Science Question From a Toddler: The magnet conundrum

Sometimes, silly questions can teach us fascinating things. Each month, BoingBoing science editor Maggie Koerth-Baker takes one query submitted by a child (or former child) and finds the eye-opening science behind seemingly simple questions.

It seems that we all owe the Insane Clown Posse a bit of an apology.

Last year, we, the Internet, watched the music video for the song "Miracles" and had a good, hearty chuckle. Here were two grown-ass* men wearing white sweatsuits and clown makeup, frolicking beneath poorly CGI'd rainbows as they philosophized about the miraculous nature of things that were, really, not especially miraculous. The fact that Shaggy 2 Dope's kids look like him is not an inexplicable act of God, it's genetics. The existence of rainbows is a wonder of optics, not an unknowable mystery.

The song was a lot less twitch-inducing once you understood that the Insane Clown Posse didn't literally think pet cats and dogs were miracles. In reality, they were simply trying to convey excitement about the awesomeness of the Universe—something I can get behind, even if I, personally, think that scientific explanations only add to that awesomeness, rather than detract from it.

But that's not what the apology is for. Instead, it all comes back to the most famous line in the "Miracles" song. Say it with me now, "Fucking magnets, how do they work?"

Oh, sure, it sounds ignorant on the surface. After all, didn't we all learn about magnets in, like, third grade? But you have to think about the specific question. The Insane Clown Posse didn't ask, "What are magnets?" or "What do magnets do?" If most of us are honest with ourselves, we'll admit we're every bit as mystified by the inner workings of magnets as the Insane Clown Posse. When I put out a call for Science Question From a Toddler submissions, no fewer than five different people emailed me, asking, essentially, "No, seriously. Fucking magnets. How do they work?"

This "ignorant" question turns out to have one hell of a complicated answer.

For every natural phenomenon there are different levels of explanation. I like to call these "why" values. For the first value of why, the question "Why is the sky blue?" can be answered with some simple hand-waving about light from the sun passing through our planet's atmosphere. For a value of why + 2 (also known to parents as, "But whyyyyy?") you have to start talking about the fact that light comes in different colors. The further you go, the more complicated the answer becomes.

No matter what question you're asking, there is almost always a point—why + n—where the explanation starts to dive into some seriously heavy physics. Some questions take a while to reach that point. Some get there distressingly fast.

"Fucking magnets, how do they work?" turns out to be one of those questions that hits physics at the first value of why.

"I remember being in Electricity and Magnetism class at college, when we were talking about ferromagnetism," says Joel Bonasera, Program Specialist at Discovery Place museum in Charlotte, North Carolina. "We could only go so far before the professor said, "And the rest of this is really weird and you'll study it in quantum mechanics. Moving on..."

Bonasera, who has a BS in physics and designs physics education exhibits for Discovery Place, was instrumental in helping me delve into the amazing world of magnetism. As was University of Minnesota physics professor Jim Kakalios. Both agreed—magnets are not simple things. There's no shame in not quite getting why two pieces of magnetized metal attract or repel one another.

To understand it, you have to start with electrons.

Everything that ever existed—from a giraffe, to a magnet, to the Insane Clown Posse—is made up of atoms. This is the basic unit of matter, and it's so tiny that you can't see it without some very specialized equipment. But that tiny atom is made up of even smaller things. At its heart is a ball of particles called the nucleus, which contains protons and neutrons—the protons have a positive electric charge, while the neutrons, appropriately, have no charge.

Meanwhile, outside the nucleus, are the negatively-charged electrons.

It's useful to imagine the atom as something like the carousel at the county fair. Just like the carousel has a central pipe organ that has ponies constantly spinning around it, the atom has a central nucleus with electrons going round and round it. This analogy isn't accurate. But it's what physicists call a "useful fiction"—an easy way to wrap your head around a concept that is totally different from anything we experience in our everyday lives. There are a lot of useful fictions involved in talking about the particles that make up an atom. Case in point: Spinning electrons.

As they circle around the nucleus, each electron also spins on its own axis—so, maybe the atom is less like a carousel, and more like a spinning teacup ride. Again, this is a useful fiction. Bonasera and Kakalios are careful to point out that electrons do not actually spin like a top. But just like each electron has a mass and a negative electric charge, they each have another property, as well. One that's very, very difficult to describe.

Electrons possess an intrinsic angular momentum, independent of any orbit around a nucleus. Physicists call that momentum "spin", in that the electron's internal rotation can be clockwise, or counter-clockwise. But, when they do that, they're really just using familiar words, and familiar mental images, to talk about something completely unfamiliar.

All of this is important because electron spin is central to explaining how those fucking magnets work.

Because electrons spin—because they have this hard-to-describe property that we call "spin"—each electron produces a small magnetic field. In fact, Kakalios told me that, originally, some physicists had thought that electrons might, literally, spin. They thought that because they knew that if you took something with an electric charge—like the electron has—and spun it fast enough, it would create a magnetic field. That literal interpretation doesn't work. To produce their observed magnetic field by actually spinning, each electron would have to turn on its axis faster than the speed of light. But it helps you understand the concept: Electrons produce a magnetic field because they spin.

Every atom has electrons, so every atom has a magnetic field. But why, then, are only some materials magnetic? Why doesn't your couch repel other couches? Why can't we stick two cats together?

In cats, couches—all the everyday things that aren't magnetic—the magnetic fields produced by electrons simply cancel each other out. For every electron that's spinning clockwise, there's another electron spinning counterclockwise. All electrons produce magnetic fields, even the ones in cats and couches. But cats and couches aren't magnetic because their electrons' magnetic fields interfere with one another and keep the overall magnetic force so weak as to be nonexistent.

Magnets are different.

In a piece of iron, most of the electrons still cancel each other out—there's a clockwise spinner for every counterclockwise spinner. But, there are also a few stragglers, electrons which have no opposite-spin partner. Their magnetic fields don't get counteracted. When we see two pieces of iron stick together, or repel one another, we're seeing the work of those straggler electrons.

Remember back in third grade, when you learned about what magnets do, and you were able to magnetize a nail by rubbing a bar magnet against it? That's the stragglers again. See, all the un-partnered electrons in a single piece of iron aren't necessarily working together. In that nail, the stragglers are like squabbling city-states, Joel Bonasera says. Those city-states are called "domains". But domains easily fall into line behind a strong leader. So, when you rub the bar magnet over the nail, the straggler electrons in the nail all snap to attention. Their magnetic fields line up with the magnetic fields in the electrons of the magnet. Now, the nail doesn't just have a lot of tiny, disconnected magnetic field domains. It has one, unified magnetic field. It becomes a magnet that we can see on the macro level.

And that's how magnets work, to the first value of why. It's fascinating, it's mind-boggling, and, as Jim Kakalios put it, "Insofar as the entire Universe is a 'miracle', this is, too."

*I honestly could not figure out how to write about this question without dropping the F bomb. Because, really. I'm not going to censor the most oft-repeated song lyric of 2010. So, I figure, in for a penny, in for a pound. While I strive to make most editions of Science Question From a Toddler something that you can read with your kids, this particular story may or may not meet those standards—depending on how your family feels about kids and swear words. But, even if you don't want your 5-year-old asking their teacher about "Fucking magnets", this post should help you formulate your own, curse-free explanation. Just an FYI.

Image: Some rights reserved by Karl Horton

• [Gawain Lavers]

  Why can’t we stick two cats together?

  You should try briskly rubbing them together first.

