
Stross' 2005 novel Accelerando [1] set around the technological singularity, is made freely available by the author
In addition to various standalone science fiction novels, Stross also has a couple of long series, the Laundry Files and Merchant Princes / Empire Games.
The setting of the Laundry Files is a mix of magic as a branch of applied math, UK secret service bureaucracy and lovecraftian horror. Stross' laundry files novella "Down on the Farm" is available to read here [2].
Stross' early novelette A Colder War, published in 2000, can be read here [3].
The Merchant Princes series is also a great yarn. The setup is that parallel universes with alternate history Earths exist, and tech journalist Miriam discovers she belongs to a bloodline who can "jaunt" into a parallel medieval Earth. One thing Stross does well is applying the science fictional / economic lens of "OK, so if that were true, then what happens?", so instead of simple fantasy tale we get an exploration of stuff like the transdimensional narco-courier-for-guns trade, or what would Rumsfeld do if transdimensional narcoterrorists made a severe error of judgement and picked a fight with the US? The series gets pretty dark...
[1] http://www.antipope.org/charlie/blog-static/fiction/accelera... [2] https://reactormag.com/down-on-the-farm/ [3] https://www.infinityplus.co.uk/stories/colderwar.htm
I'm going to try and work through it here.
As a civilization spreads, the outer nodes get "dumber" as the speed of light begins to cut into bandwidth/response. So agents get much more bang for their buck increasing their complexity while staying inside the light-second (or light-hour, with caching) sphere, right up until computational complexity is nearing the atomic level (i.e., "computronium").
So you get these planetary-sized shells of computronium, bound by the bandwidth limit of C. Human-equivalent intelligence gets a simulation space that's larger than a few hundred thousand Earths[0]. I'm probably not explaining it all that well, but Accelerando is free on the internet[1]. Like I said - not amazing literature, but pretty neat ideas.
The sad part of all this is that civilizations reach this hard halt where they've converted their systems into computronium - they come to a sudden halt, and no way to press on outwards, as they're all held in thrall to the light sphere.
[0] I challenge the notion of "simulation space" or even the notion that "downloaded humans" would stay human for very long (they wouldn't). Another problem: Stross' system is a little bit magical in terms of its infrastructure, because a fog of undifferentiated laser-connected micro-computers is going to have terrible latency across a 1 AU distance, and there's no way for a central authority to route things. But Stross is way smarter than I am . . so who knows?
[1] https://www.antipope.org/charlie/blog-static/fiction/acceler...
[1.a] Unrelated, but check out "A Colder War", also downloadable. CIA Cold War shenanigans meets Cthulhu! Features some obscure Cambrian species. This sent me down a rabbit hole of learning about the incredible early animals of our planet's history.
It's not at all about uploading, but it is very much worth a read.
Also, while I'm at it - I don't know how many times I've read A Colder War but the ending still gives me the creeps.
