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Homework Help: General Relativity Equations

  1. Jul 21, 2012 #1
    1. The problem statement, all variables and given/known data

    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.

    2. Relevant 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.

    3. 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?
  2. jcsd
  3. Jul 21, 2012 #2


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    Science Advisor

    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?
  4. Jul 21, 2012 #3
    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.
  5. Jul 21, 2012 #4
    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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