Conductance anomalies in quantum point contacts and 1D wires

Over the last decade, interest in 1D charge transport has progressed from the seminal discovery of Landauer quantization of conductance, as a function of carrier density, to finerscale phenomena at the onset of quantization. This has come to be called the '0.7 anomaly', rather connoting a theoretical mystery of some profundity and universality, which remains open to date. Its somewhat imaginative appellation may tend to mislead, since the anomaly manifests itself over a range of conductance values: anywhere between 0.25-0.95 Landauer quanta. In this paper we offer a critique of the 0.7 anomaly and discuss the extent to which it represents a deep question of physics.