personally, I find realism is less important than plausibility. If you can portray the event or action as having the possibility of happening (whether through magic, genetic mutations, or some fancy technology) than it doesn't matter if it is in effect unrealistic. There's no need to go into huge complex explanations of events or why things work. Simply give an overview. If I wanted to know every realistic detail of cold fusion, I'd get a text book. All you need is a basic understanding of the concept to avoid obvious mistakes and then its as simple as just writing and giving simple overviews of information if they are necessary.
Complete non sequitur... I had a friend in college whose answer to any repair situation was, "Just fuse it, man!"
"Realism" in fiction depends on proximity to the present. If your fiction is set in the near future, you can not deviate far from science as we presently understand it without losing "believability". On the otherhand, 100 years ago we did not have antibiotics, television, computers, telephones, superhighways, air conditioning in homes, MRIs, Xrays in hospitals, space shuttles - the list is long. So, if your fiction is set well into the future, you can speculate any way you want. Just don't attempt to be a "junior physicist" and define "how" the new technology was made possible. Simply write using the result of the new technology.
And don't make what is, to my mind, one of the main problems with sci-fi (a la star trek) by having everyone be an expert in particle physics/medicine/quantum mechanics or whatever the subject of discussion is. How many people in real life understand how a nuclear reactor works? Or even the electronics in their clock radio? People don't have to know how something works to use it.
Op, I don't entirely understand your question. The confusing bits had to do with the primitive sword setting and the cold fusion setting. How does that mesh? SF: Personally, I don't care much about the science. It's kind of hollow without the philosophical exploration of life. I'd read your novel in a sec if it focused on the cycle you mentioned. That sounds like an existential exploration to me, mostly about the absurdity of life. That generalizes to the individual and how many people waste life making the same mistakes over and over.
Also rather off topic, this plot vaguely reminds me of "A Canticle For Leibowitz." Mankind just not learning from its mistakes, and repeating them over and over. Echoing TheAdlerian's comments, I'd be more interested in the philosophical/social/emotional side of the story than in the hard details of how physics work. I'm the same way with movies of this sort; I find I get quite irritated when they focus all on the science/plot and not enough on the characters. If your science is consisent with the world's rules then it's fine with me. Consistency is what makes something in fantasy/SF realistic, however outlandish it might be in reality.
I enjoy scifi and I enjoy the science. I like hard scifi, but not everyone does. I think it will help to know who your audience is going to be. However when you do explain the cold fusion, do it here and there. Don't try to explain it all at once. I think it might be easier to focus on a small setting and cast, and slowly bring in the other outside world. But I think you should bring in that outside world because it sounds interesting. Or should I say worlds.
Ok good, Very good Matrix loop like setting. Why? In the end, if you are the author, if you say that your hero can fight all day, ride a horse in full plate and then make love to his fair maiden then that is the physical limitations of your "Human" which may or may not have any bearing on the limitations of a todays "human" Not to mention the effects of magical or scientific augments or genetic engineering, etc... etc... etc.... Ok works... you have an idea of what you are talking about. Good. This is tricky and depends on your skill as a story teller. If you make it sound realistic (like people climbing in air vents and such) then it is realistic. What feels good to YOU? (because YOU are the only one writing this story, unless you have co-authors and then I would suggest you talk with them) I have no idea what you mean by this question? The presence of realism is a requirement as if it feels phony it destroys the story. You are the one writing the story, write what comes out of you... not what comes from me or anyone else for that matter. They are not writing your story.
I suppose in the end of things what I am really trying to say is that "Just don't let anyone else discourage you from writing what you want to write" Write the story as you want to write it. First Once you have it written, there will be time to edit and revise it till your hearts content;and there will be lots and lots of painful tedious revisions and editing again and again. Sorry just poking fun at ya on that last bit.
