Gravitational Definition and 1000 Threads

Is gravitational prospecting pseudoscience? From the literature, it says that we can know what is beneath a site (say for prospecting for oil. metals, etc) from measuring the local "g" field/acceleration at various locations. Together with other information, we can know the mass distributions...

In Newtonian mechanics, both gravitational mass and inertial mass is m. This principle is known as the principle of equivalence. However, I heard that in Relativity, gravitational mass is γm instead of m because total energy of the particle is γmc2. But in special relativity, it is widely known...

What is the mathematical formula for the time dilation (clock-slowing factor) for a clock in a gravitational field g, equivalent to the Lorentz factor γ for a clock traveling at a relative speed v?

I would like to know which of the following interpretations of what happens when a local observer with a non-zero mass (i.e. not a photon) crosses the event horizon of a black hole: 1. Not only does the falling observer not *notice* anything strange (because his/her clocks run proportionally...

Homework Statement Let's consider two wooden logs. We burn the first one at the base of the mountain and the second one on the peak. Which one is releasing more energy? Do they release the same amount of energy? Does the potential energy affect the burning Homework Equations ## \Delta H =##...

Can someone please show that calculation of gravitational potential energy at a point R+h from the centre of the Earth by choosing the centre of the Earth to be at zero potential. Here R is the radius of the Earth and h is not very small wrt to R

I am looking at a couple of very interesting papers, published in MNRAS, that deduce, that the accelerated expansion of the Universe we observe can be attributed to gravitational waves, produced by a very distant merger of two or more universe-mass-scale black holes. The last one is on the...

Im trying to create or find some way to calculate gravitational acceleration on planet surface based solely on density and mass of planet. This should be based on average density and it can be also some approximation, without calculating minor effects like rotation, planet bulge, relativity and...

Newton's law of gravitation cannot be compatible with relativity because the gravity from a massive object applies a force to all other masses infinitely fast. General relativity is supposed to correct this flaw by setting a speed limit on how fast the effect of gravity can reach a distant...

If a celestial body's kinetic energy (say, the Moon's) surpassed the energy necessary to exceed the gravitational binding energy (GBE), would said body break apart because of it? For example, the Moon is currently orbiting the Earth at a speed of 1020 meters per second, giving it a kinetic...

I was doing a thought experiment last night. Gravitational waves, being like any other type of wave would cancel each other out and create a refraction pattern of strength. While we do not have definitive proof there is a black hole at the center of every Galaxy, we do know, through...

This paradox may have come from Feynman's Lectures on Physics, or I may have dreamed it up myself. I am not sure. It has been around for a while and if you have already seen it, I apologize. I am not aware of any resolution. An electron is at rest in a gravitational field. We know from...

Could it be imagined that due to a particular stars' distribution in a galaxy the gravitational force felt would be like $$f(\vec{e}_r)/r^{\alpha}$$ where $$\alpha\neq 2$$ but near 2 and f a non spherically symmetric function (like a comet around a flat galaxy) ?

What I know gravitational time dilation (based on GRT) is dependent on gravity potential and not on gravitational acceleration. That would mean, that for example in center of Earth is the gravitational acceleration zero, but the gravitational potential is bigger than on the surface of Earth...

Are gravitons postulated to be excitations of gravitational waves? If so, and since gravitational waves have been unambiguously observed, then gravitons must exist, no? If not, then what is the postulated relationship between gravitational waves and gravitons? Are both deemed/postulated to...

Hi 1-)If an object's total velocity through space-time(four-velocity)is c, for example even we stand still we move with velocity c (through time) and if mass slows down time, can we say mass also increase our velocity in space? 2-) Is Four-velocity magnitude constant in General Relativity...

it seems to me that during a high energy event that a space time compression wave would be created which would then normalize as it spread out. A particle on a back end wave would become close enough to the front end wave that it could tunnel between the two as "distance" is compressed. We...

Hi I have 2 questions. There are 2 planets and one clock on each of them. One of them has a bigger gravitational field strength. And two clock have same distance from the core. 1-) Does time dilation occur between two? Which clock ticks slower? 2-) If time dilation occurs, which formula...

If we run two identical lasers and put one at sea level and one on top of a high mountain, will they operate at different frequencies?

Imagining that an object spining around a spherical mass M has angular momentum that has z-component(θ=0) only, then $$g_{μν}\frac{dx^μ}{dτ}\frac{dx^ν}{dτ}=(1-\frac{r_s}{r})c^2(\frac{dt}{dτ})^2-\frac{1}{1-\frac{r_s}{r}}(\frac{dr}{dτ})^2-r^2(\frac{dθ}{dτ})^2-r^2\sin^2θ(\frac{dφ}{dτ})^2=c^2$$...

I understand time dilation due to speed, but am confused on why time dilates depending on the distance from a mass. Help?

I’m only an interested layman and my math is pretty basic so please excuse my lack expertise in this subject but I was wondering how to calculate the threshold distance an object of mass m would have to be to a system of mass M to overcome the effects of dark energy and not be receding?

A paper in Nature is getting some press, for having calculated "the pressure distribution inside the proton". But the theory behind the calculation seems a little odd. Apparently the data pertains to the scattering of an electron from a quark via the exchange of two photons. But each photon...

Homework Statement Project Thor is a proposed (and terrifying) weapon system where a cylindrical tungsten rod (19600 kg m3 ) about the size of a telephone pole (6.10 m long and 0.300 m in diameter) is dropped from Earth orbit. Imagine you dropped one of these from an orbit 10,000 km above the...

Homework Statement [/B] Homework EquationsThe Attempt at a Solution I think the two masses , inertial and gravitational are equivalent and because of this fact , the ratio of the two masses is one . The correct option should be 1) . But the answer given is 3) i.e A statement is true and R...

