Gravity is an attractive force that affects and is effected by all mass and - in general relativity - energy, pressure and stress. Prefer newtonian-gravity or general-relativity if sensible.

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What does the presence of gravity waves show?

Is the essence of the discovery of gravity waves that we now know that gravity propagates through space at the speed of light and not instantly?
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What will a true law of gravitation look like?

Newton's law of gravitation and Einstein's general relativity (GR) are empirical laws of gravitation that are strong on description and prediction but lack deterministic and/or causal rigor, which ...
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Gravitational waves in other dimensions

I know this question is purely speculative, as we don't know if more dimensions do exist and also we do not know if gravity is indeed stronger in other dimensions (if they were to exist). But, one of ...
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Is the expanding of the universe also a cause which can induce gravitational waves from mass?

Gravitational waves arises when mass is rotating in another mass'orbital, in explosions and of course in case of colliding black holes. But are they also created when mass is moving and speeding ...
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Are gravitational waves effected by the curvature of space time (gravitational lensing)?

I have a basic question I can't seem to find anything on (I keep hearing about how gravity waves and gravitational lensing were both predicted by Einstein). We all know about the gravitational ...
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Are gravitons affected by the force of gravity?

Every particle, including photons, is affected by gravity. Would this be true for gravitons as well? Gravitons should always move at the speed of light, so, if photons are red-shifted while moving ...
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Why are the arms of the LIGO interferometer so long?

The LIGO experiment consists of two interferometers, where each one of them has two 4 km long arms. Within these, light is further trapped via Fabry-Pérot cavities to achieve a total path length of ...
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What was the frequency of the gravitational wave recently detected, and why?

In one early Internet post there was a graphic that appeared to show the gravitational wave (pulse) at about 30 cps. And another video it was stated that the gravitational wave would be as high as ...
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What is the isochronic law of pendulums? [on hold]

I think the Isochronic law of pendulums is related to law of isochronism in thermodynamics: //physics.stackexchange.com/
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G4v Gravity Wave vs General Relativity vs LIGO Observation

CalTech emeritus professor Carver Mead produced an alternative prediction, to General Relativity, for gravitation wave observation which he published last year in anticipation of LIGO observations. ...
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Prospects for detection of gravitons?

With the announcement of the detection of gravitational waves, questions about the implications proliferate. Some relate to the possible existence of gravitons. The analogous relationship between ...
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How do gravitational waves and black holes interact?

Following the first detection of gravitational waves yesterday (11 Feb. 2016) by LIGO, I have a couple of questions about how gravitational waves and black holes interact. Assume that there is a ...
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Is it really just a gravitational wave that curves spacetime or is there also something else involved?

Gravitational waves are quadrupole waves which can stretch and sqeeuze space. So when a wave is passing through you you get taller and thinner and shorter and fatter. Like on a water wave you get up ...
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Why does a curved spacetime result in a movement?

If gravity is not a force but a curvature of spacetime, where does the motion towards the center of gravity come from? To put it differently, why would two objects in a space fall towards each other ...
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Is it possible that there are still gravitational waves of the big bang?

We already discovered the cosmic background radiation what are the 'leftovers' of electromagnetic radiation of the big bang. Probably gravitational waves of the big bang (if they exists) would be to ...
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Bondi mass aspect

I'm looking for a good reference that defines the Bondi mass aspect and his relations to Bondi and ADM mass. Googling a bit I've not founded any satisfactory exposition of the subject. A short ...
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What is the effect of gravitational waves on time? [duplicate]

I always struggle with the time concept when it comes to general relativity. In the recent discovery the gravitational waves have been detected by the "displacement" of the mirrors and the difference ...
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1answer
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How much force is required to produce a noticeable gravitational wave?

By noticeable, I do not mean noticeable from half way across the galaxy to our observatories, but noticeable as in, if there were an object with enough mass and energy within say, the distance of our ...
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Will the photon wavelength fluctuate in the presence of a gravitational wave?

The microwave background is due to the expansion of the Universe where the wavelengths of radiations are stretched by spacetime. As in the LIGO experiment, in the presence of gravitational wave, ...
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Why are Gravitational Waves so small?

I'm sure you've all seen the diagrams and/or 3D visualizations of gravity; the ball sitting on a piece of fabric which makes it sink down. They've also started using it in the videos that explain ...
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Does the existence (now proved) of gravitational waves imply the existence of Gravitons?

I studied the theoretical part about the Gravitational waves in General Relativity (linearization of gravity and small perturbations of the metric and so on). But I was wondering about: since ...
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In what shape do gravitational waves radiate?

The recent detection of gravitational waves made me wonder how the amplitude of the waves fell off with distance. My first naive thought was that it was probably by the cube of the distance. ...
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The existence of gravity waves has just been demonstrated by direct observation, 2016 [duplicate]

How does the apparent confirmation of gravity waves effect String Theory today
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What is the proof of gravity being curvature of spacetime?

According to general relativity gravity is an illusion caused by curvature of space-time, rather than real force. As I understand there is overwhelming experimental evidence to support general ...
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How did LIGO detect the source location of the black holes mentioned to be the cause of today's announcement?

Today LIGO announced discovery of Gravitational waves. What method was used to determine the source location of the waves?
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Does gravitational time dilation have a direction?

