Feynman: How Do Magnets Work?

Feynman seems irritated at the question:

“I’m not going to be able to give you an answer to why magnets attract each other, except to tell you they do.”

Fucking magnets, how do they work? Even Feynman doesn’t know!

  • bigjohn756

    I agree 100% with whatever it was that he said.

  • http://lydiafromtexas.wordpress.com/ LRA

    Brilliant man!

  • dutchhobbit

    F*cking Feynman, how does he work?

    • http://lydiafromtexas.wordpress.com/ LRA

      WIN!!!

    • http://camelswithhammers.com Camels With Hammers

      “F*cking Feynman, how does he work?”

      That about sums up my feeling.

  • MahouSniper

    He didn’t say he couldn’t explain it. He said he couldn’t explain it in terms we’d understand since we don’t have the necessary doctorates or an IQ of 200.

    • wintermute

      I’m guessing the complete explanation involves prostitutes…

    • Michael

      You don’t necessarily need a PhD or 200 IQ to understand how magnets work at some level, but to understand it to the same level Feynman does would probably require a lot of post-doc work and a fairly high intelligence. Feynman understood as well as anybody for his time, but keep in mind his time was quite a while ago.

  • Danny Wuvs Kittens

    I think I kind of get it. The atoms(or molecules? I dunno) or whatever in the magnets have a tendency to stay together with other atoms, just like the atoms in a chair have a tendency to stay together, except when they’re pulled apart with enough force so that the atoms break, and the opposite is true for why they repel; like he said, when you push on a chair, it resists, because the atoms tend not to allow shit to pass through.

    I still don’t know WHY atoms tend not to allow shit to pass through, or tend to stick together under certain situations(why do atoms bond when they’re heated, like with plastic or metal?). Why do atoms stay together in the first place? What makes the protons and electrons or whatever spin around? Where do protons and electrons come from? Is it possible to make a molecule from just protons, electrons, and a nucleus if you can find out how to stick them together?

    He makes a good point. Its a curios question; why do magnets work? Most normal people aren’t curious enough to give a goddamn, and the people who ARE curious enough to give a goddamn won’t be satisfied easily.

    Who is this guy? I’d like to watch more of him.

    • http://lydiafromtexas.wordpress.com/ LRA

      Atoms have three subatomic particles: protons (+), electrons (-), and neutrons. The protons and neutrons are in the nucleus of the atom and the electrons are on the outside in shells (orbitals). Electrons are the same charge and repel other electrons. That’s why stuff doesn’t pass through stuff- the external electrons are repelling other electrons.

      Also, an electron is the smallest magnet there is. Flowing electrons result in magnetism. That’s why it is called the electro-magnetic force. In ferromagnetic metals, some of the electrons flow to one end of the magnet, making that side more negative and the other side more positive. But you can’t cut apart the poles of a magnet, you just get two magnets. It’s because the electron flow is only of some of the electrons in the weird ‘d’ orbitals.

      • http://lydiafromtexas.wordpress.com/ LRA

        Also, bonding of elements or molecules happens when electrons in the outer orbitals are shared. For instance, in water, hydrogen has 1 electron and water has 6 electrons. A valence shell (orbital) is full (not always but as a general rule) at 8 electrons… so

        ** **
        **O**
        H H

        That’s what a water molecule looks like. The electrons on top push the Hs down making water look like a boomerang.

        • http://lydiafromtexas.wordpress.com/ LRA

          Oh! And there are four forces associated with atoms– the strong nuclear force, the weak nuclear force, the electromagnetic force, and gravity. These forces are what cause the attractions and repelling we are talking about.

          You will learn about all of this if you take chemistry.

          • http://lydiafromtexas.wordpress.com/ LRA

            Whoa! Feynman is right… there are layers and layers of explanations!

          • Danny Wuvs Kittens

            Holy shit! That’s a lot. Thanks!

            I took some shitty creationist general science and chemistry a few years ago. It was mainly wasted on showing how amazing gawds creation is and debunking evolution through fucking lies that I’m still trying to de-program. A year ago, I qualified for a dual-enrollment classes, and because I already had a bunch of shit to do, I figured I’d just take one class; biology, so I didn’t have to “waste time in college studying it(my mother’s words). I would have learned a fuckload if I wasn’t a creationist. I believed I was being indoctrinated, so I made a point to not take the information seriously(I think that because of this, my brain never moved the information to the permanent memory section or whatever its called). Towards the middle to end of the class, I kind of believed in (theistic) evolution, didn’t really. Its hard to explain. When the class ended, I was very relieved, and made a point to forget all the “brainwashing” I had been through.

