Bruno Maddox and the Magnet: A Story of Misconceptions

Insane Clown Posse certainly wonders how magnets work.
Insane Clown Posse certainly wonders how magnets work.

This week the ever-inquisitive Gary Matthews pointed me to a 2008 article for Discover Magazine by Bruno Maddox, claiming that physicists cannot explain how magnetism works, and that they are in denial about it. I encourage you to read the article. Maddox is wrong—dead wrong—but his argument displays a number of common misconceptions about science. And I’d like to address some of them. The most important misconceptions Maddox displays are that of first cause, of classical intuition, and of distrust of the abstract. Let’s get started.

(DISCLAIMER: The opinions in this article are my own. I will be describing very little real science here… just philosophy.)

The Misconception of First Cause

Early in his article, claims that nobody can explain how a magnet works and that nobody seems to be particularly bothered by this.

For one thing, as far as I can tell, nobody knows how a magnet can move a piece of metal without touching it.

Maddox writes

And for another—more astonishing still, perhaps—nobody seems to care.

I want to talk about the notion of “touch” later. But for now let’s focus on the other part of that quote—that nobody seems to care. What Maddox is getting at, I think, is that science can never answer why something happens… at a fundamental level, it can only offer descriptions and make predictions. It can only tell you how something happens.

A Hypothetical Conversation

Let’s imagine, for a moment, a hypothetical conversation between Maddox and a physicist. If he asks about magnets… the physicist will say something like “oh the electromagnetic force is caused by the magnetic field.”

“Okay, so what causes the magnetic field?” Maddox might ask. And to this a physicist might say “Well, the magnetic field is really a relativistic echo of this more fundamental thing, the electromagnetic field tensor. A magnetic field is created by moving charge… but that motion depends on your point of view. The field tensor is invariant.”

Maddox might push further. “What causes that?” And a physicist might tell him that it’s a low-energy limit of the electroweak force.

Maddox, getting really aggravated now, might push again. “But what causes that?” And the physicist, depending on her leanings on quantum gravity, would give him an unworried shrug. “We don’t know. It just is.”

What’s Wrong With Maddox’s Question

Do you see the problem? It’s the same problem as in theology. If you ascribe cause to something, then you must ask what causes the cause. One (very theological) answer is that God is infinite and can get around these petty problems like cause and effect.

But science has a better answer: we don’t know! And moreover, we cannot know! At a fundamental level, science is based on observations of the world around us. We are limited by what those observations can tell us. These observations can tell us a lot. They can tell us what happens—to bars of iron can be made to pull at each other. They can tell us how it happens—the bars attract if they are oriented in a particular way, otherwise they repel. And, with a bit of cleverness, they can give us the tools to make predictions—an electric current will attract an iron bar.

But observations, at some level, will fail to explain something. And that’s perfectly okay. In fact, it’s better than okay. It’s a good thing to know your limits! And this is a fundamental limit. The success of science is built on knowing that whatever Nature does must be the truth, no matter how counter-intuitive.

I believe Maddox knows this. He certainly lampshades it when he comments that

But as far as I can tell—and isn’t the point of science that all its bigger propositions come accompanied by this noble caveat?—[Steven Weinberg] really can’t [explain how magnets work].

But Maddox sees this as a reason to distrust science and it is not. It is science’s greatest strength.

(I don’t mean to imply that science has no explanatory power. It tells us that magnetism in a bar magnet is caused by either atomic spin or electron spin, for example… which is very powerful. But at some point, the chain of causes stops and you can go no further.)

The Misconception of Classical Intuition

Let’s reflect on that for a moment. Whatever Nature does must be truth, no matter how counter-intuitive. This is the second misconception Maddox displays. Maddox finds it unsettling that we cannot explain “how a magnet can move a piece of metal without touching it.”

But… what does it mean to touch? Let’s think about the subatomic realm, the world of quantum mechanics. In the world of atoms and electrons, “touch” is a fuzzy concept. For one thing, there is no such thing as a “particle.” Protons, electrons, neutrons, and even atoms and molecules, are not localized balls, like we’re used to in our world. They’re waves of probability, distributed throughout space. What this means to us in the world of trains and aeroplanes is not totally clear. But it is the nature of Nature. So particles them, aren’t really particles.

For another thing, when we “touch” a table, there’s a lot of empty space between the atoms in our hands and the atoms in the table! What’s really happening is that the atoms in our hands are repelling the atoms in the table… for a variety of reasons, including the electromagnetic force and the Pauli exclusion principle. There’s none of the “touching” Maddox seeks at all! Maddox is disturbed by the idea that we appeal to “spooky action at a distance,” but a more interesting question is are there any forces that aren’t, fundamentally, this sort of spooky action at a distance.

