My first real S/F love was Hard Science Fiction. Writers of the genre have a good grasp of current science and extrapolate where it might go in the future. They may make up something fantastic, but they go out of their ways to make it at least seem plausible. They do their best not violate the known laws of physics.
A lot of that S/F was written by actual scientists and engineers. The amazing science and technology of the story was the story. Sometimes it was the whole story. The better writers would squeeze in some character development and decent dialog.
Later the market was flooded with writers who tended more towards being Liberal Arts types rather than Hard Science types. Often they didn’t know a thing about how the technology all around them functions, never mind extrapolating new science. Their stories could be set in any number of genres. The starships, robots, and flying cars could just as easily be pirate ships, remote island natives, and war canoes. Heck, why not covered wagons, Indians, and horses?
That’s not to say those stories are bad. They can be quite good. Take Star Wars for example. Yes, it’s not hard science. It’s got wizards. I mean Jedi Knights and magic. I mean the force. The one time the movies tried to put a scientific spin on it, it was a dismal failure. Midichlorians, really?
Over the years I’ve branched out well beyond my first love of Hard S/F. I’ve come to realize a good story is a good story. If you want to write about faster than light ships with explaining how they might work, go right ahead.
There’s just one big caveat: do not mess up the very basic stuff of commonly known science. Your readers will not forgive you for that.
-Raymond M. Coulombe