Time–Scalar Field Theory (TSFT) introduces a single scalar field Θ(xμ) representing local temporal potential, from which the structures of quantum mechanics, relativity, electromagnetism, thermodynamics, and cosmology emerge as limiting regimes. The framework reinterprets spacetime geometry as an epiphenomenon of scalar-time flow, governed by the continuity law ∇μ∂μΘ = 0. Explicit derivations demonstrate recovery of Schr¨odinger, Dirac, Maxwell, and Einstein equations as harmonic, torsional, or curvature limits of the same principle. Empirical validations include Mercury’s perihelion shift, solar-corona heating, and cosmological deceleration parameters. TSFT remains falsifiable through measurable scalar-time gradients and coherence differentials, distinguishing it from speculative metaphysics. This Reviewer’s Edition presents the axioms, derivations, and validation data in compact, testable form.