All Questions
64
questions
3
votes
2
answers
86
views
Tug of war between observers in frames with different rate of time
You have a very dense hollow sphere of matter. Observer A is inside the sphere inside a rocket. Observer B is in an identical rocket outside the sphere where the ring's gravity is negligible. They are ...
- 171
0
votes
1
answer
57
views
When is it appropriate to say Newtonian gravity is a force? When is it not appropiate? [closed]
Please help me understand the notion of force when it is applied to Newtonian gravity. From my understanding forces in physics involve interactions with at least 2 objects and can cause an ...
- 431
-2
votes
1
answer
139
views
If time moves slower the faster you go. Doesn't that mean that the gravity experienced will be lower too?
Disclaimer: I still don't understand the theory of general relativity. I'm completely ignorant.
I was watching the movie Interstellar yesterday and saw their interpretation of time dilation, I also ...
- 127
1
vote
2
answers
224
views
Does a linearly accelerating spherically symmetric body emit gravitational waves
According to Birkhoff's Theorem, any spherically symmetric body will not emit gravitational waves. I can understand this for an object that is contracting and expanding because from far away the ...
- 101
0
votes
2
answers
129
views
Gravity is not a Force? [duplicate]
I don't know much about this topic, but I read something saying that gravity is not a force using an example of inertial observation. I started thinking about the topic again when I was researching ...
- 11
4
votes
6
answers
1k
views
How does general relativity theory explain gravitational pull? [duplicate]
I watched some videos on YouTube that explain why gravity is not a force,
according to general relativity theory.
I can wrap my head around the idea that spacetime can be curved due to a massive mass,
...
- 141
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
6
answers
804
views
Is the gravitational force a phenomenon or a theoretical invention? [closed]
We use to say that gravitational force is a phenomenon. But since the theory of General Relativity replaced Newtonian gravitational force, how is it possible for a phenomenon to be replaced by a ...
0
votes
2
answers
429
views
Why is gravity not a force? [duplicate]
Gravitation is the mutual attraction of masses, yet Einstein showed it is how spacetime is curved by mass and how mass moves in relation to this curvature. Why then do we still consider gravitation a &...
- 510
25
votes
4
answers
7k
views
If gravity is not a force, then how come gravitational assists work?
I have learned about general relativity and how gravity arises from spacetime curvature. And I have always been taught that gravity is not a real force in the sense that
$$\frac{dp}{dt} = 0$$
And from ...
- 1,896
4
votes
3
answers
472
views
How does relativity explain Newton's apple? [duplicate]
You must have heard the anecdote about the apple falling on Newton's head that led him to come up with the concept of Gravity. A long time later, Einstein upgraded it to the General Theory of ...
- 91
2
votes
4
answers
122
views
Einsteins gravity theory, but for static objects [duplicate]
https://www.youtube.com/watch?v=XRr1kaXKBsU this is a good video to explain Einsteins gravity.
The video claims that objects always move in a straight line, with an absence of a force of gravity, ...
- 133
0
votes
1
answer
76
views
How do you find the distance between a massive object and its certain gravitational force?
Okay so I know I might've not phrased the question very well so I will give an example to try to make sense of it:
Say we have the moon and a place in space where the moon's gravitational force is 1,...
- 33
4
votes
4
answers
929
views
Where does gravity come from?
First, in my childhood, I learned that gravity is a force. Later, I learned that gravity is a property of spacetime. If gravity is a property of spacetime, then why is it one of the fundamental forces....
- 49
11
votes
4
answers
2k
views
Why does gravity seem to have two natures (force or warping of space and time)?
In classical mechanics, gravity is regarded as a force but in general relativity it's a warping of space and time in presence of mass. Are these two definitions the same? Or is this a duality nature ...
- 78