Physics Breakthrough at University of Konstanz Overturns Amontons’ 300-Year-Old Law of Sliding Friction

University of Konstanz researchers discover a magnetic friction mechanism that defies Amontons' law, showing friction doesn't always increase with load.

By: AXL Media

Published: Mar 18, 2026, 9:45 AM EDT

Source: Information for this report was sourced from University of Konstanz

Deconstructing a Fundamental Pillar of Classical Physics

For more than three centuries, Amontons’ law has served as a foundational principle of physics, positing that friction between two surfaces increases proportionally with the load applied to them. This empirical law reflects the common experience that a heavier object is more difficult to slide across a floor than a lighter one, a phenomenon typically attributed to the microscopic deformation of contact points. However, a pioneering study from the University of Konstanz, published by researchers led by Professor Clemens Bechinger, has identified a regime where this rule fails. By utilizing magnetic coupling rather than physical contact, the team demonstrated that friction can actually decrease as the effective load increases, challenging the universal applicability of one of the oldest laws in science.

Exploring Friction Through Contactless Magnetic Reorganization

To investigate the limits of classical friction, the research team designed a tabletop experiment consisting of two magnetic layers that never physically touch. The upper layer is composed of a two dimensional array of freely rotating magnets, while the lower layer remains fixed. As the layers move relative to each other, the magnetic coupling creates a measurable resistance to motion, known as contactless friction. This experimental setup allowed the scientists to bypass the interference of surface roughness and material wear, focusing instead on how internal configurations respond to movement. By adjusting the distance between the layers, they could precisely tune the effective load and observe the resulting collective dynamics of the magnetic moments.

The Role of Magnetic Frustration in Energy Dissipation

The most striking finding of the study was the non-monotonic behavior of the friction force. According to Amontons’ law, decreasing the distance between the layers—thereby increasing the load—should steadily increase friction. Instead, the researchers observed a pronounced maximum at intermediate distances. This occurs because of "magnetic frustration," a state where competing interactions force the magnets into unstable configurations. The top layer naturally favors an antiparallel alignment, while the bottom layer pulls the magnets toward a parallel arrangement. This incompatibility drives a constant, hysteretic reorganization of th...