Metric-Inertial Repulsive Gradients from Destructive Field Interference: A Deterministic Continuum Alternative to Dark Energy and Cosmological Constant Fine-Tuning

The observed late-time accelerated expansion of the universe represents one of the greatest theoretical enigmas in contemporary physics, obliging the concordance CDM model to introduce a cosmological constant or an ad-hoc "Dark Energy" component that accounts for approximately 68% of the cosmic energy budget. However, attempting to identify with quantum vacuum zero-point energy results in the infamous vacuum catastrophe—a theoretical overprediction by 120 orders of magnitude. In this work, we present a deterministic, field-theoretic mechanism for cosmic acceleration derived from the Local Interaction Field Equilibrium (LIFE) framework. Within the 6-term continuum force balance (), we demonstrate that the gravito-inertial coupling term (Term B-6: ) undergoes an exact sign reversal in regions of destructive field interference. In these underdense, field-depleted domains—precisely corresponding to cosmic voids that occupy over 80% of the universe's spatial volume—the effective gravito-inertial acceleration switches from inward confinement to an outward repulsive metric gradient: . This outward metric pressure naturally drives the accelerated expansion of cosmic voids and surrounding large-scale structures without requiring an ad-hoc cosmological constant, unphysical scalar fields (quintessence), or fine-tuned vacuum parameters.