What I'm impressed about isn't just the work he's done - which is very impressive - but his ability to explain it. That skill is a very important skill to have.

He's written many other articles about his work: http://rsnous.com/index.html

And they all are great reads. I'm sure being able to explain his code has contributed to his skill as a programmer as well.

Well done, Omar.

12,000 years ago there was an impressive (for its time) dynamics demonstrator named "xspringies", (which is still listed on the rutgers site: http://www.cs.rutgers.edu/~decarlo/software.html ) it would let one build mobile or anchored objects with selected internal spring constants which would respond to various parameterized imposed forces. by now someone must've written something that would far transcend xspringies. i'll assume that this falling ball demo is more sophisticated and responsive in various ways along those lines.

This reminds me of Enigmo http://www.pangeasoft.net/enigmo/