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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Does volume of an object affect space-tme curvature? [closed]

If I have 2 bodies of same mass, let 100 tonnes, Both have different volume, let one of $1m^3$ and other of $10,00,000m^3$. Which would have more gravity. Consider here that affect of gravity by ...
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If there were a planet with oceans tall enough saturn fitted in, would it be floating around? [closed]

In this morning I read an article that claimed (translated into english, so emphasis mine) Saturn is so slight1 it would float around in an ocean. So appart the missleading wording of its ...
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Can the mass within the event horizon of a black hole interact gravitationally with the mass outside the event horizon?

If so, gravitons and their fields, unlike photons, must be able to cross the event horizon freely in both directions. If not, the observed mass of a black hole must depend only on the particles ...
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How/why does gravity affect spacetime? [duplicate]

I've always heard that gravity warpes spacetime, but I've never understood why and/or how. I'm only 12 so please keep it simple if possible.
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How does gravity truly work? [duplicate]

I Am only 12 years old and I'm constantly wondering and trying understand how gravity really works. On YouTube everyone always talks about objects wrapping space time around themselves and uses the ...
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181 views

Does mass compress space-time?

My understanding of relativity explains that the presence of mass warps space-time so that light travelling through the warp follows at straight line but the warp itself is curved and therefore the ...
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71 views

Gravitational Waves and LIGO [closed]

Last month, we as a species did something remarkable. We detected the presence of gravitational waves. While we all are celebrating and excited about the newest discovery of mankind. I could use ...
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Can gravity prevent quantum superposition of positions for a massive object?

Theoretically, nothing prevents a really massive object to be in a superposition of two spatial locations, even far away one from the other. Then I guess spacetime would also show the superposition of ...
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What can and can't gravitational waves affect?

Owing to the relative weakness of gravity, I would have assumed that the gravitational waves detected by LIGO couldn't expand / contract the nuclei of atoms (governed by the strong interaction) or ...
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114 views

Did the LIGO measure gravitomagnetic waves as well?

I think of gravitomagnetism as as the "magnetic" portion of gravity, with gravity being the "electric" portion. Since gravity ("electric") seems to affect space (which the LIGO could detect) what ...
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74 views

Black hole's singularity: Does it has to be multi-dimensional?

We assume that there is an infinite density at the center of a black hole. But we also know that if it was really infinite, it would apply an infinite gravitational force to masses even if they were ...
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Practical limit of equivalence principle

The equivalence principle says, for a small elevator, it is not possible to distinguish between a closed elevator moving at a constant acceleration, and the same amount of gravitational acceleration ...
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49 views

If I turn the tip of a 100 light years long pencil, the other end instantly turns , or it takes 100 years? [duplicate]

If a civilization could build a strong , lightweight tube, hundreds of thousands of kilometers long , could theoretically use it to communicate faster than light, simply by rotating it at one end , ...
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Can two photons form a bound state?

I've always wondered if it's possible to bind two photons, in particular by gravitational interaction. Photons don't have a rest mass but nevertheless have a gravitational mass, by which they can ...
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How does the gravitational field behave inside a star?

The interior gravitational field of a star with constant density is given by $ds^{2}=-\left(\frac{P_{c}+\rho_{0}}{P(r)+\rho_{0}}\right)^{2}dt^{2}+\frac{dr^{2}}{1-\frac{8\pi\rho_{0}}{3}r^{2}}+r^{2}d\...
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Could there be a “massive gravity” theory?

If we talk about a "quantum theory" of General Relativity, we know that the particle that mediates the gravitational force would be the so called Graviton, a massless particle with spin $2$. I ...
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Newton's gravity vs Einstein's gravity

Hello so if i were to simplify the difference between gravity as seen from Newton and gravity as seen from Einstein, could i say that Einstein's gravity is just adding the fact that gravity does not ...
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Concept of mass

In classical mechanics, there seems to be a need to distinguish between inertial and gravitational mass. Some texts show how the concept of mass may be defined with some mathematical rigor. There is ...
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What is the source of gravitational force [closed]

What is the source of gravitational force ? Will it work between two charged particle ?
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49 views

Acceleration of falling body in regards to height [closed]

A boulder falls from a cliff of unknown height. Unfortunately, the stop-watch was in my back pocket, so I could only measure the time the boulder took to fall the final third of its journey, which was ...
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67 views

What is the Current Status of Measurement of the Gravitational Mass of Antimatter?

My current understanding is that it's generally expected (and has been predicted) that antimatter will fall down and not up in earth's gravity. But I haven't been able to locate any definitive ...
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How are photons influenced by gravity? [duplicate]

Are photons actually a zero-mass particle, or are they a low-mass particle. Ive heard many mentions of photons having no mass at all, but shouldnt the massive gravity of a black hole not affect light ...
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1answer
46 views

Does light accelerate as it nears a black hole? [duplicate]

As light is affected by gravity ( gravitational lending and black holes), it would seem that gravity causes acceleration. Acceleration has two parts: direction and magnitude. It is clearly evident ...
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Why In Thermosphere is He and O divided as measured? [closed]

If we look Thermosphere a bit closer. we found out that Helium and Oxygen is divided peculiarily. This picture below shows the Earth looked below the south pole. So the orbiting direction is shown in ...
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Can the gravitational force be affected by another force? [closed]

Can the gravitational force be affected by another force? If yes, then like what? I was reading about conservative forces and was given the gravity force as an example stated that one of the reasons ...
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46 views

Gravity difference on earth?

