<b>The Unified Limit: The Ultimate Constraint on Energy-Density in the Universe</b>

The <b>Unified Limit (U)</b> is a fundamental concept within the <b>Mass-Energy Gravity (MEG) model</b>, representing the upper bound on energy density that governs mass-energy interactions, gravitational effects, and cosmic expansion. This paper explores how U serves as the ultimate energy threshold, unifying the speed of light limit and black hole energy density under a single principle. <br><br>By constraining energy-density variations, U prevents singularities, maintains cosmic stability, and naturally explains phenomena such as gravitational lensing, galaxy rotation curves, and large-scale structure formation without requiring dark matter or dark energy. The implications of U extend beyond gravity, offering a framework that integrates inertia, entropy, and energy redistribution into a coherent, testable model. <br><br>This paper presents the mathematical formalism of U, discusses its role in cosmology and astrophysics, and outlines observational tests to distinguish MEG’s predictions from those of General Relativity.