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Researchers at Saarland University<\/a> have uncovered that ice slipperiness is not caused by pressure or friction. Instead, it\u2019s the interaction between molecular dipoles in the ice and those in materials like shoe soles. <\/p>\n The study challenges a belief rooted in the 19th century, when James Thomson, Lord Kelvin\u2019s brother, first proposed the old theory.<\/p>\n \u201cIt turns out that neither pressure nor friction plays a particularly significant part in forming the thin liquid layer on ice,\u201d said Professor Martin M\u00fcser, who led the research.<\/p>\n Dipoles make ice slippery<\/p>\n So what are dipoles? A dipole forms when a molecule has partial positive and negative charges, creating polarity. Water molecules naturally have this polarity, and in ice they align in a crystalline lattice<\/a>. <\/p>\n When someone steps onto ice, it is not the force of weight but the orientation of dipoles in the shoe sole disrupting the ordered structure of ice molecules. This disturbance causes disorder at the surface.<\/p>\n \u201cIn three dimensions, these dipole-dipole interactions become \u2018frustrated,’\u201d said M\u00fcser. <\/p>\n The result is that the once-orderly lattice breaks down into an amorphous, liquid-like film. This process explains why ice remains treacherously slippery.<\/p>\n Old explanations overturned<\/p>\n The new theory also challenges long-standing explanations involving pressure melting and frictional heating. For decades, scientists debated whether skiers<\/a> glide because pressure lowers the melting point or because frictional heat generates a thin water film.<\/p>\n But simulations show that ice can liquefy without significant heating or pressure. Instead, displacement-driven amorphization occurs. <\/p>\n The crystalline surface becomes disordered purely through sliding motion, with molecules shifting from their fixed lattice positions into unstable, fluid-like arrangements that mimic melting<\/a> yet arise entirely from motion-induced disruptions rather than thermal energy.<\/p>\n In fact, ice at extremely low temperatures can amorphize faster than ice closer to its melting point. This shows that slipperiness does not depend only on thermal effects but on molecular disorder created during sliding. It highlights a deeper physical mechanism that rewrites how scientists understand everyday icy surfaces.<\/p>\n Slippery even in extreme cold<\/p>\n The research also refutes another long-standing belief. \u201cUntil now, it was assumed that skiing below -40\u00b0C (-40\u00b0F) is impossible because it\u2019s simply too cold for a thin lubricating liquid film to form beneath the skis. That, too, it turns out, is incorrect,\u201d M\u00fcser said.<\/p>\n \u201cDipole interactions persist at extremely low temperatures. Remarkably, a liquid film still forms at the interface between ice and ski \u2013 even near absolute zero.\u201d<\/p>\n At such extremes, the film is thicker than honey, making skiing impractical, but the layer still exists.<\/p>\n Surface materials matter<\/p>\n The Saarland study highlights how ice friction<\/a> depends not only on molecular dipoles but also on surface properties. Hydrophobic surfaces, which repel water, reduce friction more effectively than hydrophilic ones, which attract it.<\/p>\n This suggests that the material of skis, skates, or shoes plays a major role in how slippery ice feels. Even with disorder-induced films, friction remains small only if the surfaces allow water to slip easily. <\/p>\n As a result, design choices in sporting equipment, footwear, and transportation materials can directly affect performance, safety, and stability on frozen surfaces during winter and beyond everyday human movement.<\/p>\n Rethinking slippery ice<\/p>\n For everyday life, whether pressure, friction, or dipoles are responsible may not change much for someone who slips on a sidewalk. But in physics, this distinction matters deeply.<\/p>\n The work of M\u00fcser and his colleagues Achraf Atila and Sergey Sukhomlinov overturns nearly two centuries of accepted understanding. <\/p>\n It reveals that slipperiness comes from disorder, not just melting, and that cold ice can lubricate itself by forming amorphous films, reshaping how scientists think about motion, energy<\/a>, and structural changes under stress at the most fundamental molecular scale.<\/p>\n The implications stretch beyond icy sidewalks and ski slopes. They open a new window into how materials deform, how friction works at the molecular level, and why even the coldest ice can still betray our balance, inspiring further research into novel materials and practical safety solutions.<\/p>\n The study is published in the journal Physical Review Letters<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Every winter, countless people step onto icy sidewalks and suddenly find themselves sliding. For generations, the explanation was…\n","protected":false},"author":2,"featured_media":131161,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[49,48,314,66],"class_list":{"0":"post-131160","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-ca","9":"tag-canada","10":"tag-physics","11":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/131160","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=131160"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/131160\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/131161"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=131160"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=131160"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=131160"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}