Observers detect objects and events with objects. These objects are essentially passive; they must be made to do things by force and work.
Participants are subjects among subjects, actively engaging in events and making them happen. Subjects participate and participants are subjects.
The perspectives of an observer and a participant are inverses of each other. They are different attitudes. An observer has an attitude of standing apart from the world. A participant has an attitude of being part of the world. The world is placed in different contexts because of the attitude of the contact.
~~~
Synchrony is synchronous, temporally together. Diachrony is asynchronous, not temporally together but spatially together, syntopic. Diachrony is global time in local space. Synchrony is global space in local time. They are opposite contexts.
Synchrony has 3D space with 1D time (3+1). Diachrony has 3D time with 1D space (1+3). Time-space is diachronic. Space-time is synchronic.
Three dimensions of length combined together are called space. Three dimensions of time combined together could be called tritime.
~~~
Dropping something into water generates ripples spread out from it. Each of these ripples may be measured by the time that it takes to travel a distance. Or they may be measured by the distance that they travel for a duration. In a smooth surface they are similar. But they could be different, as for example if a barrier or irregularities are present.
This illustrates the way that tritime can be contracted into time, and space can be contracted into length. Each length is a radius (radial length) of the expanding circular ripples. Similarly, Each time is a radial time (tradial?) of the expanding ripples.