I was about to give a very scathing answer to RL on the flame board but changed my mind due to your posts.

It is true that my mathematical ability is not up to the proper level in this area of communication.

And since you seem like a person of great integrity and compassion, I will explain my ideas to you and perhaps you can show me how these ideas can be expressed in mathematical terms.

You said:

"I really need to extend this to a clear 'derivation' (verbally I mean) of E = mc sq .. also, yesterday someone asked me about c being constant for everyone in flat space .. how can this be so? I answered by the usual means of Maxwell's equations and the M-M interferometry expt, but it didn't convince him, even though he's very bright and very interested. I believe there must be a better and simpler way - which would have to come out of deeper understanding on my part."

I will answer your questions to the best of my ability, but first you must understand the language that I will use.
The mathematical language will remain familiar to you and everyone that understands math. The concept being that all calculations can be reduced to the three fundamental units of Length, Time, and Mass. And despite RL's assertions to the contrary, I will heed all corrections in that area.

The verbal language will be mostly English.
Since a single English word often has several different meanings associated with it, I will explain what meaning I will be using.

The subject under discussion will be Einstein's formula of 'e=mc squared' and for that reason all the important words will have a fundamental meaning. For instance the word energy will be in reference to the said formula and envisioned in sub-microscopic context rather than everyday macroscopic context.
How the sub-microscopic and the macroscopic events are related will become evident from further analysis.

First of all, since the outcome of Einstein's formula is "energy," I will explain my understanding of that word.

In modern reference books the word energy is described by the words; "ability of matter to perform work as the result of motion or position." I disagree with the "or position part of the statement.
In my opinion energy in its fundamental state IS motion of mass. The "position" of a fundamental particle of mass can not have energy if it is stationary in relation to its surroundings. If the mass is stationary and within the influence of a force then it has the potential for energy.
The word force then can be associated with potential for energy.

For a lack of a better word, I will use the word force when explaining the influences or results that are caused by various fields.

For instance in the macroscopic scale, I could describe an object that is suspended above the ground as having potential energy. The potential energy being due to the force of the gravitational field.
Also I could explain that; when the restraint was released the force of the gravitational field accelerated the object. And also I could say that the object hit the floor with great force.

This then implies that there is a force involved in both kinetic and potential phenomenon.

For the purpose of explaining mass in its fundamental state, I will differentiate the potential from the kinetic form of force by stating, when the need arises, which form it is, such as kinetic force or potential force.

Is my explanation understandable so far?

Johannes