Questions tagged [gravitational-waves]

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199
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9answers
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Why is the detection of gravitational waves so significant?

LIGO has announced the detection of gravitational waves on 11 Feb, 2016. I was wondering why the detection of gravitational waves was so significant? I know it is another confirmation of general ...
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Why does the LIGO observation disprove higher dimensions?

I recently read this article which claims that last year’s LIGO observation of gravitational waves is proof that, at least on massive scales, there cannot be more than three spatial dimensions. I ...
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What was the major discovery on gravitational waves made March 17th, 2014, in the BICEP2 experiment?

The Harvard-Smithsonian Centre for Astrophysics held a press conference today to announce a major discovery relating to gravitational waves. What was their announcement, and what are the implications? ...
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Is there 'friction' in spacetime?

So, if all the bodies are embedded in space-time and moves through it, is there some kind of 'friction' with space time of the planets? For example, the Earth suffers friction when moving near the sun ...
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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 the ...
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Why did the gamma ray burst from GW170817 lag two seconds behind the gravitational wave?

The ABC, reporting on the announcement of gravitational wave GW170817, explained that for the first time we could identify the precise source of a gravitational wave because we also observed the event ...
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In theory, could gravitational waves be used to make a “gravity laser”?

The sources I've read compare gravitational waves to electromagnetic waves. I'm curious to what extent this is. In theory, could gravity be harnessed in similar ways to how we've used electromagnetic ...
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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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Would you hear a gravitational wave, if its amplitude and frequency were suitable?

If there was a source of a continuous gravitational wave at (say) 50hz, and amplitude of say a micrometer (a typical sound wave displacement, I think), and you were nearby (standing happily on a ...
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How much mass can colliding black holes lose as gravitational waves?

Concerning the recent detection of gravitational waves produced by colliding black holes, it has been reported that a significant percentage of the combined mass was lost in the resulting production ...
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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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If spacetime is curved, how would anyone know? If anyone could tell, would that really be spacetime curving?

I never had a problem accepting that spacetime is curved as a result of matter, until I learned the LIGO experiments showed that evidently the curvature of spacetime can be measured. This, to me, is ...
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Is it theoretically possible to shield gravitational fields or waves?

Electromagnetic waves can be shielded by a perfect conductor. What about gravitational fields or waves?
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Could a powerful gravitational wave cause electrons to emit light?

I imagine electrons being accelerated by passing gravitational waves, say from a nearby kilonova, so I would expect the electrons to emit light. Am I right?
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Are gravitational waves longitudinal or transverse?

Waves are generally classified as either transverse or longitudinal depending on the they way the propagated quantity is oriented with respect to the direction of propagation. Then what is a ...
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1answer
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Can gravitational waves be red-shifted?

Whenever the Doppler effect is mentioned, it's typically in the context of sound waves or electromagnetic radiation. On the cosmological scale, red-shifting is also important because of the enormous ...
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Why can't we produce gravitational waves in the lab?

Fairly straightforward. I just thought it wouldn't be too hard to produce a ripple in spacetime several times smaller than a proton radius in a particle accelerator or something. It seems like it ...
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Could (old) LIGO have detected GW150914?

The merging black hole binary system GW150914 was detected in only 16 days of aLIGO data at a signal level that appears to be well above the detection threshold at around 5 sigma. There are no further ...
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What will we learn from further LIGO events?

LIGO announced a third gravitational wave detection today. The news outlets didn't comment on significant differences between this one and previous detections. Did this third event teach us anything ...
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Is the graviton hypothetical?

Wikipedia lists the graviton as a hypothetical particle. I wonder whether graviton is indeed hypothetical or does its existence directly follow from modern physics? Does observation of gravitational ...
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How strong were the gravitational waves that LIGO detected at the source?

Congrats to the LIGO team on the announcement of their discovery of gravitational waves! The articles I've read say that the distortion we see here is much smaller than a proton. What about at the ...
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Why did the neutron star merger signal last for so much longer than the black hole merger signals?

Just recently, LIGO and Virgo successfully detected new signs of gravitational waves. This time, instead of colliding black holes, it is a pair of colliding neutron stars. This collision emits light ...
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Why were the GW detections at Livingston and Hanford separated by 7 ms if the light travel time between them is 10 ms?

