“The Bean” in the Throes of Computronium Boot Drive Failure (Black Hole Era #3)

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-realistic 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 substrate for Turing-complete computation which has run up against the limit for information density that our physics impose. If you’re part of a civilization that ancient, chances are you've fully exhausted Moore’s Law, amirite?

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 begins, the heat death of our universe.