[alancalverd]

You can feel a gravitational field. Lead is much more susceptible to gravitation, and hydrogen much less so,  than human tissue. You can also sense the absence of a gravitational field by jumping out of a plane.

[geordief]

You can feel a gravitational field. Lead is much more susceptible to gravitation, and hydrogen much less so,  than human tissue. You can also sense the absence of a gravitational field by jumping out of a plane

So it is perfectly acceptable to think of the field as a physical object that is subject to deformation? Is it a 3d +1 physical object?

[alancalverd]

Not really. A gravitational field is a mathematical abstraction that predicts how bodies will move in the presence of one another, or how photons will behave in the vicinity of a massive body.

[Colin2B]

So it is perfectly acceptable to think of the field as a physical object that is subject to deformation? Is it a 3d +1 physical object?

As Alan says the field is a mathematical abstraction. What you do is place a test mass (1kg) and measure the force vector acting on that mass, that vector is the field strength (unit gravitational force) at that point (you can do the same with a magnetic field, using a test magnet). In this case you create a map of of gravitational force values for a volume of space.
That’s all a field is. The value of it is that with gravity we can use a simple formula to calculate the field strength at any point between 2 masses, and hence the force between 2 masses.
When we say spacetime is curved we are saying we can use the maths of curved surfaces to describe the motion of a mass in a gravitational field.

[geordief]

As Alan says the field is a mathematical abstraction. What you do is place a test mass (1kg) and measure the force vector acting on that mass, that vector is the field strength (unit gravitational force) at that point (you can do the same with a magnetic field, using a test magnet). In this case you create a map of of gravitational force values for a volume of space.
That’s all a field is. The value of it is that with gravity we can use a simple formula to calculate the field strength at any point between 2 masses, and hence the force between 2 masses.

Is that the famous Einstein Field Equation I have heard of?
 (if it is I am glad to learn it is simple    )

[Colin2B]

Is that the famous Einstein Field Equation I have heard of?
 (if it is I am glad to learn it is simple    )

Whoops, you caught me there being nonspecific.
I should have said calculate approximate field strength. These are Newton’s equations, good enough to land men on the moon but not accurate enough to predict the precession of planets to very high accuracy. Like any more accurate calculation, Einstein’s field equations are somewhat more complex; don’t despair however, the basics of how they work is very easy to understand, it’s solving them that’s hard.

[David Cooper]

You (the OP) are right to say that there is no mechanism for curving Spacetime. Worse than that, there is no way for the mass in the singularity of a black hole to govern the shape and size of its event horizon and gravity well without faster-than-light control signals - if the black hole accelerates, it would have to be dragged along by it's gravity well rather than moving its gravity well. However, the establishment now claims that Lorentz Ether Theory is just a different philosophical slant on the same theory, and LET does have a mechanism for all of this: there is a medium involved which slows the speed of light more at greater depth in gravity wells, and that medium is a dark extension of the visible matter that we see at the bottom of the well, and that dark extension is simply the result of each particle being spread out through the whole universe. So, it should be possible to translate that mechanism to the mathematical abstraction of Spacetime in some way, although it will need faster-than-light aspects to get that control from the singularity to things at higher altitude.

[yor_on]

Outcast, are you trolling us?