We analyse the measurable components of photon flux from distant cosmological sources by examining the relationship between wavelength and energy distributions in both emitted and observed spectra, within the framework of Tolman’s surface brightness test. Our model offers a quantitative approach to interpreting these observations without invoking cosmological expansion. We propose that the observed dimming of distant objects arises not from wavelength stretching over time, but from the decreasing spatial density of higher-energy (shorter-wavelength) photons with increasing distance. Meanwhile, lower-energy photons dominate the observed flux, creating an apparent redshift pattern. This effect, we argue, is a statistical consequence of emission dynamics and distance-based dilution, rather than a manifestation of expanding space. In our framework, photons retain their energy during propagation, and the shift in observed spectra reflects the energy-dependent distribution of flux—not a post-emission loss of energy of individual photons. This reinterpretation preserves the observed brightness–wavelength scaling and complies with Tolman’s test, while challenging the conventional explanation based on metric expansion.