  • [Nightflyer]

    “Why can’t we stick two cats together?”

    “You should try briskly rubbing them together first.”

    I really don’t think my cats are going to agree to that.

    However, their hair sticks to all my *clothing* just fine. But if I’m not wrong, that’s cling due to static electricity, *not* magnetism, which is a whole other f*cking topic. Magnetism is enough to ponder for one day, IMHO.

• [Anonymous]

  This site explains “spin” theory, complete with pictures:
  http://ibrahimgedik.com/14onthermt.htm

  If you want a perfect explanation of magnetism, you’ll have to cover a lot of physics. Here is a link to a chart showing particles described by the Standard Model of particle physics:
  http://bccp.lbl.gov/Academy/workshop08/08%20PDFs/chart_2006_4.jpg

  Protons and Neutrons are types of baryons. Electric charge comes from combinations of quarks. The smallest of the familiar sub-atomic particles, the Electron, is a type of Lepton. Technically, the photon is also a type of particle (a boson)… but most people don’t think of ‘photons’ when they list sub-atomic particles.

• [Onigorom]

  Why do magnets attract each other?
  The answer, before any science sneaks in, is: Why not?
  We take our fascination for attraction for granted in justifying a ‘why’ question.
  We ask ‘why’ very often only in regard to phenomena that seem to challenge our usual experiences.
  But from a certain point of view, everything can be ‘why-ed’ – even the scientific explanation for magnetism. ‘Why’ as a concept certainly was not invented by scientists. It is not the question of cause and effect, ‘why’ asks for more than that. It is more like: What is the point of it? And causality explains something different. Not the point of it, not the point of attraction, so to speak.

• [Anonymous]

  This is something the western mind simply can’t easily grasp. “Why” just isn’t applicable in some cases. That is how your 3 year old kid beats your grown-ass to pulp in the ‘why’ game.
  Why = “for what”, as if there is a purpose. Gravity isn’t anything to philosophise over, it is the container we live in. We can’t be free from it, *ever*. It is always there, even when you think you are floating in space, Alpha Centauri is pulling on you a little bit too.
  Magetism and the other rules of physics are part of the same container. Finding out more about it doesn’t make it any different. A Brick wall 10 feet away, keeping you inside your yard will still accomplish the same thing after you’ve walked up and “discovered” that it is made up of cinder, and mortar, and gee, look at those wonderful tiny grains of sand in the mortar!
  Not to discount finding out more about these things. Once you get bored in your container, you need to start beating your fists upon and scratching stuff. All this science is just an extension of that.

  • [teufelsdroch]

    Oh fer crissakes. Everything Feynman says should be taken with a very big grain of salt. Einstein didn’t mean that there was a God when he said god doesn’t play dice, and Feynman didn’t mean there was no explanation of magnetism when he clearly got caught unprepared by this journalist’s question.

    Gravity bloody well is something to philosophize over, and ‘because objects move in straight paths in curved space’ is as good as it gets.

    Magnetism occurs when charged particles move. Yeah, okay, Feynman meant that he could describe how electric and magnetic fields were exchangeable, describe how replacing the normal concept of energy (schrodinger) with relativistic energy (dirac) can be approximated as spin, and finally describe the difference between electric and magnetic fields in QED–and the average listener wouldn’t follow.

    But please understand. The point is that the explanation is one that YOU WOULDN’T UNDERSTAND, not one that DOESN’T EXIST.

    • [teufelsdroch]

      Too rude, sorry.

      Feynman acknowledges that any explanation he gave would be a lie-to-children.

      It upsets me when people mistake this for saying that there is no answer.

• [ROSSINDETROIT]

  Metaphors are all useful up to a point. Bulk charge flow in a conductor can be thought of like water for some purposes. But when you ask why a germanium transistor (holds up 2n158) has a different junction voltage than a silicon transistor (holds up a970) the water metaphor won’t give you an answer and you have to be more specific about the characteristics of particles.
  That’s why magnetism can’t be explained in simple language. The concepts represented by common English words are inadequate.

• [DarthVain]

  My question is on “Rare Earth” magnets.

  What are they and why are they and why do they have a so much stronger magnetic force?

  • [Ralph Giles]

    “Rare Earth” elements are those from the Lanthanide series, the upper of the two extra rows you see at the bottom of a periodic table. Neodymium is the most popular one.

    These make for especially strong magnets because the particular crystal structure of the rare-earth alloys makes it possible to lock more of the domains pointing in the same direction than in other materials. In Joel’s metaphor, the “squabbling city states”, once aligned by a strong leader, are especially resistant to post-revolutionary political change.

    Since more of the domains align together, they add up to larger macroscopic magnetic field.

    • [jangusKhan]

      This is great, I lol’ed.

  • [jangusKhan]

    Great question! This is Joel from the article.

    Rare earth magnets are alloys of iron and one of the elements from the “rare earth” group on the periodic table. Most of the time, if you have a rare earth magnet, it is a combination of iron and neodymium, and boron. Some of these rare earth elements make good ferromagnets, but only at temperatures much colder than people usually live at. By combining them with other ferromagnetic elements, they produce extra strong permanent magnets. I guess you can think of it like a “magnetic alloy” that is a stronger magnet than its parts alone.

• [Anonymous]

  Riddle me this: We put magnets in a generator, and then when we spin the shaft, we pull off electricity as the coils cross the lines of magnetic flux. So, why don’t the magnets in a generator get weaker even when I’m pulling 100,000 watts out of my little gennie in the back of my truck?

• [Anonymous]

  If frogs can be magnetised – then so can cats !
  You just need 16 Tesla or so !
  http://www.ru.nl/hfml/research/levitation/diamagnetic/

• [Mike Mol]

  Next questions:

  Why do electrons have spin? What is it about that particular triplet of quarks gives it to them?

  • [jangusKhan]

    Hey, this is Joel from the article.

    Electrons actually aren’t made of quarks. They are leptons, which like quarks are considered “fundamental” particles. String theory posits that electrons and quarks are actually loops of energy vibrating away, but we haven’t proven this yet.

    Spin is a “quantum number”. A value that we assign to particles of different types that helps us distinguish them. Asking “What is spin?” is like asking “what is mass?” My point is that it’s a good, nay, GREAT question, but one that I don’t think I can really give you an answer to.

    What I CAN say, is that we call it spin for a few reasons. Angular momentum is a measurable value related to objects which are spinning in place. Through extensive experimentation, physicists discovered that individual electrons seem to have a specific amount of intrinsic angular momentum. Also, they’ve shown that electrons have a magnetic moment (related to the discussion above) that would be characteristic of a charged object that is spinning around an axis. Unfortunately, calculating how fast the electron would have to be spinning in order to produce the values we find in the lab (based on it’s mass and distinguishable size) produces numbers in excess of the speed of light. This doesn’t mesh with our understanding of relativity, so at this point we just say that it has spin 1/2 and move on. Other particles have spin too: photons are spin 1, neutrons are spin 1/2, quarks are spin 1/2. In fact, we can separate all particles into 2 groups, bosons who have integer spin, and fermions who have spin 1/2.

• [Anonymous]

  BUT WHAT IS SPIN?
  Love, a thirteen year old who understood magnetism until just now.

• [bnprime]

  magnets are fun, but i think that the “how to they work” and “why do they work” questions are different. the “how” question demands an intuitive understanding, while the “why” question demands a first principles approach.

  so i think it just confuses and discourages people when they ask “how do they work” and we physicists start going on about electron spin.

  so, i wrote a post about it explaining how magnets work in terms of awesome fans:

  http://paleocave.sciencesortof.com/2010/11/fcking-magnets-how-do-they-work/

  yeah.

