A theory that describes how matter interacts dynamically with the geometry of space and time. It was first published by Einstein in 1915 and is currently used to study the structure and evolution of the universe, as well as having practical applications like GPS.

learn more… | top users | synonyms (1)

4
votes
1answer
28 views

Why gravitational waves are not produced by objects moving at constant velocity?

Gravitational wave is produced by change in gravitational field, source. If something is moving away from me at constant speed, its gravitational field will vary. But why only accelerating bodies ...
0
votes
0answers
8 views

Multi Dimensions - Relativity

Now is a fact that our galaxy is moving at lightspeed relative to other huge bodies in the far universe. If we accelerate to c/2 to a determined xyz vector, is there a possibility any bodies that are ...
0
votes
0answers
12 views

Numerical simulation of strong field gravitational vacuum solutions colliding

I am interested in the current state of knowledge of strong field General Relativity learned from numerical investigations of gravitational wave packets colliding with each other or black holes. If ...
1
vote
1answer
82 views

Is it pure luck to observe a gravitational wave?

I actually have two questions: Since only a gravitational wave that is strong enough can be detected and the GW passes by the earth at light speed, can I say that we are lucky to detect one this ...
0
votes
1answer
27 views

What does the presence of gravity waves show? [duplicate]

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?
8
votes
1answer
188 views

Is there a “CGBR”?

The recent discovery by the LIGO made me wonder about this. We know that there exists a CMBR, Cosmic Microwave Background Radiation, a blanket of electromagnetic energy covering the universe, made by ...
-8
votes
2answers
51 views

What will a true law of gravitation look like? [on hold]

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 ...
0
votes
0answers
34 views

Energy Conversion from Mass to Gravitational Wave

How is mass converted to gravitational wave energy by inspiralling binary black holes? Is the gravitational wave energy coming purely from the kinetic energy/gravitational potential of the two black ...
0
votes
0answers
26 views

Why is it said that the cosmic censorship hypothesis depends on the future evolution of the spacetime?

I am reading a bit about the cosmic censorship hypothesis and I came across the following statement: Cosmic censorship is precisely a statement on the global future evolution of a spacetime. My ...
0
votes
1answer
28 views

Schwarzschild manifold

I am given the following metric $$g = \frac{dr^2}{1-2m/r} + r^2dS,$$ where $dS$ is the standard metric on the sphere $S^2$. I am told that this is isometric to $\mathbb{R}^3$ or (taking its ...
0
votes
1answer
31 views

Is the cosmological time grosso modo isochrone?

Is the cosmological time grosso modo isochrone? by analogy with space isotropy. Or else do we have possibly great differences by analogy with great voids in the space. We know that it's not strictly ...
4
votes
1answer
33 views

Black hole singularity from collapsing light vs dust

Consider two black holes, one formed from a spherical cloud of electromagnetic radiation, and one formed from a non-interacting dust solution. The stress energy tensor is traceless for ...
0
votes
0answers
40 views

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 ...
1
vote
0answers
24 views

Acceleration 4-vector in Schwarzschild metric [on hold]

I am working on A note of a paradoxical property of the Schwarzschild solution by Abramowicz M. A. and Lasota J-P It is a note on surprising cases in the context of the standard Schwarzschild ...
3
votes
0answers
68 views

Are gravitational waves dissipated and what is the mechanism?

I was amazed by the fact that we have been able to detect gravitational waves created thousands of year before they were observed. My surprise is that any wave phenomena I know it is always ...
0
votes
1answer
53 views

How much time distortion was caused by GW150914?

I understand (at least I think I understand) that LIGO used distortion of space to detect GW150914 (one arm grew longer, the other arm grew shorter, causing interference in the returning laser-pulse ...
0
votes
0answers
34 views

Path of light and gravitational waves

Now that gravitational waves are detected, the way they are detected was using laser beams and they were out of phase when the return from the same trip distance. Does this means it is based on ...
0
votes
1answer
39 views

How would a galaxy “bathing in radiation” behave?

For the sake of understanding mass and radiation interaction, I hope somebody could explain how this hypothetical situation would look. I want to exaggerate the amount of photons, assuming that there ...
4
votes
2answers
98 views

Do the photons emitted along with the gravitational waves take more time to reach earth than the ones emitted after them?

I'm puzzled because the gravitational waves do warp the spacetime locally. They do it continuously as they propagate. So the photons travelling in tandem with these waves must be constantly following ...
1
vote
1answer
42 views

General Relativity, Curvature, and extra dimensions

Setup of idea I had somewhat of a thought question regarding general relativity. Consider a simple situation of a sphere and arrow. You hold the arrow and walk from the equator to the north pole. ...
4
votes
0answers
101 views

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. ...
0
votes
0answers
44 views

LIGO event - energies involved?

So, we have two Black Holes merging shortly after LIGO turns on after the upgrade. Some questions: a) How lucky was it to see this event? What are the expected rate of occurrence? b) Was this event ...
1
vote
2answers
85 views

How were the solar masses and distance of the GW150914 merger event calculated from the signal?

The GW150914 signal was observed, giving us the frequency and amplitude of the event. Because LIGO has two detectors a rough source location could be derived. But how do these three factors allow for ...
0
votes
0answers
40 views

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 ...
0
votes
0answers
8 views

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 ...
2
votes
1answer
45 views

In GR what is a “source-frame mass”?

