  The critical fluctuations at second order structural transitions in a bulk
crystal may affect the dissipation of mechanical probes even if completely
external to the crystal surface. Here we show that noncontact force microscope
dissipation bears clear evidence of the antiferrodistortive phase transition of
SrTiO3, known for a long time to exhibit a unique, extremely narrow neutron
scattering "central peak". The noncontact geometry suggests a central peak
linear response coupling connected with strain. The detailed temperature
dependence reveals for the first time the intrinsic central peak width of order
80 kHz, two orders of magnitude below the established neutron upper bound.
