All Questions
10
questions
1
vote
0
answers
42
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Einstein's equation of gravitation field [duplicate]
I'm looking for the reason why there is the number eight $8$ at the r.h.s. of EI:
$$R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}=\frac{8\pi G}{c^2}T_{\mu\nu}.$$
My attempt was to take the limit of this equation ...
- 255
2
votes
1
answer
139
views
Physical relevance of the $ij$ components of the Einstein field equations in the Newtonian limit
In the weak field limit of general relativity (with matter described by a perfect fluid consisting only of dust), we have the following correspondences:
$00$-component of the Einstein field equations ...
- 830
4
votes
2
answers
695
views
General relativity when can we approximate to Newtonian gravity?
Lets consider this scenario in deep void of space where other curvatures of large objects are negligible in this case and we bring 2 objects lets say $A$ and $B$.
We give it a force slightly lower ...
- 441
2
votes
1
answer
71
views
Is the Newtonian gravitational potential $-\frac{GMm}{R}$ just an approximation?
Is $-\frac{GMm}{R}$ just an approximation? I believe that it is since we assume that one of the mass is at rest when deriving it.
- 21
15
votes
8
answers
2k
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What is the true nature of gravity? [closed]
In 17th century, Sir Isaac Newton gave us the universal law of gravitation which stated that gravity is an inverse square force. In 1915, Albert Einstein recognised gravity as a curvature of space-...
- 255
5
votes
3
answers
2k
views
Newtonian Limit of Schwarzschild metric
The Schwarzschild metric describes the gravity of a spherically symmetric mass $M$ in spherical coordinates:
$$ds^2 =-\left(1-\frac{2GM}{c^2r}\right)c^2 \, dt^2+\left(1-\frac{2GM}{c^2r}\right)^{-1}dr^...
- 1,037
34
votes
4
answers
8k
views
How can we recover the Newtonian gravitational potential from the metric of general relativity?
The Newtonian description of gravity can be formulated in terms of a potential function $\phi$ whose partial derivatives give the acceleration:
$$\frac{d^2\vec{x}}{dt^2}=\vec{g}=-\vec{\nabla}\phi(x)=\...
- 1,406
4
votes
1
answer
532
views
Modifying Newtonian gravity to fit observed precession of Mercury's orbit
The idea is to modify Newtonian gravity so that it fits measurements of orbits around the sun. For example the precession of Mercury's orbit unlike Newtonian $n$-body simulations.
I'm currently not ...
- 103
8
votes
2
answers
3k
views
How general relativity gets to an inverse-square law [duplicate]
I understand that a general interpretation of the $1/r^2$ interactions is that virtual particles are exchanged, and to conserve their flux through spheres of different radii, one must assume the ...
- 4,256
20
votes
7
answers
7k
views
Is Newton's Law of Gravity consistent with General Relativity?
By 'Newton's Law of Gravity', I am referring to
The magnitude of the force of gravity is proportional to the product of the mass of the two objects and inversely proportional to their distance ...
- 6,000