Gravity for Mac

From TriVectus:

Gravity is a chaotic, scientifically inspired screen saver created in OpenGL. At its heart is a collection of planets that exist in a miniature universe. Each planet has mass and velocity, and is affected by gravitational forces from all of the other planets. Eventually, the planets will collide, the victors gaining mass in the destruction of others. Planets will become larger and larger until they form into suns and finally black holes. The universe is not only populated by planets: spaceborne spectators will come to watch the chaos and cause a little themselves!