  A variety of scenarios for early-universe cosmology give rise to a population
of primordial black holes (PBHs) with a broad spectrum of masses. The
evaporation of PBHs in such scenarios has the potential to place the universe
into an extended period of "stasis" during which the abundances of matter and
radiation remain absolutely constant despite cosmological expansion. This
surprising phenomenon can give rise to new possibilities for early-universe
dynamics and lead to distinctive signatures of the evaporation of such PBHs. In
this paper, we discuss how this stasis epoch arises and explore a number of its
phenomenological consequences, including implications for inflationary
observables, the stochastic gravitational-wave background, baryogenesis, and
the production of dark matter and dark radiation.
