Gravitational waves Definition and 332 Threads

Please, help here people. Im reading this article Wave Optics in Gravitational Lensing (T. T. Nakamura, 1999) . In the article start work with \begin{equation} (\nabla ^2 +\omega)\tilde\phi = 4\omega^2U\tilde\phi \end{equation} where $$\tilde\phi = F(\vec r)\tilde\phi_{0}(r)$$. Using...

Like the title said, is there a way at all to use gravity waves as a way to transport us to other stars??

<Moderator's note: thread spawned from this previous thread.> I have a question only loosely associated with any of the above, but that I hope may interest the minds behind this discussion. Does the apparent discovery and confirmation of gravity waves give us a source of information...

Ivette Fuentes and her group are attempting to use phonon excitations in BECs to detect gravitational waves. Their GW-detector is called MAGA, which stands for Micrometre Antenna for Gravitational-wave Astronomy. Here's a video of her explaining it: More from their blog:

Can someone recommend me some beginner/intermediate level books about gravitational waves and some articles about their discovery. I need to write scientific paper about them for my graduation but i don't have resources where to find about them so i would really appreciate help :)

Homework Statement Two plane gravitational waves with TT (transverse-traceless) amplitudes, ##A^{\mu\nu}## and ##B^{\mu\nu}##, are said to have orthogonal polarizations if ##(A^{\mu\nu})^*B_{\mu\nu}=0##, where ##(A^{\mu\nu})^*## is the complex conjugate of ##A^{\mu\nu}##. Show that a 45 degree...

http://www.bbc.com/news/science-environment-39212305

As per the above figure coil A is situated inside a magnetic field caused by small accelerating objects B which in turn are causing the larmor frequency in coil Object C or train of objects C have quadruple movement and are rotating around the coil A giving out gravitational waves. Objects C...

So a spherically symmetric object, by Birkhoff's theorem, does not emit gravitational waves. Is this why we look to binaries, so that there is some rotation of the objects with respect to each other breaking the spherical symmetry? Or mainly because the gravitational radiation is much greater...

I have been through following papers for research: 1)http://cdsads.u-strasbg.fr/cgi-bin/nph-iarticle_query?1990ApJ...362..584M&amp;data_type=PDF_HIGH&amp;whole_paper=YES&amp;type=PRINTER&amp;filetype=.pdf 2)https://arxiv.org/pdf/gr-qc/9905054.pdf Conclusion of the second paper given above...

It occurred to me that if the speed of gravity is the speed of light, then the universe must be accelerating due to Dark Energy, What my question is do we know the frequency of gravitational radiation, If we do then any compression or expansion of these waves will change the cosmological...

Something is wrong in my understanding of Relativity. There is an equivalence idea running around, which says that gravity and the distortion of space time by gravity waves acts the same way on all things. That would mean that all objects and light and space experience the same distortion...

https://arxiv.org/pdf/astro-ph/0006077v2.pdf page 5. Tensor Perturbations "Tensor perturbations do not couple strongly to the thermal background and so gravitational waves are only generated by quantum fluctuations, as in standard supercooled inflation". Why? Tensor perturbations are created...

I understand that any source of gravitational waves loses energy, which is carried away by the waves. But since the waves are perturbations in spacetime rather than a physical field, they cannot carry energy the way photons do. I have read that this used to be a source of considerable...

I'm confused about how the predictions of this graph were formed. I have this formula: But the change in frequency per second is about : 2x 10^-12 which has a problem because when you multiply this by 10 years you don't even get a change of frequency of 1/1000 of a second and in the graph it...

https://www.ligo.caltech.edu/video/gravitational-waves How do gravitational waves get emitted here? Is it in a sphere or on a flat(?) surface?

In the paper Advanced LIGO they published some figures with chances. I would like to know how they know that there's a 90% chance for something to be in a specific value. https://dcc.ligo.org/public/0122/P1500218/014/PhysRevLett.116.241102.pdf paper here also have some other questions: What...

I have some questions about the first discovery paper that was released about gravitational waves, especially some of the maths. How did they: 1. Calculate the masses of the black holes that merged 2. Calculate the energy radiated away in gravitational waves 3. Calculate how far away the event...

What would happened if the speed of gravitational waves were not equal to the speed of light . Please explain it with example of sun and Earth or any other but in easy way. With reference to general relativity.

Hi all, On the subject of being able to feel gravity waves as a human without machines, I couldn't find a very definitive answer to what I was looking for. First, I reference the video: at 40 tp 55 seconds. Its called: LIGO, journey of a G wave. They say in this clip that when the black...

By reading on the internet I ve found various websites talking about the relation between gravitation and electromagnetism, and in particular, under: - "Small" Gravitational fields -"small" changes in energy with respect to time, The linearized enstein' s field equation becomes pretty much...

This is a quote from an article written by a Phd student in physics in the online magazine Aeon (https://aeon.co/ideas/gravitational-waves-will-bring-the-extreme-universe-into-view): "Consider the properties of the September 14 event: the signal was generated by two objects, each roughly 35...

I understand gravitational waves as ripples in spacetime. As PeterDonis said in an earlier post, " The 4-d spacetime geometry does not have to "propagate" anything; it just is." On the other hand, this is block-universe speak. In this language, verbs that imply change are forbidden. We might...

If the amplitude of gravitational waves, frequency of gravitational waves and the vector potential of magnetic field in surrounding of such waves are known then what would be the easiest way to calculate resultant acceleration of electrons? My above question is based on the various researches...

