Einstein field equations Definition and 51 Threads

Hi, I'd like to discuss in this thread the propagation of Gravitational Waves (GW) in the context of GR. Just to fix ideas, let's consider a FW spacetime. It is not stationary (even less static), however the timelike congruence of "comoving observers" is hypersurface orthogonal. Suppose at a...

Years ago I posted a thread where I solved for the exterior vacuum metric for a static spherical mass using only a single one of the unknown functions, A, B, or D, where D = C r^2, since they are inter-related. A moderator here graciously supplied the EFE's as A, B, and D relate to the energy...

So, there are a fair amount of metrics designed with a zero value for the cosmological constant in mind. I was wondering if there was some method to modify metrics to account for a nonzero cosmological constant. Say, for instance, the Schwarzschild metric due to its relative simplicity. A...

[Moderator's Note: Thread spin off due to topic and level change.] For a spherically symmetric solution, if SET components were written in terms a single one of 4 coordinates, in a way plausible for a radial coordinate, the I believe solving the EFE would require spherical symmetry of the...

Let's say I want to describe a massive box in spacetime as described by the Einstein Field Equations. If one were to construct a metric in cartesian coordinates from the Minkowski metric, would it be reasonable to use a piecewise Stress-Energy Tensor to find our metric? (For example, having...

HI, I'm curios about the analytic derivation of Mercury perihelion precession starting from EFE - Einstein Field Equation (or simply just from Schwarzschild solution of the EFE). Can you advise me about some source or online material to learn it ? Thanks.

Is it true that the Einstein Field Equations have an infinite number of solutions when the pressure is zero?

I would be grateful if some one would consider my following thought and indicate to me the likely mistakes, which I cannot do. Following the paper “Why the Riemann Curvature Tensor needs twenty independent components” by David Meldgin UC Davis 2011, I understand that with a coordinates...

Most often, general relativity is formulated in terms of Einstein's field equations: whose terms are familiar to readers in this forum. But, I understand (and feel free to correct me or qualify my statement if I am incorrect) that it is also possible to describe general relativity with an...

What do I have to do if I want the EFE's to approximate a weak gravitational field, where for example, an inversely proportional to the cube ( ##1 / r^3## ) of the distance law between the masses applies?

I am not familiar with tensors and I would like to know if it's possible to understand GR without using them. I imagine we use them to describe four-dimentional space-time, because a regular vector or matrix wouldn't be enough. Is there an analog of Einstein's equations for a 2D space (plane)...

So, rather than causality and time travel paradoxes and the like that are usually discussed about relativity, I'm curious about something else. On one side of the Einstein Field Equations is the Stress-Energy Tensor, along with some constant coefficients (G, c^-4, etc), which essentially...

This past semester, I just took an introductory course on G.R., which translates to a lot of differential geometry and then concluding with Schwarzschild's solution. We really didn't do any cosmology. However, one of the themes that kept creeping up again and again is that in 4-dimensions...

Hello dear friends, today's question is: In a non static and spherically simetric solution for Einstein field equation, will i get a non diagonal term on Ricci tensor ? A R[r][/t] term ? I'm getting it, but not sure if it is right. Thanks.

Hi all - I am trying to follow a derivation of the above. At some point I need to find gαβ for gαβ = ηαβ + hαβ with |hαβ|<<1 I am stuck. The text says gαβ = ηαβ - hαβ but I cannot figure out why. Can anybody help?

Hello I am little bit confused about calculating Ricci tensor for schwarzschild metric: So we have Ricci flow equation,∂tgμν=-2Rμν. And we have metric tensor for schwarzschild metric: Diag((1-rs/r),(1-rs]/r)-1,(r2),(sin2Θ) and ∂tgμν=0 so 0=-2Rμν and we get that Rμν=0.But Rμν should not equal to...

Hello I've been have been done some research about Einstein Field Equations and I want to get great perspective of Ricci tensor so can somebody explain me what Ricci tensor does and what's the mathmatical value of Ricci tensor.

