Gary Simpson,
Studying your paper makes me realize just how much dedication you have. You are so determined to learn and apply Quaternions. Even your many thoughtful comments on other essays show what a [u]Scholar and a Gentleman[/u] you truly are. I catch myself thinking: "Heh! When I grow up -- I'd like to be like this Gary Simpson guy!"
You have succeeded in taking a rather intimidating subject and putting it within the grasp of many others, including myself - for which I'm sincerely grateful.
Perhaps I'm a slower learner than others, for it has taken me more time to evaluate your essay. My personal bent is the find pieces to the Great Cosmic Puzzle and to find tools with which to assemble those pieces into a model. In the timeframe of reading essays in this contest I'm finding that Quaternions is just one of a dozen mathematical toolsets used in physics and quantum mechanics -- most of which I have yet to learn. So I read on...
You say, "Geometric Algebra describes three dimensional space and that Physics occurs within three dimensional space" which I think is the perspective that most of the scientific community shares. In my paper I emphasize that physical reality exists in a 4D Space~Time context, so my model needs 4D Geometry where the 4th dimension is the radius of an ever-expanding Now-manifold inside the context of 4D Spherical standing-waves. While studying your paper I'm asking myself "How to I apply these Quaternions to my 4D context?" Do I have to model each Time-Space point as a Planck-time, Planck-lengths as three Quaternions: (t, X, Y, Z) where X, Y & Z are each Quaternions? Or am I better off using a coordinate system based on plain complex numbers: (t, X, Y, Z) where X,Y,Z are complex? In my mind the real portions of complex/quaternion numbers are positions in space or time and the imaginary parts are the stress-energy tensors of how stretched/compressed the Space~Time Medium is at a particular instant. I think the answer is somewhere around Equation 7 to 10 but at this time I'm still undecided.
In your equations is there something that says time-slows as speed approaches c? Like, your quaternion T: do the complex components represent a rotation of the direction of motion "rotating" towards negative-time - meaning local time slows as the object approaches c?
(Ditto, on the recommendation on David Hestenes' Geometric Algebra.)