  We analyze the influence of the evolution of light absorption by gray dust in
the host galaxies of type Ia supernovae (SNe Ia) and the evolution of the mean
combined mass of close-binary carbon-oxygen white dwarfs merging due to
gravitational waves (SNe Ia precursors) on the interpretation of Hubble
diagrams for SNe Ia. A significant increase in the mean SNe Ia energy due to
the higher combined masses of merging dwarfs should be observable at redshifts
z > 2. The observed relation between the distance moduli and redshifts of SNe
Ia can be interpreted not only as evidence for accelerated expansion of the
Universe, but also as indicating time variations of the gray-dust absorption of
light from these supernovae in various types of host galaxies, observational
selection effects, and the decrease in mean combined masses of merging
degenerate dwarfs.
