Speaker 1: Welcome to tech Stuff, a production from iHeartRadio.
Speaker 2: Hey there, and.
Speaker 1: Welcome to tech Stuff. I'm your host, Jonathan Strickland. I'm
Speaker 1: an executive producer with iHeartRadio, and how the tech are you?
Speaker 1: It is time for a tech Stuff classic episode. This
Speaker 1: one is called How Magnetic Storage Works. It originally published
Speaker 1: on January twenty fifth, two thousand and seventeen. So how
Speaker 1: do you preserve information so that you can access it
Speaker 1: again later? Cause in the old days, and I'm talking
Speaker 1: like tens of thousands of years ago, verbal communication was
Speaker 1: where it was at. You stored all that information up
Speaker 1: in your head. Someone would tell you something important and
Speaker 1: you had to remember it. Perhaps they would tell you
Speaker 1: within the context of a story. And then eventually, if
Speaker 1: you were trying to preserve information, you would tell that
Speaker 1: same information to someone else and pass it along this way.
Speaker 1: This is essentially folklore. That's how knowledge was maintained for centuries.
Speaker 2: And then way back in the day.
Speaker 1: Someone said, hey, what if we made up some symbols
Speaker 1: to represent these sounds we're making to communicate with each other,
Speaker 1: and then we put those symbols into some sort of
Speaker 1: fixed format, like in a clay tablet, and that way,
Speaker 1: we can preserve the information a lot longer. And if Bob,
Speaker 1: who's really good at making fires, can explain how to
Speaker 1: make fires, and we put it down in this format,
Speaker 1: we'll be able to make fires even if Bob does
Speaker 1: something stupid like walks off the edge of a cliff
Speaker 1: or something. And writing was born. It probably went a
Speaker 1: little differently from the way I explained it, but I
Speaker 1: think I got the gist of it. Not everyone, however,
Speaker 1: was a fan of this development. Believe it or not,
Speaker 1: there were people who were against the whole idea of
Speaker 1: right stuff down. Socrates was actually a critic of writing
Speaker 1: stuff down, or at least that's what we hear, because
Speaker 1: Socrates didn't write anything down, his students did. He said
Speaker 1: that the written word is fixed, and therefore it can't
Speaker 1: defend itself or any arguments it makes, so it's inherently flawed.
Speaker 1: If someone writes down an argument and your access to
Speaker 1: the argument is in that written format, and you have
Speaker 1: questions or you have attacks on that argument, it can't
Speaker 1: defend itself. The person who wrote it could if they
Speaker 1: were there, but if they're not there, then the argument
Speaker 1: has to stand on its own, and therefore it has
Speaker 1: to be less effective, let's say, than an actual human being.
Speaker 1: He also said that if you write stuff down, you
Speaker 1: don't have to remember it yourself, and that makes you
Speaker 1: less intelligent, because if you're not actually committing something to memory,
Speaker 1: you're getting super dumb. This might sound a lot like
Speaker 1: some of the arguments people have made about Google and
Speaker 1: the Internet, and it's absolutely correct. Every single time we
Speaker 1: have created a new way to permanently store data in
Speaker 1: some form or another, people have brought up this idea
Speaker 1: that it's making us more dumb. Like they might say, hey,
Speaker 1: back in the day, you'd have to remember all your
Speaker 1: phone numbers, like all the numbers of the friends and
Speaker 1: family that you'd be calling on a regular basis. But
Speaker 1: now it's all on your phone, so you don't remember it.
Speaker 1: You may not be able to rattle off more than
Speaker 1: two or three phone numbers today because of that, therefore
Speaker 1: you are more dumb. I don't subscribe to that particular argument.
Speaker 1: I think having the accessibility of information outweighs the fact
Speaker 1: that we are no longer able to remember it necessarily.
Speaker 1: The point I would make is that comprehension is always
Speaker 1: more important than being able to recall something You might
Speaker 1: be able to recall some information, but if you don't
Speaker 1: truly comprehend it, it's of no use to you. So
Speaker 1: I don't think it's necessarily a measure of intelligence. It's
Speaker 1: certainly perhaps more of a statement about our memories than
Speaker 1: anything else. But I'm getting off on a tangent here,
Speaker 1: So I think the developments we've had have been phenomenal.
Speaker 2: We wouldn't be where.
Speaker 1: We are today if we were still depending upon just
Speaker 1: telling each other the important stuff and hoping that they
Speaker 1: would be able to then tell other people the important
Speaker 1: stuff we just told them and in a way that
Speaker 1: was accurate and effective. We clearly wouldn't be where we
Speaker 1: are today if we still depended upon that. And I
Speaker 1: don't have to travel all the way across the world
Speaker 1: to find a specific guru to learn how to perform
Speaker 1: a particular skill. I can just go onto YouTube and
Speaker 1: watch like thirty or forty videos until I find one
Speaker 1: that actually makes sense. So AD's progress take that, Socrates. Now,
Speaker 1: throughout history, we saw many advances in the way we
Speaker 1: store information, and as we developed more advanced technology, it
Speaker 1: became clear that a compatible method of star scoring data
Speaker 1: would be really handy. So imagine what computers would be
Speaker 1: if they could not save information. They'd be practically useless.
Speaker 1: You need to have a way of storing data somehow,
Speaker 1: whether it's in magnetic storage, optical, solid state punch cards, whatever.
Speaker 1: You need something that can record that information, otherwise it's
Speaker 1: only good for a moment. And a lot of folks
Speaker 1: worked on this problem, and as is the case with
Speaker 1: many technological developments, some of that work had nothing to
Speaker 1: do with computers, but more with researching fundamental scientific questions
Speaker 1: and finding answers to questions led other people being able
Speaker 1: to use that information in practical ways that we didn't anticipate.
Speaker 1: And this is kind of another soapbox I like to
Speaker 1: get up on to argue for the importance of exploratory science.
Speaker 1: Applied science is really interesting. Applied science is when you're
Speaker 1: trying to find a particular solution that will work for
Speaker 1: some sort of problem. Right you might be researching whether
Speaker 1: or not a specific material would be great rate to
Speaker 1: use for a particular purpose, like bulletproof material something like that.
