Gravity Definition and 1000 Threads

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...

I realize that my understanding of this matter and it's vast number of related concepts is rudimentary and incomplete. Kindly forgive my ignorance and try to explain your thoughts in layman's terms. Thank you for your time.

I have a question I have been wondering about lately ,somewhat abstract . Hopefully my description will be adequate . Here it is … The Earth revolves around the sun because of the suns gravitational pull and Earth's inertia . It takes about 8 minutes for sunlight to reach the Earth . What would...

From the proceedings of Group32, the 32nd International Colloquium on Group Theoretical Methods in Physics (9–13 July 2018, Prague): https://iopscience.iop.org/article/10.1088/1742-6596/1194/1/012097 M D Sheppeard Abstract: A physical approach to a category of motives must account for the...

Hey, This isn't a homework question I need help with but more of a concept I can't seem to grasp. I understand that Centre of Gravity is: the point on a body where all the weight can be considered to act. And I understand how to find this point on different types of bodies. However, this...

If we have an object in space (deep space where it is under no other gravitational influence) and we push it a little so that it gains some velocity and after some time comes into the influence of a planet's gravitational field and crashes on it. Where is that energy from the crash coming from...

I have never felt comfortable about trying to explain gravitational attraction to children by using heavy balls running around elastic rubber sheets. After all, it is using gravity to explain gravity. It would be so much better to explain it more like it really is, thanks to that originally...

The main role in quantum gravity can be played by the uncertainty principle , where is the gravitational radius, is the radial coordinate, is the Planck length. This uncertainty principle is another form of Heisenberg's uncertainty principle between momentum and coordinate as applied to the...

Are there new hermitian operators in quantum gravity? Background: In many worlds interpretation (MWI). We have the preferred basis problem and the basis are for example position, momentum, spin. Each of those bases come from a hermitian operator: they are the eigenbasis of the (for example)...

I'm working on a planet that is earth-sized, but has been essentially a dead stone for millions of years: no volcanic activity, the core has completely cooled down, the atmosphere has long since drifted off. In turn it has been mined for so long that a sixth of its mass has been dug up and...

Would making the graviton self-interaction easily calculable solve most of the problems of quantum gravity?

Its been awhile since I even thought about conducting a scientific experiment, and I do remember that you need a dependent variable.. the observation or effect such as the apple fell from the tree, and then the independent variable, such as gravity. But in order to test the hypothesis, you...

The best story from space I remember is how NASA spent a huge pile of money trying to get a pen to work in so little to no gravity in space. They worked and worked away and the Soviets found the solution: using a pencil.

In the 1970s, Ni formulated an alternative theory of gravity (The Astrophysical Journal {\bf 176}, 769 (passage on pages 791 f); see also Misner-Thorne-Wheeler, page 1070). Though in conflict with observation, I am interested in its fundamental properties. Ni has a scalar ##\Phi## as the...

So, I have this idea for the FTL engine for artistic purposes and I wanted to ask if anybody could point out it's flaws. I would greatly appreciate if you were willing to discuss them further. It is just a rough summary, so if you want me to disclose more details, ask away. The idea is as...

Or both? The cycling between 'stretch' and 'squeeze' is caused by the orientation changing of the black holes with respect to us. Correct? This is understood as waves (or pulses) moving through space, Correct? So they take time to get to us. So, consider the orientation which yields us being...

From what I have read gravitational waves are caused by the acceleration of massive object causing ripples in space time. What specifically causes this, and how does general relativity predict these. Does it have to be a high density of matter, or a large amount of it. How do these waves affect...

Hi, I am also having problem with the assumption Entropy makes about the movement of molecules in a 3D space. Does it assume that gas molecules could have equal chance of going in any direction? If so then how is it possible outside a free-fall lab as Gravity bias would always make all the...

I posted this earlier, but the thread has been closed. String theorists frame much of their studies in the context of Planck length. The theories are meant to fold together QM and general relativity. The equation for Planck length includes the gravitational constant, G. It seems to me the...

Based on our current understanding of astrophysics, what's the largest possible rocky planet, theoretically speaking, with a surface gravity of 1g? The larger the planet, the lower the average density, and there's a structural lower limit to the density.

I want to know the differences between Newtonian Gravity and Quantum Gravity

This study from Johns Hopkins University shows that even if we manage to nuke an asteroid and "destroy" it, it will have a core back, in almost 2 hours. Nuking them was a bad idea before, but now seems worse. More details here...

I have a strange question. It's strange because I don't need a correct answer. I need an answer that seems correct and leads to predictable results. I'm making a multiplayer computer game where the players fire cannons in outer space. The cannon shells will move through the gravitational fields...

Hello everyone! I am an undergraduate getting three bachelors in Anthropology/Ecology/Neurosciences (just to show off of course), but sadly no true physics (I don't show off that much, I'm still humble). I am working on a personal project, a tabletop role playing game, where my main struggle is...

Homework Statement Consider an elliptical orbit of a satellite (of mass m) around the Earth (of mass M >> m). The perigee is at ##r_A## and the apogee at ##r_B##, as measured from the centre of the Earth, itself located at one of the focal points of the ellipse (see Fig. 1). We work in an...

Square law? i raise this question because of recently reading some QM, and realizing that for significantly short periods of time, it becomes hard to detect the mathematical patterns. E.g. in the double slit experiment, the standard pattern doesn’t appear after just a few photons. It takes...

