An Objective Story Domain of Physics means the story’s troubles are caused by an activity gone wrong. This might be an activity engaged in by people or existing in nature. Either way, the “perpetuation” of this activity is what generates all the difficulties faced by the Objective Characters. There is often the tendency to think of an activity in the large scale, making it macroscopic; larger than life. But dry rot works as well as a marauding horde in creating problems big enough to drive a story. The only constraint is that the activity must be an external one that is causing the difficulties.
Situation vs. Activities
It is easy to think of kinds of activities that border on being situations. For example, we might want to tell a story about a disease. If the story’s problem stems from having the disease, it is a situation. If the story’s problem is actually caused by fighting the disease, it is an activity. Because all four Classes will show up in a complete story, it is likely that both having and fighting the disease will show up as things unfold. The thematic question here is: which one is seen objectively, or phrased another way, which one is best seen as the cause of the problems for all the characters throughout the entire story – having it or fighting it?
From the Dramatica Theory Book