Gravitational waves Definition and 332 Threads

You're on Earth. You throw a ball and watch its trajectory. It's curved. That's because the Earth is curving space-time at every point along the trajectory. But the Earth itself is not present along the trajectory - there is no matter along the trajectory (let's ignore the air and any radiation...

I wonder why electromagnetic waves don't escape from a black hole while gravitational waves (obviously) do. What is the difference between the two kind of waves? And between gravitons and photons? thank you for your attention

I am reading the following paper on the basic physics of a binary black hole merger: https://arxiv.org/ftp/arxiv/papers/1608/1608.01940.pdf Imagine two black holes orbiting each other until a point they merge. As you can see in Figure 1, the wave period is decreasing and thus the frequency...

Gravitational waves are produced by accelerating masses. Since all space is curved -- more curved near large masses stars, less curved in intergalactic space -- all moving masses are being accelerated to some degree. Do all moving masses therefore produce gravitational waves? If they do, will...

Two black holes that are orbiting and collide give off mass in the form of gravitational waves before the collision. Do these waves get absorbed by something, or is this mass lost to the universe?

I am interested in studying at least the basics of gravitational waves. How much knowledge do I need to have about waves in general before procceding?

A few years go, we detected a gravity chirp from the collapse of binary black holes. The initial total mass was about 21.7 solar masses. The end result was about 20.8 solar masses. The difference was presumably contained in the gravity wave. I believe, under the right conditions, an object...

From what I have read gravitational waves are caused by the acceleration of massive object causing ripples in space time. What specifically causes this, and how does general relativity predict these. Does it have to be a high density of matter, or a large amount of it. How do these waves affect...

Hi, a simple question related to the gravitational wave detection. The net effect of gravitational wave is basically the stretching of the space including all the measurements tools (meter sticks just to illustrate the concept) that could be used to detect it. I am aware of laser...

How could we detect negative mass matter? The only proposal I've ever heard of is that we could detect there's a cutoff frequency in the gravitational waves we receive, due to attenuation of those lower frequency waves by negative matter. Are there more experiments that could be conducted...

When and how can the gravitational wave be used for data communication, which the speed be much faster than the current technology by means of electromagnetic wave like 5G, 6G..etc wireless systems ?

I am curious if the motion of massive object can effect it's gravitational influence due to the fact that gravitational waves travel at the speed of light. For a weak analogy, consider how a small object can make bigger ripples in the water if it is moving around more. I am curious if there...

Is it a fair prediction to state that in the next several years or so, globally, there will be major investments into gravitational wave research, and many more ‘LIGOs’ being developed? Is it a good idea to venture into that area of physics?

Assuming that the multiverse hypothesis is true and a singularity at the center of a black hole can give rise to another baby universe. Can we detect such an event in the LIGO observatory?

Conformal Cyclic Cosmology, or CCC, is a hypothesis put forward by Roger Penrose in the early 2000s. My understanding of physics is lacking so my explanation will not be that clear, but I will summarize it here. Essentially, the existence of a previous spacetime, or "aeon," is postulated. This...

I am looking at a couple of very interesting papers, published in MNRAS, that deduce, that the accelerated expansion of the Universe we observe can be attributed to gravitational waves, produced by a very distant merger of two or more universe-mass-scale black holes. The last one is on the...

When neutron stars collide, heavy elements, such as gold, are created. Are these elements ejected from the system to be found, say, here on earth? Or do they fall back into the newly created black hole?

I was doing a thought experiment last night. Gravitational waves, being like any other type of wave would cancel each other out and create a refraction pattern of strength. While we do not have definitive proof there is a black hole at the center of every Galaxy, we do know, through...

Are gravitons postulated to be excitations of gravitational waves? If so, and since gravitational waves have been unambiguously observed, then gravitons must exist, no? If not, then what is the postulated relationship between gravitational waves and gravitons? Are both deemed/postulated to...

it seems to me that during a high energy event that a space time compression wave would be created which would then normalize as it spread out. A particle on a back end wave would become close enough to the front end wave that it could tunnel between the two as "distance" is compressed. We...

well since gravity waves are supposed to have mass, they are supposed to be effected by gravity itself, and :/ how are we supposed to detect gravitational waves emitted from a black hole when none can get out?

I am curious as to what the maximum amplitude of gravitational waves is. I have read that the maximum amplitude as such is equal to two but I cannot seem to find again a reference that states this clearly.

Gravitational waves are quadrupoles, they bend and stretch spacetime. Does the expansion of spacetime due to gravitational waves exceed flat (Minkowski) spacetime or is flat spacetime it's limit?

I am doing a term paper on G. Waves and I have a couple of questions about them. - How do we know that the G. Waves detected by LIGO on September 14, 2015, come from 1.5 billion light years? - How is Einstein's Theory related to them?

Hello, Thank you for opening this thread. I am strongly interested in the universe, especially black hole. Though I am only eighteen years old, the more I read books about a black hole, the more my interest is getting powerful. Therefore, I want to know the latest and exciting news about...

