How Can You Simplify General Relativity Equations Without Using Tensors?

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Homework Help Overview

The discussion revolves around simplifying the equations of general relativity without utilizing tensor notation. The original poster mentions a directive from their adviser to eliminate tensors from the equations, specifically referencing the Einstein field equations.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to manipulate the equations by substituting values for the metric tensor but encounters issues with the results. Some participants question the assumptions regarding the space being analyzed and suggest considering the implications of the metric tensor in different contexts.

Discussion Status

The discussion is ongoing, with participants exploring various interpretations of the problem. Some guidance has been offered regarding the treatment of the metric tensor, but no consensus has been reached on a specific approach or solution.

Contextual Notes

Participants note the lack of information regarding the specific conditions or scenarios under which the equations should be simplified, leading to uncertainty in the approach taken by the original poster.

Vardonir
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Homework Statement



Essentially, my adviser just told me to get the equation, then expand it so that it doesn't have any tensors. That's it. Just get rid of the tensors.

He said that this would be normally found in some textbook...? I've searched a lot of books, but I never saw anything that didn't have the equations in tensor form.

Homework Equations



I got Gμv = 8πTμv.

Reading further, I also got the following:
Gμv = Rμv - (1/2)gμvR
R = gαβRαβ

And I also found the Ricci tensor in terms of the Christoffel symbols but that's too long to type.

The Attempt at a Solution



What I tried doing is just plug in values of the greek indices and treat each one as a separate equation. However, when I use gαβ = diag(-1, 1, 1, 1), the left hand side always becomes zero.

Is there any other value of the metric tensor that I can use?
 
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The whole point of the Einstein tensor is that it is trivial in flat space, where there is no gravity. What you get for the Einstein tensor depends upon the metric tensor which, in turn, depends upon the distribution of mass in space. What situation are you assuming? You are trying to find the Einstein tensor for what space?
 
HallsofIvy said:
The whole point of the Einstein tensor is that it is trivial in flat space, where there is no gravity. What you get for the Einstein tensor depends upon the metric tensor which, in turn, depends upon the distribution of mass in space. What situation are you assuming? You are trying to find the Einstein tensor for what space?

I wasn't really given that much information, aside from "find the equations in terms of x, y, z, and t." I'm guessing Euclidean space, then.
 
I wouldn't plug in anything for the metric. Just leave the formulas in terms of [itex]g_{tt}, g_{tx}[/itex] and so on.
 

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