[Colin2B]

Is it a good starting off point to take it as axiomatic that the "natural" relationship between relative  space measurements and time measurements   is variable ?

Not an axiom because not easily observed or self evident.

Would that take us any further towards detecting the actual mechanism(s?) that caused changes in that variability?

Considering that physicists accept it is observed and have based a lot of theories and experiments on the basis of it being true, I can’t see how it moves us any further towards an ‘actual mechanism’.
Currently the assumption is that any form of energy will result in a curvature of spacetime (note: not a bending of spacetime). Mass just happens to be one of the most concentrated forms of energy that we have, hence its affect is greater than most other forms.
When people talk about an ‘actual mechanism’ they are missing the point. GR provides the mechanism, the very fact that the spacetime dimensions are not ‘flat’ as we might expect is the mechanism and it is well described in the field equations. I think @Janus has described it elsewhere.

[geordief]

When people talk about an ‘actual mechanism’ they are missing the point. GR provides the mechanism, the very fact that the spacetime dimensions are not ‘flat’ as we might expect is the mechanism and it is well described in the field equations. I think @Janus has described it elsewhere.

So not so much a mechanism as a basic condition ("flat space" is just a special case  that applies when  there are no local sources of gravity and the "natural" condition  is just a function of the local distribution of energy)

But if we do not have a theory of Quantum Gravity does it not follow that there are mechanisms involved in spacetime curvature  yet to be explained?

E.g. we don't know yet ,do we whether spacetime should be  a continuous or a discrete model ,do we?

[alancalverd]

The model can be continuous or discrete as you wish. It's easier to solve continuous equations, and until we discover a graviton with quantum properties, the continuum model will rule.

[Janus]

The reason It "wasn't enough" was that there were already "chinks' showing up in Newton's Theories by the time Einstein began to formulate his theory.

Do you recognize any "chinks" in Einstein's theories?

To date, none have been found.  Every time we perform a new test, the theory passes.  How long this will continue, no one knows.  we suspect that there is a better theory out there. For one thing GR doesn't "play well" with QM, and there are quite a few people out there trying to formulate a ways of joining them together.   It might even be helpful if some experimental discrepancy could be found, as it might give us a hint of where to look.
and as @alancalverd  has already pointed out, Newton didn't provide a mechanism either. And his theories were accepted and well-established for centuries.  The point being that "does not provide a mechanism" is not a valid criticism of a theory. 

[Outcast (OP)]

The point being that "does not provide a mechanism" is not a valid criticism of a theory. 

I realize it's not a science reference, but it's the first line in describing the history of gravitational theory. The mechanisms have always been an integral part of the theories.

"History of gravitational theory
From Wikipedia, the free encyclopedia

In physics, theories of gravitation postulate mechanisms of interaction governing the movements of bodies with mass."

[Kryptid]

To date, none have been found.

Many would argue that its inability to mesh with quantum mechanics is a "chink". Although relativity seems to be extremely accurate on large scales, it likely diverges from reality to some extent on certain extreme scales (like large amounts of mass crammed into tiny volumes, such as when stars collapse into black holes.)

[Colin2B]

The mechanisms have always been an integral part of the theories.

Can you be specific about which mechanisms you are referring to in each case?

[alancalverd]

The history of non-science is full of mechanisms, mostly involving incestuous gods in the form of animals. Scientists occasionally discover bits of mechanism but the equations we consider to be laws of physics are mathematical abstractions of what happens, not lists of the components of nature. 

[Outcast (OP)]

The history of non-science is full of mechanisms, mostly involving incestuous gods in the form of animals. Scientists occasionally discover bits of mechanism but the equations we consider to be laws of physics are mathematical abstractions of what happens, not lists of the components of nature. 

Here's one list of the main branches of physics.
1 Classical mechanics.
2 Thermodynamics and statistical mechanics.
3 Electromagnetism and electronics.
4 Relativistic mechanics.
5 Quantum mechanics.
6 Optics, and atomic, molecular, and optical physics.
7 Condensed matter physics.
8 High energy/particle physics and nuclear physics.
Four of the branches contain "mechanics" in the name. No gods, no animals, no incest.

