Questions tagged [gravitational-waves]

Waves in spacetime formed by the acceleration of massive bodies. A passing wave causes spacetime to be stretched and squashed by a very small amount. Typically we can only detect the most energic gravitational events such as black hole mergers.

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Why is the discovery of merging neutron stars important?

I'm fairly certain people here will have heard about it, already, but apparently, two supernova leftovers clashed some 130 million years ago and some billion billion kilometres away ... What I haven'...
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Can gravitational waves pass through a black hole?

As the title says, what happens when a gravitational wave approaches a black hole? I would presume that something interesting happens because of the way spacetime works near black holes but I have no ...
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What did LIGO Actually See? (Gravitational waves discovery)

I am trying to find an original video/image of what LIGO actually saw, but all I can find is artist renditions of gravitational waves.
Scott Taylor's user avatar
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Quantum Mechanics after the detection of Gravitational Waves

Of course everyone knows by now of the detection of Gravitational waves But, since General Relativity and Quantum Mechanics don't get along, can we say now that this detection proves that Quantum ...
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Are binary neutron star mergers needed to explain the abundance of gold?

The NPR News item Astronomers Strike Gravitational Gold In Colliding Neutron Stars mentions and quotes "Daniel Kasen, a theoretical astrophysicist at the University of California, Berkeley:" ...
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Why does the sensitivity to GWs drops off inversely proportional to the distance?

This answer makes me wonder why the sensitivity to gravitational waves decreases proportionally to the distance. Since gravitational waves extend in all directions, my (uneducated) guess would be ...
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What observations can be expected on LIGO if any when Betelgeuse goes supernova?

What observations can be expected from the LIGO† gravitational wave observatory if and when Betelgeuse goes supernova? Would we know that Betelgeuse has gone supernova before we see it light up our ...
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How far away are the events that caused the gravitational waves that have been detected?

A certain number of gravitational wave events have been detected. Is it possible to know how far away the mergers that caused those gravitational wave events are?
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Multi-messenger astronomy: what is the potential of simultaneous detection of gravitational waves and neutrinos from a supernova?

Thanks to the efforts of the aLIGO team, gravitational wave astronomy is a reality. At the same time, neutrino detectors like Hyperkamiokande are becoming much more sensitive. My question is: what ...
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Is it suspicious that gravitational waves propagate at the speed of light?

Thinking about gravitational waves and the fact that they propagate at the speed of light, I was wondering if it isn't suspicious - the speed of light I mean. Does it perhaps point to something ...
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Is there an upper limit on the mass of black hole mergers we can detect?

From the LIGO website, black hole mergers have been observed between black holes with a mass up to roughly 50 $M_\odot$. Are there no black holes with a mass above 100 $M_\odot$ or is this an ...
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Why can't supermassive black holes merge? (or can they?)

The CNet article Astronomers discover two supermassive black holes in a death spiral links to Discovery of a Close-separation Binary Quasar at the Heart of a z ~ 0.2 Merging Galaxy and Its ...
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"Who saw" the binary neutron star merger first? What was the sequence of events? (GRB/GW170817)

I'm trying to read Multi-messenger Observations of a Binary Neutron Star Merger the "cast of thousands" OPEN Access ApJ letter 848:L12 (59pp), 2017 October 20 https://doi.org/10.3847/2041-8213/aa91c9 ...
uhoh's user avatar
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Frequency of gravitational wave detection

You may have heard in the news that the LIGO experiment recently detected a gravitational wave. Though I'm not an astronomer, the paper is a good read and mostly accessible. The detection of the ...
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Sound of a black hole merger

If we were in an earthlike planet at 1AU from a black hole merger, would we be able to hear the spacetime strains as the black holes orbit around each other? How would it sound?
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How exactly does inflation convert random gravity fluctuations into coherent gravitational waves?

In the course of this very enjoyable press announcement, it is mentioned that inflation can create gravity waves by amplifying gravity fluctuations. I do not properly understand this statement. I ...
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Why do Earth and moon move apart but binary black holes move closer?

According to the accepted answer on Is the moon moving further away from Earth and closer to the Sun? Why?, the moon is receding from Earth because tidal forces and friction cause energy to be lost. ...
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Why are there not yet any instruments dedicated to registering time dilation caused by passing gravitational waves?

