Questions tagged [gravitational-waves]

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Effects of a neutron star merger

After the announcement of a neutron star merger on 16 October, I have been wondering how close such a merger would have to be in order to generate effects that could affect life on Earth. For example,...
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Implications of the LIGO detections on the 'Modified Gravity' Program

We all know that GR needs modification at the microscopic scale but there are some attempts to modify GR in the classical regime as well, known by the name of "Modified Gravity". As far as I ...
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What is the redshifted amplitude of a gravitational wave?

Consider a gravitational plane wave in flat background spacetime, with amplitude $h$ and frequency $f$. For an observer moving with redshift $(1+z)$ relative to the plane wave, what is the observed ...
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Neutron star merger: large scale dynamics

Yesterday was announced the first detection of a neutron star merger via gravitational and electromagnetic waves. On the announcement one of the speakers is showing a simulation of the dynamics of ...
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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 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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Did LIGO detect gravitational waves from Big Bang Inflation?

I recently watched an installment of "Spaces Deepest Secrets" that examined the efforts of the BICEP2 team. (Strangely, it was titled "When Black Holes Collide.") The team was looking for ...
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Do neutrino produce gravitational wave?

Neutrino can oscillates and it's mass fluctuate according to which of the three known flavors, since it has mass and is known to change flavors in flight... now more mind blogging stuff is the ...
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Would it be scientifically useful to put a LIGO or VIRGO on the moon?

Or a couple of them on the moon? It seems to me that it's seismically pretty quiet there, with no trucks bouncing around on a nearby highway messing things up. Maybe four LIGOs at the vertices of a ...
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Strength of gravitational waves vs. electromagnetic waves

If the recent gravitational wave's energy had reached us as visible light, how bright would it have been? Stackexchange complains about the form and brevity of the question so i add something... if it ...
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1answer
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What is the point of the reaction mass in the LIGO mirror suspension system?

I learned from the LIGO official website that the LIGO mirror suspension system consists of a "main chain" and a "reaction chain", and there are small electric motors gently pushing the masses on the ...
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Is it possible that dark matter is just a bunch of gravitational waves interacting with one another? [duplicate]

Since stars and other objects are much closer to one another towards the centers of galaxies where dark matter tends to be found, it seems that it would follow that events forming gravitational waves (...
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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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Gravitational waves and the word “ripple”

Now a days physicists have succeeded in discovering gravitational waves. Like a recent one with merging two large black holes billions of light years far away Well it is quite big discovery and ...
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Is the LIGO detector acceptance different for gravitational and for non-gravitational waves?

The famous signals recorded by the LIGO observatories are characterized as observations of passing gravitational waves, where at each observatory site: Test masses are hung by wires near the vertex ...
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1answer
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Will Gravitational Wave ripple permanently alter space-time?

When Gravitational Waves alter space-time, would that change be permanent? Will the space-time returns to its initial state once the ripple has stopped?
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What is the probability that gravitation wave detections were coincidental errors? [duplicate]

The reported discovery of gravitational waves has been put in question by the scientific community: https://www.quantamagazine.org/strange-noise-in-gravitational-wave-data-sparks-debate-20170630/ In ...
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Can gravitational waves be absorbed near a quasar?

As the Quasar Wikipedia article explains, a quasar is powered by gas falling into a supermassive black hole at the center of a galaxy. The Luminous infrared galaxy article says that, in extreme cases, ...
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Are gravitons real? [duplicate]

Is graviton a particle? What's your view on this? Sence physics is the study of matter, it seems to me forced to believe that the gravitational force are particles. There are no particle called ...
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1answer
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How to know the distance of the black hole merger? [duplicate]

I have a question about the detection of the gravitational waves by LIGO. When there is no electromagnetic wave coming from the black holes, then how do they know in which distance it is?
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Is there any electrostatic waves for electrostatic force like the gravitational waves for gravity?

If sun suddenly disappears then it will take 8 minutes for earth to move out of its orbit due to the presence of gravitational waves. What happens if proton in an atom suddenly disappears, will the ...
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1answer
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Why does the magnitude of the Gravitational wave reach maximum peak upon merger?

We all know that objects which are accelerating in space-time produce Gravitational waves. My question is why is there a burst of GW upon two black holes merging. Also, does that mean that let's say ...
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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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Consequences of a stable geon

What would be the consequences be of a stable geon? What similiarity, if any, would it have to a naked singularity? What would a stable geon potentially look like, and what would the immediate ...
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1answer
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Easy to grasp physical description of LIGO sensitivity?

