Chicago in the Throes of Computronium Boot Drive Failure (Black Hole Era #1)

In hundreds of trillions of years, when even the white dwarf stars have exhausted their fuel and the universe has gone completely dark, sentient life may still flourish by extracting angular momentum from black holes. In this imagined but plausible, physically consistent future, the entire life of the universe up til then may be recreated many billions of times over in the form of virtual simulations.

These would be hosted on a suitable medium such as computronium, a term for physical substrates which have run up against the limit for information density that our physics impose upon Turing complete calculators. Indeed, Moore's Law only takes you so far...

The simulation era is not forever though. Eventually the black holes will evaporate via Hawking radiation, and the computronium drives will fail, finally snuffing out all sentience in our universe!

Maximally entropic timelike infinity thus begins: the heat death of our universe...