Magic is the most wonderful form of “unobtanium.” It allows anything to happen, regardless of energy requirements, differences in mass and density, and subverts all requirements for fuel. Strong and weak forces? Out the window! And that’s part of what makes it so wonderful to read about.
Good stories featuring magic have good systems in place to govern its usage, and I love that. Fullmetal Alchemist is famous for the Law of Equivalent Exchange, and Brandon Sanderson’s Mistborn Saga is a wonderful example of how metals, when ingested, can be used to power extraordinary events.
Inspired by Randall Munroe’s “What If?” comics, I decided to devise a magic system that married physics and fantasy. Firstly, I sorted the schools of magic into the fundamental forces, plus time and telepathy. Then came the grimoire!
Ignoring energy requirements, I focused on the consequences of everything else being as realistic as possible. Turn metal into foam rubber? That’s an atomic spell that’s going to result in a serious increase in volume. Teleport something? A kinetic spell that will leave behind a thunderclap and superheat the target upon arrival. There’s no way a mortal could survive such a journey, but an alien homing beacon just might.
In practice, this means my characters can’t just wave their hand and teleport safely! They have to invent enchanted workarounds, which makes the magic feel both wondrous and dangerous.