The Inverse Square Law has to be the most exciting thing i have ever seen.... ever, infact, the excitement is almost unbearable so I suppose I better tell you about it
Basically, the inverse square law is used to work out how intense (rate of recieving energy) a wave will be depending upon how far away you are from the source and the power of the source (energy radiated per second).
The idea is that, if you have a light source in space that light gets emitted from in all directions. The light emitted at any time will move out as a sphere with a growing radius which would grow at the speed of light. Anyway, as the sphere grows larger, the surface area of the sphere is getting bigger and bigger. Therefore the light emitted from a single point source has to be spread out over a larger area. So when you are looking towards the pointsource, the further away from the source you are, the less intense the point source will seem because less light is entering your eye.
The equation to work out how intense the light will be is simply the amount of power emitted from the point source devided by the surface area of the sphere at any point.
I = P / ( 4 * π * Radius Squared)
The reason that this simple formula/idea excites me so much is simply because it affects absolutely everything we see. No other true reason.
I take no responsibility for this being proven to be completely wrong in some kind of strange extreme circumstances.