Gravitational Definition and 1000 Threads

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?

I'd like to call attention to this paper: https://arxiv.org/ftp/physics/papers/0409/0409124.pdf I'm not trying to question the validity of GR in bending of light near a star (such as the sun), as this paper apparently does. But surely Newtonian refraction of light passing through the sun's upper...

Is it possible for a transition between two atomic states to proceed by emission of gravitational, rather than electromagnetic, radiation?

problem 3.8 Classical mechanics R.Douglas Gregory A narrow Hole is drilled through the centre of a uniform sphere of mass M and radius a . Find the gravitational force exerted on a particle of mass m which is inside the hole at a distance r from the centreF = GMm/r2(i) interior to a uniform...

Can someone please tell me how the energy field created by warped space (gravity) and centred at the Earth's core dissipates? Is it the pressure/compression of this force/energy that makes the core so volatile? Whilst time slows at altitude, do we become lighter, as we are further away from...

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

I'm looking for an expression for the deflection of light in a static gravitational field. Referring to 'deflection of star light past the sun' in Sean Carroll's "Spacetime and Geometry" - equation 7.80 for the "transverse gradient": \nabla\perp\phi = \frac{GM}{(b^2 + x^2)^{3/2}}\vec b...

As I understand, under Newtonian Gravity, there are no limits for the length of the gravitational influence of an object, except the speed of causality and the age of that object. So, considering the Sun as an example, which is roughly 4.6 billion years old, its gravitational influence would...

Dear all, I'm having confusion about the standard derivation of Schwarzschild's gravitational time dilation. For concreteness I'll follow the explanation of Schutz' "gravity from the ground up", but other texts argue the same. So let me rephrase Schutz's explanation (I surpress factors of c in...

I'm afraid I've come to a problem which I cannot solve. It concerns using gravitational lensing as a means of transmitting signals over interstellar distances. The real issue is finding the correct focal distance to make this possible. Now the only information I've been able to glean from the...

Homework Statement In Newtonian theory the gravitational potential Φ exerts a force F = dp/dt = −m∇Φ on a particle with mass m and momentum p. Before Einstein formulated general relativity, some physicists constructed relativistic theories of gravity in which a Newtonian-like scalar...

I have just glanced this magazine and got curious about what is gravitational lensing http://blogs.discovermagazine.com/d-brief/2017/06/07/19964/#.WYibwxWGO00 I am quite less knowledged in Astronomy, so explain me clearly!.:smile:

Just a thought I had...

Hello, I'm fascinated by gravitational lensing and would like to know what is the latest in this area - I mean the latest interesting research that lensing is used for, to help understand something or suchlike. Thanks.

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...

1. The problem is attached in a picture. I've done it five times and keep getting it wrong. The correct answer is also displayed in the picture. Thank you for any help. 2. Fg=Gm_1m_2/r^2 3. I calculated Fg between AB and BC (they are equal). So Fg=(6.67*10^-11)(4)(4)/(.10)^2=1.067*10^-10...

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

Is none detection evidence of no gravitational radiation?arXiv:1707.06755 [pdf, other] Reanalysis of the BICEP2, Keck and Planck Data: No Evidence for Gravitational Radiation J. Richard Gott III (Princeton University), Wesley N. Colley (University of Alabama in Huntsville) Comments: LaTeX (MNRAS...

Hi all, Since the gravitational acceleration varies depending on location, then how do you know if your scale is precisely calibrated? If I use a calibration weight (e.g. 100.000000 g) that was manufactured and tested around at equator where g=9.780 m/s^2, in my lab at the north pole where...

I know that the force of gravity is (ma)=GMm/r^2 or a=GM/r^2 This makes sense and If I were to drop a bowling ball down to Earth I'd expect it to fall with 9.8m/s^2. However I can calculate that the bowling ball has its own gravity using the formula noted above. My question is what will be the...

Please ignore strikeout (not sure why post is doing that) I just watched a video from Caltech (Video link at bottom of post) It says: Displacement = Distance Fallen in first second of time in [m] * Time2 so Time2 has no si unit as it is just a ratio right? Instant or Average Velocity = 2 *...

In a recent thread, the question came up of whether the presence of gravitational time dilation implies spacetime curvature. My answer in that thread was no: This was based on the obvious counterexample of observers at rest in Rindler coordinates in flat Minkowski spacetime; two observers at...

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...

Is anyone aware of a concise review of the experimental evidence of the nature of the gravitational field due to an entity in spatial superposition? Is it known (or generally presumed) that photons exert gravitational attraction through the stress-energy tensor at all points in space related to...

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.

