Conversion of energy, I think, if in a way a normal understanding of physics isn't applicable to.

[ Exchanges, though. Magic and exchanges. It certainly feels like it's rooted in something concrete, and... alchemy? Well, given that Edward had been insistent on not calling it magic: ]

For them at least, I imagine the concept isn't too different from burning something for light and heat. Though I couldn't presume to say for sure. As for myself, I'm afraid the main purveyor of it wasn't particularly forthright with the details.

[ Its main target demographic is middle school girls, after all. ]