A Causal-Set Quantum-Measure Ansatz for Globally Identified Chronology-Violating Histories: Seam Actions, Propagator Divergences, and the Operational Agency Trilemma

This exploratory theoretical preprint investigates whether a discrete quantum-spacetime framework can accommodate globally identified chronology-violating histories while preserving local causal order. The model represents physical histories as marked triples consisting of an infinite, past-infinite, acyclic causal set; a marked, freely acting order automorphism; and an equivariant quantum field configuration. Chronology violation is introduced through a global quotient of the covering causal set rather than by inserting cycles directly into the causal order. The paper develops a finite-domain action with explicit seam corrections and examines the stability of retarded propagator image sums under repeated timelike winding. The massless image sum diverges for every real phase twist, while the massive case fails to achieve absolute convergence without introducing a non-unitary damping term. The paper also formulates an operational-agency trilemma using intervention-based causal analysis. Subject to an explicitly stated faithful-embeddability assumption, the model inherits an obstruction to agent-controlled backward communication in 3+1 dimensions and collapses toward a Novikov-style self-consistency boundary condition. This work is presented as a speculative theoretical research note, not as an experimentally verified theory of quantum gravity or a completed time-machine design. It developed through an iterative human–AI research dialogue involving Jamal Goddard, OpenAI ChatGPT, Anthropic Claude, and Google Gemini. The named author accepts responsibility for the manuscript’s final arguments, references, and conclusions.