This argument seems quite clearly based on the assumption that the Euclidean u=2πr holds exactly. That means that at least spatial curvature has to be zero. So here something is assumed which is simply known to be wrong in GR.
Wrong thinking at best, continued malicious misrepresentation most likely. Any non-zero azimuthal 'strains' h_φφ, and meridian 'strains' h_θθ are self-contradictory on two levels at least, as stated clearly beginning in #1 (even though h_φφ, h_θθ nomenclature wasn't explicitly used there).
Firstly, each such spatial metric 'strain' separately would violate the explicitly purely transverse character supposedly applying.
Most bleeding obvious in the particular case of equatorial plane, where indeed only u=2πr fulfills GR GW solution requirement of 'purely transverse'. In TT gauge, which is what is typically applied to a local patch, this is obscured. Proper length of rulers and a bead array deform in unison. Once a global view is taken, on a coordinate basis where h_φφ, h_θθ have a direct application, there is simply no room for any necessarily axially symmetric, purely transverse, non-zero h_φφ 'strain'. Only by allowing radial 'breathing' - and such is not allowed within GR GW physical solution.
One wishes nevertheless to allow such radial 'breathing'? Then read again the passage in #94:
In #1 it was stated without proof, that nevertheless allowing radial expansion - contrary to GR GW's character - would have to have an radial displacement amplitude constant for all r, in order that transverse relative motions matched the necessary 1/r decline in transverse displacement between beads i.e circumferential expansion/contraction of metric. That is transverse metric strain h_φφ x r = K/r x r = K, a constant. An unphysical situation for any free-space wave. So desperate out - 'radial breathing' option is not an option.
Secondly, relaxing the pure transverse GR solution requirement and allowing radial motions i.e. longitudinal wave character, has the h_φφ, h_θθ 'strains' in mutual conflict. Since at a moment t when say h_φφ is +ve (outward 'breathing'), at that same location h_θθ is -ve (inward 'breathing'). Integrated over a spherical shell, there is literally nowhere net deformations of such strains could make sense. This is not QM - beads can't be in two places, and having conflicting motions, at once.
What's a poor bead to do? My advice to such a confused bead - ignore the stupid, impossible demands of the theory. Don't 'stress' as another disingenuous poster imagines is a relevant consideration.
The problem is essentially identical to that of considering what purely transverse mechanical strains are possible on a rigid thin spherical shell. Which matters were worked out in detail way back in the 1880's by Rayleigh and Love and others.
It was shown that only pure torsional modes, and linear combinations of such, can fulfill that requirement. If any of those workers were told that the GR GW 'purely transverse' 'pure shear' solutions, mapped on a coordinate basis to the mechanical counterpart, could qualify, they would justly laugh such a claim out of the room.
I have tried to clarify if this is indeed assumed, but Q-reeus refuses to answer my questions about this. But if u≠2πr, why hφφ cannot be non-zero?
See above. Go to coordinate basis, not proper TT-gauge basis, and try and argue your non-zero h_φφ, or h_θθ for that matter, makes any sense.
And here is the real 'ultimate challenge' no-one has been game to attempt. My very first reference in #1 - Feynman's famous beads on a stick.
No pretense now that scenario as per
https://s26.postimg.org/axee7pdmh/GR_GW_paradox_2.png is 'incomprehensible'.
If I have somehow misunderstood the situation, and Feynman had it right, here's what to do to settle it.
Just take a straight plan view of linear oscillator case, a single slice through equatorial plane. So oscillator axis is perpendicular to page/screen. A billion Feynman's each holding their locally straight stick tangent to the r >> λ, far-field equator line, are distributed uniformly around that equator line. As are the beads on those sticks. The sticks are touching end to end and ever so slightly curved so as to form a huge, perfectly circular hoop overall, centred about oscillator axis. (Yes, this is essentially a repeat of what was in #1)
Show that beads moving azimuthally along those sticks is logically coherent.
Post it here, with diagram, this thread. That would be end of story. Something that should have happened back around post #2 - if it were possible. So let's see who will finally bite. I predict no-one will.