  To describe many-particle systems suspended in incompressible
low-Reynolds-number fluids, effective hydrodynamic interactions can be
introduced. Here, we consider particles embedded in elastic media. The
effective elastic interactions between spherical particles are calculated
analytically, inspired by the approach in the fluid case. Our experiments on
interacting magnetic particles confirm the theory. In view of the huge success
of the method in hydrodynamics, we similarly expect many future applications in
the elastic case, e.g. for elastic composite materials.
