Astrophysics and Space Science
It has become apparent that our intuitive notions of space and time are inadequate for developing a theory of quantum gravity. It is perhaps worthwhile to understand where our macroscopically-developed spatial instinct is implicit in the concept of manifold, and to consider alternative methods for defining (vis-a-vis explicating) space and time. A simple example for generating a topos over a fundamental set is provided to illustrate the potential basis of such a definition.
Stuckey, W. M., "Defining spacetime" (1996). Faculty Publications. 1526.