http://www.youtube.com/watch?v=8MWNs7Wfk84&feature=PlayList&p=858478F1EC364A2C&index=2" , Edmund Bertschinger is talking about Einstein's field equations . during the lecture , under the title of : "Gravity as sapcetime curvature (GR viewpoint) " , he wrote : "Freely falling bodies move along spacetime geodesics ....." this statement made me confused. what does this actually mean ???