Reality Is Not What It Seems.
In quantum gravity theory, space-time is not a four dimensional volume but an interaction between quantum fields. If I were to philosophize without any scientific input, then I would suggest that:
space is the relationship between material bodies;
each body's relationship to other bodies is that body's position;
bodies move, i.e., their relationships change;
therefore, there is a second order relationship between positions changed from and positions change to;
that is a relationship of before and after or of earlier than and later than and thus is a temporal, not a spatial, relationship;
thus, time is not just more space;
if two bodies are one foot apart and one moves away at one foot per second, then the separation of two feet is one second later than the separation of one foot and the second is not another foot.
However, because natural philosophy has become empirical science, we are informed that:
each body is a large number of particles;
each particle is a quantum of a field;
space-time is both a single set of relationships and a field;
there is an attempt to unify the fields.
But some conceptual/philosophical issues remain. If we conceptualize space-time as a four dimensional space and, if we also regard consciousness not as a cerebral process but as an immaterial entity moving along the fourth dimension of the human body, then we not only introduce a second temporal dimension but also reintroduce Platonic-Cartesian mind-body dualism. We might want to do both those things - although I don't.