This story takes place in roughly 6 million years, when the entire Milky Way has been populated by humans or their evolved (naturally or artificially) offspring. The universal speed limit (of light) applies, which forces us to get creative if we want to explore the galaxy. Sometime in the distant past (but far in our future), it was faddish amongst the rich and powerful to create shatterlings. The idea is to clone yourself several times (1000 clones seems to be the norm), equip your shatterlings with souped up ships and then have them go off one by one in all directions and explore the galaxy. Every couple of hundred thousand years or so, they all get together and exchange memories. Not just by telling stories — there is some kind of actual memory-sharing technology implied, so that each one really does have the memories of all the others, somewhere deep down inside.
Key to the whole shatterling idea is a method of preserving life throughout the long, long sub-light speed voyages between stars. There are two solutions, first your standard freeze’n’thaw, then something more interesting involving “synchromesh” and stasis chambers, which allow the user to compress time, so that an hour on the inside is a decade on the outside (or whatever compression rate is desired).
Thus the shatterlings roam the galaxy, with no real goals other than to soak up knowledge, experience the wonders humanity creates, and maybe help out a civilization here and there by building a stardam (to safely enclose and neutralize a soon-to-be supernova) or serving justice in a local micro-war. They are more-or-less immortal gods, who dive in and out of history as they please. They are really just going around in circles, traveling through the same regions of space, if not the same planets too, each time around on the galactic circuit, but since ~200,000 years of surface time have passed since the last visit, the situation on the ground is often totally different. The Lines (each Line being a set of clones from one individual) actually maintain something called the “Universal Actuary,” which gives continually updated probabilities of existence for planetary or multi-world civilizations and empires. “Let’s see, the last UA entry for the Poobabian Confederacy of Worlds is only 4,000 years old, but we are 10,000 years out …. there’s currently a 62% probability that the Confederacy is still in existence, but when we will arrive the probability is only 14%…” The Lines derisively refer to everyone else as “turnover” civilizations. Rise and fall of empire is universal and continual.
Anyway, lots of cool ideas. The plot is good, but not as great as some of the world (or should I say “galaxy”) building. The Gentian Line, from Abigail Gentian, gets all but wiped out in a surprise ambush during one of their memory-sharing reunions. They get to find out why. Key to the plot (which I won’t totally spoil here) are two other types of beings that have acheived immortality in this galaxy. First are Machine People, robots who probably originated with some human intervention but who are now totally independent artificial intelligences. Then there is a unique personage known as the Spirit of the Air. He was a human from about the time of the original shatterlings, but took a different path – little by little, he downloaded his consciousness into a computerized network of ever-increasing sophistication, until he wasn’t quite human any longer. Kind of like Ray Kurweil and his singularity.
I’m not sure why the whole shatterling fad seemed to be just a singular event. Was only that one culture advanced enough to make it possible, and none of the turnover civs have achieved that level in all the time since? Furthermore, even with the time compression and all, the shatterlings have lived way beyond a normal (to us) life expectancy in real time; why hasn’t their longevity tech migrated to other civs?
I always try to predict in my mind where the author is trying to take the story, and what the big twist is going to be, and I was kind of misled on this one by the flashback entries which precede each section. I kind of think my version would work better that the real twist in the book: the flashbacks are about Abigail’s experience with Palatial, a virtual reality simulation of a fantasy kingdom. She’s the good princess, one of her playmates becomes her evil half-brother prince. They eventually go to war … I thought it would have been cool if the current attack on the Gentian Line was a long dormant continuation of the battles they fought in Palatial, but such was not the case.