It looks like I haven't posted in here yet, and forgive me if I don't go through all 8 pages first, but I'll comment a little. In _Taijiquan, Classical Yang Style_ by Dr. Yang, Jwing-Ming, Chapter 2 covers the subject of qi and defining it. Parts talk about the more traditional definitions, about it being energy, and parts talk about a more modern definition. To quote one line from it, "It was not until the last few decades, when the Chinese people were more acquainted with electromagnetic science, that they began to recognize that this energy circulating in the body, which they called Qi, might be the same thing as what today's science calls 'bioelectricity'." Later on it goes into some anatomy and stuff to work on the modern definition. I guess my general feeling is that there is something there, some sort of energy you can call chi, and maybe you can define and describe it scientifically, but you don't really need to. Sometimes it's just easier to work with something as a general concept than to break it all down into its component parts to get a complete, scientific explanation of it.