EL Science — Volume I Nonlinear Vacuum Dynamics, Emergent Phantom Crossing, and Observational Cosmology

This volume establishes the foundational dark-energy sector of EL Science through a nonlinear vacuum-dynamics framework in which cosmic acceleration emerges from the evolving internal state of the vacuum rather than from a fixed cosmological constant. A canonical four-variable system — compression, release, activation, and structural memory — generates an emergent phantom-divide crossing without imposing it by hand. The framework is tested directly against DESI DR2 dark-energy constraints, BAO distance measurements, and cosmic-chronometer H(z) data while maintaining a fully self-consistent expansion history derived from energy conservation. The resulting cosmology remains observationally near-degenerate with ΛCDM at the present epoch while predicting a structured, evolving vacuum sector and a future deterioration regime explored in later EL Science volumes. This volume presents the mathematical structure, numerical implementation, observational confrontations, tensions, limitations, and current status of the framework with full methodological transparency.