Unified theory of direct interaction between particles, strings and membranes

A model of generalized relativistic membranes that contains as special cases, particles, geometric strings and geometric membranes, and other one and two dimensional objects is discussed. The equations of motion for such objects in direct interaction are examined and the constraints on the interaction due to the freedom of gauge of the free model are solved. Conservation theorems associated with Poincare invariance of the action are studied, as well as the generalization for action-at-a-distance theories of the action and reaction law.