Department of Physics, Rochester Institute of Technology, 78 Lomb Memorial Drive, Rochester,
NY 14623, USA
Abstract. Chandrasekhar’s most important contribution to stellar dynamics was the concept of
dynamical friction. I briefly review that work, then discuss some implications of Chandrasekhar’s
theory of gravitational encounters for motion in galactic nuclei.
Keywords. Celestial mechanics; relativity and gravitation.
PACS Nos 95.10.Ce; 95.30.Sf