Snippets of physics

It is well known in Newtonian gravity that a spherically symmetric density distribution produces a force outside it which falls as the square of the distance. Surprisingly, the converse is not true! Just be cause the force falls as inverse square outside a density distribution, you cannot conclude that it must be spherically symmetric. This article, first in a new series, explores this and related issues. This is based on an article originally published by the author in Physics Education, Vol 22, No. 4, p.263, 2006. T Padmanabhan works at IUCAA, Pune and is interested in all areas of theoretical physics, especially those which have something to do with gravity.