  • [SamSam]

    I think the “awesome fans” approach is an analogy that’s way-too-far-away to particularly help people understand why or how they work. I don’t see what new intuitive understanding kids learn by thinking of magnets as fans.

    It’s saying that this “force” thing that you’re experiencing with magnets is kinda-sorta-similar to the “force” thing you’ve experienced with wind. But that’s no better than explaining that the force you’re experiencing with wind is kinda-like the force you’ve experienced with magnets: it’s circular, and it doesn’t provide any new information or understanding, assuming the person has any experience with magnets.

    I guess if the person has never heard of a magnet, and so don’t know that they attract things, it might be useful in explaining that they do, in fact, attract things.

    The wind analogy fails even at the most trivial experiential level, for instance: you’ve explained why the north poles repel, but why do the south poles repel? According to your analogy, the south poles should suck together extra-tight!

    I think if you want to take that waay-back approach and explain things at an intuitive level, it’s easier just to say it’s a “force,” and then talk about how forces can make things move, kind of like the also-invisible forces of wind and gravity.

• [francoisroux]

  I’m sure someone already said, “But why”, but you have to already have a certain level of understanding of all or many things for that to be the first level of why. If you don’t even know what some of the words mean it’ll be to the power of infinity level of why to you.

  It’s a very good explanation though, probably better than the explanation our science teacher in high school gave us and had us gasping for air after the first 5 minutes…

• [daen]

  Great stuff, Maggie! It’s also rather mind-boggling how the charge of every electron (and every proton, for that matter) is (as far as we know) exactly the same for every one of the little buggers throughout the universe.

• [djfatsostupid]

  I don’t think this explanation really gets at the question that is being asked, though I recognize that the question being asked is probably very difficult. From a lay-person perspective, it sounds a lot like you said that everything is made up of tiny little magnets, and that while most of the time these little magnets cancel each other out, sometimes they work together to make a big magnet. The question, about how magnets work, is equally applicable regardless of the size of the magnet, and a magnet should be understood to be anything that has a magnet field. The answer is, why do these things we call magnets (short for thing with a magnetic field) move closer together or further apart depending on which way we turn them around? It probably isn’t a valid question to ask about electrons, but it is a perfectly valid question to ask about the sort of thing that people imagine electrons to be when you give them metaphors about subatomic particles.

  I guess my question is, does anyone actually know at this point, and is the question of what magnetism actually is (or, why things sometimes move closer to one another and sometimes move away from one another) even a reasonable question to ask given the current state of physics? Presumably in order to answer the question you would have to completely abandon your medium-sized intuitive ideas about what is a “thing”, what “distance” is (what it is to “move” or to be “closer” or “further”) and possible even your concept of “sometimes.” And if that is the case, then is any explanation in actual English going to get better than, “opposite charges attract, like charges repel.”

• [SallyStrange]

  Nice explanation. It is rather mind-boggling.

  I take issue, though, with your characterization of the question as “ignorant.” Asking how magnets work is not ignorant.

  Asking how magnets work, with the expectation that nobody knows the answer, and that that lack of an answer means “goddidit”–that is ignorant.

  • [Ian]

    Surely asking any non-rhetorical question is by definition ignorant? How would one progress from ignorance to knowledge without asking questions?

    [I find it very strange to be speaking about non-rhetorical questions while only using rhetorical questions. My head is beginning to hurt, I think I'll go and have a lie-down before I find myself thinking about recursion and thinking about thinking about recursion.]

• [awjtawjt]

  Nicely done. Can you explain the difference between electromagnets and ferromagnets in real talk?

  • [jangusKhan]

    Yeah! This is Joel from the article.

    Basically, a ferromagnet (ferro = iron) is a permanent magnet that is dependent on the electron interactions mentioned in the article. By getting the domains to line up in the same direction, we can produce a strong magnetic field. The domains tend to reinforce each other and maintain “order” as long as stuff stays relatively undisturbed (heating ferromagnets past the “Curie temperature” of the magnet starts to jostle the domains out of synch).

    An electromagnet is the result of current flowing through a wire. This phenomenon is actually related to another deep truth in physics: electricity and magnetism are basically the same thing; which one you experience depends on your frame of reference. Basically, when electricity moves/flows, it produces a magnetic field. When magnets move or change strength, it produces an electric field. In an electromagnet, the flow of electricity around a coil of wire produces a magnet. In the ferromagnet, the “spin” of the electrons produces a magnet. Either way, we have electron motion producing the field.

    TL;DR – Motion of electrons produces a magnetic field. If you turn off the current/flow, then the magnet turns off too.

  • [GavinD]

    A Ferromagnet refers to a piece of iron that has its own magnetic field for reasons described in the article. That’s pretty cool. But what if you could turn a magnetic field on and off as you saw fit? Now THAT would be cool. That’s where electromagnets come in handy. To make an electromagnet, you don’t need something such as iron that magnetizes easily. All you need is a piece of wire, and a source of electric current. Whenever current passes through the wire, there will be a magnetic field near the wire. When you hit the switch and turn off current, the field goes away. The original article talked about electrons “spinning,” and large, observable magnetic fields happening when lots of free electrons spin the same way. This happens in your current carrying wire. The voltage source provides an electric force that makes free electrons in the wire move in the same direction*, producing a field. For stronger fields, coil the wire, and the weak fields around the plain wire will stack up, and make a big field. Hope this helps.

    Oh, btw, when you start playing with coils of wire and current, especially alternating current, other weird things start going on. Like inductance.

    *the electrons move in a fashion called “brownian motion.” They don’t flow exactly like water in a pipe. But, if you take the root means squared velocity of each electron, and add them together, you would find that they all tend in the same direction, and we call that current.

• [awjtawjt]

  This is righteously awesome info. Thanks Joel & Gavin

• [mordicai]

  I really enjoy Feynman tackling this question:

  http://youtu.be/MO0r930Sn_8

• [SamSam]

  That was a great explanation.

  Quick further question (which I believe does not delve into a second-order whyyyyyy): when you line up all the domains using a stronger magnet, I assume you are not actually changing the spin on the straggler electrons, but instead just reorienting them so that they are facing the same direction, right? But what does this actually entail? Should we simply imagine that we have taken the whole spinning carousel (atom) and tipped it so that it’s pointing in a new direction?

  And if you look at a single electron, the fields it generates has a North pole and a South pole? Is the direction of the field directly related to the spin? And if you took a clockwise spinning electron and rotated it around its axis 180º, have you rotated the field? But it wouldn’t have become a counter-clockwise spinning electron, right?

  Ok, sorry. That started to become a but whyyyyyy?

  • [Anonymous]

    Greetings, SamSam: Jim Kakalios here.

    Let me take a stab at your questions:

    (1) When you align the magnetic domains in the first piece of iron using another magnet, you are doing work on the atoms in the domains, forcing them to line up in the same direction. Think about compressing a gas – you have forced the gas into a smaller volume (a more ordered state), but you had to do work to acheive this configuration. With the magnetis it is easier if you heat the first piece of iron when applying the external magnetic field. The thermal energy makes it easier to polarize the atoms. when you cool the iron down, and then remove the external magnetic field, the atoms do not have energy to reorient themselves, and you have a “permanent magnet.” You could ruin your magnet by heating it up again, but without an external field, or by just hitting it with a hammer, where the mechanical vibrations would randomize the orientation of the atoms.

