:09:11.440 net positive. And you know that opposites attract, so we 0:09:11.600 --> 0:09:16.480 have the negative electrons attracted to the positive nucleus. We 0:09:16.720 --> 0:09:20.520 can and do experience electromagnetic forces on a daily basis, 0:09:20.520 --> 0:09:24.079 so this one is one of the familiar forces. And 0:09:24.480 --> 0:09:27.360 then we have the strongest of them all, the strong 0:09:27.760 --> 0:09:31.800 nuclear force. This is the force that holds a nucleus together. 0:09:32.440 --> 0:09:35.600 It's a dominant force in various chemical reactions, and it 0:09:35.679 --> 0:09:38.079 has to be strong because it's. 0:09:37.920 --> 0:09:39.920 Doing something that's really difficult to do. 0:09:40.040 --> 0:09:45.439 It's holding together similarly charged particles. Remember, a nucleus is 0:09:45.480 --> 0:09:49.120 a bunch of protons and neutrons. The protons all have 0:09:49.240 --> 0:09:52.720 a positive charge. They don't want to be and when 0:09:52.720 --> 0:09:55.680 I say want, I don't actually mean they have motivations, 0:09:55.679 --> 0:09:58.720 but they don't want to be next to each other. 0:10:00.240 --> 0:10:03.959 Those similar charges are repelling one another. So the strong 0:10:04.040 --> 0:10:07.600 nuclear force has to be stronger than the electromagnetic force 0:10:07.640 --> 0:10:10.360 in order to hold protons together in a nucleus with 0:10:10.400 --> 0:10:15.520 a bunch of neutral charge particles. It does have a 0:10:15.600 --> 0:10:19.839 very short range, however, so while it's stronger than the 0:10:19.920 --> 0:10:24.760 electromagnetic force, the range does not reach very far outside 0:10:24.760 --> 0:10:27.200 of a nucleus, so we don't directly observe it in 0:10:27.200 --> 0:10:30.720 our daily lives, and therefore it is an unfamiliar force. 0:10:31.080 --> 0:10:34.880 So gravity and electromagnetism are familiar forces. The strong and 0:10:34.920 --> 0:10:42.000 weak nuclear forces are unfamiliar forces. So what makes electromagnetism 0:10:42.040 --> 0:10:44.840 tick and how did we even figure out how to 0:10:44.920 --> 0:10:45.920 make good use of it? 0:10:46.440 --> 0:10:47.760 Well, let's start. 0:10:47.400 --> 0:10:50.320 By imagining a bar magnet. A lot of this is 0:10:50.360 --> 0:10:52.840 going to go back to stuff that you probably learned 0:10:52.880 --> 0:10:56.240 in elementary school, middle school, high school, those physics courses, 0:10:56.280 --> 0:10:59.040 that kind of stuff, basic science. So you've got your 0:10:59.080 --> 0:11:02.559 bar magnet. Let's just say it's a rectang. It's rectangular 0:11:02.600 --> 0:11:06.760 in shape, so you know you've got your north pole 0:11:06.920 --> 0:11:11.040 and your south pole on the magnet. This These represent 0:11:11.440 --> 0:11:15.240 the various charges magnetic charges of the magnet. 0:11:15.360 --> 0:11:16.360 Opposites tracked. 0:11:17.000 --> 0:11:20.040 So if we were to bring this bar magnet close 0:11:20.080 --> 0:11:23.360 to another bar magnet, the north end of our bar 0:11:23.480 --> 0:11:26.560 magnet would start to exert a pole on the south 0:11:26.800 --> 0:11:29.959 end of the other bar magnet. Or if we were 0:11:29.960 --> 0:11:32.800 to try and bring the north pole of our magnet 0:11:32.840 --> 0:11:35.240 close to the north pole of the second magnet, it 0:11:35.280 --> 0:11:38.640 would push against each other, just like I was mentioning 0:11:38.679 --> 0:11:41.960 a second ago. Now, magnets produce a field around them 0:11:42.080 --> 0:11:46.600 that we can represent as lines of force, and those 0:11:46.640 --> 0:11:50.720 lines exit from the north pole, loop around the magnet, 0:11:51.000 --> 0:11:54.439 and enter the south pole. A permanent magnet is always 0:11:54.520 --> 0:11:59.640 producing the sort of magnetic field. It's consistent, it doesn't waiver. 