Speaker 1: But exploratory science, when you're not necessarily looking for applications,
Speaker 1: is also important because we expand our knowledge about how
Speaker 1: the universe works. And it can open up opportunities to
Speaker 1: leverage that knowledge in ways we could not have anticipated
Speaker 1: when we first started looking into the issue in the
Speaker 1: first place. It's important stuff, so I argue that exploratory
Speaker 1: science needs to continue to be supported. Now acknowledge all this,
Speaker 1: take a deep breath, and get ready to jump into
Speaker 1: the strange world of magnetism. So first, magnetism, or more specifically,
Speaker 1: electro magnetism, is one of four fundamental forces that govern
Speaker 1: the atomic behavior in our universe. So the other three,
Speaker 1: if you're keeping track, are the strong nuclear force, the
Speaker 1: weak nuclear force, and gravity. And if you want to
Speaker 1: rank those from the weakest to the strongest, you'd start
Speaker 1: with gravity. Gravity is negligible at the atomic scale. It's there,
Speaker 1: but it's so faint as to be almost absent. And
Speaker 1: this is largely because gravity is dependent upon mass. So
Speaker 1: at the atomic scale, masses are so small there's barely
Speaker 1: any gravitational attraction between particles. But gravity is kind of
Speaker 1: nifty because while it's weak, it is there, and in fact,
Speaker 1: there's a gravitational pull on every bit of matter from
Speaker 1: every other bit of matter in our universe. So you
Speaker 1: that is you listening to me, right Now you are
Speaker 1: exerting a gravitational pull on the Sun, and on Alpha Centauri,
Speaker 1: and on the Andromeda galaxy. You are exerting a gravitational
Speaker 1: pull on everything else that is matter in our universe.
Speaker 1: It's just that that gravitational pull is so weak as
Speaker 1: to be practically nothing, but it is there. So since
Speaker 1: gravity is something we ourselves can and do experience in
Speaker 1: our daily lives, we categorize it as one of the
Speaker 1: familiar forces. Now, next in the rank from weakest to
Speaker 1: strongest is the weak force. Now that's responsible for nuclear
Speaker 1: beta decay and some other decay processes. And this one's
Speaker 1: pretty difficult to explain, and since I'm already going to
Speaker 1: have to explain magnetism, I'm gonna call for a pass
Speaker 1: on this one.
Speaker 2: Let's mulligan it.
Speaker 1: But this is a force that we do not experience
Speaker 1: firsthand in our daily lives, So this one actually falls
Speaker 1: into the category of unfamiliar forces. Now, next in strength,
Speaker 1: so second strongest, if you prefer, is the electromagnetic force,
Speaker 1: the one we'll be focusing on today. Now, this is
Speaker 1: a force that exists between all particles that have an
Speaker 1: electric charge, so electrons, for example, we'll bind to a
Speaker 1: nucleus because electrons have a nextative charge, and a nucleus
Speaker 1: which only contains positively charged protons and neutral neutrons is
Speaker 1: net positive. And you know that opposites attract, so we
Speaker 1: have the negative electrons attracted to the positive nucleus. We
Speaker 1: can and do experience electromagnetic forces on a daily basis,
Speaker 1: so this one is one of the familiar forces. And
Speaker 1: then we have the strongest of them all, the strong
Speaker 1: nuclear force. This is the force that holds a nucleus together.
Speaker 1: It's a dominant force in various chemical reactions, and it
Speaker 1: has to be strong because it's.
Speaker 2: Doing something that's really difficult to do.
Speaker 1: It's holding together similarly charged particles. Remember, a nucleus is
Speaker 1: a bunch of protons and neutrons. The protons all have
Speaker 1: a positive charge. They don't want to be and when
Speaker 1: I say want, I don't actually mean they have motivations,
Speaker 1: but they don't want to be next to each other.
Speaker 1: Those similar charges are repelling one another. So the strong
Speaker 1: nuclear force has to be stronger than the electromagnetic force
Speaker 1: in order to hold protons together in a nucleus with
Speaker 1: a bunch of neutral charge particles. It does have a
Speaker 1: very short range, however, so while it's stronger than the
Speaker 1: electromagnetic force, the range does not reach very far outside
Speaker 1: of a nucleus, so we don't directly observe it in
Speaker 1: our daily lives, and therefore it is an unfamiliar force.
Speaker 1: So gravity and electromagnetism are familiar forces. The strong and
Speaker 1: weak nuclear forces are unfamiliar forces. So what makes electromagnetism
Speaker 1: tick and how did we even figure out how to
Speaker 1: make good use of it?
Speaker 2: Well, let's start.
Speaker 1: By imagining a bar magnet. A lot of this is
Speaker 1: going to go back to stuff that you probably learned
Speaker 1: in elementary school, middle school, high school, those physics courses,
Speaker 1: that kind of stuff, basic science. So you've got your
Speaker 1: bar magnet. Let's just say it's a rectang. It's rectangular
Speaker 1: in shape, so you know you've got your north pole
Speaker 1: and your south pole on the magnet. This These represent
Speaker 1: the various charges magnetic charges of the magnet.
Speaker 2: Opposites tracked.
Speaker 1: So if we were to bring this bar magnet close
Speaker 1: to another bar magnet, the north end of our bar
Speaker 1: magnet would start to exert a pole on the south
Speaker 1: end of the other bar magnet. Or if we were
Speaker 1: to try and bring the north pole of our magnet
Speaker 1: close to the north pole of the second magnet, it
Speaker 1: would push against each other, just like I was mentioning
Speaker 1: a second ago. Now, magnets produce a field around them
Speaker 1: that we can represent as lines of force, and those
Speaker 1: lines exit from the north pole, loop around the magnet,
Speaker 1: and enter the south pole. A permanent magnet is always
Speaker 1: producing the sort of magnetic field. It's consistent, it doesn't waiver.
Speaker 1: You may hear about things like electromagnetism. I'll talk a
Speaker 1: little bit more about in a bit where you have
Speaker 1: to move a coil through a varying magnetic field. Well,
Speaker 1: a permanent magnet creates a consistent magnetic field unless you
Speaker 1: start doing things like moving it around, in which case
Speaker 1: you're really just moving where the magnetic field is. You're
Speaker 1: not actually fluctuating the field itself. Now, inside a magnet
Speaker 1: a permanent magnet are microscopic regions called magnetic domains, and
Speaker 1: each of these domains is essentially a tiny magnet with
Speaker 1: its own north and south pole. Only by aligning the
Speaker 1: poles of all of these magnetic domains in a similar direction,
Speaker 1: like north south, will you get a permanent magnet.