    (2) The magnetic field of the electron does indeed point in the direction of the intrinsic angular momentum – well, in the opposite direction. Imagine a spinning top. Curl your fingers in the direction of rotation. Your thumb, sticking out from your palm, will point in the defined direction of the spin. The magnetic field of this spinnign electron will have a North pole 180 degrees opposite to this, as the electron has a negative charge, and currents are defined as the flow of positive charges (thank you so very much, Benjamin Franklin, for this definition.), so the magnetic field will point in the opposite direction. Flip the direction of rotation, so that a clockwise rotation becomes counter-clockwise, and the magnetic field of the electron will flip as well.

    As hard as all of this is to wrap your brain around – the actual nature of spin is even weirder. We talk about clockwise/counter-clockwise rotation, or equivalently spin up and spin down. But up or down relative to what? Until you measure the the electron’s spin with an external magnetic field, it is pointing even “up or down” relative to every axis. Once you apply a magnetic field, with a particular orientation, then THAT becomes the direction about which “up” and “down” refer. This is the heart of the mumbo-jumbo behind quantum entanglement.

    A story for another time.

    Your Friendly Neighborhood Physics Professor,

    Jim Kakalios

  • [3eff_jeff]

    SamSam to answer your questions: Spin is a vector property. It has a strength and a direction. Reorienting the direction is changing the spin. So, when you magnetize a piece of iron, you are changing the spin on untold numbers of electrons. Generally, the carousel stays in one spot, and the teacups (electrons) flip upside down or rightside up.

    The inherent field of an electron (from it’s “spin”) has a north and south pole. This is determined by the spin vector (it points along the pole axis, I don’t remember off the top of my head if it points north or south).

    Now is probably a good time to reiterate, spin is a bad word that physicists use. The electron, as best we can tell, doesn’t actually spin. It just has this angular momentum. That’s all. To the best of my knowledge we don’t know why it has this angular momentum even though it isn’t rotating. (The Why+m where the answer is “we don’t understand that yet” for magnets is astonishingly low, that’s related to Why+n being astonishingly low.)

    In that light, I’m having a hard time with your next couple of questions. There is the angular momentum axis (the spin vector), and it can point in one of two directions: up or down. This direction is determined by the local magnetic field (usually just the spin direction of nearby particles, like the nucleus). So it can be aligned and reinforcing or counter acting the local field. If the electron were spinning, flipping it from up to down would reverse the theoretical rotation, but as best we can tell, it doesn’t actually rotate.

    • [SamSam]

      So spin is a vector property, and rubbing a magnet on a nail will cause a bunch of electron spins to flip, as you say. But, as far as I’ve been able to work out from what you’re saying, spin’s direction is binary — it’s either spinning clockwise or counterclockwise. But the direction of a field is not binary.

      So if rubbing a magnet on a nail from top to bottom causes a bunch of electrons to switch to a counter-clockwise spin, what happens when I rub the magnet perpendicular to the main, making one “side” of the nail north, as opposed to one “end.”

      This is why it made more sense to me to suggest that we are just changing the tilt of the (not-really) spinning teacups, instead of saying we were flipping their spin. But it seems that the spin is, in fact, changing direction.

      So I’m still confused. This may be the problem with analogies.

• [screwt]

  This reminds me of one of my favourite ever answers given to me by y high school physics teacher (who was awesome, btw).

  I asked how one magnet knew the other magnet was there – I mean seriously, how the F does *that* work? I couldn’t accept how this mysterious thing called a “force” just magically meant the magnets were attracted to each other.

  His answer was “well, how do you think gravity works?” – i.e. I happily accept the mysterious “gravity” force that pulls me down … magnets, pretty much the same. Unfortunately that just made me realise there was this whole other mind boggling thing to deal with that I’d been fine with til now…

• [Anonymous]

  To concentrate on ICP’s line, I felt, shortly after viewing the video, that their entire ouvre (I know, there’s an apostrophe above the e, but don’t feel like changing my keyboard) is based on appearing like idiots, which tends to trip people up-they’re either knowingly, or unconciously pulling a Nasrudin-you know, the guy who would wander around riding a donkey, asking “where’s my donkey?” People would of course, be astounded, figure Nasrudin was an idiot, and point out that he was riding one. Often not realizing that Nasrudin was using a kind of moronic philosophy on them. He was saying that they were so silly, they fell for an incredibly stupid joke, and were just as silly as he was.

  Exactly what ICP did. Looks like people on the board have fallen for a “You’re not as smart as you think you are.” kind of thing-and that the more you try to prove you’re so smart, the sillier you look (just like I’m doing, by stupidly pointing how stupid this all is!).

  Then again, Nasrudin used to help people find themselves, by having them run around in circles…brilliant! And then I think, they’re throwing back at science the very point that science uses against belief-”Okay, so who made God?” Because when we get past the spin and sundry of magnets, we’re faced with a ‘mysterious force.’ Starting to get it? Think about this: if they’d dropped the F-word out of the line, they would have looked almost sensible. It hooked self-styled intellectuals brilliantly.

• [udqbpn]

  YYYYAAAAAYYYYYYYYYY!!! :-) You know, I asked my physics TA about this a few years ago. He was doing theoretical work on the origin of the asymmetry between matter and antimatter in our universe at the time. I had read via Feynman and others that one could think of two magnets REPULSING each other as being like atoms throwing “virtual” photons at each other to push each other apart via momentum.

  I told my T.A. that even after reading Feynman’s Q.E.D. (Quantum ElecroDynamics) I still didn’t see how two opposite charges attracted! How can two magnets or charges pull each other towards each other by throwing things at each other?? How do they convey to each other their pull for each other? I know that with gravity it has something to do with warping space-time, but that’s not the same for magnetism, is it? Or is it?

  He told me that the “virtual photon” thing was just some kind of approximation, and really it had something to do with fields or something, but at that point it all became gibberish, and searching the interwebs has failed to enlighten me any further on the point.

  Seriously how do those fucking magnets work. Did you know that Richard Feynman claims part of the reason he became a physicist was when he got a compass as a child and suddenly got this idea that there must be something magical going on in the world? I shit you not. Although personally I thought there was something weird going on before that when I realized some inexplicable thing was pushing me down on to the ground all the time. Probably just the noodly appendages of the Flying Spaghetti Monster. Rant over.

• [Anonymous]

  http://paleocave.sciencesortof.com/2010/11/fcking-magnets-how-do-they-work/

  I wrote a blog post a couple months ago on magnets.
  explaining them shouldn’t be mind boggling.

• [Stewtheking]

  Excellent explanation, if a little too sweary to lift verbatim for use teaching in school.

  I hit a magnetism brick wall teaching high-school science. I am a biologist by trade, but have to teach all sciences at KS3 (up to age 14). When it came to teaching magnetism for the first time, I was stumped looking for a way to simply explain it, and turned to my brother (mathsy-physicsy; slightly asd; superbrain) for help. After pondering the question for a long while, he gave the answer “Well, magnetism is sort of like electricity… but purpendicular.”

  Needless to say, I sought help elsewhere.

  • [3eff_jeff]

    Magnetism is sort of like electricity but perpendicular. The electric force acts along field lines (dot product) and the magnetic force acts across field lines (cross product). Also, the magnetic force is the relativistic transform of the electric force. Basically, when you shift between frames of reference, magnetic fields pop up so that the motion and forces observed from all frames are consistent.

