  Using a high-sensitivity torsional oscillator technique, we mapped the
rotational and relaxational dynamics of solid helium-4 throughout the parameter
range of the proposed supersolidity. We found evidence that the same
microscopic excitations controlling the torsional oscillator motions are
generated independently by thermal and mechanical stimulation. Moreover, a
measure for the relaxation times of these excitations diverges smoothly without
any indication for a critical temperature or critical velocity of a supersolid
transition. Finally, we demonstrated that the combined temperature-velocity
dependence of the TO response is indistinguishable from the combined
temperature-strain dependence of the solid's shear modulus. This implies that
the rotational responses of solid helium-4 attributed to supersolidity are
associated with generation of the same microscopic excitations as those
produced by direct shear strain.
