Gravity waves and gravitomotive force

  • I
  • Thread starter snorkack
  • Start date
  • #1
1,773
313
For a binary emitting gravity waves: are there any directions of space into which gravity waves are not emitted for reasons of symmetry?
Also:
a steadily rotating electric charge current causes a magnetostatic field
A steadily rotating mass must cause a gravitomagnetostatic field.
Electrostatic field of an electric monopole charge is a potential field. Its integral through any closed circuit is zero.
A gravitostatic field of a mass monopole charge is also a potential field. Its integral through any closed circuit is also zero.
When a magnetic field varies in time, it causes electromotive field. It is electric field, but it is allowed to have nonzero integral through closed circuits.
What happens when gravitomagnetic field varies through time, for example due to orbital movement?
Can varying gravitomagnetic field include a gravitomotive field, with nonzero integral over closed circuits?
In other words, can varying gravitomagnetic field cause a wheel to rotate?
 

Answers and Replies

  • #2
38,061
15,842
There is a framework in which gravity is treated by analogy with electromagnetism:

https://en.wikipedia.org/wiki/Gravitoelectromagnetism

This framework has limitations: for example, it is not covariant under coordinate transformations, as Maxwell's equations are. So it cannot model gravitational radiation. But it does give a good idea of which EM effects have reasonably close gravitational analogues.
 
  • #3
1,773
313
So, repeating the first question:
For a binary emitting gravity waves: are there any directions of space into which gravity waves are not emitted for reasons of symmetry?
 
  • #4
pervect
Staff Emeritus
Science Advisor
Insights Author
10,158
1,308
So, repeating the first question:

For a binary emitting gravity waves: are there any directions of space into which gravity waves are not emitted for reasons of symmetry?

I'd say yes, offhand, that there shouldn't be any GW emission in the directions in which the components of the quadrupole moment is constant. For instance, if the rotation is in the xy plane, and z is constant so that the integral of ##z^2 dm## is constant, I wouldn't expect any gravitational radiation in the z direction. But I don't have a rigorous proof, or a reference that says exactly this (Wiki and by memory several textbooks do say that you need a nonzero quadrupole moment to have gravitational radiation at all, but this doesn't quite say anything about the direction of the radiation).
 

Related Threads on Gravity waves and gravitomotive force

  • Last Post
Replies
9
Views
2K
  • Last Post
Replies
18
Views
1K
  • Last Post
Replies
4
Views
1K
Replies
7
Views
3K
  • Last Post
Replies
4
Views
5K
  • Last Post
2
Replies
36
Views
9K
  • Last Post
Replies
23
Views
7K
Replies
18
Views
2K
Replies
2
Views
664
  • Last Post
Replies
4
Views
814
Top