From States to Seconds: An Operational Information Chain for Physical Timekeeping

Physical clocks do not ordinarily produce duration as a context-free observable of their internal dynamics. They generate states, transitions, phases, or trajectories from which a measurement arrangement constructs a calibrated reading. We propose an operational decomposition of physical timekeeping into five components: clockwork, readout, record space, estimator, and calibration specification. This separates information encoded in a time-sensitive physical process from information made accessible by a selected readout and from the numerical duration inferred from the resulting record. Standard data-processing and Fisher-information relations organize this chain. A phase-encoding qubit provides an exact illustration: a measurement in the σₓ basis retains the full local Fisher information, Jₓ = ω², whereas a σ₂ measurement is temporally blind, J₂ = 0. Even the informative readout identifies only the phase ωτ unless the frequency scale is independently calibrated. Thermodynamic costs likewise cannot be assigned to ‘the clock’ without declaring the boundary separating clockwork, readout, memory, and reset. The framework introduces no new ontology of time, clock dynamics, or metrological bound; it clarifies how time-sensitive physical states become accessible records and, through inference and calibration, measured durations.