Your impressions of the current state of our knowledge has lead you to some conclusions that overstep the bounds of theory. To discuss the topics of matter/energy, time/space, and gravity/inertial from the perspective that there are relationships between them is scientific. To say that these relationships are understood by science to the degree that we can move them from theory to reality is the overstep.
In regard to matter/energy, there is clearly an equivalence. And co-joined is a good way to express that equivalence. We agree that far. But we don't know what causes mass. We have theories but there is insufficient evidence to call them reality.There are several co-joined properties in the universe.
Matter / Energy
Time / Space
Gravity / Inertia
These are realities not theories.
I would agree with that at the particle level and would say that when a particle exists, it is composed of energy and the nature of the energy contained in particles gives the particle duality, i.e. wave/particle characteristics at the particle level. If you combine particles into objects, then the object is internally expressing the frequency of the particles but the object itself, the classical object, can be at rest. The motion of an object is relative to other objects.When a object or particle is given energy it must move.
This is true for the wave/particle nature of particles and if you mean that there must be movement at the particle level then it is true. But an object can be at rest relative to other objects and time will still pass.In order for time to elapse a distance must be traveled.
This is an overstep from theory to what you have concluded to be reality. We not only don't know what causes mass, we don't know what causes gravity. We quite clearly know the effect of gravity and General Relativity has it described to a great degree of accuracy. But it is still theory and not fact. The coupling of space and time assumes a start point from zero volume at t = 0, or at least that is the common conception of what is implied by GR. Your reference to the universe's state of motion refers to the expansion, assumes zero volume at t = 0, and not only gives no explanation for pre-conditions, it is implied that there we no pre-conditions, i.e. it implies that the energy came from nowhere. Cleary that is just theory and there are alternative theories that accomodate pre-conditions.For mass to exert gravitational force it must resist the change in the universe's state of motion, accerlation.
The entire paragraph gets mixed reviews from the standpoint of theory vs. reality. There is no argument with the energy and motion part. But when you give GR the status of fact and not theory, and then ignore the incompatibility between General Relativity and the quantum realm buy advancing string theory as the answer, you are overstepping the standards of the scientific method.Existence is litteraly defined as energy (in any form) in motion. If a particle ceases to move it will not exist. Everything in the universe is in motion. The theory of General Relativity couldn't have gotten it more right. Even down to the quantum level the theory of strings works because it suggest a relative vibrational momentum to directional momentum. This is how I suppose why String Theory supposes 7 additional dimensions because of the ineraction of relative motions on beyond the quantum level.