Questions tagged [gravitational-waves]
The gravitational-waves tag has no usage guidance.
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Dark matter - Graviton [on hold]
Ok, I have been thinking of this for a long time.
I have made a theory about the quantization of gravity and gravity more generally. Yes you heard me right. Please do not leave. This post is not a ...
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Can photon Create gravitational wave when it travel through Space-time? [duplicate]
When big Explosion occurs in space it create gravitational wave. but it is possible that when photon (a packet of energy) make displacement in space-time it also create gravitational wave after all it'...
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Does the photon decay due to loss of energy in a gravitational shock wave that it creates? [duplicate]
If photon has energy, it has gravity.
If photon has gravity and move through space at light speed, it creates gravitational shock wave (like sonic boom because gravity move at the same speed as ...
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112 views
Can dark matter actually be gravitational radiation?
It seems to exist like only space distortion, and it seems to move just like radiation (specially when galaxy clusters collide, dark matter goes trough unaffected just like some type of radiation).
...
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Gravitational wave, single particle, double slit experiment, measurement?
Would it be possible to measure the gravitational wave of a single particle say a proton (or other particle) which would give such a pattern as to solve the question of whether a particle has a single ...
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Does frequency of light change in the LIGO interferometer arms?
There are a number of questions on the internet and on this site asking about how the LIGO interferometer measurement works given that the gravitation wave stretches both the length of the ...
2
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1answer
88 views
Detectability of gravitational waves emitted by a free-falling object, by different observers
Does an object falling radially in a gravitational field of a planet emit gravitational waves as seen by an observer on the surface of the planet?
What about an observer falling along with the object?...
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2answers
60 views
If gravity is a wave, what medium does it pass through? Is there a medium that it can not pass through?
I listened to a podcast discussing gravity and had this question. My apologies if it has been aptly answered somewhere else.
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What's the shortest “safe” distance from a neutron star merger?
Take GW170817 for example, the first neutron star collision picked up by LIGO. Given how much data we got from that event, can anyone figure out what the "blast radius" is, and how far away from the ...
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127 views
Why does everyone seem to assume that gravitational waves will always be very small? [duplicate]
The size or effective distortion field of a gravitational-wave perturbation at any given location in space-time is determined by the distance separating the source and that location. This describes a ...
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“High-Frequency Gravitational Wave Generator” patent from U.S. Navy, among other things [closed]
A scientist going by the name Salvatore Cezar Pais, employed by the U.S. navy, was recently granted the following eyebrow-raising patents:
-High frequency gravitational wave generator (10322827)
-...
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61 views
Gravitons from linearized gravity
Linearizing gravity as follows:
$$
g_{\mu\nu}=\eta_{\mu\nu}+h_{\mu\nu}
$$
Up to this point, everything is a 4x4 matrice.
How does one eventually recover a spin-2 particle which, according to https:/...
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Newtonian Gravitational Waves
I was thinking about the classical equations for gravity. I got stuck on two equations:
$$\vec{\nabla}.\vec{g}= 0$$
and
$$\vec{\nabla} \times \vec{g}= 0$$
The first equation is Gauss law of ...
2
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2answers
53 views
Can gravitational waves be visualized in the elastic rubber sheet model of gravity?
To visualize the space curvature related to gravity,
there is a model or analogy using an elastic sheet and a weight. A rubber sheet is spanned like a very soft trampoline, and a heavy ball on it ...
2
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61 views
Why gravitational waves can only be generated by a time-varying quadrupole moment of the mass distribution?
The (rather old) source I dispose of "Sexl, Urbantke : Gravitation and Cosmology" describes the radiation of gravitational waves only rather sketchy. So why gravitational waves are only generated by ...
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1answer
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Can GWs move objects (excerpt pressure on matter) like EM waves?
Gravitational waves are real, they have been observed.
Gravitational waves are disturbances in the curvature of spacetime, generated by accelerated masses, that propagate as waves outward from ...
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Can gravitational waves be used to investigate the inside of black holes?
I do understand that nothing, no particles and no information can escape a BH.
