The Invariability of Past and Future: Relativity of Simultaneity and the Ontology of Becoming

Abstract

This paper examines the ontological invariability of past and future events in light of the relativity of simultaneity. While the past is commonly regarded as fixed and the future as open, this distinction becomes philosophically problematic when spatially separated events can be assigned different temporal orders in different inertial frames. Using accessible thought experiments involving distant events, deliberate decisions, causal signals, quantum entanglement, and traces of the past, the paper distinguishes ontological reality from epistemic accessibility, causal determination, and temporal ordering. The discussion critically engages with the Rietdijk–Putnam argument, Gödel's reflections on time, and the philosophical positions of eternalism, presentism, the growing block universe, ontologically revisable pasts, frame-relative definiteness, and local becoming. Particular attention is given to the assumption that past events are necessarily invariant, while future events remain ontologically open. The paper argues that neither the availability of traces of the past nor the relativity of simultaneity alone establishes such an ontological asymmetry. Rather than advocating a definitive solution, the paper identifies the conceptual commitments and difficulties associated with competing interpretations. Its central contribution is to clarify why the presumed transition from an open future to a fixed past cannot be taken for granted. The investigation concludes that the distinction between temporal ordering, ontological invariability, and genuine openness remains philosophically unsettled. Clarifying the limits of what can be established is itself a substantive philosophical result.