Gravitational force vs space time fabric

In summary, the conversation discusses the relationship between Newtonian gravitational force and the "tension" or "stress" in the fabric of space time caused by the depression of two masses. It is determined that the two are not equivalent and that gravitational force is a result of the curvature of space time, not a direct force. The concept of pressure is also introduced and its role in gravitational attraction and repulsion is discussed. The conversation ends with a clarification and a thank you.
  • #1
blade_chong
33
0
Hi guys, I got a question that has been in my head for a while.
Is the Newtonian gravitational force equivalent to the "tension" in the space time fabric caused by the depression of 2 masses? If it is equivalent, does it means that gravitational force does not act in a straight line but it spread across the curvature in the space time fabric? If it is not, then what is the Newtonian gravitational force representation in general relativity?
Thanks
 
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  • #2
(1)Is the Newtonian gravitational force equivalent to the "tension" in the space time fabric caused by the depression of 2 masses? (2)If it is equivalent, does it means that gravitational force does not act in a straight line but it spread across the curvature in the space time fabric? (2) If it is not, then what is the Newtonian gravitational force representation in general relativity?
Did you mean "stress" instead of "tension"...??

(1) no
(2) no
(3) GR simplifies to Newtonian attraction at low energies and pressures. Newtonian gravity asserts the strength of gravitational attraction between two objects is due only to their masses and the distance between them. period.

GR attributes gravity to curvature of spacetime, not to force, and asserts that not just mass contributes the the strength of the gravitational field but energy and pressure as well.

The concept of pressure leads to positive pressure contributing to ordinary gravitational attraction, while negative pressure contributes to repulsive gravity...hence the cosmological constant.

A finite mass, like a planet, ends up having curved space time fabric...but an infinite plane of mass, for example, would not have such curved space time fabric...no tidal forces...this is the kind Einstein envisioned in his "equivalence" principle...
 
  • #3
Thx a lot Naty1 for yr help
I have gotten a clearer picture now
 

1. What is gravitational force?

Gravitational force is a fundamental force of nature that is responsible for the attraction between objects with mass. It is the force that keeps planets in orbit around the sun and holds objects to the surface of the Earth.

2. What is space-time fabric?

Space-time fabric is a concept in physics that describes the fabric of the universe. It is a four-dimensional continuum that combines the three dimensions of space with the dimension of time. It is the medium in which all objects with mass exist and interact.

3. How does gravitational force affect space-time fabric?

According to Einstein's theory of general relativity, gravitational force is not a force between two objects, but rather the curvature of space-time caused by the presence of mass. Massive objects, such as planets, create a dip in the space-time fabric, causing other objects to move towards it.

4. How is the strength of gravitational force related to the curvature of space-time fabric?

The strength of gravitational force is directly proportional to the curvature of space-time fabric. The more massive an object is, the stronger its gravitational force and the greater the curvature of the space-time fabric around it.

5. Can space-time fabric be affected by anything other than mass?

According to general relativity, space-time fabric can also be affected by energy and momentum. In addition, the presence of gravitational waves, which are ripples in the fabric of space-time, can also cause changes in the curvature of space-time fabric.

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