# Thread: Practical experiment, which proves, that Theory Of General Relativity might be incorrect

1. I'm planning a simple experiment, which will test, if General Relativity explains the force of gravity correctly. I want to use the rubber surface model of gravity, to see, if changing the size of an object really has no effect on the force of gravity, which it produces...

According to our current knowledge, force of gravity depends only on the mass of an object. Science tells, that if Sun would shrink enough, to become a black hole, it wouldn't have no effect on the orbital motion of planets in Solar System.

Sadly I'm a scientific sceptic and I don't believe in anything, what seems to be incorrect. Since science is about facts and not beliefs, this is why I want to observe and measure, if changing the density of a central body in a gravitational field won't affect the acceleration and forces, which are induced on other bodies in this field. To make it happen, I will use the model of gravity, which is proposed by the theory of General Relativity:

And this is, what we can expect to see, if we will change the size of an object, without changing it's mass:

According to science - force of gravity, induced on the blue marble won't change even a bit...
According to me - depending on the distance between the source of gravity, blue marble can experience 2 (possibly 3) kinds of effects:
- if the distance is small, force of attraction towards the center of field, will grow significantly
- if the distance is big, force of attraction will become weaker and eventually completely fade
- it's possible, that at a certain distance from the center, force of attraction won't change

Those images explain, why I expect to observe such effects  What I need to do, to prove my idea, is to measure the acceleration of a body, which is attracted towards the center - but better will be to measure instead the force of attraction itself, as acceleration can be affected by friction between the surface and the body - for different densities of central bodies.
Another thing, which I can check, is to see, what will happen, if I change the density of attracted body - combined, it gives me 4 possible measurements to compare.

You need to know, that I've made already some attempts, only to check, if it's possible, that Einstein could be possibly wrong - but before I will show you some initial results, I would love to hear, what do you think about my experiment and what do you expect to happen...  2. This is a science forum, not the place where you post your personal fringe theories.  3. There is no such thing as a Rubber sheet model for gravity. There is the Rubber sheet analogy. The difference is that the analogy is just a way to help laymen visualize the concept of space-time curvature, while a model is used to make actually predictions of the behavior of objects in a gravity field. No physicist has ever used the Rubber sheet analogy to make real predictions of the behavior of gravity.

This is because, like pretty much any analogy, it is not a totally accurate representation. For example, space-time is represented by the 2D sheet, but the masses are 3D objects. A more accurate representation would have the "masses" be part of the sheet.
Here is cross-section view of how this works. There is no "circle" that represents the mass, Just points on the curve that show where the surface of the mass would be. The part of the curve in between the vertical lines is gravity below the surface of the mass. The outer two lines in this diagram show the surface of the Earth. Outside of the lines is gravity above the surface, inside is of them is below the surface. The red curve is for a object with the same mass, but denser than the Earth. The red vertical lines mark of its surface.
Everywhere outside of the lines which mark the distance of Earth's surface, the two curves perfectly overlap. It is only when you get closer to the denser object than Earth surface distance that the curves deviate.

The reason the red curve dips deeper is that, for the Earth, as you go below the surface, the total effective mass pulling on you decreases, as any part of the Earth further from the center than you are no longer contributes. Thus the g-force you undergo decreases as you approach the center of the Earth. With the denser object, you can get much closer to the center before passing beneath its surface, so g-force continues to increase as you get closer than the Earth surface distance, up until you pass below the surface of the object. (In this diagram, the vertical axis is gravitational potential, while gravitational force would be represented by the slope of the line at a given point, with horizontal being 0g.)  4. Originally Posted by Janus There is no such thing as a Rubber sheet model for gravity. There is the Rubber sheet analogy. The difference is that the analogy is just a way to help laymen visualize the concept of space-time curvature, while a model is used to make actually predictions of the behavior of objects in a gravity field. No physicist has ever used the Rubber sheet analogy to make real predictions of the behavior of gravity.

This is because, like pretty much any analogy, it is not a totally accurate representation. For example, space-time is represented by the 2D sheet, but the masses are 3D objects. A more accurate representation would have the "masses" be part of the sheet.
Here is cross-section view of how this works. There is no "circle" that represents the mass, Just points on the curve that show where the surface of the mass would be. The part of the curve in between the vertical lines is gravity below the surface of the mass. The outer two lines in this diagram show the surface of the Earth. Outside of the lines is gravity above the surface, inside is of them is below the surface. The red curve is for a object with the same mass, but denser than the Earth. The red vertical lines mark of its surface.
Everywhere outside of the lines which mark the distance of Earth's surface, the two curves perfectly overlap. It is only when you get closer to the denser object than Earth surface distance that the curves deviate.

The reason the red curve dips deeper is that, for the Earth, as you go below the surface, the total effective mass pulling on you decreases, as any part of the Earth further from the center than you are no longer contributes. Thus the g-force you undergo decreases as you approach the center of the Earth. With the denser object, you can get much closer to the center before passing beneath its surface, so g-force continues to increase as you get closer than the Earth surface distance, up until you pass below the surface of the object. (In this diagram, the vertical axis is gravitational potential, while gravitational force would be represented by the slope of the line at a given point, with horizontal being 0g.)
This is an excellent post but it totally misses his point: he's denying the validity of the Shell Theorem. As such, his post has no place in this forum.  Tags for this Thread Posting Permissions
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