[Outcast (OP)]

Can you be specific about which mechanisms you are referring to in each case?

The original question concerned a mechanism whereby matter warps space.

[alancalverd]

Mechanics: mathematical modelling of functional systems. Prediction of system functions. Physics.

Mechanisms: description of how components fit together. Realisation of functional systems. Engineering.

Hence  celestial mechanics predicts the sunrise and the trajectory of an asteroid, but whilst relativistic mechanics gives us the answer, we still haven't found a gravity exchange particle, let alone a testable mechanism for the creation of matter in the first place. That's where our forebears hypothesised the incestuous and bestial relationships of fairies, but it doesn't seem to have much predictive value or help us to fly around the world.

[Petrochemicals]

In fact Einstein stands out as possibly the only experimentally proven prophet. Others (including Newton) have explained existing observations or had the temerity to question Aristotle's logic, but relativity theory has accurately predicted a whole bunch of stuff, from gravitational lensing to the hydrogen bomb, that had never been seen or even sought previously.

Love the wombat poo. Yes, folks, there's nothing too weird or trivial for this forum! Interestingly, though, whilst their turds are isosymmetric with cubes (evolution?) , they do not (cannot) have sharp edges (biophysics).

Isnt it a bit soon to say that ? How long before problems with newtons theory where uncovered ? Relativity is a part just like newtons stuff, yet it is held up as absolute. After all, Einstein really only created the Aether after denying it.

[Bored chemist]

After all, Einstein really only created the Aether after denying it.

That's just silly.

[PmbPhy]

Einstein could discover no mechanism for gravity's influence across space...

It was never the purpose of GR to do so. No scientist to date has ever discovered a mechanism for gravity.

So he theorized that matter warps space...

Warps spacetime as well as space, not just space.
[/quote]
..and provided no mechanism whereby matter does this.
I don't see this as a good answer.
[/quote]
That's okay. The rest of the physics community thinks so.   Seriously though. Einstein knew that the presence of mass generates a gravitational field. That was demonstrated by Newton. What Einstein showed that not just mass by any kind of energy does also as does stress and momentum.

In any case its not true that Einstein theorized that matter warps space. It fell out the theory. Also matter is not always generate warped spacetime in all cases. E.g. the spacetime of a uniform gravitational field is not warped, its flat.

[PmbPhy]

I thought Einstein predicted gravitational waves...just thought we would never detect them.

That's true.

[PmbPhy]

An argument can always be made that that which can't be detected doesn't exist.

That's a bad argument since it can't be known what can and can't be detected unless by their nature they can't be detected. In that case we call them virtual like in virtual particle. But we did detected gravity waves.

[PmbPhy]

Einstein's theories criticized a multitude of dead geniuses that came before him...I'm sure a few were honest...

Not at all. Einstein's theories  either explained that which was as of yet unexplained or provided a more precise description of what had already been explained.

[PmbPhy]

The reason It "wasn't enough" was that there were already "chinks' showing up in Newton's Theories by the time Einstein began to formulate his theory.

Do you recognize any "chinks" in Einstein's theories?

I myself don't.

[alancalverd]

An argument can be made for that which can't be detected, even in principle, doesn't exist.

Utterly brilliant! Viral disease is caused by electron microscopes! Give the man a Nobel Prize.

[geordief]

If we  consider gravitation fields to actually  be physical objects  in the same way as magnetic fields are  ,can we say that mass/energy distorts  these fields?

If that was so it would put to bed the head scratching that goes on when people try to visualize space or spacetime being somehow physically curved when ,intuitively that just feels absurd.

I know that gravitational fields are very different from magnetic fields and it would be difficult /impossible to feel them in the same way because  everything is subject to gravitational fields .( you can feel magnetic fields because the human body is less subject to that field than ,say a metallic object it might hold in the hand. )