Galilean decoherence and quantum measurement

Abstract In this study, we present a modified quantum theory, denoted as QT *, which introduces mass-dependent decoherence effects. These effects are derived by averaging the influence of a proposed global quantum fluctuation in position and velocity. While QT * is initially conceived as a conceptual framework – a “toy theory” – to demonstrate the internal consistency of specific perspectives in the measurement process debate, it also exhibits physical features worthy of serious consideration. The introduced decoherence effects create a distinction between micro- and macrosystems, determined by a characteristic mass-dependent decoherence timescale, τ ( m ). For macrosystems, QT * can be approximated by classical statistical mechanics (CSM), while for microsystems, the conventional quantum theory QT remains applicable. The quantum measurement process is analyzed within the framework of QT *, where Galilean decoherence enables the transition from entangled states to proper mixtures. This transition supports an ignorance-based interpretation of measurement outcomes, aligning with the ensemble interpretation of quantum states. To illustrate the theory’s application, the Stern–Gerlach spin measurement is explored. This example demonstrates that internal consistency can be achieved despite the challenges of modeling interactions with macroscopic detectors.