    You can imagine a rotating, charged globe and a small oppositely charged particle in space. If you are off the globe observing, there will be a magnetic field, and the small particle will spiral into the globe. If you are on the globe directly underneath the particle, it will appear to come straight down at you, and you will observe no magnetic field.

    Of course, if your best answer for a 6 year old is “sort of like electricity but perpendicular” it’s probably time to fall back on dad logic. http://xkcd.com/826/

• [Utenzil]

  Thanks very much, this is f*ing cool <– in for 1/7th penny

  It seems like if one got *all* the electrons in one piece of iron to spin one way, and *all* the electrons in the other piece of iron to spin in the other way, they’d fuse, right?

  That is to say, wtf would happen?

  • [3eff_jeff]

    Utenzil, if you got all the electrons spinning the same way in a material, you’d just have a really strong magnet. That’s all. Go look up the Pauli Exclusion Principle. (It’s the quantum mechanics behind: two objects cannot occupy the same space at the same time.)

    • [Utenzil]

      “That’s all” !!!?

      Well, you are not as f’ing awed as you should be about magnets I think, but I appreciate the answer :)

• [Anonymous]

  So -how magnets work is explained by reference to the magnetic properties of electrons (ie how magnets work). How exactly does that explain how magnets work?

  • [teufelsdroch]

    1) Moving electric charges create magnetic fields. To prove this, place a compass next to a wire.

    2) Electrons ‘spin’, creating a field akin to a charge moving in a circle. I.e. a dipole, the familiar North-South magnetic field you see if you put a bar magnet near iron filings.

    3) When you heat iron, you give the dipoles enough energy to line up. That is why iron placed in a hot enough fire becomes magnetic, and why lightning-struck iron is a lodestone.

    4) (the +1 explanation) Static magnetic fields are made by interacting with a cloud of electrons and positrons which are constantly, and briefly, coming into and out of existence. When charged particles exchange momentum with this virtual photon field, they create the magnetic force.

    Think that’s it…

  • [Anonymous]

    When most people say magnet, they mean the lumps of material that attract certain metals. How those work, and how magnetic fields work in general, are two separate questions with two separate answers. After all, everything has some interaction with magnetic fields, but only certain special substances can be used as magnets.

• [Bill Beaty]

  What is a magnetic field? Well, electrostatic fields and magnetic fields are two versions of the same “stuff,” so the real question should be: what the hell is an EM field?

  Answer: Michael Faraday discovered the concept of “fields in empty space.” Faraday saw that, besides empty space and particles, there was also a third thing here: fields of invisible force. A field wasn’t a material. It was a ghostly thing which spread out into space and caused North poles to repel other North poles, and caused Negative charged particles to attract Positive ones. This idea was so heretical that Faraday experienced years of sneering/derision, and he even died before ever see his discovery vindicated. Probably JC Maxwell’s championing of the “Field” concept was the main reason why fields made the jump from Disgusting Physics Heresy to mainstream acceptance. So what is a magnetic field? It’s a disgusting crackpot heresy which must be stamped out by all right-thinking physicists.

  Another Answer: What if an atom was the size of a baseball? Yes, it would be an intensely weird object …but one part of the weirdness is already available: a single atom would be like a magnet! In other words, if we take a hunk of iron and align all the spins of the inner electrons in all the iron atoms, the entire piece of iron begins acting like a single gigantic atom. So what is a magnetic field? It’s one of those weird things we’d see if we could hold a huge atom in our hands.

  • [Anonymous]

    Maxwell didn’t champion fields. In his version, everything was still based on motion of ether, some fine gaseous medium permeating space.

• [chenille]

  For those curious as to why there should be spin, I’d like to try to do a bit better than “there just is”.

  A basic mathematical property of field theories is that for each symmetry, you can defined a conserved quantity. For instance, the laws of physics are the same over time, and that gives you the conserved value we call energy. For a quantum wave, the energy is basically the frequency, i.e. how many vibrations are over a set period of time. If you took physics you might remember E=hf.

  Momentum is similar, but instead of looking at time, you look at spatial axes: how many vibrations there are over some given distance. And for angular momentum, you look at rotational axes: how many vibrations there are as you turn around the wave.

  Something like a Higgs particle is supposed to be perfectly symmetrical, so the only angular momentum it has would come from how it is moving. A photon, on the other hand, turns out to look different from the front and back. So when you rotate around it, you get a little extra change in the wave from which side you are looking at, with a period of 360 degrees.

  That extra vibration means extra angular momentum that isn’t related to how it moves. Because angular momentum is normally connected with rotating objects, that intrinsic value is called spin, but really, it’s a measure of what kind of symmetry photons have.

  Magnetism comes from charged waves. If you’re willing to accept a magnetic field from a current, where an electron wave varies along some path, you should see why you’d also get one from a single particle with spin, where there is wave varies around its axis.

  The short version: spin has to do with what kind of geometry things like electrons and photons have. I hope that’s at least a little more satisfying.

  • [Mike Mol]

    That’s actually incredibly illuminating, thank you. :)

    (And thanks to Joel for the earlier explanation, too)

• [Bill Beaty]

  Another answer: Radio waves are these invisible ripples which fly through empty air, and these waves can vibrate a charged object or a magnet. But what if we could *stop* a radio wave? Catch it in a box? Well, that’s what a magnetic field is. It’s a radio wave that’s attached to a piece of iron: a radio wave without a frequency: a “DC radio wave.”

  Another: during electric currents, during flows of charges inside a wire, the wire becomes surrounded by a strange invisible thing called a “magnetic field.” Wind the wire into a coil, and the “field” becomes much stronger. But here’s and odd concept: when a battery is powering an electromagnet, the battery’s energy all goes into heating the wire, and none of that energy flow is needed to create the magnetism. If wires had no resistance, we could connect them in a complete circle, remove the battery, yet the electromagnet would keep on working. And that’s why permanent magnets exist: they are electromagnets created by moving charges, but these charges lack friction, so the need no power supply, and nothing ever slows them down.

• [ROSSINDETROIT]

  Magnetism is not trivial. It’s all around us but its ubiquity doesn’t make it simple. I kinda know how electrons attract through exchange of particles but only because I read a 430 page book on particle physics that Gareth Branwyn ‘assigned’: http://www.amazon.com/Warped-Passages-Unraveling-Mysteries-Dimensions/dp/0060531088.
  The book was very enlightening but left me with even more questions. Unfortunately “If the quantum fluctuations in vacuum retard weak force particles and strengthen strong force particles, does the vacuum’s energy remain net zero?” is hard to rhyme and will never be in a lyric.

• [Anonymous]

  Utenzil:

  http://en.wikipedia.org/wiki/Saturation_%28magnetic%29

  The long and short of it is that it will not become a molten slab or fuse. You can simulate the same effect with electromagnets.

• [lasttide]

  This post pretty much summed up my knowledge of permanent magnets. However, when I think about what I know of quantum mechanics, this explanation begins to make little if any sense.

  Basically, please post the why+1 explanation of magnets.

  • [jangusKhan]

    This is Joel from the article. I’ll see what I can do here; I’m not totally sure what your asking.

    Every electron has an intrinsic magnetic moment which is the result of this quantity we call “spin”. As mentioned in the article, this cannot possible be actual, physical spin, because the calculations of its velocity produce values higher than the speed of light. Even so, the magnetic properties of the electron are very similar to a charged object that is spinning in place: it has a magnetic moment (strength and orientation) that is measurable in the lab.

