QM indicates that zero is not a possible value of electromagnetic energy. The Casimir Effect supports this.
Ok you have bought in QM which technically isn't need to do GR but lets go with where you want to go. QM and Electromagnetism are formally joined in the theory of Quantum Electrodynamics and it is one of the most tested and precise theories in our science knowledge. It is a relativistic quantum field theory and that means it incorporates relativity (specifically Special Relativity), QM and electromagnetics and so it embodies 3 other sets of understanding within it. Yes along with the casmir effect you therefore arrive at a vacuum expectation value of energy in each point in spacetime.
There are however some problem worth noting, if spacetime is infinite in it's points in space your universe vacuum energy is an infinite quantity. When you use the value you get as a quantum gravity theory the value you get for the cosmological constant is massive compared to it's measured value.
QM tells us that matter is composed of wavelike energy. We might conclude from this that empty space and matter are the same thing, differing only in their energy states. We might continue this line of thought to say that matter/energy and space/time are the same thing.
No there are extensions of QM that do that but not all, is it the favoured possibly but again science isn't a consensus vote you can take a personal view on that issue.
You may care to review the tenets of quantum mechanics which says none of that except the wavelike behaviour bit.
Changes of energy in matter may lead to detectable changes; e.g. expansion/contraction. The presence of matter/energy in space/time may involve a transition between matter/energy and space/time which results in transitional phenomena, such as expansion/contraction.
Ok now you are getting in to trying to describe interactions and we need to get into details and perhaps I will give you some.
What Einstein noticed is that forces can arrive centred on a point in space based solely on motion you know these as centripetal forces in classic physics. There are several key points to this so lets deal with them
1.) The "fictional force" is focused to a single point in spacetime
2.) The force seems to be transparent to the focal point in spacetime. That focal point in spacetime does not see the force like a media would and you can't seem to create a force so large it crushed or shatter the point. This goes to the point that GR locally takes it's stress tensor to zero and you can't directly measure the force directly on a single point in spacetime well at least one that non zero.
One might expect that the expansion/contraction would effect both matter/energy and space/time, and that it would be more perceptible in the latter.
One might expect it based on the matter/energy but the above detail casts a lot of doubt on space/time because at the interface we see and measure nothing.
However what Einstein also realized is he had seen behaviour before in hydraulics. He also knew a basic fact that hydraulic systems will work most efficiently if the hydraulic fluid used has zero compressibility and zero viscosity. Think about the behaviour above. What he ended up at was very different but it was a useful starting point. I am not sure how much you want to go into that so leave that up to you.
The “classic” example of what the Earth would feel (and when) if the sun just vanished is obviously just a thought experiment which relies on a physical impossibility. Matter does not spontaneously appear and disappear.
As far as we know all that is correct
Excluding individual particles, matter becomes present in masses of increasing size by a process of accretion; thus, the interaction between matter/energy and space/time is an ongoing complex relationship in which the expansion/contraction/deformation of space/time – giving rise to what we experience as gravity – is an integral part.
Yes but there is a problem does the gravity come first or the particles, you have a chicken and egg problem.
There is no external influence, the process is integral to the formation and evolution of the Universe
Simply no way to answer that we have no evidence there is an external force but let me give you a stupid answer which at present you cant refute. Gravity is because a big green giant has the whole universe in his hand and is swinging us around and it is really the centripedal force of that motion.
