Soft Matter at the Thermal Scale, Ch Brownian particles, sedimentation and the hard-sphere fluid
Problem
Someone argues: "Entropy always favours disorder. A crystal is more ordered than a fluid, so its configurational entropy must be lower. Since nothing but volume exclusion acts between hard spheres, there is no energy available to offset this entropy loss, so hard spheres can never freeze into a stable crystal; the freezing seen in real colloidal suspensions must be caused by some residual attraction between the spheres." Using the free-volume (cell) picture of hard-sphere freezing, explain what is wrong with this argument.