Declan,
Please read my essay slowly and carefully. It is not light reading. Figure 1 presents the 5-D geometry. It does so in a way that can be construed as 3-D geometry for an inertial reference frame.
In both GR and SR, time and space are presented together as a 4-vector. The 4'th dimension is presented as i*c*t. Essentially, i*c*t is added to a space vector and the result becomes Minkowski space-time. GR is presented taught using tensors. Thus far, I have not learned to use tensors competently.
Time in QM is more simple. It is presented as a scalar rather than a pseudo-vector component of space time. Space in QM is also treated differently ... more like a scalar than a vector. The Schrodinger Equation presents time coupled with the complex i and it presents the space variables x, y, and z presented as scalars rather than as vectors containing the unit vectors i, j, and k.
Wikipedia is a wonderful resource. I give Wikipedia a modest amount of financial support. But it is not a substitute for other sources.
BTW, Einstein himself specifically rejected the idea of a scalar field. I mention this near the end of the essay. Space-time is not a vector plus a scalar as in a quaternion. Space-time is a vector plus a "time-vector" based upon the speed of light. That is not the time of QM.
Best Regards and Good Luck,
Gary Simpson