  Extant proofs of the spin-statistics connection (SSC) are kinematical. C S
Unnikrishnan has suggested that a dynamical interaction leading to the SSC
would involve spin and perforce gravity, the only known universal force. For
the scattering of two identical particles, he considers [arXiv: gr-qc/0406043]
the interaction of their spins with the gravito-magnetic field generated by
their scattering motion through cosmic matter-energy. There the direct and
particles-exchanged scattering amplitudes accumulate different quantum phases
which provide the relevant bosonic/fermionic sign between them without applying
the ad hoc SSC rule. Here it is shown that the scattering probabilities given
by the standard implementation of SSC in quantum mechanics are actually not
obtained from the above interaction for most initial spin states of the
scattering particles. Instead, an unrealized peculiar dynamical interaction is
required. Further, a spin-gravito-magnetic interaction as above (with caveats)
would result in a large unmeasured spin-orbit coupling type effect on atomic
energy levels. A comparison with a typical rotation based proof is also
provided.
