冰之所以滑被归因于表面存在一层“极薄”的类液态水膜，但其成因仍无共识；围绕这一现象，过去约 200 年主要争论 3 种理论，去年德国研究者又提出第 4 种。关键温度标尺是 0 °C（32 °F）融点：压力可降低融点，因此 19 世纪中期 James Thomson 提出“压力融化”理论，但 1930 年代 Bowden 与 Hughes 计算认为滑雪者施加的压力远不足以显著改变融点，若要做到需“数千千克”体重。相对地，“摩擦融化”理论认为滑动产生热使表面融化，但其速度依赖性受到挑战：Bonn 团队用微型“冰场”测得滑度与速度无关，削弱“摩擦越大越滑”的预期关系。

第三种“预融化（premelting）”把水膜视为接触前即存在：1842 年 Faraday 观察到冰块相互接触会再冻结粘连，推断暴露表面有可再冻结的薄层；后续解释强调表面分子邻居更少、束缚更弱，因此更易位移。数值上，这层液态样结构被模拟为“仅几层分子厚”。马德里团队用原子级模拟综合三机制：常温近融点时预融化层已较厚，摩擦加热影响小；重物滑过会让薄层增厚（支持压力效应）；在更低温下，摩擦产生的热仍可使层增厚。其结论是三种机制会“同时”以不同权重起作用。

第四种“非晶化（amorphization）”主张低温下的滑并非靠融化：萨尔大学团队认为在极冷条件下仍可观测到滑性而预融化层不存在，且现实速度下摩擦热不足、所需接触面积若要产生足够压力则“不合理地小”。他们借鉴钻石抛光研究（2011 年德国模拟）提出：滑动可机械性破坏晶格，形成无序的非晶层，并随滑动持续加厚；由于水分子是偶极子，滑动中会形成并断裂微小“焊点”，驱动结构重排。争议焦点转向速度区间与术语：有人认为非晶化只在高滑速显著，但也有实验（Bonn 团队 2021 年）与新模拟支持“结构变化”是关键，只是对机制命名与描述仍分歧。

Ice is slippery because its surface is coated by an extremely thin, liquidlike water layer, but scientists still disagree on why that layer forms. Over roughly two centuries, three main hypotheses dominated—pressure melting, frictional melting, and premelting—until a fourth was proposed last year by German researchers. The melting benchmark is 0 °C (32 °F): pressure can lower the melting point, yet 1930s calculations by Bowden and Hughes argued an average skier’s pressure is far too small, requiring a mass of thousands of kilograms to shift the melting point enough.

Frictional melting posits that sliding-generated heat melts the surface, but key measurements undermine the expected speed dependence. Bonn’s group built a microscopic “ice rink” and measured slipperiness via a force ratio while rotating metal at different speeds; the result that slipperiness did not depend on speed weakens friction as a primary cause. Premelting instead treats the layer as preexisting: Faraday’s 1842 observations of ice cubes freezing together suggested a thin surface film that refreezes when covered, later rationalized by surface molecules having fewer neighbors and thus greater mobility. Simulations by MacDowell’s team found a liquidlike layer only a few molecules thick, thickening under heavy sliding (pressure effect) and, at lower temperatures, from frictional heating, implying all three mechanisms can operate simultaneously in different regimes.

The newer “amorphization” hypothesis argues low-temperature slipperiness can arise without melting: Saarland University researchers contend required pressure would demand an “unreasonably small” contact area, frictional heat at realistic speeds is insufficient, and at extremely cold temperatures ice remains slippery even when premelting is absent. Borrowing from diamond studies, they simulated sliding ice surfaces at temperatures low enough to prevent melting and found mechanical lattice разрушening creates a disordered amorphous layer that thickens with continued sliding, aided by dipole-driven micro-welds that form and break. Debate persists over whether this occurs only at high speeds, and over terminology, leaving consensus still unsettled.