Abstract We present a systematic and quantitative comparison between Transition Theory (TT) and the standard ΛCDM cosmological model, confronting both frameworks with a broad set of high-precision observational data. While ΛCDM attributes the observed cosmological redshift and late-time acceleration to metric expansion driven by dark energy, TT introduces an alternative physical mechanism in which redshift arises from gradual energy dissipation of radiation into higher-dimensional hyperspace. To assess the empirical viability of this framework, we implement TT within modified Boltzmann solvers and perform ray-tracing simulations, enabling direct comparison with observational probes. The analysis incorporates the Planck 2018 cosmic microwave background (CMB) temperature anisotropy spectrum, baryon acoustic oscillations (BAO), cosmic chronometer measurements of the Hubble parameter H(z), Type Ia supernova luminosity distances, and weak-lensing data from DES and KiDS. We find that TT reproduces the principal observational signatures of the concordance model, including the CMB acoustic peak structure, BAO scales, and lensing convergence, with statistical accuracy comparable to ΛCDM across multiple datasets. Notably, TT achieves this level of agreement without invoking a cosmological constant or dark energy component, while exhibiting a tendency to alleviate both the Hubble-constant and σ₈ tensions. These results indicate that TT constitutes an empirically consistent and theoretically well-motivated alternative cosmological framework, warranting further investigation as a viable extension to standard cosmology. Keywords: Transition Theory; ΛCDM model; Cosmological redshift; CMB Anisotropies; Baryon Acoustic Oscillations; Gravitational Lensing.
Vlachogiannis et al. (Mon,) studied this question.
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