The story follows two characters in the far, far future. Rakesh is a citizen of the Amalgam, a galaxy-spanning civilization home to an immeasurable host of organic beings, artificial intelligences, and uploaded personalities. An adventurous man (or male-identifying uploaded intelligence), he has grown restless living in a society that tamed the galaxy and seemingly discovered everything that can be discovered eons before he was born.
The story begins when he is approached by a stranger named Lahl, who tells him that she has evidence of a species unknown to the Amalgam, deep in the galactic core. The core is the domain of the Aloof, an enigmatic civilization that has spurned the Amalgam's attempts to communicate for millions of years. Despite this, they broke their silence long enough to show Lahl- who was taking a shortcut through Aloof space to cut a few thousand years off her travel time- a meteor containing fossilized DNA-based cells that belong to no known known species, and that must have originated in the core itself.
For their own incomprehensible reasons, the Aloof have charged Lahl with the task of finding a "child of DNA," a member of a species born from the smae panspermia that gave rise to the sample and to many of the species of the Amalgam, willing to help seek out the DNA's source. As a human, Rakesh fits the bill. Presented with this opportunity, Rakesh agrees to enter the domain of the Aloof in search of the discovery he thought he'd never have a chance to make.
Roi is an alien living in a strange world of tunnels called the Splinter, where the strength and direction of of gravity depends on your location and everything is brilliantly lit by the all-pervading light they call the Incandescence. She lives a normal life, tending crops nourished by the light and heat of the Incandescence with the rest of her work team, until the day she meets Zak in the weightless heart of the splinter, the Null Line. Too old, eccentric, and unhealthy to be targeted for recruitment by a work team, he spends his time trying to understand the nature of their home, seeking lost records and studying the shifting patterns of weight around the Splinter. Like everyone she knows, the question of why their world is as it is is something she had never taken an interest in before, but her encounter with Zak awakens, for the first time in her life, to understand. So overwhelming is her curiosity that it overpowers her natural biochemical bonds joining her to her work team, and she begins returning to the null line to learn more from Zak. Together, starting with simple experiments about motion in the weightless environment of the null line, they begin probing into the nature of their strange home. As time passes, their discoveries lead to an ominous conclusion- the Incandescence is not the safe, eternally static place they had thought, and their growing understanding may be the only way to preserve the Splinter from catastrophe.
I really enjoyed Incandescence, but I have to be a bit cautious in recommending it. If you like hard science fiction that really delves into the science, I recommend it strongly. If you don't, you're likely to find it rather dry.
For those who do like especially science-heavy hard science fiction, this book has much to recommend it. Egan creates two radically different but fascinating environments in the Amalgam and the Splinter. I liked the way the Amalgam is introduced- it initially seems like a strange but somewhat recognizable future, but it quickly becomes apparent just how alien it really is. Despite that, it didn't have the chilly, eerie feeling that I often associate with settings involving the extremely distant future, posthumanity, and/or large-scale interstellar civilizations without faster-than-light travel. I enjoy that feeling, generally speaking, but Incandescence's Amalgam was a pleasant change of pace. The Amalgam characters were generally not delved into deeply, and their psychology and mode of existence was quite alien in some ways, but to me their personalities and interactions had a sense of good-natured warmth to them that I don't often see, and I quite enjoyed that.
The Splinter is a fascinating creation that should intrigue people who like science fiction about life in environments radically different from our own in the vein of Hal Clement, Robert Forward, or Stephen Baxter. There have been many books about bizarre environments, but incandescent is the first SF novel I'm aware of to use a location- an object closely orbiting a black hole- where the effects of relativity can be readily seen in day-to-day life.
One of the things I enjoyed was that the book is about science not just as an existing body of knowledge, but as a process of learning and discovery. Again, this is not the sort of thing that can be recommended for people of every taste, but I found it very satisfying to follow Roi as she learned the underlying laws behind her world, gradually seeing things that seemed meaningless, baffling, or arbitrary come together into a coherent, comprehensible whole. Egan is also quite ingenious in showing ways that intelligent beings might be able to gain a sophisticated understanding of physics in an environment where the science that drove so much of it's advancement on Earth, astronomy, is impossible.
Greg Egan's Incandescence
