Gravitational 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...

Do all black holes have the same gravitational pull yes or no, and if not, is it possible that if space and time bends on itself and connects two black holes that the one with the strongest pull will continue as a black hole and the weakest will turn into a white hole considering the amount of...

Why do we use the equation ##\frac {1}{2}mv^2 = \frac {GmM}{r}## to derive potential velocity, and then put that in the Lorentz factor in order to derive gravitational time dilation? Shouldn't we be using the relativistic definition of kinetic energy -> ##mc^2(\gamma - 1)## to derive the...

I am interested in studying at least the basics of gravitational waves. How much knowledge do I need to have about waves in general before procceding?

I have found on the internet an article from Gizmodo magazine, in which a LIGO team member answer some readers’ questions, regarding gravitational waves, and found a specific question and answer in that article, to be very interesting. The question relates to weather gravitational waves are...

A few years go, we detected a gravity chirp from the collapse of binary black holes. The initial total mass was about 21.7 solar masses. The end result was about 20.8 solar masses. The difference was presumably contained in the gravity wave. I believe, under the right conditions, an object...

Is there a way to generate an accurate visual computer simulation of gravitational lensing?

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 have always held (and still do I suppose) the view that gravity is much weaker than the coulomb electrical force due to the fact the equations are so similar you can just compare the constants from each equation showing that the graviational force is many orders of magnitude smaller...

I have a chapter in a novel that involves a crew exploring a derelict space station. The station's systems are largely down, but the artificial gravity still works and is about twice the g force of Earth. I wanted it to be low enough that a lay man would find it not terribly alien, but high...

By using the equation for the Gravitational Potential -GM/R. It is understand that the max Gravitation Potential would be at infinity point. - G(100M)/22R-(-GM/22R) would be the maximum Gravitational Potential... I guess... Then what would be the next step to find the distance?

Hello. I'd just like to check a some points concerning the two kinds of singularities that Penrose and Hawking describe in this paper. https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.1970.0021 The Singularities of Gravitational Collapse and Cosmology. 1. According to the Cosmic...

As proven experimentally clocks tick slower deep in a gravitational well and the difference in energy levels between atomic/molecular quantum state also becomes smaller deep in a gravitational well. This is sometimes known as "gravitational time dilation" and "gravitational redshift" I think...

I thought gravitational waves were how changes in the gravitational field was propagated. The Insight https://www.physicsforums.com/insights/how-fast-do-changes-in-the-gravitational-field-propagate/ says so as well. What got me confused was the following scenario: take a stationary black hole...

Would it be possible for a person in a lift to know if he is in a gravitational field if he measures the gravitational acceleration at the bottom of the lift versus the top as they would differ since gravitational field strength would be different between the bottom and top. In an accelerating...

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, Any object has a gravitational potential energy as a function of the distance from the Earth (R). Does this energy depend only on the rest mass of the object; or one must take into account it's relativistic mass? In other words, if we imagine two identical bullets on the top...

I am trying to understand the following: 1. Have gravitational wave constructive and deconstructive interference phenomena already been observed or is it that only after making LIGO kind of experiments more advanced, that we might be able to observe such phenomena in the future? 2. Can't...

Imagine a ball being tossed into 'the air'. At its peak, the ball has a velocity of 0(m/s), but how long does it actually have this velocity for? --> Neglecting the effects of air-resistance. Obviously the ball undergoes constant 'g' the whole time, but the answer to my question doesn't relate...

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...

Homework Statement Astrology, that unlikely and vague pseudoscience, makes much of the position of the planets at the moment of birth. The only known force a planet exerts on Earth is gravitational. (a) Calculate the gravitational force exerted on a 5.00 kg baby by a 130 kg father 0.200 m away...

(Apologies I posted this initially as a conversation. Not familiar with the format) I used the ‘gravitational time dilation’ equation to see how the clock rate varies with distance from the center of an object. I got the opposite result to what I was expecting.From Wikipedia; Gravitational...

Is there any evidence that objects moving increasingly closer to light speed gain gravitational mass, in the sense of attracting surrounding (and not co-moving) masses more strongly, rather than solely possessing the increased inertial mass implied by the greater force necessary to...

So I know gravity correlates with time dilation. If you have two individual equal size black holes close to each other, then at a point between them, gravity is equal to zero. Would the time dilation at that point be a sum of each individual black holes gravity or would the two time dilation...

I am attempting to prove Newton's shell theorem. There are multiple solutions to this problem, but I am attempting a solution involving adding up the gravitational force of an infinite number of infinitely small disks that are placed together (the discs facing a point mass "m") to form a...

Let us assume that we have a large gravitational field, then the gravitational redshift can be expressed as, $$\frac {v_{\infty}} {v_e} = (1-r_s/R_e)^{1/2}$$ In this equation ##v_{\infty}## represents the frequency of the light measured by an observer at infinity, ##v_e## is the frequency of...

Hi, a simple question related to the gravitational wave detection. The net effect of gravitational wave is basically the stretching of the space including all the measurements tools (meter sticks just to illustrate the concept) that could be used to detect it. I am aware of laser...

