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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
92 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
158 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
65 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
108 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
78 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
57 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
82 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
196 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
56 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 ...
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0answers
71 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 ...
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1answer
51 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 ...
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2answers
2k views

Does the existence of “gravitational waves” (assuming they exist) imply that time exists as a 4th dimension in the universe? [closed]

I'm new to thinking about special and general relativity and I have no formal training as a physicist. However, I've been doing a bit of thinking about spacetime recently. I was wondering if "...
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2answers
105 views

Gravitational waves from an oscillating mass

If you drill a hole through the earth and drop a mass down it, it will oscillate back and forth as it moves through the hole from one end to the other. Does this motion create gravitational waves (I ...
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0answers
45 views

Do gravitational vawes deplete energy even if there's nothing they can affect?

I've read multiple times that one of consequences of gravitational waves being a thing is, that they make any orbit unstable. As long as the two or bodies orbit around each other, they create ...
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1answer
66 views

Gravitational Waves and LIGO [closed]

Last month, we as a species did something remarkable. We detected the presence of gravitational waves. While we all are celebrating and excited about the newest discovery of mankind. I could use ...
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0answers
49 views

Using geodesic deviation for freely falling particles when gravitational waves comes through

Suppose we have a gravitational wave which gives us the following metric $$ds^2=-dt^2+(1+h_+\cos(\omega(t-z)))dx^2+(1-h_+\cos(\omega(t-z)))dy^2+dz^2$$ I want to calculate the time it takes for a ...
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2answers
49 views

Gravitational waves: simulations of signal

I am self-learning GR. I was wondering if there is any open source software to help learn more about the signal processing of gravitational waves. E.g. a software that injects a signal into random ...
4
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1answer
138 views

If there is no speed limit on space-time compression, why do gravitational waves travel at light-speed?

From what I've read about spacetime and general relativity it seems there is no limit on how quickly space-time can be compressed or expanded. Why then gravitational waves are limited to light speed? ...
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2answers
80 views

What can and can't gravitational waves affect?

Owing to the relative weakness of gravity, I would have assumed that the gravitational waves detected by LIGO couldn't expand / contract the nuclei of atoms (governed by the strong interaction) or ...
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0answers
111 views

Did the LIGO measure gravitomagnetic waves as well?

I think of gravitomagnetism as as the "magnetic" portion of gravity, with gravity being the "electric" portion. Since gravity ("electric") seems to affect space (which the LIGO could detect) what ...
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2answers
123 views

How does the propagation of gravity work for photons?

As explained in the answers to this post, photons apparently exert a gravitational pull on other objects. It has also been explained on this site, that gravity propagates at the speed of light. I'm ...
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3answers
246 views

Two “devil's advocate” questions related to LIGO measurement results interpretation

"If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things." Rene Descartes Laymen like me typically refers to Wikipedia ...
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1answer
40 views

Since the horizon of a Nonstationary isolated black hole is a closed surface, how can gravitational waves be generated?

I understand this is from numerical calculations in GR. I have not seen them. Can anyone elucidate on what generates the GW waves - I know that deformities (anything moments higher than dipole) will ...
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1answer
34 views

Circular array of (4, 6 or 12) interferometers with circumferential end points for GW analysis?

If both or, at least, one of the two current LIGO installations instead of the single interferometer would have the circular array of (4, 6 or 12) interferometers (with circumferential locations of ...
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1answer
22 views

Time and frequency extremes

I wonder if there exists a table of which physical events have the shortest time scale (like matter/antimatter annihilation) and which have the longest (like proton decay). The same question applies ...
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1answer
42 views

light gravitational wave interaction

What happens when light photos and gravitation waves collide? Like can the photon "surf" on the gravitational wave and change direction, wavelength, velocity?
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1answer
69 views

LIGO detection: What do we know about the black hole system?

