In 2021, Turkish scientist Hamdi Ucar discovered a new form of magnetic levitation, in which rapidly rotating magnets levitate nearby magnets. Professor Rasmus-Björk and his team replicated and studied this phenomenon, which defies classical physics. They found that the levitating magnets aligned with the rotating magnets, creating a state of equilibrium similar to that of a top.
Scientists at the Technical University of Denmark (DTU) have confirmed the basic physics behind the newly discovered phenomenon of magnet levitation.
In 2021, a scientist from Turkey published a research paper detailing an experiment: attaching a magnet to a motor to make it spin rapidly. As the device approached the second magnet, the second magnet began to rotate and suddenly hovered in a fixed position a few centimeters away.
While magnetic levitation is nothing new—the best-known example is probably the maglev train, which relies on powerful magnets for lift and propulsion—the experiment has puzzled physicists because the phenomenon is not described by classical physics, or at least not by any known mechanism of magnetic levitation.
However, now is the time. Rasmus Bjørk, a professor at the School of Energy at DTU, was very interested in Uka's experiment, so he replicated the experiment with master student Joachim M. Hermansen and clarified the specific process of the experiment. Rasmus Bjørk said that copying is easy and can be done using off-the-shelf components, but the physics behind it are strange:
"Magnets shouldn't hover when they're close. Normally, they either attract or repel each other. But it turns out that if you rotate one of the magnets, you can achieve hovering. That's where it gets weird," he said. "The forces affecting the magnets shouldn't change because you rotate one of the magnets, so there seems to be a coupling between motion and magnetism."
These results were recently published in the journal Applied Physics Reviews.
Multiple experiments confirm physical principles
The experiment involved several magnets of different sizes, but the principle was the same: By spinning one magnet quickly, the researchers observed how another magnet, known as a "floating magnet," began spinning at the same speed while quickly locking into one position, maintaining a hovering state.
They found that when the float magnet locks into position, it is oriented close to the axis of rotation, toward the same poles of the rotor magnet. So, for example, the north pole of the floating magnet keeps pointing toward the north pole of the stationary magnet as it rotates.
This is different from what would be expected from the laws of magnetostatics, which explain how static magnetic systems operate. However, it turns out that the magnetostatic interaction between the rotating magnets is what produces the float's equilibrium position, which is what Frederik L. Durhuus, a doctoral student and co-author of the study, discovered by simulating this phenomenon. They observed a significant impact of magnet size on levitation dynamics: smaller magnets require higher rotational speeds to levitate due to their greater inertia and are more buoyant.
"It turns out that the float magnet wants to align with the spinning magnet, but it doesn't spin fast enough. As long as this coupling is maintained, it hovers or floats," Rasmus-Bjork said. "We can compare it to a spinning top. If it's not spinning, it doesn't stand, but locks into position by spinning. Only when the rotation loses energy will gravity - or in our case the push and pull of the magnets - be large enough to overcome equilibrium."
Compiled source: ScitechDaily