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How does the $4$Km arms of LIGO measured so accurately?

The arms of the LIGO interferometer are $4$ Km long.Now,LIGO functions by measuring phase difference between two beams of light comming (as in Michaelson's Interferometer) to a sensitivity of ...
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1answer
17 views

Is there a “CGBR”?

The recent discovery by the LIGO made me wonder about this. We know that there exists a CMBR, Cosmic Microwave Background Radiation, a blanket of electromagnetic energy covering the universe, made by ...
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2answers
19 views

Gravitational Wave Impact

What would we see and feel if the waves were powerful enough? Do the waves influence whatever they pass through like a pressure wave would? Or would they be more transparent to the subject there ...
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38 views

Two naive questions about gravitational waves

My understanding of GW is that they ripple the fabric of the space-time just as accelerating charged particle emits electromagnetic radiation, accelerating massive objects produce gravitational ...
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23 views

Gravitational waves in other dimensions

I know this question is purely speculative, as we don't know if more dimensions do exist and also we do not know if gravity is indeed stronger in other dimensions (if they were to exist). But, one of ...
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1answer
34 views

What effect would GW150914 have had over a much shorter distance? [duplicate]

In the wake of the recent news of the confirmation of the existence on gravity waves, I was discussing gravitational waves with a friend, and he asked whether this could potentially lead to some kind ...
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24 views

How LIGO is calibrated?

I think I have understood properly the principle of LIGO, however the sensitivty is around $10^{-18}m$ of accuracy of distorion. That looks pretty small... just starting with simpler phenomena, for ...
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1answer
68 views

LIGO may have inadvertently detected the helioseismic burst from the Sun on 14 September 2015

Here is a quote from an online article: "A gust is on the way. NOAA forecasters expect a stream of high-speed solar wind to reach Earth on Sept. 14th-15th, sparking renewed displays of high-latitude ...
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1answer
71 views

How did the scientists know two black holes collided 1.3 billion years ago?

I saw a TEDx talk the previous day about the LIGO experiment and in that video he said they are waiting for the day Jan 1st 2017 for the Ripple in Gravity caused by two black holes colliding each ...
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1answer
26 views

Is the expanding of the universe also a cause which can induce gravitational waves from mass?

Gravitational waves arises when mass is rotating in another mass'orbital, in explosions and of course in case of colliding black holes. But are they also created when mass is moving and speeding ...
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2answers
39 views

Are gravitational waves effected by the curvature of space time (gravitational lensing)?

I have a basic question I can't seem to find anything on (I keep hearing about how gravity waves and gravitational lensing were both predicted by Einstein). We all know about the gravitational ...
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1answer
42 views

How did LIGO detect the source of the gravitational waves?

I read the newspaper today and I found that LIGO had detected gravitational waves. This is from their official website: For the first time, scientists have observed ripples in the fabric of ...
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45 views

How does LIGO reduce noise below what it is detecting?

LIGO is designed to detect changes in length on the order of 10,000ths the scale of a proton. I know they are extremely well isolated from their surroundings, but how could we even approach isolation ...
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61 views

Are gravitational waves dissipated and what is the mechanism?

I was amazed by the fact that we have been able to detect gravitational waves created thousands of year before they were observed. My surprise is that any wave phenomena I know it is always ...
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1answer
42 views

How much time distortion was caused by GW150914?

I understand (at least I think I understand) that LIGO used distortion of space to detect GW150914 (one arm grew longer, the other arm grew shorter, causing interference in the returning laser-pulse ...
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2answers
52 views

What was the frequency of the gravitational wave recently detected, and why?

In one early Internet post there was a graphic that appeared to show the gravitational wave (pulse) at about 30 cps. And another video it was stated that the gravitational wave would be as high as ...
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0answers
28 views

Do gravitational waves interact with the Earth's magnetic field?

Do gravitational waves cause a minor vibration of the Earth's magnetic field, and therefore a minor (if undetectable) electrical inductance?
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2answers
50 views

Could the LIGO in fact 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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0answers
34 views

Path of light and gravitational waves

Now that gravitational waves are detected, the way they are detected was using laser beams and they were out of phase when the return from the same trip distance. Does this means it is based on ...
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1answer
34 views

Is there any issue/concern for a slight wavelength shift of the laser light in the LIGO experiments?

A friend and I were having a discussion about the LIGO experiments and were wondering if there is any issue with the laser light undergoing a wavelength shift as a result of the gravitational wave? ...
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2answers
95 views

Do the photons emitted along with the gravitational waves take more time to reach earth than the ones emitted after them?

I'm puzzled because the gravitational waves do warp the spacetime locally. They do it continuously as they propagate. So the photons travelling in tandem with these waves must be constantly following ...
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1answer
46 views

Orientation of the LIGO Arms

The orientation of the interferometer arms at both sites are approximately Northeast-Southwest and Nortwest-Southeast, though I assume that, on account of the Earth's curvature, no pair of arms is ...
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1answer
60 views

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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2answers
80 views

Does wave-particle duality exist for gravitational waves?

For electromagnetic waves there exists a wave/particle duality: light sometimes behaves as a wave, and other times as a particle (photons). Does such a duality exist for gravitational waves? In other ...
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2answers
75 views

How were the solar masses and distance of the GW150914 merger event calculated from the signal?

The GW150914 signal was observed, giving us the frequency and amplitude of the event. Because LIGO has two detectors a rough source location could be derived. But how do these three factors allow for ...
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1answer
64 views

Where does gravitational waves' energy go?

