Phase separation is ubiquitous in systems far from equilibrium.

A far from exhaustive list of examples includes the clustering of self-propelled particles, vibrated granular materials, the formation of membraneless organelles within cells, chromatin organization in the nucleus, some types of ecological segregation, and social dynamics. 

Generic properties of phase separation, those that are independent of system details, can be understood in terms of minimal continuum models. This allowed us to discover that novel qualitative phenomenology, impossible in equilibrium systems, can arise in far from equilibrium phase-separating systems. These include several types of microphase-separation, states that resemble to steady-state foams, and ones in which a continuum flux of material persists in the steady state. 

Moreover, it is possible to generalize to non-equilibrium crucial concepts that allow to describe phase-separation, among which: what are and what is the role of interfacial tension(s), the Ostwald process, the dynamics of capillary waves, the theory of nucleation, the presence of hyper-uniformity during coarsening, and the critical properties of phase separating systems. 

In this talk, I will review theoretical works we have been developing in the last years to characterize the generic properties of phase-separating systems far from equilibrium.

Reference (review article): M.E. Cates, C. Nardini. "Active phase separation: new phenomenology from non-equilibrium physics." Reports on Progress in Physics 88.5 (2025): 056601.