  Type 1a supernovae, SNeIa, are used as standard candles in cosmology for
determining the distances of the galaxies harboring them. We show that the
luminosity of an SNIa depends on its distance from us when physical constants
(the speed of light $c$, the gravitational constant $G$, and the Planck
constant $h$) are permitted to evolve. It is because the Chandrasekhar mass of
the white dwarf that explodes to create SNIa depends on the values of the
constants at the epoch the SNIa is formed. We show that the SNeIa luminosities
were up to about four times higher in the past than they are now. Thus, the
luminosity distance estimation of the earliest SNeIa could be off by up to a
factor of two. Cosmological parameters, determined with this correction applied
to the redshift vs. distance modulus database (Pantheon SNeIa), are not very
different from those from the standard $\Lambda $CDM model without this
correction, except for the dark-energy density and the curvature energy
density; the latter increases at the cost of the former. Variations of the
constants are given by $\dot{G}/G=3.90(\pm 0.04)\times 10^{-10} yr^{-1} $ and
$\dot{c}/c=\dot{h}/h=1.30(\pm 0.01)\times 10^{-10} yr^{-1} $ at present. These
variations are valid only when $G$, $c$, and $h$ are permitted to vary
concurrently rather than individually.
