In terms of curious cosmologies, a certain formulation of the concave hollow earth theory is fun. From: http://en.wikipedia.org/wiki/Hollow_Earth#Concave_holl

In terms of curious cosmologies, a certain formulation of the concave hollow earth theory is fun. From: http://en.wikipedia.org/wiki/Hollow_Earth#Concave_hollow_Earths http://en.wikipedia.org/wiki/Hollow_Earth#Concave_hollow_Ear... In one chapter of his book On the Wild Side (1992), Martin Gardner discusses the hollow Earth model articulated by Abdelkader. According to Gardner, this hypothesis posits that light rays travel in circular paths, and slow as they approach the center of the spherical star-filled cavern. No energy can reach the center of the cavern, which corresponds to no point a finite distance away from Earth in the widely accepted scientific cosmology. A drill, Gardner says, would lengthen as it traveled away from the cavern and eventually pass through the "point at infinity" corresponding to the center of the Earth in the widely accepted scientific cosmology. Supposedly no experiment can distinguish between the two cosmologies.