Modern condensed matter physics is concerned with systems of strongly correlated particles in an enormous variety of settings. These particles range from electrons in solids to biological cells, but a common theme is the emergence of complex collective behaviour. Some of the systems of interest are inherently quantum-coherent, while in soft and biological matter classical statistical descriptions apply.
Historically, quantum states of matter such as superconductors or ferromagnets have been classified using symmetry principles. Over the last decade the discovery of new types of matter, such as topological insulators and non-equilibrium steady states in cold atomic gases has made it clear that this classification is insufficient. The overarching theme of the work by John Chalker, Fabian Essler, Paul Fendley and Steve Simon is the characterisation and understanding of states of quantum matter that defy conventional classification themes. Ramin Golestanian, Ard Louis, and Julia Yeomans study the physics of living matter. They address current ideas surrounding various forms of active matter - such as cells and microorganisms - and discuss how these systems naturally provide a testing ground for theories of non-equilibrium statistical physics, as well as how evolution finds solutions in hyper-astronomically large search spaces to design living matter.