    In most materials, the valid orbitals for electrons to fill produce electron pairs whose spins are opposed. That is, their magnetic moments cancel each other out, leaving the effective amount of magnetism at zero. However, the way electrons fill orbitals is not as simple as filling a bookshelf. Electrons always fill the lowest energy level first, and due to orbital interactions this produces some unexpected results. In iron, cobalt, and nickel (mostly iron), there is an unpaired electron that results in a small net magnetic field. Also, in order to produce strong magnetic fields overall, the individual atoms must be highly organized, crystalline in structure, like iron and some iron compounds.

  • [Anonymous]

    Magnetism can be viewed as a consequence of electrostatics and relativistic length contraction:

    http://skepticsplay.blogspot.com/2007/12/relativity-electrostatics-magnetism.html
    http://skepticsplay.blogspot.com/2011/03/electricity-magnetism-space-and-time.html

    http://physics.weber.edu/schroeder/mrr/MRRtalk.html

• [phosphorious]

  I’m not sure this explanation explains anything. As BurntHombre says above, to say that “spin” causes magnetism dodges the question. As does saying that a bar of iron is magnetic because its parts, electrons, are magnetic. The question remains: what is magnetism.

  Compare it to gravity: gravity is explained by saying it’s a bend in space. An objects mass warps space, causing objects to move differently through that space. The attraction that the earth has for the moon is therefore described in terms of a simpler concept, namely a bend in space.

  But what explains a magnet’s attraction for iron, but not for wood? “Spin” creates a “magnetic field”. . . but what exactly is a magnetic field?

  If this question seems ignorant, that’s because it is. I am not a scientist to any degree.

  • [chenille]

    Sooner or later any line of questioning is going to run into something that simply is. If you’re satisfied with explaining gravity by bending 3-D space, though, you can also get electric fields in a very natural way by looking at bending 4-D space. This is the approach taken by models like string theory to explain forces, but it’s still being worked out.

    If you take attraction and repulsion of electric charges for granted, though, magnetism automatically shows up as what that looks like when they move. Something sitting in place is on a path through time, and something moving is one one through time and space. By relativity, though those are just different directions; you can do a space-time rotation to turn one into the other.

    What we find is that the field a charge generates also has a direction through space-time. If a charge is sitting there, only moving through time, that field will also point straight into time. A second stationary charge will only feel a push or pull based on that same component, which is what we’ve named the electric potential.

    The situation where they’re moving is the same, but rotated. Now the charge is going through time and space, so besides the part of the field pointing into time there are extra space parts. And a second charge also moving through space and time is going to feel forces based on them, because rotate back to its perspective and they become time again.

    Those extra components are what we call magnetism; you get them straight out of rotating Coulomb’s Law. Unfortunately the math is hard to follow intuitively, because these aren’t ordinary Euclidean rotations. Even so, I hope that gives some idea why there should be an extra force associated with currents and spins. Relativity actually gives similar results for gravity, but most of the time you never see anything both heavy and fast enough to notice it.

  • [donncha-m]

    I don’t think your question is ignorant, but from my (albeit very limited) understanding of current physics, nobody really knows how to answer your question.

    Physics has approached an understanding of forces and particles and the quantum universe from the top down, by way of reference to the middle-world we exist in and by using ever-more-refined analogies and similies.

    Magnetism (and gravity, and forces and fields) don’t make any sense in our world. We just accept them. That’s all. But what makes sense in our world – concrete matter, pushing and punching and possibly even ‘object’-hood itself – doesn’t make sense in theirs.

    The mind-blowing thing is, somehow our world is BUILT ON TOP OF the other. Explaining that…well, is why we still have physicists as opposed to just physics-historians.

• [jjatria]

  I hate to comment on something that is so tangential to the topic at hand, but I haven’t seen this here before, and I think it might be interesting, specially with all the links between this and ICP.

  I have to say, after reading this interview from the Guardian from last October (“Insane Clown Posse: And God created controversy”), I think they might have been holding back a bit on that explanation of the motivations behind “Miracles”.

  I’d like to believe it’s a song that’s ultimately about how wonderful the world is, and for a long time I refuse to believe otherwise.. But really, the drive behind XKCD and ICP could not be further apart, even if the way in which it materializes shares some (rather minor) common ground.

• [ROSSINDETROIT]

  The +1 question here would be how is force mediated between electrons, and that’s where things start to get seriously weird.

  • [pauldavis]

    The +1 question here would be how is force mediated between electrons, and that’s where things start to get seriously weird.

    i think that even asking this question is falling into the trap that Kelvin warned us against: do not mistake your models for reality. our models include a number of fundamental components (force is one, fields are another) that are really useful in explaining what happens. i’m not sure they are useful for anything more than that, which means asking “how does force work” is a bit like asking “but how does suction work?” in response to the “tubes” explanation of the internet.

    • [ROSSINDETROIT]

      I disagree in this case. The particles that mediate the force between electrons (I’d have to look up the actual mechanism) have characteristic behavior that’s useful to know about. They’re not just the nails that hold things together and can be ignored. More like screws that have distinct diameter, pitch, length and depth. Going one level down below ‘net polarized substances attract or repel’ reveals more information about how things work.

• [ROSSINDETROIT]

  Pauli Exclusion Principle = awesome. Spin polarize all of the molecules in a gas and they will avoid each other. The mean free path between collisions is longer because they’re swerving around to stay away from particles with the same quantum states.

  • [3eff_jeff]

    It’s even more awesome that it only applies to half-integer spin particles, so when you get integer spin particles, they *can* be in the same place at the same time. Which leads to crazy stuff like superfluids and superconductivity.

• [pauldrye]

  Everything that ever existed—from a giraffe, to a magnet, to the Insane Clown Posse—is made up of atoms.

  Not really. Plasmas aren’t, so stuff like lightning and stars aren’t made of atoms. The majority of the matter in the universe isn’t composed of atoms, TBH.

  (I bring this up because I am a nit-picking jerk. Sorry.)

  • [Ralph Giles]

    Plasmas aren’t, so stuff like lightning and stars aren’t made of atoms.

    Plasmas are made of atoms where some (or all) of the electrons are free to move independently of the nuclei. Some of the teacups have come off the carousel, in other words. But it’s still made up of positively charged proton-neutron balls and electrons.

    The same thing happens in metals; some of the electrons in a bulk metal can freely flow from one nucleus to another. That’s why metal conducts electricity.

    So while plasma doesn’t really fit the ponies-on-a-carousel model, it’s still made up of the same stuff as everything else, just arranged a bit differently. At the level of ‘everything is made of atoms!’ I think it’s misleading to say plasma is any different.

• [Anonymous]

  Huh? You’ve answered the question of why magnets attract (or repel) each other by saying that they are made up of electrons that attract (or repel) each other. But… Why do electrons attract (or repel) each other?

  I like Feynman’s explanation the best, but really, when you get down to it, when it comes to force, be it gravity or magnetism, we don’t really know “how” or “why”, we just know “what”. Any explanation I’ve ever heard always comes down to a description of what is happening (or a metaphor for the same). There is never an answer for “why?”.

  I like Feynman’s answer the best because he basically explains that there never is an answer to “why?”

  -Why did she fall? Because she slipped.
  -Why to people fall when they slip? Because of gravity.
  -Why does gravity make people fall? Because it’s a force and that’s what it does.

  As the Old 97s say, “Blame it on gravity.”

