Physics

Prof. Seshadri. Sridhar
Raman Research Institute, Bangalore

Abstract :

The classical N-body problem is about the motion of N point masses exerting
inverse-square, gravitational forces on each other. Open clusters, Globular clusters and Galaxies are stellar systems consisting of many stars (N = 10^3, 10^6 and 10^11), with well-separated 
orbits. Since many stars are long-lived, the large N limit of the classical problem applies to these
systems. Their physical properties are very different from the many-body systems usually 
encountered in the laboratory, because gravity is a long-ranged and purely attractive force. 
Observations over the past few decades provide evidence for super-massive black holes at the 
centres of galaxies. Orbiting these black holes are dense star clusters, whose dynamics and 
statistical mechanics are remarkably different from even other stellar systems. The reasons lie 
in the familiar Kepler problem (of two point masses on elliptical orbits) and the principle of 
averaging in classical mechanics.