Gravity Definition and 1000 Threads

How mathematically within the confines of mainstream physics would you experts in physics merge Einstein's Field Equations with Quantum Mechanics and Quantum Field Theory? I am looking for a different perspective on this subject usually I get the perspective of "Cranks".

This is probably going to sound like a ridiculous question... but here goes. I (think) I understand that matter tells spacetime how to curve and spacetime tells matter how to move. I also know that light obeys the same laws of general relatively as matter. What I can't get my head around is...

Did not know where to start so I tried A= v/t to find velocity then plug into equation to find g, but i got a huge g.

is there a equation that links quantum gravity and special relativity?

a = (change in magnitude of velocity) + (change in direction of velocity) → Can you feel when you change direction? Even if force and acceleration are constant? ↑ ↓ ↑ ↓ ↑ ↓ o

How feasible is such a planet? Can the planet still be dense enough to be rocky and not gaseous?

Gravity can be described not as a force but a curvature of spacetime. I assume this can’t be done to the other 3 fundamental forces. If so, then we cannot treat gravity in a way similar to the other forces. Why then does QFT postulate the existence of gravitons? Why does it attempt to treat...

Choice D is obviously wrong therefore leaving us with choices A, B, and C. Can someone explain the relationship of the three variables stated above (mass, volume, and acceleration due to gravity)? Thank you.

I am watching a show about the Standard Model and The Theory of Everything (which of course we do not have right now) and the lecturer mentioned gravity is not part of the Standard Model. Yet other books include it. What is the general consensus? Thanks Bill

If you drop an object from rest, its acceleration towards the ground is g ,ok i know that but if you drop the object at some speed v does acceleration is still g? i suppose is still g

I pick up half information on some things, so please straighten me out on this. My understanding is that gravity is an emergent property of expanding space time. So presumably if space time shrinks in the very distant future then, if that were to happen, gravity would become a repulsive force...

Hi. Could the local effects of gravity between nearby stars at the edge of a galaxy cause these stars to rotate around the centre of the galaxy more quickly than predicted if the prediction is based upon individual stars only. This effect would be similar to the way the Earth "drags" the Moon...

According to general relativity, gravity is simply the side-effect of bending the geometry of space-time. As a thought experiment imagine a 3D image being projected from a 2D hologram - the distance between the actual 2D pixels in the 2D plane always remains constant, yet depending on the shape...

Hi all, another newbie question for you. I often hear gravity described as a force, including speculation that gravitons are its messenger particle, but is that consistent with general relativity? I thought relativity implies it's more like rolling down a hill than being pulled by a force.

Can someone help me? I am not sure where is my mistake correct answer: ##g=\pi G\rho R## my calculus By symmetry, I only need to add the vertical component of gravity ##dg = \frac {GMdm}{d^2}\cdot cos\theta## (1) Where d=R ##\rho =\frac{dm}{dV} ## ##dm = \rho \cdot dV## (2) (2) in (1) ##dg...

Apologies if there are already an abundance of threads on related questions. I have tried searching for threads on here and have read quite a few, as well as reading other sources. I've kind of reached a point where I need help to parse some of the information that I have been reading and to get...

You're on Earth. You throw a ball and watch its trajectory. It's curved. That's because the Earth is curving space-time at every point along the trajectory. But the Earth itself is not present along the trajectory - there is no matter along the trajectory (let's ignore the air and any radiation...

u=5m/s t=5sec the height will be the displacement s=ut - (1/2)gt^2 s=5*5-0.5*10* 25 s=-100m But the answer is 273.6m

I have a pendulum and an object with radius "R" and mass "m". There are forces: constant gravitational acceleration and tension on the rope. I can write: $$x=R sin(\theta) \ \ y=R cos(\theta)$$ $$\dot{x}=R\dot{\theta}cos(\theta) \ \ \dot{y}=-R\dot{\theta}sin(\theta)$$...

Hi Guys, I have a specific mechanism problem I am trying to solve. I can't divulge the specific application, however I am looking for examples of where this has been done in the past (or if this is even possible in peoples opinions).I have a mechanism that employs a weighted pendulum type...

The red dots show the CM of each block. ##x## is the amount by which the upper block overhangs the lower block. The blue (dashed) line shows the CM of the combination. For maximum overhanging, this line lies on the edge of the table below. By symmetry, the CM lies exactly midway between the two...

I submitt a paper to journal Classical and Quantum Gravity. The status "awaiting referee reports" lasted one mont. However, now , the paper is on status "awaiting decision" two weaks up to now. Is a ill signal the delayed on the status "awaiting decision"?

I have this theory; gravitation is a result of the right composition and amount of elements, combined with the right temperature with a flux of course. This means there are many possibilities to create gravity, and anti-gravity if switched 180 degrees. Am I far out? what's your thoughts?

So there is no a full quantum theory of gravitation. However, there are instances where quantum effects due to gravitation have been studied. Like Gravitational neutron interferometry https://arxiv.org/pdf/1701.00259.pdf or maybe gravitational decoherence...

Is General Relativity applicable in problems involving tidal gravity? For example if a system being analyzed is large enough where tidal gravity effects become apparent - suppose two distantly separated hovering observers see a freefalling object change velocity - are general relativity...

Full quantization of gravity is a big issue, but that's not what I'm asking here. I'm asking about quantum effects that involve any form of gravitation (Newtonian or GR) but that don't require a full quantization of GR or anything like that. Things like gravitational neutron interference or the...

