  Time is a parameter playing a central role in our most fundamental modeling
of natural laws. Relativity theory shows that the comparison of times measured
by different clocks depends on their relative motions and on the strength of
the gravitational field in which they are embedded. In standard cosmology, the
time parameter is the one measured by fundamental clocks, i.e. clocks at rest
with respect to the expanding space. This proper time is assumed to flow at a
constant rate throughout the whole history of the Universe. We make the
alternative hypothesis that the rate at which cosmological time flows depends
on the dynamical state of the Universe. In thermodynamics, the arrow of time is
strongly related to the second law, which states that the entropy of an
isolated system will always increase with time or, at best, stay constant.
Hence, we assume that time measured by fundamental clocks is proportional to
the entropy of the region of the Universe that is causally connected to them.
Under that simple assumption, we build a cosmological model that explains the
Type Ia Supernovae data (the best cosmological standard candles) without the
need for exotic dark matter nor dark energy.
