Gravitational waves Definition and 332 Threads

There are rumours that scientists at Advanced LIGO have detected gravitational waves ... it is about 100 years after Einstein predicted they were there in his mathematical theory of general relativity ... Anyone know more about this rumour ...? Peter

In section 4.4 of gravitational radiation chapter in Wald's general relativity, eq.4.4.49 shows the far-field generated by a variable mass quadrupole: \gamma_{\mu \nu}(t,r)=\frac{2}{3R} \frac{d^2 q_{\mu \nu}}{dt^2} \bigg|_{t'=t-R/c} I have the following field from a rotating binary...

So I saw that claims are being made that LIGO may have detected gravitational waves. http://www.nature.com/news/has-giant-ligo-experiment-seen-gravitational-waves-1.18449 My question is, if the universe were in fact multidimensional as string theory predicts, would gravitational waves propagate...

Can gravitational waves be treated like light or water waves? E.g. what would happen if two waves intersected at their max amplitude? Or what would happen if they intersected at a peak and trough?

What happens to a body experiencing a gravitational wave? Suppose I put a ball in the path of a GR wave. As the wave passes through it, the space will expand and contract. This means that the space between every point in the ball should expand and contract. But what will be the reference point I...

I'm not sure exactly how to phrase this question, but I was thinking earlier about electromagnetic waves being absorbed by atoms and 'slowing down' the speed of light. Do gravitational waves propagate slower when blocked by, say, a really massive object? In the same way that light slows down...

There is a rumor going around that a gravitational wave inspiral has been seen at advanced LIGO. The web sites say it went on line in Sept, 2015, so I guess this is possible. Has anyone here heard anything?

In today's Physics ArXiv: New constraints on primordial gravitational waves from Planck 2015. Authors Luca Pagano, Laura Salvati, and Alessandro Melchiorri of the Physics Department and INFN, Universita di Roma. Primordial gravitational waves from the universe exiting Inflation get more and...

I know GWs are produced by moving masses, but I can't find an explanation as to why it happens. A system would lose energy to gravitational radiation. Does the radiation get produced spontaneously, or would it be because the mass has to move through space-time which holds it back somewhat...

To motivate the question, Andy Strominger recently put out a paper on calculating the Sagnac shift of counterrotating beams due to the angular momentum flux of a passing gravitational wave. See here: http://arxiv.org/abs/1502.06120. But consider now two nearby freely falling gyroscopes...

Hi everybody, I have been reading about gravitational waves, but I don't get how the E modes work; in one place I read that they were created during the inflation time, but in other I read that they come from the recombination. Does it mean that they were produced almost when the Big Bang...

Could we detect Earth gravity wave from Earth orbit?

Hi All, Can someone tell me why gravitational waves are always decomposed in spin weighted spherical harmonics with spin weight -2 ? I'm assuming you can hand wave the answer with something to do with the 'graviton' being a spin 2 particle but this isn't very satisfying to me. Are there any...

Heisenberg's Uncertainty Principle (HUP) tells us that the standard deviation in position times the standard deviation in momentum is equal to Planck's constant divided by 4π. And HUP also causes there to be a zero point energy in the fields of QFT. This is because position and moment can not...

The usual calculations for gravitational waves linearize the GR equations around the background solution of flat space time ( g = Minkowski metric matrix ) empty of matter and energy ( T = 0 ) What happens in cosmology, when one must linearize the GR equations about the FRW metric matrix with...

would gravitational waves redshift with the expansion of the universe ?

Hello. I would like to ask if really gravitational waves (GWs) exist? Mathematically they are predicted to exist. However despites the intense efforts invested to detect them so far they cannot be detected.

I always thought when there is no force acting on an object it moves at constant speed but every object that moves generates gravitational waves what causes that object to lose energy. Does it mean that object loses kinetic energy and slows down and after some (very long) time will stop.

I have read that the team at Vienna are conducting experiments to test whether even gravity can exhibit quantum superpositions or not. Is anyone tracking their late developments on this? What do the physics community think is going to happen when even gravitational waves are superposed. Will the...

Have "we" (the scientific community) found any proofs of gravitational waves? I read about an experiment including a couple of mirrors very apart from each other and a laser that aimed to somehow measure the possible existence of gravitational waves, but as far as I understood (clearly not much)...

Hi, I need a beginner's book to study gravitational waves by myself. I am an undergrad physics major and just took my GR course. A beginner's book on GR will also help me lot. please suggest

Hello all, Well, I am on my master project named 'General Relativity & Gravitational Waves'. My supervisor asked me if you can simulate gravitational waves by programming it would be a plus. But only programming language I am currently learning is python. Is it possible to simulate some kind of...

Stumbled upon this problem lately. Maybe someone could help me clarify some subtleties I do not see? 1. Consider the propagation speed ##c## of periodic surface of gravity waves with wavelength ##\lambda## and amplitude ##a## in water of depth ##H##. Let ##\rho_{a}## and ##\rho_{w}## be the...

An heavy body near other body gives off gravitational waves at a higher rate than when it is away from any body. So, if there is only one body in the universe and nothing else.Will it give off the gravitational waves and it's mass will keep decreasing?

Hi, I have been reading about gravitational waves for the last few days. I saw any cylindrically or spherically symmetric body can not produce gravitational wave, can you please explain to me why ? I also need a brief explanation on why GW are actually produced. regards

Today, all of the scientific world (including /r/physics) buzzes about BICEP2's discovery of gravitational waves dating from Big Bang as an undispute confirmation of the general relativity. Now I wonder is it really GR? Can't it be explained by simple Newton's mechanics? I mean if you can...