Homework Statement Consider the Earth as 1. with a constant density of matter, 2. as a thin shell empty sphere and 3. with a constant linear density of matter ##\rho(r) = \rho_{0}r##. In all cases, calculate the gravitational potential and the gravitational field everywhere and make a...

I understand that gravitational acceleration is independent of mass. However, I've seen a common mathematical description of this that I can't help but find circular. I suspect that there's an error in my thinking that I'm hoping someone can point out for me. It goes like this; ##F=mg## but we...

Homework Statement Q7. Some lead shot with a mass of 50 grams is placed into a card board box the distance from one end to the other being 1m. The ends are sealed with rubber bungs in order to prevent the lead shots from falling out, the tube is rotated so the lead shots fall down from one end...

I'm sure you are familiar with Le Sages physics and how it predicts gravitational drag. But what if no velocity vector matters except the direct line between the two gravitational objects? Does this fix Le Sages theory?

The speed of light (in the vacuum) is a function of the permeability and permittivity of the vacuum. In other mediums the phase velocity will be different. It is assumed (by me) that the speed of a gravitational wave does not change depending on the medium i.e. a gravitational wave would not...

Since force is transformed via: F'x= Fx ; F'y= Fy/ ϒ; F'z=Fz/ ϒ (F' is the force related to the moving frame, F is the force on the rest frame and ϒ=1/√1-v2/c2 ).I expect that G (Gravitational constant) will be transformed between moving and rest frame in order to satisfy force transformation...

This latest observation of gravity waves has brought up a question with me.. Since gravity is a mass-caused distortion in space-time aren't these waves wave distortions of the space-time? I know there is no such thing as ether but for this analogy and my simple mind I'll use it to illustrate...

Homework Statement I know that potential gravitational energy is relative to the reference point that I decide to choose (like in the picture below). But then if, for instance, I set my reference point in the ceiling and my vertically down y-axis to be positive. What would the potential...

If gravitational force is caused by a particle (tensor boson) which is massless and so travels at c, why doesn't matter ever exhaust, or even seem to reduce, its supply of these particles?

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...

Signatures of extra dimensions in gravitational waves David Andriot, Gustavo Lucena Gómez (Submitted on 24 Apr 2017) Considering gravitational waves propagating on the most general 4+N-dimensional space-time, we investigate the effects due to the N extra dimensions on the four-dimensional waves...

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...

Why is gravitational force equal mass multiply gravitational acceleration F=m.g

Hi guys. I'm new to this forum so I'm not sure if I'm posting this in the right place or correctly, but I was totally stumped on a Physics 12 question as I was studying for my exam. The question is: An explorer spacecraft is descending towards Mars using a rocket engine for braking. The...

Homework Statement A projectile is fired vertically from the Earth's surface with an initial speed of 11.4 km/s. Neglecting air drag, how far (in meters) above the surface of the Earth will it go? Homework Equations (1/2)mv^2 -GmM/R The Attempt at a Solution KEi+PEi = KEf+PEf (1/2)mv^2 -...

Homework Statement Express the gravitational force equation in terms of density. Homework Equations F(Gravity) = ((GravitationalConstant)(Mass1)(Mass2))/radius^2 Density = mass/volume The Attempt at a Solution Based on the original equation for gravitational force, there are two masses...

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

Homework Statement a) What is the magnitude of the net gravitational force on the m2=10kg mass? Assume m1=20kg and m3=15kg. b) What is the direction of the net gravitational force on the m2=10kg mass? Assume m1=20kg and m3=15kg. Homework Equations F = G*m2*m3/R^2 The Attempt at a Solution M2...

<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...

The spacecraft "Helios 2" (with 100 kg of mass) used the Sun to get a speed of 250.000 km/h using gravitational assistance, I want to know if the mass of the spacecraft influences the result of the speed. I mean, if the spacecraft mass 10.000 tons, the speed would be less of more?

It is said that GR in the weak field limit it produces Newtons familiar law, so why can't GR produce other formulas for "strong field" which I guess it means at short distances.

We know (measured) that a clock on a mountain "ticks" faster than a clock at sea level. At higher altitude, the clock runs even faster. Now, if we go much higher, towards the Sun, on the line between the center of the Earth and the center of the Sun, the clock should begin, at some point, to...

A professor from a UK university who is a member of LIGO kindly video called me the other day regarding potential PhD projects and said that a lot of gravitational research isn't about the dynamics and source-model nor application of general relativity but high performance computation and big...

Hello! I hope this is the proper forum for my question(s). English is not my native language, so I apologize in advance for language mistakes. In Feynman Lectures on Physics, there is a chapter about the conservation of energy. The first part, which deals with the definition of energy, I...