0:12:00.600 --> 0:12:04.079 You may hear about things like electromagnetism. I'll talk a 0:12:04.080 --> 0:12:07.240 little bit more about in a bit where you have 0:12:07.320 --> 0:12:10.439 to move a coil through a varying magnetic field. Well, 0:12:10.480 --> 0:12:15.280 a permanent magnet creates a consistent magnetic field unless you 0:12:15.360 --> 0:12:17.800 start doing things like moving it around, in which case 0:12:17.840 --> 0:12:20.280 you're really just moving where the magnetic field is. You're 0:12:20.320 --> 0:12:26.680 not actually fluctuating the field itself. Now, inside a magnet 0:12:26.760 --> 0:12:33.120 a permanent magnet are microscopic regions called magnetic domains, and 0:12:33.240 --> 0:12:36.920 each of these domains is essentially a tiny magnet with 0:12:36.960 --> 0:12:40.760 its own north and south pole. Only by aligning the 0:12:40.800 --> 0:12:45.760 poles of all of these magnetic domains in a similar direction, 0:12:46.000 --> 0:12:48.840 like north south, will you get a permanent magnet. 0:12:49.280 --> 0:12:52.240 So if you could just zoom in on. 0:12:52.200 --> 0:12:55.359 A permanent magnet, you would see all these tiny regions 0:12:55.880 --> 0:12:58.880 that are essentially magnets that are all aligned the same 0:12:58.960 --> 0:13:04.480 way south. If you didn't do that, if the alignment 0:13:04.800 --> 0:13:07.160 was mixed up so that you had, you know, an 0:13:07.200 --> 0:13:11.120 equal mixture of north south and south north, they would 0:13:11.160 --> 0:13:13.480 cancel each other out and you wouldn't have a magnet. 0:13:13.520 --> 0:13:18.800 It would just be inert magnetically speaking. So that is 0:13:18.840 --> 0:13:21.840 something that's interesting because you can actually do that to 0:13:22.000 --> 0:13:24.480 magnets in a couple of different ways. I'll talk about 0:13:24.480 --> 0:13:29.720 that in a second. So all of that is changeable, 0:13:30.679 --> 0:13:35.320 bomb bomb bomb. I wrote that in my notes. Actually 0:13:35.480 --> 0:13:37.920 I had to say it. I could show Dylan, but 0:13:37.920 --> 0:13:40.760 he's working on something else. By the way, when all 0:13:40.760 --> 0:13:44.440 those magnetic domains are aligned north south, what happens if 0:13:44.480 --> 0:13:46.800 you were to cut the magnet in half right between 0:13:46.840 --> 0:13:49.400 the north and south pole. So imagine you've got this 0:13:49.480 --> 0:13:51.120 rectangular bar magnet. 0:13:50.760 --> 0:13:52.120 You've got you've labeled one. 0:13:52.040 --> 0:13:53.960 End the north pole, the other end of the south pole. 0:13:54.280 --> 0:13:58.959 You cut the magnet in half horizontally across, well, you 0:13:59.000 --> 0:14:02.840 would end up with two magnet. The middle of that 0:14:02.880 --> 0:14:05.880 magnet would become the south pole for the north end 0:14:05.960 --> 0:14:08.160 and the north pole for the south end. That's because 0:14:08.320 --> 0:14:11.960 those magnetic domains I was talking about, those tiny regions 0:14:12.000 --> 0:14:16.120 inside the magnet themselves itself, those are all aligned north south. 0:14:16.240 --> 0:14:18.600 So if you cut the magnet across, you still have 0:14:18.679 --> 0:14:22.960 those magnetic domains lined up north south, so the overall 0:14:23.040 --> 0:14:26.040 magnetism is preserved. You get two magnets for the price 0:14:26.080 --> 0:14:29.920 of one. But don't cut into magnets. Magnets, they tend 0:14:29.960 --> 0:14:32.280 to be, at least the ones that we typically use 0:14:32.440 --> 0:14:34.920 for things like our fridges and stuff are ceramic magnets, 0:14:34.960 --> 0:14:36.640 and they don't cut so well unless you have like 0:14:36.680 --> 0:14:41.800 a diamond saw, which some of you probably do. And 0:14:42.200 --> 0:14:45.480 if you cut magnets normally, then disregard my warning. I'm 0:14:45.480 --> 0:14:47.800 talking about people who don't typically do that sort of thing. 