Abstract
In this paper, we suggest a framework for cosmology based on gravitational
effective field theories with a negative fundamental cosmological constant,
which may exhibit accelerated expansion due to the positive potential energy of
rolling scalar fields. The framework postulates an exact time-reversal symmetry
of the quantum state (with a time-symmetric big bang / big crunch background
cosmology) and an analyticity property that relates cosmological observables to
observables in a Euclidean gravitational theory defined with a pair of
asymptotically Anti-de Sitter (AdS) planar boundaries. We propose a microscopic
definition for this Euclidean theory using holography, so the model is UV
complete. While it is not yet clear whether the framework can give realistic
predictions, it has the potential to resolve various naturalness puzzles
without the need for inflation. This is a shorter version of arXiv:2203.11220,
emphasizing the effective field theory point of view.