Nano-scale intrinsic inhomogeneity in the cuprates

The possibility that nano-scale electronic inhomogeneity is intrinsic in the high-temperature superconducting cuprates has been suspected from many experiments, and recent STM observations enhanced this view. However, the subject is still highly controversial, particularly with respect to its relevance to the mechanism of superconductivity. We present recent results of inelastic neutron scattering measurement that support the intrinsic nature of inhomogeneity and discuss its implications.