CHAPTER 2Nature of Light
A natural question for a beginning student of light is to ask: Does light travel in a straight line? The answer is basically yes, and this scientific fact has been known as one of the fundamental properties of light or more generally for all electromagnetic (EM) waves.
Then naturally, the next question to ask is: Why does light travel in a straight line? Is there something special about the light wave’s behavior in time and space that leads light to travel in a straight line, and are there any limits to this straight-line behavior.
We start with a geometrical picture of a straight line or ray that also forms the directional k or propagation vector for the traveling light wave under observation over a ...