All Questions
16
questions
1
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How does gravity act and propagate in a 2+1D universe?—Newtonian versus general relativity
In a hypothetical 2+1D universe:
if we apply the Newtonian concept of gravity, we might expect that the gravitational force between two mass points with a distance of $r$ would diminish linearly with ...
- 618
1
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0
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86
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How does a curvature in time equate to Newtonian gravity? [duplicate]
I often read that a curvature in time (the rate at which clocks tick) near a massive object, is considered to be the source of Newtonian gravity.
This got me wondering, does General Relativity use the ...
-6
votes
1
answer
396
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Why use the Minkowski metric in general relativity? [closed]
We can represent Newton's free fall as a curved trajectory in 4-dimensional spacetime. Time is on the ordinate and space on the abscissa.
By adding an initial speed to the object, we can reproduce ...
- 97
-5
votes
1
answer
668
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How can two objects with the same mass attract each other?
According to Einstein's theory of GR, two objects with the same mass won't atract each other, Why i'm saying this? The atraction according to GR happens because the objects with less curvature of ...
user319766
4
votes
3
answers
370
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What is the physical meaning and origin of the gravitational constant $G$?
Is $G$ just a value to fix the units in the equation? Something like a proportionality constant or a coupling constant?:
$$F=\frac{G m_{1} m_{2}}{r^{2}}$$
Does it have any physical meaning or physical ...
- 4,170
1
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1
answer
358
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Curvature in the Newtonian Gravity
Let me give a little bit of insight. I was trying to calculate the geodesic of different curves when I realised some relation (if I can call it like that), between General Relativity and Newton's Law ...
- 1,525
4
votes
2
answers
1k
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If MOND were true, what would that imply for the geometrical description of gravity as curved spacetime?
As I understand it, Modified Newtonian Dynamics, or MOND (Milgrom M., 1983, ApJ, 270, 365), slightly alters Newton's Law of Gravity by introducing a low acceleration limit below which (for an object ...
- 109
3
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1
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208
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Attemp to encode newtonian gravitation as 3-dimensional space curvature
In lecture 9 of this series of lectures, Professor Frederic Schuller (around time 24:00) is trying to answer the question about the possibility to interpret newtonian gravity as a three-dimensional ...
- 1,290
6
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9
answers
3k
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According to general relativity planets and Sun bend the spacetime (explaining gravity), but does this hold true for smaller objects?
According to general relativity planets and the sun bend spacetime, and that is the explanation of gravity. However, does this hold true for smaller objects, like toys, pens, etc.? Do they also bend ...
- 119
2
votes
2
answers
466
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Why isn't general relativity equivalent to Newtonian gravity?
I know this question may seem a bit laughable, but the way the equations for general relativity are formed is through Poisons equation:
$$\nabla^2\phi=4 \pi G \rho$$
Which are formed using Newton's ...
- 775
2
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4
answers
646
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How can one understand with an example that Newton's law(s) fail in a curved space?
Is it true that Newton's law is not valid in curved spaces? If yes, how can I understand it and explain to a high school student preferably with an example? I tried to think about the motion of a ...
- 11.7k
0
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1
answer
277
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Is it possible to express acceleration in a gravitational field as a logarithmic spiral?
The derivation starts from a logarithmic spiral:
$r=de^{b\theta}$
The lenght of a part of the spiral i calculated by:
$\int_{\theta_1}^{\theta_2} \sqrt{(\frac{dr}{d\theta})^2+r^2} d\theta$
From 0 ...
- 61
1
vote
1
answer
135
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When is Newton's law of gravity recoverable in GR?
Often in a course in GR one can recover Newton's law of gravity under certain assumptions. weak field, slow moving particles etc. Is there a general method to recover Newton's laws of gravity for an ...
- 1,988
3
votes
1
answer
579
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A few questions about Einstein's theory involving gravity
After watching a documentary about Einstein's theory of relativity, my mind was busy trying to comprehend how space bends when space is void and not made of matter. And additionally, does his theory ...
- 33
2
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3
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293
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Newtonian space
Often, gravity in relativity is depicted as and the orbit of a celestial body around another body like a ball spinning in a deep bowl, which is said to be space influenced by the presence of a large ...
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