            Thank go-

            Thank the people who invented the internet, thank the people before them who invented languages and forms of communication that allowed information to be transmitted easily and fully, thank the people who helped to evolve and continue to evolve the internet, thank the workers who maintain the infrastructure required to keep the internet up, thank the coal miners, truckers, coal sun, wind and nuclear workers, thank the people who build servers and websites, thanks to my ancestors who came from abiogenesis, then, through processes that I’m just beginning to understand, evolved into fish, then grew lungs and legs, then gradually evolved into homo-sapiens, whom I also thank for not all dieing from tigers and shit. Thank all my ancestors and their stages, for surviving and fucking for so long to allow me to be conscious and literate.

            Thanks to the people who provide free, educational media. Videos, blog posts, books, and, more specifically and recently, longass comments that fascinate me, make me want to learn more, and give me back more of what religion stole from me. Thank all of those people, and especially you. Thank all of them for allowing me to have more to say than “Thank God”.

            • http://lydiafromtexas.wordpress.com/ LRA

              You’re welcome!!!

              :D

              Any other questions?

      • Michael

        In ferromagnetic metals, some of the electrons flow to one end of the magnet, making that side more negative and the other side more positive.

        No, that could be true of charged ends of a metal, but not of permanent magnets. Permanent magnets have a certain alignment of spins of electrons. All electrons spin, and this spin results in a magnetic field around those electrons. However, two electrons in an orbital must always spin in opposite directions, so (for the most part) only materials with unpaired electrons have a significant magnetic moment. Still, the direction of the unpaired electron is random, so there is usually no significant magnetic moment in the absence of an external electric or magnetic field. This is why you can temporarily make iron into a magnet by putting a current through it or holding it next to another magnet, but the magnetism degrades rather quickly (in a couple of minutes). However, there are some materials, such as the natural magnetite, which retain their magnetism in the absence of such fields. I don’t really understand why. According to Wikipedia, they still have an equal number of spin-up and spin-down unpaired electrons arranged in a sublattice, but (for a reason that is not clear to me) the magnetic moment of one is greater than that of the other, so they don’t cancel. I imagine this would depend on the geometry of the crystal lattice, among other things.

        • http://lydiafromtexas.wordpress.com/ LRA

          Ah! Thanks for the correction. I’m a biologist by training, not a chemist or physicist. I think I mixed up electrically induced magnets with permanent magnets.

          Here is a website that explains the role of the crystalline lattice of ferromagnetic metals in magnets:

          http://magician.ucsd.edu/Essentials/WebBookse18.html

    • Paul

      “I still don’t know WHY atoms tend not to allow shit to pass through, or tend to stick together under certain situations…”

      Two ways of thinking about this. One, when atoms bound together (share their orbiting electrons with other atoms), they form some sort of structure. This has structure has gaps in between the molecules, so only things smaller can pass through. Two, more along the lines of what Feynman was talking about in the video, like charges repel. Electrons are on the outsides of molecules and atoms (which is why electrons are shared when atoms and molecules bond together). We are made of atoms and molecules and so is everything else, therefore, when are electrons get close to the electrons of objects, they repel. The scale on which this happens is really really really small, so it appears, to us, that we are touching the object.

      “…(why do atoms bond when they’re heated, like with plastic or metal?)”

      The electrons orbit around the nucleus (although these aren’t nice orbits like the planets have, but similar enough), and can store energy by moving into different orbits. Think about swinging a rope in a circle: If you give it more energy– that is, you swing it faster– the rope wants to increase the radius of the circle it makes while swinging. Similarly for electrons. So when you add heat, a form of energy, the electrons move around. Heating actually will break bonds, not form them, since the more energetic electrons are hard to share between atoms.

      “Why do atoms stay together in the first place? What makes the protons and electrons or whatever spin around?”

      The reason the electrons are spinning around and why the atoms stay together is due to the fact that, just as like charges repel, opposite charges attract. Protons are of opposite electrical charge as a proton, so the electrons want to be near the proton, so they spin around the nucleus (which is where the protons are). To know exactly why they spin around the nucleus and not just crash into it requires more physics than I’m ready to explain at this moment. An introductory course in quantum mechanics will explain this– in fact, this question is exactly what we were trying to answer when we invented quantum mechanics (it’s not as tough as it sounds =] ).

      On a even smaller scale, atoms stick together because of something we call the “strong force.” This is what binds the nucleus together, even though the nucleus, consisting of protons (positively charged) and neutrons (no charge), want to repel itself internally. And actually, atoms don’t always stay together: the nucleus can break apart into smaller nuclei. This is due to something called the “weak force” (Wanna bet which is stronger, the weak force or the strong force? This is why atoms stay together more than they decay.).

