Vacuum Response Theory: Emergence of Fundamental Interactions, Spacetime Geometry, Quantum Mechanics, and Cosmology from Boundary-Induced Vacuum Reorganisation

We present Vacuum Response Theory (VRT), a unified framework in which spacetime geometry, gravitational dynamics, dark energy, and quantum coherence emerge from boundary-induced reorganisation of quantum vacuum energy. In VRT, a boundary is any physical surface that imposes phase conditions on vacuum modes — from charged particles at the quantum scale to the cosmic coherence boundary at the Hubble radius. VRT distinguishes two vacuum states: the finite ordered interior vacuum enclosed by the cosmic coherence boundary, and the surrounding infinite Primordial Dynamic Uncontrolled Vacuum (PDUV), from which the boundary emerged at the Planck scale. The outward growth of the cosmic coherence boundary into the PDUV drives the apparent expansion of the universe — cosmic acceleration emerges naturally from boundary dynamics without requiring a cosmological constant or exotic dark energy field. Three physical constraints—quantum coherence preservation, the cosmic boundary condition, and Lorentz invariance—force a unique field equation whose exact solution eliminates spacetime singularities. The vacuum energy density resolves the cosmological constant discrepancy without fine-tuning. The cosmic coherence boundary growth rate is derived as β_DE = Ω_m/4; its thickness κ* = 3.77 is derived from the VRT attractor equation to 0.11%. The covariant action reproduces Einstein field equations exactly, with post-Newtonian parameters proved as theorems. Galaxy rotation curves are reproduced without dark matter; the Hubble tension is explained by logarithmic cosmic coherence boundary evolution. The Schrödinger and Dirac equations are derived from vacuum mode physics. Ten quantitative falsifiable predictions are presented, including a gravitational wave breathing mode consistent with current constraints and testable with next-generation observatories. Three parameters remain open: inflation boundary speed, transition function, and lepton mass ratios.