Geometric Origin of the Quantum–Classical Boundary and the Arrow of Time

The quantum measurement problem and the arrow of time problem are two of the most fundamental unsolved problems in physics. This paper proves that they share the same geometric origin: the transition of the total information dissipation coefficient Υ from 0 to >0. Quantum collapse is a saddle-point bifurcation of Υ on a single quantum system — when the information dissipation channel opens, only a single classical saddle-point path survives among the quantum superposition states. Collapse and decoherence are not two independent processes but different stages of the same saddle-point bifurcation: decoherence is the early stage, and collapse is the late stage. The arrow of time is the macroscopic manifestation of Υ in statistical ensembles — irreversibility has two independent channels: ΥE (energy dissipation, thermodynamic arrow) and Υ_φ (phase dissipation, information arrow). The two can be asynchronous: a pure dephasing system has Υ_φ>0 while ΥE=0; collapse precedes thermalization. This independence yields testable predictions on cosmological scales: if the information arrow is activated before or after the thermodynamic arrow in the very early Universe, the primordial density fluctuations will retain distinct types of non-Gaussian features, whose shapes can be used to determine the activation order of the two channels. Foundational concepts of quantum mechanics — wave function, complex numbers, entanglement, decoherence, quantum–classical boundary — obtain a unified geometric definition within the order-parameter geometric framework. If experiments confirm that ΥE and Υ_φ always change synchronously, or that log C (t) is linear rather than upward-curving, this theory is falsified.