Light is maybe one of the more important things in the universe (though this is debateable—some sensible people rank chocolate above it). It also has a rich history of people not really knowing what it was, how fast it moves, or even how it moves. So, in order to better understand it, let's turn back time, and cover a bit of light history (these puns never get old).

For a very long time, people believed light to be instantaneous, and for good reason. When is the last time you could see light move from place to place? Some folks disagreed, including a man born on February 15th in 1564 by the name of Galileo Galilei. Galileo attempted to measure the speed of light much like one might measure the speed of sound. In fact, you and another person could get a rudimentary measurement of the speed of sound using this method, so let's cover the sound applications first: