The Structure and Arrow of Time

Problem What must a physical record preserve to reveal temporal direction, measure duration, and support a calibrated experiment? This two-volume mathematical working paper distinguishes causal order, clock readings, and forward–reverse evidence, and studies their joint realization under one history law. Principal results Relative-entropy disintegration identifies evidence lost through observation. Graph potentials characterize sufficient current sensors by the absence of affinity on unobserved cycles; paired histories extend the criterion to silent events and indistinguishable reaction channels. Anonymous records, finite memory, and stopped decisions are treated explicitly. Compensated currents control clock calibration under shared environmental dynamics. A preparation-and-work identity bounds directional records and terminal organization together. Exact elimination retains hidden memory, while inverse and energy margins control response. A moving-sector comparison bounds the complete quantum apparatus record, including interactions, leakage, and transport; a spectral gap gives an explicit operating-time estimate. Analytical constructions and counterexamples cover graph–matter selection, ring and torus persistence, localized field clocks and receivers, and source-correlated records. A kinetic parent combines a selected ring, an inertial field, and a finite reversible receiver. Preparation frontiers separate information cost from attainable initial laws of a fixed dynamics. Methods, scope, and open questions The proofs use conditioning, path potentials, martingale compensation, generating functions, and stable operator comparison. The project includes editable sources, bibliography, 47 reproducible finite verification programs, provenance, and a separate corrections report. The results concern specified model classes and conditional external inputs. Selected spatial geometry is not a derived Lorentzian spacetime; the joint ring receiver uses supplied capture materials and diffusive transport. A common microscopic derivation of Lorentzian geometry, apparatus formation, two distinct proper-time clocks, constrained gravitational response, and typical directional preparation remains open.