All Questions
125
questions
21
votes
3
answers
2k
views
Can perfectly stable orbits exist in GR?
Defining "stable orbit" between two bodies as one where, in the absence of other bodies or non-gravitational forces, the distance stays between some value pair $r_{min}>0$ and $r_{max}$. ...
- 363
7
votes
1
answer
747
views
Can gravity radiate?
In electromagnetism, when a charge accelerates, it emits radiation. We know this because we can write the retarded potentials, apply $\vec E=- \nabla V-\frac{\partial \vec{A}}{\partial t}$ and $\vec B=...
- 1,616
2
votes
1
answer
60
views
Acceleration at peak of a gravitational wave
The amplitude of the strongest gravitational wave signal detected by LIGO sofar can maybe be expressed as an acceleration? If so, what would the numerical value be (in m/s^2)? I would like to compare ...
- 243
3
votes
0
answers
80
views
Why does the wavelength of gravitational waves increase with larger energy?
Gravitational and electromagnetic waves are quite similar, as both are fundamental force waves that travel at the speed of light and have no limit to their range, but when it comes to electromagnetism,...
- 413
2
votes
1
answer
50
views
How to relate a gravitational plane wave to the GW from a binary system?
I have two different forms of gravitational waves that I am trying to reconcile.
A monochromatic GW with angular frequency $\Omega$ propagating in the $\textbf{n}$-direction can be expressed as
$$ ...
- 1,751
1
vote
1
answer
156
views
Can a single black hole emit gravitational waves and evaporate?
I have read this:
Yes, single neutron stars can emit gravitational waves if they have sufficient asymmetries.
For some background, an object symmetric about its axis of rotation does not produce ...
- 29k
2
votes
0
answers
47
views
Gravitational Wave Emission from Symmetrically Accelerating Systems
I've been exploring the concept of gravitational wave (G-wave) emission from symmetrically accelerating systems and have encountered a puzzling question. Standard sources typically state that ...
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
22
votes
4
answers
3k
views
Does the gravitational field have a gravitational field?
I am currently reading electrodynamics from Feynman. When talking about the energy of the electromagnetic fields, he says that the location of the field energy could be known at least theoretically ...
- 639
4
votes
4
answers
524
views
Interpretation of gravitational waves
A wave has peaks and valleys. I can think of a sine wave as a wave with peaks and valleys.
Now, if gravity is a wave, can we say that gravity would have peaks and valleys, with the valley becoming ...
- 1,023
9
votes
2
answers
288
views
Is there partial gravitational shielding?
Gravitational waves carry energy. The sticky bead argument shows that this energy can be extracted: https://en.wikipedia.org/wiki/Sticky_bead_argument
But Lee Smolin points out that
"In ...
- 476
2
votes
1
answer
65
views
Malus law for gravitational waves
What is the analogue of the Malus law for polarized electromagnetic waves to the cause of plus and cross polarized gravitational waves?
Bonus: What if gravitational waves have further degrees of ...
- 6,611
0
votes
1
answer
65
views
Gravitational recoil with stars/planets...? [closed]
When two black holes are merging, one of them can be ejected if it has less mass than the other black hole, so the gravitational waves emitted by both of them is unbalanced, and the more strong ones ...
- 2,462
8
votes
1
answer
802
views
Do gravitons refer to gravity or to gravitational waves?
I am confused about what gravitons exactly are.
On the one hand it is said that gravitons are presumed to represent gravity (see Wikipedia "Graviton" : "In theories of quantum gravity, ...
- 3,155
2
votes
2
answers
102
views
More on frames of reference and coordinates in GR
I have read other questions concerning this subject, and by now I believe that in order to solve a gravitational problem in GR, one has to basically abandon the notion of frames of reference. However, ...
- 307