Gravity Definition and 1000 Threads

Conceptually I have never really understood Ohm's law, other than using it in calculations. My brain just cannot understand why this equation works. I was wondering if there is some sort of gravity equivalent to perhaps conceptualise it a bit better. Voltage: would be the acceleration due to...

I would like to understand if matter accumulates into the gravity well of the Earth? After so many years of circling the sun I have this imagination of tritium, nitrogen, and ozone accumulating underneath the Earth into it's traditional orbit, and accumulating over time. Is this possible and...

I'm reading through Stephen Hawking's 'A Brief History of Time' and came across this sentence in the second chapter: " If the law were that the gravitational attraction of a star went down faster or increased more rapidly with distance, the orbits of the planets would not be elliptical, they...

Hi everybody I saw quite a nice Youtube vid about general relativity and how gravity bends spacetime and therefor redirects angular momentum into the center of gravity. I thought the first time I begun to understand the concept but immediatly the questions poped up. The video basically says...

Assuming that the dark matter problem is finally solved by some kind of MOND, how that would change the scene for quantum gravity?, how that would change the proposed/expected properties of the Graviton (massless spin 2 particle)?

This video explains gravity in a way I haven't encountered before (regardless of how irritating the presenter may be). Nevertheless, I find it hard to believe that a squirrel falls from a tree to the ground due to gravitational time dilation between its head and its feet. The amount is so...

Hi, I’ve got a question. it seems that engineers, structural mainly, don’t seem to understand how gravity works regarding an endless stationary (steel) ring/bridge around the equator. Many if not all have said that such a ring would be modeled as two half circles pushing into each other. So the...

Space exploration plays an important role in expanding our human civilisation beyond earth. But the major challenge is our difficulty of working in zero gravity. So the only possible explanation I could think of is creating artificial gravity. How can this be done ?

Imagine I hang a mass from the ceiling of a building using a rope. The mass is hanging 2m above the floor. Also tied "in line" with this rope, and between the weight and the ceiling, is a scale that measures the weight of the mass. Let's say the scale reads 10 Newtons. Now, between the...

How does gravity influence an electron beam? And how does it influence the other particles?

I want know is there any unified and consistent theory between general relativity and electromagnetism ? If yes could you provide me any textbook ? I'm interest

I am currently doing my masters in theoretical physics and I would like for my phd to be something quantum gravity oriented. However it seems hard to find what's "hot" in the field those past few years and I only know the basics of these topics (though I believe this can be improved). What are...

Imagine you are in the universe of the Expanse book. First of all, you want to speed up your spaceship to reach the alien gate. And you will use Jupiter's gravity. But there is a queue of spaceship wanting to go to the gate, and they all use Jupiter's gravity to accelerate. Suddenly Jupiter...

first I tried to use gravitational force to solve it but because of the incline the gravitational force is zero. so I used normal force to solve. Normal force is 39.36, then f*d*cos(theta) 39.36*3.6*cos(55) it would be cos 55 because the angle is in the direction of normal force from the...

I understand that gravity causes a neutron star larger than about 10 solar masses to collapse into a black hole. I also understand that gravity is the weakest of the four forces. So I find this counterintuitive and I'm puzzled that why is it gravity that causes the collapse and NOT the strong...

This is a basic conundrum that has bothered me for years: if you or a species like you is "adapted" to Twice Gravity (or any other multiple of 9.8m/2 squared) and your life functions and capacities are near identical, How strong/fast are you? Compared to 1G? See, this is the issue of mass vs...

If we just prove (https://www.physicsforums.com/threads/does-every-object-rotate-around-its-center-of-gravity.998359/) that object don't rotate about CG ,why then center of gravity must be ahead of center of pressure ,for yaw stability? Can you explain physics behind this phenomen?

It is said that rocket,plane rotate about center of gravity ,why this is is not case for boats? Boat pivot point is not in center of gravity.

Hello. What are the problems specifically or mathematically or physically that physicists find difficulty in solving to make a theory of quantum gravity? Thank you.

I passed O level Physics in 1983 and loved it but went down the arts route. Over the last 5 years or so I re-kindled my interest and have been reading a lot e.g. Hawkings, Al Khalili, Rovelli etc. I am still struggling with various things that relativity throws up. For example I understand...

I can see how spinfoams and spin networks can describe the structure of space and time. But i have not seen what is added so that there is gravity. is it a less action principle?u

Regarding the equivalence principle of GTR, inertial mass and heavy mass are comparable, and are causing identically effects on mass objects. The pseudo force of inertial mass could be experienced in an accelerated frame of reference. In that point the "Force" appers, while energy is...

Disclaimer - I am not an expert by any means so this might be as much about confirming my understanding as an inquiry from the general public... as such, it might be fairly conversational as I attempt to clearly communicate my thoughts and understanding. Please excuse this. If gravity is the...

Hello everyone, happy holidays! Y/day i googled that question (see title), and i found no clear answer, and I was really suprised, So I had to investigate my self, this is a super basic question, Let me know if i got this right: Earth R: 6,371 km Moon R: 1,737.1 km d1: 384,400 km (center to...

Hello there. What will physicists do after a theory of quantum gravity is found?Will they ask, if it is found ,more questions about it and try to develop it?What other questions will they make probably?Thank you.