How did a gravitational wave travel from Livingston, Louisiana to Hanford, Washington in 7 milliseconds, when they are separated by 10 milli-light seconds (3002 km)?
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Gravitational radiation from hydrogen atom [duplicate]

Background: It is known that orbital motion is accelerated motion under the influence of a central force; and that in a hydrogen atom the electron orbits the proton and is therefore accelerated; and ...
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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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Would warp bubbles emit gravitational Cerenkov radiation in general relativity?

Inspired by the gravtiomagnetic analogy, I would expect that just as a charged tachyon would emit normal (electromagetic) Cerenkov radiation, any mass-carrying warp drive would emit gravitational ...
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How can LIGO still detect the gravitational waves?

I was watching this video by Veritasium (note: I don't have much physics knowledge). As I understand, at LIGO they detect the gravitational waves that were generated by the collision of the two black ...
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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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Can gravitational wave be used for data transmission?

Imagine an advanced civilization which can manipulate gravity like we manipulate electromagnetic radiation. Could they already be using gravitational waves for data transmission across different ...
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Is there a possibility for discovery of anti-graviton, i.e. the graviton antiparticle?

If gravitons exists, then would there be anti-gravitons as well? 1)If not, why? 2) If yes, what are their expected properties?
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How close would you have to be to the merger of two black holes, for the effects of gravitational waves to be detected without instruments?

Assume two black holes in the most common size range, spiraling into each other until they merge. The event releases significant amounts of energy via gravitational waves, which warp the space-time. ...
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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: http://www.slate.com/blogs/bad_astronomy/2016/02/11/...
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1answer
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Are the masses of merging black holes correlated?

LIGO/VIRGO recently released data on observed "gravitational wave transients", mostly BH-BH mergers. The data includes a plot of the primary and secondary mass (the primary mass is defined as the ...
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1answer
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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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How can I read off the fact that gravity is associated with spin-2 particles from the Einstein-Hilbert action?

I have often heard that the gravitational field has spin $2$. How can I read the spin of the field from the Einstein-Hilbert action $$S=\int \! \mathrm{d}^4x \,\sqrt{|g|} \, \mathcal{R} \, \, \, ?$$
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Is there a good chance that gravitational waves will be detected in the next years?

Is there a good chance that gravitational waves will be detected in the next years? Theoretical estimates on the size of the effect and the sensitivity of the newest detectors should permit a ...
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Since there are gravitational lenses, are there gravitational mirrors?

Gravitational lensing is an observed phenomenon. Can one have a gravitational mirror? A slightly unrelated question: Can gravitational waves be reflected?
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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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Wouldn't angular momentum of a binary star system decrease?

Consider a binary star system, as these stars go around one another they would emit gravitational waves. Since, the graviton is a spin 2 particle. Wouldn't the angular momentum of the stars decrease? ...
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Do gravitational lenses work on gravitational waves?

Do gravitational lenses work on gravitational waves? Could we get an Einstein cross of gravity?
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How are 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 coming (as in a Michelson interferometer) to a sensitivity of $10^{-18}\:...
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LIGO flawed by the identical expansion of laser wavelength and arms in presence of a gravitational wave?

LIGO, Laser Interferometer Gravitational-Wave Observatory, is a large-scale physics experiment aiming to directly detect gravitational waves. The device measures the phase shift laser beams. If I ...
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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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G4v Gravitational Wave vs General Relativity vs LIGO Observation

CalTech emeritus professor Carver Mead produced an alternative prediction, to General Relativity, for gravitation wave observation which he published last year in anticipation of LIGO observations. ...
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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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Would it be possible to transmit information through gravitational waves?

First thing I've been wondering is how the gravitational field is emitted. Matter emits gravitational waves, and I guess that those waves travel at around the speed of light. If that's not the case, ...
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How would a passing gravitational wave look or feel?

In a hypothetical situation I'm still sitting in a coffee shop but a gravitational wave similar to the three reported by LIGO passes through me from behind. The source is much closer though, so this ...
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Trying to understand what a gravitational wave is

It seems to me that there is a great deal of interest in the possibility of gravitational waves. Several gravitational-wave detectors have been built, and there is even a branch of science with that ...
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Why is there a search for an exchange particle for gravity?

If I understand correctly, according to Einstein's General Theory of Relativity, mass results in a distortion in space-time. In turn, the motion of the mass is affected by the distortion. A result of ...
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Did merging Black Holes in GW150914 give up entropy and information to the gravitational waves, since they lost 3 solar masses?

Since the final Black Hole (BH) had 3 solar masses less of mass than the original binary BH, it seems the 2 BHs lost mass, and with it event surface area, entropy, and information. If that came from ...