Every now and then friends ask for an overview explanation of detection results from LIGO. I know/understand just enough to be useful to them. One of the examples I use (I think it originated in a ...
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What's the relationship between classical gravitational waves and gravitons? [duplicate]

LIGO have detected gravitational waves, why we are still far away from detecting gravitations? how to understand the statement below? A classical wave may be considered to be a coherent ...
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3answers
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How do we know LIGO didn't detect stars but Black holes? [duplicate]

My assumption is that stars have significantly larger volume than black holes. And if they spiraled they would would merge before they had the chance to reach high enough velocities to generate ...
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Inflationary model that predicts both gravitational waves and isocurvature perturbations

I 'm searching for inflationary models that predict both gravitational waves and isocurvature (isothermal) perturbations. If I understood well, de Sitter inflation predicts only curvature (adiabatic)...
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Does a binary system really emit gravitational waves?

In this essay from Petkov, it is stated on page 13 that when the stars follow their orbits in the binary system, they do not emit gravitational waves since they move by inertia according to general ...
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Is speed of gravitational waves constant? [duplicate]

Is the speed of gravitational waves constant in all inertial frames? If so, why isn't this included as one of the postulates of special relativity?
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Can a gravitational wave stretch a volume equally in 3 dimensions?

The wikipedia page for gravitational waves contains this statement: "The area enclosed by the test particles does not change and there is no motion along the direction of propagation. citation needed" ...
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Gravitational wave luminosity and energy transfer to masses in vicinity of merging mid-sized black holes

Would the energy transmitted by gravitational waves to stars or planets in the vicinity of a mid-sized black hole merger be enough to disrupt those bodies? If so, how far away would the gravitational ...
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Can gravitational wave induce electromagnetic waves?

Moving charged particle produces a magnetic field. If a gravitational wave passes by stationary charged particle and makes it oscillate together with the space, would that movement produce an EM wave?
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Why did we take so long to directly detect gravitational waves?

According to this article, http://www.sciencemag.org/news/2016/02/gravitational-waves-einsteins-ripples-spacetime-spotted-first-time, the search for gravitational waves was beset by continual ...
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Do gravitational waves violate conservation of baryon number?

I was reflecting on the large amount of energy released in the black hole merger GW150914. The black holes were about 36 and 29 solar masses, with the resulting black hole being 62 solar masses and 3 ...
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Are the gravitational wave mass estimates redshift dependent?

In answers to previous questions about (see, especially, this one) the LIGO detections it is stated that LIGO is unable to determine redshift, only luminosity distance. This is made clear in the ...
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Why people think dark matter as a massive particle? Couldn't it be gravitational waves?

Dark matter is said to be present in the galaxies which helped galaxies to exist in the first place forming the glue to attach all the matter in the galaxies. Given that dark matter never been seen ...
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Gravitational and electromagnetic radiation from collision of Kerr-Newman black holes

When black holes collide, they produce a gravitational wave, as has been recently established by LIGO. When a charge is accelerated, it creates an electromagnetic wave. Does an accelerated massive ...
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Could gravitational waves be matter waves?

Pretty straightforward. The idea of 3 solar masses radiating away as gravitational waves is still troubling to me. I don't understand how matter can be converted into 'gravitational energy'. I can ...
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Can gravitational waves be explained by the interactions between photons? [closed]

What the question really amount to asking is, if (as LIGO said) the gravitational waves emitted from the black hole collision were emitted as 'pure energy' this surely means that they were emitted as ...
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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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Is the gravitational pull of the early ($10^{10}$ more massive) universe still observable?

During one of the early epochs of the universe it used to be 10^10 times more massive than it is now, just before the matter / antimatter annihilation. So what cosmic gravity is being asserted on the ...
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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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Where does the rate of mergers per halo in the “Did LIGO detect dark matter?” paper come from?

It was recently proposed that dark matter (DM) could be made of primordial black holes (PBHs) of $\sim 30 M_{\odot}$, like the first ones detected by LIGO. This idea was written in "Did LIGO detect ...
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Why do two masses orbiting around their CM emit gravitational radiation?

Two (extended, non-point-like) masses orbiting around their CM are emitting gravitational waves. However, these masses are both in free fall and follow a geodesic path through space-time. Now ...
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What LIGO should detect that it has not yet?

What would the lack of detection of such phenomena tell us about the Universe? What should be the most frequent signals detected, theoretically speaking? I'm a lay person in the area, so you might ...
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Gravitational waves and Michio Kaku [closed]

I was reading a book from 2005 written by Michio Kaku (Parallel Worlds). In the book it is stated, that if gravitational waves should be detected, then that proves the multiverse theory. is there any ...
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How does the orientations of the two black holes' spins show up in LIGO data? (GW170104)

Today's Phys. Rev Letter GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2 shows the analysis of the third confirmed detection of a black hole merger by the LIGO ...
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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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Are gravitational waves produced only by masses which experience a change in acceleration, and if so, is this connected to the spin 2 of the graviton?

I can't remember for sure, which is why I ask this question, but is it the case that gravitational waves are produced not by accelerated masses (like e.m. waves are produced by accelerated charges), ...