Scientists used molecular simulations to study how ice changes when something slides over it, and their findings challenge previous ideas about why ice has such low friction.
Why Does Ice Feel So Slippery?: A Molecular Mystery Solved
Wondered why it’s so easy to slip and slide on ice? For years, scientists have grappled with this seemingly simple question. While we intuitively know that the presence of water plays a crucial role, the exact mechanisms that lead to low friction between ice and other surfaces have remained elusive. However, recent research may finally shed light on this long-standing scientific enigma.
Why Does Ice Feel So Slippery?
Ice is famous for being slippery, but the reason behind this smooth-slide sensation is more complex than it seems. Many believe that a thin layer of water on the ice surface makes it slick. But recent studies show this might not be the whole truth. Scientists used molecular simulations to study how ice changes when something slides over it. Their findings challenge previous ideas about why ice has such low friction.
The Science Behind Ice’s Slippery Surface
What Happens Underneath?
For a long time, experts thought ice became slippery because of pressure melting, where the pressure from your foot or a skate blade melts some ice into water. Others suggested that sliding creates enough heat to melt ice temporarily, a phenomenon known as frictional melting. However, experiments show that these processes don’t always happen or explain all cases, especially at freezing temperatures.
The Real Cause: Cold Amorphization
Recent results reveal that instead of traditional melting, the surface of ice undergoes a change called amorphization. This means the orderly crystal structure breaks down into a disordered, liquid-like state without heating up enough to melt. This happens because sliding causes tiny shifts and displacements in the surface molecules. Similar to what happens in materials like diamond and silicon under stress.
The New Discovery: Molecular Dipoles at Work
The team led by Professor Martin Müser found that molecular dipoles—tiny charges within molecules—are actually responsible for making ice slippery. These dipoles interact between the ice’s surface and materials like shoe soles or skis. When these interactions occur, they disturb the ordered crystalline structure of ice and create a thin liquid layer without any need for pressure or friction.
What Are Dipoles and How Do They Affect Ice?
Understanding Molecular Dipoles
A dipole happens when a molecule has two poles—one slightly positive and one slightly negative charge. Water molecules (H₂O) have this quality because oxygen pulls electrons more strongly than hydrogen atoms do.
Dipole Interactions Disrupt Ice Structure
Ice is made up of water molecules arranged in a neat crystal lattice below freezing temperatures. When an object with its own molecular dipoles touches this lattice, such as your shoe sole or ski equipment, its dipoles interact in complicated ways. These interactions make the previously rigid surface disordered and turn it into a slippery thin film of liquid water.
Skiing at Extreme Cold Temperatures is Still Possible
This research also shows that even at temperatures near absolute zero—which is far colder than anyone imagined—this liquid film still forms beneath skis due to persistent dipole effects. Although at such low temperatures the layer becomes very thick and sticky (much like honey), it proves that sliding is still theoretically possible.
How Water Helps Slide Smoothly
The simulations showed that even though amorphization creates a lubricating layer similar to water, very low friction levels require actual water molecules sliding past surfaces that repel water (hydrophobic surfaces). If the counter-surface attracts too much water or there isn’t enough excess water due to fast sliding speeds or other factors, friction increases.
The Importance for Wintersports and Technology
This finding is important for understanding how skis glide over snow or why car tires slide on icy roads. It also helps engineers design better materials for cold environments by controlling surface properties and managing water presence at tiny scales. Knowing how ice reacts at the molecular level can improve safety gear and sports equipment used in winter conditions.
Reference
- Atila, A., Sukhomlinov, S. V., & Müser, M. H. (2025). Cold self-lubrication of sliding ice. Physical Review Letters, 135(6). https://doi.org/10.1103/1plj-7p4z
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Neha Adikane holds a Master’s degree in Environmental Science from Pune University, bringing a unique blend of scientific expertise and creative writing skills to her craft. She specializes in creating engaging, insightful, and impactful content across various niches. With a passion for translating complex ideas into simple, relatable narratives, she excels at crafting blogs, articles, website content, and social media posts that captivate readers and drive engagement. Neha’s background in environmental science adds depth to her writing, allowing her to effectively cover topics related to sustainability, eco-awareness, and scientific innovations.