Order-of-Magnitude Estimation of the Age of the Universe Based on CMB Wavelength Stretching in the Light-Universe Framework

The age of the universe is traditionally estimated with high precision in standard cosmology using the expansion history and redshift observations. In this study, we conceptually consider the wavelength stretching of photons from the early universe to the present cosmic microwave background (CMB) and provide an order-of-magnitude estimate of the universe's age. The evaluation is independent of the detailed expansion history and the exact initial photon energy, relying solely on the present Hubble constant. The resulting estimate of approximately 14\,Gyr is consistent with standard cosmology and demonstrates the feasibility of a \textit{light-universe} framework for assessing cosmic time scales. Potential future work includes estimating the initial photon energy to refine our understanding of the early universe's radiation state.