Consistent Histories of Systems and Measurements in Spacetime

M. P. Blencowe

Matthew T. Gorski

Bernard d’Espagnat

Tomoyuki Uchida

This paper presents an interpretive framework that redescribes discussions in quantum measurement, decoherence, holography, ER=EPR, traversable wormholes, cosmological natural selection, and the simulation hypothesis through the vocabulary of information architecture. The central proposal is to describe physical reality as a causally consistent history of information updates rather than primarily as a collection of objects independently existing within spacetime. Spacetime, matter, and observers are treated as effective representations through which this history becomes experientially accessible under locality, light-speed constraints, conservation laws, and decoherence. The framework uses the metaphor of the “Akashic Ledger” for this history and “Custodian” for the constraint structure that prevents inconsistent updates. Observation is redescribed as commitment: an effectively irreversible environmental interaction through which information becomes redundantly recorded and practically unavailable for reversal. The paper classifies its claims into four levels—metaphor, consistent redescription, speculative hypothesis, and narrative extension—in order to distinguish physically grounded interpretations from speculative or fictional components. The paper’s main contribution is the Governance Convergence Argument, which interprets constraints such as No-FTL, Base Integrity, containment, auditability, and resource boundedness as attractor-like conditions for any long-lived, consistently continuable information history. The framework offers no independent empirical predictions at this stage and is therefore not a physical theory. It is best understood as a conceptual and philosophical model that provides a consistency-engineering vocabulary for questions about quantum measurement, emergent spacetime, holography, black hole information, and speculative cosmology.

D. Sokolovski, Y. Liu

James B. Hartle

Sum-over-histories generalizations of nonrelativistic quantum mechanics are explored in which probabilities are predicted, not just for alternatives defined on spacelike surfaces, but for alternatives defined by the behavior of spacetime histories with respect to spacetime regions. Closed, nonrelativistic systems are discussed whose histories are paths in a given configuration space. The action and the initial quantum state are assumed fixed and given. A formulation of quantum mechanics is used which assigns probabilities to members of sets of alternative coarse-grained histories of the system, that is, to the individual classes of a partition of its paths into exhaustive and exclusive classes. Probabilities are assigned to those sets which decohere, that is, whose probabilities are consistent with the sum rules of probability theory. Coarse graining by the behavior of paths with respect to regions of spacetime is described. For example, given a single region, the set of all paths may be partitioned into those which never pass through the region and those which pass through the region at least once. A sum-over-histories decoherence functional is defined for sets of alternative histories coarse-grained by spacetime regions. Techniques for the definition and effective computation of the relevant sums over histories by operator-product formulas are described and illustrated by examples. Methods based on Euclidean stochastic processes are also discussed and illustrated. Models of decoherence and measurement for spacetime coarse grainings are described. Issues of causality are investigated. Such spacetime generalizations of nonrelativistic quantum mechanics may be useful models for a generalized quantum mechanics of spacetime geometry.