I would to know how much we can infer from the LIGO detection on the black hole system. I understand that at least the following can be verified: Spins Inclination Initial masses Final masses ...
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2answers
1k views

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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0answers
76 views

Non-locality of gravitational energy

Gravitational energy is non-local which is essentially because of the equivalence principle. The equivalence principle says that you can always transform your frame so that you feel like in a ...
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0answers
131 views

Do photons generate gravitational waves since they affect with their energy the stress tensor?

The gravitational waves are fact. They are produced in a way predicted 100 years before by Einstein. Anything with energy affecting stress tensor of space time produces them. What does it happen with ...
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3answers
215 views

Can we detect gravitational waves generated from inside the event horizon of a black hole? [duplicate]

General relativity prevents light from escaping a black hole, but does it also apply to gravitational waves?
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0answers
43 views

How can LIGO's measures be unequivocaly tied to gravitational waves? [duplicate]

I understand that there are 2 devices so that the signal cannot have a local stimulation as a source. But why couldn't it be seismic activity for instance? Given the accuracy of the devices couldn't ...
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0answers
64 views

LIGO detection statistic, SNR formula

According to B. P. Abbott paper published in Physical Review Letters, "Observation of Gravitational Waves from a Binary Black Hole Merger" http://journals.aps.org/prl/abstract/10.1103/PhysRevLett....
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1answer
114 views

What are gravitational waves relative to? [closed]

I have been having trouble picturing what kind of waves say Sun and Earth would make. Looking from top perspective Sun is in the middle and denting space while Earth is moving which is also denting ...
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0answers
43 views

How far gravitational waves like the ones recently detecty are dangerous for life? [duplicate]

I have read that gravitational waves can tear matter appart. I imagine you have to be fairly close to the event to be affected. Do we have a rough estimation of lethal distance ?
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1answer
94 views

Is there a path to go from GR, to Gravitational Waves, to Gravitational Particles (Gravitons), to Quantum Gravity?

The articles on the subject often say : a part of the mass of the 2 celestial bodies became energy for gravitational waves after merging : E(gravity waves) = (M1 + M2 - M_merged).c^2 Intuitively I ...
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0answers
38 views

Does the gravitational wave community plan to lower the threshold for claiming detections by 2000x?

I've read: To investigate the impact of reducing the parameter space for GRB searches, we will deliberately avoid the question of first gravitational wave detection - where a "5-sigma" ...
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0answers
13 views

How does gravitational waves interact with each other [duplicate]

With my limited knowledge in physics, I assume gravitational waves behave like the waves we know. If this assumption is true, how will they act when ripples go through each other? Will they cancel ...
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0answers
22 views

Gravitational Ripples [duplicate]

Recently the observance of Gravitational Ripples was reported using the LIGO detector. LIGO consists of two arms perpendicular to each other through which a split laser beam is passed and then ...
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0answers
64 views

Which formula was used to get Gravitational Waves animation?

I would like to make animation like this by myself It is from wikipedia article "Gravitational wave". But if I use formula from wikipedia article "Gravitational wave" subsection "7.2.2 Wave ...
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1answer
83 views

What field property may allow faster than $c$ speed?

What field property may allow faster than $c$ speed? Is there theoretical field or what property it needs to have to allow wave speed larger than $c$? What is the speed of the gravitational wave? Is ...
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3answers
118 views

Would the uncertainty principle apply to gravitational waves?

The uncertainty principle is one of the most basic rules of quantum mechanics, but Quantum mechanics still has not been unified with general relativity, so would the uncertainty principle apply to ...
2
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1answer
65 views

Gravitational waves induce changes in the $h_{00}$ (time) component of the metric?

I'm rather stumped by a subtle point regarding metric perturbations of GW. I'm well aware the GW are able to produce changes in the flat space metric, They are transverse and have planes of ...
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1answer
75 views

LIGO: Importance of photons

In LIGO, a photon beam travels in two perpendicular direction and time taken by each beam is noted. Non zero time difference is a signature of GWs here. What if I use electron beam travelling at ...
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0answers
64 views

Do gravitational waves contain actual energy and momentum? [closed]

Gravitational waves are waves in the fabric of space time and gravity is also caused by warped space time. So do gravitational waves contain actual energy and momentum?