# Questions tagged [gravitational-wave-detectors]

A gravitational wave detector is an instrument built for the purpose of direct detection of gravitational waves, most notably, LIGO, Virgo, and the future space-based detector LISA.

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### Reduced mass vs. Total mass in gravitational wave estimations

When people do back of the envelope calculations about GW physics, they always use a very abstract mass scale $M$ and I want to figure out the identity of said scale for different relevant magnitudes ...
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### Can either of LISA, NanoGrav or LIGO measure the polarization of gravitational wave background (GWB)?

Polarization in GWB should carry as much important information as in CMB. However, I've done some superfluous literature research and found little discussion. Is there any planned project for ...
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### What type of detail and imaging might we be able to achieve with mature gravitational wave detector arrays?

With the success of LIGO and considering the types of imaging we're able to do with distributed arrays of radio telescopes, what level of detail would we be able to achieve were we to build arrays of ...
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### Detecting gravitational wave polarization

We know that in TT gauge frame the gravitational wave has two polarization components, and the actual gravitational wave we are detecting is a linear combination of those two states , now a natural ...
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### What is a complete book for Gravitational Wave Detectors

I would like to find textbook/lecture notes which include the following: explain how gravitational waves are produced the physical principles underlying detectors of gravitational waves (particulary ...
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### What is the significance of a constant, $C$ in a damped cosine function? [closed]

I've used to fit some scattered points by an equation of damped cosine with a constant function ($(A\cos({kx})+C)e^{-Bx}$) and that equation fits better than only a damped cosine $A\cos({kx})e^{-Bx}$, ...
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### Gravitational Waves - Are all detectors finding the same gravitational waves?

I read that there have been approximately 90 recorded cases of gravitational waves. Have the 4 different gravitational wave detectors agreed on specific individual recordings or have all 90 cases been ...
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### Searching for an "intuitive" explanation about how gravitational waves can be detected by a laser interferometer like LIGO

Since LIGO's first detection of gravitational waves, I have been searching for an intuitive way -as long as intuition can be useful in relativity, which often it isn't- to understand how the detector ...
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### LIGO et al: Is it possible to estimate the frequency of GW+EM detections?

In the past few years LIGO and VIRGO have detected a multitude of gravitational events. As far as I know however only GW170817 had a verifiable EM counterpart. Shouldn't it be possible, based on ...
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### How can we calculate formula for effective coupling constant in spin independent direct detection of dark matter?

At tree level, the spin independent (SI) direct-detection cross section includes effective coupling constant. How to calculate effective coupling constant? There is always a mandelstram variable in it....
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### Claims of detection of gravitational waves with an accelerometer

Is this claim: https://earthscience.stackexchange.com/q/21236/ of detection of gravitational waves with accelerometers legitimate? I do not know much about this, but given how gravitational waves form ...
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### Could LIGO detect an Alcubierre drive being used within 10 light-years of the Solar system? [closed]

Maybe this question is too speculative... But is it possible that LIGO would detect the ramp-up and ramp-down of an Alcubierre drive being used within 10 light-years of the Solar system? Also, if the ...
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### How does LIGO work?

LIGO is described as working as an interferometer, like a Michelson-Morley interferometer but with many reflections along the arms to increase the sensitivity. In MMs work it was assumed that the ...
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### Why gravitational waves are hard to detect?

I just started to learn general theory of relativity by Hartle's gravity textbook. In a section on gravitational wave I encountered following statement 'Gravitational waves are hard to detect due to ...
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### The detection of gravitational waves and the assumption that gravity travels at the speed of light

I read from this wikipedia article that we have obtained some empirical evidence that gives us an upper bound on the difference between the speed of light and the speed of gravitational waves. What I ...
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### Gravitational Wave detection [closed]

Does the detection of Gravitational Waves provide any significant headway into concretely answering as to what exactly is causing the arms of the interferometer to move or even why should they move at ...
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### Is it true that speed of gravity was confirmed in 2017?

I was reading a Wikipedia article on speed of gravity, https://en.wikipedia.org/wiki/Speed_of_gravity . The following quote is taken from the mentioned article. In the relativistic sense, the "...
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### Tidal effect on interferometry

Interferometry relies on the change in the phase of two orthogonal light beams reflected back to the source point. Assume there is an interferometer at the equator, one mirror is planted 1 mile due ...
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### Paper about signal-to-noise ratio for LIGO/VIRGO

I am looking for a recent paper in which the signal-to-noise ratio for the ground based advanced LIGO/VIRGO interferometers is discussed, on the same line of this paper (dated 2006 by E. Berti et al.) ...
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### Cosmic microwave background polarization and detecting primordial gravitational waves

I have a few questions about primordial gravitation waves What are primordial gravitational waves? Wikipedia says that they are observed in the cosmic microwave background (CMB), but gravitational ...
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### Difference between gravitational wave detectors

There are a lot of different gravitational wave detectors and they all have their own wave period and frequency they operate at. This picture shows that The last three (pulsar timing, space ...
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### How to interprete the gravitational wave measurement?

