Magic and physics

Dresden universe magic is modeled more closely upon physics.  Magic still has to pay attention to fundamental universal laws–such as “matter and energy can neither be created nor destroyed, only rearranged.”  The energy for all those magical effects has to come from somewhere.  There ain’t no free lunch.
For instance, you could fly someone on a broom in the Dresden universe, but you’d have to be providing the same kind of kinetic energy you’d see from one of those James Bond rocket packs that they fly into the Superbowl from time to time–IE, a buttload.  (Those packs are good for about twenty or twenty five seconds of flight, if I remember correctly, and that’s it.)  In the Potter universe, dozens of children who know next to nothing about magic can gad about on brooms in the afternoon for fun and recreation, and no one thinks anything of it.  There’s a foundational difference in the approach to how magic interacts with reality.

(The Corvidian (http://www.jimbutcheronline.com/bb/index.php?action=profile;u=1493), September 27, 2007)