  Negative lambda gravitational effective field theories dual to holographic
CFTs have potentially realistic cosmological solutions. Generic cosmological
solutions of these effective field theories have scalar field evolution that
can lead to a period of accelerated expansion when the scalar field is at
positive values of its potential (Fig. 1). If such a model describes our
universe, significant evolution of dark energy is expected over a Hubble time
as the scalar descends from positive to negative values of its potential
towards the AdS extremum. Our recent observational study 2305.04946 based on
supernova and baryon acoustic oscillation (BAO) observations suggests that
significant evolution of dark energy associated with a descending scalar field
may be preferred by data (Fig. 2). Taking a linear approximation to the scalar
potential around the present value, a standard likelihood analysis gives an
$e^{- \chi^2/2}$ distribution in which $dV/dt$ is presently negative in $99.99
\%$ of the distribution, with a mean fractional variation of the potential of
$36 \%$ over the period $z \lessapprox 2$ over which supernova data is
available. In this note, we review these theoretical and observational results
and provide an update on the question of how the physics of these cosmological
solutions can be related to the physics of the underlying CFT.