0:14:48.040 --> 0:14:49.760 If you are going to do it, where eye protection 0:14:49.840 --> 0:14:56.160 because that stuff can shatter anyway. If you do that 0:14:56.320 --> 0:15:00.040 with a magnet. Essentially, each magnet has approximately half the 0:15:00.080 --> 0:15:04.160 magnetic domains of the old magnet, so they're not particularly 0:15:04.240 --> 0:15:06.880 you know, the individual magnets aren't as strong as they 0:15:06.880 --> 0:15:10.400 were when they were a single magnet. Because your yournet, 0:15:10.640 --> 0:15:15.320 your overall magnet strength is dependent upon the accumulative effect 0:15:15.480 --> 0:15:19.480 of the magnetic domains within it, all right, So each 0:15:19.640 --> 0:15:24.320 of those magnetic domains are tiny magnets. There are three 0:15:24.360 --> 0:15:26.800 ways to get them to line up so that the 0:15:26.880 --> 0:15:30.560 overall material becomes a magnet itself. Like how you get 0:15:30.560 --> 0:15:33.320 them all to line up? Like north south? So way 0:15:33.440 --> 0:15:36.200 number one is to whack on it with something heavy, 0:15:36.960 --> 0:15:39.200 which isn't a joke. If you hold the material in 0:15:39.240 --> 0:15:41.480 a north south direction and strike it with a hammer, 0:15:41.960 --> 0:15:45.760 you physically realign the magnetic domains and you can knock 0:15:45.840 --> 0:15:50.360 the material into a weak magnet. There's a bit more 0:15:50.400 --> 0:15:52.280 to it than that, but that's the basic idea, and 0:15:52.320 --> 0:15:54.160 that that does mean that you're not going to get 0:15:54.160 --> 0:15:56.440 a very strong magnet as a result, but you can 0:15:56.720 --> 0:16:01.800 physically force those magnetic domains to be in the same 0:16:01.880 --> 0:16:06.160 direction and create a magnet that way. Way number two 0:16:06.680 --> 0:16:09.680 is that you can place the material inside a strong 0:16:09.760 --> 0:16:12.160 magnetic field and make sure the material is in a 0:16:12.240 --> 0:16:15.920 north south alignment and you just leave it there, and 0:16:16.320 --> 0:16:18.720 if it's a strong magnetic field, it will start to 0:16:18.960 --> 0:16:23.800 realign the magnetic domains within your target material so that 0:16:23.920 --> 0:16:28.800 they gradually line up with the magnetic fields direction, so 0:16:28.840 --> 0:16:30.280 you just have to have a strong enough one to 0:16:30.320 --> 0:16:33.040 affect the magnetic domains in your target material and then 0:16:33.080 --> 0:16:36.360 eventually you end up with a magnet So that's kind 0:16:36.360 --> 0:16:39.200 of cool. And way number three is ya zap it 0:16:39.360 --> 0:16:43.760 with electric current. So one hypothesis is that this is 0:16:43.800 --> 0:16:47.480 how loadstone, which is a naturally magnetic material you can 0:16:47.520 --> 0:16:51.000 find here on Earth, was originally formed. The idea is 0:16:51.040 --> 0:16:54.560 that loadstone, which is made up of the stuff called magnetite, 0:16:55.920 --> 0:16:59.960 some of it was struck by lightning over the millennium 0:17:00.440 --> 0:17:04.399 that Earth was forming, So you have magnetite on the surface. 0:17:04.040 --> 0:17:04.600 Of the planet. 0:17:04.680 --> 0:17:07.919 Occasionally lightning strikes and hit some of this magnetite and 0:17:07.960 --> 0:17:13.720 then magnetizes it. That's one hypothesis, but there's another one 0:17:13.760 --> 0:17:17.199 which suggests that magnetite gained its magnetic properties during the 0:17:17.200 --> 0:17:19.560 time when Earth was forming, and it was through more 0:17:19.600 --> 0:17:23.920 of just a physical the physical process of cooling where 0:17:23.960 --> 0:17:25.840 these magnetic domains aligned in. 0:17:25.760 --> 0:17:26.520 The proper way. 0:17:27.160 --> 0:17:30.360 Here's the thing, we don't really know how it all 0:17:30.400 --> 0:17:31.160 got started. 0:17:31.400 --> 0:17:32.520 We don't have that information. 0:17:32.640 --> 0:17:34.840 No one was around back then to write it down 0:17:35.160 --> 0:17:38.200 or put it in magnetic storage. So it's still a 0:17:38.200 --> 0:17:40.640 bit of a mystery, but we do know that those 0:17:40.640 --> 0:17:43.320 are two possible ways that this could have come about. 