A Causal Summation Framework for the Structure of Time - Why True Simultaneity Is Impossible

This paper proposes a conceptual framework in which time is understood not as a universal linear dimension but as an emergent property arising from the summation of causal contributions within a given domain. In this model, a “now” is defined as the boundary at which all prior causal effects have been integrated into a coherent state for an observer or system. Because two events cannot mutually contribute to each other’s causal summation, true simultaneity is impossible even within a single domain. This framework synthesizes insights from relativity, quantum measurement, and causal‑set thinking, offering a unified philosophical account of why time is locally linear yet globally undefined, and why an absolute “now” could only exist from a vantage point external to spacetime.