On a more blatant, if less exalted, level, the force of friction makes its appearance in the first days of any first-year course. We declare, as if there can be no doubt, that friction impedes the motion between two bodies, and we invoke sophisticated microscopic models that show how the soles of running shoes bind to a track.
换一个更加显浅，也不那么深奥的理论层面，所有大学一年级物理教材都会提到摩擦力。我们似乎斩钉截铁的宣称：摩擦力阻碍了两个互相接触的物体之间的相对运动，而且还运用精密的显微镜模型来展示跑步者的鞋底是如何抓紧跑道的。