Cosmological Constant as a Structural Parameter of Space–Time and the Origin of Late-Time Accelerated Expansion of the Universe

Preprint. This manuscript is a preprint and has not been peer-reviewed. It is currently under consideration for publication in a peer-reviewed journal. Abstract The observed accelerated expansion of the Universe at late cosmological times is conventionally interpreted as a manifestation of dark energy or a dynamical vacuum component. In this work, an alternative interpretation is proposed, in which late-time acceleration is understood as a structural consequence of the cosmological dynamical equations rather than as a new physical process. It is shown that in a homogeneous and isotropic Universe described by Einstein’s equations with a positive cosmological constant, late-time accelerated expansion arises inevitably from the dilution of matter and radiation contributions in the presence of a structurally invariant vacuum sector. Within this framework, the cosmological constant $\Lambda$ is interpreted as a fundamental structural parameter of the theory, rather than as a sum of quantum vacuum fluctuations. It is rigorously demonstrated that $\Lambda$ is, in principle, non-computable within local quantum field theory without violating general covariance and consistency with the observed cosmological dynamics. As a result, the need for a reductionist explanation of its smallness is eliminated, and the so-called coincidence problem disappears. It is further shown that for $\Lambda>0$ the de Sitter regime represents an asymptotic structural attractor of cosmological evolution, determining the fate of the Universe without the introduction of new fields, phase transitions, or modifications of gravity. Observational tensions in modern cosmology, including discrepancies in $H_0$ and $\sigma_8$, as well as evidence for early massive structure formation, naturally admit an interpretation as consequences of a structural transition of the dominant sector. Taken together, this work demonstrates that the accelerated expansion of the Universe is not a symptom of incompleteness of standard cosmology, but a necessary manifestation of its internal structural logic.