Given that no assumption is of a point energy is necessary to derive the vacuum (Schwarzschild) solution to the EFE, why is the solution assumed to apply to spacetime surrounding a point energy?

Hello, can somebody please help me understanding the following. Action of general relativity consists of two terms: action of gravitation, dependent on metric tensor and its derivatives; action of matter, say one freely moving point mass particle, dependent on particle coordinates and metric...

Hello all, first post. I have come here to get second opinions on the program I have written to compute the Einstein Tensor (the Riemann Tensor and Ricci Tensor). I enjoy looking for solutions to the Einstein Field Equations, however computing them by hand is not realistic. I decided to write a...

In the Einstein Field Equations: Rμν - 1/2gμνR + Λgμν = 8πG/c^4 × Tμν, which tensor will describe the coordinates for the curvature of spacetime? The equations above describe the curvature of spacetime as it relates to mass and energy, but if I were to want to graph the curvature of spacetime...

Hello dear Physicists, I am very curious about understanding the math and the nature properties of the Einstein Field Equations.What I need to know is,what concrete mathematical operations I need to know and understand,and have experience with to understend this theory.I'm a quick learner and...

Homework Statement I am given this metric: ##ds^2 = - c^2dt^2 + a(t)^2 \left( dx^2 + dy^2 + dz^2 \right)##. The non-vanishing christoffel symbols are ##\Gamma^t_{xx} = \Gamma^t_{yy} = \Gamma^t_{zz} = \frac{a a'}{c^2}## and ##\Gamma^x_{xt} = \Gamma^x_{tx} = \Gamma^y_{yt} = \Gamma^y_{ty} =...

Homework Statement [/B] (a) Find the christoffel symbols (b) Find the einstein equations (c) Find A and B (d) Comment on this metric Homework Equations \Gamma_{\alpha\beta}^\mu \frac{1}{2} g^{\mu v} \left( \partial_\alpha g_{\beta v} + \partial_\beta g_{\alpha v} - \partial_\mu g_{\alpha...

How do you represent einstein field equations with levi civita symbol or jacobian determinant? I saw a lot of work that involves this but I don't know how and why. Besides how is the jacobian determinant related to the levI civita symbol?

Homework Statement (a)Find Christoffel symbols (b) Show the particles are at rest, hence ##t= \tau##. Find the Ricci tensors (c) Find zeroth component of Einstein Tensor Homework EquationsThe Attempt at a Solution Part (a)[/B] Let lagrangian be: -c^2 \left( \frac{dt}{d\tau}\right)^2 +...

In the Einstein-Hilbert action wikipedia page, the following paragraph is written: I thought for treating spin, we need to consider Einstein-Cartan theory! This is really surprising to me. Can anyone suggest a paper or book that explains this in some detail? Thanks

I'm a bit confused about the derivation of the Schwarzschild radius. I can do it quite easily using Newton's Law of gravitation, but this law is only an approximation, so I am wondering whether the result I obtain, r_{s}=\frac{2GM}{c^{2}}, is an approximation or not. It seems to me that it...

Hello Everyone, I have read many derivations of Einstein field equations (done one myself), but none of them explain why the constant term should have a $$c^4$$ in the denominator. the 8πG term can be obtained from Poisson's equation, but how does c^4 pop up? Most of the books just derive it...

From what I know, to get the reverse trace form of the Einstein field equations, you must multiply both sides by gab (I didn't have a lot of time to make this thread so I did not spend time finding the Greek letters in the latex). This turns: Rab- \frac{1}{2}gabR= kTab (where k=...

Hello everybody. I was recently brainstorming ways to make the Einstein field equations a little easier to solve (as opposed to having to write out that monstrosity of equations that I started on some time ago) and I got an interesting idea in my mind. Here, we have the field equations...

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Hi, Are Einstein's field equations without the cosmological constant scale invariant? If so does the addition of the cosmological constant break the scale invariance? John

A typical formulation of the Einstein equations is R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}+\Lambda g_{\mu\nu}=\frac{8\pi G}{c^4}T_{\mu\nu} The \frac{G}{c^4} make the units work out. What about the 8*pi? Why is this necessary?

