This is an implementation of the barnes-hut algorithm, which allows simulating n body systems in O(n log n) time. It also includes a a simple particle renderer for the "stars".
The actual algorithm is technically broken. There is a small ghost force which acts on particles in dense regions of the quad tree. This is not super obvious, and it still produces pretty pictures, which is all I really wrote it for anyways :p
Also, this is a toy project, so a lot of magic constants, etc, etc.