Hi when i found out about the presence of gravity waves, i first thought 'what happens if they were to be reversed' and then i thought 'what happens to space time in between these waves?' thanks

A while ago, robphy posted a link to a paper by Saulson describing a "step" gravitational wave described by the metric ##ds^2=-dt^2+[1+h(t)]dx^2+[1-h(t)]dy^2##, where ##h(t)=h_0H(t-\tau)## is a step function of (constant) height ##h_0##, with the step occurring at ##t=\tau##. Presumably...

Join some of the very scientists responsible for this most anticipated discovery of our age and see how gravitational waves will be used to explore the universe like never before.

So we know that in GR electromagnetic waves have their trajectories effected by the gravity of stars and planets. But how about gravitational waves. Are their trajectories altered by gravity? If so, would this imply that gravitons are self-interacting if they exist?

First let me be clear, I am not questioning GR or the detection of gravitational waves by LIGO, I am trying to improve my own understanding of GW to the point where I can offer a graphic illustration (web video) showing what they do as they pass us to help others understand them. I started this...

The Michelson-Morley Experiment (as depicted in the scishow YouTube video "The Greatest Failed Experiment Ever") which was used to test for the effects of 'Aether Wind' appears to be almost, if not completely, the same setup as the one used in a gravitational-wave observatory. Why is the success...

Hi, First: I'm pretty sure my question has been asked numerous times, so I'm absolutely happy with links to other threads. I've used search but it didn't come up with satisfying responses, probably mainly because I don't really know what search terms to use. So the question is: How can a...

Hey! I am about to start my Bachelor's thesis about General Relativity. My professor mentioned that my thesis might as well be related to Gravitational Waves. Do you think that it would be appropriate to work on Gravitational Waves for a Bachelor's thesis? Isn't it too advanced? Also, any idea...

Since the thread In LIGO’s pulse, how much comes from BH merging/ inspiraling where I questioned the late ‘ringdown’ part of the LIGO signal, scientists have pointed out that the main pre-merging signal could indicate various types of binary compact objects, including gravastars of similar mass...

If things such as quantum entanglement and the expansion of space can travel faster than light, then why can't gravitational waves, which are vibrations of spacetime? I thought that only matter cannot move through space faster than light. Also, has it been 100 percent proven that gravity waves...

Suppose two masses are connected via a really strong spring, where one of the masses undergo an acceleration towards a relativistic speed, by say a rocket that leaves the scene soon after. When in isolation, (the two masses), they exhibit a sinusoidal oscillation to and fro. What is the...

OK, so it's time to start a new thread. I heard many times that there exists only one black hole solution for a given mass and angular momentum, but I know already that this is not true. We all know that if we throw something into an existing black hole, its event horizon starts to ripple. So...

Sorry for the amateurish setup that follows. Here's my thought experiment. Consider a 2-dimensional universe on the Cartesian plane. Earth is located at point (0,0). There is a binary system {A,B} oscillating around (1,1). To simplify, assume that the oscillation is 1-dimensional and occurs on...

This is something I've been curious for some time. I've heard that there is a relation between gravitational waves and black holes. Moreover, this year the quite important paper "Observation of Gravitational Waves from a Binary Black Hole Merger" was published. Now, I'm starting to study...

Currently I'm in the last year of the Physics course and I'm interested in working on some undergraduate research project. At first I was suggested to work with statistical physics, but I believe I would prefer working with General Relativity. From the point of view of background I do have a...

To me, it seems that with our current technology it would be difficult to observe the speed of gravitational waves. Can anyone correct me if I am wrong?

hello, I was reading a recent article about gravitational waves and I had a few questions... I actually have a lot of questions, but I digress. Let me first start with what I think I know to be right, and then move on to the questions about the subject. -Time and space are connected. This...

The inspiralling oscillations of ~20ms period (reducing to ~5ms) appear much stronger than the ringdown of ~ 3ms period (noisy, at resolution limit). Merger happens at ~440ms in the figure of Abbott et al. (Phys Res Lett link.aps.org/doi/10.1103/PhysRevLett.116.061102). This would agree with...

Hi all, this is my first post so before my question I want to show my appreciation to this community for offering a great framework to talk physics between experts and others who chose different life career paths, such as me. I have always loved physics but the math... not that much. English is...

In 1916 Einstein has published the first paper of gravitational wave bu linearize approximation but It contain an error of his calculation then In 1918 he published a new paper of gravitational wave that has a correction of the his last error and conclude that there are the Gravitational wave...

Does the fact that orbital electrons are stable suggest that gravitation is quantized, analagous to the observation that the stability of orbital electrons suggested that electromagnetic energy was quantized?

What would happen if I were to fly toward a gravitational wave pulse at relativistic speed? Would I be destroyed by the Doppler-shifted pulse? Would the wave become visible?

In the most recent postings on LIGO, it is stated that the amplitude of the signal is less than the diameter of a proton after the propagation of the wave over billions of light years. I am assuming that the wave amplitude will decay as 1/r^2, but perhaps that is an incorrect assumption. So is...

Hi, previously at Cardiff Uni, now at Buckingham, I'm still interested in gravitational fields, waves, Einstein, LIGO and all that.

Hi folks. I see there is a similar thread on grav waves and time, but I have a few specific questions. Everyone talks about grav waves "in space" -- even Brian Greene was saying this on Colbert, whereas Colbert was saying spacetime. I would like to make a video on how GWs are indeed "waves in...

I was told that there are two kinds gravitational waves. One dies out as 1/r, another one dies out as 1/r^2. The former is what LIGO detected, the latter is not. While I trust the professional qualification of the person very much, as a non-physics professional, I would like to a second person...