Why are there not yet any instruments dedicated to registering time dilation caused by passing gravitational waves? Wouldn't it be interesting to augment LIGO/Virgo capturing of space distortion with ...
Alex's user avatar
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Are there any gaps in the range of gravitational wave frequencies we can detect?

We have LIGO and other earth-based interferometers for detecting high-frequency gravitational waves, we're going to have satellites in orbit around the sun for low-frequency waves, and we have a ...
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How is the Hubble constant determined from gravitational waves?

We know there is a discrepancy between measurements of the Hubble constant, $H_0$. On one side there is the method of the Planck mission, where they use the CMB and the $\Lambda$CDM model to determine ...
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Why do gravitational waves travel "only" at the speed of light but the gravitational scalar potential is instantaneous?

To my old Space SE question Besides retarded gravitation, anything else to worry about when calculating MU69's orbit from scratch? @DavidHammen's excellent answer replies that one should not add a ...
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Life planets orbiting black-holes. Can/Do they really exist?

So, I watched Interstellar and if you watched it too you know that there's a planet orbiting a black-hole, they call it Miller's Planet. According to the movie, every hour on Miller's Planet is ...
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Can gravitational waves transfer energy or momentum to baryonic matter

In essence I want to know if GW can affect the momentum of baryonic matter. I know that massive objects like planets, stars, galaxies, etc will not be "ripped apart" or even disturbed by ...
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Why did astronomers believe most or all stellar black holes had masses no greater than 15 solar masses?

The so-called 'mass gaps' for black holes, according to theoretical models, are between 2-5 solar masses and 50 to 150 solar masses. (Actually, I have read that there is no good theoretical reason ...
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From where does the energy for gravitational waves come from?

As far as I understand, in the events detected by LIGO, about 4% of the total mass of merging binary black holes was converted to gravitational waves. Where does this energy come from, i.e. what ...
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Energy deposition in planet Earth due to gravitational waves

The gravitational wave detected by the LIGO observatory acted on planet Earth streching and shrinking it a little bit. I assume that not all of this action was fully elastic and that some energy of ...
Sir Cornflakes's user avatar
11 votes
1 answer
552 views

Why can we detect gravitational waves?

Now that LIGO has finally measured gravitational waves using a huge laser interferometer, to me, the question remains, why was it possible? As it is explained in many news articles, gravitational ...
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Will gravitational waves too far away ever reach us?

Gravity is the curvature of spacetime, and its effects travel at lightspeed. However, space is expanding; eventually, light from distant galaxies will become more and more redshifted, and we will no ...
Sir Cumference's user avatar
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564 views

What would it feel like to be orbiting near a merging black hole?

The recent 4th discovery of gravitational waves where the black hole masses were 31 and 25 times the mass of the sun, and they released 3 solar masses of energy as gravitational waves, made me wonder ...
joseph.hainline's user avatar
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Do mixed type remnant collisions produce anything interesting?

The recent detection of a binary neutron star inspiraling and colliding raises an interesting question in my mind. Type Ia supernovae are believed to be caused by white dwarf/regular star pairs and/or ...
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Are gravitational waves emitted equally in all directions?

I have a question regarding gravitational waves that I can't figure out. Hope some wise minds here can help a simple amateur without technical or scientific education. Two black holes rotating around ...
Peter's user avatar
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The size of the radius of the event horizon of a black hole created by the merger of a black hole binary system

Let's assume that you had a black hole binary system and everything said here is possible. Their large masses would lead to a large emission of gravitational waves. The loss of orbital energy and ...
ScienceGirl1234's user avatar
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1 answer
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What do the acronyms in "AT 2017 gfo" mean?

About 11 hours after the detection of GW170817 by Ligo/Virgo and the quickly succeeding detected GRB170817, a transient afterglow in the optical-nIR frequency appeared which showed many signs of r-...
Arturo don Juan's user avatar
9 votes
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639 views

Gravitational waves and gamma ray burst: how were the error bars determined for this speed of gravity calculation? Was $H_0$ used?