Would gravity on earth be any different if the earth were in intergalactic space rather than interstellar space?
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19 views

Standing waves and acoustic levitation

i am doing a new personnal project about acoustic levitation with standing waves into ambiant air using a piezo ultrasonic tranceiver and a reflective pannel. I modelised both of the emission and the ...
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Non-locality of gravitational energy

Gravitational energy is non-local which is essentially because of the equivalence principle. The equivalence principle says that you can always transform your frame so that you feel like in a ...
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330 views

Can an observer know what is the source of gravity?

There's an observer in a closed room without windows under an influence of gravity force. Can he determine what is the source of gravity - whether it's a spinning motion, acceleration or huge mass ...
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Centre of gravity: Adjusting position

If an object is freely suspended from a pivot, why does the centre of gravity fall directly below that pivot? Would this be the same in non-uniform gravitational fields?
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1answer
42 views

A question gravitation and magnetism? [closed]

Suppose I have a magnet and I put a piece of iron next to it, then the magnet will attract it. Now if I put a piece of wood in front of the magnet and the piece of iron, the iron will not get ...
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97 views

Two places having same gravitational acceleration - Do they also have same curvature of space time?

If there are two places (possibly on/above two different planets) having same gravitational acceleration (g), would it imply that the two places have same extent of space time curvature and will have ...
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1answer
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Why is the matter orbiting a black hole in the shape of a disk? [duplicate]

More generally, if a blackhole is a singularity...a point in space...why is matter only circling in a flat disk-like region. It would seem to me matter would circle it in a sphere surrounding the ...
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Is there a path to go from GR, to Gravitational Waves, to Gravitational Particles (Gravitons), to Quantum Gravity?

The articles on the subject often say : a part of the mass of the 2 celestial bodies became energy for gravitational waves after merging : E(gravity waves) = (M1 + M2 - M_merged).c^2 Intuitively I ...
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Why do black holes need a quantum mechanical description?

I read about black holes, about the Schwarzschild metric, Einstein field equations and their solution in the vacuum for a spherical body. I understood black holes are object whose gravity is enormous,...
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111 views

Distance from Earth where gravity becomes negligible

This is a basic little problem I thought up when trying to remember some physics, and I wanted to see if it's at all correct: trying to figure out the distance from earth where gravity becomes ...
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1answer
27 views

Why do water droplets not form on large openings such as pipes?

When you have an object with a small opening, such as a pipette, water droplets form and hang easily. However, when you have a larger opening such as a pipe, the same water droplets do not form. Is ...
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4answers
105 views

Theoretical Possibility of “Opposite” Gravitational Mass? [duplicate]

This is an unusual idea that I have been entertaining for some time, and I can't find anything about it online. However, it is so simple that someone must have conceived it before. First, I will ...
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Can a tidally locked planet have a horizontal rotational axis?

Is it hypothetically possible for a planet to be both tidally locked, and still have a rotation "horizontally"? Where the substellar point would in effect be like the point of a top, spinning and yet ...
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What is the relationship between the flow rate of time and gravitational field?

I have heard, qualitatively, about the fact that time's rate of flow slows when the gravitational field is "strong". Here I am looking for some more rigorous descriptions of this phenomenon. My first ...
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237 views

Gravitational self-interaction

Today, someone asked me why "the warped space-time warps itself" (he read it in Kip Thorne's: The Science of Interstellar). I guess this is related to the gravitational self-interaction. But I don't ...
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If mass increases as velocity increases, does gravity increase as well? [duplicate]

The way I understand it, velocity and mass are tied together with relativity. As I increase in velocity, I increase my mass until my mass is so great that it would take more energy than the entire ...
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Can the KLT low-energy limit relations be obtained without string theory?

The KLT (Kawai-Lewellen-Tye) relations roughly say that -at the tree level- closed string amplitudes equal open string amplitudes squared and in the low-energy limit this becomes a "Gravity = Gauge ...
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Does orbital motion cause rotation?

Assume the moon was flying freely in space, and not rotating at all. If if then happened to pass earth at just the right distance and velocity to fall into orbit, would its absolute rotation be ...
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Can a micro black hole hover above a regular black hole?

So let's say you have a black hole $A$, that is small enough for its gravity to be very small, but has strong hawking radiation, and larger black hole, $B$, with very small hawking radiation, but ...
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When we spin and feel our arms fly, is it the effect of gravity?

If accelerating reference frames can be treated as normal inertial reference frames but with gravity, then for a rotating reference frame, is the centrifugal force = gravity? More specifically, I was ...
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Is it possible that dark-matter is composed of a large number of neutrinos from the big bang? [duplicate]

They seem to have all the properties of dark-matter (massive, with no electromagnetic interaction). Could it be that many of the neutrinos produced since the big bang have formed massive neutrino ...
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2answers
104 views

Derivation for the temperature of Reissner-Nordström (charged) black hole

A lot of the text for this is from "How does one correctly interpret the behavior of the heat capacity of a charged black hole?" but this concerns a different question. The Reissner-Nordström black ...
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Is the energy released by gravitional waves kinetic energy or converted rest mass?

It is said that at the binary black hole collision LIGO detected recently, the energy equivalent of 3 solar masses has been released. Since no matter can escape a black hole, the only source I can ...
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Can solar flares affect gravity?

Can a large eruption of solar flares on our sun change the effects of its gravity ever so slightly, and is it possible to measure these changes with the equipment we have today.