Show that photons moving in the radial direction have coordinate "velocities" given by dr dtff = 1 ( 2M r )1/2 . This is one indication of a physical picture of the spacetime in these coordinates: space itself is falling inward at a radially dependent speed given by 2M/r! Hence one must exert oneself to move outward through this inflowing space. Why is it then that a material particle cannot escape the event horizon at r = 2M