The Informational Conservation Principle (CFund): Lagrangian Derivation of Structural Coherence Decay

This record contains the preprint and supplemental material for: **The Informational Conservation Principle (CFund): Lagrangian Derivation of Structural Coherence Decay** Author: Yilwook Kim (Independent Researcher) Abstract:We propose the Principle of Total Informational Invariance (CFund) as a fundamental axiom: the global von Neumann entropy of the universe is strictly conserved. Any local coherence that reduces subsystem entropy generates an informational asymmetry cost, which must decay along the path of least informational action. Using Bateman's modified Lagrangian formalism, we derive the Symmetry Reversion Equation and show that exponential coherence decay is a deterministic structural necessity. Equating the minimal action to Planck's constant reproduces the Compton scale, yielding universal coherence time and length. The framework predicts two sharp, parameter-free signatures absent in standard quantum theory: (i) finite photon coherence time in perfect vacuum and (ii) a material-dependent structural decoherence floor at ultralow temperatures. Contents:- Main article (Kim_CFund_PRL_2025.pdf)- Supplemental integrated version (Kim_CFund_PRL_2025_Supplemental Integrated Version.pdf)