Dave de Vos
Everything that exists is inside the realm of physics, more or less by definition. But that's not the same as saying that everything can be explained very well using only the language and concepts of physics. I can't explain beauty using only the language of physics. Does that mean that beauty is a useless term?
I think "martial ki" refers to a special coordination between mind and body that can be learned. I don't think it's beyond scientific measurement. The difference can be physically felt by other people, so I think that, in principle, scientists should be able to measure its external effect in terms of force and motion. But it's probably quite hard to scientifically describe and quantify the difference between "normal" body mechanics and body mechanics with "martial ki" in a way that is of practical use for martial arts training.
The problem is a mismatch between information and learning. For example, how would you scientifically distinguish a good dancer from a bad one? Surely the difference could be measured by collecting physical data from sensors and video and analyzing it, but this still leaves the problem of translating the measurements to training guidance for those aspiring to become good dancers. I think a dancing teacher would do a much better job using language and concepts that have little to do with science. Ki is such a concept.
BTW: I think initially the term aikido was intended to specifically refer to this special coordination between mind and body. I know that the founder himself added more meanings as the years went by and many translations / explanations have been given by countless other people, but I'm thinking something like synthesis spirit way, or more explicitly the way of using spirit for synthesis [of mind and body]
For a number of years I taught Aikido to professional dancers. Most of them trained in different styles of modern dance. One of these methods involved the notion of dancing from ones organs. They would start a class with very small deliberate movements, movements that at first could hardly be seen by a person watching. They imagined that their organs were initiating the movement. Normally we are hardly conscious of our organs and the last thing that we would want is that our kidneys are moving around in our body. The teachers and dancers knew this very well. They used it strictly as an image, as a metaphor (I would not even call it a concept) to improve their way of movement and to physically and mentally understand their movements better.
There really would have been no point in doing medical tests to find out if their kidneys or liver, etc were really moving.
To add to this; a better scientific understanding of something does not always lead to an improvement in body movement or in a healing process. Images, phantasy, metaphor, myths, even reading a book, watching a movie or listening to music may bring better or quicker results.
The Tour de France has begun this week and that reminds me of Lance Armstrong who won the Tour by using music.