What is Gravitational: Definition and 1000 Discussions
Gravity (from Latin gravitas 'weight'), or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are attracted to (or gravitate toward) one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides. The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing and forming stars and caused the stars to group together into galaxies, so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become weaker as objects get further away.
Gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915), which describes gravity not as a force, but as a consequence of masses moving along geodesic lines in a curved spacetime caused by the uneven distribution of mass. The most extreme example of this curvature of spacetime is a black hole, from which nothing—not even light—can escape once past the black hole's event horizon. However, for most applications, gravity is well approximated by Newton's law of universal gravitation, which describes gravity as a force causing any two bodies to be attracted toward each other, with magnitude proportional to the product of their masses and inversely proportional to the square of the distance between them.
Gravity is the weakest of the four fundamental interactions of physics, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a consequence, it has no significant influence at the level of subatomic particles. In contrast, it is the dominant interaction at the macroscopic scale, and is the cause of the formation, shape and trajectory (orbit) of astronomical bodies.
Current models of particle physics imply that the earliest instance of gravity in the Universe, possibly in the form of quantum gravity, supergravity or a gravitational singularity, along with ordinary space and time, developed during the Planck epoch (up to 10−43 seconds after the birth of the Universe), possibly from a primeval state, such as a false vacuum, quantum vacuum or virtual particle, in a currently unknown manner. Attempts to develop a theory of gravity consistent with quantum mechanics, a quantum gravity theory, which would allow gravity to be united in a common mathematical framework (a theory of everything) with the other three fundamental interactions of physics, are a current area of research.
During an eclipse the Moon covers the Sun.However this shouldn't be happening due to gravitational lensing we should be able to see some light?
Is the mass of the Moon not big enough or photons do reach us but they are so little our eyes can't detect them?
I noticed in physics papers that gravitational redshift is expressed in m/s or km/s.
I assume that this must be the equivalent velocity to produce that same redshift.
So for example, if the gravitational redshift was measured as 3x10 ↑ -4 then;
z= v/c
3x10^-4= v/c
v = 9x10^4 m/s
v=90km/s...
An object on the surface of the ground does not penetrate the ground. How much is this because of the electrostatic force between the particles constituting the ground and the object, and thereby maintaining their integrity? And, how much is it because of the materiality of the mass of the...
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Can someone advise on this? In most diagrams showing how mass effects the gravitation field (earth for instance), bending fabric of space, it is demonstrated on one plane. Why is it shown this way and is there any other way of illustrating this?
I would like to be sure that objects passing at high speed (half or more of the speed of light) have more gravitational attraction to each other than they would if their relative speed were forty miles per hour.
Thank you for your help.
Jim Adrian
Hello!
I was wondering if it is possible to express the gravitational energy as a product of the gravitational field by a moment, as we do with the magnetic and electric energy? Would this require the existence of bodies with negative mass? How could we relate this to the existence or total...
Hello,
Apart from the graviton postulate, which would permit such a mechanism, my question is: would a similar mechanism be possible with a stationary wave? (the simplest scenario I can immagine is of two opposing waves).
My background is in DSP and Acoustics so I might get things wrong (a...
History & evidence can be found in:
https://onlinelibrary.wiley.com/doi/full/10.1002/andp.201900013
https://phys.org/news/2015-04-gravitational-constant-vary.html
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The experimental data strongly suggest are actual x,y,z,t variations in the measured value of G
I'd like to see some of the consequences of the existence of gravitational waves (both expected and unexpected), in laymen's terms so a simpleton like me can understand and relate to them.
A possible consequence that I thought of (and I'm sure someone will correct me if I'm wrong) is that...
Spring has more potential energy when it is compressed or stretched from its initially balanced state. As external work is done, it stores energy in the form of potential energy. Here, we know energy is stored in spring but For the Earth-ball system, where the energy stored?
I was reading (or at least skimming) this paper:
https://arxiv.org/abs/2005.10702
in which they seem to be discussing gravitational wave lensing. Is this an analogue of light lensing or is it another subject entirely? I mean, as I understand it, light is bend using gravity (as for...
First, start off with x and y directional forces
F (Test object 1) - F x(Test object 2)
I need help primarily with finding the horizontal component of the force from object 2. How do I find it and express it?
Thanks
I was thinking about an experiment to demonstrate gravitomagnetic effect. I did my calculations using gravitomagnetic model. It is not as accurate as general relativity, but GR should give similar predictions. I do not know if it would be possible to to this experiment in real life(are there...
At first, I thought when the rod goes really far away from the particle, then L would approach to zero in a particle's reference view. As a result, the equation will be GmM/d^2. However, I just thought that L just remain as it is regardless of change in d, but not sure...
I am doing a book that have only exercises, and an introduction to the posterior theme, so, in the introduction, there is the relevant equations, and there is a equation: G = -Gm/r^3 called strength G, in the gravitational topic, what is this? I never saw it.
I've been trying to understand gravitational time dilation by considering a light-clock of length ##l## undergoing an equivalent acceleration ##a## from rest along the direction of the bouncing light pulse.
I find that the time ##t## that the light pulse takes to travel to the forward receding...
Hello! Can someone point me towards some papers that use AI for gravitational wave generation? I found many papers using AI to analyze data, but not really something where AI is used to actually generate waveforms. For example this was done for particle physics simulations to increase the speed...
Hello folks,
I am working on Java program just for fun to model an n-body problem using 3-dimension graphics. I'm looking for a way to speed up the model.
Suppose for example that I decide to increase the speeds of all objects by a factor of, say, 2. To compensate, I would also increase the...
