Well....that changes everything. NOW I understand. ;^)
The "inverse sqare law" states that the intensity of energy, for example from a light bulb, decreases by the square of a distance change.
If the distance is increased by a factor of 2, the energy received is reduced by a factor of 4, not 2. If the distance is increased by a factor of 3, the energy received is reduced by a factor of 9.
As the distance is increased, the area over which the energy spreads out is much greater than what you might expect.
The inverse-square law is really pretty easy to understand.
Imagine yourself in a dark room with a candle in the center located twenty feet from a wall. Hold a "shade" consisting of a one-foot square piece of opaque material ten feet from the wall and parallel to the wall.
There will be light from the candle hitting the shade. There will be a shadow on the wall which is twice as big as the shade in both directions, because the wall is twice as far from the candle as the shade. That is, the shadow is a two-foot by two-foot square.
If you then remove the one-foot square, all of the light which was previously hitting the one-foot square will then be hitting the two-foot square area which was previously in shadow. The intensity of light per square foot has decreased by a factor of four, since the original light falling on the shade is now distributed over an area four times as large.
Whatever relative distances are chosen for the experiment, the sides of the shadow will scale with the distance increase and the light falling when the shade is removed will be decreased as it is distributed over an area which is the square of the distance scale.
That is what the "inverse-square" law describes.