Following the measurement of gravitational waves, many sources described them and explained they carry energy away. What I don't get is how this energy will get transfered back to anything else. If ...
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2answers
42 views

Can we see the famous black hole pair or its effect on other stars in any other means but LIGO?

If the source of LIGO's detection is a pair of black holes, can we see them using a traditional electromagnetic/neutrino/some other kind of telescope? Or can we see their effect on other stars in ...
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1answer
74 views

LIGO discovery: if the space “time” metric is changed, how is it measured?

Regarding the wonderful 2016 news about gravitational waves. Travel time in one arm of the LIGO is ~ 30μs. A gravitational wave affects the arm for some few hundred of these laps. Then for example ...
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2answers
142 views

Could discovered gravitational waves in fact be an aether wind? [duplicate]

Proving the existence of gravitational waves might revolutionise cosmology, but the method used by LIGO is quite similar to the famous Michelson-Morely interferometer built more than a hundred years ...
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4answers
169 views

Could LIGO discovery be due to e.g. earthquakes or have a terrestrial source?

I mean, could it have been earthquakes or anything else?
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0answers
26 views

How do gravitational waves and black holes interact?

Following the first detection of gravitational waves yesterday (11 Feb. 2016) by LIGO, I have a couple of questions about how gravitational waves and black holes interact. Assume that there is a ...
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55 views

Now that gravitational waves have been discovered, what does their particle version look like? [duplicate]

Duality dictates that gravitational waves should have a particle counterpart too, right? Will this in any way help solve the big problem of quantum gravity?
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0answers
26 views

What is the effect of gravitational waves on time? [duplicate]

I always struggle with the time concept when it comes to general relativity. In the recent discovery the gravitational waves have been detected by the "displacement" of the mirrors and the difference ...
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0answers
25 views

In GR what is a “source-frame mass”?

In the recent LIGO paper, they refer to the masses in some models as: "... a nearly equal mass black-hole binary system of source-frame masses $36^{+5}_{−4} M_{\odot}$ and $29^{+4}_{−4} M_{\odot}$ ...
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1answer
58 views

How much force is required to produce a noticeable gravitational wave?

By noticeable, I do not mean noticeable from half way across the galaxy to our observatories, but noticeable as in, if there were an object with enough mass and energy within say, the distance of our ...
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4answers
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Do gravitational waves travel faster than light?

In Feb 12, 2016 edition of Times of India, an article read [with the discovery of gravitational waves, we will be able to] Track Supernovas hours before they're visible to any telescope because ...
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2answers
62 views

Is there a connection between Space-Time Vortex and Gravitational Waves?

Is there a connection between Space-Time Vortex and gravitational waves? Space-Time Vortex
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1answer
95 views

How does LIGO account for curvature of Earth?

Using an earth curvature calculator, I found that at a distance of 4 km (the length of LIGO's arms), more 1.26 m is hidden by the horizon. When constructing LIGO, did they account for the curvature of ...
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1answer
78 views

Why are Gravitational Waves so small?

I'm sure you've all seen the diagrams and/or 3D visualizations of gravity; the ball sitting on a piece of fabric which makes it sink down. They've also started using it in the videos that explain ...
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1answer
135 views

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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0answers
68 views

In what shape do gravitational waves radiate?

The recent detection of gravitational waves made me wonder how the amplitude of the waves fell off with distance. My first naive thought was that it was probably by the cube of the distance. ...
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1answer
46 views

If the solar system is a sensitive chaotic system, can gravity waves make orbits unpredictable?

Scott Tremaine says here ..for practical purposes the positions of the planets are unpredictable further than about a hundred million years in the future because of their extreme sensitivity to ...
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0answers
35 views

What would it look like if the earth were suddenly put on the anti-node of a gravitational standing wave with a huge amplitude?

What would it look like if the earth were suddenly put on the anti-node of a gravitational standing wave with a huge amplitude? Can gravitational standing waves even exist? Say if there were two ...
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0answers
34 views

The existence of gravity waves has just been demonstrated by direct observation, 2016 [duplicate]

How does the apparent confirmation of gravity waves effect String Theory today
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1answer
204 views

How is it that distortions in space can be measured as distances? [duplicate]

Imagine yourself and anything you're able to perceive to be drawn onto a rubber band. Any means of determining distances would be affected by the stretching/contracting of the rubber band. The ...
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2answers
88 views

At which point are gravitational waves generated when two black holes merge?

I was reading today's announcement of the gravitational waves and was wondering about this situation where there are two orbiting black holes. Did the wave come from the final merging or was it from ...
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1answer
81 views

How did LIGO detect the source location of the black holes mentioned to be the cause of today's announcement?

Today LIGO announced discovery of Gravitational waves. What method was used to determine the source location of the waves?
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2answers
90 views

Redshift of merging black holes

How did they found that the gravitational waves where emitted at redshift $z=0.09$? I understand the measurement of redshift for an electromagnetic wave where we have measured in a lab various ...
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0answers
142 views

Einstein's original papers predicting gravitational waves?

I came across the original handwritten papers in which Einstein predicted gravitational waves1: and since LIGO announced they've detected a signal confirming the predictions I was wondering if ...
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1answer
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So Black Holes Actually Merge! In 1/5th of a Second - How?

I've read a lot of conflicting answers in these forums. However, today saw the awesome announcement of gravitational waves. Two black holes merged: ...