The alert is here,
https://www.sciencealert.com/supermassive-black-hole-jets-have-been-seen-slamming-into-gas-in-the-early-universe
The abstract from the paper here,
https://iopscience.iop.org/article/10.3847/2041-8213/ab7b7e
The effects of jets from a black hole within the galaxy including...
This is a quite specific question, but maybe someone knows (part of) the answers, what would be much appreciated.
The Moller (the o is a specific Danish character) Lagrangian for gravitation reads (see for example Aldrovandi-Pereira, Teleparallel Gravity, Springer 2013) ##L = \partial_\mu...
If we are in a cabine in a gravitational field and inside, we have a racket and a ball. We put strings in each side of the racket and we connect the racket to the ceiling of the cabine. This strings only allows us to keep the weight of the racket. Then, we drop a ball to the racket.
We do this...
Hi,
starting from this very interesting thread
I'm still a bit confused about the conclusions.
The main point, as far as I can understand, is all about conditions for a quadrilateral to be considered a parallelogram.
My first basic doubt is: the concept of 'parallel' applies just to geodesic...
The term “negative mass” gets puts forth occasionally, and it’s definitions can sometimes be unclear.
the topic I’m interested in is particles which have both positive inertial mass and negative gravitational mass.
So far, what theories do physicists have of speculating on the existence of...
I attempted the question with
d=vi x t + (at^2)/2
gravitation acceleration= -9.8
and I got the solution of 22.724.
Should I use the value of -9.8? or should I just use 9.8?
should I use the equation above? I feel like what I am calculating is not displacement but distance...
thank you
Does the electric and magnetic fields of electromagnetic radiation remain perpendicular in the presence of an intense gravity field? If not, what is the physical ramifications of this?
The correct answer is the second one. I honestly have no idea why this is so. I understand that the right rope has less tension that the left one since it's at a shallower angle from real world experience, but I don't really know why this is so, let alone how the forces compare to gravitational...
The thing is, I've already looked up at the solution online at it's t= 2a/3v. But I've approached it a different way and I can't really tell what I'm doing wrong, my solutions gives out t= (a/√3v )* (π/3),I don't know what's wrong with it. Here's my approach:
The points will meet at the...
Using the Sun as example, we know from the Eddington experiment that the Sun deflects light.
Does light from other stars get deflected towards or away from the centre of mass, or is it a mix?
Does light coming from the Sun get deflected towards or away from the centre of mass?
Would this make an...
Here are 2 questions that I have tried to answer and was hoping if these are right ways to go about it?
Q1) Find the distance in meters (m) between centre of the Moon and the centre of the Earth, assuming that the Moon moves in a circular orbit with a period of 27.5 days. Take the mass of the...
So, here's an attempted solution:
With ##r_{min}##,
$$r_{min} = \frac{1}{B + \frac{\beta}{\alpha^2}}$$
With ##r_{max}##,
I get:
$$r_{max} = \frac{1}{B - \frac{\beta}{\alpha^2}}$$
or
$$r_{max} = \frac{1}{\frac{\beta}{\alpha^2}}$$
Other than this, I and the team have absolutely no idea on how...
The man floating inside the elevator travels through space at constant velocity, and soon reaches proximity to a planet.
To an outside observer, the elevator appears to change course and accelerate towards the planet, so he reasons there is a force acting on the elevator, changing its course and...
Hi all, I've been wondering:
Thinking of Arthur Eddington's relativistic oriented 1919 eclipse observation, would the photon deviation due to the Sun's gravitational imposition have caused the photons to exhibit a qualitative redshift due to the time photons had spent within the Sun's...
Hi there
I have been attempting the parts to this question and I'm finding some trouble on how to answer the last part which is d)iii
Here is what I have done for the rest of the parts and what I think I should start off with in part d)iii
Thanks!
Below, I have already solved - I assume - correctly for question 1. Question 2, I am nearing to what I believe is the solution. Question 3, I simply have no idea where I should begin considering that it is interconnected with question 2.
With that said, below is the lengthy and somewhat tedious...
To begin with, I posted this thread ahead of time simply because I thought it may provide me some insight on how to solve for another problem that I have previously posted here: https://www.physicsforums.com/threads/special-relativity-test-particle-inside-suns-gravitational-field.983171/unread...
Below is an attempted solution based off of another user's work on StackExchange:
Source: [https://physics.stackexchange.com/questions/525169/special-relativity-test-particle-inside-the-suns-gravitational-field/525212#525212]
To begin with, I will be using the following equation mentioned in...
If there are three bodies A, B, and C arranged linearly, and B is free falling towards C, will the gravitational presence of A affect the rate of free fall of B towards C?
In this paper by Carlip, a comparison is made between electromagnetic and gravitational aberration.
For the latter case, he takes as a study subject the Kinnersley’s “photon rocket”, an exact solution which is known to have the strange property of not producing any gravitational waves, even...
By the time the gravity wave reaches us it is very small in energy, I assume. We do not know how to make gravity waves in a laboratory but we have a place where we have a very sensitive gravity wave detector. If we had a lab set up a few blocks away we might be able to do various experiments...
In the Lagrangian (L1) point between two hypothetically massive (and close) objects , is gravitational time dilation effect summed or canceled, or something else?
I am trying to derive the gravitational binding energy of the cluster. Its given as
$$U = -\alpha \frac{GM^2}{r}$$
Now for the derivation I started from
$$dU = -\frac{GM(r)dm}{r}$$
I I tried to write ##dm = \rho(r)4 \pi r^2dr## and do it from there but I could not do much. Any ideas how can...
Hi,
Gravitational energy in de Sitter has equation of state w=-1 (cosmological constant) and w=-1/3 (curvature energy in open or closed de Sitter). Is this just gravitational radiation, and how does this accord with the equation of state of photon radiation w=1/3?
Does this mean that densities...