(As a historical note, Einstein described quantum mechanics as “spooky action at a distance” because he was disturbed by the fact that quantum entanglement seemed to violate causality. We know now that it does not violate causality and Einstein was worried for nothing. But the electromagnetic force never bothered Einstein.)

Maddox is falling prey to the fallacy of classical intuition. He believes that because he experiences the world in a particular way, the world must be that particular way. But Nature is not so gentle! We evolved to perceive the world in a way that benefits us evolutionarily… not in the way it really is! Again, the great strength of science as a methodology is that it overcomes this classical intuition and allows us to glimpse the world as it really is. (Or at least, closer to how it really is.)

A Fallacious Distrust of the Abstract

Finally, Maddox says that

When you get right down to it, the mystery of magnets interacting with each other at a distance has been explained in terms of virtual photons, incredibly small and unapologetically imaginary particles interacting with each other at a distance. As far as I can tell, these virtual particles are composed entirely of math and exist solely to fill otherwise embarrassing gaps in physics, such as the attraction and repulsion between magnets.

Well, Maddox is right about one thing. Virtual particles are unapologetically imaginary. This is a complaint that I, and many other scientists, share with Maddox. But this isn’t a problem with the science. It’s a problem with lazy science communication.

As I described above, the notion of a particle is deeply misguiding. A particle is a “human-scale” approximation of the true nature of reality, which is made up fields and waves. Really, force isn’t carried by virtual particles. It’s carried by fields, which interact with each other via waves that travel at speeds no greater than the speed of light. And it just so happens that these waves look like particles to us if we squint. But this doesn’t work all the time. Sometimes the notion of a single particle simply doesn’t make sense.

But, even in the realm of subatomic physics, the idea of a particle is very powerful. It provides intuition and a surprisingly robust computational tool. This is why, historically, high-energy physics has been misleadingly called “particle physics.” (And for those in the know, how the terrible name “second quantization” came to be.) And the notion of a virtual particle, an imaginary particle associated with the excitation of a quantum field, even more powerful.

So… if it makes good predictions…. is a virtual particle really imaginary? Or is it a valid way of interpreting the fundamental nature of reality?

The answer is that, despite my distaste for virtual particles… they’re often exactly as good of a description as waves—better, because they’re easy to work with. It’s true that the description fails sometimes, but so what?

(For experts, I’m discussing the occupation-number formalism of quantum field theory, vs. other formalisms. In particular, the occupation number formalism fails when a vacuum cannot be uniquely defined… a la Unruh effect or curved spacetime.)

This is why Maddox is wrong to distrust virtual particles. Maddox’s distrust seems to stem from the fact that virtual particles are purely mathematical and that there is a more general way to describe quantum fields. But he should not distrust this mathematical abstraction. It is the tool we use to make predictions.

Moreover, it’s the only tool we have. Scientists are not explaining why phenomena occur. Really what scientists do is build Lego models of the universe, simulacra that behave like the universe and allow us to make predictions. Equations and mathematical abstraction are the Lego blocks of our models. And the particle picture of quantum field theory is a very good model indeed.

Other Rebuttals

Maddox’s post is quite old… seven years old by now. I am not the first scientist to refute him. In particular, I’d like to recommend this blog post by Sabine Hossenfelder, which is, as usual, excellent.

8 thoughts on “Bruno Maddox and the Magnet: A Story of Misconceptions

  1. I am not a scientist, nor even anything close to it, and I love this article. I find it incredibly interesting how much Newtonian science cannot explain, therefore it’s not “real” science. We cannot adequately explain how the fetus forms either, yet somehow pathways of information form and one cell divides and separates into trillions of cells—each knowing exactly what to do. We cannot explain that either, yet people are confident they are here.

    You always make me think Jonah. Thank you.

    1. Thanks for reading, Lisa! I’m glad you liked it! 🙂

      I hope I haven’t given you the impression that Newtonian science isn’t “real science.” It’s very good science. At the level of cars and buses and aeroplanes, it does a very good job of describing reality. And describing reality is the best and only reason for physicists to like theory.

      But it’s simply not complete. And trying to carry out Newtonian understanding to the quantum realm leads to faulty reasoning.

  2. I would agree with Maddux on this one, no one fully understands the “how” or “why” of permanent magnets. If you were to hold two magnets close together but leave a gap between them, what is in that gap? There are no particles going back and forth since they interact in a way that is faster than the speed of light. There is nothing you could place between them that will block this interaction, it’s like they know. Electromagnets are understood, there is a flow of electrons and you can shield one from another, but not permanent magnets. So without knowing what is in that gap, there is no understanding of “how” or “why”. Any explanation with the word “quantum” in it is pure opinion, and that’s a FACT, a word this author resorted to 8 times.

