In a colloidal dispersion, particles much bigger than atoms are spread more or less uniformly amid a molecular fluid. Paint is a colloidal dispersion; so are ice cream, smog, and shampoo.
Less quotidian are the myriad new colloids being developed for drug delivery, photonics, and other high-tech applications. Materials scientists like the colloid concept because it combines functional nanoparticles, whose aggregate surface is huge, with a supporting medium, whose properties can be tailored and transformed.
Predicting and optimizing a colloid’s properties requires a physical model. But the colloid’s mix of particle sizes, along with the range and variety of forces present, frustrates the modeler. Even though one can write down exact equations for the interparticle forces, obtaining a solution for the bulk substance is impossible without severe approximations. Numerical approaches founder under the colossal computational load.
Now, Erik Luijten of the University of Illinois at Urbana-Champaign and Jiwen Liu, his...
