In ref to a previous question collision between RB and softbody objects? lbalazscs kindly remarked I just noticed your video on flickr, I think it is pretty good, apart from the timing: the ball moves slowly, suggesting a large object, but the "jello mattress" moves fast, suggesting a smaller object.
This causes me to ask, is it actually possible to have 2 objects (interacting!) in a physics simulation, and have them running on different clocks, i.e. deliberately slowing down one object to give it the illusion of greater mass rather than just adding mass to its physical properties. I thought there was only one master clock for the whole physics world.