    1. Thanks for reading, Dan.

      First, it’s true that quantum mechanics is often misunderstood in pop culture, and thus many people use the word “quantum” as a placeholder for “magic.” But quantum mechanics is one of the best-tested, most experimentally robust theories of all time. We’ve confirmed the predictions of quantum field theory to more than thirty decimal places. And I’d like to gently remind you that the computer you used to write that comment is built on transistors, which rely on quantum-mechanical effects and could not be created without a firm understanding of quantum mechanics. So no, not all explanations with the word “quantum” in them are opinion. They’re based, as I said, on observing the universe and accepting what it has to say about itself.

      Regarding “permanent” magnets. You’re thinking of Ferromagnets. And, to a good approximation, they can be well-understood via current loops. A block of iron is a crystal lattice of iron atoms. And each atom has electrons around it. Unpaired electrons (remember your chemistry) have a quantum property called spin, which produces a magnetic field. But if you don’t want to buy into that, imagine that they’re spinning spheres. And since they’re charged, that means they have a current loop. If they align in the lattice all in the same direction, that produces a net magnetic field.

      All materials have these electrons. But ferromagnets have the right crystalline structure so that if all the little current loops get aligned, it’s hard for them to randomize and get un-aligned. So to create a ferromagnet, you apply a strong magnetic field to a block of iron, which aligns all the little current loops. Then it’s stuck like that.

      Also, magnetic interaction is most definitely NOT faster than the speed of light. I’m not sure where you got that idea. Magnetic and electric forces are transmitted at exactly the speed of light. Indeed, they are the root CAUSE of light. Photons are made up of electric and magnetic fields mixing together and feeding into each other.

      1. Hey, thanks for replying. You dodged around the very thing Bruno and I feel no one fully understands, permanent magnets. They are real things made from ferromagnetic material. I’m no expert, like Bruno, so be forgiving and understand that I’m not trying to act smart, I just really want to know. What I want to understand is the field around a permanent magnet. Are there particles with mass circling around it in the field? Just saying “one side is positive and one side is negative and they attract….” doesn’t cut it. I want to know exactly what is going on in the space between two magnets. If there aren’t particles with mass, then what is transferring between the two? If the interaction has no particles then it’s not a wave and it’s not bound by the rules of special relativity or the speed of light like an electromagnetic wave is right? Just so you don’t think I’m completely crazy, I understand that magnets follow all the rules of physics, but they seam to be warping space-time in a way that isn’t understood yet. You can get extra bonus points for explaining why an inch of lead placed between two magnets does nothing at all.

        1. Hi Dan,

          So you are indeed upset by the “action at a distance” bit. Let me clarify a few things and then offer the best brief explanation I can.

          First, you seem to be under the impression that electromagnets and ferromagnets are different… They’re not really. My above comment was meant to show you that you can really think of a ferromagnet as a collection of many tiny, semi-permanent electromagnets, each of which is a tiny bit of electric current, which creates a magnetic field.

          Second, you seem to be under the impression that magnetic force acts instantaneously. This is absolutely not true. Magnetic force “travels” at the speed of light. When you turn on a flashlight, the light appears to instantaneously travel to your eye. But you know that the light actually has to take time to get there. It only appears instantaneous because we don’t perceive time scales short enough to catch the light “in-flight.”

          Similarly, the magnets APPEAR to interact instantaneously. But they don’t. It takes time for the information about one magnet to reach the other. As we will see, given my explanation below, that’s perhaps not surprising.

          So, you ask what’s “between” two magnets. I can answer in two ways. And they’re related. The first is that there’s this stuff, called a magnetic field, between the two magnets. You can’t see it or touch it, but it’s there, filling the space. We can intuit the existence of the field by its interactions with other things, like electric charge and permanent magnets. You may find this answer unsatisfactory, but we observe its presence, so we are forced to acknowledge its existence, regardless of our preferences. That’s how science works. And that’s a big part of what I was saying in my article.

          But I just told you that it takes time for one magnet to notice the other. So if there’s a magnetic field between them, how does that work? The answer is that changes in the magnetic field travel at the speed of light, as waves. Indeed, they ARE light waves. The magnetic field is one side of a two-sided coin: the electromagnetic field, which is what light is made of.

          So in this sense, there are actually particles travelling between the two magnets, photons, which carry the information about the magnetic field. Since these photons aren’t localized as particles, we usually call them “virtual photons.”

          I hope that helps.

What do you think?