Speaker 2: So if you could just zoom in on.
Speaker 1: A permanent magnet, you would see all these tiny regions
Speaker 1: that are essentially magnets that are all aligned the same
Speaker 1: way south. If you didn't do that, if the alignment
Speaker 1: was mixed up so that you had, you know, an
Speaker 1: equal mixture of north south and south north, they would
Speaker 1: cancel each other out and you wouldn't have a magnet.
Speaker 1: It would just be inert magnetically speaking. So that is
Speaker 1: something that's interesting because you can actually do that to
Speaker 1: magnets in a couple of different ways. I'll talk about
Speaker 1: that in a second. So all of that is changeable,
Speaker 1: bomb bomb bomb. I wrote that in my notes. Actually
Speaker 1: I had to say it. I could show Dylan, but
Speaker 1: he's working on something else. By the way, when all
Speaker 1: those magnetic domains are aligned north south, what happens if
Speaker 1: you were to cut the magnet in half right between
Speaker 1: the north and south pole. So imagine you've got this
Speaker 1: rectangular bar magnet.
Speaker 2: You've got you've labeled one.
Speaker 1: End the north pole, the other end of the south pole.
Speaker 1: You cut the magnet in half horizontally across, well, you
Speaker 1: would end up with two magnet. The middle of that
Speaker 1: magnet would become the south pole for the north end
Speaker 1: and the north pole for the south end. That's because
Speaker 1: those magnetic domains I was talking about, those tiny regions
Speaker 1: inside the magnet themselves itself, those are all aligned north south.
Speaker 1: So if you cut the magnet across, you still have
Speaker 1: those magnetic domains lined up north south, so the overall
Speaker 1: magnetism is preserved. You get two magnets for the price
Speaker 1: of one. But don't cut into magnets. Magnets, they tend
Speaker 1: to be, at least the ones that we typically use
Speaker 1: for things like our fridges and stuff are ceramic magnets,
Speaker 1: and they don't cut so well unless you have like
Speaker 1: a diamond saw, which some of you probably do. And
Speaker 1: if you cut magnets normally, then disregard my warning. I'm
Speaker 1: talking about people who don't typically do that sort of thing.
Speaker 1: If you are going to do it, where eye protection
Speaker 1: because that stuff can shatter anyway. If you do that
Speaker 1: with a magnet. Essentially, each magnet has approximately half the
Speaker 1: magnetic domains of the old magnet, so they're not particularly
Speaker 1: you know, the individual magnets aren't as strong as they
Speaker 1: were when they were a single magnet. Because your yournet,
Speaker 1: your overall magnet strength is dependent upon the accumulative effect
Speaker 1: of the magnetic domains within it, all right, So each
Speaker 1: of those magnetic domains are tiny magnets. There are three
Speaker 1: ways to get them to line up so that the
Speaker 1: overall material becomes a magnet itself. Like how you get
Speaker 1: them all to line up? Like north south? So way
Speaker 1: number one is to whack on it with something heavy,
Speaker 1: which isn't a joke. If you hold the material in
Speaker 1: a north south direction and strike it with a hammer,
Speaker 1: you physically realign the magnetic domains and you can knock
Speaker 1: the material into a weak magnet. There's a bit more
Speaker 1: to it than that, but that's the basic idea, and
Speaker 1: that that does mean that you're not going to get
Speaker 1: a very strong magnet as a result, but you can
Speaker 1: physically force those magnetic domains to be in the same
Speaker 1: direction and create a magnet that way. Way number two
Speaker 1: is that you can place the material inside a strong
Speaker 1: magnetic field and make sure the material is in a
Speaker 1: north south alignment and you just leave it there, and
Speaker 1: if it's a strong magnetic field, it will start to
Speaker 1: realign the magnetic domains within your target material so that
Speaker 1: they gradually line up with the magnetic fields direction, so
Speaker 1: you just have to have a strong enough one to
Speaker 1: affect the magnetic domains in your target material and then
Speaker 1: eventually you end up with a magnet So that's kind
Speaker 1: of cool. And way number three is ya zap it
Speaker 1: with electric current. So one hypothesis is that this is
Speaker 1: how loadstone, which is a naturally magnetic material you can
Speaker 1: find here on Earth, was originally formed. The idea is
Speaker 1: that loadstone, which is made up of the stuff called magnetite,
Speaker 1: some of it was struck by lightning over the millennium
Speaker 1: that Earth was forming, So you have magnetite on the surface.
Speaker 2: Of the planet.
Speaker 1: Occasionally lightning strikes and hit some of this magnetite and
Speaker 1: then magnetizes it. That's one hypothesis, but there's another one
Speaker 1: which suggests that magnetite gained its magnetic properties during the
Speaker 1: time when Earth was forming, and it was through more
Speaker 1: of just a physical the physical process of cooling where
Speaker 1: these magnetic domains aligned in.
Speaker 2: The proper way.
Speaker 1: Here's the thing, we don't really know how it all
Speaker 1: got started.
Speaker 2: We don't have that information.
Speaker 1: No one was around back then to write it down
Speaker 1: or put it in magnetic storage. So it's still a
Speaker 1: bit of a mystery, but we do know that those
Speaker 1: are two possible ways that this could have come about.
Speaker 2: And you can.
Speaker 1: Also render magnets inert by changing the alignment of the
Speaker 1: magnetic domains within it. If you heat a magnet up
Speaker 1: beyond its Curey point, which is different for different magnetic materials,
Speaker 1: it loses its magnetism. The heat warps the material and
Speaker 1: makes the magnetic domains fall out of alignment. So what
Speaker 1: used to be magnetic will no longer be so something
Speaker 1: that would stick to your fringe no problem, will just
Speaker 1: slide off and hit the floor, and everyone will be sad,
Speaker 1: unless you just did it as a scientific experiment, in
Speaker 1: which case you might be happy that you got the
Speaker 1: result you expected. Now we can experience magnetism because of electrons.
