You describe your books as science-fantasy, and the fantasy is fine, but, well, you know, where's the SCIENCE?
Oh, pretty much the same place it is in most of our lives: it's just there, and we hardly ever think about it. At least I don't, and therefore neither do the Kelts. So the starships go faster than light; big deal. I don't know the mechanics of how they do it and I completely do not care...
And I try to keep it that way, in my life as in my art: I stuffed some more memory into my laptop, I can replace a fuse when one blows, I know a lot of geology and some chemistry and astronomy; but that's it. I'm just not into science and I never was, and if you open one of my books expecting to read hot high-end technostuff you've picked the wrong girl.
But here is some of what I believe, scientifically speaking (I have a strong feeling these theories are not original, but hey, they work for me...):
The Real Theory of Electricity: a whole bunch of electrons go chugging along the wires, running really really fast, 'cause, oh, I don't know, protons are chasing them. Then they jump out into your lamp wires, they runrunrun to the bulb, they EXPLODE and that makes the light (or the TV picture or whatever); then they all die and fall on the floor and their little dead electron corpses make the dust bunnies. There's a Nobel Prize in there somewhere, the letter's probably already on its way from Stockholm. (Actually, the fuse blows because the poor tired little electrons just can't run fast enough to fill all the wires going to all those appliances...)
The Real Theory of Blood Circulation: We are all solid inside, like potatoes. We have leg blood, arm blood, head blood (source of headaches when it's not fresh enough, or if there's too much of it in your head then you have nosebleeds), finger blood--that limey guy was wrong, it so does NOT move around! That's why when the doctor tries to stick your arm or finger for a blood test, and none comes out, it's because all the arm blood or finger blood is temporarily used up, or it's scared and it ran away (well, you probably tried to run, too, when you saw that needle), and you have to wait for it to come back. Face blood, too: that's why when guys cut themselves shaving, they don't bleed to death--there's just not enough face blood for it. (Your heart pulses not because it's pushing the blood around but because it's trying to keep it where it is.) Another Nobel there...what am I going to wear to the ceremony??
(And I haven't even finished working on the Real Theory of Aviation--or railways, for that matter: what DO they nail those tracks to? How come they don't slip around all over the place?? Do they just have really really long spikes?)
Seriously, I'm with whomever on this one: any sufficiently advanced technology is indistinguishable from magic. Think about elevators: you get in a little tiny room, the door closes, when it opens again you're someplace else. We hear those stories about simple country folk who flip out the first time they take an elevator--they think it's black magic. Well, I'd probably freak, too (and sometimes I do, when the elevator gets stuck): it is extremely weird to think about--but logical once the principle is explained.
Or television. Now there's black magic for you! Invisible talking pictures in the air that you can only see if you have this special machine--oh, yeah, right, explain that to your great-great-grandfather! Or battleships--if they're made of iron, and we know they are, then how the heck do they float??? (And don't tell me it's because they're hollow! Do you have any idea how solid those suckers really are?? `Cause they HAVE to be--they're battleships!) And if battleships are made of iron and they float, how come submarines--also made of iron--SINK? And they even have big old tanks of air--I guess--for the sailors to breathe, so wouldn't that make the subs come up even faster??? Or never go underwater in the first place--you know how hard it is to make a plastic bottle full of air sink in the bathtub, so there you are.
I have to go lie down now, steam is coming out of my ears...
The point is, we don't think about all this stuff because we're used to it. Same with the Kelts. They got big-time science so long ago, and it seemed like magic so they just accepted it; they often choose to go low-tech--horses, not aircars--but when their technology was taken away they were annoyed and they wanted it back and they went out and got it again. Nobody but the scientists really knows how or why it works.
And neither do we know about our own, even in our limited little way. So don't bust my chops because I don't give you detailed working instructions for the Curtain Wall or the Firedrake. It's magic, and it would make sense if we knew about it, but we don't. Just like submarines. And that's all I have to say.