Gravitational waves are real, they have been observed.
Gravitational waves are disturbances in the curvature of ...
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Do gravitational waves disperse/refract (like EM waves in a prism)?
I have read this question:
What is the relationship between a gravitational wave and a graviton?
where kingledion says:
Gravitational waves were theorized a century ago and recently ...
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Confused about the gauge transformation of the amplitude tensor for gravitational waves
Far away from the field sources, where the energy-momentum tensor $$T_{mn}=0 \tag{m,n=0,1,2,3}$$
The linearized EFE becomes $$\Box \bar h_{mn}=0 \tag{1}$$
where $\bar h_{mn}$ is the trace-reverse ...
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2answers
100 views
What really is GW quanta?
I have read this question:
What is the difference between gravitons and gravitational waves?
where annav says:
So photons are the building blocks of light, and gravitons are (hopefully) the ...
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Tianqin project vs LISA
How does Tianqin space-based gravitational wave detector compare to LISA? Will it be able to detect gravitational waves from e.g. inflation (considering possible upgrades)?
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1answer
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Gravitons (real) passing through a black hole
This is not a duplicate. I do not ask about the gravitational field of the black hole, or why it extends farther out then the event horizon. I do understand that the gravitational field is described ...
3
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1answer
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Is there some Rindler-like horizon on this gravitational wave spacetime?
In the book Gravitation by Misner, Thorne & Wheeler (MTW), the authors present in section 35.9 "An Exact Plane-Wave Solution". The metric is
$$ds^2=L^2(e^{2\beta}dx^2+e^{-2\beta}dy^2)-dudv,\quad ...
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1answer
102 views
Superposition of gravitational waves and the dark energy
Is it theoretically possible to create a superposition of gravitational waves that form a locally static negative curvature, something like the dark energy?
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What happens in theory if we focus gravitational waves into a point?
https://www.youtube.com/watch?v=iWKFPTgkpXo
Basically inspired by this video and its comparison with wormholes.
While many other questions on the site have already covered the weak strength of ...
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1answer
103 views
Could a scientist use the internet to detect gravitational waves?
According to my understanding (I'm not a physicist just a fan), LIGO measures the changes in two path's lengths to detect gravitational waves by sending a particle down each path at the constant speed ...
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1answer
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Theoretical solution to binary black hole merger based on Hawking and Ellis
Following Hawking and Ellis, Chapter 9, Fig. 60, Pg. 322, the following figure is meant to illustrate the contrast between apparent horizons and event horizons in the case of a binary black hole ...
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1answer
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LIGO test masses in free fall
I know that the LIGO test masses are considered to be in free fall. However, they are supported by pendula. I thought that free fall means the only acting force is gravity - doesn't the tension in the ...
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1answer
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Can a system be engineered to cause a standing wave resonance with gravitational waves
Can a system be engineered to cause a standing wave resonance with gravitational waves?
It appears that gravity waves can be reflected.
Do Mirrors for Gravitational Waves Exist?
Stephen J. Minter, ...
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Signal parameter estimation in PyCBC
I have a gravitational wave signal (strain vs. time). And I want to find out the corresponding parameters of the compact binary. But I do not know how to create injection for this signal in PyCBC.
...
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Converting from trace reversed to standard metric perturbation
In linearised gravity, when dealing with gravitational waves it is common to consider just the spatial part of the trace-reversed metric perturbation $\bar{h}_{ij}$.
I know that in general the trace-...
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2answers
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Is the gravitational waves velocity also $c$, regardless the adopted inertial frame, and the source movement conditions? [duplicate]
The second postulate of STR was made exclusively for light (electromagnetic waves)?
If gravitational waves also travel at velocity $c$, then are they obliged to fulfill this second postulate?
Any ...
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Gravitational $N$-body mergers?
Beyond binary systems and its mergers, have numerical relativity groups computed an approximation to $N$-body GW signals/waveforms or is that a hard unsolved task?
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Why aren't gravitons spin 1?
