Questions tagged [gravitational-waves]

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Does vacuum affect gravitational force?

My question is that does a vacuum affect the strength of gravitational force? If yes then how it is affected? And if no then why it is not affected? In perfect vacuum there is no particle in the ...
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What causes the 20 second period in LIGO data?

I download LIGO data on GW150914 (gravitational waves) via the code in Mathematica ...
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Damhsa Theory: Can gravitational waves really affect the long term climatic evolution of Earth?

As a glaciologist I'm often involved in topics related to the long-term climatic evolution of Earth, and to the factors that can trigger or end ice ages. Recently, I came across the paper "Applying ...
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Gravitational Potential Energy irony

While calculating potential energy of an object with respect to Earth which equals work done to bring it from infinity to that point. The gravitational force and displacement are in same direction, ...
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Is a seismic gravity perturbation a gravitational wave?

Powerful enough earthquakes generate gravity perturbations that propagate at $c$ and can be detected by sensitive enough seismographers. See, e.g., this news in Nature: In the latest paper, Vallée ...
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Attributing Gravitational waves to a source

At a given time, there would be n number of binary neutron stars or Black Holes or even Super Novae, all of which would be leaving a gravitational wave imprint ..So how do LIGO scientists know which ...
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If two black hole mergers happen close enough would there be any interesting effects due to their waves constructive and destructively interfering?

If two pairs of black holes were to merge at the same time in the same plane within close proximity (small odds) what effects could be observed due to their waves constructively and destructively ...
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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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What causes primordial gravitational wave in the early universe?

Is it collision between primordial black holes or perhaps big bang itself, I read that if we can observe very first polarized light e.g. CMBR etc then inflation theory is proven. So my question is ...
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Classical mechanics gravitational waves

Would there be gravitational waves even if general relativity was wrong? For example imagine there was a theory of gravity that was consistent with special relativity. How different could ...
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Hulse-Taylor binary data gap in the nineties

I was wondering what is the reason there are no data points in the famous Hulse-Taylor plot of the period decay in the 1990s. Does anyone know why no one collected data during this period?
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Why is the Ricci scalar non-zero in this case?

The Einstein equations can be written as (1): $$R_{ab}-\frac{1}{2}Rg_{ab} = -8\pi GT_{ab}$$ or by contracting the above equation with the metric tensor and resubstituting: (2) $$R_{ab}=8\pi G(\frac{1}...
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Could a powerful gravitational wave cause electrons to emit light?

I imagine electrons being accelerated by passing gravitational waves, say from a nearby kilonova, so I would expect the electrons to emit light. Am I right?
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Stochastic versus primordial gravitational waves

I have read differences terms but I doubt if they are exactly the same in Cosmology: Primordial gravitational waves (and their background). Stochastic gravitational waves (and their background). ...
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Redshift z=40 and gravitational waves

Why z=40 is the critical value of the redshift (more or less) to decide find out primordial gravitational waves around it? I have read that is related to the following issue: black hole mergers ...
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Does the existence (now proved) of gravitational waves imply the existence of Gravitons?

I studied the theoretical part about the Gravitational waves in General Relativity (linearization of gravity and small perturbations of the metric and so on). But I was wondering about: since ...
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Why gravitational waves are not produced by objects moving at constant velocity?

Gravitational wave is produced by change in gravitational field, source. If something is moving away from me at constant speed, its gravitational field will vary. But why only accelerating bodies ...
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Neutron Stars of unequal mass merging

Is the difference in masses between merging Neutron Stars the cause of the massive gravitational disturbances due to the unbalanced decaying orbit right before the merger?
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How does a neutron star collision turn mass into gravitational waves?

I heard on the TED Radio hour that in the neutron star collision that LIGO recently detected, some of the mass of the neutron stars was turned into energy in the form of gravitational waves. How does ...
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Detection of gravitational waves and the expansion of the universe

Very recently, there was the fascinating news of new measurements being done by LIGO, in this case detecting the gravitational waves of two Neutron stars colliding. These detections prompted the ...
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Gravitational Waves + impedance

Why isn't there an Impedance with gravitational waves? http://www.scientificamerican.com/video/gravitational-waves-are-the-ringing-of-spacetime/
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How to show that the polarization tensor of the gravitational plane wave in vacuum is transverse

This is Ta-Pei Cheng's book p.254. I am trying to understand (13.28). The Lorentz gauge condition (13.18) is like below. How can I use the (13.18) condition to show (13.28)? I am trying to calculate ...
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Gravitational waves frequency

When people quote the discovery of gravitational waves no reference seems to be made to the frequency, presumably this is about the current state of detectors. Or are the frequencies detected the ...
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Why people think dark matter as a massive particle? Couldn't it be gravitational waves?

Dark matter is said to be present in the galaxies which helped galaxies to exist in the first place forming the glue to attach all the matter in the galaxies. Given that dark matter never been seen ...
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Gravitational waves' path and interaction with black holes

As a gravitational wave propagates away from its source, how does its path get affected if a black hole is in its way? I was trying to picture it visually and here was my 'before' (with the line being ...
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1answer
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Could LIGO have detected R'lyeh if it existed?

