For me, Olaf Stapledon has held the record for extended epics. His Last and First Men and Star Maker imagine billions of years into the future. I classify them as Science Fantasy because their speculations are grounded in natural and social sciences. Other authors, such as James Blish in Cities in Flight, imagination various scenarios of the end of the Universe, usually into or through the "big crunch" that would accompany the "big bang" for a closed Universe, some tens of billions of years in its future.
The City at the End of Time by Greg Bear is of another order altogether. Apparently based upon a flat cosmology, or perhaps the acceleratingly open cosmology that is now fashionable, it links a time in the near future with one that is a hundred trillion years away (that is an American trillion, a million million). There is a hint of social science here, but the ESP-ish methods of the protagonists and the immensely godlike aspects of other beings puts this book, for me, in the Future Fantasy category.
Rather than detail the plot of a story of near-impossible questing, I find a few ideas to be of interest:
- Final Sin replacing Original Sin,
- Text as the ultimate Observer, and Memory its Preserver,
- Chaos as an engineered quality, and
- Cats (Schrödinger's, or others'?) as ultimate Judges of
- A (perhaps) intelligent Black Hole-ish something called the Typhon (a thinly-disguised temporal typhoon), the enemy of time and order.
I found myself wondering, as I neared the end of the book's 476 pages, if it could not have been told in half the space. Greg Bear's prose can be compelling, even breathtaking. Yet it frequently dragged for me. Epic stories need not require epic endurance of a reader.