Incandescence is a science-fiction novel set millions of years in the future. Humans have evolved into immortal data streams that can travel through the galaxy on cosmic rays and reconfigure themselves in any shape they desire. They are know as the Almalgam.
At the core of the galaxy live the mysterious Aloof, who have rejected any attempts by the Amalgan to expand into their territory. The Aloof allow the Almalgam to travel through their territory, but not to stop.
Rakesh is a bored member of the Amalgan who has spent decades looking for something exciting and challenging to do that has not already been done. He is approached by a traveller who was woken during a journey through Aloof territory and told about a meteor that contained traces of DNA. The Aloof want a child of DNA, an Amalgan, to examine it. Rakesh accepts the challenge and sets off with a friend to travel for thousands of years into Aloof territory.
Roi and Zak are bug like creatures living inside a translucent rock world called the Splinter that orbits in a sea of light called the Incandescence. Roi and Zak's scientific curiosity make them outcasts in a subsistence, duty bound society, as they try to work out the true nature of the Splinter. When the Splinter is shunted out of orbit and begins to experience intervals of darkness, Roi and Zak start recruiting others to find out what happened.
Incandescence is hard science-fiction, in both concept and content. Roi and Zak discover many scientific qualities of the Splinter, which are described to the reader in words when diagrams might have been more appropriate. Egan does include a couple of diagrams but I think he could have attached an appendix with more. At the least, a glossary would have been welcomed, as his scientists made up names for a lot of their discoveries.
This reviewer has only year 12 physics and found it hard to understand Incandescence in places. Without a desire to find out how the two separate stories would interlink, the novel might not have been read to the end. This would have been a shame because Egan does some interesting exploring of why society's stagnant.
The Splinter society is one of unquestioning duty, where everything has been done the same way for eons and people haven't the energy to question the world they live in. They are emotionally inert, which is why I found some of the scenes where concerns where shown for their offspring to have a tacked on quality. It felt like Egan needed a reason for the Splinter's stagnating, uncreative society to want to survive the looming catastrophe.
The ending is both satisfying, in theme, and unsatisfying, in plot. Incandescence is not as good as the high concept Quarantine or as well written as the character driven Teranesia. A reader who has a physics degree or perhaps the patience to continually re-read sections, might rate the novel higher.