• [tsa]

  But still I don’t understand magnetism. All this spin-stuff I know from university, but indeed, the +1 question, and maybe even the +2 question also has to be answered: what causes the attracting or repelling force, or in other words what pulls or pushes the magnets? Or, in other words: what does a ‘field,’ wether electric or magnetic, consist of?

  • [Oskar]

    Or, in other words: what does a ‘field,’ wether electric or magnetic, consist of?

    YOUR MOM!

• [patter]

  I’m glad that cats aren’t magnetic, floating them with antigravity toast is bad enough but a cloud of floating cats all stuck together back to back floating through the town and terrorising small dogs *shudder*

  otherwise, very interesting article :)

  • [Anonymous]

    Maggie left a gaping hole in her discussion, feebly attempting to skirt with the passing remark that cats do not stick together.
    I beg to differ.
    In fact, I have observed the following:

    Kittens stick together. Apparently, any number of kittens can stick together.
    Cats stick together, but only in pairs.
    Puppies stick together, much like kittens.
    Dogs do not stick together.

    Details discussing Bose-Einstein and Fermi-Dirac statistics, the Pauli exclusion principle, and Iams vs. Purina, are left to the astute reader.

• [Harrkev]

  And still nowhere do you actually explain HOW it works. If you have two magnets, what causes the force between them? One flies towards the other — what exactly causes the motion?

  I know that photons are electromagnetic (note the “magnetic” part). Electricity, magnetism, and photons are all closely related. Moving electricity creates photons (think a radio antenna). Moving electricity also creates a magnetic field (think electromagnet).

  So two magnets in close proximity must be exchanging a LOT of photons in order to make one move towards the other. How are these photon different from the ones given off by a light bulb? AFAIK, all photons are the same except for polarization and frequency. Why don’t two magnets glow if you put your head in between them? Also, if you think of an analogy of two ships firing cannons at each other, they will move farther apart, not closer together. Yet two magnets shooting photons (that we can’t see) towards each other move closer. How does THAT work?

  • [Mike Mol]

    This one I might be able to answer a part of, based on the electronics course I took when I started college, with a synthesis of some of the stuff described above. As I got to the end of writing it, though, I felt like I was drifting off into la-la land. Any studied folk spot anything recognizable or simply wrong in it, please point it out.

    Magnetic field lines, I was told, are thought of as a static ‘circuit’ of photons. Based an above description of spin, it doesn’t seem wrong to thing of this ‘circuit’ as inexhaustible, as it’s not a transfer of something from one place to another. It seems like it’s more a static wave.

    These circuits desire to be as short as they can, but that depends on the permeability of the material they’re passing through. Materials with high permeability will allow the field to pass through in a more concentrated fashion, which allows a particular path parallel to the shape of the field to be shorter.

    I expect that it’s the attraction of two opposite magnetic poles which causes a pull between all electrons in the field. Think about an electric circuit. Any two points in the circuit have a potential relative to each other, but you can take your voltage source and simplify your view of the circuit by collapsing components directly attached to it into your unitary view of it (assuming there are no other components directly attached to it).

    If you take that integration of components and consider each particle on the magnetic circuit to be a component of that circuit, then you can think of of any group of particles as a single one, and think of each group of particles attracting the next group along the circuit.

    As these particles get closer to each other, their pull on each other increases (hiya, inverse square law!). As their pull increases, they tend to get closer, so it’s a self-reinforcing.

    Where does the initial movement come from, though? At a guess, I might point at temperature vibration, or possibly this ‘vibration’ that is described by string theory. Anything that causes things to be non-static in a static frame of reference might suffice. (Which is curious, actually…if a vibration is perpendicular to the direction of the magnetic field, it wouldn’t have an effect in bringing the component closer or farther away. If it were in any component parallel (my geometry terminology is almost gone, sorry), the magnetic field might represent a resistance or inertia against movement away, but not towards, and thus the actual force viewed would be the aggregation of the vibrating energy)

  • [Anonymous]

    This is backwards. A photon is a wave in the electromagnetic field, like a sound is a wave in air pressure. The only properties the waves have are polarization and frequency, but the field itself has others, just as you can have different air pressure and temperature even in absence of sound waves.

• [bcsizemo]

  I don’t particularly like Feynman’s answer.

  It’s like saying it just does… Well isn’t that just wonderful.

  I’m not exactly a layman, but it looks like Physics would try and explain all the whys. The number of questions associated with how/why does a magnet work isn’t going to delve off into topics of love and war. It should just be a series of ever progressively complicated steps. Atom -> electron -> spin -> mystery force??? -> …???

• [Anonymous]

  I remember being told a long time ago, that the first WHY is why (useful fiction) and every why after that is looking for a RESULT… Why does the sun shine? They want a reason, and emotive cause and effect reason – not a HOW does the sun shine (hydrogen.. etc).. but “So the grass can grow”, it seems backwards, but it works beautifully to explain the relationships between things that can then be expanded later.

  Early one, “Why” is asking for a relationship – later, maybe around 7 or so, does it really get into the “how”. How == what mechanism causes the phenomenon, Why == for what purpose is this phenomenon.

  So you never answered “Why do magnets work?”, you answered “How do magnets work”.

  Why do Magnets work? so we can travel to Mars!

• [rosyatrandom]

  There’s some fascinating reading in the comments – what I’m really getting from it is how the essential element is that electrons are, in some way, frozen features of the EM field that represent spin quanta, and this is due to the geometry and polarity of photon exchange.

  I have a question, though – I know the electrons aren’t really spinning… but if they _were_, how big would their radius have to be for their magnetic moment to be produced by them spinning at lightspeed? Or does that not make actual sense?

  • [teufelsdroch]

    I read this as ‘does the torque on a single spinning electron equal that of a certain non-spinning electron moving in a circle?’

    Course it does.

    If you take the electron’s velocity as ‘c’ (as you do) it happens when

    r(m_e)(c)/hbar = 1/2

    or

    radius of orbit = hbar / 2(m_e)c = 1.9e-13 m. ’bout a hundred times thicker than a proton.

    See: http://en.wikipedia.org/wiki/Electron_magnetic_dipole_moment

• [Anonymous]

  And then I think, they’re throwing back at science the very point that science uses against belief-”Okay, so who made God?”

  Science never used that line against belief; it only shows that insisting everything should have a cause isn’t an argument for God, since adding God doesn’t actually resolve the problem.

  As for the ICP, removing the F-word: “Magnets, how do they work? I don’t want to talk to a scientist, you are all lying and getting me upset”. No, it still sounds sophomoric and willfully ignorant. I don’t understand why everyone expects there to be some hidden brilliance here instead of using Occam’s razor.

• [Anonymous]

  I don’t want to be a jerk but you’ve basically said: “magnets work because electrons have a magnetic field”.

  That isn’t an explanation, it just leads us to ask “how does an electron’s magnetic field work?” :/

  I mean it’s still an interesting article, but you haven’t actually answered the question.

  -TitaniumTeddyBear

• [Anonymous]

  Man, you people are really getting a jump on 4/20

• [Lobster]

  OK, maybe you can explain the “fucking magnets” line. How about the one after that?

  “I don’t want to talk to a scientist, ya’ll motherfuckers lying and getting me pissed”

  To me that sounds like they’re saying, “I don’t know how magnets work and I question the motives of anyone who tries to explain it to me.”

  That’s not a childlike wonder and appreciation of our beautiful universe. That’s aggressive anti-intellectualism.

  Even though it is a good question to ask, the ICP should not be the ones asking.

