"As a physicist/engineer..."
Me too, in fact my specialty was Vibration of Compressor and Turbine Blades in Jet Engines - I worked for Pratt & Whitney.
The "sports science" of piano technique is either lacking or highly guarded. (But maybe not - how much money is there in winning a piano competition? If the money is there like in pro sports, the tech will be there.)
I've just discovered Taubman (I'm 63, mostly self taught, ruined by the age of 10 by Finger-Method, yadda yadda...) and while it is so clear that rotation is important (I'm mesmerized by Lisitsa's hands), the explanation of it is very lacking in physics.
Yes, they are identifying the Rotation "Structural Mode" and illustrate its motion or Displacement. And it looks like a few are mentioning Stress which can be related to Force.
But what is really lacking is any mention of Inertia - especially of the forearm. I'll leave Inertia as a characteristic that needs much further investigation and explanation. And note that in slow speeds, inertia "terms" are negligible. But at high speeds, they dominate.
Any repetitive motion can be viewed as a Single Mass Oscillator: a Mass on the end of a Spring. (I think we can leave the Dampener out for now.)
At high speed we can have large inertial and restoring forces and yet they are invisible as far as displacement is concerned.
A high speed trill w/ and w/o rotation will look very similar, but if you could see the fraction of the force due to rotation, it would be a lot higher than what you can see (with the naked eye - slomo and precision mapping of motions would reveal what is actually going on.)
This part is OFF TOPIC, in that it is what lead me to think along these lines: fast octaves:
The very first question I asked myself for playing octaves is, What primary mode of the finger/wrist/forearm/arm is the fastest?
Obviously, the forearm up/down pivoting at elbow is not a fast one.
Nor is individual finger moving up and down either.
Wrist up/down is faster than the above. (So I thought this might be the basis of fast octaves.)
But wrist rotation is the fastest. (Can't see how this helps octaves though.)
But all of these motions are the various "Fundamental Modes" of portions of the complete arm system
But what about 2nd modes?
The forearm u/d is slow, but it's 2nd mode is much faster. In this mode when the arm goes down, the wrist goes up - it is a whip-like motion - something you would do if you were trying to shake something off your hand.
Could the forearm 2nd be faster than the wrist 1st for octaves? Beats me. But I'll bet you that mode shows up if you could measure the joint forces during fast play.
And yes, I also think Golandsky is hot(!)