Only the physical mechanisms of gravity aren't missing in GR. Einstein said a concentration of energy in the guise of a massive body alters the surrounding space, such that the speed of light varies with position and so light curves,
All of that is true except for the part that says the physical mechanisms aren't missing. The rest of what you said, though it is all true, it isn't mechanistic. Look at each point:
"a concentration of energy in the guise of a massive body"
That is true, but it isn't mechanistic if you ask how the influence emanates from the mass, and the mechanics of containment.
"a massive body alters the surrounding space"
Very true, but not mechanistic if you ask how or what alters the surrounding space. What is the nature of the influence if it isn't wave energy?
"the speed of light varies with position and so light curves"
Again, true, but not mechanistic if you ask how light slows down, mechanistically.
I know I sound like a broken record, but none of the effects that you refer are new to me, and I don't see the mechanics in what you mention. The nature of the energy involved, and the "how" of the effects are not presented mechanistically. That is my point.
... and we all know about the wave nature of matter.
That is true, but the "how" of energy containment in particles and the nature of the waves might need some explaining, and I do know how to Google, so don't say look it up, lol. I have.
I'm sorry quantum_wave, but you're advancing an unsupported hypothesis ...
That is true, but I'm not a science professional trying to "do science", I'm a laymen, very science enthusiastic, well read, and thoughtful. I compare the various perspectives in the material I research, think about them, and decide how they could work together, without feeling I have to falsify the material that I don't see fitting in. All I am intending is that I post it for the record, listen to meaningful responses with content, like from you, review the content in the responses, decide if I have already thought the things through that you mention, and adjust my thinking as necessary, as determined by me :shrug:.
... here without having read up on what Einstein said ...
I've read plenty, and continue to do so. I appreciate the links and references you give on the subject.
... and without understanding gravity.
Oh yeah,
If you did, you wouldn't be saying that gravitational waves constitute the energy density of the medium of space. Because you'd know that gravitational waves are variations in the energy density of the medium of space.
After you think about it, and sort it out considering the alternatives, what do you conclude constitutes the rest of the energy in the medium of space?