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21 views

Why do LIGO use a quarter wavelength for detecting gravitational waves?

I have already researched into this and I am left slightly confused still. I have gathered that the use of a quarter wavelength is to turn a linearly polarised wave into a circularly polarised wave. ...
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1answer
46 views

Could gravitational waves have a large entropy in quantum gravity?

The question is broad, and we still don't know what is quantum gravity. But let me be more specific. In the question (on this site, see below) on whether gravitational waves have entropy the answers ...
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1answer
96 views

Gravitational wave and string theory

I'm new to physics and have been reading about fundamental and textbook physics text, which is the Young & Freedman University Physics (good book). I'm little skeptical towards string theory as ...
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2answers
138 views

Do gravitational waves have entropy?

We know, according the current understanding of black holes and General Relativity, as well as quantum fields in General Relativity, that black holes have an entropy proportional to the area of the ...
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0answers
21 views

LIGO Gravitational Wave Discovery and Gravitons [duplicate]

Now that gravitational waves have been detected, how hard will it be to detect a graviton? Will the equipment have to be more sensitive or are the difficulties more complicated than that?
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1answer
58 views

Do gravitational waves radiate isotropically?

Do gravitational waves radiate equally in all directions? If so, is this an inherent property of all gravitational waves or is it just due to how they are normally produced? In other words, in a ...
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1answer
27 views

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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1answer
49 views

At what rate do gravitational waves lose energy and amplitude?

Part 1: How do gravitational waves decay with distance? My Newtonian instincts tell me that gravitational waves would likely decay in the same way that Newtonian gravity decays, but at this point ...
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1answer
25 views

scaling law of gravitational waves and consequences

With which power law of distance is decreasing the amplitude of the distortion caused by a gravitational wave ? $r^{-1}$ ? $r^{-2}$ ? something else ? -> The coalescence between 2 black holes about a ...
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2answers
74 views

Speed of gravitational waves and light

We all know that speed of gravitational waves (GW) and that of light in space are exactly the same (= $c$). We also know that space is medium for GW. Does that mean space is also the medium for ...
2
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1answer
59 views

Gravitational waves and it's interaction with matter

I have been reading an article on gravitational waves here. There, it is written that the gravitational wave, unlike the electromagnetic waves, interact very weakly with matter. The principle of LIGO ...
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0answers
24 views

Gravitational waves' Amplitude

Gravitational waves are disturbances in gravitational field which in turn is the curvature of space-time. So my question is it possible to somehow measure the amplitude of a gravitational wave and if ...
3
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0answers
101 views

Do gravitational waves propagate backwards in time?

Gravitational waves are spacetime waves, which stretch and squeeze both space and time. Since relativity puts space and time (almost) on an equal footing, it seems to me that since gravitational waves ...
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0answers
30 views

How does one derive Christodoulou Memory Effect?

There is a non-linear effect associated to the permanent displacement of test masses when a gravitational wave interact with them. This is called the Christodoulou memory effect. How does one obtain ...
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3answers
652 views

Speed of gravitational waves vs speed of light

I own an educational YouTube channel on physics and astronomy. I am currently working on a gravitational waves video extension to my "How Fast Is It" video book on relativity theory. I have a question ...
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0answers
32 views

Can I send a message to a far away friend by means of gravity? [duplicate]

Suppose a friend of mine is somewhere on Mars. Can I send him a message (for example that his father died) by means of gravity?
3
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0answers
35 views

Is there high ring-down frequencies in LIGO's recent discovery?

This question is from Physics overflow: question in physicsoverflow. I am reading LIGO's new discovery of gravitational waves by black hole merger. During the merger, two phases are not hard to ...
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1answer
41 views

Can gravitational waves interfere polarize or show any other properties of stndard waves

Is it possible for gravitational waves to be able to produce phenomenon such as interference and polarization etc. which are observed in standard waves. Also is it possible for gravitational waves to ...
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2answers
66 views

Why are they building eLISA and what implications would it have?

I understand that the next step after LIGO is to plan and build eLISA, I understand that out in space there are a lot less interferences compared to Earth which makes it a good way to detect things we ...
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0answers
84 views

Gravity vs Gravitational Waves

I thought I had a reasonable understanding of relativity, the speed of light speed limit, and how this stuff related to gravity. Then I read through all the answers/comments for this question: How ...
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1answer
62 views

Gravitational wave equations worked out

Is there a website where gravitational wave equations are worked out numerically? I would like to experiment with mass configurations but can't find examples.
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0answers
26 views

Non equilibrium black hole radiating away energy and angular momentum, with total energy and angular momentum conserved

The question refers to whether mass (i.e., energy) and angular momentum can be considered to have been carried away by the gravitational radiation in the hole settling down. And whether those entities ...
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1answer
91 views

Gravitational waves from neutron star - neutron star merger

How is neutron star-neutron star merger different from Black Hole-Black Hole merger and what information can be extracted from gravitational waves emitted by these processes?
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2answers
108 views

A spin zero graviton?

Why can the graviton not be a spin 0 particle? On a similar note why can it not be a spin 4, spin 6 particle?
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10answers
11k views

How does Zumberge's 1981 gravitational measurements relate to gravitational waves?

Gravitational waves were discovered 35 years ago without fanfare in 1981/2 by Zumberge, R L Rinker and J E Faller, then completely ignored. See: "A Portable Apparatus for Absolute Measurements of ...
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2answers
596 views

Producing gravitational waves in labs

Can gravitational waves be created on very small region of vacuum with quadruple movement of atom or subatomic particles?
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0answers
17 views

Why is graviton not found yet? [duplicate]

Why is graviton not found yet? Newton said gravity pulls us, Einstein said space is bent and it pushes us, hawking predicts the existence of graviton and 'hawking radiation'. How far are we from ...
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1answer
73 views

Do Gravitational Waves disprove superluminal Alcubierre drive?

