Questions tagged [gravitational-waves]
For questions about the propagation of waves carried by space-time, for instance as described by general relativity. Not to be confused with gravity waves, such as ocean surface waves.
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Non-test-particle dynamics from inside a black hole horizon
It seems to me that most arguments in favor of impossibility of communication from beyond black hole horizon region are based on "test-particle" scenario, where the falling object is (very) light with ...
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Different perturbations?
In Newtonian gravity and gravitational waves the metric ($g_{\mu\nu}$) changes. The metric tells us how to measure distances in a spacetime (in this case the flat $\eta_{\mu\nu}$), and is correlated ...
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Newtonian fields interaction
Newtonian gravity is a linear approximation of a very weak field, such as gravitational waves. But why do gravitational waves interact with each other while Newtonian fields don't?
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GW luminosity depends on the 3rd time derivative but quadrupole formula depends on the 2nd time derivative?
The quadrupole formula for GW emission (see here) states that the metric perturbation is given by:
\begin{align}
\bar{h}_{ij}(t,r) = \frac{2G}{c^4 r} \ddot{I}_{ij}(t - r/c)
\end{align}
This ...
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Tensioned string and gravitational wave
Potential energy of the spring/string is a square of deformation. It is way better to add deformation to tensioned resonator.
In existing gravitational wave resonators wave deforms antenna some 10^-20 ...
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Teukolsky's identity for Petrov type D spacetimes
I've been trying to derive the identity (2.11) from this Teukolsky paper, which reads:
$$
[D-(p+1)\epsilon + \epsilon^* + q \rho - \rho^*](\delta - p \beta + q \tau) - [\delta - (p+1)\beta - \alpha^* +...
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Perturbations of Schwarzschild Metric
I am reading Luciano Rezzolla's lecture notes on Gravitational waves from Perturbed Black Holes and Relativistic Stars. Link. In sections 2.2 and 2.3, he splits the metric perturbation components into ...
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Noise in gravitational wave detections
I'm reading a paper (https://doi.org/10.1103/PhysRevD.49.2658) in order to understand the use of Fisher Matrix in gravitational wave detection. I'm a bit confused with the assumptions they do about ...
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What is expanding and contracting in LIGO? The space between the arms, the arms themselves, or both?
At LIGO, gravitational waves are detected by the interference effects of the laserlight traveling in the mutually orthogonal arms.
But what is actually expanding and contracting? Are the arms ...
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Is there any way in which orbits emitting gravitational waves could avoid coalescence?
In the very far future, all orbits will eventually coalesce as they lose orbital energy through gravitational waves emission.
However, can there be 3-body or N-body interactions in which the members ...
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Do gravitational waves cause matter to radiate?
Gravitational waves distort the "fabric" of spacetime. In doing so, it seems they can cause particles to accelerate.
On the other hand, textbook electromagnetism predicts accelerated charges ...
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Since waves are abstractions, does it even make sense to ask whether light is a wave? [closed]
All waves transmit energy.
Water Waves
Let's say you're in the middle of a calm pond and you start moving your hand up and down. Transverse "waves" are generated, and they propagate ...
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Do magnetar stars relatively produce stronger gravitational waves than neutron stars? [closed]
According to Reissner-Nordstrom solution to Einstein's gravitational field equations in astronomy the electric or magnetic or both, field of a charged body of mass generates its own gravitational ...
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Will LISA be able to detect quantum corrections to the waveforms of gravitational radiation?
My main motivation for asking this question is this paper, in which the authors calculate the periodic orbits of a
small celestial object around a supermassive quantum-corrected black hole and the ...
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Do gravitational waves change the color of light?
It stands to reason if gravity changes the color of light then the color will be affected by gravitational waves. My question is, when the waves pass, will the color change be permanent or will the ...
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Polarization of gravitational waves - Dirac's rotation operator
I refer to the page extracts below. I think my question is fully self-contained, but for background:
Dirac is dealing with the weak-gravity case and gravitational plane waves moving in the $l_\sigma$ ...
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Can gravitational energy be localized in the case of plane waves?
Reading Dirac's "General Theory of Relativity", Chap. $33$ "Gravitational waves". He shows that in a weak gravitational field ($g_{\mu\nu}$ approximately constant), using harmonic ...
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Localization of gravitational energy-momentum in plane waves
Dirac ("General Theory of Relativity") shows that in the case of a weak gravitational plane wave, the Einstein pseudo-energy tensor ${t_\mu}^\nu$ has the (approximate) form of a tensor in ...
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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}$. ...
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What Does Feynman Mean When He Says Amplitude and Probabilities?
In Feynman lectures on gravitation section 1.4, he tries to debate over whether one should quantize the gravitation or not.
He provides a two-slit diffraction experiment with a gravity detector, which ...
Buzz♦
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Why are laser beams not affected by gravitational waves in Michelson interferometer? [duplicate]
Michelson interferometers are used to detect gravitational waves. This means two laser beams are sent in long arms and reflected at the end. Usually, they annihilate each other and no signal is ...
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The data file of the LISA Interferometer results
How to extract the data of the strain versus frequency plot of the Laser Interferometer Space Antenna (LISA): Figure (2) in this paper:
https://arxiv.org/abs/1702.00786
The paper doesn't contain any ...
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How to plot the curve of the gravitational wave energy density giving the data of the strain versus frequency
I want to plot the curve of energy density ($\Omega$) of the gravitational waves versus frequency that are predicted by the Einstein telescope. But in the ET pages:
https://moscow.sci-hub.se/4444/...
