Citizen Science #21 by Jamie Zvirzdin

Energy Demystified: The Real Attraction of Magnetic Energy

I’ve been mesmerized by magnets since I was a little girl. They seem like magic: They stick notes to our fridges, help our earbuds play great tunes, even help doctors see the difference between normal brain tissue and a growing tumor, through MRI (magnetic resonance imaging) scans. But can magnets heal us if we wear them? That’s where things get a bit rough, and we must look carefully at the claims and at the science behind magnetic energy.

I once saw a magazine ad claiming a magnetic bracelet would heal my pain. Conveniently for the seller, the bracelet was also expensive. Proponents of this “ionized jewelry” claim these magnets can improve blood flow, reduce pain and balance your body’s energy fields. This may sound too good to be true, and it is: There’s just no scientific proof backing these claims beyond a simple placebo effect (See Citizen Science article #5 on AllOtsego.com for more about the placebo effect). The hemoglobin in our blood contains iron, but it’s not ferromagnetic and isn’t affected by the weak magnetic fields of bracelets.

Magnets are marvelous, but it is unethical to swindle people out of their hard-earned money by promising miracles. To protect ourselves from such pseudoscience, let’s get into the physics of magnetic energy and see what is really happening.

Magnetic energy is the energy stored in a magnetic field. But what do we mean by that? How do we measure it? At the heart of magnetic energy is something called the magnetic dipole moment, or just “magnetic moment” for short. Think of your refrigerator door: It is usually made of steel, which contains iron. Each iron atom is like a tiny bar magnet itself, with a north and south pole. The electrons swirling around each iron nucleus determine that atom’s orientation in space—that is, the electrons influence the direction of the iron atom’s magnetic moment through electron orbital motion and intrinsic spin, which we can calculate using quantum mechanics.

When these tiny atom-magnets in your refrigerator door encounter a magnetic field—say, from a fridge magnet—they get yanked into alignment, like little compasses lining up with Earth’s magnetic field. The stronger the magnet, the more whole groups of iron atoms (“domains”) are pulled into alignment. And when enough of these domains align with the magnet’s field, they effectively become little magnets themselves. South poles of the iron atoms will connect to north poles of the fridge magnet (or vice versa, or both; fridge magnets often alternate poles in what is called the Halbach array), and the magnet now sticks to the fridge.

It is that pulling force, called torque, which creates stored magnetic energy, like pulling on the handle of an old slot machine, rotating it out of its resting position. If you let go, the energy will be released and it will spring back.

Let’s pretend we have a strong fridge magnet whose fridge-facing surface produces a magnetic field (symbol B, in bold to show that its direction matters) of around 0.01 teslas (T). A fridge magnet like that might have a magnetic moment (symbol m) on the order of 0.01 Ampere-square meters (A ⋅ m^2). We can calculate the magnetic potential energy E of the fridge-magnet system using the equation

E = −m ⋅ B,

where the negative sign tells us about the direction of the alignment.If we assume that the magnetic moment is aligned with the magnetic field, giving us the maximum value of energy, then

E = −(0.01 A ⋅ m^2) ⋅ (0.01 T) = −0.0001 joules.

This is enough to make the magnet stick, but it’s not very much energy. In contrast, when you are put inside the superconducting magnet of an MRI machine, the protons or hydrogen atoms in your body are going to experience a magnetic field of around 1.5 to 3 teslas, a much stronger magnetic field than anything a fridge magnet or magnetic bracelet could produce.

According to a 2017 article published in the scientific journal “Superconductor Science and Technology,” commercial MRI machines with a magnetic field of 1.5 teslas give us a magnetic potential energy of 2,000,000 to 3,000,000 joules. That’s quite a difference.

And when the MRI scan is over, the hydrogen atoms in your body release their borrowed energy, producing an image of your body doctors can examine for problems. Your atoms quickly return to their normal, random orientations without any lasting effects. If you’re not affected by the magnetic field of an incredibly powerful superconducting MRI, then surely the claims about healing magnetic bracelets are worthless.

In the 18th century, Franz Mesmer claimed that a mysterious magnetic force—animal magnetism—could heal and balance the body, a concept long debunked as pseudoscience. Today’s sellers of magnetic bracelets are merely repackaging these old myths in shiny new wrappers. The true power of magnets lies in MRI technology, where they help doctors diagnose serious conditions—not in flimsy wristbands.

And when it comes to easing chronic pain or finding peace in the chaos of life, forget the bracelets (and the crystals, and the homeopathic remedies, and all other pseudoscientific practices) and reach for your earbuds instead. As the current flows through a coil inside, it creates a magnetic field, moving a thin membrane to produce the soothing sounds of your favorite music. Unlike those bracelets, music therapy is a proven, affordable way to complement traditional pain management. Magnets are indeed marvelous—when used wisely.

Jamie Zvirzdin researches cosmic rays with the Telescope Array Project, teaches science writing at Johns Hopkins University and is the author of “Subatomic Writing.”