"Configuration spaces of hard spheres (in two dimensions hard disks) are a natural generalization of configuration spaces of points, which are well studied in topology. They also represent the phase space or energy landscape for a hard spheres system, so they are also of interest in physics. Barsyhnikov, Bubenik, and Kahle showed that the as the radius of the spheres varies, the topology of such a configuration space can only change in the presence of a mechanically balanced configuration. Carlsson, Gorham, Kahle, and Mason did experimental work to find mechanically balanced configurations experimentally, and found that even for a system with only 5 disks in box, the configuration space topology could change dozens of times as the disk radius varies. I will survey this area, briefly reviewing some of this earlier work and focusing on more recent progress in the area. "