Physics research is a more dynamical process than it may appear from the textbook descriptions of various physical theories or from a posteriori foundational analyses in the frame of the theory of science. Insights in the research process itself may give hints about the building up of meaning related to the various theoretical constructions and hence may help identify the constructive component in the semantics of physical theories. The discussion presented here is not an analysis in the field of the theory of science, nor a contribution to the history of physics and surely not a theoretical physics study — but is an essay, a trial to circumscribe a certain moment in the evolution of the ideas associated with the concepts of space and time in modern physics. For this, besides briefly describing the physical problems involved, we shall also try to follow the views of physicists concerned with these questions.