Long ago(I guess around 2006),I read this and was struck by the amazing ideas. I couldn't remember the author, though, just the title. Then I came across some of Greg Egan's other works a decade or so later and it felt similar, so I checked and sure enough, same author. Fantastic ideas, although his character development is a bit lacking in my opinion.
"A bit lacking" is putting it mildly. I love Egan, but he wraps his hard sci fi worldbuilding efforts in the minimum veneer of a story that can be written to tell you about the universe he's imagined.
- Appears a very well documented, well researched (in that he does his homework) author
- This might sound trite, but ... his per-book websites have this '90s internet feel to them, which is grand. (And, in a way, an indicator of quality ...)
Interestingly, Egan pokes some holes in his own work here: https://gregegan.net/PERMUTATION/FAQ/FAQ.html (spoiler warning) and I think is all the more credible for doing so, totally on brand for a hard sci-fi author.