Committed Presentism: A Single-History Ontology of Quantum Mechanics

Committed Presentism is a single-history ontology of quantum mechanics in which only the present exists, reality advances through one global now within each common-origin causal domain, and one decohered alternative becomes actual while the others do not. The quantum state retains its ordinary dynamics, while actuality is represented separately and becomes physically consequential through gravity. The quantum actualization used here is state-silent and has standard modal antecedents; the framework's distinctive temporal structure is that the actual node indexes history and truthmaking, which the quantum state does not carry, while the present record structure fixes which successors are eligible. The present is what exists, where becoming occurs, and what grounds truth about the past. The past is fixed without remaining as an independently existing region, while the future remains open. At the commit slice, the framework leaves the standard quantum predictions examined here unchanged: local marginals are unaltered and matter no-signaling is preserved. Gravitational efficacy is constitutive: the source at an event reads the actual sector restricted to that event's causal past, so an extended commitment's response is not carried on the commit leaf; its onset across a causal layer graded by record overlap, and a causal completion of this coupling, are argued at linear order about a Minkowski background and, where the causal source loses no derivative against the metric, at nonlinear order. Beyond the commit slice, on matter regions that carry no record of the commitment, the run-ensemble matter channel is non-unitary exactly where the positive-weight branch evolutions are not phase-equivalent on a supplied common factor carrier. Committed Presentism therefore combines objective becoming, a single actual history, and an open future within a quantum framework that remains operationally standard at the moment of commitment.