Reversed Gravitational Acceleration for High-speed Particles
  Examination of the free-fall motion of particles of extremely high-speed in the Schwarzschild geometry reveals that the gravitational acceleration of such particles is reversed when measured in Schwarzschild coordinates. High-speed particles decelerate when moving radially downward, and they accelerate when moving upward. The onset of this abnormal behavior occurs at a speed of 1/Sqrt(3) times the local value of the speed of light. However, the gravitational force always remains attractive. PACS numbers: 04.20.-q, 04.20.Cv, 01.65+g 
Hans C. Ohanian
gr-qc