0:17:44.280 --> 0:17:45.439 And you can. 0:17:45.359 --> 0:17:50.080 Also render magnets inert by changing the alignment of the 0:17:50.080 --> 0:17:53.520 magnetic domains within it. If you heat a magnet up 0:17:53.560 --> 0:17:58.160 beyond its Curey point, which is different for different magnetic materials, 0:17:58.520 --> 0:18:02.119 it loses its magnetism. The heat warps the material and 0:18:02.200 --> 0:18:05.679 makes the magnetic domains fall out of alignment. So what 0:18:05.960 --> 0:18:08.880 used to be magnetic will no longer be so something 0:18:08.920 --> 0:18:11.320 that would stick to your fringe no problem, will just 0:18:11.359 --> 0:18:14.960 slide off and hit the floor, and everyone will be sad, 0:18:15.640 --> 0:18:17.919 unless you just did it as a scientific experiment, in 0:18:17.920 --> 0:18:19.399 which case you might be happy that you got the 0:18:19.440 --> 0:18:25.360 result you expected. Now we can experience magnetism because of electrons. 0:18:25.560 --> 0:18:29.359 Those tiny, negatively charged sub atomic particles hold the key 0:18:29.520 --> 0:18:33.520 to whether material is affected by magnets or isn't. You 0:18:33.680 --> 0:18:36.320 might wonder, like, why are some things magnetic and some 0:18:36.400 --> 0:18:39.239 things art? Why do magnets stick to some materials but 0:18:39.359 --> 0:18:42.840 slide right off of other materials? And ultimately the answer 0:18:42.880 --> 0:18:50.480 of falls with electrons. Now, electrons orbit the nucleus right 0:18:50.680 --> 0:18:53.960 in atoms, You remember your basic description of an atom 0:18:53.960 --> 0:18:56.320 where you have a nucleus at the center and electrons 0:18:56.400 --> 0:19:02.000 orbiting at different orbital shells around the electrons. Typically electrons 0:19:02.000 --> 0:19:05.919 will pair up with other electrons. You'll get pairs of electrons. 0:19:05.960 --> 0:19:10.120 They have a state that's called spin, and each electron 0:19:10.160 --> 0:19:12.760 in a pair has the opposite spin of its partner, 0:19:13.240 --> 0:19:16.359 So we can describe spin as up or down. For example, 0:19:16.840 --> 0:19:20.080 if one electron is spinning up, the other one by necessity, 0:19:20.200 --> 0:19:23.879 has to be spinning down. You cannot get both electrons 0:19:23.920 --> 0:19:26.960 in a pair to spin in the same direction in 0:19:27.000 --> 0:19:30.120 the same orbital That just that ain't cricket. It's part 0:19:30.119 --> 0:19:34.080 of a quantum mechanical principle we call the poly exclusion principle. 0:19:34.840 --> 0:19:36.880 And until I did research for the show, I could 0:19:36.920 --> 0:19:39.200 have sworn that referred to the practice of not inviting 0:19:39.240 --> 0:19:42.000 poly shore to your parties. So I guess you learned 0:19:42.040 --> 0:19:45.280 something new every day. That got a smirk from Dylan. 0:19:46.040 --> 0:19:48.919 It's maybe he'll laugh when he listens to it the 0:19:48.960 --> 0:19:53.239 second time. Some elements have an unpaired electron in an 0:19:53.320 --> 0:19:55.760 orbital just because that's just how it works out. So 0:19:56.720 --> 0:20:01.760 those unpaired spinning electrons generate a very tiny magnetic field, 0:20:02.200 --> 0:20:05.800 and we call it an orbital magnetic moment, which sounds 0:20:05.840 --> 0:20:09.440 like something you'd expect in a romantic science fiction film. Iron, 0:20:09.800 --> 0:20:14.639 for example, has four unpaired electrons that all have the 0:20:14.720 --> 0:20:20.119 same spin. Those four unpaired electrons have an orbital magnetic moment. 0:20:20.400 --> 0:20:23.840 So magnetic moment has a magnitude and a direction, which 0:20:23.880 --> 0:20:27.280 means it is a vector. The bottom line is this 0:20:27.400 --> 0:20:30.280 vector refers to the strength of the magnetic field and 0:20:30.320 --> 0:20:34.520 the torque it can exert. So a permanent magnets magnetic 0:20:34.560 --> 0:20:37.600 moments are composed of all the moments of its atoms. 0:20:38.160 --> 0:20:42.240 In other words, we've got all these atoms that represent 0:20:42.359 --> 0:20:45.240 an orbital magnetic moment because of the spin of the 0:20:45.320 --> 0:20:47.359 electrons of the unpaired electrons. 