The discovery of the cosmic expansion had a profound influence on our
understanding of the past history of the universe. This talk outlines the
future history of the cosmos as it continues to expand: we consider the
evolution of planets, stars, galaxies, and the universe itself over time
scales that greatly exceed the current cosmic age. The discussion starts
with the effects of accelerated cosmic expansion, which causes every galaxy
cluster to become its own island universe. Within these bound structure, the
lowest mass stars continue to burn hydrogen over much longer times, and evolve
off the main-sequence near the epoch when conventional star formation ends. The
stellar population is thus converted into degenerate remnants -- neutron stars,
white dwarfs, and brown dwarfs. Although the supply of interstellar gas grows
depleted, star formation continues at an attenuated rate through brown dwarf
collisions. As the galaxy evaporates via dynamical relaxation, dark matter
particles are accreted by white dwarfs, where they annihilate and keep the
stellar remnants relatively warm. Over longer time scales, the degenerate
objects evolve and sublimate through the decay of their constituent nucleons.
When the white dwarfs and neutron stars disappear, black holes are the
brightest astrophysical objects, slowly losing their mass as they emit Hawking
radiation. After the largest black holes have evaporated, the universe slowly
slides into darkness.