Time sequence and causality of acoustic events in supersonic motion

The acoustic events arising from the abrupt supersonic motion of a point mass (event E1) and its impact on a plane wall (event E2) are investigated theoretically. The fact that one observer can perceive the events in the order E1, E2 while another observer might perceive them in the order E2, E1 is considered by analogy to the causality-violation problem in optics. The motion of the Mach cone in the medium, the space-time diagram of E2 and causality, and the kinematics of E1 are presented graphically.