 Bear called City at the End of Time his " longest and most ambitious science fiction novel " he has written for a while . He said it is a " significant departure " from any of his previous works , and that it has a future history unlike anything he had tackled before . In an interview with Andromeda Spaceways Inflight Magazine in September 2008 , Bear said that what inspired him to write City at the End of Time was the question , " What if we 're still primitive in our thinking [ about physics and cosmology ] ? " , and this led to the idea for a story of " a Universe that goes on and on and on , and how reality might have to be changed by that circumstance . " 
