Structural Differentiation Cosmology (SDC): An Irreversible Universe Model with Observational Correspondence

Structural Differentiation Cosmology (SDC) is a theoretical frameworkbased on the premise that absolute nothingness cannot exist.The universe is modeled as a closed system without external reference,where cosmic evolution is described as irreversible internalreconfiguration of existing structure. In this version, the conceptual variable structural density C(t)is weakly connected to cosmological observables.Cosmic expansion and acceleration are interpreted as observationalprojections of monotonic structural differentiation,providing an alternative interpretive frameworkfor dark-energy-like phenomena without introducing additional entities.