From what I understand the LIGO experiments were the first in the road to demonstrating the existence of gravitational waves. There was a dicussion about this on Utube where someone pointed out that the polarized light scattered from dust, being much larger, could mask the the effect of...

LIGO is most sensitive to a GW from directly above/below. As a transverse wave hits an arm why don't the laser source and the mirror move in unison -- thereby covering up the distorted motion?

Does the event horizon of a black hole really represents the surface of the "star" (or mass) itself? What I mean to say is: That the event horizon is the (let's say it this way) sphere surface where the scape velocity is => than the speed of light. So it is not necessary for event horizon to be...

Is there any relationship between the Speed of gravitational waves and the Universe's "local" expansion rate? Speed of gravitational waves is supposed to be equal to the speed of light. Gravitational waves don't travel faster than light. But we can observe far galaxies moving away from us with...

Suppose a gravitational wave propagating through space encounters a strong magnetic field (for example the wave might pass through a magnetar with a B field strength of 10^{11} Tesla). Would there be any observable perturbation in the magnetic field itself? In other words would the gravitational...

My understanding is that gravitational waves have not been detected from the proposed inflationary epoch of the big bang, only from the merger of two super massive objects. Is that correct? Are GWs predicted from the big bang in models where there is no inflationary epoch? If GWs are detected...

Why are clocks not used to measure gravity waves? Spacetime wriggle and time must also vary. It is possible to measure time very accurately and with a high resolution. Så why not use clocks to detect gravity waves?

does any object with mass that moves create a gravity wave? So if I wave my hand it is in fact creating gravity waves, just very small ones

I'm aware that the LIGO system uses interferometry but I'm confused how it works in this case. Do they test both beams of light? Or do they use one beam to test the wavelength of the other and see the difference? Also it is sensitive up to 10 e-18 meters, is that for the change in wavelength or...

This thread is to serve as - a collection of theories that have been falsified by and/or have had new constrained placed on them by the ongoing gravitational wave measurements. - a place to discuss the further constraining/falsifying of still existing models using GW data. I'll start by posting...

I have no idea where this belongs or if it will be deleted but would Alcubierre drive cause detectable gravitational waves? And since I'm heading out on this limb would the direction of propulsion be indiscernible? As per the Wikipedia description it follows from a solution to the same general...

Since gravitational waves have energy, they can curve space all by themselves. I wonder in what conditions, if any, two gravitational waves could orbit each other. Thanks.

Dear all, In a recent talk, I have heard that speed of gravitational waves is non-dispersive. How is it proved "observationally" in LIGO detections that all the frequencies travel with the same speed, so one can say the speed is non-dispersive?

Is this accepted throughout the science community now? Is there any doubt that LIGO actually detected gravity in the form of waves?

Erebon theory is a novel explanation of dark matter recently invented by Roger Penrose. Erebons are scalar particles of the order of a Planck mass which can only interact gravitationally. When erebons decay, they release their energy as oscillating classical gravitational waves on the order of...

Just a thought I had...

Finally... this month, Virgo and LIGO look for gravitational waves together (they started yesterday). The Virgo detector is a bit less sensitive than the LIGO detectors at the moment, but it is still a big improvement: It is an independent experiment, on a different continent run by different...

It seems that with the 2016 LIGO and VIRGO confirmation of the gravitational chirp that we have also experimental confirmation that the speed is indeed the speed of light. True? https://en.wikipedia.org/wiki/First_observation_of_gravitational_waves#Direct_observation

Roger Penrose, July 2017. Correlated "noise" in LIGO gravitational wave signals: an implication of Conformal Cyclic Cosmology

I thought I understood the following, but recently I am having doubts about my understanding. https://www.physicsforums.com/threads/is-a-2-body-elliptical-orbit-stable-in-gr.898258/ @PAllen said: I don't believe any orbital system is stable in GR due to gravitational radiation. The time scale...

Hey all. Since gravitational waves travel at the speed of light, when they are "escaping" from mass, doe's their intensity lower? If so what mass would be needed to completely absorb a gravitational wave given the wave's properties? Any help appreciated.

What happens to the path of Earth if a strong gravitational waves hit earth. Would there be a possibility of Earth moving out/changing the path of its current orbit? Can a high frequency gravitational waves knocks the Earth out from sun's gravitational field? (I know it is very unlikely that a...

Hi, (all discussions here are in the extreme weak field approximation about Minkowski space) For the last couple of years I've been looking into the production and reception of radio frequency gravitational waves. It's kind of a retirement project the main goal of which is to get a better...

Homework Statement In-phase light from a laser with an effective power of 2x105J and a wavelength of 1064nm is sent down perpendicular 4km arms of the LIGO detector. (i) Determine the number of photons traveling in the interferometer arms. (ii) Assuming the detector is sensitive enough to...

Hi guys. I am having a little trouble understanding a few relations professor mentioned at lectures, regarding gravitational waves - flux of energy and strain. First one expresses how is the flux of energy F related to frequency of radiation f and inflicted strain h. And the second one is for...