It has been proposed that the gravitational wave events GW170809 and GW170814 , named after their date (5 days difference) were actually a single one which appeared twice and magnified due to gravitational lensing. Both events have very similar parameters and come from the same area in the sky...

A person of mass 60kg will weigh around 100N on the moon. This is roughly equivalent to the gravitational force on a 10kg object on Earth. Even if the forces acting on both are about the same, we don't see 10kg objects floating around on Earth whereas a man weighing 60kg can easily float on the...

When and how can the gravitational wave be used for data communication, which the speed be much faster than the current technology by means of electromagnetic wave like 5G, 6G..etc wireless systems ?

From a frame of reference outside of a gravitational field, does the mass of an object near a gravitational field increase?

Hi. If 2 equal masses are placed at rest ( an arbitrary distance apart ) on a horizontal friction-less surface do they accelerate from rest towards each other until they collide ? Thanks

Is it possible to estimate the gravitational force of the center of a Galaxy (it could be Andromeda or the Milky way) to any point (such as a planet) of its Orbit? Furthermore is there such as Schwarzschild solution that calculates the time dilation of any point of an external Galaxy (e.g...

I keep seeing a popular question asking about atmospheric pressure "crushing" us. The word "crush" throws me off. It is my understanding that air molecules create pressure due to collisions. In other words, the molecules exert pressure due to having kinetic energy - and the more molecules you...

I am curious if the motion of massive object can effect it's gravitational influence due to the fact that gravitational waves travel at the speed of light. For a weak analogy, consider how a small object can make bigger ripples in the water if it is moving around more. I am curious if there...

The Wikipedia page on gravitational time dilation (https://en.wikipedia.org/wiki/Gravitational_time_dilation) states: "Relative to Earth's age in billions of years, Earth's core is effectively 2.5 years younger than its surface." A clock subjected to less acceleration (gravitational or...

Is it a fair prediction to state that in the next several years or so, globally, there will be major investments into gravitational wave research, and many more ‘LIGOs’ being developed? Is it a good idea to venture into that area of physics?

If gravity is effected by "wave particles", per Einstein's theory and now confirmed by recent observations, why do we not detect 'interference' - gravitational 'shadows' - or do we? Consider that with light waves, a photon once it hits a detector, nothing behind the detector registers the...

Homework Statement Somewhere between the Earth and the Moon there is a point where the gravitational potential due to the Earth exactly equals that due to the Moon. i)At what distance from the Earth is this point? Mass of Earth = 5.98x10^24 kg Mass of Moon= 7.35x10^22 kg Distance between...

Homework Statement The change in gravitational potential energy of a mass m as it moves from the surface to a height h above the surface of a planet of mass M and radius R is given by: ΔPE= GMmh/R(R+h) a) show that when h is very small compared to R , this approximates to the more familiar...

If someone wanted to pursue a career in gravitational wave physics, and work at places like LIGO, studying astrophysical objects such as black holes and neutron stars, etc. What are some key courses/skills that person should take/learn as an undergraduate, and graduate student?

In his GR youtube talk ( , starting 24:30), Susskind shows that a light photon on straight path in a stationary frame has a curved path in an accelerated frame. Concluding, as did also Einstein, that gravity deflects photons. But exactly the same argument applies to massless particles. Meaning...

If a beam of light is shot from a fast space ship, it travels a distance c*t1 according to their reference frame. The same beam of light seen from an outside observer goes at an angle and travels a distance c*t2. The distance the spaceship travels is equal to v*t2. Using the triangle made from...

Homework Statement Not give any information just the equation Fg= G m1m2/r^2 Supposed to find the distance at which the moons gravity has a greater force on a spacecraft than the Earth does. Homework Equations My prof told me to put G m1m2/r^2= G m1m2/r^2 and substitute one r in for another...

Homework Statement I don’t understand why this would relate to cosine and not sine, if gravity is often assiciated in the up and down part of a free body diagram. Homework Equations Wg=mgdcos(theta)[/B]The Attempt at a Solution Is it because it would depend on your reference frame?

does the mass on the surface of the planet (in state of rest ) has inside it the same gravitational energy to a similar mass after a free falling above its surface for one entire second?

I was thinking about the idea of looking up at a particular minuscule spot in the sky to see a particular planet at a very precise time, say, with a telescope. I was considering how light takes a matter of minutes to reach us. But then, remembering that gravitational forces must travel through...

Hello, I am trying to find a function x(t) that describes a particle falling into a gravitational well from a certain distance. So, for example, I am trying to figure out the differential equation: F = m*(dx^2/dt^2) = -GMm/x^2. Or simply, dx^2/dt^2=-GM/x^2 or even more simply, x''(t)=-k/x^2...

Consider an "unidimensional elevator" of size L accelerating w.r.t. a given inertial reference frame. Suppose each elevator's point accelerates with a constant proper acceleration ##g## according Rindler acceleration profile. In the given inertial frame with coordinates ##(x,t)## the elevator...

Assuming that the multiverse hypothesis is true and a singularity at the center of a black hole can give rise to another baby universe. Can we detect such an event in the LIGO observatory?