Conservation of Energy in a Closed Universe and the Kinematic Illusion of Dark Energy

We explore the thermodynamic lifecycle and macroscopic topology of a closed, temporally bifurcated spacetime manifold by applying the First Law of Thermodynamics and the Principle of Least Action to the primordial photon field. Utilizing a dimensionless equation linking the cosmic scale to the Planck scale, we demonstrate a linear geometric ratio mirroring the Schwarzschild geometry, necessitating a total invariant mass of $2M_u$ . To explain this physically, we propose a temporally bifurcated universe originating from a shared 5D torsion axis, which strictly separates a matter hemisphere from an equal antimatter hemisphere, thereby structurally bypassing the need for the Sakharov conditions to resolve Baryon Asymmetry. By evaluating the isotropic radiation pressure of the CMB traversing lines of zero spacetime interval, we offer a mathematical consistency argument—supported by the Isaacson effective stress-energy formulation—that the energy lost by the photon field is conserved as the mechanical work required to drive spherical volume expansion against the 5D Planck Stiffness (${\kappa }_T=c^4/G$ ). Finally, we establish a temporal and spatial boundary ($z\ge 1$ ) for the application of this pure global expansion. At later historical times, isotropic expansion is superseded by localized gravitational clustering. By analyzing the Milky Way’s vantage point near the boundary of the Local Void, we provide quantitative scale checks demonstrating that the apparent “accelerated expansion” of nearby supernovae is a localized kinematic artifact—a bulk flow phenomenon—rendering the hypothesis of Dark Energy unnecessary.