Einstein's Gravity Model: Explaining Its Creation

[Android17]

When we do the stretched rubbers he etc analogy of gravitational well, there are two differences 1) the ball moves into depression because of gravity of the earth.
2) stretched rubbersheet is physical and prevents ball from falling down while space would allow you to move anywhere as space doesn't apply a force on you.

 

[PeterDonis]

the stretched rubbers he etc analogy of gravitational well

Is not a very good analogy because it leaves out the crucial time dimension. For objects moving at slow speeds relative to the massive object that is the source of gravity, the ordinary effects of gravity are best understood as affecting time, not space.

 

[Ibix]

When we do the stretched rubbers

This is an analogy. The truth is $G^{\mu\nu}=8\pi T^{\mu\nu}$ and does not have those shortcomings, but it's difficult to make pretty graphics out of that.

 

[A.T.]

When we do the stretched rubbers he etc analogy of gravitational well,..

It's an analogy of a potential well, not of curved space-time in GR. Try this one instead:

 

[sweet springs]

There is a third interpretation. As for a circle draw on rubber around the depression due to massive body, its periphecy is smaller than 2 pi *(radius on rubber sheet) . Geometry changed to Non-Euclid.

 

[A.T.]

There is a third interpretation. As for a circle draw on rubber around the depression due to massive body, its periphecy is smaller than 2 pi *(radius on rubber sheet) . Geometry changed to Non-Euclid.

That is still just describing the spatial geometry, and doesn't explain gravity for which the time dimension is key.

 

[sweet springs]

Thanks. Schwartschild metric suggests that inverse of rubber stretch corresponds to time dilation, so... No, I will stop further analogy on rubber toy now.

 

[A.T.]

Schwartschild metric suggests that inverse of rubber stretch corresponds to time dilation...

If the rubber sheet represents the potential well (as it can for Newtonian gravity too). But the sheet has no time dimension to show how space-time geometry creates gravity.

 

[PeroK]

When we do the stretched rubbers he etc analogy of gravitational well, there are two differences 1) the ball moves into depression because of gravity of the earth.
2) stretched rubbersheet is physical and prevents ball from falling down while space would allow you to move anywhere as space doesn't apply a force on you.

That's quite a good analysis of why the rubber sheet is a poor analogy of curved spacetime!