I understand that higher the gravitational potential, "slower" time runs. So a clock on international space station will run "faster" than a clock at sea level. However does it matter where the ...
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Graviton and photon

I understand that photon is the carrier of a change in the EM field. Is the graviton a carrier of the gravitational field itself or a carrier of a change in the gravitational field?
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How strong were the gravitational waves that LIGO detected at the source?

The articles I've read say that the distortion we see here is much smaller than a proton. What about at the source? Would these waves have been strong enough to see macroscopic effects near the binary ...
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How were gravitational waves discovered?

It was announced today that gravitational waves were discovered. The article gives the following explanation of the experiment: When a gravitational wave passes LIGO, the tunnels deform ...
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Meaning of $R=0$, $R_{ab}=0$. $R_{abcd}=0$.

First let me state some definition The Einstein tensor is given by \begin{align} G_{\mu\nu} = R_{\mu\nu} - \frac{1}{2} g_{\mu\nu} R \end{align} and note that \begin{align} G^{\mu}_{\phantom{\mu} ...
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Why do you believe in [on hold]

Is it possible that gravity doesn't exist?
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Integrating the geodesic equation to obtain Newtonian energy of test particle

I am studying General Relativity, and have come across a question that I am finding rather intractable: In Newtonian Theory, the energy equation for a test particle in orbit around a point mass ...
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Does gravity have two directions?

Imagine a particle that interacts strongly with gravity, but not with any of the other forces, and does not interact with normal matter (this may be analogous to the description of dark matter, I'm ...
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If gravity is additive, then how does it cancel itself out?

I understand that gravity, as far as we know, is always attractive. Also, it has additive qualities - i.e. the size and strength of the field are proportional to the quantities of mass. This seems to ...
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identity : $ \epsilon_{abcd} R^{cd}_{\phantom{cd}mn} = \epsilon_{mncd} R^{cd}_{\phantom{cd}ab}$ in vacuum

starting from \begin{align} \epsilon_{\rho\lambda\xi \kappa} R^{\xi \kappa}_{\phantom{ab} \sigma\tau} + \epsilon_{\rho\sigma \xi \kappa} R^{\xi \kappa}_{\phantom{ab} \tau \lambda} + \epsilon_{\rho ...
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In the process of Bel-robisons tensor: identity for $R_{amnk} R_{b}^{\phantom{b}mnk} = \frac{1}{4} g_{ab} R_{dmnk} R^{dmnk}$

Recently, i an starting to study some subject related with Bel-Robinson tensor. In the process of computing its some basic properties i noticed i need to prove following identity which holds on ...
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gravitational force and irreversibility

If we place a ball at a certain height it falls and the process is irreversible. Is there any entropy change associated with the falling of ball? If so why?
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Calculating Gravity: Small scale vs Large scale

In some calculations I've ran, I've noticed that when the gravitational forces between individual particles are calculated and when the gravitational force between bodies are calculated there tend to ...
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Why do stellar boundaries exist?

What theorems or insights are available to decide wether a star with some given interdependence between its density, pressure and temperature distributions ought to have a boundary at a finite ...
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Liquid jet in the absence of gravity [on hold]

On earth, we have liquid jets which are falling and accelerating under influence of gravity ( this cause their radius to decrease ) My question is about liquids in the absence of gravity. Can we make ...
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Why is it difficult for 2 black holes to merge?

Apparently as part of the merger of galaxies, sometimes the central supermassive black holes of colliding galaxies get really close, however once they come to a distance of about <1 parsec, it ...
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What would be the research advances if we discover the gravitational waves? [closed]

As researchers of LIGO (USA) and VIRGO (France/Italy) say that they have discovered gravitational waves thanks to black hole collision today, what would be, apart of the important confirmation of ...
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Weight of mass falling through liquid

If I place a container of fluid on a scale and drop a non-buoyant mass into the fluid, will the scale read less as long as the mass is in motion downward as compared to when the mass is at rest on ...
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Work by Gravity using Tensors [closed]

Now I'm familiar with the various methods for deriving work done by gravity, but I noticed a few things about the situation, and wanted to see if I could properly apply a tensor treatment to the ...
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Freely falling body applied some external force [closed]

A body of mass $10kg$ is thrown upwards with initial velocity = $10m/s$. Then it moves up and falls back down at the same point, after which an external force of $10N$ is applied in the upward ...
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Would the Moon be able to take water from Earth?

I know that if you add mass to the moon, it would get closer to the Earth. We all know that the moon causes the tides because it's gravity pulls the water. So, my question is: If the moon gained more ...
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Could a satelite be pulled away by gravity while the object it was orbiting keeps unaffected in its own orbit?

I'm asking this, since I try to educate my self a bit in the field of astrophysics. From my point of knowledge the by title given scenario could occur. But I haven't yet read anything that sounded ...
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Virtual particles, gravity, and dark matter? [closed]

In Hawking's radiation, virtual particles respond to intense gravitational tidal forces with pairs being ripped apart. One crosses the event horizon and the other escapes. On the other hand, in ...
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How do stars from far away affect Earth?

I know that we obviously get light (or we wouldn't be able to see them), but are there any other ways that they affect Earth and maybe just our solar system in general?
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Gravity, Acceleration, Time Dilation and the Equivalence Principle

Three clocks are started at exactly the same time on Earth. The first and second clocks are taken into the vacuum of space. The first clock accelerates until it reaches 100,000m/s, then stays at this ...