Null results so far for the elusive gravitational search, but were they expected to be found at this range? arXiv:1402.4974 (cross-list from gr-qc) [pdf, ps, other] Implementation of an F-statistic all-sky search for continuous gravitational waves in Virgo VSR1 data J. Aasi, B. P. Abbott, R...

Owing to the Hamiltonian constraint in general relativity, the total energy is zero. (To avoid ambiguity, here energy is DEFINED as the corresponding part of the ADM Hamiltonian.) Since matter has positive energy, it implies that gravitational field has negative energy. Does it mean that...

My understanding is that there is currently a large amount of money being spent on different experiments to detect gravitational waves. From all the articles I've read , they all describe these waves getting weaker as you travel further from the source. So my question is does anybody know of any...

From my own(simplistic)perspective,dark energy is expanding the universe by creating further spacetime at a velocity faster than the speed of light,if gravitational waves propagate at the speed of light how is it possible that M31 and the milky way are still bound by gravity when the fabric of...

Are gravitons and gravitational waves analogous to photons and EM radiation?

If a huge wave of space-time hit, let's say a space ship, what would theoritically happen to it? Would it be pushed away like the way air do, or would the spaceship itself ripple as if it is woven into spacetime?

Alright, so I have been reading about gravitational waves and have a silly question to ask. Suppose, hypothetically, under the right conditions you were standing somewhere on the surface of the Earth and a gravitational wave were to pass through the area of space you were occupying...would you...

According to this: http://en.wikipedia.org/wiki/Gravitational_radiation Inspiraling binary stars create gravitonic waves. This leads me to ask: If an amount of material with sufficient mass is accelerated to an extremely high speed (ideally a percentage of C but everyone knows that's...

Hi not sure if this is GR or cosmology, does anyone know what the gravitational wave equation is for GW's produced during cosmic inflation is it just \ddot{h}+2H\dot{h} +k^{2}h=0 because this is derivable using the FRW metric which isn't valid during inflastion, does this govern the...

I have a doubt about this, what is actually detected by a GW detector is a specific change in length (δl) in the arms of the interferometer due to the motion of the test masses being affected by the passing wave. But this variation is not of the proper length which is not uniquely defined in GR...

This may be a stupid question, but why can't the expansion/contraction of spacetime from a gravitational wave be used to create the areas of expansion/contraction required in the Alcubierre metric, instead of using regions of positive/negative energy density? I saw on the forums about the...

Hi, Guys. So i am doing a research paper on gravitational waves. As I read through review articles on gravitational waves and LIGO, I don't quite get a few points. The materials are really dense and I don't have the math and physics level to back it up. But I am really interested in the topic...

This is a question about electromagnetic waves and gravitational waves. Let's say we're on the Earth and we're looking up at the sun (safely). If the sun were --for some reason-- to violently and dramatically jerk from its position, how would we first find out? Would we first *see* the...

According to General Relativity, do gravitational waves penetrate black holes? My gut feeling says "no, if gravitational wave goes under event horizon, it won't re-emerge", but I'm not an expert...

2 closely orbiting massive objects are predicted to deserve the fabric of spacetime so much that they will release a ripple of gravitational waves. When geavitational waves are released, they slowly loose velocity energy and spiral into one another. 2 pulsars were discovered orbiting each other...

Hi, it's my first post here, though I've long viewed these forums without a registered account. I was thinking about gravitational waves, and what exactly they would do. From what I understand, these waves affect everything with mass in the universe. The force they exert is exponentially...

Has the Planck satellite observed any gravitational waves yet? I'm pretty sure that gravitational waves were formed when gravity split from the other forces at 10^-43 seconds but I could be wrong. Anyhow, if we do detect them, will we be looking at the first Planck time in our universe's...

What speed do gravitational waves travel in matter. Is it a little less than c. Are their certain objects that slow it down a lot.

In his article The Ricci and Weyl Tensors John Baez states that the tidal stretching and squashing caused by gravitational waves would not change the volume as there is 'only' Weyl- but no Ricci-curvature. No additional meaning is mentioned. But, beeing not an expert I still have no good...

Can anybody explain me those contradictions. 1.If gravitation has speed = c and spread in form of gravitation wave. How it can escape Schwarzschild radius in black hole? 2. Magnetic field for black hole - how it can be possible? What create magnetic field? 3. Electrically charged black hole...

Gravitational waves theoretically effect themselves due to "self-gravity" http://arxiv.org/abs/0704.1149 I thought this was interesting. From a layman's perspective, a wave is a bundle of energy distributed through the medium it's traveling through. In the case of gravity waves (which...

I'm not a physics student (I was a long time ago) but I find the General Relativity subject extremely interesting. I'm very interested in the way the (I don't even know how to call it) "fabric" (the another dimension used to represent objects' gravity/energy) behaves. For example when I...

Hi A topic came up in a lecture the other day about how if certain simplifications are made, then the Einstein equation reduces to a form of the wave equation. When I look at derivations of how this happens, I get a little confused as to how this happens. I think I'm posting it in the...

Hello every one, This might sound as much stupid as it is confusing for me. Suppose the sun vanished right now (that would not happen practically, but I'm not concerned with that), then it will not be less than approximately a little more than eight minutes for us to know that the sun has gone...