Speaker 1: Those tiny, negatively charged sub atomic particles hold the key
Speaker 1: to whether material is affected by magnets or isn't. You
Speaker 1: might wonder, like, why are some things magnetic and some
Speaker 1: things art? Why do magnets stick to some materials but
Speaker 1: slide right off of other materials? And ultimately the answer
Speaker 1: of falls with electrons. Now, electrons orbit the nucleus right
Speaker 1: in atoms, You remember your basic description of an atom
Speaker 1: where you have a nucleus at the center and electrons
Speaker 1: orbiting at different orbital shells around the electrons. Typically electrons
Speaker 1: will pair up with other electrons. You'll get pairs of electrons.
Speaker 1: They have a state that's called spin, and each electron
Speaker 1: in a pair has the opposite spin of its partner,
Speaker 1: So we can describe spin as up or down. For example,
Speaker 1: if one electron is spinning up, the other one by necessity,
Speaker 1: has to be spinning down. You cannot get both electrons
Speaker 1: in a pair to spin in the same direction in
Speaker 1: the same orbital That just that ain't cricket. It's part
Speaker 1: of a quantum mechanical principle we call the poly exclusion principle.
Speaker 1: And until I did research for the show, I could
Speaker 1: have sworn that referred to the practice of not inviting
Speaker 1: poly shore to your parties. So I guess you learned
Speaker 1: something new every day. That got a smirk from Dylan.
Speaker 1: It's maybe he'll laugh when he listens to it the
Speaker 1: second time. Some elements have an unpaired electron in an
Speaker 1: orbital just because that's just how it works out. So
Speaker 1: those unpaired spinning electrons generate a very tiny magnetic field,
Speaker 1: and we call it an orbital magnetic moment, which sounds
Speaker 1: like something you'd expect in a romantic science fiction film. Iron,
Speaker 1: for example, has four unpaired electrons that all have the
Speaker 1: same spin. Those four unpaired electrons have an orbital magnetic moment.
Speaker 1: So magnetic moment has a magnitude and a direction, which
Speaker 1: means it is a vector. The bottom line is this
Speaker 1: vector refers to the strength of the magnetic field and
Speaker 1: the torque it can exert. So a permanent magnets magnetic
Speaker 1: moments are composed of all the moments of its atoms.
Speaker 1: In other words, we've got all these atoms that represent
Speaker 1: an orbital magnetic moment because of the spin of the
Speaker 1: electrons of the unpaired electrons.
Speaker 2: If you've got enough of them.
Speaker 1: And they're aligned the right way, that determines the permanent
Speaker 1: magnets magnetic moments. So iron and several other magnetic elements
Speaker 1: have a crystalline structure, right, So think of it like scaffolding.
Speaker 1: It makes this very ordered kind of structure as opposed
Speaker 1: to something that looks much more chaotic. So as iron
Speaker 1: cools from a molten state, atoms line up into this
Speaker 1: crystalline arrangement. And groups of atoms that have a parallel
Speaker 1: orbital spin will line up within the crystal, and those
Speaker 1: form those magnetic domains I mentioned earlier. The qualities that
Speaker 1: make good magnets are also the same ones as the
Speaker 1: qualities that make materials attracted to magnets.
Speaker 2: So a strong.
Speaker 1: Magnet will attract iron and other elements that have these
Speaker 1: orbital magnetic moments in alignment. Now, not all permanent magnets
Speaker 1: are equal. The ceramic magnets you may have on your
Speaker 1: fringe door are pretty weak all things considered. They're made
Speaker 1: of a mixture of iron oxide and a ceramic composite.
Speaker 1: These are feric magnets. That's what we call them, feric
Speaker 1: for the iron that's in them. But on the other
Speaker 1: end of the scale are neodymium magnets, a rare earth
Speaker 1: element magnet does much much, much stronger than the feric
Speaker 1: magnets we tend to use, and they typically contain a
Speaker 1: mixture of neodymium, iron and boron. They could be really
Speaker 1: strong too. I have played with some where if they
Speaker 1: get into contact with something like a metal table, it
Speaker 1: can be really hard to remove them. We had some
Speaker 1: here at How Stuff Works that were potentially causing injuries.
Speaker 1: One person slipped one in their pocket and then found
Speaker 1: themselves stuck to a filing cabinet for a little bit.
Speaker 2: This was way back in the day, but.
Speaker 1: It was one of those things where a lot of
Speaker 1: us didn't have a whole lot of experience with it
Speaker 1: because at the time they were fairly uncommon. Today you
Speaker 1: can order neodymium and other rare earth magnets online without
Speaker 1: much trouble. But when I started, first of all, how
Speaker 1: stuff works was easy because there were only three things,
Speaker 1: so it was easy to explain how stuff works. Once
Speaker 1: you wrote the three articles, you were done.
Speaker 2: But over time more stuff.
Speaker 1: Was made and we had more work to do, and
Speaker 1: at that point it was more.
Speaker 2: It was more.
Speaker 1: Well, it was easier to get hold of neodymium magnets
Speaker 1: at that point. Now some materials are called temporary or
Speaker 1: soft magnets, and those will produce a magnetic field in
Speaker 1: the presence of another magnetic field and retain some of
Speaker 1: that magnetism for a while after they leave the field itself,
Speaker 1: so they're very easy to influence. So imagine that you've
Speaker 1: got something like a paper clip and you put it
Speaker 1: within the range of a magnetic field for a while
Speaker 1: and it starts to have its magnetic domains aligned according
Speaker 1: to this magnetic field. You remove it and you find
Speaker 1: you can pick up other paper clips with it, but
Speaker 1: only for a little while, and.
Speaker 2: Then it stops working.
Speaker 1: That's very typical with soft or temporary magnets. They very
Speaker 1: quickly will change, but then they will overtime change back
Speaker 1: to being, let you know, not magnetic, but they're also
Speaker 1: hard magnetic materials. These it's harder to change them, but
Speaker 1: then they will stay changed for longer. So stuff like iron,
Speaker 1: if you're able to really realign those magnetic domains and
Speaker 1: iron magnet will hold that magnetic ability much much longer.
Speaker 1: And that's how you can end up with permanent magnets
Speaker 1: as opposed to some that will just temporarily be magnetic.
Speaker 2: It's kind of interesting.
Speaker 1: So then you've got electromagnets and this will only produce
Speaker 1: the magnetic field in the presence of electricity. And I'm
Speaker 1: sure everyone listening to this has done some variation on
Speaker 1: the experiment where you take an iron nail and you
Speaker 1: coil some wire around it, usually some insulated copper wire
Speaker 1: around the nail several times, and then you run an
Speaker 1: electric current through the wire and you create an electromagnet.
