Chandu's Duality Theorem: Harmonic Phase Transitions Across Physical Boundaries

We present Chandu’s Duality Theorem, which establishes that physical systems governed by second-order harmonic field equations undergo an enforced phase transition of π/2 across critical boundaries. This transition manifests as a sine-dominated solution on one side of the boundary and a cosine-dominated solution on the other, ensuring continuity, finiteness, and information preservation. The theorem applies across physical scales, including black hole horizons, galactic cores, and cosmological boundaries, and provides a consistency-driven framework that removes singular behavior without violating known physical laws.