I know the solution for the problem of the tension on a rotating ring without gravity (tha is, ##\frac{mR\omega^2}{2\pi}##) - that I find simple enough. But I'm at a loss how can I change it to do with gravity :/ Any help is appreciated! (and apologies for the bad drawing)

Physics is not my area of expertise. That being said, philosophy of science is, but I'm not here to discuss philosophy. I recently found myself trying to imagine how light behaves once it crosses the event horizon of a black hole. Presumably, between the event horizon and the singularity...

If singularities don't exist in QG then what prevents particles from just collapsing falling further until they collapse into a singularity? Is there a repulsive force in QG ? Is time infinitely stretched near a singularities? What else could be happening?

I have several questions related to gravity. I first need to know if gravity decreases at a steady rate for very 1 mile higher up we go?

So what I did was find each of the forces the masses had on m1 using the above equation. From m2 I found 19.975 in the negative i hat and for m4 i found 29.96 in the positive k hat direction using the above equation. For m3 I used pythagorean theorem to calculate r, which was 3.25 (so r^2 was...

Hi everyone! I don't know how to solve the next problem, and if anyone could explain to me step by step how it is solved I would thank you a lot. I know it's not hard, but I'm not seeing how to do it. Thank you in advance!

Hi. I'm a science fiction author whose first novel Hemispheres, published through RockHill Publishing, explored a tidal-locked planet (Gliese 581g) where a group of activists increased its rotation to bring daylight cycles to both hemispheres. Now I'm writing the sequel, and there's ecological...

From the german Version of Carlo Rovellis book "La realtà non è come ci appare. La struttura elementare delle cose" I have learned about the theory of Loop Quantum Gravity that space and time arise through the interactions of gravitational quanta, the space quanta have discrete volume spectra...

As per the summary I would like to find a review paper, monograph or book. Google is not find any recent reviews. Post 2018 would be ideal. Thanks for any pointers. Regards Andrew

Do we first find out as to what is the gravitational strength of a celestial object and then with that determine its density or do we first know what is its density and then conclude with that as to what is its gravity? Also whether the knowledge about gravitational strength or density comes...

Hello. I have this question: do you know why a physical body with bigger mass makes another one orbit around it like the sun does in the solar system and not the opposite of this? Thank you.

This is a conceptual problem. Consider two identical rocket ships in a gravitational field with no atmosphere. Ship A is hovering at a fixed altitude, ship B is ascending at a constant vertical velocity. Since neither ship is accelerating vertically, the thrust required of both should be the...

Hello there.My question is:can Newtonian gravity be generalised to include not only bodies with mass but energy also?Thank you.Can my thread be moved to classical physics?

It seems a gravitational field does not alter the electromagnetic field strength. Is this correct? My reasoning: With no gravity, field strength is: F_{\mu\nu} = \partial_\mu A_\nu - \partial_\nu A_\mu Introduce gravity: \partial_\mu A_\nu \rightarrow \nabla_\mu A_\nu = \partial_\mu A_\nu +...

https://phys.org/news/2018-04-dark-interactive.html "Observations using the Hubble Space Telescope appeared to show that a galaxy in the Abell 3827 cluster - approximately 1.3 billion light years from Earth - had become separated from the dark matter surrounding it. Such an offset is predicted...

I'm watching the Stanford University Lecture series: Einsten's General Theory of Relativity presented by Leonard Susskind (who incidentally has to be one of the greatest educators I've ever watched). Whilst deriving the basic divergence equations relating acceleration, mass density, and...

I have heard Cumrum Vafa one of the leading figure sin string theory proposed a model of the early universe using something called "topological gravity". Can anyone explain what this refers to? A paper can be found here: https://arxiv.org/pdf/2009.10077.pdf

Before I attempt to delve into the math of tensors and curved spacetime, I'm hoping to get a more general intuitive grasp of things. As such, I'm parsing through a lot of lower level articles on these topics, and several that I've come across have argued that Newtonian gravity can be thought of...

It has been hypothesized by quantum field theory that the vacuum is not empty due to the energy time uncertainity relationship. Instead it is filled with a sea of virtual particles popping in and out of existence and renormalized to the observed value we see today in experiments like the casimir...

Normalizing respect m, M, R and k then the normalized force for the case of the bar bell body aligned with the direction of R become Fn = 1/(1+x)^2 + (1-x)^2 is a vectorial sum but in this case the vectors are aligned We can assume x<<1 but is not really material to the problem For...

Hi, I have a question about a hanging rope - how do you find it's mass? I've been searching a long time, stumbled across some advanced calculus involving catenary functions and equations, but couldn't quite figure it out.

If I shine a white light out into space from Earth, and it bends around a black hole and comes straight back to me so I can see it in my telescope, is the light red or blue shifted, or neither? For sake of the thought experiment, let’s leave out cosmic expansion that would stretch it on it’s...

I think Physics should not be weird, there have to be explanations or it might mean we don't understand enough.

Summary:: i) Set up a differential equation that describes how the pressure ##p## varies with the distance r from the center of the planet. Hint: You can base your reasoning on static equilibrium and Archimedes' principle. ii)Calculate how the atmospheric pressure p and the density of the...

https://phys.org/news/2020-09-function-collapse-gravity.html An interesting article I saw yesterday. However, both Nature articles (the summary [https://www.nature.com/articles/s41567-020-1026-2] and the actual technical paper [https://www.nature.com/articles/s41567-020-1008-4]) are behind a...