Speaker 1: The nail becomes magnetic and you can pick up all sorts.
Speaker 2: Of stuff with it.
Speaker 1: The strength of the magnetic field is dependent upon the
Speaker 1: number of coils around the nail, as well as some
Speaker 1: other factors, but that's the primary one. And you know,
Speaker 1: it's a cool, little basic science experiment you can run,
Speaker 1: but it's also the basis of a ton of the
Speaker 1: work done in electrical fields, including general electronics, computers, storage.
Speaker 1: It is an important fundamental piece of technology, and the
Speaker 1: very simple applications of this you can find in stuff
Speaker 1: like electric transformers or electric motors and dynamos. Like transformer,
Speaker 1: you can have two different coils of wire, one that
Speaker 1: is got a lot more coils to it, like maybe
Speaker 1: twice as many as the second one, and when you
Speaker 1: run a current through the larger number of coils, the
Speaker 1: magnetic field it generates induces electricity to flow through the
Speaker 1: second set of coils, but it steps down the voltage
Speaker 1: because you have half as many coils around a core
Speaker 1: as you do with the first one. That's how you
Speaker 1: can step down or step up voltage, and that's why
Speaker 1: alternating current ends up being much more effective for distributing
Speaker 1: electricity across long distances than direct current, because.
Speaker 2: You can't do that with direct current.
Speaker 1: You need that alternating electric current in order to create
Speaker 1: the magnetic field that will induce electricity to flow through
Speaker 1: a separate set of coils. Just like you need a
Speaker 1: varying magnetic field to induce electricity, you need that varying
Speaker 1: electricity to produce a varying magnetic field. It's this interesting relationship,
Speaker 1: a fundamental relationship in our universe, between electricity and magnetism.
Speaker 1: And that's why I was saying before. If you have
Speaker 1: a permanent magnet and you just put it next to
Speaker 1: a coil of wire, it's not going to induce electricity
Speaker 1: to flow apart from when you first introduce the magnetic
Speaker 1: field to the coil, because it's not varying. You'd have
Speaker 1: to spin the permanent magnet, which would you know, effectively,
Speaker 1: according to the coil's perspective, change the alignment of that
Speaker 1: magnetic field that would induce electricity to flow through the wire.
Speaker 1: But just having a standard magnet staying perfectly still next
Speaker 1: to wire, you don't get the electricity to flow that way.
Speaker 1: And that is a very important aspect to memory storage
Speaker 1: as well. And that's our lesson on the physics of
Speaker 1: magnets without diving too deeply into quantum mechanics. I think
Speaker 1: we're ready to talk about our use of magnets with electronics,
Speaker 1: but first let's take a quick break to thank our sponsor.
Speaker 1: All Right, we're back, and we just learned how magnets
Speaker 1: work in general, But when did we figure out they
Speaker 1: could be useful for storing information? So I'm going to
Speaker 1: skip over all the historic uses of magnets leading up
Speaker 1: to data storage because I cannot spend another hour talking
Speaker 1: about compasses, or ironically, i'll lose Dylan here in the studio.
Speaker 1: So in the late nineteenth century we saw a boom
Speaker 1: in innovation that was mid to late nineteenth century was
Speaker 1: a crazy time in the world really for inventors discovering
Speaker 1: not just fundamental principles of science, but how to apply
Speaker 1: them in technology. I'm talking about stuff like Samuel Moore
Speaker 1: successfully sending an electrical signal that could be decoded into communication,
Speaker 1: all the way up to Alexander Graham Bell showing that
Speaker 1: electricity could also be used to carry audio signals and
Speaker 1: then be converted from electricity back into audio signals. That
Speaker 1: really got things moving. And over at Thomas Edison's Menlo Park,
Speaker 1: a guy named Oberlin Smith got a gander at a
Speaker 1: cylinder phonograph and got some interesting ideas. So first let's
Speaker 1: talk about this cylinder phonograph. It would record sound by
Speaker 1: transforming audio waves into electrical signals. That would then cause
Speaker 1: a needle to etch grooves into a wax cylinder. So
Speaker 1: you've got this wax cylinder. It would slowly spin and
Speaker 1: a needle would be dragged across it, and as sound
Speaker 1: came in, it would cause the needle to wiggle around,
Speaker 1: and that caused variations in the etching on the wax
Speaker 1: cylinder itself.
Speaker 2: Now, when you took that cylinder.
Speaker 1: Out and you put it in another phonograph and you
Speaker 1: placed a needle on it within the groove, and he
Speaker 1: started to earn the cylinder, the needle would start to
Speaker 1: shake because it's following the groove that was made by
Speaker 1: the previous recording. Essentially, that whole process would be reversed.
Speaker 1: The shaky needle would generate an electrical s which would
Speaker 1: then go to a essentially a speaker a diaphragm and
Speaker 1: cause it to vibrate and that would generate the sound,
Speaker 1: so you would get a replica of the sound you
Speaker 1: made when you were speaking into the wax cylinder phonograph. Now,
Speaker 1: Oberlin Smith wondered if he might be able to do
Speaker 1: the same thing, only instead of using a wax cylinder,
Speaker 1: he would record sound onto magnetic wire, not tape, not
Speaker 1: a disc, but an actual length of wire using magnetism. Now,
Speaker 1: he was not successful in this attempt, but he published
Speaker 1: his ideas in a journal called Electrical World in eighteen
Speaker 1: eighty eight, and ten years later a Dutch inventor inventor
Speaker 1: named Valdemar Pulsen gave it another go. He began a
Speaker 1: working magnet recorder. He started building it. He called it
Speaker 1: the telegraphone Pulson, and he filed the patent for this
Speaker 1: invention in eighteen ninety nine. So one year after he
Speaker 1: started working on it, he showed it off at the
Speaker 1: nineteen hundred Paris Exhibition. So how did it work? What
Speaker 1: exactly was it doing? How was it preserving this audio
Speaker 1: information in a magnetic format so that it could be
Speaker 1: played back?
Speaker 2: Well, Poulson knew.
