Roy, I will attempt to answer your questions. Miss out the "how I got there" after answer number 1. to get to answer number 2.
you said, "Georgina, regarding your "potential energy field" description of gravity, how would you recover *gravitational* mass? Whatever the origins of gravity, it does manifest as acceleration (vector) and your idea only seems to explain *inertial* mass."
The mass energy will cause alteration of the gradient of the potential energy field and is therefore also equivalent to the gravitational mass. A change in position along the 4th dimension can be observed as a change in position in 3D vector space for example when an object falls. The attracted object is itself progressing along the 4th dimension, and can be visualised with its own "gravity well". However it can loose even more potential energy by moving into the "gravity well" of an attracting body. It does this by moving not only along the 4th dimension but vertically (relative to an observer on the attracting body) through observable 3D vector space towards the attracting body.(All matter looses potential energy at every opportunity.) One could say that the potential energy difference between the two objects is reduced as a result of the attraction or change in spatial position in observable 3D vector space.
I will try to explain how I got there .
Subatomic particles that constitute matter are elusive and dynamic entities that can not be given precise location in both time and space. They have continuous change in position and energy. A description of matter and sub atomic particles can then either be given in terms of changes in position in space of matter or particle, or in terms of the corresponding energy changes.
According to this model all matter is continuously changing position along the 4th spatio-energetic dimension towards afore space. This change in position is loss of potential energy. It is this change in position will cause the disturbance recognised as gravitational field. It can be envisioned as the wake of the mass as it passes through quaternion space. The more displacement of the the unknown medium of space that is caused by the change in position of the object along the 4th dimension the greater the gravitational mass. An object with large gravitational mass not only has a "large presence" in observable 3D space either as large volume or large atomic mass but penetrates more deeply into afore space than a smaller mass. Causing a deeper "gravity well" experienced within 3D vector space as a stronger gravitational field.
According to this model it is also this potential energy that gives the mass energy of an object observed to be stationary in 3D vector space. An object observed to be in motion in 3D vector space would have mass energy comprised of promotional energy (loss of potential energy giving change of spatial position towards centre of hypersphere), and kinetic energy ( changes of position in 3D vector space). When the matter is destroyed it is no longer able to change position afore and the promotional energy is released. This accounts for the very high value of mass energy, in my opinion.
Roy you said "I don't think this "energy field" could be scalar as it induces a centre of mass directed effect in it's coupling to the matter?"
If I understand your question correctly, I think the reason you ask this is because you are not thinking about how the scalar dimension intersects with 3 vector dimensions of space in the same way as myself.
In my opinion a model can be constructed in which the 4th dimension runs from the exterior of the Mega universal hypersphere through aft space (space outside of the 3D vector space occupied by the object, beyond its exterior along the 4th dimension) to the exterior of the object at every point on its surface. From there it runs through the object to the centre of gravity, where it then passes on to afore space (space outside of observable 3D vector space occupied by the object, that is ahead of the object along the 4th dimension .) and on to the centre of the hypersphere. The 4th dimension intersects the 3 vector dimensions of space where the material object exists in 3D vector space.
Beyond the exterior of the object along the 4th dimension is aft space that has been passed through and beyond the interior of the object is afore space that has not been passed through. When the object continuously changes position along the 4th dimension it is not moving through 3D vector space and thus may appear to be stationary in 3D vector space. The visualisation of a moving gravity well rather than a static one can make this more comprehensible". (When this "motion" not within 3D space is visualised, which can take a little getting used to, gravity be understood.)