The Coincidence Problem and the Swampland Conjectures in the
  Ijjas-Steinhardt Cyclic Model of the Universe
  In the Ijjas-Steinhardt cyclic model, the universe passes through phases
dominated by radiation, matter, and a dark energy scalar field, with the value
of the scale factor increasing with each cycle. Since each cycle terminates in
a finite time, it is straightforward to calculate the fraction of time that the
universe spends in a state for which the matter and dark energy densities have
comparable magnitudes; when this fraction is large, it can be taken as a
solution of the coincidence problem. This solution of the coincidence problem
requires a relatively short lifetime for each cycle, but unlike in the case of
phantom models, there is no fixed upper bound on this lifetime. However, scalar
field models satisfying the Swampland conjectures yield sufficiently short
lifetimes to provide a satisfactory resolution of the coincidence problem.