Speaker 1: That he needed a magnetically hard material. If you remember
Speaker 1: what I was talking about, before the break. That's a
Speaker 1: material that will retain its magnetic moment indefinitely. It may
Speaker 1: very gradually revert back to its original status, but it'll
Speaker 1: hold it over a great deal of time. And if
Speaker 1: you want to record data for later retrieval, obviously you
Speaker 1: want to make sure that that data remains intact. Otherwise
Speaker 1: you have a self destructing or at least a self
Speaker 1: erasing message on your hands. So Paulson had to experiment
Speaker 1: with various factors to make certain he could record anything
Speaker 1: to the medium. To begin with, if the medium has
Speaker 1: a coercivity factor that's very high, that means you have
Speaker 1: to use stronger magnetic fields.
Speaker 2: To affect it.
Speaker 1: I'll al ways talk about magnetic fields now. I'm thinking
Speaker 1: about the Book of Love, this great song by a
Speaker 1: group called the Magnetic Fields.
Speaker 2: Back to this.
Speaker 1: So you have to have a really strong magnetic field
Speaker 1: in order to affect that material, and that can be difficult.
Speaker 1: It can start to eat in on your efficiency. And
Speaker 1: you need the magnetic information to be distinct enough so
Speaker 1: that you could get a good replay signal. And you know,
Speaker 1: when you're reading the material back later, you want to
Speaker 1: make sure you can actually hear what was recorded and
Speaker 1: not just get some sort of muffled, you know, simulation.
Speaker 2: Of the sounds you made.
Speaker 1: So to record information onto a wire, you first need
Speaker 1: a recording head. You need something that's going to generate
Speaker 1: a magnetic flux that can affect.
Speaker 2: The medium you're using, the wire in this case.
Speaker 1: This, by the way, is also true for other methods
Speaker 1: of magnetic storage, including cassette tape, VHS tapes, floppy disks,
Speaker 1: and some hard drives. When I say some hard drives,
Speaker 1: I mean magnetic hard drives.
Speaker 2: Obviously, there are.
Speaker 1: Solid state hard drives that are not affected in this way.
Speaker 1: They don't use that technology. They are not part of
Speaker 1: this discussion. So the recording head is a transducer, and
Speaker 1: basically a transducer is something that converts some physical quantity
Speaker 1: into an electrical signal, or does the reverse. So you
Speaker 1: might have a transducer that can measure pressure, like air
Speaker 1: pressure and change that into an electrical signal. That's a transducer.
Speaker 1: But in this case we're talking about things like a
Speaker 1: microphone a transducer, and a microphone converts pressure from sound
Speaker 1: waves into electrical signals. With recording devices, you can use
Speaker 1: one transducer to pull double duty one of them. It
Speaker 1: can act as both a recording head when recording, so
Speaker 1: it's actually writing something to the storage medium, or it
Speaker 1: could be a read head when playing a signal back
Speaker 1: it's reading the signal and then converting it back into
Speaker 1: whatever it was originally before it was stored in that format.
Speaker 1: Now these days, most recording devices still use that are
Speaker 1: still using magnetic storage have a dedicated recording head and
Speaker 1: a dedicated read head so that each transducer can be
Speaker 1: optimized for its respective role.
Speaker 2: You don't see a.
Speaker 1: Whole lot of them where it's doing both things. Some
Speaker 1: very cheap electronics, probably because then you don't have to
Speaker 1: have as many components in it makes it less expensive
Speaker 1: to produce. Now, the right head's job, or the recording
Speaker 1: head if you prefer, is to convert electric current into
Speaker 1: a magnetic field. But you remember what we said about electromagnets,
Speaker 1: that's pretty easy to do. The field it generates needs
Speaker 1: to be strong enough to affect the storage medium the wire,
Speaker 1: but also it has to fall off quickly as you
Speaker 1: move away from the recording head. In other words, you
Speaker 1: don't want the effect to be wide spread in area,
Speaker 1: or else you're going to end up affecting way too
Speaker 1: much wire at once, you'll end up with having to
Speaker 1: use way more wire to record very short sounds in
Speaker 1: this case, and not only is that inefficient, but you'd
Speaker 1: also run the risk of writing over stuff you've just recorded.
Speaker 1: Let's say that you're writing something to wire. If the
Speaker 1: magnetic field is wide enough so that it's constantly overlapping
Speaker 1: what you just recorded, then all you're really doing is
Speaker 1: muddling your recording with every successive sound. So a coil
Speaker 1: of wire creates the magnetic field when electricity runs through it.
Speaker 1: This wire is coiled around a soft magnetic material. Remember
Speaker 1: those are the kinds of magnetic materials that are easy
Speaker 1: to influence, but then will go back to their natural
Speaker 1: state shortly after the magnetic field they've been exposed to
Speaker 1: has gone away. This creates what we call a magnetic flux,
Speaker 1: and it concentrates at the tip of the soft magnetic
Speaker 1: material that's the core of this coil. A common design
Speaker 1: for early recording heads was a ring that had a
Speaker 1: small gap cut into it, and then you would wrap
Speaker 1: the wire around the inside of this ring, like you know,
Speaker 1: around the ring. So imagine just a regular ring. You
Speaker 1: cut a little gap at one end. On the other end,
Speaker 1: you've wrapped this this coil of wire and you run
Speaker 1: electricity through it. It turns the ring into a magnet.
Speaker 1: But the gap creates a difference in this magnetic field.
Speaker 1: The soft material, the soft magnetic material, conducts magnetic flux
Speaker 1: easily and the gap doesn't. This causes the magnetic flux
Speaker 1: to do something we call fringing. It fringes. A fringe
Speaker 1: field is a bit tricky to explain, but it's easier
Speaker 1: to understand if you imagine a horseshoe magnet. So the
Speaker 1: two ends of the horseshoe are the two poles, the
Speaker 1: north pole and the south pole. The fringe field is
Speaker 1: the magnetic field that extends outside the space between the
Speaker 1: two poles. That would be a fringe field. Now, that
Speaker 1: fringe field is what the right head uses to actually
Speaker 1: record information onto the magnetic medium. Now, with sound, we're
Speaker 1: talking about an analog approach, meaning you'd find a smooth
Speaker 1: variability in the medium. You would create that by varying
Speaker 1: the magnetic flux in subtle ways. The recording head adjusts
Speaker 1: the magnetic flux by varying the current running through the
Speaker 1: head and the recording medium thus has a variability in
Speaker 1: the magnetic flux recorded within the wire itself. The wire
Speaker 1: represents a sort of copy of the flux if you
Speaker 1: were to run the wire back. So let's say you've
Speaker 1: got the red head, the transducer that acts as a redhead,
Speaker 1: and you run the wire next to it sequentially, so
Speaker 1: you're just spinning one reel pulling wire across so that
Speaker 1: this redhead is very close to it. That would create
Speaker 1: a varying magnetic field across the gap in the red head,
Speaker 1: and that then would create a varying magnetic field in
Speaker 1: the core of the red head, which would induce a
Speaker 1: current to flow through the coil of wire, which then
Speaker 1: could be sent to an amplifier. The varying electric electrical
Speaker 1: signal goes to a transducer such as speakers, and then
Speaker 1: it can play back the sound. Now, those old wire
Speaker 1: recorders moved at a pretty good clip.