  • [Cola]

    You beat me to it.

    The whole point of that song is “…fuck science because I don’t want to know how shit works.” It’s a fundamentally incurious mindset, and we don’t owe them any kind of apology for wearing their ignorance with pride.

• [AirPillo]

  So metals/alloys that make strong magnets (neodymium magnets for example) possess this strength because they have a larger number of non-paired electrons to generate a cohesive field, then?

  • [Ralph Giles]

    The unpaired electrons are part of why rare earth magnets are so strong. This is getting into the why+1 explanation.

    There’s a phenomenon called ferromagnetism which is one of the important ways we experience magnetism in everyday life. Because of details of how the unpaired electrons in adjacent atoms interact, they like to point their spins in the same ways as their neighbors. It’s ferromagnetism which allows the formation of city-states in the first place; without it there’s just a collection of hunter-gather tribes making their own decisions.

    At room temperature, only the elements Iron, Nickel and Cobalt are ferromagnetic. This is why a magnet will stick to a piece of steel, but not a piece of aluminum, for example. When you bring a magnet close to a ferromagnetic material, all the unpaired electron spins feel the field, and some of them start to align with it. The ferromagnetic effect means that once some start to align, all the others do too, and suddenly the piece of steel has become a mirror of the magnet, and the original magnet is attracted to it just like it was another permanent magnet. In a non-ferromagnetic material, like aluminum, some of unpaired electrons still align, but there’s no collective agreement and most of them just say “we’re fine as we are, thanks.”

    How do we make a permanent magnet then? Generally what happens when you take the magnet away is that the city-states go back to squabbling. Ferromagnetism means that they like to do what their neighbors are doing, but without the “leadership” of the externally imposed magnetic field, it’s easier for each microscopic magnetic domain to point in a different direction. You do what your neighbor does, but customs are different across borders. Some of the domains still point in the direction of the last field they felt, which is why can you magnetize a piece of steel by rubbing it with a magnet, but this is a weak effect.

    To make a stronger permanent magnet, you need a way to keep those domains pointing in the same direction, even after you take away the magnetic field which aligned them.

    It turns out that rare earth alloys, like Neodymium-Iron-Boron are ferromagnetic, although Neodymium by it self is not (at room temperature).
    So you get domains where every atom’s tiny magnetic field is aligned. And those tiny magnetic fields are particularly strong for the Lanthanide atoms.

    However, what’s most important to the strength of a permanent magnet is what’s called the magnetic anisotropy. This is a separate effect from ferromagnetism, although it also arises from the details of how the magnetism of each atom interacts with its neighbors. Magnetic anisotropy means that the unpaired electrons want to align their magnetic fields with a particular orientation in the material’s crystal lattice. And that is how you keep them all pointing the same way, You can grow crystals the size of the ferromagnetic domains, align them in an external magnetic field and then melt them all together while they’re pointing the same way. The crystal grains can’t move because they’re frozen in place, held in a particular orientation by the physical matrix of the material. Magnetic anisotropy means the atomic-level magnets want to point the same way as the crystals, and ferromagnetism means they’re all going to point that way.

    It’s the combination of the three effects together which allows us to make such strong, permanent magnets.

    Hope that makes more sense than the paragraph saying the same thing in wikipedia. :)

• [Anonymous]

  @bcsizemo
  What you’ve written there:
  “Atom -> electron -> spin -> mystery force??? -> …???”
  is basically everything that physicists know about magnetism (pretty much).
  We know it’s a force, and that it’s very closely related to the electric force (but at a right angle). In fact, we’re so sure they’re connected we usually just talk about the electro-magnetic force, but after that the next question is “what is a force?” (along with “how does it work?”, and “why is it stronger here than over there?”, and eventually “what do I mean by stronger?”), and I’m afraid we don’t really have any good answers to that question.
  Certainly no easy answers that will make you go “oh right, so that’s how it works”, more the sort of answers that make you go “um, right, I kinda get that bit, but…”.
  Sorry. We’re working on it though!

• [lutzray]

  Speaking of Feynman, anyone interested in magnetic force and science vulgarisation should watch this Youtube video wMFPe-DwULM . Feynman FAILS to explain how do magnets work 8-)

  “I really can’t do a good job, any job, of explaining magnetic force in terms of something else you’re more familiar with, because I don’t understand it in terms of anything else you’re more familiar with.”

• [yesno]

  Is it the case that any “spinning” electric field (whether it’s an actual spinning object, or just subatomic angular momentum/”spin”) creates a magnetic field?

  I mean, I know enough about how generators and motors work, to know that there’s some connection between movement and electromagnetism generally. Is it really a deep angular momentum connection, where angular momentum creates magnetism out of electric charge?

• [TFox]

  After my sophomore year as a physics major, I got a summer job working on the magnets at the Stanford Linear Accelerator. I realized that I didn’t really know how magnets worked, and decided that if I was going to work on them, it’d be good to know. So I spent a couple weeks in the library, studying the Feynmann lectures on physics, and every other source I could find. At the end of that, I knew a lot more about magnetism, but still didn’t really feel like I knew how magnets work. Later, I got a PhD in physics, so I’ve been able to do graduate problems in magnetism, know the QM, know about the various magnetic moments (in addition to electron spin, there’s the orbital moment, and the nuclear moment) and their interactions, and have even been able to do therenormalization that describes the ferromagnetic phase transition. (Ie why does iron behave differently from a cat.) Nevertheless, magnetism still feels like a bit of a mystery. Fucking magnets, how do they work?

  • [sisyphus321]

    Thanks for an honest reply. What I have been able to gather from the discussion is that the state of knowledge about magnetism is essentially “when we work the math out, there’s this thing about electrons that has units of angular momentum, so we’re going to call it ‘spin’, and that thing also shows up in the math when we talk about magnetism, but basically we don’t know.” Which is at least honest, if not satisfying.

• [doingdoing]

  But why are cats attracted to couches?

• [BurntHombre]

  Electrons produce a magnetic field because they spin.

  But…but…

  You might as well have said they produce a magnetic field because they’re sparkly. Why does this “hard-to-describe property” produce a magnetic field?

• [Anonymous]

  I think I understand magnets as well as one without a physics degree can. But why do some cutting tools become magnetized while “permanent” magnets lose some strength when knocked?

• [Anonymous]

  Feynman’s description in the Feynman lectures book is pretty good. It uses just the electric field and special relativity to calculate the force between 2 parallel wires with currents in the same or opposite directions. magnetism is just a relativistic effect. (you may need some basic undergraduate physics knowledge to appreciate it).

  Once you get that, then seeing how a rotating charge can make a magnetic field is a small step.

• [KWillets]

  I like this explanation for how magnetism arises from Special Relativity (remember Einstein’s paper was titled “On the Electrodynamics of Moving Bodies”):

  “Let’s consider a specific case: two wires with current going in the same direction….From the electron’s point of view, the other wire contains a bunch of motionless electrons and a bunch of backwards-moving protons….Lorentz contraction causes the protons to be closer together, more densely packed. As a result, the other wire has an overall positive charge, creating an electrostatic force. The electron will be attracted by this force.”

  http://skepticsplay.blogspot.com/2007/12/relativity-electrostatics-magnetism.html

  Magnetism is related to relativity; in fact Dirac’s derivation of electron spin starts by writing the relativistic expression for energy rather than a classical one. The above thought experiment makes it clear in a simpler context — one reference frame’s magnetism is the other reference frame’s electrostatics.

  Then it’s turtles all the way down.