Scientists have uncovered the real reason why ice is slippery

However, a new study by physicists from Saarland University challenges this longstanding scientific stereotype.

According to data published in Physical Review Letters, the cause of sliding on ice is not pressure or heat from the sole of the shoe, but the interaction of molecular dipoles - on the surface of the ice and on the sole of the object in contact.

Professor Martin Müser used computer modelling to follow the breakdown of the ice crystal lattice. His conclusion: it is dipole interactions that disrupt the ordered structure of water molecules, causing the formation of an amorphous, liquid-like layer on which we slide.

To understand this phenomenon, we need to remember that ice is a structure in which water molecules (H₂O) form a rigid lattice orientated in a specific order.

When a person steps on ice, the interaction of the dipoles in the sole of the shoe with the dipoles on the ice surface disrupts this order. What emerges is the so-called "frustrated state," a term from physics that refers to the inability to achieve a stable configuration due to competing forces. As a result, an unstable liquid layer forms at the ice-shoe interface.

Thus, the claim made by James Thompson, Lord Kelvin's brother, almost 200 years ago - that ice is slippery due to pressure and friction - has been recognised as outdated.

The researchers have also disproved another idea: that skiing at temperatures below -40 °C is impossible because no slippery water layer forms. In fact, dipole interactions continue to operate even at extreme cold, although the liquid layer becomes thick as honey and almost unsuitable for skiing.

According to Müser, this discovery is of great importance not only for basic science, but also for applied fields - for example, the manufacture of sports equipment, footwear and risk assessment on slippery surfaces.