Minimal Necessary and Sufficient Conditions for a Physical Universe

This preprint presents a minimal framework for the existence of a physical universe, grounded in the structural requirements under which physical description becomes applicable at all. Rather than proposing new dynamical laws or modifying existing physical theories, the work identifies the minimal conditions that must be satisfied before any meaningful physical distinction may be defined. It argues that distinction requires the simultaneous logical availability of complementary alternatives. In its most reduced form, this complementarity appears as This / not-This, without presupposing spacetime, causality, observers, or physical law. The framework further argues that durably registered physical distinction is necessarily irreversible. Once a complementary distinction is irreversibly resolved, thermodynamic consequence becomes unavoidable. The quantity ΔQ is introduced to denote this irreversible cost, marking the earliest point at which physical description may become applicable. From this minimal transaction follow the conditions necessary for durable ordering, information, and physically meaningful structure. Time, locality, and spacetime description are treated not as primitive assumptions, but as downstream consequences explored in subsequent works within the ΔQ: The Irreversible Universe series. The framework is intentionally austere in scope. It does not compete with quantum mechanics, thermodynamics, or relativity, nor does it alter their operational predictions. Instead, it seeks to clarify the structural prerequisites under which such theories become jointly coherent and physically meaningful. Falsifiability is addressed through the framework's thermodynamic commitments. Specifically, the proposal would fail if durable physical distinctions could be demonstrated to register without corresponding thermodynamic cost. This work constitutes the opening paper in ΔQ: The Irreversible Universe, a series examining the relationships among complementarity, irreversibility, thermodynamic cost, locality, and the applicability of physical description.