Defying Gravity: How Rotating Magnets Unlock Stable Levitation

If someone saw a magnet levitating above another without any visible support, surprise would be a natural reaction. This striking phenomenon was recently confirmed by researchers at the Technical University of Denmark, who demonstrated that when one magnet rotates beneath another, the upper magnet can float stably, defying what we understand about traditional magnetic forces. The experiment points to the existence of a new physical mechanism beyond the familiar static magnetic repulsion.

First, the traditional magnetic levitation technology we know is implemented using superconductors or precisely controlled electromagnets, and requires a highly controlled environment and a multi-axis stabilization system. In these systems, objects are levitated by the static magnetostatic force between magnets, but complex reaction control circuits are essential to create a stable levitation state. This is due to Earnshaw's theorem, which states that electrostatic or static magnetostatic forces alone cannot form a stable peak in all three directions. That is, no object can remain suspended in midair and levitate between simple permanent magnets.

However, the situation changes completely when a rotating magnet appears. When a magnet rotates at high speed, the magnetic field created around it constantly changes with time. This time-varying magnetic field generates an induced current inside the surrounding magnets or conductors. The induced current generates a magnetic field that acts in a direction that opposes the change in the original magnetic field, and thus, a complex interaction occurs between the two magnets. In particular, the magnet floating above is continuously subjected to a rotational torque by the time-varying magnetic field of the rotating magnet, and under certain conditions, it synchronizes the dynamic magnetic field and rotational motion of the rotating magnet.

In this state of synchronization, the upper magnet rotates while maintaining a constant relative phase with the lower magnet. At this time, the position occupied by the levitated magnet is not a simple point of magnetic equilibrium, but an energy minimum point with dynamic stability. At this point, gravity and magnetic induction cancel each other out, and as long as the magnet continues to rotate, it can maintain a stable altitude and posture. In this way, in a non-conservative system where the induced current created by the time-varying magnetic field and the reverse magnetic field formed by it interact, a new type of stable state that cannot exist in a static system is possible.

What is more interesting is that this phenomenon can be explained by a nonlinear dynamical system. The magnetic field change of the rotating magnet is not linear, and the electromagnetic response appears differently depending on the posture, rotation speed, and position of the upper magnet. Under these conditions, the upper magnet gradually stabilizes in the direction of minimizing energy loss and being aligned by the magnetic field, and eventually reaches a state where it maintains a constant altitude and angular momentum. This process can be understood as a spontaneous stabilization phenomenon of a magnetic system that naturally self-aligns without any external control.

This magnetic levitation principle suggests various technological applications. First, it can be applied to a frictionless bearing system that can support a rotating body in the air. Such a system can reduce friction and vibration and minimize energy loss in high-speed rotating equipment or precision machine tools. Second, based on the position stability and vibration-damping characteristics, it can be utilized in precision sensors or fine-position control devices, and the characteristic of being able to float stably only at a specific location can also be applied to self-aligning equipment or signal filtering devices. Finally, the fact that levitation can be implemented using only a rotating magnet can suggest a new direction for the design of next-generation magnetic levitation vehicles or floating robots. In particular, the fact that an object can be levitated using only a simple rotating body without complex electronic control provides great advantages in terms of cost reduction and system simplification. In short, the magnetic levitation phenomenon created by a rotating magnet can be said to be a new extension of physical principles. An equilibrium state that could not be established in a classical conservative system was realized in reality through the dynamic reaction of a magnetic field and magnets that change over time. This is an example of nonlinear interaction that appears at the intersection of classical mechanics and electromagnetism, and an example that shows how much science can create a new order under the conditions of motion and change. This small experiment opens up completely new possibilities in technology and physics beyond the world of magnets that we know.