0:20:47.359 --> 0:20:48.600 If you've got enough of them. 0:20:48.440 --> 0:20:51.440 And they're aligned the right way, that determines the permanent 0:20:51.480 --> 0:20:56.640 magnets magnetic moments. So iron and several other magnetic elements 0:20:56.680 --> 0:21:00.880 have a crystalline structure, right, So think of it like scaffolding. 0:21:01.440 --> 0:21:05.120 It makes this very ordered kind of structure as opposed 0:21:05.200 --> 0:21:08.679 to something that looks much more chaotic. So as iron 0:21:08.800 --> 0:21:12.639 cools from a molten state, atoms line up into this 0:21:12.760 --> 0:21:16.600 crystalline arrangement. And groups of atoms that have a parallel 0:21:16.720 --> 0:21:20.120 orbital spin will line up within the crystal, and those 0:21:20.200 --> 0:21:24.040 form those magnetic domains I mentioned earlier. The qualities that 0:21:24.080 --> 0:21:26.919 make good magnets are also the same ones as the 0:21:26.960 --> 0:21:29.879 qualities that make materials attracted to magnets. 0:21:30.000 --> 0:21:30.840 So a strong. 0:21:30.600 --> 0:21:33.320 Magnet will attract iron and other elements that have these 0:21:33.480 --> 0:21:38.200 orbital magnetic moments in alignment. Now, not all permanent magnets 0:21:38.359 --> 0:21:41.399 are equal. The ceramic magnets you may have on your 0:21:41.400 --> 0:21:44.480 fringe door are pretty weak all things considered. They're made 0:21:44.480 --> 0:21:47.960 of a mixture of iron oxide and a ceramic composite. 0:21:48.160 --> 0:21:51.439 These are feric magnets. That's what we call them, feric 0:21:51.520 --> 0:21:53.720 for the iron that's in them. But on the other 0:21:53.840 --> 0:21:57.600 end of the scale are neodymium magnets, a rare earth 0:21:57.640 --> 0:22:01.359 element magnet does much much, much stronger than the feric 0:22:01.400 --> 0:22:04.600 magnets we tend to use, and they typically contain a 0:22:04.640 --> 0:22:09.440 mixture of neodymium, iron and boron. They could be really 0:22:09.480 --> 0:22:13.720 strong too. I have played with some where if they 0:22:13.800 --> 0:22:16.760 get into contact with something like a metal table, it 0:22:16.800 --> 0:22:20.159 can be really hard to remove them. We had some 0:22:20.320 --> 0:22:24.679 here at How Stuff Works that were potentially causing injuries. 0:22:25.800 --> 0:22:28.240 One person slipped one in their pocket and then found 0:22:28.280 --> 0:22:30.680 themselves stuck to a filing cabinet for a little bit. 0:22:31.400 --> 0:22:33.080 This was way back in the day, but. 0:22:34.080 --> 0:22:35.280 It was one of those things where a lot of 0:22:35.359 --> 0:22:36.919 us didn't have a whole lot of experience with it 0:22:36.920 --> 0:22:40.240 because at the time they were fairly uncommon. Today you 0:22:40.280 --> 0:22:45.080 can order neodymium and other rare earth magnets online without 0:22:45.119 --> 0:22:49.119 much trouble. But when I started, first of all, how 0:22:49.160 --> 0:22:51.560 stuff works was easy because there were only three things, 0:22:51.840 --> 0:22:54.400 so it was easy to explain how stuff works. Once 0:22:54.400 --> 0:22:55.959 you wrote the three articles, you were done. 0:22:56.480 --> 0:22:58.160 But over time more stuff. 0:22:57.920 --> 0:23:01.199 Was made and we had more work to do, and 0:23:01.440 --> 0:23:03.880 at that point it was more. 0:23:04.119 --> 0:23:04.880 It was more. 0:23:07.400 --> 0:23:10.400 Well, it was easier to get hold of neodymium magnets 0:23:10.400 --> 0:23:14.280 at that point. Now some materials are called temporary or 0:23:14.320 --> 0:23:17.399 soft magnets, and those will produce a magnetic field in 0:23:17.440 --> 0:23:20.240 the presence of another magnetic field and retain some of 0:23:20.240 --> 0:23:24.560 that magnetism for a while after they leave the field itself, 0:23:24.880 --> 0:23:27.680 so they're very easy to influence. So imagine that you've 0:23:27.680 --> 0:23:30.439 got something like a paper clip and you put it 0:23:30.480 --> 0:23:33.240 within the range of a magnetic field for a while 0:23:33.800 --> 0:23:39.960 and it starts to have its magnetic domains aligned according 0:23:40.000 --> 0:23:42.720