Speaker 2: The post war.
Speaker 1: Wire recorders would play back wire at about twenty four
Speaker 1: inches per second, so two feet of wire per second.
Speaker 1: That's about sixty one centimeters per second for you folks
Speaker 1: on the metric system, if you wanted to record an
Speaker 1: hour's worth of audio, you would need seven two hundred
Speaker 1: feet of wire or about two thy one hundred and
Speaker 1: ninety five meters of wire, and you could only record
Speaker 1: along one direction of the wire, so if you wanted
Speaker 1: to listen to it again, you'd have to wind all
Speaker 1: the wire back up up into a reel and then
Speaker 1: play it out across a redhead all over again. Most
Speaker 1: of these early ones were hand cranked too, so you
Speaker 1: would get variability on the sound quality as it was
Speaker 1: played back, plus when you were recording, so it took
Speaker 1: a steady hand to create a decent recording and a
Speaker 1: decent replication. And if you wanted to re record over it,
Speaker 1: Let's say that you've you know, you recorded an hour
Speaker 1: of someone catterwaulling, and then you're like, well, that wasn't
Speaker 1: really worth it. I would love to use this wire
Speaker 1: to record something else. You would first have to run
Speaker 1: that wire by a strong permanent magnet, and that would
Speaker 1: effectively erase the stuff that was on it before, because
Speaker 1: the strong permanent magnet would cause all those those those
Speaker 1: magnetic domains inside the wire to realign to the permanent
Speaker 1: magnet's magnetic field. It essentially erases all the variability, all
Speaker 1: the flux that was copied there before and turns it
Speaker 1: back into a uniform medium which you then could run
Speaker 1: through and record stuff on again. The same thing, by
Speaker 1: the way, is true for lots of other magnetic storage media.
Speaker 2: Now.
Speaker 1: Eventually Polson began to work with other types of magnetic media,
Speaker 1: and a big breakthrough came with the invention of plastic.
Speaker 1: I say the invention of I really mean the mass
Speaker 1: production of plastic's been around for a pretty long time,
Speaker 1: but I'm talking about when we really started producing it
Speaker 1: on a mass scale.
Speaker 2: So you can use.
Speaker 1: Plastic film coated with a ferro magnetic powder. This is
Speaker 1: how cassette tapes, VHS tapes, even floppy disks work. You
Speaker 1: can make a cheap recording medium this way. The invention
Speaker 1: of the cassette tape itself was another big jump, because
Speaker 1: engineers figured out how you could double the amount of
Speaker 1: material you could record on a tape if you just
Speaker 1: record it on half of it at a time. Now,
Speaker 1: this is a little triggy to explain without the use
Speaker 1: of visual aids, but I'll try and give it a shot.
Speaker 1: So imagine that you've got a length of flat ribbon
Speaker 1: in front of you. You might think of cassette that
Speaker 1: cassette recorders are actually putting information on both sides of
Speaker 1: the ribbon, but that's not what is happening. All the
Speaker 1: information for Side A and Side B are on one
Speaker 1: side of that ribbon, but they are one hundred and
Speaker 1: eighty degrees opposite each other, side by side. So you
Speaker 1: lay out the ribbon so it's horizontal in relation to you.
Speaker 1: You're looking at a horizontal strip of ribbon. Imagine a
Speaker 1: line going down the middle of that ribbon horizontally. The
Speaker 1: top half of the ribbon is one side of the
Speaker 1: cassette and the bottom half is the other side of
Speaker 1: the cassette. So when you put a cassette into a
Speaker 1: cassette player, the red head is positioned over just one
Speaker 1: half of that tape and it reads what's off of that.
Speaker 1: When you flip the cassette over, then and the side
Speaker 1: of the tape that's running across the redhead is the
Speaker 1: opposite of that. You know, it's the bottom of the
Speaker 1: ribbon as opposed to the top of the ribbon, and
Speaker 1: that's how you're able to listen to Side B. We're
Speaker 1: going to take another quick break and then we'll be
Speaker 1: back to talk more about magnetic storage. So while the
Speaker 1: format is more or less obsolete. I'm gonna talk about
Speaker 1: floppy disks for a bit, and that's because there are
Speaker 1: a lot of parallels between floppy disks and cassette tapes,
Speaker 1: which I talked about in the last section. Floppy discs,
Speaker 1: by the way, used to come in several sizes. When
Speaker 1: I first started using computers, the standard size and the
Speaker 1: US was the five and a quarter inch disc. There
Speaker 1: were larger discs that came before that, but the first
Speaker 1: ones I ever used were five and a quarter inch.
Speaker 1: A lot of people thought they were called floppy disks
Speaker 1: because the outer sheath of the disc itself was flexible.
Speaker 1: Some people even thought you could fold them up and
Speaker 1: put them in your pocket, which technically I guess you
Speaker 1: could do, but you wouldn't be able to use them
Speaker 1: later because you'd mangle the disk inside and it would
Speaker 1: no longer spend properly inside a computer, So don't do that.
Speaker 1: Later on came the three and a half inch discs,
Speaker 1: and these had a hard plastic casing, but they were
Speaker 1: still floppy disks because the disk inside, the actual medium
Speaker 1: upon which information was stored, was still this flexible material.
Speaker 1: A lot of folks thought that these three and a
Speaker 1: half inch discs were actually hard disks. They said, you know,
Speaker 1: the floppy disks wereth the five and a quarter three
Speaker 1: and a half because the plastic is sturdy, that's a
Speaker 1: hard disk. No, that's not a hard disk. But anyway,
Speaker 1: that's all ancient history, and you guys probably don't even
Speaker 1: understand what I'm talking about, so get off my lawn,
Speaker 1: all right. Inside the outer covering of these disks was
Speaker 1: the actual disc itself.
