Aah... a clear line of demarcation.
Matthew's proposition - There are no things in the martial arts that cannot be explained by physics.
Mark's proposition - It is a fact that some things in the martial arts cannot be explained by physics.
It's at this point that the experimental physicist would devise an experiment to test which of the above propositions is supported by experimental data. Anyone care to contribute to the design of said experiment? Thought experiments welcomed.
No experiments needed. Let's step back from the martial arts world for a moment. If we look at physics overall in the entire world by the best and brightest physicists out there -- there is no known way to describe via physics how the human body goes from a walk cycle to a run cycle. Can't be done. This simple thing that the human body does on a subconscious level can not be derived in the physics world.
Now, to expand on that, let's look at the robotics area in the entire world by the best and brightest engineers and programmers out there. There is no known way to create and program a robot derived from a human model. Can't be done. Simple things we take for granted in our bodies have yet to be revealed in either physics, robotics, or programming.
Now, let's go back to the martial arts world. Many people like to use simple physics to explain jujutsu principles. The fact is that they are not using physics at all, but are creating a picture in a person's mind of the principles they are trying to get across.
Human beings are a self contained collaboration of a multitude of complex operational systems that do not work the same from person to person. They do not have to respond like simple physics models. That they do, is only because they have been programmed to.