Event Emergence as Structural Saturation of Causal GeometryA Foundational Framework for Irreversibility and Time in Space-Time

Abstract This work presents a foundational framework in which irreversibility and the directionality of time arise as intrinsic features of causal geometry rather than as consequences of entropy, statistical mechanics, or boundary conditions. Spacetime is treated as a causally structured manifold where temporal asymmetry emerges from geometric and relational constraints on admissible causal paths. The framework emphasizes causal order and structural non-equivalence between forward and backward extensions in spacetime, providing a geometric basis for irreversibility that does not rely on thermodynamic assumptions. Time is not introduced as an external parameter or as a macroscopic emergent phenomenon, but as a dimension constrained by causal accessibility and structural consistency. The paper does not propose a new physical theory or empirical predictions. Its contribution is conceptual and foundational: to clarify the geometric conditions under which irreversibility becomes unavoidable in spacetime models. This perspective offers a unifying basis for discussions of time asymmetry across general relativity, causal set approaches, and the foundations of physics.