The phenomenon known as ?supernova timescale stretching? was discovered by measuring the observed light curve broadening and by measuring the rate of spectra evolution (aging) for Type Ia supernovae. In modern cosmology this phenomenon is widely considered as one that rules out the ?tired light? hypothesis. The redefined ?tired light? hypothesis presented in this paper not only agrees with the supernova timescale stretching but actually explains it without employing universe expansion. Using Type Ia supernova spectra template, I have conducted a computer simulation study of light propagation from a supernova to an observer based on the tired light assumptions. The results of the simulation for ?at rest? UBVRIYJHK bands do not contradict the astronomical observations related to light curve broadening and spectra aging.
