Linked Questions

-1
votes
2answers
589 views

Gravity in the center of a hollow neutron star [duplicate]

Imagine a hollow 100 metre diameter (for example) sphere made of incredible dense material (ie neutron star dust etc) but is self supporting (ie the central cavity). Assuming that the sphere skin is ...
4
votes
1answer
575 views

The metric Tensor inside a massive shell [duplicate]

Given a fixed shell with the mass of $M$ and a radius $R$ , what would be the metric tensor for $r<R$? I do know that using Birkhoff Theorem the metric for $r>R$ should be schwarzschild. I'm ...
1
vote
0answers
85 views

Shell theorem in general Relativity [duplicate]

How is it that gravitational field inside a spherically symmetric body is zero in case of General Relativity where the equations are nonlinear unlike Newtonian gravity where the force is perfectly $1/...
16
votes
5answers
3k views

What would happen if I were to fall into a massive hollow planet?

Imagine, if you will, there exists somewhere out there a supermassive planet. For some reason, this planet is only a shell of its former existence and all that is left is a crust of substantial size ...
9
votes
4answers
1k views

What is the general relativity explanation for why objects at the center of the Earth are weightless?

The idea that as you move through the earth you get a symmetric cancelling of gravitational acceleration which approaches zero acceleration due to gravity at the center of the earth makes a lot of ...
12
votes
2answers
5k views

Gravitational field intensity inside a hollow sphere

It is quite easy to derive the gravitational field intensity at a point within a hollow sphere. However, the result is quite surprising. The field intensity at any point within a hollow sphere is zero....
6
votes
3answers
507 views

Zero $g$ in a black hole?

At the very centre of the Earth, masses cancel each other out, creating an effective zero-$g$ environment. Would the same happen in a black hole?
5
votes
1answer
145 views

How does time behave inside a massive spherical shell?

According to General relativity the clocks in our satellites in the atmosphere tick faster than those on Earth, as they are farther from the gravitational well of Earth and are free falling. ...
2
votes
1answer
272 views

Two spherically symmetric shells of matter collapsing into a black hole

Suppose I have a thin spherically symmetric shell of matter of (rest) mass $M$ that collapses to form a black hole, and later a second thin spherical shell of mass (rest) $M'$, concentric to the first,...
0
votes
1answer
80 views

Speed of light on and through a hollow planet [duplicate]

First of all, this is a thought experiment regarding faster-than-light communication. Say you had an immense hollow planet that was made of some heavy material such as neutron-star dust. Due to the ...
4
votes
0answers
66 views

The (Newton-Laplace-Ivory-Arnold) shell theorem in general relativity

It is well-known that Birkhoff's theorem and the classification of LTB spacetimes proves one version of Newton's shell theorem in the context of GR. Another statement in Newtonian gravity, often ...