Do We Need the Ether of Polar Nanoregions?

This paper deals with possible experimental signatures of the so-called polar nanoregions in lead-based perovskite relaxors. It outlines both traditional and alternative approaches to these signatures. It is argued that the concept of polar nanoregions is useful but largely speculative. Polar nanoregions are compared with ferroelectric nanodomains. Qualitative explanation of the principal "relaxor" properties of PMN are discussed in both frameworks. It is argued that polarization as a vector may not be well defined at any nanometric region in PMN Crystal.