Order-of-Magnitude Estimate of the Age of the Universe from CMB Wavelength Stretching Based on the Light Universe Theory

This study presents an order-of-magnitude estimate of the age of the universe based on the wavelength stretching of photons from the early universe to the present cosmic microwave background (CMB). Unlike standard cosmological models, the approach does not rely on a detailed cosmic expansion history or specific predictions for the initial photon energy EinitE_{\rm init}Einit, which remains unknown. Instead, the current Hubble constant H0H_0H0 is used to evaluate the timescale of the universe, yielding an approximate age of 14 Gyr. The study defines a proportionality factor k=Eobs/Einitk = E_{\rm obs}/E_{\rm init}k=Eobs/Einit to conceptually represent the wavelength stretching, without requiring numeric values for EinitE_{\rm init}Einit. This framework allows future research to potentially reverse-calculate EinitE_{\rm init}Einit using the estimated universe age and CMB observations, which may provide insights into the state of photons in the early universe and the initial cosmic environment. The work is positioned as a simple, yet conceptually informative, evaluation within the light universe theory.