In Possible Bubbles of Spacetime Curvature in the South Pacific, that R'lyeh might be exist within a bubble of spacetime. (It appears to be a joke paper since some of the references are fictional, but ...
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Observation of Hawking radiation

Is it conceivable that Hawking radiation could be observed using e.g. gravitational waves or imprints in the CMB?
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Gravitational waves detector orientation

For a wave of the form, say, $$ ds^2 = -dt^2 + [1 - A\sin(\omega(t-z))]dx^2 + [1 + A\sin(\omega(t-z))]dy^2 + dz^2$$ how should one orient the detector (that works by monitoring the distance between ...
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Difference in Gravitational Waveforms for different objects?

This is an extension of one of my older questions: How would the gravitational strain waveform look like for a planet in orbit with a star? Let's say at some distance D there are two objects which ...
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Why is it correct to conceptualize LIGO's mirrors as “test masses?”

In the LIGO paper on the first detection of gravitational waves, they have a diagram of one of the interferometers in which they label the mirrors with the conceptual label of "test masses." The ...
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Primordial Black Holes mass diference with isomass stellar black holes

How can we distinguish, for a given mass (measured from gravitational waves experiments and or other experiments) of a black hole or black hole binary, if they are PRIMORDIAL or they are stellar black ...
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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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Why are non-relativistic methods used in binary pulsar systems (gravitational waves)?

Although gravitational waves are a subject of the General Relativity, why do most books use Newtonian equations of motion for power radiated and rate of change of eccentricity calculations? In most ...
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Black hole hair, gravitational wave emission, and information, from outside observer

I have a few conceptual puzzles that I cannot see my way through. Time and again, I've read that from the point of view of a static outside observer, infalling matter just reaches a black hole's event ...
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Why there is no dipole gravitational wave?

I have read that "thanks to conservation of momentum" there is no dipole gravitational radiation. I am confused about this, since I cannot see the difference with e.m. radiation. Is this due to the ...
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Why does gravity travel at the speed of light?

In electromagnetism, Maxwell's equations predict that electromagnetic disturbances travel at the speed $$c = \frac{1}{\sqrt{\mu_0 \epsilon_0}}.$$ Does general relativity predict that gravitational ...
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Does special relativity apply to gravity wells?

If the gravity well of a non-rotating heavy object is in roughly the same inertial frame as an observer, its spacetime geometry (as measured e.g. by photon lensing) will present as spherically ...
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Does an object creates gravitational waves when only accelerating in one direction?

I know from reading about the gravitational waves detected by Ligo, that when an object has angular acceleration, it produces gravitational waves. I'm wondering if an object creates gravitational ...
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Could gravitational waves be matter waves?

Pretty straightforward. The idea of 3 solar masses radiating away as gravitational waves is still troubling to me. I don't understand how matter can be converted into 'gravitational energy'. I can ...
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GW170817 optical and infrared light

I'm reading about GW170817 in various research articles. One of them, The X-ray counterpart to the gravitational-wave event GW170817. E. Troja et al. Nature 551, 71 (2017), arXiv:1710.05433 ...
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Could (old) LIGO have detected GW150914?

The merging black hole binary system GW150914 was detected in only 16 days of aLIGO data at a signal level that appears to be well above the detection threshold at around 5 sigma. There are no further ...
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Effect of Gravitational Waves on light?

We all know about the gravitational lensing effect. From the analogy of fabric of space time used to explain this concept to laymen like me, I understand that light follows the curvature of spacetime. ...
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Data for speed of gravitional wave

By the distance of the two LIGO detectors and the time delay for the same gravitational wave(GW) event, the speed of GW can be determined. guys, do you know where can I find related data?
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How to generate numerical relative waveforms representing gravitational wave strain for different masses?

I have read in many sources that Numerical relativity produces a general solution for the waveforms which are to be expected by LIGO data to identify the different masses which are observed . Can ...
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LIGO Gravitational Waves [closed]

Has LIGO detected any gravitational waves yet, or any hints of them? Is it just that LIGO is not sensitive enough or are we now entering disconfirmation territory? If we never detect gravitational ...
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Would it be possible to transmit information through gravitational waves?

First thing I've been wondering is how the gravitational field is emitted. Matter emits gravitational waves, and I guess that those waves travel at around the speed of light. If that's not the case, ...
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What information can we know by LIGO's detection of gravitational waves?

LIGO's detection of gravitational waves can help estimate Hubble's constant in a new way. Another paper might be informative. Apart from that what information can we get from the observed ...
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Kerr BH effects on inspiral binaries

In the gravitational wave calculation for binary systems: what is the effect of rotation of two BH (or neutron stars, BH-NS,...) on the usual calculations? Is there any EXACT result known?
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Tetrad formalism in linearized gravity

I have not seen so far any application of linearized gravity treated using the local orthonormal frame approach. Stuff, such as newtonian limit, gravitational waves, etc. I can totally see the tetrad ...