Last Joule

Set in the sub-kelvin quiet of the degenerate era, The Last Joule is a hard-SF novella told entirely in transmissions between two minds guarding the last of their lineage's memory. Ves orbits a dead white dwarf, forced to prune an ancient archive because every erased bit sheds heat that could quench her superconducting mind. Four light-years away, Orrin survives on the edge of a spinning black hole whose horizon is the coldest place in the universe. When a structured signal begins leaking from the ergosphere in the archive's own language, survival demands more than compression. It demands the oldest escape in computing: copy one answer, then run everything else backward until every register returns to zero.