# Second order action ADM formalism

I am trying to derive the second order action

$$S_{(2)}~=~\frac{m_{pl}^{2}}{8}\int a^{2}[(h_{ij}')^{2}-(\partial_{i}h_{ij})^{2}]d^{4}x,$$

used for tensor fluctuations derived from the ADM approach to the Einstein-Hilbert action. I don't really understand it. Can anyone help or recommend literature?

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did you mean ADM, not ADN? – twistor59 Mar 17 at 17:07