9. Geodesics.

MIT General Relativity, Spring 2020 Instructor: Scott Hughes View the complete course: YouTube Playlist: The kinematics of bodies in spacetime.  Free fall described by geodesics: trajectories that parallel transport their tangents through spacetime, and extremize the experienced proper time.  How symmetries of spacetime lead to quantities being conserved along geodesics; associated notions of 'energy' and 'angular momentum' for certain spacetimes. License: Creative Commons BY-NC-SA More information at More courses at Support OCW at We encourage constructive comments and discussion on OCW’s YouTube and other social media channels. Personal attacks, hate speech, trolling, and inappropriate comments are not allowed and may be removed. More details at