Finite speed of disturbance for the nonlinear Schr\"odinger equation

Abstract

We consider the Cauchy problem for the nonlinear Schr\"odinger equation on the whole space. After introducing a weaker concept of finite speed of propagation, we show that the concatenation of initial data gives rise to solutions whose time of existence increases as one translates one of the initial data. Moreover, we show that, given global decaying solutions with initial data $u_0, v_0$, if $|y|$ is large, then the concatenated initial data $u_0+v_0(\cdot -y)$ gives rise to globally decaying solutions.