2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34098State-dependent gauge principle invoked to realize the relativity to a measuring device, has been proposed. Self-consistent global (cosmic) potential forms the state space of the fundamental field and its connection, agreed with Fubini-Study metric of $CP(N-1)$, serves as state-dependent gauge potential. In this framework the linearity of the ordinary quantum mechanics appears as a `tangent approximation' to the totally nonlinear underlying pre-dynamical `functional' field theory on $CP(N-1)$.20 pages, LaTeX, submitted to the Foundations of Physics Letters, some formulas improved, minor grammatical changesGeneral Relativity and Quantum CosmologyHigh Energy Physics - TheoryQuantum Physicstext