Why does light only go in a straight line?

Light travels in straight lines due to its wave-like nature and the principle of rectilinear propagation, which states that in a uniform medium, light rays move along the shortest path between two points. This behavior is a consequence of the laws of physics, particularly Maxwell's equations, which describe how electromagnetic waves propagate. When light encounters different media, it can bend or refract, but in a consistent medium, it maintains a straight trajectory.