@Radagast
I posit magic is a powerful natural Quantum force in the multiverse, but not normally present in any quantity on earth, until something releases it / attracts it to earth where it acts like oil on water and suppresses other energetic waveforms, such as explosions and electricity.
That could be a good approach if I were willing to try and reconcile magic with physical laws. (And I say could only because my physics knowledge isn't sufficient to think through all aspects - it might be a super great approach!) However, for story reasons, I don't want to go there. I want to let magic be a limited exception to physical laws, capable of suppressing or producing effects in ways that simply do not fit with those laws. There will be no physical reason why humans can't control explosions or electricity; it's because that was the way the god Power (with an assist from the goddess Fate) shaped magic as he began shoving it into the universe.
The story reasons for this decision hinge on the fact that the suppression of technology is not the primary focus of Power's action. (Alternatively- it's not the story in my mind when I started.) The suppression of technology is the main reason Fate wasn't that unhappy that she had bee caught unprepared (a very rare event for Fate) by Power's massive re-shaping of the world. The reasons for her relative agreement with this aspect of Power's action come out in the story.
Power primarily sought to elevate the value of Power in the pantheon of human values, and he did so by magically tying it to sex. In the magical world he is creating, all sexual relations will involve magically enforced sexual slavery. As originally intended by Power, the sudden surge of magic into the world would create an apocalypse as systems failed and an opportunity for those most attuned to Power to gain ascendancy. A brutal, dystopian world would result.
Fate cannot stop this as Power built up the magic in a purpose-created alternative universe hidden from her sight and control. This is a first for the gods, catching her unaware. Instead, she creates her own temporary, purpose-specific alternative universe and sends her chosen agent, a rejuvenated old man whose life suggests his personal value structure will prioritize love and caring and family over power, back over sixty years into that alternative universe. His job is to shape magic into a more humane structure for humanity. She gives him only a little information on all of this (for reasons), to the point he doesn't even know he is going into the past and doesn't know what will happen when history returns to the moment she sends him back. The one thing she does give him is a way to add a choice option to the sexual slavery, a nuance that makes his overall task of shaping a more humane magical world possible.
The series will cover the key moments over the decades as the main character, his team, and the magical world that slowly grows around them shape the magic that they are pulling back (though they don't even know they are doing this at first). Sort of like the big bang, choices and actions and imagination (often mostly unconscious) in the early stages establish aspects of magical slavery and the use of magic in the world that then become the ways magic works in the world. Of course, like the big bang, this means that events early in the timeline carry extreme weight, so it turns out that the series may be heavily weighted toward the early months and years. At least, currently, the first four books cover only about two months, and number five is starting two months after the end of book four. I expect the time skips to grow as the series progresses, otherwise telling the whole story would be impossible for me.
Obviously, I'm more focused on choices, values, relationships, and culture than on physics and technology. There is a good (I hope) story reason for the anti-technology effects of magic, and it comes out over the course of the series, but I didn't start writing with the desire to delve into how humanity will adapt to the changes in technological solutions to the challenges of life; it's just an interesting side aspect.
So, going too far down the path of reconciling magic and pre-magic physical laws is a path I don't want to take. The physical universe will work just as it always has, except when magic overrides that. There will be at least one interesting situation I'm going to have to choose a solution for - what happens when a pressurized system fails? This isn't an human-intended result, and the failure is not controlled, i.e., initiated as an intended result, so does the anti-explosion aspect of magic apply? Could the system just magically de-pressurize in a non-destructive manner? Wouldn't that be great for system engineers? Design right up to the limits of tolerance and let magic provide the safety. That consequence alone is making me think the answer will be that destructive failure can happen, but I'm not completely sure yet.
Anyway, I appreciate all the help in this thread. I was expecting help on technology, but ended up getting even more on magic. Great stuff!
Obviously, I started writing the first book without all of this worked out. In fact, I hadn't even thought of it. The story I thought I was writing when I began is not the story that has evolved - maybe, like my characters, as a result of my personal values structure. But, now that I'm into it, I'm hooked and want to finish it, despite the interesting but sideline aspect of showing how technology and the economy will adapt to magic. (And I still haven't resolved just how apocalyptic things are going to get. I don't think the team can mitigate all of that, but...)