I'm reading Spacetime and Geometry: An Introduction to General Relativity by Sean M. Carrol and in the chapter on gravitation, he derives the Einstein Field Equations. Here is the part I don't get. He starts with the equation R_{\mu\nu}-\frac{1}{2} Rg_{\mu\nu}=\kappa T_{\mu\nu} Wher R_{\mu\nu}...

Hi everyone, Say that one can separate the metric of a space time in a background metric and a small perturbation such that g_{\alpha \beta}=g'_{\alpha \beta}+h_{\alpha \beta}, where g'_{\alpha \beta} is the background metric and h_{\alpha \beta} the perturbation. Computing the christoffel...

I have seen and read a few different versions of the Einstein field equations (EFE). For example; R_{\mu\nu} - \frac{1}{2}g_{\mu\nu}R = - 8\piGT_{\mu\nu} , R_{\mu\nu} - \frac{1}{2}g_{\mu\nu}R + g_{\mu\nu}\Lambda = \frac{8 \pi G}{c^4}T_{\mu\nu} , and 8\piT_{\mu\nu} = G_{\mu\nu} So which one is...

Hi all, I have been trying to solve the Einstein Field Equations for its (0,0) component. So I have got that (c=1) Einstein Tensor (upper,0,0)=8*pi*G*T(upper,0,0) Now, let's see what T (0,0) really is. It is energy density, right? So According to famous E=mc^2 the energy density is the same...

Hi all! When we talk about the Einstein Field equations. What do we mean with "extremal proper time" or "extremal path"? Why "extremal" ? and why "proper" ? and why do we need to introduce the concept of "geodesic" ? Cheers

Can one deduce from the einstein field equations: -Conservation of mass -Conservation of energy -Conservation of mass-energy -Conservation of linear momentum -Conservation of angular momentum -Principle of least action ? And does curvature of space-time has a "potential" on certain...

So I am an engineering graduate trying to teach myself some general relativity. I have tried to solve the Einstein Field equations for a wormhole metric and some others. After pages and pages of calculating Christoffel Symbols, Riemann Tensors, Ricci Tensors and Scalars, and so on, I end...

For Minkowski spacetime, the metric is: ds^2 = -dt^2 + dx^2 + dy^2 + dz^2 I have read there is a solution when the time dimension is "rolled" into a cylinder forming a closed timelike curve. So the BC is t -> [0,T] with t = 0 identical with t = T. The Field Equation is: Rab - 1/2...

1) What exactly does the metric tensor expand into? Since it describes general space-time, shouldn't it be more like a vector like R = √(x^2+y^2+z^2) Why even should we use tensors in relativity when we can just stick with vectors? 2) Are the equations all theoretical? Have they been...

Einstein Field Equations? I have not been able to comprehend the Einstein Field Equation, the Stress Energy Tensor, the Ricci Tensor, the Einstein Tensor, and Christoffel Symbols. Though I am reasonably proficient at working with nested loops in programming, and I have a rudimentary knowledge...

Why should we trust the Reissner–Nordström solution of charged black holes? It relies on coupling between Einstein tensor and EM stress-energy tensor, which has NO experimental support whatsoever. Is there any chance we can test this?

I understand the difference betw mathematical and physical pi. I also understand that in non-Euclidean space the value of pi would differ depending on a surface's deviation from flatness. But is there a different symbol for physical pi, to distinguish it from mathematical pi? Because I...

Can someone explain the equation G_{\mu\nu}+\Lambda g_ {\mulnu}={8\ pi G\over c^4} T_{\mu\nu}\ by Albert Einstein?

Are the phrases "Linearized gravity", "Linearized Einstein Field Equations", "GEM (gravitoelectrodynamics)", all referring to mathematically equivalent approximations of Einstein's full non-linear field equations? If not, could someone tell me what order (in some rough sense) these would be...

Hello, As with a lot of people, I have been excited and fascinated by the field equations Einstein described, revealing the curvature of spacetime. I would like to create a computer simulation which simulates the effects of the Einstein Field Equations, in other words, the curvature of...