In the recent LIGO paper, "GW150914: First results from the search for binary black hole coalescence with Advanced LIGO, (LIGO Scientific Collaboration and Virgo Collaboration)", they refer to the ...
0
votes
0answers
44 views

Is it accurate to say that nothing can travel faster than c in a GR context, where more space can be created?

Years ago, my brother and I had an argument where I was trying to convince him that nothing could travel faster than the speed of light. I was pursuing this in the context of Special Relativity. My ...
0
votes
0answers
19 views

Can we always effectively describe a timelike worldline (non-geodesic) in one spacetime as a geodesic in some other spacetime?

Can we always effectively describe a timelike worldline (non-geodesic) in one spacetime as a geodesic in some other spacetime with a different metric? Is this implied by the equivalence principle ...
0
votes
0answers
90 views

What are the implications of today's direct detection of gravitational waves?

Here is the announcement from today's Physical Review Letters by Abbott et al.:"On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory ...
0
votes
0answers
35 views

What would it look like if the earth were suddenly put on the anti-node of a gravitational standing wave with a huge amplitude?

What would it look like if the earth were suddenly put on the anti-node of a gravitational standing wave with a huge amplitude? Can gravitational standing waves even exist? Say if there were two ...
0
votes
1answer
83 views

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 ...
5
votes
1answer
219 views

How is it that distortions in space can be measured as distances? [duplicate]

Imagine yourself and anything you're able to perceive to be drawn onto a rubber band. Any means of determining distances would be affected by the stretching/contracting of the rubber band. The ...
-3
votes
0answers
47 views

Gravitational waves now detectated [duplicate]

Based on the information released so far, have we learned anything new from the detection of gravitational waves at LIGO?
0
votes
2answers
90 views

At which point are gravitational waves generated when two black holes merge?

I was reading today's announcement of the gravitational waves and was wondering about this situation where there are two orbiting black holes. Did the wave come from the final merging or was it from ...
4
votes
0answers
147 views

Einstein's original papers predicting gravitational waves?

I came across the original handwritten papers in which Einstein predicted gravitational waves1: and since LIGO announced they've detected a signal confirming the predictions I was wondering if ...
18
votes
3answers
2k views

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 ...
2
votes
2answers
113 views

What will be the role of gravitational waves in future physics? [on hold]

What does this discovery mean for us? Can it lead to a better understanding of the cosmos?
96
votes
7answers
7k views

Why is the detection of gravitational waves so significant?

Since there is to be an announcement by LIGO about this today (11 Feb. 2016), I was wondering why the detection of gravitational waves was so significant? I know it is another confirmation of ...
0
votes
1answer
57 views

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} ...
0
votes
0answers
17 views

event horizon vs apparent horizon ramifications

If the event horizon doesn’t exist in the 2-dimension or 3-dimension time-space - and it doesn’t exist if it can’t be measured or observed - then an apparent horizon would be necessary to reconstruct ...
3
votes
0answers
52 views

Extrinsic Curvature of Surface of Codimension > 1 [migrated]

We can define the extrinsic curvature of a codimension-one surface as $$K_{ab} = q_a^{\phantom{a}c} q_b^{\phantom{b}d} \nabla_c n_d,$$ where $n^d$ is the normal vector to the hypersurface and ...
1
vote
1answer
30 views

Looking out from a collapsing star

From the perspective of the surface of a collapsing star, if you were riding it in as it formed a black hole, what would you observe looking out into the rest of the universe? As you approached the ...
0
votes
1answer
44 views

How do I derive geodesic equation using variational principle? [duplicate]

I am trying to derive the geodesic equation using variational principle. My Lagrangian is $$ L = \sqrt{g_{jk}(x(t)) \frac{dx^j}{dt} \frac{dx^k}{dt}}$$ Using the Euler-Lagrange equation, I have got ...
0
votes
1answer
53 views

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 ...
6
votes
2answers
699 views

Evidence for quantum gravity from gravitational waves

The rumor spreads that physicists will make their big gravitational wave announcement this thursday. I am far from being an experimentalist, but I want to know if there is any chance that the ...
1
vote
0answers
43 views

Are objects like $a^{\mu \nu} a_{\mu \nu} b^{\mu \nu}$ consistent with Einstein summation?

I'm familiar with Einstein' summation notation and I understand objects like $a^{\mu \nu} a_{\mu \nu}$ just fine. But I'm wondering why I've never come across objects like this: $a^{\mu \nu} a_{\mu ...
-1
votes
6answers
157 views

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 ...
-3
votes
3answers
59 views

Twins paradox question [duplicate]

In the twins paradox, the twin that travels away from earth comes back to find that his (her) twin has aged much more due to relativity's effect on time. Why can't we posit that it is not the one twin ...
0
votes
0answers
36 views

What is conformal symmetry physically?

I'm reading a paper by t'Hooft http://arxiv.org/abs/1410.6675. There is an argument in the paper that I could not understand: "Now that system, described by Maxwell’s equations, does have conformal ...
1
vote
1answer
34 views

In the orthonormal tetrad method, what is the relation between basis one forms and commutation coefficients?

If $\omega_i$ are dual basis one forms corresponding to an orthonormal tetrad basis $e_i$, and given that the commutation coefficients $C_{ij}^k$ are defined by \begin{equation} [e_i,e_j]=C_{ij}^k ...