Current macroscopic physics relies heavily on General Relativity (GR) to explain gravitational dynamics through the curvature of spacetime. However, GR introduces persistent mathematical anomalies, such as gravitational singularities and incompatibilities with quantum vacuum limits. This paper formalizes the macroscopic foundations of Energy Field Theory (EFT), a framework that rejects spatial curvature. In EFT, space is a rigid, non-flexible, 3D spatial dimension. The universe is governed by two opposing types of energy that interact within this spatial grid. Extrinsic Energy is naturally attractive and drives gravitational force, while Intrinsic Energy is naturally repulsive and drives universal expansion. By establishing a direct energy-to-energy attraction constant ($K_{ee}$), redefining time dilation as a systemic inertial load caused by Extrinsic Energy density, and defining a spatial saturation limit that bypasses the singularity problem, EFT successfully replicates the observational data of standard cosmology without utilizing flexible spacetime geometry. Finally, variable Intrinsic Energy density is proposed as a mechanism for anisotropic cosmic expansion, offering a novel resolution to the Hubble Tension.