Expressing the metric as $g_{\mu \nu} = \eta_{\mu \nu} + h_{\mu \nu}$, assuming $h_{mu \nu} \ll 1$ we can write the Einstein Hilbert action to leading order in $h_{\mu \nu}$ and quantize the ...
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1answer
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Is a body in passing gravitational wave still in free fall?
I have a simple apparatus: a box and inside it a test particle (small bullet). If the device is in inertial motion or affected only but (static) gravitational field of another massive body (in free ...
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Could the persistent effects of gravitational waves solve the black hole information paradox?
I am not bothered that much by the fact that two observers describe the same phenomenon differently. Something similar , in principle , happens with simultaneity in special relativity, and special ...
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Could two atomic clocks really be used to detect gravitational waves from a distant source? If so, how?
Three articles report on the recent paper in Phys Rev. D: Flanagan, Éanna É. et al. 2019 Persistent gravitational wave observables: General framework (also ArXiv):
Phys.org: Gravitational waves leave ...
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Could gravitational waves be the cause of inflation? [closed]
Ok, crazy idea time. Context: https://www.livescience.com/65441-gravitational-wave-memory.html
Quick lay summary: Apparently gravitational waves alter the structure of the space they pass through.
...
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How to convert from a tensor GW perturbation to a scalar one?
Typically the gravitational wave (GW) strain is calculated (e.g. by the Quadrupole formula) as some tensor object $h^{ij} (t)$.
However, I often read of the strain as some scalar time series, i.e. $h(...
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For a given chirp mass, how to decide between different binary systems?
Suppose we observe a gravitational wave with chirp mass $M$. How to decide between the different possibilities of BH mergers, NS-BH, WD-NS, WD-NS mergers? Can it be done with ONLY gravitational wave ...
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What does it mean to hear the gravitational waves?
In last few years, I watched a lot of YouTube videos claiming that gravitational waves can be and has been heard. They also play a short audio signal. How do experiments such as LIGO replicate the ...
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How do LIGO and Virgo know that a gravitational wave has its origin in a neutron star or a black hole?
It is being said that gravitational-wave detectors are now able to distinguish neutron star waves from those originating from black holes.
Two Questions:
How do LIGO and Virgo know that a ...
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5answers
118 views
In general relativity, is there a difference between matter-energy and spacetime?
This is the third time I try to formulate a question in a proper format so as to understand what is going on with gravitational waves at a physical level.
I am told that a spacetime oscillation and/...
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39 views
From a gravitational wave detector perspective, what is the difference between a gravitational wave and a phonon?
I already asked a question but it seemed that it was not precise enough. My problem is that I cannot see how gravitational waves have anything to do with spacetime. An EM wave or a phonon can put ...
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1answer
39 views
Does charging and discharging a capacitor create very small gravitational waves?
If I understand it correctly, curvature in a region of spacetime is due to concentration of energy and momentum in that region. If I further understand things (I don't) a gravitational wave is a ...
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Direct observation of Gravitational Waves via increased resolution
First, congrats to the event horizon team for the first photograph of a black hole.
Not to downplay the significance of the photo, but it is a bit blurry. Still, it got me thinking.
One might expect ...
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Is it possible to use the principle of EHT to build a virtual gravitational wave detector to detect very long wavelength gravitational waves?
The press conference of the EHT is fascinating. While there are some features such as the asymmetry in the ring that is to be followed up by the team, I was actually wondering, whether it is possible ...
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How much more precise would LIGO have to be?
The planets and a spinning black hole both drag their local frames and thus generate gravitational waves The amplitude should be proportional to the size of the celestial body, while the frequency of ...
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1answer
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Can expanding space stretch the wavelength of GWs? [duplicate]
I have read this question:
Redshifting of Light and the expansion of the universe
Now analogously, we could talk about GWs traveling in the empty voids of space, where the expansion of space is ...
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When space expands where do the energy of the gravitational wave dissipate to? [duplicate]
I think it is safe to say that gravitational wave do not dissipate unless it met matter along the way imparting some of it's energy to cause some distortion or when it's frequency is stretched even ...
