Solution formula and time-periodicity for the motion of relativistic strings in the Minkowski space

In this paper we study the motion of relativistic strings in the Minkowski space R 1 + n which is governed by n nonlinear partial differential equations of second order. Surprisingly, we obtain a general solution formula for this complicated system of nonlinear equations. Furthermore, based on this solution formula, we show that the motion of closed strings is always time-periodic. We further extend our solution formula to finite relativistic strings.