This newly updated answer to How precise are the observational measurements for the speed of gravity? and this answer to How is the most accurate value of 𝐺 measured? cites the November 2017 arXiv ...
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Black Hole Collision & Gravitational Waves

The Gravitational waves detected by LIGO on 14th September 2015 are attributed to a collision of two black holes, which had been rotating near the speed of light around each other just before the ...
Jan Stuller's user avatar
9 votes
1 answer
512 views

Why can there be several seconds of lag between a binary neutron star merger and the emission of gamma rays from the same area?

Answers to: Gravitational waves and gamma ray burst: how were the error bars determined for this speed of gravity calculation? Was $H_0$ used? go into substantial detail explaining this determination. ...
uhoh's user avatar
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9 votes
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In an isolated binary system, can the expansion of the universe balance out collapsing orbit due to gravitational waves?

We know that binary systems slowly lose energy due to gravitational waves from the objects moving through spacetime and that if the objects are compact and massive enough, the mergers happen in time ...
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How does the Gamma Ray Burst that occurred when 2 black holes merged compare to other GRB's?

A Gamma Ray Burst was detected 0.4 seconds after the gravitational wave event, GW150914, caused by a black hole merger, and it was in the same part of the sky. It is uncertain whether that Gamma Ray ...
RichS's user avatar
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Do tidal forces on moons cause them to emit gravitational waves?

As moons orbit planets, they get squashed by uneven gravitational forces acting on them. Does this make a moon emit gravitational waves?
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391 views

Is there a limit to the distance of detectable gravitational wave events?

This is somewhat a follow up question to this one. This article indicates that the binaries detected have a distance between 320 and 2840 Mpc. With the current technology, is there a limit to the ...
usernumber's user avatar
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8 votes
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Is gravitational wave frequency always equal to double the orbital frequency?

If the binary does not evolve into merger stage (i.e.: it is still a steady binary), does the gravitational wave frequency have to be 2*orbital frequency? Could the frequency be, for instance, 2/3*...
Chen's user avatar
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8 votes
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Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves?

Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves? Is this attribution unique, or are there other mechanisms that could lead to the excitation of tensor modes? In ...
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What produces gravitational waves with "periods between about 100 - 8000 seconds"?

The Ulysses mission has a compelling story. It was sent to Jupiter to perform a gravitational assist shooting it out of the plane of the ecliptic in order to fly over the Sun's north and south poles ...
uhoh's user avatar
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7 votes
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If an object 1 billion light years away emits light, does it take more than 1 billion years to reach us because of the expansion of the universe?

From page 7 of the recent (September 26, 2020) edition of Science News Magazine: Detected May 21, 2019, the gravitational waves came from a source about 17 billion light-years from Earth, making this ...
Kurt Hikes's user avatar
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7 votes
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LIGO: How can laser interferometry (wavelength >$10^{-7}$m) detect length changes of arms <$10^{-18}$ m?

I'm trying to understand the sensitivity of the LIGO interferometer. I've been reading around lots of discussion of how they manage noise cancellation between the two detectors, achieving a very pure ...
user2433311's user avatar
7 votes
1 answer
104 views

What changes are being made to VIRGO and LIGO (if any)?

Gravitational wave detectors VIRGO and LIGO are currently down for some updates, slated to be completed sometime early next year (they hope). What exactly are they doing? I hadn't heard it was down ...
Magic Octopus Urn's user avatar
7 votes
2 answers
341 views

Would gravitational waves be subject to external gravitational perturbations?

Given that the gravitational wave detected by LIGO was a very weak echo of a very distant event, could it have been "deviated" and distorted on its way here by a sufficiently massive black hole in ...
Drunken Code Monkey's user avatar
7 votes
1 answer
191 views

What will eLISA be trying to observe?

eLisa - Evolved Laser Interferometer Space Antenna. A LISA-like mission is designed to directly observe gravitational waves, which are distortions of space-time travelling at the speed of light. ...
SF.'s user avatar
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6 votes
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Do supernovae produce powerful gravitational waves?

I would think that the amount of energy produced by one supernova is much more than a pair of colliding black holes, no? Wouldn't that much material and energy output from the explosion generate a ...
user6760's user avatar
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6 votes
6 answers
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Gravitational waves vs. "normal gravity"

Imagine you have a super sensitive 3D accelerometer/gravimeter alongside the Virgo interferometer. A gravitational wave passes by and Virgo detects a variation in the length of the 3000m long arms. ...
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