Tai chi is a form of qigong, which means “energy work”. There are multiple types of energy that move through the body, and some are more subtle than others. This need not be an esoteric practice, however, as there is no real distinction between the definition of the “energy” felt in tai chi and the scientific definition. In physics, energy can take on multiple forms, including mechanical, chemical, electrical, and potential. Kinetic energy is the energy of matter in motion, and is associated with momentum. It happens that kinetic energy is the easiest form of energy to feel in the body, because it is the most macroscopic, and we can all feel movement. However, all types of energy flow along the same channels and in the same way. Therefore, developing the sensitivity for how kinetic energy flows through the body, as well as the ability to direct and project it, also develops the capacity to work with other, more subtle forms of energy.
Many people feel frustration with their tai chi practice when they are told to “feel the energy”, but are not sure what they are supposed to be feeling for. “Trying” to feel the more subtle forms of energy before you truly develop a feel for kinetic energy is barking up the wrong tree, as far as tai chi is concerned. You might develop some type of skill by doing this, but not the physical capacity that tai chi has the potential to develop. On the other hand, by developing the sensitivity to feel and work with kinetic energy, you will develop your physical capacity as well as open the channels along which the more subtle types of energy also flow. As your sensitivity develops through this practice, you will begin to feel these subtle forms of energy, at which point you can start to work with them, but trying to work with them if you can not actually feel them is a distraction from what should be the true purpose of your practice.