Classical Science Assumes Instantaneity — and That Assumption Is Wrong A Conceptual Foundation via History Bundles

This work provides a conceptual foundation for physics by identifying and removing a hidden assumption shared by classical and quantum theories: instantaneity. Modern physical theories are typically formulated in terms of instantaneous states that evolve through local-in-time update rules. This paper argues that such an assumption is neither empirically required nor conceptually fundamental. Instead, physical reality is reformulated in terms of history bundles: weighted ensembles of temporally extended, globally consistent histories. Within this framework, time evolution emerges from consistency constraints imposed on entire histories rather than from differential equations acting on instantaneous states. Quantum probability arises as a geometric and combinatorial measure over admissible histories, yielding the Born rule without postulating measurement axioms, collapse, or observer-dependent rules. Apparent quantum nonlocality is reinterpreted as a temporal selection effect, not as instantaneous spatial influence. At cosmological scales, causal horizons progressively restrict the set of extendable histories. This irreversible contraction of the history bundle induces an effective negative pressure, providing a natural interpretation of late-time cosmic acceleration without introducing scalar fields, vacuum energy, or ad hoc modifications of gravity. The resulting effective equation of state approaches −1 at late times while remaining non-phantom, and leads to observationally distinguishable signatures. Rather than proposing a new phenomenological model, this paper reorganizes the conceptual structure underlying quantum mechanics, statistical physics, and cosmology. By relaxing a single modeling assumption—instantaneity—it reveals a unified structural explanation for probability, nonlocal correlations, irreversibility, and cosmic acceleration. The work is foundational and conceptual in scope. It is intended as a basis for future numerical studies, observational tests, and extensions toward quantum gravity and information theory.