I first quickly review the decades-long history of the development of the methods for simulating the dynamical evolution of star clusters, with additional discussion of N-body methods. Then I survey some things that can or could go wrong, with particular attention to the role played by the theory of two-body relaxation.
Dwarf Spheroidal galaxies and Ultra Faint Dwarf galaxies orbiting around the Milky Way are commonly considered as dynamically "hot" systems so that the high velocity dispersions measured could be compatible with a virial state just if their total mass is very large respect to the luminous mass. This led to the consideration that they are the most dark matter (DM) dominated stellar systems in...
As a graduate student I had the privilege to learn from Daiichiro Sugimoto (then Visiting Gauss professor at Uni Goettingen) and Erich Bettwieser. A gaseous or moment model of star clusters was designed. Gravothermal oscillations were detected using this model, which inspired star cluster dynamics for many years, if not decades. I could contribute a little to the model by adjusting the heat...
