Is This Invariant Calculation Correct?

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Homework Statement



Calculate the invariant
<br /> E^{\alpha \beta} E_{\alpha \beta}<br />



Homework Equations





The Attempt at a Solution


we apply the metric in this case,
<br /> E^{\alpha \beta} E_{\alpha \beta} = g_{\alpha n} g_{\beta m} E_{n m} E^{n m}<br />

is that even correct?
 
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Nusc said:
we apply the metric in this case,
<br /> E^{\alpha \beta} E_{\alpha \beta} = g_{\alpha n} g_{\beta m} E_{n m} E^{n m}<br />

is that even correct?

No, that equation is non-sensical...on the lefthandside \alpha and \beta are dummy indices (they are being summed over)...on the righthandside they are free indices and you also have m and n appearing 3 times (which is notational nonsense).


I assume you are given either E^{\alpha \beta} or E_{\alpha \beta}?
 
To solve this, I first used the units to work out that a= m* a/m, i.e. t=z/λ. This would allow you to determine the time duration within an interval section by section and then add this to the previous ones to obtain the age of the respective layer. However, this would require a constant thickness per year for each interval. However, since this is most likely not the case, my next consideration was that the age must be the integral of a 1/λ(z) function, which I cannot model.
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