Stellar Encounters as an Example of Brownian Motion

Stellar encounters as an example of Brownian motion, outlines the similarities between stellar dynamics and the classical theory of Brownian motion. It emphasizes that the motion of stars under the influence of Newtonian inverse square attractions mimics the behavior of Brownian particles due to the cumulative effect of numerous small encounters rather than a few significant ones. This analogy highlights that while individual encounters between stars have minimal impact, their aggregate effect over time can lead to significant changes in stellar velocities and trajectories.

Dynamical Friction

Dynamical friction explains how the cumulative effect of stellar encounters leads to a phenomenon similar to friction in a viscous medium, termed “dynamical friction.” This effect causes stars to experience a gradual deceleration due to interactions with surrounding stars, effectively transferring kinetic energy from faster-moving stars to slower ones. Chandrasekhar provides the mathematical derivation of dynamical friction, demonstrating its emergence from the gravitational interactions between stars without resorting to heuristic methods. This analysis shows that stars with velocities lower than the average tend to be accelerated, while those with higher velocities are decelerated, leading to an overall energy redistribution within the stellar system .

This paper provides a comprehensive look at how principles from the theory of Brownian motion apply to stellar dynamics, illustrating the deep connections between different physical phenomena through rigorous mathematical frameworks.