A weird one from Rucker, but then, that's kind of a redundancy; everything from the mind of Rucker has a weird stance. This one posits the idea that space/time is a continuum, and circular in nature. That is, if one was to increasingly make oneself smaller and smaller, after passing through the various levels (atomic, subatomic, etc.) one would then start progressing through space (universe, galaxy, solar system, etc.). Like Robert Anton Wilson's "Schrodinger's Cat" trilogy, Spacetime Donuts posits the theory, then fits a story around what it might be like if that theory were true. Rucker's writing style, at least in this early novel, is most similar to the early novels of Philip K. Dick, but whereas Dick was focused on the nature of reality from a psychological and philosophical viewpoint, Rucker comes at it from a mathematical and physical view.