Further Insights into the Universe Evolution Problem

The ΛCDM cosmological model has been highly successful in describing the large-scale structure and evolution of the Universe, yet it continues to face persistent challenges, most notably the cosmological constant problem and the Hubble tension. Building upon a recently proposed conceptual framework, this work investigates the temporal evolution of the Universe’s total energy density and its constituent components—dark energy, matter, and radiation—under the assumptions that the Hubble parameter evolves inversely with cosmic time and that gravitationally repulsive dark energy remains in dynamical balance with attractive matter–radiation components. Within this framework, the Universe expands linearly with time and exhibits zero acceleration, sustained by a constant expectation value of an energy inflow rate attributed to gravity-driven vacuum energy fluctuations. Analytical results indicate that dark energy acts as a persistent energy reservoir, continuously supplying energy for the formation and evolution of matter and radiation throughout cosmic history. A simplified phenomenological description of the radiation–matter transition, while not derived from first principles, is shown to reproduce the broad thermal history of the Universe, yielding temperature estimates in good agreement with established cosmological epochs from the Planck era to the present day. Furthermore, the framework offers a potential pathway toward reconciling quantum field theory predictions of vacuum energy density with cosmological observations and provides a possible explanation for the unexpectedly rapid formation and maturity of early galaxies observed at high redshift.