A Cyclic Cosmological Model Without Singularities, Inflation, or Dark Energy Based on Modified Gravity

This work presents a cyclic cosmological model that eliminates the need for a Big Bang singularity, cosmic inflation, and dark energy. The model is based on a minimally modified form of General Relativity, such as an f(R) gravity with an additional quadratic curvature term. This modification remains negligible at low curvature but becomes repulsive at high curvature, enabling a non-singular cosmological bounce. Quantum mechanics acts only on matter fields and does not need to be extended to the spacetime manifold, since the model avoids divergent densities and Planck-scale singularities. The observed apparent acceleration of cosmic expansion is explained without a cosmological constant. Instead, the model combines large-scale geometric effects from modified gravity with light-propagation distortions caused by mild inhomogeneities in the matter distribution. This combination can reproduce the Type Ia supernova luminosity–distance relation without invoking dark energy. The model naturally addresses several current cosmological tensions, including the Hubble tension, early massive galaxies observed by JWST, large-scale CMB anomalies, and the stability of cosmic structures. Overall, this framework provides a minimalist and observationally consistent alternative to the ΛCDM paradigm, relying only on established physics and avoiding speculative components such as inflation fields, vacuum energy, or quantum gravity.