(First I will respond to your statements.)
So I see two alternatives:
1. Search the literature for experiments, perhaps ongoing, that determine if gravity is instantaneous or not. That can be your task, as well as mine
2. Do some gadanken(sp?) (thought) experiments. For example:
(i) Suppose that gravity and all other forces traveled only at the speed of light and see if any contradictions can be found:
(a) black holes would not be detectable
(Unless of course there is a pressure force on all mass and gravity is caused by a vacuum of this pressure.)
(b) gravity would be red shifted
( Yes red shifted or non existent which would cause a lower pressure from a massive object. )
(c) particles could not be entangled
The ball is yours.
(Regarding the experiments done by Alan Aspect
Each photon must be in a specific state to be absorbed. The photon oscillates between two fields. I will refer to them as primary and alternate fields. The photons can only be absorbed while it is in the primary field which is compatible with the absorption media. The mirrored photons rotate in opposite directions while in the primary field. Each photon also rotates the reverse direction while in the alternate field causing both to complete a cycle which is constantly repeated. From the time of conception it has been determined which way each photon will be spinning when it is absorbed by a specific absorption media and therefore no information is required to be transferred at the time of absorption.
If an alternate absorption media was used then the each photon would have been found to be spinning in the opposite direction which would still be opposite of each other.
If an alternate absorption media was use to absorb one photon and a primary absorption media was use to absorb the mirrored photon then the photons would be found to be spinning in the same direction.
So in short - the information required to determine which way the spin will be absorbed is stored in the structure of the photon and travels with the photon at the speed of light.
This explanation appealed to me because it required no undiscovered parameters to be necessary.)
PS: The experiments done by Alan Aspect in France first proved, based on the math of Bell, that quantum mechanics is correct and the prediction of Relativity that all forces travel at the speed of light or less is incorrect. This experiment has been repeated many times and the results are always the same.
Alan created an photon pair of opposite spin at a point and allowed them to propagate off in opposite dirtections. He then measured the spin on one, thereby collapsing the waves into a photon of definite spin. Depending on the arrangement of the apparatus, the spin measured was not always the same in agreement with quantum mechanics. But the spin of the other photon was always opposite, proving that one particle had instantanewous knowledge of the other.
(Why did you not assume that the photon carried the “knowledge” with it instead of having it delivered instantly at the time of absorption.?)
This experiment has been repeated with electron-positron pairs, and even molecule pairs with some property that is opposite. The result is always the same. The speed of light is broken and within the limits of the measurements, the action appears to be instantaneous.
( I don’t agree with this interpretation of the evidence in light of the explanation above.)
Now my explanation for how this happens is that the two particles are connected in higher dimensions. In string theory fermions are made in ten dimensions- but 6 of them compactify down to 4-d spacetime. These compactifies dimensions then form a thread that connects say the e-p pair to each other so that one always knows the state of the other.
Now this same argument can be extended to spacetime itself. The particles of space have zero mass. Therefore their wave functions are infinite just like a photon. Did you know that photons do not experience the passage of time. They retain the time of their creation as a marker. So if you ask how big is the photon at any particular time, it eithre does not exist or it is infinite, like a delta function.
Any zero mass particle has the same property from quantum mechanics- their wave functions are infinite. Therefore all the wave functions of space particles overlap and each partilce knows what happens to every other pertice instantly, just like in the Alan Aspect experiment. It's called 'entanglement'.
That is how space reacts instantly. And since gravity is just spacetime curvature according to General Relativity, gravity propagates instantly. We call it propagation by virtaul particles. But nthat is misleading. In my opinion, it all happens because of entanglement, which has been proven experimentally.
(We could also suppose gravity travels faster then the speed of light and see if any contradictions can be found but I will not try to poke holes in your theory, as my primary intent is to find flaws in my own thinking which need to be corrected. In this you have been much help and I thank you.
Here is a possible experiment which could determine if the speed of gravity is infinite.
An object is separated in half due to an explosion and attains very high receding velocities.
If gravity is instantaneous then the deceleration should depend on the actual distance between the objects. If gravity travels at the speed of light then the deceleration will depend on the visual distance between the objects. This derivation between these two distances in the gravity equation may be evident by measurement. We could punch some numbers and try to determine if the derivation is enough to be observed.