Persistent Impression
Our various determinations of moments of time refer to physical realities that give meaning to the notion of time in physical sciences. These realities are always already implied when physics speaks of “time”, but they have hardly been registered yet.
Not only the activity (the interaction) is physically real, but also that what is called “knowledge” here. In the sense that activity causes a change and that this change is a persistent expression of the activity. The activity is stored in the change, so to speak.