The quantum criticality conundrum

It is well known theoretically that materials possessing distinct adjoining quantum phases at zero temperature can display behaviour that is universal and insensitive to microscopic details. This is the phenomenon of quantum criticality. Universality is, however, a central feature of the phases themselves and one essential to identifying them. Recent developments in the study of correlated-electron materials suggest that quantum criticality is present in these materials and has been masking the true nature of their phases. This raises troubling questions about the relation between theory and experiment in physics, as well as in science generally.