In 1962, V. A. Antonov conducted simulations showcasing that gravitating systems can defy thermodynamic rules and get hotter instead of reaching equilibrium. If a group of stars in a sphere with elastic bounces and gravitational interactions are gravitationally bound, they may form a dense, hot cluster leading to a gravo-thermal catastrophe. To combat this, the sphere must be shrunk, but even then, it’s just a temporary fix as the system is in a metastable state. This phenomenon is explained in detail in an article by D. Lynden-Bell and Roger Wood. The study of point particles interacting via gravity helps understand realistic stellar clusters like globular clusters where stars can collide and form black holes.
https://johncarlosbaez.wordpress.com/2024/09/20/the-gravo-thermal-catastrophe/