hey Dan how did you come up with US?
Universe Sandbox is the result of many experiments and iterations of a basic idea. I've been wanting to make something like this for a long time and I've always been fascinated by how such a simple equation (Newton's law of gravity) can result in something so amazing.
I wrote my first very basic gravity simulator in 1993, expanded that in 1994, and again in 1997. A few years later I started working with 3D graphics and particles effects, but I abandoned the project before it became something more than working concept.
http://dandixon.us/programming/planets.htmIn 2007 I picked the idea up again, modifying a simple trebuchet concept that I was working on. This time I already had a physics library in place and was fascinated with watching spheres collapse into a larger structure. Over a weekend I modified the code to use real world units (instead of arbitrary values) and decided that it would make a good portfolio piece. After another few months of work I decided to post it on the internet and the response has been more positive that I ever expected. Since then I've added galaxies, clusters, chart mode, and dice orbiting bowling balls.
In the next few months I'll be releasing a new version with a completely redesigned user interface. This update will make Universe Sandbox easier to use and accessible to more people. I can't wait to share it with everyone.