Maxwell's equations remain unchanged when time is replaced with its negative, but this does not imply retro-causality, as the speed of propagation remains constant. The discussion references the Wheeler-Feynman absorber theory, highlighting its relevance to the topic. It emphasizes that Maxwell's equations are incomplete without boundary conditions, which incorporate causality into the wave equation. Advanced solutions may be mathematically interesting but do not represent physical reality. Overall, the conversation underscores the importance of boundary conditions in understanding wave propagation and causality.