There is a very sharp distinction drawn between hard science fiction, and the less-particular, broader genre of sci-fi. For the record, Babylon 5 was explicitl

There is a very sharp distinction drawn between hard science fiction, and the less-particular, broader genre of sci-fi. For the record, Babylon 5 was explicitly designed to be The Lord of the Rings in space. It's fantasy in sci-fi dress-up. Similar things could be said for Star Trek, Star Wars, and other sci-fi staples. Hard science fiction like The Expanse, or most of the collected works of Arthur C Clarke, Alistair Reynolds, Kim Stanley Robinson, and Robert Forward present entirely self-consistent universes set in the future with logical extrapolations of technical capability governed by physical law. Some people don't care for the distinction, but there are also those of us that have very strong preferences for ONLY readying hard science fiction. I like to feel that I learned something, or that the book describes societies that might someday come into being, or alien cultures that might realistically exist.