1. The physics bit was very interesting and instructive. I liked it a lot. But a question you never answered is why it is good to let the energy/force run up through your bones and spine. I of course have some answers to that question, but I think it would be good for you to speak to why this is important. Does that make sense? Might seem really obvious to you, but might not be to everyone.
2. Re the tantra entry. I've always had a problem with faith. Not that I don't have faith, but more, what is faith and what do you really mean by it. There is a way that I do believe wholly in the forces that govern the world, us, our lives. And there is a way that I feel I am one with them. The latter is not a matter of faith. If the human body is indeed a sri yantra and when we interact with these forces in our practice, we also interact with these parts of ourselves, then where is 'faith' in that? I look at Ganapati and Laksmi and Lalita on my altar and feel both reverent and on par with them at the same time. I recognize and surrender to those forces which are bigger than 'I' but at my core, I know I am also their equal, that we are the same. There are times when I don't know if this is hubris or recognition. The small, human part of me looks at them as beings other than myself, and I ask them for help and guidance. Another part of me looks at them as old friends and what I feel is not faith as much as recognition or something harder to define.
1. I meant to answer this in a later post and will have an entire article on bone strength. Basically the short answer to this is that stresses on bone will increase its strength. So from a purely physical basis we are in fact strengthening the bones with this type of bone force work. I will explain this in more detail later. Blood quality is also increased as the bones, which are responsible for blood production, are stimulated. Different energetic centers that exist within the bones are also affected. The subjective feeling which we feel through the bone I call "energy". The working of the bones in this way acts to store chi or prana in the bones which can actually be felt as one increases in sensitivity. This work really requires deep instrumental level awareness to notice this.
2. What I mean by faith is that which strengthens belief, creating a world view which becomes solid and thus has the power to direct the mind in a particular direction. Faith to me is a deep orientation of one's self that serves as a foundation for belief/view, that acts as a sort of "armor" to protect against opposing views that might arise from one's own potentially contrary belief systems due to the nature of the multiple egos (see my other articles regarding my thoughts on how the ego is actually many). Why is belief or view powerful? Because it is the mind which creates the subjective world view, which in turn can affect powerfully the world at large. So our beliefs actually become very important if we have any hope of creating effective movement in this world. Faith acts to strengthen that belief, which is why it is important even before faith to cultivate pure discrimination. Otherwise our deep faith leads to potentially disastrous consequences (ex. fundamentalism and acts of religious oppression/aggression). Once decided, consistency brings movement leading to success in the given area of application. Without this we potentially fall prey to indecisiveness and the inability to affect forward movement. This is a purely subjective phenomena I am discussing here, which is why I also stated that it was vital not to criticize others beliefs. More important than the beliefs themselves, which are relative, is the power behind the beliefs, which I am describing here as faith. We are not talking about objective faith which would be attempting to hold to some objective "truth". It is more an inner act of strengthening which helps to sharpen will and personal movement. I feel this is vital to understand for success in deep spiritual sadhana.
Hope these answers clarify. Questions and opinions are always welcomed.