I used to think there was a rule. Many science fiction short stories followed the rule, any remaining suck out.
The template was simple, two or three paragraphs of introduction, introducing strangeness to the reader, a new environment, an action you couldn’t do on Earth. There followed another section, filling in backstory, an alternative history explaining why things on the first page looked strange. The story would restart after the history.
I loved the alternative histories, part of a personal fascination with the future. However, my first novel had a vast amount of backstory, several thousand years of events, migrations, disasters, treachery and deceit, success tainted with failure. The template wouldn’t work, and indeed it’s rare in novels.
I had to give readers enough information to let them understand my world, but information had to be ladled out. I explained features as my characters encountered them. An extraordinary engineering feat to us would appear mundane to them, so I needed to describe everything in plain terms. We would see their world as a tunnel, immense, curving walls towering miles above our head, the lower section carpeted with life. Characters travel through this world, describing things with a factual voice, as you would describe fields and forests; they see their world as natural, and one of my novel’s themes covers a possible fusion between nature and technology. Sufficiently advanced technology may be indistinguishable from nature; if you can spot a difference, the technology isn’t advanced enough.
I didn’t want a chapter dedicated to describing the world’s shape, so I dotted the required information around the novel, feeding the reader with enough images to let them see the world I’ve created. I loved the feeding process in the short stories I mentioned above, but I spread the process out through several chapters, turning it into a subtle feed, a showing not a telling. Descriptions were layered in with actions, there must be a reason for a character to look at the vast walls in the world I’d made. I nudged people into seeing this different world, one brick at a time, rather than force feeding readers into my vision. This helped readers understand the world their way. The readers needed to work, but they would bring their own perceptions and models to bear, making their journey easier. They would start from their imaginations, not mine. Readers are intelligent people and writers should not baulk at using that intelligence.
Exposition exists, but it comes later, once I’ve foregrounded material with hints and pointers. It was necessary to hand out history to the readers, but laying out the world before the history allowed them to create links in their own minds. As a science fiction reader I love the strangeness of encountering new technology, a strange society, or finding two or more familiar items interacting in an unusual way. Stretching out the encounter’s enjoyment may be part of making science fiction more accessible and enjoyable.