case 1: in the frame of A, A and B are not symmetric.
case 2: in the frame of B, A and B are not symmetric.
but in the more outer loop, case 1 and case 2 are completely symmetric.
so, any unsymmetric prediction is wrong. any theory predicts wrong prediction is fundamentally flawed...
twin paradox alone kills special relativity:
the story:
A stays on the planet, B round-travels by spaceship;
when back, based on spectral relativity, B youngs.
analysis:
when special relativity is be applied, the property difference between planet and spaceship is never used; so...