The luminosity function of Fast Radio Bursts (FRBs) hold the key to observability, the overall energetics and perhaps even the physics of the FRBs. For instance, recently a low luminosity FRB from a Galactic magnetar showed that at last some FRBs come from magnetars and that at least some FRBs are magnetospheric phenomena (rather than external shocks).  The speaker will conclude his talk with a vision for a global array of simple dipole stations aimed at exploring the microsecond time (project GREx).