Excerpted from The Zen of Story Structure
The Physics Class is one of action. Whereas the Universe Class describes a fixed situation, Physics is a Class of dynamics. Situations evolve, develop, and change. Activities are engaged in and endeavors undertaken.
DEFINITION: Physics: an activity or endeavor.
SYNONYMS: an activity, an enterprise, an initiative, an endeavor, an operation.
DYNAMIC PAIR: Psychology, a manner of thinking or demeanor.