What is the scientific principle called when light travels in a straight line?

The scientific principle that describes light traveling in a straight line is known as the Law of rectilinear propagation. This principle explains that light rays move in a straight path in a uniform medium, which is fundamental to understanding various phenomena in optics, such as how we perceive images, the behavior of lenses, and the formation of shadows.

Understanding this principle is essential for applications in optics, as it forms the basis for more complex concepts like reflection and refraction. While the Law of reflection pertains to how light bounces off surfaces, and the Law of refraction deals with how light bends when it passes through different media, the Law of rectilinear propagation specifically focuses on the straight-line nature of light in a consistent medium. The Law of diffusion, on the other hand, refers to the scattering of light rather than its straight-line movement.