This total energy is called the ADM mass of slice \(\Sigma_t\)
\[
\displaystyle
\fbox{$ M_{\rm ADM} = {\dfrac{1}{16\pi}} \lim\limits_{{{S}}_{t}\rightarrow\infty} \displaystyle\oint_{{{S}}_{t}} \left[ \bar{D}^{j} \gamma_{ij} - \bar{D}_i (f^{kl} \gamma_{kl}) \right] s^i \sqrt{q}\;\hbox{d}^2 y $}\,
\]
原文：https://www.cnblogs.com/yuewen-chen/p/11537524.html