A square sheet of metal has a square of one quarter of the original area cut from one corner as shown in the figure. Which of the following statements is true about the position of the centre of gravity of the remaining portion of the sheet? a) center of gravity lies at a distance of 5/12 of...

Is the gravity sling possible without rocket propulsion which dynamically guides the object to the right point? Ie, if instead of using a rocket, you shoot the object with an accurately aimed cannon from the moon, will it either hit the planet or miss it but never get slung/accelerated...

In Quantum Mechanics, the position (or momentum) variable is quantized. I define "quantization" as promoting a variable into a probability distribution. For example, with the double slit experiment, the classical assumption that the position/path of a particle is "unique" cannot explain...

My current understanding is that a person falling toward the surface of a planet with no atmosphere, would feel no force acting upon themselves even though they are accelerating relative to the planet. If the mass of the planet suddenly tripled while the person is in free fall, would the person...

http://www.google.it.ao/books?id=4qp8AAAAIAAJ&pg=PA212&focus=viewport&vq=%22yet+untouched+10,000+more+were+faithfully+collected+:+some+of+which+without+question+would+render+the+text+more+beautiful,+just,%22&dq=editions:ISBN0803974612&lr=&output=html_textThe last clause of the second position I...

Here is the picture where person balancing a toy bird with using center of mass. I am bored with center of mass. I want to try same experiment with center of gravity. Is it possible to use center of gravity to balance bird toy ?

When i get into discussions regarding "Gravity" i say that it is a force that is caused by gravity. that the acceleration is due to gravity. there are some, like George Musser who have recently said, "Gravity is not a force, but can be thought of as a force". i think what he means is that...

Hypothetically, if the universe was completely empty, and two apples were 10,000,000,000 light years apart, would their gravity be strong enough to eventually bring them together?

The typical equation for the height of a projectile on Earth after ##t ## seconds is ## h = -4.9t^{2}+vt+c## where ##v## is the velocity of the projectile and ##c## the initial height. This is nice and all but what happens if the height is very large? The leading coefficient of the equation...

In a recent study (https://phys.org/news/2018-08-flaw-emergent-gravity.html) it has been discovered an important flaw in Emergent/Entropic Gravity because it has been discovered that holographic screens cannot behave according to thermodynamics... But then, doesn't this also invalidate...

Hi I am trying to roughly calculate a force. If i am moving an object towards the Earth and then stop it, how much force will this generate? a=vf-vi/t - vi =0.6m/s -vf= 0 -t = 0.1 s This equalling - a Then applying f=ma m=150kg Im unsure how to add gravity into this. would... 0-(9.8+0.6)/0.1...

If you have two different liquids (water and oil for example) mixed together and free floating without gravity, will they separate as they do here on Earth? If so, what property would determine the layering structure? I suspect they would separate, and if left undisturbed probably form a...

I only need help with how to find the component of gravity along the curve. See image.

Summary: Lower than average weight at the equator causes the Earth to be wider, yet positive gravity anomalies are claimed to cause an increase in sea height. Summary: Lower than average weight at the equator causes the Earth to be wider, yet positive gravity anomalies are claimed to cause an...

I read that just a few feet difference in height would show a different rate of time and that was measurable. However, If the clock that is at a more elevated position it will be traveling through more space, is that what is responsible for the difference in the rate of time for that clock? I...

How much is too much gravity for life as we know it to exist on a body too small to become a star? At approximately what multiple of 1g would life as we know it be impossible because of the direct effects of gravity? What about secondary factors--e.g. how the higher gravity would affect the...

Dear Physics Forums people, My problem lies in understanding how the following line integral, which represents work done by the gravitational force, was calculated Specifically, in the integral after the 2nd = sign, they implicitly used \hat{r}\cdot d\vec{s} = dr I wish to understand what...

Has/Can gravity wave time distortions be measured to any degree of accuracy as does LISA measures space distortions? If not, why not?

Is it possible to reduce and/or modify the EFE so that they make the exact same prediction as Newton's law of gravity? I am wondering if the slight differences in prediction from these two mathematical approaches can be identified at a particular place in the EFE or if it's the geometrical...

So using conservation of energy where v0 = 7000 m/s $$ K_{i} + U_{i} = K_{f} + U_{f} $$ $$\frac{1}{2}mv^{2}_{0} - \frac{GMm}{R} = \frac{1}{2}mv^{2} - \frac{GMm}{r}$$ where R = the radius of the Earth and r = the distance from Earth's center plus the height its orbiting $$v =...

Under Newton, gravity is what I term an "invisible magic rope" that pulls you down. Enter Einstein. We do away with the invisible magic rope, and say that space (or space-time) is warped by mass. However, we still have other forces, that (as far as I know, anyway) are "invisible magic ropes."...

Well the first one that comes to mind is gravity and maybe centrifugal/centripetal force. I imagine that forces such as drag shouldn't even be considered. I find it difficult to imagine which belong to which frame of reference.

In Special Relativity, you learn that invariant mass is computed by taking the difference between energy squared and momentum squared. (For simplicity, I'm saying c = 1). m^2 = E^2 - \vec{p}^2 This can also be written with the Minkowski metric as: m^2 = \eta_{\mu\nu} p^\mu p^\nu More...