The phenomenon that light travels through a straight line is called

The phenomenon that light travels through a straight line is called rectilinear propagation of light.

The phenomenon that light travels through a straight line is called "rectilinear propagation" or "rectilinear motion of light." In simpler terms, it means that light travels in a straight path unless it is influenced by external factors like refraction or reflection. This property of light allows us to accurately predict its path and study its behavior in various scenarios.