I'm guessing that most FEs will dismiss the inverse square law with regards to light and gravity out of hand.
They already have problems understanding the decrease in gravity as you move away from the centre of the planet, due to the fact that they persist in showing the planet as a flat coplanar surface being acted upon by some external but unknown force.
Until they acknowledge, firstly, that gravity is generated by the mass of a spherical planet, and acts perpendicular to the surface of that sphere, they'll never be able, secondly, to comprehend that a specified physical quantity or intensity is inversely proportional to the square of the distance from the source of that physical quantity.