Chi, to me, has nothing to do with physics, rather, with psychology. In my experience with martial arts, I believe that Chi is not PHYSICAL energy, just like many of you. But, I have an explanation for what it is. I could just tell you that Chi is a spiritual channeling of energy, but this would be only a partial truth.
The "energy" that you channel, chi, is the feeling of strength, confidence, or, "spirit". Anyone who, for instance, breaks concrete using "chi" could have done the feat without "chi", but not as easily, because their mind would not be prepared for the attempt.
Another good way to describe chi is thus.
-The stomach is the root of the body.
-If the mind is uneasy, if you are nervous, upset, angry, that is the mind, the stomach remains steadfast.
-Chi is the name for the strength that lies in the stomach.
-Using Chi, you can mask, and eliminate all mind delusions, and cover yourself in a blanket of truth, that you CAN conquer whatever you want.
-Chi gives the feeling of solidness, like you are a rock, with no negative emotion.
spiritual example: when you have a horrible feeling of dread, the "pit of your stomach" is the last point where it can be felt. This is because no delusional emotion such as greed can dwell in such a powerful place
*bows*