  Recent developments in string compactifications demonstrate obstructions to
the simplest constructions of low energy cosmologies with positive vacuum
energy. The existence of obstacles to creating scale-separated de Sitter
solutions indicates a UV/IR puzzle for embedding cosmological vacua in a
unitary theory of quantum gravity. Motivated by this puzzle, we propose an
embedding of positive energy Friedmann-Lemaitre-Robertson-Walker cosmology
within string theory. Our proposal involves confining 4D gravity on a brane
which mediates the decay from a non-supersymmetric false AdS5 vacuum to a true
vacuum. In this way, it is natural for a 4D observer to experience an effective
positive cosmological constant coupled to matter and radiation, avoiding the
need for scale separation or a fundamental de Sitter vacuum.
