Your think/do loop is obviously very tight and you don't have to consciously will your body to move as a separate act.
I have used the example before, but there is a study out there that talks about the gap between the average body reflex to hit a baseball and the time it takes for the ball to travel from the pitcher to the plate. Personally, I belive that something must exist which allows this gap to be bridged, as evidenced by Major League baseball.
"Just" makes me nervous. The foundation of aiki may be "just" good physics, but I am not sure about aiki. My first instructor used to differentiate between musubi and aiki. Musubi was a solid foundation and a connection with your partner. Aiki was more.
Saotome Sensei used to describe driving a car in analogy to aiki. In the beginning, we need to concentrate on on feet and the petals, both our hands steering the wheel, constantly checking our mirrors. Then, gearing into first on a incline... Holy s&#%
. What about taking a hand off the wheel to use the turn signal... Which way does the d%#$^ thing go
. Over time, we become more comfortable with the process and our body and mind start to work together and next thing you know... flipping radio stations while putting on make-up and texting the honey-do list. Not that I ever do that while driving...because that would be dangerous... and illegal...and I don't wear make-up.