The Born Rule from Irreversible Records: Derivation, Finite-Time Corrections, and an Experimental Test

The Born rule — the statement that the probability of obtaining outcome |ϕi⟩ from quantum state |ψ⟩ equals |⟨ϕi|ψ⟩|² — is normally taken as a fundamental postulate of quantum mechanics. This paper derives the Born rule from the bridge law connecting the the Fubini–Study geometry of quantum state space to physical time through irreversible contraction of the accessible future state space Ω. The bridge law, d(ln Ω)/dτ = −κ Γ(τ), specifies that each recording event depletes generative capacity at a rate set by the structural efficiency constant κ = π — the Fubini–Study volume of ℂP1. This identifies the Fubini–Study metric as the natural measure of state-space contraction. Three physical requirements — unitary invariance, projective consistency, and smooth locality — uniquely select this metric, leaving no freedom in the probability assignment. The probability of each outcome is the fraction of the local Fubini–Study contraction associated with that outcome, yielding pi = |⟨ϕi|ψ⟩|². The framework further predicts finite-time corrections to the Born rule. Because records form through irreversible thermodynamic processes with characteristic timescale τdet, the effective probability of registering independent events at short delay τ is modulated by the record-completion function R(τ) = 1 − e−|τ|/τdet. This produces a distinctive suppression of photon coincidences in the second-order correlation function g(2)(τ) at picosecond timescales in Hanbury Brown–Twiss measurements using superconducting nanowire single-photon detectors. The effect depends on detector material properties through the detector transition time τdet and is experimentally testable with existing instrumentation. The result therefore provides both a geometric derivation of the Born rule from the bridge law of irreversible record formation and a concrete experimental prediction linking quantum probability to the thermodynamics of measurement. This work forms part of the author's research programme Emergence as Regime Formation, investigating the origin of time, probability, and physical constants through irreversible record formation.