When an object is resting on a surface such as the floor, there are exerted on it two forces: The normal force - force of the ground - and the weight (the force of gravity, the Earth pushing the object down), the forces drawn on the left. What are the forces on the right? Are they the same as...

Hi, How to calculate the position in time by applying a force, like a Thrust, not in the center of mass: I only know about the linear and angular formulas: Pos/rotation = 1/2 * F * Time^2 I have struggled finding topics about this maybe because i don't know the correct nomenclatures and maths.

Hi everyone, I have this topic ,and I searched all over the internet without any results what is the affect of Laser Beam on cancelling the Gravity or reducing it if anyone can refer to a reference that can help me I will appreciate it

I've been searching the web for an answer to my question without success, My question is... Is it possible to equate the gravity weight we experience on Earth with the PSI you would experience in places as deep as the Mariana Trench at 10,994 meters which would approx. equal 16,000psi? ex. Would...

<< Mentor Note -- thread moved from the Introductions forum to the technical forums >> Hello there, This is my first post, I find myself often wondering about the universe and how it works, and there are a couple of things I just can't wrap my head around. According to wikipedia the force that...

Homework Statement We need to calculate value for the acceleration due to gravity. We did a test were we dropped a ball from x height and recorded it. Ball 1 0.65 0.82 0.95 0.79 0.81 0.9 0.91 0.85 0.76 Avg - 0.844 Homework Equations Displacement formula The Attempt at a Solution I've...

First off, this is just an assumption. My knowledge of the field is extremely limited and I beg you to come and correct my mistakes, so I can learn. So, I guess we all know how that space-time fabric is bended by gravity. When a star dies, all of the atoms are brought extremely close...

I've seen much about jerk, and how it's generally nearly instantaneous, and for general acceleration, that's fine. However, if I lift at a constant acceleration upward slightly stronger than gravity is pulling me downward, the gravitation pull of the Earth will offset part of my force, so that...

Hello everyone, I am currently finishing my Masters in Theoretical Physics and looking forward to continue in a PhD. I always thought I would love String Theory, and now that i am actually doing it I see that my feeling was correct. I do not know why but trying to understand its concepts...

In reviewing one of Einstein's thought experiments, the accelerating elevator in space, and the resulting bending of light passing through the elevator, Einstein's predicted that light will bend in gravity. Now Einstein's original prediction was off by a factor of 2 because he hadn't yet...

If we were to find some way to make the graviton self-interaction easily calculable, would applying non-perturbative renormalization on it seem any promising?

Hey guys, I reading over Taylor's Classical Mechanics book. Chapter 9, Centrifugal Acceleration Section. In p.346 he mentions that for a free fall acceleration: g = g_0 + Ω^2 * Rsinθ ρ Where its radial component would be...

The current definition of Gravity is: The force of attraction between bodies as a result of their mass. Gravity affects both the space and time of the area surrounding a mass, diminishing with distance, so is the current accepted definition truly accurate? Do I have the correct definition and if...

Homework Statement : It takes gravity 1.43 seconds to pull a 3.67 kg cat down from a 10m tall ledge. What is the power output of gravity? [/B] Homework Equations P=mgd/t P=w/t P=power M=mass G=gravity D=distance W=work T=time[/B] The Attempt at a Solution P=(3.67)(9.81)(10)/1.43 P=251.77

I have tried twice now to calculate acceleration of gravity using the general relativistic equation of geodesic deviation and both times my solution is twice the correct answer. What am I doing wrong? As an example here is one problem: Calculate the acceleration of gravity g at the earth’s...

Homework Statement My answer seems really off and wondering if someone could just look at it before I submit answer? Two 65 kg astronauts leave Earth in a spacecraft , sitting 2.4 m apart How far are they from the center of the Earth when the gravitational force between them is as strong as...

What I understood is that The Schwazschild metric is obtained by setting spherical symmetry in the metric and solves the field equation in vacuum. But is the flat metric a solution too, or does it mean that changing the coordinates induces gravity ?

I'm armchair knowledgeable about GR, but I've come up against something I can't eloquently explain (to someone who asserts otherwise and wants an unassailable answer). What property results in time dilation even when net gravity is zero?The net gravity at the centre of the Earth is zero, but...

Thought you all might be interested in this article. It could just be hype, but there also might be something deeper to it. You hear of so many schemes of tying together quantum mechanics with a relativistic understanding of gravity, that it's easy to respond to yet another announcement like...

I am wondering why gravity needs to be unified with the other three forces into a super-force. Why can't the three forces be seen as interactions between particles in a space-time fabric whose geometry gives the impression of gravity?

This is probably a fairly simple question, but I am struggling with it. My question is: Would you experience the effects of gravity if orbiting in a stable or circular orbit close to a black hole? This stems from my mental image of the International Space Station (ISS). There is obviously...

Greetings: I can understand that an object's trajectory curves about a greater mass (e. g., satellite in Earth's orbit). The spacetime is curved via the great mass and the moving object simply follows the curvature. My problem is this: Why does a stationary object at a short distance from...

This has been bothering me for some time, and would like to get a physicist's view of it. If my understanding or contention is in error, please correct me (gently). I only have under grad physics from 1970, and was a microbiologist, though am interested in quantum physics, cosmology. My...

Warning: I'm a freshman chemistry student. My math skills are elementary at best. Image a ball in deep space. A baseball sounds nice. Assume this ball had no initial velocity but suddenly finds itself caught in the sphere of influence of a massive body. A black hole sounds fun. The ball begins...