      “Is it possible to make a molecule from just protons, electrons, and a nucleus if you can find out how to stick them together?”

      Yes: Hydrogen gas is a molecule of two hydrogen atoms– each consisting of one proton and one electron. You actually need neutrons to help dilute the affects of like-charges-repelling, so atoms larger than Hydrogen (which is all of the other elements) have neutrons. We can get them to stick together by literally smashing two atoms together. The only requirement is that we are careful about what sizes of atoms we throw together. This is how man made elements are made, and how we discovered the last 30 or so elements on the periodic table.

      “Where do protons and electrons come from?”

      This is a cosmological question, a lot different from the previous ones. Basically, energy and mass are the same thing (Einstein’s: E=mc^2). After the big bang, there was only energy (heat), and as the universe expanded, the energy became more diluted, that is, it cooled. Eventually it cooled to a point that E=mc^2 could work, and the energy formed mass, and from this protons and electrons formed.

      This is very much an overview and not at all truly answer why the stuff you asked about is. If you’re still curious, I’d recommend a chemistry class for the bonding stuff. For the weak and strong stuff, you need nuclear physics (which require quantum mechanics). The chemistry class will probably be most accessible and the best place to start, as the physics requires lots of work building up. Although, if you do go the physics route, you will learn about magnets before you get too far in.

      I’d also recommend Carl Sagan’s Cosmos; I haven’t seen it all, but I know some of this stuff is covered, particularly the cosmology. You might also enjoy the book The Disappearing Spoon by Sam Kean; which gives a brief intro to the ideas of chemistry before doing an historical overview of the periodic table.

      The entire interview with Richard Feynman can be watched for free here:

      http://www.ted.com/talks/lang/eng/richard_feynman.html

      • Danny Wuvs Kittens

        Holy shit, that’s a lot of info. Looks like I’ve got something to do in my freetime!

      • Michael

        When atoms bound together (share their orbiting electrons with other atoms), they form some sort of structure. This has structure has gaps in between the molecules, so only things smaller can pass through.

        Actually, other electrons can occupy the same space, they just have to be in higher energy orbitals (cf. Pauli exclusion principle). Note also that all orbitals technically span all of space, so it’s hard to get a good definition of “gaps” in this context.

        Electrons are on the outsides of molecules and atoms (which is why electrons are shared when atoms and molecules bond together). We are made of atoms and molecules and so is everything else, therefore, when are electrons get close to the electrons of objects, they repel. The scale on which this happens is really really really small, so it appears, to us, that we are touching the object.

        This is indeed the microscopic description of the “normal force” (which is what you are describing).

        “…(why do atoms bond when they’re heated, like with plastic or metal?)”

        I’m not exactly sure what you mean by this. Metals melt when heated (at the right pressure), as do most substances, but this isn’t a chemical change. No bonds are broken or formed.

        However, all chemical reactions do require a minimum energy, called an “activation energy.” This is because bonds in a reaction are broken then reformed, and breaking bonds takes energy. Temperature is simply a measure of the RMS kinetic energy of the molecules, so the rate of reaction depends on temperature. However, the equilibrium point does not (generally).

        Basically, energy and mass are the same thing (Einstein’s: E=mc^2).

        That is to say, massive objects have an invariant energy. They also have kinetic energy, which is only really “mass” if you use a different definition of “mass” from that normally used.

        After the big bang, there was only energy (heat), and as the universe expanded, the energy became more diluted, that is, it cooled.

        This makes no sense. For one thing, “heat” (or thermal energy) is a macroscopic phenomenon; it is really kinetic energy of individual molecules and atoms. Without particles, there is no heat.

        Eventually it cooled to a point that E=mc^2 could work, and the energy formed mass, and from this protons and electrons formed.

        This also butchers SR pretty badly. For one thing, E = mc^2 only “works” at extremely low speeds, since otherwise the next term, 1/2 mv^2, will be significant. Second, mass-energy equivalence in no way implies that one particle can automagically turn into another simply because they have the same energy, nor that any particle can miraculously appear from a positive-energy gauge field.

        The first particles in the universe were likely bosons, of which there may have been just one type. (It is generally assumed that eventually we will construct a consistent theory of quantum gravity in which all four forces are unified. Grand unified theories (GUTs) of the other three forces are fairly developed already, and electroweak theory is very well established and tested.) As the universe expanded and the energy (due to gauge interactions on small scales) declined, the symmetry would break, first with gravity separating from the other GUT force, followed by the strong force from the electroweak force, and finally the weak force from electromagnetism. But that last symmetry-breaking is the most interesting, because the weak bosons (+W, -W, and Z) all have mass, while photons (and gluons and gravitons) do not. So there must be some mechanism (called the Higgs mechanism) that gives these bosons mass.

