Dan, there's a certain logic to this stuff that's difficult to go outside of, once you're in it. ... Imagine one of those snap-together flexible support-poles that form the outside through-the-loops structure of many lightweight portable tents nowadays. ... That example is the equivalent of pretty much all of Tohei's and Ueshiba's "withstand a push" demonstrations that they did. They formed flexible "poles" throughout their body, starting from the ground, at their will. ...
There are other ways of thinking about it, too, however. Waves are quintessential examples of conservation of angular momentum as somewhat divorced from the structures or medium in which they operate -- i.e. the energy travels globally, while the medium moves only locally, minimally and cyclically. This is an aspect of wave/particle nonduality at the macroscale.
While very simple in operation, it can be very spooky because the the actual cause of movement is relatively difficult to percieve, and the ultimate effect of the movement is highly unforeseen. Tsunamis are devastatingly huge, but they lift the surface of the ocean only a few inches and then drop it down again, hardly above background noise -- but coordinated with a totality of interaciton that is difficult to envision -- the total circulation system of the tsunami is from surface to the bottom and many, many miles long. The vortex energy in the water wave is cyclic and rotating, but the individual components of the medium simply go up slightly and then down again as the massive energy passes leaving them each barely disturbed.
Poles in the analogy operate as sprung structures, i.e. -- depending on material torsional or tensile strength as with mechanical springs (taking as a given that no one is pushing hard enough to crush bones in compression).
Sprung structures will vibrate in compression waves easily enough, but not in ways that concentrate kinetic energy in geometric terms as with a loosely bound snapping whip or flailing chain. Likewise, sprung structures do not as easily dissipate kinetic energy as with the attempt to push on a chain. The physical concept of vorticity and the Chinese "open/close" of joints are not that dissimilar in their understanding of the manipulation of this form of energy -- positively or negatively.
For Rob: the vibration shaking or trembling is just higher frequencies of waves particularly at the end of the limbs or the weapon where the positively applied rotational energy is constantly reducing in radius -- thus decreasing in wavelength and increasing frequency and geometrically increasing in total impulse when finally meeting the target. There are two squared energy terms in the relevant equations. In examples of fajin, which is very much given as example s on these topics, the whip model is precisely accurate, and for Tim -- some of the videos of that actually do show the result in the gentleman's cuffs snapping just like the end of the whip.
The whip or flail is the image of the positive concentration model -- the negative model is really best seen in aerodynamic lift, or in destabilized arches. Both are directly applicable also here. If you consider the joints or limb elements as individual whorls of briefly rotating energy, and adaptive in their "viscosity" or relative pliability under impulse, the way it works on the negative phase becomes more clear. Ellis Amdur's very persuasive argument that O Snesei's purpose in "editing" waza from DTR was in selecting those whose ukemi required opening and softening of joints fits this set of observations very closely. Lewis Richardson's doggerel poem is the among the best summaries of the dissipative principle:
Big whorls have little whorls
Which feed on their velocity,
And little whorls have lesser whorls
And so on to viscosity.
Grounding in one manner stores energy in the sprung structure, as Mike suggests. Grounding in another way, merely reflects the wave off the ground like a wave reflects off the beach -- One can generate waves as well as receive them, and thus the thing that can be controlled is the phase of generated wave, or that that the ground reflects, relative to the phase that is being received. I am not saying that grounded energy is not useful or applicable -- but it is not the whole story either - the Ki of Heaven is as just as useful as the Ki of Earth.
Like waves reflecting off the beach, if they meet the oncoming swells with peaks coinciding, the energy doubles and the oncoming wave's energy becomes unstable and breaks and falls down chaotically, or if the reflected trough coincides with the oncoming peak the energy literally vanishes at that point. No grounding required, and at no time do the energies collide or create resistance in the medium they are traversing, (they literally pass through one another), while at the same time causing interesting effects in the medium (bodily structure, in our case) at the point where they are meeting.
The largest energies may require this reflected grounding to avoid injury to weaker structures, but smaller energies may be reflected from any other suitable joint by meeting it with a negative or positive counter-phase, which in one phase is physically equivalent to meeting a barrier like the ground, or in the other phase, like falling into a hole. The body can be manipulate to control the phase delay to dissipate progressively, to transmit without much dissipation, or to alter the phase and magnitude in or joining with and transmitting it
The way in which the joints are addressed to the wave phase they are receiving/generating is another aspect of the "quantizing" of the angular momentum energy in a continuous/discontinuous form that I perceive to operate also in proper control of ma-ai, which I mentioned before.
The only significant difference is that ma-ai involves considering the connected person and oneself as one medium, and the fact that two minds may be involved in the interaction. In a sense, by attacking you give up your receptive mind (ukemi) in proportion to your commitment to the strike and thus only one mind may actually be operating in full possession of its senses at the moment of contact -- as O Sensei's numerous comments about attacking suggest.
Conversely, applied energy can also be eaten up in rotational inertia at each link in the chain if the body's joints are disposed correctly to receive the energy in dissipation. It can even be redirected back into the source along the yin line of the incoming wave going back the other way at the exact point of contact, although this is the most difficult and most highly trained manner of doing this.
A "wave" that is not focused along a connected, flexible, a focused path will simply be a "wave" (as cool as it sounds) and won't be particularly powerful.
No arguments -- action must occur with awareness and sensitivity.
Mike Sigman wrote:
To do it correctly takes a path from the ground, a trained connection, and a wave-path that is focused along the path from the ground to the target.
All except that grounding (in my sense of the term) is one way, not the only way. Several ways of applying angular momentum in the chain or whip model (tekubi furi undo as the chief example) actually "unground" the body and literally lift its weight with the applied acceleration UPWARD vice downward to ground -- making it more easily and speedily moved at a moment of critical contact WHILE applying energy into the target -- and not merely as a secondary reaction to that energy. The same can be applied in connection to the other person's body, either floating or grounding them depending -- if they are not able to make the necessary adjustments in turn .
The most critical application for utilizing the upward Ki pulse that enables swifter movement -- is with the sword. Both suri-age, and kiri-age, (upward and downward vertical sweeping cuts) can be performed so as to either lift or ground the body at several critical junctures in the movement, depending on the situation. The "vibrational" finish seen in ken suburi in Saito's curriculum makes this action somewhat visible.
It basically depends on whether you catch the applied angular momentum travelling down the body on the down cycle or the up cycle when you gird the undercarriage -- one lifts -- the other grounds. All of this has to be intuitive in action, although the reasons for doing one or the other depending on what is happening are perfectly capable of being analyzed to improve training.