Solved: How a spinning magnet causes other magnets to levitate

Back in 2021, the Turkish scientist Hamdi Ucar published a paper describing how he attached a magnet to a motor and made it rotate very fast. He then moved it close to a second magnet that started to rotate and suddenly hovered in a fixed position a few centimetres away.

While magnetic levitation is nothing new - the best-known example is probably Maglev trains that rely on a strong magnetic force for lift and propulsion - the experiment puzzled physicists as this phenomenon was not described by classical physics, or, at least, by any known mechanism of magnetic levitation.

It is now, however. Rasmus Bjørk, a professor at DTU Energy, was intrigued by Ucar’s experiment and set out to replicate it with MSc student Joachim M. Hermansen while figuring out exactly what was going on. The replicating was easy and could be done by using off-the-shelf components, but the physics of it was strange, says Rasmus Bjørk:

“Magnets should not hover when they are close together. Usually, they will either attract or repel each other. But if you spin one of the magnets, it turns out, you can achieve this hovering. And that is the strange part. The force affecting the magnets should not change just because you rotate one of them, so it seems there is a coupling between the movement and the magnetic force,” he says.

The results have recently been published in the article 'Magnetic levitation by rotation' in the journal Physics Review Applied. 

Several experiments to confirm the physics

The experiments involved several magnets of differing sizes, but the principle remained the same: By rotating a magnet very fast, the researchers observed how another magnet in close proximity, dubbed a “floater magnet”, started spinning at the same speed while it quickly locked into a position where it stayed hovering.