We’ve been wrong for 200 years: Belief about why ice is slippery shattered

The concept may seem simple, but for over two centuries the best of the best scientists had it very wrong. Here’s the slippery truth.

Physics just took a face‑plant - just like you probably have when walking too confidently on a patch of snow.

For nearly 200 years, scientists clung to a simple idea: ice is slippery because pressure or friction melts its surface, creating a thin film of water that lets you slide like Mumble from Happy Feet.

But a stunning new study from Saarland University has blown that centuries‑old theory wide open.

It turns out, ice is slippery because of how the tiny magnet-like molecules in the ice interact with whatever is touching it, not because of pressure or friction alone.

These tiny molecules - called dipoles - behave like push‑and‑pull magnets.

When your shoe (or a tyre, or a skiblade or even your finger) touches ice, the dipoles in the contact material tug and twist against the dipoles in the ice surface.

This interaction disrupts the crystalline structure of the ice’s top layer and converts it into a thin, effectively liquid‑like film.

That, not melting, is what makes you slip.

Take a frozen sidewalk, for example: the usual explanation is that your body weight, pressing down, melts a microscopic layer of ice under your shoe.

The new theory is that it’s not pressure or heat creating that change - it’s “molecular mischief” that causes the ice to become “disordered” - aka, liquid.

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The illustration shows what happens on the surface of ice when another object, such as skis, ice skates or shoe soles, comes into contact with it: the previously orderly crystal structure of the water molecules is suddenly disrupted. Picture: AG Mueser

Cold Self‑Lubrication of Sliding Ice by Achraf Atila, Sergey V. Sukhomlinov, and Martin H. Müser - challenges a model originally championed by 19th-century physicist James Thomson (brother of Lord Kelvin - the mind behind the Kelvin scale of temperature).

Thomson’s model claimed that pressure, friction and temperature alone caused ice to melt under force.

“It turns out that neither pressure nor friction plays a particularly significant part in forming the thin liquid layer on ice,” now refutes Müser.

“Instead, computer simulations by the team reveal that dipole (to) dipole interactions (becoming) frustrated - are the key drivers.”

One of the most surprising implications of this discovery is that, contrary to old assumptions, skiing below minus 40 degrees Celsius is not unthinkable.

“Until now, it was assumed impossible because it’s simply too cold for a thin lubricating liquid film to form beneath the skis. That too, it turns out, is incorrect,” explains Müser.

“Dipole interactions persist at extremely low temperatures.”

The film would be more like honey - and skiing on it would still be pretty hazardous, but there you go.

Skiing in extreme temperatures (-40), is now considered possible - but maybe don’t try it. Picture: iStock

You may have heard of the “quasi‑liquid” layer - a super-thin layer of water that exists on the surface of ice, that acts like a lubricant.

That model has dominated textbooks and is probably what you learnt in school: the idea goes that even below freezing, the top molecules are a bit loose and can move, making ice slick.

The Saarland team doesn’t dismiss this layer - instead, they’ve just reframed how it forms.

Their work suggests that instead of melting from heat, the ice surface becomes disordered through molecular movement.

Basically, the molecules get jumbled, creating a slippery, fluid-like layer without any melting.

So in a sense, the “quasi‑liquid” concept still holds - but it’s not melted water - just a movable surface.

Many ice skaters have long described the sensation of ice being simultaneously slick and clingy, especially in extreme cold - so this may explain it.

Slipperiness is believed to be born from subtle, invisible forces called molecular dipoles. Picture: iStock

A popular short video - The Science Behind Slippery Ice: Why Ice Skating Defies Logic - explores the strange duality: the ice feels slick enough to glide over effortlessly, yet somehow grips the blade just enough to carve, stop, and turn.

This meshes beautifully with the Saarland narrative: slipperiness is born from subtle, invisible forces - molecular dipoles doing their dance - much like ice skaters gliding effortlessly across a frozen rink.

For someone nursing an injury after slipping on ice, it probably doesn’t make a difference whether pressure, friction, or dipoles were to blame. But for physics, the distinction is monumental.

The Saarland team’s discovery has turned foundational scientific beliefs on their heads, and winter sports researchers are now rethinking how surfaces, coatings, and shoe or ski materials interact with ice at the molecular level.

This could reshape how we design anti‑slip surfaces, winter footwear, or even better performance gear in frigid environments.

Translation: get ready to see a few more triple axels.

Originally published as We’ve been wrong for 200 years: Belief about why ice is slippery shattered