How come the gravity of a stellar- mass black hole is strong enough to trap light but the gravity of a stellar-mass star (eg the sun) is not strong enough to trap light ?

Hello everybody! I am TanX. I was reading about neutrons in a gravitational field, which was based on the Grenoble experiment ( Institute Laue - Langevin ) conducted in 2002. I have put a link down here to the research papers below ( Refer to page number 17 in the booklet for the important...

I am curious as to what the maximum amplitude of gravitational waves is. I have read that the maximum amplitude as such is equal to two but I cannot seem to find again a reference that states this clearly.

A star or a planet is a material object, while a black hole is an 'immaterial' spacetime object. Does the material or 'immaterial' nature of an object make any difference in how it curves or travels through spacetime as it manifests gravitation (apart from the powerful gravitation near a black...

Disclaimer: to avoid giving the impression of speculative nature, I state the purpose of this thread is only to conflate known theory with my own understanding in a specific point and clarify where the disagreement lies; that is all. TOV limit: since early research in black hole (BH) formation...

Information Given: In the figure, a square of edge length 17.0 cm is formed by four spheres of masses m1 = 4.70 g, m2 = 2.90 g, m3 = 0.800 g, and m4 = 4.70 g. Question: In unit-vector notation, what is the net gravitational force from them on a central sphere with mass m5 = 2.90 g? Attempted...

Gravitational waves are quadrupoles, they bend and stretch spacetime. Does the expansion of spacetime due to gravitational waves exceed flat (Minkowski) spacetime or is flat spacetime it's limit?

So we have the Newtonian gravitation potential given by ##\phi_M(r)=-GM/r##, and in class the teacher said that the Newtonian force is given by ##F_m = -m\nabla \phi_M(r)##. Now, I was thinking about what was taught in UG or high school, isn't the force should be ##F_m = GmM/r^2##, if I plug...

Homework Statement Scientist want to put a satellite into an orbit where the gravitational field of Earth is half its value at Earth's surface. The altitude of this orbit above the Earth's surface will be A.3R B. √2R-R C. 4R D.√2R Homework Equations Fg∝1/r^2 The Attempt at a Solution I know...

Homework Statement Hi I'm attempting to derive the gravitational potential energy of a point mass (##m##) that's moving from infinity to a point r' inside a gravitational field produced by a another mass ##M##. For simplicity I treated it as a one dimensional case. The problem I get is that the...

I am doing a term paper on G. Waves and I have a couple of questions about them. - How do we know that the G. Waves detected by LIGO on September 14, 2015, come from 1.5 billion light years? - How is Einstein's Theory related to them?

Hello! The equation for relativistic mass by special relativity tells us the relativistic mass for object in motion...but since inertia mass has same value as gravitational, does this formula also apply for gravitational mass? Thank you!

What is the difference between the gravitational force and gravity? Because I was under the impression that gravity is not a force, but one of the 4 fundamental forces of nature is the gravitational force, so I was wondering what the difference between the two is?

Is there a gravitational variant of the Schwinger limit? I mean: a strong gravitational field can separate virtual dipoles with tidal forces. The force applied to the positron is different from that applied to the electron (though both are attractive) and, if this difference is high enough, the...

According to the Unruh effect an observer who is has an acceleration ##g## will observe the temperature of the vacuum to be $$T=\frac{\hbar g}{2 \pi c k_B}.$$ According to the equivalence principle the observer should measure the same Unruh temperature if he is sitting on a planet whose surface...

Homework Statement Distance Earth-Sun at perihelion = 1.471×108 km Distance Earth-Sun at aphelion = 1.521×108 km Sun mass = 2.0×1030 kg Earth mass = 5.972×1024 kg G = 6.67×10-11 m3/kg⋅s What is the change in Newton of the attraction force between the Sun and the Earth from the perihelion to the...

Hey everyone, I've recently programmed an animated simulation of the main elements (core planets and Sun) of our solar system: by using the initial coordinates from the JPL database, and then calculating the combined gravitational perturbations and the relativistic effects from the Sun...

Homework Statement Homework Equations F=ma F=Gm1m2/r2 Gauss' Law? The Attempt at a Solution I'm not sure if I should be using Gauss' Law for this question, because I've never heard of it or learned about it. I'm currently taking multi-variable calculus (gradients, vectors, etc.). From what I...

Hello. I am in a 100 level physics college course and we are learning about conservation of energy. I am working with a program called Logger Pro. I've attached my data in the pictures. Here is a question that I am very much stuck on. Using the Law of Conservation of Energy, show that the...

Doesn't the postulation of the inertial and gravitational mass equivalence suggest that GR is not a complete theory? (since it also cannot be explained as a neccessity by the anthropic principle)

Homework Statement The Earth has a mass of 5.98 x 1024 kg and the moon has a mass of 7.35 x 1022 kg. The distance from the centre of the moon to the centre of the Earth is 3.84 x 108 m. A rocket with a total mass of 1200 kg is 3.0 x 108 m from the centre of the Earth and directly in between the...

From what I understand the LIGO experiments were the first in the road to demonstrating the existence of gravitational waves. There was a dicussion about this on Utube where someone pointed out that the polarized light scattered from dust, being much larger, could mask the the effect of...

I know this is a naive question that has almost certainly been brought up numerous times before, but my search abilities seem not to be sufficient for finding a good answer, so if anyone just refers me, that would be fine. The question: Special relativity concerns comparisons between pairs of...

I hear people say that even light cannot escape from black hole.So how big is this black hole?Why gravitational pull is very high? Does it have any escape velocity like Earth have?

This is my first (well second if we exclude introduction forums) topic here. I just want to make clear that I am not professional nor involved in field in any way. I am just regular Joe who wants to know more about nature. I could say that I understand fact that mass distorts space but there is...