Physics is a fairly complex system. Single physical statements cannot be understood but with a certain acquaintance, with prior knowledge. So we may say that physics constitutes its own knowledge space.

Sometimes, however, it is possible (and necessary) to distinguish different subareas, relatively self-contained disciplines or approaches defining their own spaces of knowledge. These may penetrate and superpose one another; different theories and models may mesh and complement each other.

Still, in the end, physics makes sense only because there also overlap quite another kind of spaces that are no integral parts of science as such, but of the “real” world, so to speak. Only this enables physics to take effect upon material things, as well as to be affected by them and thus to reflect physical reality.