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\textit{Oh, an empty article!} The interval for the Schwarzschild black hole looks like  You can get started by \textbf{double clicking} this text block $$  ds^2 = - \left(1- \frac{2M}{r}\right) dt^2 + \left(1-\frac{2M}{r}\right)^{-1} dr^2 + r^2 d\Omega^2  $$  It is associated with the Lagrangian  $$  L = - \left(1- \frac{2M}{r}\right) \dot{t}^2 + \left(1-\frac{2M}{r}\right)^{-1} \dot{r}^2 + r^2 (\dot{\theta}^2 + \sin{\theta}^2 \dot{\phi}^2)  $$  It does not depend explicitly on $t$  and begin editing. You can also click $\phi$, so $\frac{dL}{d\dot{t}}$ and $\frac{dL}{d\dot{\phi}}$ will be  the \textbf{Text} button below constants of motion:  $$  -\frac12 \frac{dL}{d\dot{t}} = \left(1- \frac{2M}{r}\right) \dot{t} = \epsilon  \\  \frac12 \frac{dL}{d\dot{\phi}} = r^2 \sin{\theta}^2 \dot{\phi} = \lambda  $$  Those are related  to add new block elements. Or you can \textbf{drag the energy  and drop an image} right onto this text. Happy writing! the angular momentum of the particle.  And we also know that for a particle with mass $m$  $$   -m^2 = p_\mu p^\mu = m^2 \frac{dx_\mu}{d\tau} \frac{dx^\mu}{d\tau}  $$