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Abstract

We investigate classically non-singular bounces caused by dark energy. In the
presence of positive spatial curvature, vacuum energy, either in the form of a
cosmological constant or a scalar field potential, allows for an open set of
initial conditions leading to non-singular bounces, without any violation of
the null energy condition. We study anisotropic Bianchi IX cosmologies, and
demonstrate that they can even have multiple bounces, accompanied by intricate
evolutions of the anisotropies that provide a non-singular analogue of
mixmaster crunches. The relation of these solutions to more complete
cosmological models, as well as to the recently proposed swampland criteria,
are briefly discussed.