Speaker 2: We call the floppy.
Speaker 1: Disks that, but they're not disc shaped. If you were
Speaker 1: to show someone a floppy disk and they had absolutely
Speaker 1: no context for it, they knew what the word disc meant,
Speaker 1: they'd take one look at it and.
Speaker 2: Say, why the heck do you call it a disc.
Speaker 2: It's because on the inside.
Speaker 1: There is a disc of material and it is essentially
Speaker 1: a plastic base that's coded with ferromagnetic materials. And the
Speaker 1: advantage of this is that if you apply a magnetic
Speaker 1: field to it, it would record the information permanently, or
Speaker 1: at least until you erased it and wrote over it,
Speaker 1: or if you encountered a really strong magnetic field, and
Speaker 1: it was a really fast way to record a lot
Speaker 1: of information. So discs are organized into concentric rings. You
Speaker 1: can kind of think of an old vinyl album in
Speaker 1: the same way how the grooves slowly move inward on the.
Speaker 2: Disc.
Speaker 1: But in this case they're actual concentric rings of information,
Speaker 1: not just one line that slowly, you know, swirls inward
Speaker 1: towards the center. So when a computer is reading information back,
Speaker 1: it can it can reference some information at the at
Speaker 1: the front of the disc and learn exactly where a
Speaker 1: file is located, and it can then position the read
Speaker 1: right head directly over the appropriate part of the disc,
Speaker 1: rather than having to go through.
Speaker 2: The whole thing sequentially.
Speaker 1: So with a cassette tape, if you want to listen
Speaker 1: to a specific song, you have to wait. I mean,
Speaker 1: you can use fast forward to speed things up, but
Speaker 1: you can't jump straight to the track you want to
Speaker 1: hear onlike you could with say a compact disc. Well,
Speaker 1: in this way, a floppy disk is more like a
Speaker 1: compact disc in that a computer can understand exactly where
Speaker 1: the file is stored within those concentric rings and go
Speaker 1: straight there. In other ways, it is very different from
Speaker 1: a compact disc, but in that specific way it is similar. Now,
Speaker 1: in other words, it's kind of lifting a record player's
Speaker 1: needle off of one groove and skipping ahead to a
Speaker 1: specific song on an album, lowering the needle and then
Speaker 1: playing it, and thank goodness, record players are coming back.
Speaker 1: So that you guys know what I'm talking about when
Speaker 1: I say these things. This, by the way, is a
Speaker 1: type of direct access storage, meaning the computer can get
Speaker 1: direct access to that information in a very short amount
Speaker 1: of time. When writing to a disc, first the drive
Speaker 1: will use an erase coil, and this essentially just clears
Speaker 1: a section of the storage medium for writing. So it's
Speaker 1: kind of like exposing that steel wired to a permanent magnet.
Speaker 1: It's that same principle. You want a clean slate to
Speaker 1: write upon, and typically this clean slate is a bit
Speaker 1: wider than the actual right section you're going to be
Speaker 1: working on. You want the area that is a clean
Speaker 1: slate to be larger so that you have a buffer
Speaker 1: zone at either end, and that way it keeps adjacent
Speaker 1: files from interfering with each other. If you were writing
Speaker 1: information to that part of the disc and it went
Speaker 1: over that area, you would start writing on top of
Speaker 1: some other file and then the storage wouldn't work at all.
Speaker 1: So the right head puts data on the disk drive.
Speaker 1: By applying one of two magnetic fields to the tape,
Speaker 1: it either aligns the magnetic material as north south or
Speaker 1: south north. That means it's either a zero or a one.
Speaker 1: So imagine that north south magnetization represents as zero and
Speaker 1: south north represents a one. The right head can then
Speaker 1: go through this disc very very quickly, applying these magnetic
Speaker 1: fields one after the other, maybe several north south in
Speaker 1: a row, followed by a south north or whatever, and
Speaker 1: it is recorded on the disc itself, and when you
Speaker 1: read it back then you know by looking at the code, oh,
Speaker 1: these are three zeros in a row and then a one.
Speaker 1: It replicates those zeros and ones that were recorded to
Speaker 1: the storage medium. This, in a way is much more
Speaker 1: simple than a variable magnetic flux because you only have
Speaker 1: to have two magnetic states. You just have to have
Speaker 1: something that represents a zero and something that represents a one.
Speaker 1: No other values are accepted, so you just have to
Speaker 1: have those two basic modes, and the same basic principles
Speaker 1: apply to other computer magnetic storage. Magnetic hard drives use
Speaker 1: a very similar approach to the ones I describe for
Speaker 1: floppy drives. And you probably heard that it's a bad
Speaker 1: idea to expose computers to strong magnetic fields. And the
Speaker 1: big reason for this is that magnetic storage. If you
Speaker 1: bring a strong permanent magnet close enough to magnetic storage media,
Speaker 1: you'll erase the data that's stored there. That includes data
Speaker 1: that's on a hard drive if it's a magnetic drive, right,
Speaker 1: If it's a solid state drive, it's a different story.
Speaker 1: Or if you were to take a strong permanent magnet
Speaker 1: and threatening someone by holding a compact disc with all
Speaker 1: their photos on it, and you're saying, if you come
Speaker 1: any closer, I'm going to ruin your pictures by putting
Speaker 1: this magnet up to the CD, it won't work because
Speaker 1: the information stored on the CD is an optical format,
Speaker 1: not magnetic, and magnets aren't going to affect it at all.
Speaker 1: That's it for that classic episode how magnetic storage works.
Speaker 1: I hope you enjoyed it.
Speaker 2: Clearly still a thing.
Speaker 1: We still use magnetic storage and lots of different applications.
Speaker 1: But yeah, it's not uncommon to find machines that only
Speaker 1: have solid state drives these days and not a magnetic
Speaker 1: storage drive. But yes, very important in the history of
Speaker 1: computers and data storage. If we're being honest.
Speaker 2: I hope you.
Speaker 1: Enjoyed that episode. Hope you're all well, and I'll talk
Speaker 1: to you again.
Speaker 2: Release It.
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