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Using einstein field equation

  1. Mar 25, 2009 #1
    Gµv + Λgµv = (8πG/c4)Tµv
    I have several questions. what is the µv? when we use it today do we use the cosmological constant even though the universe isnt static or does it mean something different than einstein orignally thought? what are we measuring when we use this if theyre all constants?
    Last edited: Mar 26, 2009
  2. jcsd
  3. Mar 26, 2009 #2


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    I don't know the alt code either, but here's a copy-paster: Λ (from Wikipedia :))

    The mu and nu are tensor indices, indicating that G, g and T are two-tensors. If you don't know what they are you should first of all learn about them, because they are very important constituents of the language in which GR is formulated (I recommend Carroll's book), but for now you can consider G, g and T as 4 x 4 matrices and mu, nu as simply indices, for example G00 is the top left component, etc.

    The cosmological constant was written off a long time ago, but recently interest in it has arisen again. It can quite nicely explain some of the "odd" observed properties, such as the acceleration of the expansion rate of the universe and the fact that there seems to be more energy content than we'd expect. This might get you started, more advanced questions I will leave to the cosmologists out here :)
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