I am not a physicist. But... does the rate at which gravitational waves travel set an upper limit to the "speed" of a ship propelled with Alcubierre drive? Or does it present a relativistic trick ...
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3answers
141 views

Do gravitational waves affect light?

Gravity "bends" light, predicted with theory of relativity and subsequently observed: how does gravity and gravitational waves achieve this effect, and shouldn't this effect be present wherever ...
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0answers
24 views

Why '1+log slicing condition' and 'Gamma Driver Shift Condition' were successful in black hole simulations?

The 1+log slicing and Gamma driver shift conditions are I want to know if there is a specific reason why these conditions were used most for Black Hole simulations in Numerical Relativty. And how ...
2
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1answer
77 views

Why does the 'sticky bead argument' for (gravitational waves carrying energy) work?

Throughout much of the 20th century there was debate about whether Gravitational Waves were real, and whether or not they carrier energy and could be detected. It is often presented that Feynman's ...
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0answers
42 views

Can Bose-Einstein Condensates reflect gravitational waves?

This is a question based on the paper by Raymond Chiao in 2002 where it is stated: One of the conceptual tensions between quantum mechanics (QM) and general relativity (GR) arises from the clash ...
3
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0answers
42 views

Can gravitational waves observed far from a black hole tell us anything about the multipole moments of a dynamical horizon?

In a paper by Ashtekar et al in 2013 on the approach to the final state to a stationary black hole they study the evolution of the multipole moments of dynamical horizons, which relax away (except for ...
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1answer
26 views

How would be effect gravitational field of an accelerated object?

We have a mass in space and it is accelerating until 0.7C (which gives it nearly 50% mass equivalence in momentum.) I'd like to hope to understand the changes in gravitational fields after ...
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0answers
23 views

shouldn't a photon traversing the vacuum always be associated with a gravitational wave?

In perusing the linearized Einstein equation, it appears that even a classical electromagnetic plane wave would always have to be associated with a tensor perturbation to the background spacetime. ...
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2answers
87 views

Can gravitational waves diffract off massive objects?

Can gravitational waves diffract off massive objects? If so, how much mass is needed to significantly disturb the waves propagation?
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3answers
2k views

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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1answer
44 views

Could it in theory be possible to produce AM and FM gravitational waves?

I'm borrowing the concept of a radio and having fun with space-time, my argument is that since gravitational wave have amplitude and frequency it is very much similar to electromagnetic wave such as ...
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1answer
152 views

What would happen if a gravitational wave hit me?

What would happen if a gravitational wave hits me? Will it affect me or will something else happen?
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2answers
64 views

What did we learn by detecting a gravitational wave? [duplicate]

In February 2016 the LIGO team announced that they had detected gravitational waves on 14 September 2015. As far as I know, we already knew that gravity propagates at the speed of light. So two black ...
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1answer
107 views

Do gravitational waves travelling through a medium produce sound?

Say Alice decided to orbit dangerously close to a couple of black holes circling each other. She is in a heavily enclosed astronaut suit, as is Bob, who is floating much further away. Assuming Alice ...
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1answer
69 views

If we could perfectly control gravitational waves, could we play music with them? [closed]

Sound is just a kinetic wave propagating through a medium, right? In that case, if we had the ability to make gravitational waves exactly as we want them, could we play music to an observer some ...
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1answer
55 views

Can gravitational wave be blue/red shifted?

I'm picturing a simple scenario: 2 black holes about to merge and they are receding away from us at constant speed. (I like to negate the rate of expansion of space and assume universe is perfectly ...
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2answers
76 views

If gravitons are 'real' and analogous to photons are they also being 'stretched' by the universe's expansion?

Since photon wavelengths are stretched by our expanding universe, appearing to us as a redshift, would graviton wavelengths similarly be stretched? For that matter, do gravitons even have a ...
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2answers
186 views

If space can expand faster than light why can't gravitational wave?

I heard that gravitational wave is the measure of stretchiness of space time, so since there is no limit to how fast space can stretch what about gravitational wave?
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1answer
55 views

Classical gravitational waves, again [duplicate]

I'm basically duplicating this question, because I'm not satisfied with the answer. Here's why I'm not satisfied. If we know that "gravity travels at a finite speed", then it seems obvious that it ...
0
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0answers
69 views

What is the explicit form of $\tau^{\alpha\beta}$ in the linearized Einstein field equations $\Box h^{\alpha\beta}=-16\pi\tau^{\alpha\beta}$?

If we let $h^{\alpha\beta}=\eta^{\alpha\beta}-g^{\alpha\beta}\sqrt{|det(g)|}$ then, according to wikipedia, the Einstein Field Equations become $$\Box h^{\alpha\beta}=-16\pi\tau^{\alpha\beta},$$ where ...
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7answers
5k views

What are gravitational waves made of?

The following facts are what I think I know about gravitational waves: Distortion of space-time moving away from a source at light speed. Produced by very powerful event in the universe such as ...
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2answers
2k views

The LIGO Gravitational Wave Detection: have deep-mantle earthquakes been ruled out? [duplicate]

Everywhere I've looked so far that talks about the possibility the LIGO detection was an earthquake, involves being ruled out due to the large distance between the two LIGO sites. Two identical ...
0
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1answer
47 views

The LIGO Gravitational Wave Detection: How frequent in the observable universe? [duplicate]

The currently detectable interval of black hole mergers is on the order of seconds or fractions of seconds. So each black hole merger, no matter how long the end to end process, is only detectable by ...