"Physically Based" has somewhat turned into the CG/gamedev version of "Big Data". I remember reading a paper about physically based facial animation or modelling. Which uses the concepts of facial tissue and muscles to realistically render faces. It went all downhill after that though. We'll probably soon see a re-release of asteroids called "Physically Based Asteroids" because there is a multiplication in there somewhere that reminded the author of Newtons second law.