Contracting Riemann tensor with itself

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SUMMARY

The forum discussion centers on the contracting of the Riemann tensor with itself, specifically referencing chapter 8 of Padmanabhan's "Gravitation: Foundations and Frontiers." The equation presented, ##R_{abcd} R^{abcd}=\frac{48 M^2}{r^6}##, is scrutinized for its validity. It is established that the anti-symmetries of the Riemann tensor do not imply that this quantity is zero; rather, it is identified as the Kretschmann scalar, which is crucial for understanding the nature of singularities in the Schwarzschild metric.

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ShayanJ
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In chapter 8 of Padmanabhan's "Gravitation: Foundations and Frontiers" titiled Black Holes, where he wants to explain that the horizon singularity of the Schwarzschild metric is only a coordinate singularity, he does this by trying to find a scalar built from Riemann tensor and show that its well-behaved at the horizon. He writes (eq. 8.3) ##R_{abcd} R^{abcd}=\frac{48 M^2}{r^6}##. But this can't be correct. The (anti-)symmetries of the Riemann dictate that ##R_{abcd} R^{abcd}## is equal to zero. What is he doing here?
Thanks
 
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The anti-symmetries do not dictate that this is zero.
 
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Also, this quantitiy is called the Kretschmann scalar. You may have seen posts about it recently.
 
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