        It is a common idea that this same mechanism should account for the origin of fermion masses. However, this alone does not explain where elementary fermions (spin-1/2) particles came from in the first place. I frankly don’t know what the explanation for this is supposed to be. Currently there are 24 known fermions (6 quarks, 6 antiquarks, 6 leptons, and 6 antileptons), all of which need to somehow be accounted for.

        • Paul

          Since Danny seemed new to the topic of atomic forces, I thought I’d keep things simple and general. I figured that the Pauli Exclusion Principle, although a beautiful and relevant theory, would be superfluous for a first round in atomic theory. You are correct about the different orbitals spanning all space and having non-intuitive structure, but the gaps are well defined as those are where the nodes in the electron clouds probability function exist (ie where the probability is zero, and yes the mathematics work out this way especially for the lower quantum numbers).

          Technically the relativistic correct expression for total energy is (gamma)mc^2, but most people are quite familiar with the iconic mc^2, which is correct for rest mass. In the broad view, without getting into gauge theories, the universe expanded causing cooling of the early universe allowing particles to form– first a quark gluon plasma and then after further cooling were these particles able to combine. I did not want to delve into symmetry breaking processes; this is still pertinent, just not for a first go.

          Also, my use of “heat” is accurate. Heat is defined to be the transfer of thermal energy, which includes not just kinetic thermal energy as you described but also radiant energy. Photons would qualify as both heat and thermal energy.

          • Michael

            Your usage of heat was not correct, though. You said the universe was “only energy,” which would imply there were no (non-virtual) particles, and so no energy transfer. You also claimed that the entire universe was made of heat, which is clearly false as the majority of the energy of the early universe came from quantum-scale interactions.

            I mean, I’m all for simplicity, but I don’t understand the idea that the early universe was “just heat” in any sense or at any level.

    • JK

      Hi Danny

      Feynman was a genius. That should sum it up :).

      If you like the video, you surely will like one of Feynman’s books “Surely You’re Joking, Mr. Feynman! (Adventures of a Curious Character)” too:
      http://www.amazon.com/Surely-Feynman-Adventures-Curious-Character/dp/0393316041/ref=sr_1_1?ie=UTF8&qid=1295254151&sr=8-1

      Have fun reading it (I had for my part).

  • Custador

    Iirc from A-Level physics, it’s a manifestation of interactions of electromagnetic force due to how electrons align in crystaline metals.

  • Elemenope

    Surely you’re joking!

    • Custador

      I’m not joking. And don’t call me Shirly.

      • Elemenope

        No, no. Not you.

        Him.

        • Custador

          Can I still have a cookie for the Leslie Nielson joke?

          • Elemenope

            Of course!

          • Jabster

            “cookie”

            Come now Custy, as an Englishman you know full well it’s a biscuit and not a cookie. There is some merit in modifying your language so that those from the colonies can understand but some things are just going a step to far …

  • Paul

    Ah, Feynman… the only person capable of out doing Sagan’s explanatory powers…

    • dutchhobbit

      Not really true. Carl Sagan does not leave you with the feeling of confusion you get with Feynman and takes less time to say that he does not really know, or does not understand your question.

      • Michael

        It’s not that Feynman can’t give a better answer that he did, it’s that an accurate answer that the questioner would find satisfactory satisfactory requires a lot more education than he had time for.

  • trj

    To those interested in how it f*cking works, here’s a good explanation: http://science.howstuffworks.com/magnet3.htm

    • http://lydiafromtexas.wordpress.com/ LRA

      (Also, wikipedia has an article on magnets.)

      • wintermute

        “Wikipedia has an article on x” is true, where x is any statement.

        Proof: http://en.wikipedia.org/wiki/List_of_fictional_pigs

        • Elemenope

          LOL. It’s actually failed me occasionally (on really obscure legal terms, and some other professional terms of art), but so rarely as to be negligible.

          Also, some articles are informationless stubs.

        • Jerdog

          Hmm… that would make a good Sporcle quiz.

        • Elliott

          ∀x(Wikipedia(y)→has,on(y,x))

          Believe that’s right. My predicate calculus is rusty.

          • Michael

            Probably you want something like ∀x(⊤→Wikipedia(x)), or more simply, ∀x Wikipedia(x), where Wikipedia is the property of Wikipedia having an article on.


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