I saw this picture: the LIGO measurements of a gravitational wave. I have a few questions about the graphs. First the graph with residual, what does that mean? If the data of Hanford is projected on ...
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### Could gravitational wave detectors be used for other purposes than gravitational wave detection?

Gravitational wave detectors like LIGO are very sensitive machines, and I wonder whether they could be (or actually are) used for other detections. What comes into mind is: Earth science: The ...
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### Is there a way to detect gravitational waves in subatomic particles?

Consider the hypothetical situation of two electrons orbiting each other with a certain radius between them, going at extremely high speeds. Would this create gravitational waves strong enough to be ...
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### Sidebands, cavity tuning and detection in interferometric gravitational wave detectors

I know the basics of gravitational wave detection but struggle to put things together and view the whole picture of the signal path. Most of my knowledge refers to second generation gravitational wave ...
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### 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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### 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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### 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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### Can the vibrations from the Earth affect gravitational wave detectors?

I was very interested in gravitational wave detectors and how they work exactly. From what I know they set up two lasers with mirrors set up to cancel each other out. Then if movement is detected from ...
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### Pendulum usage in gravitational wave detectors

I've read that pendulums are (or were) used to calibrate the distance between the mirrors in a gravitational wave detector. In principle pendulums are supposed to be moving in just one plane no matter ...
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### Could LIGO detect two simultaneous gravitational waves?

Hypothetically if two (or more) gravitational waves were passing through the LIGO detector at the same instant, can the LIGO team deduce from the data that there were two simultaneous waves passing? ...
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### Is it possible that the LIGO results are anomalies? [duplicate]

Since it was reported recently that the supermassive black holes at the centres of galaxies may in fact be as many as 20,000 smaller black holes I wondered if, if these black holes collide with one ...
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### Sudden doubt about the principle behind Gravitational waves detection

From Wikipedia: "Feynman’s gravitational wave detector: It is simply two beads sliding freely (but with a small amount of friction) on a rigid rod. As the wave passes over the rod, atomic forces ...
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### Will gravitational wave detectors be able to locate black hole collisions in time to view them?

Can a single LIGO identify the general direction of a black hole collision? Could multiple observatories be able to accurately pinpoint the direction from them so that telescopes could quickly point ...
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### Why did we take so long to directly detect gravitational waves?

According to this article, "Gravitational waves, Einstein’s ripples in spacetime, spotted for first time", the search for gravitational waves was beset by continual failures. Even the LIGO took a ...
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### Dark matter and LIGO

In addition to the functioning LIGO detectors (two in USA and one in Italy), I am aware there are some gravitation wave detectors under construction. More detectors should provide more statistical ...
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### Can curved spacetime be detected by an experiment at home?

Can curved spacetime be detected by an experiment at home? I am an educator and trying to find out experiments that can be used to prove curved spacetime, perhaps by reverse engineering any of the ...
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### Have gravitational waves any effect on the electromagnetic waves in interferometers?

I am not into general relativity, but the explanation of how an interferometric gravitational antenna works is generally pretty basic. In the recently published paper announcing the detection of ...
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### How well can we localize gravitational wave sources?

A recent question cited a story about the recent gravitational wave detection saying that we can use the gravitational wave sensing to find supernova earlier in their process of collapse: [with the ...
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### Is the sensitivity of the LIGO sensitive enough to measure the "expansion of the universe"? What specifically is the numerical ratio of effects?

It would seem that LIGO measures wibbles in the metric (not manifold) of spacetime: How is it that distortions in space can be measured as distances? It would seem that the expansion of the universe ...
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### Why do detectors for gravitational waves have only two perpendicular arms, not three?

I wonder why detectors for gravitational waves have only two perpendicular arms, not three. Having three arms appears to allow for better detection of direction, or may even increase sensitivity (I ...
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### How were gravitational waves discovered? [duplicate]

It was announced today that gravitational waves were discovered. The article gives the following explanation of the experiment: When a gravitational wave passes LIGO, the tunnels deform slightly ...
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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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