QG v19.6.30 www.grelf.net
Up to 10 particles of different colours move around a central mass attracting them by an inverse square law. The motion does not exactly obey Newtonian mechanics. When particles collide interesting changes can occur.
All tracks are erased 1,000 time steps after they were drawn, causing black traces. You may observe in the background that erasure is not complete; this is due to antialiasing when lines are drawn.
It is believed the program can keep running indefinitely if it is allowed to.
Some would categorise this as algorithmic art. Is it art? I really don't know. All I can say is that some of the shapes that it draws hold a certain fascination. The fact that they are not exactly symmetrical or concentric probably helps.
The program started around 1990 based on an extremely naive idea about quantum gravity (QG). If, as some physicists think, at an extremely small scale time must be quantised then the kind of behaviour shown here could occur. Time steps could not be small enough to integrate the equations of motion correctly when very close to an attractive source.