Neither, when you are sitting and turning left or right you are turning with upper torso, with the Thoracic spine.
I took your "hips or waist" as repetition instead of hips as lower part of yao and waist as upper part of yao to be chosen between.
It wouldn't be the first non-issue that I've belaboured.
When I wrote:
"The confusion is due to that the UPPER TORSO rotation can be seen as RELATIVE to the HIPS and lumbar area, especially if the hips are not moved."
I was recognizing that he was using a "temporal-locative" perspective.
Trouble is that when this relative movement is taking place it is happening in the flesh.
Its got everything to do with articulations.
Try and achieve this 'temporal-locative' change of relative position without moving the body.
Something can move in the flesh and also be relative to a positional overlay.
When one object or one part of an object moves, it moves relative to an indeterminate number of possible reference points.
Ie. when the upper torso turns on the thoracic spine it also moves relative to the moon but that is a non-issue.
Pivot is a "metaphor" for a location in space and time?
Thank god, metaphor is an application of a name or descriptive phrase to an object or action to which it is not literally applicable.
Although,this would be ok if the hips/waist were a metaphor for a location in space and time, as well as the upper body being such a metaphor also.
Then 3 metaphors would be moving relative to each other and no issue would arise re what happens when two parts of the body move relative to each other in real time space with real muscles.
No, the center of gravity is not a physical "thing".
It is an attribute of a physical thing. It is a point through which all of the weight of a body having mass is held to act relative to another body having mass.
It is not a convenient fiction as Daniel has led you to believe.
It is a precise location in a physical body that can be determined by suspending the object from a number of points.
It is one of the forces in our universe and acts in combination with a host of other forces acting on bodies.
Centers of gravity become relevant when one object moves relative to its own base, or as you say changes shape. Or I would say the relative locations of its parts change relative to each other.
It also becomes relevant when two objects are in contact so that the principle of the lever applies.
Assign the force of gravity and the points at which it acts to 'convenient fiction' status at grave peril.
The location of the center of gravity of any object can be precisely determined.
The relation of the center of gravity to a fulcrum or pivot point is such that when the two coincide there is equilibrium. When they don't there is displacement.
The center of gravity is not itself a fixed pivot point around which an object spins.http://www.s-cool.co.uk/topic_quicklearn.asp?loc=ql&t opic_id=5&quicklearn_id=8&subject_id=2&ebt=140&ebn=&ebs=&ebl=&elc=13
What if that slight turn did depart from classical principles. Would you abandon the turn or the principle?
There is more than one interpretation of the principles and some of them might exclude the turn not as a major contravention but as as an addition that is a stylistic addition without important practical use.
As it stands it allows upper torso turning independent of the lower torso, regardless of whether the lower turned before it.
The point being that the lower is not moving.
What happened to when one part moves all parts move, when one stops all stop?
Do we now have when one part stops other parts can move. Or when one part stops other parts can move as long as the other parts moved before.
As to the natural spirals, when the stuff seeps out between the spinal discs, it is also the gentlest of explosions which in caressing the sciatic nerves will give an seemingly extraordinary amount of sensation.
YZJ specifically proscribes movement that will incur that tension, so as to avoid it.
Why would he want to avoid it? What is the tension an indicator of so as to require a prohibition.
"By the way, where is your “pivot” while you are in the process of shifting your weight from one leg to the other? Or do you just wait until you’ve arrived where all of your weight is over one leg before you engage your pivot?"
My pivot for lateral weight shifts is the hip joint. I relax my knee a little, let the weight all sink to one side. My other foot now while still on the ground has not abandoned its position but is no longer supporting the weight of the body.
Some people may still have that empty foot support its own weight, sort of like a brace, but its no longer supporting the weight of the rest of the body.
This allows the appearance that it is still weighted. Keeps the other guy from knowing where the weight is. Keeps him from knowing which leg the center of gravity is closest to.
And, of course, I wait till all weight has arrived on that leg before I pivot my hip/torso laterally on that leg's hip joint.
Doesn't everybody? Do you move your leg when walking before all the weight is transfered?
The angle of the feet depends on where you want to go. The external/internal rotation of the leg determines the arc of lateral torso rotation and its direction.
Small frame/large frame can be confusing since it can take into account not only the space of the stance/step, but the amount of lateral rotation of the torso as well as the amount of vertical arc of the arms.
And then you can have combinations of this.
Eg. Slant flying needs only slight upper movements but may need a moderately large step to get one leg behind an opponent.
You can blind a person in any stance without torso rotation with just a flick of your wrist.
But this is with respect to applications.
When applied to describe the way the forms are done small frame applies to the Wu Hao form. YCF form is large predominantly, but a skilled practicioner can sneak in some small frame applications in eg. Lady works at shuttles.
The Wu chian form once was the same as the YCF. When the leaning was exaggerated it became the largest of the large frame forms.
Your teachers may have shrunk the way the postures are performed.
It is important to keep forms and applications distinct. Forms, in my opinion, are stylized, standardized, choreographed routines. They are good memory devices and vehicles for giving demonstrations. As well as being challenging to learn and fun to do. But, in essence, they usually are IMITATIONS of real application.
They even allow the inclusion of little symbolic gestures, little bits of flowery fists.
EG. modern wushu with its grand acrobatic skills and incredible speed so as to keep the audience spellbound has no martial application as such. Except to run into someone at high speed, but then a good T'ai chi person should know how to respond to all that momentum.
[This message has been edited by RonKreshmar (edited 05-17-2003).]
[This message has been edited by RonKreshmar (edited 05-17-2003).]