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Extreme Mass Ratio Inspirals and GWs cycles
I was reading through the following paper GRMHD study of accreting massive black hole binaries in astrophysical environment: A review. Therein, we have the following image
It is not quite clear how ...
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On gravitational waves of dark matter collisions
It is known that dark matter interacts gravitationally (and weakly in other ways as predicted by the WIMP model), and dark matter is present in the same space-time fabric as that of matter. When two ...
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Gravitational Wave Impact on Connected Particles
We understand that when a gravitational wave passes through a setup with two freely falling particles, it causes them to oscillate and change the distance between them. However, if the two particles ...
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Solving the wave equation of a tensor $h_{\mu\nu} = (1/2) (e_\mu e_\nu + e_\nu e_\mu)$
It is known that the solution to the wave equation for a tensor
$$
\square h_{\mu\nu} = 0
$$
is
$$
h_{\mu\nu}(\vec{x}, t) = \int \frac{d^3k}{(2\pi)^3} \sum_{\lambda=+,\times} \left( \epsilon_{\mu\nu}^{...
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What does "DC" mean in gravitational physics?
I have came across a few works in gravitational physics using the term "DC" without further explanation of its meaning. For example, consider Strominger's 1703.05448, which states in p. 2 ...
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What is the difference between Hawking radiation and a black hole laser?
While reading this paper (https://arxiv.org/abs/1409.6550), I got a little bit puzzled: what is the difference between Hawking radiation and a black hole laser? Is it the same thing? From my ...
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Gravitons with negative mass?
I have been reading several papers on massive gravity. All of them have equations that involve the square of the graviton mass, rather than graviton mass itself. See for example, equations 43 and 44 ...
CommunityBot
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Do particle physics experiments need to take a possible gravitational wave background into account?
As I understand gravitational waves, we can barely detect them, because their strength is so small. On the other hand, they are presumably able to move individual particles like electrons. Does this ...
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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=...
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What are the Maxwell's equations for gravitational waves?
Maxwell's four equations can be used to describe the propagation of electromagnetic waves. What is the equivalent for gravitational waves - if that question makes sense?
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Describing force accumulation trend of an infinite volume with evenly distributed radiative sources
I am looking for confirmation if I've built my equation properly.
My goal is to describe the change in force over time at a given point if evenly distributed radiators (in-phase or cumulative energy/...
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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 ...
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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,...
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Using Gravitational Waves as an observation technique
In theory, could you possibly use Gravitational Waves as a way to detect and observe subatomic particles without disrupting them if the gravitational wave was small enough? And then translate that ...
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Simultaneous operations of LHC and LIGO
I once asked a question regarding atomic clocks near particle accelerators.
Where the high-energy of the accelerators would be considered a source of stress energy. I was made to understand that the ...
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Gravitational wave flux in Effective One-Body (EOB) models
I'm working for my M2 internship on gravitational waves in effective one-body approach, and I'm struggling in understanding how they compute the non-conservative flux from GW radiations. Most of the ...
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Where can I obtain the recorded data of GWs and corresponding best-matched templates for published events confirmed by LIGO please?
It is known that the LIGO-Virgo Collaboration (LVC) has released over 100 confirmed GW events. For each event, I believe that they possess the recorded raw data, which is a one-dimensional sequence of ...
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Can gravitational waves orbit each other to form a standing wave?
Since gravitational waves are a type of propagation of energy of some sort, they ought to induce their own gravitational field. I'm assuming this extra gravitational force / curvature is independent ...
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Geodesics on a gravitational wave
$$
\newcommand{\dot}[1]{\overset{.}{#1}}
\newcommand{\ddot}[1]{\overset{..}{#1}}
$$
Consider the following metric, which describes a linearized plane gravitational wave:
$$
g_{\mu\nu} = \eta_{\mu\nu} +...
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How to relate a gravitational plane wave to the GW from a binary system?
I have two different forms of gravitational waves that I am trying to reconcile.
A monochromatic GW with angular frequency $\Omega$ propagating in the $\textbf{n}$-direction can be expressed as
$$ ...
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What happens to the angular momentum of two merging black holes?
Suppose that two black holes of roughly equal mass in a binary system, formed from say a large mass stellar binary system, are in orbits around their center of mass. Further, suppose that we are ...
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Gravitational waves from metric perturbation
I have just been introduced to gravitational waves from metric perturbations and I have some questions about gauge symmetry and solutions in a given gauge.
Consider a metric on the form $g_{\mu\nu} = \...
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Is LIGO flawed by the identical expansion of laser wavelength and arms in presence of a gravitational wave?
LIGO, Laser Interferometer Gravitational-Wave Observatory, is a large-scale physics experiment aiming to directly detect gravitational waves.
The device measures the phase shift laser beams.
If I ...
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Particles Associated With Gravitational Waves
I've been reading about linearized GR and the study of gravitational waves, and an odd thought popped into my head. According to wave-particle duality (admittedly, usually used in quantum mechanics!), ...
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How can a pulsar slow down?
I saw in some astronomy textbooks that pulsars gradually slow down due to the loss of energy by its radiation. I wonder why this is possible?
Although the radiation is now not thermal but in the form ...
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How do gravitational waves carry energy when gravitational energy cannot be localised?
I have a very naive question, actually someone asked it and I can't answer. It simply asks that if gravitational energy cannot be localised (we cannot write a pure gravitational energy momentum tensor)...
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Gravitational waves from any metric?
First, to be clear, I know practically nothing on gravitational waves and finding their solutions. The most I know confidently is that they are found by expanding the metric in a weak field expansion ...
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