Lorentz contraction: A real change of shape

A simple model of a solid is created by use of a few charged point particles interacting only with electromagnetic forces. Such a model cannot fix the size of the solid since the particles will be in unstable equilibrium, but the shape will be determined by the requirement of equilibrium. It is then easy to show that when this solid is in motion, it must Lorentz contract in the direction of the motion (as compared with the transverse dimensions) in order for the charges to remain in equilibrium.