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13
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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
votes
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 ...
6
votes
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 ...
0
votes
2answers
101 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 ...
3
votes
0answers
44 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 ...
1
vote
1answer
62 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 ...
1
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0answers
48 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 ...
2
votes
0answers
27 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
votes
1answer
113 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? ...
1
vote
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 ...
0
votes
0answers
108 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 ...
5
votes
2answers
106 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 ...
0
votes
3answers
223 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 ...
0
votes
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 ...
0
votes
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 ...
0
votes
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 ...
1
vote
1answer
39 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?
1
vote
1answer
64 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 ...
18
votes
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 ...
2
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0answers
75 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 ...
7
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0answers
126 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 ...
7
votes
3answers
198 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?
0
votes
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 ...
1
vote
0answers
55 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" ...
1
vote
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 ...
0
votes
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 ?
3
votes
1answer
92 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 ...
0
votes
0answers
36 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" ...
0
votes
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 ...
0
votes
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 ...
0
votes
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 ...
0
votes
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 ...
1
vote
3answers
112 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
votes
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 ...
1
vote
1answer
70 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 ...
1
vote
0answers
62 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?
1
vote
0answers
62 views

Gravitational Waves + impedance

Why isn't there an Impedance with gravitational waves? http://www.scientificamerican.com/video/gravitational-waves-are-the-ringing-of-spacetime/
1
vote
1answer
57 views

Turbulence in gravitational waves

I want to understand physical meaning and possible implications of few terms often used in physics specially with regards to gravitational waves / space-time fabric Space-time fabric is disturbed by ...
1
vote
1answer
81 views

Neutrinos are slower than gravitational waves according to their mass?

Neutrino bursts are observed before the visible light of supernovas, most famously SN 1987A. Astronomers likewise expect gravitational waves. Gravitational waves are supposed to travel at exactly the ...
0
votes
1answer
29 views

How is light used to measure the change in time caused by gravity?

Is the following analogy correct, if not- what changes are necessary to correct it? Let's consider a guy riding on a photon with a clock, and every time his clock ticks he paints a dot. Let's also ...
1
vote
2answers
92 views

How does some of the black hole (BH) mass escape the event horizon (EH) of either BH, or the merged EH of two merged BHs?

BH mass is a conserved quantity and cannot escape the horizon of a BH. Yet in mergers some percent (in GW150914 it was about 5 percent, or 3 solar masses) of the binary's mass escaped either before ...
6
votes
3answers
226 views

Meaning of $5.1\sigma$ significance with regards to GW150914

I couldn't find any publication by LIGO that explains how we should interpret this value. The closest I have found is the following quote: This means that a noise event mimicking GW150914 would be ...
2
votes
2answers
79 views

How does gravitational wave compress space time?

My question came from the talk of how gravitational wave stretches and compresses space time. Say there are two protons that are 1 centimeters apart, as a G-wave passes through them, would the ...
1
vote
1answer
58 views

Vibrating black holes

From http://ligo.org/science/Publication-S5S6RD/index.php "Every star in the universe vibrates or oscillates in some manner. Turbulence on the surface of the Sun causes well-known solar oscillations ...
0
votes
1answer
87 views

Gravitational waves veracity? [closed]

W/r to the recent announcement of gravitational wave detection, since the signal to noise ration appears to be about 3 to 1 (not really very good) and there is no collaborating evidence from neutrino ...
1
vote
2answers
204 views

Why does LIGO have an arm length of few kilometers? Is the distance dependent on Gravitational Wave wavelength?

Antennas for capturing radio waves need to have $\frac{\lambda}{2}$ length for optimum reception of signal. Does it imply LIGO arm length is $\frac{\lambda}{2}$ of Gravitational Wave it is trying to ...
1
vote
2answers
93 views

About the working of LIGO [closed]

How is it that the gravitational wave occurred exactly so as to compress one tunnel and expand the other one( as is inferred from the explanations they Caltech gives)? Or is LIGO built in a way that ...
4
votes
1answer
109 views

What was the rate of Black Hole - Black Hole mergers expected to be detected by LIGO prior to GW150914?

My question is a more detailed version of the one found here, which elicited some good information but the question was never really answered. From table 4 in a 2010 paper we see the estimated rate ...
0
votes
0answers
62 views

Do gravitational waves have field components like electromagnetic waves?

One way I've been led to understand electromagnetic waves (and I accept that this might be a misconception I have) is that they 'self propagate' through empty space by virtue of the wave consisting of ...
-12
votes
1answer
230 views

Could the September 2015 LIGO gravity wave “detection” from “merging black holes” be fake? [closed]

The following Physical Review D article gives reasonable bounds for gravitational wave detection for Supernova core collapse. These bounds cannot be overwhelmingly different from the bounds on GW ...